| 摘要 |
PURPOSE:To manufacture gypsum wisker which is small in fiber diameter, great in aspect ratio, and excellent in breaking resistance with good efficiency by mixing CaSO4 and a solvent to lower the solubility of CaSO4 under a condition that alpha- type hemihydrate gypsum is crystallized. CONSTITUTION:When mixing with a bad solvent, a CaSO4 solution is preheated so that the temperature becomes more than the temperature at which alpha-type hemihydrate gypsum is crystallized and also regulated so that the solution becomes saturated solution at the crystallization temperature. Then, the CaSO4 solution is mixed with a bad solvent, e.g., methanol, ethanol, ethylene glycol, diethylene glycol, formic acid, acetic acid, DMF, etc., whereupon alpha-type hemihydrate gypsum wisker is crystallized abruptly to form a slurry. The slurry is subjected to solid-liquid separtion, and then the wisker is washed with methanol, etc., and dried at 60 to 80 deg.C., followed by a stabilization treatment, e.g., baking, etc., as needed, to manufacture a gypsum wisker of an average fiber diameter of less than 0.1 microns and an aspect ratio of more than 50. |
