HEXAGONAL BORON NITRIDE HAVING LOW CONTENT OF WATER-SOLUBLE BORON COMPOUND AND ITS PREPARATION

摘要

A hexagonally crystalline boron nitride containing water-soluble boron containing impurity in such a magntidue that amount of boron to be contained in an extract after boiling at 100 DEG C of pure water is less than or equal to 100 mu g/g-BN. In order to purify the boron nitride, a purification process is carried out according to the steps of preparing fine particles of boron nitride powder; dispersing the boron nitride powder in a disperser and stirred for a given period of time for removing water-soluble boron containing impurity; and drying the boron nitride in an atmosphere, in which vapor pressure is maintained lower than or equal to 10 mmHG and/or the process temperature is maintained lower than or equal to 100 DEG C.