How fine is calcined kaolin?

Calcined kaolin grades are normally very fine in particle size, generally 88–96% less than 2 μm. The calcined kaolin is used as an additive to hydrous kaolin in coating colors to increase brightness and opacity, usually in amounts of 20% or less based on the dry weight.

What is calcined kaolin used for?

Calcined kaolin is generally used in wires and cable coverings as it provides excellent dielectric and water-resistant properties. The wide usage of kaolin as filler is obviously within reasons. Foremost of them being the wide availability of kaolin in nature as well as its cost effectiveness compared to some other fillers.

Why is calcined kaolin a good sealant?

Calcined kaolin, because the hydroxyls on the surface have been eliminated, gives low moisture pickup which provides excellent performance in moisture sensitive sealant applications. The platy shape and white color are important properties in some adhesives and sealants. 10.4. Cosmetics

Does calcined kaolin improve electrical resistance of PVC?

Electrical resistance of PVC is improved by fillers that are hydrophobic. Calcining kaolin to about 1000°C reduces surface energy (Drzal et al., 1983), which develops some hydrophobicity which makes calcined kaolin a preferred filler in PVC.

How is kaolin surface modified?

The surface properties of kaolin are modified by treating China clay powder with specific chemicals, creating surface modified China clay powder. This modification enables better compatibility of the clay with various polymers and improves dispersion in different matrices.

What is the opacity of calcined kaolin?

The calcined kaolin products have brightness ranging from 91% to 96%. The opacity is increased because the kaolin particles are slightly fused together, which increases the light scatter due to air voids in the slightly fused calcined particles.