TRIBOELECTRIC CHARGE CONTROL TREATMENT OF PIGMENTS BY FREEZE DRYING
Original Publication Date: 1978-Jun-30
Included in the Prior Art Database: 2004-Mar-31
Xerox Disclosure Journal
Disclosed is a method for adjusting the triboelectric proper-ties of a colored toner wherein the pigment is coated by freeze drying a solution of a coating material having the pig-ments suspended therein, combining these pigments with the toner resin for the purpose of forming toner particles and subsequently combining the mixture with a carrier for which the colorant has been triboelectrically adjusted. In one em-bodiment, a pigment such as color index pigment red 122 is disposed in a one-to-one weight ratio with styrene maleic anhydride copolymer resin dissolved in the solvent such as ammoniated water. This sample is frozen and the water sublimed under vacuum for about 8 hours until a substantially dry sample results. A toner is then subsequently prepared by one of the known forming methods when the above colorant is blended with a polymer such as styrene-n-butyl methacrylate copolymer and attrited into particles of about 15 microns average size.