Label, method for removing ink layer from label, and method for manufacturing label

Abstract

The present invention provides: a label, from which an ink layer can be removed efficiently; a method for removing the ink layer from the label; and a method for manufacturing the label.　A label (11) comprises; a substrate (101); an alkali-soluble coating layer (102) which is on the substrate (101); and an ink layer (103) which is on the coating layer (102). The coating layer (102) or the ink layer (103) contains a material which emits light when irradiated with an energy ray.

Description

Technical Field

[0001] The present disclosure relates to a label, a method for removing an ink layer from the label, and a method for manufacturing the label.

Background Art

[0002] In recent years, plastic products such as polyethylene terephthalate bottles (PET bottles) have been widely used. From the viewpoints of resource conservation and the environment, etc., it is strongly required to reuse plastic products such as PET bottles.

[0003] Among plastic products, in particular, the reuse of PET bottles has already been established. However, although a plastic label having an ink layer printed for displaying product information or the like may be attached to the body of a PET bottle, the label has not yet been reused.

[0004] One of the factors that inhibits the reuse of labels is that the ink layer cannot be sufficiently removed from the labels. If the ink layer cannot be sufficiently removed from the label, the ink may be mixed into the recycled resin regenerated from the label, and it may not be possible to produce recycled products such as pellets having a useful value from the recycled resin.

[0005] Therefore, for example, Patent Document 1 describes a plastic label in which a display printing ink layer is formed on a base film via a coat layer soluble in an aqueous alkali solution. In Patent Document 1, the display printing ink layer is alkali-desorbed by dissolving the coat layer of the plastic label in an aqueous alkali solution.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] When actually reusing labels, it is assumed that labels with an alkali-detachable ink layer and labels with a non-alkali-detachable ink layer are mixed and recovered. When reusing labels, a technique for separating labels with an alkali-detachable ink layer and labels with a non-alkali-detachable ink layer has not yet been established.

[0008] Even if alkali detachment of the ink layer is performed with labels having an alkali-detachable ink layer and labels having a non-alkali-detachable ink layer mixed, it is necessary to remove the labels having a non-alkali-detachable ink layer after the alkali detachment of the ink layer. Therefore, a method for efficiently removing the ink layer is desired. [Means for Solving the Problems]

[0009] According to the embodiment disclosed herein, a label including a substrate, an alkali-soluble coat layer on the substrate, and an ink layer on the coat layer can be provided, wherein the coat layer or the ink layer contains a material that emits light when irradiated with an energy beam.

[0010] According to the embodiment disclosed herein, a method for removing an ink layer from a label can be provided, including the steps of collecting a group of labels including a label containing a material that emits light when irradiated with an energy beam and capable of removing the ink layer by alkali detachment, irradiating the collected group of labels with an energy beam, separating the labels that emit light by irradiating with the energy beam, and removing the ink layer from the separated labels by alkali detachment.

[0011] According to the embodiment disclosed herein, a method for manufacturing a label containing, as a raw material, a resin derived from a label obtained by the above removal method can be provided. [Advantages of the Invention]

[0012] According to the embodiments disclosed herein, it is possible to provide a label capable of efficiently removing an ink layer, a method for removing the ink layer from the label, and a method for manufacturing a label using a resin containing, as a raw material, the label from which the ink layer has been removed.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0014] <Label> FIG. 1 shows a schematic cross-sectional view of the label of the embodiment. As shown in FIG. 1, the label 11 of the embodiment includes a base material 101, an alkali-soluble coat layer 102 on the base material 101, and an ink layer 103 on the coat layer 102. The label 11 of the embodiment may be a label having heat shrinkability (shrink label) or a label not having heat shrinkability. Further, the label 11 of the embodiment may be a stretch label having self-stretchability or a label not having self-stretchability.

[0015] <Base Material> The base material 101 is a substrate containing a resin capable of supporting the coat layer 102 and the ink layer 103.

[0016] Examples of the resin contained in the base material 101 include polyester resins (such as polyethylene terephthalate, polyethylene naphthalate, polylactic acid, etc.), polystyrene resins (such as polystyrene, styrene-butadiene copolymer, etc.), polyolefin resins (such as polyethylene, polypropylene, etc.), polyvinyl chloride resins, polyamide resins, aramid resins, polyimide resins, polyphenylene sulfide resins, or acrylic resins, etc. The base material 101 may contain one type of these resins or two or more types of these resins.

[0017] As the resin contained in the base material 101, it is preferable to use a polyester resin, and among them, it is particularly preferable to use PET. PET is a polyester resin containing terephthalic acid as the main component of the dicarboxylic acid component and ethylene glycol as the main component of the diol component. Further, PET may contain, as other components, for example, dicarboxylic acids such as isophthalic acid, phthalic acid, adipic acid, sebacic acid, or naphthalenedicarboxylic acid, and may contain, for example, diol components such as diethylene glycol, neopentyl glycol, polyalkylene glycol, or 1,4-cyclohexanedimethanol.

[0018] The base material 101 may be, for example, a film having heat shrinkability (shrink film). When the base material 101 is a shrink film, the processability (followability to the container) and decorativeness of the label 11 can be improved, and the display area of the label 11 can be further expanded. The base material 101 may also be, for example, a stretch film having self-stretchability.

[0019] The base material 101 may be a single-layer film composed of one layer or a multilayer film composed of two or more layers. Further, the thickness of the base material 101 can be, for example, 5 μm or more and 100 μm, but is not particularly limited.

[0020] <Coat layer> The coat layer 102 is a layer located between the base material 101 and the ink layer 103 and contains a resin having alkali solubility.

[0021] That the coat layer 102 has alkali solubility means that when a sample in which a coat layer 102 having a size of 4 cm × 4 cm in length × width is formed on a base material 101 of any size and an arbitrary ink layer 103 is provided on the coat layer 102 is immersed in an aqueous sodium hydroxide solution at 85 °C and 1.5% by mass (that is, 1.5% of the total mass of the aqueous sodium hydroxide solution is sodium hydroxide) and stirred at 1500 rpm, 70% or more of the total area of the ink layer 103 peels off from the sample in 15 minutes of immersion time.

[0022] As the resin contained in the coat layer 102, for example, a resin having the following (1) to (4) can be used. (1) Contains a first resin which is an acrylic acid copolymer resin having a first glass transition temperature T1; (2) Contains a second resin which is an acrylic acid copolymer resin having a second glass transition temperature T2 lower than the above T1; (3) The apparent acid value of the coat layer 102 is 40 mgKOH / g or more and 150 mgKOH / g or less; (4) The first resin and the second resin contained in the coat layer 102 together account for 50 to 95% by mass of the entire coat layer 102.

[0023] The resin having the above (1) to (4) has good alkali solubility. Therefore, by providing the label 11 with the coat layer 102 having alkali solubility between the base material 101 and the ink layer 103, the ink layer 103 also peels off from the label 11 along with the alkali peeling of the coat layer 102 from the label 11.

[0024] In addition, the resin having the above (1) to (4) is excellent in printing suitability in addition to the above-mentioned alkali solubility. Accordingly, the decorativeness of the ink layer 103 on the coat layer 102 can be enhanced.

[0025] As shown in the above (1) and (2), the first resin and the second resin are each an acrylic acid copolymer resin. The acrylic acid copolymer resin is a resin that contains acrylic acid and / or methacrylic acid as the main repeating unit and also contains a copolymerizable monomer copolymerizable with acrylic acid and / or methacrylic acid. It is preferable that the total proportion of acrylic acid and / or methacrylic acid and the copolymerizable monomer in the resin is 60 mol% or more.

[0026] Examples of the copolymerizable monomer include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, t-butyl (meth)acrylate [preferably lower alkyl esters of (meth)acrylic acid]; hydroxyl group-containing (meth)acrylates such as hydroxyethyl (meth)acrylate; glycidyl group-containing (meth)acrylates such as glycidyl (meth)acrylate; (meth)acrylamides such as N,N'-dimethyl (meth)acrylamide, N,N'-diethyl (meth)acrylamide; amino group-containing (meth)acrylates such as dimethylaminoethyl (meth)acrylate; styrenes such as styrene, vinyltoluene, α-methylstyrene; vinyl esters such as vinyl acetate, vinyl propionate; vinyl halides such as vinyl chloride; vinyl ethers such as methyl vinyl ether; carboxyl group-containing vinyls [(excluding (meth)acrylic acid)] such as itaconic acid, maleic anhydride; cyano group-containing vinyls such as acrylonitrile, methacrylonitrile; olefins such as ethylene, propylene, and dienes. The copolymerizable monomer can be used alone or in combination of two or more.

[0027] Regarding the above (1) and (2), the Tg of each of the first resin and the second resin can be controlled, for example, by adjusting the mass average molecular weight (Mm) of the acrylic acid copolymer resin. For example, by making the Mm of the first resin larger than the Mm of the second resin, the first resin and the second resin having the relationship of T1>T2 can be obtained. Preferably, the Mm of the first resin is 30,000 or more and 90,000 or less, and the Mm of the second resin is 10,000 or more and less than 30,000.

[0028] Regarding the above (1) and (2), T1, which is the Tg of the first resin, is preferably 90°C or higher, more preferably 95°C or higher, and particularly preferably 100°C or higher. The upper limit value of T1 can be about 120°C, for example, from the physical properties of the acrylic acid copolymer resin. T2, which is the Tg of the second resin, is preferably less than 80°C, more preferably 75°C or lower, and particularly preferably 65°C or lower. The lower limit value of T2 can be about 30°C, for example, from the viewpoint of ease of handling. T1 and T2 preferably have a difference of 20°C or more, more preferably a difference of 30°C or more, and particularly preferably a difference of 40°C or more. In this case, since the decrease in printing suitability can be more effectively suppressed, the cosmetic property of the ink layer 103 can be particularly improved.

[0029] Regarding the above (3), the apparent acid value of the coat layer 102 means the acid value of the mixed resin composed of two or more kinds of resins contained in the coat layer 102. The apparent acid value of the coat layer 102 can be adjusted by controlling the acid value of each of the first resin and the second resin. The acid value of each of the first resin and the second resin can be adjusted, for example, by the blending ratio of (meth)acrylic acid and the copolymerizable monomer.

[0030] Regarding the above (3), the apparent acid value of the coating layer 102 is more preferably 50 mgKOH / g or more and 130 mgKOH / g or less, and particularly preferably 55 mgKOH / g or more and 125 mgKOH / g or less. In these cases, it becomes possible to particularly improve the alkali solubility and printing suitability of the coating layer 102.

[0031] The acid value of the first resin and each acid value of the second resin are each preferably 40 mgKOH / g or more and 150 mgKOH / g or less. In this case, the apparent acid value of the coating layer 102 can be easily made 40 mgKOH / g or more and 150 mgKOH / g or less as described in the above (3). Further, the acid value of the first resin is preferably lower than the acid value of the second resin. The acid value of the first resin is preferably less than 60 mgKOH / g. Also, the acid value of the second resin is preferably 80 mgKOH / g or more.

[0032] Regarding the above (4), the first resin and the second resin in the coating layer 102 preferably occupy 70% by mass or more and 95% by mass or less of the entire coating layer 102 in total, and more preferably 80% by mass or more and 95% by mass or less. In these cases, it becomes possible to particularly improve the alkali solubility and printing suitability of the coating layer 102. Also, it is preferable that the content ratio of the first resin and the content ratio of the second resin do not differ greatly. From the viewpoint of improving the synergistic effect by containing the two types of resins, the first resin and the second resin, the ratio of the content of the first resin to the content of the second resin (content of the resin with a relatively large content / content of the resin with a relatively small content) is preferably 3 or less.

[0033] That the coating layer 102 contains an alkali-soluble resin can be confirmed, for example, using various analytical techniques. For example, it can be confirmed by nuclear magnetic resonance (NMR), gas chromatography-mass spectrometer (GCMS), or pyrolysis gas chromatography (pyrolysis GCMS), etc., that an acrylic acid copolymer resin is present in a specific content in the coating layer 102. Further, the acid value of the coating layer 102 can be confirmed, for example, by titrating the coating layer 102. The titration of the coating layer 102 can be calculated, for example, based on the result of potentiometric titration of the coating layer 102 dissolved in a titration solvent such as a mixed solvent of xylene and dimethylformamide using a potassium hydroxide solution of a predetermined concentration (for example, 0.1 mol / L potassium hydroxide-ethanol solution). Also, that the coating layer 102 contains the first resin and the second resin having the above Tg can be confirmed, for example, by subjecting the composition used for forming the coating layer described below to differential scanning calorimetry (DSC) method. The DSC method can be performed using "DSC6200" manufactured by Seiko Instruments Inc. under the condition of a heating rate of 10 °C / min. Further, the Mm of the first resin and the Mm of the second resin can be confirmed, for example, by gel permeation chromatography (GPC).

[0034] The above-mentioned first resin and second resin are preferably methacrylic acid-methyl methacrylate copolymer (hereinafter, also referred to as "MM copolymer"). In this case, it becomes possible to significantly improve both characteristics of the alkali solubility and printability of the coating layer 102. The MM copolymer may be synthesized or may be a commercially available product. Commercially available products suitable for the first resin include "Dianal LR-1941" or "Dianal BR-87" manufactured by Mitsubishi Rayon Co., Ltd. Commercially available products suitable for the second resin include "JONCRYL JDX-C3000" manufactured by BASF Japan Ltd., "ARUFON UC3000" manufactured by Toagosei Co., Ltd., or "BR-605" manufactured by Mitsubishi Rayon Co., Ltd. Among them, as the first resin and the second resin, it is preferable to use a combination of "Dianal LR-1941" and "JONCRYL JDX-C3000".

[0035] In addition to the first resin and the second resin, the coating layer 102 may contain other components. Preferred other components include cellulose derivatives. When the coating layer 102 contains a cellulose derivative, it becomes possible to improve the blocking resistance, adhesion, etc. of the coating layer 102.

[0036] Examples of the cellulose derivative contained in the coating layer 102 include nitrocellulose, acetyl cellulose, carboxymethyl cellulose or its salts, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate butyrate, or cellulose acetate propionate, etc. It is preferable to use nitrocellulose as the cellulose derivative contained in the coating layer 102. In the coating layer 102, the cellulose derivative can be used alone or in combination of two or more.

[0037] The content of the cellulose derivative in the coating layer 102 is preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 15% by mass or less, and particularly preferably 8% by mass or more and 12% by mass or less of the total mass of the coating layer 102. In these cases, the blocking resistance and printability of the coating layer 102 can be improved. The cellulose derivative preferably has a degree of polymerization of 35 or more and 380 or less, more preferably 45 or more and 290 or less, and particularly preferably 55 or more and 110 or less. Also in these cases, it becomes possible to improve the blocking resistance and printability of the coating layer 102.

[0038] Further, the coat layer 102 may contain, as other preferable components, for example, a vinyl chloride-vinyl acetate copolymer (hereinafter, also referred to as "VV copolymer"). By including the VV copolymer in the coat layer 102, it becomes possible to further improve the adhesion between the base material 101 and the coat layer 102. Therefore, when the coat layer 102 contains an alkali-soluble resin and a VV copolymer, it can function as an underlayer with particularly excellent adhesion.

[0039] The content of the VV copolymer in the coat layer 102 is preferably 5 to 20% by mass, more preferably 8 to 18% by mass, and particularly preferably 9 to 12% by mass of the total mass of the coat layer 3. In these cases, the adhesion and printability of the coat layer 102 can be improved. The VV copolymer in the coat layer 102 preferably has a Mm of 10,000 to 40,000, and more preferably has a Mm of 15,000 to 35,000. In these cases, the improvement in the adhesion of the coat layer 102 becomes remarkable.

[0040] The coat layer 102 may further contain a material that emits light when irradiated with energy rays. Thereby, when the label 11 is irradiated with energy rays and the coat layer 102 of the label 11 emits light, it becomes possible to identify and separate the label 11 of the embodiment provided with the alkali-soluble coat layer 102.

[0041] As the energy rays irradiated on the label 11, for example, short-wavelength electromagnetic waves such as X-rays or ultraviolet light, visible light, infrared light, near-infrared light, or microwaves can be used. It is preferable to use ultraviolet light as the energy rays irradiated on the label 11. When ultraviolet light is used as the energy rays irradiated on the label 11, it becomes easier to cause electron excitation of the material that emits light when irradiated with energy rays.

[0042] As the material that emits light when irradiated with energy rays, for example, a fluorescent pigment or a phosphorescent pigment can be used.

[0043] A fluorescent pigment is a pigment that emits light when irradiated with energy rays, but pigments having phosphorescence are excluded from fluorescent pigments. Examples of fluorescent pigments include organic pigments and inorganic pigments. Examples of organic pigments include fluorescein-based, coumarin-based, rhodamine-based, oxazole-based, pyrazoline-based, thiadiazole-based, spiropyran-based, pyrenesulfonic acid-based, benzimidazole-based, and diaminostilbene-based pigments. Examples of inorganic pigments include zinc sulfide activated with copper, silver, manganese, etc., zinc silicate activated with manganese, etc., calcium sulfide activated with cadmium, bismuth, etc., strontium sulfide activated with samarium, cerium, etc., and calcium tungstate activated with lead, etc.

[0044] More specifically, examples of red fluorescent pigments include Y2O2S:Eu, Y2O3:Eu, Y2SiO5:Eu, Y3AlO 12 :Eu, Zn3(PO4)2:Mn, YBO3:Eu, (Y, Gd)BO3:Eu, GdBO3:Eu, ScBO3:Eu, or LuBO3:Eu, etc. can be used.

[0045] Examples of blue fluorescent pigments include BaMg2Al 16 O 27 :Eu, Y2SiO5:Ce, CaWO4:Pb, or BaMgAl 14 O 23 :Eu, etc. can be used.

[0046] Examples of green fluorescent pigments include BaMg2Al 16 O 27 :(Eu,Mn), (Ba,Mg)Al 16 O 27 :(Eu,Mn), Zn2SiO4:Mn, BaAl 12 O 19 :Mn, SrAl 13 O 19 :Mn, CaAl 12 O 19 :Mn, YBO3:Tb, BaMgAl 14 O 23: Mn, LuBO3:Tb, GdBO3:Tb, ScBO3:Tb, or Sr6Si3O3C 14 : Eu or the like can be used.

[0047] As the fluorescent pigment, for example, one of the above may be used alone, or two or more of the above may be used in combination.

[0048] The phosphorescent pigment is a pigment having a phosphorescent property among the pigments that emit light when irradiated with an energy ray. As the phosphorescent pigment, for example, a sulfide-based phosphorescent pigment, an oxyacid salt-based phosphorescent pigment, an aluminic oxide-based phosphorescent pigment, or the like can be used.

[0049] As the sulfide-based phosphorescent pigment, for example, calcium sulfide: bismuth-based (CaS:Bi), calcium strontium sulfide: bismuth-based (CaSrS:Bi), zinc sulfide: copper-based (ZnS:Cu), or zinc cadmium sulfide: copper-based (ZnCdS:Cu) etc. can be used.

[0050] As the oxyacid salt-based phosphorescent pigment, for example, Zn2SiO4:Mn, (Zn,Be)2SiO4:Mn, Ca3(PO4)2:Ce, or Ca3(PO4)2:(Ce,Mn) etc. can be used.

[0051] As the aluminic oxide-based phosphorescent pigment, for example, calcium aluminum oxide: europium-based (CaAl2O4:Eu), strontium aluminum oxide: europium-based (SrAl2O4:Eu), or barium aluminum oxide: europium-based (BaAl2O4:Eu) etc. can be used.

[0052] As the phosphorescent pigment, for example, one of the above may be used alone, or two or more of the above may be used in combination.

[0053] The coating layer 102 may contain other components, for example, for the purpose of improving printability and the like, in addition to the above. In addition, for example, when the coating layer 102 contains a first resin, a second resin, a VV copolymer, and a cellulose derivative at predetermined content ratios, the sum of the content ratios of the respective components × the acid value of each resin becomes the apparent acid value of the coating layer 102.

[0054] The thickness of the coating layer 102 can be, for example, 0.1 μm or more and 5 μm or less, preferably 0.3 μm or more and 3 μm or less, but is not particularly limited.

[0055] <Ink layer> The ink layer 103 is a layer located on the coating layer 102 and containing an ink resin composition. The ink resin composition contained in the ink layer 103 may contain, for example, a pigment, a resin, and an additive. Further, the ink layer 103 is preferably a design printing layer. The design printing layer contains a pigment and is a layer that displays a visible pattern, characters, or the like.

[0056] The ink layer 103 may be provided on the entire surface of the coating layer 102 or may be provided on a part of the coating layer 102. Further, the ink layer 103 may be a single layer or a multi-layer. The thickness of the ink layer 103 can be, for example, about 0.1 μm or more and 100 μm or less, but is not particularly limited.

[0057] The ink layer 103 may further contain a material that emits light when irradiated with energy rays. Thereby, when the label 11 is irradiated with energy rays and the ink layer 103 of the label 11 emits light, the label 11 in the embodiment provided with the alkali-soluble coating layer 102 can be specified and separated.

[0058] <Other layers> The label 11 may further include other layers such as an overcoat layer on the ink layer 103, for example. The overcoat layer is a layer for protecting the ink layer 103 from external factors.

[0059] <Method for Manufacturing Label> The label 11 of the embodiment can be manufactured, for example, as follows. First, a base material 101 is prepared. The base material 101 can be prepared, for example, by forming a film by a method such as an extrusion method or a calender method, and further performing a stretching process on the film as necessary.

[0060] Next, a coat layer 102 is formed on one surface of the base material 101. The coat layer 102 can be formed, for example, by applying a composition containing a resin contained in the coat layer 102 on one surface of the base material 101 and then solidifying it.

[0061] Next, an ink layer 103 is formed on the surface of the coat layer 102. The ink layer 103 can be formed, for example, by applying an ink resin composition for forming the ink layer 103 on the surface of the coat layer 102 and then solidifying it.

[0062] When the label 11 further includes another layer such as an overcoat layer, the other layer can be formed by applying a resin composition for forming the other layer on the surface of the ink layer 103 and then solidifying it.

[0063] <Method for Removing Ink Layer from Label> Figs. 2(a) to (i) show an example of a flowchart of a method for removing an ink layer from a label of an embodiment when the label 11 of the embodiment is a shrink label. Hereinafter, with reference to Figs. 2(a) to (i), a method for removing an ink layer from the label 11 of the embodiment will be described.

[0064] <Recycling Process of PET Bottle> First, as shown in Fig. 2(a), the PET bottle 10 is collected in a collection box 12. Here, a label 11 of the embodiment having an ink layer 103 is attached to the body of the PET bottle 10. In the present embodiment, the ink layer 103 is used as a printing layer for product display and the like.

[0065] <Compression process> Next, as shown in Fig. 2(b), the recovered PET bottle 10 is compressed with the label 11 attached thereto to obtain a labeled bale 20.

[0066] <Accumulation process> Next, as shown in Fig. 2(c), the labeled bale 20 is sent to a recycling factory 30 and accumulated.

[0067] <Label group recovery process> Next, as shown in Fig. 2(d), a label group 50 including the label 11 of the embodiment and a normal label 40 is recovered. The recovery of the label group 50 can be performed, for example, as follows.

[0068] First, at the recycling factory 30, the label 11 of the embodiment and / or the normal label 40 are removed from the PET bottle 10 of the labeled bale 20, and the label group 50 including the label 11 of the embodiment and the normal label 40 and the PET bottle 10 are separated, and the label group 50 including the label 11 of the embodiment and the normal label 40 is recovered.

[0069] In the present embodiment, the normal label 40 is a label in which the ink layer cannot be alkali-desorbed because the coating layer or the ink layer is not alkali-soluble, and does not contain a material that emits light when irradiated with energy rays.

[0070] The PET bottle 10 from which the label 11 and / or the normal label 40 are separated is reused in the recycling process of existing PET bottles.

[0071] <Energy ray irradiation / sorting process> Next, as shown in Fig. 2(e), the recovered label group 50 is irradiated with energy rays. Fig. 3 shows a schematic side view illustrating an example of the process of irradiating the recovered label group 50 with energy rays. Hereinafter, an example of the process of irradiating the recovered label group 50 with energy rays will be described with reference to Fig. 3.

[0072] First, the collected label group 50 is carried into the interior of the first dark place 201. Next, the label group 50 is irradiated with energy rays 22 from the light source 21 disposed inside the first dark place 201.

[0073] Next, the label group 50 after irradiation with the energy rays 22 is carried out from the interior of the first dark place 201. Next, the label group 50 carried out from the interior of the first dark place 201 is carried into the interior of the second dark place 202.

[0074] At this time, since the coating layer 102 of the label 11 of the embodiment after irradiation with the energy rays 22 emits light, inside the second dark place 202, the label 11 of the embodiment appears to be glowing. On the other hand, since the normal label 40 does not contain a material that emits light when irradiated with energy rays, even when irradiated with the energy rays 22, it does not appear to be glowing inside the second dark place 202.

[0075] Thereby, it becomes possible to separate and collect the label 11 of the embodiment that appears to be glowing inside the second dark place 202 from the normal label 40 that does not appear to be glowing inside the second dark place 202. The normal label 40 separated and collected from the label 11 of the embodiment is reused, for example, in a thermal recycling process.

[0076] Note that in this embodiment, the irradiation of the label group 50 with the energy rays 22 is performed inside the first dark place 201, but the irradiation of the label group 50 with the energy rays 22 does not necessarily have to be performed in a dark place.

[0077] <Preheating step> Next, as shown in Fig. 2(f), the shrink label 11 is preheated. The method of preheating the label 11 is not particularly limited as long as it can suppress the amount of shrinkage and curling of the label piece in the alkali detachment described later. However, it is preferably carried out such that the preheating temperature is the same as or higher than the alkali detachment temperature. From the viewpoint of efficiently removing the ink layer from the label piece in the alkali detachment described later, the preheating temperature is preferably 5°C or higher than the alkali detachment temperature.

[0078] Examples of the method of preheating the label 11 include passing the label 11 through a hot air tunnel 61 or immersing the label 11 in the warm water 60 in a warm water tank 62.

[0079] However, from the following viewpoints (A) to (D), it is preferable to use the method of immersing the label 11 in the warm water 60 in the warm water tank 62 as the method of preheating the label 11 rather than the method of passing the label 11 through the hot air tunnel 61. (A) When using hot air, the label 11 removed from the PET bottle 10 is blown away by the hot air, making control difficult. (B) The method of immersing in warm water is easier to control the temperature. (C) The method of immersing in warm water has a smaller footprint of the device. (D) The method of immersing in warm water is less likely to cause uneven shrinkage of the label 11 and can shrink uniformly.

[0080] For example, when preheating the label 11 by immersing the label 11 in the warm water 60 in the warm water tank 62, it can be carried out by immersing the label 11 in warm water at about 80°C to 90°C for about 10 seconds to 20 seconds.

[0081] The temperature of preheating means the surface temperature of label 11 during preheating. Therefore, when preheating label 11 by immersing label 11 in the warm water 60 in the warm water tank 62, the temperature of preheating can be replaced with the temperature of the warm water. Also, when preheating label 11 by passing label 11 through the hot air tunnel 61, the temperature of preheating can be replaced with the temperature of the hot air.

[0082] <Crushing process> Next, as shown in FIG. 1(g), the preheated label 11 is crushed by a crusher 70 to produce label pieces 71. The method of crushing the preheated label 11 is not particularly limited as long as the size of the label pieces 71 generated after the crushing is smaller than the size of the preheated label 11. For example, the preheated label 11 can be crushed to a size (for example, several cm square) that can efficiently remove the ink layer 103 from the label pieces 71 in the alkali detachment described later. Note that since the label pieces 71 are obtained by crushing the label 11 of the embodiment, it goes without saying that the layer configuration of the label 11 of the embodiment and the layer configuration of the label pieces 71 are the same.

[0083] <Alkali detachment process> Next, as shown in FIG. 1(h), the ink layer 103 is removed from the label pieces 71 by alkali detachment. The alkali detachment can be performed, for example, by stirring the inside of the hot alkali tank 82 while immersing the label pieces 71 in an alkali aqueous solution 80 at about 80°C to 90°C in the hot alkali tank 82 for about 30 seconds to 20 minutes. In this case, the label pieces 21 can be easily separated into the base material 101 and the ink coating 93 in the hot alkali tank 82. Also, the alkali detachment can be performed, for example, by immersing the label pieces 71 in the above-described alkali aqueous solution 80 for about 30 seconds to 20 minutes and then performing water washing. In this case, the label pieces 71 can be easily separated into the base material 101 and the ink coating 93 in the water washing (for example, in a water tank). A surfactant may be added to the alkali aqueous solution 80 for the purpose of further improving the detachability.

[0084] As described above, in this embodiment, the preheating temperature is set to be the same as or higher than the alkali detachment temperature. The alkali detachment temperature means the surface temperature of the label piece 71 during alkali detachment. Therefore, the alkali detachment temperature can be replaced with the temperature of the alkaline aqueous solution 80 in which the label piece 71 is immersed. From the viewpoint of efficiently removing the ink layer 103 from the label piece 71 in alkali detachment, the alkali detachment temperature is preferably 65°C or higher. The upper limit of the alkali detachment temperature is theoretically 100°C, more preferably the alkali detachment temperature is 85°C or higher and 95°C or lower, and even more preferably the alkali detachment temperature is 80°C or higher and 90°C or lower.

[0085] The alkaline aqueous solution 80 after removing the ink layer 103 from the label piece 71 may be discarded as waste liquid, or may be reused as the alkaline aqueous solution 80 for alkali detachment.

[0086] The alkaline aqueous solution 80 is not particularly limited as long as the ink layer can be removed from the label piece 71 by immersing the label piece 71, and is not particularly limited as long as it is an alkaline aqueous solution containing an alkaline substance. As the alkaline aqueous solution 80, for example, an aqueous solution of an alkali metal hydroxide such as sodium hydroxide (NaOH) or potassium hydroxide (KOH), an aqueous solution of an alkali metal carbonate such as sodium carbonate (Na2CO3), an aqueous solution of an alkali metal bicarbonate such as sodium bicarbonate (NaHCO3), or aqueous ammonia can be used.

[0087] The concentration of the alkaline substance in the alkaline aqueous solution 80 can be appropriately selected within a range that does not impair the detachment ability, operability, workability, etc. of the ink layer 103. The concentration of the alkaline substance in the alkaline aqueous solution 80 is, for example, about 0.1 to 10% by weight, preferably 0.5 to 5% by weight, and even more preferably about 1 to 3% by weight.

[0088] <Separation step of the substrate and the ink coating film> Next, as shown in FIG. 1(i), the base material 101 and the ink coating film 93 are separated. The separation of the base material 101 and the ink coating film can be performed, for example, by collecting the base material 101 after the ink layer 103 has been removed with a first screen 90 having a relatively large opening, and collecting the ink coating film 93 smaller than the base material 101 with a second screen 92 having a relatively small opening. Thus, the ink layer 103 can be removed from the label 11 of the embodiment. Note that the ink coating film 93 is a film obtained by finely dividing the ink layer 103 removed from the base material 101 during alkali detachment.

[0089] Thereafter, the base material 101 collected by the first screen 90 can be reused, for example, as a plastic raw material for manufacturing plastic products such as pellets. Also, by mixing the base material 101 into the raw material of a new label, it can be reused as a label such as a shrink label. On the other hand, the ink coating film 93 collected by the second screen 92 can be reused, for example, in a thermal recycling process.

[0090] The method for removing the ink layer from the label of the embodiment includes a step of collecting a label group 50 including the label 11 containing a material that emits light when irradiated with the energy beam 22, a step of irradiating the collected label group 50 with the energy beam 22, and a step of sorting the label 11 that has emitted light by irradiating the energy beam 22.

[0091] Therefore, according to the method for removing the ink layer from the label of the embodiment, by irradiating the energy beam 22 to emit light, it is possible to establish a technique capable of separating the label 11 from which the ink layer 103 can be removed by alkali detachment from the normal label 40 from which the ink layer 103 cannot be removed by alkali detachment.

[0092] This makes it possible to perform alkali detachment of the ink layer only for labels capable of alkali detachment of the ink layer, and it is not necessary to remove labels that are incapable of alkali detachment of the ink layer after the alkali detachment of the ink layer. Therefore, alkali detachment of the ink layer can be efficiently performed from labels capable of alkali detachment of the ink layer.

[0093] Also, the method for removing the ink layer from the label of the embodiment includes a step of preheating the label 11 provided with the ink layer 103, a step of crushing the label 11 after the preheating step to produce label pieces 71, and a step of removing the ink layer 103 from the label pieces 71 by alkali detachment, and the temperature of the preheating can be the same as or higher than the temperature of the alkali detachment.

[0094] In this case, when the label 11 is a shrink label, the ink layer 103 can be removed from the label 11 more efficiently than before.

[0095] That is, in the method for removing the ink layer from the label of the present embodiment, the label 11 is crushed into label pieces 71 prior to removing the ink layer 103 from the label 11 by alkali detachment. This is because the ink layer 103 can be efficiently removed from the label 11 by performing alkali detachment in a state where the label 11 is crushed into smaller label pieces 71.

[0096] When shrink label pieces produced by crushing a shrink label without preheating are immersed in an alkaline aqueous solution, the shrink label pieces in the alkaline aqueous solution wind up and curl while shrinking. It is very difficult to remove the ink layer from the curled small pieces, i.e., the shrink label pieces.

[0097] The shrink label attached to a PET bottle or the like has been heat-shrunk once during attachment, but the shrinking ability still remains in the shrink label. Therefore, when the temperature of the alkaline aqueous solution during alkali detachment is high, the shrink label piece will further heat-shrink. On the other hand, when the temperature of the alkaline aqueous solution is low, the ink layer cannot be efficiently removed from the shrink label piece.

[0098] Therefore, in the method for removing the ink layer from the label of the present embodiment, before crushing the shrink label into shrink label pieces, preheating of the shrink label is performed at a temperature equal to or higher than the temperature of alkali detachment to preheat and shrink it in advance. Then, the shape of the shrink label can be made, for example, a wavy shape with a small degree of curl. If preheating of the shrink label is performed after crushing the shrink label, the shrink label pieces will curl (be rolled up) as a whole, which is not suitable for removing the ink layer.

[0099] Then, the preheated and pre-shrunk shrink label is crushed into shrink label pieces. The shrink label pieces obtained by crushing a shrink label with a small degree of curl will also have a small degree of curl.

[0100] After that, for such shrink label pieces, alkali detachment can be performed at a temperature equal to or lower than the preheating temperature. In this case, even when the temperature of the alkaline aqueous solution during alkali detachment is high, the ink layer can be removed while suppressing the shrinkage of the shrink label pieces during alkali detachment.

[0101] For the above reasons, in the method for removing the ink layer from the label of the present embodiment, when the label 11 is a shrink label, it is considered that the ink layer can be removed from the label 11 more efficiently than before.

[0102] In particular, many labels 11 as shrink labels removed from containers such as PET bottles 10 generally have a side length of 10 cm or more. After heat-shrinking a label 11 of such a size by preheating and then crushing it into a few centimeters square, preferably 5 cm square or less, and performing alkali desorption at 65°C or higher, preferably 80°C or higher, more preferably 85°C or higher, the efficiency of removing the ink layer 103 can be significantly improved.

[0103] As the label 11 as a shrink label suitable for the method of this embodiment, a shrink label that, after being removed from a container such as a PET bottle 10 and immersed in a warm bath at 95°C for 10 seconds, has a shrinkage rate of 30% or more, preferably 40% or more, more preferably 50% or more as measured in the radial direction (main shrinkage direction) of the container can be mentioned.

[0104] In the method for removing the ink layer from the label of the above embodiment, the case where the label 11 is a shrink label has been described. However, the label 11 used in the method for removing the ink layer from the label of the embodiment does not have to be a shrink label.

[0105] Also, in the method for removing the ink layer from the label of the above embodiment, the case where a label 11 in which a material that emits light when irradiated with an energy beam is contained only in the coat layer 102 has been described. However, in the method for removing the ink layer from the label of the embodiment, the material that emits light when irradiated with an energy beam may be contained in at least one layer (for example, only the coat layer 102, only the ink layer 103, or both the coat layer 102 and the ink layer 103) constituting the label 11.

[0106] In addition, in the above-described embodiment, when the ink layer 103 is the above-described design printing layer, it is preferable that the coating layer 102 contains a material that emits light when irradiated with an energy beam. If the ink layer 103 is composed of a plurality of layers (multi-color design printing layers), it becomes complicated to determine how much of the material that emits light when irradiated with an energy beam should be included in each layer constituting the ink layer 103, and problems may occur such as the need to change the content of the material that emits light when irradiated with an energy beam in each design printing layer. Further, when the ink layer 103 is composed of a plurality of layers (multi-color design printing layers), it is preferable to include a material that emits light when irradiated with an energy beam in the ink that constitutes the white layer among the plurality of layers that constitute the ink layer 103. In this case, it becomes easier to confirm that the material emits light when irradiated with an energy beam.

[0107] In addition, in the above-described embodiment, when the coating layer 102 contains a material that emits light when irradiated with an energy beam, the content of the material that emits light when irradiated with an energy beam is preferably 5% by mass or more of the entire coating layer 102.

[0108] In addition, in the above-described embodiment, when the ink layer 103 contains a material that emits light when irradiated with an energy beam, the content of the material that emits light when irradiated with an energy beam is preferably 5% by mass or more of the entire ink layer 103.

[0109] <Method for manufacturing label> Using the label 11 obtained by the above-described method for removing the ink layer, pellets or the like can also be manufactured. By manufacturing a label using such pellets or the like, a label (recycled label) made from the resin derived from the label 11 obtained by the above-described method for removing the ink layer can be manufactured.

Example

[0110] <Experimental Example 1> (Preparation of Label) In Experimental Example 1, a label 11 (label of Experimental Example 1) having the configuration shown in the schematic cross-sectional view of FIG. 4 was prepared. The label of Experimental Example 1 was prepared as follows.

[0111] First, as the base material 101, a polyethylene terephthalate film (PET film) with a thickness of 20 μm was prepared. Next, using a gravure coater, a composition for forming the coating layer 102 was applied onto one surface of the PET film and then solidified to form the coating layer 102.

[0112] Note that the composition for forming the coating layer 102 was prepared by adding 5 parts by mass of a phosphorescent ink (NT Highlmic (NF) Phosphorescent Green) to 100 parts by mass of the composition shown in Table 1 below.

[0113]

Table 1

[0114] Next, using a gravure coater, an ink resin composition containing Etna red as the ink was applied onto the coating 102 layer and then solidified to form the color layer 103a.

[0115] Next, using a gravure coater, an ink resin composition containing white ink (NT Highlmic (NF) 701 White) was applied onto the color layer 103a layer and then solidified to form the white ink layer 103b.

[0116] Thereafter, using a gravure coater, medium was applied onto the white ink layer 103b and then solidified to form the overcoat layer 104, thereby completing the label of Experimental Example 1.

[0117] (Evaluation of Luminescence) The evaluation of the luminescence of the label of Experimental Example 1 was performed by irradiating the label of Experimental Example 1 with ultraviolet light. Fig. 5 shows a schematic side view illustrating the method for evaluating the luminescence of the label of Experimental Example 1.

[0118] As shown in Fig. 5, the evaluation of the luminescence of the label of Experimental Example 1 was performed by irradiating the surface of the label of Experimental Example 1 with ultraviolet light 22 from the light source 21 and evaluating the luminescence in the dark from the front side of the label 11, and by irradiating the back surface of the label of Experimental Example 1 with ultraviolet light 22 from the light source 21 and evaluating the luminescence in the dark from the back side of the label 11 (the side on which each layer is formed). The luminescence of the front and back surfaces of the label of Experimental Example 1 was evaluated based on the following evaluation criteria. The results are shown in Table 2.

[0119] (Evaluation criteria for luminescence) A... Strong luminescence could be visually confirmed. B... Normal luminescence could be visually confirmed. C... Weak luminescence could be visually confirmed. D... Luminescence could not be visually confirmed.

[0120]

Table 2

[0121] As shown in Table 2, in the label of Experimental Example 1, strong luminescence could be visually confirmed from each of the front side and the back side.

[0122] <Experimental Example 2> (Preparation of label) In Experimental Example 2, a label 11a (label of Experimental Example 2) having the configuration shown in the schematic cross-sectional view of Fig. 6 was prepared. The label of Experimental Example 2 was prepared as follows.

[0123] First, as the base material 101, a PET film with a thickness of 20 μm was prepared. Next, using a gravure coater, a composition for forming the coating layer 102a was applied onto one surface of the PET film and then solidified to form the coating layer 102a.

[0124] Note that the composition for forming the coat layer 102 is composed only of the compositions having the compositions shown in Table 1 above, and no phosphorescent ink was added.

[0125] Next, an ink resin composition containing Etna red as ink was applied onto the coat 102a layer using a gravure coater and then solidified to form a color layer 103a.

[0126] Next, an ink resin composition in which 5 parts by mass of phosphorescent ink (NT Highlmic (NF) phosphorescent green) was added to 100 parts by mass of white ink (NT Highlmic (NF) 701 white) was applied onto the color layer 103a layer using a gravure coater and then solidified to form a white ink layer 103c.

[0127] Thereafter, medium was applied onto the white ink 103c using a gravure coater and then solidified to form an overcoat layer 104. Thus, the label of Experimental Example 2 was produced.

[0128] (Evaluation of Luminescence) The label of Experimental Example 2 was irradiated with ultraviolet light in the same manner and under the same conditions as the label of Experimental Example 1, and the luminescence of the label of Experimental Example 2 was evaluated according to the same method and the same evaluation criteria as the label of Experimental Example 1. The results are shown in Table 3.

[0129]

Table 3

[0130] As shown in Table 3, in the label of Experimental Example 2, weak luminescence could be visually confirmed from the front side, and normal-level luminescence could be visually confirmed from the back side.

[0131] <Experimental Example 3> After applying an ink resin composition obtained by adding 10 parts by mass of a phosphorescent ink (NT High Lamic (NF) Phosphorescent Green) to 100 parts by mass of a white ink (NT High Lamic (NF) 701 White) on the color layer 103a layer and then solidifying it, a label for Experimental Example 3 was produced in the same manner and under the same conditions as the label for Experimental Example 2, except that a white ink layer 103c was formed.

[0132] Thereafter, the label for Experimental Example 3 was irradiated with ultraviolet light in the same manner and under the same conditions as the labels for Experimental Examples 1 to 2, and the luminescence of the label for Experimental Example 3 was evaluated in the same manner and according to the same evaluation criteria as the labels for Experimental Examples 1 to 2. The results are shown in Table 4.

[0133]

Table 4

[0134] As shown in Table 4, in the label for Experimental Example 3, weak luminescence could be visually confirmed from the front side, and luminescence above the normal level could be visually confirmed from the back side. In particular, as shown in Table 4, when the ultraviolet light irradiation surface was on the back side, strong luminescence could be visually confirmed from the back side.

[0135] <Experimental Example 4> After applying an ink resin composition obtained by adding 20 parts by mass of a phosphorescent ink (NT High Lamic (NF) Phosphorescent Green) to 100 parts by mass of a white ink (NT High Lamic (NF) 701 White) on the color layer 103a layer and then solidifying it, a label for Experimental Example 4 was produced in the same manner and under the same conditions as the labels for Experimental Examples 2 to 3, except that a white ink layer 103c was formed.

[0136] Thereafter, the label for Experimental Example 4 was irradiated with ultraviolet light in the same manner and under the same conditions as the labels for Experimental Examples 1 to 3, and the luminescence of the label for Experimental Example 4 was evaluated in the same manner and according to the same evaluation criteria as the labels for Experimental Examples 1 to 3. The results are shown in Table 5.

[0137]

Table 5

[0138] As shown in Table 5, in the label of Experimental Example 4, normal-level light emission could be visually confirmed from the front side, but strong light emission could be visually confirmed from the back side.

[0139] <Evaluation of Light Emission of Labels in Experimental Examples 1 to 4> The label of Experimental Example 1 prepared by incorporating 5 parts by mass of the phosphorescent ink into the coating layer 102 showed strong light emission from both the front side and the back side as compared with the labels of Experimental Examples 2 to 4 prepared by incorporating 5 to 20 parts by mass of the phosphorescent ink into the white ink layer 103c. This indicates that when sorting the labels for removing the ink layer by alkali desorption, it is more preferable to incorporate the phosphorescent ink into the coating layer between the base material and the ink layer rather than into the ink layer on the coating layer. Further, when the coating layer contains the phosphorescent ink, a small amount of the ink can provide strong light emission as compared with the case where the ink layer contains the phosphorescent ink, so that the use of the expensive phosphorescent ink can be reduced. This is considered to enable more efficiently removing the ink layer from the label from the viewpoint of cost.

[0140] Although the embodiments and experimental examples have been described as above, appropriate combinations of the respective configurations of the above-described embodiments and experimental examples have also been planned from the beginning.

[0141] The embodiments and experimental examples disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. are intended.

Explanation of Reference Numerals

[0142] 10 PET bottle, 11, 11a label, 12 collection box, 20 veiled label, 30 recycling factory, 40 normal label, 50 label group, 60 warm water, 61 hot air tunnel, 62 warm water tank, 70 crusher, 71 label piece, 80 alkaline aqueous solution, 82 hot alkaline tank, 90 first net, 92 second net, 93 ink coating, 101 base material, 102 coat layer, 103 ink layer, 103a color layer, 103b, 103c white ink layer, 104 overcoat layer, 201 first dark place, 202 second dark place

Claims

1. A base material, an alkali-soluble coat layer on the base material, and an ink layer on the coat layer, wherein the coat layer or the ink layer contains a material that emits light when irradiated with energy rays, and the label is a label capable of identifying and sorting the label provided with the alkali-soluble coat layer by the coat layer or the ink layer emitting light when the label is irradiated with the energy rays.

2. A base material, an alkali-soluble coat layer on the base material, and an ink layer on the coat layer, wherein the coat layer or the ink layer contains a material that emits light when irradiated with energy rays, and the label is a label capable of being attached to a PET bottle.

3. The label according to claim 1 or claim 2, wherein the coat layer contains a material that emits light when irradiated with energy rays.

4. The alkali-soluble coat layer contains a first acrylic acid copolymer resin and a second acrylic acid copolymer resin, and the apparent acid value of the coat layer is 40 mgKOH / g or more and 150 mgKOH / g or less. The label according to claim 1 or claim 2.

5. A step of collecting a group of labels including a label containing a material that emits light when irradiated with energy rays and capable of removing the ink layer by alkali desorption, a step of irradiating the collected group of labels with energy rays, a step of sorting the labels that have emitted light by irradiating the energy rays, and a step of removing the ink layer from the sorted labels by alkali desorption. A method for removing an ink layer from a label.

6. The method for removing an ink layer from a label according to claim 5, further including a step of crushing the labels sorted before the step of removing by alkali desorption.

7. A method for manufacturing a label, which includes, as a raw material, a resin derived from a label obtained by the removal method according to claim 5.

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