现代纺织技术2025，Vol.33Issue(4)：75-82,8.DOI:10.19398/j.att.202407026
狭缝涂布过程流体流动形态的数值模拟
Numerical simulation of the fluid flow pattern in slot die coating process
摘要
Abstract
The slot die coating is widely utilized in fabric coating and advanced packaging as a predictive coating technology.The thickness distribution and stability of the liquid film formed during the slot die coating process affect the morphology and structure of the cured coating,ultimately influencing the properties of the product.However,due to the coupling of multiple operational parameters,the mechanism that influences film thickness distribution and stability remains unclear. In this study,we conduct numerical simulations of the slot die coating process to investigate film formation.Firstly,relevant governing equations are established,the geometric model and boundary conditions are determined and meshed,the solution method is given and mesh-independence is verified.Subsequently,we verify the accuracy of our numerical simulations by comparing them with experimental data reported in the literature.Finally,we investigate the mechanisms through which operating conditions and fluid properties influence the thickness,uniformity,and stability of the liquid film. The contour plots of liquid phase distribution shows that the thickness of the liquid film increases continuously with the elongation of fluid flow time.When the flow time is 0.1 s,the liquid film thickness no longer changes with time,and the transient numerical calculation is completed.To investigate the coating mechanism and flow pattern of slot die coating,different substrate moving speeds,inlet velocities and fluids with different viscosities are set up for numerical calculation,and the role of each factor is analyzed in combination with the film thickness distribution and film-forming stability.It can be concluded from the film thickness distribution graph and velocity contour that:when the substrate moving speed is relatively low,the film-forming flow rate is less than the inlet flow rate,resulting in fluid accumulation at the die lip.Thus the film-forming flow rate and the liquid film thickness increase with the substrate moving speed;when the film-forming flow rate increases to the inlet flow rate,the liquid film thickness reaches the maximum.However,as the substrate moving speed further increases,the film-forming flow rate remains constant and equal to the inlet flow rate,leading to a decrease in liquid film thickness.Within the stable operating window,coating uniformity increases with the increase of the substrate moving speed.As the viscosity of the fluid increases,there is little noticeable change in the thickness of the coating,whereas the uniformity of the liquid film steadily decreases.This is attributed to the increased viscous force,which causes the substrate to entrain more fluid.Consequently,the film-forming flow rate equals the inlet flow rate,resulting in no further changes in film thickness.As the inlet velocity increases,the thickness of the liquid film keeps increasing and the uniformity of the liquid film does not change significantly.The simulation results show that the substrate velocity and inlet velocity are the main factors influencing the film thickness and its uniformity.A stable and uniform coating can only be achieved within a specific range of process parameters;otherwise,coating defects may arise.The analysis of the film formation mechanism of slot die coating provides theoretical guidance for the optimization of coating process parameters.关键词
狭缝涂布/液膜厚度/成膜稳定性/CFD数值模拟Key words
slot die coating/film thickness/film stability/CFD numerical simulation分类
化学工程引用本文复制引用
洪浩斌,章恒宽,张先明..狭缝涂布过程流体流动形态的数值模拟[J].现代纺织技术,2025,33(4):75-82,8.基金项目
国家自然科学基金项目(51973196) （51973196）
