Mechanical Interlocking In Coating Paper/Board Adhesion, 1996 Coating Conference Proceedings

Adhesion between two surfaces involves physico-chemical interactions (acid-base and Lifshitz-van der Waals forces) and possibly mechanical interlocking if the substrate is porous and rough. Paper has a roughness and a network of pores. It could be expected that, when paper is coated the adhesion would contain mechanical interlocking in addition to the physico-chemical interactions. Experiments were designed to measure the level of mechanical interlocking by pretreating handsheets with a fluorocarbon, to remove the physico-chemical interactions. Adhesion was measured through a peel test. It was found that as porosity and/or roughness increased, the peel force also increased. In some cases the peel force measured on coated-paper represented up to 60% of the delamination energy of the paper. From measurements of single fiber-coating adhesion it is concluded that the fiber’s micro-roughness can contribute up to 20% of the fiber-coating adhesion.