Graphene longitudinal heat conductor and preparation method thereof

Abstract

The invention discloses a graphene longitudinal heat conductor and a preparation method thereof, and belongs to the technical field of high-heat-conductivity materials. According to the preparation method disclosed by the invention, on the basis of a traditional stacking-cutting process, the prepared longitudinal graphene heat conductor and the polymer layer are subjected to primary stacking operation, and then secondary cutting is performed, so that the longitudinal graphene heat conductor is obtained; according to the method, secondary stacking is adopted, so that the graphene longitudinal heat conductor can obtain a vertical heat conduction structure, graphene which is easy to layer can be coated by a polymer, the tensile property of the graphene longitudinal heat conductor in each horizontal direction is enhanced, the integrity of the material is improved, and feasibility is provided for subsequent processing technology and application.

Description

Technical Field

[0001] The invention belongs to the technical field of high thermal conductivity materials, and particularly relates to a graphene longitudinal thermal conductor and a preparation method thereof. Background Art

[0002] With the rapid advancement of 5G communication technology, the widespread popularization of Internet of Things applications, and the rapid development of new energy vehicle electronic systems, modern electronic devices are undergoing unprecedented changes. These technological innovations have not only greatly improved the integration, operating speed, and power density of electronic equipment, but also brought unprecedented challenges to the heat dissipation management of equipment. According to industry statistics, due to overheating problems, the failure rate of electronic equipment is as high as 55%, which undoubtedly sounded the alarm for heat dissipation problems. Overheating will not only affect the performance stability of the equipment, but also greatly shorten its service life and even cause safety hazards. Therefore, how to effectively solve the heat dissipation problem of electronic equipment has become an important issue that needs to be overcome in the current scientific and technological field.

[0003] In this context, the development of new materials with efficient thermal conductivity is particularly important. Graphene, as a revolutionary two-dimensional material, stands out with its excellent thermal conductivity and has become a bright new star in the field of thermal management. According to research, the thermal conductivity of graphene is as high as 3000-5300 W / (m•K), which is far higher than the thermal conductivity of traditional metal fillers, such as copper, and is even 7-10 times higher. This feature makes graphene have great application potential in the field of thermal interface materials. Applying graphene to the thermal management of electronic equipment can not only significantly improve the heat dissipation efficiency of the equipment and reduce the risk of overheating, but also effectively ensure the stable operation of the equipment and extend its service life. Therefore, the research and development of graphene thermal interface materials is of great significance to promote the innovation of electronic equipment heat dissipation technology, reduce the failure rate of electronic equipment, and improve the overall performance and user experience. In the future, with the continuous maturity of graphene preparation technology and the further reduction of costs, graphene thermal interface materials are expected to be applied and promoted in a wider range of fields.

[0004] In order to obtain a material with high thermal conductivity, the Chinese patent application with publication number CN117507504A proposes a process of stacking graphene films and adhesives layer by layer, and then cutting the stacked blocks to obtain a graphene material with high longitudinal thermal conductivity. However, the graphene longitudinal heat conductor produced by this process is very easy to separate, causing the heat conductor to spread out, which seriously affects the practical application of the material. The Chinese patent with authorization number CN114148044B discloses the use of laser to punch holes in the graphene film, and the adhesive passes through the holes when stacking, thereby solving the problem of easy separation of materials. However, this process has the problem of long processing time in practical application, which seriously affects production efficiency. Therefore, a process that is both effective and efficient is needed to solve the problem of easy delamination of graphene longitudinal heat conductors. Summary of the invention

[0005] The object of the present invention is to provide a graphene longitudinal heat conductor and a preparation method thereof, so as to solve the technical problem of low production efficiency in solving the problem of easy separation of materials in the existing methods.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The invention discloses a method for preparing a graphene longitudinal heat conductor, comprising the following steps: Along the Y-axis direction in the three-dimensional coordinate system, the graphene heat-conducting layer and the polymer layer are sequentially stacked cyclically to obtain a primary stacking block; after the primary stacking block is subjected to vacuum hot pressing, a slicing process is performed along the cyclic stacking direction to obtain a primary graphene longitudinal heat conductor; The primary graphene longitudinal thermal conductor and the polymer layer are cyclically stacked in sequence along the X-axis direction in the three-dimensional coordinate system to obtain a secondary stacked block; the secondary stacked block is vacuum hot-pressed and then secondary sliced ​​along the cyclic stacking direction to obtain a graphene longitudinal thermal conductor.

[0007] Furthermore, the thickness of the primary stacked block is ≤100 mm; The thickness of the primary graphene longitudinal heat conductor is 0.27-5 mm; The graphene thermal conductive layer has a thickness of 0.05-0.3 mm and a density of 0.5-1.9 g / cm 3 .

[0008] Furthermore, the polymer layer is made of one of epoxy resin, polyurethane, silicone rubber, phenolic resin, acrylic resin or organic silica gel.

[0009] Furthermore, the process parameters of the vacuum hot pressing are: the environment is a vacuum condition, the pressure is 50-300T, and the temperature range is 50-400°C.

[0010] Furthermore, when preparing a stacked block, the thickness of the polymer layer is 0.02-0.06 mm; When preparing the secondary stacking block, the coating thickness of the polymer layer is 0.02-0.06 mm.

[0011] Furthermore, the thickness of the graphene longitudinal heat conductor is greater than 0.27 mm; The cutting speeds of the primary slicing process and the secondary slicing process are both 1-20 mm / s.

[0012] Furthermore, before the primary graphene longitudinal heat conductor and the polymer layer are sequentially cyclically stacked, the primary graphene longitudinal heat conductor is sequentially cleaned and dried.

[0013] Furthermore, after the primary stacking blocks are subjected to vacuum hot pressing, they also need to be trimmed; and after the secondary stacking blocks are subjected to vacuum hot pressing, they also need to be trimmed.

[0014] The invention also discloses a graphene longitudinal heat conductor prepared by the preparation method.

[0015] Furthermore, the tensile strength of the graphene longitudinal heat conductor in the x-axis and y-axis directions is 0.1-2 MPa.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a method for preparing a graphene longitudinal heat conductor. On the basis of a traditional stacking-cutting process, the prepared graphene longitudinal heat conductor and a polymer layer are stacked again to obtain the graphene longitudinal heat conductor. The secondary stacking adopted in the method can not only enable the graphene longitudinal heat conductor to obtain a vertical heat conducting structure, but also can coat the graphene that is easy to be layered with a polymer, thereby strengthening the tensile performance of the graphene longitudinal heat conductor in all horizontal directions, improving the integrity of the material, and providing feasibility for subsequent processing technology and application. The method is simple and easy to operate, and solves the technical problem of low production efficiency in solving the problem of easy separation of materials in the existing method.

[0017] The present invention also discloses a graphene longitudinal thermal conductor prepared by the above-mentioned preparation method. Due to the secondary stacking and cutting of the longitudinal thermal conductor, the obtained graphene longitudinal thermal conductor has a higher integrity, has a vertical thermal conductive structure, and wraps the easily delaminated graphene with a polymer, thereby reducing the risk of material separation. According to relevant experimental results, the graphene longitudinal thermal conductor has both high thermal conductivity and high overall tensile strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a stacked block of the present invention; Figure 2 It is a structural schematic diagram of the secondary stacking block of the present invention; Figure 3 This is a SEM characterization image of the graphene longitudinal thermal conductor of the present invention. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0020] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0021] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0022] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0023] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0024] The present invention provides a method for preparing a graphene longitudinal heat conductor, comprising the following steps: Step 1: Figure 1 As shown, along the Y-axis direction in the three-dimensional coordinate system, the graphene thermal conductive layer and the polymer layer are cyclically stacked in sequence using a fully automatic composite stacking machine to obtain a primary stacking block; Step 2: vacuum hot pressing the stacked blocks by a vacuum hot press; Step 3: Use a single-wire cutting machine to trim the edges of the stacked blocks after vacuum hot pressing to the required size to keep the size of the overall material consistent; Step 4: Adjust the placement direction of the material so that the multi-wire saw slices the entire material along the stacking direction to obtain a primary graphene longitudinal heat conductor of the required thickness; Step 5: Clean, peel and dry the primary graphene longitudinal heat conductor by using a separation and cleaning composite integrated machine; Step 6: Figure 2 As shown, along the X-axis direction in the three-dimensional coordinate system, the primary graphene longitudinal heat conductor and the polymer layer are cyclically stacked in sequence by using a fully automatic composite stacking machine to obtain a secondary stacking block; Step 7: The secondary stacked block is subjected to vacuum hot pressing by a vacuum hot pressing machine; Step 8: Trim the vacuum hot-pressed secondary stacked blocks according to corresponding sizes using a single-wire cutting machine to obtain block materials of corresponding sizes; Step 9: Adjust the cutting direction of the block material and let the multi-wire cutting machine slice along the stacking direction of the secondary stacking of the block. Then use the separation and cleaning composite integrated machine to clean and peel it off, and stick PET double-sided tape one by one as a protective film to obtain the graphene longitudinal thermal conductor of the required thickness.

[0025] Preferably, the thickness of the stacked blocks is ≤100 mm.

[0026] Preferably, the graphene thermal conductive layer has a thickness of 0.05-0.3 mm and a density of 0.5-1.9 g / cm 3 .

[0027] Preferably, when preparing the primary stacking block, the coating thickness of the polymer layer is 0.02-0.06 mm; when preparing the secondary stacking block, the coating thickness of the polymer layer is 0.02-0.06 mm.

[0028] Preferably, vacuum hot pressing is performed under vacuum conditions.

[0029] Preferably, the pressure of vacuum hot pressing is 50-300T and the temperature range is 50-00℃.

[0030] Preferably, during the cutting process, the cutting fluid used is continuously filtered.

[0031] Preferably, the thickness of the primary graphene longitudinal heat conductor is 0.27-2 mm.

[0032] Preferably, the thickness of the graphene longitudinal heat conductor is greater than 0.27 mm.

[0033] Preferably, the polymer layer is generally selected from epoxy resin, polyurethane, silicone rubber, phenolic resin, acrylic resin, and organic silica gel; more preferably, epoxy resin.

[0034] Preferably, during the vacuum hot pressing process of step 2, the preferred pressure parameter range is set at 50-300T, and the temperature parameter range is set at 50-400°C. The specific process is to put the material in, first heat it to 80°C, maintain it for 20-80min, then heat it to 150°C, maintain it for 20-40min, and then hot press it, hot press it 1-3 times, the pressure is about 10-40T, and then hold the pressure for 30-80min, the holding pressure is one-fifth of the hot pressing, and the vacuum is maintained throughout the hot pressing process.

[0035] Preferably, in step 3 and step 8, the cutting speed of the single-wire saw is in the range of 1-20 mm / s.

[0036] Preferably, in step 4 and step 9, the multi-wire cutting machine preferably has a cutting thickness range greater than 0.27 mm to ensure mechanical strength and prevent it from cracking or interlayer separation. The multi-wire cutting machine used has a cutting fluid filtering function to prevent material debris generated during the cutting process from affecting subsequent cutting and ensure the surface quality of the material after cutting.

[0037] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0038] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0039] Example 1 A method for preparing a graphene longitudinal heat conductor comprises the following steps: Along the Y-axis direction, a fully automatic composite lamination machine is used to stack the laminated sheets with a thickness of 0.05 mm and a density of 1.8 g / cm 3 The graphene thermal conductive layer and the silicone resin are cyclically stacked in sequence to obtain a primary stacking block; the coating thickness of the thermal conductive polymer glue is 0.03 mm, and the thickness of the primary stacking block is 9 cm; The stacked blocks were placed in a vacuum hot press, first heated to 80°C, maintained for 40 minutes, then heated to 150°C, maintained for 35 minutes, and then vacuumed and hot pressed. The hot pressed was repeated twice at a pressure of 25t, and then maintained for 65 minutes. The pressure was one fifth of the hot pressed pressure, and the stacked blocks after vacuum hot pressing were obtained. The thickness of the stacked blocks after vacuum hot pressing was 7.3 cm. Use a single-wire cutting machine to trim the edges of the stacked blocks after vacuum hot pressing to the required size at a cutting speed of 5.5 mm / s; Adjust the placement direction of the material so that the multi-wire saw slices the entire material along the stacking direction to obtain a 0.3 mm primary graphene longitudinal heat conductor; The primary graphene longitudinal heat conductor is cleaned, peeled off and dried by a separation and cleaning composite integrated machine; Along the X-axis direction, the primary graphene longitudinal thermal conductor and the thermal conductive polymer glue are cyclically stacked in sequence using a fully automatic composite stacking machine, with the polymer glue coating thickness of 0.03 mm to obtain a secondary stacking block with a thickness of 10 cm; The secondary stacked block was placed in a vacuum hot press, first heated to 70°C, maintained for 40 minutes, then heated to 160°C, maintained for 35 minutes, and then vacuumed and hot pressed, once at a pressure of 25t, and then held for 65 minutes at a holding pressure of one-fifth of the hot press, to obtain a vacuum hot-pressed secondary stacked block with a thickness of 8.4 cm; The vacuum hot-pressed secondary stacked blocks are passed through a single-wire cutting machine and trimmed according to corresponding sizes at a cutting speed of 5.5 mm / s to obtain block materials of corresponding sizes; Adjust the cutting direction of the block material, and let the multi-wire cutting machine slice the block into 0.3mm thick slices along the stacking direction of the secondary stacking of the block. Then use the separation and cleaning composite integrated machine to clean and peel it off, and stick PET double-sided tape on it one by one as a protective film to obtain a graphene longitudinal thermal conductor of the required thickness.

[0040] After testing, the overall thermal conductivity of the graphene longitudinal thermal conductor prepared in Example 1 is 574.6 W / mK; the cutting direction of the secondary stacked graphene thermal conductor is considered to be the horizontal direction, the secondary stacking direction is the x-axis, and the primary stacking direction is the y-axis; the tensile strength on the x-axis is 0.6 MPa, and the tensile strength on the y-axis is 0.25 MPa.

[0041] Example 2 A method for preparing a graphene longitudinal heat conductor comprises the following steps: Along the Y-axis direction, a fully automatic composite lamination machine is used to stack the laminated sheets with a thickness of 0.05 mm and a density of 1.8 g / cm 3The graphene heat-conducting layer and the silicone resin are cyclically stacked in sequence to obtain a stacked block; the coating thickness of the thermally conductive polymer glue is 0.05 mm, and the thickness of the stacked block is 9 cm; The stacked blocks were placed in a vacuum hot press, first heated to 80°C, maintained for 40 minutes, then heated to 150°C, maintained for 35 minutes, and then vacuumed and hot pressed. The hot pressed was repeated twice at a pressure of 25t, and then maintained for 65 minutes. The pressure was one fifth of the hot pressed pressure, and the stacked blocks after vacuum hot pressing were obtained. The thickness of the stacked blocks after vacuum hot pressing was 7.3 cm. Use a single-wire cutting machine to trim the edges of the stacked blocks after vacuum hot pressing to the required size at a cutting speed of 5.5 mm / s; Adjust the placement direction of the material so that the multi-wire saw slices the entire material along the stacking direction to obtain a 0.3 mm primary graphene longitudinal heat conductor; The primary graphene longitudinal heat conductor is cleaned, peeled off and dried by a separation and cleaning composite integrated machine; Along the X-axis direction, the primary graphene longitudinal thermal conductor and the thermal conductive polymer glue are cyclically stacked in sequence using a fully automatic composite stacking machine, with the polymer glue coating thickness of 0.05 mm to obtain a secondary stacking block with a thickness of 10 cm; The secondary stacked block was placed in a vacuum hot press, first heated to 70°C, maintained for 40 minutes, then heated to 160°C, maintained for 35 minutes, and then vacuumed and hot pressed, once at a pressure of 25t, and then held for 65 minutes at a holding pressure of one-fifth of the hot press, to obtain a vacuum hot-pressed secondary stacked block with a thickness of 8.4 cm; The vacuum hot-pressed secondary stacked blocks are passed through a single-wire cutting machine and trimmed according to corresponding sizes at a cutting speed of 5.5 mm / s to obtain block materials of corresponding sizes; Adjust the cutting direction of the block material, and let the multi-wire cutting machine slice the block into 0.3mm thick slices along the stacking direction of the secondary stacking of the block. Then use the separation and cleaning composite integrated machine to clean and peel it off, and stick PET double-sided tape on it one by one as a protective film to obtain a graphene longitudinal thermal conductor of the required thickness.

[0042] After testing, the overall thermal conductivity of the graphene longitudinal thermal conductor prepared in Example 2 is 530.4 W / mK; the cutting direction of the secondary stacked graphene thermal conductor is considered to be horizontal, the secondary stacking direction is the x-axis, and the primary stacking direction is the y-axis; the tensile strength on the x-axis is 0.7 MPa, and the tensile strength on the y-axis is 0.32 MPa; it can be seen that as the content ratio of the graphene thermal conductive layer decreases and the content ratio of the polymer layer increases, the overall tensile strength of the material increases, and although the thermal conductivity conversion is slightly reduced, the thermal conductivity conversion rate is still 86%.

[0043] Example 3 A method for preparing a graphene longitudinal heat conductor comprises the following steps: Along the Y-axis direction, a fully automatic composite lamination machine is used to stack the laminated sheets with a thickness of 0.05 mm and a density of 1.8 g / cm 3 The graphene heat-conducting layer and the silicone resin are cyclically stacked in sequence to obtain a stacked block; the coating thickness of the thermally conductive polymer glue is 0.02 mm, and the thickness of the stacked block is 9 cm; The stacked blocks were placed in a vacuum hot press, first heated to 80°C, maintained for 40 minutes, then heated to 150°C, maintained for 35 minutes, and then vacuumed and hot pressed. The hot pressed was repeated twice at a pressure of 25t, and then maintained for 65 minutes. The pressure was one fifth of the hot pressed pressure, and the stacked blocks after vacuum hot pressing were obtained. The thickness of the stacked blocks after vacuum hot pressing was 7.3 cm. Use a single-wire cutting machine to trim the edges of the stacked blocks after vacuum hot pressing to the required size at a cutting speed of 5.5 mm / s; Adjust the placement direction of the material so that the multi-wire saw slices the entire material along the stacking direction to obtain a 0.3 mm primary graphene longitudinal heat conductor; The primary graphene longitudinal heat conductor is cleaned, peeled off and dried by a separation and cleaning composite integrated machine; Along the X-axis direction, the primary graphene longitudinal thermal conductor and the thermal conductive polymer glue are cyclically stacked in sequence using a fully automatic composite stacking machine, with the polymer glue coating thickness of 0.02 mm to obtain a secondary stacking block with a thickness of 10 cm; The secondary stacked block was placed in a vacuum hot press, first heated to 70°C, maintained for 40 minutes, then heated to 160°C, maintained for 35 minutes, and then vacuumed and hot pressed, once at a pressure of 25t, and then held for 65 minutes at a holding pressure of one-fifth of the hot press, to obtain a vacuum hot-pressed secondary stacked block with a thickness of 8.4 cm; The vacuum hot-pressed secondary stacked blocks are passed through a single-wire cutting machine and trimmed according to corresponding sizes at a cutting speed of 5.5 mm / s to obtain block materials of corresponding sizes; Adjust the cutting direction of the block material, and let the multi-wire cutting machine slice the block into 0.3mm thick slices along the stacking direction of the secondary stacking of the block. Then use the separation and cleaning composite integrated machine to clean and peel it off, and stick PET double-sided tape on it one by one as a protective film to obtain a graphene longitudinal thermal conductor of the required thickness.

[0044] After testing, the overall thermal conductivity of the graphene longitudinal thermal conductor prepared in Example 3 is 583.7 W / mK; the cutting direction of the secondary stacked graphene thermal conductor is considered to be horizontal, the secondary stacking direction is the x-axis, and the primary stacking direction is the y-axis; the tensile strength on the x-axis is 0.52 MPa, and the tensile strength on the y-axis is 0.2 MPa; it can be seen that as the content ratio of the graphene thermal conductive layer decreases and the content ratio of the polymer layer increases, the overall tensile strength of the material increases, and the content ratio of the polymer layer decreases, the thermal conductivity is relatively improved, and the overall tensile strength of the material decreases.

[0045] Example 4 A method for preparing a graphene longitudinal heat conductor comprises the following steps: Along the Y-axis direction, a fully automatic composite lamination machine is used to stack the sheets with a thickness of 0.03 mm and a density of 1.84 g / cm 3 The graphene thermal conductive layer and the silicone resin are cyclically stacked in sequence to obtain a primary stacking block; the coating thickness of the thermal conductive polymer glue is 0.03 mm, and the thickness of the primary stacking block is 9 cm; The stacked blocks were placed in a vacuum hot press, first heated to 80°C, maintained for 40 minutes, then heated to 150°C, maintained for 35 minutes, and then vacuumed and hot pressed. The hot pressed was repeated twice at a pressure of 25t, and then maintained for 65 minutes. The pressure was one fifth of the hot pressed pressure, and the stacked blocks after vacuum hot pressing were obtained. The thickness of the stacked blocks after vacuum hot pressing was 7.3 cm. Use a single-wire cutting machine to trim the edges of the stacked blocks after vacuum hot pressing to the required size at a cutting speed of 5.5 mm / s; Adjust the placement direction of the material so that the multi-wire saw slices the entire material along the stacking direction to obtain a 0.3 mm primary graphene longitudinal heat conductor; The primary graphene longitudinal heat conductor is cleaned, peeled off and dried by a separation and cleaning composite integrated machine; Along the X-axis direction, the primary graphene longitudinal thermal conductor and the thermal conductive polymer glue are cyclically stacked in sequence using a fully automatic composite stacking machine, with the polymer glue coating thickness of 0.03 mm to obtain a secondary stacking block with a thickness of 10 cm; The secondary stacked block was placed in a vacuum hot press, first heated to 70°C, maintained for 40 minutes, then heated to 160°C, maintained for 35 minutes, and then vacuumed and hot pressed, once at a pressure of 25t, and then held for 65 minutes at a holding pressure of one-fifth of the hot press, to obtain a vacuum hot-pressed secondary stacked block with a thickness of 8.4 cm; The vacuum hot-pressed secondary stacked blocks are passed through a single-wire cutting machine and trimmed according to corresponding sizes at a cutting speed of 5.5 mm / s to obtain block materials of corresponding sizes; Adjust the cutting direction of the block material, and let the multi-wire cutting machine slice the block into 0.3mm thick slices along the stacking direction of the secondary stacking of the block. Then use the separation and cleaning composite integrated machine to clean and peel it off, and stick PET double-sided tape on it one by one as a protective film to obtain a graphene longitudinal thermal conductor of the required thickness.

[0046] After testing, the overall thermal conductivity of the graphene longitudinal thermal conductor prepared in Example 4 is 563.8 W / mK; the cutting direction of the secondary stacked graphene thermal conductor is considered to be horizontal, the secondary stacking direction is the x-axis, and the primary stacking direction is the y-axis; the tensile strength on the x-axis is 0.69 MPa, and the tensile strength on the y-axis is 0.3 MPa; it can be seen that the density of the graphene thermal conductive layer is almost unchanged, and reducing the thickness will reduce the thermal conductivity and improve the overall tensile strength of the material.

[0047] Example 5 A method for preparing a graphene longitudinal heat conductor comprises the following steps: Along the Y-axis direction, a fully automatic composite lamination machine is used to stack the sheets with a thickness of 0.08 mm and a density of 1.72 g / cm 3 The graphene thermal conductive layer and the silicone resin are cyclically stacked in sequence to obtain a primary stacking block; the coating thickness of the thermal conductive polymer glue is 0.03 mm, and the thickness of the primary stacking block is 9 cm; The stacked blocks were placed in a vacuum hot press, first heated to 80°C, maintained for 40 minutes, then heated to 150°C, maintained for 35 minutes, and then vacuumed and hot pressed. The hot pressed was repeated twice at a pressure of 25t, and then maintained for 65 minutes. The pressure was one fifth of the hot pressed pressure, and the stacked blocks after vacuum hot pressing were obtained. The thickness of the stacked blocks after vacuum hot pressing was 7.3 cm. Use a single-wire cutting machine to trim the edges of the stacked blocks after vacuum hot pressing to the required size at a cutting speed of 5.5 mm / s; Adjust the placement direction of the material so that the multi-wire saw slices the entire material along the stacking direction to obtain a 0.3 mm primary graphene longitudinal heat conductor; The primary graphene longitudinal heat conductor is cleaned, peeled off and dried by a separation and cleaning composite integrated machine; Along the X-axis direction, the primary graphene longitudinal thermal conductor and the thermal conductive polymer glue are cyclically stacked in sequence using a fully automatic composite stacking machine, with the polymer glue coating thickness of 0.03 mm to obtain a secondary stacking block with a thickness of 10 cm; The secondary stacked block was placed in a vacuum hot press, first heated to 70°C, maintained for 40 minutes, then heated to 160°C, maintained for 35 minutes, and then vacuumed and hot pressed, once at a pressure of 25t, and then held for 65 minutes at a holding pressure of one-fifth of the hot press, to obtain a vacuum hot-pressed secondary stacked block with a thickness of 8.4 cm; The vacuum hot-pressed secondary stacked blocks are passed through a single-wire cutting machine and trimmed according to corresponding sizes at a cutting speed of 5.5 mm / s to obtain block materials of corresponding sizes; Adjust the cutting direction of the block material, and let the multi-wire cutting machine slice the block into 0.3mm thick slices along the stacking direction of the secondary stacking of the block. Then use the separation and cleaning composite integrated machine to clean and peel it off, and stick PET double-sided tape on it one by one as a protective film to obtain a graphene longitudinal thermal conductor of the required thickness.

[0048] After testing, the overall thermal conductivity of the graphene longitudinal thermal conductor prepared in Example 5 is 591.5 W / mK; the cutting direction of the secondary stacked graphene thermal conductor is considered to be horizontal, the secondary stacking direction is the x-axis, and the primary stacking direction is the y-axis; the tensile strength on the x-axis is 0.55 MPa, and the tensile strength on the y-axis is 0.12 MPa; it can be seen that the density of the graphene thermal conductive layer is almost unchanged, and increasing the thickness will increase the thermal conductivity and reduce the overall tensile strength of the material.

[0049] Example 6 A method for preparing a graphene longitudinal heat conductor comprises the following steps: Along the Y-axis direction, a fully automatic composite lamination machine is used to stack the sheets with a thickness of 0.15 mm and a density of 0.8 g / cm 3 The graphene thermal conductive layer and the silicone resin are cyclically stacked in sequence to obtain a primary stacking block; the coating thickness of the thermal conductive polymer glue is 0.03 mm, and the thickness of the primary stacking block is 9 cm; The stacked blocks were placed in a vacuum hot press, first heated to 80°C, maintained for 40 minutes, then heated to 150°C, maintained for 35 minutes, and then vacuumed and hot pressed. The hot pressed was repeated twice at a pressure of 25t, and then maintained for 65 minutes. The pressure was one fifth of the hot pressed pressure, and the stacked blocks after vacuum hot pressing were obtained. The thickness of the stacked blocks after vacuum hot pressing was 7.3 cm. Use a single-wire cutting machine to trim the edges of the stacked blocks after vacuum hot pressing to the required size at a cutting speed of 5.5 mm / s; Adjust the placement direction of the material so that the multi-wire saw slices the entire material along the stacking direction to obtain a 0.3 mm primary graphene longitudinal heat conductor; The primary graphene longitudinal heat conductor is cleaned, peeled off and dried by a separation and cleaning composite integrated machine; Along the X-axis direction, the primary graphene longitudinal thermal conductor and the thermal conductive polymer glue are cyclically stacked in sequence using a fully automatic composite stacking machine, with the polymer glue coating thickness of 0.03 mm to obtain a secondary stacking block with a thickness of 10 cm; The secondary stacked block was placed in a vacuum hot press, first heated to 70°C, maintained for 40 minutes, then heated to 160°C, maintained for 35 minutes, and then vacuumed and hot pressed, once at a pressure of 25t, and then held for 65 minutes at a holding pressure of one-fifth of the hot press, to obtain a vacuum hot-pressed secondary stacked block with a thickness of 8.4 cm; The vacuum hot-pressed secondary stacked blocks are passed through a single-wire cutting machine and trimmed according to corresponding sizes at a cutting speed of 5.5 mm / s to obtain block materials of corresponding sizes; Adjust the cutting direction of the block material, and let the multi-wire cutting machine slice the block into 0.3mm thick slices along the stacking direction of the secondary stacking of the block. Then use the separation and cleaning composite integrated machine to clean and peel it off, and stick PET double-sided tape on it one by one as a protective film to obtain a graphene longitudinal thermal conductor of the required thickness.

[0050] After testing, the overall thermal conductivity of the graphene longitudinal thermal conductor prepared in Example 6 is 496.7 W / mK; the cutting direction of the secondary stacked graphene thermal conductor is considered to be horizontal, the secondary stacking direction is the x-axis, and the primary stacking direction is the y-axis; the tensile strength on the x-axis is 0.58 MPa, and the tensile strength on the y-axis is 0.21 MPa; it can be seen that increasing the thickness of the graphene thermal conductive layer and reducing the density will greatly reduce the thermal conductivity, but the overall tensile strength of the material remains almost unchanged.

[0051] Comparative Example 1 The graphene longitudinal heat conductor disclosed in the Chinese patent application with publication number CN117507504A is taken, and its cutting thickness and that of the secondary stacked graphene longitudinal heat conductor are both 0.3 mm; the cutting direction of the graphene heat conductor is regarded as the horizontal direction, and the extension direction of the graphene heat conductive layer is set as the x-axis; the cutting direction of the secondary stacked graphene heat conductor is regarded as the horizontal direction, and the secondary stacking direction is set as the x-axis, and the primary stacking direction is set as the y-axis.

[0052] Table 1 is a comparison of the strength data of the materials of Example 1 and Comparative Example 1. From the above experimental results, it can be seen that although Comparative Example 1 has good tensile resistance in the x direction, it has almost no tensile resistance in the y direction, and although Example 1 is not as good as Comparative Example 1 in the x direction, its overall tensile resistance has been greatly improved. Therefore, the secondary stacking makes the material have good integrity, which provides possibilities for subsequent processing and practical applications.

[0053] Table 1 Strength data of materials in Example 1 and Comparative Example 1

[0054] Table 2 is a comparison of the thermal conductivity of the materials of Example 1 and Comparative Example 1. It can be seen from the above experimental results that after the secondary stacking, the thermal conductivity of Example 1 decreases slightly compared with Comparative Example 1, but still maintains a relatively high thermal conductivity level, reaching 96% of Comparative Example 1, and has a relatively high thermal conductivity conversion rate, which is beneficial to subsequent process improvement and product optimization.

[0055] Table 2 Thermal conductivity data of materials in Example 1 and Comparative Example 1

[0056] Figure 3 This is a SEM characterization image of the graphene longitudinal thermal conductor prepared in an embodiment of the present invention. It can be seen from the figure that the thermal conductor is cut twice and glued together with polymer glue to have no gaps, maintaining a certain surface flatness, thereby ensuring the high uniformity of the thermal conductor.

[0057] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a graphene longitudinal thermal conductor, characterized in that: The following steps are involved: Along the Y-axis direction in the three-dimensional coordinate system, the graphene heat-conducting layer and the polymer layer are sequentially stacked cyclically to obtain a primary stacking block; after the primary stacking block is subjected to vacuum hot pressing, a slicing process is performed along the cyclic stacking direction to obtain a primary graphene longitudinal heat conductor; The primary graphene longitudinal thermal conductor and the polymer layer are cyclically stacked in sequence along the X-axis direction in the three-dimensional coordinate system to obtain a secondary stacked block; the secondary stacked block is vacuum hot-pressed and then secondary sliced ​​along the cyclic stacking direction to obtain a graphene longitudinal thermal conductor.

2. The method for preparing a graphene longitudinal heat conductor according to claim 1, characterized in that: The thickness of the primary stacked block is ≤100 mm; The thickness of the primary graphene longitudinal heat conductor is 0.27-5 mm; The graphene thermal conductive layer has a thickness of 0.05-0.3 mm and a density of 0.5-1.9 g / cm 3 .

3. The method for preparing a graphene longitudinal heat conductor according to claim 1, characterized in that: The polymer layer is made of one of epoxy resin, polyurethane, silicone rubber, phenolic resin, acrylic resin or organic silica gel.

4. The method for preparing a graphene longitudinal heat conductor according to claim 1, characterized in that: The process parameters of the vacuum hot pressing are: the environment is a vacuum condition, the pressure is 50-300T, and the temperature range is 50-400°C.

5. The method for preparing a graphene longitudinal heat conductor according to claim 1, characterized in that: When preparing a stacked block, the thickness of the polymer layer is 0.02-0.06 mm; When preparing the secondary stacking block, the coating thickness of the polymer layer is 0.02-0.06 mm.

6. The method for preparing a graphene longitudinal heat conductor according to claim 1, characterized in that: The thickness of the graphene longitudinal heat conductor is greater than 0.27 mm; The cutting speeds of the primary slicing process and the secondary slicing process are both 1-20 mm / s.

7. The method for preparing a graphene longitudinal heat conductor according to claim 1, characterized in that: Before the primary graphene longitudinal heat conductor and the polymer layer are sequentially stacked in a cyclic manner, the primary graphene longitudinal heat conductor is sequentially cleaned and dried.

8. The method for preparing a graphene longitudinal heat conductor according to claim 1, characterized in that: After the primary stacking blocks are subjected to vacuum hot pressing, they also need to undergo edge removal processing; and after the secondary stacking blocks are subjected to vacuum hot pressing, they also need to undergo edge removal processing.

9. A graphene longitudinal heat conductor, characterized in that: The method is prepared by any one of claims 1 to 8.

10. The graphene longitudinal heat conductor according to claim 9, characterized in that: The tensile strength of the graphene longitudinal heat conductor in the x-axis and y-axis directions is 0.1-2 MPa.

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