JP2023051155A - Label, method for separating label, and method for recovering base material from label - Google Patents

Abstract

To provide a label that can easily classify a re-usable label, a method for separating the label, and a method for recovering a base material from the label.SOLUTION: A label (11) includes: a base material (101); a separation layer (102) laminated on the base material (101), the separation layer being separable from the base material (101); an ink layer (105) located in the opposite side of the separation layer (102) to the side where the base material (101) is located, the ink layer including ink; a heat generation unit (104) for generating heat by being irradiated with an energy line.SELECTED DRAWING: Figure 1

Description

The present invention relates to a label, a method of sorting labels, and a method of recovering substrates from labels.

Conventionally, plastic products such as polyethylene terephthalate (PET) bottles have been widely used as beverage containers and the like. From the viewpoint of resource saving and environmental protection, there is a demand for reusing plastic products such as PET bottles.

Among plastic products, the reuse of PET bottles as resin, that is, material recycling, has already become widespread. On the other hand, there are cases where plastic labels with printed product information are attached to the body of PET bottles. The current situation is that

Ink must be efficiently removed from the label in order for the label to be reused for material recycling. For example, Patent Document 1 discloses a label in which a display printing ink layer is formed on a base film via a coating layer soluble in an alkaline aqueous solution. The ink is alkali-desorbed.

JP 2004-240029 A

It is possible to detach and remove the ink from the label by the method described in Patent Document 1. However, before performing the ink-removing treatment, it is necessary to separate the label from which the ink can be removed, that is, the label having the coat layer described above, and the label from which the ink cannot be removed.

An object of one aspect of the present invention is to provide a label capable of easily separating reusable labels, a method for separating labels, and a method for collecting substrates from labels.

A label according to an aspect of the present invention comprises a base material, a separation layer laminated on the base material and separable from the base material, and a separation layer located on the side opposite to the base material side of the separation layer. An ink layer containing ink, and a heat generating portion located on the side opposite to the substrate side of the separation layer and containing a material that generates heat when irradiated with energy rays.

According to one aspect of the present invention, reusable labels can be easily sorted.

1 is a schematic cross-sectional view of a label according to Embodiment 1 of the present invention; FIG. FIG. 2 is a schematic diagram showing an example of the flow of a method for sorting labels and a method for separating substrates according to Embodiment 1. FIG. FIG. 10 is a schematic side view showing an example of a step of irradiating a collected label group with energy rays; FIG. 10 is a schematic cross-sectional view of a label according to Modification 1; FIG. 11 is a schematic cross-sectional view of a label according to modification 2; FIG. 11 is a schematic cross-sectional view of a label according to Modification 3; FIG. 11 is a schematic cross-sectional view of a label according to Modification 4; FIG. 11 is a schematic cross-sectional view of a label according to modification 5; FIG. 8 is a schematic cross-sectional view of a label according to Embodiment 2; FIG. 11 is a schematic cross-sectional view of a label according to Embodiment 3;

Hereinafter, a label, a label, a method for separating the label, and a method for recovering the base material from the label according to embodiments, which are examples of the present disclosure, will be described in detail with reference to the drawings. However, the following description is an example of a label, a method for sorting labels, and a method for recovering substrates from labels according to the present invention, and the technical scope of the present invention is not limited to the illustrated examples.

[Embodiment 1]
<label>
FIG. 1 shows a schematic cross-sectional view of the label 11 of Embodiment 1. As shown in FIG. As shown in FIG. 1, the label 11 includes a base material 101, an alkali-soluble base layer (separation layer) 102 laminated on the base material 101, and an ink layer 105 laminated on the base layer 102. It has The label 11 may be a heat-shrinkable label (shrink label) or a non-heat-shrinkable label. Further, the label 11 may be a stretch label having self-elasticity or may be a label without self-elasticity. As will be described later, the ink layer 105 includes a heat-generating portion 104 containing a material (heat-generating material) that generates heat when irradiated with energy rays, and a non-heat-generating portion 103 that does not contain a heat-generating material and does not generate heat. As shown in FIG. 1, a heat-generating portion 104 having a predetermined width is formed on the surface of a base layer 102, and a non-heat-generating portion 103 is formed so as to surround the heat-generating portion 104. As shown in FIG. The heat generating portion 104 may be formed in a hole or recess formed in the non-heat generating portion 103 . The lower side of the label 11 in FIG. 1 corresponds to the back side of the label 11, and the label 11 is used by covering the surface of a container such as a PET bottle with the back side of the label 11 facing the surface. As will be described later, the label 11 may have an ink layer 105 formed on the front side of the substrate 101 . The non-heat generating portion 103 may generally be transparent.

<Base material>
The substrate 101 is a substrate containing a resin capable of supporting the underlayer 102 and the ink layer 105 . Examples of resins contained in the base material 101 include polyester resins (polyethylene terephthalate (PET), polyethylene naphthalate, polylactic acid, etc.), polystyrene resins (polystyrene, styrene-butadiene copolymer, etc.), polyolefin resins ( polyethylene, polypropylene, etc.), polyvinyl chloride-based resin, polyamide-based resin, aramid-based resin, polyimide-based resin, polyphenylene sulfide-based resin, acrylic resin, or the like can be used. The base material 101 may contain one type of these resins, or may contain two or more types thereof.

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

The substrate 101 may be, for example, a heat-shrinkable film (shrink film). When the base material 101 is a shrink film, the workability (conformability to the container) and decorativeness of the label 11 can be improved. The substrate 101 may also be, for example, a stretch film having self-elasticity.

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

<Underlayer>
The base layer 102 is a layer that is positioned between the substrate 101 and the ink layer 105 and contains an alkali-soluble resin. That the underlying layer 102 has alkali solubility means that the underlying layer 102 dissolves when the underlying layer 102 is immersed in an alkaline aqueous solution. For example, the base layer 102 is formed by forming the base layer 102 with a size of 4 cm × 4 cm square on the substrate 101 of arbitrary size, and providing an arbitrary ink layer 105 on the base layer 102. When the sample is immersed in a 1.5% by mass sodium hydroxide aqueous solution at 85° C. and stirred at 1500 rpm, 70% or more of the total area of the ink layer 105 is detached from the sample after 15 minutes of immersion. It is. Examples of the resin contained in the base layer 102 include acrylic acid copolymer resin. An 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 is preferably a methacrylic acid-methyl methacrylic acid copolymer. The acrylic acid copolymer resin preferably has a total ratio of acrylic acid and/or methacrylic acid and copolymer monomers in the resin of 60 mol % or more.

The thickness of the underlayer 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 105 is a layer that is located on the opposite side of the base layer 102 to the substrate 101 and contains ink. The ink contained in the ink layer 105 may contain pigments, resins, and additives, for example. Moreover, the ink layer 105 is preferably a design printed layer. The design printing layer is a layer that contains pigments and displays visible patterns, characters, or the like. The ink layer 105 may be provided on the entire surface of the underlying layer 102 or may be provided on a part of the underlying layer 102 . Further, the ink layer 105 may be a single layer or multiple layers. The thickness of the ink layer 105 can be, for example, approximately 0.1 μm or more and 30 μm or less, but is not particularly limited. As described above, the ink layer 105 includes the heat-generating portion 104 and the non-heat-generating portion 103 other than the heat-generating portion 104 .

<Exothermic part>
The ink forming the heating portion 104 contains a material that generates heat when irradiated with energy rays.

[Energy Ray]
Energy rays include short-wave electromagnetic waves such as X-rays and ultraviolet light, visible light, infrared light, near-infrared light, and microwaves. The inventors of the present invention have studied a label that can be separated by detecting heat generation by including a base layer that can be removed with an alkaline solution and further including a material that generates heat when irradiated with energy rays. Conventionally, labels have also been sorted by detecting color development caused by irradiation with energy rays such as ultraviolet light. However, since the degree of luminescence is not so strong, it is necessary to include a large amount of material for luminescence in the label, or a high-performance camera is required. On the other hand, when using the heat-generating material described above, the amount used is small and a high-performance camera is not required. Among them, it is preferable to use a material that absorbs energy rays in the microwave region as the heat generating material. Materials used for ordinary design printing are less likely to generate heat when irradiated with energy rays in the microwave region. Therefore, by using a material that absorbs energy rays in the microwave region as the heat generating material, reusable labels and labels that are not suitable for reuse can be distinguished with high accuracy.

[Heat generating material]
Exothermic materials that absorb energy rays in the microwave range include aluminum pigments, carbon black, and conductive polymers such as polythiophene conductive polymers. In particular, since aluminum pigments and carbon black absorb microwaves remarkably, the heat-generating part 104 can generate heat well, and the reusable labels 11 can be sorted well. From the viewpoint of generating heat with a small amount of energy, it is preferable to use a material having a dielectric loss coefficient of 10 or more as the heat generating material. Carbon black having a dielectric loss factor of 100 or more absorbs microwaves more significantly, and is therefore more preferable as a heat generating material. Furthermore, since carbon black is excellent in light resistance, it does not fade before collection of the label 11, unlike the material that emits light under ultraviolet light. Microwaves can reach the heating portion 104 regardless of whether the label 11 is oriented upside down during transportation, so the orientation of the label 11 does not affect the absorption of microwaves. In the case of carbon black, since it has a black color, it can be used for JAN codes, product indications, product descriptions, recycling marks, phototube marks, etc., without spoiling the design. When the heating portion 104 as a part of the label 11 generates heat, it can be easily detected by thermography, so the planar view area of the heating portion 104 may be small. Therefore, the cost of the heating unit 104 such as printing cost is low.

<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 calendering method, and, if necessary, further stretching the film.

Next, a base layer 102 is formed on one surface of the base material 101 . The base layer 102 can be formed, for example, by applying a composition containing a resin, a solvent, and the like contained in the base layer 102 to one surface of the base material 101 and then drying and solidifying the composition.

Next, the non-heat-generating portion 103 and the heat-generating portion 104 are formed as the ink layer 105 on the surface of the base layer 102 . The ink layer 105 includes, for example, ink for forming the non-heat generating portion 103 and a heat generating material, and is formed by applying the ink for forming the heat generating portion 104 to the surface of the base layer 102 and then drying and solidifying the ink. can do. The non-heat generating portion 103 and the heat generating portion 104 may be formed by printing, printing, kneading, or the like. Examples of the printing method include known methods such as gravure printing, flexographic printing, screen printing, and inkjet printing. A plurality of printing methods may be combined.

The non-heat-generating portion 103 and the heat-generating portion 104 may be formed on the surface of the base layer 102 at once, for example, by printing, or may be formed separately. When the non-heat-generating portion 103 and the heat-generating portion 104 are separately formed, the non-heat-generating portion 103 is first formed on the surface of the base layer 102, and then the heat-generating portion 104 is formed on the surface of the base layer 102 where the non-heat-generating portion 103 is not formed. may be formed, or the non-heat-generating portion 103 may be formed after the heat-generating portion 104 is formed on the surface of the base layer 102 .

<How to attach the label>
The label 11 is attached to a container (for example, a PET bottle) and is wrapped around the container so that the printed surface (that is, the side where the ink layer 105 is located) faces the container. Various methods can be adopted as the winding method. For example, when the label 11 is a wrap-around label, one end of the label 11 may be attached to the container, and the other end may be attached to the surface of the one end. When the label 11 is a shrink label, the label 11 may be formed in advance into a cylindrical shape, and the container may be covered with the label 11 to shrink the label 11 .

<Method for separating labels and collecting base materials>
FIG. 2 is a schematic diagram showing an example of the flow of the method for sorting labels and the method for collecting substrates according to the first embodiment. As shown in FIG. 2, the method for separating the ink layer includes a bottle collection step S1, a compression step S2, an accumulation step S3, a label group collection step S4, an energy beam irradiation/separation step (energy beam irradiation step, label Separation step S5, crushing step S6, alkali desorption step S7, and separation step S8 between substrate and ink coating film (substrate separation step: hereinafter referred to as separation step) S8. Hereinafter, each step of the label sorting method and the base material recovery method will be described with reference to FIG. 2 . The steps from S1 to S5 relate to the label sorting method, and the steps from S4 to S6 relate to the base material recovery method.

<Bottle collection process>
As shown in S1 in FIG. 2, used PET bottles (articles) 10 are collected in a collection box 12. As shown in FIG. A label 11 having an alkali-soluble base layer 102 and an ink layer 105 (heat generating portion 104) or a label 40 not including the heat generating portion 104 is attached to the body of the PET bottle 10. FIG.

The article to which the label 11 or the label 40 is attached may be a container other than the PET bottle 10 or various molded articles other than the container. Similarly, the type of label 11 or label 40 is not particularly limited, and may be a shrink label, a wrap label (roll label), a stretch label, or the like.

<Compression process>
As shown in S2 in FIG. 2, the collected PET bottles 10 with the label 11 or label 40 attached thereto are compressed to form a labeled bale 20. As shown in FIG.

<Integration process>
The labeled bales 20 are collected and sent to the recycling plant 30, as shown in S3 of FIG.

<Collecting process of label group>
As shown in S4 of FIG. 2, the label group 50 including the label 11 of Embodiment 1 and the label 40 not including the heating portion 104 is collected. At the recycling plant 30, the label 11 or the label 40 is removed from the PET bottle 10 of the labeled bale 20, the PET bottle 10 is separated from the label group 50 including the label 11 and the label 40, and the label group 50 is collected. As the label 40, a label that does not include the heating portion 104 and does not include the alkali-soluble base layer 102 or the ink layer 105 separable from the substrate 101 is assumed. The PET bottle 10 is reused, for example, in existing recycling processes.

<Energy beam irradiation and separation process>
Next, as shown in S5 in FIG. 2, the collected label group 50 is irradiated with microwaves as energy rays. FIG. 3 shows a schematic side view of an example of the step of irradiating the recovered label group 50 with energy rays. An example of the process of irradiating the collected label group 50 with microwaves will be described below with reference to FIG.

First, the collected label group 50 is carried into the microwave irradiation area 201 . A microwave irradiation unit 21 is arranged in the microwave irradiation area 201 . Microwaves 22 are irradiated from the microwave irradiation unit 21 to the label group 50 . Since the label 11 includes the heating portion 104, it generates heat when irradiated with microwaves. Since the label 40 does not include the heating portion 104, it does not generate heat.

Next, the label group 50 irradiated with the microwave 22 is carried out from the microwave irradiation area 201 and carried into the thermography area 202 . A thermography camera 24 is arranged in the thermography area 202 , and the thermography camera 24 is connected to the image processing device 25 . Examples of the thermography camera 24 include an infrared camera, and examples of the image processing device 25 include a PC (personal computer). An image of the conveyed label group 50 is captured by the thermography camera 24 . The image processing device 25 acquires image data from the thermography camera 24, performs image processing, and displays the temperature distribution of each label 11 or label 40 on the display. When the label 11 is conveyed by the conveyor, it is not affected by microwave absorption and heat generation regardless of whether the label 11 is oriented upside down or upside down, so there is no need to consider the orientation of the label 11 .

Since the heating portion 104 of the label 11 is heated after the microwave irradiation, it is displayed as a red portion on the display of the image processing device 25 . Since the label 40 does not contain a material that generates heat when irradiated with microwaves, it does not have a red portion. Therefore, the label 11 can be recovered separately from the label 40. FIG. Based on the image of the temperature distribution, the labels 11 are sorted manually or by a robot and transported to the crusher 70 described below. The separated labels 40 are transported to, for example, a thermal recycling plant and reused. Note that the microwave irradiation area 201 and the thermography area 202 may be the same area. That is, image data may be acquired by the thermography camera 24 while irradiating the label group 50 with the microwaves 22 .

<Crushing process>
As shown in S6 of FIG. 2, the label 11 is crushed by the crusher 70 to produce the label pieces 71. As shown in FIG. In the crushing step S6, the label 11 is crushed into smaller label pieces 71 prior to removing the ink layer 105 from the label 11 in the subsequent alkali desorption step S7. In this way, the ink layer 105 can be efficiently removed from the label piece 71 in the alkali desorption step S7 by performing the alkali desorption step S7 while the label 11 is made into the smaller label piece 71. .

A method for crushing the label 11 is not particularly limited. The label 11 is crushed into a size (for example, several cm square) that can efficiently remove the ink layer 105 from the label piece 71 in the alkali desorption step S7 described later.

Note that the crushing step S6 is not essential and can be omitted. In this case, the alkali desorption step S7 is performed in the state of the label 11 . In addition, when the label 11 is a shrink label, preheating is performed before the crushing step S6 to suppress the amount of curling of the label piece 71, and the surface of the label piece 71 is well dried in the following alkali desorption step S7. The ink layer 105 may be detached immediately.

<Alkali desorption step>
As shown in S7 of FIG. 2, the ink layer 105 is removed from the label piece 71 by desorption of alkali. Alkali desorption is performed, for example, by stirring the inside of the hot alkali bath 82 while the label piece 71 is immersed in the alkaline aqueous solution 80 of about 80° C. to 90° C. in the hot alkali bath 82 for about 30 seconds to 20 minutes. . In this case, the label piece 71 can be easily separated into the substrate 101 and the ink coating 93 formed from the ink layer 105 in the hot alkali bath 82 . Alkali desorption may be carried out by, for example, immersing the label piece 71 in the alkaline aqueous solution 80 described above for about 30 seconds to 20 minutes and then washing it with water. In this case, the label piece 71 can be easily separated into the substrate 101 and the ink film 93 by washing with water (in a water tank, for example). A surfactant may be added to the alkaline aqueous solution 80 for the purpose of improving the detachability.

The temperature of the alkaline aqueous solution 80 is preferably 65° C. or higher. The temperature for desorption of alkali is preferably 100° C. or lower, more preferably 85° C. or higher and 95° C. or lower, and still more preferably 80° C. or higher and 90° C. or lower. The alkaline aqueous solution 80 after removing the ink layer 105 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 can remove the ink layer 105 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 alkali metal hydrogen carbonate such as sodium (NaHCO ₃ ), or aqueous ammonia 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 detachability, operability, workability, etc. of the ink layer 105 and the heat-generating portion 104 . The concentration of the alkaline substance in the alkaline aqueous solution 80 is, for example, approximately 0.1 to 10% by weight, preferably 0.5 to 5% by weight, and more preferably approximately 1 to 3% by weight. The alkaline aqueous solution 80 may contain a solvent other than water as a solvent. For example, the alkaline aqueous solution 80 may contain, in addition to water, a glycol-based solvent or a high-boiling point solvent (eg, a polymer alcohol-based solvent) as a solvent.

<Separation process>
As shown in S8 in FIG. 2, the film piece 91 and the ink film 93 in the water tank 86 are separated and recovered. For example, a first sieve 90 having relatively large openings collects the film pieces 91 after the ink layer has detached from the label pieces 71, and a second sieve 92 having relatively small openings collects the film pieces 91. Ink coatings 93 smaller than are collected. The ink coating film 93 is a finely divided film of the ink layer 105 removed from the label piece 71 in the alkali desorption step S7.

After that, the film pieces 91 collected by the first sieve 90 can be reused as a plastic raw material for manufacturing plastic products such as pellets. Also, by mixing the film piece 91 into the raw material of a new label, it can be reused as a label. On the other hand, the ink coating 93 collected by the second sieve 92 can be reused, for example, in a thermal recycling process.

When the ink coating film 93 detached from the label piece 71 in the alkali desorption step S7 contains aqueous ink, in the separation step S8, instead of sieving, it is aggregated by solvent volatilization, extraction, or the like, and centrifuged. It is separated by separation, filtration, etc. and recovered.

<Modification 1>
FIG. 4 is a schematic cross-sectional view of the label 13 according to Modification 1. As shown in FIG. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. This point also applies to modified examples 2 to 5, which will be described later. The label 13 includes a base material 101 and an alkali-soluble base layer 102 formed on one surface of the base material 101 , and a heating portion 104 is formed on the surface of the base layer 102 opposite to the base material 101 . The heat generating portion 104 has a certain area in plan view, and is formed by coating, printing, printing, kneading, or the like. A non-heat-generating portion 103 is formed so as to cover the surface of the heat-generating portion 104 and the surface of the base layer 102 . The label 13 is manufactured by forming the non-heat-generating portion 103 after forming the heat-generating portion 104 on the surface of the base layer 102 . The heat generating portion 104 is covered and protected by the non-heat generating portion 103 . An ink layer 105 is composed of the heat-generating portion 104 and the non-heat-generating portion 103 . In the case of the label 13, since the surface of the heat-generating portion 104 is not exposed, there is no fear that the heat-generating portion 104 will drop (break) due to an external factor. In addition, since the heat-generating portion 104 is covered with the non-heat-generating portion 103, the heat is less likely to escape to the outside when the heat is generated.

<Modification 2>
FIG. 5 is a schematic cross-sectional view of a label 14 according to Modification 2. As shown in FIG. The heat-generating portion 104 of the label 14 is formed in a concave portion recessed toward the base layer 102 from the surface of the non-heat-generating portion 103 that is not in contact with the base layer 102 . Unlike the label 11 , the thickness of the heating portion 104 is thinner than the thickness of the non-heating portion 103 . When the heat-generating portion 104 has a black color such as carbon black, the influence on the design of the non-heat-generating portion 103 can be reduced by setting the formation range of the heat-generating portion 104 within a range where heat generation can be detected.

<Modification 3>
FIG. 6 is a schematic cross-sectional view of a label 15 according to Modification 3. As shown in FIG. The heating portion 104 of the label 15 is formed on the surface of the non-heating portion 103 that is not in contact with the base layer 102 . In the case of the label 15, after the non-heat-generating portion 103 is formed on the entire surface of the base layer 102, the heat-generating portion 104 can be easily formed at an arbitrary spot position.

<Modification 4>
FIG. 7 is a schematic cross-sectional view of a label 16 according to Modification 4. As shown in FIG. The heat generating portion 104 of the label 16 is formed on the surface of the substrate 101 that is not in contact with the underlying layer 102 . In the case of the label 16, the heat-generating portion 104 can be easily formed at an arbitrary position on the surface of the substrate 101. FIG.

<Modification 5>
FIG. 8 is a schematic cross-sectional view of a label 17 according to modification 5. As shown in FIG. In the label 17 , the base layers 102 are formed on both sides of the base material 101 . The heat generating portion 104 is formed on the surface of the base layer 102 exposed on the outermost surface of the label 17 . In the case of the label 17, the base layer 102 on the side where the heating portion 104 is formed is also separated from the substrate by alkali desorption or the like, so that the substrate 101 includes the non-heating portion 103 and the ink layer 105 of the heating portion 104. It can be reused without it.

<effect>
As described above, the labels 11, 13 to 17 (hereinafter referred to as the labels 11, etc.) of the first embodiment are provided with the heat-generating portion 104. Therefore, by detecting heat generation, the reusable labels 11, etc. can be easily produced. can be separated. Thermography provides excellent detection of heat generation. The separated base material 101 such as the label 11 can be separated from the non-heat-generating part 103 and the heat-generating part 104 by removing the base layer 102, and the base material 101 can be reused. When the heat generating portion 104 is included in the ink layer 105, the heat generating portion 104 can display a visually recognizable pattern, characters, or the like. When the energy rays are microwaves, the label 11 or the like includes a material that generates heat by absorbing the energy rays in the microwave range, so that the labels can be clearly distinguished from labels that do not include the material. When carbon black or aluminum pigment is used as the heat-generating material, these materials absorb microwaves remarkably, so that the heat-generating portion 104 can generate heat well and the reusable labels can be sorted well. If the heat-generating material has a dielectric loss factor of 10 or more, even a small amount of the heat-generating material can generate a detectable amount of heat.

According to the method for sorting the labels 11 and the like of Embodiment 1, the labels 11 and the like that are heated by the irradiation of the energy rays in the energy ray irradiation/separation step S5 are detected, and the labels 11 and the like that can be separated from the base material 101 are easily separated. can be separated into In the energy beam irradiation/separation step S5, thermography can be used to easily detect the label 11 that has generated heat.

According to the method of recovering the substrate from the label 11 or the like of the first embodiment, the substrate 101 is removed from the label 11 or the like detected to be reusable based on heat generated by the above-described label 11 sorting method. It can be separated and reused successfully.

According to the method for separating the label 11 and the like and the method for separating the base material from the label 11 and the like according to Embodiment 1, the label 11 and the like can be reused, and the Sustainable Development Goals (SDGs) can be achieved. can contribute.

Although the label 11 and the like described above have the ink layer 105 positioned on the back side (the side of the label contacting the container), the ink layer 105 may be positioned on the front side.

[Embodiment 2]
FIG. 9 is a schematic cross-sectional view of the label 18 according to Embodiment 2. FIG. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the label 18, an alkali-soluble base layer 108 is formed on the front side of the base material 101 (the side of the label opposite to the side in contact with the container). The underlayer 108 includes a non-heat-generating portion 106 that is a base layer that does not contain a heat-generating material, and a heat-generating portion 107 that is a base layer that contains a heat-generating material. The composition of the non-heat generating portion 106 is the same as the composition of the base layer 102 described above. A heat generating portion 107 is formed in a hole or recess provided in the non-heat generating portion 106 . Heat-generating portion 107 contains the same heat-generating material as heat-generating portion 104 described above, and is alkali-soluble. The non-heat generating portion 106 and the heat generating portion 107 may be formed on the surface of the substrate 101 by printing or the like. Either one of the non-heat generating portion 106 and the heat generating portion 107 may be formed on the surface of the base material 101, and then the other may be formed. Further, a mixture of the composition for forming the non-heat-generating portion 106 and the composition containing the heat-generating material for the heat-generating portion 107 is applied to the surface of the substrate 101, solidified and dried to form the base layer 108. You may An ink layer 109 is formed on the surface of the underlying layer 108 . The composition of the ink layer 109 is the same as the composition of the non-heating portion 103 described above. Since the base layer 108 includes the heat generating portion 107, the ink layer 109 can be formed with reduced restrictions on the design based on the heat generating portion 107. FIG.

[Embodiment 3]
FIG. 10 is a schematic cross-sectional view of a label 19 according to Embodiment 3. FIG. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. The label 19 includes a substrate 101 and an alkali-soluble ink layer 112 formed on one surface of the substrate 101 . The ink layer 112 includes a non-heat-generating portion 110 and a heat-generating portion 111 containing a heat-generating material. A heat-generating portion 111 having a predetermined width is formed on the surface of the base material 101 , and a non-heat-generating portion 110 is formed so as to surround the heat-generating portion 111 . The heat generating portion 111 may be formed in a hole or recess formed in the non-heat generating portion 110 . The non-heat-generating part 110 and the heat-generating part 111 contain a vehicle resin such as styrene-acrylic acid copolymer and/or styrene-maleic acid copolymer. The non-heat generating portion 110 and the heat generating portion 111 are formed in the same manner as the non-heat generating portion 103 and the heat generating portion 104 described above. According to Embodiment 3, the ink layer 112 dissolves in the alkaline aqueous solution and disappears in the alkali desorption step described above, and the substrate 101 is separated from the ink layer 112 . That is, the substrate 101 can be separated from the ink layer 112 without having the base layer 102 as a separation layer.

The result of examining the material of the heat generating portion 104 will be described below.
<Ink shrinkage evaluation>
A PET film was prepared as the base material 101 . Using a gravure proofing machine, an ink layer was formed by applying an ink containing Samples 1 to 10 in Table 1 below to 101 layers of the substrate and then solidifying the ink. Table 1 shows the exothermic materials of Samples 1 to 10 and the imaginary part (dielectric loss factor) of the complex dielectric constant. Here, the ink layer corresponds to the heating portion 104 .

The base material 101 layer on which each ink layer was formed was cut into a size of 50 mm×50 mm, and the shrinkage property was evaluated when irradiated with microwaves in a microwave oven for 10 seconds. Contractility evaluation is as follows. High shrinkability means good absorption of microwaves and heat generation.
Evaluation A: Shrinkage up to the maximum shrinkage rate of the shrinkable film, or partial melting of the film was confirmed
Evaluation B: The shrink film shrunk (however, the shrinkage rate was less than the maximum shrinkage rate)
Evaluation C: No shrinkage

From Table 1, when the ink compositions of Samples 1 to 4 containing carbon black having a dielectric loss coefficient of 100 or more are applied to the substrate 101, they shrink well, that is, they absorb a large amount of microwaves, It turns out that I had a fever. When the ink compositions of Samples 1 to 4 containing carbon black and having a dielectric loss factor of 10 or less were applied to the substrate 101, they did not shrink. It can be seen that when the composition of Sample 9 containing an aluminum pigment having a dielectric loss coefficient of 10 or more was applied to the substrate 101, it shrunk well and generated heat well. When the composition of Sample 10 containing aluminum pigments with a dielectric loss factor of less than 10 was applied to the substrate 101, it did not shrink.

From the above, it can be seen that carbon black, aluminum pigment, and silver ink are examples of the material of the heat generating portion 104, and it is preferable to use a material having a dielectric loss coefficient of 10 or more. When carbon black is selected as the material of the heat generating portion 104, carbon black having a dielectric loss coefficient of 100 or more is more preferable.

<Summary>
The label according to aspect 1 of the present invention comprises a base material, a separation layer laminated on the base material and separable from the base material, and a separation layer located on the side opposite to the base material side of the separation layer. An ink layer containing ink and a heat generating portion containing a material that generates heat when irradiated with energy rays are provided.

According to the above configuration, since the heating portion includes a material that generates heat when irradiated with energy rays, it is possible to easily separate reusable labels by detecting heat generation. By separating the separation layer from the base material by an alkali desorption treatment or the like, the separated base material of the label can be separated from the heating portion and reused.

In the label according to aspect 2 of the present invention, the heat generating portion is included in the ink layer.

According to the above configuration, since the heat-generating portion is included in the ink layer, it is possible to display a visually recognizable pattern, characters, or the like. By printing or the like, the heat generating portion and the portion other than the heat generating portion can be formed at the same time. Note that the entire ink layer may be the heat generating portion.

In the label according to aspect 3 of the present invention, the heat-generating part is included in the separation layer.

According to the above configuration, since the separation layer contains the heat-generating portion, the ink layer can be formed in a state in which restrictions on the design based on the heat-generating portion are reduced. It can also be applied when a separation layer and an ink layer are formed in this order on the front side of the substrate (the side opposite to the side of the label contacting the container).

A label according to aspect 4 of the present invention includes a base material, an ink layer laminated on the base material and containing an ink separable from the base material, contained in the ink layer, and irradiated with an energy ray. a heat-generating part containing a material that generates heat thereby.

According to the above configuration, it is possible to separate from the ink layer including the heat generating portion without passing through the separation layer.

In the label according to aspect 5 of the present invention, the energy rays are microwaves.

Materials that absorb energy rays in the microwave range are limited. According to the above configuration, since the label contains a material that generates heat by absorbing energy rays in the microwave region, the label can be clearly distinguished from a label that does not contain the material.

In the label according to aspect 6 of the present invention, the material has a dielectric loss factor of 10 or more.

According to the above configuration, even if the material is small, a large amount of heat is generated by absorbing microwaves.

In the label according to aspect 7 of the present invention, the material is carbon black or aluminum pigment.

Since the carbon black or aluminum pigment absorbs microwaves remarkably, the heat generating portion can generate heat well, and the reusable labels can be separated well.

A label sorting method according to aspect 8 of the present invention includes the steps of collecting a label group including any of the labels described above, irradiating the collected label group with the energy ray, and irradiating the energy ray. and a sorting step of sorting the label including the heat-generating portion that has generated heat.

According to the above configuration, labels whose substrates can be separated can be easily sorted by detecting labels heated by irradiation with energy rays.

In the label sorting method according to aspect 9 of the present invention, thermography is used to detect the heated label in the sorting step.

According to the above configuration, since the image of the heated portion becomes red, the heated label can be easily detected. If a portion of the label heats up, it can be detected by thermography, so there is no need to provide a heat generating portion on the entire label, and a separable label can be manufactured at low cost.

A method for recovering substrates from labels according to aspect 10 of the present invention includes the steps of recovering a label group including the above-described label, irradiating the recovered label group with the energy ray, and applying the energy ray. The method includes a sorting step of sorting the label including the heat-generating portion which is heated by irradiation, and a step of separating the base material from the label sorted by the sorting step.

According to the above configuration, the base material can be separated from the sorted label and reused.

10 PET bottle 11, 13, 14, 15, 16, 17, 18, 19 label 101 base material
102, 108 base layer 103, 110 non-heat-generating portion 104, 107, 111 heat-generating portion 105, 109 ink layer 106 non-heat-generating portion (non-heat-generating portion of base layer)
21 microwave irradiation unit 22 microwave 24 thermography camera 25 image processing device 40 label 50 label group

Claims (10)

a substrate;
a separation layer laminated on the substrate and separable from the substrate;
an ink layer containing ink located on the side opposite to the substrate side of the separation layer;
a heating part containing a material that generates heat when irradiated with energy rays;
label with 2. The label according to claim 1, wherein said heat generating portion is included in said ink layer. The label according to claim 1, wherein the heat generating portion is included in the separation layer. a substrate;
an ink layer laminated on the substrate and containing ink separable from the substrate;
a heat-generating portion that is contained in the ink layer and contains a material that generates heat when irradiated with an energy ray;
label with The label according to any one of claims 1 to 4, wherein said energy rays are microwaves. 6. The label of claim 5, wherein the material has a dielectric loss factor of 10 or greater. A label according to any one of claims 1 to 6, wherein said material is carbon black or an aluminum pigment. collecting a label group including the label according to any one of claims 1 to 7;
a step of irradiating the recovered label group with the energy beam;
a sorting step of sorting the label including the heat-generating portion generated by the irradiation with the energy beam;
Separation method for labels containing 9. The label separation method according to claim 8, wherein in the separation step, thermography is used to detect the heated labels. collecting a label group including the label according to any one of claims 1 to 7;
a step of irradiating the recovered label group with the energy beam;
a sorting step of sorting the label including the heat-generating portion generated by the irradiation with the energy beam;
and separating the substrate from the labels sorted by the sorting step.

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