METHOD FOR PREPARING HIGHLY-COLORIFIC HIGH-PURITY BISMUTH VANADATE BASED PIGMENTS.

摘要

PCT No. PCT/BE93/00047 Sec. 371 Date Jan. 17, 1995 Sec. 102(e) Date Jan. 17, 1995 PCT Filed Jul. 8, 1993 PCT Pub. No. WO94/01497 PCT Pub. Date Jan. 20, 1994A process for preparing a pigment based on bismuth vanadate by reacting an acidic solution of bismuth nitrate with a basic solution of ammonium metavanadate to form a precipitate in a very acidic reaction mixture with a pH value of between 1 and 2. The pH of the reaction mixture is brought to a value of about 7, and the temperature of the reaction mixture is established at 80 DEG C. or higher for a period of about 30 minutes. The reaction mixture is stirred for a period of time of at least one half hour until a pH of approximately 6.5 is reached, and then the precipitate is filtered from the reaction mixture. Finally, the precipitate is washed and dried to obtain a dried pigment.