Tioxide Group, Plc

Derek O'Donnell

Peter Barry Howard

Titanium dioxide pigment having a high durability when used in paints comprises a particulate core of rutile titanium dioxide having an inner coating of dense amorphous silica on which is carried an outer coating of a hydrous oxide of zirconium. Optionally the pigment has an outer coating of a hydrous oxide of aluminum. The amount of dense amorphous silica is up to 12% by weight expressed as SiO.sub.2 and the amount of hydrous oxide of zirconium is up to 5% expressed as ZrO.sub.2 on the weight of TiO.sub.2. The outer coating of hydrous oxide of aluminium can be present in an amount of up to 6% by weight expressed as Al.sub.2 O.sub.3 on the weight of TiO.sub.2. A combination of these coatings has been found to be extremely advantageous in producing a paint containing the pigment having a very good durability and resistance to weathering.

Pigments and their preparation by coating with oxides of Si-Zr-Al

Titanium dioxide pigment of improved durability in paints comprises a particulate core of rutile titanium dioxide having an inner coating on the core of an oxide or hydrous oxide of zirconium, and a coating of dense amorphous silica on the inner coating. The pigment optionally has an outer coating of a hydrous oxide of aluminium. The pigments contain the oxide of hydrous oxide of zirconium in an amount of up to 5% expressed as ZrO.sub.2 and an amount of dense amorphous silica of up to 12% by weight expressed as SiO.sub.2 on the weight of TiO.sub.2. The pigments when incorporated in paints have extremely high durability.

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Cleveland, United Kingdom

Derek O'Donnell