PURPOSE: To obtain the title magnetite of high saturation magnetization and dispersion stabilized for a long period of time by adding a basic aqueous solution to the organic layer resulting from extraction of a solution in which a sol of hydrated iron oxide is coagulated with an organic solvent, then adding a secondary surfactant to transfer the sol into the aqueous phase.
CONSTITUTION: A basic aqueous solution is added to an aqueous solution containing a soluble ferrous salt and a soluble ferric salt to adjust the pH to 1 to 4.5 to form a sol of hydrated iron oxide which is clear and positive and has particle size of less than 300 A on the average, then the sol is aged and stabilized at higher than room temperature. Then, the resultant dispersion is combined with a primary surfactant to coagulate a sol, which is combined with an organic dispersant whereby the sol is transferred into and dispersed in the organic phase. Then, the dispersion is washed with water to remove salts. The solution is separated to collect the organic phase. The organic phase is mixed with water, heated over 50°C and combined with a basic aqueous solution under stirring to adjust the pH to over 9, mixed with the secondary surfactant to transfer the ultrafine particles of magnetite into and disperse in the aqueous phase. Then, the organic dispersant is removed to give the objective magnetite.
| JP2006111728 | WIRE SAW CUTTING OIL |
IZEKI SEIJI
MATSUI TOSHITAKA
KIDA YOSHIE
