Study On The Interface Homogenization Mechanism In Laminar Flow And The Structure And Properties Of Laminated Shrinking Film

With the increasingly fierce market competition,single-layer film packaging has been unable to meet the increasing needs of the packaging level,co-extruded film has become a research hotspot.The Multilayer coextrusion film has developed more economical and multifunctional,which requires a high performance and high efficiency multi-layer co-extruded equipment to suit its production.In view of the shortcomings of traditional multi-layer coextrusion blown film methods and equipments,Professor Qu Jinping of South China University of Technology proposed a new multi-layer coextrusion blown film forming technology which based on Couette flow: an Multi-layer co-extruded annular die with inner rotating mandrel can induce a Couette flow,which can achieve the uniform distribution of the circumferential direction.Finally,the thickness uniformity,interface uniformity and shrinkable performance of the multi-layer coextruded films are improved greatly.The interface homogenization mechanism of multilayer coextrusion based on Couette flow was analyzed in this paper,and the physical model and mathematical model were also established.According to the hypothesis and boundary conditions,we calculated the velocity,flow rate and pressure distribution in the circumferential direction during the multi-layer coextrusion process by simplifying the model,and revealed the affection of the key manufacturing parameters of the multi-layer coextrusion die to the flow uniformity of products,whuch lay a foundation for guiding equipment improvement and process debugging.This paper first carries out research on the static and dynamic rheological properties of materials for each layer,and find the rheological parameters of the compound on the process of laminated shrinking film preparation can benefit thickness uniformity and interface homogenization.Through the test of mechanical properties,thermal properties and morphology of the prepared multi-layer laminated shrinking film,analyzed the influence law of the new structure die and mandrel speed on the structure and properties of the products,which showed the characteristics and advantages of multi-layer coextrusion blow molding based on Couette flow.So the advantages of this method were proved on the basis of the experiment: the equipment owes small size,the flow channel was simple,the melt interface was stable,and the film performance was superior.