Lightweight shielded cable and preparation method thereof
By employing an inner-outer core wire, insulation layer, metal foil layer, and modified shielding layer structure in the shielded cable, and utilizing core-shell structured composite microspheres and inorganic particles in the conductive adhesive, the problems of excessive weight and poor electromagnetic shielding effect of the shielded cable are solved, achieving lightweight and highly efficient electromagnetic shielding.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGYIN YUANDA ELECTRICAL MATERIALS CO LTD
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-01
AI Technical Summary
Existing shielded cables suffer from excessive weight and poor electromagnetic shielding performance in applications such as microelectronic devices and aerospace.
The structure consists of a core wire, an insulation layer, a metal foil layer, and a modified shielding layer arranged from the inside out. The modified shielding layer is made of glass fiber cloth impregnated with conductive adhesive. The conductive adhesive contains core-shell composite microspheres, and the outer shell is composed of nano-iron oxide particles and nano-silver particles. Inorganic particles are loaded onto the surface of the polymer microspheres through co-precipitation and reduction methods.
It achieves a lightweight structure while improving electromagnetic shielding effect, and the manufacturing process is simple and the conditions are mild.
Smart Images
Figure CN121964248A_ABST
Abstract
Description
A lightweight shielded cable and its preparation method Technical Field
[0001] This invention relates to the field of electromagnetic shielding technology, specifically to a lightweight shielded cable and its preparation method. Background Technology
[0002] Common shielded cables have a metal mesh braided layer. The material of the metal mesh braided layer is usually red copper or tin-plated copper.
[0003] Shielded cables with metal mesh braiding as the shielding layer are too heavy, which is not conducive to applications in microelectronic devices and aerospace. More and more cable manufacturers are starting to develop shielded cables (with lightweight structures) for aerospace applications, but most of these lightweight cables are still in the laboratory stage.
[0004] Currently, there is an urgent need to develop a shielded cable that combines a lightweight structure with good electromagnetic shielding performance. Summary of the Invention
[0005] One of the objectives of this invention is to overcome the deficiencies in the prior art and provide a shielded cable with a lightweight structure and good shielding effect.
[0006] To address the aforementioned technical problems, this invention provides a lightweight shielded cable, comprising, from the inside out, a core wire, an insulation layer, a metal foil layer, a modified shielding layer, and a surface layer. The modified shielding layer is a glass fiber cloth impregnated with a conductive adhesive. The conductive adhesive includes an adhesive and conductive particles dispersed in the adhesive. The conductive particles are interconnected to form conductive channels. The conductive particles include composite microspheres with a core-shell structure. The core of the composite microsphere is a polymer microsphere, and the outer shell of the composite microsphere is made of an inorganic material. The outer shell is composed of nano-iron oxide particles and nano-silver particles.
[0007] The preferred technical solution is that the mass ratio of the nano-iron oxide particles to the nano-silver particles is 1:(4~5).
[0008] Furthermore, the mass ratio of the nano-iron oxide particles and nano-silver particles can be selected as a point value of 1:4, 1:4.2, 1:4.5, 1:4.7, 1:4.9, or 1:5, or as an interval value between the two points mentioned above, representing the maximum and minimum values.
[0009] The preferred technical solution is that the polymer microspheres are polystyrene microspheres.
[0010] A preferred technical solution is that the modified shielding layer comprises a first modified shielding layer and a second modified shielding layer stacked sequentially; the composite microspheres comprise a first composite microsphere and a second composite microsphere, wherein the average particle size of the first composite microsphere is 0.5~4.5μm and the average particle size of the second composite microsphere is 5~20μm; one of the first composite microsphere and the second composite microsphere is disposed in the first modified shielding layer, and the other of the first composite microsphere and the second composite microsphere is disposed in the second modified shielding layer.
[0011] Furthermore, the average particle size of the first composite microsphere can be selected as a point value of 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 μm or a range of the above two point values as the maximum and minimum values, and the average particle size of the second composite microsphere can be selected as a point value of 5, 7, 9, 10, 14, 17, 19, 20 μm or a range of the above two point values as the maximum and minimum values.
[0012] Furthermore, the first composite microsphere is disposed on the first modified shielding layer, which is located between the metal foil layer and the second modified shielding layer.
[0013] The preferred technical solution is that the polydispersity index of the first composite microsphere is 0.8~1, and the polydispersity index of the second composite microsphere is 0.1~0.7.
[0014] Furthermore, the polydispersity index of the first composite microsphere can be selected as a point value of 0.8, 0.9, or 1, or a range of the above two point values as the maximum and minimum values, and the polydispersity index of the second composite microsphere can be selected as a point value of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7, or a range of the above two point values as the maximum and minimum values.
[0015] A preferred technical solution is that the average thickness of the outer shell is 10% to 20% of the average particle size of the composite microspheres.
[0016] Furthermore, the average thickness of the shell can be selected as a point value of 10%, 13%, 16%, 18%, or 20% of the average particle size of the composite microspheres, or a range of the above two point values as the maximum and minimum values.
[0017] A preferred technical solution is that the conductive microparticles further include carbon black nanoparticles, the average particle size of the carbon black nanoparticles is 30~80nm, and the mass ratio of the composite microspheres to the carbon black nanoparticles in the conductive microparticles is 1:(3~5).
[0018] Furthermore, the average particle size of the nano-carbon black particles can be selected as a point value of 30, 40, 50, 60, 70, or 80 nm, or a range of the above two point values as the maximum and minimum values; the mass ratio of the composite microspheres and nano-carbon black particles in the conductive microparticles can be selected as a point value of 1:3, 1:4, or 1:5, or a range of the above two point values as the maximum and minimum values.
[0019] The second objective of this invention is to provide a method for preparing a lightweight shielded cable, comprising the following steps: S00: preparing modified polystyrene microspheres by dispersion polymerization, wherein the functional groups of the polystyrene microspheres include carboxyl and aldehyde groups; S01: loading nano-iron oxide particles onto the surface of the polystyrene microspheres by co-precipitation; S02: loading nano-silver particles onto the surface of the polystyrene microspheres by reduction polymerization to obtain composite microspheres; S03: mixing the dispersion of the composite microspheres, nano-carbon black particles, and an adhesive to obtain a conductive adhesive; S04: impregnating and drying aminosilane-modified glass fiber cloth into the conductive adhesive to obtain a shielding film.
[0020] A preferred technical solution is that, in S03, the mass ratio of the dispersion to the adhesive is 85:(17~40); the mass ratio of the conductive particles to the dispersant in the dispersion is 25:(45~70); and the solid content of the adhesive is 40%~50%.
[0021] Furthermore, in S03, the mass ratio of the dispersion to the adhesive can be selected as 85:17, 85:30, or 85:40, or a range of the above two values as the maximum and minimum values; the mass ratio of the conductive particles to the dispersant in the dispersion can be selected as 25:45, 25:60, 25:65, or 25:70, or a range of the above two values as the maximum and minimum values; the solid content of the adhesive can be selected as 40%, 45%, or 50%, or a range of the above two values as the maximum and minimum values.
[0022] The preferred technical solution is that the reaction temperature of the SO1 co-precipitation method is 40~45℃.
[0023] Furthermore, the reaction temperature of the SO1 co-precipitation method can be selected as a point value of 40, 41, 42, 43, 44, or 45℃, or as a range of two of the above point values as the maximum and minimum values.
[0024] The advantages and beneficial effects of this invention are as follows: The lightweight shielded cable of this invention relies on a metal foil layer and a modified shielding layer to shield electromagnetic waves. The modified shielding layer, made of composite materials, has a low density, which is conducive to achieving lightweight cable design. Composite microspheres composed of nano-iron oxide particles and nano-silver particles are selected as the conductive particles of the modified shielding layer, thereby improving the electromagnetic shielding performance of the cable. Inorganic particles are loaded on the surface of polymer microspheres using co-precipitation and reduction methods, which are mild and simple. Attached Figure Description
[0025] Figure 1 is a SEM image of the carboxyl / aldehyde bifunctionalized microspheres; Figure 2 is a TEM image of the bifunctionalized microspheres of Example 1 with some nano-iron oxide particles loaded on the surface; Figure 3 is a TEM image of the composite microspheres of Example 1. Detailed Implementation
[0026] The specific embodiments of the present invention will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.
[0027] Core-shell microspheres are composite materials with diameters ranging from nanometers to micrometers, assembled from two different materials using physical or chemical methods. They possess a central core and a heterogeneous outer shell. These microspheres are often functionalized by modifying their surface with various groups. The core of a core-shell microsphere is typically dense, porous, or eccentric, and can take the form of tubular, linear, spherical, rod-shaped, or ring-shaped structures. The outer shell can be continuous and dense, continuous and porous, or discontinuous and granular.
[0028] The metal foil layer can be made by wrapping aluminum foil or by wrapping aluminum-plastic composite tape.
[0029] The pores of fiberglass cloth: Fiberglass cloth is woven from fiberglass yarns, and the interlacing gaps between the yarns constitute the pores of the fiberglass cloth. Fiberglass yarns are generally made by twisting together multiple micron-sized fiberglass monofilaments, and the tiny gaps / micropores formed between these monofilaments also constitute the pores of the fiberglass cloth.
[0030] In the microscopic realm, the particle size distribution of microparticles affects their performance and applications; therefore, the polydispersity index (PDI) is commonly used for evaluation. The PDI value typically falls within the range of 0 to 1. When PDI equals 0, it indicates that the particle size is completely uniform, meaning the system is perfectly monodisperse. If PDI is less than 0.1, it indicates a narrow particle size distribution. When PDI exceeds 0.5, it means that the particle size distribution is wide, and the system exhibits significant polydispersity.
[0031] The preparation process of carboxyl / aldehyde bifunctional (polystyrene) microspheres by weight includes: S00: Mixing 2 parts of polyvinylpyrrolidone, 45 parts of deionized water, and 21 parts of anhydrous ethanol to obtain a polyvinylpyrrolidone solution, and then introducing the polyvinylpyrrolidone solution into a constant temperature stirring device at 65°C for later use; S02: Mixing 0.1 parts of azobisisobutyronitrile and 6 parts of styrene and then introducing the mixture into the constant temperature stirring device of S00, setting the stirring speed to 220 rpm, and after the reaction solution changes from colorless to white, introducing 2 parts of acrylic acid and 4 parts of acrolein into the reaction solution in sequence, and reacting for 24 h; S03: Adjusting the reaction solution to neutral using a pH adjuster and continuing the reaction for 8 h, centrifuging the reaction solution at high speed to obtain a solid product, and washing the solid product multiple times (dispersing with ethanol and centrifuging at high speed) to obtain purified carboxyl / aldehyde bifunctional microspheres.
[0032] Examples and Comparative Examples 1. Examples 1, 1 Comparative Example 1, and 2 Comparative Example 2 regarding the types of particles constituting the shell of the composite microspheres. Example 1
[0033] The preparation process of the composite microspheres in Example 1, by weight, includes: S10: Dispersing 1 part of carboxyl / aldehyde bifunctionalized microspheres in 30 parts of deionized water to obtain a bifunctionalized microsphere dispersion, and introducing the bifunctionalized microsphere dispersion into a constant-temperature sealed stirring device equipped with a pH meter for later use. The temperature is set at 43°C and the stirring speed is 230 rpm; S11: Mixing 0.3 parts of ferrous sulfate heptahydrate and 25 parts of deionized water and introducing the mixture into the constant-temperature sealed stirring device of S10, and adding a pH adjuster to adjust the pH of the reaction solution to 4; S12: Adding ammonia water dropwise to the reaction solution until the pH of the reaction solution is 8.5, at which point the reaction solution turns black; S13: Adjusting the reaction solution to neutral using a pH adjuster and continuing the reaction for 1 hour; S14: Centrifuging the reaction solution at high speed to obtain a solid product, and washing the solid product multiple times (dispersing the solid product with ethanol). After centrifugation (one washing step), bifunctional microspheres (magnetic core-shell microspheres) with some nano-iron oxide particles on the surface are obtained; S15: 1 part of magnetic core-shell microspheres are dispersed in 50 parts of deionized water to obtain a magnetic core-shell microsphere dispersion. The magnetic core-shell microsphere dispersion is introduced into a constant temperature stirring device for later use. The temperature is set at 70℃ and the stirring speed is 200 rpm; S16: Silver nitrate solution and ammonia water are mixed to obtain a silver ammonia solution (the amount of silver nitrate powder is 0.59 parts). The silver ammonia solution is slowly added dropwise to the constant temperature stirring device in S15 (as the silver ammonia solution is added to the reaction solution, the reaction solution gradually changes color). After the reaction solution no longer changes color, the reaction continues for 0.5 h; S17: The reaction solution is centrifuged at high speed to obtain a solid product. The solid product is washed multiple times to obtain bifunctional microspheres (composite microspheres) with nano-iron oxide particles and nano-silver particles on the surface.
[0034] The preparation process of the shielding film in Example 1, by weight, includes: S20: Composite microspheres with an average particle size of 11 μm and a polydispersity index of 0.92 are screened by differential centrifugation (the mass ratio of nano-iron oxide particles and nano-silver particles is 1:4.5 as determined by thermogravimetric analysis, and the average thickness of the inorganic shell is 15% of the average particle size of the composite microspheres as determined by TEM). 5 parts of composite microspheres, 20 parts of nano-carbon black particles (average particle size 50 nm) and 60 parts of 50% isopropanol solution are mixed to obtain 85 parts of conductive particle dispersion; S21: 30 parts of acrylate adhesive (solid content of 45%) and 85 parts of conductive particle dispersion are mixed to obtain conductive adhesive; S22: 0.1 mm thick glass fiber cloth is modified (aminosilane modified), impregnated with conductive adhesive and dried (part of the conductive adhesive enters the pores of the glass fiber cloth, and part of the conductive adhesive remains on the surface of the glass fiber cloth) to obtain a shielding film with a thickness of 0.13 mm.
[0035] The preparation process of the lightweight shielded cable in Example 1 includes: S30: using an extrusion insulation process to wrap silicone rubber on the surface of a stranded conductive core wire with a diameter of 0.45 mm (forming an insulation layer); S31: using a wrapping machine to wrap a 60 μm thick aluminum-plastic composite tape on the surface of the insulation layer (forming a 90 μm thick metal foil layer); S32: using a wrapping machine to wrap a shielding film on the surface of the metal foil layer (forming a 0.2 mm thick modified shielding layer); S33: using an extrusion insulation process to wrap cross-linked polyethylene on the surface of the modified shielding layer (forming a 0.7 mm thick surface layer).
[0036] Comparative Example 1: The preparation process of the composite microspheres in Comparative Example 1, by weight, includes: S10: Dispersing 1 part of carboxyl / aldehyde bifunctionalized microspheres in 30 parts of deionized water to obtain a bifunctionalized microsphere dispersion. The bifunctionalized microsphere dispersion is then introduced into a constant-temperature sealed stirring apparatus equipped with a pH meter. The temperature is set at 43℃ and the stirring speed at 230 rpm. S11: Mixing 0.89 parts of ferrous sulfate heptahydrate and 25 parts of deionized water, and then introducing the mixture into the constant-temperature sealed stirring apparatus of S10, adding a pH adjuster to adjust the pH of the reaction solution to 4. S12: Adding ammonia water dropwise to the reaction solution until the pH of the reaction solution reaches 8.5, at which point the reaction solution turns black. S13: Using p... After adjusting the reaction solution to neutral with H regulator, the reaction continued for 1 hour; S14: The reaction solution was centrifuged at high speed to obtain a solid product. The solid product was washed multiple times to obtain bifunctional microspheres (magnetic core-shell microspheres) with nano-iron oxide particles loaded on the surface; The preparation process of the shielding film of Comparative Example 1 was based on Example 1, except that in S20: Composite microspheres with an average particle size of 11.1 μm and a polydispersity index of 0.97 were screened by differential centrifugation (the average thickness of the inorganic shell was measured by TEM to be 17% of the average particle size of the composite microspheres). 5 parts of composite microspheres, 20 parts of nano-carbon black particles (average particle size 50 nm) and 60 parts of 50% isopropanol solution were mixed to obtain 85 parts of conductive microparticle dispersion.
[0037] The preparation process of the lightweight shielded cable in Comparative Example 1 is the same as that in Example 1.
[0038] Comparative Example 2, by weight, the preparation process of the composite microspheres in Comparative Example 2 includes: S10: Dispersing 1 part of carboxyl / aldehyde bifunctionalized microspheres into 50 parts of deionized water to obtain a carboxyl / aldehyde bifunctionalized microsphere dispersion, and introducing the carboxyl / aldehyde bifunctionalized microsphere dispersion into a constant temperature stirring device for later use, setting the temperature to 70℃ and the stirring speed to 200 rpm; S11: Mixing silver nitrate solution and ammonia water to obtain a silver ammonia solution (the amount of silver nitrate powder used is 0.89 parts), and slowly adding the silver ammonia solution dropwise into the constant temperature stirring device in S10 (as the silver ammonia solution is added to the reaction solution, the reaction solution gradually changes color), and continuing the reaction for 0.5 h after the reaction solution no longer changes color; S12: Centrifuging the reaction solution at high speed to obtain a solid product, and washing the solid product multiple times to obtain bifunctionalized microspheres (composite microspheres) with nano-silver particles loaded on the surface.
[0039] The preparation process of the shielding film in Comparative Example 2 is based on Example 1, except that in S20: composite microspheres with an average particle size of 11.5 μm and a polydispersity index of 0.95 were screened by differential centrifugation (the average thickness of the inorganic shell measured by TEM was 16% of the average particle size of the composite microspheres). 5 parts of composite microspheres, 20 parts of nano carbon black particles (average particle size 50 nm) and 60 parts of 50% isopropanol solution were mixed to obtain 85 parts of conductive microparticle dispersion. The preparation process of the lightweight shielded cable in Comparative Example 2 is the same as that in Example 1.
[0040] Referring to GB / T 31723.403-XXXX / 1EC 62153-4-3:2013, the average isolation of the cable in the 10~30MHz, 100~500MHz, and 1~3GHz bands was tested. The average isolation of the lightweight shielded cables of Example 1, Comparative Example 1, and Comparative Example 2 in different bands is as follows:
[0041] Examples 1, 1, and 2 show that the electromagnetic shielding effect of the cable is optimal when the microparticles constituting the composite microsphere shell are nano-iron oxide microparticles and nano-silver microparticles.
[0042] 2. Examples 2 and 3 regarding the mass ratio of (the nano-iron oxide particles and nano-silver particles constituting the shell of the composite microspheres)
[0043] The preparation process of the composite microspheres in Example 2, by weight, includes: S10: Dispersing 1 part of carboxyl / aldehyde bifunctionalized microspheres in 30 parts of deionized water to obtain a bifunctionalized microsphere dispersion, and introducing the bifunctionalized microsphere dispersion into a constant temperature sealed stirring device equipped with a pH meter for later use. The temperature is set at 43°C and the stirring speed is 230 rpm; S11: Mixing 0.262 parts of ferrous sulfate heptahydrate and 25 parts of deionized water and introducing the mixture into the constant temperature sealed stirring device of S10, and adding a pH adjuster to adjust the pH of the reaction solution to 4; S12: Adding ammonia water dropwise to the reaction solution until the pH of the reaction solution is 8.5, at which point the reaction solution turns black; S13: Adjusting the reaction solution to neutral using a pH adjuster and continuing the reaction for 1 hour; S14: Centrifuging the reaction solution at high speed to obtain a solid product, and washing the solid product multiple times. The following steps were performed: S15: 1 part of magnetic core-shell microspheres were dispersed in 50 parts of deionized water to obtain a magnetic core-shell microsphere dispersion. The magnetic core-shell microsphere dispersion was then introduced into a constant temperature stirring device for later use. The temperature was set at 70℃ and the stirring speed at 200 rpm. S16: Silver nitrate solution and ammonia water were mixed to obtain a silver ammonia solution (the amount of silver nitrate powder was 0.628 parts). The silver ammonia solution was slowly added dropwise to the constant temperature stirring device in S15 (as the silver ammonia solution was added to the reaction solution, the reaction solution gradually changed color). After the reaction solution stopped changing color, the reaction was continued for 0.5 h. S17: The reaction solution was centrifuged at high speed to obtain a solid product. The solid product was washed multiple times to obtain bifunctional microspheres (composite microspheres) with nano-iron oxide particles and nano-silver particles loaded on the surface.
[0044] Based on Example 1, the difference in the preparation process of the shielding film in Example 2 is in S20: composite microspheres with an average particle size of 10.8 μm and a polydispersity index of 0.93 were screened by differential centrifugation (the mass ratio of nano-iron oxide particles and nano-silver particles was 1:5.5 as determined by thermogravimetric analysis, and the average thickness of the inorganic shell was 18% of the average particle size of the composite microspheres as determined by TEM). 5 parts of composite microspheres, 20 parts of nano-carbon black particles (average particle size 50 nm) and 60 parts of 50% isopropanol solution were mixed to obtain 85 parts of conductive microparticle dispersion.
[0045] The preparation process of the lightweight shielded cable in Example 2 is the same as that in Example 1.
[0046] Example 3
[0047] The preparation process of the composite microspheres in Example 3, by weight, includes: S10: Dispersing 1 part of carboxyl / aldehyde bifunctionalized microspheres in 30 parts of deionized water to obtain a bifunctionalized microsphere dispersion, and introducing the bifunctionalized microsphere dispersion into a constant temperature sealed stirring device equipped with a pH meter for later use. The temperature is set at 43°C and the stirring speed is 230 rpm; S11: Mixing 0.346 parts of ferrous sulfate heptahydrate and 25 parts of deionized water and introducing the mixture into the constant temperature sealed stirring device of S10, and adding a pH adjuster to adjust the pH of the reaction solution to 4; S12: Adding ammonia water dropwise to the reaction solution until the pH of the reaction solution is 8.5, at which point the reaction solution turns black; S13: Adjusting the reaction solution to neutral using a pH adjuster and continuing the reaction for 1 hour; S14: Centrifuging the reaction solution at high speed to obtain a solid product, and washing the solid product multiple times. The following steps were performed: S15: 1 part of magnetic core-shell microspheres were dispersed in 50 parts of deionized water to obtain a magnetic core-shell microsphere dispersion. The magnetic core-shell microsphere dispersion was then introduced into a constant temperature stirring device for later use. The temperature was set at 70℃ and the stirring speed was 200 rpm. S16: Silver nitrate solution and ammonia water were mixed to obtain a silver ammonia solution (the amount of silver nitrate powder was 0.544 parts). The silver ammonia solution was slowly added dropwise to the constant temperature stirring device in S15 (as the silver ammonia solution was added to the reaction solution, the reaction solution gradually changed color). After the reaction solution stopped changing color, the reaction was continued for 0.5 h. S17: The reaction solution was centrifuged at high speed to obtain a solid product. The solid product was washed multiple times to obtain bifunctional microspheres (composite microspheres) with nano-iron oxide particles and nano-silver particles loaded on the surface.
[0048] The preparation process of the shielding film in Example 3 is based on Example 1, except that in S20: composite microspheres with an average particle size of 11.3 μm and a polydispersity index of 0.94 were screened by differential centrifugation (the mass ratio of nano-iron oxide particles and nano-silver particles was 1:3.6 as measured by thermogravimetric analysis, and the average thickness of the inorganic shell was 14% of the average particle size of the composite microspheres as measured by TEM). 5 parts of composite microspheres, 20 parts of nano-carbon black particles (average particle size 50 nm) and 60 parts of 50% isopropanol solution were mixed to obtain 85 parts of conductive microparticle dispersion.
[0049] The preparation process of the lightweight shielded cable in Example 3 is the same as that in Example 1.
[0050] The performance test results of the lightweight shielded cables in Examples 2 and 3 are as follows:
[0051] The results of Examples 1, 2, and 3 show that when the mass ratio of the nano-iron oxide particles and nano-silver particles constituting the composite microsphere shell is within the preferred range, the electromagnetic shielding effect of the cable is better.
[0052] 3. Examples 4 and 5 regarding the loading of nano-iron oxide microspheres onto the surface of carboxyl / aldehyde bifunctionalized microspheres using a co-precipitation method. Example 4
[0053] The preparation process of the composite microspheres in Example 4 is based on Example 1, except that in S10: 1 part of carboxyl / aldehyde bifunctional microspheres is dispersed in 30 parts of deionized water to obtain a bifunctional microsphere dispersion. The bifunctional microsphere dispersion is then introduced into a constant temperature sealed stirring device equipped with a pH meter for later use. The temperature is set at 37°C and the stirring speed is 230 rpm.
[0054] In Example 5, the preparation process of the composite microspheres was based on that of Example 1, except that in S10: 1 part of carboxyl / aldehyde bifunctional microspheres was dispersed in 30 parts of deionized water to obtain a bifunctional microsphere dispersion. The bifunctional microsphere dispersion was then introduced into a constant temperature sealed stirring device equipped with a pH meter for later use. The temperature was set at 47°C and the stirring speed was 230 rpm.
[0055] The performance test results of the lightweight shielded cables in Examples 4 and 5 are as follows:
[0056] Compared to Examples 4 and 5, the improved electromagnetic shielding performance of Example 1 may be due to the fact that a larger surface area of the iron(III) oxide on the composite microspheres results in more sufficient contact with electromagnetic waves, thus facilitating their absorption. When the temperature of the coprecipitation system is too low, the nano-iron(III) oxide particles formed on the surface of the composite microspheres are too small, have high surface energy, and are prone to agglomeration (they cannot be dispersed at intervals on the surface of the composite microspheres), resulting in a smaller total area for electromagnetic wave absorption. When the temperature of the coprecipitation system is too high, the nano-iron(III) oxide grains grow rapidly, and the specific surface area decreases rapidly, reducing the total area for electromagnetic wave absorption.
[0057] 4. Examples 6, 7, 8, 9, 10, and 11 regarding the shielding layer. Example 6
[0058] Based on Example 1, the difference lies in the preparation process of the lightweight shielded cable in Example 6, which includes: S30: using an extrusion insulation process to wrap silicone rubber on the surface of a stranded conductive core wire with a diameter of 0.45 mm (forming an insulation layer); S31: using a wrapping machine to wrap a 60 μm thick aluminum-plastic composite tape on the surface of the insulation layer (the aluminum layer of the aluminum-plastic composite tape forms a metal foil layer); S32: using a wrapping machine to wrap a shielding film on the surface of the metal foil layer (forming a first modified shielding layer); S33: using a wrapping machine to wrap a shielding film on the surface of the first modified shielding layer (forming a second modified shielding layer); S34: using an extrusion insulation process to wrap cross-linked polyethylene on the surface of the second modified shielding layer (forming a 0.7 mm thick surface layer).
[0059] Example 7 is based on Example 6, except that the lightweight shielded cable of Example 7 includes a first shielding film and a second shielding film. The first shielding film forms a first modified shielding layer, and the second shielding film forms a second modified shielding layer. The second shielding film uses the same shielding film as in Example 1. The preparation process of the first shielding film is based on the second shielding film. The composite microspheres used in the first shielding film have the following specifications: an average particle size of 0.3 μm and a polydispersity index of 0.89.
[0060] Example 8 is based on Example 6, except that the first shielding film in Example 8 uses the same shielding film as in Example 1. The preparation process of the second shielding film is based on the first shielding film, and the specifications of the composite microspheres used in the second shielding film are: average particle size of 0.3 μm and polydispersity index of 0.89.
[0061] Example 9 is based on Example 7, except that the first shielding film in Example 9 uses composite microspheres with an average particle size of 3 μm and a polydispersity index of 0.92.
[0062] Example 10 is based on Example 7, except that the first shielding film in Example 10 uses composite microspheres with an average particle size of 5.5 μm and a polydispersity index of 0.95.
[0063] Example 11 is based on Example 9, except that the composite microspheres used in the second shielding film of Example 11 have the following specifications: average particle size of 11.7 μm and polydispersity index of 0.6.
[0064] Example 12 is based on Example 9, except that the composite microspheres used in the second shielding film of Example 12 have the following specifications: average particle size of 10.8 μm and polydispersity index of 0.05.
[0065] The performance test results of the lightweight shielded cables in Examples 6-12 are as follows:
[0066] Among Examples 6-12, the reason why Example 11 exhibits the best shielding performance may be that the conductive particles of the first and second shielding layers form a double-layer shielding network. Electromagnetic waves entering the double-layer shielding network are reflected and continuously absorbed between the first and second shielding layers. The average particle size and polydispersity index of the composite microspheres both affect the contact area between the double-layer shielding network and the electromagnetic waves, and also influence the reflection path of the electromagnetic waves within the double-layer shielding network. In Example 11, the average particle size and polydispersity index of the composite microspheres are both within the preferred range, resulting in the optimal effect of the double-layer shielding network in reflecting and absorbing electromagnetic waves.
[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A lightweight shielded cable, comprising, from the inside out, a core wire, an insulation layer, a metal foil layer, a modified shielding layer, and a surface layer, wherein the modified shielding layer is a glass fiber cloth impregnated with a conductive adhesive, the conductive adhesive comprising an adhesive and conductive particles dispersed in the adhesive, the conductive particles being interconnected to form conductive channels, the conductive particles comprising composite microspheres with a core-shell structure, the core of the composite microspheres being a polymer microsphere, and the outer shell of the composite microspheres being an inorganic material, characterized in that... The outer shell is composed of nano-iron oxide particles and nano-silver particles.
2. The lightweight shielded cable according to claim 1, characterized in that, The mass ratio of the nano-iron oxide particles to the nano-silver particles is 1:(4~5).
3. The lightweight shielded cable according to claim 1, characterized in that, The polymer microspheres are polystyrene microspheres.
4. The lightweight shielded cable according to claim 1, characterized in that, The modified shielding layer includes a first modified shielding layer and a second modified shielding layer stacked sequentially; the composite microspheres include a first composite microsphere and a second composite microsphere, wherein the average particle size of the first composite microsphere is 0.5~4.5μm and the average particle size of the second composite microsphere is 5~20μm; one of the first composite microsphere and the second composite microsphere is disposed in the first modified shielding layer, and the other of the first composite microsphere and the second composite microsphere is disposed in the second modified shielding layer.
5. The lightweight shielded cable according to claim 4, characterized in that, The polydispersity index of the first composite microsphere is 0.8~1, and the polydispersity index of the second composite microsphere is 0.1~0.
7.
6. The lightweight shielded cable according to claim 1, characterized in that, The average thickness of the outer shell is 10% to 20% of the average particle size of the composite microspheres.
7. The lightweight shielded cable according to claim 1, characterized in that, The conductive microparticles also include carbon black nanoparticles, the average particle size of which is 30-80 nm, and the mass ratio of the composite microspheres to the carbon black nanoparticles in the conductive microparticles is 1:(3-5).
8. A method for preparing a lightweight shielded cable, characterized in that, The lightweight shielded cable according to any one of claims 1 to 7 comprises the following steps: S00: preparing modified polystyrene microspheres by dispersion polymerization, wherein the functional groups of the polystyrene microspheres include carboxyl and aldehyde groups; S01: loading nano-iron oxide particles onto the surface of the polystyrene microspheres by co-precipitation; S02: loading nano-silver particles onto the surface of the polystyrene microspheres by reduction polymerization to obtain composite microspheres; S03: mixing the dispersion of composite microspheres, nano-carbon black particles and adhesive to obtain conductive adhesive; S04: impregnating and drying aminosilane-modified glass fiber cloth into the conductive adhesive to obtain a shielding film.
9. The method for preparing the lightweight shielded cable according to claim 8, characterized in that, In S03, the mass ratio of the dispersion to the adhesive is 85:(17~40); the mass ratio of the conductive particles to the dispersant in the dispersion is 25:(45~70); and the solid content of the adhesive is 40%~50%.
10. The method for preparing the lightweight shielded cable according to claim 8, characterized in that, The reaction temperature for the S01 co-precipitation method is 40~45℃.