Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Patent
1991-03-04
1991-10-29
Martin, Roland
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
430110, 430120, G03G 909, G03G 9097, G03G 1308
Patent
active
050615858
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a blue coloring agent based on a triaminotriphenylmethane dyestuff for dyeing toners and developers for electrophotographic copying processes which is present in controlled substitution as a highly crystalline sulfate salt and consequently has particularly beneficial charge control properties. Owing to its color, the coloring agent is furthermore suitable as a color-imparting component for blue and green toners and developers or as a color modifier for black and brown toners and developers.
In electrophotographic copying processes, a "latent charge image" is produced, for instance, on a photoconductor. This is carried out, for instance, by charging up the photoconductor with a corona discharge and subsequently exposing the electrostatically charged surface of the photoconductor to an image, the drainage of charge to the earthed substrate at the exposed points being effected by the exposure. Subsequently, the "latent charge image" produced in this manner is developed by applying a toner.
In a subsequent step, the toner is transferred from the photoconductor to, for instance, paper, textiles, foils or plastic and fixed thereon, for instance, by pressure, irradiation, heat or exposure to solvents. The used photoconductor is subsequently cleaned and is available for a fresh copying operation.
Numerous patents describe the optimization of toners, inter alia, the effect of the toner binder (variation of resin/resin components or wax/wax components), the effect of control agents or other additives or the effect of additives or the effect of carriers (in two-component developers) and magnetic pigments (in one-component developers) being investigated (U.S. Pat. No. 2,221,776). A measure of the toner quality is its specific charging capacity Q/M (charge per unit mass).
Recently, positively chargeable toners have acquired significance, inter alia owing to their use in laser printers employing inorganic photoconductors or in copiers which are equipped with organic photoconductors (OPC) for copying the latent charge image. The inexpensive organic photoconductors are being used to an increasing extent, for instance, as a drum or master strip, primarily because of their versatile use, and because they can be simply disposed of. In order to obtain electrophotographic toners or developers with positive triboelectric charging capacity, so-called control agents (also termed charge control agents) are often added. In addition to the sign of the charge control, the extent of the control effect is important since a higher efficiency makes it possible to use a smaller amount.
Apart from sign and the level of the control effect of a charge control agent, its effect on the charging constancy of the toner is important. In practice this is of central significance insofar as the toner in the developer mixture is exposed to a considerable activation time before it is transferred to the photoconductor because it may remain in the developer mixture for a period covering the production of up to several thousand copies during the copying and printing operation. The requirement imposed on the toner is therefore that, regardless of the activation time, as constant a toner charging capacity as possible is ensured. Since toner binders alone, effect, as a rule, a considerable change in the charging capacity as a function of the activation time, it is the task of a charge control agent, on the one hand, to set the sign and level of the toner charging capacity, and, on the other hand, to counteract the drift in charging capacity of the toner binder and to ensure constancy of the toner charging capacity. Charge control agents which are unable to prevent the toner or developer exhibiting a high charge drift (aging) for a prolonged duration of use which may even have the effect that the toner or developer undergoes a charge reversal are therefore unsuitable for practical use.
The object of the present invention was therefore to find a charge control agent with positive control effect which can be set as
REFERENCES:
patent: 4560635 (1985-12-01), Hoffend et al.
patent: 4822707 (1989-04-01), Inoue et al.
Macholdt Hans-Tobias
Sieber Alexander
Hoechst Aktiengesellschaft
Martin Roland
LandOfFree
Blue coloring agent for electro-photographic copying processes w does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Blue coloring agent for electro-photographic copying processes w, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Blue coloring agent for electro-photographic copying processes w will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1399862