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.
本发明的基础是发现通过乳液聚合法制造的调色剂
树脂的特性可以通过在其合成过程中使用二元酸环脂族
乳化剂而得到改善。与使用标准皂(如
松香酸皂和
脂肪酸皂)制成的
树脂相比,使用这种二元酸环脂族
乳化剂制成的调色剂
树脂不会因
树脂中残留的皂而产生明显的电荷效应。由于在凝结过程中不需要使用盐,因此灰分含量通常也较低。由于灰分含量低,用二元酸皂制成的调色剂
树脂具有出色的抗湿敏性和吸附性。众所周知,吸附的
水分会中和电荷,因此,与传统皂类
树脂相比,用这些
树脂制成的调色剂具有更好的电荷稳定性。用这些
树脂制成的墨粉还能大大提高对纸张的附着力。本发明更具体地公开了一种制备特别适用于墨粉
树脂的聚合物的工艺,该工艺包括:(1) 在二元酸环脂族
乳化剂存在下,乳化共聚
乙烯基芳香族单体和选自共轭二烯单体和选自
丙烯酸烷基酯单体和
甲基丙烯酸酯单体组成的组中的第二种单体,以生产聚合物;(2) 从
水乳液中回收聚合物。