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

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

[0001] The present disclosure relates to recycling techniques and techniques for dismantling components that are glued or adhered with adhesive tape.

[0002] In response to the issue of resource depletion, demand for recycling and reuse is increasing in various areas. In particular, there are many places where adhesives or glues are used, where screws or soldering are not possible, but glued parts are difficult to dismantle, and until now, even if there were still usable parts remaining, they were often discarded as waste while still glued together. In recent years, recycling and other such activities have been actively promoted based on the concept of resource circulation, and there is a demand for improving dismantling while ensuring reliability.

[0003] Therefore, efforts have been made to recycle resources by weakening the bond using heat or light energy to remove the bonded parts. For example, an easily dismantlable adhesive tape has been known in which the adhesive strength of the adhesive tape is reduced by irradiating it with light such as ultraviolet light, thereby allowing the bonded components to be easily separated during recycling (see, for example, Patent Document 1).

[0004] JP 2014-80524 A

[0005] However, when objects that do not transmit UV light are bonded together, it is sometimes difficult to disassemble them because it is not easy to irradiate the entire bonded area with UV light. In order to solve the above-mentioned problems, the present disclosure aims to provide an adhesive member that can be easily disassembled even when objects that do not or do not easily transmit UV light are bonded together.

[0006] The adhesive member of the present disclosure comprises a light diffusion film made of a material with a refractive index of 1.6 to 1.9 and capable of transmitting UV light, and an adhesive layer formed in a layered form on at least one side of the light diffusion film, the adhesive layer losing its adhesiveness upon irradiation with UV light after curing, and having a refractive index difference of 0.3 to 0.45 with the light diffusion film after curing.

[0007] According to the present disclosure, an adhesive member can be obtained that can be easily disassembled even when it bonds together objects that do not transmit or have low transmittance to UV light.

[0008] FIG. 1 is a schematic perspective view of an adhesive member according to embodiment 1. FIG. 2 is a schematic perspective view of two adherends bonded by the adhesive member according to embodiment 1. FIG. 3 is a schematic perspective view of an adhesive member of another form according to embodiment 1. FIG. 4 is a schematic perspective view of an adhesive member according to embodiment 2. FIG. 5 is a schematic perspective view of an adhesive member according to embodiment 2. FIG. 6 is a schematic perspective view of an adhesive structure bonded with an adhesive member according to embodiment 4. FIG. 7 is a schematic perspective view of a part of a rotor bonded with an adhesive member according to embodiment 4. FIG. 8 is a schematic perspective view of a refrigerator bonded with an adhesive member according to embodiment 4.

[0009] 1 is a perspective view schematically illustrating the structure of an adhesive member 100 according to a first embodiment of the present disclosure. As shown in FIG. 1 , the adhesive member 100 according to the present embodiment includes a light diffusion film 102 and adhesive layers 103 formed on both sides of the light diffusion film 102.

[0010] The light diffusion 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 diffusion film 102 with respect to UV light is 1.6 or more and 1.9 or less. The adhesive layer 103 functions to bond the light diffusion film 102 to an adherend placed on the opposite side thereof, and chemically loses its adhesive force when irradiated with UV light. The refractive index n2 of the adhesive layer 103 with respect to UV light is greater than the refractive index n1 of the light diffusion 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 may be 1.2 or more and 1.4 or less. Here, UV light may be any light that promotes decomposition of chemical bonds and may include some light in the visible light range. Specifically, the wavelength is preferably 280 nm or more and 500 nm or less, and more preferably 280 nm or more and 400 nm or less.

[0011] FIG. 2 is a schematic diagram of a structure in which two adherends 200 are bonded using the adhesive member of this embodiment. When two adherends are bonded using the adhesive member of this embodiment, they can be easily disassembled even if the adherends are made of materials that do not transmit UV light. When UV light 300 is incident on the end surface of the light diffusion film 102 of the structure in which the two adherends 200 are bonded, the UV light propagates through the light diffusion film 102. A portion of the propagated UV light penetrates the adhesive layer 103 from the light diffusion film 102. This deactivates the adhesive strength of the adhesive layer 103 formed on one or both surfaces of the light diffusion film 102, separating the adherends 200 that were previously bonded to each other.

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

[0013] In the case of an object bonded with the adhesive member shown in Figure 3, as in the case of using the adhesive member shown in Figure 1, the adhesive force of the adhesive layer 103 can be inactivated by irradiating UV light from the end face of the light diffusion film 102, and the objects to be bonded can be separated.

[0014] Although the light diffusion film 102 is in the form of a film here, the light diffusion film 102 may be in the form of a plate or a sheet. The adhesive member 100 may also be called an adhesive sheet.

[0015] The light diffusion film 102 may be made of polycarbonate, polyester, thiourethane, polyethylene terephthalate, polyethylene, epoxy compounds, silicone compounds, or other materials with optical improvements. Materials that absorb UV light, such as acrylic compounds, are not suitable for the light diffusion film 102.

[0016] Furthermore, it is desirable that the material of the light diffusion film 102 has a low UV absorption rate, but even if the material has a high UV absorption rate, it can be dissociated by increasing the irradiation intensity of UV light.

[0017] As a 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, or the like can be used.

[0018] The adhesive layer 103 used in the adhesive member of this embodiment may be an adhesive or a pressure sensitive adhesive.

[0019] When the adhesive layer 103 is an adhesive, it may be of a type that hardens when adhered. Furthermore, the hardening may be by any method, such as heat hardening, moisture hardening, or two-component mixing. Here, the adhesive used is one that has UV peelability at room temperature. When a pressure-sensitive adhesive is used as the material for the adhesive layer 103, the adhesive member 100 may be called an adhesive member or an adhesive sheet.

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

[0021] First, a case will be described in which the adhesive that becomes adhesive layer 103 is a photoacid generator such as an anthracene or an azo compound that peels off when exposed to light or heat. Examples of photoacid generators include 2,2'-azobis4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobisisobutyronitrile, 4,4'-azobis4-cyanovaleric acid, 2,2'-azobis2-methylpropionate dimethyl, 1,1'-azobis1-cyclohexanecarboxylate dimethyl, 1,1'-azobiscyclohexane-1-carbonitrile, and 2,2'-azobis2,4,4-trimethylpentane.

[0022] Next, a description will be given of the case where the adhesive that forms the adhesive layer 103 is an epoxy-based or urethane-modified epoxy-based compound. For example, when the adhesive is a urethane-modified epoxy-based compound, it can be decomposed by using a phosphorus fluoride salt or antimony fluoride salt containing triarylsulfonium as the main component, which is a strong photoacid generator against compounds having an isocyanate group.

[0023] These can also be cured by using an amine or radical generator during curing. For moisture curing, cyanoacrylate can be added, or an amine-based curing agent can be added to epoxy resins with a urethane structure or urethane terminals.

[0024] Furthermore, the adhesive that becomes the adhesive layer 103 is a sulfonium salt, an iodonium salt, a phosphorus-based PF ６ or antimony-based SbF ６ It may also be an onium salt having the anion:

[0025] When the adhesive is a urethane-modified epoxy compound, a photosensitizer such as an iodonium salt, a sulfonium salt, or an ammonium salt may be added as an auxiliary agent. Examples of the photosensitizer added include bis(an-alkylphenyl)iodonium hexafluoroantimonate, bis(4-n-alkylphenyl)iodonium, tetrakis(pentafluorophenyl)borate, and bis(4-tert-butylphenyl)iodohexafluorophosphate.

[0026] Furthermore, a primer treatment may be performed on the adhesive layer 103 to improve the adhesive reliability. For example, for epoxy adhesives, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldithoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldithoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(benzylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, or the like may be used as a primer.

[0027] In addition, as a physical treatment, the adhesive layer 103 may be subjected to physical treatment such as atmospheric plasma treatment, deep ultraviolet light treatment, corona discharge treatment, or roughening treatment (laser roughening, polishing, sandblasting treatment) to improve adhesion and increase adhesive strength.

[0028] On the other hand, a dismantling primer for facilitating dismantling may be used for the adhesive layer 103. The dismantling primer may be one containing anthracenes or one that generates an acid initiator when exposed to light as described above.

[0029] Next, a case where a pressure-sensitive adhesive is used for the adhesive layer 103 will be described. A pressure-sensitive adhesive exhibits adhesive properties when attached to an adherend, and is known as a pressure-sensitive adhesive. Any conventionally known pressure-sensitive adhesive can be used for the adhesive layer without any particular restrictions, and examples of such adhesives include pressure-sensitive adhesives having a base polymer such as acrylic, urethane, silicone, epoxy, or polyvinyl ether. Among these, acrylic, urethane, and silicone-based adhesives are preferred from the viewpoint of adhesion, and silicone-based adhesives are more preferred from the viewpoint of heat resistance.

[0030] The adhesive may also contain a tackifier to improve adhesion. Examples of tackifiers that can be used include rosin-based resins, terpene-based resins, and styrene-based resins. Furthermore, the adhesive may also contain a silane coupling agent to improve adhesion to the adherend. The use of an adhesive has the advantage of eliminating the need for a liquid application process and a curing process, thereby increasing workability.

[0031] The thickness of the adhesive layer 103 may be 1 nm or more and 500 μm or less. When an adhesive is used as the adhesive layer 103, the thickness of the adhesive layer 103 is generally 5 μm or more and 200 μm or less. In this case, a thickness of 10 μm or more and 100 μm or less is desirable from the viewpoint of a balance between adhesion reliability and peeling. When a pressure-sensitive adhesive is used as the adhesive layer 103, the thickness is generally 50 μm or more and 500 μm or less. In this case, a thickness of 100 μm or more and 300 μm or less is desirable.

[0032] In addition, the refractive index of adhesive layer 103 to UV light refers to the refractive index of adhesive layer 103 after curing, in the case of a cured type. In this embodiment, an adhesive layer that has UV peelability at room temperature is used for adhesive layer 103. The photosensitive wavelength that contributes to peeling may be 280 to 400 nm.

[0033] The adhesive member 100 of this embodiment is made of a material with a refractive index of 1.6 to 1.9 and includes a light diffusion film 102 that transmits UV light, and an adhesive layer 103 formed in a layer form on at least one side of the light diffusion film 102, whose adhesiveness is inactivated by irradiation with UV light after curing, and whose refractive index differs from that of the light diffusion film 102 by 0.3 to 0.45.

[0034] When UV light is incident on the end surface of the light diffusion film 102 of the adhesive member 100 of this embodiment, the UV light propagates within the light diffusion film 102. A portion of the propagated UV light penetrates from the light diffusion film 102 into the cured adhesive layer 103. This causes the adhesive force of the adhesive layer 103 formed on one or both surfaces of the light diffusion film 102 to be lost, separating the adherends 200 that had been adhered to each other.

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

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

[0037] Fig. 4 shows a perspective view of an example of the adhesive member 100 of this embodiment. Fig. 5 shows a perspective view of the adhesive layer 103 of the adhesive member 100 of this embodiment. In Figs. 4 and 5, the refractive layer 105 is formed in a stripe pattern in the adhesive layer 103 in contact with the light diffusion film 102. A plurality of refractive layers 105 are formed, and the surface in contact with the light diffusion film 102 is flat and the surface in contact with the adhesive layer 103 is curved. There may be only one refractive layer 105.

[0038] The shape of the refractive layer 105 does not need to be striped, and may be dot-shaped, for example, as shown in the perspective view of Fig. 6. In this way, the shape of the refractive layer 105 is arbitrary, and it is desirable to install it in a place where it is desired to irradiate more light.

[0039] The size of the refractive layer 105 in the planar direction is preferably 0.1 mm to 10 mm. If the size in the planar direction exceeds 10 mm, it is desirable to design it taking into consideration 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, may be small, as long as it is in the range of 0.1 μm to 1000 μm. Furthermore, it is desirable that the thickness of the refractive layer 105 be equal to or less than 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 diffusion film 102 and the adhesive layer 103, and when the adhesive layer 103 is formed on both sides of the light diffusion film 102, the refractive layer 105 may be formed on both sides of the light diffusion film 102 or on only one side.

[0041] The refractive index of the refractive layer 105 may be in the range of 1.4 to 1.6, and the material may be polycarbonate, polyester, thiourethane, polyethylene terephthalate, polyethylene, epoxy compounds, silicone compounds, or the like.

[0042] In the adhesive member 100 of the present embodiment, the adhesive layer 103 may be formed after the refractive layer 105 is formed on the light diffusion film 102. As a method for forming the refractive layer 105 on the light diffusion film 102, it is desirable to use pressure bonding by pressing or heat welding rather than a method using a separate material such as an adhesive or welding with a chemical solution, in order to suppress unnecessary light interference.

[0043] When UV light is incident on the end surface of the light diffusion film 102 of the adhesive member 100 of this embodiment, the UV light propagates within the light diffusion film 102. A portion of the propagated UV light passes from the light diffusion film 102 through the refractive layer 105 and enters the adhesive layer 103. This causes the adhesive force of the adhesive layer 103 formed on one or both surfaces of the light diffusion film 102 to be lost, separating the adherends 200 that had been adhered to each other.

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

[0045] Embodiment 3 In this embodiment, a method for bonding a plurality of adherends 200 using the adhesive member of Embodiment 1 or 2, and a method for peeling the bonded objects will be described.

[0046] First, the bonding method, that is, the method for manufacturing a bonded structure will be described.

[0047] First, the uncured adhesive member of embodiment 1 or 2, or in the case of a pressure-sensitive adhesive layer, is prepared in a state where it is not exposed to UV light or where its strength is below a predetermined level. Next, the adhesive member 100 is sandwiched between multiple adherends 200, and the adhesive layer 103 is cured. Curing may be performed by heat curing, moisture curing, two-component mixing, or the like. Furthermore, if the adhesive layer 103 is a pressure-sensitive adhesive, pressure is applied between the adherends 200 that sandwich the adhesive member 100. In this manner, multiple adherends 200 can be bonded together, and a bonded structure can be produced. Note that 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 a bonded structure, which is a plurality of adherends 200 bonded by the adhesive member 100, will be described.

[0049] UV light 300 is applied to the light diffusion film 102 at the end of the adhesive member 100 of multiple adherends 200 bonded together with the adhesive member 100. The UV light may have a wavelength of 280 nm or more and 500 nm or less. When UV light is applied for a predetermined period of time, the adhesive strength of the adhesive layer 103 of the adhesive member 100 is lost. Next, a force is applied in a direction that separates the bonded multiple adherends 200. In this way, the adherends 200 bonded together with the adhesive member 100 can be peeled off.

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

[0051] 7 shows an adhesive structure in which a prism 106 is provided on the side of the end of the light diffusion film 102 of the adhesive member 100 of the adherend 200 adhered by the adhesive member 100 of embodiment 1. The prism 106 guides UV light incident from above in FIG. 7 to the end of the light diffusion film 102. The prism 106 may be made of any material as long as it transmits UV light 300.

[0052] In the adhesive structure of Figure 7, when UV light 300 is directed toward the side of the adherend 200, the UV light 300 reaches the adhesive layer 103 via the prism 106 and the light diffusion film 102, and the adhesive strength of the adhesive layer 103 that has been reached by the UV light 300 is inactivated, so the adhesive structure can be easily dissociated.

[0053] 8 is a schematic diagram of a magnet attachment portion 400 of a motor rotor bonded with the adhesive member 100 of embodiment 1. In the case of a motor, it is generally difficult to allow UV light to enter the motor because the motor is usually completely enclosed in a housing. In the rotor magnet attachment portion 400, which is an adhesive structure of this embodiment, a magnet 402 is bonded to a rotor body 401 with the adhesive member 100. A light-conducting window 403 is formed facing the end of the adhesive member 100, and a prism 106 is formed outside the light-conducting 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 light-conducting window 403, and reaches the adhesive layer 103 via the light-diffusing film 102. The adhesive strength of the adhesive layer 103 is lost when the UV light 300 reaches it, so that the rotor, which is the adhesive structure shown in Figure 8, can easily release the magnet 302 by irradiating it with UV light. The prism 106 may be a mirror.

[0055] 9 is a schematic diagram of refrigerator 500 bonded with adhesive member 100 according to the first embodiment. In FIG. 9 , decorative panel 502 is bonded to door 501 of refrigerator 500 with adhesive member 100. Decorative panel 502 is sometimes made of glass to improve design, but in the case of a glass-top decorative panel 502, decorative panel 502 is made of glass, and UV light 300 may be incident from the front of door 501. Therefore, by using a light-blocking material on decorative panel 502 or applying an HR (High Reflection) coating, UV light 300 is prevented from entering from the front during use.

[0056] When separating the decorative panel 502 from the door 501, UV light 300 is applied to the edge of the light diffusion film 102 of the adhesive member 100. When the UV light 300 passes through the light diffusion film 102 and reaches the adhesive layer 103, the adhesive strength of the adhesive layer 103 is inactivated. Therefore, in the refrigerator, which is the adhesive structure of Fig. 9, the decorative panel 502 can be easily separated by irradiating it with UV light. The adhesive structure of the present disclosure can also be applied to the decorative panels of elevators.

[0057] As exemplified by the bonded structure of this embodiment, the bonded structure of the present disclosure can be applied to motors, sensors, electrical equipment, and the like.

[0058] 100 adhesive member, 102 light diffusion film, 103 UV-inactivated adhesive layer, 104 UV-resistant adhesive layer, 105 refractive layer, 106 prism, 200 adherend, 300 UV light, 400 magnet attachment portion, 401 rotor body, 402 magnet, 403 light-conducting window, 500 refrigerator, 501 door, 502 decorative panel.

Claims

1. a light diffusion film made of a material with a refractive index of 1.6 to 1.9 and transmitting UV light; an adhesive layer having a refractive index difference of 0.3 to 0.45 with respect to the light diffusion film, the adhesive layer being formed in a layer shape on at least one surface of the light diffusion film, and the adhesiveness of which is deactivated by irradiation with UV light; a refractive index layer between the light diffusion film and the adhesive layer, the refractive index of which is between the refractive index of the light diffusion film and the refractive index of the adhesive layer; An adhesive member comprising:

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

3. The adhesive layer is formed in layers on both sides of the light diffusion film. The adhesive member according to claim 1 .

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

5. The adhesive layer is an epoxy or urethane type. The adhesive member according to claim 1 .

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

7. A bonded structure bonded with the adhesive member according to any one of claims 1 to 6.

8. The bonded structure according to claim 7 , wherein the bonded structure is any one of an electric device, a motor, and a sensor.

9. The adhesive member according to any one of claims 1 to 6 is used to bond two objects to be bonded. A method for manufacturing a bonded structure.

10. The adhesive member according to any one of claims 1 to 6 is used to separate two objects adhered to each other by irradiating UV light from the side of the light diffusion film of the two objects adhered to each other. A method for releasing a bonded structure.

11. The optical diffusion film is made of a material having a refractive index of 1.6 to 1.9 and transmits UV light, and the difference in refractive index between the optical diffusion film and the optical diffusion film is 0.3 to 0.

45. The optical diffusion film is bonded with an adhesive member having an adhesive layer formed in a layer shape on at least one side of the optical diffusion film, the adhesiveness of which is inactivated by irradiation with UV light, An adhesive structure comprising a prism or a mirror that allows the UV light to be incident on the light diffusion film.

12. The bonded structure according to claim 11, wherein the bonded structure is any one of an electric device, a motor, and a sensor.