SULFUR CHARGE CONTROL ADDITIVE
Original Publication Date: 1996-Feb-29
Included in the Prior Art Database: 2004-Apr-07
Xerox Disclosure Journal
Disclosed is a negative charge control additive comprising elemental sulfur for use in electrophotographic developers and imaging processes. The charge additive may be incorporated into the toner composition by, for example, adding the charge additive to the bulk resin during melt mixing, adding the charge additive to the surface of the toner particles as a submicron powder coating, and as a surface additive coated on the surface of a metal oxide surface additive, such as a 10 weight percent elemental sulfur solution coated on the surface of a hydrophobic submicron AEROSIL particles. The sulfur charge additive can be used in developer formulations in amounts of from about 0.001 to about 5 weight percent based on the total weight of toner and the desired disposition of the charge additive in the formulation. The use of elemental sulfur as a negative charge control additive is particularly useful in combination with known poly (styrene butadiene) and polyester resins. The toner formulations containing the sulhr charge enhancing additive can be used with known carriers, for example partially resin coated iron beads, to achieve negative triboelectric values from -10 to about -30 microcoulombs per gram with admix values of 1 minute or less. The sulfur charge additive containing toner formulations are generally suitable for use in developers with other conventional additives present, such as flow aids, waxes, release agents, and the like.