| 摘要 |
PROBLEM TO BE SOLVED: To easily obtain alumina grains which are free from aggregation and having a sharp grain size distribution without using high pressure by adding water and dispersant to aluminum hydroxide or alumina hydrate, pulverizing the mixture and drying the resulted slurry, then adding a crystal growth agent to the mixture and firing the same. SOLUTION: The water and the dispersant of an inorganic system or organic system is added to raw material consisting of the aluminum hydroxide or the alumina hydrate and the mixture is pulverized down to <=5μm in central grain size to obtain a slurry. The crystal growth agent of at least one kind among phosphoric acid, phosphate, phosphoric acid compound, silicic acid, silicate and silicic acid compound is added to the slurry before or after the drying of the slurry and the slurry is dried. The dry powder is fired at 1000 to 1600 deg.C, by which the alumina tabular grains are obtained. The resulted alumina tabular grains are the alumina particles of 0.2 to 100μm in average particle size, <=3μm in thickness and >=5 in aspect ratio (particle diameter/thickness) and are extremely good in dispersibility in water.
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