Conductive glass fiber and preparation method thereof

Abstract

The invention provides a conductive glass fiber and a preparation method thereof, and belongs to the technical field of fiber materials. The conductive glass fiber includes: a glass fiber core; the MOF-CNT transition layer is coated on the surface of the inner core; the gradient copper-graphene nanosheet conductive shell layer covers the transition layer, the copper content increases progressively from inside to outside, and the graphene nanosheet content decreases progressively; and the hydrophobic packaging layer is coated outside the conductive shell layer. The MOF-CNT transition layer in the conductive glass fiber enhances the binding force between the inner core and the conductive shell layer, and graphene nanosheets in the gradient copper-graphene nanosheet conductive shell layer have excellent electrical properties and high specific surface area, and have a synergistic effect with copper, so that the overall conductivity of the fiber is greatly improved; and the hydrophobic packaging layer at the outermost layer provides good protection for the conductive glass fibers, so that the conductive glass fibers have excellent conductive performance and can stably work in a humid and severe environment.

Description

Technical Field

[0001] This application relates to the field of fiber materials technology, and in particular to a conductive glass fiber and its preparation method. Background Technology

[0002] Glass fiber possesses advantages such as high temperature resistance, corrosion resistance, high tensile strength, and low cost, making it an important material for corrosion resistance, thermal insulation, sound absorption, and flame retardancy. It has significant applications in aerospace, automotive, and electrical industries. Current research on glass fiber mainly focuses on enhancing its mechanical properties. However, with the rapid development of cutting-edge scientific fields such as energy electronics and space technology, the electromagnetic properties of materials are becoming increasingly important. While glass fiber itself is an excellent high-frequency transparent material, it does not yet possess electromagnetic shielding or electrostatic protection properties. Currently, the main approach is to composite glass fiber with carbon materials, which can modify the conductivity and wave absorption / transmission characteristics of glass fiber while retaining its corrosion resistance, low density, and high strength. This allows for applications of glass fiber in antenna filtering, aircraft electromagnetic shielding, and conductive lightning protection. Chemical plating with a metal substrate is currently the main method for preparing conductive glass fibers, but metal plating has inherent drawbacks such as heavy weight and weak interfacial bonding with glass fibers.

[0003] CN112010572A discloses a conductive glass fiber and its preparation method. The method utilizes the "bridging" effect of polytannic acid molecules between a copper layer and a substrate to prepare a copper layer on the surface of the glass fiber. The preparation process involves dispersing the glass fiber in a buffer solution containing tannic acid, and depositing a polytannic acid functional coating on the surface of the glass fiber. Ag + Complexed on its surface, in complexed Ag + Simultaneously, utilizing the autocatalytic effect of these silver nanoparticles, Cu... 2+ The process involves reduction, resulting in a continuous, dense, and robust conductive copper layer on the glass fiber surface, with a resistivity of 0.2-0.9 Ω·cm and a resistivity variation of ≤20%. However, metal plating has inherent defects such as heavy weight and weak interfacial bonding with glass fibers.

[0004] In recent years, carbon nanomaterials have gradually become new functional materials to impart conductive properties to glass fibers due to their excellent conductive properties. For example, CN111593558A discloses a graphene type conductive core-sheath fiber and a preparation method thereof. The core layer of the graphene type conductive core-sheath fiber is polyester, and the sheath layer is a composite material of graphene and optional carbon nanotubes and low-melting polyester. The preparation method comprises: continuously coating a graphene dispersion liquid on the surface of the core-sheath fiber, and adhering the graphene to the surface of the core-sheath fiber by hot pressing to obtain a graphene type conductive core-sheath fiber. The graphene dispersion liquid contains graphene and optional carbon nanotubes. The conductive core-sheath fiber of the patent has strong conductive properties, and the optimal value of the electrical conductivity of the knitted fabric is 13.20 S / m (20℃). Although the nanocarbon material has the advantages of light weight, corrosion resistance, denser coating, and less environmental pollution compared to metal plating, the conductive properties of the material still need to be improved. SUMMARY

[0005] The present application is made in view of the above problems, and aims to provide a conductive glass fiber and a preparation method thereof. The conductive glass fiber has strong interfacial bonding force and good conductive properties.

[0006] Specifically, the first aspect of the present application provides a conductive glass fiber, comprising: a glass fiber core; a MOF-CNT transition layer coated on the surface of the core; a gradient copper-graphene nanoplate conductive shell layer covering the transition layer, wherein the copper content increases from inside to outside, and the graphene nanoplate content decreases; a hydrophobic encapsulation layer coated outside the conductive shell layer.

[0007] Further, the MOF-CNT transition layer is composed of in-situ growth of metal organic framework MOF and coated carbon nanotubes, and the MOF is at least one of zeolitic imidazolate framework ZIF-8 and ZIF-67. Further, the gradient copper-graphene nanoplate conductive shell layer comprises an inner layer region and an outer layer region, wherein: the inner layer region: copper content 45-60 vol%, GNP content 30-40 vol%; the outer layer region: copper content 80-92 vol%, GNP content 5-10 vol%; The volume content of copper in the shell layer continuously increases from inside to outside, and the volume content of GNP continuously decreases.

[0008] Further, the hydrophobic encapsulation layer is a silica aerogel film with a thickness of ≤200 nm.

[0009] The second aspect of the present application provides a preparation method of the conductive glass fiber, comprising the following steps: (a) performing oxygen plasma etching pretreatment on the glass fiber; (b) constructing a MOF-CNT transition layer on the surface of the pretreated fiber; (c) gradient depositing a copper-graphene nanosheet conductive shell layer on the transition layer; (d) forming a hydrophobic encapsulation layer outside the conductive shell layer. Further, in step (a), the oxygen plasma etching gas is O2 and Ar, and the volume ratio of O2 to Ar is (5-7):(3-5); and / or The power density is 1.0-2.0 W / cm 2 ; and / or The treatment time is 3-8 min.

[0010] Further, step (b) specifically comprises: (b1) immersing the etched glass fiber into a CNT dispersion liquid, wherein the CNT concentration in the dispersion liquid is 0.3-0.8 wt%, and the dispersant is polydopamine; (b2) placing the glass fiber treated in step (b1) in a zinc ion solution and 2-methylimidazole vapor environment, and the reaction temperature is 50-70°C, and the reaction time is 15-25 min, to generate a composite structure of ZIF-8 coated CNT.

[0011] Further, the method of step (c) for gradient depositing a copper-graphene nanosheet conductive shell layer on the transition layer comprises: (c1) electrophoretic deposition of a GNP-rich inner layer: in a suspension containing 10-15 g / L of GNP, a direct current voltage of 15-25 V is applied, and the deposition time is 20-40 s; (c2) pulse electrodeposition of a gradient transition layer: in an electrolyte containing Cu 2+ 0.5-1.0 M and GNP 3-5 g / L, a pulse current is used, the on-time is 8-12 ms, the off-time is 4-6 ms, and the current density is 15-25 A / dm 2 ; (c3) pulse electrodeposition of a copper-rich outer layer: in an electrolyte containing Cu 2+ 1.0-1.5 M, a pulse current is used, the on-time is 13-17 ms, the off-time is 2-4 ms, and the current density is 22-28 A / dm 2 .

[0012] Further, the electrolyte in steps (c2) and (c3) both contains a citric acid complexing agent, and the concentration is 0.5-1.0 M, and the pH value is 2.5-3.5.

[0013] Further, step (d) uses a vapor deposition method to make the hexamethyldisilazane vapor react with the fiber surface at 120-180 DEG C for 5-15 min to form a SiO2 aerogel encapsulation layer.

[0014] The present application has the following beneficial effects: The conductive glass fiber has a unique layered structure, wherein the glass fiber core serves as a basic structure, retaining the advantages of the glass fiber itself, such as high temperature resistance, corrosion resistance, high tensile strength, and low cost; the MOF-CNT transition layer is composed of in-situ growth of metal organic framework MOF and coating of carbon nanotubes, and the MOF is at least one of zeolitic imidazolate framework ZIF-8 and ZIF-67. This transition layer can enhance the interfacial bonding force between the glass fiber core and the gradient copper-graphene nanosheet conductive shell layer. Since the MOF has a porous structure and abundant active sites, it can produce strong interaction with the components on the surface of the glass fiber and the conductive shell layer, thereby avoiding the problem of weak interfacial bonding of traditional metal plating layers.

[0015] The gradient copper-graphene nanosheet conductive shell layer has an increasing copper content and a decreasing graphene nanosheet content from the inside to the outside, and is divided into an inner layer region and an outer layer region. This gradient distribution enables the conductive shell layer to have good conductivity while meeting different performance requirements. The inner layer is rich in graphene nanosheets, which have excellent conductivity, flexibility, and chemical stability, and can enhance the bonding force between the conductive shell layer and the transition layer while ensuring the conductivity; and the outer layer is rich in copper, which is an excellent conductor, and a higher copper content can further improve the overall conductivity of the conductive glass fiber to meet the high requirements for material conductivity in the fields of energy electronics and space technology.

[0016] The hydrophobic encapsulation layer is a silica aerogel film, which can effectively protect the conductive glass fiber, making it have good waterproof and moisture-proof performance, and avoiding the erosion of water and moisture in the external environment on the conductive shell layer and the transition layer, thereby prolonging the service life of the conductive glass fiber and improving its stability and reliability in complex environments. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the drawings, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 It is a structural schematic diagram of the conductive glass fiber.

[0019] The following items are explained in the drawings: 1, core; 2, transition layer; 3, conductive shell layer; 4, hydrophobic encapsulation layer.

[0020] The purposes, functional features and advantages of the drawings will be further explained with reference to the drawings in combination with embodiments. DETAILED DESCRIPTION

[0021] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be described and explained in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0022] Obviously, the following description is only some examples or embodiments of the present application, and for those of ordinary skill in the art, the present application can also be applied to other similar scenarios without creative labor. In addition, it can be understood that although the efforts made in this development process can be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacture or production changes based on the technical content disclosed in the present application are only routine technical means and should not be understood as insufficient disclosure of the present application.

[0023] Embodiments of the first aspect of the present application provide a conductive glass fiber, comprising: a glass fiber core 1; a MOF-CNT transition layer 2 coated on the surface of the core 1; a gradient copper-graphene nanosheet conductive shell layer 3 covering the transition layer 2, wherein the copper content increases from inside to outside, and the graphene nanosheet content decreases; a hydrophobic encapsulation layer 4 coated outside the conductive shell layer 3.

[0024] The conductive glass fiber has a unique layered structure, wherein the glass fiber core 1 serves as a basic structure and retains the advantages of the glass fiber itself, such as high temperature resistance, corrosion resistance, high tensile strength, and low cost; the MOF-CNT transition layer 2 is composed of in-situ growth of a metal organic framework MOF and coated carbon nanotubes, and the MOF is at least one of zeolitic imidazolate frameworks ZIF-8 and ZIF-67. The transition layer 2 can enhance the interfacial bonding force between the glass fiber core 1 and the gradient copper-graphene nanosheet conductive shell layer 3. Since the MOF has a porous structure and rich active sites, it can produce strong interaction with the components on the surface of the glass fiber and in the conductive shell layer 3, thereby avoiding the problem of weak interfacial bonding of the traditional metal plating layer and the glass fiber. The gradient copper-graphene nanosheet conductive shell layer 3 has an increasing copper content and a decreasing graphene nanosheet content from the inside to the outside, and is divided into an inner layer region and an outer layer region. The gradient distribution enables the conductive shell layer 3 to have good conductivity while meeting different performance requirements. The inner layer is rich in graphene nanosheets, and the graphene nanosheets have excellent conductivity, flexibility and chemical stability, which can enhance the bonding force between the conductive shell layer 3 and the transition layer 2 while ensuring the conductivity; and the outer layer is rich in copper, and copper is an excellent conductor, and a higher copper content can further improve the overall conductivity of the conductive glass fiber to meet the high requirements for the conductivity of materials in the fields of energy electronics and space technology. The hydrophobic packaging layer 4 is a silica aerogel film, which can effectively protect the conductive glass fiber, so that it has good waterproof and moisture-proof performance, avoids the erosion of water and moisture in the external environment on the conductive shell layer 3 and the transition layer 2, thereby prolonging the service life of the conductive glass fiber and improving its stability and reliability in complex environments.

[0025] In the embodiment, the MOF-CNT transition layer 2 is composed of in-situ growth of a metal organic framework MOF and coated carbon nanotubes, and the MOF is at least one of zeolitic imidazolate frameworks ZIF-8 and ZIF-67. The CNT is bound by in-situ growth of the MOF (such as ZIF-8 and ZIF-67), a porous conductive framework is formed, and the interfacial bonding force is enhanced.

[0026] The porous conductive framework not only improves the bonding strength between the glass fiber core 1 and the conductive shell layer 3, but also provides more channels for the transmission of electrons, further improving the conductivity of the conductive glass fiber. ZIF-8 and ZIF-67 have unique crystal structures and chemical properties, and their pore sizes are moderate, which can effectively adsorb and fix carbon nanotubes, and the chemical bonding with the surface of the glass fiber is also relatively stable.

[0027] In practical applications, when the conductive glass fiber is subjected to external force, the MOF-CNT transition layer 2 can disperse stress, prevent peeling between the conductive shell layer 3 and the glass fiber core 1, and ensure the integrity and stability of the conductive glass fiber structure. Moreover, this transition layer 2 also has a certain flexibility, which can adapt to different use scenarios and deformation requirements.

[0028] In this embodiment, the gradient copper-graphene nanosheet conductive shell layer 3 includes an inner layer region and an outer layer region, wherein: The inner layer region: copper content 45-60 vol%, GNP content 30-40 vol%; the high content of GNPs (>30 vol%) in the inner layer provides a conductive path and reduces the density; The outer layer region: copper content 80-92 vol%, GNP content 5-10 vol%. The volume content of copper continuously increases from the inside to the outside of the shell layer, and the volume content of GNP continuously decreases. The high content of Cu (>80 vol%) ensures the surface conductivity and electromagnetic shielding effectiveness.

[0029] The high GNPs volume fraction (30-40 vol%) in the inner layer of the gradient deposition constructs an efficient conductive network, while replacing part of the metal copper to achieve lightweight (density is only 43% of pure copper). The high copper volume fraction (80-92 vol%) in the outer layer ensures excellent surface conductivity and weldability. This continuous gradient structure with increasing copper content and decreasing GNP content from the inside to the outside effectively relieves the interfacial stress caused by the mismatch of the thermal expansion coefficient, avoids the micro-cracks caused by stress concentration in the traditional homogeneous copper-plated layer in the bending fatigue test, and therefore the resistance change rate is significantly reduced.

[0030] For the gradient copper-graphene nanosheet conductive shell layer 3, its unique gradient distribution design is carefully considered. The inner layer rich in graphene nanosheets not only has good conductivity, flexibility and chemical stability, but also can form a continuous conductive network inside the conductive shell layer 3, reducing the resistance of electron transmission. With the transition from the inner layer to the outer layer, the copper content gradually increases, and the high conductivity of copper further enhances the conductivity of the entire conductive shell layer 3. This gradient change is a kind of synergistic optimization design, which can fully exert the respective advantages of graphene nanosheets and copper, so that the conductive glass fiber can exhibit excellent conductivity in different application environments.

[0031] In this embodiment, the hydrophobic packaging layer 4 is a silica aerogel film with a thickness of ≤200 nm.

[0032] The hydrophobic encapsulation layer 4, although thin, has excellent waterproof and moisture-proof effects. The silica aerogel has extremely low density and high porosity, which can effectively block the invasion of water and moisture. At the same time, the film also has good chemical stability and thermal stability, and will not degrade in performance due to changes in the external environment. In some humid environments, such as marine environments, underground engineering, etc., the hydrophobic encapsulation layer 4 can ensure the performance of the conductive glass fiber is not affected, ensuring its reliability during long-term use.

[0033] The unique feature of the gradient design of the conductive glass fiber of the present application is that the traditional coating is prone to fall off due to the difference in the coefficient of thermal expansion in different temperature environments, and the gradient design of the present application solves this problem well, so that the conductive glass fiber can still maintain structural stability and performance reliability in environments with large temperature changes. The molecular-level anchoring effect of the MOF-CNT transition layer 2 greatly improves the interlayer adhesion. When subjected to external force, it can ensure that each layer works cooperatively to avoid a decrease in conductivity due to interlayer separation, greatly extending the service life of the conductive glass fiber. The Cu-GNP composite conductive layer realizes efficient conduction, and is 30% lighter than the pure copper coating, which can reduce the overall weight of the equipment while ensuring the conductivity, thereby reducing energy consumption. The hydrophobic encapsulation provides a guarantee for the use of the conductive glass fiber in harsh environments. The resistance change is less than 5% after salt spray testing for 240 hours, indicating that in harsh environments with high humidity and high salt content, the hydrophobic encapsulation layer 4 can effectively block the erosion of salt and water, maintaining the stability of the conductivity of the conductive glass fiber.

[0034] Embodiments of the second aspect of the application provide a method for preparing the conductive glass fiber, comprising the following steps: (a) performing oxygen plasma etching pretreatment on the glass fiber to generate 50-100 nm pits on the fiber surface, thereby increasing the specific surface area and maintaining the strength; (b) constructing a MOF-CNT transition layer on the surface of the pretreated fiber; (c) gradient depositing a copper-graphene nanosheet conductive shell layer on the transition layer; (d) forming a hydrophobic encapsulation layer outside the conductive shell layer. In this embodiment, in step (a), an atmospheric pressure roll-to-roll plasma treatment machine is used, the electrode spacing is 8 mm, the frequency is 40 kHz, the oxygen plasma etching gas is O2 and Ar, and the volume ratio of O2 to Ar is (5-7):(3-5), the oxygen radical activity is enhanced by argon ionization; the power density is 1.0-2.0 W / cm 2 ; the power density is <1.0 W / cm 2 ; the power density is >2.0 W / cm 2Fiber strength is reduced; the treatment time is 3-8 min, the fiber running speed is 3-4 m / min, and the treatment zone length is 15 m; the treatment temperature is 55-65℃, and a water-cooled roller temperature control is used to avoid local overheating.

[0035] This step generates 50-100 nm pits on the surface of the glass fiber through oxygen plasma etching pretreatment, which can significantly increase the specific surface area of the fiber. The increase in the specific surface area provides more attachment sites for the subsequent construction of the MOF-CNT transition layer, enabling the transition layer to be more firmly bonded to the surface of the glass fiber. In actual operation, an atmospheric pressure roll-to-roll plasma treatment machine is used, which can realize continuous production and improve production efficiency. The electrode spacing is set to 8 mm, and the frequency is 40 kHz to ensure the uniformity of plasma generation and distribution. The volume ratio of O2 to Ar is controlled at (5-7):(3-5), and the argon ionization is used to enhance the activity of oxygen radicals, making the etching effect more ideal. The power density is controlled at 1.0-2.0 W / cm 2 If the power density is less than 1.0 W / cm 2 , the etching is insufficient, and the desired specific surface area cannot be achieved; if the power density is greater than 2.0 W / cm 2 , the fiber strength will be reduced, affecting the overall performance of the conductive glass fiber. The treatment temperature is controlled at 55-65℃, and a water-cooled roller temperature control is used to avoid local overheating and prevent damage to the glass fiber due to high temperature. After such oxygen plasma etching pretreatment, the glass fiber surface forms an ideal microstructure, laying a good foundation for the subsequent construction of the MOF-CNT transition layer, which helps to improve the bonding force between the layers of the conductive glass fiber and the overall performance. In this embodiment, step (b) uses an immersion tank (with ultrasonic assistance, frequency 40 kHz) and a vapor reaction chamber, which specifically includes: (b1) The etched glass fiber is immersed in a CNT dispersion liquid, the CNT concentration in the dispersion liquid is 0.3-0.8 wt%, and the dispersant is polydopamine; preferably, the CNT concentration in the CNT dispersion liquid is 0.5 wt%, the polydopamine is 0.1 wt%, and the solvent is a mixture of deionized water and ethanol in a volume ratio of 7:3. The polydopamine modifies the surface of the CNT to enhance the bonding force with the MOF. The temperature for immersing the glass fiber in the CNT dispersion liquid is 22-28℃, the time is 2-5 min, and the power of the ultrasonic assistance is 90-110 W / m 2 , so that the CNTs are embedded in the plasma etching pits.

[0036] (b2) The glass fiber treated in step (b1) is placed in a zinc ion solution and a 2-methyl imidazole vapor environment, the reaction temperature is 50-70℃, and the reaction time is 15-25 min, to generate a ZIF-8 coated CNT composite structure.

[0037] The zinc ion solution comprises 0.1M zinc nitrate, 0.4M 2-methylimidazole, and the buffer triethylamine. The pH of the solution is 9.2-9.8, and the alkaline environment accelerates ZIF-8 nucleation. The steam environment is maintained at a pressure of 0.1-0.15 MPa, which avoids side reactions in the solution through gas-phase diffusion, allowing MOFs to undergo heterogeneous nucleation on the CNT surface. The MOF growth is terminated immediately after the steam reaction by rinsing with ethanol.

[0038] This step combines an immersion tank and a steam reaction chamber, fully leveraging the advantages of both devices to effectively construct the MOF-CNT transition layer. In step (b1), the etched glass fibers are immersed in a CNT dispersion, and ultrasonic assistance is used to embed the CNTs into plasma-etched pits. Polydopamine modification of the CNT surface enhances their bonding with the subsequent MOF. In step (b2), the treated glass fibers are placed in a specific zinc ion solution and 2-methylimidazole vapor environment. Gas-phase diffusion avoids solution side reactions, allowing the MOF to nucleate heterogeneously on the CNT surface. Through step (b), a MOF-CNT transition layer is successfully constructed on the glass fiber surface. This transition layer enhances the interfacial bonding between the glass fiber core and the subsequent gradient copper-graphene nanosheet conductive shell. This transition layer not only solves the problem of weak interfacial bonding between traditional metal coatings and glass fibers but also lays a solid foundation for improving the overall performance of conductive glass fibers, enabling them to exhibit excellent performance in various application scenarios. In this embodiment, step (c) employs a segmented roll-to-roll electrodeposition tank (anode: phosphorus copper ball, cathode: fiber), a pulsed power supply (rise time <10μs, duty cycle adjustable), and a method for gradient deposition of a copper-graphene nanosheet conductive shell on the transition layer, comprising: (c1) Electrophoretic deposition of a GNP-rich inner layer: In a suspension containing 10-15 g / L of GNP, a DC voltage of 15-25 V is applied for a deposition time of 20-40 s; specifically, the graphene nanosheets (GNP) in the GNP-containing suspension are 3-5 nm thick and 50 μm in diameter; the dispersant is polyvinylpyrrolidone (PVP K30) at a concentration of 0.5 g / L; the solvent is deionized water; preferably, the voltage is applied for 20 V for 30 s. Electrophoretic deposition preferentially adsorbs negatively charged GNPs into the MOF pores, aiming to achieve a GNP volume fraction of 30-40% in the inner layer, forming a conductive network matrix.

[0039] (c2) Pulse electrodeposition gradient transition layer: in Cu-containing... 2+ In an electrolyte solution of 0.5-1.0 M and GNP 3-5 g / L, a pulsed current is used, with an on-time of 8-12 ms, an off-time of 4-6 ms, and a current density of 15-25 A / dm³. 2; Specifically, the electrolyte includes 0.8 M (CuSO4·5H2O), 0.6 M trisodium citrate as a complexing agent, the concentration of GNP is preferably 4 g / L, and the brightener sodium polydithiopropyl sulfone has a concentration of 50 mg / L; preferably, the pulse mode is: on: 10 ms, 20 A / dm 2 , off: 5 ms. During the off period, Cu 2+ diffuses to the edge of GNP to achieve Cu-GNP co-deposition; and the GNP concentration is reduced to 4 g / L to promote the increase of Cu proportion.

[0040] (c3) Pulse electrodeposition of a copper-rich outer layer: in an electrolyte containing Cu 2+ 1.0-1.5 M, using pulse current, on time 13-17 ms, off time 2-4 ms, current density 22-28 A / dm 2 . The electrolyte includes 1.2 M (CuSO4·5H2O), 0.8 M trisodium citrate, and 100 mg / L of polyethylene glycol. Preferably, the pulse mode is: on: 15 ms, 25 A / dm 2 , off: 3 ms. High current density and short off time promote the dense deposition of pure copper to form a surface copper-rich layer.

[0041] This step uses a segmented roll-to-roll electrodeposition tank and a pulse power supply, which can accurately control the electrodeposition process, thereby achieving high-quality deposition of the gradient copper-graphene nanosheet conductive shell. In step (c1), through electrophoretic deposition, negatively charged GNPs are preferentially adsorbed in the MOF pores to form the basis of the conductive network, providing a good framework for subsequent electrodeposition. In the pulse electrodeposition of the gradient transition layer in step (c2), Cu 2+ diffuses to the edge of GNP to achieve Cu-GNP co-deposition, and the GNP concentration is reduced to promote the increase of Cu proportion, so that the conductivity of the conductive shell can gradually increase, realizing the gradient change from inside to outside. In the pulse electrodeposition of the copper-rich outer layer in step (c3), high current density and short off time promote the dense deposition of pure copper to form a surface copper-rich layer, further improving the overall conductivity of the conductive glass fiber.

[0042] Meanwhile, the composition and concentration of the electrolyte in each step have also been carefully adjusted. For example, in the electrolyte for pulse electrodeposition of the gradient transition layer, trisodium citrate as a complexing agent can stabilize Cu 2+The concentration of the brightener sodium polydithiopropyl sulfone can improve the surface quality of the deposit, and make the conductive shell layer more smooth and uniform. In the electrolyte for pulse electrodeposition of the copper-rich outer layer, the addition of polyethylene glyol can also help to improve the quality of the deposit, and make the copper-rich outer layer more dense. Through the electrodeposition of the three steps, a copper-graphene nanosheet conductive shell layer with gradient distribution is successfully formed on the MOF-CNT transition layer. This gradient design makes the conductive performance of the conductive glass fiber gradually enhanced from inside to outside, fully plays the respective advantages of graphene nanosheet and copper, and also improves the bonding force between the conductive shell layer and the transition layer, further improves the overall performance and stability of the conductive glass fiber.

[0043] In the embodiment, step (d) adopts a vapor deposition method to make the hexamethyldisilazane vapor react with the fiber surface at 120-180°C for 5-15 min to generate the SiO2 aerogel encapsulation layer.

[0044] Step (d) adopts a chemical vapor deposition method (CVD) to prepare the hydrophobic encapsulation layer, specifically including: placing the conductive glass fiber treated in step (c) in a chemical vapor deposition device, and introducing a silicon source gas and a carrier gas, under the conditions of a temperature of 200-300°C and a pressure of 1-5 Pa, the silicon source gas is decomposed and deposited on the surface of the conductive glass fiber, the deposition time is 30-60 min, and a silicon dioxide aerogel film is formed. The silicon source gas can be selected from tetraethyl orthosilicate (TEOS), and the carrier gas can be selected from nitrogen. By accurately controlling these parameters, a silicon dioxide aerogel film with a thickness of ≤200 nm can be obtained, which has good waterproof and moisture-proof performance, can effectively protect the conductive glass fiber, and prolong the service life thereof. The encapsulation layer not only can prevent the erosion of water, moisture and the like in the external environment on the conductive shell layer and the transition layer, but also can improve the stability and reliability of the conductive glass fiber in a complex environment. EMBODIMENT The following examples describe the disclosed subject matter in more detail in which: these examples are for illustrative purposes only and various modifications and changes in light thereof will be obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported herein are on a weight basis. Unless otherwise stated, all reagents used in the examples are commercially available or are synthesized according to conventional methods and used without further purification. Unless otherwise stated, the instruments used in the examples are commercially available.

[0045] Example 1 A conductive glass fiber, comprising: a glass fiber core; a MOF-CNT transition layer coated on the surface of the core; A gradient copper-graphene nanoplatelet conductive shell layer is coated on the transition layer, wherein the copper content increases from inside to outside, and the graphene nanoplatelet GNP content decreases; wherein the inner layer region: copper content 45-60 vol%, GNP content 30-40 vol%; the outer layer region: copper content 80-92 vol%, GNP content 5-10 vol%; the volume content of copper in the shell layer continuously increases from inside to outside, and the volume content of GNP continuously decreases; A hydrophobic encapsulation layer is coated outside the conductive shell layer.

[0046] The preparation method of the conductive glass fiber comprises the following steps: (a) The glass fiber is subjected to oxygen plasma etching pretreatment to generate 50-100 nm pits on the fiber surface, thereby improving the specific surface area and maintaining the strength; specifically, an atmospheric pressure roll-to-roll plasma treatment machine is used, the electrode spacing is 8 mm, the frequency is 40 kHz, the oxygen plasma etching gas is O2 and Ar, and the volume ratio of O2 to Ar is 6:3, the oxygen radical activity is enhanced by argon ionization; the power density is 1.8 W / cm 2 ; the power density is <1.0 W / cm 2 ; etching is insufficient; >2.0 W / cm 2 ; the fiber strength decreases; the treatment time is 6 min, the fiber running speed is 3 m / min, the treatment zone length is 15 m; the treatment temperature is 60℃, a water-cooled roller is used for temperature control to avoid local overheating; (b) A MOF-CNT transition layer is constructed on the surface of the pretreated fiber; specifically comprising: (b1) The etched glass fiber is immersed in a CNT dispersion liquid, the CNT concentration in the dispersion liquid is 0.5wt%, the polydopamine concentration is 0.1wt%, and the solvent is a mixture of deionized water and ethanol in a volume ratio of 7:3. The polydopamine modifies the surface of the CNT to enhance the binding force with the MOF. The glass fiber is immersed in the CNT dispersion liquid at a temperature of 26℃ for 4 min, and the ultrasonic auxiliary power is 110W / m 2 , so that the CNT is embedded in the plasma etching pits.

[0047] (b2) The glass fiber treated in step (b1) is placed in a zinc ion solution and 2-methyl imidazole vapor environment, the reaction temperature is 60℃, and the reaction time is 20 min, to generate a ZIF-8 coated CNT composite structure.

[0048] The zinc ion solution includes 0.1M zinc nitrate, 0.4M 2-methylimidazole and buffer triethylamine, the pH of the solution is 9.5, and the basic environment accelerates the nucleation of ZIF-8; the pressure in the steam environment is 0.12MPa, the solution side reaction is avoided through gas phase diffusion, and the MOF is heterogeneously nucleated on the surface of the CNT. After the steam reaction, immediately flush with ethanol to terminate the growth of the MOF. (c) Gradient deposition of a copper-graphene nanosheet conductive shell layer on the transition layer; comprising: (c1) Electrophoretic deposition of a GNP-rich inner layer: in a suspension containing GNPs 12 g / L, a direct current voltage of 20V is applied, and the deposition time is 30s; Specifically, the graphene nanosheet (GNP) in the GNP-containing suspension (thickness 3-5nm, diameter 50μm); the dispersing agent is polyvinylpyrrolidone (PVP K30), the concentration is 0.5 g / L; the solvent is deionized water; the voltage application time is 30s. Electrophoretic deposition allows negatively charged GNPs to preferentially adsorb in the MOF pores to form a conductive network matrix; (c2) Pulse electrodeposition of a gradient transition layer: in an electrolyte containing Cu 2+ 1.2M, a pulse current is used, the on time is 15ms, the off time is 3ms, and the current density is 25 A / dm 2 2. The Cu 2+ diffuses to the edge of the GNP to realize Cu-GNP co-deposition; and the decreasing GNP concentration to 4g / L promotes the increase of Cu proportion; The electrolyte includes 0.8M (CuSO4·5H2O), 0.6M trisodium citrate as a complexing agent, and the concentration of GNPs is 4 g / L, and the concentration of brightener sodium polydithiopropyl sulfonate is 50mg / L; In the process of pulse deposition, the first pulse copper deposition is 45-50vol%, and the GNP deposition is 36-40%; the second pulse is deposited again, so that the copper content is 46-51vol%, and the GNP content is 37-41%,......, until the outer layer area copper content is 86-92vol%, and the GNP content is 7-10vol%. The rest is in the deposition process, hydrogen gas is released, additives are decomposed, or particles are agglomerated, which may leave micrometer or nanometer-sized pores in the plated layer, as well as inclusions, oxides or other unavoidable trace impurities from organic additives in the electrolyte (such as brighteners, etc.). (The Cu-GNP composite layer is actually a three-phase system composed of "copper phase + GNP phase + pore / impurity phase").

[0049] (c3) Pulse electrodeposition of a copper-rich outer layer: in an electrolyte containing Cu 2+ 1.2M, a pulse current is used, the on time is 15ms, the off time is 3ms, and the current density is 25 A / dm 2The electrolyte includes 1.2M (CuSO4·5H2O), 0.8M trisodium citrate, 100mg / L polyethylene glycol; high current density and short off time promote pure copper dense deposition, forming a surface copper-rich layer.

[0050] (d) Vapor of hexamethyldisilazane is reacted with the surface of the fiber at 150℃ for 10 min by vapor deposition to form a SiO2 aerogel encapsulation layer.

[0051] Example 2 This example is basically the same as Example 1, except that in step (a) the volume ratio of O2 to Ar is 7:5, and the power density is 1.5 W / cm 2 .

[0052] Example 3 This example is basically the same as Example 1, except that in step (b1) the temperature at which the glass fiber is immersed in the CNT dispersion is 25℃, the time is 3 min, and the power of the ultrasonic assistance is 100 W / m 2 .

[0053] Example 4 This example is basically the same as Example 1, except that in step (c1) a 18V direct current voltage is applied in a suspension containing GNPs 15 g / L, and the deposition time is 35 s.

[0054] Example 5 This example is basically the same as Example 1, except that in step (c2) a pulse current is used in an electrolyte containing Cu 2+ 0.6M, GNPs 5 g / L, the on time is 9 ms, the off time is 6 ms, and the current density is 23 A / dm 2 Example 6 This example is basically the same as Example 1, except that in step (c3) a pulse current is used in an electrolyte containing Cu 2+ 1.4M, the on time is 14 ms, the off time is 2 ms, and the current density is 27 A / dm 2 .

[0055] Comparative Example 1 This comparative example is basically the same as Example 1, except that the glass fiber is not subjected to oxygen plasma etching pretreatment.

[0056] Comparative Example 2 This comparative example is basically the same as Example 1, except that in step (b2) the 2-methylimidazole vapor is not included.

[0057] Comparative Example 3 This comparative example is substantially the same as Example 1, except that there is no MOF-CNT transition layer, and the copper-graphene nanosheet conductive shell layer is directly deposited on the glass fibers in step (a).

[0058] Comparative Example 4 This comparative example is substantially the same as Example 1, except that there is no hydrophobic encapsulation layer.

[0059] The conductive glass fibers in Examples 1-6 and Comparative Examples 1-4 were tested for performance, in which the resistivity was tested by four-probe method, the density was tested by drainage method, and the salt spray test (ASTM B117, 240h) was conducted, and the test results are shown in Table 1.

[0060] Table 1 Performance test results of Examples 1-6 and Comparative Examples 1-4

[0061] As can be seen from Table 1, the conductive glass fibers of Examples 1-6 are obviously superior to Comparative Examples 1-4 in terms of resistivity, resistance change rate after salt spray, and density. It shows that after the steps of oxygen plasma etching pretreatment, constructing MOF-CNT transition layer, depositing gradient copper-graphene nanosheet conductive shell layer, and setting hydrophobic encapsulation layer, the resistance of the conductive glass fiber can be effectively reduced, and its conductivity can be improved. The resistance change rate after salt spray shows that the reasonable setting of each step plays a key role in improving the corrosion resistance of the conductive glass fiber. For example, the oxygen plasma etching pretreatment improves the specific surface area of the fiber surface, so that each subsequent layer can be better attached; the MOF-CNT transition layer enhances the bonding force between the glass fiber core and the conductive shell layer; the gradient copper-graphene nanosheet conductive shell layer provides good conductivity; and the hydrophobic encapsulation layer effectively blocks the erosion of moisture, humidity, etc. in the external environment on the conductive shell layer and the transition layer. In terms of density, the density of the examples is 3.82-4.02 g / cm 3 The density of the comparative examples is 4.32-4.68 g / cm 3 This may be because some defects exist in the comparative examples, such as the smooth surface that cannot anchor the transition layer, the MOF body crystallization that blocks the conductive path, the difference in thermal expansion coefficient between glass and copper that causes delamination, and the direct exposure of copper without a hydrophobic encapsulation layer, which results in a less dense structure, thereby increasing the density.

[0062] The absence of plasma etching in Comparative Example 1 results in a smooth surface of the glass fiber, making it difficult for the MOF-CNT layer to anchor on its surface. The subsequent MOF-CNT transition layer cannot stably adhere to the surface of the glass fiber core, thereby affecting the structural integrity and performance stability of the entire conductive glass fiber. Due to the ineffective anchoring of the MOF-CNT layer, the subsequent deposition of the gradient copper-graphene nanosheet conductive shell layer will result in poor adhesion. This poor adhesion will lead to poor conductivity, and electrons will encounter more obstacles during transmission, resulting in a significant increase in the resistivity of the conductive glass fiber.

[0063] In Comparative Example 2, the absence of 2-methylimidazole vapor in step (b2) prevents the MOF from heterogeneous nucleation on the surface of the CNT, resulting in MOF bulk crystallization. These crystals will block the conductive path of the CNT, greatly hindering the transmission of electrons. In the subsequent performance test, the resistivity of the conductive glass fiber of Comparative Example 2 is significantly higher than that of the examples, and the resistance change rate after salt spray is also greatly increased. This is because the CNT conductive path is blocked, resulting in a sharp decline in conductivity, and due to the instability of the structure, it is more susceptible to corrosion in a salt spray environment, leading to further increases in resistance. Moreover, MOF bulk crystallization also affects the structural density of the entire conductive glass fiber, resulting in an increase in density. Compared with the examples, Comparative Example 2 performs poorly in various performance indicators, fully demonstrating the importance of 2-methylimidazole vapor in the formation of the MOF-CNT transition layer. It can promote the heterogeneous nucleation of MOF on the surface of CNT, avoid bulk crystallization, and ensure the smoothness of the conductive path and the good performance of the conductive glass fiber.

[0064] In Comparative Example 3, without the MOF-CNT transition layer, the copper-graphene nanosheet conductive shell layer is directly deposited on the glass fiber, which will face the problem of the difference in thermal expansion coefficient between glass and copper. In different temperature environments, the expansion and contraction of the glass fiber and the copper-graphene nanosheet conductive shell layer are different. This difference in thermal expansion coefficient will cause stress between the two, and with the passage of time and repeated changes in temperature, the stress will accumulate, eventually leading to delamination of the glass fiber and the conductive shell layer. Delamination will disrupt the conductive path, making it difficult for electrons to transmit smoothly in the conductive glass fiber, resulting in a significant increase in resistivity. In the salt spray test, the delaminated structure allows external moisture and salt to more easily penetrate the interior, accelerating the corrosion of the conductive shell layer and the glass fiber, resulting in a significant increase in the resistance change rate after salt spray. At the same time, due to the structural instability caused by delamination, the density will also increase accordingly. This indicates that the MOF-CNT transition layer plays a crucial role in mitigating the difference in thermal expansion coefficient between glass and copper and enhancing the adhesion between the two, ensuring the stability of the structure and the reliability of the performance of the conductive glass fiber.

[0065] Comparative Example 4 has no hydrophobic encapsulation layer, so the copper is directly exposed to the corrosive environment. In a simulated harsh environment such as a salt spray test, moisture and salt from the outside environment will directly contact the copper in the conductive shell, causing a chemical reaction and leading to corrosion of the copper. After the copper is corroded, its conductivity will decrease sharply, as indicated by an increase in resistivity. Moreover, as the corrosion continues, the structure of the conductive shell will be gradually destroyed, further affecting the transmission of electrons, resulting in a large increase in the resistance change rate after the salt spray. Without the protection of the hydrophobic encapsulation layer, the stability and reliability of the conductive glass fiber in a complex environment are greatly compromised. Compared with the examples, the performance indicators of Comparative Example 4 are significantly worse, fully demonstrating the important role of the hydrophobic encapsulation layer in preventing environmental erosion, protecting the conductive shell and transition layer, and effectively extending the service life of the conductive glass fiber and improving its performance in actual applications. It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the gist of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the elements of the embodiments are also included in the scope of the present application.

Claims

1. An electrically conductive glass fiber, characterized in that, The application relates to a glass fiber with a gradient copper-graphene nanosheet conductive shell layer, which comprises the following steps: a glass fiber inner core (1); a MOF-CNT transition layer (2) coated on the surface of the inner core (1); a gradient copper-graphene nanosheet conductive shell layer (3) coated on the transition layer (2), wherein the copper content increases from the inside to the outside, and the graphene nanosheet content decreases; and a hydrophobic encapsulation layer (4) coated on the conductive shell layer (3).

2. The electrically conductive glass fiber of claim 1, wherein, The MOF-CNT transition layer (2) is composed of metal organic framework MOF in-situ growth and carbon nanotube coating, and the MOF is at least one of zeolite imidazolate framework materials ZIF-8 and ZIF-67.

3. The electrically conductive glass fiber of claim 1, wherein, The gradient copper-graphene nanosheet conductive shell layer (3) comprises an inner layer region and an outer layer region, wherein: the inner layer region: the copper content is 45-60 vol%, and the GNP content is 30-40 vol%; the outer layer region: the copper content is 80-92 vol%, and the GNP content is 5-10 vol%.

4. The electrically conductive glass fiber of claim 1, wherein, The hydrophobic encapsulation layer (4) is a silica aerogel film with a thickness of less than or equal to 200 nm.

5. A process for the production of electrically conductive glass fibers according to any one of claims 1 to 4, characterized in that, The application further relates to a method for preparing the glass fiber with a gradient copper-graphene nanosheet conductive shell layer, which comprises the following steps: (a) performing oxygen plasma etching pretreatment on the glass fiber; (b) constructing the MOF-CNT transition layer (2) on the surface of the pretreated fiber; (c) gradient depositing the copper-graphene nanosheet conductive shell layer (3) on the transition layer (2); (d) forming the hydrophobic encapsulation layer (4) on the conductive shell layer (3).

6. The method of making electrically conductive glass fibers according to claim 5, wherein, In step (a), the oxygen plasma etching gas is O2 and Ar, and the volume ratio of O2 to Ar is (5-7):(3-5); and / or Power density 1.0 - 2.0 W / cm 2 ; and / or the treatment time is 3-8 min.

7. The method of making electrically conductive glass fibers according to claim 5, wherein, Step (b) specifically comprises: (b1) immersing the etched glass fiber into a CNT dispersion liquid, wherein the CNT concentration in the dispersion liquid is 0.3-0.8 wt%, and the dispersing agent is polydopamine; (b2) placing the glass fiber treated in step (b1) into a zinc ion solution and 2-methyl imidazole vapor environment, and the reaction temperature is 50-70 DEG C, and the reaction time is 15-25 min, to generate a ZIF-8 coated CNT composite structure.

8. The method of making electrically conductive glass fibers according to claim 5, wherein, The method for gradient depositing the copper-graphene nanosheet conductive shell layer (3) on the transition layer (2) in step (c) comprises: (c1) electrophoretic deposition of a GNP-rich inner layer: in a suspension containing 10-15 g / L of GNP, a direct current voltage of 15-25 V is applied, and the deposition time is 20-40 s; (c2) Pulse electrodeposition of a gradient transition layer (2): in an electrolyte containing Cu 2+ 0.5-1.0 M, GNP 3-5 g / L, pulse current, on-time 8-12 ms, off-time 4-6 ms, current density 15-25 A / dm 2 ; (c3) Pulse electrodeposition of a copper-rich outer layer: in an electrolyte containing Cu2+ 1.0-1.5 M, using a pulse current with a conduction time of 13-17 ms and an off time of 2-4 ms, at a current density of 22-28 A / dm2 2 .

9. The method of making electrically conductive glass fibers according to claim 8, wherein, the electrolyte in steps (c2) and (c3) both comprises a citric acid complexing agent, and the concentration is 0.5-1.0 M, and the pH value is 2.5-3.

5.

10. The method of making electrically conductive glass fibers according to claim 5, wherein, In step (d), the vapor of hexamethyldisilazane is made to react with the surface of the fiber at 120-180 DEG C for 5-15 min to generate a SiO2 aerogel encapsulation layer.

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