Silicon Dioxide Powder As Anti Corrosive Agent

What is the mechanism of action of silica in anti-corrosion coatings?

Silica is dispersed in a non-polar liquid, and the silanol groups on the surfaces of different particles form bridges through hydrogen

bonding interactions. This three-dimensional structure produces a thickening effect. When the system is subjected to mechanical external

force, such as stirring or shaking, this structure is destroyed. The type and duration of the mechanical external force acting determine the

degree of damage. The result is that the thickened system becomes a liquid again. If left to stand still, the silica particles will join together

and regain their original viscosity. This phenomenon is called pseudoplasticity.

Most anti-corrosion coatings are epoxy resin, polyurethane resin, vinyl resin and other systems. These resins have strong polar groups.

Generally, Hydrophilic Fumed Silica is used, which is prone to solvent-based effects, that is, sticky after being dispersed. The consistency

and suspension effect are very good, but within a week to ten days, the polar groups destroy the hydrogen bonds forming the network structure,

leading to the cracking of the hydrogen bonds, thinning, non-thixotropy, filler precipitation and other problems. Therefore, anti-corrosion It is

recommended to use hydrophobically modified Precipitated Silica for coatings, which has strong stability and avoids solvent-based effects.

The thickening and thixotropic effects of silica depend largely on the dispersion strength, which at least requires the use of a high-speed

disperser.

To achieve good dispersion effect, rotor stator dispersion or ball mill or three-roller dispersion can be used. The choice of dispersion method and

dispersion equipment depends on the consistency of the system. Sometimes we recommend using part of the liquid or part of the formula raw

materials to disperse all the silica first, and then adding the remaining liquid and other formula raw materials to adjust the silica content to the

required ratio of the formula. In principle, the thickening effect of silica increases as the basic particle size decreases. As the particle fineness

increases, higher shear force is required to achieve the thickening effect it can have.

USING TIPS:
* Recommend dosage is 3%-8%.  (Please adjust the dosage according to the actual product.)                                                                     

* As different formulations and conditions, suggest the user to test and make sure the dosage before using.

Anticorrosion Pigments, Inkjet Receptive Coating, Matting Agent