- 學位論文
模具式塗佈對塗液在多孔布膜中流動行為之研究
Investigating the Flow Behavior of Coating Solution in Porous Media for Die Coating Process
摘要
纖維強化之高分子複合材料(FRP)的塗佈製程中，塗佈的方式不同會有不同的浸潤效果，所以本研究首先以數值方法分析狹縫式模具(slit die)及押出式模具(slot die)塗佈對塗液在多孔性材料中的流動行為。 以有限差分法的FLOW-3D軟體探討模具式塗佈製程中模具內所產生的壓力及其對塗液在多孔介質中的浸潤行為影響。模擬結果發現使用押出式模具其模內的壓力遠大於狹縫式模具，所以能有效地增快浸潤速度、減少達完全飽和所需的時間，模擬顯示押出式模具的飽和浛浸所需時間約為浸沾式塗佈的1/10。 另外，為探討操作變因對塗佈寬幅及厚度的影響，建立三維押出式模型並將結果以無因次群呈現。結果發現當理論與實驗的慣性力/黏滯力(Reynold number)對黏滯力/表面張力(Capillary number)比值分別約為500與450以下時，無因次寬幅會小於1，此即表示塗液無法填滿整個布膜的寬幅，這臨界比值可做為放大產線之參考。
並列摘要
In the coating process of fiber reinforced plastic (FRP), it was found that different types of coating methods had different effects on the imbibition of coating solution. In this study, the flow behavior of coating solution in porous media for the slit die and the slot die in the coating process was numerically investigated, firstly. The Finite Difference Method FLOW-3D commercial software was utilized to analyze the build-up pressure in the dies and understand the imbibition phenomenon of coating solution in porous media. It was found that the build-up pressure in the slot die is much greater than the slit die, and imbibition rate can be significant increased and reducing the required time to reach the complete saturation. In general the required saturation time of the slot die coating can be greatly shorted to one tenth of the dip coating required. To analyze operating conditions effect on the coating width and thickness, a 3-D model was constructed, and the simulation data were transformed in dimensionless groups. It was found that when the ratio of inertial force/viscous force (Reynold number) to viscous force/tension force (Capillary number) was smaller than 500 and 450 for numerical computation and experiment, respectively, the dimensionless width W* was less than one. This means the coating solution can not completely cover the width of the slot die. This critical ratio can be used as a reference in scale-up production lines.