The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 31, 1998
Filed:
Jul. 20, 1995
Masaaki Hoshiba, Fujioka, JP;
Mitsubishi Pencil Kabushiki Kaisha, Tokyo, JP;
Abstract
By kneading a composition containing a filler and an organic forming binder, extruding the composition, baking the composition in a non-oxidizing atmosphere, there is obtained a first baked lead containing, as a binder, a carbon obtained by the carbonization of the organic forming binder. Then, by heating the first baked lead in an oxidizing atmosphere to remove the binder carbon, there is formed a second baked lead composed of at least the filler. The pores of the second baked lead are impregnated with a solution containing perhydropolysilazane, subjecting the lead to a heat treatment in an inert atmosphere or an ammonia gas atmosphere to form a third baked lead containing the resultant silicon nitride. Finally, ink is filled into the pores of the third baked lead to provide a baked color pencil lead.