Impact of silicone additives on slip/mar performance and surface characteristics of waterborne acrylic coatings

Abstract

Silicone additives are often added to coating formulations for improved slip and mar performance. However, the relationship between the chemical structure of silicone slip/mar additives and their performances has not been well understood. In the current study, six different silicone slip/mar additives made of silicone gum dispersions or silicone polyethers were investigated. Micron-sized silicone gum dispersions (G1 and G2) result in the lowest coefficient of friction and the highest mar resistance in a waterborne acrylic coating; however, they also lead to the highest surface roughness and the lowest gloss. The submicron-sized silicone gum dispersion (G3) results in a smaller improvement in the slip/mar performance and a much smaller detrimental impact on the surface roughness and gloss. All of the silicone polyethers (P1, P2, and P3) contribute to smaller improvement in slip/mar performance compared to silicone gum dispersions, but they have minimum impact on the gloss and roughness of coatings. Studies by AFM and XPS demonstrate coatings with micron-sized silicone gum dispersions have the highest surface segregation of silicone whereas coatings with silicone polyethers have the lowest surface segregation of silicone. A strong correlation between the surface segregation of silicone and the slip/mar performances of coatings is observed.