Preparation Of Flexible Conductive Textiles Based On Nano-silver Conductive Ink And Its Application

In recent years,with the continuous development of science and technology and the change of lifestyle,flexible wearable electronic devices have received great attention.Textiles are ideal substrates for the preparation of flexible wearable electronic devices.The key of conductive textiles is to make the common fabric have better electrical conductivity without affecting the inherent properties of the fabric.At present,nano-silver has been widely used in the preparation of conductive inks due to its advantages such as particle size control,high conductivity,strong oxidation resistance and good stability.Inkjet printing technology has important research value and broad development prospect in the preparation of wearable electronic textiles due to its advantages such as wide range of printing materials,high pattern precision,no need to make printing plate and high ink utilization rate.At present,it is a major challenge to solve the problem between conductive materials and fabrics with the contradiction between fastness and conductivity,and to realize the water-resistant properties of conductive textiles.Based on this,this paper took nano-silver as conductive filler,and prepared conductive ink by optimizing its preparation process.Waterborne polyurethane was used as adhesive layer to finish the coating on the surface of the fabric to improve the conductivity and fastness of the conductive fabric.The conductive pattern is printed on the surface of fabric by means of simulating inkjet printing and applied to conductive circuit and textile strain sensor.The main research contents and results are as follows:Firstly,this paper silver nanoparticles was prepared by chemical reduction method with silver nitrate as the silver source,PVP as a protective agent,hydrazine hydrate as a reducing agent.The effects of the dosage of PVP,the concentration of silver nitrate and the concentration of hydrazine hydrate on the particle size and electrical conductivity of silver nanoparticles were investigated.The structure and properties of silver nanoparticles were analyzed by different characterization methods.The prepared silver nanoparticles were sintered at high temperature and low temperature,and the optimal sintering conditions were obtained by comparison.The results showed that the optimal preparation conditions were as follows: the molar ratio of PVP to silver nitrate was1.8:1,the concentration of silver nitrate was 0.05 mol/L,and the concentration of hydrazine hydrate was2 mol/L,the average particle size of the silver nanoparticles is 62.2 nm,and the particle distribution is uniform and concentrated,almost no agglomeration phenomenon.The particles have good crystallinity and complete structure,which belong to face-centered cubic structure,and the conductivity of nano-silver is good under these conditions.The sintering of silver nanoparticles by different sintering methods shows that the low temperature sintering can melt the silver nanoparticles in a short time compared with the high temperature sintering,so as to achieve the purpose of high conductivity.The sintering process was determined to use chemical sintering,with saturated sodium chloride as the sintering agent,and the sintering time was 5 min.Secondly,conductive ink was prepared with nano-silver as conductive filler,ethylene glycol as moisturizer,glycerol as viscosity adjusting agent,the influence of nano-silver,ethylene glycol,glycerol content on the performance of conductive ink were investigated.Then,cotton fabric was used as the substrate for printing,and water-based polyurethane was used to treat the surface adhesion layer of cotton fabric.The effects of concentration of water-based polyurethane solution on the surface morphology and feel of cotton fabric and the electrical conductivity of printed conductive fabric were investigated.And the printed conductive fabrics are tested for washing resistance,bending resistance,adhesion fastness and conductivity.Then,different conductive patterns were printed on the surface of the cotton fabric treated with the best conditions to produce conductive fabrics with good conductivity and good fastness.The results showed that the best formula of nano-silver conductive ink was 20% nano-silver,30% ethylene glycol,10% glycerol and 40% ethanol.Under these conditions,the nano-silver conductive ink has good stability and conductivity,and the ink viscosity and surface tension are more suitable,and the printing effect is better.The optimal concentration of waterborne polyurethane was 50%,when the surface of cotton fabric was relatively smooth,which was conducive to the deposition of conductive ink,and cotton fabric feels soft.By printing 10 conductive layers on the surface of the treated cotton fabric,the fabric with good conductivity and good fastness was obtained.The conductive fabric could withstand ultrasonic washing for more than 60 min,three times of conventional soaping and more than 500 times of bending.It had good ultrasonic cleaning,soaping washing and bending resistance.At the same time,the conductive fabric has certain scratch resistance and good adhesion fastness.By simulating inkjet printing on the surface of processed cotton fabric,the conductive pattern with clear pattern and good metallic luster can be obtained,and the original softness of the fabric can be maintained,and the external force can be tolerated to a certain degree.Finally,nano-silver conductive ink is applied to conductive circuit and flexible textile strain sensor and medium respectively.Performance analysis is carried out by lighting LED lights and monitoring human body and sound electrical signals.The results show that the LED can emit brighter light from the near end to the far end,and the brightness of the LED increases with the thickening of the conductive circuit.Conductive circuits have good electrical conductivity and low resistance,and can be used in the preparation of fine circuits.The flexible textile strain sensor has good strain sensing performance,and can be installed on many parts of the human body and other objects,and can accurately monitor human movement and sound signals.