Kronos International, Inc.

Alexander Breyder

Volker Schmitt

Siegfried Bluemel

Frank Mersch

Volker Juergens

Siegfried Blumel

Janine Siekman

The invention relates to a method for the surface treatment of inorganic pigment particles with agglomerates of fine primary particles or single crystals of inorganic compounds, particularly of oxides or sulphates. The method is characterized in that the inorganic compounds are first precipitated from an aqueous solution under suitable pH conditions in a separate vessel in the form of fluffily structured agglomerates and/or single crystals. The precipitation product is subsequently added to an aqueous suspension of inorganic pigment particles. The method is particularly suitable for the surface treatment of titanium dioxide particles, in order to achieve high hiding power or high opacity when used in emulsion paints or laminates.

Method for surface treatment of inorganic pigment particles

Method for the surface treatment of inorganic pigment particles

The invention relates to a method for the surface treatment of a titanium dioxide with aluminum phosphate and hydrous aluminum oxide that leads to pigments with improved greying resistance, while simultaneously maintaining good brightness and opacity. The method is characterized in that phosphoric acid is initially added to a TiOsuspension with a pH value of at least 8, in which context the pH value drops to 3 or below. An alkaline aluminum compound is subsequently added, in which context the pH rises to at least 5, after which an acid aluminum compound is added, as a result of which a pH value of 4.5 to 7 is obtained. The pigment manufactured by the method according to the invention is eminently suitable for use in decorative laminating paper.

Method for surface treatment of a titanium dioxide pigment

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Leverkusen, Germany

Alexander Breyder