| 摘要 |
PROBLEM TO BE SOLVED: To provide a calcined pencil lead excellent in flexural strength and writing density, destroying the conventional negative correlation between the flexural strength and the writing density, in which a calcined pencil lead with enhanced flexural strength tends to have low writing density due to less abrasion wear in writing, while a calcined pencil lead with enhanced writing density tends to have low flexural strength, being easily broken by writing pressure or drop impact.SOLUTION: The calcined pencil lead includes at least graphite and oxygen-containing inorganic plate-like particles having an aspect ratio of 5 or more and a grain size of 1 μm or more. The content of the inorganic plate-like particles is 0.1 to 0.45 wt.% in the lead body and 0.15 to 0.75 wt.% relative to graphite. The inorganic plate-like particles are cleavable inorganic amorphous plate-like particles in an amorphous state. |
