Adhesive label

Abstract

To provide an adhesive label which allows a printed portion to be peeled off using warm water and offers good adhesion of a base material.SOLUTION: An adhesion label is provided comprising a release coating layer, a base material, and an adhesive layer arranged in this order, the release coating layer containing a polyester resin and a water-soluble polymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive label. [Background technology]

[0002] In recent years, recycling of empty containers has been attracting attention due to environmental considerations.

[0003] For example, in the material recycling of polyester-based containers (such as polyethylene terephthalate (PET) bottles), after collecting used containers, they are crushed, washed, and dried to form flakes, which are then heated and melted to form pellets, and the resulting recycled resin is used as the material for polyester-based containers.

[0004] Typically, containers have adhesive labels (also referred to as labels) affixed to their surfaces with various pieces of information. When polyester-based containers are recycled, if the label's substrate and adhesive are not compatible with the resin that makes up the polyester-based container, the substrate and adhesive that make up the label act as foreign matter, resulting in a problem of reduced mechanical properties of the recycled resin. For this reason, adhesive labels are typically removed from polyester-based containers for material recycling.

[0005] Furthermore, in the recycling of glass containers such as beer bottles, after use, the adhesive labels are removed from the containers, and the containers are then washed and reused.

[0006] In this regard, for example, Patent Document 1 below describes that by using a polyester resin substrate and a polyester adhesive layer that are compatible with the polyester container to be adhered, it is possible to recycle molded products such as PET bottles without removing the label. Even in this case, the printed portion on the adhesive label becomes an impurity when the polyester container is recycled, so the printed portion has been removed by washing and immersing in an alkaline aqueous solution, by providing a coating layer that is peelable from the substrate and has printability. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-10489 Summary of the Invention [Problem to be solved by the invention]

[0008] As mentioned above, even when recycling containers by peeling off adhesive labels from containers, there is a demand for recycling the peeled off labels separately. In this case, the printed portion becomes an impurity, so it is still necessary to remove the printed portion from the label. When removing the printed portion from the adhesive label, it is possible to use a coating layer as described in Patent Document 1, but this requires the use of an alkaline aqueous solution. However, if an alkaline aqueous solution must be used to remove the printed portion, special equipment is required, which makes this method less versatile.

[0009] On the other hand, when a coating layer is used to peel off the printed portion, the coating layer must adhere sufficiently to the underlying substrate.

[0010] The present invention has been invented to solve the above-mentioned problems, and aims to provide an adhesive label that allows the printed portion to be detached (peeled off) without using an alkaline aqueous solution and has good adhesion to the substrate. [Means for solving the problem]

[0011] In order to achieve the above object, an adhesive label according to the present invention is an adhesive label having a release coating layer, a substrate, and an adhesive layer in this order, wherein the release coating layer contains a polyester resin and a water-soluble polymer. [Effects of the Invention]

[0012] The adhesive label of the present invention has excellent adhesion to the substrate, and the printed portion can be removed from the adhesive label with warm water without using an alkaline aqueous solution. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view illustrating a pressure-sensitive adhesive label according to an embodiment of the present invention. [Figure 2] FIG. 10 is a cross-sectional view illustrating a pressure-sensitive adhesive label according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional proportions in the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.

[0015] In this specification, the range "X to Y" means "X or more and Y or less." Unless otherwise specified, operations and measurements of physical properties are carried out under conditions of room temperature (20 to 25°C) and a relative humidity of 45 to 55% RH.

[0016] The adhesive label is attached to a glass container such as a glass bottle or a polyester container such as a polyethylene terephthalate (PET) bottle. The shape of the adhesive label is not particularly limited, but is generally rectangular when viewed from the stacking direction. The shape of the adhesive label may also be triangular or circular. The adhesive layer is disposed, for example, on the entire surface of the substrate.

[0017] The structure of the adhesive label will be described below with reference to FIG.

[0018] FIG. 1 is a cross-sectional schematic diagram of an adhesive label 10 according to one embodiment. As shown in FIG. 1, the adhesive label 10 according to the embodiment of the present invention has, from top to bottom, a printed portion 13, a release coating layer 14, a substrate 16, an adhesive layer 15, and a release liner 30. The release liner 30 is composed of a release agent layer 12 and a release substrate 11 arranged in this order. The release coating layer 14 decomposes and dissolves when it comes into contact with warm water, causing the printed portion 13 to detach (peel) from the adhesive label 10 (the release coating layer 14 has releasability from the adhesive label). As a result, the detached printed portion 13 floats on the surface, making it easy to collect. The adhesive label 10 may have other functional layers, such as a primer layer, between the layers or on the surface.

[0019] FIG. 2 is a cross-sectional schematic diagram of an adhesive label 20 according to another embodiment. The adhesive label 20 has a printing coating layer 17 between the printing portion 13 and the release coating layer 14 of the adhesive label 10. That is, the printing coating layer 17 is provided on the release coating layer 14 facing the substrate 16. The printing portion 13 is disposed on the surface of the adhesive label. The printing coating layer 17 preferably has a property of not dissolving but remaining as a resin when the release coating layer is peeled off. With such a property, the printing coating layer 17 is detached in the form of a film together with the upper printing portion 13. In other words, the printing portion 13 does not break down into small pieces and maintains a certain size, making it easy to collect. Here, "on the release coating layer" does not only mean that the release coating layer 14 and the printing coating layer 17 are adjacent to each other, but also means that another layer (not shown) may exist between the release coating layer 14 and the printing coating layer 17. A preferred embodiment is that the release coating layer 14 and the printing coating layer 17 are adjacent to each other.

[0020] Furthermore, a preferred embodiment has no other release coating layer between the substrate 16 and the adhesive layer 15. In one preferred embodiment, the substrate 16 and the adhesive layer 15 are adjacent to each other. Since there is no other release coating layer between the substrate 16 and the adhesive layer 15 and the release coating layer 14 is present between the substrate 16 and the printed portion 13 or between the substrate 16 and the printing coating layer 17, when the adhesive label 10 (20) is recycled while still attached to a PET bottle (polyester container), the substrate 16 does not peel off from the polyester container (adherend) when brought into contact with warm water, and the adhesive layer 15 and the substrate 16 remain attached to the polyester container. Therefore, both the substrate 16 and the adhesive layer 15 can be recycled at the same time.

[0021] If the adhesive label 10 (20) is not recycled together with the container, the adhesive label 10 (20) is peeled off from the container, and then the label is brought into contact with warm water in the same manner as above to remove the printed portion 13 (and the printing coating layer 17), and then the recycling process is carried out.

[0022] The concept of "label" includes what are called films, sheets, tapes, etc.

[0023] Each component will be described below.

[0024] <Print section> The printed portion 13 is a layer for displaying information, and is an optional layer in the present invention. There are no particular limitations on how the printed portion 13 is formed, and it can be formed by, for example, flexographic printing, offset printing, letterpress printing, gravure printing, screen printing, thermal transfer printing, or the like.

[0025] The information displayed on the printed portion may be, for example, letters, numbers, symbols, illustrations, photographs, graphs, or a combination thereof.

[0026] <Printing coating layer> The printing coating layer 17 is a layer disposed below the printed portion 13, and preferably does not dissolve when the detachment coating layer is peeled off, but remains as resin, so that the printed portion 13 is detached in the form of a film, which facilitates recovery of the printed portion 13. For this reason, the printing coating layer 17 is preferably disposed on the printing surface.

[0027] The printing coating layer 17 is mainly composed of a resin. Here, "main component" refers to a resin that accounts for 60% by mass or more (upper limit 100% by mass) of the printing coating layer 17. The resin that constitutes the printing coating layer is preferably water-insoluble so that it maintains its shape when the detachment coating layer is detached. Here, "water-insoluble" refers to a solubility in water at 70°C of 20% by mass or less (lower limit 0% by mass), preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 1% by mass or less.

[0028] Examples of resins that can be used to form the printing coating layer 17 include urethane-modified polyester resins, acrylic acid ester (co)polymers, epoxy resins, and polyamide resins. These resins can be used alone or in combination of two or more. Among these, urethane-modified polyester resins are preferred as the resin that can provide high printing adhesion. Furthermore, the resin that forms the printing coating layer 17 preferably has an acid value of 3 KOHmg / g or less, and more preferably 2 KOHmg / g or less, in order to reduce solubility in water. Polyester-based resins can also be used to form the printing coating layer 17 as long as the acid value is within the above range.

[0029] Specific examples of urethane-modified polyester resins include polymers (polyester urethanes) obtained by reacting various polyisocyanate compounds with polyester polyols having hydroxyl groups at the terminals of polymers obtained by condensation polymerization of polyols and carboxylic acid components.

[0030] Examples of the polyisocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate.

[0031] The number average molecular weight (Mn) of the urethane-modified polyester resin is preferably 2,000 or more and 100,000 or less, and more preferably 5,000 or more and 50,000 or less, where Mn is the number average molecular weight measured by gel permeation chromatography (GPC) and converted into polystyrene.

[0032] The glass transition temperature of the urethane-modified polyester resin is, for example, preferably 100°C or lower, and more preferably -40°C or higher and 100°C or lower.

[0033] The urethane-modified polyester resin may be a commercially available product, and examples of commercially available products include the Vylon series (trade name) manufactured by Toyobo MC Co., Ltd., and preferably used are Vylon UR-1400 (acid value <1, hydroxyl value 2 to 3, number average molecular weight 40,000, Tg 83°C), UR-8300 (acid value <1, hydroxyl value 3 to 4, number average molecular weight 30,000, Tg 23°C), and UR-6100 (acid value <1, hydroxyl groups 4 to 6, number average molecular weight 25,000, Tg -30°C).

[0034] The resin content in the printing coating layer 17 is preferably 80% by mass or more and 100% by mass or less, and more preferably 90% by mass or more and 100% by mass or less.

[0035] The resin contained in the printing coating layer 17 is preferably a crosslinked product. A crosslinked resin is preferred because it further reduces its solubility in water. To make the resin a crosslinked product, a crosslinking agent may be added to the printing coating layer forming composition for forming the printing coating layer 17, as described below. In this case, a crosslinking agent that reacts with the crosslinkable reactive groups in the resin is appropriately selected.

[0036] Examples of crosslinking agents that can react with crosslinkable reactive groups (preferably carboxyl groups and / or hydroxyl groups) include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, and metal chelate-based crosslinking agents.

[0037] Isocyanate crosslinking agents include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methylcaprate, lysine diisocyanate, lysine ester triisocyanate, and 1,6,11-undecane triisocyanate. diisocyanate compounds such as aliphatic diisocyanates such as 1,3,6-hexamethylene triisocyanate, trimethylhexamethylene diisocyanate, and decamethylene diisocyanate; aromatic diisocyanates such as tolylene diisocyanate and xylylene diisocyanate; and alicyclic diisocyanates such as isophorone diisocyanate; as well as isocyanate derivatives such as adducts of diisocyanate compounds and polyol compounds such as trimethylolpropane, biuret and isocyanurate diisocyanate compounds, and bifunctional diisocyanate compounds.

[0038] Examples of epoxy crosslinking agents include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine.

[0039] Examples of the aziridine crosslinking agent include diphenylmethane-4,4'-bis(1-aziridinecarboxamide), trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethane tri-β-aziridinylpropionate, toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, bisisophthaloyl-1-(2-methylaziridine), tris-1-(2-methylaziridine)phosphine, and trimethylolpropane tri-β-(2-methylaziridine)propionate.

[0040] Metal chelate crosslinking agents include chelate compounds whose metal atoms are aluminum, zirconium, titanium, zinc, iron, tin, etc. Examples of aluminum chelate compounds include diisopropoxyaluminum monooleyl acetoacetate, monoisopropoxyaluminum bisoleyl acetoacetate, monoisopropoxyaluminum monooleate monoethyl acetoacetate, diisopropoxyaluminum monolauryl acetoacetate, diisopropoxyaluminum monostearyl acetoacetate, and diisopropoxyaluminum monoisostearyl acetoacetate.

[0041] Among these, it is preferable that the crosslinking agent is an isocyanate-based crosslinking agent, since high print adhesion can be obtained in the coating layer after crosslinking.

[0042] The above crosslinking agents may be used alone or in combination of two or more.

[0043] The amount of crosslinking agent added is set appropriately taking into consideration the amount of crosslinkable reactive groups in the resin, etc., but is preferably 0.01 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the resin.

[0044] Considering the ease of recovery of the printed portion 13 and thinness, the thickness of the printing coating layer 17 is preferably 0.05 μm or more and 1 μm or less, and more preferably 0.05 μm or more and 0.5 μm or less.

[0045] The printing coating layer 17 may contain additives such as a catalyst, an ultraviolet absorber, a pigment, and a filler.

[0046] <Detachable Coating Layer> The release coating layer 14 contains a polyester resin and a water-soluble polymer.

[0047] From the viewpoint of deinking ability (ability to remove printing ink) when immersed in water, the thickness of the release coating layer is preferably 0.01 μm or more and 3 μm or less, more preferably 0.03 μm or more and 1 μm or less, and even more preferably 0.05 μm or more and 0.5 μm or less.

[0048] (Polyester resin) The polyester resin is not particularly limited, but is preferably a water-based polyester resin from the viewpoint of compatibility with the water-soluble polymer.

[0049] "Aqueous polyester resin" refers to a polyester resin that can be dissolved in an aqueous solvent to form an aqueous solution, or a polyester resin that can be dispersed as an emulsion in an aqueous solvent to form an aqueous dispersion. The use of such an "aqueous" polyester resin makes it possible to reduce the amount of volatile organic compounds emitted during coating. Here, the aqueous solvent refers to water and / or an aqueous organic solvent, and preferably contains 60% by mass or more (up to 100% by mass), more preferably 70% by mass or more, even more preferably 85% by mass or more, and most preferably 90% by mass or more of water.

[0050] Examples of aqueous organic solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, dimethylformamide, methyl cellosolve, butyl cellosolve, tetrahydrofuran, ethylene glycol mono-t-butyl ether (ETB), etc. These aqueous organic solvents may be used alone or in combination of two or more.

[0051] In one embodiment of the present invention, in order to prepare an aqueous dispersion in which the aqueous polyester resin is dispersed as an emulsion in water, a small amount of an emulsifier, a surfactant, or the like may be used within a range that does not impair the effects of the present invention.

[0052] However, low-molecular-weight components such as emulsifiers and surfactants may be localized in the release coating layer, resulting in reduced adhesion and possibly reduced interlayer adhesion. From the viewpoint of suppressing this phenomenon, in one embodiment of the present invention, the aqueous polyester resin is preferably a self-emulsifying aqueous polyester resin.

[0053] If the resin is a self-emulsifying aqueous polyester resin, it is possible to form an emulsion without using low-molecular-weight components such as emulsifiers or surfactants, which cause a decrease in interlayer adhesion, and therefore the interlayer adhesion of the resulting PSA sheet can be further improved. Note that "self-emulsifying" means, for example, that some kind of hydrophilic group is chemically introduced into the resin skeleton, and the resin itself has emulsifying ability, without the need to add an emulsifier or surfactant.

[0054] In a preferred embodiment of the present invention, the aqueous polyester resin has a hydroxyl value of 3 KOH mg / g or more and / or an acid value of 10 KOH mg / g or more. In this embodiment, hydrophilic groups are appropriately introduced, making it easier to make the aqueous polyester resin self-emulsifying. The hydroxyl value of the aqueous polyester resin may be 50 KOH mg / g or less, 30 KOH mg / g or less, 20 KOH mg / g or less, or 10 KOH mg / g or less. The acid value of the aqueous polyester resin may be 200 KOH mg / g or less, or 100 KOH mg / g or less. In this specification, the hydroxyl value / acid value of the aqueous polyester resin is a value measured in accordance with JIS K 0070:1992.

[0055] The glass transition temperature (Tg) of the aqueous polyester resin used in one embodiment of the present invention is preferably 0°C or higher and 70°C or lower, more preferably 10°C or higher and 65°C or lower, and may be 20°C or higher and 65°C or lower, or 30°C or higher and 65°C or lower. When the glass transition temperature (Tg) of the aqueous polyester resin is within the above range, the blocking resistance of the pressure-sensitive adhesive label 10 (20) is improved, and as a result, the printability is improved. Furthermore, when the glass transition temperature (Tg) of the aqueous polyester resin is within the above range, the deinking ability of the release coating layer 14 is improved.

[0056] In this specification, the glass transition temperature (Tg) of the aqueous polyester resin is a value measured in accordance with JIS K 7121:2012, and specifically, a value measured based on the method described below.

[0057] From the viewpoint of improving solubility or dispersibility in water, the number average molecular weight (Mn) of the aqueous polyester resin is preferably 1,000 to 50,000, more preferably 1,500 to 30,000, and even more preferably 2,000 to 25,000. If the Mn of the aqueous polyester resin is in such a range where the molecular weight is relatively low, the solubility and dispersibility in water will be sufficiently high, and deinking properties will be better, which is preferable.

[0058] In the present invention, the number average molecular weight (Mn) is a value calculated as a standard polystyrene as measured by gel permeation chromatography (GPC), and specifically, for example, is a value measured based on the method described below.

[0059] (1) Number average molecular weight (Mn) Measurements are carried out using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name "HLC-8020") under the conditions below, and the values ​​measured are converted into standard polystyrene equivalents. Columns: "TSK guard column HXL-H", "TSK gel GMHXL (x2)", "TSK gel G2000HXL" (all manufactured by Tosoh Corporation) Column temperature: 40℃ Developing solvent: tetrahydrofuran ·Flow rate: 1.0mL / min. (2) Glass transition temperature (Tg) Measurements are performed in accordance with JIS K 7121:2012 using a differential scanning calorimeter (manufactured by TA Instruments Japan, product name "DSC Q2000") at a heating rate of 20°C / min.

[0060] Examples of polyester resins include copolymers obtained by polycondensation of an alcohol component and a carboxylic acid component, and modified products of such copolymers.

[0061] As the alcohol component, a polyhydric alcohol having two or more hydroxyl groups in one molecule can be used.

[0062] Specific examples of the alcohol component include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, and hydroxypivalic acid neopentyl glycol ester. Examples of suitable alcohol components include polylactone diols obtained by adding lactones such as ε-caprolactone to these glycols, polyester diols such as bis(hydroxyethyl) terephthalate, dihydric cyclic alcohols such as 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, spiroglycol, and dihydroxymethyltricyclodecane, ethylene oxide and propylene oxide adducts of bisphenol A, and trihydric or higher polyhydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, and mannitol. These alcohol components may be used alone or in combination of two or more.

[0063] As the carboxylic acid component, a polybasic acid having two or more carboxyl groups in one molecule can be used.

[0064] Specific examples of the carboxylic acid component include dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, HET acid, maleic acid, fumaric acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, and methylhexahydrophthalic acid. tricarboxylic acids and their anhydrides, such as trimellitic acid, pyromellitic acid, trimesic acid, methylcyclohexene tricarboxylic acid, hexahydrotrimellitic acid, and tetrachlorohexene tricarboxylic acid; and tetracarboxylic acids and their anhydrides, such as 1,2,4,5-cyclohexanetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, and pyromellitic acid. These carboxylic acid components may be used alone or in combination of two or more.

[0065] The aqueous polyester resin used in one embodiment of the present invention may have a structural unit derived from a polybasic acid having three or more carboxyl groups in one molecule, or may have a structural unit derived from a tricarboxylic acid or an anhydride of a tricarboxylic acid, from the viewpoint of adjusting the acid value within the above range.

[0066] From the viewpoint of substrate adhesion and releasability, the content of the polyester resin in the release coating layer is preferably 20% by mass or more and 95% by mass or less, and may be 25% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 85% by mass or less, even more preferably 35% by mass or more and 85% by mass or less, even more preferably 55% by mass or more and 80% by mass or less, and particularly preferably 60% by mass or more and 80% by mass or less.

[0067] The content of the polyester resin relative to the total content of the polyester resin and the water-soluble polymer may be 20% by mass or more, or 25% by mass or more, preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 55% by mass or more, and particularly preferably 60% by mass or more, from the viewpoint of substrate adhesion (particularly substrate adhesion to a polyester resin substrate). Also, the content of the polyester resin relative to the total content of the polyester resin and the water-soluble polymer may be 95% by mass or less, or 90% by mass or less, preferably 85% by mass or less, and more preferably 80% by mass or less, from the viewpoint of release property. The content of the polyester resin relative to the total content of the polyester resin and the water-soluble polymer is preferably 20% by mass or more and 95% by mass or less, 25% by mass or more and 90% by mass or less, 30% by mass or more and 85% by mass or less, 40% by mass or more and 85% by mass or less, 50% by mass or more and 85% by mass or less, 55% by mass or more and 85% by mass or less, or 60% by mass or more and 80% by mass or less.

[0068] (Water-soluble polymer) Examples of water-soluble polymers include polyvinyl alcohol-based resins, polyalkylene glycol-based resins such as polyethylene glycol and polypropylene glycol, polyacrylamide, sodium polyacrylate, polyvinylpyrrolidone, cellulose-based resins such as acetyl cellulose, acetyl butyl cellulose, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose, starch, dextrin, gelatin, glue, sodium alginate, etc. Among these, in consideration of substrate adhesion, it is more preferable that the water-soluble polymer contains a polyvinyl alcohol-based resin and / or a polyalkylene glycol-based resin.

[0069] Polyvinyl alcohol resins include not only ordinary polyvinyl alcohol (unmodified polyvinyl alcohol) obtained by hydrolysis of polyvinyl acetate, but also modified polyvinyl alcohol. Examples of modified polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, and nonion-modified polyvinyl alcohol. Among these, the polyvinyl alcohol resin is preferably ordinary polyvinyl alcohol (unmodified polyvinyl alcohol) obtained by hydrolysis of polyvinyl acetate.

[0070] From the viewpoint of the effects of the present invention, the degree of polymerization of polyvinyl alcohol is preferably from 100 to 5000, more preferably from 200 to 2500, even more preferably from 200 to 1500, still more preferably from 200 to 1000, and may be from 200 to 800, from 200 to 600, or from 200 to 400. The "degree of polymerization of polyvinyl alcohol" refers to a value measured by a method in accordance with the "average degree of polymerization" described in JIS K 6726:1994.

[0071] The saponification degree of polyvinyl alcohol is preferably 65 to 100 mol%, and may be 65 to 95 mol%, or 85 to 95 mol%. The "saponification degree of polyvinyl alcohol" refers to a value measured by a method in accordance with the "saponification degree" described in JIS K 6726:1994.

[0072] Examples of polyalkylene glycol resins include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexamethylene glycol, block or random copolymers of ethylene oxide and propylene oxide, and block or random copolymers of ethylene oxide and tetrahydrofuran. Among these, polyethylene glycol is preferred as the polyalkylene glycol resin. From the viewpoint of elimination properties, the molecular weight of the polyalkylene glycol resin is preferably, for example, 100 or more and 20,000 or less, and more preferably 500 or more and 10,000 or less.

[0073] The content of the water-soluble polymer in the detachment coating layer is preferably 5% by mass or more and 80% by mass or less, and may be 10% by mass or more and 75% by mass or less, more preferably 15% by mass or more and 70% by mass or less, even more preferably 15% by mass or more and 65% by mass or less, even more preferably 15% by mass or more and 55% by mass or less, and particularly preferably 20% by mass or more and 40% by mass or less.

[0074] (particle) The release coating layer may contain particles for the purpose of improving the blocking resistance between films when rolled.

[0075] The particles may be either inorganic or organic. Examples of inorganic particles include zirconia, silica, titanium dioxide, kaolin, alumina, titania, zeolite, calcium carbonate, barium sulfate, magnesium hydroxide, calcium phosphate, glass, mica, and talc. Examples of organic particles include acrylic resin particles such as polymethyl methacrylate, polystyrene particles, styrene-acrylic resin particles, and polycarbonate particles. These particles may be used alone or in combination of two or more. Among these, silica particles are preferred.

[0076] The content of particles in the release coating layer is appropriately set to achieve the desired purpose (for example, improving blocking resistance), and is, for example, 0.1 to 10 parts by mass per 100 parts by mass of the aqueous polyester resin.

[0077] The average particle size of the particles is appropriately set taking into consideration the desired purpose, but for example, for the purpose of improving blocking resistance, it is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.3 μm or more and 0.6 μm or less. In this specification, unless otherwise specified, the average particle size refers to the average particle size on a volume basis, and can be determined, for example, by measuring a particle dispersion with a Coulter Counter particle size distribution analyzer (TA-II model manufactured by COULTER ELECTRONICS INC.) using a 50 μm aperture.

[0078] (general-purpose additives, other resin components) The release coating layer may contain general-purpose additives such as surfactants in addition to the polyester resin and particles described above, as long as the effects of the present invention are not impaired.

[0079] <Base material> The substrate 16 is not particularly limited, and examples thereof include synthetic paper having an internal cavity, polyolefin resins such as polyethylene, polypropylene, and various olefin copolymers, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polystyrene resins, polyvinyl chloride resins, acrylic resins, polycarbonate resins, polyamide resins, and fluorine-based resins such as polytetrafluoroethylene, and films made from mixtures or laminates of these resins. The material of the substrate can be selected appropriately, and depending on the relationship between the material of the container to which the adhesive label 10 (20) is affixed and the material of the substrate, it is possible to choose to recycle the label either while it is attached to the container or after it has been peeled off.

[0080] In this case, when the adhesive label 10 (20) is recycled together with the container (i.e., when the adhesive label 10 (20) is recycled with the adhesive label 10 (20) still attached), it is preferable to use the same material that is compatible with the container to be adhered. For example, when the adhesive label 10 (20) is used by attaching it to a PET bottle, it is preferable that the substrate used for the substrate 16 is a polyester-based resin substrate. In terms of the quality of the recycled resin, such as the mechanical properties, it is particularly advantageous to use a polyester-based film resin substrate whose composition is close to that of the resin used in the PET bottle.

[0081] Examples of resin substrates used in polyester-based films include polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. One or more of these may be appropriately selected and used depending on the type of resin used in the PET bottle to be adhered, so as to obtain a resin substrate that is compatible with the resin.

[0082] Here, compatibility means that the material melts at the temperature at which PET bottles are heated and melted, is well mixed with the resin substrate of the melted PET bottle, and does not degrade the properties of the recycled product. When the resin substrate of a PET bottle is a mixture of two or more compatible resins, one of the resins in the mixture that makes up the PET bottle can be used as the resin for the resin substrate. Similarly, when the container is made of a resin other than polyester resin, a resin can be appropriately selected to obtain a resin substrate that is compatible with the type of resin used.

[0083] The thickness of the substrate 16 is not particularly limited and is selected appropriately depending on the application, but is generally preferably in the range of 25 to 100 μm. When attaching the adhesive label 10 (20) to a container, a labeling process may be performed in which the adhesive label 10 (20) is attached to the container using a labeling device, from the viewpoint of production efficiency. By making the thickness of the substrate 16 25 μm or more, the adhesive label 10 (20) can be easily released from the release liner 30 during the labeling process. Furthermore, by making the thickness of the substrate 16 100 μm or less, the roll length installed in the labeling device can be sufficiently long, reducing the frequency of roll replacement and improving work efficiency. The substrate 16 may be obtained by any conventional film-forming method, such as an extrusion method, a calendar method, a solution coating method, or a casting method.

[0084] In the present invention, one or both sides of the substrate 16 may be subjected to a surface treatment as desired in order to improve adhesion to a coating layer provided thereon or to the pressure-sensitive adhesive layer 15 provided on the opposite side. Examples of such surface treatment methods include surface roughening treatments such as sandblasting or solvent treatment, or surface oxidation treatments such as corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, and ozone / ultraviolet irradiation treatment.

[0085] <Adhesive layer> Next, the adhesive layer 15 will be described. The adhesive used in the adhesive layer 15 can be appropriately selected from those commonly used as adhesives for conventional labels, and examples thereof include acrylic adhesives, rubber adhesives, silicone adhesives, polyurethane adhesives, and polyester adhesives. As with the substrate 16, the composition of the adhesive can also be appropriately selected depending on the material of the container to which the adhesive label 10 (20) is attached, and this allows the label to be recycled either while still attached to the container or after being peeled off.

[0086] As with the substrate 16, when the adhesive label 10 (20) is recycled together with the container, the adhesive layer 15 is preferably formed from a material that is highly compatible with the container. For example, when the adhesive label 10 (20) is used by being attached to a PET bottle, the adhesive layer 15 preferably contains a polyester-based adhesive. Specifically, the adhesive layer 15 is preferably formed from an adhesive composition containing a polyester-based resin (A) as a main component.

[0087] The polyester resin (A) can be obtained by copolymerizing copolymerization components containing a polycarboxylic acid component (A1) and a polyol component (A2) as constituent raw materials.

[0088] [Polycarboxylic acid component (A1)] Examples of the polycarboxylic acid component (A1) used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, benzylmalonic acid, diphenic acid, 4,4'-oxydibenzoic acid, and naphthalenedicarboxylic acid; aliphatic dicarboxylic acids such as malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, thiodipropionic acid, and diglycolic acid; and alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, and adamantanedicarboxylic acid. These may be used alone or in combination of two or more.

[0089] Among these, it is preferable to contain an aromatic dicarboxylic acid in order to impart cohesive strength.

[0090] [Polyol component (A2)] Examples of the polyol component (A2) used in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2 and dihydric alcohols such as aliphatic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; and aromatic diols such as 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m-, and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and their ethylene oxide and propylene oxide adducts. These may be used alone or in combination of two or more.

[0091] Among these, aliphatic diols and alicyclic diols are preferred because of their excellent reactivity. Particularly preferred aliphatic diols include ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol, and particularly preferred alicyclic diols include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol.

[0092] The blending ratio of the polycarboxylic acid component (A1) to the polyol component (A2) is preferably 1 to 2 equivalents, particularly preferably 1.1 to 1.7 equivalents, of the polyol component (A2) per equivalent of the polycarboxylic acid component (A1). If the content of the polyol component (A2) is too low, the acid value tends to increase, making it difficult to achieve a high molecular weight, while if it is too high, the yield tends to decrease.

[0093] The polyester resin (A) is produced by arbitrarily selecting the polycarboxylic acid component (A1) and the polyol component (A2) and subjecting them to a polycondensation reaction in the presence of a catalyst by a known method.

[0094] The number average molecular weight of the polyester resin (A) used in the present invention is preferably 5,000 to 100,000, more preferably 10,000 to 100,000, and even more preferably 15,000 to 80,000, from the viewpoints of cohesive strength, heat resistance, mechanical strength, adhesiveness, etc.

[0095] The number average molecular weight is the number average molecular weight converted into the molecular weight of standard polystyrene, and is measured by using a high performance liquid chromatography (manufactured by Tosoh Corporation, "HLC-8220 GPC") with two TSK gel GMHXL columns in series.

[0096] Typically, the polyester resin (A) is crosslinked using a crosslinking agent to provide excellent cohesive strength and exhibit excellent performance as a pressure-sensitive adhesive. Examples of such crosslinking agents include polyisocyanate compounds (isocyanate crosslinking agents) and polyepoxy compounds, which have functional groups that react with the hydroxyl and / or carboxyl groups contained in the polyester resin (A). Among these, polyisocyanate compounds are particularly preferred because they can achieve a good balance between initial adhesion, mechanical strength, and heat resistance.

[0097] Examples of such polyisocyanate compounds include polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate, as well as isocyanate adducts such as a tolylene diisocyanate adduct of trimethylolpropane, a hexamethylene diisocyanate adduct, and an isophorone diisocyanate adduct. The above polyisocyanate compounds may also be used in which the isocyanate moiety is blocked with phenol, lactam, or the like. These crosslinking agents may be used alone or in combination of two or more.

[0098] The amount of the crosslinking agent to be added can be appropriately selected depending on the molecular weight of the polyester resin (A) and the intended use, but in general, taking into consideration adhesiveness and the like, it is preferable to add 0.5 to 5 parts by mass per 100 parts by mass of the polyester resin (A).

[0099] The pressure-sensitive adhesive layer may contain conventionally known additives such as hydrolysis inhibitors, softeners, ultraviolet absorbers, stabilizers, antistatic agents, and tackifiers, as well as other powdery or particulate additives such as inorganic or organic fillers, metal powders, and pigments, within the scope of not impairing the effects of the present invention.

[0100] The thickness of the pressure-sensitive adhesive layer is not particularly limited, but may be, for example, 5 to 100 μm, or 10 to 50 μm.

[0101] <Release liner 30> As shown in Figure 1, release liner 30 has release substrate 11 and release agent layer 12. Release liner 30 is an optional component that has the function of protecting pressure-sensitive adhesive layer 15 and preventing a decrease in adhesiveness until it is attached to an adherend.

[0102] The material of the release substrate 11 is not particularly limited, and known materials can be used. Examples include resin materials and paper. Examples of resin materials include polyester and polyolefin. Examples of paper include high-quality paper, glassine paper, and laminated paper laminated with a thermoplastic resin such as polyethylene.

[0103] The thickness of the release liner 30 is preferably 25 μm or more and 100 μm or less. By making the thickness of the release liner 30 25 μm or more, the adhesive label 10 (20) has excellent suitability for punching. Furthermore, by making the thickness of the release liner 30 100 μm or less, the release liner 30 has excellent releasability from the adhesive layer 15 during the labeling process.

[0104] Examples of the release agent constituting the release agent layer 12 include silicone-based release agents, long-chain alkyl-based release agents, fluorine-based release agents, and rubber-based release agents. Among these, silicone-based release agents are preferred. The thickness of the release agent layer is usually about 0.01 to 5 μm.

[0105] <Manufacturing method> The method for producing the adhesive label 10 (20) of the present invention is not particularly limited, but examples thereof include a method in which an adhesive roll or sheet is produced, and then printing, half-punching, and scrap removal are performed as necessary to produce the adhesive label 10 (20). Examples of methods for producing an adhesive roll or sheet include (1) a method in which an adhesive composition is applied to a release liner 30 to form an adhesive layer 15, and then this is laminated to a substrate 16, and (2) a method in which an adhesive composition is applied directly to a substrate 16 to form an adhesive layer 15, and then a release liner 30 is laminated.

[0106] The method for applying the pressure-sensitive adhesive composition to the substrate 16 or the release liner 30 is not particularly limited, and the composition can be applied using a known application device such as a roll coater, knife coater, air knife coater, bar coater, blade coater, slot die coater, lip coater, gravure coater, or curtain coater.

[0107] Furthermore, the substrate 16 may have a release coating layer 14 or a printing coating layer 17 formed thereon in advance.

[0108] For each coating layer, a coating layer-forming composition (a detachment coating layer-forming composition or a printing coating layer-forming composition, hereinafter collectively referred to as a coating layer-forming composition) is prepared by mixing a resin, an additive as needed, and a solvent. The solvent is appropriately selected depending on the form of the resin, and examples thereof include water, alcohols (e.g., ethanol, isopropanol, etc.), toluene, methyl ethyl ketone, and ethyl acetate.

[0109] Thereafter, the coating layer-forming composition is applied to the substrate 16 or the detachable coating layer 14 to form a coating layer (detachable coating layer 14 or printing coating layer 17). The coating method is not particularly limited, and a conventionally known method can be used, for example, a method in which the coating layer-forming composition is applied to the substrate 16 and dried to form each coating layer. The coating method is not particularly limited, and for example, a method in which various coating devices are appropriately selected from various types such as a blade coater, air knife coater, rod blade coater, bar blade coater, gravure coater, bar coater, multi-stage roll coater, roll coater, reverse roll coater, curtain coater, and spray coater can be used.

[0110] After the coating layer-forming composition is applied, it may be subjected to a drying step. Drying conditions are appropriately set, for example, at 80 to 160° C. for 10 to 60 seconds.

[0111] The adhesive label of the present invention allows the release coating layer to be peeled off by warm water, for example, by immersing a container (e.g., a PET bottle) to which the adhesive label is affixed in water of a temperature of 50°C or higher and 100°C or lower, causing the printed portion to release from the adhesive label, and enabling the printed portion to be separated from the adhesive label.

[0112] In addition, since the pressure-sensitive adhesive label of the present invention has the configuration of the present invention, the release coating layer is unlikely to be released or does not release in water at room temperature.

[0113] <Polyester-based containers> The present invention also provides a polyester-based container having the above-mentioned adhesive label attached thereto. The polyester-based container refers to a container made of a polyester-based resin. Examples of polyester-based resins include polyethylene terephthalate. The container can be produced by injection molding, vacuum forming, pressure forming, or the like of the polyester-based resin.

[0114] The present invention also includes the following aspects.

[0115] (1) An adhesive label having a release coating layer, a substrate, and an adhesive layer in this order, wherein the release coating layer contains a polyester resin and a water-soluble polymer.

[0116] (2) The adhesive label according to (1), wherein the water-soluble polymer comprises a polyvinyl alcohol-based resin and / or a polyalkylene glycol-based resin.

[0117] (3) An adhesive label according to (1) or (2), in which the content of the polyester-based resin relative to the total content of the polyester-based resin and the water-soluble polymer is 30% by mass or more.

[0118] (4) The adhesive label according to any one of (1) to (3), wherein the content of the polyester resin relative to the total content of the polyester resin and the water-soluble polymer is 85 mass % or less.

[0119] (5) The pressure-sensitive adhesive label according to any one of (1) to (4), further comprising a printing coating layer on the release coating layer facing the substrate.

[0120] (6) The pressure-sensitive adhesive label according to any one of (1) to (5), wherein the printing coating layer contains a urethane-modified polyester resin.

[0121] (7) The adhesive label according to any one of (1) to (6), wherein the substrate is a polyester-based resin substrate.

[0122] (8) The adhesive label according to any one of (1) to (7), wherein the adhesive layer contains a polyester-based adhesive.

[0123] (9) The adhesive label according to any one of (1) to (8), which has a printed portion on its surface. [Example]

[0124] Next, the examples will be described. In the examples, the units "parts" or "%" may be used, but unless otherwise specified, they represent "parts by mass" or "% by mass." Furthermore, unless otherwise specified, each operation is carried out at room temperature (25°C).

[0125] Example 1 A self-emulsifying aqueous polyester resin solution (30% solids by weight, aqueous solvent (containing 10% butyl cellosolve), polyester resin: hydroxyl value 5 mg KOH / g, acid value <3 mg KOH / g, containing carboxyl groups, molecular weight (Mn) 20,000, Tg 61°C) was mixed with 25 parts by solids of a polyvinyl alcohol (PVA) (manufactured by Japan Vinyl Acetate & Poval Co., Ltd., trade name JP-03, degree of polymerization 300, degree of saponification 86-90%) aqueous solution (5% solids by weight) to obtain a release coating layer-forming composition. The release coating layer-forming composition was applied to a 50 μm-thick polyethylene terephthalate film (polyester resin substrate) using a Meyer bar and dried to a dry film thickness of 0.2 μm.

[0126] Next, 2 parts by mass (solid content) of an isocyanate crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate HL") and 40 parts by mass of ethyl acetate were added and mixed with 100 parts by mass (solid content) of a polyester resin (manufactured by Mitsubishi Chemical Corporation, trade name "Nichigo Polyester NP-110S50EO") to prepare a pressure-sensitive adhesive composition.

[0127] The obtained adhesive composition was applied using a knife coater onto a release liner (thickness: 88 μm) made of polyethylene-laminated glassine paper coated with a silicone-based release agent so that the film thickness after drying would be 20 μm, and then dried at 90°C for 1 minute to form an adhesive layer.

[0128] An adhesive layer with a release liner laminated thereon was attached to the side of the polyethylene terephthalate film opposite the release coating layer, and the film was left standing for 7 days under standard conditions (23°C, 50% RH) to obtain an adhesive label.

[0129] Example 2 An adhesive label was obtained in the same manner as in Example 1, except that in the composition for forming the detachment coating layer of Example 1, the self-emulsifying aqueous polyester resin solution was 50 parts by mass in solid content and the polyvinyl alcohol aqueous solution was 50 parts by mass in solid content.

[0130] Example 3 An adhesive label was obtained in the same manner as in Example 1, except that in the composition for forming the detachment coating layer of Example 1, the self-emulsifying aqueous polyester resin solution was used in an amount of 65 parts by mass in terms of solid content and the polyvinyl alcohol aqueous solution in an amount of 35 parts by mass in terms of solid content.

[0131] Example 4 An adhesive label was obtained in the same manner as in Example 1, except that in the composition for forming the detachment coating layer of Example 1, the self-emulsifying aqueous polyester resin solution was used in an amount of 80 parts by mass in terms of solid content and the polyvinyl alcohol aqueous solution in an amount of 20 parts by mass in terms of solid content.

[0132] Example 5 An adhesive label was obtained in the same manner as in Example 4, except that the composition for forming the release coating layer in Example 4 was a self-emulsifying aqueous polyester resin solution (solid content 25% by mass, viscosity 10 mPa·s (20°C), water solvent, polyester resin: acid value 40 to 60 mgKOH / g, carboxyl group-containing, molecular weight 3,000, Tg 46°C).

[0133] Example 6 An adhesive label was obtained in the same manner as in Example 4, except that polyethylene glycol (molecular weight: 4000) was used instead of the aqueous solution (solid content 5% by mass) of polyvinyl alcohol (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., product name JP-03, degree of polymerization 300, degree of saponification 86-90%) in the composition for forming the release coating layer of Example 4.

[0134] Example 7 An adhesive label was obtained in the same manner as in Example 4, except that in the composition for forming the release coating layer of Example 4, an aqueous solution (solid content 5% by mass) of polyvinyl alcohol (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., product name JP-20, polymerization degree 2000, saponification degree 87 to 89%) was used as the polyvinyl alcohol.

[0135] Example 8 An adhesive label was obtained in the same manner as in Example 4, except that in the composition for forming the release coating layer of Example 4, an aqueous solution of polyvinyl alcohol (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., product name JP-05, polymerization degree 500, saponification degree 87 to 89%) (solid content 5% by mass) was used as the polyvinyl alcohol.

[0136] Example 9 An adhesive label was obtained in the same manner as in Example 4, except that in the composition for forming the release coating layer of Example 4, an aqueous solution (solid content 5% by mass) of polyvinyl alcohol (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., product name JL-05E, degree of polymerization 500, degree of saponification 80 to 84%) was used as the polyvinyl alcohol.

[0137] Example 10 An adhesive label was obtained in the same manner as in Example 4, except that in the composition for forming the release coating layer of Example 4, an aqueous solution (solid content 5% by mass) of polyvinyl alcohol (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., trade name JR-05, degree of polymerization 500, degree of saponification 70 to 74%) was used as the polyvinyl alcohol.

[0138] Example 11 An adhesive label was obtained in the same manner as in Example 1, except that in the composition for forming the detachment coating layer of Example 1, the self-emulsifying aqueous polyester resin solution was used in an amount of 90 parts by mass in terms of solid content and the polyvinyl alcohol aqueous solution was used in an amount of 10 parts by mass in terms of solid content.

[0139] Example 12 An adhesive label was obtained in the same manner as in Example 4, except that a printing coating layer was formed by mixing 3 parts by mass of a crosslinking agent (hexamethylene diisocyanate) with 100 parts by mass of urethane-modified polyester resin (Vylon UR-8300, manufactured by Toyobo Co., Ltd.) and resin solids, and diluting the mixture with toluene. The resulting release coating layer was coated and dried using a Mayer bar to give a dry film thickness of 0.08 μm.

[0140] (Comparative Example 1) An adhesive label was obtained in the same manner as in Example 1, except that the self-emulsifying aqueous polyester resin solution was not used in the composition for forming the release coating layer.

[0141] (Comparative Example 2) An adhesive label was obtained in the same manner as in Example 1, except that the aqueous polyvinyl alcohol solution was not used in the composition for forming a release coating layer of Example 1.

[0142] [Evaluation method 1: Adhesion to substrate] In the examples and comparative examples, a sample (a detachment coating layer-polyester resin substrate laminate) having a detachment coating layer formed thereon was left to stand for 24 hours in an environment of 23°C and a relative humidity of 50%RH to prepare a test sample. Then, a 10cm x 24mm piece of cellophane tape (manufactured by Nichiban Co., Ltd., registered trademark) was attached to the surface of the test sample on which the detachment coating layer had been formed, and the tape was peeled off to check the remaining state (area) of the detachment coating layer and evaluate it according to the following evaluation criteria. The results are shown in Table 1.

[0143] <Evaluation criteria> ⊚: 80% or more of the detached coating layer remains. ◯: 50% or more and less than 80% of the detached coating layer remains. △: 20% or more and less than 50% of the detached coating layer remains. ×: Only 20% or less of the detached coating layer remains.

[0144] [Evaluation method 2: Hot water desorption] The samples obtained in the examples and comparative examples were printed solidly using ink: UV161 J Ink S (manufactured by T&K TOKA) with a printer: RI Tester. The ink was cured by irradiating it with ultraviolet light from a high-pressure mercury lamp, and then cut into samples measuring 10 mm x 10 mm. Five samples were placed in 1 L of 70°C hot water and stirred. The time until all five prints had peeled off was recorded (maximum 15 minutes) and evaluated according to the following criteria. The results are shown in Table 1.

[0145] [Table 1]

[0146] As shown above, the pressure-sensitive adhesive labels of the Examples had excellent substrate adhesion and excellent deinking properties in hot water. On the other hand, Comparative Example 1, which used a release coating layer made only of a water-soluble polymer, had significantly reduced substrate adhesion. Furthermore, Comparative Example 2, which used a release coating layer made only of polyester, had significantly reduced deinking properties in hot water.

[0147] In Example 12, the results were equivalent to those of Example 4 in terms of substrate adhesion and hot water releasability. [Explanation of symbols]

[0148] 10, 20 adhesive labels, 11 base material, 12 release agent layer, 13 Printing Department, 14. Detachable coating layer, 15 adhesive layer, 16 base material, 17 printing coat layer, 30 release liners.

Claims

1. The adhesive tape has a release coating layer, a substrate, and a pressure-sensitive adhesive layer in this order, An adhesive label, wherein the release coating layer comprises a polyester resin and a water-soluble polymer.

2. The adhesive label according to claim 1 , wherein the water-soluble polymer comprises a polyvinyl alcohol-based resin and / or a polyalkylene glycol-based resin.

3. The pressure-sensitive adhesive label according to claim 1 or 2, wherein a content of the polyester-based resin relative to a total content of the polyester-based resin and the water-soluble polymer is 30 mass % or more.

4. The pressure-sensitive adhesive label according to claim 1 or 2, wherein a content of the polyester-based resin relative to a total content of the polyester-based resin and the water-soluble polymer is 85 mass % or less.

5. The pressure-sensitive adhesive label according to claim 1 or 2, further comprising a printable coating layer on the release coating layer facing the substrate.

6. The pressure-sensitive adhesive label according to claim 5 , wherein the printable coating layer contains a urethane-modified polyester resin.

7. The adhesive label according to claim 1 or 2, wherein the substrate is a polyester-based resin substrate.

8. The adhesive label according to claim 1 or 2, wherein the adhesive layer comprises a polyester-based adhesive.

9. The adhesive label according to claim 1 or 2, which has a printed portion on its surface.

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