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:
Dec. 24, 1991
Filed:
Oct. 12, 1989
Applicant:
Inventor:
Werner Handl, Altdorf, DE;
Assignee:
J. S. Staedtler GmbH & Co., , US;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C04B / ;
U.S. Cl.
CPC ...
264 63 ; 106 19 ; 264 56 ;
Abstract
A method and composition are disclosed for the preparation of pencil lead from clay, graphite and optionally other material, wherein the clay or the clay/graphite mixture is digested with water, pressed, dried and fired, and at least one alkali phosphate, alkali borate and/or alkali carbonate is added before or as part of the digestion of the clay or the clay/graphite mixture.