Analysis of the Occurring of the Un-uniform Regions in Slot Coating

• Main Authors: Wu,Tsai-Fang, 吳采芳
• Other Authors: Chen,Ren-Haw
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/07778959714714723439

碩士 === 國立交通大學 === 機械工程系所 === 102 === Although the slot coating process in the production of polymer films has a wide range of applications, the process is difficult to be systemized, and un-uniform regions often occur on the edges of the slot coating film, so this study developed a solution for the problem of non-uniform regions on the edges of slot coating film. This research aims to use the CFD software POLYFLOW to aid the analysis of the cause and characterstics of the un-uniform regions on slot coating films. First, the non-Newtonian rheological properties and surface tension of the coating material were acquired through experiments. The measurement data were imported to the simulation software for mathematical modeling. Then, 2D and 3D numerical model of the slot coating process were created. Arbitrary Lagrangian-Eulerian (ALE) calculation methods were used in the POLYFLOW software for simulation. The results of 2D simulation show that surface tension will decreases the coating length. Substrate speed and relaxation time increase coating length, but excessive substrate speed causes defects. The 3D simulation results show that unsteady phenomena at the flow front generate uneven deformation grids, which cause a divergence in the calculation. Balancing the system parameters can improve the results. Additionally, moderately increasing the length of the coating lip increases the uniformity of the flow rate in the x-direction, and helps to minimize un-uniform areas of the slot coating. An additional trench on the coating lip usually does not improve the flow rate in the x-direction. However, the simulation of a 0.5*0.1*2.5 mm3 trench achieved good results, which were consistent with the experimental results. This research provides a reference for improved mold design.