Method for making leads for color pencils, cosmetic pencils and colored chalk
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United States of America Patent
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-
Nov 13, 2001
Grant Date -
N/A
app pub date -
Oct 20, 1997
filing date -
Oct 21, 1996
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A simplified method for producing a lead for color pencils, cosmetic pencils and colored chalk with good down stroke behavior involves mixing powdered or granular base materials containing a thermolabile, polymeric binding agent, inorganic filler materials and a coloring agent with water and then extruding the mixed materials to form raw leads, which extruded material is subsequently heat treated at the binding agent decomposition temperature for a time sufficient to partially decompose the binding agent. Enough water is mixed with the base material to achieve a lead mass of approximately 5 parts by weight of base material and 1 part by weight of water.
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- Non-US Classification not provided for expired patents
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