关键词: 聚乙烯膜, 可迁移组分, 锦纶织物, 聚氨酯涂层, 吸附, 分子动力模拟

Abstract: Polyethylene bags, crafted from polyethylene film, are prevalent in the packaging industry, valued for their lightweight, transparent, soft, and durable properties. They find extensive use in varied sectors, including garment and food packaging. However, these bags contain migratable components such as openers, plasticizers, and other unstable polymers. These components can migrate, causing adverse effects, such as surface stains on nylon fabrics, impacting the quality and visual appeal of the fabrics. Therefore, investigating the adsorption mechanism between the migratable components in LDPE film and the surface of PU nylon fabrics is crucial to mitigate the impact of retained stains on PU nylon fabrics.
To elucidate the mechanism behind the visually visible oily stains on the surface of polyurethane (PU)-coated nylon garments wrapped in low-density polyethylene (LDPE) film, this study employed a combination of experimental testing and molecular dynamics simulation. Initially, the composition of the oily stains on the surface of the PU-coated nylon fabrics and the migratory components of the LDPE film were identified. Subsequently, a comparative analysis of the compositions was conducted. This comparison identified two chemicals: oleic acid amide and erucic acid amide, which are fatty amide slip agents in LDPE. Therefore, this research, via a blend of experimental testing and molecular dynamics simulation, determined that the main contributors to the oily stains appearing on the surface of PU nylon fabrics are the fatty amide slip agents present in LDPE films. Further microstructural analysis illustrated that the migratable components interact closely with the surface of the nylon fabric, forming a cauliflower-like structure. The PU-coated surface of the nylon fabric demonstrated notable oleophilic and hydrophobic properties. Molecular dynamics simulation results revealed that the migratory components in the polyethylene film and the nylon fabric surface primarily adhered through H-bonds and van der Waals forces, with -OH, -NH2, and -CO in the PU producing the principal bonding sites with the polar groups (NCO) of fatty amides.
Through this multifaceted approach, the research clarified the microscopic adsorption mechanism between the fatty amide slip agents—oleamide and erucic acid amide—and PU, in LDPE films. These insights can guide the development of strategies to understand and prevent the occurrence of oily stains during the garment packaging process, offering technical support for the selection of suitable slip agents in garment packaging materials.

Key words: polyethylene film, migratory component, nylon fabric, polyurethane coating, adsorption, molecular dynamic simulation