Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-05-06
2004-02-17
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S108300, C430S108400, C430S108500, C430S111410, C430S122520
Reexamination Certificate
active
06692880
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electrophotographic toners. More particularly, the present invention relates to electrophotographic toners having stable triboelectric properties and methods of printing images using these toners.
The image quality currently available is generally good in that prints have high solid area reflection density, low background in non-image areas, and consistent print quality from toner lot to toner lot and from the start of a new developer until it is replaced. The present toners, however, are not as good with respect to fusing quality and toner ruboff (e.g., the abrasion resistance of the fused image).
In attempting to improve toner ruboff, a wax, for instance, can be included in the toner. However, waxes can effect triboelectric properties of a toner. If the triboelectric properties are increased, the resulting prints may look gray because less toner is being transferred onto the paper. In addition, the toners may not be as free flowing as desired.
Accordingly, new toner formulations which provide an improved or reduced ruboff without affecting the charge and/or flow properties would be beneficial to those in the industry.
SUMMARY OF THE PRESENT INVENTION
A feature of the present invention is to provide an electrophotographic toner having stable triboelectric properties.
Another feature of the present invention is to provide a toner formulation that has improved ruboff properties.
A further feature of the present invention is to provide an electrophotographic toner formulation that reduces ruboff and yet provides satisfactory charge and/or flow properties.
Additional features and advantages of the present invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention will be realized and attained by means of the elements and combinations particularly pointed out in the written description and appended claims.
To achieve these and other advantages and in accordance with the purposes of the present invention as embodied and broadly described herein, the present invention relates to a toner formulation containing at least one toner resin, at least one first charge control agent capable of providing a consistent or controllable level of charge, at least one second control agent capable of providing a sustained level of charge, and optionally at least one surface treatment agent, and optionally at least one release agent, and optionally at least one colorant.
The present invention further relates to a method of decreasing toner ruboff on an image and involves printing an image on a substrate using the above-identified toner formulation of the present invention.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide a further explanation of the present invention, as claimed.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention relates to toner formulations preferably having stable triboelectric properties and also preferably having acceptable toner ruboff properties. Further, preferably the toner formulations of the present invention are free flowing. In more detail, the toner formulations of the present invention contain at least one toner resin, at least one first charge control agent capable of providing a consistent level of charge and at least one second charge control agent capable of providing a sustained level of charge. The toner formulation preferably further contains at least one surface treatment agent which is optional and optionally at least one release agent. Optionally, the toner formulation can contain at least one colorant and other conventional components typically found in toner formulations.
The toner formulations of the present invention can be used in single component toners or two component toners. Preferably, the toner formulations of the present invention are used in two component toner/developer systems.
In the present invention, the toner resin can be any conventional polymeric resin or combination of resins typically used in toner formulations using conventional amounts.
The toner particles can include one or more toner resins which can be optionally colored by one or more colorants by compounding the resin(s) with at least one colorant and any other ingredients. Although coloring is optional, normally a colorant is included and can be any of the materials mentioned in
Colour Index,
Volumes I and II, Second Edition, incorporated herein by reference. The toner resin can be selected from a wide variety of materials including both natural and synthetic resins and modified natural resins as disclosed, for example, in U.S. Pat. Nos. 4,076,857; 3,938,992; 3,941,898; 5,057,392; 5,089,547; 5,102,765; 5,112,715; 5,147,747; 5,780,195 and the like, all incorporated herein by reference. Preferred resin or binder materials include polyesters and styrene-acrylic copolymers. The shape of the toner particles can be any shape, regular or irregular, such as spherical particles, which can be obtained by spray-drying a solution of the toner resin in a solvent. Alternatively, spherical particles can be prepared by the polymer bead swelling techniques, such as those described in European Patent No. 3905 published Sep. 5, 1979, which is incorporated in its entirety by reference herein.
Typically, the amount of toner resin present in the toner formulation is from about 85 to about 95% by weight of the toner formulation.
The term “charge-control” refers to a propensity of a toner addendum to modify the triboelectric charging properties of the resulting toner. A very wide variety of charge control agents for positive and negative charging toners are available. Suitable charge control agents are disclosed, for example, in U.S. Pat. Nos. 3,893,935; 4,079,014; 4,323,634; 4,394,430; and British Patent Nos. 1,501,065 and 1,420,839, all of which are incorporated in their entireties by reference herein. Additional charge control agents which are useful are described in U.S. Pat. Nos. 4,624,907; 4,814,250; 4,840,864; 4,834,920; 4,683,188; and 4,780,553, all of which are incorporated in their entireties by reference herein. Mixtures of charge control agents can also be used. Particular examples of charge control agents include chromium salicylate organo-complex salts, and azo-iron complex-salts, an azo-iron complex-salt, particularly ferrate (1-), bis[4-[(5-chloro-2-hydroxyphenyl)azo]-3-hydroxy-N-phenyl-2-naphthalenecarboxamidato(2-)], ammonium, sodium, and hydrogen (Organoiron available from Hodogaya Chemical Company Ltd.).
With respect to the first charge control agent, as indicated above, one or more different types of first charge control agents can be used. The first charge control agent is capable of providing a consistent level of charge (e.g., controllable level of charge). The first charge control agent has the ability to “dial in” the desired charge level. For purposes of the present invention, a preferred consistent level of charge is from about −10 to about −30 micro C/gm. The toner Q/m ratio can be measured in a MECCA device comprised of two spaced-apart, parallel, electrode plates which can apply both an electrical and magnetic field to the developer samples, thereby causing a separation of the two components of the mixture, i.e., carrier and toner particles, under the combined influence of a magnetic and electric field. A 0.100 g sample of a developer mixture is placed on the bottom metal plate. The sample is then subjected for thirty (30) seconds to a 60 Hz magnetic field and potential of 2000 V across the plates, which causes developer agitation. The toner particles are released from the carrier particles under the combined influence of the magnetic and electric fields and are attracted to and thereby deposit on the upper electrode plate, while the magnetic carrier particles are hel
Alexandrovich Peter
Fields Robert D.
Guistina Robert
Tyagi Dinesh
Wilson John C.
Goodrow John
Heidelberger Druckmaschinen AG
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