Is Silicon Dioxide SiO2 suitable for anti-corrosion coatings
In anti-corrosion coating formulations, Silicon Dioxide SiO2 is used as a thickening thixotropic and anti-settling additive. Thickening, anti-settling, suspension and other functions make the additives such as fillers evenly dispersed in the resin without precipitation; the thixotropic effect makes the coating have excellent anti-sag performance and thick coating performance, improving construction performance.
Mechanism of action:
When Silicon Dioxide SiO2 is dispersed in a non-polar liquid, the silanol groups on the surfaces of different particles form bridges through hydrogen bonding interactions, and the composition of this three-dimensional structure produces a thickening effect. When the system is subjected to a mechanical external force, such as stirring or shaking, the structure is destroyed. The type and duration of the mechanical external force determines the degree of damage, and the result is that the thickening system becomes liquid again. If left static, the silica particles will link up to restore the original viscosity. This phenomenon is called pseudoplasticity.
Anti-corrosion coatings are mostly epoxy resin, polyurethane resin, vinyl resin and other systems, these resins have strong polar groups, generally use hydrophilic fumed Silicon Dioxide SiO2, easy to solvent effect, good viscosity and suspension effect after dispersion, but leave for a week To ten days, the polar groups destroy the hydrogen bonds of the network structure, resulting in hydrogen bond cracking, dilution, no thixotropy, and filler precipitation. Therefore, it is recommended to use hydrophobically modified fumed silica, which has strong stability and avoids solvent effects.