Preparation and incorporation of microcapsules in functional coatings for self‐healing of packaging board

The replacement of flexible polyolefin barrier layers with novel, thin, functional polymer coatings in the production of paperboard packaging involves the risk of deteriorated barrier and mechanical properties during the converting process. Local defects or cracks in the protective barrier layer can arise because of the stress induced in creasing and folding operations. In this study, the incorporation of microencapsulated self‐healing agents in coating formulations applied both by spot‐ and uniform‐coating techniques was studied. The preparation process of microcapsules with a hydrophobic core surrounded by a hydrophobically modified polysaccharide membrane in aqueous suspension was developed to obtain capsules fulfilling both the criteria of small capsule size and reasonably high solids content to match the requirements set on surface treatment of paperboard for enhancement of packaging functionality. The survival of the microcapsules during application and their effectiveness as self‐healing agents were investigated. The results showed a reduced tendency for deteriorated barrier properties and local termination of cracks formed upon creasing. The self‐healing mechanism involves the rupture of microcapsules local to the applied stress, with subsequent release of the core material. Crack propagation is hindered by plasticization of the underlying coating layer, while the increased hydrophobicity helps to maintain the barrier properties. Copyright © 2009 John Wiley & Sons, Ltd.     

蜂窝纸板压痕折叠方法探讨

针对目前蜂窝纸板难以折叠成型的问题,分析了蜂窝纸板压痕困难的原因,以及实现折叠的可行性和前提条件,讨论了蜂窝纸板制作缓冲衬垫可能的压痕折叠方法,提出了搭接蜂窝纸板和改变蜂窝芯结构的方法,为解决蜂窝纸板压痕折叠问题提供参考依据。