| 摘要 |
A process for preparing stable, essentially transparent alkaline silica aquasols having an average particle diameter of 5 to 10 millimicrons by adding an acidic silica sol to a dilute alkali metal silicate solution. The acidic silica sol is gradually added over a period of 4 to 8 hours such that not more than 25 weight percent of the acidic sol is added during any one hour period. At least 25 weight percent of the acidic sol is added while the temperature is maintained within a range of about 25 DEG C. to about 50 DEG C., at least about 7 weight percent to about 30 weight percent is added while the temperature is maintained within a range of about 50 DEG C. to about 90 DEG C. and the balance is added while the temperature is maintained within a range of about 70 DEG C. to about 100 DEG C. The last step is that of concentrating by evaporation of water. |
