A wave-absorbing material outer coating and a preparation method thereof

Abstract

The application discloses an absorbing material outer coating and a preparation method, relates to the field of outer coatings taking polysiloxane and fluorocarbon material as core components, and comprises the following components in proportion by weight: 35-45 parts of polysiloxane resin with a hydroxyl content of 3-5%; 15-25 parts of fluorocarbon resin with a solid content of 98%; 8-12 parts of nano carbon black with a particle size of 50-100 nm and a purity of 99%; 3-5 parts of flexible auxiliary agent; 1-2 parts of dispersing agent; 15-25 parts of solvent; and 0.5-1 part of curing agent. The compression-release cycle is that the agglomerates experience the cycle of 'extrusion crushing-dispersing uniformly-reextrusion', and the particle size gradually decreases; the spiral descending path is that the absorbing material gradually descends along a spiral track under the action of the gap between the stirring plates and its own gravity, the descending process is continuously gathered by the stirring plates, the descending speed is extremely slow, the residence time is prolonged, and the stirring can be more uniform in the limited space.

Description

Technical Field

[0001] This invention relates to the field of exterior coating technology with polysiloxane and fluorocarbon materials as core components, and specifically to a microwave absorbing material exterior coating and its preparation method. Background Technology

[0002] With the rapid development of electronic information technology, electromagnetic pollution has become the fourth largest source of environmental pollution after noise pollution, air pollution, and water pollution. As a functional material that can effectively absorb electromagnetic waves, microwave absorbing coatings have broad application prospects in fields such as military stealth, electromagnetic shielding, and building protection.

[0003] Currently, microwave absorbing coatings mainly use epoxy resin and polyurethane as film-forming materials, combined with microwave absorbing fillers such as ferrite and carbon fiber. However, existing technologies have the following prominent problems: 1. Nano-carbon black and other microwave absorbing fillers have high specific surface area and a strong tendency to agglomerate. In traditional preparation processes, they are directly added to the resin system, resulting in uneven dispersion and the formation of agglomerates. 2. There is a contradiction between "curing speed" and "coating performance" in the curing of traditional microwave absorbing coatings. High-temperature rapid curing (120-150℃) results in high internal stress, poor flexibility, and easy cracking of the coating; low-temperature slow curing (60-80℃, >2 hours) results in low production efficiency and high energy consumption. 3. Existing dispersion and stirring equipment has the problems of crude temperature control and single stirring method.

[0004] To address these issues, we provide an exterior coating for a microwave absorbing material and its preparation method. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides an external coating for microwave absorbing materials and its preparation method. Using polysiloxane and fluorocarbon materials as core components, combined with conventional auxiliary raw materials, it designs three flexibly adaptable external coatings: paint, powder coating, and cured coating. Through innovative optimization of the preparation process and design of specialized equipment, it solves the technical pain points of existing microwave absorbing external coatings, such as complex preparation, high cost, simple structure, limited application, and poor adaptability to large-scale scenarios. It achieves synergistic optimization of "material properties, preparation process, and application scenarios," while ensuring that the coating possesses excellent flexibility and microwave absorption performance. Furthermore, its reasonable structural design and wide range of applications can promote the widespread application of microwave absorbing materials in multiple industries.

[0006] To achieve the above objectives, the present invention employs a microwave absorbing material exterior coating, comprising: The following components are included in parts by weight: 35-45 parts of polysiloxane resin, viscosity 10000-50000 mPa·s, hydroxyl content 3-5%; 15-25 parts of fluorocarbon resin, molecular weight 50,000-100,000, solid content ≥98%; Nano carbon black, 8-12 parts, particle size 50-100nm, purity ≥99%; 3-5 parts of flexible additive; 1-2 parts dispersant; Solvent 15-25 parts; 0.5-1 part curing agent.

[0007] This invention also discloses a method for preparing an exterior coating of a microwave absorbing material, comprising the following steps: Step 1, Raw material pretreatment: The polysiloxane resin and fluorocarbon resin were placed in a constant temperature drying oven at 60-80℃ and dried for 1-2 hours, with the moisture content controlled to be ≤0.1%. Mix nano carbon black and dispersant, add a small amount of solvent, and stir for 5-10 minutes to prepare a pre-dispersion; The second step is mixing and dispersing: Add the pretreated polysiloxane resin and fluorocarbon resin to a dispersion and stirring device, add the remaining solvent, set the stirring speed to 800-1000 r / min, the stirring temperature to 40-50℃, and stir for 15-20 minutes to form a basic resin solution. Slowly add the pre-dispersed liquid and the softening agent, adjust the speed to 1200-1500 r / min, and continue stirring for 20-30 minutes; Step 3, viscosity adjustment and filtration: Test the viscosity of the coating and adjust it to 200-300 mPa·s (25℃); Filtered through a 100-120 mesh filter; Step 4, curing process: The filtered coating is sprayed onto the substrate surface to a thickness of 50-100μm. Place it in a curing device, set the curing temperature to 80-100℃, and the curing time to 30-60 minutes to obtain a polysiloxane-fluorocarbon microwave absorbing coating exterior coating.

[0008] This invention also discloses an apparatus for preparing an exterior coating of a microwave absorbing material, comprising: The mixing drum is a cylindrical structure with caps at both the top and bottom. The upper cap has an inlet and the lower cap has an outlet. Continuous gradual heating system, including: The internal heating chamber is located at the center of the inside of the stirring drum; External heating chamber, which is located inside the outer wall structure layer of the stirring drum; A connecting cavity is located in the bottom structural layer of the stirring tank, and the connecting cavity connects the inner heating cavity and the outer heating cavity. The electric heating rods are arranged in several units, which are evenly distributed in the outer heating chamber and the inner heating chamber. The electric heating rods are arranged along the height of the stirring drum, and the heating power increases step by step from top to bottom. Temperature sensors are located at the upper and lower ends of the external heating cavity. An isolated mixing system, including: The driving rings are provided in four pairs, which are distributed in pairs at the upper and lower ends of the mixing drum. The driving rings, which are concentrically distributed inside and outside, are fixedly connected by connecting ribs. The connecting rods are provided in multiple ways and are fixedly connected between the upper and lower corresponding drive rings. The connecting rods are evenly distributed at angles around the axis of the stirring cylinder. The mixing plate has its two ends connected to corresponding connecting rods. The upper and lower adjacent mixing plates form a figure-eight structure, with the larger openings of the figure-eight structure close to each other and the smaller openings close to each other.

[0009] As a further optimization of the above scheme, the electric heating rod is an electric heating silicon rod, the power of the electric heating rod in the outer heating cavity increases from top to bottom, and the power distribution of the electric heating rod in the inner heating cavity is synchronized with that of the outer heating cavity.

[0010] As a further optimization of the above solution, the stirring plate is rotatably mounted on the connecting rod via a rotating shaft, and a torsion spring is provided at the rotating connection. The stirring plate rotates during the compression and release of the wave-absorbing material.

[0011] As a further optimization of the above solution, the inlet of the mixing drum is located at the center of the upper cylinder cover, and the outlet is located at the center of the lower cylinder cover. After entering through the inlet, the microwave absorbing material gradually flows downward along the height direction of the mixing drum and is finally discharged from the outlet, forming a continuous processing.

[0012] As a further optimization of the above solution, the temperature sensor is connected to an external temperature control system, which adjusts the heating power of the electric heating rod according to the monitored temperature, so that the temperature inside the stirring drum increases steplessly from top to bottom along the height direction, and there is no discontinuity in the temperature change difference.

[0013] As a further optimization of the above solution, a motor is also included. The motor is installed at the upper end of the mixing drum, and the motor shaft extends into the interior of the mixing drum. The shaft is connected to the drive ring.

[0014] As a further optimization of the above scheme, there is a gap between the upper and lower adjacent stirring plates.

[0015] The microwave absorbing material coating and its preparation method of the present invention have the following beneficial effects: The present invention discloses an external coating of a microwave absorbing material and its preparation method, which involves a compression-release cycle in which the agglomerates undergo a cycle of "compression and crushing - uniform dispersion - re-compression" to gradually reduce the particle size; and a spiral descent path in which the microwave absorbing material gradually descends from the gap between the stirring plates and its own gravity in a spiral trajectory. During the descent process, the material is further gathered by the stirring plates, the descent speed is extremely slow, the residence time is extended, and more uniform stirring can be achieved in a limited space. The raw materials used in this invention are mainly conventional raw materials. The polysiloxane and fluorocarbon materials are selected from industrial-grade conventional models, without the need for special customization, which effectively controls the cost of raw materials. The preparation process is simplified and complex steps are reduced, making it suitable for large-scale production. The preparation equipment is specially optimized, with a simple structure and convenient operation, which can be adapted to small-batch production and large-scale continuous production, taking into account both practicality and economy. The preparation method of the microwave absorbing material exterior coating in this invention breaks through the technical pain points of traditional microwave absorbing coatings, such as "uneven dispersion, slow curing speed, and difficulty in balancing flexibility and microwave absorption performance". The process is simple, the steps are clear, and no complicated operation is required. The inner heating chamber and the outer heating chamber are connected by a connecting chamber, so that the temperature that is finally transferred to the inside of the stirring drum increases steplessly downward along the height direction of the stirring drum. There is no discontinuity in the temperature change difference, which can ensure that the microwave absorbing material flowing downward along the height direction of the stirring drum is gradually heated without the influence of excessive temperature difference during heating. It can be evenly dispersed and flowed, and energy consumption is reduced.

[0016] Specific embodiments of the present invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope as a result, and that the embodiments of the present invention include many changes, modifications and equivalents within the spirit and scope of the appended claims. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the equipment for preparing the outer coating of the microwave absorbing material according to the present invention; Figure 2 This is a front view of the equipment for preparing the outer coating of the microwave absorbing material according to the present invention; Figure 3 This is a three-dimensional cross-sectional view of the outer coating structure of the wave-absorbing material of the present invention; Figure 4 This is a schematic diagram of the stirring plate structure of the present invention; Figure 5 This is a schematic diagram of the rotating shaft structure of the present invention.

[0018] In the diagram: 1. Stirring drum; 2. Motor; 3. Drive ring; 4. Connecting rod; 5. Stirring plate; 6. Temperature sensor; 7. Electric heating rod; 1001. External heating chamber; 1002. Internal heating chamber; 1003. Connecting chamber; 301. Connecting rib; 101. Inlet; 8. Rotating shaft. Detailed Implementation

[0019] Please refer to the instruction manual appendix. Figure 1-5 This invention provides a technical solution: a microwave absorbing material exterior coating and its preparation method. The raw materials used in this invention are mainly conventional raw materials; industrial-grade conventional polysiloxane and fluorocarbon materials are selected, requiring no special customization and effectively controlling raw material costs. The preparation process is simplified, reducing complex steps and adapting to large-scale production. The preparation equipment is a specially optimized design, with a simple structure and convenient operation, suitable for both small-batch production and large-scale continuous production, balancing practicality and economy. The following three core embodiments, corresponding to coatings, powder coatings, and cured coatings respectively, detail their preparation processes, specialized equipment, performance parameters, and application scenarios. Raw materials not specified in each embodiment are all industrial-grade conventional raw materials, and parameters can be flexibly adjusted according to actual needs.

[0020] Example 1 Polysiloxane-fluorocarbon microwave absorbing coating (liquid) and its preparation method and special equipment: The microwave absorbing coating of this embodiment uses polysiloxane and fluorocarbon resin as the core film-forming substances, combined with conventional microwave absorbing fillers and flexible additives. The raw materials are readily available and the cost is controllable. The specific formula includes (by weight parts): 35-45 parts of polysiloxane resin, 15-25 parts of fluorocarbon resin (polytetrafluoroethylene), 8-12 parts of conventional microwave absorbing filler (nano carbon black), 3-5 parts of flexible additive (dibutyl phthalate), 1-2 parts of dispersant (polycarboxylate), 15-25 parts of solvent (xylene), and 0.5-1 parts of curing agent (dibutyltin dilaurate).

[0021] Among them, the polysiloxane resin is industrial grade, with a viscosity of 10,000-50,000 mPa·s and a hydroxyl content of 3-5%. As the core film-forming material, it enhances the flexibility and weather resistance of the coating and assists in wave absorption. Fluorocarbon resin is of industrial grade, with a molecular weight of 50,000-100,000 and a solid content of ≥98%. It is the core film-forming material, which improves the coating's corrosion resistance, self-cleaning properties, and optimizes its microwave absorption performance. Nano carbon black is of industrial grade, with a particle size of 50-100nm and a purity of ≥99%. It is the core microwave absorbing component, which absorbs electromagnetic waves through dielectric loss. Conventional raw materials are low in cost. Flexible additives enhance coating flexibility and prevent cracking; these are readily available from conventional raw materials. Dispersants ensure uniform dispersion of fillers, preventing agglomeration and guaranteeing uniform microwave absorption performance. Solvents dissolve film-forming substances, adjust coating viscosity, and facilitate application. Curing agents accelerate coating curing and improve coating adhesion; these are low-cost, made from conventional raw materials.

[0022] The preparation method of the microwave absorbing material exterior coating in this invention overcomes the technical pain points of traditional microwave absorbing coatings, such as "uneven dispersion, slow curing speed, and difficulty in balancing flexibility and microwave absorption performance." The process is simple, the steps are clear, and no complicated operations are required. The specific steps include: Step 1: Raw material pretreatment. Polysiloxane resin and fluorocarbon resin are placed in a constant temperature drying oven at 60-80℃ for 1-2 hours to remove moisture (moisture content controlled to ≤0.1%), preventing air bubbles from forming during subsequent preparation and affecting coating smoothness and microwave absorption performance. Nano carbon black and dispersant are mixed, and a small amount of xylene is added. The mixture is stirred for 5-10 minutes to prepare a pre-dispersion liquid, preventing carbon black agglomeration and ensuring uniform microwave absorption performance. This step is a creative optimization that solves the problem of uneven carbon black dispersion in conventional preparation. Step 2: Mixing and dispersing. Add the pretreated polysiloxane resin and fluorocarbon resin to a dedicated dispersion and stirring device, add the remaining xylene, set the stirring speed to 800-1000 r / min, the stirring temperature to 40-50℃, and stir for 15-20 minutes to ensure that the two resins are fully dissolved and mixed evenly to form a basic resin solution; then slowly add the pre-dispersed liquid and flexible additives, adjust the speed to 1200-1500 r / min, and continue stirring for 20-30 minutes to ensure that all components are evenly dispersed and free of obvious particulate impurities; Step 3: Viscosity adjustment and filtration. After stirring, check the viscosity of the coating. If the viscosity is too high, add a small amount of xylene to adjust it to 200-300 mPa·s (25℃). If the viscosity is too low, let it stand for 5-10 minutes to thicken naturally. Then filter it through a 100-120 mesh filter to remove impurities and undispersed particles, ensuring that the coating is fine and avoiding defects on the surface of the coating after construction. This step simplifies the conventional filtration process and takes into account both efficiency and quality. Step 4: Curing treatment. Pour the filtered coating into a dedicated spraying device and spray it onto the surface of the substrate (substrate can be metal, plastic, glass, sheet, etc., suitable for multiple scenarios). The spraying thickness is controlled at 50-100μm. After spraying, place it in a dedicated curing device, set the curing temperature to 80-100℃, and the curing time to 30-60 minutes to obtain the polysiloxane-fluorocarbon microwave absorbing coating exterior coating. This step solves the problems of slow curing speed and incomplete curing of conventional coatings by optimizing the curing temperature and time, while ensuring that the coating flexibility and microwave absorption performance are synergistically improved. It does not require high temperature and high pressure, thus reducing energy consumption.

[0023] The apparatus for preparing the outer coating of the microwave absorbing material in this invention includes: a dispersion and stirring device, a spraying device, and a curing device.

[0024] refer to Figure 1 and Figure 2 As shown, the dispersion and mixing equipment includes: a mixing drum 1, which is a cylindrical structure. Both the upper and lower ends of the mixing drum 1 are equipped with lids that can be opened and closed. A motor 2 is installed at the upper end of the mixing drum 1. An inlet 101 and an outlet 102 are respectively provided on the lids at the upper and lower ends of the mixing drum 1. The microwave absorbing material enters the interior of the mixing drum 1 through the inlet 101 and is stirred. After stirring is completed, it is discharged from the outlet 102.

[0025] In order to achieve thorough mixing of the microwave absorbing material and reduce its agglomeration, the present invention provides an isolation mixing system and a continuous gradual heating system inside the mixing cylinder 1.

[0026] refer to Figure 3 neutralization Figure 4 As shown, the continuous gradual heating system includes electric heating rods 7. An inner heating cavity 1002 is provided at the center of the stirring drum 1. An outer heating cavity 1001 is provided inside the outer wall structure layer of the stirring drum 1. A connecting cavity 1003 is provided in the bottom structure layer of the stirring drum 1, which connects the inner heating cavity 1002 and the outer heating cavity 1001. Several electric heating rods 7 are provided, and the several electric heating rods 7 are distributed at equal distances inside the outer heating cavity 1001 and the inner heating cavity 1002, and the electric heating rods 7 are distributed along the height direction of the stirring drum 1.

[0027] The microwave absorbing material enters through the inlet 101 at the top of the mixing drum 1 and gradually flows downwards along the height direction of the mixing drum 1, eventually exiting from the outlet 102. During this process, the electric heating rod 7 operates, and the heat generated by the electric heating rod 7 is transferred to the microwave absorbing material through the wall structure of the mixing drum 1, heating the microwave absorbing material. The heating power of the electric heating rod 7 increases gradually from top to bottom along the height direction of the mixing drum 1, causing the temperature inside the mixing drum 1 to gradually increase downwards along the height direction of the mixing drum 1. This also reduces the viscosity of the microwave absorbing material, making it easier to mix. Furthermore, the gradual heating ensures that the dispersant or curing agent on the surface of the microwave absorbing material disperses synchronously, avoiding the secondary agglomeration phenomenon of dispersion followed by desorption.

[0028] Furthermore, the inner heating chamber 1002 and the outer heating chamber 1001 are connected by a connecting chamber 1003, so that the temperature ultimately transferred to the inside of the stirring drum 1 increases steplessly downward along the height direction of the stirring drum 1, and there is no discontinuity in the temperature change difference. This ensures that the microwave absorbing material flowing downward along the height direction of the stirring drum 1 is gradually heated without the influence of excessive temperature difference during heating, so that it can be evenly dispersed and flowed, and energy consumption is reduced.

[0029] It should be noted that the electric heating rod 7 is an electric heating silicon rod structure, which provides stable and uniform heat during heating. It is powered by an external power source. The wires and other mechanisms connecting to the external power source are not shown in the figure. This is conventional existing technology and will not be described in detail here. Temperature sensors 6 are provided at both the upper and lower ends of the external heating cavity 1001. The temperature sensors 6 are used to monitor the extreme temperatures at two points of the external heating cavity 1001 to facilitate temperature control.

[0030] Example 2 refer to Figures 3 to 5 As shown, a stirring assembly is provided inside the stirring drum 1. The stirring assembly includes a drive ring 3, a connecting rod 4, and a stirring plate 5. There are four drive rings 3, which are distributed in pairs at the upper and lower ends of the stirring drum 1. Two drive rings 3 that are concentrically distributed inside and outside are fixedly connected by a connecting rib 301. The upper and lower corresponding drive rings 3 are fixedly connected by a connecting rod 4. There are multiple connecting rods 4, which are distributed at equal angles around the axis of the stirring drum 1. The two ends of the stirring plate 5 are respectively connected to the corresponding connecting rods 4.

[0031] A motor 2 is installed above the mixing drum 1. The rotating shaft of the motor 2 extends into the interior of the mixing drum 1. One end of the rotating shaft extending into the interior of the mixing drum 1 is fixedly connected to the upper end of the drive ring 3. When the motor 2 drives the drive ring 3 to rotate, multiple mixing plates 5 rotate simultaneously inside the mixing drum 1, so that the microwave absorbing material is stirred evenly.

[0032] Furthermore, the adjacent stirring plates 5 form a figure-eight structure, which is distributed laterally. Multiple figure-eight structures are arranged in a circular array along the axis of the stirring cylinder 1, with their heads and tails corresponding to each other. That is, the ends of the figure-eight structures with larger openings are close to each other, and the ends of the figure-eight structures with smaller openings are close to each other. When the stirring plates 5 rotate and stir inside the stirring cylinder 1, the microwave absorbing material is first stirred by multiple figure-eight structures at the same horizontal position. When the microwave absorbing material enters from the large opening and exits from the small opening of the figure-eight structure, the microwave absorbing material is compressed, which can fully squeeze and mix the microwave absorbing material. When the microwave absorbing material enters from the small opening and exits from the large opening of the figure-eight structure, the microwave absorbing material is released, which can make the agglomerates in the microwave absorbing material evenly distributed. This is repeated to form a compression-release-recompression cycle stirring mode, which can fully disperse and reduce the agglomerates in the microwave absorbing material and mix them evenly.

[0033] Furthermore, due to the gap between the adjacent stirring plates 5, when the absorbing material is stirred on the same horizontal plane, it will gradually descend due to its own gravity. At this time, the absorbing material descends gradually in a spiral trajectory and is discharged from the outlet 102. The long processing path ensures that the newly entered absorbing material does not directly descend to the bottom of the stirring drum 1 for mixing, thus ensuring that the absorbing material is gradually stirred evenly. That is, absorbing material can be continuously input into the inlet 101, and the newly entered material will not quickly enter the bottom of the stirring drum 1 and be discharged from the outlet 102, ensuring that the absorbing material discharged from the outlet 102 is mixed evenly, and continuous non-stop processing is possible.

[0034] Example 3 refer to Figure 5 As shown in the figure, as another embodiment, the present invention also proposes a method in which the stirring plate 5 is rotatably mounted on the connecting rod 4 via the rotating shaft 8. However, this method is only a concept and can be used as a direction for future research and development. A torsion spring is also provided at the rotating connection of the stirring plate 5 to ensure that the stirring plate 5 rotates within a certain range during the compression and release of the absorbing material, so as to allow the absorbing material to pass smoothly through the figure-eight structure without falling rapidly, thereby further slowing down the descent speed of the absorbing material.

Claims

1. A wave-absorbing material outer coating characterized by, include: The following components are included in parts by weight: 35-45 parts of polysiloxane resin, viscosity 10000-50000 mPa·s, hydroxyl content 3-5%; 15-25 parts of fluorocarbon resin, molecular weight 50,000-100,000, solid content ≥98%; Nano carbon black, 8-12 parts, particle size 50-100nm, purity ≥99%; 3-5 parts of flexible additive; 1-2 parts dispersant; Solvent 15-25 parts; 0.5-1 part curing agent.

2. A method for preparing an outer coating of a wave-absorbing material, characterized by: The preparation of the microwave absorbing material exterior coating according to claim 1 includes the following steps: Step 1, Raw material pretreatment: The polysiloxane resin and fluorocarbon resin were placed in a constant temperature drying oven at 60-80℃ and dried for 1-2 hours, with the moisture content controlled to be ≤0.1%. Mix nano carbon black and dispersant, add a small amount of solvent, and stir for 5-10 minutes to prepare a pre-dispersion; The second step is mixing and dispersing: Add the pretreated polysiloxane resin and fluorocarbon resin to a dispersion and stirring device, add the remaining solvent, set the stirring speed to 800-1000 r / min, the stirring temperature to 40-50℃, and stir for 15-20 minutes to form a basic resin solution. Slowly add the pre-dispersed liquid and the softening agent, adjust the speed to 1200-1500 r / min, and continue stirring for 20-30 minutes; Step 3, viscosity adjustment and filtration: Test the viscosity of the coating and adjust it to 200-300 mPa·s; Filtered through a 100-120 mesh filter; Step 4, Curing treatment: The filtered coating is sprayed onto the substrate surface to a thickness of 50-100μm. Place it in a curing device, set the curing temperature to 80-100℃, and the curing time to 30-60 minutes to obtain a polysiloxane-fluorocarbon microwave absorbing coating exterior coating.

3. A preparation device of a wave-absorbing material outer decorative coating, characterized in that: The method for preparing the microwave absorbing material exterior coating of claim 1 using the method of claim 2 further includes: The stirring drum (1) is a cylindrical structure. The upper and lower ends of the stirring drum (1) are provided with drum covers. The upper drum cover is provided with an inlet (101) and the lower drum cover is provided with an outlet (102). Continuous gradual heating system, including: An internal heating chamber (1002) is located at the center of the inside of the stirring drum (1); An external heating chamber (1001) is located inside the outer wall structure layer of the stirring drum (1); The connecting cavity (1003) is located in the bottom structural layer of the stirring cylinder (1) and connects the inner heating cavity (1002) and the outer heating cavity (1001). Electric heating rod (7), several electric heating rods (7) are provided, and several electric heating rods (7) are distributed at equal distances in the outer heating chamber (1001) and the inner heating chamber (1002). The electric heating rods (7) are arranged along the height direction of the stirring drum (1), and the heating power increases step by step from top to bottom. Temperature sensor (6) is located at the upper and lower ends of the external heating cavity (1001); An isolated mixing system, including: The driving ring (3) is provided with four driving rings (3). The four driving rings (3) are distributed in pairs at the upper and lower ends of the stirring drum (1). The driving rings (3) distributed concentrically inside and outside are fixedly connected by connecting ribs (301). Connecting rod (4), multiple connecting rods (4) are provided, and the connecting rods (4) are fixedly connected between the upper and lower corresponding drive rings (3). The connecting rods (4) are distributed at equal angles with the axis of the stirring cylinder (1) as the axis. The stirring plate (5) is connected to the corresponding connecting rod (4) at both ends. The upper and lower adjacent stirring plates (5) form a figure-eight structure. The ends with larger openings of the figure-eight structure are close to each other, and the ends with smaller openings are close to each other.

4. The preparation equipment of the outer coating of the wave-absorbing material according to claim 3, characterized in that: The electric heating rod (7) is an electric heating silicon rod. The power of the electric heating rod (7) in the outer heating cavity (1001) increases from top to bottom. The power distribution of the electric heating rod (7) in the inner heating cavity (1002) is synchronized with that in the outer heating cavity (1001).

5. The preparation equipment of the outer coating of the wave-absorbing material according to claim 3, characterized in that: The stirring plate (5) is rotatably mounted on the connecting rod (4) via the rotating shaft (8), and a torsion spring is provided at the rotating connection. The stirring plate (5) rotates during the compression and release of the wave-absorbing material.

6. The preparation equipment of the outer coating of the wave absorbing material according to claim 3, characterized in that: The inlet (101) of the mixing drum (1) is located at the center of the upper end of the drum cover, and the outlet (102) is located at the center of the lower end of the drum cover. After the absorbing material enters through the inlet (101), it gradually flows downward along the height direction of the mixing drum (1) and is finally discharged from the outlet (102), forming a continuous processing.

7. The preparation equipment of the outer coating of the wave absorbing material according to claim 3, characterized in that: The temperature sensor (6) is connected to an external temperature control system. The heating power of the electric heating rod (7) is adjusted according to the monitored temperature, so that the temperature inside the stirring drum (1) increases steplessly from top to bottom along the height direction, and there is no discontinuity in the temperature change difference.

8. The preparation equipment of the wave-absorbing material outer coating layer according to claim 3, characterized in that: It also includes a motor (2), which is installed on the upper end of the mixing drum (1). The shaft of the motor (2) extends into the inside of the mixing drum (1) and is connected to the drive ring (3).

9. The preparation equipment of the outer coating of the wave absorbing material according to claim 3, characterized in that: There is a gap between the upper and lower adjacent stirring plates (5).

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