Method for processing a layer element

Abstract

The invention relates to a method for processing a layer element. The layer element has at least one main part with a lower face and an upper face lying opposite the lower face, a cover layer which is at least partially transparent to visible light, and at least one adhesive layer which is arranged between the cover layer and the upper face. According to the method, the adhesive layer is heated to an adhesive-layer temperature, and the lower face of the main part is cooled to a lower-face temperature.

Description

[0001] Method for processing a layer element

[0002] The invention relates to a method for processing a layered element, wherein the layered element comprises at least one base body with a bottom side and a top side opposite the bottom side, a cover layer that is at least partially transparent to visible light, and at least one adhesive layer arranged between the cover layer and the top side. The invention also relates to a device for carrying out such a method.

[0003] A layered element within the meaning of the present invention is, for example, a solar module which has the aforementioned layers. Other components and elements which have the aforementioned layers are also to be understood under the term layered element. Solar modules of the type mentioned above are being used in increasing numbers to generate electrical power from sunlight. These solar modules can, for example, be placed in small numbers on private roofs, for example on residential buildings, in order to at least partially cover the electricity needs of the house on which the solar modules are mounted. Such decentralized energy supplies are being used in increasing numbers, also for the decentralized charging of electric vehicles, for example. However, solar modules of the type mentioned above are also used in large systems on otherwise agricultural land to generate commercial electrical power and feed this into the public power grid.

[0004] A disadvantage is that solar modules only have a limited lifespan. Expensive raw materials are used in their production. For example, the conductor tracks in a large number of modules are made of silver. For this reason alone, the prior art describes methods by which these raw materials can be recycled and made accessible for reuse. For solar modules in which metal components are arranged on a glass substrate, JP 2014 / 054593 A, for example, proposes a method in which these components are removed mechanically. For solar modules that have a silicon substrate, the unpublished DE 10 2021 129 301 describes a method in which the adhesive layer arranged between the cover layer and the conductor tracks is heated in order to be able to remove the cover layer from the rest of the solar module.

[0005] The disadvantage is that this process is not applicable to all solar modules with a silicon base body. The invention therefore aims to improve the process so that it can be used for a wider range of different solar modules.

[0006] The invention solves the stated problem by a method according to the preamble of claim 1, which is characterized in that in the method the adhesive layer is heated to an adhesive layer temperature and the underside of the base body is cooled to a underside temperature. By heating the adhesive layer it is possible to remove the cover layer from the rest of the layer element. The cover layer is preferably a glass layer which is particularly preferably completely transparent to visible light. By heating the adhesive layer the adhesive force of the adhesive layer decreases and the cover layer can be removed. The heat introduced into the adhesive layer is dissipated within the layer element and gradually heats other layers and elements of the layer element. Often a plastic layer, for example made of polyvinyl fluoride (PVF), is arranged on the underside of the base body.The material of this plastic layer is generally less heat-resistant than the base body, the cover layer, and especially the adhesive layer. The heat applied to heat the adhesive layer also heats the plastic layer, which can decompose it, releasing harmful and hazardous gases. This is prevented according to the invention by cooling the underside of the base body to a lower surface temperature. For the purposes of the present invention, processing a layer element includes, for example, at least partially disassembling the layer element. In a preferred embodiment, this is done by removing the cover layer entirely or partially from the base body. This preferably occurs without damaging or destroying the cover layer. However, this is not necessarily the case.Even if the cover layer is damaged or destroyed during the complete or partial removal from the base body and / or before the complete or partial removal from the base body, this is “processing” within the meaning of the present invention.

[0007] This does not mean that the underside is cooled to a temperature below room temperature during the process. Before the process begins, the underside of the base body of the layered element has a temperature significantly below the target underside temperature. It simply means that heat is dissipated from the underside of the base body to reach and, preferably, maintain the underside temperature. The underside temperature is lower than the bond layer temperature.

[0008] In order to cool the underside of the base body to a bottom temperature, a cooling device is provided through which heat is dissipated from the underside of the base body.

[0009] One difficulty overcome by the method according to the invention is that the conductor tracks of the layer elements, for example of solar modules made from the valuable raw material, are not accessible from the outside. Although they are located on the upper side of the base body, they are covered by the cover layer, which is secured by the at least one adhesive layer. By heating the adhesive layer, its adhesive effect is reduced, so that the cover layer and the base body can then be removed from each other. The conductor tracks arranged on the upper side of the base body are then accessible. They are then removed from the base body by mechanical ablation, and the material removed in this process is collected.The layer element is preferably a solar module, wherein the layer element preferably has metallic conductor tracks, which are particularly preferably arranged on the upper side of the base body and are covered by the cover layer.

[0010] The adhesive layer temperature is preferably at least 180°C, preferably at least 200°C, more preferably at least 230°C and at most 400°C, preferably at most 350°C, most preferably at most 280°C. This is particularly advantageous when the adhesive layer is a layer made of or containing ethylene vinyl acetate (EVA). The adhesive layer temperature is preferably selected such that pyrolysis of the adhesive layer, which can release toxic and environmentally harmful gases, does not occur. This is avoided at a temperature below 400°C. At a temperature of more than 180°C, preferably more than 200°C, acetic acid is released in an EVA adhesive layer, forming a lubricating film between the layers connected by the adhesive layer. As a result, the adhesive forces exerted by the adhesive layer decrease, and the two elements connected to one another can be separated.Preferably, therefore, at least one EVA film is used as the adhesive layer.

[0011] Preferably, the bottom temperature is at most 150°C, preferably at most 110°C, particularly preferably at most 100°C. The lower this temperature, the lower the effects of the heat on layers arranged on the underside of the base body.

[0012] The base body preferably has a structure composed of several layers arranged next to one another. The underside of the base body forms the underside of the layer element that is processed by the methods described here. The base body has, for example, a substrate that is preferably made of silicon, particularly preferably consists of silicon, and has a charge-doped zone and a hole-doped zone. The metallic conductor tracks are arranged on the top side of this substrate, which forms the top side of the base body. The underside of the substrate does not necessarily have to form the underside of the layer element. Further layers, for example the plastic layer already mentioned, can be arranged on the underside of the substrate. The underside of the base body preferably forms the underside of the layer element.

[0013] In a preferred embodiment, the adhesive layer is heated by means of infrared radiation and / or magnetic induction and / or microwave radiation.

[0014] Particularly when using infrared or microwave radiation, it is advantageous to apply the radiation through the cover layer, which is preferably at least partially, but preferably completely, transparent to the respective type of radiation. Infrared radiation used to heat the adhesive layer preferably has a wavelength of 1000 to 4000 nm, more preferably 1000 to 2000 nm.

[0015] If microwave radiation is used, it preferably has a frequency between 2.4 GHz and 2.5 GHz, preferably 2.45 GHz. Alternatively, the microwave radiation has a frequency of 5.8 GHz.

[0016] Heating by magnetic induction uses alternating magnetic fields with a frequency preferably between 1 kHz and 500 kHz. One usable frequency range is referred to as the low-frequency range and includes frequencies between 1 kHz and 7 kHz. Another frequency range is referred to as the medium-frequency range and includes frequencies between 8 kHz and 40 kHz. The high-frequency range includes frequencies between 60 kHz and 500 kHz. The frequency used is preferably between 25 kHz and 300 kHz, particularly preferably between 25 kHz and 100 kHz.

[0017] The invention also achieves the stated object by a device for carrying out one of the methods described here, which is characterized in that the device has a heating device for heating the adhesive layer of a layer element to the adhesive layer temperature and a cooling device for cooling the underside of the base body of the layer element to the underside temperature.

[0018] The device preferably has a holding device with which the layer element that is processed by means of the device is held. The device preferably has a work table for supporting the layer element, wherein the cooling device is preferably arranged within the work table. In a particularly preferred embodiment, the work table has a support surface on which the layer element rests while the method is being carried out. This support surface can preferably be cooled by the cooling device. The holding device with which the layer element is held is, for example, a pulling device for exerting a pulling force. This can, for example, have at least one negative pressure element, for example a suction element. The layer element is, for example, positioned on openings within the support surface, which are closed by the layer element.By applying a negative pressure or a suction force to the closed openings, a suction force and thus a tensile force is exerted on the layer element, which holds it to the support surface.

[0019] Alternatively or additionally, the holding device has a pressure device for exerting a compressive force. This compressive force presses the layer element against the support surface. The pressure device preferably has at least one, preferably several, hold-down devices. These are preferably movable relative to the support surface. The hold-down devices are preferably removed from the support surface in order to arrange a layer element to be processed on the support surface. The hold-down devices are then lowered until they come into contact with the layer element and can exert a compressive force on the layer element.

[0020] The cooling device preferably has at least one fluid channel through which a cooling medium can be conducted. The cooling medium is, for example, a cooling liquid, such as water. The cooling device preferably has a pump that moves the cooling medium through the fluid channel. If the fluid channel is located within the work table, it is advantageous if it is made of a material with high thermal conductivity, for example, a metal such as aluminum or steel.

[0021] Preferably, the at least one cooling channel is located as close as possible to the actual support surface of the work table, for example, at most 15 cm, preferably at most 10 cm, and particularly preferably at most 5 cm from the support surface. The material of the work table, at least the material of the work table located between the at least one cooling channel and the support surface, preferably has a high thermal conductivity. The material is preferably a metal, for example, aluminum or steel.

[0022] Alternatively or additionally, the cooling device has at least one fan through which air can be directed to the underside of the layer element. The fan can, for example, be designed in the form of one or more fans arranged and oriented to move air toward the underside of the layer element.

[0023] Alternatively or additionally, the cooling device has at least one device for expelling compressed air. This device is configured such that compressed air, originating from a compressed air source that is preferably part of the cooling device, but at least part of the device, is directed to the underside of the layer element. In the methods described here, the underside of the layer element is preferably cooled via the fan and / or the device for expelling compressed air.

[0024] The device preferably has a first temperature sensor for detecting the adhesive layer temperature and / or a second temperature sensor for detecting the underside temperature. The first temperature sensor and / or the second temperature sensor preferably has a pyrometer, by means of which the occurring temperatures can be detected, preferably without contact. The device preferably has an electrical control system, particularly preferably an electronic data processing device, which is configured to control the heating device and / or the cooling device depending on the detected adhesive layer temperature and / or the detected underside temperature. For this purpose, the respectively detected temperature is compared with a target temperature stored in an electronic data memory. The target temperature can also be a temperature range within which the detected temperature should lie.The electrical control is configured to increase the heating device's power and / or the heating duration if the detected adhesive layer temperature is deemed too low after comparison with a stored target temperature. Preferably, the electrical control is alternatively or additionally configured to increase the cooling device's power and / or the cooling duration if the detected underside temperature is deemed too high after comparison with a stored target temperature.

[0025] Some embodiments of the present invention are explained in more detail below with the aid of the accompanying drawings. They show:

[0026] Figures 1 - 6 schematic representations of a layer element in the process.

[0027] Figure 1 shows a layer element 2 designed as a solar module. It has a base body 4, on the upper side 6 of which are conductor tracks (not shown in the figures). The layer element 2 also has a cover layer 8, which is made of glass, for example. The cover layer 8 is arranged on the base body 4 by means of an adhesive layer 10. On the underside 12 of the base body 4, opposite the upper side 6, a rear side 16 is arranged by means of a further adhesive layer 14. In the method, for example, the layer element 2 is to be processed by recycling it. For this purpose, the cover layer 8 must first be removed. To achieve this, the adhesive layer 10 is heated, for which purpose a radiant heater 18 is used in the embodiment shown in Figure 1. The upper side of the layer element 2 is heated by means of schematically illustrated thermal radiation.Since the cover layer 8 is at least partially, but preferably completely transparent to the radiation, which can also be visible light, for example laser radiation, the adhesive layer 10 is heated by the thermal radiation and thus at least partially loses its adhesive effect.

[0028] The back side 16 of the layer element 2 comes into contact with a work table 20 in which a cooling device 22 is located. This is schematically shown as a solid line and can, for example, have cooling channels through which a cooling medium is passed.

[0029] Figure 2 differs from Figure 1 only in the modified cooling device 22. In Figure 2, this is implemented in the form of several fans 24, through which air is directed to the rear side 16 of the layer element. This can be done, for example, through openings in the work table.

[0030] Figure 3 shows the layer element 2 and the radiant heater 18. Two temperature sensors 26 are provided to determine the temperature of the cover layer 8 and the back side 16. These sensors can be used to measure the corresponding temperatures and transmit the measured data to an electrical controller (not shown) that controls the heating device and / or the cooling device.

[0031] In the embodiment shown in Figure 4, the layer element 2 rests on the work table 20, which is designed as a cooling plate 28. This cooling plate 28 is part of the cooling device 22. In the exemplary embodiment shown, the cooling device 22 also has cooling fins 30, which are arranged on the side of the work table 20 facing away from the layer element 2. This makes it possible to dissipate heat transferred from the layer element 2 to the work table 2 and the cooling plate 28. The heat is preferably released into the surrounding air. For this purpose, the cooling fins 30 are preferably cooled with at least one, preferably several fans, which are not shown in Figure 4. Figure 5 shows a further embodiment. The layer element 2 is positioned on the work table 20, in which the cooling device 22 is located, as in Figure 1.In the exemplary embodiment shown, a vacuum plate 32 is arranged between the layer element 2 and the part of the work table 20 which has the cooling device. This vacuum plate 32 exerts a suction force on the layer element 2 and thus holds it to the work table 20, of which the vacuum plate 32 preferably forms a part. The figure largely corresponds to Figure 1. Unlike there, in Figure 6 the work table 20 is not equipped with a holding device, for example a suction device. The layer element 2 can therefore be moved on the upper side of the work table 20, for example to change the area heated by the radiant heater 18. Rollers 34 are used for this purpose, which are shown on the upper side of the layer element 2. The rollers can be rotated in two directions, one of which is illustrated by the arrow shown in Figure 6.

[0032] List of reference symbols

[0033] 2 layer element

[0034] 4 Base body 6 Top side

[0035] 8 Top layer

[0036] 10 adhesive layer

[0037] 12 Bottom

[0038] 14 Adhesive layer 16 Back

[0039] 18 radiant heaters

[0040] 20 work table

[0041] 22 Cooling device

[0042] 24 Fan 26 Temperature sensor

[0043] 28 Cooling plate

[0044] 30 cooling fins

[0045] 32 vacuum plate

[0046] 34 roller

Claims

Patent claims 1. A method for processing a layer element, wherein the layer element comprises at least one base body with a bottom surface and a top surface opposite the bottom surface, a cover layer that is at least partially transparent to visible light, and at least one adhesive layer arranged between the cover layer and the top surface, characterized in that, in the method, the adhesive layer is heated to an adhesive layer temperature and the bottom surface of the base body is cooled to a bottom surface temperature.

2. Method according to claim 1, characterized in that the layer element is a solar module, wherein the layer element preferably has metallic conductor tracks which are particularly preferably arranged on the top side of the base body and are covered by the top layer.

3. Method according to claim 1 or 2, characterized in that the adhesive layer temperature is at least 180 °C, preferably at least 200 °C, particularly preferably at least 230 °C and at most 400 °C, preferably at most 350 °C, particularly preferably at most 280 °C.

4. Method according to one of the preceding claims, characterized in that the underside temperature is at most 150 °C, preferably at most 110 °C, particularly preferably at most 100 °C.

5. Method according to one of the preceding claims, characterized in that the adhesive layer is heated by means of infrared radiation and / or magnetic induction and / or microwave radiation. A device for carrying out a method according to any one of the preceding claims, characterized in that the device comprises a heating device for heating the adhesive layer of a layer element to the adhesive layer temperature and a cooling device for cooling the underside of the base body of the layer element to an underside temperature. A device according to claim 6, characterized in that the device comprises a worktable for supporting the layer element, wherein the cooling device is arranged in the worktable. A device according to claim 6 or 7, characterized in that the cooling device comprises at least one fluid channel through which a cooling medium can be conducted. A device according to any one of claims 6 to 8, characterized in that the cooling device comprises at least one fan through which air can be directed onto the underside of the layer element.A device according to any one of claims 6 to 9, characterized in that the device comprises a first temperature sensor for detecting the adhesive layer temperature and / or a second temperature sensor for detecting the underside temperature. A device according to claim 10, characterized in that the device comprises an electrical control unit, preferably an electronic data processing unit, which is configured to control the heating device and / or the cooling device depending on the detected adhesive layer temperature and / or the detected underside temperature.

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