Electrophotographic liquid developer for the reversal development of negatively-charged images

摘要

An electrophotographic liquid developer is disclosed which is useful in the development of negatively charged charge images. The developer comprises an electrically insulating carrier liquid of high electrical resistivity and a low dielectric constant, a pigment or dye, a resinous binder, a charge controller comprising a copolymer of N-vinyl-2-pyrrolidone and a methacrylic acid ester, and a poly-N-vinyl-2-pyrrolidone which has been alkylated with an alpha -olefin. A process for producing the liquid developer is also disclosed.