2.3 Impacts of Silane Modified Colloidal Silica on Waterborne Clear Coatings
(Room 240-242)
09 Apr 18
3:00 PM
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3:30 PM
Tracks:
Session 2: Wood Coatings
Water-free systems of silane modified colloidal silica particles have been found to enhance mechanical properties of coatings. Aqueous colloidal silica has been used in co-polymerization of resins and co-polymerized colloidal silica resin hybrids are also used to enhance a variety of coatings properties like hardness, anti-blocking and reduced dirt-pickup. Non-surface modified colloidal silica has been tested as nano-filler in latex coatings with encouraging results concerning mechanical properties.
AkzoNobel has developed silane modified colloidal silica to use in waterborne coating. Concentrated epoxysilane modified colloidal silica in the form of aqueous sols is one of most readily available sources of nano-particles for the coating area. Such sols are characterized by high solids content, up to at least 50 % by weight of silica depending on particle size which ranges from about 5 nm to 100 nm. Compared with conventional silica sols, silane modified colloidal silica has greater stability towards aggregation and gelling, both as is and in latex-based coating formulations.
The effect of epoxysilane modified colloidal silica, added to water-based coating formulations, on the mechanical properties of resin films was studied. In general, the effect of the silica particles depended strongly on the resin and other components of the coating formulation but very significant improvements of block resistance (and hence sanding properties) were seen. In addition, extended open time, better penetration and substrate wetting for “anfeuerung” in acrylic resin based wood coatings and additionally of mechanical properties in 2-pack PUD system could be observed.