DISPERSION OF CARBON BLACK IN POLYESTERS DURING POLYMERIZATION
Original Publication Date: 1979-Dec-31
Included in the Prior Art Database: 2004-Apr-02
Xerox Disclosure Journal
Disclosed is a process for the dispersion of large amounts of carbon black in either amorphous or crystalline polyesters during ester interchange polymerization. Generally, this is accomplished by the addition of carbon black in an amount of about 10% by weight of the polyester to the initial monomer mixture, the carbon black having a pH of less than 7, although acidic carbon black can be used by neutralizing it with a base such as sodium hydroxide. This process results in improving the amount of carbon black dispersed, eliminates the melt blending step of toner fabrication and provides a toner that can be used in electrophotographic imaging systems. In one embodiment, there is polymerized a poly(neopenty1 isophthalate) in the presence of a 10% by weight of a predispersed Molacco H (coated with polystyrene) a basic carbon black amorphous polyester. In a similar manner, poly(neopenty1 isophthalate) was polymerized in the presence of a basic carbon black having medium electrical resistivity for the purpose of reducing the conductivity of the pigmented resin. The carbon blacks used are commerically available from Cabot Corporation or Columbian Carbon Company.