The Study Of Electroless Ag Plating Process On Polyamide 6 And Test Methods Of Shielding Effectiveness

With the increasing development of electronic technology, the use of electronic products and communication instruments increase, they are able to engender electromagnetic radiation more or less, electromagnetic radiation has been a problem for the lifetime and efficiency of the instruments. The demand of products about electromagnetic shielding increases day by day, the kind of products is usually manufactured by metal coating techniques. Currently developed metal coating techniques are conductive paint,lacquers,sputter coating,sputter coating,flame and arc spraying and electroless plating. Among them, electroless plating is probably a preferred way to produce metal-coated EMI shielding textiles. This technique has advantages such coherent metal deposition, excellent conductivity and shielding effectiveness and applicability to complex shaped materials so that it can be applied to almost all fiber substances. And it can be performed at any stage of textile production such as yarn, stock, fabric and cloth. We favor the electroless plating silver fabric for its excellent conductivity, antibacterial and dazzling appearance.In this thesis, electromagnetic shielding PA6 fabric is prepared by electroless plating using glucose as reducing agent, whether electroless silver plating is feasible is studied firstly. The change of Gibbs free energy of electroless sliver plating reaction is -323.65KJ/mol under standard condition, it shows that electroless plating silver is completely feasible using glucose as reducing agent. In addition, from the angle of electrochemical analysis, the standard electromotive force of electroless sliver plating reaction is 1.251V using ammonia as complexing agent, it also shows that electroless plating silver is feasible.Afterwards, the thesis studies the pretreatment of electroless plating silver. It can increase the hydrophilic of fabric surface by degreasing using sodium hydroxide on PA6, the adhesion is better to degrease using 80g/L sodium hydroxide, 3～5 mL/L OP emulsifier under 70℃. Palladium is adsorbed on surface of PA6 fabric after sensitizing and activating using palladium colloid, which catalyzes electroless sliver plating reaction achieve successfully. Experiment shows the proper sensitization and activation condition is PdCl2 0.2g/L, SnCl2 16g/L, HCl 150 mL/L, 30℃and 5min. Based on pretreatment of electroless plating, the thesis studies the process of electroless silver plating and discusses the effect of pH value, temperature, ammonia to coating structure and shielding effectiveness of electroless plating fabric. The results show that higher pH value and temperature leaded to tight deposit, good crystal structure are obtained when pH 12.9 and 20℃. The addition of ammonia can reduce dissociative sliver ion, deposition rate and improve the structure and properties of coating. But high ammonia concentration has negative effect on electroless sliver plating, and the proper concentration is 100mL/L.At the same time the thesis studies properties of electroless silver plating on PA6, the results show that the electromagnetic shielding effectiveness is excellent, with the increase of heavy rate, electromagnetic shielding effectiveness also increases, When heavy rate reaches 30.7%, the electromagnetic shielding effectiveness can reach 20dB; The conductive performance of electroless plating fabric significantly improves, the minimum surface resistance is 19m?/sq; The UPF value of electroless plating fabric is 142.7 when pH value is 12.9, exceeding 50 remotely, it can be used as preventing ultraviolet product; With the increase of heavy rate, friction resistance color fastness of electroless plating PA6 fabric appear downward trend. The friction resistance color fastness of fabric is better when heavy rate is 15.2% and 30.7%, the level is 4.5, The Ag-plated polyamide 6 fabric has higher tensile strength, stiffness and draping,but lower air permeability than the original fabric. Besides, electroless plating silver fabric of different percentage of weight growth has different wearability, as percentage of weight growth increases, the tensile strength and stiffness increase firstly, then decrease, permeability is adverse exactly, but drape coefficient has been reduced. When percentage of weight growth is 30.7%, tensile strength and stiffness is bigger, permeability is poorer.Finally, with shielding theory of electromagnetic wave for the foundation, we design and put together a new device for testing electromagnetic shielding effectiveness, and make debugging for the device. After debugging, we test different processes PA6 fabrics by the new device, the results conform to expected requirements.