Electroless Silver Plating On Polyester Fabrics And The Protection Of Silver Coating

Electromagnetic radiation is produced by electronic products andcommunication instruments at different levels. Electromagnetic radiation not onlycause mutual interference between electronic products and endanger human health.As the functional textile materials， metallized fabrics has a wide range ofapplications in electromagnetic shielding, medical, military, clothing and other fields,with anti-electromagnetic radiation, anti-static, anti-bacterial properties. Thesilver-plated polyester fabrics has a higher conductivity and electromagneticshielding effectiveness than copper-plated and nickel-plated fabrics.On the otherhand, the conductive fabrics coated with silver is soft, breathable and antibacterial,increasingly showing great market potential.In order to get good performance silver-plated polyester fabrics, the processesof pretreatment (etching, sensitization/activation, reduction) for polyester fabricsbefore electroless silver plating were investigated to increase the hydrophilic surfaceand the catalytic activity of the fabrics.The composition of silver salt solution wasoptimized, the double silver plating technology was investigated, and self-assembledmonolayers (SAMs) to protect silver plating from changing color was discussed.The main contents are as follows:1) In the surface roughening process, NaOH solution was selected to etchpolyester fabrics’ surface. The optimized condition of roughening is175g/L NaOH,75℃,25min. At this condition, the polyester fabrics displayed uneven roughsurface, there was a large number of micro-pits and grooves on it, increasing thespecific surface area and surface activity of the fiber fabric, and increasing theadhesion and bonding strength between the fabric substrate and the silver-coating;2) The morphology, weight gain and surface resistivity of the silver-platedpolyester fabric were studied at different sensitization/activation, reduction treatment,and different composition of the silver salt solution. These values have been obtained from optimization expereiments:①sensitizing solution,20g/L SnCl2,20mL/LHCl,7.5mg/L PEG1000,30℃,15min;②silver salt solution,10g/L AgNO3,60mL/L NH3H2O,20mL/L C2H8N2,6g/L KOH,70mg/LNa2S2O35H2O;③reducingagent solution and reducing treatment solution,8g/L glucose,2.5g/L C4H4O6KNa,40ml/L C2H5OH, and75mg/L PEG1000. In this formula, the weight gain of silverplating up to36.4g/m2, the square resistance down to20～30mΩ/□. On this basis,double silver plating was researched, and the weight gain of silver-plated coating upto80.4g/m2, the square resistance down to9～15mΩ/□. The silver coatinguniformly dense covered on polyester fabrics surface.3) This silver-plated polyester fabrics was prepared in this article, with goodoxidation resistance and corrosion resistance. The color and squsre resistance arealmost unchanged after one year.4) To further improve the performance of anti-discoloration of silver coating,this paper uses L-Cys and C18H38S SAMs for protection. The assembly time andconcentration were optimised. Experiments showed that L-Cys SAMs’ protectiveeffect needs to be improved. Compared10-3mol/L to10-4mol/L C18H38S SAMs atself-assembed24h for protection, the research of electrochemical polarization curvesand impedance spectroscopy curves at pH=5.02,0.1mol/L HAc-NaAc solutionshowed C18H38S self-assembled film can be well suppressed the electrochemicalreaction process on cathode and anode surface. The accelerated corrosionexperiments and spot test showed that the C18H38S SAMs can well improve theperformance of silver coating of anti-discoloration.