陽極氧化鋁(AAO)奈米結構無縫滾輪研發及應用

Abstract

具奈米結構的薄膜廣泛應用於抗反射光學元件、表面自潔玻璃等，由於熱滾壓製程具有快速、連續、大面積的優點，奈米結構塑膠膜一般以滾壓生產；但目前用以滾壓奈米結構薄膜的滾輪模具，其製作大多仍仰賴電子束或離子束等加工方式或熱壓成型，成本高、加工時間長且能源效率不佳。本研究探討無縫陽極氧化鋁奈米孔洞滾輪模具之製作技術，並嘗試以熱滾壓成型之技術於PC薄膜表面製作出連續大面積奈米結構。 本研究嘗試使用純度99.99%之鋁金屬管材作為陽極進行陽極氧化製程，直接於其上製作陽極氧化鋁(AAO)奈米孔洞結構，並確認其結構於圓周各角度上的生成狀況皆相同。接著以40 V、80 V及180 V的外加電壓，搭配不同種類與濃度之酸液，皆獲得具有陽極氧化鋁孔洞結構的無縫滾輪模具，其表面奈米孔洞間距為80 nm、160 nm及430 nm。然而，因材料純度較低，內部含有雜質，使得陽極氧化製程期間表面出現微米級孔洞結構，奈米孔洞於生成期間不易達到受力平衡之狀況，排列受影響而難以整齊。 本研究進一步以純度為99.999 %的鋁片為材料，捲成管狀後進行陽極氧化實驗；實驗結果顯示，使用較高純度的鋁材進行陽極氧化製程，因雜質含量低，可得到表面無微米級孔洞結構的陽極氧化鋁，且奈米孔洞排列更加有序。另外，本研究嘗試以真空濺鍍方式，於普通滾輪上濺鍍純度99.99 %的鋁金屬層，進行陽極氧化實驗；實驗結果顯示，濺鍍前有先拋光、鍍膜與基材間具有介質層者，鍍層與基材結合能力較強，經陽極氧化後可得到表面微米孔洞結構較少之模具。 本研究亦製作無縫AAO滾輪模具應用於連續熱滾壓製程。在一定的熱滾壓製程條件下，AAO滾輪模具上的奈米結構可無長度限制地於PC薄膜基材上進行翻印複製，且因模具本身為無縫滾輪模具，所滾壓出的PC薄膜上沒有接縫存在，證實AAO無縫滾輪模具可實際應用於具奈米結構薄膜的生產。

Nanostructured thin films have been widely applied for anti-reflective components and self-cleaning surfaces. The roller mold for production of nanostructured films mostly relies on expensive processes, such as e-beam or focused ion beam. This study develops an effective, fast, and low-cost method to fabricate seamless anodic aluminum oxide (AAO) roller mold, which then be employed to fabricate nanostructures on the surface of polycarbonate (PC) continuously by roller hot embossing. The alumina oxide membranes with nanopores of 80 nm, 160 nm and 430 nm in pitches were fabricated via two-step anodization, and the employed anodization voltage are 40 V, 80 V and 180 V, respectively. The SEM photos show that the fabricated nanopores are similar as observed from all degrees of the surface. However, there are microholes on the surface due to the purity of the aluminum is only 99%. The aluminum with higher purity, including a 99.999% purity aluminum foil and a roller which were sputter coated with a 99.99% purity aluminum layer, were anodized in this research. The result show that using higher purity aluminum could obtain anodic aluminum oxide with better arrangement and without microholes on surface because less impurities exist. The seamless AAO roller mold fabricated in this research has been utilized to continuous hot rolling process. Comparing to plate form hot embossing, hot rolling has the advantage of high speed, continuous, large area, and suit for mass production. Since the mold itself is seamless, in this work, the nanostructures on the AAO roller mold can be replicated onto the PC substrate with no restriction of length and seam defect, providing the nanostructured films various ways of application.