狹縫塗佈的數值研究

Abstract

狹縫塗佈是一個製造各種產品的常用方法，其優點為可利用給定的流量和基板速度達到控制塗膜厚度的效果，而成模狀態也會因不同的實驗條件產生不同的缺陷，通常會以塗佈視窗(Operability Window)來表示，相關的理論和數值模擬也已經有了相當多的研究。 多孔材質塗佈的研究相對是比較少的，因此本研究利用計算流體力學軟體FLUENT來分析狹縫塗佈製程，並且探討在多孔材質在不同參數下的塗佈情形，以減少實驗上所產生的塗佈缺陷和降低實驗的時間和成本。首先，經過紀錄塗佈過程的影像，並且根據實驗的各項參數，建立一可以與實驗比較之數值模型；其次改變參數，利用所建立之數值模型觀察流場中的變化以及是否有塗佈缺陷產生，由模擬結果建立操作視窗，並且對於滲透深度及膜厚等參數進行分析。研究結果顯示在入口流速0.055 m s-1時，基板速度超過0.18 m s-1會產生液膜破裂的問題，並且在滲透深度方面顯示，基板速度越快時，液體滲透的深度越淺。除此之外，塗佈在有孔洞之基板相較於無孔洞基板在高速時會更容易產生缺陷。

Slot die coating is a versatile process that is widely used for producing thin and uniform films. A major benefit of slot die coating is the thickness of the thin film can be controlled based on the flow rate and the velocity of the substrates. However, the defects of the film might occur because of different experimental conditions, and usually presents in form of operability window. There has been quite a lot of research on related theories and numerical simulations. However, the study of coating on porous medium is relatively few. This study uses FLUENT, a computational fluid dynamics software, to analyze the slot coating process and discuss the application of porous materials under different parameters to reduce coating defects and reduce the time and cost of the experiment. Firstly, establish a numerical model that can be compared with experiment by recording the images of coating process and parameters. Secondly, establish operability windows using the numerical model, and analyze the film thickness and penetration depth. The results of the study show that when the inlet velocity is 0.055 m s-1, the substrate velocity exceeds 0.18 m s-1 will cause the problem of liquid film rupture. And in terms of penetration depth, the faster the substrate speed, the shallower the liquid penetration depth. In addition, coating on porous substrate is more prone to defects at high speeds than coating on non-porous substrate.