Preparation process of graphene heat-conducting compound and application thereof in PERT floor heating pipe

Abstract

The application discloses a preparation process of graphene heat-conducting mixed material and application of the graphene heat-conducting mixed material in PERT floor heating pipes, and comprises the following steps: resin melting, batched dispersion of conventional fillers, dispersion of graphene, dispersion of antioxidants, intermittent vibration and automatic feeding. No vibration is performed in the resin melting stage, so that the base resin is uniformly melted, local temperature fluctuation caused by vibration is avoided, the integrity of resin molecular chains is ensured, a stable foundation is laid for subsequent filler dispersion, intermittent impact vibration during the addition of conventional fillers can break the filler agglomerates, enhance the interface bonding between the filler agglomerates and the molten resin, and reduce thermal resistance defects caused by uneven dispersion, and low-frequency vibration during the addition of graphene can not only avoid secondary agglomeration caused by violent vibration, but also promote the formation of a continuous heat-conducting path of graphene in the resin, so that the heat-conducting performance and the mechanical performance are synergistically optimized.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a preparation process of a graphene thermally conductive compound and its application in PERT underfloor heating pipes. Background Technology

[0002] PE-RT underfloor heating pipes have broad application prospects in the market due to their good toughness, water pressure resistance, and temperature resistance. However, their low thermal conductivity is a key factor restricting further improvement in their performance. In practical use, this leads to problems such as slow heating rate, low heat transfer efficiency, and difficulty in achieving the ideal overall room temperature. Improving the heating effect by increasing the water temperature inside the pipes easily exceeds the long-term heat resistance capacity of the pipe material, resulting in a significant shortened service life. Against this backdrop, graphene has come into the research spotlight due to its excellent properties. However, in the traditional preparation process of graphene thermal conductive masterbatch, the filler is unevenly dispersed and graphene is prone to agglomeration, resulting in low thermal conductivity of the pipe, slow room heating, and high energy consumption. In order to improve the thermal conductivity, the amount of filler is often increased, but this reduces the mechanical properties of the pipe and shortens its service life. Meanwhile, dead zones exist during the mixing process, conventional fillers do not bond tightly with the resin, and the interfacial thermal resistance is high, which further restricts the thermal conductivity. These problems make it difficult for existing underfloor heating pipes to balance thermal conductivity and mechanical properties, and thus fail to meet the market demand for high-efficiency and energy-saving heating materials. Summary of the Invention

[0003] The purpose of this invention is to solve the problems in the background art and provide a preparation process for graphene thermally conductive compound and its application in PERT underfloor heating pipes.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A preparation process for a graphene thermally conductive compound includes the following steps: S1. Resin melting: PERT resin, PE wax and EBS are mixed first, and then dispersed and fed into the mixing chamber of the mixing unit through the left feeding mechanism of the mixing unit for mixing and melting. The pressing mechanism of the mixing unit is vibration-free. S2. Conventional fillers are added in batches and dispersedly. Flake graphite is added in batches and dispersedly to the mixing chamber of the mixing unit through the right lower feeding mechanism of the mixing unit. Each batch is 2 minutes apart, and the mixture is mixed until the torque is stable. After each batch of fillers is added, the pressing mechanism of the mixing unit is intermittently impacted and vibrated for 10 seconds. S3. Graphene is dispersed and added. The graphene pretreated with PE-g-MAH is dispersed and fed into the mixing chamber of the mixing unit through the left feeding mechanism of the mixing unit. The pressing mechanism of the mixing unit vibrates at low frequency. S4. Antioxidant is added in a dispersed manner. The internal mixer is cooled down, and then the antioxidant is added in a dispersed manner through the right feeding mechanism of the internal mixer. The pressing mechanism of the internal mixer vibrates once, and the mixture is discharged after mixing. S5. Intermittent vibration: During the internal mixing process, the rotor of the internal mixing unit vibrates intermittently, which effectively disperses and avoids dead zones in material mixing. S6. Automatic feeding: The well-mixed compound is automatically conveyed to the extruder via the conveyor belt of the mixing unit for tube making.

[0005] This invention features vibration-free resin melting, ensuring uniform melting of the matrix resin and preventing localized temperature fluctuations caused by vibration from affecting the integrity of the resin molecular chains. This lays a stable foundation for subsequent filler dispersion. Intermittent impact vibration during conventional filler addition can break up filler agglomerates, enhance their interfacial bonding with the molten resin, and reduce thermal resistance defects caused by uneven dispersion. The low-frequency vibration during graphene addition not only avoids secondary agglomeration caused by severe vibration but also promotes the formation of continuous thermally conductive pathways for graphene in the resin. This solves the thermal conductivity bottleneck caused by poor graphene dispersion in traditional processes and avoids the problem of decreased material mechanical properties due to excessive graphene addition caused by insufficient dispersion. Ultimately, it achieves synergistic optimization of thermal conductivity and mechanical properties.

[0006] In addition, the batch feeding method makes the conventional filler and the matrix resin more tightly bonded, reducing the interfacial thermal resistance. The PE-g-MAH pretreatment further improves the compatibility between graphene and resin, significantly improves the thermal conductivity of the masterbatch, and avoids the decline in mechanical properties caused by excessive filler. The antioxidant is added after cooling, which can reduce the damage to its activity by high temperature and extend the service life of the masterbatch.

[0007] Pretreatment: Dry mix graphene and PE-g-MAH at a mass ratio of 10:1-5:1 and ball mill for 10-15 minutes.

[0008] This invention improves the uniformity of material mixing by dispersing the addition of materials.

[0009] Preferably, the mixing device includes a left feeding mechanism, a mixing chamber with a top opening, a pressing mechanism, an intermittent vibrating rotor, a cabinet, and a right feeding mechanism. The mixing chamber is located at the bottom of the cabinet, the pressing mechanism is located at the top of the cabinet, the two intermittent vibrating rotors are rotatably located inside the mixing chamber, the left feeding mechanism is located on the left side wall of the cabinet, and the right feeding mechanism is located on the right side wall of the cabinet.

[0010] This invention uses a left-feeding mechanism to disperse a mixture of PERT resin and PE wax into a mixing chamber, achieving uniform material distribution. A pressing mechanism seals the mixing chamber, and the mixture is melted by an intermittently vibrating rotor. Then, conventional fillers are added in batches to the mixing chamber via a right-feeding mechanism. The pressing mechanism seals the mixing chamber again, and each batch of fillers is subjected to intermittent impact vibration by the pressing mechanism, resulting in melting and mixing by the intermittently vibrating rotor. Finally, graphene pretreated with PE-g-MAH is dispersed into the mixing chamber of the mixing unit via the left-feeding mechanism. The pressing mechanism of the mixing unit vibrates at low frequency, and the mixture is melted by intermittent vibration. The rotor mixes and melts the materials, then the antioxidant is dispersed and added through the right-side feeding mechanism of the mixing unit. The pressing mechanism of the mixing unit vibrates once, and the mixing and melting are carried out by the intermittently vibrating rotor. After mixing, the material is discharged, achieving precise mixing and processing of materials. The cabinet provides a supporting frame for the entire device, and the mixing chamber, as the core mixing space, carries the mixing reaction of materials at each stage. Each component has a clear division of labor. Through coordinated control of material feeding, vibration mode and mixing environment, the quality and efficiency of graphene thermal conductive masterbatch preparation are ensured, laying the foundation for the high performance of subsequent underfloor heating pipes. The automatic feeding system realizes continuous production, reduces manual intervention and improves production stability.

[0011] Preferably, the intermittent vibration rotor includes an eccentric shaft, a rotary motor, a rotor body, an elastic support spring, a displacement-inhibiting electric push rod, a locking block, and a fixing block. The eccentric shaft is located inside the mixing chamber, and the fixing blocks are located at both ends of the eccentric shaft. One fixing block contains a rotary bearing, and the rotary motor is located between the other fixing block and the eccentric shaft. The elastic support spring is located on the upper and lower opposite side walls of the fixing block. One end of the elastic support spring is fixedly connected to the mixing chamber, and the other end is fixedly connected to the fixing block. The rotor body is sleeved and fixed on the outside of the eccentric shaft. The locking block is detachably connected to the fixing block. The push rod end of the displacement-inhibiting electric push rod is fixedly connected to the locking block, and the motor end of the displacement-inhibiting electric push rod is fixed to the mixing chamber.

[0012] When vibration is required, the present invention drives the eccentric shaft to rotate at high speed via a rotary motor. The eccentric block generates centrifugal force, and the elastic support spring causes the shaft to bounce up and down under the action of centrifugal force, thereby achieving vibration of the rotor body. When vibration is not required, the displacement suppression electric push rod drives the locking block to insert into the fixing block to fix the eccentric shaft. Thus, when the eccentric shaft rotates, the rotor body also rotates, achieving stable rotation and thus achieving intermittent vibration, avoiding dead zones in material mixing.

[0013] Preferably, the locking block includes a connecting block and insert rods. One side of the connecting block is fixedly connected to the displacement-suppressing electric push rod, and the two insert rods are fixed on the other side of the connecting block. The fixing block has a fixing groove that cooperates with the insert rods.

[0014] This invention enables or disables vibration by extending or retracting the insertion rod within the fixed groove.

[0015] Preferably, the pressing mechanism includes a pressing electric push rod and an intermittent vibration pressing plate mechanism. The intermittent vibration pressing plate mechanism is located above the mixing chamber. The push rod end of the pressing electric push rod is fixedly connected to the intermittent vibration pressing plate mechanism, and the motor end of the pressing electric push rod is fixedly connected to the cabinet.

[0016] This invention uses an electric push rod to extend and retract the intermittent vibrating pressure plate mechanism to control whether the mixing chamber is closed.

[0017] Preferably, the intermittent vibration pressure plate mechanism includes a pressure plate, a fixed plate, a compression spring, a roller, a limiting block, a drive motor, and an internally hollow housing. The housing is located at the push rod end of the electric pressure push rod, the drive motor is located at the top inner part of the housing, the fixed plate is fixed to the motor end of the drive motor, several limiting blocks are arranged in a circular array at the bottom of the fixed plate, the roller is located at the bottom of the limiting block, and a connecting rod is provided at the bottom of the roller. A through groove is opened at the bottom of the housing opposite to the connecting rod, the connecting rod passes through the through groove and is fixedly connected to the pressure plate, the compression spring is sleeved on the connecting rod, one end of the compression spring presses against the roller, and the other end presses against the housing, and the cross-section of the limiting block is trapezoidal.

[0018] This invention uses the rotation of a drive motor to rotate a fixed plate. When the limiting block passes over the roller, it compresses the roller to move downward, causing the connecting rod to move downward and the pressure plate to move downward. When the limiting block leaves the roller, the roller is rebounded by the elastic force of the compression spring, causing the pressure plate to move upward, thus realizing the up-and-down vibration of the pressure plate.

[0019] Preferably, the left feeding mechanism includes an outer tube, an inner tube, a rack, a gear, and a feeding can. The outer tube is inclined downwards and is disposed on the side wall of the cabinet. The inner tube is disposed inside the outer tube and fixed to the cabinet. The rack is disposed on the side wall of the outer tube. The gear meshes with the rack. The feeding can is disposed at the starting end of the inner tube. The gear is driven by a motor. This is prior art and will not be described in detail in this case.

[0020] This invention uses the rotation of gears to drive the reciprocating motion of racks, thereby achieving the extension and retraction of the outer tube. When material needs to be fed, it can extend to the middle of the cabinet, ensuring uniform material distribution and preventing material at the edges from remaining unreacted for a long time. When material feeding is not needed, it can retract, avoiding interference with the lifting and lowering of the pressing mechanism.

[0021] Preferably, the bottom arc-shaped array of the inner tube has several dispersing plates, and a flow-dividing channel is formed between two adjacent dispersing plates. A guide column is provided below the dispersing plate, and a guide plate is provided below the guide column. A powder outlet channel is provided between two adjacent guide plates. The flow-dividing channel realizes the diversion of the stockpiled material, so that the material is dispersed when it exits from the outlet, which facilitates the uniformity of the mixing.

[0022] The application of graphene thermally conductive masterbatch in PERT underfloor heating pipes involves preparing underfloor heating pipes using a pipe extrusion molding process.

[0023] In summary, the beneficial effects of this invention are as follows: 1. The present invention features vibration-free resin melting, ensuring uniform melting of the matrix resin and avoiding local temperature fluctuations caused by vibration that could affect the integrity of the resin molecular chains. This lays a stable foundation for subsequent filler dispersion. Intermittent impact vibration during conventional filler addition can break up filler agglomerates, enhance their interfacial bonding with the molten resin, and reduce thermal resistance defects caused by uneven dispersion. The low-frequency vibration during graphene addition can avoid secondary agglomeration caused by severe vibration and promote the formation of continuous thermal conductive paths in the resin. This solves the bottleneck of thermal conductivity caused by poor graphene dispersion in traditional processes, while avoiding the problem of decreased material mechanical properties caused by excessive graphene addition due to insufficient dispersion. Ultimately, it achieves synergistic optimization of thermal conductivity and mechanical properties. 2. When vibration is required, the present invention drives the eccentric shaft to rotate at high speed via a rotary motor. The eccentric block generates centrifugal force. Due to the presence of an elastic support spring, the shaft bounces up and down under the action of centrifugal force, thereby achieving vibration of the rotor body. When vibration is not required, the displacement suppression electric push rod drives the locking block to insert into the fixing block, thereby fixing the eccentric shaft. Thus, when the eccentric shaft rotates, the rotor body also rotates, achieving stable rotation and thus achieving intermittent vibration, avoiding dead zones in material mixing. 3. The present invention rotates the fixed plate by driving the motor to rotate. When the limiting block passes above the roller, the roller is squeezed to move downward, the connecting rod moves downward, and the pressure plate moves downward. When the limiting block leaves the roller, the roller is rebounded by the elastic force of the compression spring, causing the pressure plate to move upward, thereby realizing the up and down vibration of the pressure plate. 4. This invention uses the rotation of gears to drive the reciprocating motion of racks, thereby realizing the extension and retraction of the outer tube. When material needs to be fed, it can extend to the middle of the cabinet, ensuring uniform material distribution and preventing material at the edges from remaining unreacted for a long time. When material feeding is not needed, it can retract, avoiding affecting the lifting and lowering of the pressing mechanism. Attached Figure Description

[0024] Figure 1 This is a three-dimensional schematic diagram of the mixing apparatus of the present invention; Figure 2 This is a cross-sectional schematic diagram of the mixing apparatus of the present invention; Figure 3 For the present invention Figure 2 An enlarged view of point A; Figure 4 This is a schematic diagram of the insertion of the insertion rod into the fixing groove of the present invention; Figure 5 This is a schematic diagram of the eccentric shaft of the present invention; Figure 6 This is a schematic diagram of the intermittent vibration pressure plate mechanism of the present invention; Figure 7 This is a cross-sectional schematic diagram of the intermittent vibration pressure plate mechanism of the present invention; Figure 8 This is a three-dimensional schematic diagram of the fixing plate, roller, and compression spring of the present invention; Figure 9 This is a bottom view of the fixing plate, rollers, and compression spring of the present invention; Figure 10 This is a schematic diagram of the dispersion plate, guide column, and guide plate of the present invention; Figure 11 For the present invention Figure 2 An enlarged view of point B; 100. Internal mixing device; 1. Left feeding mechanism; 2. Internal mixing bin; 3. Pressing mechanism; 4. Intermittent vibrating rotor; 5. Cabinet; 6. Right feeding mechanism; 41. Eccentric shaft; 42. Rotary motor; 43. Rotor body; 44. Elastic support spring; 45. Displacement suppression electric push rod; 46. Clamping block; 47. Fixing block; 411. Shaft; 412. Eccentric block; 461. Connecting block; 462. Insert rod; 463. Fixing groove; 31. Pressing device 32. Electric push rod; 32. Intermittent vibration pressure plate mechanism; 321. Pressure plate; 322. Fixing plate; 323. Compression spring; 324. Roller; 325. Limiting block; 326. Drive motor; 327. Box body; 328. Connecting rod; 11. Outer tube; 12. Inner tube; 13. Rack; 14. Gear; 15. Feeding tank; 121. Dispersion plate; 122. Diversion channel; 123. Guide column; 124. Guide plate; 125. Powder outlet channel. Detailed Implementation

[0025] The following specific embodiments are merely illustrative of the present invention and are not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present invention.

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] Example 1

[0028] A preparation process for a graphene thermally conductive compound includes the following steps: S1. Resin melting: PERT resin, PE wax and EBS are mixed first, and then dispersed and fed into the mixing chamber 2 of the mixing device 100 through the left feeding mechanism 1 of the mixing device 100 for mixing and melting. The pressing mechanism of the mixing device 100 is vibration-free. S2. Conventional fillers are added in batches and dispersedly. Flake graphite is added in batches and dispersedly to the mixing chamber 2 of the mixing device 100 through the right feeding mechanism 6 of the mixing device 100. Each batch is spaced 2 minutes apart and mixed until the torque is stable. After each batch of fillers is added, the pressing mechanism 3 of the mixing device 100 is intermittently impacted and vibrated for 10 seconds. S3. Graphene is dispersed and added. Graphene pretreated with PE-g-MAH is dispersed and fed into the mixing chamber 2 of the mixing device 100 through the left feeding mechanism 1 of the mixing device 100. The pressing mechanism 3 of the mixing device 100 vibrates at low frequency to avoid structural damage. S4. Antioxidant is added in a dispersed manner. The internal mixer is cooled down, and then the antioxidant is added in a dispersed manner through the right feeding mechanism 6 of the internal mixer 100. The pressing mechanism 3 of the internal mixer 100 vibrates once, and the mixture is discharged. The antioxidant here is a mixture of antioxidant 168 and antioxidant 1010. S5. Intermittent vibration: During the mixing process, the intermittent vibration rotor 4 of the mixing unit 100 intermittently vibrates, which effectively disperses and avoids dead zones in material mixing. S6. Automatic feeding: The well-mixed compound is automatically conveyed to the extruder via the conveyor belt 51 of the mixing device 100 for tube making.

[0029] like Figures 1-2 As shown, the mixing device 100 includes a left feeding mechanism 1, a mixing chamber 2 with a top opening, a pressing mechanism 3, an intermittent vibrating rotor 4, a cabinet 5, and a right feeding mechanism 6. The mixing chamber 2 is located at the bottom of the cabinet 5, the pressing mechanism 3 is located at the top of the cabinet 5, and the two intermittent vibrating rotors 4 are rotatably located inside the mixing chamber 2. The left feeding mechanism 1 is located on the left side wall of the cabinet 5, and the right feeding mechanism 6 is located on the right side wall of the cabinet 5. The bottom of the mixing chamber 2 is a feeding port, and a conveyor belt 51 is provided at the bottom of the feeding port. A push plate is provided on the feeding port, and the push plate is pushed by a push rod mechanism. When feeding is required, the push plate opens, and the material enters the conveyor belt 51 for conveying to the extruder.

[0030] like Figures 2-3 and Figure 5As shown, the intermittent vibration rotor 4 includes an eccentric shaft 41, a rotary motor 42, a rotor body 43, an elastic support spring 44, a displacement-inhibiting electric push rod 45, a locking block 46, and a fixing block 47. The eccentric shaft 41 is located inside the mixing chamber 2. The fixing blocks 47 are located at both ends of the eccentric shaft 41. One fixing block 47 contains a rotary bearing, and the rotary motor 42 is located between the other fixing block 47 and the eccentric shaft 41. The elastic support spring 44 is located on the upper and lower opposite side walls of the fixing block 47. One end of the elastic support spring 44 is fixedly connected to the mixing chamber 2, and the other end is fixedly connected to the fixing block 47. The rotor body 43 is sleeved and fixed on the eccentric shaft 41. On the outside of the spindle 41, the locking block 46 and the fixing block 47 are detachably connected. The push rod end of the displacement-inhibiting electric push rod 45 is fixedly connected to the locking block 46. The motor end of the displacement-inhibiting electric push rod 45 is fixed on the mixing chamber 2. The eccentric shaft 41 includes a shaft body 411, and an eccentric block 412 is provided on the shaft body. The locking block 46 includes a connecting block 461 and a plug rod 462. One side of the connecting block 461 is fixedly connected to the displacement-inhibiting electric push rod 45. The two plug rods 462 are fixed on the other side of the connecting block 461. The fixing block 47 has a fixing groove 463 that cooperates with the plug rod 462.

[0031] like Figures 6-9 As shown, the pressing mechanism 3 includes a pressing electric push rod 31 and an intermittent vibration pressing plate mechanism 32. The intermittent vibration pressing plate mechanism 32 is located above the mixing chamber 2. The push rod end of the pressing electric push rod 31 is fixedly connected to the intermittent vibration pressing plate mechanism 32, and the motor end of the pressing electric push rod 31 is fixedly connected to the cabinet 5. The intermittent vibration pressing plate mechanism 32 includes a pressing plate 321, a fixing plate 322, a compression spring 323, a roller 324, a limiting block 325, a drive motor 326, and an internally hollow box 327. The box 327 is located at the push rod end of the pressing electric push rod 31, and the drive motor 326 is located in the box 327. The top of the inner part of the box is fixed to the motor end of the drive motor 326. Several limiting blocks 325 are arranged in a circular array at the bottom of the fixed plate 322. The roller 324 is located at the bottom of the limiting block 325. The bottom of the roller 324 is provided with a connecting rod 328. The bottom of the box 327 is provided with a through groove 329 at the position opposite to the connecting rod 328. The connecting rod 328 passes through the through groove 329 and is fixedly connected to the pressure plate 321. The compression spring 323 is sleeved on the connecting rod 328. One end of the compression spring 323 presses against the roller 324 and the other end presses against the box 327. The cross section of the limiting block 325 is trapezoidal.

[0032] like Figure 2As shown, the left feeding mechanism 1 includes an outer tube 11, an inner tube 12, a rack 13, a gear 14, and a feeding tank 15. The outer tube 11 is inclined downwards and installed on the side wall of the cabinet 5. The inner tube 12 is installed inside the outer tube 11 and fixed to the cabinet 5. The rack 13 is installed on the side wall of the outer tube 11. The gear 14 meshes with the rack 13. The feeding tank 15 is installed at the starting end of the inner tube 12. Both the left feeding mechanism 1 and the right feeding mechanism 6 have two feeding tanks 15. The left feeding mechanism 1 has one feeding tank for a mixture of PERT resin and PE wax and one feeding tank for graphene. The right feeding mechanism 6 has one feeding tank for conventional fillers and one feeding tank for antioxidants.

[0033] like Figure 10 As shown, the bottom arc array of the inner tube 12 has several dispersing plates 121, and a flow-dividing channel 122 is formed between two adjacent dispersing plates 121. A flow-guiding column 123 is provided below the dispersing plate 121, and a flow-guiding plate 124 is provided below the flow-guiding column 123. A powder outlet channel 125 is provided between two adjacent flow-guiding plates 124.

[0034] Bottom of the mixing chamber 2 The application of graphene thermally conductive masterbatch in PERT underfloor heating pipes involves preparing underfloor heating pipes using a pipe extrusion molding process.

[0035] The graphene thermal conductive masterbatch formulation is as follows (parts by weight): PERT Type I resin (MFR 1.0): 90 parts PE wax: 1.0 part Flake graphite (particle size 50 μm): 3.5 parts Graphene (d90=6μm): 5.0 parts EBS (dispersant): 1.4 parts Antioxidant 1010: 0.2 parts Antioxidant 168: 0.2 parts PE-g-MAH: 1.5 parts Working principle: such as Figures 1-11As shown, when the internal mixing device 100 is in use, the internal mixing chamber 2 is preheated first. Then, the mixture of PERT resin, PE wax, and EBS is fed from the feeding tank of the left feeding mechanism 1. Through the action of the dispersing plate 121, the guide column 123, and the guide plate 124, the mixture is dispersed and discharged into the internal mixing chamber 2. The gear 14 rotates, driving the rack 13 to move and retract the outer tube 11 from the cabinet. The pressing electric push rod 31 of the pressing mechanism 3 drives the intermittent vibration pressing plate mechanism 32 to move downward, thereby closing the internal mixing chamber 2. The displacement suppression electric push rod 45 drives the locking block to insert into the fixing block 47, thereby fixing the eccentric shaft 41. Thus, when the eccentric shaft 41 rotates, the rotor body 43 also rotates, thereby achieving the rotation effect. After mixing and melting, the electric push rod 31 of the pressing mechanism 3 drives the intermittent vibration pressing plate mechanism 32 to move upward, thereby opening the mixing chamber 2. The gear 14 rotates, driving the rack 13 to move, and the outer tube 11 enters the cabinet. The first batch of conventional filler flows out from the conventional filler discharge tank of the right discharge mechanism 6 and enters the mixing chamber 2 after dispersion. The gear 14 rotates, driving the rack 13 to move, and the outer tube 11 retracts from the cabinet 5. The electric push rod 31 of the pressing mechanism 3 drives the intermittent vibration pressing plate mechanism 32 to move downward, thereby closing the mixing chamber 2. The rotor body 43 rotates, and the drive motor 326 of the pressing mechanism 3 of the mixing device 100 rotates rapidly, thereby causing the fixed plate 322 to move rapidly. The high-speed rotation causes the limiting block 325 to quickly pass over and leave the roller 324, thus rapidly achieving up-and-down vibration of the pressure plate and impact vibration for 10 seconds. This breaks up filler agglomerates and enhances their interfacial bonding with the molten resin. Conventional fillers are then added in batches using the same method. PE-g-MAH pretreated graphene and antioxidants are then added to the mixing chamber 2 using the same method as the PERT resin and PE wax mixture. After adding the PE-g-MAH pretreated graphene, the drive motor 326 of the pressing mechanism 3 of the mixing device 100 rotates slowly, causing the fixed plate 322 to rotate slowly, thereby causing the limiting block 325 to slowly rotate. The material slowly passes over and away from the roller 324, causing the pressure plate to vibrate slowly up and down multiple times, achieving low-frequency vibration. After adding the antioxidant, the drive motor 326 of the pressing mechanism 3 of the mixing device 100 rotates slowly, causing the fixed plate 322 to rotate slowly and vibrate once, thus achieving thorough mixing. The well-mixed blend is automatically transported to the extruder via the conveyor belt 51 of the mixing device 100 to form graphene thermally conductive masterbatch. This solves the bottleneck of thermal conductivity caused by poor graphene dispersion in traditional processes, while avoiding the problem of decreased material mechanical properties caused by excessive addition of graphene due to insufficient dispersion. Ultimately, it achieves synergistic optimization of thermal conductivity and mechanical properties.

[0036] During the mixing process, each time new material is added, the intermittently vibrating rotor vibrates once, suppressing displacement. The electric push rod 45 drives the locking block to leave the fixed block 47. Through the high-speed rotation of the eccentric shaft 41, the eccentric block 412 generates centrifugal force. Due to the elastic support spring 44, the shaft jumps up and down under the action of centrifugal force, realizing the vibration of the rotor body 43, thereby avoiding dead zones in material mixing.

[0037] Example 2

[0038] Unlike Example 1, The graphene thermal conductive masterbatch formulation is as follows (parts by weight): PERT Type I resin (MFR 1.0): 90 parts PE wax: 0.8 parts Flake graphite (particle size 50 μm): 3.0 parts Graphene (d90=6μm): 5.5 parts EBS (dispersant): 1.3 parts Antioxidant 1010: 0.15 parts Antioxidant 168: 0.25 parts PE-g-MAH: 1.65 parts.

[0039] Example 3

[0040] Unlike Example 1, The graphene thermal conductive masterbatch formulation is as follows (parts by weight): PERT Type I resin (MFR 1.0): 90 parts PE wax: 1.2 parts Flake graphite (particle size 50 μm): 4.0 parts Graphene (d90=6μm): 4.0 parts EBS (dispersant): 0.8 parts Antioxidant 1010: 0.2 parts Antioxidant 168: 0.2 parts PE-g-MAH: 1.2 parts Graphene Thermal Conductivity PERT Underfloor Heating Pipe Thermal Conductivity Performance Test Report 1. Testing Standards Thermal conductivity: GB / T 10297-2015 "Determination of thermal conductivity of non-metallic solid materials - heat flow meter method" Thermal stability: GB / T 17391-1998 "Test Methods for Thermal Stability of Polyethylene Pipes and Fittings" Pipe performance: GB / T 28799.2-2020 "Heat-resistant polyethylene (PE-RT) piping systems for hot and cold water - Part 2: Pipes" 2. Preparation of experimental samples

[0041] 3. Thermal conductivity test data

[0042] 4. Key Data Analysis Improved thermal conductivity: The thermal conductivity of all embodiments is 3-4 times that of the traditional PERT, with embodiment 2 being the best, thanks to the high graphene content forming a continuous thermally conductive network.

[0043] Thermal stability: The addition of thermally conductive filler caused a slight decrease in OIT, but it still meets the standards for underfloor heating pipes.

[0044] hydrostatic test Sample preparation Pipe processing: The three embodiments were made into floor heating pipes of the same specifications (outer diameter 20mm, wall thickness 2.0mm).

[0045]

Claims

1. A preparation process for a graphene thermally conductive compound, characterized in that, Includes the following steps: S1. Resin melting: PERT resin, PE wax and EBS are mixed first, and then dispersed and fed into the mixing chamber (2) of the mixing device (100) through the left feeding mechanism (1) of the mixing device (100) for mixing and melting. The pressing mechanism of the mixing device (100) is vibration-free. S2. Conventional fillers are added in batches and dispersedly. Flake graphite is added in batches and dispersedly to the mixing chamber (2) of the mixing device (100) through the right feeding mechanism (6) of the mixing device (100). Each batch is spaced 2 minutes apart and mixed until the torque is stable. After each batch of fillers is added, the pressing mechanism (3) of the mixing device (100) is intermittently impacted and vibrated for 10 seconds. S3. Graphene is dispersed and added. Graphene pretreated with PE-g-MAH is dispersed and fed into the mixing chamber (2) of the mixing device (100) through the left feeding mechanism (1). The pressing mechanism (3) of the mixing device (100) vibrates at low frequency. S4. Antioxidant is added in a dispersed manner, the internal mixer is cooled down, and then the antioxidant is added in a dispersed manner through the right feeding mechanism (6) of the internal mixer (100). The pressing mechanism (3) of the internal mixer (100) vibrates once, and the mixture is discharged. S5. Intermittent vibration: During the mixing process, the intermittent vibration rotor (4) of the mixing device (100) intermittently vibrates to efficiently disperse and avoid dead zones in material mixing; S6. Automatic feeding: The well-mixed compound is automatically fed to the extruder via the conveyor belt (51) of the mixing device (100) for tube making; The formulation of the graphene thermally conductive compound in the above preparation process includes the following components in parts by weight: 85-95 parts of PERT type I resin, 0.8-1.2 parts of PE wax, 3.0-4.0 parts of flake graphite, 4.0-5.5 parts of graphene, 0.8-1.4 parts of EBS dispersant, 0.15-0.25 parts of antioxidant 1010, 0.2-0.25 parts of antioxidant 168, and 1.2-1.65 parts of PE-g-MAH.

2. The preparation process of a graphene thermally conductive compound according to claim 1, characterized in that, The mixing device (100) includes a left feeding mechanism (1), a mixing chamber (2) with a top opening, a pressing mechanism (3), an intermittent vibrating rotor (4), a cabinet (5), and a right feeding mechanism (6). The mixing chamber (2) is located at the bottom of the cabinet (5), the pressing mechanism (3) is located at the top of the cabinet (5), and the two intermittent vibrating rotors (4) are rotatably located inside the mixing chamber (2). The left feeding mechanism (1) is located on the left side wall of the cabinet (5), and the right feeding mechanism (6) is located on the right side wall of the cabinet (5).

3. The preparation process of a graphene thermally conductive compound according to claim 1, characterized in that, The intermittent vibration rotor (4) includes an eccentric shaft (41), a rotary motor (42), a rotor body (43), an elastic support spring (44), a displacement-inhibiting electric push rod (45), a locking block (46), and a fixing block (47). The eccentric shaft (41) is located inside the mixing chamber (2), and the fixing blocks (47) are located at both ends of the eccentric shaft (41). One fixing block (47) contains a rotary bearing, and the rotary motor (42) is located between the other fixing block (47) and the eccentric shaft (41). The elastic support spring (44) is located at both ends of the rotor body (43). Spring (44) is provided on the upper and lower opposite side walls of fixed block (47). One end of the elastic support spring (44) is fixedly connected to the mixing chamber (2), and the other end is fixedly connected to the fixed block (47). The rotor body (43) is sleeved and fixed on the outside of the eccentric shaft (41). The locking block (46) is detachably connected to the fixed block (47). The push rod end of the displacement-suppressing electric push rod (45) is fixedly connected to the locking block (46). The motor end of the displacement-suppressing electric push rod (45) is fixed on the mixing chamber (2).

4. The preparation process of a graphene thermally conductive compound according to claim 3, characterized in that, The eccentric shaft (41) includes a shaft body (411) on which an eccentric block (412) is provided.

5. The preparation process of a graphene thermally conductive compound according to claim 3, characterized in that, The locking block (46) includes a connecting block (461) and a plug rod (462). One side of the connecting block (461) is fixedly connected to the displacement-suppressing electric push rod (45). The two plug rods (462) are fixed on the other side of the connecting block (461). The fixing block (47) has a fixing groove (463) that cooperates with the plug rod (462).

6. The preparation process of a graphene thermally conductive compound according to claim 2, characterized in that, The pressing mechanism (3) includes a pressing electric push rod (31) and an intermittent vibration pressing plate mechanism (32). The intermittent vibration pressing plate mechanism (32) is located above the mixing chamber (2). The push rod end of the pressing electric push rod (31) is fixedly connected to the intermittent vibration pressing plate mechanism (32), and the motor end of the pressing electric push rod (31) is fixedly connected to the cabinet (5).

7. The preparation process of a graphene thermally conductive compound according to claim 6, characterized in that, The intermittent vibration pressure plate mechanism (32) includes a pressure plate (321), a fixed plate (322), a compression spring (323), a roller (324), a limiting block (325), a drive motor (326), and an internally hollow housing (327). The housing (327) is located at the push rod end of the electric pressure push rod (31). The drive motor (326) is located at the top inner part of the housing (327). The fixed plate (322) is fixed to the motor end of the drive motor (326). Several limiting blocks (325) are arranged in a circular array at the bottom of the fixed plate (322). The roller (324) is located at the bottom of the limiting block (325). The bottom of the roller (324) is provided with a connecting rod (328). The bottom of the box (327) is provided with a through groove (329) at the position opposite to the connecting rod (328). The connecting rod (328) passes through the through groove (329) and is fixedly connected to the pressure plate (321). The compression spring (323) is sleeved on the connecting rod (328). One end of the compression spring (323) presses against the roller (324), and the other end presses against the box (327). The cross section of the limiting block (325) is trapezoidal.

8. The preparation process of a graphene thermally conductive compound according to claim 2, characterized in that, The left feeding mechanism (1) includes an outer tube (11), an inner tube (12), a rack (13), a gear (14), and a feeding tank (15). The outer tube (11) is inclined downward on the side wall of the cabinet (5). The inner tube (12) is located inside the outer tube (11) and fixed on the cabinet (5). The rack (13) is located on the side wall of the outer tube (11). The gear (14) meshes with the rack (13). The feeding tank (15) is located at the starting end of the inner tube (12).

9. The preparation process of a graphene thermally conductive compound according to claim 8, characterized in that, The bottom arc array of the inner tube (12) has several dispersing plates (121), and a flow-dividing channel (122) is formed between two adjacent dispersing plates (121). A flow-guiding column (123) is provided below the dispersing plate (121), and a flow-guiding plate (124) is provided below the flow-guiding column (123). A powder outlet channel (125) is provided between two adjacent flow-guiding plates (124).

10. The application of a graphene thermally conductive compound in PERT underfloor heating pipes, characterized in that: The graphene thermally conductive compound prepared by the preparation process of the graphene thermally conductive compound according to claim 1 is used to prepare floor heating pipes by pipe extrusion molding process.

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