Method of preparing metal oxide slurries

摘要

A high solids metal oxides coated titanium dioxide aqueous slurry requires a negative charge and a high pH for use in aqueous paint media. A hot ageing of the coated titanium dioxide can alter the isoelectric point of the slurry and make practicable the avoidance of mixtures of metal oxide coating agents which give rise to processing difficulties and the use of mixtures of metal oxides which would not without the hot ageing step give suitable charge and pH characteristics. An example of a suitable mixture of metal oxide coating agents is a 1:1 molar Al2O3 : TiO2 mixture. An example of hot ageing conditions is the use of a temperature of 98 DEG C - 100 DEG C for 1 hour while avoiding loss of water and under alkaline conditions.