覆膜铁熔融覆膜过程界面传热与熔膜填充行为研究

覆膜铁是金属包装领域的新型复合材料。成品覆膜铁的界面结合强度和水透性取决于覆膜过程中高聚物薄膜熔融层的厚度和流动铺展行为。但覆膜过程复杂而迅速，且受钢板表面微观形貌影响，熔融层膜厚及其流动铺展行为难以精细调控。针对此，基于分形理论表征与重构基板带钢表面微观形貌；基于广义Maxwell模型试验建立聚合物膜的黏弹性本构关系；建立了考虑基板带钢表面微观形貌的覆膜过程有限元仿真模型，并试验验证了模型的准确性。研究表明，熔融层膜厚主要受基板带钢初始预热温度影响，界面填充率则主要受覆膜辊压力影响。高聚物膜熔融层厚度和界面填充率随基板带钢粗糙度降低以及基板带钢和覆膜辊初始预热温度增加而增加，且辊压力增加也导致界面填充率增加。这些规律被定量化描述，为精细化调控熔融层膜厚及其流动铺展行为提供了理论依据。

Study on Interface Heat Transfer and Polymer Film Melting-Filling Behavior During the Laminating Process for Laminated Steel

Laminated steel is a new type of composite material in the field of metal packaging. The interfacial bond strength and water permeability of the finished laminated steel depend on the thickness and flow-spreading behavior of the molten layer of the polymer film during the laminating process. However, it is difficult to tune the thickness of the molten layer and its flow-spreading behavior, because the laminating process is complex and rapid, and affected by the microscopic topography of the substrate surface. Aiming at this difficulty, the microscopic topography of the substrate surface was characterized and reconstructed based on the fractal theory, the viscoelastic constitutive relation of the polymer film was established based on the generalized Maxwell model experiment, hence a finite element simulation model of the laminating process considering the microscopic topography of the substrate was established, and the accuracy of the model was experimentally verified. The model results show that the thickness of the molten layer is mainly affected by the initial preheating temperature of the substrate strip, and the interface filling ratio is mainly affected by the pressure of the laminating roll. The molten layer thickness and the interfacial filling ratio increase with the decrease of the roughness of the substrate strip and the increase of the initial preheating temperature of the substrate strip and the laminating roll, and the increase of the roll pressure also leads to the increase of the interfacial filling ratio. These laws were quantitatively described, which provides a theoretical basis for fine-tuning the thickness of the molten layer and its flow-spreading behavior.