Foamed silicon dioxide insulating high-fidelity communication coaxial cable and preparation method thereof

Abstract

The invention relates to a foamed silicon dioxide insulated high-fidelity communication coaxial cable and a preparation method thereof, the foamed silicon dioxide insulated high-fidelity communication coaxial cable comprises an inner conductor, an insulating layer distributed outside the inner conductor, an outer conductor distributed outside the insulating layer, a sheath distributed outside the outer conductor, and the insulating layer is composed of foamed silicon dioxide hollow microspheres with purity of more than or equal to 99.8%. The dielectric constant of the foamed silicon dioxide hollow microbeads is 1.45-1.65, and the foaming degree is 55%-65%; the closed porosity of the foamed silicon dioxide hollow microspheres is greater than or equal to 90%, the surface hydroxyl content is less than or equal to 0.5 wt%, and the fitting gap between the foamed silicon dioxide hollow microspheres and the inner conductor is less than or equal to 0.1 mu m. In the preparation period, a vibration platform with the amplitude of 0.1-2 mm and the frequency of 20-200 Hz is adopted for filling the foamed silicon dioxide hollow microspheres. Therefore, high-fidelity communication can be achieved, the overall electrical performance and environmental adaptability are high, and the protection and heat dissipation requirements during use are met.

Description

Technical Field

[0001] The present invention relates to a cable and a preparation method thereof, and particularly to a foamed silica insulated high-fidelity communication coaxial cable and a preparation method thereof. Background Art

[0002] In combination with the existing technology, coaxial cables, as a commonly used wire and signal transmission line, are widely used in the fields of analog signal and digital signal transmission, such as television transmission, long-distance telephone transmission, short-distance connection of computer systems, and local area networks. Its development has gone through multiple stages from using polyethylene materials as solid core insulation media to chemically foamed, lotus core longitudinal hole, and physically foamed PE materials as insulation media.

[0003] For example, the Chinese patent with the authorization announcement number CN222145871U discloses a simple coaxial cable, which has the advantages of low overall cost, simple process, and good attenuation performance through specific structural settings. Another example is the ultra-high-definition video signal transmission coaxial cable disclosed in the Chinese patent with the authorization announcement number CN211957251U, which has the characteristics of high compressive strength and long service life.

[0004] At the same time, the prior art CN118782290A discloses a graded silica powder as the insulating material of the cable. The cable preparation method it adopts is: positioning the center conductor and the outer conductor, filling the silica powder, and drawing and forming. However, it does not disclose the implementation method of filling, and the insulating silica used is solid silica, and the graded method is used to achieve the low dielectric insulation method. During actual use, the effect of low dielectric insulation is not good and cannot meet the requirements of high-frequency high-fidelity communication.

[0005] Therefore, the current coaxial cables still have deficiencies in high-frequency high-fidelity communication. For example, when the frequency exceeds 20 GHz, the standing wave ratio of some coaxial cables will increase significantly, resulting in an increase in the transmission error rate and making it difficult to meet the requirements of high-quality communication. At the same time, in terms of insulation performance, it is difficult for the existing insulation materials and structures to simultaneously achieve a low dielectric constant and a uniform dielectric distribution, which affects the fidelity of signal transmission. In addition, there is also room for improvement in the working temperature range, precise control of characteristic impedance, and adaptation to special environments (such as high temperature, high electromagnetic interference, etc.) of the existing coaxial cables.

[0006] In view of the above-mentioned defects, the present inventor has actively carried out research and innovation in order to create a foamed silica insulated high-fidelity communication coaxial cable and a preparation method thereof, making it more valuable in industrial applications. Summary of the Invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a foamed silica insulated high-fidelity communication coaxial cable and a preparation method thereof.

[0008] A foamed silica insulated high-fidelity communication coaxial cable of the present invention includes an inner conductor, wherein: an insulating layer is distributed outside the inner conductor, an outer conductor is distributed outside the insulating layer, and a sheath is distributed outside the outer conductor. The insulating layer is composed of foamed silica hollow microspheres with a purity ≥ 99.8%. The dielectric constant of the foamed silica hollow microspheres is 1.45 to 1.65, and the foaming degree is 55% to 65%. The closed cell rate of the foamed silica hollow microspheres ≥ 90%, the surface hydroxyl content ≤ 0.5 wt%, and the fitting gap with the inner conductor ≤ 0.1 μm.

[0009] Further, in the above-mentioned foamed silica insulated high-fidelity communication coaxial cable, the inner conductor and the outer conductor can be independently selected from one or a combination of copper conductors, coated copper conductors, and pure nickel conductors.

[0010] Even further, in the above-mentioned foamed silica insulated high-fidelity communication coaxial cable, the outer conductor has a tubular structure, and the surface roughness Ra of the tubular structure ≤ 0.8 μm; the tolerance of the tubular structure is within ± 0.05 mm.

[0011] Even further, in the above-mentioned foamed silica insulated high-fidelity communication coaxial cable, the sheath is a stainless steel layer or a titanium alloy layer, and the outer surface of the sheath is treated by a passivation process.

[0012] Even further, in the above-mentioned foamed silica insulated high-fidelity communication coaxial cable, a silica fiber braided layer is distributed between the sheath and the outer conductor. The braiding density of the silica fiber braided layer ≥ 80 meshes per inch; the surface of the silica fiber braided layer is coated with a silica coating.

[0013] A preparation method of a foamed silica insulated high-fidelity communication coaxial cable of the present invention is characterized by including the following steps: Step 1, screening treatment of foamed silica hollow microspheres: a. Screen the foamed silica hollow microspheres through a molecular sieve to separately screen out small particle microspheres and large particle microspheres. The diameter of the small particle microspheres is 50 ± 10 nm, and the diameter of the large particle microspheres is 200 ± 10 nm; b. Mix the small particle microspheres and the large particle microspheres, and the ratio of the small particle microspheres to the large particle microspheres is 2:1 to 3:1; c. Add anhydrous alcohol and stir and wash the mixed small particle microspheres and large particle microspheres; d. Dry the mixed small particle microspheres and large particle microspheres for standby; Step 2, fix the inner conductor, the outer conductor, and the sheath through a mold respectively, and make the inner conductor and the outer conductor be distributed in a concentric circle state; Step 3: Fill the hollow silica microspheres with a vibration platform having an amplitude of 0.1 to 2 mm and a frequency of 20 to 200 Hz. Step 4: After filling, use a drawing device to form the cable by multiple precision cold drawing methods.

[0014] Furthermore, in the preparation method of the foamed silica insulated high-fidelity communication coaxial cable described above, in Step 1, the purity of anhydrous alcohol is 99.8%. By stirring the small particle microspheres and large particle microspheres, the surface impurities of the small particle microspheres and large particle microspheres are removed; the mixed small particle microspheres and large particle microspheres are placed in a container and dried at an environmental temperature of 600°C ± 50°C for 8 h, and then taken out after natural cooling.

[0015] Even further, in the preparation method of the foamed silica insulated high-fidelity communication coaxial cable described above, in Step 4, the compression ratio of the drawing device is 1.2:1 to 1.5:1.

[0016] Even further, in the preparation method of the foamed silica insulated high-fidelity communication coaxial cable described above, during the drawing in Step 4, the number of drawing times is controlled as needed to maintain effective drawing accuracy, so that the compression ratio of each drawing does not exceed 1.05:1.

[0017] Even further, in the preparation method of the foamed silica insulated high-fidelity communication coaxial cable described above, the hollow silica microspheres are subjected to hydrophobic treatment.

[0018] By means of the above solution, the present invention has at least the following advantages: 1. High-fidelity communication can be achieved. By using specific hollow silica microspheres as the insulating layer material, due to their low dielectric constant and uniform dielectric distribution characteristics, the high-frequency signal transmission fidelity of the cable is significantly improved. Even when operating in the high-frequency band, it can effectively suppress the growth of the standing wave ratio and reduce the transmission error rate. Compared with existing coaxial cables, it can achieve more stable and accurate signal transmission.

[0019] 2. The overall electrical performance and environmental adaptability are strong. By improving the anti-leakage and buffering effects of the entire cable, the cable can operate stably within a very wide temperature range, and at the same time, the characteristic impedance is accurately controlled. Compared with existing products, the applicable temperature range of operation is broadened, the stability of electrical performance is improved, and it can calmly cope with more complex environments.

[0020] 3. High overall preparation precision. The outer conductor adopts a specific tubular structure, reasonably controlling the surface roughness and tolerance, which not only avoids the cracking risk caused by uneven stress but also facilitates the die positioning and the filling of insulating materials, improving the processing convenience and the product yield. In addition, the structural ratio of the insulating layer and the inner conductor is reasonably designed, optimizing the overall structure while ensuring the insulation effect.

[0021] 4. The insulating layer has good stability, with excellent foaming degree and dielectric constant. Small particle microbeads and large particle microbeads are used in combination. The large particle microbeads can form a structure, and the small particle microbeads fill the gaps between the structures, making it form a complete insulating layer. It can meet the necessary stress support and will not show looseness or collapse.

[0022] 5. The preparation method is efficient and reliable. Through process steps such as precise die positioning, vibration-assisted filling, and multiple precision cold drawing, it ensures that the insulating material is filled in place and forms a good combination with the overall cable. Compared with the traditional preparation process, this method effectively improves the production efficiency and the product quality stability, which is conducive to the large-scale production of high-performance coaxial cables.

[0023] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following takes the preferred embodiments of the present invention and combines with the drawings to describe in detail as follows. Brief Description of the Drawings

[0024] Figure 1 It is a schematic cross-sectional structure diagram of a foamed silica insulated high-fidelity communication coaxial cable.

[0025] The meanings of the reference numerals in the drawings are as follows.

[0026] Detailed Description of the Embodiments The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0027] Such as Figure 1A foamed silica insulated high-fidelity communication coaxial cable, including an inner conductor 1, is characterized in that: an insulating layer 2 is distributed outside the inner conductor 1, an outer conductor 3 is distributed outside the insulating layer 2, and a sheath 4 is distributed outside the outer conductor 3, presenting an overall laminated wrapping state. Thus, a composite structure is adopted to protect the inner conductor 1. At the same time, in order to meet a better dielectric constant and achieve effective high-frequency high-fidelity communication, the insulating layer 2 is composed of foamed silica hollow microspheres with a purity ≥ 99.8%. The dielectric constant of the foamed silica hollow microspheres is 1.45 to 1.65, and the foaming degree is 55% to 65%. Since the foamed silica hollow microspheres are all at the nanoscale, they closely and evenly fit with the inner conductor 1. The insulation of low dielectric superposed with uniform medium can ensure that the cable has high-fidelity characteristics. During use, even when the frequency exceeds 20 GHz, the standing wave ratio will not increase significantly, effectively reducing the bit error rate during transmission. Of course, from a more optimized implementation method, the dielectric constant of the silica hollow microspheres after preparation can reach 1.5, and the foaming degree is 60%.

[0028] During implementation, in order to improve the anti-electric leakage and buffering effects of the foamed silica hollow microspheres, the closed cell rate of the foamed silica hollow microspheres ≥ 90%, the surface hydroxyl content ≤ 0.5 wt%, and the fitting gap with the inner conductor 1 ≤ 0.1 μm. Thus, the operating temperature range of the coaxial cable is -200°C to 650°C, and the characteristic impedance is 50Ω ± 2Ω. Furthermore, for the protection need of insulation, the ratio of the thickness of the insulating layer 2 to the diameter of the inner conductor 1 is 1:1.5 to 1:3.

[0029] Combined with a preferred implementation mode of the present invention, in order to achieve good signal transmission, the inner conductor 1 and the outer conductor 3 adopted can be independently selected from one or a combination of a copper conductor, a plated copper conductor, and a pure nickel conductor. At the same time, the outer conductor 3 has a tubular structure, and the surface roughness Ra of the tubular structure ≤ 0.8 μm. Avoiding the existence of rough parts causes uneven stress bearing and cracking in the follow-up. At the same time, the tolerance of the tubular structure is within ±0.05 mm. Thus, it adapts to the mold positioning and is convenient for the effective filling and pouring of the foamed silica hollow microspheres during processing.

[0030] Furthermore, in order to achieve effective isolation and protection, the sheath 4 adopted is a stainless steel layer or a titanium alloy layer. At the same time, and for some special use requirements, the sheath 4 can also adopt other composite structures such as other alloy layers, which will not be elaborated here. Moreover, the outer surface of the sheath 4 can be passivated.

[0031] Furthermore, in order to meet the high-temperature usage requirements of certain components, a silica fiber braided layer is distributed between the 4th layer of the sheath and the outer conductor 3, and the braiding density of the silica fiber braided layer is ≥ 80 meshes per inch. Considering the improvement of the high-temperature protection effect, the surface of the silica fiber braided layer is coated with a silica coating.

[0032] To better implement the present invention, a method for preparing a foamed silica-insulated high-fidelity communication coaxial cable is provided, which includes the following steps: Step 1, screening and processing of foamed silica hollow microspheres. In order to make the foamed silica hollow microspheres have a dielectric constant of 1.5 after subsequent forming and ensure that at least 60% of the foaming degree can be satisfied, the following process can be used to complete the screening and processing.

[0033] First, the foamed silica hollow microspheres are screened through a molecular sieve to separately screen out small-particle microspheres and large-particle microspheres. The diameter of the small-particle microspheres is 50 ± 10 nm, and the diameter of the large-particle microspheres is 200 ± 10 nm. In this way, the diameter distribution of a conventional coaxial cable can be satisfied, which is convenient for effective filling and will not cause slight bulging of the outer conductor during subsequent drawing processing.

[0034] After that, the small-particle microspheres and the large-particle microspheres are mixed, and the ratio of the small-particle microspheres to the large-particle microspheres is 2:1 to 3:1. In this way, it can be ensured that the space reserved in the insulating layer can be fully filled by the foamed silica hollow microspheres without gaps. At the same time, relying on the mutual extrusion of the non-equal-diameter small-particle microspheres and large-particle microspheres, the self-stress of self-filling can be realized.

[0035] Subsequently, anhydrous alcohol is added to stir and wash the mixed small-particle microspheres and large-particle microspheres. During this period, in order to ensure the effective mixing of the small-particle microspheres and the large-particle microspheres, sufficient stirring can be carried out without damage. The anhydrous alcohol can effectively remove surface impurities such as dust and oil on the surface of the foamed silica hollow microspheres without affecting subsequent filling. Specifically, the purity of the anhydrous alcohol used is 99.8%. By moderately stirring or soaking the small-particle microspheres and the large-particle microspheres, the surface impurities of the small-particle microspheres and the large-particle microspheres are removed. During implementation, the appropriate purity of anhydrous alcohol can be selected according to the cleanliness of the processing link of the foamed silica hollow microspheres, or a purity of 99% can also be used, which will not be elaborated here.

[0036] Finally, the mixed small-particle microspheres and large-particle microspheres are dried for standby. During processing, they are placed in a container with a lid and dried at an environmental temperature of 600 °C ± 50 °C for 8 h, and then taken out after natural cooling. Of course, during actual processing, the temperature of the link and the drying time can be adjusted according to the size of the current container. Escape holes or escape slits are distributed between the container and the lid to facilitate the evaporation and release of anhydrous alcohol.

[0037] Step 2: Fix the inner conductor 1, outer conductor 3, and sheath 4 respectively through a mold. During the mold positioning, at least ensure that the inner conductor 1 and the outer conductor 3 are distributed in a concentric circle state. In this way, during the subsequent filling, it can be ensured that the finally formed insulating layer 2 presents an equal-diameter annular distribution without deviation or concavity. Thus, the smooth distribution of the foamed silica hollow microspheres is satisfied. Considering the convenience of implementation, the mold can be directly pre-installed on the vibration platform for quick standby.

[0038] Step 3: Set the operating parameters of the vibration platform to an amplitude of 0.1 to 2 mm and a frequency of 20 to 200 Hz. Along with the addition of the foamed silica hollow microspheres, turn on the vibration platform to ensure that the foamed silica hollow microspheres are filled in place. During this period, the appropriate amplitude and frequency can be selected according to the addition amount of the foamed silica hollow microspheres. At the same time, in order to facilitate the better entry of the foamed silica hollow microspheres into the filling space, the funnel for discharging the foamed silica hollow microspheres can form an angle of 30 to 60 degrees with the vibration platform. During this period, due to the non-equal-diameter layout of the small-particle microspheres and large-particle microspheres, the large-particle microspheres can achieve spatial dimension support and positioning, and the small-particle microspheres can fill the gaps. And along with the operation of the vibration platform, the small-particle microspheres and large-particle microspheres have a beneficial contact extrusion with each other, and finally are tightly combined to form a stable insulating layer 2.

[0039] Step 4: After the foamed silica hollow microspheres are filled, use a drawing device to form the cable by means of multiple precision cold drawing. At the same time, the compression ratio of the drawing device is 1.2:1 to 1.5:1 to meet the requirement of non-destructive drawing. Specifically, as a more preferred method, control the number of drawing times as needed during drawing to maintain effective drawing accuracy, so that the compression ratio of each drawing does not exceed 1.05:1. In this way, the final forming of the coaxial cable can be realized, and the small-particle microspheres and large-particle microspheres form the final insulating layer 2 without any looseness during the subsequent cable processing. In some special working environments with high curl or twist of the needle or large waves, even if there is abnormal water vapor infiltration, it can still have an appropriate insulating effect to meet the emergency treatment needs, and the foamed silica hollow microspheres can be subjected to water repellent treatment.

[0040] The above is only the preferred implementation mode of the present invention and is not used to limit the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present invention, several improvements and modifications can still be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A foamed silica insulated high-fidelity communication coaxial cable, comprising an inner conductor, characterized in that: An insulating layer is distributed outside the inner conductor, an outer conductor is distributed outside the insulating layer, and a sheath is distributed outside the outer conductor. The insulating layer is composed of foamed silica hollow microspheres with a purity ≥ 99.8%. The dielectric constant of the foamed silica hollow microspheres is 1.45 to 1.65, and the foaming degree is 55% to 65%. The closed cell rate of the foamed silica hollow microspheres is ≥ 90%, the surface hydroxyl content is ≤ 0.5 wt%, and the fitting gap with the inner conductor is ≤ 0.1 μm.

2. The foamed silica insulated high-fidelity communication coaxial cable according to claim 1, wherein: The inner conductor and the outer conductor can be independently selected from one or a combination of copper conductors, coated copper conductors, and pure nickel conductors.

3. A foamed silica insulated high-fidelity communication coaxial cable according to claim 1, characterized in that: The outer conductor has a tubular structure, and the surface roughness Ra of the tubular structure is ≤ 0.8 μm. The tolerance of the tubular structure is within ± 0.05 mm.

4. A foamed silica insulated high-fidelity communication coaxial cable according to claim 1, characterized in that: The sheath is a stainless steel layer or a titanium alloy layer, and the outer surface of the sheath is treated by a passivation process.

5. A foamed silica insulated high-fidelity communication coaxial cable according to claim 1, characterized in that: A silica fiber braided layer is distributed between the sheath and the outer conductor. The braiding density of the silica fiber braided layer is ≥ 80 meshes per inch. The surface of the silica fiber braided layer is coated with a silica coating.

6. A preparation method of a foamed silica insulated high-fidelity communication coaxial cable, characterized in that It includes the following steps: Step 1, screening treatment of foamed silica hollow microspheres; a. Through a molecular sieve, the foamed silica hollow microspheres are screened to separately screen out small particle microspheres and large particle microspheres. The diameter of the small particle microspheres is 50 ± 10 nm, and the diameter of the large particle microspheres is 200 ± 10 nm. b. The small particle microspheres and the large particle microspheres are mixed, and the ratio of the small particle microspheres to the large particle microspheres is 2:1 to 3:

1. c. Absolute ethanol is added, and the mixed small particle microspheres and large particle microspheres are stirred and washed. d. The mixed small particle microspheres and large particle microspheres are dried for standby. Step 2, the inner conductor, the outer conductor, and the sheath are respectively fixed by a mold, and the inner conductor and the outer conductor are distributed in a concentric state. Step 3, on a vibration platform with an amplitude of 0.1 to 2 mm and a frequency of 20 to 200 Hz, the foamed silica hollow microspheres are filled. Step 4, after filling, a drawing device is used to form the cable by multiple precision cold drawing methods.

7. The preparation method of a foamed silica insulated high-fidelity communication coaxial cable according to claim 6, characterized in that: In Step 1, the purity of the absolute ethanol is 99.8%. By stirring the small particle microspheres and the large particle microspheres, the surface impurities of the small particle microspheres and the large particle microspheres are removed. The mixed small particle microspheres and large particle microspheres are placed in a container, dried at an environmental temperature of 600 °C ± 50 °C for 8 h, and taken out after natural cooling.

8. The preparation method of a foamed silica insulated high-fidelity communication coaxial cable according to claim 6, characterized in that: In the said Step 4, the compression ratio of the drawing device is 1.2:1 to 1.5:

1.

9. The preparation method of a foamed silica insulated high-fidelity communication coaxial cable according to claim 6, wherein: During the drawing in Step 4, the number of draws is controlled as needed to maintain effective drawing accuracy, so that the compression ratio of each draw does not exceed 1.05:

1.

10. The preparation method of a foamed silica insulated high-fidelity communication coaxial cable according to claim 6, characterized in that: The foamed silica hollow microspheres are subjected to a hydrophobic treatment.

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