Lightweight shielding material and method for manufacturing the same

Abstract

The present application relates to a kind of light shielding material and its preparation method, the light shielding material has the foaming structure by foaming main body, made of raw material of foaming material and conductive filler, and the foaming wall inner wall of foaming main body is evenly distributed with conductive filler;Shielding material is pressurized, and the foaming wall between adjacent foaming main body is mutually contacted, to realize conductive shielding;Preparation method: first component and second component are prepared respectively, and then mixed, calendering molding again.The light shielding material of the present application has the characteristics of low density, light weight, and it can be used normally under 50% compression rate, and under the same compression rate, the compression force of the light shielding material of the present application is less than that of traditional shielding material;Preparation method is simple and feasible, and economic cost is low, and production efficiency is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic shielding, in particular to a lightweight shielding material and a preparation method thereof. BACKGROUND

[0002] At present, the development of new energy vehicles and the fields of aviation and aerospace in China puts forward the demand for lightweight shielding materials. Since the traditional shielding material relies on the electric conduction between the conductive particles at a close enough distance to make the resistance of the material not too large to achieve the shielding function, such electric conduction principle leads to the fact that the shielding material cannot meet the requirements of low density and lightweight, which is especially a problem to be solved in the fields of aviation and aerospace. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a lightweight shielding material and a preparation method thereof.

[0004] The technical solution adopted by the present application to solve the technical problem is: a lightweight shielding material, the lightweight shielding material has a foaming structure composed of foaming bodies, is made of raw materials of foaming materials and conductive fillers, and the inner walls of the foaming walls of the foaming bodies are uniformly distributed with conductive fillers; the shielding material is pressurized, and the foaming walls of adjacent foaming bodies are in contact with each other to realize electric conduction shielding.

[0005] The lightweight shielding material is made by mixing the first component and the second component in a weight ratio of 1:(0.5-1.5); the first component is made of the following raw materials in weight fractions: 30-70 parts of a first crosslinking agent, 3-7 parts of a first reinforcing agent, 40-80 parts of a first conductive filler, and 0.05-0.15 parts of a catalyst; the second component is made of the following raw materials in weight fractions: 30-70 parts of a second crosslinking agent, 3-7 parts of a second reinforcing agent, and 40-80 parts of a second conductive filler.

[0006] Preferably, the first crosslinking agent includes vinyl silicone oil and hydroxyl silicone oil, the second crosslinking agent includes high hydrogen-containing silicone oil, and the mass fraction of hydrogen in the high hydrogen-containing silicone oil is greater than 10%; or, the first crosslinking agent includes vinyl silicone resin and hydroxyl silicone resin, the second crosslinking agent includes high hydrogen-containing silicone resin, and the mass fraction of hydrogen in the high hydrogen-containing silicone resin is greater than 10%.

[0007] Preferably, the first reinforcing agent and the second reinforcing agent are both fumed white carbon black.

[0008] Preferably, the first conductive filler and the second conductive filler both include nickel-carbon powder and nickel-plated carbon fiber, the particle size of the nickel-carbon powder is 30-500 μm, the aspect ratio of the nickel-plated carbon fiber is (5-8):1, and the length of the nickel-plated carbon fiber is 0.2-30 mm.

[0009] Preferably, the catalyst is platinum gold water, and its concentration is 2000-4000 ppm.

[0010] A preparation method of a lightweight shielding material, comprising the following steps:

[0011] S1, weighing: weighing 30-70 parts of a first crosslinking agent, 3-7 parts of a first reinforcing agent, 40-80 parts of a first conductive filler, 0.05-0.15 parts of a catalyst, 30-70 parts of a second crosslinking agent, 3-7 parts of a second reinforcing agent, and 40-80 parts of a second conductive filler;

[0012] S2, preparing a first component: mixing and stirring the first crosslinking agent, the first reinforcing agent, and the catalyst, then adding the first conductive filler in portions and mixing and stirring, the mixing temperature being 20-40℃, to obtain the first component;

[0013] S3, preparing a second component: mixing and stirring the second crosslinking agent and the second reinforcing agent, then adding the second conductive filler in portions and mixing and stirring, the mixing temperature being 20-40℃, to obtain the second component;

[0014] S4, mixing: mixing and stirring the first component and the second component according to a weight ratio of 1:(0.5-1.5), then calendering and slitting, to obtain the lightweight shielding material.

[0015] Preferably, in the S2 step, the first crosslinking agent, the first reinforcing agent, and the catalyst are mixed and stirred at 500-1500 r / min for 1-5 min, then part of the first conductive filler is added and mixed, stirred at 300-1000 r / min for 1-5 min, the remaining first conductive filler is added and mixed, stirred at 300-1000 r / min for 20-40 min, and then stirred at 500-1500 r / min for 20-40 min.

[0016] Preferably, in the S3 step, the second crosslinking agent and the second reinforcing agent are mixed and stirred at 500-1500 r / min for 1-5 min, then part of the second conductive filler is added and mixed, stirred at 300-1000 r / min for 1-5 min, the remaining second conductive filler is added and mixed, stirred at 300-1000 r / min for 20-40 min, and then stirred at 500-1500 r / min for 20-40 min.

[0017] Preferably, in the S4 step, the first component and the second component are mixed and stirred at 300-1000 r / min for 1-5 min.

[0018] Preferably, in the S4 step, the calendering operation is performed at 0.5-1.5 m / min, followed by a heat treatment at 100-150 DEG C at 0.4-0.8 m / min.

[0019] The implementation of the present application has the following beneficial effects:

[0020] The lightweight shielding material of the present application combines the foamed material with the conductive filler, so that the conductive filler is uniformly distributed in the foamed wall of the shielding material. By pressing the shielding material, the foamed walls are in contact with each other, and the distance between the conductive fillers is reduced, thereby enhancing the conductive shielding performance of the material. In addition, the shielding material of the present application has the characteristics of low density and lightweight, and it can be used normally at a compression rate of 50%. Under the same compression rate, the compression force of the lightweight shielding material of the present application is smaller than that of the conventional shielding material.

[0021] The present application prepares the first component and the second component respectively, then mixes and stirs them, and finally obtains the lightweight shielding material through the calendering process. The preparation method is simple and feasible, has low economic cost, and has high production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0022] The present application will be further described below in conjunction with the drawings and examples. In the drawings:

[0023] Figure 1 is a light microscope observation diagram of the lightweight shielding material of Example 1 of the present application at a compression rate of 0%;

[0024] Figure 2 is a light microscope observation diagram of the lightweight shielding material of Example 1 of the present application at a compression rate of 30%;

[0025] Figure 3 is a light microscope observation diagram of the lightweight shielding material of Example 1 of the present application at a compression rate of 40%;

[0026] Figure 4 is a light microscope observation diagram of the lightweight shielding material of Example 1 of the present application at a compression rate of 50%;

[0027] Figure 5 is a compression rate-compression force-resistance comparison curve diagram of the shielding materials of Example 1, Comparative Example 1 and Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0028] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the present application will be further described below in conjunction with the examples, which are only used to explain the present application and do not constitute a limitation on the protection scope of the present application.

[0029] It should be further noted that the terms "first", "second", "third", etc. are only for the convenience of describing the technical solutions, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features with "first", "second", "third", etc. can be explicitly or implicitly included one or more of the features. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] The present application provides a kind of light shielding material, the shielding material has the foaming structure of foaming main body, made of raw material of foaming material and conductive filler, and the foaming wall of foaming main body is uniformly distributed with conductive filler on inner wall.The adjacent foaming wall of foaming main body is contacted with each other by pressurizing shielding material, to realize conductive shielding.With the increase of pressure, the contact area between the foaming wall of adjacent foaming main body increases, the distance between the conductive filler in the foaming wall reduces, so that the resistance of shielding material becomes smaller, the conductive performance is enhanced, and the shielding performance is also enhanced.

[0031] The light shielding material is made by mixing the first component and the second component in a weight ratio of 1:(0.5-1.5); the first component is made of the following raw materials in weight ratio: 30-70 parts of the first crosslinking agent, 3-7 parts of the first reinforcing agent, 40-80 parts of the first conductive filler and 0.05-0.15 parts of the catalyst; the second component is made of the following raw materials in weight ratio: 30-70 parts of the second crosslinking agent, 3-7 parts of the second reinforcing agent and 40-80 parts of the second conductive filler. Among them, the first crosslinking agent, the first reinforcing agent, the catalyst, the second crosslinking agent and the second reinforcing agent are raw materials of foaming material, and the first conductive filler and the second conductive filler are conductive fillers.

[0032] Among them, the first crosslinking agent includes vinyl silicone oil and hydroxyl silicone oil in any mass ratio, preferably the mass ratio of vinyl silicone oil and hydroxyl silicone oil is 1:1; the second crosslinking agent includes high hydrogen-containing silicone oil, and the mass fraction of hydrogen in the high hydrogen-containing silicone oil is greater than 10%. Alternatively, the first crosslinking agent includes vinyl silicone resin and hydroxyl silicone resin in any mass ratio, and the second crosslinking agent includes high hydrogen-containing silicone resin, and the mass fraction of hydrogen in the high hydrogen-containing silicone resin is greater than 10%. Among them, the mass fraction of hydrogen in the high hydrogen-containing silicone oil and the high hydrogen-containing silicone resin is greater than 10%, which is not specifically limited. The first crosslinking agent and the second crosslinking agent react under the action of the catalyst to form silica gel through reticular crosslinking, and the hydrogen generated by the reaction acts as a foaming agent for foaming.

[0033] Further, the second component should at least include a second reinforcing agent and a second conductive filler in addition to the second cross-linking agent, if the content of the second cross-linking agent (which can be a high-hydrogen silicone oil or a high-hydrogen silicone resin) in the reaction system is too high, the reaction rate of the first cross-linking agent and the second cross-linking agent is too fast, and the reaction is not easy to control, therefore, the second reinforcing agent and the second conductive filler are used to dilute the second cross-linking agent, and the second reinforcing agent has the same composition as the first reinforcing agent, and the second conductive filler has the same composition as the second conductive filler. Further, after the first component and the second component are mixed in a weight ratio of 1:(0.5-1.5), the contents of the first cross-linking agent and the second cross-linking agent in the reaction system are equal, the contents of the first reinforcing agent and the second reinforcing agent are equal, and the contents of the first conductive filler and the second conductive filler are equal, so that the first component and the second component can be fully mixed and uniform.

[0034] The first reinforcing agent and the second reinforcing agent are both fumed white carbon black, which has a reinforcing effect and can improve the mechanical properties such as tensile strength of the lightweight shielding material silicone rubber. Preferably, the first reinforcing agent and the second reinforcing agent are both fumed white carbon black A200 or fumed white carbon black A300.

[0035] The catalyst is platinum-gold water (i.e., platinum-gold catalyst), and the concentration thereof is 2000-4000 ppm. The catalyst is used to catalyze the reaction of the first cross-linking agent and the second cross-linking agent, and in addition, the catalyst also has a foaming effect.

[0036] The first conductive filler and the second conductive filler both include nickel-carbon powder and nickel-plated carbon fiber in any mass ratio, the particle size of the nickel-carbon powder is 30-500 μm, and the aspect ratio of the nickel-plated carbon fiber is (5-8):1, wherein the aspect ratio is the ratio of length to diameter, and the length of the nickel-plated carbon fiber is 0.2-30 mm. The particle size of the nickel-carbon powder and the aspect ratio and length of the nickel-plated carbon fiber can be within the above corresponding ranges, and are not specifically limited. In some embodiments, the first conductive filler and the second conductive filler both include silver-carbon powder and silver-plated carbon fiber, or the first conductive filler and the second conductive filler both include aluminum-carbon powder and aluminum-plated carbon fiber.

[0037] The application also provides a preparation method of the lightweight shielding material, which comprises the following steps:

[0038] S1, weighing: weighing 30-70 parts of the first cross-linking agent, 3-7 parts of the first reinforcing agent, 40-80 parts of the first conductive filler, 0.05-0.15 parts of the catalyst, 30-70 parts of the second cross-linking agent, 3-7 parts of the second reinforcing agent, and 40-80 parts of the second conductive filler.

[0039] S2, preparing the first component: mixing and stirring the first cross-linking agent, the first reinforcing agent, and the catalyst, and then adding the first conductive filler in batches and mixing and stirring, the mixing temperature is 20-40 °C, to obtain the first component.

[0040] Preferably, in the S2 step, the first cross-linking agent, the first reinforcing agent and the catalyst are mixed, stirred at 500-1500 r / min for 1-5 min, then part of the first conductive filler is added and mixed, stirred at 300-1000 r / min for 1-5 min, the remaining first conductive filler is added and mixed, stirred at 300-1000 r / min for 20-40 min, and then stirred at 500-1500 r / min for 20-40 min.

[0041] S3, preparing the second component: mixing the second cross-linking agent and the second reinforcing agent, then adding the second conductive filler in portions and mixing, the mixing temperature is 20-40℃, to obtain the second component.

[0042] Preferably, in the S3 step, the second cross-linking agent and the second reinforcing agent are mixed, stirred at 500-1500 r / min for 1-5 min, then part of the second conductive filler is added and mixed, stirred at 300-1000 r / min for 1-5 min, the remaining second conductive filler is added and mixed, stirred at 300-1000 r / min for 20-40 min, and then stirred at 500-1500 r / min for 20-40 min.

[0043] In the S2 and S3 steps, the first conductive filler and the second conductive filler are added in portions, preferably in two equal portions; the mixing temperature should not be higher than 40℃, otherwise the curing time of the first component and the second component after mixing will be too long, at the same time, the mixing temperature should not be too low, otherwise the viscosity of the first component and the second component will increase, which is not conducive to uniform mixing of the two; therefore, the mixing temperature is selected to be 20-40℃, and the mixing temperature can be within 20-40℃, without specific limitation.

[0044] S4, mixing: mixing the first component and the second component according to the weight ratio of 1:(0.5-1.5), then calendering and slitting to obtain the lightweight shielding material. Preferably, the first component and the second component are mixed according to the weight ratio of 1:1.

[0045] Preferably, in the S4 step, the first component and the second component are mixed, stirred at 300-1000 r / min for 1-5 min; in the calendering operation, calendering is performed at 0.5-1.5 m / min, then heating treatment is performed at 100-150℃ at 0.4-0.8 m / min.

[0046] The calendering forming process can be that the first component and the second component are mixed and stirred, and then immediately injected into a two-roller calender, the distance between the two rollers of the calender is adjusted to 1.4-1.8 mm, and the calendering is performed at a speed of 0.5-1.5 m / min with an amplitude of 350-450 mm. Then the mixed material is heated and treated in a tunnel furnace with a length of 10-14 meters and a width of 550-650 mm at a speed of 0.4-0.8 m / min at a temperature of 100-150°C. Finally, the material is cut and packaged for storage. The specific parameters of the calendering process can be adjusted according to actual needs, which are not specifically limited here. The size and shape of the material can be selected and set according to actual needs, which are not specifically limited here. In some embodiments, the material can be a square sheet with a size of 400 mm*400 mm*2 mm (thickness).

[0047] The mixing and stirring operations in steps S1-S4 can use a 5L planetary mixer, or other stirring methods.

[0048] Since the first component and the second component are both liquid materials at 20-40°C, they can be mixed uniformly and then solidified. At this time, the calendering process can be used to quickly and continuously produce sheets. In some embodiments, an injection process with automatic stirring and injection can also be used to form the material.

[0049] The following is further illustrated by examples:

[0050] The shielding materials of Examples 1-4 were prepared according to the above preparation method, and the components and their weight fractions are shown in Table 1.

[0051] Table 1 Components and their weight fractions of Examples 1-4

[0052]

[0053]

[0054] The preparation method of the shielding materials of Examples 1-4 is as follows:

[0055] The preparation method of the shielding material of Example 1 includes the following steps:

[0056] S1, weighing: weigh 25 parts of ethylene silicone oil, 25 parts of hydroxyl silicone oil, 5 parts of fumed white carbon black A200, 55 parts of nickel carbon powder, 2 parts of nickel-coated carbon fiber, 0.1 part of platinum gold water (3000 ppm), 50 parts of high hydrogen silicone oil, 5 parts of fumed white carbon black A200, 55 parts of nickel carbon powder, and 2 parts of nickel-coated carbon fiber.

[0057] S2, Preparation of the first component: vinyl silicone oil 25 parts, hydroxyl silicone oil 25 parts, fumed white carbon black A200 5 parts and platinum gold water (3000 ppm) 0.1 part were mixed and stirred at 1000 r / min for 3 min, then nickel-carbon powder 27.5 parts and nickel-plated carbon fiber 1 part were mixed and stirred at 500 r / min for 3 min, then nickel-carbon powder 27.5 parts and nickel-plated carbon fiber 1 part were mixed and stirred at 500 r / min for 30 min and then at 1000 r / min for 30 min to obtain the first component.

[0058] S3, Preparation of the second component: high hydrogen-containing silicone oil 50 parts and fumed white carbon black A200 5 parts were mixed and stirred at 1000 r / min for 3 min, then nickel-carbon powder 27.5 parts and nickel-plated carbon fiber 1 part were mixed and stirred at 500 r / min for 3 min, then nickel-carbon powder 27.5 parts and nickel-plated carbon fiber 1 part were mixed and stirred at 500 r / min for 30 min and then at 1000 r / min for 30 min to obtain the second component.

[0059] S4, Mixing: the first component and the second component were mixed in a weight ratio of 1:1 and stirred at 500 r / min for 3 min; then calendering was performed at 1 m / min, then heating treatment was performed at 125°C at 0.6 m / min, and the lightened shielding material was obtained after slitting.

[0060] The preparation method of the shielding material of Example 2 comprises the following steps:

[0061] S1, Weighing: vinyl silicone resin 15 parts, hydroxyl silicone resin 15 parts, fumed white carbon black A200 3 parts, silver-carbon powder 38.5 parts, silver-plated carbon fiber 1.5 parts, platinum gold water (4000 ppm) 0.15 parts, high hydrogen-containing silicone resin 60 parts, fumed white carbon black A200 6 parts, silver-carbon powder 77 parts and silver-plated carbon fiber 3 parts were weighed.

[0062] S2, Preparation of the first component: vinyl silicone resin 15 parts, hydroxyl silicone resin 15 parts, fumed white carbon black A200 3 parts and platinum gold water (4000 ppm) 0.15 parts were mixed and stirred at 1500 r / min for 1 min, then silver-carbon powder 19.25 parts and silver-plated carbon fiber 0.75 parts were mixed and stirred at 1000 r / min for 1 min, then silver-carbon powder 19.25 parts and silver-plated carbon fiber 0.75 parts were mixed and stirred at 1000 r / min for 20 min and then at 1500 r / min for 20 min to obtain the first component.

[0063] S3, Preparation of the second component: high hydrogen-containing silicone resin 60 parts and fumed white carbon black A200 6 parts were mixed and stirred at 1500 r / min for 1 min, then silver carbon powder 38.5 parts and silver-coated carbon fiber 1.5 parts were added and mixed at 1000 r / min for 1 min, then silver carbon powder 38.5 parts and silver-coated carbon fiber 1.5 parts were added and mixed at 1000 r / min for 20 min, then mixed at 1500 r / min for 20 min to obtain the second component.

[0064] S4, Mixing: the first component and the second component were mixed in a weight ratio of 1:0.5 and stirred at 1000 r / min for 1 min; then calendering was carried out at 1.5 m / min, then heating treatment was carried out at 150℃ at 0.8 m / min, and the lightened shielding material was obtained after slitting.

[0065] The preparation method of the shielding material of Example 3 comprises the following steps:

[0066] S1, weighing: ethylene silicone oil 22.5 parts, hydroxyl silicone oil 22.5 parts, fumed white carbon black A300 7 parts, aluminum carbon powder 67.5 parts, aluminum-coated carbon fiber 2.5 parts, platinum gold water (2000 ppm) 0.05 parts, high hydrogen-containing silicone oil 30 parts, fumed white carbon black A300 3 parts, aluminum carbon powder 48 parts and aluminum-coated carbon fiber 2 parts.

[0067] S2, Preparation of the first component: ethylene silicone oil 22.5 parts, hydroxyl silicone oil 22.5 parts, fumed white carbon black A300 7 parts and platinum gold water (2000 ppm) 0.05 parts were mixed and stirred at 500 r / min for 5 min, then aluminum carbon powder 33.75 parts and aluminum-coated carbon fiber 1.25 parts were added and mixed at 300 r / min for 5 min, then aluminum carbon powder 33.75 parts and aluminum-coated carbon fiber 1.25 parts were added and mixed at 300 r / min for 40 min, then mixed at 500 r / min for 40 min to obtain the first component.

[0068] S3, Preparation of the second component: high hydrogen-containing silicone oil 30 parts and fumed white carbon black A300 3 parts were mixed and stirred at 500 r / min for 5 min, then aluminum carbon powder 24 parts and aluminum-coated carbon fiber 1 part were added and mixed at 300 r / min for 5 min, then aluminum carbon powder 24 parts and aluminum-coated carbon fiber 1 part were added and mixed at 300 r / min for 40 min, then mixed at 500 r / min for 40 min to obtain the second component.

[0069] S4, mixing: the first component and the second component are mixed according to the weight ratio of 1:1.5, stirred at 300 r / min for 5 min; then calendering is carried out, calendering is carried out at 0.5 m / min, then heating treatment is carried out at 100℃ at 0.4 m / min, and the lightweight shielding material is obtained after slitting.

[0070] The preparation method of the shielding material of example 4 comprises the following steps:

[0071] S1, weighing: weigh ethylene silicone oil 35 parts, hydroxyl silicone oil 35 parts, fumed white carbon black A200 7 parts, nickel carbon powder 77.5 parts, plated nickel carbon fiber 2.5 parts, platinum gold water (4000ppm) 0.1 parts, high hydrogen-containing silicone oil 70 parts, fumed white carbon black A200 7 parts, nickel carbon powder 38 parts and plated nickel carbon fiber 2 parts.

[0072] S2, preparation of the first component: mix ethylene silicone oil 35 parts, hydroxyl silicone oil 35 parts, fumed white carbon black A200 7 parts and platinum gold water (4000ppm) 0.1 parts, stir at 1300 r / min for 2 min, then add nickel carbon powder 38.75 parts and plated nickel carbon fiber 1.25 parts, stir at 800 r / min for 2 min, then add nickel carbon powder 38.75 parts and plated nickel carbon fiber 1.25 parts, stir at 800 r / min for 25 min, then stir at 1300 r / min for 25 min, to obtain the first component.

[0073] S3, preparation of the second component: mix high hydrogen-containing silicone oil 70 parts and fumed white carbon black A200 7 parts, stir at 1300 r / min for 2 min, then add nickel carbon powder 19 parts and plated nickel carbon fiber 1 part, stir at 800 r / min for 2 min, then add nickel carbon powder 19 parts and plated nickel carbon fiber 1 part, stir at 800 r / min for 25 min, then stir at 1300 r / min for 25 min, to obtain the second component.

[0074] S4, mixing: the first component and the second component are mixed according to the weight ratio of 1:1.3, stirred at 800 r / min for 2 min; then calendering is carried out, calendering is carried out at 0.8 m / min, then heating treatment is carried out at 125℃ at 0.7 m / min, and the lightweight shielding material is obtained after slitting.

[0075] Performance test:

[0076] The lightweight shielding material of example 1 is pressurized to make its compression rate reach 0%, 30%, 40% and 50% respectively, and observed by optical microscope, and the observation results are as follows: Figures 1 to 4The shielding material of Example 1 was compared with a conventional shielding material (a nickel-carbon conductive silicone rubber material was selected) in performance, wherein the nickel-carbon conductive silicone rubber material with a Shore A hardness of 50A was taken as Comparative Example 1, and the nickel-carbon conductive silicone rubber material with a Shore A hardness of 70A was taken as Comparative Example 2.

[0077] I. Hardness Test

[0078] 1. Test Instrument

[0079] Shore C hardness tester: LX-C (Wenzhou Shandu Instrument Co., Ltd.); Shore A hardness tester: LX-A

[0080] 2. Test Procedure

[0081] (1) A 1 inch x 1 inch square test piece was punched out from a vulcanized test piece with a thickness of 2 mm, three test pieces were stacked into one test sample, and the shielding materials of Example 1, Comparative Example 1 and Comparative Example 2 were respectively made into three test samples;

[0082] (2) The test sample was placed on the hardness tester test platform, the handle was put down to make the hardness tester probe press down to the sample surface at a uniform speed, and the value was read.

[0083] Among them, the Shore C type hardness tester is suitable for foamed rubber materials, and the Shore A type hardness tester is suitable for general rubber materials, so the Shore C hardness of the shielding material of Example 1 is tested, and the Shore A hardness of the shielding materials of Comparative Example 1 and Comparative Example 2 is tested. The test procedure refers to the standard ASTM D2240, and the test results are shown in Table 2.

[0084] II. Density Test

[0085] 1. Test Instrument

[0086] Density balance: JA3003J

[0087] 2. Test Procedure

[0088] (1) A 1 inch x 1 inch square test piece was punched out from a vulcanized test piece with a thickness of 2 mm as one test sample, and the shielding materials of Example 1, Comparative Example 1 and Comparative Example 2 were respectively made into five test samples;

[0089] (2) The sample was placed on the density balance, and the mass of the sample in air and water was measured in turn, and the density was calculated by operating the density balance. When measuring, pay attention to remove the bubbles on the surface of the sample. The test procedure refers to the test standard ASTM D792, and the test results are shown in Table 3.

[0090] III. Compression Rate-Compression Force-Resistance Test

[0091] 1. Test Instrument

[0092] High-precision load testing machine: MAX-5KN-P (JISC); Resistance meter: RM3545 (Hioki)

[0093] 2. Experimental Procedure

[0094] (1) A circular piece with a diameter of 14 mm was punched from a 2 mm thick vulcanized molded test piece as a test sample, and test samples of shielding materials of Example 1, Comparative Example 1 and Comparative Example 2 were prepared respectively.

[0095] (2) Place the sample on the test platform of a high-precision load testing machine with an external resistance meter, set the compression program, and test the compressive force and resistance of the sample at compression rates of 0%, 10%, 20%, 30%, 40%, and 50%. The test results are shown in Table 4 and... Figure 5 As shown. Among them, the shielding material of Comparative Example 2 cannot achieve a compression rate of 50%, and its maximum compression rate under normal use is 48%.

[0096] Table 2. Hardness test results of shielding materials in Example 1, Comparative Example 1, and Comparative Example 2.

[0097] Test sample Sample 1 Sample 2 Sample 3 Example 1 (C) 84 85 84 Comparative Example 1 (A) 50 50 49 Comparative Example 2 (A) 75 75 76

[0098] Table 3. Test results of shielding material density in Example 1, Comparative Example 1, and Comparative Example 2.

[0099] Test sample Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Example 1 (g / cm 3 )]]> 1.507 1.427 1.529 1.466 1.486 Comparative Example 1 (g / cm 3 )]]> 2.001 2.006 2.005 1.998 2.003 Comparative Example 2 (g / cm 3 )]]> 2.128 2.126 2.123 2.122 2.126

[0100] Table 4. Compression ratio-compression force-resistance test results for Example 1, Comparative Example 1, and Comparative Example 2

[0101]

[0102] Note: " / " indicates that it has not been tested.

[0103] Depend on Figures 1 to 4 It is understood that the lightweight shielding material of the present invention has a foamed structure composed of a foamed body. Conductive fillers are uniformly distributed on the inner wall of the foamed body. As the material compression ratio increases, the contact area between adjacent foamed walls becomes larger, resulting in stronger conductive shielding performance of the material.

[0104] As shown in Table 2, the Shore C hardness of the shielding material in Example 1 is about 85C. It is a foamed silicone rubber material, which has a lower hardness than traditional shielding materials (silicone rubber materials), making it more conducive to compression deformation.

[0105] As shown in Table 3, the density of the shielding material in Example 1 is less than 1.7 g / cm³. 3 At 1.5g / cm 3 The density of the shielding material in Comparative Example 1 and Comparative Example 2 is greater than 1.7 g / cm³.3 and the density of the shielding material is less than 2.0 g / cm 3 It can be seen that the shielding material of the present application has a smaller density, which can meet the requirement of light weight, while the density of the traditional conductive shielding material is larger.

[0106] As shown in Table 4 and Figure 5 It can be seen that with the increase of the compression rate, the resistance value of the shielding material of Example 1 is significantly reduced, and when the compression rate reaches 30% or more, the conductive performance of the shielding material is close to or even better than that of the traditional conductive shielding material; under the same compression rate, the compression force value of the shielding material of Example 1 is close to that of the softer 50A nickel-carbon conductive silicone rubber (Comparative Example 1), while the 70A nickel-carbon conductive silicone rubber (Comparative Example 2) requires a larger compression force when compressed due to its larger hardness, and cannot reach a compression rate of 50%, but even if the 70A nickel-carbon conductive silicone rubber reaches a compression rate of 50%, the material cannot be used normally because it cannot rebound after long-term use, resulting in shielding failure. Generally, shielding materials have shielding effect only under pressure, while the light-weight shielding material of the present application can be used normally under a compression rate of 50%, and can still rebound to restore the initial shape after long-term use.

[0107] In summary, the present application provides a light-weight shielding material and a preparation method thereof, which combines a foaming material with a conductive filler, so that the conductive filler is uniformly distributed in the foaming wall of the shielding material. By pressing the shielding material, the foaming walls are in contact with each other, and the distance between the conductive fillers is reduced, thereby enhancing the conductive shielding performance of the material. In addition, the shielding material of the present application has the characteristics of low density and light weight, and can be used normally under a compression rate of 50%, while under the same compression rate, the compression force of the light-weight shielding material of the present application is smaller than that of the traditional shielding material. The light-weight shielding material is prepared by separately preparing the first component and the second component, mixing and stirring them, and finally molding by calendering process. The preparation method is simple and feasible, has low economic cost, and has high production efficiency.

[0108] It can be understood that the above examples only express the preferred embodiments of the present application, which are described in detail and specifically, but cannot be construed as limiting the scope of the present application; it should be noted that for ordinary skilled persons in the art, the above technical features can be freely combined without departing from the concept of the present application, and several modifications and improvements can be made, which all belong to the protection scope of the present application; therefore, any equivalent transformation and modification within the scope of the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. A lightweight shielding material, characterized in that, The lightweight shielding material has a foamed structure composed of a foamed body, which is made of the raw materials of the foaming material and conductive fillers, and the conductive fillers are uniformly distributed on the inner wall of the foamed body; when the shielding material is pressurized, the foamed walls of adjacent foamed bodies come into contact with each other to achieve conductive shielding. The lightweight shielding material is made by mixing a first component and a second component in a weight ratio of 1:(0.5-1.5); the first component is made from the following raw materials in parts by weight: 30-70 parts of a first crosslinking agent, 3-7 parts of a first reinforcing agent, 40-80 parts of a first conductive filler, and 0.05-0.15 parts of a catalyst; the second component is made from the following raw materials in parts by weight: 30-70 parts of a second crosslinking agent, 3-7 parts of a second reinforcing agent, and 40-80 parts of a second conductive filler; The first crosslinking agent comprises vinyl silicone oil and hydroxyl silicone oil; or, the first crosslinking agent comprises vinyl silicone resin and hydroxyl silicone resin. The second crosslinking agent comprises a high-hydrogen-content silicone oil, wherein the mass fraction of hydrogen in the high-hydrogen-content silicone oil is greater than 10%; or, the second crosslinking agent comprises a high-hydrogen-content silicone resin, wherein the mass fraction of hydrogen in the high-hydrogen-content silicone resin is greater than 10%. Both the first conductive filler and the second conductive filler include nickel-carbon powder and nickel-plated carbon fiber.

2. The lightweight shielding material according to claim 1, characterized in that, Both the first reinforcing agent and the second reinforcing agent are fumed silica.

3. The lightweight shielding material according to claim 1, characterized in that, The particle size of nickel-carbon powder is 30-500μm, the aspect ratio of nickel-plated carbon fiber is (5-8):1, and the length of nickel-plated carbon fiber is 0.2-30mm.

4. The lightweight shielding material according to claim 1, characterized in that, The catalyst is platinum water with a concentration of 2000-4000 ppm.

5. A method for preparing the lightweight shielding material according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Weighing: Weigh 30-70 parts of the first crosslinking agent, 3-7 parts of the first reinforcing agent, 40-80 parts of the first conductive filler, 0.05-0.15 parts of the catalyst, 30-70 parts of the second crosslinking agent, 3-7 parts of the second reinforcing agent, and 40-80 parts of the second conductive filler; S2. Preparation of the first component: The first crosslinking agent, the first reinforcing agent and the catalyst are mixed and stirred, and then the first conductive filler is added in batches and mixed and stirred at a mixing temperature of 20-40℃ to obtain the first component; S3. Preparation of the second component: The second crosslinking agent and the second reinforcing agent are mixed and stirred, and then the second conductive filler is added in batches and mixed and stirred. The mixing temperature is 20-40℃ to obtain the second component. S4. Mixing: The first component and the second component are mixed and stirred in a weight ratio of 1:(0.5-1.5), then calendered and slit to obtain a lightweight shielding material.

6. The method for preparing the lightweight shielding material according to claim 5, characterized in that, In step S2, the first crosslinking agent, the first reinforcing agent, and the catalyst are mixed and stirred at 500-1500 r / min for 1-5 min. Then, a portion of the first conductive filler is added and mixed, and stirred at 300-1000 r / min for 1-5 min. The remaining first conductive filler is then added and mixed, and stirred at 300-1000 r / min for 20-40 min, followed by stirring at 500-1500 r / min for 20-40 min.

7. The method for preparing the lightweight shielding material according to claim 5, characterized in that, In step S3, the second crosslinking agent and the second reinforcing agent are mixed and stirred at 500-1500 r / min for 1-5 min. Then, a portion of the second conductive filler is added and mixed, and stirred at 300-1000 r / min for 1-5 min. The remaining second conductive filler is then added and mixed, and stirred at 300-1000 r / min for 20-40 min, followed by stirring at 500-1500 r / min for 20-40 min.

8. The method for preparing the lightweight shielding material according to claim 5, characterized in that, In step S4, the first component and the second component are mixed and stirred at 300-1000 r / min for 1-5 min.

9. The method for preparing the lightweight shielding material according to claim 5, characterized in that, In step S4, the rolling operation is performed at a speed of 0.5-1.5 m / min, followed by heat treatment at 100-150°C at a speed of 0.4-0.8 m / min.

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