Preparation Of Silver-coated Talc Powder And Its Applications In Functional Textiles

Silver is an important precious metal, it has excellent conductivity and antibacterial activity. Nano-silver not only has the nature of the metal silver, but also combines the unique characteristics of nano-materials, such as the features of strength, heat, light, electricity, etc, which will ensure its wide application in many areas including textiles. However, nano-silver powder costs much to prepare and it is difficult to disperse and control particle size and morphology. The nano-silver coated powders can not only save the amount of silver, but also be easy to disperse and the thickness, pattern, content of the deposition of silver are also easy to control. Furthermore, the silver-coated powder can be used as a functional agent to enable fabrics antibacterial, anti-static, and anti-ultraviolet through fabric coating finish. In this context, a kind of inorganic mineral materials - talc powder was used as a carrier in this paper, which has a large source and low price and it was silver-coated through electroless plating.The conditions of the plating were studied, as well as the effects of plating parameters, surface modification and surfactants on the plating process and the effects of the deposion. Ultimately, the surface of the talc powder was coated by a more complete and dense layer of nano-silver particles. The prepared silver-coated talc powder was used for nylon fabric's coating finish and its applications in antibacterial, anti-static and anti-ultraviolet functional textile products were studied.Main contents and conclusions are as follows:(1) During the pre-treatment process of silver plating, the talc was etched by HF and the coarsening time was determined to be 20min through the SEM observation of surface morphology. It were found that the activated powder had deeper color if the amount of SnCl₂·2H₂O was increased and the time for sensitization was extended properly. However, the evenness of the surface of the coated powder was decreased with excessive amount of SnCl₂·2H₂O, so the process of sensitization in this experiment was chosen as 20g/L SnCl₂·2H₂O + 50mL/L HCl with 15min. Activation process adopted 2g/L silver nitrate activating solution with 20min. (2) In the process of electroless silver plating, three kinds of reducing agents were studied: formaldehyde, glucose, potassium sodium tartrate. It was found that different reducing agents had different coating morphology, and the surface of the silver-coated powder was most complete and compact with the the highest silver content when using formaldehyde as reducing agent .The crystal structure of the deposits were all face-centered cubic structure and the fastness of the deposits were all good. With the formaldehyde formula, the silver-coated talc had the best conductivity and the rate of chemical silver reaction was also the fastest.(3) With formaldehyde as a reducing agent, the way of silver ammonia dropping into the bath was chosen and the conditions of silver plating including temperature, pH, concentration, load, reaction time were explored. As a result, the best silver conditions were concluded: temperature 20²5℃, silver Ammonia solution pH =11.7, the concentration of silver nitrate 10g/L, the concentration of formaldehyde 13mL/L, powder loading 25g/L, the reaction time 60min.(4) The surface of talc powder had increased active sites after activation, and more complete and compact silver deposition was achieved after surface modification by aminosilane coupling agent. Surfactants added into the plating solution had various effects on the completeness and particle sizes of the deposited silver; with completeness in descending order of SDBS(sodium dodecyl benzene sulfonate), SDS(Sodium dodecyl sulfate), PEG(Polyethylene glycol) and PVP(Polyvinylpyrrolidone), and particle size in descending order of PEG, SDS, SDBS, and PVP.(5) With the optimal conditions, the silver-plated talc was made and it was used for nylon fabric's coating finishing , and then the antibacterial, anti-ultroviolet and anti-static properties of the coated fabric with different silver content were researched. The results shown that with 0.5% silver content, bacteriostatic ratio was larger than 90%; with silver content of 1.0².0%, the ultraviolet protection factor was 30⁵0; with silver content of 1.5%, the half static decay lifetime was less than 10s.