| 摘要 |
PROBLEM TO BE SOLVED: To obtain a filler material excellent in electroconductivity by grinding expanded graphite or a molded form thereof and by coating the resultant powder with a specified amount of greater of a metal. SOLUTION: First, natural flaky graphite is treated with a mixture of concentrated sulfuric acid and concentrated nitride acid to form a graphite interlaminar compound which, in turn, is treated under heating up to about 1.000 deg.C to prepare expanded graphite. Secondly, the expanded graphite or a molded form thereof about 0.05-0.8g/cm<3> in bulk density of ground into powder about 0.1-0.5g/cm<3> in bulk density and about <=350μm in average particle size. Subsequently, the surface of the expanded graphite powder is coated with >=25 (pref. >=35)wt.%, based on the powder, of at least one kind of electroconductive metal such as copper, nickel and/or silver by nonelectrolytic plating, thus obtaining the objective filler material. |
