Preparation method of carbon-based electromagnetic wave absorption rubber

Abstract

The invention discloses a preparation method of carbon-based electromagnetic wave absorbing rubber. The invention belongs to the technical field of electromagnetic wave absorbing materials. The problems that an existing carbon-based wave-absorbing material is difficult to process, prone to embrittlement and incapable of being fully combined with a base material are solved. The method comprises the following steps: weighing a carbon-based material, silicon dioxide, a cross-linking agent and rubber, and uniformly mixing to obtain a precursor; and performing hot-pressing vulcanization on the precursor to obtain the carbon-based electromagnetic wave absorbing rubber. Over-high electromagnetic parameters of the carbon-based material are adjusted through silicon dioxide, so that the carbon-based material has better electromagnetic wave absorption performance. The carbon-based material and the silicon dioxide are combined with the rubber, so that the final product has better processability and can be conveniently processed into a required shape in modes of mold forming, hot pressing and the like, and the production flexibility is improved. When the thickness of the carbon-based electromagnetic wave absorption rubber is only 2 mm, the RL of the carbon-based electromagnetic wave absorption rubber can reach-24.3 dB. Compared with pure rubber, the carbon-based electromagnetic wave absorbing rubber is obviously improved in mechanical property and heat-conducting property. The process is simple, and batch stable production can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic wave absorbing materials, and specifically relates to a method for preparing carbon-based electromagnetic wave absorbing rubber. Background Art

[0002] With the rapid development of electronic technology, especially in the fields of wireless communication, radar systems and stealth technology, the demand for electromagnetic wave absorbing materials is growing. Electromagnetic wave absorbing materials are widely used in many fields such as wireless communication equipment, radar stealth, electronic warfare protection, automobile lightning protection and electromagnetic compatibility protection. Traditional electromagnetic wave absorbing materials are mainly based on metals, magnetic materials and conductive materials, but these materials often have disadvantages such as heavy weight and poor conductivity, and cannot meet the special requirements of modern high-performance electronic equipment for materials.

[0003] In recent years, carbon-based materials have become a research hotspot for the new generation of absorbing materials due to their unique electrical conductivity, chemical stability and high mechanical properties. Graphene, carbon nanotubes and carbon black in carbon materials are widely used in the research of absorbing materials due to their excellent electrical conductivity, easy processing and good electromagnetic wave absorption performance. However, these carbon-based materials often have problems such as difficult processing, easy brittle cracking and inability to fully combine with the matrix material in practical applications. In the research of absorbing materials, the application of flexible materials has gradually become an important direction. Flexible absorbing materials can not only adapt to complex use environments, but also meet the needs of lightweight and thinness. Therefore, the research and development of flexible carbon-based absorbing materials has become an important topic in recent years. Compared with traditional metal or hard absorbing materials, flexible absorbing materials can effectively reduce the weight of equipment and provide better adaptability, especially in some fields that require flexible structures, such as soft electronics and wearable devices, which have broad application prospects.

[0004] Rubber materials have excellent flexibility, wear resistance and good electrical insulation, and the processing technology is simple and the cost is low. Combining carbon-based materials with rubber can not only give full play to the electromagnetic wave absorption characteristics of carbon-based materials, but also retain the flexibility and easy processing of rubber, thus providing a new direction for the realization of lightweight and flexible absorbing materials. Through reasonable formula design and process control, carbon-based absorbing rubber materials can have both high electromagnetic wave absorption performance and flexibility to meet the application requirements in various harsh environments. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of existing carbon-based absorbing materials being difficult to process, easy to crack and unable to fully combine with a base material, and to provide a method for preparing a carbon-based electromagnetic wave absorbing rubber.

[0006] A method for preparing carbon-based electromagnetic wave absorbing rubber is achieved by the following steps:

[0007] 1. Weigh the carbon-based material, silica, cross-linking agent and rubber, add them into the mechanical dispersion equipment in sequence, and mix them evenly to obtain the precursor;

[0008] Second, the precursor is placed in a vulcanization mold, and then placed in a flat vulcanizer for hot pressing and vulcanization to obtain a carbon-based electromagnetic wave absorbing rubber, thereby completing the preparation method.

[0009] Furthermore, the carbon-based material, silicon dioxide, cross-linking agent and rubber described in step 1 are weighed according to a mass ratio of (1-15):(0-5):(1-3):(83-97).

[0010] Furthermore, when the weighed amount of silicon dioxide in step one is 0, the carbon-based material is rGO@SiO2 and / or GO@SiO2; when the weighed amount of silicon dioxide is not 0, the carbon-based material is one or a combination of several of graphene, graphene oxide (GO), reduced graphene oxide (rGO), rGO@SiO2, GO@SiO2, carbon nanotubes, and carbon black.

[0011] Furthermore, the silicon dioxide described in step 1 is one or a combination of crystalline silicon dioxide, amorphous silicon dioxide, synthetic silicon dioxide, and nano silicon dioxide.

[0012] Furthermore, the crosslinking agent described in step one is one or a combination of aminosilane, epoxysilane, silane olefin, mercaptosilane, vinyltriethoxysilane, bis(25-pentadienyl) crosslinking agent, disulfur peroxide, sulfur, and benzoyl peroxide.

[0013] Furthermore, the rubber in step 1 is one or a combination of natural rubber, butadiene rubber, silicone rubber, nitrile rubber, styrene-butadiene rubber, and ethylene-propylene-diene rubber.

[0014] Furthermore, the mechanical dispersing equipment in step one is an open mixer or an internal mixer.

[0015] Furthermore, the parameters for hot pressing vulcanization in the flat vulcanizer in step 2 are: temperature 160-210° C., pressure 5-15 MPa, and hot pressing time 1-20 min.

[0016] Furthermore, the thickness of the carbon-based electromagnetic wave absorbing rubber obtained in step 2 is 0.1 to 5 mm.

[0017] Advantages of the present invention:

[0018] The present invention uses a simple method to adjust the excessively high electromagnetic parameters of the carbon-based material through silicon dioxide, so that the carbon-based material has better electromagnetic wave absorption performance. In addition, by combining the carbon-based material and silicon dioxide with rubber, the final product has better processability and can be conveniently processed into a desired shape by mold forming, hot pressing, etc., thereby improving production flexibility. The addition of a cross-linking agent not only enhances the compatibility of rubber and carbon-based materials, but also promotes the cross-linking between rubber molecules, improves the heat resistance, chemical stability and service life of the material, and can be used in a variety of harsh environments. The present invention provides a method for preparing an absorbing rubber with excellent performance and easy large-scale production. In addition, the absorbing rubber prepared by this method also has good mechanical flexibility and processability, and can be widely used in electromagnetic wave shielding and absorption in the fields of electronic equipment, automobiles, aircraft, etc., and has important theoretical value and application prospects.

[0019] Mechanism of the present invention:

[0020] The preparation method of the present invention is to mix carbon-based materials, silicon dioxide, cross-linking agent and rubber in a certain mass ratio, obtain a uniform precursor by mechanical dispersion equipment, and further form a final product by hot pressing vulcanization. Specifically, the carbon-based materials (such as graphene, graphene oxide, carbon nanotubes, etc.) in step one provide good electromagnetic wave absorption performance for rubber, and its surface structure and conductivity help absorb electromagnetic waves and convert them into heat energy. Silicon dioxide improves the efficiency of electromagnetic wave absorption through the synergistic effect with carbon-based materials. In addition, the addition of silicon dioxide enhances the mechanical properties and stability of the composite material. The role of the cross-linking agent is to promote the cross-linking reaction between rubber molecules, so that the material forms a three-dimensional network structure during the vulcanization process, and enhances the mechanical properties and thermal stability of the final rubber. The characteristics of the rubber itself provide good flexibility and wear resistance, so that the material has excellent processability and performance. In the hot pressing vulcanization process of step two, the good combination of the carbon-based material and the rubber matrix is ​​ensured by appropriate temperature, pressure and time control, and the final product is given excellent electromagnetic wave absorption characteristics and mechanical strength.

[0021] The present invention achieves efficient electromagnetic wave absorption and excellent mechanical properties by carefully selecting and optimizing the combination of carbon-based materials, silicon dioxide, a cross-linking agent and rubber, and a reasonable preparation process. Through the combined effect of the electromagnetic wave absorption characteristics of the carbon-based material, the dielectric properties of silicon dioxide, the cross-linking promoting effect of the cross-linking agent and the mechanical properties of the rubber, a high-performance carbon-based electromagnetic wave absorbing rubber material with wide application potential is finally formed. The method described in the present invention can make the corresponding materials evenly dispersed in the rubber. The test results show that when the thickness of the carbon-based electromagnetic wave absorbing rubber is only 2mm, its reflection loss (RL) can reach -24.3dB. Compared with pure rubber, the mechanical properties and thermal conductivity of the carbon-based electromagnetic wave absorbing rubber are also significantly improved. And because its preparation process is simple, it can be stably produced in batches, so it has more practical application significance.

[0022] The present invention is suitable for the preparation of carbon-based electromagnetic wave absorbing rubber. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a physical picture of the carbon-based electromagnetic wave absorbing rubber in the embodiment;

[0024] Figure 2 This is a scanning electron microscope image of the carbon-based electromagnetic wave absorbing rubber in the embodiment;

[0025] Figure 3 This is a graph showing the wave absorption performance of pure rubber with a thickness of 2 mm in the embodiment;

[0026] Figure 4 This is a graph showing the wave absorption performance of the carbon-based electromagnetic wave absorbing rubber at a thickness of 2 mm in the embodiment;

[0027] Figure 5 This is a comparison diagram of the tensile stress of pure rubber and carbon-based electromagnetic wave absorbing rubber in the embodiment;

[0028] Figure 6 This is a comparison diagram of the tensile strain of pure rubber and carbon-based electromagnetic wave absorbing rubber in the embodiment;

[0029] Figure 7 This is a comparison chart of the thermal conductivity of pure rubber and carbon-based electromagnetic wave absorbing rubber in the embodiment. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0031] Specific implementation method 1: This implementation method is a method for preparing a carbon-based electromagnetic wave absorbing rubber, which is implemented by the following steps:

[0032] 1. Weigh the carbon-based material, silica, cross-linking agent and rubber, add them into the mechanical dispersion equipment in sequence, and mix them evenly to obtain the precursor;

[0033] Second, the precursor is placed in a vulcanization mold, and then placed in a flat vulcanizer for hot pressing and vulcanization to obtain a carbon-based electromagnetic wave absorbing rubber, thereby completing the preparation method.

[0034] Specific embodiment 2: This embodiment is different from specific embodiment 1 in that the carbon-based material, silicon dioxide, cross-linking agent and rubber in step 1 are weighed according to a mass ratio of (1-15):(0-5):(1-3):(83-97). Other steps and parameters are the same as those in specific embodiment 1.

[0035] In this embodiment, the carbon-based material, silicon dioxide, cross-linking agent and rubber are all weighed by dry weight according to the mass ratio.

[0036] Specific implementation method 3: This implementation method is different from specific implementation method 2 in that the carbon-based material, silicon dioxide, cross-linking agent and rubber in step 1 are weighed in a mass ratio of 15:0:2:83. Other steps and parameters are the same as those in specific implementation method 2.

[0037] Specific embodiment 4: This embodiment is different from specific embodiment 1 in that when the weighed amount of silicon dioxide in step 1 is 0, the carbon-based material is rGO@SiO2 and / or GO@SiO2; when the weighed amount of silicon dioxide is not 0, the carbon-based material is one or a combination of graphene, graphene oxide (GO), reduced graphene oxide (rGO), rGO@SiO2, GO@SiO2, carbon nanotubes, and carbon black. Other steps and parameters are the same as those in specific embodiment 1.

[0038] When the carbon-based material in this embodiment is a composite material, the components are mixed in any ratio.

[0039] The rGO@SiO2 described in this embodiment is derived from a patent with application number 202411772130.7, application date 2024.12.04, and invention name “A method for preparing a lightweight reduced graphene oxide@silicon dioxide electromagnetic wave absorbing material”; the specific preparation process is as follows:

[0040] 1. Weigh graphene oxide, silicon dioxide and silane coupling agent, and then add them into a mechanical dispersion device in sequence, and then add a solvent and stir to complete a sufficient chemical cross-linking reaction to obtain a precursor;

[0041] 2. The precursor is filtered and dried, and then sintered in an atmosphere at 500-1000° C. for 6-16 hours to obtain a lightweight reduced graphene oxide @ silicon dioxide electromagnetic wave absorbing material, thereby completing the preparation method;

[0042] The graphene oxide, silicon dioxide and silane coupling agent described in step 1 are weighed in a mass ratio of (1-3):(0.5-4):(2-6);

[0043] The graphene oxide, silicon dioxide and silane coupling agent described in step 1 are weighed in a mass ratio of 2:2:6;

[0044] The graphene oxide described in step 1 is in a solution state, and its pH is 1 to 5, and the solid content is one or more of the composition of 1% to 30%;

[0045] The silicon dioxide described in step 1 is one or a combination of crystalline silicon dioxide, amorphous silicon dioxide, synthetic silicon dioxide, and nano silicon dioxide;

[0046] The silane coupling agent described in step 1 is one or a combination of aminosilane, epoxysilane, acrylic silane, nitrosilane, silane olefin, mercaptan silane, isocyanate silane, and phenyl silane;

[0047] The solvent in step 1 is water and / or anhydrous ethanol;

[0048] The drying temperature in step 2 is 40-70°C;

[0049] The atmosphere sintering in step 2: the atmosphere is argon, helium or vacuum, and the sintering heating rate is 5-10°C / min;

[0050] In step 2, the mixture is sintered at 700°C in atmosphere for 6 hours.

[0051] Specific embodiment 5: This embodiment is different from specific embodiment 1 in that the silicon dioxide described in step 1 is one or a combination of crystalline silicon dioxide, amorphous silicon dioxide, synthetic silicon dioxide, and nano silicon dioxide. Other steps and parameters are the same as those in specific embodiment 1.

[0052] The specifications of the silicon dioxide described in this embodiment are micron-level.

[0053] When the silicon dioxide in this embodiment is a composition, the components are mixed in any ratio.

[0054] Specific embodiment 6: This embodiment is different from specific embodiment 1 in that the crosslinking agent described in step 1 is one or a combination of aminosilane, epoxysilane, silane olefin, mercaptosilane, vinyl triethoxysilane, bis(2-5) crosslinking agent, disulfur peroxide, sulfur, and benzoyl peroxide. Other steps and parameters are the same as those in specific embodiment 1.

[0055] When the crosslinking agent in this embodiment is a composition, the components are mixed in any ratio.

[0056] Specific embodiment 7: This embodiment is different from specific embodiment 1 in that the rubber in step 1 is one or a combination of natural rubber, butadiene rubber, silicone rubber, nitrile rubber, styrene butadiene rubber, and EPDM rubber. Other steps and parameters are the same as those in specific embodiment 1.

[0057] When the rubber in this embodiment is a composition, the components are mixed in any ratio.

[0058] Specific embodiment 8: This embodiment is different from specific embodiment 1 in that the mechanical dispersion equipment in step 1 is an open mixer or an internal mixer. The other steps and parameters are the same as those in specific embodiment 1.

[0059] Specific embodiment 9: This embodiment is different from specific embodiment 1 in that the parameters for hot pressing vulcanization in the flat vulcanizer in step 2 are: temperature 160-210°C, pressure 5-15MPa, and hot pressing time 1-20min. Other steps and parameters are the same as those in specific embodiment 1.

[0060] Specific embodiment 10: This embodiment is different from specific embodiment 1 in that the thickness of the carbon-based electromagnetic wave absorbing rubber obtained in step 2 is 0.1-5 mm. The other steps and parameters are the same as those in specific embodiment 1.

[0061] The beneficial effects of the present invention are verified by the following examples:

[0062] Example:

[0063] A method for preparing carbon-based electromagnetic wave absorbing rubber is achieved by the following steps:

[0064] 1. Weigh the carbon-based material, silica, cross-linking agent and rubber, add them into the mechanical dispersion equipment in sequence, and mix them evenly to obtain the precursor;

[0065] Second, the precursor is placed in a vulcanization mold, and then placed in a flat vulcanizer for hot pressing and vulcanization to obtain a carbon-based electromagnetic wave absorbing rubber, thereby completing the preparation method.

[0066] As described in step 1 of this embodiment, 15 g of carbon-based material, 1.5 g of cross-linking agent, and 83.5 g of rubber were weighed.

[0067] In step 1 of this embodiment, the weighed amount of silicon dioxide is 0, and the carbon-based material is rGO@SiO2.

[0068] The crosslinking agent described in step 1 of this embodiment is a di-2-5 crosslinking agent.

[0069] The rubber described in step 1 of this embodiment is silica gel.

[0070] The mechanical dispersion equipment in step 1 of this embodiment is an open mixing mill.

[0071] The parameters for hot pressing vulcanization in the flat vulcanizer in step 2 of this embodiment are: temperature 165° C., pressure 6 MPa, and hot pressing time 3 min.

[0072] The thickness of the carbon-based electromagnetic wave absorbing rubber obtained in step 2 of this embodiment is 2 mm.

[0073] The preparation method of rGO@SiO2 described in this embodiment is recorded in the patent with application number 202411772130.7, application date 2024.12.04, and invention name "A preparation method of lightweight reduced graphene oxide @ silicon dioxide electromagnetic wave absorption material", which is implemented by the following steps:

[0074] 1. Weigh graphene oxide, silicon dioxide and silane coupling agent, and then add them into a mechanical dispersion device in sequence, and then add a solvent and stir to complete a sufficient chemical cross-linking reaction to obtain a precursor;

[0075] 2. The precursor is filtered and dried, and then sintered in an atmosphere at 700° C. for 6 hours to obtain a lightweight reduced graphene oxide @ silicon dioxide electromagnetic wave absorbing material, thereby completing the preparation method;

[0076] The equipment used includes electric heating blast drying oven and tube furnace;

[0077] The graphene oxide is 66.67 grams (dry weight 2 grams), the solid content is 3%, and the pH value is 1.

[0078] The silicon dioxide is 2g of synthetic silicon dioxide, and the powder size is nanometer scale;

[0079] The silane coupling agent is 6g of silane olefin (Si69) type silane coupling agent;

[0080] The solvent is a mixture of water and anhydrous ethanol; the volume ratio of water to anhydrous ethanol is 3:1; the amount of solvent added is until the solvent liquid level can completely disperse the raw materials in the equipment;

[0081] The drying temperature is 60°C;

[0082] The atmosphere sintering: the atmosphere is vacuum, and the sintering heating rate is 10°C / min.

[0083] The carbon-based electromagnetic wave absorbing rubber prepared in this embodiment is as follows: Figure 1 As shown, black uniform sheet rubber can be seen, the rubber surface has no defects, the overall color is uniform, and the edges are neat.

[0084] Its scanning electron microscope image, such as Figure 2As shown, it can be seen that the flake rGO@SiO2 is evenly dispersed in the rubber without any agglomeration.

[0085] Pure rubber materials are used for comparison, such as Figure 3 As shown, the 2 mm thick pure rubber material has basically no wave absorbing performance as a whole; after being prepared into a carbon-based electromagnetic wave absorbing rubber by the method described in this embodiment, as shown in FIG. Figure 4 As shown, the material exhibits excellent wave absorbing performance. When the thickness of the carbon-based electromagnetic wave absorbing rubber is only 2mm, its reflection loss (RL) can reach -24.3dB.

[0086] Tensile stress Figure 5 As shown, after the carbon-based electromagnetic wave absorbing rubber is prepared by the method described in this embodiment, as shown in Figure 5 As shown, compared with the lower tensile stress of pure rubber, the tensile stress of carbon-based electromagnetic wave absorbing rubber increases from 284KPa to 1359KPa.

[0087] Tensile strain Figure 6 As shown, after the carbon-based electromagnetic wave absorbing rubber is prepared by the method described in this embodiment, as shown in Figure 6 As shown, compared with the lower tensile strain of pure rubber, the tensile strain of the carbon-based electromagnetic wave absorbing rubber increased from 102% to 140.5%.

[0088] Thermal conductivity Figure 7 As shown, after the carbon-based electromagnetic wave absorbing rubber is prepared by the method described in this embodiment, as shown in Figure 7 As shown, compared with the lower thermal conductivity of pure rubber, the thermal conductivity of the carbon-based electromagnetic wave absorbing rubber increases from 0.186 W / (m·K) to 0.276 W / (m·K).

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a carbon-based electromagnetic wave absorbing rubber, characterized in that It proceeds as follows:

1. Weigh the carbon-based material, silica, cross-linking agent and rubber, add them into the mechanical dispersion equipment in sequence, and mix them evenly to obtain the precursor; Second, the precursor is placed in a vulcanization mold, and then placed in a flat vulcanizer for hot pressing and vulcanization to obtain a carbon-based electromagnetic wave absorbing rubber, thereby completing the preparation method.

2. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 1, characterized in that The carbon-based material, silicon dioxide, cross-linking agent and rubber described in step 1 are weighed according to the mass ratio of (1-15):(0-5):(1-3):(83-97).

3. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 2, characterized in that The carbon-based material, silicon dioxide, cross-linking agent and rubber described in step 1 are weighed at a mass ratio of 15:0:2:

83.

4. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 1, characterized in that When the weighed amount of silicon dioxide in step one is 0, the carbon-based material is rGO@SiO2 and / or GO@SiO2; when the weighed amount of silicon dioxide is not 0, the carbon-based material is one or a combination of several of graphene, graphene oxide, reduced graphene oxide, rGO@SiO2, GO@SiO2, carbon nanotubes, and carbon black.

5. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 1, characterized in that The silicon dioxide described in step 1 is one or a combination of crystalline silicon dioxide, amorphous silicon dioxide, synthetic silicon dioxide, and nano silicon dioxide.

6. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 1, characterized in that The crosslinking agent described in step 1 is one or a combination of aminosilane, epoxysilane, silane olefin, mercaptosilane, vinyltriethoxysilane, bis(25-3) crosslinking agent, disulfur peroxide, sulfur, and benzoyl peroxide.

7. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 1, characterized in that The rubber in step 1 is one or a combination of natural rubber, butadiene rubber, silicone rubber, nitrile rubber, styrene butadiene rubber, and ethylene propylene diene monomer rubber.

8. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 1, characterized in that The mechanical dispersing equipment in step 1 is an open mixer or an internal mixer.

9. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 1, characterized in that The parameters for hot pressing vulcanization in the flat vulcanizer in step 2 are: temperature 160-210° C., pressure 5-15 MPa, and hot pressing time 1-20 min.

10. The method for preparing a carbon-based electromagnetic wave absorbing rubber according to claim 1, characterized in that The thickness of the carbon-based electromagnetic wave absorbing rubber obtained in step 2 is 0.1 to 5 mm.

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