Preparation And Printing Properties Of Nano-silver/sodium Alginate Conductive Thickening System On Textiles

Sodium alginate is a kind of natural macromolecular biological polysaccharide extracted from seaweed.The molecular chain contains a large number of hydroxyl and carboxyl groups.After soluble in water,it has a certain pseudo-plasticity and shows the viscosity characteristic of shearing thinness under the action of shear stress.It is widely used as a thickener in cotton dye printing,which is easy to prepare,easy to remove paste,and does not affect the feel of the fabric.Nano-silver is an ideal material for preparing high quality conductive printing inks for textile applications because of its high conductivity and stable properties.When nano-silver is used to prepare conductive printing ink,it needs to be used together with other components such as thickener to achieve the best printing effect.There are few reports on the preparation and application of sodium alginate in nano-silver conductive printing ink,and the in-depth study on the interaction between nano-silver and sodium alginate is also relatively scarce.This paper systematically explores the effect of sodium alginate on the synthesis of silver nanoparticles.Through UV-vis spectrophotometry analysis,particle size analysis,surface Zeta potential test,stability analysis and TEM test,the effects of sodium alginate G/M ratio,concentration,degradation degree and other factors were investigated.It is found that the effect of sodium alginate on silver nanoparticles is mainly achieved by changing the particle size of the synthesized silver nanoparticles.The hydrodynamic radius of silver nanoparticles synthesized in the thickening system of sodium alginate with G/M of 0.248 is less different from that of the control group.As the concentration of sodium alginate increases,the particle size of the synthesized silver nanoparticles in the thickening system also increases.It can be seen from TEM image that the high concentration of sodium alginate encapsulates the synthesized silver nanoparticles on its macromolecular chain.With the increase of degradation degree,sodium alginate generated a lot of small molecular fragments.Although the particle size of nano-silver synthesized in the thickening system decreased to a certain extent,the stability of the system became worse because of the uneven distribution and poor stability of sodium alginate after degradation.Through TG,XRD,FT-IR and XPS analysis,the interaction between nano-silver and sodium alginate was revealed,and it was found that nano-silver and sodium alginate only had physical binding.It was found that the G/M ratio and the concentration of sodium alginate had no obvious effect on the conductive thickening system of nano-silver/sodium alginate.Then the printing performance of nano-silver/sodium alginate thickening system on cotton fabric was emphatically studied.First,to low viscosity thickening system using inkjet printing,the printing parameters such as voltage,pulse frequency had a greater influence on the shape and frequency cannot influence the shape of drops.Second,the effect of sodium alginate concentration,nano silver content,baking temperature,binder,hydrophilic and hydrophobic modification of fabric on the printing performance was systematically studied by screen printing method.The high concentration sodium alginate nano-silver printing ink shows the characteristics of pseudo-plastic fluid in rheological properties and obvious shear thinning characteristics.The electrical conductivity of the pattern printed by nano-silver printing ink was enhanced with the increase of silver solid content.When the silver solid content was 15wt%,it showed a higher electrical conductivity.When the sodium Alginate concentration was 1wt%,the printing accuracy and fastness of the conductive printing ink were higher,and the resistance was as low as 5.28? at 150?.At the same time,it is found that the durability of printed conductive lines can be improved obviously by adding proper amount of binder into the system.Finally,the hydrophilicity of the textile surface has an effect on the printing performance of the nano-silver conductive paste.The hydrophilic surface will reduce the printing precision of the textile but with low resistance,while the hydrophobic surface will increase the printing precision of the textile but with high resistance.