| 摘要 |
<p>1358636 Modified TiO 2 BRITISH TITAN Ltd 9 March 1973 [5 April 1972] 15726/72 Heading C1N [Also in Division C5] A TiO 2 comprising microcrystalline rutile TiO 2 having an average particle size of 10-100 Š together with larger size rutile particles may be prepared by mixing rutile TiO 2 particles with a solvent therefor, e.g. H 2 SO 4 , dissolving TiO 2 from the surfaces of the particles, and cooling to precipitate the microcrystalline TiO 2 . The core particles preferably have an average size of 0À2-0À25 Á. The initial TiO 2 may be calcined sulphate process TiO 2 , chloride process TiO 2 , or natural mineral rutile. The H 2 SO 4 preferably contains (NH 4 ) 2 SO 4 and may be heated with the TiO 2 at 85-205‹ C. and then allowed to cool naturally or quenched. The product may be filtered, boiled with NaOH, washed with water, dried at 120‹ C. and optionally fluid energy milled. It may be heated at at least 300‹ C., e.g. 400‹ C., to increase the surface area, e.g. to 210 m.<SP>2</SP>/g.</p> |
