Flow Analysis of Non-Newtonian Fluid Slot Coating
|關鍵字:||狹縫式塗佈;計算流體力學;POLYFLOW;塗佈視窗;slot coating;computational fluid dynamics;POLYFLOW;coating window|
本研究旨在利用計算流體力學軟體POLYFLOW來分析狹縫式塗佈製程，探討製程參數對於薄膜塗佈特性的影響，以降低塗佈實驗方法所消耗的時間和成本。首先透過實驗取得非牛頓流體之材料流變特性，並將其建置於模擬軟體內，進行數學模型的擬合；其次建立狹縫塗佈製程模型，並使用軟體內的Arbitrary Lagrangian-Eulerian (ALE)方法，在不同的入流量與基板速度條件下進行計算。得到的模擬結果並與實驗數據以及文獻進行比較和驗證，以探討製程參數對塗層的影響，並建立操作視窗。研究結果顯示本研究所用材料的黏度-剪切率特性在剪切率為20~5000 s^(-1)的範圍下能與Cross Law、Carreau-Yasuda、Bird-Carreau等三個模型相當吻合，本次研究選用Cross Law模型。當選擇不同的入流量與基板速度時，在特定的範圍內，可以生成穩定的膜厚，但塗佈速度過快、供液量不足時，則會產生斷膜、膜厚不均、氣泡混入等不良現象。而塗佈速度過慢、供液量過量時，會產生大量的積料，使得成膜過厚。|
Although the slot coating process in the production of polymer films has a wide range of applications, the process cannot be systemized, owing to the variety in demand of function on thin films that are prepared for production. Difference properties were needed to achieve by using different processing conditions. This study uses the computational fluid dynamics software POLYFLOW to analyze the slot coating process and investigate the influence that process parameters have on the characteristics of thin-film coating to reduce the time and cost consumption in the experimental methods. The rheological material characteristics of non-Newtonian fluid were first identified by conducting experiments, and then configured in the simulation software for fitting with mathematical models. In addition, the models of the slot coating process were constructed, and the Arbitrary Lagrangian-Eulerian (ALE) calculation methods were then used in the POLYFLOW software under different inflow and substrate speed. The simulation results were then compared to the experimental results and the findings reported in relevant literature, to determine the influence that the process parameters have on the characteristics of thin-film coating. The simulation results were represented graphically in a coating window plot. The comparison results indicate that the viscosity-shear rate characteristic of the material used in this study is an excellent fit in the shear rate range of 20 to 5000〖 s〗^(-1) for the following three models: Cross Law, Carreau-Yasuda, and Bird-Carreau. The Cross Law model was selected for this study. When selecting different inflow and substrate speed, stable coatings can be coated in a specific range. When the coating speed is too high or the amount of inflow is insufficient, phenomena such as break lines, uneven thickness, and air entrainment can occur. When the coating speed is too slow or the amount of inflow is excessive, a lot of material will accumulate and then leads to an excessive coating thickness.