Method for the production of pencil leads and pencil leads produced by the method
CA 1300816 C · Owner: Bard, Martin · Inventors: Baumgart, Hans-Georg; Bard, Martin
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention is concerned with the production of pencil leads and also pencil leads as produced by the proposed method. In accordance with the invention graphite enamel, frit and quartz flour, preferably at least approximately in a ratio of one part of graphite, two to four parts of enamel frit and one part of quartz flour are processed to form a starting mixture, which is then pressed into the form of a lead, is dried and is fired. The invention renders it possible to perform sintering below a temperature of 550°C and accordingly to perform the sintering firing operation in a normal oxidizing atmosphere.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted May 19, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended May 19, 2009.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.