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Analysis of Flow in Coating Process of Functional Film

功能薄膜涂布工艺流程分析

基本信息

批准号：
13450076
负责人：
MORI Noriyasu
金额：
$ 9.6万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13450076/
关键词：
Complex fluids Coating film Liquid crystalline polymers Polymer solutions Orientation Film Dip coating Gas penetration 引上げコーティング

项目摘要

Flow phenomena in the coating process of functional films were investigated both experimentally and numerically. In the present project, coating films of liquid crystalline polymers (LCPs) and polymer solutions were mainly considered. For the LCPs, investigated were flow-induced molecular orientation in a process for making an alignment layer, and textures appeared in both simple shear flows and flows in a slit channel. Experiments of the coating flow of hydroxypropylcellulose (HPC) confirmed the alignment layer was created owing to the flow-induced molecular orientation. Moreover, the flow-induced orientation was numerically analyzed using the Doi model as a constitutive equation, and the results showed that the molecules aligned parallel to the film surface. In addition, textures in the simple shear flow were observed with a microscope. The flow was generated with a Cambridge Shearing System and liquid temperature was also controlled with this device. Temporal changes in the texture under the shear flow and in the relaxation process after cessation of the flow were observed to elucidate the effects of the liquid temperature, shear rate, and gap width on the texture pattern. In the slit channel, experiments in startup flows were carried out to obtain the knowledge of the occurrence mechanism of a wavy texture observed in the flow. For polymer solutions, the effect of rheological properties of polymer solutions on the film thickness was investigated in both dip-coating flows and gas penetration flows in a circular tube. In the dip-coating process, the film thickness increased with increasing the withdrawal velocity and the increasing rate became smaller than that for Newtonian fluids because of the shear-thinning viscosity. In the gas penetration in polymer solutions, the shear-thinning viscosity took a role to make the film thin and the elastic property made the film thick.

对功能薄膜涂覆过程中的流动现象进行了实验研究和数值模拟。在本项目中，主要考虑液晶聚合物（LCP）和聚合物溶液的涂层膜。对于LCP，研究了在用于制造取向层的过程中流动诱导的分子取向，并且纹理出现在简单剪切流和狭缝通道中的流中。羟丙基纤维素（HPC）的涂布流动实验证实，取向层是由于流动诱导的分子取向而产生的。采用Doi模型对流动诱导取向进行了数值分析，结果表明分子取向与膜面平行。此外，在简单剪切流织构观察用显微镜。流动是由剑桥剪切系统产生的，液体温度也由该装置控制。观察了剪切流动下纹理和流动停止后松弛过程中纹理的时间变化，以阐明液体温度、剪切速率和间隙宽度对纹理图案的影响。在狭缝通道中，在启动流中进行了实验，以获得在流动中观察到的波状纹理的发生机理的知识。对于聚合物溶液，研究了聚合物溶液的流变特性对圆管中浸涂流和气体渗透流的膜厚的影响。在浸涂过程中，由于剪切变稀粘度的存在，膜厚随抽拉速度的增加而增加，且增加速率小于牛顿流体。气体在聚合物溶液中的渗透过程中，剪切变稀粘度使膜变薄，弹性使膜变厚。