Agne Swerin
SP Technical Research Institute of Sweden – Chemistry, Sweden
Title: One-pot waterborne superhydrophobic pigment coatings at high solids with improved scratch and water resistance
Biography
Biography: Agne Swerin
Abstract
A pigment coating was developed to achieve superhydrophobicity in one step from a waterborne formulation containing aragonite calcium carbonate, hydrophobized using sodium oleate, latex binder and cross-linker. Coatings formulated ≤50 mass% and applied to polyethylene coated paperboard substrates displayed typical superhydrophobic features: water contact angles ≥150°, low roll-off angle and low stain sizes, but poor scratch and water resistance as well as foaming issues during preparation. Reformulation at higher solids content significantly improved scratch and water resistance properties. Water rinsing of the dried coatings further increased the water barrier capacity due to reduced surfactant-assisted wetting; findings were corroborated by detailed surface chemistry analyses showing the removal of surface-active components after water rinsing of the dried coatings. A plausible cause for the improved durability is the fact that capillary forces increase exponentially with increasing pigment volume fraction (power law exponent of 2.2) leading to efficient binder coverage during the early stage of pigment coating consolidation.
