Surface metallized fibers and method for making same

Abstract

The present application relates to a kind of surface metallization fiber and its preparation method, preparation method includes: fiber is washed, and the fiber after washing is carried out plasma surface treatment, obtain the fiber after processing;The fiber after processing is sensitized in sensitizer solution and is soaked, obtain the fiber after sensitization;The fiber after sensitization is activated in palladium catalyst solution and is soaked, obtain the fiber after activation;The fiber after activation is placed in metal plating solution, under the condition of reducing agent, by chemical plating mode is carried out oxidation-reduction reaction, until the surface of the fiber after activation forms metal plating, obtain the fiber of surface metallization;The fiber of surface metallization is in polyvinyl alcohol solution and is soaked film, until the surface of the fiber of surface metallization forms polyvinyl alcohol film.The fiber prepared by the method has good thermal conductivity, electrical conductivity and flexibility, stable performance during use, good forming ability.

Description

Technical Field

[0001] This invention belongs to the field of surface metallization technology of fiber materials, and specifically relates to a surface metallized fiber and its preparation method. Background Technology

[0002] Polytetrafluoroethylene (PTFE) is a polymer material with excellent comprehensive properties, exhibiting excellent resistance to high and low temperatures and chemical corrosion, as well as superior dielectric properties and a very low coefficient of friction. It is widely used as a lubricating layer in aerospace, automotive, and large machinery industries. However, PTFE also has drawbacks such as poor creep resistance, poor adhesion to other materials, poor resilience, and susceptibility to wear, which limit its further applications.

[0003] Aramid fibers possess excellent properties such as high strength, high modulus, chemical corrosion resistance, and fatigue resistance, and their composites are characterized by lightweight and high strength. However, aramid is an electrical insulating material. Aramid has low surface energy, high inertness, and lacks modifiable functional groups, resulting in poor interfacial compatibility with the matrix, which affects the mechanical properties of the composites and limits their application range.

[0004] If the surface of polytetrafluoroethylene (PTFE) fiber or aramid fiber is appropriately metallized to give it electromagnetic shielding function, PTFE fiber or aramid fiber will gain wider application value on the basis of its original advantages.

[0005] However, due to the ultra-high surface inertness of polytetrafluoroethylene and the lack of modifiable functional groups on the surface of aramid, it is difficult to form a strong metallized fiber surface on their surfaces. The metallized fibers have poor corrosion resistance and abrasion resistance, which limits their further application. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a surface-metallized fiber and its preparation method. The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides a method for preparing surface-metallized fibers, wherein the fibers include polytetrafluoroethylene fibers or aramid fibers, and the preparation method includes the following steps: The fibers are cleaned and then subjected to plasma surface treatment to obtain treated fibers. The treated fibers are immersed in a sensitizing agent solution for sensitization to obtain sensitized fibers. The sensitized fiber is activated by immersing it in a palladium catalyst solution, so that the surface of the sensitized fiber acquires a metal element as a reduction center, thereby obtaining the activated fiber. The activated fiber is placed in a metal plating solution and subjected to an oxidation-reduction reaction by chemical plating under the condition of a reducing agent until a metal coating is formed on the surface of the activated fiber, thus obtaining a surface-metallized fiber. The surface-metallized fibers are immersed in a polyvinyl alcohol solution for coating until a polyvinyl alcohol coating is formed on the surface of the surface-metallized fibers.

[0007] In one embodiment of the present invention, the plasma surface treatment time is 1 min to 15 min; The immersion sensitization time is 12h-48h; The soaking and activation time is 12h-48h; The redox reaction takes 30-180 minutes; The soaking and coating time is 3-10 minutes.

[0008] In one embodiment of the present invention, the sensitizer in the sensitizer solution includes catechol compounds, which include one or more of polydopamine and tea polyphenols.

[0009] In one embodiment of the present invention, the sensitizer solution comprises a mixed solution of polydopamine and tea polyphenols in a mixed solvent, wherein the mass ratio of polydopamine to tea polyphenols is 1:1-5, the total mass of polydopamine and tea polyphenols accounts for 5%-20% of the mass of the mixed solvent, and the mixed solvent comprises an ethanol-water mixed solution with a volume ratio of 1:1 for ethanol and water.

[0010] In one embodiment of the present invention, the palladium catalyst solution comprises an ammonium chloropalladate solution or a palladium chloride solution, wherein, When the palladium catalyst solution is the ammonium chloropalladate solution, the mass ratio of ammonium chloropalladate to water is 0.002-0.01:1; When the palladium catalyst solution is the palladium chloride solution, the mass ratio of palladium chloride to water is 0.002-0.01:1.

[0011] In one embodiment of the present invention, the metal plating solution includes a copper plating solution, and correspondingly, the reducing agent includes a formaldehyde solution, wherein... The copper plating solution is prepared as follows: NaOH, potassium sodium tartrate, sodium ethylenediaminetetraacetate, potassium ferrocyanide, and 2',2-bipyridine are added to water in sequence, and after stirring evenly, copper sulfate pentahydrate is added. The ratio of water, NaOH, potassium sodium tartrate, sodium ethylenediaminetetraacetate, potassium ferrocyanide, 2',2-bipyridine, and copper sulfate pentahydrate is 1L:14.5g:14g:19.5g:0.01g:0.02g:15g. The formaldehyde solution contains 2%-10% by volume. The volume ratio of the copper plating solution to the formaldehyde solution is 1:0.02-0.1.

[0012] In one embodiment of the present invention, the metal plating solution includes a nickel plating solution, and correspondingly, the reducing agent includes ammonia water, wherein... The nickel plating solution includes solution A and solution B. Solution A is a mixed solution of water, nickel sulfate hexahydrate, sodium citrate, and lactic acid, wherein the mass ratio of nickel sulfate hexahydrate, sodium citrate, and lactic acid is 4:2:1. Solution B is an aqueous solution of dimethylaminoborane, wherein the mass percentage of dimethylaminoborane in the aqueous solution is 0.3%-1%. The volume ratio of liquid A, liquid B, and ammonia is 20:5:1.

[0013] In one embodiment of the present invention, the thickness of the metal coating is 10 μm-100 μm; The thickness of the polyvinyl alcohol coating is 5μm-200μm.

[0014] Another embodiment of the present invention provides a surface-metallized fiber, prepared by the preparation method described in the above embodiments, comprising: a supporting substrate, a metal plating layer, and a polyvinyl alcohol coating, wherein, The supporting substrate includes polytetrafluoroethylene fiber or aramid fiber; The metal coating is bonded to the surface of the supporting substrate; The polyvinyl alcohol coating covers the surface of the metal plating.

[0015] In one embodiment of the present invention, the fineness of the polytetrafluoroethylene fiber or aramid fiber is 200D-1500D; The thickness of the metal coating is 10μm-100μm; The thickness of the polyvinyl alcohol coating is 5μm-200μm.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this invention, after depositing a metal coating on the fiber surface, the gold-plated fiber is further immersed in a polyvinyl alcohol solution to form a polyvinyl alcohol film for protection. This not only effectively improves the thermal conductivity of the fiber and increases its temperature tolerance to the working environment, but also enhances its electrical conductivity. The improved electrical conductivity also enables fabrics woven from this fiber to have considerable electromagnetic shielding effectiveness, reducing secondary pollution caused by electromagnetic wave reflection. At the same time, the metallized and coated fiber can avoid various physical and chemical corrosions during use, improving the wear resistance of the metallized fiber. It combines the fiber's inherent good corrosion resistance and abrasion resistance with strong plasticity, thereby improving the overall durability of the metallized fiber and enabling its wider application.

[0017] 2. This invention performs plasma surface treatment on fibers, using plasma to strike the fiber surface, which not only improves the cleanliness of the fiber surface, but also exposes the molecular groups on the fiber surface, improving the affinity of the fiber surface and facilitating the adhesion of molecular groups and metals during the fiber metallization process, thereby helping to form a strong metallized fiber surface. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart illustrating a method for preparing surface metallized fibers according to an embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0020] Example 1 Please see Figure 1 , Figure 1 This is a schematic flowchart illustrating a method for preparing surface-metallized fibers according to an embodiment of the present invention. The method for preparing surface-metallized fibers in this embodiment includes the following steps: S1. The fiber is cleaned and then subjected to plasma surface treatment to obtain the treated fiber.

[0021] First, the fibers are ultrasonically cleaned in an acetone solution for 30-180 minutes. Then, the fibers are removed and rinsed with distilled water. Through ultrasonic cleaning and rinsing, impurities on the fiber surface are removed.

[0022] Then, the cleaned fibers are subjected to plasma surface treatment using a plasma surface treatment machine for 1-15 minutes. During the plasma surface treatment process, the O and N plasmas strike the fiber surface, resulting in a higher degree of cleanliness and exposing the molecular groups on the fiber surface. This further cleans the fibers and improves their affinity for subsequent metallization, which is beneficial for the adhesion of molecular groups and metals during the fiber metallization process, thus facilitating the formation of a strong metallized fiber surface.

[0023] S2. The treated fibers are immersed in a sensitizing agent solution for sensitization to obtain sensitized fibers.

[0024] Specifically, the sensitizer includes catechol compounds, which include one or more of polydopamine and tea polyphenols. Correspondingly, the sensitizer solution can be a polydopamine solution, a tea polyphenol solution, or a mixed solution of polydopamine and tea polyphenols. The solvent used in the above solutions is a mixture of ethanol and water.

[0025] When the sensitizer solution is a mixed solution of polydopamine and tea polyphenols in a mixed solvent, the mass ratio of polydopamine to tea polyphenols is 1:1-5, and the total mass of polydopamine and tea polyphenols accounts for 5%-20% of the mass of the mixed solvent. The mixed solvent includes an ethanol-water mixture with a volume ratio of 1:1. For example, 0.5g of polydopamine powder and 0.5g of tea polyphenol powder are diluted with 10mL-15mL of water and 10mL-15mL of ethanol, wherein the water can be ultrapure water.

[0026] Specifically, the soaking and sensitization time is 12-48 hours. After soaking and sensitization, the fibers are taken out, washed, and dried.

[0027] In this embodiment, both polydopamine and tea polyphenols are polyphenolic substances containing a large number of hydroxyl groups. When the fiber is immersed in a sensitizer solution formed by polydopamine and / or tea polyphenols, the polydopamine and / or tea polyphenol molecules can be adsorbed onto the surface of the fiber through physical or chemical forces, making the fiber surface rich in hydroxyl groups, thereby making the fiber surface more susceptible to oxidation.

[0028] In this embodiment, when the sensitizer solution is a tea polyphenol solution, compared with a polydopamine solution, the tea polyphenol solution can significantly reduce the cost of metallization on the fiber surface. When a mixed solution of polydopamine and tea polyphenol is used, the polyphenolic substance tea polyphenol can assist polydopamine in activating the fiber surface. Compared with a polydopamine solution, it can significantly improve the activity of the fiber surface, which is beneficial to improving the adhesion of the subsequent metal coating.

[0029] S3. The sensitized fiber is immersed in a palladium catalyst solution for activation, so that the surface of the sensitized fiber obtains a metal element as a reduction center, and the activated fiber is obtained.

[0030] Specifically, the palladium catalyst solution can be an ammonium chloropalladate solution or a palladium chloride solution as the activator. When an ammonium chloropalladate solution is used, the mass ratio of ammonium chloropalladate to water is 0.002-0.01:1; when a palladium chloride solution is used, the mass ratio of palladium chloride to water is 0.002-0.01:1.

[0031] For example, 1g of palladium diammonium tetrachloride powder is diluted with 100mL-150mL of ultrapure water.

[0032] Specifically, the soaking and activation time is 12h-48h.

[0033] In this embodiment, fibers with a surface rich in hydroxyl groups are immersed in a palladium catalyst solution. The hydroxyl groups react with palladium ions to form palladium nanoparticles on the fiber surface, which increases the surface activity of the fiber.

[0034] S4. Place the activated fiber in a metal plating solution and carry out an oxidation-reduction reaction by chemical plating under the condition of a reducing agent until a metal coating is formed on the surface of the activated fiber, thus obtaining a surface-metallized fiber.

[0035] Specifically, the metal plating solution can be either a copper plating solution or a nickel plating solution.

[0036] When the metal plating solution is a copper plating solution, the preparation method is as follows: Add NaOH, potassium sodium tartrate, sodium ethylenediaminetetraacetate, potassium ferrocyanide, and 2',2-bipyridine to water in that order, stirring for 20 minutes until the solution is homogeneous. Then add copper sulfate pentahydrate. The ratio of water, NaOH, potassium sodium tartrate, sodium ethylenediaminetetraacetate, potassium ferrocyanide, 2',2-bipyridine, and copper sulfate pentahydrate is 1L:14.5g:14g:19.5g:0.01g:0.02g:15g. Correspondingly, the reducing agent used in chemical copper plating with this solution is a formaldehyde solution formed by mixing formaldehyde and water, with a formaldehyde volume percentage of 2%-10%. Furthermore, the volume ratio of the copper plating solution to the formaldehyde solution is 1:0.02-0.1.

[0037] When the metal plating solution is a nickel plating solution, it includes solution A and solution B. Solution A is a mixed solution of water, nickel sulfate hexahydrate, sodium citrate, and lactic acid, with a mass ratio of nickel sulfate hexahydrate, sodium citrate, and lactic acid of 4:2:1. This can be understood as adding nickel sulfate hexahydrate, sodium citrate, and lactic acid in a mass ratio of 4:2:1 to 1L of water and stirring until homogeneous to obtain solution A. Solution B is an aqueous solution of dimethylaminoborane, with a mass percentage of dimethylaminoborane of 0.3%-1%. Correspondingly, ammonia water with a mass percentage greater than or equal to 95% is used as the reducing agent during electroless nickel plating. Furthermore, the volume ratio of solution A, solution B, and ammonia water is 20:5:1.

[0038] Specifically, the activated fibers are placed in a metal plating bath. Under the conditions of a reducing agent, with palladium atoms as the catalyst center, a redox reaction occurs between the palladium atoms and the metal plating bath. The metal in the metal plating bath is precipitated, forming a metal coating on the surface of the fibers, thus achieving electrodeposition-free deposition. Specifically, the redox reaction time is 30 min-180 min, and the thickness of the metal coating is 10 μm-100 μm.

[0039] S5. The surface-metallized fibers are immersed in a polyvinyl alcohol solution for coating until a polyvinyl alcohol coating is formed on the surface of the surface-metallized fibers.

[0040] Specifically, polyvinyl alcohol is a white, flaky, flocculent, or powdery solid that forms a viscous solution when heated in water. Using a surface coating process, surface-metallized fibers are immersed in a polyvinyl alcohol solution with a concentration of 1 g / L-10 g / L for 3-10 minutes, then removed and dried or allowed to air dry. This results in a polyvinyl alcohol film with a thickness of 5 μm-200 μm on the surface of the surface-metallized fibers.

[0041] The surface metallization fiber preparation method of this embodiment can be applied to both polytetrafluoroethylene (PTFE) fibers and aramid fibers. Due to the extremely high surface inertness of PTFE and the lack of modifiable functional groups on the surface of aramid, chemical gold plating on both surfaces is very difficult. This embodiment successfully metallizes the surface of PTFE or aramid fibers by introducing a plasma surface treatment process and a catechol-based sensitizer (such as tea polyphenols). Simultaneously, it proposes to coat the surface of the metallized fibers with a protective film, effectively improving the poor thermal conductivity of PTFE or aramid fibers. Because of the metallic coating on the surface, fabrics woven from PTFE or aramid fibers after surface metallization will possess a certain electromagnetic shielding effectiveness. The surface coating process not only prevents the metallized fibers from being subjected to various physical and chemical corrosions during use but also improves the strength and wear resistance of the metallized fibers, thereby improving the overall durability of the metallized PTFE or metallized aramid fibers. Therefore, the fibers prepared by this method have good thermal conductivity, electrical conductivity and flexibility, stable performance during use, good forming ability, and can be well applied in various application scenarios, making them highly practical.

[0042] In summary, this embodiment, after depositing a metal coating on the fiber surface, further immerses the gold-plated fiber in a polyvinyl alcohol solution to form a polyvinyl alcohol film for protection. This not only effectively improves the fiber's thermal conductivity and increases its temperature tolerance to the working environment, but also enhances its electrical conductivity. The improved conductivity also allows fabrics woven from this fiber to have considerable electromagnetic shielding effectiveness, reducing secondary pollution caused by electromagnetic wave reflection. Simultaneously, the metallized and coated fiber can prevent various physical and chemical corrosions during use, improving the wear resistance of the metallized fiber. It combines the fiber's inherent good corrosion resistance and abrasion resistance with strong plasticity, thereby comprehensively improving the durability of the metallized fiber and enabling its wider application.

[0043] Example 2 Based on Example 1, this example provides a surface-metallized fiber, prepared by the method of Example 1, comprising a supporting substrate, a metal coating, and a polyvinyl alcohol coating. The supporting substrate comprises polytetrafluoroethylene fiber or aramid fiber; the metal coating is bonded to the surface of the supporting substrate; and the polyvinyl alcohol coating covers the surface of the metal coating.

[0044] Specifically, the fineness of the polytetrafluoroethylene fiber or aramid fiber is 200D-1500D; the thickness of the metal coating is 10μm-100μm; and the thickness of the polyvinyl alcohol coating is 5μm-200μm.

[0045] Example 3 Based on Example 1, this example further illustrates the preparation method of surface metallized fibers through the following examples.

[0046] Example 1 Taking the chemical copper plating of polytetrafluoroethylene fiber as an example, the preparation method of surface metallized fiber includes the following steps: S1. First, pre-treat the polytetrafluoroethylene (PTFE) fibers. Specifically, the pre-treatment includes ultrasonic washing with the organic solvent acetone for 180 minutes, rinsing with distilled water, and then cleaning and activating with a plasma surface treatment machine for 15 minutes.

[0047] S2. The treated polytetrafluoroethylene (PTFE) fibers are sensitized by immersing them in a mixed solution of polydopamine and tea polyphenols to obtain sensitized PTFE fibers. The mass ratio of polydopamine to tea polyphenols is 1:1, and the total mass of polydopamine and tea polyphenols accounts for 5% of the mass of the mixed solvent. The mixed solvent includes an ethanol-water mixed solution with a volume ratio of 1:1 for ethanol and water.

[0048] S3. The sensitized polytetrafluoroethylene (PTFE) fibers are activated by immersion in an ammonium chloropalladate catalyst, thereby acquiring elemental metals as reduction centers on the surface of the sensitized PTFE fibers to obtain activated PTFE fibers. The mass ratio of ammonium chloropalladate to water in the ammonium chloropalladate solution is 0.008:1.

[0049] S4. Immerse the activated polytetrafluoroethylene (PTFE) fibers in a copper plating solution for electrodeposition for 180 minutes to form a copper plating layer on the surface of the PTFE fibers. The copper plating solution is prepared as follows: add 14.5g of NaOH, 14g of potassium sodium tartrate, 19.5g of sodium ethylenediaminetetraacetate, 0.01g of potassium ferrocyanide, and 0.02g of 2'-bipyridine to 1L of water in sequence. Stir the solution for 20 minutes until homogeneous, then add 15g of copper sulfate pentahydrate. The reducing agent used in the chemical copper plating is a formaldehyde solution formed by mixing formaldehyde and water, with a formaldehyde volume percentage of 8%. The volume ratio of the copper plating solution to the formaldehyde solution is 1:0.08.

[0050] S5. After removing the copper-plated polytetrafluoroethylene fiber, wash it and dry it in a 60℃ oven for 3 hours. Then soak it in a 5g / L polyvinyl alcohol aqueous solution for 10 minutes, and then take it out and let it air dry.

[0051] The polytetrafluoroethylene (PTFE) fibers prepared as described above are conductive with a resistivity of 1.2 Ω / cm. Plain weave fabrics made from these surface-metallized PTFE fibers exhibit an electromagnetic shielding effectiveness of 34 dB and a thermal conductivity of 0.3541 W / m·K, while plain weave fabrics made from the original fibers have almost zero electromagnetic shielding effectiveness and a thermal conductivity of 0.2353 W / m·K. The surface-metallized PTFE fibers prepared using this method possess excellent thermal conductivity, electrical conductivity, and electromagnetic shielding effectiveness.

[0052] Example 2 Taking the chemical nickel plating of polytetrafluoroethylene fiber as an example, the preparation method of surface metallized fiber includes the following steps: S1. First, pre-treat the polytetrafluoroethylene (PTFE) fibers. Specifically, the pre-treatment includes ultrasonic washing with the organic solvent acetone for 3 hours, rinsing with distilled water, and then cleaning and activating with a plasma surface treatment machine for 15 minutes.

[0053] S2. The treated polytetrafluoroethylene (PTFE) fibers are sensitized by immersing them in a mixed solution of polydopamine and tea polyphenols to obtain sensitized PTFE fibers. The mass ratio of polydopamine to tea polyphenols is 1:3, and the total mass of polydopamine and tea polyphenols accounts for 5% of the mass of the mixed solvent. The mixed solvent includes an ethanol-water mixture with a volume ratio of 1:1.

[0054] S3. The sensitized polytetrafluoroethylene (PTFE) fibers are activated by immersion in an ammonium chloropalladate catalyst, allowing the surface of the sensitized PTFE fibers to acquire elemental metals as reduction centers, thus obtaining activated PTFE fibers. The mass ratio of ammonium chloropalladate to water in the ammonium chloropalladate solution is 0.003:1.

[0055] S4. Immerse the activated polytetrafluoroethylene (PTFE) fibers in a nickel plating solution for electrodeposition for 120 minutes to form a nickel plating layer on the surface of the PTFE fibers. The nickel plating solution includes solution A and solution B. Solution A is obtained by adding nickel sulfate, sodium citrate, and lactic acid to 1 L of water in a mass ratio of 4:2:1 and stirring until homogeneous. Solution B is an aqueous solution of dimethylaminoborane, with a mass percentage of 1% dimethylaminoborane. The reducing agent for electroless nickel plating is 95% ammonia water, and the volume ratio of solution A, solution B, and ammonia water is 20:5:1.

[0056] S5. After washing the nickel-plated polytetrafluoroethylene fiber, dry it in a 60℃ oven for 3 hours. Then soak it in a 10g / L polyvinyl alcohol aqueous solution for 3 minutes, and then take it out and let it air dry.

[0057] The polytetrafluoroethylene (PTFE) fibers prepared as described above are conductive with a resistivity of 1.7 Ω / cm. Plain weave fabrics made from these surface-metallized PTFE fibers exhibit an electromagnetic shielding effectiveness of 39 dB and a thermal conductivity of 0.3336 W / m·K, while plain weave fabrics made from the original fibers have almost zero electromagnetic shielding effectiveness and a thermal conductivity of 0.2511 W / m·K. The surface-metallized PTFE fibers prepared using this method possess excellent thermal conductivity, electrical conductivity, and electromagnetic shielding effectiveness.

[0058] Example 3 Taking the chemical copper plating of aramid fiber surface as an example, the preparation method of surface metallized fiber includes the following steps: S1. First, pre-treat the aramid fibers. Specifically, the pre-treatment includes ultrasonic washing with the organic solvent acetone for 3 hours, rinsing with distilled water, and then cleaning and activating with a plasma surface treatment machine for 10 minutes.

[0059] S2. The treated aramid fibers are sensitized by immersing them in a mixed solution of polydopamine and tea polyphenols to obtain sensitized aramid fibers. The mass ratio of polydopamine to tea polyphenols is 1:3, and the total mass of polydopamine and tea polyphenols accounts for 5% of the mass of the mixed solvent. The mixed solvent includes an ethanol-water mixed solution with a volume ratio of 1:1.

[0060] S3. The sensitized aramid fibers are activated by immersion in an ammonium chloropalladate catalyst, which allows the surface of the sensitized aramid fibers to acquire elemental metals as reduction centers, thus obtaining activated aramid fibers. The mass ratio of ammonium chloropalladate to water in the ammonium chloropalladate solution is 0.005:1.

[0061] S4. Immerse the activated aramid fibers in a copper plating solution for electrodeposition for 90 minutes to form a copper plating layer on the surface of the aramid fibers. The copper plating solution is prepared as follows: add 14.5g NaOH, 14g potassium sodium tartrate, 19.5g sodium ethylenediaminetetraacetate, 0.01g potassium ferrocyanide, and 0.02g 2'-bipyridine to 1L of water in sequence. Stir the solution for 20 minutes until homogeneous, then add 15g copper sulfate pentahydrate. The reducing agent used in the chemical copper plating is a formaldehyde solution formed from formaldehyde and water, with a formaldehyde volume percentage of 5%. The volume ratio of copper plating solution to formaldehyde solution is 1:0.1.

[0062] S5. After removing the copper-plated aramid fibers and washing them, dry them in a 60℃ oven for 3 hours. Then, soak them in a 5g / L polyvinyl alcohol aqueous solution for 10 minutes, and then remove them and let them air dry.

[0063] The aramid fibers prepared as described above are conductive with a resistivity of 1.6 Ω / cm. Plain weave fabrics made from these surface-metallized aramid fibers exhibit an electromagnetic shielding effectiveness of 36 dB and a thermal conductivity of 0.1762 W / m·K, while plain weave fabrics made from the original fibers have almost zero electromagnetic shielding effectiveness and a thermal conductivity of 0.1024 W / m·K. The surface-metallized aramid fibers prepared using this method possess excellent thermal conductivity, electrical conductivity, and electromagnetic shielding effectiveness.

[0064] Example 4 Taking the chemical nickel plating of aramid fibers as an example, the preparation method of surface metallized fibers includes the following steps: S1. First, pre-treat the aramid fibers. Specifically, the pre-treatment includes ultrasonic washing with the organic solvent acetone for 3 hours, rinsing with distilled water, and then cleaning and activating with a plasma surface treatment machine for 5 minutes.

[0065] S2. The treated aramid fibers are sensitized by immersing them in a mixed solution of polydopamine and tea polyphenols to obtain sensitized aramid fibers. The mass ratio of polydopamine to tea polyphenols is 1:5, and the total mass of polydopamine and tea polyphenols accounts for 5% of the mass of the mixed solvent. The mixed solvent includes an ethanol-water mixed solution with a volume ratio of 1:1.

[0066] S3. The sensitized aramid fibers are activated by immersion in an ammonium chloropalladate catalyst, which allows the surface of the sensitized aramid fibers to acquire elemental metals as reduction centers, thus obtaining activated aramid fibers. The mass ratio of ammonium chloropalladate to water in the ammonium chloropalladate solution is 0.003:1.

[0067] S4. Immerse the activated aramid fibers in a nickel plating solution for electrodeposition for 60 minutes to form a nickel plating layer on the surface of the aramid fibers. The nickel plating solution includes solution A and solution B. Solution A is obtained by adding nickel sulfate, sodium citrate, and lactic acid to 1 L of water in a mass ratio of 4:2:1 and stirring until homogeneous. Solution B is an aqueous solution of dimethylaminoborane, with a mass percentage of 0.3% dimethylaminoborane. The reducing agent for electroless nickel plating is 95% ammonia water, and the volume ratio of solution A, solution B, and ammonia water is 20:5:1.

[0068] S5. After washing the nickel-plated aramid fibers, dry them in a 60℃ oven for 3 hours, then soak them in a 10g / L polyvinyl alcohol aqueous solution for 3 minutes, and then remove and air dry.

[0069] The aramid fibers prepared as described above are conductive with a resistivity of 2.1 Ω / cm. Plain weave fabrics made from these surface-metallized aramid fibers exhibit an electromagnetic shielding effectiveness of 33 dB and a thermal conductivity of 0.1823 W / m·K, while plain weave fabrics made from the original fibers have almost zero electromagnetic shielding effectiveness and a thermal conductivity of 0.1196 W / m·K. The surface-metallized aramid fibers prepared using this method possess excellent thermal conductivity, electrical conductivity, and electromagnetic shielding effectiveness.

[0070] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing surface-metallized fibers, characterized in that, The fiber is polytetrafluoroethylene fiber or aramid fiber, and the fineness of the polytetrafluoroethylene fiber or aramid fiber is 200D-1500D; The preparation method includes the following steps: The fibers are cleaned and then subjected to plasma surface treatment to obtain treated fibers. The treated fibers are sensitized by immersing them in a sensitizing agent solution to obtain sensitized fibers. The sensitizing agent solution is a mixed solution of polydopamine and tea polyphenols in a mixed solvent, wherein the mass ratio of polydopamine to tea polyphenols is 1:1-5, and the total mass of polydopamine and tea polyphenols accounts for 5%-20% of the mass of the mixed solvent. The mixed solvent is an ethanol-water mixed solution with a volume ratio of 1:

1. The sensitized fiber is activated by immersing it in a palladium catalyst solution, so that the surface of the sensitized fiber is coated with elemental palladium, thus obtaining the activated fiber. The palladium catalyst solution is an ammonium chloropalladate solution or a palladium chloride solution; The activated fiber is placed in a metal plating solution and subjected to an oxidation-reduction reaction by chemical plating under the condition of a reducing agent until a metal coating is formed on the surface of the activated fiber, thus obtaining a surface-metallized fiber; the metal plating solution is a copper plating solution, and the reducing agent is formaldehyde solution; or the metal plating solution is a nickel plating solution, and the reducing agent is dimethylaminoborane aqueous solution. The surface-metallized fibers are immersed in a polyvinyl alcohol solution for coating until a polyvinyl alcohol coating is formed on the surface of the surface-metallized fibers.

2. The method for preparing surface metallized fibers according to claim 1, characterized in that, The plasma surface treatment time is 1 min to 15 min; The immersion sensitization time is 12h-48h; The soaking and activation time is 12h-48h; The redox reaction takes 30-180 minutes; The soaking and coating time is 3-10 minutes.

3. The method for preparing surface metallized fibers according to claim 1, characterized in that, When the palladium catalyst solution is the ammonium chloropalladate solution, the mass ratio of ammonium chloropalladate to water is 0.002-0.01:1; When the palladium catalyst solution is the palladium chloride solution, the mass ratio of palladium chloride to water is 0.002-0.01:

1.

4. The method for preparing surface metallized fibers according to claim 1, characterized in that, The copper plating solution is prepared as follows: NaOH, potassium sodium tartrate, sodium ethylenediaminetetraacetate, potassium ferrocyanide, and 2',2-bipyridine are added to water in sequence, and after stirring evenly, copper sulfate pentahydrate is added. The ratio of water, NaOH, sodium potassium tartrate, sodium ethylenediaminetetraacetate, potassium ferrocyanide, 2',2-bipyridine, and copper sulfate pentahydrate is 1L:14.5g:14g:19.5g:0.01g:0.02g:15g. The formaldehyde solution contains 2%-10% by volume. The volume ratio of the copper plating solution to the formaldehyde solution is 1:0.02-0.

1.

5. The method for preparing surface metallized fibers according to claim 1, characterized in that, The nickel plating solution includes solution A and solution B. Solution A is a mixed solution of water, nickel sulfate hexahydrate, sodium citrate, and lactic acid, wherein the mass ratio of nickel sulfate hexahydrate, sodium citrate, and lactic acid is 4:2:

1. Solution B is an aqueous solution of dimethylaminoborane, wherein the mass percentage of dimethylaminoborane in the aqueous solution is 0.3%-1%. The nickel plating solution also includes ammonia. The volume ratio of liquid A, liquid B, and ammonia is 20:5:

1.

6. The method for preparing surface metallized fibers according to claim 1, characterized in that, The thickness of the metal coating is 10μm-100μm; The thickness of the polyvinyl alcohol coating is 5μm-200μm.

7. A surface-metallized fiber, characterized in that, Prepared by the preparation method according to any one of claims 1-6, comprising: a supporting substrate, a polydopamine and tea polyphenol sensitizing layer, a palladium activation layer, a metal plating layer, and a polyvinyl alcohol coating, wherein, The supporting substrate is polytetrafluoroethylene fiber or aramid fiber; The polydopamine and tea polyphenol sensitization layer, the palladium activation layer, and the metal plating layer are sequentially bonded to the surface of the supporting substrate; The polyvinyl alcohol coating covers the surface of the metal plating.

8. The surface metallized fiber according to claim 7, characterized in that, The fineness of the polytetrafluoroethylene fiber or aramid fiber is 200D-1500D; The thickness of the metal coating is 10μm-100μm; The thickness of the polyvinyl alcohol coating is 5μm-200μm.

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