| 摘要 |
<p>Rutile pigment is subjected to two after treatments, the after treatments in each case comprising treating an aqueous suspension of rutile in any order with a water soluble silicate and/or a water soluble aluminium salt and/or another water soluble metal salt and precipitating, washing, drying and grinding the pigment after each treatment. After the two treatments the pigment is calcined at 450 to 600 DEG C. In the examples the pigment is dispersed in water using sodium metaphosphate and sodium hydroxide. The silica is added as a solution of waterglass and the aluminium oxide as a solution of aluminium sulphate, and the precipitation is brought about by adding ammonia until the pH of the solution is 8.1. The concentration of the additive used may be between 0.5 and 5.0% of each additive for each after treatment.</p> |
