Research On The Preparation Of Metallized Conductive Fiber

Metallization Conductive Fibers combine the characteristics of fibers and metals. Comparedwith other conductive fibers, they have the advantages of low density and excellent conductivity.With good flexility and cohesive property, Metallization Conductive Fibers have flexiblereprocessing formability, and can be easily blended with common fibers into yarns. Furthermore,by weaving the yarns to cloth as conductive, anti-static or electromagnetic shielding materials, itcan significantly improve hand feeling and permeability of functional materials, also cut the cost.Metallization Conductive Fibers are widely used in the field of anti-static, electromagneticshielding, anti-heat radiation, antibacterial, sensor, smart textiles, reflection and absorptionultraviolet and infrared radiation, etc.The electroless plating has the advantages of wide substrate and hermetically uniformcoating, while the process of electroplating has simple equipment. By combining the technologyof electroless plating and electroplating together, the thesis successfully prepared tin-coppercoated conductive polyamide fibers with high property and low cost. Activation is the keyprocedure of electroless plating of nonmetallic substrate, and the activation effect will affect theplating effect and the quality of coating directly. The thesis padded adhesive on the surface offibers, and dried the adhesive into film under a certain temperature and time. The film not onlycould combine with substrate firmly, but also could react with the metal ions which can catalyzethe electroless plating. Then, the fibers would be activated by reducing the metal ions. Thisexplorative idea breakthrough current activation method and will provide guiding significance tothe research and application of electroless plating on nonmetallic substrate. In order to verify thefeasibility of the above activation method, the thesis padded self-made adhesive A on the fiberssurface and reacted with PdCl2. The fibers were then activated by the reduction of NaBH4. Theresult shows that the fibers could be successfully copper electroless plated by the activationmethod. Then, the thesis improved the activation process. We prepared adhesive B, used Aginstead of Pd as the catalytic metal which has much lower price, and used HCHO in the copperelectroless plating bath to reduce the Ag+on surface of fibers directly. The result shows that theimproved activation method was also feasible and effective. It reduced the preparation cost andsimplified technology. To prevent the oxidation of copperplating layer and enhance the practical performance of copper plating fiber, tin electroplating was processed on electroless copper platedfibers to obtain tin-copper coated metallization conductive fibers. The details of researchs andconclusions are as follows:1. The adhesive A was prepared, and could complex with Pd2+effectively. The adhesive waspadded onto the fiber which endowed the fibers with the fuction of fixing Pd2+. The fibers werethen activated by the in-situ reduction of Pd2+by NaBH4and an ultrafine Pd catalytic layer wascoated on the surface of the fibers. By the “anchoring effect” of the adhesive, the Pd layer wouldneither absciss nor deposite, so that it could catalyst copper electroless plating efficiently. Byplated the activated PA6fibers in the copper electroless plating bath, we obtained copper platedPA6fibers which surface were coatd with hermetically uniform layers. The resistivity of copperplated PA6fibers was2.20×10-4·cm. The copper layer and the PA6substrate formed obviousskin-core structure with good adherence stability. The average grain size of copper was19.9nm.2. The adhesive B was prepared, and could react with AgNO3effectively. The adhesive waspadded onto the fiber which endowed the fibers with the fuction of fixing Ag+. Put the fibersdirectly into the copper electroless plating bath after reacted with AgNO3and heat to50℃.Because of the reduction of HCHO in the bath, the Ag+was reduced into Ag priority. Meanwhile,the Ag could further initiate copper electroless plating and deposite the Cu onto the fibers.Therefore, a uniform and ultrafine Ag/Cu composite catalytic layer was coating on the surface ofthe fibers, and it could continuously auto catalyst copper electroless plating. With the increasingof time, the particles increased and linked into sheet shape on the surface of the fibers. Then,hermetically uniform copper layers were obtained, and formed obvious skin-core structure withgood adherence stability. Furthermore, the effect of adhesive content, modifier amount,temperature and time of modification and plating time on the resistivity of copper plated fiberswere investigated. Under the condition of30g·L-1adhesive content,5g·L-1modifier amount,80℃modification temperature,10min modification time and30min plating time, theresistivity of the copper electroless plated PA6fibers was as low as7.27×10-5·cm and theweight gain rate was60%. The average grain size of copper was16.4nm.3. The copper electroless plated PA6fibers would be very easily oxidized in the air, whichlead to the gradual decreasing of conductivity and affect the long term performance. Tinelectroplating was processed on electroless copper plated fibers to obtain tin-copper coated metallization conductive fibers to protect the copper layer. The resistivity of tin-copper coatedmetallization conductive fibers was4.23×10-5·cm and the weight gain rate was100%whenchose the potential of1V for6min as the optimal tin electroplating condition. The average grainsize of tin was32.0nm. Outer tin layer and inner copper layer formed obvious double-layerskin-core structure with the PA6substrate, and also they had good adherence stability with eachother phases. Because of the special structure, tin-copper coated metallization conductive fibersnot only had excellent conductivity, but also enhanced its antioxidant capacity and the practicalperformance.