Process for producing toner resin with amino acid soaps

摘要

This invention is based upon the discovery that the characteristics of toner resins made by emulsion polymerization can be improved by utilizing amino acid soaps. Such amino acid soaps are typically salts of alkyl sarcosinates, such as ammonium lauryl sarcosinate and sodium lauryl sarcosinate. Toner resins which are made utilizing such amino acid surfactants do not exhibit significant electrical charge effects from the residual level of amino acid soap in the resin compared to resins made using other soap types, such as rosin acid soaps, fatty acid soaps, and the like. 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 amino acid 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 other soaps since adsorbed moisture is known to neutralize electrical charges. 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 an amino acid soap to produce the polymer; and (2) recovering the polymer from the aqueous emulsion.