Browse Prior Art Database

TRIBOELECTRIC CHARGE CONTROL TREATMENT OF PIGMENTS BY FREEZE DRYING

IP.com Disclosure Number: IPCOM000023619D
Original Publication Date: 1978-Jun-30
Included in the Prior Art Database: 2004-Mar-31
Document File: 2 page(s) / 261K

Publishing Venue

Xerox Disclosure Journal

Abstract

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.

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XEROX DISCLOSURE JOURNAL

TRIBOELECTRIC CHARGE CONTROL Proposed Classification

TREATMENT OF PIGMENTS BY FREEZE U.S. Cl. 252/62.1
DRYING Int. Cl. GO3g 9/00
Joseph Mammino

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.

The freeze drying method used to separate the solvent from the
coating and pigment is disclosed in a number of prior art
patents, for example, U.S. Patents 3,622,366; 3,731,391; and
2,445,120. The method preferred is a freezing of the solution
containing evenly dispersed pigment followed by freeze drying
at low vacuum without agitation since such method allows an
even coati...