Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1999-12-15
2001-07-24
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S106100
Reexamination Certificate
active
06265127
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to electrostatographic developers and toners containing charge control agents.
BACKGROUND OF THE INVENTION
In electrography, image charge patterns are formed on a support and are developed by treatment with an electrographic developer containing marking particles which are attracted to the charge patterns. These particles are called toner particles or, collectively, toner. Two major types of developers, dry and liquid, are employed in the development of the charge patterns.
In electrostatography, the image charge pattern, also referred to as an electrostatic latent image, is formed on an insulative surface of an electrostatographic element by any of a variety of methods. For example, the electrostatic latent image may be formed electrophotographically, by imagewise photo-induced dissipation of the strength of portions of an electrostatic field of uniform strength previously formed on the surface of an electrophotographic element comprising a photoconductive layer and an electrically conductive substrate. Alteratively, the electrostatic latent image may be formed by direct electrical formation of an electrostatic field pattern on a surface of a dielectric material.
One well-known type of electrostatographic developer comprises a dry mixture of toner particles and carrier particles. Developers of this type are employed in cascade and magnetic brush electrostatographic development processes. The toner particles and carrier particles differ triboelectrically, such that during nixing to form the developer, the toner particles acquire a charge of one polarity and the carrier particles acquire a charge of the opposite polarity. The opposite charges cause the toner particles to cling to the carrier particles. During development, the electrostatic forces of the latent image, sometimes in combination with an additional applied field, attract the toner particles. The toner particles are pulled away from the carrier particles and become electrostatically attached, in imagewise relation, to the latent image bearing surface. The resultant toner image can then be fixed, by application of heat or other known methods, depending upon the nature of the toner image and the surface, or can be transferred to another surface and then fixed.
Toner particles often include charge control agents, which desirably provide uniform net electrical charge to toner particles without reducing the adhesion of the toner to paper or other medium. Also, the charge control agent desirably should provide a level of charge that is consistent with good transfer to and from the photoconductor and minimizes dust. Many types of positive charge control agents, materials that impart a positive charge to toner particles in a developer, have been used and are described in the published patent literature. In contrast, relatively few negative charge control agents, materials that impart a negative charge to toner particles in a developer, are known.
Prior negative charge control agents have a variety of shortcomings. Many charge control agents are dark colored and cannot be readily used with pigmented toners, such as cyan, magenta, yellow, red, blue, and green. Some are highly toxic or produce highly toxic by-products. Some are highly sensitive to environmental conditions such as humidity. Some exhibit high throw-off or adverse triboelectric properties in some uses. Use of charge control agents requires a balancing of shortcomings and desired characteristics to meet a particular situation.
The dihydropyridines are a well-known class of compounds, and their chemistry has been reviewed (Eisner, U. and Kuthan, J., Chemical Reviews, 72(1), 1, (1972)). Among the uses found for this class of materials are as pyridine precursors and in pharmaceuticals . However, there is no known use in the field of electrostatographics.
SUMMARY OF THE INVENTION
The invention provides an electrophotographic toner having polymeric binder and a charge control agent selected from the group consisting of 1,4-dihydropyridines having the following general structure:
wherein n is 1 or 2, where R
1
and R
2
may be the same or different and are H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted saturated or unsaturated heterocylic ring, or R
1
and R
2
taken together may form a saturated hydrocarbon ring system; with the proviso that when n is 2, R
2
is a bivalent group, preferably a substituted or unsubstituted cyclic or non-cyclic alkylene or a substituted or unsubstituted arylene.
R
3
and R
4
are independently alkyl or aryl;
R
5
is hydrogen, alkyl, or aryl;
X and Z are the same or different and may be cyano, substituted or unsubstituted alkanoyl, substituted or unsubstituted aroyl, substituted or unsubstituted alkoxycarbonyl, substituted or unsubstituted phenoxycarbonyl, substituted or unsubstituted phenylaminocarbonyl, substituted or unsubstituted alkylaminocarbonyl; or X together with R
3
,and/or Z together with R
4
, may also form a ring system.
It is also an object of the invention that negatively charging toners can be provided which have favorable charging characteristics.
DETAILED DESCRIPTION OF THE INVENTION
The term “particle size” as used herein, or the term “size,” or “sized” as employed herein in reference to the term “particles,” means the median volume weighted diameter as measured by conventional diameter measuring devices, such as a Coulter Multisizer, sold by Coulter, Inc. of Hialeah, Fla. Median volume weighted diameter is an equivalent weight spherical particle which represents the median for a sample; that is, half of the mass of the sample is composed of smaller particles, and half of the mass of the sample is composed of larger particles than the median volume weighted diameter.
The term “charge control,” as used herein, refers to a propensity of a toner addendum to modify the triboelectric charging properties of the resulting toner.
The term “glass transition temperature” or “T
g
”, as used herein, means the temperature at which a polymer changes from a glassy state to a rubbery state. This temperature (T
g
) can be measured by differential thermal analysis as disclosed in “Techniques and Methods of Polymer Evaluation,” Vol. 1, Marcel Dekker, Inc., New York, 1966.
As indicated above, the invention provides an electrophotographic toner having polymeric binder and a charge control agent selected from the group consisting of 1,4-dihydropyridines having the following general structure:
wherein n is 1 or 2 and R
1
and R
2
may be the same or different and are H, substituted or unsubstituted alkyl substituted or unsubstituted aryl, substituted or unsubstituted, saturated or unsaturated heterocyclic ring, or R
1
and R
2
taken together may form a saturated hydrocarbon ring system; with the proviso that when n is 2, R
2
is a bivalent group, preferably a substituted or unsubstituted cyclic or non-cyclic alkyl or a substituted or unsubstituted aryl.
R
3
and R
4
are independently alkyl or aryl;
R
5
is hydrogen, alkyl, or aryl;
X and Z are the same or different and may be cyano, substituted or unsubstituted alkanoyl, substituted or unsubstituted aroyl, substituted or unsubstituted alkoxycarbonyl, substituted or unsubstituted phenoxycarbonyl, substituted or unsubstituted phenylaminocarbonyl, substituted or unsubstituted alkylaminocarbonyl; or X together with R
3
, and/or Z together with R
4
, may form a ring system.
A preferred class of compounds consist of 1,4-dihydropyridines having the following general structure:
where R
1
is substituted or unsubstituted aryl, substituted or unsubstituted saturated or unsaturated heterocyclic ring, and R
2
is hydrogen or alkyl; wherein the substituents (up to 5) on the aryl are nitro, naphthyl, halo, carboxyl, amino, dialky amino, diarylamino, phenylaminocarbonyl, carbophenoxy, carboalkoxy, aroyl, alkanoyl, alkyl, alkoxy, hydroxy, and/or cyano.
R
3
and R
4
are alkyl;
R
5
is hydrogen or alkyl;
X and Z are the same or different and may be cyano, substituted or unsubstituted alkanoyl, sub
McGrath Gretchen S.
Srinivasan Satyanarayan A.
Wilson John C.
Eastman Kodak Company
Goodrow John
Konkol Chris P.
LandOfFree
1, 4-dihydrophyridine charge control agents for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with 1, 4-dihydrophyridine charge control agents for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and 1, 4-dihydrophyridine charge control agents for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2526031