Adhesive member, adhesive structure, method for manufacturing an adhesive structure, and method for separating an adhesive structure

Abstract

An adhesive member (100) according to the present disclosure comprises a light-diffusing film (102) that is composed of a material having a refractive index of 1.6-1.9 and through which ultraviolet (UV) light transmits, and an adhesive layer (103) formed in layers on at least one side of the light-diffusing film (102), having an adhesiveness that deactivates under UV light irradiation after curing, and having a refractive index that differs from the light-diffusing film by 0.3-0.45. When adhered by using the adhesive member (100) according to the present disclosure, objects that do not transmit UV light (300) can be easily separated even when adhered to each other.

Description

Technical Field

[0001] The present disclosure relates to recycling technologies and technologies for disassembling members adhered by adhesive or adhesive tapes.

Background Art

[0002] Due to the problem of resource depletion, the demand for recycling and reuse has been increasing in various scenarios. In particular, in many places where adhesives or adhesives are used, screwing or soldering cannot be performed, but it is difficult to disassemble the adhered parts. Until now, even if there are remaining parts that can still be used, they have sometimes been discarded as waste while still adhered. In recent years, due to the concept of resource circulation, recycling and the like have been actively promoted, and it is desired to improve the disassembly property while ensuring reliability.

[0003] Therefore, it has been considered to remove the adhered part by weakening the bonding using heat or light energy and recycle the resources. For example, there has been known an easily disassemblable adhesive tape that can reduce the adhesive force of the adhesive tape by irradiating light such as ultraviolet light, and can easily separate the adhered members during recycling (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when objects that do not transmit UV light are adhered to each other, it is sometimes difficult to disassemble because it is not easy to irradiate UV light to the entire adhered part. An object of the present disclosure is to obtain an adhesive member that can be easily disassembled even when objects that do not transmit or hardly transmit UV light are adhered to each other in order to solve the above problems. [Means for solving the problem]

[0006] The adhesive member of this disclosure comprises a light-diffusing film made of a material with a refractive index of 1.6 to 1.9 that transmits UV light, and an adhesive layer formed in layers on at least one side of the light-diffusing film, the adhesive properties of which are deactivated by UV light irradiation after curing, and the refractive index difference between the cured light-diffusing film and the adhesive layer is 0.3 to 0.45. Then, between the light-diffusing film and the adhesive layer, a refractive index layer with a refractive index between the refractive index of the light-diffusing film and the refractive index of the adhesive layer is formed. It is equipped with the following features. [Effects of the Invention]

[0007] According to this disclosure, it is possible to obtain an adhesive member that can be easily disassembled even when objects that do not transmit UV light or transmit UV light poorly are bonded together. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view of the adhesive member according to Embodiment 1. [Figure 2] This is a schematic perspective view of two adherends bonded together by an adhesive member according to Embodiment 1. [Figure 3] This is a schematic perspective view of another form of adhesive member according to Embodiment 1. [Figure 4] This is a schematic perspective view of the adhesive member according to Embodiment 2. [Figure 5] This is a schematic perspective view of another adhesive member according to Embodiment 2. [Figure 6] This is a schematic perspective view of the adhesive member according to Embodiment 2. [Figure 7] This is a schematic perspective view of an adhesive structure bonded with an adhesive member according to Embodiment 4. [Figure 8] This is a schematic perspective view of a part of a rotor bonded with an adhesive member according to Embodiment 4. [Figure 9] This is a schematic perspective view of a refrigerator bonded with an adhesive member according to Embodiment 4. [Modes for carrying out the invention]

[0009] Embodiment 1. Figure 1 is a schematic perspective view illustrating the structure of the adhesive member 100 of Embodiment 1 of the present disclosure. As shown in Figure 1, the adhesive member 100 of this embodiment comprises a light-diffusing film 102 and adhesive layers 103 formed on both sides of the light-diffusing film 102.

[0010] The light-diffusing film 102 transmits UV light, and when UV light is incident on the edge of the film, the UV light propagates within the film. The refractive index n1 of the light-diffusing film 102 with respect to UV light is 1.6 or more and 1.9 or less. The adhesive layer 103 has the function of bonding the light-diffusing film 102 to the object to be bonded on the opposite side, and when UV light is irradiated onto the adhesive layer 103, the adhesive strength is chemically lost. The refractive index n2 of the adhesive layer 103 with respect to UV light is greater than the refractive index n1 of the light-diffusing film 102, and the difference Δn between n1 and n2 is 0.3 or more and 0.45 or less. The refractive index n2 of the adhesive layer 103 with respect to UV light can be 1.2 or more and 1.4 or less, for example. Here, UV light refers to any light that can promote the decomposition of chemical bonds, and may include some light in the visible light range. Specifically, it should have a wavelength of 280 nm or more and 500 nm or less, more preferably 280 nm or more and 400 nm or less.

[0011] Figure 2 shows a schematic diagram of a structure in which two adherends 200 are bonded together using the adhesive member of this embodiment. If two adherends are bonded together using the adhesive member of this embodiment, they can be easily disassembled even if the adherends are made of a material that does not transmit UV light. By irradiating the end face of the light-diffusing film 102 of the structure in which the two adherends 200 are bonded together with UV light 300, the UV light propagates within the light-diffusing film 102. A portion of the propagated UV light penetrates from the light-diffusing film 102 into the adhesive layer 103. As a result, the adhesive force of the adhesive layer 103 formed on one or both faces of the light-diffusing film 102 is deactivated, separating the adherends 200 that were bonded together.

[0012] Note that the adhesive member of this embodiment may be provided with an adhesive layer 103 that is deactivated by UV only on one side of the light diffusion film 102. FIG. 3 is a schematic diagram of another adhesive member of this embodiment. In FIG. 3, an adhesive layer 103 that is deactivated by UV is formed on one side of the light diffusion film 102, and an adhesive layer 104 that is not deactivated by UV is provided on the other side of the light diffusion film 102. The refractive index n3 of the adhesive layer 104 that is not deactivated by UV may be the same as the refractive index n2 of the adhesive layer 103, or may not be the same.

[0013] Even in the case of being adhered with the adhesive member shown in FIG. 3, by irradiating UV light from the end face of the light diffusion film 102, the adhesive force of the adhesive layer 103 can be deactivated, and the adherend can be separated, similar to the case of using the adhesive member shown in FIG. 1.

[0014] Here, the light diffusion film 102 is in the form of a film, but the light diffusion film 102 may be in the form of a plate or a sheet. Also, the adhesive member 100 may be called an adhesive sheet.

[0015] As the material of the light diffusion film 102, polycarbonate, polyester, thiourethane, polyethylene terephthalate, polyethylene, epoxy-based compounds, silicone-based compounds, etc. can be used. Also, those obtained by optically improving these may be used. Materials that absorb UV light, such as acrylic-based compounds, are not suitable as the material of the light diffusion film 102.

[0016] Also, as the material of the light diffusion film 102, those with a low absorption rate for UV are desirable, but even materials with a high absorption rate for UV can be dissociated by increasing the irradiation intensity of UV light.

[0017] As the light source of UV light, a halogen lamp, a xenon lamp, a metal halide lamp, a high-pressure mercury lamp, a UV light-emitting LED, etc. can be used.

[0018] The adhesive layer 103 used in the adhesive member of this embodiment may be any adhesive or tack.

[0019] If the adhesive layer 103 is an adhesive, it may be a type that hardens upon bonding. Furthermore, the hardening method is not limited to heat curing, moisture curing, or two-part mixing. Here, an adhesive that exhibits UV release properties at room temperature is used. If an adhesive is used as the material for the adhesive layer 103, the adhesive member 100 may be referred to as an adhesive member or adhesive sheet.

[0020] Here, the material for the adhesive layer 103 can be a photoacid generator such as anthracenes or azo compounds, or an epoxy or urethane-based material that loses its adhesive (tackiness) properties when exposed to UV light.

[0021] First, we will explain the case where the adhesive forming the adhesive layer 103 is a photoacid generator such as anthracenes or azo compounds that peel off in response to light or heat. Examples of photoacid generators include 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobisisobutyronitrile, 4,4'-azobis-4-cyanovaleric acid, 2,2'-azobis-2-methylpropinatedimethyl, 1,1'-azobis-1-cyclohexanecarboxylatedimethyl, 1,1'-azobiscyclohexane-1-carbonitride, and 2,2'-azobis-2,4,4-trimethylpentane.

[0022] Next, we will explain the case where the adhesive forming the adhesive layer 103 is an epoxy-based or urethane-modified epoxy compound. For example, if the adhesive is a urethane-modified epoxy compound, it can be decomposed by using a phosphate fluoride salt or antimony fluoride salt mainly composed of triarylsulfonium, which is a strong photoacid generator against compounds containing isocyanate groups.

[0023] Furthermore, these materials can be cured by using amines or radical generators during the curing process. In the case of moisture curing, curing is possible by adding cyanoacrylate or by adding an amine-based curing agent to an epoxy with a urethane structure or urethane-treated ends.

[0024] Furthermore, the adhesive forming the adhesive layer 103 may be a sulfonium salt, an iodonium salt, an onium salt with a phosphorus-based PF6 or an antimony-based SbF6 anion.

[0025] If the adhesive is a urethane-modified epoxy compound, it may also contain photosensitizers such as iodonium salts, sulfonium salts, or ammonium salts as auxiliary agents. Examples of adhesives with added photosensitizers such as iodonium salts, sulfonium salts, or ammonium salts include bis-an-alkylphenyliodonium=hexafluoroantimonate, bis-4-n-alkylphenyliodonium, tetrakispentafluorophenylborate, and bis-4-tert-butylphenyliodohexafluorophosphate.

[0026] Furthermore, the adhesive layer 103 may be treated with a primer to improve adhesive reliability. For example, for epoxy adhesives, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethylditoxicsilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethylditoxicsilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(benylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride may be used as a primer.

[0027] Furthermore, the adhesion and adhesive strength may be increased by performing physical treatments on the adhesive layer 103, such as atmospheric plasma treatment, deep ultraviolet light treatment, corona discharge treatment, and desaturation treatment (laser desaturation, polishing, sandblasting).

[0028] On the other hand, a decomposable primer may be used in the adhesive layer 103 to facilitate dismantling. The decomposable primer can contain anthracenes or other substances, or release the photocatalytic acid initiators mentioned above.

[0029] Next, we will explain the case where an adhesive is used in the adhesive layer 103. The adhesive is one that exhibits adhesive properties when it is attached to the substrate, and is a so-called pressure-sensitive adhesive. As the adhesive layer, conventionally known adhesives can be used without particular limitations, and for example, adhesives having a base polymer such as acrylic, urethane, silicone, epoxy, or polyvinyl ether can be used. Among these, acrylic, urethane, and silicone adhesives are preferable from the viewpoint of adhesion, and silicone adhesives are further preferable from the viewpoint of heat resistance.

[0030] Furthermore, the adhesive may contain a tackifier to improve adhesion. Examples of tackifiers include rosin-based resins, terpene-based resins, and styrene-based resins. Additionally, the adhesive may contain a silane coupling agent to improve adhesion to the substrate. Using an adhesive eliminates the need for liquid coating and curing processes, offering the advantage of improved work efficiency.

[0031] The thickness of the adhesive layer 103 can be between 1 nm and 500 μm. When using an adhesive as the adhesive layer 103, it is common to set the thickness of the adhesive layer 103 to between 5 μm and 200 μm. In that case, a thickness of 10 μm to 100 μm is desirable in terms of balancing adhesive reliability and peelability. When using a tack as the adhesive layer 103, it is common to set the thickness to between 50 μm and 500 μm. In that case, a thickness of 100 μm to 300 μm is desirable.

[0032] Furthermore, the refractive index of the adhesive layer 103 with respect to UV light refers to that of the adhesive layer 103 after curing, in the case of the curing type. In this embodiment, the adhesive layer 103 is made of a material that is UV-peelable at room temperature. The photosensitive wavelength that contributes to its peeling is 280 to 400 nm.

[0033] The adhesive member 100 of this embodiment comprises a light-diffusing film 102 made of a material with a refractive index of 1.6 to 1.9 that transmits UV light, and an adhesive layer 103 formed in a layer on at least one side of the light-diffusing film 102, the adhesive properties of which are deactivated by UV light irradiation after curing, and the refractive index difference between the light-diffusing film 102 and the adhesive layer 103 is 0.3 to 0.45.

[0034] By irradiating the end face of the light-diffusing film 102 of the adhesive member 100 in this embodiment with UV light, the UV light propagates within the light-diffusing film 102. A portion of the propagated UV light penetrates from the light-diffusing film 102 into the cured adhesive layer 103. As a result, the adhesive force of the adhesive layer 103 formed on one or both surfaces of the light-diffusing film 102 is deactivated, separating the adherends 200 that were bonded together.

[0035] Therefore, the adherend 200 bonded by the adhesive member 100 of this embodiment can be easily separated.

[0036] Embodiment 2. The adhesive member of this embodiment has a refractive layer 105 provided in a portion between the light-diffusing film 102 and the adhesive layer 103, so that UV light incident from the end face of the light-diffusing film 102 can penetrate the adhesive layer 103 more effectively than the adhesive member 100 shown in Embodiment 1. The refractive index value of the refractive layer 105 with respect to UV light is taken to be the value between the refractive index of the light-diffusing film 102 and the refractive index of the adhesive layer 103.

[0037] Figure 4 shows a perspective view of an example of the adhesive member 100 of this embodiment. Figure 5 shows a perspective view of the adhesive member 100 of this embodiment with light transmitted through the adhesive layer 103. In Figures 4 and 5, the refractive layer 105 is formed in a stripe shape within the adhesive layer 103, in contact with the light diffusion film 102. Multiple refractive layers 105 are formed, with the surface in contact with the light diffusion film 102 being planar and the surface in contact with the adhesive layer 103 being curved. There may also be only one refractive layer 105.

[0038] The shape of the refractive layer 105 does not have to be striped; for example, it may be dotted, as shown in the perspective view in Figure 6. Thus, the shape of the refractive layer 105 is arbitrary, and it is desirable to install it in a location where more light is to be emitted.

[0039] The size of the refractive layer 105 in the planar direction is preferably between 0.1 mm and 10 mm. If the size in the planar direction exceeds 10 mm, it is desirable to design it considering the light intensity, wavelength, etc. Furthermore, the thickness of the refractive layer 105, i.e., the length in the thickness direction of the light diffusion film 102, can be small, and is acceptable within the range of 0.1 μm to 1000 μm. In addition, it is desirable that the thickness of the refractive layer 105 be less than or equal to the thickness of the adhesive layer 103.

[0040] Furthermore, the refractive layer 105 may be formed on at least a portion of the interface between the light-diffusing film 102 and the adhesive layer 103. Also, if the adhesive layer 103 is formed on both sides of the light-diffusing film 102, the refractive layer 105 may be formed on both sides of the light-diffusing film 102 or on only one side.

[0041] The refractive index of the refractive layer 105 can be in the range of 1.4 to 1.6, and suitable materials include polycarbonate, polyester, thiourethane, polyethylene terephthalate, polyethylene, epoxy compounds, and silicone compounds.

[0042] In this embodiment, the adhesive member 100 can be formed by first forming a refractive layer 105 on the light diffusing film 102, and then forming the adhesive layer 103. As a method for forming the refractive layer 105 on the light-diffusing film 102, it is desirable to use pressing or heat welding rather than using another material such as an adhesive or welding with a chemical solution in order to suppress unwanted light interference.

[0043] By irradiating the end face of the light-diffusing film 102 of the adhesive member 100 in this embodiment with UV light, the UV light propagates within the light-diffusing film 102. A portion of the propagated UV light penetrates from the light-diffusing film 102 through the refraction layer 105 into the adhesive layer 103. As a result, the adhesive force of the adhesive layer 103 formed on one or both surfaces of the light-diffusing film 102 is deactivated, separating the adherends 200 that were bonded together.

[0044] According to the adhesive member 100 of this embodiment, UV light 300 can reach the adhesive layer 103 more effectively, and the adherends 200 bonded by the adhesive member 100 of this embodiment can be separated more easily.

[0045] Embodiment 3. This embodiment describes a method for bonding multiple adherends 200 using the adhesive member of Embodiment 1 or 2, and a method for peeling off the bonded objects.

[0046] First, we will explain the bonding method, that is, the manufacturing method of the bonded structure.

[0047] First, prepare the uncured adhesive member or, in the case of the adhesive layer, the adhesive material of Embodiment 1 or 2, in its original state, in a condition where it is not exposed to UV light or is below a predetermined strength. Next, the adhesive member 100 is sandwiched between multiple adherends 200 and the adhesive layer 103 is cured. Curing can be done by heat curing, moisture curing, or two-component mixture curing. If the adhesive layer 103 is an adhesive, pressure is applied between the adherends 200 sandwiching the adhesive member 100. In this way, multiple adherends 200 can be bonded together, and an adhesive structure can be manufactured. Furthermore, the adhesive layer 103 may be subjected to a primer treatment as described in Embodiment 1 before bonding.

[0048] Next, a method for peeling off an adhesive structure, which consists of multiple adherends 200 bonded together by an adhesive member 100, will be described.

[0049] UV light 300 is incident on the light-diffusing film 102 at the edges of the adhesive member 100 of multiple adherends 200 that are bonded together by the adhesive member 100. The UV light can have a wavelength of 280 nm or more and 500 nm or less. When UV light is incident for a predetermined time, the adhesive strength of the adhesive layer 103 of the adhesive member 100 is deactivated. Next, a force is applied in a direction that separates the multiple adherends 200 that are bonded together. In this way, the adherends 200 bonded together by the adhesive member 100 can be peeled off.

[0050] Embodiment 4. The adhesive structure of this embodiment includes the adhesive member 100 of Embodiment 1 or 2, and is configured to be easily peeled off.

[0051] Figure 7 shows an adhesive structure in which a prism 106 is provided on the side of the end of the light-diffusing film 102 of the adhesive member 100 of Embodiment 1, which is bonded to an adherend 200 by the adhesive member 100 of Embodiment 1. The prism 106 guides UV light incident from above in Figure 7 to the end of the light-diffusing film 102. The prism 106 may be made of any material that transmits UV light 300.

[0052] The adhesive structure in Figure 7 can be easily separated by shining UV light 300 toward the side surface of the adherend 200. The UV light 300 reaches the adhesive layer 103 via the prism 106 and light diffusion film 102, and the adhesive force of the adhesive layer 103 that has been exposed to the UV light 300 is deactivated.

[0053] Figure 8 is a schematic diagram of the magnet attachment portion 400 of the motor rotor bonded by the adhesive member 100 of Embodiment 1. In the case of a motor, it is generally difficult to expose it to UV light because it is usually completely enclosed within the housing. In the magnet attachment portion 400 of the rotor, which is an adhesive structure of this embodiment, a magnet 402 is bonded to the rotor body 401 by an adhesive member 100. An optical conduction window 403 is formed opposite the end of the adhesive member 100, and a prism 106 is formed on the outside of the optical conduction window 403.

[0054] When UV light 300 is incident from above the prism 106, the UV light is diffracted by the prism 106, passes through the optical conduction window 403, and reaches the adhesive layer 103 via the light diffusion film 102. Since the adhesive force of the adhesive layer 103 that has been exposed to UV light 300 is deactivated, the rotor, which is an adhesive structure in Figure 8, can be easily separated from the magnet 302 by irradiation with UV light. Prism 106 can also be a mirror.

[0055] Figure 9 is a schematic diagram of a refrigerator 500 bonded by the adhesive member 100 of Embodiment 1. In Figure 9, a decorative panel 502 is bonded to the door 501 of the refrigerator 500 by the adhesive member 100. The decorative panel 502 may be made of glass to improve the design, but in the case of a glass-topped decorative panel 502, UV light 300 may enter from the front of the door 501 because the decorative panel 502 is made of glass. Therefore, UV light 300 can be prevented from entering from the front during use by using a light-shielding material on the decorative panel 502 or by applying an HR (High Reflection) coating.

[0056] When separating the decorative panel 502 from the door 501, UV light 300 is incident on the edge of the light-diffusing film 102 of the adhesive member 100. When the UV light 300 passes through the light-diffusing film 102 and reaches the adhesive layer 103, the adhesive force of the adhesive layer 103 is deactivated, so the refrigerator, which is an adhesive structure in Figure 9, can be easily separated from the decorative panel 502 by irradiation with UV light. The adhesive structure of this disclosure can also be applied to the decorative panels of elevators.

[0057] As illustrated by the adhesive structure of this embodiment, the adhesive structure of this disclosure can be applied to motors, sensors, electrical equipment, and the like. [Explanation of symbols]

[0058] 100 Adhesive material, 102 Light diffusing film, 103 UV-deactivating adhesive layer, 104 UV-inactivating adhesive layer, 105 Refraction layer, 106 Prism, 200 Adhesion substrate, 300 UV light, 400 Magnet attachment part, 401 Rotor body, 402 Magnet, 403 Light-conducting window, 500 Refrigerator, 501 Door, 502 Decorative panel.

Claims

1. A light-diffusing film made of a material with a refractive index of 1.6 to 1.9 that transmits UV light, The refractive index difference with the light-diffusing film is 0.3 to 0.45, and the adhesive layer is formed in a layer on at least one side of the light-diffusing film, and its adhesive properties are deactivated by UV light irradiation. Between the light-diffusing film and the adhesive layer, there is a refractive layer with a refractive index between the refractive index of the light-diffusing film and the refractive index of the adhesive layer. An adhesive member characterized by having the following features.

2. The wavelength of the UV light is 300 nm or more. The adhesive member according to claim 1.

3. The adhesive layer is characterized by being formed in layers on both sides of the light-diffusing film. The adhesive member according to claim 1.

4. The refractive layer is characterized by being formed in a stripe or dot pattern between the light diffusing film and the adhesive layer. The adhesive member according to claim 1.

5. The adhesive layer is characterized by being epoxy-based or urethane-based. The adhesive member according to claim 1.

6. The thickness of the adhesive layer is characterized by being 1 μm or more and 500 μm or less. The adhesive member according to claim 1.

7. An adhesive structure bonded with an adhesive member according to any one of claims 1 to 6.

8. The adhesive structure according to claim 7, wherein the adhesive structure is an electrical device, a motor, or a sensor.

9. The adhesive member described in any one of claims 1 to 6 is used to bond two objects to be bonded together. A method for manufacturing adhesive structures.

10. Using the adhesive member described in any one of claims 1 to 6, UV light is irradiated from the side surface of the light-diffusing film of two adherends that are bonded together to separate the two adherends. A method for separating bonded structures.

11. The adhesive member comprises a light-diffusing film made of a material with a refractive index of 1.6 to 1.9 that transmits UV light, and an adhesive layer formed in a layer on at least one side of the light-diffusing film, wherein the adhesive properties are deactivated by UV light irradiation, and the difference in refractive index between the light-diffusing film and the light-diffusing film is 0.3 to 0.

45. An adhesive structure characterized by comprising a prism or mirror for injecting the UV light into the light-diffusing film.

12. The adhesive structure according to claim 11, wherein the adhesive structure is an electrical device, a motor, or a sensor.

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