| 摘要 |
1479329 Silica filler LEE PHARMACEUTICALS 27 Sept 1974 [28 Sept 1973] 42177/74 Heading ClA A naturally occurring silica is (a) treated with excess strong mineral acid (as defined) in aqueous solution at between 30‹ C. and the boiling point of the acid for at least one hour and (b) heating the silica to a temperature of from 900‹ to 1200‹ C. to remove the acid insoluble impurities. Strong mineral acids are those which will remove acid-soluble impurities, but will not dissolve silica. Typical acids are HCl (5% to saturation), H 2 SO 4 (10 to 100%) and HNO 3 (3% to saturation). The acid (a) and thermal (b) treatment steps may be performed in any sequence and either step may be repeated a plurality of times. The treated silica may be coated with silanes to provide effective bonding with epoxy or other synthetic resinous material. |
