| Development and popularity of the Internet and the human‘s pursuit to facilitate life accelerated the development and prosperity of things networking technology. Internet of things technology plays an important role in delivery logistics management whose target is to achieve goods tracking and targeting and to delivery information, and radio frequency identification(RFID) technology is a key technology for the Internet of Things. Antenna is a key part of the RFID tag, and its production methods reformed thanks to the development of printed electronics technology, wherein the conductive ink research and development has great significance in reducing the manufacturing cost of antenna.This thesis aims to develop nano-silver ink with both high electrical conductivity and good mechanical resistance properties. Polyvinyl pyrrolidone(PVP) capping balls, wires, and plate-like nano-silver were prepared and high concentration of nano-silver ethanol dispersions were obtained by centrifugation, washing, redispersion, and rotary evaporation process. Nano-silver dispersion liquid, solvent and acrylics resin were used to make UV conductive ink, and the effect of morphologies of nano-silver on ink conductive properties and mechanical properties of the ink were investigated.First, in the liquid phase reduction method, hydrated hydrazine and silver nitrate were used to prepare PVP capping spherical nano-silver with small and uniform size particles. Discussion were given on the kinds of solvent, the molar ratio of PVP to silver nitrate, the impact of hydrazine hydrate concentration and reaction temperature on the particle size of the silver. As a result, the silver nitrate in ethanol solution, under the condition of PVP to silver nitrate(molar ratio) was 1.5, the concentration of hydrazine hydrate 3.23% ethanol by volume, the reaction temperature 80℃, magnetic vigorous stirring, and the dropping rate of hydrazine hydrate were controlled to prepare spherical nano-silver whose particle size distribution is 20-60 nm and average particle diameter is 35 nm.Then, the polyol method, which is to realize reduction of silver nitrate with ethylene glycol under high-temperature reflow, was used to prepare PVP capping silver nanowires, and effects of the reaction time, the molar ratio of PVP to silver nitrate, PVP molecular weight and reaction temperature on silver nanowires synthesis were discussed. As a result, when the PVP K30 to silver nitrate(molar ratio) was 6, ethylene glycol reacting with silver nitrate for 1h at 160℃ high temperature with reflow, finally silver nanowires with cross-sectional diameter of about 40 nm and aspect ratio of up to 250 were synthesized.Finally, use sodium borohydride reduction with silver nitrate, hydrogen peroxide as etching agent, sodium citrate as complexing agent and PVP as stabilizer to synthesize nearly triangle nano-silver plates with side length from 70 nm to110 nm and thickness from 20 nm to 30 nm.The nano-silver dispersions in proportion were redispersed in mixed solvent system consisting of ethylene glycol and isopropanol, UV nano-silver conductive ink was then formed by adding acrylic acid ester. Comparative analysis of the conductivity and mechanical properties of UV conductive ink layer on paper were done. As a result, when the silver solids content was 66.5 wt% solids content of a conductive ink, ink with pure spherical silver showed conductivity of 0.82×105 S/m, ink with spherical silver doping equal ratio of silver wires showed conductivity of 2.1×105 S/m, while conductivity of ink doping with the equal proportion of silver balls, silver wires, silver plates reached as high as 2.73×105 S/m. Ink layer with silver balls, silver wires, and silver flakes can form perfect conductive paths, which significantly improved the conductivity. When testing the ink film resistance to tearing, abrasion resistance and bending performance, silver wires and silver plates were also found to have significantly improved the mechanical properties of the ink. |
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