| 摘要 |
1479988 Treating TiO 2 pigment TIOXIDE GROUP Ltd 27 May 1976 [17 July 1975] 30034/75 Heading ClN TiO 2 pigment is treated by forming an aqueous dispersion thereof containing a watersoluble compound of silicon in amounts of 1- 2% as SiO 2 , adding to the dispersion an acidic water-soluble Al compound in amounts of 1À5- 2-5% (as Al 2 O 3 ), an acidic water-soluble Zr compound in amounts of 0À5-1À5% (as ZrO 2 ) and an acidic water-soluble Ti compound in amounts of 1-2% (as TiO 2 ), changing the pH to 7À5-8À5 and adding to the dispersion a water-soluble Si compound in amounts of 1-2% (as SiO 2 ), an acid water-soluble Al compound in amounts of 1-2% and an alkaline water-soluble Al compound in amounts of 0-1À5% (both as Al 2 O 3 ) and recovering the treated pigment. The starting pigment is preferably a calcined "sulphate process" titania containing at least 95% rutile. The starting pigment may contain 0À1-0À5% Al 2 O 3 . The aqueous dispersion containing the watersoluble compound of silicon is preferably wet milled prior to addition of the other compounds. In a preferred embodiment the Al, Ti and Zr compounds are added in the form of a mixed solution, e.g. as a solution of sulphates of pH 0À7-1À2. The treated pigment may be milled in a fluid energy mill, optionally in the presence of an amine, alkanolamine or polyol. |
