Silicates > as binder for coatings for mineral surfaces

BTC offers silicate solutions of alkali metals which act as binder for coatings for mineral surfaces. Silicates are also known as water glass or liquid glass. Silicate solutions of alkali metals are known mainly as sodium silicate or potassium silicate. Mainly alkali silicates provide alkalinity beside other properties like adhesion (binding) or stabilisation. The silicate composition and the used alkali metal (sodium, potassium or others) determine the final property of the silicate.

Due to the absence of efflorescence exclusively potassium silicates are used as binders.

Brands

Trasol®

Cycloquart®

Properties of our silicates as binder for coatings for mineral surfaces

Alkali silicates are characterized by their weight ratio of xSiO2:yAlk2O (silica:alkali-metal ratio), which is often documented as molar ratio, or water glass modul. The final BTC silicate products depend on the alkali silicate lumps as base material and the further processing to get the final aqueous silicate solution.

Depending on the used molar weight and water content the silicate solutions are different in viscosity, density and pH-value. Generally all silicates are considered as alkaline (pH >9) solutions. With increasing alkali metal content the pH value increases and the adhesion and binding properties are also enhanced.

Potassium silicates differ in the following properties from sodium silicates:

  • they provide less tackiness;
  • no-efflorescence occurs;
  • they show good solubility;
  • they offer high temperature binding properties.

Potassium silicate solutions are used as binders for coating of mineral surfaces. Various Trasol® products are available which differ mainly in viscosity. Some Trasol® products incorporate a stabilizer like Cycloquart®.

Applications

BTC’s silicates are mainly used for the production of outdoor coatings respectively exterior paints. These coatings are known as silicate-paints. Further applications cover the manufacturing of plasters and primers.

Silicate based binders for mineral surfaces are based on potassium. Potassium silicates do not form sodium carbonate (Na2CO3) which causes blooming or efflorescence on the surface.  Mineral surfaces like concrete, lime plaster and certain natural stones contain calcium carbonate (CaCO3). Applying potassium silicate on the surface forms calcium-silicate-hydrate, which is UV, heat and acid resistant. In addition, atmospheric carbonic acid (CO2) initiates a silification reaction on the mineral surface. Thus a coating is formed with advantages compared to conventional paints with respect to

  • durability,
  • high water vapor permeability,
  • greater dirt resistance,
  • inhibits the growth of germs,
  • penetrates the substrate,
  • porosity inhibits condensation of water,
  • inflammable (heat-resistant).

Certain Trasol® products contain already a stabilizer like Cycloquart®, beside others.

Silicate based paints or plaster for mineral surfaces are combined with different other ingredients like polymer dispersion, pigments, wetting agents besides others. The inorganic silicate solution must be stabilized in such a formulation to avoid viscosity increasement or coagulation. The addition of an APEO-free, cationic additive like Cycloquart®, improves the electrolyte tolerance and coagulation is hindered. In addition the in-can viscosity of a finished formulation will remain at a workable level.

Further products used in combination with our silicates

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About BTC

BTC Europe is BASF's European sales organization for small and medium-sized customers focused on specialty chemicals. Our silicates are used in a variety of industries as

besides others.