The operability windows and coating bead dynamics for the dual-layer slot coating process with non-Newtonian coating liquids were investigated using the viscocapillary model, a two-dimensional (2D) CFD simulation, and experiments. The simplified viscocapillary model derived from the 2D equation of motion with the shear-thinning Carreau liquids bounds the uniform coating regime without defects such as leaking, bead break-up, and mid-gap invasion in dual-layer coating systems. The coating bead flows from experiments and finite-volume-based 2D simulations with the volume-of-fluid scheme demonstrate the performance of the viscocapillary model in reliably tracking the upstream meniscus position of the bottom layer in the coating bead region. The onset of leaking, bead break-up, and mid-gap invasion defects is strongly affected by the rheological properties of Carreau-type coating liquids and the flow ratio between the top and bottom layers. In particular, the relative thickness of the shear-thinning bottom layer at the onset of mid-gap invasion is smaller than the well-known 1/3 value in the Newtonian case, depending on the degree of shear thinning.

使用粘毛细管模型、二维 (2D) CFD 模拟和实验研究了使用非牛顿涂层液体的双层槽式涂层工艺的可操作性窗口和涂层珠动力学。从具有剪切稀化 Carreau 液体的 2D 运动方程派生的简化的粘毛细管模型限定了均匀的涂层状态，在双层涂层系统中没有泄漏、珠子破裂和中间间隙侵入等缺陷。来自实验和基于有限体积的 2D 模拟和流体体积方案的涂层珠流证明了粘毛细管模型在可靠地跟踪涂层珠区域中底层的上游弯液面位置方面的性能。开始泄漏，珠子破裂，Carreau型涂布液的流变特性和上下层之间的流动比对间隙中侵入缺陷有很大影响。特别是，间隙中侵入开始时剪切变薄底层的相对厚度小于牛顿情况下众所周知的 1/3 值，这取决于剪切变薄的程度。