Preparation method and device of composite heat-conducting layer and manufacturing method of longitudinal heat-conducting body

Abstract

The application discloses a preparation method and device of a composite heat-conducting layer and a manufacturing method of a longitudinal heat-conducting body. The preparation method comprises the following steps: providing a composite base film, which comprises a hot melt adhesive layer and a bottom layer carrier film; laying a graphene heat-conducting layer and continuously covering a top layer coating film; performing heat pressing, and the bonding strength between the graphene heat-conducting layer and the top layer coating film is lower than the bonding strength between the graphene heat-conducting layer and the hot melt adhesive layer, and the bonding strength between the top layer coating film and the hot melt adhesive layer in the vacant area is higher than the bonding strength between the hot melt adhesive layer and the bottom layer carrier film; separating the top layer coating film from the self-assembly body, and simultaneously taking away the hot melt adhesive layer in the vacant area during the separation process. The application utilizes the bonding force difference caused by the difference in the bonding capacity of the designed materials, so that in the continuous preparation process, the hot melt adhesive film in the area without covering the graphene heat-conducting layer can be synchronously and more thoroughly removed only by peeling off the top layer coating film, the preparation process is efficient and simple, and the edge removal quality is improved.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive composite materials technology, and in particular to a method and apparatus for preparing a composite thermally conductive layer and a method for manufacturing a longitudinal thermally conductive body. Background Technology

[0002] In recent years, with the continuous development of technology, electronic products have increasingly moved towards thinner, lighter, and more integrated designs. However, this has also led to higher heating temperatures, and overheating often shortens the lifespan of electronic devices and reduces their operational stability. Graphene possesses excellent thermal conductivity, making it the carbon material with the highest thermal conductivity to date. Novel graphene thermal conductive layers have attracted much attention due to their outstanding thermal conductivity and heat flux, as well as their excellent flexibility and lightweight characteristics.

[0003] The properties of graphene determine that its thermal conductivity along the thickness direction is far less than that along the spreading direction. Therefore, many existing technologies provide solutions to arrange graphene longitudinally in the thermal conductor to construct a graphene longitudinal thermal conductor.

[0004] To protect the surface integrity of graphene sheets, maintain their smoothness and gloss, and improve their wear resistance, moisture resistance, and stain resistance, the formed graphene sheets need to undergo film-composite processing. This can be achieved by layering polymer layers with graphene layers, then accumulating multiple layers to form a multi-layered longitudinal thermal conductor. Currently, existing technologies lack the necessary equipment and processes for coating graphene thermal conductive films, hindering continuous production of the coating and stacking process and limiting its applications. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method, apparatus, and fabrication method for a composite thermally conductive layer and a longitudinal thermal conductor. By utilizing the designed differences in bonding strength between different material layers, the bonding and peeling processes of the materials are completed continuously, greatly improving the fabrication efficiency and also enhancing the peeling quality of the composite thermally conductive layer edges.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] In a first aspect, the present invention provides a method for preparing a graphene composite thermally conductive layer, comprising:

[0008] A composite base film is provided, the composite base film comprising a hot melt adhesive layer and a bottom carrier film, the hot melt adhesive layer having a first side and a second side opposite to each other, the second side being bonded to the bottom carrier film;

[0009] A graphene thermal conductive layer is laid on the first surface and then covered with a top layer film to form an assembly. The top layer film continuously covers the graphene thermal conductive layer and the empty areas on the first surface that are not covered by the graphene thermal conductive layer.

[0010] The assembly is hot-pressed to bond the layers together. After hot pressing, the bonding strength between the graphene thermally conductive layer and the top coating is lower than the bonding strength between the graphene thermally conductive layer and the hot melt adhesive layer. In the empty area, the bonding strength between the top coating and the hot melt adhesive layer is higher than the bonding strength between the hot melt adhesive layer and the bottom carrier film.

[0011] The top coating is separated from the assembly, and the hot melt adhesive layer in the vacant area is simultaneously removed during the separation process.

[0012] Secondly, the present invention also provides a method for fabricating a graphene longitudinal thermal conductor, comprising:

[0013] Multiple graphene composite thermally conductive layers were prepared using the above preparation method;

[0014] Multiple layers of the graphene composite thermal conductive layer are stacked along the thickness direction, and the hot melt adhesive layer therein is bonded to the adjacent graphene thermal conductive layer. The graphene longitudinal thermal conductor can be obtained by selectively slicing along the thickness direction or not slicing.

[0015] Thirdly, the present invention also provides an apparatus for preparing a graphene composite thermally conductive layer, comprising the following components arranged sequentially along a process order:

[0016] A base film providing module is used to provide a composite base film, the composite base film including a hot melt adhesive layer and a bottom carrier film, the hot melt adhesive layer having a first side and a second side opposite to each other, the second side being bonded to the bottom carrier film;

[0017] The assembly module is used to lay the graphene thermal conductive layer on the first surface and continue to cover it with a top layer film to form an assembly. The top layer film continuously covers the graphene thermal conductive layer and the empty areas on the first surface that are not covered by the graphene thermal conductive layer.

[0018] A hot-pressing module is used to hot-press the assembly so that the layers in the assembly are bonded together. After hot pressing, the bonding strength between the graphene thermally conductive layer and the top coating is lower than the bonding strength between the graphene thermally conductive layer and the hot melt adhesive layer. In the empty area, the bonding strength between the top coating and the hot melt adhesive layer is higher than the bonding strength between the hot melt adhesive layer and the bottom carrier film.

[0019] A film removal module is used to separate the top film from the assembly and simultaneously remove the hot melt adhesive layer in the vacant area during the separation process.

[0020] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include at least the following:

[0021] The method and apparatus for preparing the composite thermal conductive layer provided by this invention utilize the designed differences in the adhesive strength of the materials to create differences in the bonding force between the bottom carrier film, the top coating film, and the intermediate hot melt adhesive film. Furthermore, by utilizing the natural differences in the bonding force between the hot melt adhesive film and the graphene thermal conductive layer and the top coating film, the hot melt adhesive film in the areas not covered by the graphene thermal conductive layer can be removed relatively thoroughly and simultaneously by peeling off the top coating film during continuous preparation. This allows multiple graphene composite thermal conductive layers to be separated from each other, making the preparation process highly efficient and simple, greatly improving production efficiency and edge removal quality. This is beneficial for the mass production of composite thermal conductive layers or further mass production of graphene longitudinal thermal conductors.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below in conjunction with detailed drawings. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of a method for preparing a graphene composite thermally conductive layer according to a typical embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of the preparation device for the graphene composite thermal conductive layer provided in a typical embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the preparation process and device operation status of the graphene composite thermal conductive layer provided in a typical embodiment of the present invention.

[0026] Figure 4 This is an example photograph of the preparation process of the graphene composite thermal conductive layer provided in a typical embodiment of the present invention.

[0027] Explanation of reference numerals in the attached drawings: 1. Machine body; 2. Feeding platform; 3. Unloading platform; 4. Feeding assembly; 5. Upper feeding roll; 6. Upper take-up roll; 7. Lower feeding roll; 8. Next take-up roll; 9. Second take-up roll; 10. Cooling plate one; 11. First pressure roller; 12. Heating roller; 13. Second pressure roller; 14. Cooling plate two; 15. Scraper. Detailed Implementation

[0028] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0030] Moreover, relational terms such as “first” and “second” are used merely to distinguish one component or method step from another that has the same name, and do not necessarily require or imply any such actual relationship or order between these components or method steps.

[0031] This invention provides a method for preparing a graphene composite thermally conductive layer, which includes the following steps:

[0032] A composite base film is provided, the composite base film comprising a hot melt adhesive layer and a bottom carrier film, the hot melt adhesive layer having a first side and a second side opposite to each other, the second side being bonded to the bottom carrier film.

[0033] A graphene thermally conductive layer is laid on the first surface and then covered with a top layer film to form an assembly. The top layer film continuously covers the graphene thermally conductive layer and the empty areas on the first surface that are not covered by the graphene thermally conductive layer.

[0034] The assembly is hot-pressed to bond the layers together. After hot pressing, the bonding strength between the graphene thermally conductive layer and the top coating is lower than the bonding strength between the graphene thermally conductive layer and the hot melt adhesive layer. In the empty area, the bonding strength between the top coating and the hot melt adhesive layer is higher than the bonding strength between the hot melt adhesive layer and the bottom carrier film.

[0035] The top coating is separated from the assembly, and the hot melt adhesive layer in the vacant area is simultaneously removed during the separation process.

[0036] In some embodiments, after removing the top coating, the preparation method may further include:

[0037] The underlying carrier film is separated from the assembly to obtain a graphene composite thermally conductive layer formed by the graphene thermally conductive layer and the hot melt adhesive layer.

[0038] In some embodiments, the underlying carrier film is peeled off after the assembly is frozen.

[0039] In some embodiments, the process of providing the composite substrate includes:

[0040] A composite precursor membrane is provided, the composite precursor membrane comprising the composite base membrane and a protective membrane covering the first surface.

[0041] The protective film is removed from the composite precursor film to obtain the composite base film.

[0042] In some implementations, the preparation process of the graphene composite thermal conductive layer is carried out continuously.

[0043] In some embodiments, the material of the bottom carrier film and / or the top coating film is selected from any one or a combination of two or more of PET, PE, PS, PC, and ABS.

[0044] In some embodiments, the material of the hot melt adhesive layer is selected from any one or a combination of two or more of the following: low-temperature curing epoxy resin film, TPU hot melt adhesive film, and EVA hot melt adhesive film. In the provided embodiments, the commonly used hot melt adhesive layer material is a low-temperature curing epoxy resin film of model EC0711DL-6 or EC0714. The low-temperature curing epoxy film refers to an epoxy film cured under freezing conditions (e.g., below 0°C or 10°C, but not limited to these).

[0045] In some embodiments, a separating material is also present at the interface between the underlying carrier film and the hot melt adhesive layer, which reduces the adhesion between the underlying carrier film and the hot melt adhesive layer. Of course, regardless of the method used, it is sufficient to satisfy the aforementioned relationship between the magnitudes of the bonding forces.

[0046] As some typical application examples of the above technical solutions, the continuous preparation process of graphene composite thermal conductive layers is as follows: Figure 1 As shown, the illustrated example represents a typical film material, but does not imply that the possible embodiments of the present invention are limited to this. In this implementation process, the PE layer in the three-layer composite PE-epoxy-PET2 film (i.e., the composite precursor film) is first continuously peeled off to provide a continuous epoxy-PET2 composite film; then, a graphene thermally conductive layer is continuously laid on the surface of the epoxy layer of the moving film layer; and after hot pressing by a coating roller, a PET1 film is placed as the top coating; the PET1 film is removed by continuous winding and tearing, and at the same time, the epoxy film not located in the graphene thermally conductive layer region is removed by utilizing the difference in bonding force; then, the PET1 film layer is removed by an appropriate method to obtain an independent graphene composite thermally conductive layer.

[0047] In a more specific implementation, after hot pressing PET film 1 and PET film 2 with epoxy adhesive using heated rollers, the two sides of the epoxy adhesive are bonded to PET film 1 and PET film 2 respectively. Since PET film 2 is a PET film coated with silicone oil, the adhesion between PET film 1 and epoxy adhesive is greater than that between PET film 2 and epoxy adhesive. Therefore, the tear-off effect can be achieved by utilizing the difference in the above-mentioned bonding forces. Furthermore, in this implementation, if a very small amount of epoxy adhesive remains on PET film 2, due to the tearing force of the PET film layer, the subsequent cooling and winding will allow PET film 2 to directly wind up and carry away the small amount of residual epoxy adhesive, without leaving any residue bonded to the heat conductor.

[0048] Further applications of this graphene composite thermal conductive layer include direct application, or multi-layer stacking as described below to prepare a superior longitudinal multilayer thermal conductor.

[0049] More specifically, in some implementations, the separating material may include, for example, any one or a combination of two or more of the following: silicone oil or other oily substances, or powdered substances. The goal is simply to reduce interlayer bonding strength.

[0050] In some implementations, after hot pressing, the bonding strength between the top coating and the hot melt adhesive layer is more than twice the bonding strength between the hot melt adhesive layer and the bottom carrier film.

[0051] In some implementations, the top coating is immediately peeled off at an angle after the hot-pressed assembly undergoes a second rolling process.

[0052] In some implementations, when the top coating is torn off at an angle, the angle between the separated top coating and the assembly is 30-80°.

[0053] In some implementations, the tension of the removed top coating is controlled at 60-70 N / m.

[0054] As a further application of the above technical solution, this embodiment of the invention also provides a method for fabricating a graphene longitudinal thermal conductor, which includes the following steps:

[0055] Multiple graphene composite thermally conductive layers can be prepared using the preparation method provided in any of the above embodiments.

[0056] Multiple layers of the graphene composite thermal conductive layer are stacked along the thickness direction, and the hot melt adhesive layer therein is bonded to the adjacent graphene thermal conductive layer. The graphene longitudinal thermal conductor can be obtained by selectively slicing along the thickness direction or not slicing.

[0057] Specifically, when the longitudinal direction of the longitudinal heat conductor is required to be wide, it may not be necessary to slice it. When the required longitudinal thickness is thin, it is usually necessary to slice the stacked and hot-pressed block into thin sheets as the graphene longitudinal heat conductor.

[0058] To achieve the above preparation method, this embodiment of the invention also provides a preparation apparatus for a graphene composite thermally conductive layer, comprising the following components arranged sequentially along the process order:

[0059] A base film providing module is used to provide a composite base film, the composite base film including a hot melt adhesive layer and a bottom carrier film, the hot melt adhesive layer having a first side and a second side opposite to each other, the second side being bonded to the bottom carrier film.

[0060] The assembly module is used to lay the graphene thermally conductive layer on the first surface and continue to cover it with a top coating to form an assembly. The top coating continuously covers the graphene thermally conductive layer and the empty areas on the first surface that are not covered by the graphene thermally conductive layer.

[0061] A hot-pressing module is used to hot-press the assembly to bond the layers in the assembly. After hot pressing, the bonding strength between the graphene thermally conductive layer and the top coating is lower than the bonding strength between the graphene thermally conductive layer and the hot melt adhesive layer. In the empty area, the bonding strength between the top coating and the hot melt adhesive layer is higher than the bonding strength between the hot melt adhesive layer and the bottom carrier film.

[0062] A film removal module is used to separate the top film from the assembly and simultaneously remove the hot melt adhesive layer in the vacant area during the separation process.

[0063] In some implementations, the assembly module includes a feeding assembly, a coating roller, and a first pressure roller assembly.

[0064] The feeding assembly is used to lay the graphene thermally conductive layer onto the first side of the spread composite base film; the first pressure roller group is used to gather the composite base film with the graphene thermally conductive layer laid on it and the top coating film, and perform preliminary pressing to form the assembly.

[0065] In some embodiments, the hot pressing module includes a second pressure roller group containing at least one heating roller shaft for hot pressing the assembly.

[0066] In some embodiments, the preparation apparatus may further include:

[0067] The bottom film removal module is used to separate the bottom carrier film from the assembly to obtain a graphene composite thermally conductive layer formed by the graphene thermally conductive layer and the hot melt adhesive layer.

[0068] In some embodiments, the bottom film removal module includes a cooling plate, a scraper, a take-up roller, and a take-up assembly; the cooling plate is used to freeze the assembly, the scraper is used to separate the bottom carrier film and the hot melt adhesive layer in the assembly, the take-up roller is used to continuously take up the separated bottom carrier film, and the take-up assembly is used to pick up the separated graphene composite thermally conductive layer.

[0069] As some typical application examples of the above technical solutions, such as Figures 2-3 As shown, the preparation device includes a processing body 1, a loading platform 2, and a unloading platform 3.

[0070] Both the loading platform 2 and the unloading platform 3 are equipped with a feeding assembly 4. The feeding assembly 4 includes two vertically arranged moving modules. The vertically arranged moving module is fixed to the slider of the horizontally arranged moving module. The slider of the vertically arranged moving module is connected to a suction cup. The suction cup is used to pick up and put down graphene sheets as graphene thermal conductive layers. Both the loading platform 2 and the unloading platform 3 are equipped with sheet material boxes. The size and shape of the sheet material boxes are determined according to the sheet material. The suction cup picks up and puts down the sheet material from the sheet material boxes.

[0071] For example, the top of the sheet material box on the loading platform 2 is equipped with a detection sensor, and the bottom of the sheet material box is equipped with a lifting mechanism. The lifting mechanism consists of a cylinder, a push rod, and a guide frame. The guide frame is vertically set, and the push rod is fixed to the end of the cylinder, with the end of the push rod abutting against the bottom of the bottom sheet in the sheet material box. When the top sheet is removed, the detection sensor sends a signal, and the cylinder pushes a distance equal to the thickness of a sheet, pushing the sheet in the sheet material box upwards to ensure that the suction cup can smoothly remove the sheet. Of course, the specific loading method can be different, and even manual placement and loading can be used, as long as it can achieve high-efficiency continuous operation and continuous laying of the graphene thermal conductive layer.

[0072] The machine body 1 is equipped with an upper feed roll 5, an upper take-up roll 6, a lower feed roll 7, a lower take-up roll 8, and a lower second take-up roll 9. The upper feed roll winds PET film 1, and the lower feed roll winds an epoxy film roll sandwiched between the PET film 1 and the epoxy film roll. The epoxy film roll is composed of epoxy film, PET film 2, and PE film (PET film 2 and PE film sandwich epoxy film, and both PET film 2 and PE film are coated with silicone oil to reduce their adhesion to the epoxy film). The upper take-up roll 6 is used to wind up PET film 1, and the lower take-up roll 8 and the lower second take-up roll 9 are used to wind up PE film and the final PET film 2, respectively.

[0073] A tensioning roller is provided on each side of the machine body 1, thus forming an end for placing the sheet and an end for removing the sheet. The machine body 1 is provided with a first pressure double roller 11, a bottom heating double roller 12 and at least one second pressure double roller 13. The first pressure double roller 11 and the bottom heating double roller 12 are located between the upper feed roll 5 and the upper take-up roll 6. The second pressure double roller 13 is located on the side of the upper take-up roll 6 facing the unloading platform 3. A second cooling plate 14 is provided between the second pressure double roller 13 and the unloading platform 3. A scraper 15 is fixed on the side of the second cooling plate 14 facing the unloading platform 3. The top of the scraper 15 is slightly higher than the second cooling plate 14. The lower feed roll 7 and the next take-up roll 8 are located in the same box below the machine body 1. A first cold insulation cooling plate 10 is provided in the box to maintain the low temperature inside the box.

[0074] During formal processing, the epoxy film roll wound on the unloading roll 7 is in a low-temperature environment created by the cold insulation plate 10, which reduces the adhesion between the PE film and the epoxy film. The PE film is then torn off by the next take-up roll 8, so that when the epoxy film is on the end used to place the sheet, the other PET film 2 faces the machine body 1 and the epoxy film faces upward.

[0075] Two moving modules on the loading platform 2 move horizontally and vertically, and use suction cups to pick up the graphene sheets from the sheet box and place them on the end of the machine body 1 for placing the sheets, so that the sheets fall onto the epoxy film. Then, before passing through the first pressure roller 11, the PET film 1 on the unloading roll 5 is pressed together with the heat-conducting layer on the side away from the epoxy film, so that the PET film 1 is covered on the film. The rollers perform preliminary pressing of the heat-conducting layer, epoxy film and PET film, and then pass through... The epoxy film is then heated by the bottom rollers 12, which bond the epoxy film to the thermally conductive layer. At this point, the adhesion strength between the epoxy film below the thermally conductive layer and the graphene thermally conductive layer is greater than the adhesion strength between the epoxy film and the PET film 2. The adhesion strength between the excess epoxy film below the thermally conductive layer (between the two thermally conductive layers and at both ends of the thermally conductive layer) and the PET film 1 is greater than the adhesion strength between the epoxy film and the PET film 2. The film is then rolled again by the second pressure rollers 13. Then, the PET film 1 is wound up by the upper take-up roll 6. Because the bonding strength between the epoxy film and the PET film 1 is greater than that between the epoxy film and the PET film 2, the excess epoxy film (part of the epoxy film not in the heat-conducting layer area) will be simultaneously torn off during the winding of the PET film 1. Then, after passing through the second cooling plate 14, the adhesion between the epoxy film and the PET film 2 decreases and separates under the action of the low temperature. Then, under the action of the scraper 15, the sheet after the heat-conducting layer and the epoxy film are integrated is lifted up, so that the sheet is separated from the PET film 2. Then, the PET film 2 is wound up by the second lower take-up roll 9. At this time, the sheet is only a combination of the heat-conducting layer and the epoxy film, and there is no excess epoxy film and PET film adhering. Then, the two moving modules on the unloading table 3 move horizontally and vertically, and use suction cups to pick up the independent sheet from the end of the machine body 1 used to place the sheet into the sheet box, thus completing the preparation process of the multi-sheet graphene composite heat-conducting layer.

[0076] The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only for illustrating the present invention and do not limit the scope of the present invention.

[0077] Example 1

[0078] This embodiment illustrates the preparation process of a graphene composite thermally conductive layer, as detailed below:

[0079] Using the above embodiments Figure 2 and Figure 3 The corresponding preparation device sets the pressure applied by the bottom roller heating double roller 12 to 30-100N, and the heating temperature of the bottom roller to 55-75℃ (the pressure is related to the flatness of the heat-conducting film; excessive pressure will cause wrinkles). This roller is the active roller, used to limit the overall production speed. The roller speed is 1m / s, which means the product transmission speed is 1m / s.

[0080] The angle between the second pressure roller 13 on the far right of the figure and the upper take-up roller 6 is 30-80°, with the optimal actual angle being 45° and 80°. (This angle affects the tearing of the adhesive; if the angle is too large, it will be difficult to tear off the adhesive, and if the angle is too small, it may cause the thermal conductive film to be lifted, affecting processing and product quality. 45° is the best.) The cooling temperature of the second cooling plate 14 is (-5)-(-10)℃ (this temperature can be used for rapid cooling, allowing the epoxy adhesive and PET film to separate quickly). The first cooling plate 10 maintains the temperature of the sealed space at (-5)-(-15)℃.

[0081] Using the markings in the diagram as a reference, roller 5 rotates counterclockwise, applying a tension of 16 N / m to the material between rollers 5-11; roller 6 rotates clockwise, applying a tension of 65 N / m between rollers 6-13; roller 7 rotates clockwise, applying a tension of 60 N / m between rollers 7-11; roller 8 rotates clockwise, applying a tension of 30 N / m between rollers 7 and 8; and roller 9 rotates clockwise, applying a tension of 60 N / m between rollers 9-15. (These tensions work together to keep the overall process taut, allowing for better processing of each step.) However, controlling the tension of rollers 6-13 used for removing PET film 1 is particularly crucial.

[0082] After the second pressure roller 13 presses the membrane material, the difference in rotation speed between it and roller 6 will generate a certain tension. By controlling the tension, the PET film 1 can be torn off without affecting the shape of the film. The effect of tension is that too much tension will affect the quality of the membrane material, while too little tension will cause wrinkles in the membrane material and will also affect the tearing effect.

[0083] Moreover, the second pressure roller 13 here is an active roller, used to work with the heating roller to control the speed and tension of the overall film material. The adhesive used is hot melt adhesive, which can be more flattened after heating and pressing. In addition, the double rollers here work with roller 6 at an angle to better tear the PET film. Therefore, the second pressure roller 13 has multiple functions.

[0084] This embodiment integrates all processes with unique equipment, performing them synchronously. It utilizes innovative adhesive strength to replace the slicing and waste winding processes between thermally conductive films, achieving continuous and highly efficient fabrication of the composite thermally conductive layer. Photographs of the continuous fabrication process are shown below. Figure 4 As shown.

[0085] Furthermore, the edges of the composite thermal conductive layer are cleanly removed, the film is flat, and there are no missing corners, residues, wrinkles, or curling. The yield rate when preparing longitudinal thermal conductors by stacking is extremely high.

[0086] It is also worth noting that if wrinkles appear in the PET film 1 after hot pressing, the graphene thermally conductive layer will be partially torn off during the adhesive removal process, damaging the graphene thermally conductive layer. Therefore, the tension between the upper feed roll 5 and the first pressure double roller 11, as well as the good coordination with the other rollers, also have a certain impact on the yield rate of production.

[0087] Comparative Example 1

[0088] The comparative example prepared the same graphene composite thermally conductive layer as in Example 1, and the process was largely the same as in Example 1, but the difference was:

[0089] The low-temperature curing epoxy film in Example 1 was replaced with a regular epoxy film. Using this film resulted in poor adhesive removal. When the scraper separated the PET film 2 from the graphene thermal conductive layer, residual adhesive that wasn't completely removed was scraped off along with the graphene thermal conductive layer. A large amount of residual adhesive remained at the junction of the scraper and the unloading platform. This caused the residual adhesive to be carried up when the next graphene thermal conductive layer was unloaded, resulting in excess adhesive remaining between the stacked graphene films and poor film-to-film bonding.

[0090] Comparative Example 2

[0091] The comparative example prepared the same graphene composite thermally conductive layer as in Example 1, and the process was largely the same as in Example 1, but the difference was:

[0092] Keeping other conditions unchanged, reduce the tension between the unwinding roll 5 and the first pressure roller 11 and the second take-up roll 9 and the second pressure roller 13 by 5-10N respectively. Insufficient tension in these two cases will cause wrinkles in the PET film 1, which will in turn damage the graphene film when the adhesive is peeled off.

[0093] Comparative Example 3

[0094] The comparative example prepared the same graphene composite thermally conductive layer as in Example 1, and the process was largely the same as in Example 1, but the difference was:

[0095] Keeping other conditions unchanged, reduce the tension of the upper take-up roll 6 to the second pressure double roller 13 by 5-10N. Insufficient tension at this time will result in poor adhesive tearing effect and excessive residual adhesive, but the rate of residual adhesive production is slower than that of the mismatched adhesive film used in Comparative Example 1 above.

[0096] Comparative Example 4

[0097] The comparative example prepared the same graphene composite thermal conductive layer as in Example 1. The process was largely the same as in Example 1, but the difference was that the top layer film PET1 was no longer applied. Instead, a scraper was used to forcibly separate the graphene thermal conductive sheet from the bottom carrier film PET2. As a result, without the top layer PET film 1, hot pressing was performed directly. Without the protection of the PET film 1, the graphene film was easily damaged, resulting in a high defect rate, low yield, and very poor overall product quality.

[0098] Based on the above embodiments and comparative examples, it is clear that the method and apparatus for preparing the composite thermal conductive layer provided by the present invention utilize the designed differences in the adhesive capabilities of the materials to create differences in the bonding force between the bottom carrier film, the top coating film, and the intermediate hot melt adhesive film. Furthermore, by utilizing the natural differences in the bonding force between the hot melt adhesive film and the graphene thermal conductive layer and the top coating film, the hot melt adhesive film in the areas not covered by the graphene thermal conductive layer can be removed relatively thoroughly and simultaneously by peeling off the top coating film during continuous preparation. This allows multiple graphene composite thermal conductive layers to separate from each other, making the preparation process highly efficient and simple, greatly improving production efficiency and edge removal quality. This is beneficial for the mass production of composite thermal conductive layers or further mass production of graphene longitudinal thermal conductors.

[0099] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene composite heat conducting layer, characterized in that, The application relates to a preparation method of a graphene composite heat-conducting layer. The application comprises the following steps: providing a composite bottom film, wherein the composite bottom film comprises a hot melt adhesive layer and a bottom layer carrier film, the hot melt adhesive layer has a first surface and a second surface opposite to each other, and the second surface is combined with the bottom layer carrier film; laying a graphene heat-conducting layer on the first surface and continuously covering a top layer covering film to form a combination, wherein the top layer covering film continuously covers the graphene heat-conducting layer and a vacancy area on the first surface which is not covered by the graphene heat-conducting layer; performing hot pressing on the combination to combine the layers in the combination, and the bonding strength between the graphene heat-conducting layer and the top layer covering film after hot pressing is lower than the bonding strength between the graphene heat-conducting layer and the hot melt adhesive layer, and the bonding strength between the top layer covering film and the hot melt adhesive layer in the vacancy area is higher than the bonding strength between the hot melt adhesive layer and the bottom layer carrier film; separating the top layer covering film from the combination and simultaneously taking away the hot melt adhesive layer in the vacancy area during the separation; 2. The production method according to claim 1, characterized by, separating the bottom layer carrier film from the combination to obtain a graphene composite heat-conducting layer formed by the graphene heat-conducting layer and the hot melt adhesive layer. Specifically, the application comprises the following steps: after the combination is frozen, the bottom layer carrier film is peeled off; and / or, the providing process of the composite bottom film comprises the following steps: providing a composite precursor film, wherein the composite precursor film comprises the composite bottom film and a protective film covering the first surface; 3. The preparation method according to claim 2, characterized in that, tearing off the protective film from the composite precursor film to obtain the composite bottom film.

4. The method of claim 1, wherein, The preparation process of the graphene composite heat-conducting layer is continuous. The material of the bottom layer carrier film and / or the top layer covering film is selected from any one or a combination of more than two of PET, PE, PS, PC and ABS; 5. The preparation method according to claim 1, characterized in that, and / or, the material of the hot melt adhesive layer is selected from any one or a combination of more than two of a low-temperature curing epoxy resin adhesive film, a TPU hot melt adhesive film and an EVA hot melt adhesive film.

6. The preparation method according to claim 1, characterized in that, The interface between the bottom layer carrier film and the hot melt adhesive layer further contains a separation material which reduces the adhesion between the bottom layer carrier film and the hot melt adhesive layer.

7. A method of manufacturing a graphene longitudinal heat conductor, characterized by, After the combination is hot pressed, the combination is immediately subjected to secondary roller pressing and then the top layer covering film is torn off at an angle, and when the top layer covering film is torn off at an angle, the angle between the separated top layer covering film and the combination is 30-80 DEG, and the tension of the torn-off top layer covering film is controlled to be 60-70 N / m. The application further relates to a graphene longitudinal heat-conducting body prepared by the preparation method. The application comprises the following steps:

8. A device for preparing a graphene composite heat conducting layer, characterized in that, providing a plurality of graphene composite heat-conducting layers by the preparation method in any one of claims 1-6; stacking the graphene composite heat-conducting layers in a thickness direction and combining the hot melt adhesive layers in the graphene composite heat-conducting layers with adjacent graphene heat-conducting layers, and optionally slicing or not slicing in the thickness direction to obtain the graphene longitudinal heat-conducting body. The application comprises the following modules arranged in sequence according to a process sequence: a bottom film providing module for providing a composite bottom film, wherein the composite bottom film comprises a hot melt adhesive layer and a bottom layer carrier film, the hot melt adhesive layer has a first surface and a second surface opposite to each other, and the second surface is combined with the bottom layer carrier film; a combination module for laying a graphene heat-conducting layer on the first surface and continuously covering a top layer covering film to form a combination, wherein the top layer covering film continuously covers the graphene heat-conducting layer and a vacancy area on the first surface which is not covered by the graphene heat-conducting layer; a hot-pressing module for hot-pressing the combination to bond the layers in the combination, and the bonding strength between the graphene heat-conducting layer and the top layer of film after hot-pressing is lower than the bonding strength between the graphene heat-conducting layer and the hot-melt adhesive layer, and the bonding strength between the top layer of film and the hot-melt adhesive layer in the vacant area is higher than the bonding strength between the hot-melt adhesive layer and the bottom layer of film; a film-removing module for separating the top layer of film from the combination and simultaneously taking away the hot-melt adhesive layer in the vacant area during the separation; a bottom film-removing module for separating the bottom layer of film from the combination to obtain a graphene composite heat-conducting layer formed by the graphene heat-conducting layer and the hot-melt adhesive layer.

9. The preparation device according to claim 8, characterized in that The combination module comprises a feeding assembly, a film roller and a first set of pressing rollers; the feeding assembly is used to lay the graphene heat-conducting layer on the first side of the spread composite bottom film; the first set of pressing rollers is used to gather the composite bottom film laid with the graphene heat-conducting layer and the top layer of film, and to preliminarily press and bond to form the combination; and / or, the hot-pressing module comprises a second set of pressing rollers, which comprises at least one heating roller for hot-pressing the combination.

10. The preparation device of claim 8, wherein, The bottom film-removing module comprises a refrigeration plate, a scraper, a winding roller and a receiving assembly; the refrigeration plate is used to freeze the combination, the scraper is used to separate the bottom layer of film and the hot-melt adhesive layer in the combination, the winding roller is used to continuously wind the separated bottom layer of film, and the receiving assembly is used to pick up the graphene composite heat-conducting layer separated.

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