| 摘要 |
PURPOSE:To improve stability of electric charge and stability of dispersion of an electrophotographic liquid developer by using a resin consisting of an ethylenic copolymer contg. acidic groups and being insoluble in a nonpolar liquid or swellable by the nonpolar liquid, and incorporating a nitrogen (N) atom contg. polymer or copolymer soluble in the nonpolar liquid into the developing agent. CONSTITUTION:A toner to be used consists of a nonpolar liquid having >=10<9>OMEGA.cm electric resistance and <=3 dielectric constant, a colorant, and a resin, as primary components. The resin consists of an ethylene copolymer contg. acidic groups and being insoluble in the nonpolar liquid or swellable by the nonpolar liquid. A mixture of the copolymer with a liquid having affinity with said copolymer is prepd. by stirring a mixture of the copolymer with the liquid at a temp. above a softening point of the copolymer. Then, the mixture is solidified by cooling it to below the softening point, and the solidified product is crushed coarsely and dispersed in the nonpolar liquid by the wet process to obtain thus a concentrated dispersion. An N-atom-contg. polymer is added in a stage of prepg. a liquid developer by diluting the dispersion with a carrier liquid. Thus, a liquid developer having high stability for electric charge and high stability for dispersion is obtd. |
