Chelating positive charge director for liquid electrographic toner
US5445911A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 28, 1993 |
| Grant date | Aug 29, 1995 |
| Priority date | — |
| Expiry date | Jul 28, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G9/13
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention is a positive charge director for liquid electrographic toners. The charge director comprises a very strongly chelating functional group covalently bonded in the resin coating or pigment component, or an intrinsic part of the pigment component, of the toner particle, and a very weakly associated, preferably ionic, molecule dispersed in the liquid phase to achieve charge separation. The strong chelation site on the resin is prepared, via well-known polymer chemistry. For the ionic molecule, preferred cations are those with no regulatory, health or environmental issues, such as K+, Na+, Ca.sup.2+, Al.sup.3+, Zn.sup.2+, Zr.sup.4+, Mg.sup.2+, ammonium (NH.sub.4 +), and organic cations. The chelate-containing resin is brought into dispersion with the liquid phase containing the ionic molecule. When this is done, the equilibria that compete for the cation are such that it is released from the ionic molecule and bound in the chelate. The toner particle is left with a net positive charge which is permanent, but which is balanced by an equal, opposite charge on the counter anionic species in the continuous phase. Preferably, there are no other sources of charge in the dispersi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.