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Procedure for using and Optimizing Fumed Silicas as Effective Surface Specific Charge Control Agents

IP.com Disclosure Number: IPCOM000105630D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Diaz, A: AUTHOR [+2]

Abstract

Fumed silica of 7-40nm size is added as an extraparticulate to toners to enhance their solid flow properties. Fumed silicas also affect the charging. These silicas impart a strong negative charge to the toners when added as an extraparticulate (both dual and monocomponent). Therefore, these silica can be considered as surface-specific charge additives. Establishing the optimum extraparticulate content is not straight-forward because a minimum amount is necessary for proper charging and flow performance, and excessive amounts quickly deteriorate the charging performance of the developer system. The optimum content can be determined from the q/m (dual component) rolling time plots using different extraparticulate levels. With the addition of silica, the initial rate of charging of the toner is enhanced.

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Procedure for using and Optimizing Fumed Silicas as Effective Surface Specific Charge Control Agents

      Fumed silica of 7-40nm size is added as an extraparticulate to
toners to enhance their solid flow properties.  Fumed silicas also
affect the charging.  These silicas impart a strong negative charge
to the toners when added as an extraparticulate (both dual and
monocomponent).  Therefore, these silica can be considered as
surface-specific charge additives.  Establishing the optimum
extraparticulate content is not straight-forward because a minimum
amount is necessary for proper charging and flow performance, and
excessive amounts quickly deteriorate the charging performance of the
developer system.  The optimum content can be determined from the q/m
(dual component) rolling time plots using different extraparticulate
levels.  With the addition of silica, the initial rate of charging of
the toner is enhanced.  With toners containing low extraparticulate
content, the q/m reaches a plateau with time, and it does not
deteriorate with prolonged rolling times.  With higher silica
contents, the q/m reaches a maximum value, then deteriorates or
becomes erratic with continued rolling times due to contamination of
the developer system.  The lowest silica content at which this
maximum appears, is the limiting content for charging performance.
The silica content employed should be below this quantity.  The flow
of the toner improves with the addition of minor amounts...