Toner resin with improved adhesion properties

This invention is based upon the discovery that the characteristics of toner resins made by emulsion polymerization can be improved by utilizing diacid cycloaliphatic emulsifiers in the synthesis thereof. Toner resins which are made utilizing such diacid cycloaliphatic emulsifiers do not exhibit significant electrical charge effects from the residual level of soap in the resin compared to resins made using standard soaps; such as, rosin acid soaps and fatty acid soaps. They also generally contain a lower level of ash since salts do not need to be used in their coagulation. As a result of the low level of ash, the toner resin made from the diacid soap exhibits excellent resistance to moisture sensitivity and adsorption. This feature gives the toners made from these resins better electrical charge stability compared to resins made from conventional soaps since adsorbed moisture is known to neutralize electrical charges. Toners made from these resins also exhibit greatly improved adhesion to paper. This invention more specifically discloses a process for preparing a polymer which is particularly useful as a toner resin, which comprises (1) emulsion copolymerizing a vinyl aromatic monomer and a second monomer selected from the group consisting of conjugated diene monomers and an acrylate monomer selected from the group consisting of alkyl acrylate monomers and methacrylate monomers in the presence of a diacid cycloaliphatic emulsifier to produce the polymer and (2) recovering the polymer from the aqueous emulsion.