GRANULAR ALUMINA, MANUFACTURING METHOD OF GRANULAR ALUMINA AND COMPOSITION CONTAINING GRANULAR ALUMINA

摘要

PROBLEM TO BE SOLVED: To provide granular alumina used as a filler in resin composition of high heat conductivity.;SOLUTION: In the used granular alumina, 50% cumulative average diameter (D50) expressed in terms of volume is within the range of 1.5 to 4 μm, a ratio of D90 to D10 (D90/D10) is ≤2.5, grains of ≥10 μm secondary particle size are ≤0.1 mass %, grains of ≤0.5 μm secondary particle size are ≤5 mass %, α-phase is a main phase, a ratio of long axis diameter (DL) to short axis diameter (DS) of the granular alumina (DL/DS) is ≤2 and a ratio of D50 to average primary particle size (DP) (D50/DP) is ≤2.5. Halide except fluoride is added to aluminum hydroxide having BET value within the range of 3 m²/g to 20 m²/g and SiO₂ content of ≤0.02%, the mixture is calcined in a closed vessel and then is cracked to manufacture the granular alumina.;COPYRIGHT: (C)2003,JPO