Silicon Dioxide Powder For Anti-Corrosive Pigment

Is silica suitable for anticorrosive coatings?

Anticorrosive coatings refer to a liquid or solid material that can form a thin film on the surface of an object under

certain conditions for protection, decoration or other special functions (insulation, rust prevention, mildew prevention,

heat resistance, etc.). Because most of the early coatings used vegetable oil as the main raw material, they were also

called paints. Synthetic resins have mostly or completely replaced vegetable oils, so they are called coatings. There

are three main functions: protection, decoration, covering up product defects, and improving product value. 

In the formulation of anticorrosive coatings, silica is used as a thickening, thixotropic and anti-settling additive. The

thickening, anti-settling, and suspension effects make additives such as fillers evenly dispersed in the resin without

precipitation; the thixotropic effect makes the coating have excellent anti-sagging properties and thick coating properties,

improving the construction performance.

Mechanism of action:

When silica is dispersed in a non-polar liquid, the silanol groups on the surfaces of different particles interact through

hydrogen bonds to form bridges, and the composition of this three-dimensional structure produces a thickening effect.

When the system is subjected to mechanical external forces, such as stirring or shaking, the structure is destroyed. The

type and duration of mechanical external forces determine the extent of damage, and the result is that the thickened system

becomes liquid again. If kept static, the silica particles will connect to restore the original viscosity. This phenomenon is

called pseudoplasticity.

Anti-corrosion coatings are mostly systems such as epoxy resins, polyurethane resins, and vinyl resins. These resins have

strong polar groups. Generally, hydrophilic Fumed Silica is used, which is easy to solvent effect. The viscosity and suspension

effect after dispersion are good, but after being placed for a week to ten days, the polar groups destroy the hydrogen bonds of

the network structure, resulting in hydrogen bond cracking, thinness, no thixotropy, filler precipitation and other problems.

Therefore, it is recommended to use hydrophobic modified fumed silica, which has strong stability and avoids solvent effect.

The thickening and thixotropy of silica depends largely on the dispersion strength, and at least a high-speed disperser is required.

In order to achieve the best dispersion effect, rotor stator dispersion or ball machine, three-roller machine dispersion can be used.

The best choice of dispersion method and dispersion equipment depends on the consistency of the system. Sometimes we recommend

using some liquid or some formulation ingredients to disperse all of the silica, and then adding the remaining liquid and other formulation

ingredients to adjust the silica content to meet the required proportions for the formulation. In principle, the thickening effect of silica

increases as the basic particle size decreases, but as the particle fineness increases, higher shear forces are required to achieve its

thickening effect.

Technical Index

Anticorrosion Pigments, Inkjet Receptive Coating, Matting Agent