Electrophotography, which is a method for visualizing image information by forming an electrostatic latent image, is currently employed in various fields. The term “electrostatographic” is generally used interchangeably with the term “electrophotographic.” In general, electrophotography comprises the formation of an electrostatic latent image on a photoreceptor, followed by development of the image with a developer containing a toner, and subsequent transfer of the image onto a transfer material such as paper or a sheet, and fixing the image on the transfer material by utilizing heat, a solvent, pressure and/or the like to obtain a permanent image.
During the development stage of electrophotography, as toner is magnetically attracted to the magnetic development roller, a negative charge build up is caused on the individual toner particles. This is called the triboelectric charge. Since both the toner and roller are charged negatively, the toner is repelled towards the positively charged areas of the drum to create the latent image. The negatively charged areas of the drum also repel toner, leaving only the image on the drum in dusted toner particles.
In electrostatographic reproducing apparatuses, including digital, image on image, and contact electrostatic printing apparatuses, a light image of an original to be copied is typically recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles and pigment particles, or toner. Electrophotographic imaging members may include photosensitive members (photoreceptors) which are commonly utilized in electrophotographic (xerographic) processes, in either a flexible belt or a rigid drum configuration. Other members may include flexible intermediate transfer belts that are seamless or seamed, and usually formed by cutting a rectangular sheet from a web, overlapping opposite ends, and welding the overlapped ends together to form a welded seam. These electrophotographic imaging members comprise a photoconductive layer comprising a single layer or composite layers.
When the triboelectric charge of a toner is low, a number of issues occur in electrophotography using that toner. For example, there may be color spittings during development (e.g., toner particles accumulate at baffle and nips between the roll and edge of housing of the machine during printing and release them suddenly during printing marking undesirable large marks on prints), low developer life, and background (e.g., spots caused by individual particles that you see on the permanent image) on the final image. These issues can be magnified when a toner's triboelectric charge decreases with age. These issues are more prevalent with magenta developer, because triboelectric charge is generally lower than for other colors. External additives have been used to minimize these issues, but it has previously not been possible to increase the triboelectric charge of magenta developer to that of other colors. Previous attempts to sue an internal charge control agent have not been effective, because magenta toner is often itself a powerful charge control agent. Thus, the use of large quantities of external additives, the majority of the additives being negatively charging silica, are generally required to yield a functional magenta toner design.