Method and device for coating metal on fiber surface, and metallized fiber

Abstract

The present disclosure provides a method, apparatus, and metallized fiber for coating a fiber surface with metal. The method comprises: applying a slurry containing graphite powder, a coupling agent, and a resin to the fiber surface; curing the slurry to form a coating on the fiber surface; electrostatically spraying metal powder onto the coating surface; and allowing the metal powder to melt onto the coating surface. The present disclosure can produce a continuous, dense metal coating and ensure good adhesion strength.

Description

Technical Field

[0001] The present disclosure relates to the field of coating technology, and in particular to a method and device for coating metal on a fiber surface, and a metallized fiber. Background Art

[0002] In order to improve the mechanical properties of the fiber (for example, to improve the brittleness, wear resistance and damage resistance of the glass fiber) and / or to make the fiber have good optoelectronic functions, metal is usually coated on the fiber surface to obtain metallized fibers with better performance or new properties.

[0003] In the prior art, metal coatings are typically applied to fiber surfaces using methods such as vacuum evaporation, chemical vapor deposition (CVD), magnetron sputtering, and plasma deposition. However, these methods struggle to completely cover the fiber surface with the metal coating, and are unable to form a continuous, dense metal coating.

[0004] U.S. Patent No. 4,390,589 discloses a method for hot-dip coating glass fibers with molten metal, enabling online aluminum coating of glass fibers of any tensile length. However, the metal coating of the aluminized glass fibers produced using this method is susceptible to cavities, which reduce the product's strength and fatigue resistance. Furthermore, the metal coating exhibits poor adhesion and easily peels off after friction or washing, hindering the application of the aluminized glass fibers. Summary of the Invention

[0005] A technical problem to be solved by the present disclosure is that in the prior art, a continuous and dense metal coating cannot be formed when metal is coated on the fiber surface, and the adhesion of the metal coating is not strong.

[0006] To solve the above technical problems, an embodiment of the present disclosure provides a method for coating metal on a fiber surface, comprising: coating a slurry on the fiber surface, wherein the slurry contains graphite powder, a coupling agent and a resin; allowing the slurry to solidify and form a coating on the fiber surface; electrostatically spraying metal powder on the coating surface; and allowing the metal powder to melt onto the coating surface.

[0007] In some embodiments, the particle size of the graphite powder is 0.5 to 3 μm; and / or the coupling agent is a siloxane coupling agent and / or an epoxy silane coupling agent; and / or the molecular weight of the resin is less than 5,000.

[0008] In some embodiments, on a dry basis, in the slurry, the weight ratio of graphite powder, coupling agent, and resin is (50-80):(5-10):(10-25).

[0009] In some embodiments, the slurry is applied by passing the fiber through the slurry, and the speed of the fiber passing through the slurry is no more than 10 m / min; and / or before applying the slurry, the method further comprises: acid-treating the fiber.

[0010] In some embodiments, the surface density of graphite powder on the fiber surface is 0.1×10 -5 g / cm 2 to 1×10 -5 g / cm 2 and / or forming a surface resistivity of the coated fiber of not more than 10 5 Ω·cm.

[0011] In some embodiments, the resin contains an ultraviolet initiator, and curing the slurry includes subjecting the fibers coated with the slurry to infrared radiation and ultraviolet radiation, and placing the fibers coated with the slurry in an inert gas environment during the ultraviolet radiation.

[0012] In some embodiments, the metal powder is electrostatically sprayed onto the coating surface, including: causing the coated fiber to be positively charged and pass through a powder spraying chamber, and spraying negatively charged metal powder onto the coating during the passage; and / or causing the metal powder to be melted onto the coating surface, including: causing the metal powder to melt due to heat and form a molten film on the coating surface, and annealing the fiber with the molten film.

[0013] An embodiment of the present disclosure also provides a device for coating metal on the surface of a fiber, comprising: a slurry tank, the slurry tank is used to accommodate a slurry containing graphite powder, a coupling agent and a resin; a curing mechanism, the curing mechanism is used to solidify the slurry; an electrostatic spraying mechanism, the electrostatic spraying mechanism includes a powder spraying chamber, a positive charge applying part, and a spray gun, the spray gun is used to apply a negative charge to the metal powder and spray it; a cladding mechanism, the cladding mechanism includes a heating furnace, the heating furnace can heat the metal powder to a molten state; a plurality of rollers, used to drive the fiber to move and pass through the slurry tank, the curing mechanism, the powder spraying chamber and the heating furnace in sequence.

[0014] In some embodiments, the curing mechanism includes a curing chamber and an emitting portion for emitting infrared and ultraviolet rays into the curing chamber; and / or the cladding mechanism further includes an annealing furnace, and the plurality of rollers further drive the fibers through the annealing furnace.

[0015] The embodiment of the present disclosure also provides a metallized fiber, comprising: a fiber body; a coating provided on the surface of the fiber body, the coating being a solidified product of a slurry, the slurry comprising graphite powder, a coupling agent and an adhesive; a metal cladding layer provided on the surface of the coating, the metal cladding layer being obtained by cladding metal powder electrostatically sprayed onto the surface of the coating.

[0016] Through the above technical solution, the method for coating metal on the fiber surface provided by the present disclosure can obtain a continuous and dense metal coating and can ensure that the metal coating has good adhesion strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 is a flow chart of a method for coating a metal on a fiber surface according to an exemplary embodiment of the present disclosure;

[0019] Figure 2 is a partial structural schematic diagram of a device for coating metal on a fiber surface according to an exemplary embodiment of the present disclosure;

[0020] Figure 3 is another partial structural schematic diagram of a device for coating metal on a fiber surface according to an exemplary embodiment of the present disclosure;

[0021] Figure 4 is a cross-sectional view of a metallized fiber according to an exemplary embodiment of the present disclosure;

[0022] Figure 5 3 is a scanning electron microscope image of the cross section of the metallized fiber prepared in Example 1 of the present disclosure.

[0023] Description of reference numerals:

[0024] 10. Slurry tank; 20. Curing mechanism; 22. Curing chamber; 30. Electrostatic spraying mechanism; 31. Powder tank; 32. Powder spraying chamber; 33. Gas cylinder; 34. Positive charge application unit; 36. Spray gun; 40. Cladding mechanism; 42. Heating furnace; 44. Annealing furnace; 50. Roller; 100. Metallized fiber; 101. Fiber body; 103. Coating; 105. Metal cladding layer. DETAILED DESCRIPTION

[0025] The following embodiments of the present disclosure are further described in detail with reference to the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are intended to illustrate the principles of the present disclosure, but are not intended to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but rather includes all technical solutions within the scope of the claims.

[0026] The present disclosure provides these embodiments in order to make this disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values ​​set forth in these embodiments should be interpreted as merely exemplary, and not as limiting.

[0027] It should be noted that, in the description of this disclosure, unless otherwise specified, "plurality" means greater than or equal to two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are intended solely to facilitate and simplify the description of this disclosure, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0028] In addition, the terms "first," "second," and similar terms used in this disclosure do not denote any order, quantity, or importance, but are merely used to distinguish different parts. "Perpendicular" does not mean perpendicular in the strict sense, but rather means within the tolerance range. "Parallel" does not mean parallel in the strict sense, but rather means within the tolerance range. "Include" or "comprising" and similar terms mean that the elements preceding the term include the elements listed after the term, and do not exclude the possibility of also including other elements.

[0029] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in this disclosure depending on the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intervening device between the specific device and the first or second device.

[0030] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0031] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0032] Figure 1 is a flow chart of a method for coating metal on a fiber surface according to an exemplary embodiment of the present disclosure, as shown in FIG. Figure 1 As shown, the method for coating metal on the fiber surface includes the following steps:

[0033] Coating a slurry on the surface of the fiber, wherein the slurry comprises graphite powder, a coupling agent and a resin;

[0034] Allowing the slurry to solidify and form a coating on the fiber surface;

[0035] Electrostatically spraying metal powder onto the coating surface;

[0036] The metal powder is melted onto the coating surface.

[0037] In the embodiment of the present disclosure, a slurry containing graphite powder is first coated on the fiber surface. Since the graphite powder has a certain conductivity, the charge can move in its special layered molecular structure, and a large amount of static charge is accumulated by the effect of drift drag. Therefore, the formed coating has conductivity or semi-conductivity, which can enhance the electrostatic attraction of the fiber. Such electrostatic attraction is conducive to the metal powder being sprayed evenly and firmly on the coating surface through electrostatic spraying. The metal powder sprayed on the coating surface melts during the cladding process and spreads on the coating surface to form a molten film. The metal coating can be formed after the molten film is condensed.

[0038] The multiple steps adopted in the present disclosure are all conducive to forming a continuous and dense metal coating and ensuring that the metal coating has good adhesion strength. Specifically, for continuous density, the slurry can be evenly and continuously coated on the fiber surface, and the graphite powder in the slurry can be evenly dispersed in the slurry and then evenly distributed in the coating formed after the slurry is solidified, so that the coating has a uniform electrostatic attraction ability, thereby making the metal powder evenly and continuously sprayed on the coating surface during the electrostatic spraying process, and these metal powders sprayed on the coating surface can be evenly spread during the cladding process to ultimately form a uniform and continuous metal coating. For adhesion strength, graphite powder can be firmly bonded to the fiber through the reaction of the coupling agent, and electrostatic spraying can achieve good bonding strength between the metal powder and the graphite powder, thereby ultimately enhancing the adhesion strength between the metal coating and the fiber.

[0039] refer to Figure 1 Multiple rollers 50 can be used to move fibers of a certain length (e.g., tens to hundreds of meters, or even several meters to several kilometers) through the slurry coating, curing, electrostatic spraying, and cladding steps. Uncoated fibers can be unwound from the unwinding rollers and, after undergoing the aforementioned steps, become metal-coated fibers that are collected by the take-up rollers. This allows for continuous online metal coating, facilitating mass production of metallized fibers.

[0040] The methods used in the prior art, such as vacuum evaporation, chemical vapor deposition (CVD), magnetron sputtering and plasma deposition, also have the problem of easily damaging the fibers, making it difficult to obtain high-strength metallized glass fibers, as well as problems such as expensive equipment, high processing temperature, complex process, the need for additional materials in the post-processing process, and the need for highly dangerous reactive gases. Compared with these methods, the electrostatic spraying method used in the present disclosure has the advantages of a mild development environment, easy powder recovery and controllable coating thickness, which can reduce or avoid damage to the fibers. The slurry coating, curing, electrostatic spraying and cladding processes involved in the present disclosure are relatively simple and easy to operate, and do not require the use of highly dangerous gases. For the molten metal hot dip plating method used in U.S. Patent No. 4,390,589, the holes on the interface between the glass fiber and the metal are an inherent defect of the method. The reason is that the fluid dynamic instability of the glass fiber melt flow near the meniscus of the molten aluminum liquid inlet causes oscillations in the form of standing waves on the meniscus of the melt. Compared with U.S. Patent No. 4,390,589, the present disclosure can avoid the hole problem caused by molten metal hot dip plating.

[0041] In some embodiments, the fiber can be a non-metallic fiber, such as glass fiber, carbon fiber, quartz fiber, silicon carbide (SiC) fiber, basalt fiber, etc., so that the method of the present disclosure can provide the non-metallic fiber with the properties of metal, improve the mechanical properties of the non-metallic fiber and provide photoelectric properties. The present disclosure does not specifically limit the glass fiber. The glass fiber can be E-glass fiber, C-glass fiber, E-CR glass fiber, Advantex glass fiber, S-glass fiber, R-glass fiber and T-glass fiber, etc. In some embodiments, PPG Industries' HYBON_2032E-glass fiber can be used. The diameter of the glass fiber is 12 to 20 μm, and the linear thermal expansion coefficient is 4.8×10 -6 cm / cm·K, specific heat of 0.19 cal / g·K, thermal conductivity of 0.86 kcal / m·K, and softening temperature of 860°C. In some embodiments, the fibers may be metal fibers. The methods of the present disclosure can be used to plate a metal surface with another metal. The properties of the two metals differ, thereby obtaining a composite material with comprehensive properties. In the embodiments of the present disclosure, the metal may be any suitable pure metal or alloy, including but not limited to aluminum, copper, zinc, bismuth, tin, lead, indium, and the like.

[0042] In some embodiments, the graphite powder is nano-scale ultrafine graphite powder. The particle size of the ultrafine graphite powder can be 0.5 to 3 μm, for example, 0.5 to 1 μm. The compacted density of the ultrafine graphite powder is about 1.6 to 1.9 g / cm 3 , the specific surface area is about 1.0~10m 2 / g, and the ultrafine graphite powder has a nearly spherical particle shape. The use of ultrafine graphite powder ensures a more dense and secure distribution on the fiber surface, further improving the continuous density and adhesion strength of the final metal coating. The nano-scale ultrafine graphite powder used in the embodiments of the present disclosure is not particularly limited, and commercially available nano-scale ultrafine graphite powder reagents, such as Sigma-Aldrich 282863 ultrafine graphite powder, can be used.

[0043] In embodiments of the present disclosure, the coupling agent can be any coupling agent that can firmly bond the graphite powder to the fiber through a chemical reaction. In some embodiments, when the fiber is a fiber having uncondensed free silanol functional groups on the surface (e.g., glass fiber), the coupling agent can be a siloxane coupling agent and / or an epoxy silane coupling agent. There are some uncondensed free silanol functional groups on the surface of the glass fiber, and there are some chemically reactive hydroxyl groups on the surface of the graphite powder. Through the chemical reaction of the siloxane coupling agent and / or the epoxy silane coupling agent, the graphite powder and the glass fiber can be firmly bonded together in the form of a chemical bond. The coupling agents that can be used in the embodiments of the present disclosure include, but are not limited to, at least one of γ-methacryloxypropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, γ-epoxypropyltrimethoxysilane, γ-epoxypropyl(methyl)diethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, and γ-chloropropyltrimethoxysilane.

[0044] In some embodiments, before applying the slurry, the method further comprises: acid-treating the fibers. By acid-treating the fibers (e.g., glass fibers), the number of uncondensed free silanol functional groups on the fiber surface can be increased, thereby achieving stronger bonding ability with the graphite powder.

[0045] In the embodiments of the present disclosure, the resin acts as a carrier, allowing the graphite powder to be distributed therein. The resin also has a certain adhesive effect, adhering the graphite powder to the fiber surface. In some embodiments, the resin is a low molecular weight resin, having a molecular weight of less than 5000. By using a low molecular weight resin, the resin can ensure good fluidity, that is, the resin viscosity is controlled within a certain range, preventing the graphite powder in the slurry from agglomerating; and it can also ensure that the resin can be cured or carbonized at a relatively low temperature (no higher than 300°C).

[0046] In the embodiments of the present disclosure, applicable low molecular weight resins may include oligomeric epoxy resins, oligomeric polyacrylates, oligomeric polyvinyl pyrrolidone, oligomeric polyamides, hydroxyethyl acrylate, oligomeric hydroxyethyl methacrylate, oligomeric isooctyl acrylate, oligomeric N-vinyl pyrrolidone, oligomeric epoxy acrylates, and oligomeric amino acrylates. In some embodiments, oligomeric epoxy resins with an epoxy value of 1 to 1.5 may be used. The number average molecular weight of the oligomeric epoxy resin may be 500 to 1000, for example, 550 to 750; the room temperature viscosity of the oligomeric epoxy resin may be 500 to 1300 mPa·s, for example, 800 to 1000 mPa·s. An example of an oligomeric epoxy resin having the above characteristics may be Olin Technology DER6224 low molecular weight epoxy resin. In some embodiments, the low molecular weight epoxy resin may contain an epoxy curing agent such as triethanolamine or other additives.

[0047] In some embodiments, on a dry basis, in the slurry, the weight ratio of graphite powder, coupling agent and resin is (50-80): (5-10): (10-25). By such a ratio, it is possible to ensure that the graphite powder occupies a larger proportion to provide sufficient conductivity and firmly bond to the fiber, while ensuring that the amount of coupling agent can be used to promote the chemical reaction between the graphite powder and the fiber and that the resin can provide a good carrier effect in sufficient quantity. In general, such a ratio can ensure sufficient use of graphite powder, improve the uniformity of coating and increase the adhesion strength between the slurry and the fiber. In some embodiments, the slurry may also contain a certain amount of solvent, which is not particularly limited in the present disclosure. For example, the solvent may be tetrahydrofuran or ethanol. In the slurry containing the solvent, on a dry basis, the content of graphite powder may be 50-80wt%, the content of coupling agent may be 5-10wt%, the content of resin may be 10-25wt%, and the content of solvent may be 5-15wt%.

[0048] refer to Figure 2In some embodiments, the slurry is applied by passing the fibers through the slurry. This facilitates continuous slurry application, and the speed at which the fibers pass through the slurry is no more than 10 m / min, for example, 2 to 5 m / min. This ensures uniform slurry application and a sufficient amount of graphite powder. The fibers can be driven along a V-shaped path using three rollers 50. The three rollers 50 are also arranged in a V-shape, including a first roller, a second roller, and a third roller arranged sequentially along the fiber's travel direction. The second roller is located at the lowest position and positioned within the slurry, while the first and third rollers are located at a higher position and can be positioned above the slurry. The fibers are introduced into the slurry via the first roller, sizing and finishing is performed on the second roller, and then discharged from the slurry via the third roller, completing the slurry application and ensuring uniform and stable coating. The slurry application can be performed in an air atmosphere, and the temperature during the slurry application can be between 20°C and 70°C, for example, between 50°C and 60°C, to ensure that the slurry is used in an appropriate temperature environment.

[0049] In the embodiment of the present disclosure, the surface density of graphite powder on the fiber surface is about 0.1×10 -5 g / cm 2 to 1×10 -5 g / cm 2 , for example, 0.5×10 -5 g / cm 2 to 0.8×10 -5 g / cm 2 , thus ensuring that the fiber surface resistivity after slurry solidification is not higher than 10 5 Ω·cm, with good electrostatic attraction ability. The surface density of graphite powder on the fiber surface can be adjusted by adjusting the slurry ratio, graphite powder particle size, fiber running speed, etc.

[0050] In some embodiments, the resin contains an ultraviolet (UV) photoinitiator, such as 2,2-dimethoxy-1,2-diphenylethane-1-one, etc., so that ultraviolet radiation can be used to trigger in-situ polymerization of the slurry on the fiber and strengthen the connection between the graphite powder and the fiber. The resin may also contain an epoxy curing agent such as triethanolamine, and the mass of the epoxy curing agent and the photoinitiator is not more than one percent of the total mass of the low molecular weight resin. In the embodiment where the resin contains an ultraviolet photoinitiator, the step of curing the slurry may include: subjecting the fiber coated with the slurry to infrared radiation and ultraviolet radiation, and placing the fiber coated with the slurry in an inert gas environment during the ultraviolet radiation. The slurry can be quickly cured by infrared radiation, which is suitable for continuous production of metallized fibers on an industrial scale. The chemical link between the graphite powder and the fiber can be triggered by ultraviolet radiation, further strengthening the bonding between the graphite powder and the fiber, which is beneficial to improving the adhesion strength of the final metal coating. The fiber coated with the slurry is placed in an inert gas environment during the ultraviolet radiation to prevent oxidation damage to the graphite powder. In some embodiments, the infrared radiation temperature is 150°C to 300°C, for example, 150°C to 200°C; the infrared radiation distance is 5cm to 30cm, for example, 10cm to 15cm; the infrared radiation power is 30kw to 36kw; and the infrared radiation curing time does not exceed 3 minutes. The ultraviolet light wavelength can be 200nm to 300nm, and the ultraviolet radiation power can be 5kw to 10kw. The inert gas environment can be a nitrogen environment, and a nitrogen flow can be introduced into the curing chamber, and the nitrogen flow rate can be 1-5m / s. Figure 2 As shown, after being coated with slurry and solidified, the fiber becomes fiber 1 and is sent to the next process via a winding roller 50.

[0051] After the slurry coating step and the slurry curing step, the fiber surface becomes conductive or semi-conductive. The surface resistivity of the fiber can be measured using, for example, a Keithley 6517A electrometer. In the embodiment of the present disclosure, the surface resistivity of the fiber after the slurry curing treatment is not higher than 10 5 Ω·cm, for example, controlled at 10 4 to 7×10 4 Within the range of Ω·cm, these values ​​are typical values ​​that can achieve better metal powder electrostatic coating effects verified by a large number of experiments disclosed in the present invention, which can make the fiber surface fully semi-conductive to maintain a stable electrostatic field, attracting negatively charged metal powder to be quickly and efficiently deposited and adsorbed on the fiber surface.

[0052] In some embodiments, electrostatically spraying metal powder onto the coating surface includes: passing the coated fiber with a positive charge through a powder spraying chamber, and spraying negatively charged metal powder onto the coating during the process. In this way, the metal powder can be attracted to the fiber under the drive of electrical and pneumatic forces and tightly adhere to the fiber surface, forming a metal powder coating layer of a certain thickness. Figure 3 Fiber 1 (fiber with a cured slurry coating) is transformed into fiber 2 (fiber with a metal powder coating layer) after electrostatic spraying. In some embodiments, the speed of fiber 1 passing through the powder spraying chamber 32 can be no greater than 1 m / min, which helps ensure uniformity and continuity of the metal powder coating layer.

[0053] refer to Figure 3 A positive charge applying unit 34 (e.g., a positive voltage output power supply) can be used to apply a positive charge to the fiber 1. The fiber 1 can be connected to the positive charge applying unit 34 via metal brushes to generate a voltage-controllable positive voltage electrostatic field. For example, the positive voltage output power supply can be a dual-channel low-voltage power supply (TPS7A39) with an output current of 150 mA, an output voltage range of 1 V to 35 V, low noise, and high PSRR (power supply rejection ratio). The positive voltage can be set to 1 V to 35 V, for example, 10 V to 20 V. A spray gun 36 (e.g., an electric spray gun) can be used to apply a negative charge to the metal powder and spray it. For example, the metal powder can be moved to the tip of the spray gun 36 under the propulsion of a nitrogen gas flow at a pressure of 0.5 MPa to 0.7 MPa. The powder is then electrostatically charged in a low current field (corona charging) at a high voltage of -20 kV to -90 kV (e.g., -30 kV to -60 kV), quickly charging the metal powder. Due to the electric repulsion between the charged metal powder particles, the metal powder disperses after leaving the spray gun 36 and is drawn to the fiber 1 under the impetus of the electrostatic field and the pneumatic force of the nitrogen flow, tightly adhering to the surface of the fiber 1 to form a metal powder coating layer of a certain thickness. The number of spray guns 36 can be two and distributed on opposite sides of the fiber 1, spraying powder from both sides, so as to quickly and evenly perform electrostatic spraying. The distance between the spray gun mouth and the fiber 1 can be 10cm to 50cm, for example 20cm to 30cm, to ensure a good spraying effect. When performing electrostatic spraying, the spraying system (for example Figure 3 The closed system (outlined by the dotted line) is filled with an inert gas (such as nitrogen) to prevent metal oxidation, has a pressure of approximately 1 standard atmosphere, a temperature of 30° C. to 60° C., and a relative humidity of less than 30%.

[0054] In some embodiments, the metal powder is nano-aluminum powder, the particle shape of the nano-aluminum powder is approximately spherical, the average particle size is 50nm to 900nm (for example, 100nm to 200nm), the purity is 99.99%, and the specific surface area is 10 to 30m 2 / g, the surface is not covered. The aluminum powder used in the present disclosure can be a commercially available nano aluminum powder reagent, such as NG04EO0202 nano aluminum powder produced by Nanografi.

[0055] In some embodiments, the step of cladding the metal powder onto the coating surface comprises: heating and melting the metal powder to form a molten film on the coating surface, and annealing the fiber with the molten film. Figure 3 After leaving the powder spraying chamber 32, the fiber 2 (the fiber with the metal powder coating layer) enters the heating furnace 42 (such as a tubular resistance furnace) for cladding. The heating temperature of the heating furnace 42 reaches the melting point of the metal powder (such as the melting point of aluminum 660°C), so that the metal powder on the fiber surface is melted by the heat and spreads on the fiber surface to form a continuous molten film and firmly adheres to the fiber surface. The temperature control accuracy of the heating furnace 42 is not greater than 1°C, and the time for the fiber to pass through the heating furnace 42 can be 3 minutes to 9 minutes. The heating and melting of the metal powder can be carried out in an inert gas (such as nitrogen) atmosphere to prevent metal oxidation. The nitrogen flow rate entering the heating furnace 42 can be 1 to 3 m / s. The fiber with the molten film further enters the annealing furnace 44 for annealing. The temperature gradually transitions from 600°C to 100°C, so that the molten film is solidified and finally a fiber with a metal coating is obtained. The mechanical strength of the fiber can be improved by annealing.

[0056] Figure 2 and Figure 3 Schematic diagrams of different partial structures of a device for coating metal on a fiber surface according to an exemplary embodiment of the present disclosure are shown. Figure 2 and Figure 3 The device for coating metal on the fiber surface includes: a slurry tank 10, which is used to accommodate a slurry containing graphite powder, a coupling agent and a resin; a curing mechanism 20, which is used to cure the slurry; an electrostatic spraying mechanism 30, which includes a powder spraying chamber 32, a positive charge applying part 34, and a spray gun 36, which is used to apply a negative charge to the metal powder and spray it; a cladding mechanism 40, which includes a heating furnace 42, which can heat the metal powder to a molten state; and a plurality of rollers 50, which are used to drive the fiber to move and pass through the slurry tank 10, the curing mechanism 20, the powder spraying chamber 32 and the heating furnace 42 in sequence.

[0057] In some embodiments, reference Figure 2 , three rollers 50 are arranged in a V-shape and are disposed in the slurry tank 10. The three rollers 50 include a middle roller disposed at a lower position and two side rollers disposed on both sides of the middle roller and located at a higher position. In some embodiments, the curing mechanism 20 includes a curing chamber 22 and an emitting unit for emitting infrared and ultraviolet rays into the curing chamber 22. In some embodiments, reference Figure 3, the electrostatic spraying mechanism 30 also includes a powder tank 31 for storing metal powder and a gas cylinder 33 for storing gas (such as compressed nitrogen) connected to the spray gun 36, which is used to provide metal powder and airflow to the spray gun 36. The number of spray guns 36 can be two and they are arranged relatively. The electrostatic spraying mechanism 30 can also include a feed hopper, an electrostatic power supply, a controller, an overspray powder collection unit and a powder recovery unit, etc. The multiple components included in the electrostatic spraying mechanism 30 can be connected by hoses and cables and all necessary regulators and accessories. In some embodiments, the cladding mechanism 40 also includes an annealing furnace 44, and a plurality of rollers 50 also drive the fiber through the annealing furnace 44.

[0058] Figure 4 is a cross-sectional view of a metallized fiber 100 according to an exemplary embodiment of the present disclosure. Figure 4 As shown, the metallized fiber 100 includes: a fiber body 101; a coating 103 provided on the surface of the fiber body 101, the coating 103 is a solidified product of a slurry, and the slurry contains graphite powder, a coupling agent and an adhesive; a metal cladding layer 105 provided on the surface of the coating 103, and the metal cladding layer 105 is obtained by cladding metal powder electrostatically sprayed onto the surface of the coating 103.

[0059] In summary, through the technical solution disclosed in the present invention, metallized fibers can be prepared, the mechanical strength of the fibers can be greatly improved, and the application range of the fibers can be expanded; the complex design of the inert gas protection system can be avoided, the use of highly dangerous gases can be avoided, the cost of production equipment can be reduced, the safety of production can be increased, and mass production can be carried out in an economical and inexpensive manner; the prepared metallized fibers can obtain a uniform, continuous and dense metal coating with good electrical properties; the prepared metallized fibers can avoid the generation of holes at the metal-fiber interface, and the metal coating has strong adhesion.

[0060] The following describes the specific examples and comparative examples.

[0061] Example 1

[0062] The method of coating aluminum on the surface of glass fiber is carried out according to the following steps, wherein the glass fiber is HYBON_2032 glass fiber, the diameter of the glass fiber is 20 μm, and the softening temperature is 860° C.

[0063] Step 1: Coat the glass fiber with slurry in air. The slurry contains nano-scale ultrafine graphite powder, coupling agent, low molecular weight epoxy resin and solvent. The average particle size of nano-scale ultrafine graphite powder is about 0.6μm, and the compacted density is about 1.6g / cm 3 , with a specific surface area of ​​about 6m 2 / g. The coupling agents are γ-methacryloxypropyltrimethoxysilane and γ-epoxypropyltrimethoxysilane, with a mass ratio of 1:1. The low molecular weight epoxy resin is DER6224 low molecular weight epoxy resin, with a number average molecular weight of approximately 700 and a room temperature viscosity of 800 mPa·s. The low molecular weight epoxy resin contains triethanolamine and a UV photoinitiator, 2,2-dimethoxy-1,2-diphenylethane-1-one, each of which accounts for 0.5% of the total mass of the low molecular weight epoxy resin. The solvent is tetrahydrofuran. Nano-scale ultrafine graphite powder, coupling agent, low molecular weight epoxy resin, and tetrahydrofuran are mixed in a mass ratio of 14:1:3:1 to prepare a slurry. The slurry is applied to the glass fiber in an air atmosphere at 50°C. The glass fiber passes through the slurry tank at a speed of approximately 3 m / min.

[0064] Step 2: After being coated with the slurry, the glass fiber enters a curing chamber for rapid far-infrared curing. Simultaneously, to strengthen the bond between the ultrafine graphite powder and the glass fiber, UV light is applied to the chamber, triggering a chemical bond between the graphite powder and the glass fiber through high-energy UV light. The far-infrared radiation temperature is 200°C, the infrared radiation distance is 10 cm, and the infrared curing time is approximately 3 minutes. The UV light has a wavelength of 200 to 300 nm and a power of 10 kW. A nitrogen flow is introduced into the curing chamber to prevent oxidative damage to the graphite powder. The nitrogen flow rate is approximately 2 m / s.

[0065] Step 3: Electrostatically coat the glass fiber with nano-aluminum powder after coating the slurry and curing. The nano-aluminum powder particles are approximately spherical in shape, with an average particle size of 110nm, a purity of 99.99%, and a specific surface area of ​​20m 2 / g, with no surface coverage. The glass fiber is connected to a positive voltage output power supply via a metal brush, generating a voltage-controllable positive electrostatic field of 10V. The spraying system is filled with nitrogen, with a pressure of approximately 1 standard atmosphere, a temperature of 30°C, and a relative humidity of less than 30%. Driven by a nitrogen flow at a pressure of 0.5 MPa, the nano-aluminum powder moves to the tip of the electric spray gun and is electrostatically charged at a high voltage of -60 kV in a low current field (corona charging). The distance between the electric spray gun nozzle and the glass fiber is approximately 25 cm. The negatively charged aluminum powder is drawn toward the glass fiber by the electrostatic field and the pneumatic force of the nitrogen flow. The axial movement speed of the glass fiber in the powder spraying chamber is approximately 1 m / min. When the glass fiber is immersed in the cloud of nano-aluminum powder, the charged aluminum powder is attracted to the glass fiber by the electric and pneumatic forces and tightly adheres to the glass fiber surface, forming an aluminum powder coating layer of a certain thickness.

[0066] Step 4: The aluminum-coated glass fiber is pulled from the spray chamber into a tubular high-temperature resistance furnace and then into an annealing furnace. The temperature in the tubular high-temperature resistance furnace is set to 660°C, with a temperature control accuracy of ≤±1°C and a nitrogen flow protection (flow rate of 1m / s). The glass fiber passes through the resistance furnace for approximately 5 minutes, during which the nano-aluminum powder melts to form a continuous film that firmly adheres to the surface of the glass fiber. The aluminum-coated glass fiber gradually transitions from 600°C to 100°C in the annealing furnace, where the cladding aluminum solidifies to produce the aluminized glass fiber.

[0067] After obtaining the aluminized glass fibers, their electrical conductivity was measured using a PCE-COM20 conductivity tester, and all measured values ​​were averaged. The thickness of the aluminum coating on the aluminized glass fibers was measured using a Mitutoyo Digital Palmer coating thickness gauge, with nine equally spaced measurements taken on the fiber and the average taken. The adhesion of the metal coating was tested using a NanoTest Vantage micro-nanoindentation scratch tester. The cross-sectional morphology of the aluminized glass fibers was observed using a JSM 6510 scanning electron microscope (SEM).

[0068] Example 2

[0069] The main difference between Example 2 and Example 1 is that in Example 2, nano-scale ultrafine graphite powder, a coupling agent, a low molecular weight epoxy resin and tetrahydrofuran are mixed in a mass ratio of 8:1:3:1 to prepare a slurry.

[0070] Comparative Example 1

[0071] The main differences between Comparative Example 1 and Example 1 are: the slurry of Comparative Example 1 does not contain a coupling agent, the low molecular weight epoxy resin of Comparative Example 1 does not contain a UV photoinitiator 2,2-dimethoxy-1,2-diphenylethane-1-one, and the mass of the curing agent triethanolamine is 1% of the total mass of the low molecular weight epoxy resin; and UV lamp irradiation is not performed in step 2.

[0072] Comparative Example 2

[0073] The main difference between Comparative Example 2 and Example 1 is that the low molecular weight epoxy resin in Comparative Example 2 does not contain the UV photoinitiator 2,2-dimethoxy-1,2-diphenylethane-1-one, and the mass of the curing agent triethanolamine is 1% of the total mass of the low molecular weight epoxy resin.

[0074] In Example 1, after the glass fiber is coated with the slurry and cured, its surface becomes semi-conductive. The surface density of the ultrafine graphite powder on the glass fiber surface is about 0.5×10 -5 g / cm 2The surface resistivity of the glass fiber was measured using a Keithley 6517A electrometer. The surface resistivity of the glass fiber after the coating slurry was cured was about 6×10 4 Ω·cm.

[0075] Figure 5 is a scanning electron microscope image of the cross section of the aluminum-coated glass fiber prepared in Example 1. Figure 5 As shown, the aluminum-coated glass fiber includes an innermost glass fiber body and an outermost aluminum coating, and an interface coating formed after the slurry is solidified exists between the glass fiber and the aluminum coating.

[0076] The test results of relevant parameters of the aluminum-coated glass fibers of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 are shown in Table 1.

[0077] Table 1 Comparison of properties of aluminum metallized fibers

[0078]

[0079] As shown in Table 1, both Examples 1 and 2 achieve good density and adhesion strength of the aluminum coating. However, Example 2 reduces the amount of graphite powder used, resulting in poorer density, conductivity, and adhesion strength of Example 2 than Example 1. Compared with Example 1, the slurry of Comparative Example 1 does not contain a coupling agent, the resin does not contain a UV photoinitiator, and UV lamp irradiation is not performed, resulting in poor coating thickness, density, conductivity, and adhesion strength of Comparative Example 1. Compared with Example 1, the resin of Comparative Example 2 does not contain a UV photoinitiator, resulting in the coating density, conductivity, and adhesion strength of Comparative Document 2 being inferior to those of Example 1.

[0080] Thus far, various embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0081] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. In particular, as long as there are no structural conflicts, the various technical features mentioned in the various embodiments may be combined in any manner.

Claims

1. A method for coating metal on the surface of a fiber, characterized in that: include: Coating a slurry on the surface of the fiber, wherein the slurry comprises graphite powder, a coupling agent and a resin; Allowing the slurry to solidify and form a coating on the fiber surface; electrostatically spraying metal powder onto the coating surface; The metal powder is melted onto the surface of the coating; On a dry basis, in the slurry, the weight ratio of the graphite powder, the coupling agent, and the resin is (50-80):(5-10):(10-25).

2. The method according to claim 1, wherein The particle size of the graphite powder is 0.5 to 3 μm; and / or the coupling agent is a siloxane coupling agent and / or an epoxy silane coupling agent; and / or the molecular weight of the resin is less than 5000.

3. The method according to claim 1, wherein Applying the slurry by passing the fiber through the slurry, wherein the fiber passes through the slurry at a speed of no more than 10 m / min; and / or Before applying the slurry, the method further comprises: treating the fiber with acid.

4. The method according to claim 1, wherein The surface density of the graphite powder on the fiber surface is 0.1×10 -5 g / cm 2 to 1×10 -5 g / cm 2 and / or forming the surface resistivity of the fiber having the coating layer not higher than 10 5 Ω·cm.

5. The method according to claim 1, wherein The resin contains an ultraviolet initiator, and curing the slurry includes subjecting the fiber coated with the slurry to infrared radiation and ultraviolet radiation, and placing the fiber coated with the slurry in an inert gas environment during the ultraviolet radiation.

6. The method according to claim 1, wherein The electrostatic spraying of metal powder onto the coating surface comprises: The fiber formed with the coating is made to be positively charged and pass through a powder spraying chamber, and the negatively charged metal powder is sprayed onto the coating during the passing process; and / or The step of cladding the metal powder onto the coating surface comprises: The metal powder is heated to melt and form a molten film on the surface of the coating layer, and the fiber formed with the molten film is annealed.

7. A metallized fiber (100), characterized in that include: Fiber body (101); a coating (103) provided on the surface of the fiber body (101), wherein the coating (103) is a solidified product of a slurry, wherein the slurry comprises graphite powder, a coupling agent, and a resin; a metal cladding layer (105) provided on the surface of the coating (103), the metal cladding layer (105) being obtained by cladding metal powder electrostatically sprayed onto the surface of the coating (103); On a dry basis, in the slurry, the weight ratio of the graphite powder, the coupling agent, and the resin is (50-80):(5-10):(10-25).

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