Abstract: An electrophotographic two-component system developer is described, comprising a positive charging toner and a negative charging carrier of the dispersed magnetic powder type, wherein a hydrophilic alumina particle is adhered onto the surface of said positive charging toner and a negative charging carrier has a volume average particle diameter of from 30 to 80 .mu.m. The developer provides reduced toner cloud upon development processing and provides toner images free from fog.

Abstract: Dry toners for use in electrostatic latent image development comprising a colorant in a resin binder are described, wherein said resin binder comprises a polyester containing --COOH groups in which at least one of the --COOH groups is replaced with nitrogen-containing compounds such as amines, ammonium salts, betaines, pyridinium salts, and azines. These toners are superior in development of negatively charged latent images and exhibit good low temperature fixability.

Abstract: A toner for developing an electrostatic latent image characterized by a vinyl copolymer whose acid value is in the range of about 5 to 100.

Abstract: A developer for electrostatic images consisting essentially of particles comprising a pigment, a binder and an offset-preventing agent selected from the group consisting of aliphatic fluorocarbon compounds and fluorochlorocarbon compounds is disclosed. When this developer is used, a high offset-preventing effect can be attained at the fixing step even if the amount incorporated of the offset-preventing agent is small, and further, the developing operation can be performed in good conditions. By incorporation of this offset-preventing agent, the flowability of particles of the developer and charge characteristics of the developer can be remarkably improved.

Abstract: A dry toner that is heat-fixable and/or press-fixable is disclosed, comprising (a) a colorant; and (b) a graft copolymer comprising (i) a crystalline polymer having a melting point of from 45.degree. C. to 200.degree. C., which is prepared from one or more monomers selected from ethylene, propylene and vinyl acetate, and (ii) an amorphous polymer having a glass transition point of 45.degree. C. or more, which is prepared from one or more vinyl monomers.

Abstract: A developer for electrostatic images comprising a binder medium and a pigment dispersed in the binder medium is disclosed. This binder medium comprises (A) a thermoplastic or rubbery polymer containing a member selected from the group consisting of a halogen atom and a nitrile group at a concentration of at least 100 milliequivalents per 100 g of the polymer and (B) a binder having a melting temperature lower than that of the polymer (A) at an (A)/(B) mixing weight ratio of from 1/20 to 1/1. The halogen- or nitrile-containing polymer (A) is present in the form of fine particles dispersed in the continuous phase of the binder (B). This developer has good flowability and charge characteristics at the developing step and shows an excellent offset-preventing effect at the fixing step.