During the extrusion coating of paper or paperboard, a molten film of polymer is pressed against a paper surface to generate waterproof packaging materials. Hot-melt glues are also applied to various porous materials and paperboard to generate packaging. In both cases, the penetration of the polymer into the pore space influences the product performance and the ability of the product to be recycled at the end of life. While there is much experimental work discussing various parameters in these operations, little theoretical work has been reported. Here, a simple model based on Darcy’s law is proposed to predict the penetration of polyethylene (PE) into paper and paper that has been coated with cellulose nanofibers (CNF). Another model, based on the flow of a polymer into a pore that includes dynamic heat transfer is developed, where the viscosity is a function of temperature. Experiments were conducted where a PE film is pressed against samples and the amount of fiber recovery is characterized. The model predictions are compared to experimental results. Good agreement for different paper types, pressing times, and temperatures is obtained after a calibration factor is used.

在纸或纸板的挤出涂布过程中，聚合物的熔融薄膜被压在纸表面上以产生防水的包装材料。热熔胶还应用于各种多孔材料和纸板以产生包装。在这两种情况下，聚合物渗入孔隙空间都会影响产品性能和产品在使用寿命结束时回收的能力。虽然有很多实验工作讨论了这些操作中的各种参数，但几乎没有报道理论工作。在这里，提出了一个基于达西定律的简单模型来预测聚乙烯 (PE) 对纸张和涂有纤维素纳米纤维 (CNF) 的纸张的渗透。另一个模型，基于聚合物流入孔隙，包括动态传热，被开发出来，其中粘度是温度的函数。进行了实验，其中将 PE 薄膜压在样品上，并表征了纤维回收量。将模型预测与实验结果进行比较。使用校准因子后，不同纸张类型、压制时间和温度的一致性良好。