WO2021246230A1

WO2021246230A1 - Label, method for removing ink layer from label, and method for manufacturing label

Info

Publication number: WO2021246230A1
Application number: PCT/JP2021/019690
Authority: WO
Inventors: 彰宮崎; 勇馬平戸
Original assignee: 株式会社フジシールインターナショナル
Priority date: 2020-06-04
Filing date: 2021-05-25
Publication date: 2021-12-09
Also published as: JPWO2021246230A1

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

Labels, methods of removing ink layers from labels, and methods of manufacturing labels

The present disclosure relates to labels, a method for removing an ink layer from a label, and a method for manufacturing a label.

In recent years, plastic products such as polyethylene terephthalate bottles (PET bottles) have been widely used. From the viewpoint of resource saving and environmental viewpoint, it is strongly required to reuse plastic products such as PET bottles.

Among plastic products, 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.

One of the factors that hinders 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 is mixed in the recycled resin recycled from the label, and it is not possible to produce a recycled product such as pellets having utility value from the recycled resin. Sometimes.

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 alkaline aqueous solution. In Patent Document 1, the display printing ink layer is alkaline-desorbed by dissolving the coat layer of the plastic label in an alkaline aqueous solution.

Japanese Unexamined Patent Publication No. 2004-240029

When actually reusing the label, it is assumed that the label that can desorb the alkali of the ink layer and the label that cannot desorb the alkali of the ink layer are mixed and collected. When reusing a label, a technique for separating a label capable of desorbing alkali from an ink layer and a label capable of desorbing alkali from an ink layer has not yet been established.

Even if the ink layer is desorbed with a mixture of labels that can desorb alkali from the ink layer and labels that cannot desorb alkali from the ink layer, the alkali in the ink layer is desorbed after the alkali is removed from the ink layer. Since it is necessary to remove labels that cannot be removed, there is a demand for an efficient method for removing the ink layer.

According to the embodiments disclosed herein, a substrate, an alkali-soluble coat layer on the substrate, and an ink layer on the coat layer are provided, and the coat layer or the ink layer is irradiated with energy rays. Can provide a label containing a material that emits light.

According to the embodiment disclosed here, a step of recovering a label group including a label containing a material that emits light when irradiated with energy rays and a label capable of removing an ink layer by alkali desorption, and a recovered label. The ink layer from the label includes a step of irradiating the group with energy rays, a step of separating the label emitted by irradiating the energy rays, and a step of removing the ink layer from the separated labels by alkaline desorption. A method of removing the ink can be provided.

According to the embodiment disclosed here, it is possible to provide a method for producing a label containing a resin derived from the label obtained by the above removing method as a raw material.

According to the embodiment disclosed here, a label capable of efficiently removing the ink layer, a method for removing the ink layer from the label, and a label using a resin containing the label from which the ink layer has been removed as a raw material. Production method can be provided.

It is a schematic cross-sectional view of the label of an embodiment. (A) to (i) are diagrams illustrating an example of a flow of a method for removing an ink layer from a label according to an embodiment. It is a schematic side view which illustrates an example of the process of irradiating the recovered label group with energy rays. It is a schematic cross-sectional view of the label of Experimental Example 1. FIG. It is a schematic side view which illustrates the evaluation method of the light emission of the label of Experimental Example 1. FIG. It is a schematic cross-sectional view of the label of Experimental Examples 2-4.

<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 shrinkage (shrink label) or a label having no heat shrinkage. Further, the label 11 of the embodiment may be a stretch label having self-stretchability or a label having no self-stretchability.

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

Examples of the resin contained in the base material 101 include polyester resins (polyethylene terephthalate, polyethylene naphthalate, polylactic acid, etc.), polystyrene resins (polystyrene, styrene-butadiene copolymer, etc.), and polyolefin resins (polyethylene, polypropylene, etc.). Etc.), Polyvinyl chloride resin, polyamide resin, aramid resin, polyimide resin, polyphenylene sulfide resin, acrylic resin and the like can be used. The base material 101 may contain one kind of these resins, or may contain two or more kinds of these resins.

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

The base material 101 may be, for example, a film having heat shrinkage (shrink film). When the base material 101 is a shrink film, the processability (followability to the container) and the 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.

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

<Coat layer>
The coat layer 102 is located between the base material 101 and the ink layer 103, and is a layer containing an alkali-soluble resin.

The fact that the coat layer 102 has alkali solubility means that a coat layer 102 having a size of 4 cm × 4 cm in length × width is formed on a substrate 101 of an arbitrary size, and an arbitrary ink is formed on the coat layer 102. The sample provided with the layer 103 was immersed in a 1.5% by mass sodium hydroxide aqueous solution at 85 ° C. (that is, 1.5% of the total mass of the sodium hydroxide aqueous solution was sodium hydroxide) and stirred at 1500 rpm. In this case, it means that 70% or more of the total area of the ink layer 103 is desorbed from the sample in the immersion time of 15 minutes.

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 occupy 50 to 95% by mass of the entire coat layer 102 in total.

The resin comprising the above (1) to (4) has good alkali solubility. Therefore, when the label 11 is provided with the coat layer 102 having alkali solubility between the base material 101 and the ink layer 103, the ink layer 103 is also removed from the label 11 with the alkali removal of the coat layer 102 from the label 11. Detach.

Further, the resin provided with the above (1) to (4) is excellent in printability in addition to the above-mentioned alkali solubility. Along with this, the cosmeticity of the ink layer 103 on the coat layer 102 can be enhanced.

As shown in the above (1) and (2), the first resin and the second resin are acrylic acid copolymer resins, respectively. The acrylic acid copolymer resin is a resin containing acrylic acid and / or methacrylic acid as a main repeating unit and a copolymerizable monomer copolymerizable with acrylic acid and / or methacrylic acid. The acrylic acid copolymer resin preferably has a total ratio of acrylic acid and / or methacrylic acid and a copolymerized monomer in the resin of 60 mol% or more.

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

Regarding the above (1) and (2), each Tg of the first resin and the second resin can be controlled by, for example, 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 a 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.

Regarding the above (1) and (2), T1 which is 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 of T1 can be, for example, about 120 ° C. due to the physical properties of the acrylic acid copolymer resin. The T2 of the second resin, which is Tg, is preferably less than 80 ° C, more preferably 75 ° C or lower, and particularly preferably 65 ° C or lower. The lower limit of T2 can be, for example, about 30 ° C. from the viewpoint of ease of handling. For example, T1 and T2 preferably have a difference of 20 ° C. or higher, more preferably a difference of 30 ° C. or higher, and particularly preferably a difference of 40 ° C. or higher. In this case, the deterioration of printability can be suppressed more effectively, so that the cosmeticity of the ink layer 103 can be particularly improved.

Regarding (3) above, 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 values 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.

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

The acid value of the first resin and the acid value of the second resin are preferably 40 mgKOH / g or more and 150 mgKOH / g or less, respectively. In this case, the apparent acid value of the coat layer 102 can be easily set to 40 mgKOH / g or more and 150 mgKOH / g or less as described in (3) above. 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. The acid value of the second resin is preferably 80 mgKOH / g or more.

With respect to the above (4), the first resin and the second resin in the coat layer 102 preferably occupy 70% by mass or more and 95% by mass or less of the

entire coat layer

102, and 80% by mass or more and 95% by mass or less. It is more preferable to occupy. In these cases, it becomes possible to particularly improve the alkali solubility and printability of the coat layer 102. Further, it is preferable that the content ratio of the first resin and the content ratio of the second resin do not differ significantly. From the viewpoint of improving the synergistic effect of containing 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 (relatively large content). The content of the resin / the content of the resin having a relatively small content) is preferably 3 or less.

It can be confirmed by using various analytical techniques, for example, that the coat layer 102 contains an alkali-soluble resin. For example, by nuclear magnetic resonance (NMR), gas chromatography-mass spectrometer (GCMS), pyrolysis gas chromatography (pyrolysis GCMS), etc., the acrylic acid copolymer resin is present in the coat layer 102 at a specific content. You can confirm that. Further, the acid value of the coat layer 102 can be confirmed, for example, by titrating the coat layer 102. For titration of the coat layer 102, for example, the coat layer 102 is dissolved in a titration solvent such as a mixed solvent of xylene and dimethylformamide, and a potassium hydroxide solution having a predetermined concentration (for example, a 0.1 mol / L potassium hydroxide / ethanol solution) is used. It can be calculated based on the result of potentiometric titration using. Further, the fact that the coat layer 102 contains the first resin and the second resin containing the above Tg means that, for example, the composition used for forming the coat layer described later is subjected to a differential scanning calorimetry (DSC) method. Can be confirmed by. The DSC method can be carried out using "DSC6200" manufactured by Seiko Instruments Co., Ltd. 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 by, for example, gel permeation chromatography (GPC).

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, both the alkali solubility and printability of the coat layer 102 can be remarkably improved. The MM copolymer may be synthesized or may be a commercially available product. Examples of commercially available products suitable for the first resin include "Dianal LR-1941" and "Dianal BR-87" manufactured by Mitsubishi Rayon. Examples of commercially available products suitable for the second resin include "JONCRYL JDX-C3000" manufactured by BASF Japan Ltd., "ARUFON UC3000" manufactured by Toagosei Co., Ltd., and "BR-605" manufactured by Mitsubishi Rayon Co., Ltd. Will be. Among them, as the first resin and the second resin, it is preferable to use a combination of "Dianar LR-1941" and "JONCRYL JDX-C3000".

The coat layer 102 may contain other components in addition to the first resin and the second resin. Other preferred components include cellulose derivatives. When the coat layer 102 contains a cellulose derivative, it is possible to improve the blocking resistance, adhesion and the like of the coat layer 102.

Examples of the cellulose derivative contained in the coat layer 102 include nitrocellulose, acetylcellulose, carboxymethylcellulose or a salt thereof, methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, cellulose acetate butyrate, cellulose acetate propionate and the like. Can be used. It is preferable to use nitrocellulose as the cellulose derivative contained in the coat layer 102. In the coat layer 102, the cellulose derivative can be used alone or in combination of two or more.

The content of the cellulose derivative in the coat 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 8% by mass, based on the total mass of the coat layer 102. It is particularly preferable that the content is 12% by mass or less. In these cases, the blocking resistance and printability of the coat 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. In these cases as well, it is possible to improve the blocking resistance and printability of the coat layer 102.

Further, the coat layer 102 may contain, for example, a vinyl chloride-vinyl acetate copolymer (hereinafter, also referred to as “VV copolymer”) as another preferable component. When the coat layer 102 contains the VV copolymer, 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 the alkali-soluble resin and the VV copolymer, it can function as a base layer having particularly excellent adhesion.

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 9 to 12% by mass, based on the total mass of the coat layer 3. Is particularly preferred. 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 an Mm of 10,000 to 40,000, more preferably 15,000 to 35,000. In these cases, the improvement of the adhesion of the coat layer 102 becomes remarkable.

The coat layer 102 may further contain a material that emits light when irradiated with energy rays. As a result, the label 11 is irradiated with energy rays, and the coat layer 102 of the label 11 emits light, so that the label 11 of the embodiment provided with the alkali-soluble coat layer 102 can be identified and separated.

As the energy rays irradiated to the label 11, for example, short-wavelength electromagnetic waves such as X-rays or ultraviolet light, visible light, infrared light, near-infrared light, microwaves, or the like can be used. It is preferable to use ultraviolet light as the energy ray irradiated to the label 11. When ultraviolet light is used as the energy ray to be irradiated on the label 11, the irradiation of the energy ray tends to cause electronic excitation of the material that emits light.

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

Fluorescent pigments are pigments that emit light when irradiated with energy rays, but pigments with phosphorescent properties are excluded from fluorescent pigments. Examples of the fluorescent pigment include organic pigments and inorganic pigments. Examples of the organic pigment include fluorescein-based, coumarin-based, rhodamine-based, oxazole-based, pyrazoline-based, thiadiazole-based, spiropyran-based, pyrenesulfonic acid-based, benzimidazole-based, and diaminostylben-based. Examples of the inorganic pigment include zinc sulfide activated by copper, silver, manganese, etc., zinc silicate activated by manganese, calcium sulfide activated by cadmium, bismuth, etc., strontium sulfide activated by samarium, cerium, etc. , Calcium tungstate activated with lead or the like, and the like.

More specifically, examples of the red fluorescent pigment include, for example, Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, Y ₂ SiO ₅ : Eu, Y ₃ AlO ₁₂ : Eu, Zn ₃ (PO ₄ ). ₂ : Mn, YBO ₃ : Eu, (Y, Gd) BO ₃ : Eu, GdBO ₃ : Eu, ScBO ₃ : Eu, LuBO ₃ : Eu and the like can be used.

As the blue fluorescent pigment, for example, BaMg ₂ Al ₁₆ O ₂₇ : Eu, Y ₂ SiO ₅ : Ce, CaWO ₄ : Pb, _{BaMg Al 14} O ₂₃ : Eu, or the like can be used.

Examples of the green fluorescent pigment include BaMg ₂ Al ₁₆ O ₂₇ : (Eu, Mn), (Ba, Mg) Al ₁₆ O ₂₇ : (Eu, Mn), Zn ₂ SiO ₄ : Mn, BaAl ₁₂ O ₁₉ :. _{_{_{Mn, SrAl 13 O 19: Mn}}} , CaAl 12 O 19: Mn, YBO 3: Tb, BaMgAl 14 O 23: Mn, LuBO 3: Tb, GdBO 3: Tb, ScBO 3: Tb , or _Sr 6 _Si _{3 O} 3, C ₁₄ : Eu or the like can be used.

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

The phosphorescent pigment is a pigment having a phosphorescent property among the pigments that emit light when irradiated with energy rays. As the phosphorescent pigment, for example, a sulfide-based phosphorescent pigment, an oxygen salt-based phosphorescent pigment, an alumina oxide-based phosphorescent pigment, or the like can be used.

Examples of the sulfide-based phosphorescent pigment include calcium sulfide: bismuth-based (CaS: Bi), calcium sulfide / strontium: bismus-based (CaSrS: Bi), zinc sulfide: copper-based (ZnS: Cu), or zinc sulfide / cadmium. : Copper-based (ZnCdS: Cu) or the like can be used.

Oxygen acid phosphate-based phosphorescent pigments include, for example, Zn ₂ SiO ₄ : Mn, (Zn, Be) ₂ SiO ₄ : Mn, Ca ₃ (PO ₄ ) ₂ : Ce, or Ca ₃ (PO ₄ _{) 2} : (Ce). , Mn) and the like can be used.

Examples of the alumina oxide-based phosphorescent pigment include aluminum oxide / calcium: europium (CaAl ₂ O ₄ : Eu), aluminum oxide / strontium: europium (SrAl ₂ O ₄ : Eu), and aluminum oxide / barium: europium. A system (BaAl ₂ O ₄ : Eu) or the like can be used.

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

The coat layer 102 may contain other components in addition to the above, for the purpose of improving printability and the like. For example, when the coat layer 102 contains the first resin, the second resin, the VV copolymer, and the cellulose derivative in predetermined content ratios, the total content ratio of each component x the acid value of each resin is calculated. , The apparent acid value of the coat layer 102.

The thickness of the coat 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.

<Ink layer>
The ink layer 103 is located on the coat layer 102 and contains 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 print layer. The design print layer is a layer that contains a pigment and displays a visible pattern or character.

The ink layer 103 may be provided on the entire surface of the coat layer 102, or may be provided on a part of the coat layer 102. Further, the ink layer 103 may be a single layer or a multilayer. 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.

The ink layer 103 may further contain a material that emits light when irradiated with energy rays. As a result, the label 11 is irradiated with energy rays and the ink layer 103 of the label 11 emits light, so that the label 11 of the embodiment provided with the alkali-soluble coat layer 102 can be identified and separated.

<Other layers>
The label 11 may further include another layer 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.

<Label manufacturing method>
The label 11 of the embodiment can be manufactured, for example, as follows. First, the base material 101 is prepared. The base material 101 can be prepared by, for example, forming a film by a method such as an extrusion method or a calendar method, and if necessary, further subjecting the film to a stretching treatment.

Next, the 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 onto one surface of the base material 101 and then solidifying the composition.

Next, the 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 the ink layer 103.

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

<How to remove the ink layer from the label>
2 (a) to 2 (i) show an example of a flow of a method of removing an ink layer from a label of an embodiment when the label 11 of the embodiment is a shrink label. Hereinafter, a method of removing the ink layer from the label 11 of the embodiment will be described with reference to FIGS. 2 (a) to 2 (i).

<PET bottle collection process>
First, as shown in FIG. 2A, the PET bottle 10 is collected in the collection box 12. Here, the label 11 of the embodiment provided with the 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 displaying products and the like.

<Compression process>
Next, as shown in FIG. 2B, the collected PET bottle 10 is compressed with the label 11 attached to obtain a labeled bale 20.

<Integration process>
Next, as shown in FIG. 2 (c), the labeled veil 20 is sent to the recycling plant 30 and accumulated.

<Label group collection process>
Next, as shown in FIG. 2D, the label group 50 including the label 11 of the embodiment and the normal label 40 is collected. The label group 50 can be collected, for example, as follows.

First, at the recycling plant 30, the label 11 and / or the normal label 40 of the embodiment is removed from the PET bottle 10 of the labeled veil 20 to form a label group 50 including the label 11 of the embodiment and the normal label 40. , PET bottle 10 and the label group 50 including the label 11 of the embodiment and the normal label 40 are collected.

In the present embodiment, the normal label 40 is a label in which alkali desorption of the ink layer is not possible because the coat layer or the ink layer is not alkali-soluble, and emits light when irradiated with energy rays. It is a label that does not contain the material to be used.

Further, the PET bottle 10 from which the label 11 and / or the normal label 40 is separated is reused in the recycling process of the existing PET bottle.

<Energy ray irradiation / separation 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 a process of irradiating the recovered label group 50 with energy rays. Hereinafter, an example of a step of irradiating the recovered label group 50 with energy rays will be described with reference to FIG.

First, the collected label group 50 is carried into the inside of the first dark place 201. Next, the energy rays 22 are applied to the label group 50 from the light source 21 arranged inside the first dark place 201.

Next, the label group 50 after irradiation with the energy ray 22 is carried out from the inside of the first dark place 201. Next, the label group 50 carried out from the inside of the first dark place 201 is carried into the inside of the second dark place 202.

At this time, since the coat layer 102 of the label 11 of the embodiment after irradiation with the energy ray 22 emits light, the label 11 of the embodiment appears to shine inside the second dark place 202. On the other hand, since the normal label 40 does not contain a material that emits light when irradiated with energy rays, even if the energy rays 22 are irradiated, the label 40 does not shine inside the second dark place 202.

This makes it possible to separate and collect the label 11 of the embodiment that appears to shine inside the second dark place 202 from the normal label 40 that does not shine inside the second dark place 202. The normal label 40 separately collected from the label 11 of the embodiment is reused, for example, in a thermal recycling process.

In the present embodiment, the irradiation of the energy ray 22 to the label group 50 is performed inside the first dark place 201, but the irradiation of the energy ray 22 to the label group 50 does not necessarily have to be performed in a dark place.

<Preheating process>
Next, as shown in FIG. 2 (f), the label 11 which is a shrink label is preheated. The method for 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 desorption described later. However, it is preferable that the preheating temperature is the same as the alkali desorption temperature or higher than the alkali desorption temperature. From the viewpoint of efficiently removing the ink layer from the label piece in the alkali desorption described later, the preheating temperature is preferably 5 ° C. or higher higher than the alkali desorption temperature.

Examples of the method of preheating the label 11 include a method of passing the label 11 through the hot air tunnel 61 and a method of immersing the label 11 in the hot water 60 in the hot water tank 62.

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

For example, when the label 11 is preheated by immersing the label 11 in the hot water 60 in the hot water tank 62, for example, the label 11 is immersed in hot water of about 80 ° C. to 90 ° C. for about 10 seconds to 20 seconds. Can be done by.

The preheating temperature means that it is the surface temperature of the label 11 at the time of preheating. Therefore, when the label 11 is preheated by immersing the label 11 in the hot water 60 in the hot water tank 62, the temperature of the preheating can be replaced with the temperature of the hot water. Further, when the label 11 is preheated by passing the label 11 through the hot air tunnel 61, the temperature of the preheating can be replaced with the temperature of the hot air.

<Crushing process>
Next, as shown in FIG. 1 (g), the label 11 after preheating is crushed by a crusher 70 to prepare a label piece 71. The method for crushing the label 11 after preheating is not particularly limited as long as the size of the label piece 71 produced after the crushing is smaller than the size of the label 11 after preheating. For example, the label 11 after preheating can be crushed to a size (for example, several cm square) that can efficiently remove the ink layer 103 from the label piece 71 in the alkali desorption described later. Since the label piece 71 is obtained by crushing the label 11 of the embodiment, it goes without saying that the layer structure of the label 11 of the embodiment and the layer structure of the label piece 71 are the same.

<Alkaline desorption process>
Next, as shown in FIG. 1 (h), the ink layer 103 is removed from the label piece 71 by alkaline desorption. The alkali desorption is performed, for example, by immersing the label piece 71 in the alkaline aqueous solution 80 at about 80 ° C. to 90 ° C. in the hot alkaline tank 82 for about 30 seconds to 20 minutes and stirring the inside of the hot alkaline tank 82. be able to. In this case, the label piece 21 can be easily separated into the base material 101 and the ink coating film 93 in the thermal alkali tank 82. Further, the alkali desorption can be performed, for example, by immersing the label piece 71 in the above-mentioned alkaline aqueous solution 80 for about 30 seconds to 20 minutes and then washing with water. In this case, the label piece 71 can be easily separated into the base material 101 and the ink coating film 93 by washing with water (for example, in a water tank). Further, a surfactant may be added to the alkaline aqueous solution 80 for the purpose of further improving the desorption property.

As described above, in the present embodiment, the temperature of the preheating is set to be the same as the temperature of the alkali desorption or higher than the temperature of the alkali desorption. The alkali desorption temperature means that it is the surface temperature of the label piece 71 at the time of alkali desorption. Therefore, the temperature of the alkali desorption 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 the alkali desorption, the alkali desorption temperature is preferably 65 ° C. or higher. The upper limit of the alkali desorption temperature is theoretically 100 ° C., more preferably the alkali desorption temperature is 85 ° C. or higher and 95 ° C. or lower, and further preferably the alkali desorption temperature is 80 ° C. or higher and 90 ° C. It is as follows.

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

The alkaline aqueous solution 80 is not particularly limited as long as it is possible to remove the ink layer 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. Examples of the alkaline aqueous solution 80 include 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 (Na 2} CO _{3), and hydrogen carbonate.} An aqueous solution of an alkali metal hydrogen carbonate such as sodium (NaHCO ₃ ), aqueous ammonia, or the like can be used.

The concentration of the alkaline substance in the alkaline aqueous solution 80 can be appropriately selected within a range that does not impair the desorption 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 about 0.5 to 5% by weight, and more preferably about 1 to 3% by weight.

<Separation process between base material and ink coating>
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 is performed, for example, by collecting the base material 101 after the ink layer 103 is removed by the first net 90 having a relatively large opening and having a relatively small opening. This can be done by collecting the ink coating film 93 smaller than the base material 101 with the second net 92 having the above. As described above, the ink layer 103 can be removed from the label 11 of the embodiment. The ink coating film 93 is a film in which the ink layer 103 removed from the base material 101 at the time of alkali desorption is finely divided.

After that, the base material 101 collected by the first net 90 can be reused as a plastic raw material for manufacturing plastic products such as pellets. Further, by mixing the base material 101 with the raw material of the 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 net 92 can be reused, for example, in a thermal recycling process.

The method for removing the ink layer from the label of the embodiment is a step of recovering the label group 50 including the label 11 containing a material that emits light when the energy ray 22 is irradiated, and a step of recovering the energy ray 22 to the recovered label group 50. It includes a step of irradiating and a step of separating the light-emitting label 11 by irradiating the energy ray 22.

Therefore, according to the method for removing the ink layer from the label of the embodiment, the label 11 capable of removing the ink layer 103 by alkali desorption by irradiating the energy ray 22 to emit light is desorbed from the ink layer. It is possible to establish a technique capable of separating the 103 from the normal label 40, which cannot be removed.

This makes it possible to de-alkali the ink layer only for labels that can de-alkali the ink layer, and it is necessary to remove the labels that cannot de-alkali the ink layer after the de-alkali of the ink layer. There is no. Therefore, the alkali of the ink layer can be efficiently desorbed from the label capable of desorbing the alkali of the ink layer.

Further, 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, and a step of crushing the label 11 to produce a label piece 71 after the preheating step. The step of removing the ink layer 103 from the label piece 71 by desorption of alkali is included, and the temperature of the preheating can be the same as the temperature of desorption of alkali or higher than the temperature of desorption of alkali.

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.

That is, in the method for removing the ink layer from the label of the present embodiment, the label 11 is crushed into a label piece 71 prior to removing the ink layer 103 from the label 11 by alkali desorption. This is because the ink layer 103 can be efficiently removed from the label 11 by crushing the label 11 to form a smaller label piece 71 and removing the alkali from the label 11.

When a shrink label piece made by crushing a shrink label that has not been preheated is immersed in an alkaline aqueous solution, the shrink label piece wraps around and shrinks while curling in the alkaline aqueous solution. It is very difficult to remove the ink layer from the shrink label pieces, which are curled pieces.

The shrink label attached to the PET bottle etc. was heat-shrinked once at the time of attachment, but the shrinkage ability still remains in the shrink label. Therefore, when the temperature of the alkaline aqueous solution at the time of alkali desorption is high, the shrink label piece further heat-shrinks. 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.

Therefore, in the method for removing the ink layer from the label of the present embodiment, the shrink label is preheated at a temperature equal to or higher than the temperature of alkali desorption before the shrink label is crushed into a shrink label piece. Is performed and heat-shrinked in advance. Then, the shape of the shrink label can be made into a wavy shape with a small degree of curl, for example. If the shrink label is preheated after crushing the shrink label, the shrink label piece will be curled (rolled up) as a whole, which is unsuitable for removing the ink layer.

Then, the shrink label that has been heat-shrinked in advance by preheating is crushed into a shrink label piece. A shrink label piece obtained by crushing a shrink label having a small degree of curl also has a small degree of curl.

After that, such shrink label pieces can be subjected to alkali desorption at the same temperature as or lower than the preheating. In this case, even when the temperature of the alkaline aqueous solution at the time of alkali desorption is high, the ink layer can be removed in a state where the shrinkage of the shrink label piece at the time of alkali desorption is suppressed.

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, the ink layer can be removed from the label 11 more efficiently than before. Conceivable.

In particular, in general, most of the labels 11 as shrink labels removed from a container such as a PET bottle 10 have a side of 10 cm or more, and the number of labels 11 having such a size after being heat-shrinked by preheating. The efficiency of removing the ink layer 103 is remarkably improved by crushing the ink layer to a cm square, preferably 5 cm square or less, and desorbing the alkali at 65 ° C. or higher, preferably 80 ° C. or higher, more preferably 85 ° C. or higher. Can be done.

As the label 11 as a shrink label suitable for the method of the present embodiment, it was removed from a container such as a PET bottle 10 and immersed in a warm bath at 95 ° C. for 10 seconds, and then measured in the radial direction (main contraction direction) of the container. Examples thereof include shrink labels having a shrinkage rate of 30% or more, preferably 40% or more, and more preferably 50% or more.

In the method of removing the ink layer from the label of the above embodiment, the case where the label 11 is a shrink label has been described, but the label 11 used in the method of removing the ink layer from the label of the embodiment is not a shrink label. You may.

Further, in the method of removing the ink layer from the label of the above-described embodiment, the case where the label 11 in which the material that emits light when irradiated with energy rays is contained only in the coat layer 102 is used has been described. In the method for removing the ink layer from the label, the material that emits light when irradiated with energy rays is at least one layer constituting the label 11 (for example, only the coat layer 102, only the ink layer 103, the coat layer 102, and the ink). It suffices if it is contained in both layers 103).

Further, in the above embodiment, when the ink layer 103 is the above-mentioned design printing layer, it is preferable that only the coat layer 102 contains a material that emits light when the energy rays are irradiated. If the ink layer 103 is composed of a plurality of layers (multicolor design printing layers), the amount of the material that emits light when irradiated with energy rays is contained in each layer constituting the ink layer 103. In addition to being complicated, there may be a problem that the content of the material that emits light due to the irradiation with energy rays needs to be changed in each design print layer. When the ink layer 103 is composed of a plurality of layers (multicolor design printing layers), the ink constituting the white layer among the plurality of layers constituting the ink layer 103 is irradiated with energy rays to emit light. It is preferable to contain the material to be used. In this case, it becomes easy to confirm that the material emits light by irradiating the material that emits light by irradiating the energy ray with the energy ray.

Further, in the above embodiment, when the coat layer 102 contains a material that emits light when irradiated with energy rays, the content of the material that emits light when irradiated with energy rays is the entire content of the coat layer 102. It is preferably 5% by mass or more.

Further, in the above embodiment, when the ink layer 103 contains a material that emits light when irradiated with energy rays, the content of the material that emits light when irradiated with energy rays is the entire ink layer 103. It is preferably 5% by mass or more.

<Label manufacturing method>
The label 11 obtained by the above-mentioned ink layer removing method can also be used to produce pellets and the like. By manufacturing the label using the pellets or the like, it is possible to manufacture a label (recycled label) using the resin derived from the label 11 obtained by the above-mentioned method for removing the ink layer as a raw material.

<Experimental Example 1>
(Making a 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 produced. The label of Experimental Example 1 was prepared as follows.

First, a polyethylene terephthalate film (PET film) having a thickness of 20 μm was prepared as the base material 101. Next, the coat layer 102 was formed by applying the composition for forming the coat layer 102 on one surface of the PET film using a gravure calibrator and then solidifying the composition.

The composition for forming the coat layer 102 is prepared by adding 5 parts by mass of phosphorescent ink (NT high-ramic (NF) phosphorescent green) to 100 parts by mass of the composition having the composition shown in Table 1 below. did.

Next, using a gravure calibrator, an ink resin composition containing etona red as ink was applied onto the coat 102 layer and then solidified to form a color layer 103a.

Next, a white ink layer 103b was formed by applying an ink resin composition containing white ink (NT High Ramic (NF) 701 white) on the color layer 103a using a gravure calibrator and then solidifying the ink resin composition.

After that, the label of Experimental Example 1 was completed by forming the overcoat layer 104 by applying the medium on the white ink layer 103b and then solidifying it using a gravure calibrator.

(Evaluation of light emission)
By irradiating the label of Experimental Example 1 with ultraviolet light, the emission of the label of Experimental Example 1 was evaluated. FIG. 5 shows a schematic side view illustrating the evaluation method of the light emission of the label of Experimental Example 1.

As shown in FIG. 5, in the evaluation of the light emission of the label of Experimental Example 1, the surface of the label of Experimental Example 1 is irradiated with ultraviolet light 22 from the light source 21 and the light emission is evaluated from the surface side of the label 11 in a dark place. The back surface of the label of Experimental Example 1 was irradiated with ultraviolet light 22 from the light source 21 and the light emission was evaluated from the back surface side of the label 11 (the surface side on which each layer is formed) in a dark place. The light emission on the front surface and the back surface of the label of Experimental Example 1 was evaluated based on the following evaluation criteria. The results are shown in Table 2.

(Evaluation criteria for light emission)
A ... Strong light emission could be visually confirmed B ... Normal level light emission could be visually confirmed C ... Weak light emission could be visually confirmed D ... Light emission could be visually confirmed Could not

As shown in Table 2, in the label of Experimental Example 1, strong light emission from each of the front surface side and the back surface side could be visually confirmed.

<Experimental Example 2>
(Making a 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 produced. The label of Experimental Example 2 was prepared as follows.

First, a PET film having a thickness of 20 μm was prepared as the base material 101. Next, the coat layer 102a was formed by applying the composition for forming the coat layer 102a on one surface of the PET film using a gravure calibrator and then solidifying the composition.

The composition for forming the coat layer 102 was composed only of the compositions having the compositions shown in Table 1 above, and no phosphorescent ink was added.

Next, using a gravure calibrator, an ink resin composition containing Etna crimson as ink was applied onto the coat 102a layer and then solidified to form a color layer 103a.

Next, using a gravure calibrator, 5 parts by mass of phosphorescent ink (NT high-ramic (NF) phosphorescent green) is added to 100 parts by mass of white ink (NT high-ramic (NF) 701 white) on the color layer 103a. The white ink layer 103c was formed by applying the ink resin composition and then solidifying it.

Then, using a gravure calibrator, the overcoat layer 104 was formed by applying the medium on the white ink 103c and then solidifying it. From the above, the label of Experimental Example 2 was prepared.

(Evaluation of light emission)
The label of Experimental Example 2 is irradiated with ultraviolet light by the same method and under the same conditions as the label of Experimental Example 1, and the label of Experimental Example 2 is emitted by the same method and the same evaluation criteria as the label of Experimental Example 1. evaluated. The results are shown in Table 3.

As shown in Table 3, in the label of Experimental Example 2, weak light emission could be visually confirmed from the front surface side, and normal light emission could be visually confirmed from the back surface side.

<Experimental example 3>
After applying an ink resin composition on the color layer 103a, which is obtained by adding 10 parts by mass of phosphorescent ink (NT high-ramic (NF) phosphorescent green) to 100 parts by mass of white ink (NT high-ramic (NF) 701 white). The label of Experimental Example 3 was prepared by the same method and under the same conditions as the label of Experimental Example 2 except that the white ink layer 103c was formed by solidification.

After that, the label of Experimental Example 3 is irradiated with ultraviolet light by the same method as the label of Experimental Examples 1 and 2 and under the same conditions, and the label of Experimental Example 1 and 2 is subjected to the same method and the same evaluation criteria as in Experimental Example. The emission of the label of 3 was evaluated. The results are shown in Table 4.

As shown in Table 4, in the label of Experimental Example 3, weak light emission could be visually confirmed from the front surface side, and light emission higher than normal level could be visually confirmed from the back surface side. In particular, as shown in Table 4, when the ultraviolet light irradiation surface is on the back surface side, strong light emission can be visually confirmed from the back surface side.

<Experimental Example 4>
After applying an ink resin composition on the color layer 103a, which is obtained by adding 20 parts by mass of phosphorescent ink (NT high-ramic (NF) phosphorescent green) to 100 parts by mass of white ink (NT high-ramic (NF) 701 white). The label of Experimental Example 4 was prepared by the same method and under the same conditions as the labels of Experimental Examples 2 and 3 except that the white ink layer 103c was formed by solidification.

After that, the label of Experimental Example 4 is irradiated with ultraviolet light by the same method as the label of Experimental Examples 1 to 3 and under the same conditions, and the label of Experimental Example 1 to 3 is subjected to the same method and the same evaluation criteria as in Experimental Example. The emission of the label of 4 was evaluated. The results are shown in Table 5.

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

<Evaluation of light emission of labels of Experimental Examples 1 to 4>
The label of Experimental Example 1 prepared by containing 5 parts by mass of phosphorescent ink in the coat layer 102 is the label of Experimental Example 2 to 4 prepared by containing 5 to 20 parts by mass of phosphorescent ink in the white ink layer 103c. Compared to the label, strong light emission could be confirmed from each of the front side and the back side. This is contained in the coat layer between the base material and the ink layer rather than containing the phosphorescent ink in the ink layer on the coat layer when separating the label for removing the ink layer by alkali desorption. It shows that it is preferable to let it. Further, when the phosphorescent ink is contained in the coat layer, stronger light emission can be obtained with a small amount as compared with the case where the phosphorescent ink is contained in the ink layer, so that the use of expensive phosphorescent ink can be reduced. This would make it possible to remove the ink layer from the label more efficiently in terms of cost.

Although the embodiments and experimental examples have been described above, it is planned from the beginning to appropriately combine the configurations of the above-mentioned embodiments and experimental examples.

The embodiments and experimental examples disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.

10 PET bottle, 11, 11a label, 12 collection box, 20 labeled veil, 30 recycling factory, 40 normal label, 50 label group, 60 hot water, 61 hot air tunnel, 62 hot 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 1st dark place, 202 2nd dark place

Claims

With the base material
The alkali-soluble coat layer on the substrate and
With an ink layer on the coat layer,
A label, wherein the coat layer or the ink layer contains a material that emits light when irradiated with energy rays.
The label according to claim 1, wherein the coat layer contains a material that emits light when irradiated with energy rays.
The alkali-soluble coat layer contains the first acrylic acid copolymer resin and the second acrylic acid copolymer resin, and contains the first acrylic acid copolymer resin.
The label according to claim 1 or 2, wherein the apparent acid value of the coat layer is 40 mgKOH / g or more and 150 mgKOH / g or less.
A step of recovering a label group containing a material that emits light when irradiated with energy rays and a label whose ink layer can be removed by alkali desorption.
The process of irradiating the collected labels with energy rays and
The step of separating the label emitted by irradiating the energy ray and the process of separating the label.
A method for removing an ink layer from a label, which comprises a step of removing the ink layer from the separated label by alkali desorption.
The method for removing an ink layer from a label according to claim 4, further comprising a step of crushing the separated label before the step of removing by alkali desorption.
A method for producing a label, which comprises a label-derived resin obtained by the removal method according to claim 4 as a raw material.