| 摘要 |
1445575 Preparation of silica pigments J M HUBER CORP 6 Aug 1973 [24 Aug 1972] 37271/73 Heading C1A Silicon dioxide pigment is prepared by adding acid to an alkali metal silicate solution until precipitation just begins (i.e. the solution becomes opalescent) then continuing to add acid and simultaneously adding AM silicate solution so that the pH remains constant until precipitation is complete. The pH may be maintained constant at a value between 8 and 11. The acid is preferably H 2 SO 4 but may be HNO 3 , HCl, acetic, formic or CO 2 . The AM silicate may be Na, K or Li and have an SiO 2 : alkali metal oxide molar ratio of 1 : 1 to 4 : 1. The precipitate may be separated, dried and ground. Water-soluble salts of Mg, Ca, Al and Zn may be added with the acid producing alumino-silicates or silicates. The silicate solution may be 1-2À5 lb. per U.S. gallon and the acid diluted to 10-25%. The solution temperature may be 100-250‹ F. The product may have a surface area of 50-200 m.<SP>2</SP>/g. and may be used as a reinforcing pigment in rubber, paint or paper manufacture. |
