Liquid toner composition

#The present invention relates to a liquid toner composition suited for development of electrostatic charge images, magnetic patterns, and Direct Electrostatic Printing (DEP). More specifically, the present invention relates to a liquid toner composition allowing transfusion of the toner image from a temporary carrier to the final substrate at low temperature.

#It is well known in the art of electrographic printing and electrophotographic copying to form an electrostatic latent image corresponding to either the original to be copied, or corresponding to digitized data describing an electronically available image.

#In electrophotography, an electrostatic latent image is formed by uniformly charging a photoconductive member and image-wise discharging it by an image-wise modulated photo-exposure.

#The following description and examples illustrate a preferred embodiment of the present invention in detail. Those of skill in the art will recognize that there are numerous variations and modifications of this invention that are encompassed by its scope. Accordingly, the description of a preferred embodiment should not be deemed to limit the scope of the present invention.

#Only limited teachings concerning liquid toning systems and methods are provided in the literature. A method involving non-contact fusing by dispersant evaporation and film forming by a solvated binding resin, as is employed in some specific liquid developer compositions, is a simpler method, but it has intrinsic disadvantages in terms of the sensitivity of the final fused image towards solvents in general. Also, compositions that exhibit good film forming properties generally also exhibit only limited mechanical stability of the final print to rubbing, mutual tack of prints at elevated temperature, and the like, due to the composition of the binding resin itself and its mechanical properties

#An alternative to this process is “thermal” fusing whereby the toner particle itself is thermoplastic. In a preferred embodiment, this thermal fixing can be done in a so-called “non-contact” way. After the drying step, the toner particle can melt and adhere to the substrate. The energy can be conveyed to the particle to be fixed by convection, absorption of radiation, and the like. In “Non-contact” fusing, however, the dispersant has to evaporate prior to or as a first step in the fusing process and the problem of emission has to be resolved at that stage. Energy has to be delivered to evaporate the dispersant. After this step, additional energy has to be supplied to fuse the image. This will also heat up the vapors and intensify the emission tendency.