Graphite hybridization / thermoplastic electromagnetic protection thin strip preparation device and process
Through the preparation process of graphite hybrid/thermoplastics, the problem of difficult production of high-solid content composite thin belts in traditional methods is solved, continuous production and multi-band ultra-wideband electromagnetic protection are achieved, and cost and energy consumption are reduced.
Patent Information
- Application Number
- CN202510265280.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-06
- Publication Date
- 2025-04-18
AI Technical Summary
When traditional thermoplastic films or thin strips produce high-solid content composite thin strips, the fluidity becomes poor, resulting in production difficulties and the continuous production and multi-band ultra-wideband protection requirements cannot be achieved.
The composite thin strip is prepared by mechanical crushing, low-temperature roasting, oxidation and reduction, hybridization or modification, multiple melting and mixing and continuous pultrusion.
It realizes continuous production of high-solid content composite thin strips, adapts to the requirements of multi-band or ultra-wideband electromagnetic protection, reduces production costs and energy consumption, and improves the environmental protection of the products.
Smart Images
Figure CN119840215A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a production device and process for a composite strip for electromagnetic protection, and in particular to a preparation device and process for a graphite hybrid / thermoplastic plastic electromagnetic protection thin strip. Background Art
[0002] Electromagnetic shielding is a measure used to reduce the field strength caused by certain sources in a certain area of space. In most cases, the shield can be made of metals such as copper, aluminum, and steel, but for constant and low-frequency magnetic fields, ferrite and other materials can also be used as shields. Electromagnetic noise or interference often occurs in a system or between different systems, causing system performance to deteriorate. Therefore, it is required that ① the power lines or magnetic lines of force be limited to a certain area; ② a certain area is not affected by external power lines and magnetic lines of force. When the electromagnetic wave reaches the surface of the shield, due to the discontinuity of impedance at the interface between air and metal, the incident wave is reflected. This reflection requires that the shielding material must have a certain thickness, and only requires discontinuity at the interface; b. The energy that is not reflected by the surface and enters the shield is attenuated by the shielding material during the process of forward propagation in the body. This is also called absorption; c. The remaining energy that has not been attenuated in the shield, when it is transmitted to the other surface of the material, encounters the interface of metal-air impedance discontinuity, will be reflected again, and return to the shield. This reflection may have multiple reflections at the interface between the two metals. In short, the electromagnetic attenuation of electromagnetic shielding is mainly based on the reflection and absorption of electromagnetic waves.
[0003] At present, there are two main types of electromagnetic protection films. One is to sputter or chemically plate a metal film on polyester fiber cloth, and the other is to compound electromagnetic absorbents with polymer matrix materials to form electromagnetic shielding composite films. The metal films of the former are mainly copper and nickel metal films, and the electromagnetic properties of the films are relatively simple, and the minimum thickness of the protective film is about 0.02mm. In the form of polymer-based composite films, the regulation breadth (type of absorbent composition) and depth (absorbent content) of electromagnetic protection are greatly enhanced, but its protection characteristics and adjustment range are relatively expanded, the production method is relatively more environmentally friendly, the cost is lower, and the protective film is relatively thicker. However, with the requirements of multi-band or ultra-wideband protection, the content of the absorbent will increase greatly, otherwise it will not be able to meet its performance requirements. The high solid content leads to a decrease in the fluidity of the molten fluid, which brings difficulties to the production of composite materials.
[0004] Common methods for making thermoplastic films or tapes include cast film and blow molding. However, when the solid content of the composite film or tape is high, the fluidity of the composite resin deteriorates. If the composite film is made by cast film or blow molding, its production may not be possible. If it is produced by compression molding, it cannot be produced continuously and can only produce smaller sheets. Summary of the invention
[0005] Aiming at the shortcomings of traditional thermoplastic films or thin strips in producing high-solid content composite thin strips, the present invention proposes a preparation process of graphite hybrid / thermoplastic electromagnetic protection composite thin strips.
[0006] Furthermore, the unit content of the graphite hybrid mixture is 30-85%wt of the composite thin strip, which is a mixture of graphite or graphene hybridized with one or more combinations of iron and its alloys, or nickel and its alloys, or cobalt or its alloys, or ferrite, and the thickness of the thin strip is not more than 3mm; Further described, the graphite is prepared by microcrystalline graphite, the carbon content of the microcrystalline graphite is not less than 95%, the particle size of the microcrystalline graphite is not greater than 5 μm, and the proportion of particles less than 1 μm is not less than 30%wt of the total weight of the added graphite; Furthermore, the preparation process of the graphite hybrid / thermoplastic plastic comprises the following steps: (1) Mechanical crushing: using a ball mill or crusher to further crush the microcrystalline graphite particles, and using vibration screening to obtain graphite powder that meets the particle size requirements; (2) Graphite is calcined at a low temperature of 150-300°C for 0.5-2 hours; (3) Graphite oxidation and reduction, the oxidant is sulfuric acid + potassium permanganate, and the reducing agent is iron powder; (4) hybridization or modification, drying the reduced graphite, mixing it with a soluble complex of one or more combinations of iron, nickel, or ferrite, and then filtering and drying it; (5) preparing a composite blank by melting and mixing the hybridized graphite mixture and the thermoplastic plastic pellets for multiple times to prepare composite particles, wires, rods, or plates; (6) Preparation of graphite hybrid / thermoplastic electromagnetic protection composite tape by continuous pultrusion; Furthermore, the production device for preparing graphite hybrid / thermoplastic electromagnetic protection composite thin strip by continuous pultrusion method comprises a transmission system, an extrusion wheel ①, a blank biting wheel ②, a thermal circulation system, a shoe seat ⑥, a thermal insulation pad ⑧, a release agent dripping system, a sensor (11), a mold (12), a groove block (13), and a frame (14); Furthermore, the transmission system adopts a stepper motor or a variable frequency motor + a speed changer, the transmission route is motor → speed changer → extrusion wheel ①, the transmission method adopts a pulley, or a gear, or a worm gear, or a combination thereof, the speed of the motor is controlled by a temperature sensor, and when the measured temperature is lower than the set temperature, the speed of the motor increases. The extrusion wheel ① is fixed to the frame (14) in the form of a shaft + bearing, or a shaft + bearing, and an annular groove (such asFigure 1 As shown in ). The shoe seat ⑥ is fixed to the frame (14), and the shoe seat ⑥ fits with the top of both sides of the annular groove of the extrusion wheel ①. The fitting force between the shoe seat ⑥ and both sides of the annular groove of the extrusion wheel ① is provided by mechanical or hydraulic means. The central angle of the fitting area of the shoe seat ⑥ corresponding to the arc length of the extrusion wheel ① is not greater than 180°. The fitting of the shoe seat ⑥ makes the annular groove of the extrusion wheel ① form an annular tube cavity with two ends open and a central angle of not more than 180°. A blank biting wheel ② is set at one end of the annular tube cavity, and the blank biting wheel ② is fixed to the shoe seat ⑥ in the form of a bearing or a ball. The blank biting wheel ② can rotate around its own central axis. An annular groove stopper (13) is set at the other end of the annular tube, and the annular groove stopper (13) is fixed to the shoe seat ⑥. A mold (12) is set at the tube wall of the annular tube cavity near the annular groove stopper (13), and the entrance of the mold (12) is connected to the annular tube cavity. The rotation direction of the extrusion wheel is as shown in the attached figure. Figure 1 As shown in the figure, the direction is from the blank biting wheel to the groove block (13), so that the extrusion wheel ①, the shoe seat ⑥, the blank biting wheel ②, the annular groove block (13), and the mold (12) constitute the melting cavity ⑤ of the composite blank. The composite blank is subjected to the friction and strong shearing effect between the annular groove of the extrusion wheel ① and the surface of the shoe seat, and the temperature gradually rises to a molten state. Under the friction force of the extrusion wheel ① and the winding tension F (as shown in the figure), the composite blank is subjected to the friction force of the extrusion wheel ① and the winding tension F (as shown in the figure). Figure 1 ) is gradually and continuously pulled out from the die (12) into a thin strip under the action of; Furthermore, the blank biting wheel ② is composed of a pair of cylindrical rollers of the same size with opposite rotation directions. Both cylindrical rollers are driving wheels, which are driven to rotate by a motor + speed changer. The circumference of the cylindrical roller is provided with a hole pattern corresponding to the cross-sectional shape of the blank, and a pattern is arranged on the surface of the hole pattern. The blank biting wheel ② is fixed to the shoe seat ⑥ in an embedded manner by bearings or balls, and the fitting position between the shoe seat ⑥ and the blank biting wheel ② is subjected to surface strengthening treatment.
[0007] Further, one side of the shoe seat ⑥ is fitted with the top of both sides of the annular groove of the extrusion wheel ①, and the width of the top fitting is not less than 10mm on one side. The part where the shoe seat ⑥ fits with the extrusion wheel ① is made of wear-resistant material or surface strengthening treatment. The shoe seat ⑥ is non-rigidly fixed in the radial direction of the extrusion wheel ①. The shoe seat ⑥ is provided with a mechanical or hydraulic loading device in the radial direction of the extrusion wheel, and has a certain limit of displacement adjustment capability, and its adjustment displacement is not greater than 2mm. The inner surface of the melting chamber formed by the shoe seat ⑥ is provided with discontinuous spiral protrusions to increase the shear deformation and tumbling of the material in the melting chamber, thereby forming a stronger stirring effect; Furthermore, the mold (12) is fixed to the shoe seat ⑥ by interference fit or other mechanical means, the cross-sectional shape of the sizing belt of the mold (12) is a rectangle, the height of the rectangle is not more than 3 mm, and the width is not less than 10 mm, the mold (12) is embedded with a number of sensors (11), the sensors include temperature and pressure sensors, the pressure sensor is embedded in the mold hole surface in the form of a patch, and the temperature sensor is in the form of a blind hole close to the inner surface of the mold (12), the distance between the bottom of the blind hole and the inner surface of the mold hole of the mold (12) is not more than 2 mm, the temperature sensor is a K-type thermocouple, and the pressure sensor is a diaphragm; Furthermore, the thermal circulation system comprises a shaping plate ⑩, a heat collection tube ⑦, a material heater ④, and a material bin ③. The shaping plate ⑩ is made of copper or copper alloy and is arranged in series at the outlet end of the mold (12). A groove structure is adopted between the shaping plate ⑩ and the mold (12), and a heat insulation pad ⑧ is embedded in the groove. The shaping plate ⑩ is provided with a number of mold release agent dripping ports. A heat conduction medium channel is provided in the shaping plate ⑩, and the heat conduction medium channel is connected to one end of the heat collection tube ⑦ in the form of a joint. The other end of the heat collection tube ⑦ is connected to the material heater. The material heater ④ is placed in the material bin ③. The material bin ③ is provided with a number of windows for easy material discharge, observation and discharge.
[0008] Further, the graphite hybrid / thermoplastic electromagnetic protection tape has a winding tension F (such as Figure 1 ) is 0.05-0.1 times the product of the room temperature tensile strength of the produced material and the cross-sectional area.
[0009] The advantages of the present invention are: (1) Continuous pultrusion can realize a variety of feeding methods, using composite wires, rods, plates, or even various scraps; (2) No additional heating device is required, and the heat generated by the friction between the extrusion wheel, the shoe seat and the material is used, which simplifies the design and cost of the production equipment; (3) The temperature of the material in the melting chamber can be controlled by adjusting the rotation speed of the extrusion wheel; (4) Flexible thermoplastics are used to produce composite thin strips or thin-walled tubes. The inner wall of the composite thin-walled tube is close fitting, which is convenient for transportation and storage. At the same time, it is more adaptable to the protection of cables or cables with different cross-sectional shapes and sizes. After the protected cables or cables are packaged, the two ends are sealed and then vacuumed, so that the thin-walled tube can fit closely to the protected cables or cables, which not only saves installation space, but also greatly reduces the types of product specifications; (5) Compared with the casting method or the blow molding method, since the present invention enters the mold and the water-cooled copper sleeve under compressive stress, the fluidity requirements of the molten plastic are greatly reduced, and it is more suitable for the production of thermoplastic composite materials with high solid content; (6) The present invention adopts a heat circulation system to cool the composite material after molding and preheat the blank through the system through a radiator and a heat collection pipe, thereby reducing the energy consumption of production as much as possible and achieving green and environmentally friendly production; (7) By changing the feeding form and the cross-sectional structure of the mold, the device can be used to achieve melt blending of graphite hybrid mixture and polymer plastic; (8) Discontinuous spiral protrusions are arranged at the corresponding positions of the shoe seat and the extrusion wheel groove, which can force the material entering the annular cavity to produce stronger shear deformation, and its composition is more uniform compared to extrusion.
[0010] Figures and Description Figure 1The schematic diagram of the device of the present invention is shown in the figure, wherein ① is an extrusion wheel, which is made of steel and fixed to the frame (13) in the form of shaft + bearing, or shaft + bearing shell, and an annular groove is provided on the circumference of the extrusion wheel ①; ② is a billet biting wheel, which is composed of a pair of cylindrical rollers made of wear-resistant steel of the same size and rotating in opposite directions, and the circumference of the cylindrical roller is provided with a hole pattern corresponding to the cross-sectional shape of the billet, and a pattern is provided on the surface of the hole pattern, and the billet biting wheel ② is fixed to the shoe seat ⑥ in an embedded manner by bearings or balls, and the fitting position of the shoe seat ⑥ and the billet biting wheel ② is subjected to surface strengthening treatment; ③ is a silo, which is made of structural materials , covered with heat-insulating material; ④ is a material heater, which is in the form of a plate or fin, and is connected to the heat collection pipe in the form of a joint, and the heater is made of metal; ⑤ is a melting chamber, and a plurality of sensors are arranged on the inner surface of the shoe seat of the melting chamber; ⑥ is a shoe seat, which is made of metal, and the shoe seat ⑥ is fixed to the frame (13), and the shoe seat ⑥ is fitted with the top of the two sides of the annular groove of the extrusion wheel ①, and the fitting force between the shoe seat ⑥ and the two sides of the annular groove of the extrusion wheel ① is provided by mechanical or hydraulic means, and the central angle of the fitting area of the shoe seat ⑥ corresponding to the arc length of the extrusion wheel ① is not greater than 180°, and the fitting of the shoe seat ⑥ forms the annular groove of the extrusion wheel ① into two An annular tube with an opening at one end and a central angle of not more than 180° forms a melting cavity ⑤; ⑦ is a heat collection tube, which is a metal tube; ⑧ is a heat insulation pad, which is made of thermal insulation cotton; ⑨ is a drip tube interface, the diameter of the drip hole on the inner surface of the shaping plate is not more than 1mm, the outer end of the drip hole is connected to the drip port, and the interface is connected to a pressurized lubricating oil source; ⑩ is a shaping plate, which is made of copper or copper alloy and is arranged in series at the outlet end of the mold. A groove structure is used between the shaping plate ⑩ and the mold, and the heat insulation pad is embedded in the groove. The shaping plate ⑩ is also provided with a number of release agent drip holes and a heat transfer medium channel; (11) is a sensor The sensor includes a temperature sensor and a pressure sensor. The pressure sensor is embedded in the inner surface of the mold in the form of a patch, and the temperature sensor is in close contact with the inner surface of the mold in the form of a blind hole. The distance between the bottom of the blind hole and the inner surface of the mold is not more than 2 mm. The temperature sensor is a K-type thermocouple and the pressure sensor is a diaphragm. (12) is a mold, which is fixed to the shoe seat by interference fit or other mechanical methods. The cross-sectional shape of the sizing belt of the mold (12) is a rectangle, the height of the rectangle is not more than 3 mm, and its width is not less than 10 mm. A number of sensors (11) are embedded in the mold. (13) is a frame made of metal.
[0011] Specific implementation: Example 1 A graphite hybrid rubber electromagnetic protection composite thin strip and its preparation process Devices such as Figure 1As shown, the extrusion wheel is made of steel and is fixed to the frame (13) in the form of shaft + bearing. The circumference of the extrusion wheel ① is provided with an annular groove with a semicircular cross-section shape; the billet biting wheel is composed of a pair of cylindrical rollers made of wear-resistant steel of the same size and rotating in opposite directions. The circumference of the cylindrical roller is provided with an elliptical hole. The cross section of the billet is a circular wire. A grid pattern is arranged on the surface of the elliptical hole. The billet biting wheel ② is fixed to the shoe seat ⑥ in an embedded manner by a bearing; ③ is a silo, which is made of a polymer structural material and is covered with thermal insulation cotton; ④ is a heater, which is a plate type. It is connected to the heat collection pipe in the form of a joint, and the heater is made of metal; ⑤ is a melting chamber, and a plurality of sensors are arranged on the inner surface of the shoe seat of the melting chamber; ⑥ is a shoe seat, which is made of metal; the shoe seat ⑥ is fixed to the frame (13), and the shoe seat ⑥ is fitted with the top of the two sides of the annular groove of the extrusion wheel ①; the fitting force between the shoe seat ⑥ and the two sides of the annular groove of the extrusion wheel ① is provided by a mechanical method; the central angle of the fitting area of the shoe seat ⑥ corresponding to the arc length of the extrusion wheel ① is not greater than 120°, and the fitting of the shoe seat ⑥ forms the melting chamber ⑤; ⑦ is a heat collection pipe, which is a metal pipe; ⑧ is a heat insulation pad, which is made of heat preservation cotton ⑨ is a dripping tube interface, the diameter of the dripping hole on the inner surface of the shaping plate is not more than 1mm, the outer end of the dripping hole is connected to the dripping port, and the interface is connected to the pressurized lubricating oil source; ⑩ is a shaping plate, the shaping plate ⑩ is made of copper or copper alloy, and is arranged in series at the outlet end of the mold, a groove structure is adopted between the shaping plate ⑩ and the mold, and a heat insulating pad is embedded in the groove. A number of release agent dripping holes are arranged in the shaping plate ⑩, and a heat conducting medium channel is processed; (11) is a sensor, the sensor includes a temperature and a pressure sensor, the pressure sensor is embedded in the inner surface of the mold in the form of a patch, and the temperature sensor is embedded in the inner surface of the mold in the form of a patch. The sensor is in the form of a blind hole, close to the inner surface of the mold. The distance between the bottom of the blind hole and the inner surface of the mold is no more than 2 mm. The temperature sensor is a K-type thermocouple, and the pressure sensor is a diaphragm. (12) is a mold, which is fixed to the shoe seat by interference fit or other mechanical means. The cross-sectional shape of the sizing belt of the mold (12) is a rectangle, the height of the rectangle is no more than 3 mm, and its width is no less than 10 mm. A number of sensors (11) are embedded in the mold. (13) is a groove stopper, which is made of metal and fixed to the shoe seat ⑥. (14) is a frame, which is made of metal.
[0012] The composite film preparation process comprises the following steps; 1) Mechanical crushing: ball milling for 5 hours, and the proportion of particles smaller than 1 μm measured by screening method is 30%wt; (2) calcining the crushed graphite at a low temperature of 220° C. for 1 hour, and tumbling the graphite during calcination; (3) Graphite oxidation, using sulfuric acid + potassium permanganate as the oxidant and iron powder as the reducing agent; (4) hybridization or modification, drying the reduced graphite or graphene, mixing it with an iron-soluble complex, and then filtering and drying it; (5) preparing a composite blank, melt-mixing the modified or hybridized graphene hybrid, or graphite hybrid, or a mixture of the graphene hybrid or graphite hybrid with a rubber material three times using the device to prepare a composite wire; (6) The composite wire is prepared into a graphene hybrid / thermoplastic electromagnetic protection tape using the device, and the tape has a thickness of 1-2 mm and a width of 50-100 mm.
[0013] The winding tension is 0.08 times the product of the room temperature tensile strength of the produced material and the cross-sectional area, and the release agent dripping speed is not more than 2 ml / min.
Claims
1. A process for preparing a graphite hybrid / thermoplastic electromagnetic protection composite thin strip, characterized in that: The unit content of the graphite hybrid mixture is 30-85%wt of the composite thin strip, which is a mixture of graphite or graphene hybridized with one or more combinations of iron and its alloys, or nickel and its alloys, or cobalt or its alloys, or ferrite, and the thickness of the thin strip is not more than 3mm; Further described, the graphite is prepared by microcrystalline graphite, the carbon content of the microcrystalline graphite is not less than 95%, the particle size of the microcrystalline graphite is not greater than 5 μm, and the proportion of particles less than 1 μm is not less than 30%wt of the total weight of the added graphite; Further, the preparation process of the graphite hybrid / thermoplastic plastic comprises the following steps; (1) Mechanical crushing: using a ball mill or crusher to further crush the microcrystalline graphite particles, and using vibration screening to obtain graphite powder that meets the particle size requirements; (2) Graphite is calcined at a low temperature of 150-300°C for 0.5-2 hours; (3) Graphite oxidation and reduction, the oxidant is sulfuric acid + potassium permanganate, and the reducing agent is iron powder; (4) hybridization or modification, drying the reduced graphite, mixing it with a soluble complex of one or more combinations of iron, nickel, or ferrite, and then filtering and drying it; (5) preparing a composite blank by melting and mixing the hybridized graphite mixture and the thermoplastic plastic pellets for multiple times to prepare composite particles, wires, rods, or plates; (6) Preparation of graphite hybrid / thermoplastic electromagnetic protection composite tape by continuous pultrusion; Furthermore, the production device for preparing graphite hybrid / thermoplastic electromagnetic protection composite thin strip by continuous pultrusion method includes a transmission system, an extrusion wheel ①, a blank biting wheel ②, a thermal circulation system, a shoe seat ⑥, an insulation pad ⑧, a release agent dripping system, a sensor (11), a mold (12), and a frame (13).
2. The graphite hybrid / thermoplastic electromagnetic protection composite thin strip production device according to claim 1, characterized in that: An annular groove is provided on the circumference of the extrusion wheel (as shown in FIG1 ); the shoe seat is fixed to the frame, and the shoe seat fits with the tops of both sides of the annular groove of the extrusion wheel. The fitting force between the shoe seat and both sides of the annular groove of the extrusion wheel is provided by mechanical or hydraulic means, and the central angle of the shoe seat fitting area corresponding to the arc length of the extrusion wheel ① is not greater than 180°; a billet biting wheel is provided at one end of the annular tube, and the billet biting wheel is fixed to the shoe seat in the form of a bearing or a ball, and an annular groove stopper fixed to the shoe seat is provided at the other end of the annular tube; a mold is provided at the tube wall of the melting cavity near the annular groove stopper; the billet is melted and continuously extruded into a thin strip under the action of the friction force of the extrusion wheel and the winding tension F; Furthermore, the shoe seat fits with the top of both sides of the annular groove of the extrusion wheel, and the width of the top fitting is not less than 10mm on one side. The part where the shoe seat fits with the extrusion wheel is made of wear-resistant material. The shoe seat is non-rigidly fixed in the radial direction of the extrusion wheel. The shoe seat is provided with a mechanical or hydraulic loading device in the radial direction of the extrusion wheel, and has a certain limit of displacement adjustment capability, and the adjustment displacement is not greater than 2mm. Further, the inner surface of the melting chamber shoe is partially provided with a discontinuous spiral protrusion; Furthermore, the mold is embedded with a number of sensors, including temperature and pressure sensors. The pressure sensor is embedded in the inner surface of the mold in the form of a patch, and the temperature sensor is in close contact with the inner surface of the mold in the form of a blind hole. The distance between the bottom of the blind hole and the inner surface of the mold is no more than 2 mm. The temperature sensor is a K-type thermocouple, and the pressure sensor is a diaphragm. Furthermore, the winding tension F is 0.05-0.1 times the product of the room temperature tensile strength of the produced material and the cross-sectional area.