拉伸性光固化導電墨水之製備

Abstract

本論文提供一個簡單且迅速之拉伸性光固化導電墨水製備方法，並採用脈衝光技術在數秒之內同時完成燒結及固化程序。透過照射高能量且波段廣之脈衝光，一方面使墨水中之導電填充物產生局部性加熱進而燒結，同時間也使墨水中之光起始劑激發產生自由基而進行固化交聯反應。此同時燒結及固化之程序，不僅避免掉傳統上加熱燒結過程中對樹酯之損壞，也降低導電網絡建立時樹酯的阻隔。因此，相較於傳統上先固化再加熱燒結之製程，奈米銀粒子比例需超過40-50 wt%始具有導電性質，本研究中奈米銀粒子之導電閾值(Percolation threshold)為20 wt%，高長徑比(Aspect ratio)之奈米銀線僅需10 wt%就能建立導電網絡。此較低之導電閾值不僅節省昂貴之導電填充物的原料成本，也保有較完整之彈性體性質，而可進一步應用於拉伸式導電線路。其中，同時以微米銀片及奈米銀線做為導電填充物可以架構出更穩定的導電網絡結構，在銀的總添加比例僅為25wt%下之拉伸過程中，保持良好導電特性，在60%拉伸形變下之電阻變化為7倍，重複以20%形變拉伸1000次後，電阻僅為原本之5倍，展現出此製程應用於可拉伸電子元件之潛力。

In this study, a simple and facile method is developed to prepare UV-curable conductive ink for stretchable conductors. To prevent long curing time at high temperatures, we introduced intense pulsed light (IPL) technology to simultaneously cure UV resins and sinter the silver nano-materials at room temperature. During the IPL illuminating, the intense pulsed light can heat the silver nano-materials locally and initialize the carbon double bond of the resin at the same time. This process can form a conductive pathway easily with half of percolation threshold compared to that of UV-heating process. The high aspect ratio of AgNWs makes its own low percolation threshold of only 10 wt%. Lower percolation threshold not only can save the amount of expensive conductive materials, but also retain the stretchability of elastomer. The combination (AgNWs/Ag flakes) as conductive fillers can maintain great electrical conductivity during the stretching process with only 25wt% loading of silver. The resistance ratio became only 7 times the original under 60% strain. After the composite was repeated with 20% deformation for 1000 times, the resistance of it was only 5 times the original. The fast curing and sintering process, low resistivity and good stretchability of the UV-curable ink show considerable potential for wearable printed electronics.