Peeling recovery method

Abstract

To provide a peeling recovery method for peeling and recovering an object layer including an object to be recovered from a lamellar body.SOLUTION: This peeling recovery method for recovering an object layer 11 including an object to be recovered from a laminar body 1 having the object layer 11 and a support layer 10 on which the object layer 11 is stacked comprises: a propagation layer arrangement step of arranging a pressure propagation layer 23 on the surface of the support layer 10; an absorber layer arrangement step of arranging, on the surface of the pressure propagation layer 23, an energy absorption layer 22 that receives a laser beam to generate shock waves; an irradiation step of irradiating the energy absorption layer 22 with the laser beam to generate shock waves; and a peeling step of peeling the object layer 11 in a laminar shape to separate and recover it.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a peeling and recovery method. [Background technology]

[0002] Patent Document 1 discloses a recycling method for treating used batteries. The method includes a step of crushing the battery to obtain crushed material and a step of inactivating the crushed material to obtain inactive crushed material. In this method, for example, the active material and the active material carrier are separated. An example of the active material carrier is an aluminum or aluminum alloy foil.

[0003] Patent Document 2 discloses a solar cell panel recycling device and method. This solar cell panel recycling device separates and recovers metal components of a layer structure laminated on a glass substrate. The recycling device includes a metal roller brush that separates only the layer structure containing the metal components from the glass substrate, and a separation and recovery means that recovers the separated layer structure.

[0004] Patent Document 3 describes an apparatus and method for measuring the tensile strength of ultrathin film interfaces and multilayers deposited on engineered substrates. The apparatus and method are said to use glass-modified stress waves to achieve separation and peeling of thin film lines or their complete structures from semiconductors and engineered substrates. The sample assembly evaluated by this apparatus and method is a multilayer comprising a fixed layer of solid water glass, an energy absorption layer which is an aluminum layer, a glass substrate, a silicon substrate element, and a coating having a free surface.

[0005] In the apparatus and method described in Patent Document 3, a Nd-YAG laser pulse is applied to a sample assembly. The laser pulse travels across the fixed layer. The laser pulse passes through the fixed layer and acts on the energy-absorbing layer, which absorbs the energy, heating it. The subsequent expansion of the energy-absorbing layer generates a compressive shock wave or pulse wave. The compressive shock wave or pulse wave propagates through the glass substrate and silicon substrate to the coating. The pulse wave then penetrates the coating, reaches the free surface of the coating, and is reflected, generating a tensile pulse. This generates tensile stress between the silicon substrate and the coating, causing the coating to peel off from the substrate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2019-533881 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-54593 [Patent Document 3] Special Publication No. 2007-527538 Summary of the Invention [Problem to be solved by the invention]

[0007] As disclosed in Patent Documents 1 and 2, there are cases where it is desirable to peel off layers of a layered body to recover specific recovery targets. For example, rare metals are used in battery materials for storage batteries such as secondary batteries and solar panels, and these may be desired to be recovered for recycling. However, conventional techniques have sometimes been unsuitable for recovering recovery targets from layered bodies due to the characteristics of the layered body. Therefore, there is a need for a new peeling and recovery method.

[0008] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide a peeling and recovery method for peeling and recovering an object layer containing an object to be recovered from a layered body. [Means for solving the problem]

[0009] In order to achieve the above object, the peeling and recovery method according to the present disclosure includes: A peeling and recovery method for recovering a target layer from a layered body having a target layer containing a target object to be recovered and a support layer on which the target layer is laminated, comprising: a pressure transmission layer disposing step of disposing a pressure transmission layer on the surface of the support layer; an energy absorption layer disposing step of disposing an energy absorption layer on a surface of the pressure propagation layer, the energy absorption layer receiving laser light and generating shock waves; an irradiation step of irradiating the energy absorbing layer with laser light to generate shock waves; and a peeling step of peeling the target layer into layers to separate and recover them. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a peeling and recovery method for peeling and recovering a target layer containing a target object to be recovered from a layered body. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an explanatory diagram of a processed piece used in a peeling and collecting method according to the present embodiment. FIG. [Figure 2] 1 is an explanatory diagram of an example of a peeling device that realizes a peeling and collecting method according to an embodiment of the present invention. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] 10 is a photograph of an electrode sheet that has been subjected to a peeling treatment. [Figure 8] 10A and 10B are explanatory diagrams illustrating a case where the target layer is crushed in the peeling process. [Figure 9] 10A and 10B are explanatory diagrams illustrating a case where the target layer is peeled off without being crushed in the peeling process. [Figure 10]10A and 10B are explanatory diagrams illustrating a case where the surface of the energy absorbing layer is scanned in a peeling process. [Figure 11] 10A and 10B are explanatory diagrams illustrating a case where a wide area of ​​the object layer is peeled off in the peeling process. [Figure 12] 1 is a photograph of a treated piece before peeling treatment in Example 1. [Figure 13] 1 is a photograph of a treated piece after peeling treatment in Example 1. [Figure 14] 1 is a photograph of a treated piece after peeling treatment in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] A peeling and collecting method according to an embodiment of the present disclosure will be described with reference to the drawings.

[0013] First, an outline of a peeling and collecting method according to an embodiment of the present disclosure will be described.

[0014] 1 shows an explanatory diagram of a processed piece T used in the peeling and recovery method according to this embodiment. The peeling and recovery method according to this embodiment recovers the target layer 11 from a layered body 1 having a target layer 11 containing a recovery target and a support layer 10 on which the target layer 11 is laminated.

[0015] The peeling and recovery method according to this embodiment includes a propagation layer placement step of placing a pressure propagation layer 23 on the surface of the support layer 10, an absorption layer placement step of placing an energy absorption layer 22 on the surface of the pressure propagation layer 23, which receives laser light and generates shock waves, an irradiation step of irradiating the energy absorption layer 22 with laser light to generate shock waves, and a peeling step of peeling the target layer 11 in layers and separating and recovering them.

[0016] According to the peeling and recovery method of this embodiment, the target layer 11 containing the material to be recovered is peeled from the layered body 1, thereby realizing recovery of the target layer 11. Hereinafter, peeling the target layer 11 containing the material to be recovered from the layered body 1 may be referred to as a peeling process. The peeling and recovery method of this embodiment can be used as a pretreatment for separating and recovering rare metals such as lithium from, for example, an electrode sheet of a secondary battery.

[0017] 1 shows a case in which a layered body 1 is supported on a process substrate 2 including an energy absorbing layer 22 and a pressure transmission layer 23, and the pressure transmission layer 23 is disposed on the surface of a support layer 10. The process substrate 2 will be described later. In FIG. 1, the layered substrate in which the layered body 1 is supported on the process substrate 2 by adhesion or the like is shown as a process piece T.

[0018] 2 shows an example of a peeling device 100 that realizes the peeling and recovery method according to this embodiment. The illustrated peeling device 100 includes a holding container C that securely holds the processed pieces T, a laser light source 91 that irradiates a laser beam (light beam L shown in FIG. 2) onto the processed substrate 2 side of the processed pieces T, a lens 91a that focuses the laser beam on the surface of the processed pieces T, a tank 93 that stores a viscous fluid, a pump 94 that circulates the viscous fluid inside and outside the processed substrate 2, and an imaging device 92 that optically observes the target layer 11 side of the processed pieces T.

[0019] The peeling and collecting method according to an embodiment of the present disclosure will be described in detail below.

[0020] First, the layered body 1 and the processing substrate 2 will be described in detail.

[0021] The layered body 1 has at least a target layer 11 containing a material to be collected, and a support layer 10 on which the target layer 11 is laminated. Examples of the layered body 1 include a battery electrode sheet, a semiconductor substrate such as a solar cell, a semiconductor device, or a precursor thereof. The layered body 1 has a thickness of, for example, 10 μm or more and 3 mm or less. When the layered body 1 is a battery electrode sheet, the thickness is, for example, 30 μm or more and 200 μm or less. The following description will mainly focus on the case where the layered body 1 is a battery electrode sheet.

[0022] The support layer 10 is a substrate on which the object layer 11 is supported. The thickness of the support layer 10 is, for example, 10 μm or more and 3 mm or less. When the layered body 1 is an electrode sheet, for example, the support layer 10 is a metal or metal alloy foil such as aluminum foil, copper foil, or titanium foil. When the layered body 1 is an electrode sheet, for example, the thickness of the support layer 10 is, for example, 10 μm or more and 170 μm or less.

[0023] The target layer 11 is, for example, a layer or film containing a rare substance, i.e., a material to be recovered. An example of the layered body 1 is an electrode sheet for a secondary battery. When the layered body 1 is an electrode sheet for a secondary battery, the target layer 11 may be, for example, an active material layer containing a rare metal such as lithium. The target layer 11 may be in the form of a layer or a film such as a thin film.

[0024] In this embodiment, there are no limitations on the layer formation method or film formation method of the target layer 11. The thickness of the target layer 11 is, for example, 20 μm or more and 170 μm or less. When the target layer 11 is an active material layer, the thickness of the target layer 11 is, for example, 30 μm or more and 100 μm or less.

[0025] The processing substrate 2 is an auxiliary substrate for performing a peeling process on the layered body 1. For example, the layered body 1 may be attached to the processing substrate 2 by adhesion or the like. The processing piece T is formed by laminating and attaching the layered body 1 to the processing substrate 2.

[0026] For example, the processing substrate 2 may have, in this order, a fixing layer 21, an energy absorbing layer 22, a pressure transmission layer 23, and an adhesive layer 24. The fixing layer 21, the energy absorbing layer 22, the pressure transmission layer 23, and the adhesive layer 24 are each in close contact with the adjacent layer.

[0027] The pressure propagation layer 23 is a layer for propagating the shock waves generated in the energy absorbing layer 22 toward the layered body 1. For the pressure propagation layer 23, it is preferable to select a material that is resistant to shock wave attenuation and has an acoustic impedance value close to that of the energy absorbing layer 22 and the adhesive layer 24. It is also preferable to select a ductile material that is resistant to damage due to the propagation of shock waves. It is also preferable to use a material with high thermal conductivity. An example of a preferable material is a metal material, particularly aluminum or an aluminum alloy. That is, the pressure propagation layer 23 may include an aluminum substrate made of aluminum or an aluminum alloy. In this embodiment, an example will be described in which the pressure propagation layer 23 is formed from an aluminum substrate made of an aluminum alloy (A2017).

[0028] The pressure transmission layer 23 is preferably formed to a thickness of 1 mm or more and approximately 9 mm. In this embodiment, as an example, the thickness of the pressure transmission layer 23 can be 3 mm. If the pressure transmission layer 23 is thinner than 1 mm, shock waves generated in the energy absorbing layer 22 may not be properly propagated to the layered body 1. Furthermore, the pressure transmission layer 23 may be deformed. If the pressure transmission layer 23 is thicker than 10 mm, shock waves may be attenuated in the pressure transmission layer 23, and shock waves of appropriate strength may not be properly propagated to the layered body 1.

[0029] As described above, the energy absorbing layer 22 is a layer that receives laser light and generates shock waves. The energy absorbing layer 22 may be disposed (formed) on the surface of the pressure propagation layer 23 by coating or pouring it onto the surface of the pressure propagation layer 23 (an example of an absorbing layer disposing step). For example, the energy absorbing layer 22 converts the energy supplied by the laser light into heat, and the heat causes the layer to rapidly evaporate itself, causing rapid expansion and generating shock waves.

[0030] The energy absorbing layer 22 of this embodiment may be formed of a viscous fluid containing, for example, graphite and oil. When the energy absorbing layer 22 contains graphite, the laser light can be efficiently converted into thermal energy. When the energy absorbing layer 22 contains oil, the energy absorbing layer 22 can be made into a flowable viscous fluid.

[0031] In this embodiment, the energy absorbing layer 22 is formed of a viscous fluid (an example of a fluid) that circulates inside and outside the processing substrate 2. FIG. 2 shows a case in which the separation apparatus 100 includes a tank 93 that stores the viscous fluid and a pump 94 that circulates the viscous fluid inside and outside the processing substrate 2. In the example shown in FIG. 2, the pump 94 supplies the viscous fluid from the tank 93 to the processing substrate 2 via a supply path F1. The viscous fluid supplied to the processing substrate 2 is discharged from the processing substrate 2 via a discharge path F2. In this manner, the viscous fluid may be supplied to and discharged from the energy absorbing layer 22 of the processing substrate 2, i.e., the viscous fluid of the energy absorbing layer 22 may be circulated.

[0032] The energy absorption layer 22 shown in FIG. 1 is preferably formed to a thickness of 50 μm to 300 μm. The energy absorption layer 22 is preferably formed to a thickness of 50 μm to 250 μm, more preferably 50 μm to 200 μm. If the energy absorption layer 22 is thinner than 50 μm, it may not be possible to generate shock waves of sufficient strength. In particular, when circulating a viscous fluid inside and outside the processing substrate 2 using a pump 94 (see FIG. 2), if the energy absorption layer 22 is thinner than 50 μm, the pressure when circulating the viscous fluid increases, and the power of the pump 94 may be insufficient to ensure appropriate circulation of the viscous fluid. If the energy absorption layer 22 is thicker than 200 μm, the energy absorption layer 22 may absorb the shock waves, preventing them from being propagated to the pressure propagation layer 23 with sufficient strength.

[0033] Because the energy absorbing layer 22 is a viscous fluid, the energy absorbing layer 22 can repeatedly generate shock waves even when it receives laser light repeatedly. That is, when the energy absorbing layer 22 receives laser light, the fluid in that portion evaporates, leaving a hole-like or void-like light-receiving mark. However, because the energy absorbing layer 22 is a fluid, it is possible for the layer 22 to self-regenerate (hereinafter simply referred to as self-regeneration) and fill in the light-receiving mark. This allows the energy absorbing layer 22 to repeatedly generate shock waves. This self-regeneration is performed efficiently (in a short time and reliably), particularly when a pump 94 (see FIG. 2) is used to circulate a viscous fluid inside and outside the energy absorbing layer 22 (processing substrate 2).

[0034] The fixing layer 21 is a solid layer, such as glass, that is transmissive to laser light. The fixing layer 21 is disposed on the surface of the energy absorbing layer 22 opposite the pressure propagation layer 23. In this embodiment, a case where plate-shaped sapphire glass is used as the fixing layer 21 will be described as an example. The energy absorbing layer 22 is sandwiched between the fixing layer 21 and the pressure propagation layer 23, and the energy absorbing layer 22 is held between the fixing layer 21 and the pressure propagation layer 23. The thickness of the fixing layer 21 is preferably 3 mm to 10 mm. The thickness of the fixing layer 21 is preferably 4 mm to 6 mm. For example, the thickness of the fixing layer 21 may be 5 mm. If the fixing layer 21 is thinner than 3 mm, the fixing layer 21 may become fragile and difficult to handle. If the fixing layer 21 is too thick, the laser light emitted by the laser light source 91 and focused by the lens 91a (see FIG. 2 ) may be distorted (e.g., the focused laser light may be diffused). If the laser light is distorted, there is a risk that the energy may not be supplied to the fixed layer 21 appropriately.

[0035] The adhesive layer 24 is a layer for adhering the layered body 1 to the processing substrate 2. The adhesive layer 24 is disposed on the surface of the pressure propagation layer 23 opposite the energy absorption layer 22. The adhesive layer 24 is made of a material that has an acoustic impedance value close to that of the pressure propagation layer 23 and the layered body 1 and that has the function of adhering the layered body 1. In this embodiment, an example in which the adhesive layer 24 is made of epoxy resin will be described.

[0036] The adhesive layer 24 is formed on the surface of the pressure transmission layer 23 by coating or the like. The adhesive layer 24 is preferably formed on the surface of the pressure transmission layer 23 immediately before bonding the layered body 1 to the processing substrate 2. The processing substrate 2 is attached to the layered body 1 by bonding the surface of the support layer 10 of the layered body 1 to the surface of the adhesive layer 24. The adhesive layer 24 and the support layer 10 are bonded in close contact with each other.

[0037] Next, the peeling device 100 shown in FIG. 2 will be described. As shown in FIG. 2, the holding container C is a holder that fixes and holds the processed piece T. Note that FIG. 2 shows a schematic perspective view of the holding container C and the processed piece T held therein, with the central portion shown as a vertical cross-sectional view. As an example, the holding container C may hold the processed piece T by surrounding the outer periphery of the processed piece T. It is preferable that the holding container C be capable of holding the processed piece T by sandwiching it in the thickness direction. The holding container C has both sides of the central portion of the processed piece T open to the outside. This allows the processed piece T to receive laser light (light ray L in FIG. 2) irradiated from the laser light source 91. In addition, the processed piece T can be observed by the imaging device 92.

[0038] As described above, the laser light source 91 is a light source that irradiates the workpiece T with laser light. The laser light source 91 may be any light source that can irradiate laser light of a predetermined intensity for a predetermined period of time. In this embodiment, the laser light source 91 is an Nd-Yag laser light source, and is described as a light source that can irradiate laser pulses as laser light of a predetermined intensity for a predetermined period of time. The laser light source 91 preferably has an energy output of 50 mJ or more per pulse as laser light, and a pulse width (half width) that can be adjusted within a range of 5 ns to 10 ns.

[0039] The laser light source 91 irradiates the processed piece T with laser light toward the processing substrate 2 side (the fixing layer 21 side). The laser light may be irradiated, for example, perpendicularly or obliquely, to the processed piece T. The laser light is focused by a lens 91a and then irradiated onto the fixing layer 21. The laser light is focused, for example, on the fixing layer 21 so that the diameter is about 1 mm to 4 mm (for example, 2.5 mm).

[0040] The imaging device 92 is a device that images the processed piece T to realize optical observation. A camera such as a CCD camera may be used as the imaging device 92. The imaging device 92 may include a microscope or a magnifying lens system corresponding to a microscope as its optical system. The imaging device 92 images the side of the object layer 11 of the processed piece T.

[0041] A specific example of the peeling and collecting method according to this embodiment will be described with reference to FIGS. 1 and 2, taking as an example a case where a peeling device 100 is used.

[0042] 1, a layered body 1 is attached to a processing substrate 2 to produce a processing piece T. At this time, the support layer 10 of the layered body 1 is placed opposite the adhesive layer 24 of the processing substrate 2, and the layered body 1 is bonded to the processing substrate 2 via the adhesive layer 24. As a result, a pressure propagation layer 23 is placed on the surface of the support layer 10 (an example of a propagation layer placement step).

[0043] 2, the processed piece T is mounted in a holding container C so that the laser light from the laser light source 91 is incident on the processed substrate 2 (fixing layer 21). Then, the laser light is irradiated from the laser light source 91. At this time, it is advisable to adjust the position of the lens 91a, etc., as necessary, so that the focus of the laser light is aligned with the energy absorption layer 22.

[0044] In the peeling and collecting method according to this embodiment, the peeling process is performed as follows.

[0045] As shown in Fig. 3, irradiation of the energy absorbing layer 22 with laser light (light beam L) causes a portion of the energy absorbing layer 22 to rapidly evaporate (so-called laser ablation), generating bubbles B, which in turn generates shock waves W (compression waves W1) as shown in Fig. 4 (an example of an irradiation step). These shock waves propagate to the layered body 1 via the pressure propagation layer 23 and adhesive layer 24. That is, the energy of the laser light is converted into shock wave energy.

[0046] If the pressure propagation layer 23 is formed of a ductile material such as an aluminum substrate, the pressure propagation layer 23 will not be damaged (will be prevented from being damaged) when a shock wave propagates. Furthermore, if the pressure propagation layer 23 is made of a material that is less susceptible to shock wave attenuation, such as an aluminum substrate, and has an acoustic impedance value close to that of the energy absorbing layer 22 and the adhesive layer 24, shock wave attenuation will be suppressed. Furthermore, if the pressure propagation layer 23 has high thermal conductivity, such as an aluminum substrate, cooling of the energy absorbing layer 22 and the pressure propagation layer 23 will proceed quickly, enabling repeated irradiation of laser light from the laser light source 91 (see FIG. 2), i.e., repeated generation of shock waves.

[0047] When the shock wave reaches the layered body 1 and the surface of the target layer 11 opposite the side facing the support layer 10, the shock wave W is reflected by this surface and becomes an expansion wave W2, as shown in Figure 5. When the expansion wave W2 reaches the interface between the support layer 10 and the target layer 11, it acts as a force that peels off this interface. This causes peeling between the target layer 11 and the support layer 10, as shown in Figure 6. If this peeled portion of the target layer 11 is separated from the support layer 10 while still in layer form, the target layer 11 can be recovered in layer form without being destroyed or crushed (an example of a peeling process).

[0048] In the irradiation step, the energy absorbing layer 22 may be repeatedly irradiated with laser light, and then in the peeling step, the object layer 11 may be peeled off in layers, separated, and collected.

[0049] FIG. 7 shows an example in which a peeling treatment was performed on a simulated electrode sheet on the positive electrode side, which has an active material layer containing lithium cobalt oxide as the active material and polyvinylidene fluoride as the binder. The current collector foil (current collector) of this electrode sheet is aluminum foil with a thickness of 16 μm. The active material layer of this electrode sheet is 65 μm. In this example, the current collector foil corresponds to the support layer of this embodiment. The active material corresponds to the material to be collected of this embodiment. The active material layer corresponds to the material layer containing the material to be collected of this embodiment.

[0050] Fig. 7 shows an example of a layered body peeling process performed by repeatedly irradiating the energy absorption layer of the substrate with laser light during the electrode sheet peeling process. Fig. 7 shows a photograph of the layered body side of the substrate that was actually subjected to the peeling process, i.e., the side of the target layer of the layered body, as seen from the front.

[0051] In FIG. 7, position P indicates the position where the peeling process was performed. The positions P can be relatively described below with position P1 as the reference. At position P1, the active material layer was peeled off by irradiating it once with a pulse of laser light at an output of 280 mJ. At position P2, the active material layer was peeled off in the same manner as at position P1. At position P2, the peeling state is the same as at position P1.

[0052] At position P3, the active material layer is peeled off by irradiating it twice in total with a laser beam pulse of the same output as that irradiated at position P1. Therefore, at position P3, a larger area of ​​the active material layer is peeled off compared to position P1. At position P4, the active material layer is peeled off in the same manner as at position P3. At position P4, the peeled state is the same as at position P3.

[0053] At position P5, the active material layer is peeled off by irradiating it once with a pulse of laser light having an output of 350 mJ, which is greater than the pulse irradiated at position P1. Therefore, at position P5, compared to position P1, a portion of the active material layer is peeled off in a manner that appears to have been pulverized. At position P5, the area of ​​the peeled active material is smaller than at positions P3 and P4. At position P6, the active material layer is peeled off in the same manner as at position P5. At position P6, the peeled state is similar to that at position P5. If the energy of the laser light pulse is too large (excessive), it appears that pulverization or destruction becomes more prevalent than peeling of the active material layer.

[0054] Specifically, the peeling treatment by repeatedly irradiating the energy absorbing layer 22 of the processed piece T shown in FIG. 1 with laser light may be performed as follows. For example, the peeling treatment may be performed by repeatedly irradiating the same position of the energy absorbing layer 22 with laser light. For example, if the peeling treatment is performed by irradiating a high-energy laser light only once, the target layer 11 may be destroyed (e.g., shattered), and the target layer 11 may not be recovered in a layered form (e.g., in the form of a plate). In such a case, the same position of the energy absorbing layer 22 may be repeatedly irradiated as necessary with laser light having an energy lower than that which destroys the target layer 11 (i.e., irradiated one or more times). This peels the interface between the target layer 11 and the support layer 10 without destroying the target layer 11, and the target layer 11 may be peeled off in layers, for separation and recovery. If the target layer 11 is broken down into, for example, fine particles, recovery of these fine particles may be time-consuming. However, peeling off and separating the target layer 11 in layers facilitates the recovery treatment.

[0055] FIG. 8 shows an image (explanatory diagram) of a case where the target layer 11 is crushed and cannot be recovered in the form of plate pieces. If the energy per pulse of the laser light during the peeling process is excessive, the target layer 11 may be crushed while being peeled off from the support layer 10, resulting in small pieces 11a as shown in FIG. 8. Therefore, it is preferable to set the energy per pulse of the laser light during the peeling process to be less than that at which the target layer 11 is destroyed, and peel the target layer 11 from the support layer 10 without crushing it, as shown in FIG. 9. In this case, by repeatedly irradiating the same position on the energy absorbing layer 22 (see FIG. 1) as necessary with the energy per pulse of the laser light during the peeling process to be less than that at which the target layer 11 is destroyed, peeling of the target layer 11 from the support layer 10 without crushing it may be possible to promote peeling.

[0056] Furthermore, the peeling process by repeatedly irradiating the energy absorption layer of the processing substrate with laser light may be performed by scanning the surface of the energy absorption layer and repeatedly irradiating different positions of the energy absorption layer with laser light. This may result in peeling of the target layer in a region corresponding to the area of ​​the energy absorption layer that has been repeatedly irradiated with the laser light by scanning. In other words, it may result in peeling of the target layer in larger pieces.

[0057] For example, as shown in FIG. 10 , target positions (positions Q1 to Qn, where n is an integer greater than or equal to 2; n=16 in FIG. 10 ) to be irradiated with laser light may be defined on the surface of the processed piece T at equal intervals, for example, in a square lattice pattern, and the energy absorbing layer 22 (see FIG. 1 ) at each target position may be sequentially irradiated with laser light. This may result in peeling of a wide area of ​​the target layer 11 corresponding to the area of ​​the energy absorbing layer 22 where laser light irradiation has been repeated while scanning, as shown in FIG. 11 . Note that in FIG. 10 , the trajectory of scanning each target position is indicated by a two-dot chain imaginary line R. In FIG. 10 , position Q1 is the position where the laser light was first irradiated, and position Qn is the position where the laser light was last irradiated. Note that the scanning trajectory illustrated in FIG. 10 is merely exemplary. In the peeling and recovery method according to this embodiment, there are no particular limitations on the scanning trajectory, the method of selecting the scanning order, or the method of selecting the target positions. [Example]

[0058] An example of the peeling process and recovery of the target layer using the peeling and recovery method according to this embodiment will be described below.

[0059] Example 1 In Example 1, a simulated electrode sheet for a battery such as a secondary battery was manufactured as a layered body. The support layer of the layered body was the current collecting foil of the simulated electrode sheet. Then, a peeling process was performed to peel the active material layer as the target layer from this layered body according to the peeling and recovery method of this embodiment. The peeling process was performed using an apparatus similar to the peeling apparatus described in the above embodiment.

[0060] The simulated electrode sheet as a layered body was produced as follows: First, 5 wt % of polyvinylidene fluoride (KF Polymer Sharp 721, manufactured by Kureha Corporation) as a binder was added to 1-methyl-2-pyrrolidone (95 wt %) as a binder solvent in a beaker, and the mixture was stirred with a stirrer while being heated to 85°C to produce a binder paste for forming an active material layer.

[0061] Then, 15% by weight of the above binder paste and 85% by weight of carbon (manufactured by Fuji Graphite Industries Co., Ltd., model MAG-4J artificial graphite) as an active material were mixed and kneaded in a beaker to prepare an active material paste in which the active material was dispersed in the binder paste.

[0062] Commercially available copper foil (30 μm thick) was used as the current collecting foil (support layer) of the simulated electrode sheet. The current collecting foil was cut into two rectangular pieces measuring 5 mm × 5 mm and one rectangular piece measuring 5 mm × 15 mm. These pieces were then attached to an aluminum substrate (5 mm thick) serving as a pressure transmission layer via an epoxy resin adhesive layer. These pieces were arranged on the aluminum substrate so that they did not come into contact with adjacent pieces.

[0063] The active material paste was then applied to a flake-shaped current collector foil, and the solvent in the active material paste was dried to form an active material layer. This formed a simulated electrode sheet as a layer on an aluminum substrate. A doctor blade (casting knife) was used to apply the active material paste to the current collector foil. The thickness of the active material layer in this simulated electrode sheet was 40 μm.

[0064] A glass substrate (5 mm thick) was placed on the surface of the aluminum substrate opposite the side where the flakes were attached (the side where the simulated electrode sheet was formed) as a fixing layer, and a viscous fluid was passed between the glass substrate and the aluminum substrate as an energy absorption layer to form a treated piece for the peeling treatment. This viscous fluid was prepared by dispersing 31 parts by weight of graphite (manufactured by Fuji Graphite Industries Co., Ltd., model: artificial graphite MAG-4J) in 193 parts by weight of oil (manufactured by Shincho Chemical Industry Co., Ltd., model: silicone oil KF-965-100CS). The gap between the glass substrate and the aluminum substrate was 200 μm. In other words, the thickness of the layer formed by the viscous fluid as the energy absorption layer was 200 μm.

[0065] Figure 12 shows a photograph of the treated pieces before the peeling process in Example 1. The three pieces of sheets T1, T2, and T3 in Figure 12 are simulated electrode sheets according to this example. Sheets T1 and T2 are rectangular, measuring 5 mm x 5 mm. Sheet T3 is rectangular, measuring 5 mm x 15 mm.

[0066] Next, target positions for irradiating the simulated electrode sheets with laser light were determined at equal intervals in a grid pattern. Each target position was determined so that the center-to-center spacing between adjacent target positions was 2 mm and the shortest distance from the outer periphery of the simulated electrode sheet was 2 mm. Then, a pulse of 220 mJ laser light (half-width: 7 ns) was irradiated once for each grid, aiming at these target positions in the viscous fluid layer serving as the energy absorption layer from the glass substrate side serving as the fixing layer, to perform the peeling process. The order of irradiation of the laser light (i.e., the scanning trajectory) was clockwise when viewing the treated piece from the active material layer (target layer) side.

[0067] FIG. 13 shows a photograph of the treated pieces after the peeling treatment in Example 1. From each of the three sheets T1, T2, and T3 (simulated electrode sheets), peeled pieces were obtained in which the active material layer (target layer) was peeled off in layers. These peeled pieces had an area exceeding 60% of the area of ​​the respective flakes. Specifically, the peeled pieces had an area of ​​90% and 75% for sheets T1 and T2, respectively, and the peeled pieces had an area of ​​60% for sheet T3. Therefore, in this example, it was evaluated that the target layer could be recovered in its layered form without being broken into small pieces. Furthermore, it was found that by scanning the surface of the energy absorption layer and repeatedly irradiating different positions on the energy absorption layer with laser light, the target layer could be recovered in its layered form while suppressing damage.

[0068] Example 2 Example 2 differs from Example 1 in that the active material layer as the target layer was changed to one containing 10% by weight of polyvinylidene fluoride, the same as used in Example 1, and 90% by weight of carbon, the same as used in Example 1; otherwise, simulated electrode sheets and treated pieces were formed in the same manner as Example 1.

[0069] Then, target positions were determined in the same manner as in Example 1, and a 200 mJ laser pulse (half width: 7 ns) was aimed at each target position and irradiated once or twice for each grating to perform a peeling treatment. That is, in Example 2, the energy of the laser beam was reduced compared to Example 1, and the number of irradiations per target position was increased as necessary to perform the peeling treatment. The number of irradiations per grating was determined by observing the peeled state of the active material layer (object layer) using an image captured by an imaging device, and after completing the first laser beam irradiation, if the active material layer had peeled off at a position corresponding to that target position, the peeling treatment at that target position was terminated. If the active material layer had not peeled off at a position corresponding to that target position, the peeling treatment at that target position was performed again.

[0070] FIG. 14 shows a photograph of the processed pieces after the peeling process in Example 2. As in Example 1, the target layer could be recovered from the three peeled pieces in a layered state without being broken into small pieces. These peeled pieces had an area exceeding 70% of the area of ​​the respective flakes. Specifically, in sheets T1 and T2, the peeled pieces had an area of ​​90% and 75%, respectively, and in sheet T3, the peeled pieces had an area of ​​70%. Therefore, it was found that even if the output per pulse of laser light was reduced, by repeatedly irradiating the same position with laser light, the target layer could be recovered in a layered state while suppressing destruction.

[0071] In this manner, a peeling and recovery method can be provided for peeling and recovering a target material layer containing a target material to be recovered from a layered body.

[0072] [Another embodiment] (1) In the above embodiment, the laser beam energy is set to a predetermined value (constant value) for each irradiation pulse, and the laser beam energy is repeatedly applied. However, the laser beam energy may be variable for each irradiation pulse.

[0073] (2) In the above embodiment, the pressure transmission layer 23 shown in Fig. 1 includes an aluminum substrate. However, the pressure transmission layer 23 is not limited to an aluminum substrate. The pressure transmission layer 23 may be made of silicon or silicon dioxide.

[0074] (3) In the above embodiment, the energy absorbing layer 22 shown in Fig. 1 is formed of a viscous fluid. However, it is not essential that the energy absorbing layer 22 be formed of a viscous fluid. The energy absorbing layer 22 may be a solid layer, for example, a thin aluminum layer.

[0075] (4) In the above embodiment, a case has been described in which a viscous fluid is supplied to and discharged from the energy absorbing layer 22, and the viscous fluid is circulated in the energy absorbing layer 22. However, the supply and circulation of the viscous fluid in the energy absorbing layer 22 is not essential. Self-regeneration will function as long as the energy absorbing layer 22 is made of a fluid.

[0076] It should be noted that the embodiments disclosed in this specification are merely examples, and the embodiments of the present disclosure are not limited to these, and can be modified as appropriate within the scope of the purpose of the present disclosure. [Industrial Applicability]

[0077] The present disclosure can be applied to a peeling and recovery method. [Explanation of symbols]

[0078] 1: Layered body 10:Support layer 100: Peeling device 11: Object layer 11a: Small piece 2: Processing board 21:Fixed layer 22: Energy absorption layer 23: Pressure transmission layer 24: Adhesive layer 91: Laser light source 91a: Lens 92: Imaging device 93: Tank 94: Pump B: Air bubbles C: Holding container F1: Supply path F2: Exhaust path L: Light P:Position P1 :Position P2 :Position P3 :Position P4 :Position P5 :Position P6 :Position Q1 :Position Qn :Position R: Virtual line T: processed piece T1: Seat T2: Sheet T3: Sheet W: Shock wave W1: Compression wave W2: Expansion wave

Claims

1. 1. A peeling and recovery method for recovering a target layer from a layered body having a target layer containing a target object to be recovered and a support layer on which the target layer is laminated, comprising: a pressure transmission layer disposing step of disposing a pressure transmission layer on the surface of the support layer; an energy absorption layer disposing step of disposing an energy absorption layer on a surface of the pressure propagation layer, the energy absorption layer receiving laser light and generating shock waves; an irradiation step of irradiating the energy absorbing layer with laser light to generate shock waves; a peeling step of peeling the target layer into layers and separating and recovering the target layer.

2. The peeling and recovery method according to claim 1 , wherein the irradiation step involves repeatedly irradiating the energy absorption layer with the laser light, and then the peeling step involves peeling the target layer in layers.

3. The peeling and recovering method according to claim 2 , wherein the peeling step is carried out after repeatedly irradiating the same position of the energy absorbing layer with the laser light in the irradiating step.

4. The peeling and recovering method according to claim 2 or 3, wherein the laser beam is repeatedly irradiated onto different positions of the energy absorbing layer by scanning the surface of the energy absorbing layer in the irradiating step, and then the peeling step is carried out.

5. The peeling and collecting method according to claim 1 , wherein the energy absorbing layer is formed of a fluid.

6. The peeling and recovery method according to claim 5, wherein a fluid is supplied to and discharged from the energy absorbing layer.

7. The peeling and recovery method according to claim 1 , wherein the layered body is an electrode sheet of a battery, and the target layer is an active material layer.

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