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Patent Searching and Data


Title:
PRODUCTION OF PENCIL LEAD
Document Type and Number:
Japanese Patent JPH04236276
Kind Code:
A
Abstract:

PURPOSE: To obtain a pencil lead having high flexural strength and tip strength and capable of writing a sharp line by filling a flaky substance, etc., as an extender material or coloring material in a state laminated and oriented perpendicular to the extrusion direction of the lead in the forming and extrusion of the filled compound.

CONSTITUTION: The pencil lead is composed mainly of a binder, a lubricant, an extender material and a coloring material. A composition at least containing a flaky substance such as boron nitride, talc, mica, graphite and sericite is used as the extender material and/or the coloring material. The above components are mixed and kneaded to obtain a film-formed substance. The films are laminated in a mold perpendicular to the pressing direction and hot- pressed. The compression-molded product is put into a cylinder of a ram-type extruder in a state directing the film layer perpendicular to the lead-extrusion direction and extruded to obtain the objective formed pencil lead.


Inventors:
KUWABARA HIDEO
Application Number:
JP7260891A
Publication Date:
August 25, 1992
Filing Date:
January 16, 1991
Export Citation:
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Assignee:
TOMBOW PENCIL
International Classes:
B43K19/18; C09D13/00; (IPC1-7): B43K19/18; C09D13/00