METHOD FOR PRODUCTION OF amorphous felled KISELSYREPIGMENTER WITH HIGH GRINDING EFFICIENCY AND HIGH CLEANING EFFECT FOR USE IN DENTAL CARE FUNDS

摘要

1482354 Silicic acid pigments J M HUBER CORP 17 Sept 1974 [3 Oct 1973] 40413/74 Heading C1A An amorphous precipitated silicic acid pigment is made by providing an aqueous reaction medium containing an electrolyte which does not form a water-insoluble by product with the precipitating pigments; adjusting the pH of the medium to a predetermined value, within the range 8-10À4, at which the pigment is to be precipitated; simultaneously feeding an acid and an alkali metal silicate into the reaction medium so that a constant pH is maintained until precipitation of pigment is complete, and recovering the pigment from the aqueous medium, e.g. by acidifying and filtering. The acid may be H 2 SO 4 , HNO 3 or HCl and the electrolyte preferably comprises an alkali metal salt of the acid used. The alkali metal silicate may have SiO 2 /X 2 O=2À0 to 3À3 where x is Na, K or Li.