| 摘要 |
PROBLEM TO BE SOLVED: To obtain a black pencil lead which provides smooth feeling in writhing and is excellent in density of drawn lines and strengths by molding a mixture of a graphite powder, a clay powder, a specific compd., and water, drying and baking the resultant molded item, and impregnating it with an oil or fat. SOLUTION: A mixture comprising a graphite powder pref. having an average particle size of 15μm or lower, a clay mineral contg. at least 97wt.% particles with sizes (by the Andreasen method) of 3μm or lower and 1wt.% or lower particles with sizes of 10μm or higher (e.g. montmorillonite bentonite), a sodium salt of aβ-naphthalenesulfonic acid-formalin condensate, water, and if necessary a water-soluble saccharide (e.g. gum arabic and/or PVA-grafted starch) and/or a sugar alcohol (e.g. sorbit) is molded, dried, and baked. The resultant product is impregnated with an oil or fat (e.g. lard).
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