The Function of Precipitated Barium Sulfate Applied in Various Coatings

2015/05/18  bmschem

    Precipitated barium sulfate used in high-solid coating

    The varnish on high solids needs to use the precipitated bairum sulfate with a particle size of 0.7 to 0.8 μm. Larger particles will affect the surface gloss, while smaller particles need to use more base materials for the influence of higher specific surface area.

    Precipitated barium sulfate whose particle size is less than 0.7 μm can deflocculate and separate pigments, thus reduces the amount of pigments to a very low value. 0.7 μm barium sulfate has no impact on viscosity in a wide range. So we can prepare accoring to the highest rate of barium sulfate in formulation, which does not affect gloss. Therefore, precipitated barium sulfate provides a good opportunity to reduce VOC, replace more expensive pigments and reduce the cost of formula.

    In addition to white and bright paints, it is worth to mention that white powder precipitated barium sulfate can also be used for pure black paint without impacting the black. This is due to the refractive index of precipitated barium sulfate which is similar to that of resin. So the precipitated barium sulfate mixed in the system is not white but transparent. It can reduce the VOC of black paint without producing light gray. There are big differences between the oil absorption and specific surface area of carbon black and that of barium sulfate. Through deflocculation, the useful effect of carbon black only increases slightly. Using precipitated barium sulfate to replace a large number of carbon black can reduce the total demand of base material and viscosity, thus reducing the VOC.

     Precipitated barium sulfate applied in powder coating

    Powder coating is one of the fastest growing markets in the coating industry. Due to the special properties, low base material demand and excellent dispersity, precipitated barium sulfate has become an indispensable component of powder coatings. The specific gravity of precipitated barium sulfate is the same as that of titanium dioxide, which provides us the opportunity to prepare nonflying powder coating formula. When we use tiny powder, in typical powder coating formula, the mechanical property of the powder coating filled with barium sulfate is related to the particle size (the finer the better).

    Precipitated barium sulfate applied in water-based paint

    It is also applied to water-based paint just like conventional paints due to the chemical inertness and insolubilization. The effect of micronized precipitated barium sulfate has been confirmed. In electrophoretic paint (which has complex requirements for particle deposition or wettability), it can replace 10% to 30% of titanium dioxide.