| abstract |
(57) [Summary] [Purpose] The pH is 2 to 5, and the particle size is 4 to 30 mμ. It is an object of the present invention to provide a method for producing a stable acidic silica sol which is [Structure] Stable acidic silica sol has the following (a) and (b) And (c) step. (A); Aluminium is added to a silica sol having a particle size of 4 to 30 mμ and a pH of 2 to 9 so that the Al 2 O 3 / SiO 2 molar ratio exceeds 0.0006 but is 0.004 or less. A step of adding an acid-alkali aqueous solution, (b); the silica sol obtained in the above step (a) at 0.5 to 20 at 80 to 250 ° C. Heating step, (c); by contacting the silica sol obtained in the above step (b) with an ion exchange resin, A step of generating an acidic silica sol having a pH of 2 to 5. |