Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1999-05-04
2002-06-25
Martin, Roland (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C556S055000
Reexamination Certificate
active
06410198
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a novel zirconium compound. Further, it relates to a novel zirconium compound useful as a charge control agent for an electrophotographic toner which is used to develop an electrostatic latent image in the fields of electrophotography, electrostatic recording, etc., and an electrophotographic toner containing this compound.
BACKGROUND ART
In an image-forming process by means of an electrophotographic system, an electrostatic latent image is formed on a photoconductive material made of an inorganic or organic material, and the latent image is developed by a toner, then transferred and fixed on a paper sheet or plastic film to obtain a visible image. The photoconductive material may be positively electrifiable or negatively electrifiable depending upon its construction. When a printed portion is remained as an electrostatic latent image by exposure, development is conducted by means of an oppositely electrifiable toner. On the other hand, when a printed portion is destatisized for reversal development, development is conducted by means of an equally electrifiable toner.
A toner is composed of a binder resin, a coloring agent and other additives. However, in order to impart desired tribocharge properties (such as desired charge up speed, tribocharge level and tribocharge level stability), stability with time and environmental stability, it is common to use a charge-control agent. The properties of the toner will be substantially affected by this charge-control agent. When a positively electrifiable photoconductive material is used for development by an oppositely electrifiable toner, or when a negatively electrifiable photoconductive material is used for reversal development, a negatively electrifiable toner is used. In such a case, a negatively electrifiable charge-control agent is added.
Further, in a case of a color toner for which the market is expected to expand in future, it is necessary and indispensable to use a pale-colored or preferably colorless charge-control agent which does not affect the color of the toner. Such pale-colored or colorless charge-control agents may, for example, be metal complex salt compounds of salicylic acid derivatives (e.g. JP-B-55-42752, JP-A-61-69073, JP-A-61-221756 and JP-A-9-124659), aromatic dicarboxylic acid metal salt compounds (e.g. JP-A-57-111541), metal complex salt compounds of anthranilic acid derivatives (e.g. JP-A-62-94856) and organic boron compounds (e.g. U.S. Pat. No. 4,767,688 and JP-A-1-306861).
However, these charge-control agents have various drawbacks such that some of them are chromium compounds which are feared to be detrimental to environmental safety which is expected to be viewed as increasingly important, some of them are compounds which can not be made adequately colorless or pale-colored as required for toners, some of them have inadequate electrifying effects or provide oppositely electrifiable toners, or some of them are poor in dispersibility or chemical stability as compounds themselves. Thus, none of them has fully satisfactory properties as a charge-control agent.
Accordingly, it is an object of the present invention to provide a compound which is colorless or pale-colored and excellent in environmental safety and has a high safety as a compound and which is useful as a charge-control agent for an electrophotographic toner, and further to provide an electrophotographic toner which contains a compound excellent in the dispersibility in a binder resin, as a charge-control agent and which is excellent in the tribocharge property and capable of constantly presenting an image of high image quality.
DISCLOSURE OF THE INVENTION
In order to solve these problems, the present inventors have paid an attention to zirconium (Zr) being a tetravelent metal and have synthesized studied various compounds of a tetravalent cation or a bivalent cation being an oxo complex with salicylic acid or a salicylic acid derivative. They have found that compounds obtainable by such combinations are colorless stable compounds which specifically have good dispersibility in a binder resin and which are able to impart a good tribocharge property to an electrophotographic toner and that by using such compounds as charge control agents, it is possible to obtain an excellent electrophotographic toner which is capable of supplementing the drawbacks of conventional charge-control agents. The present invention has been accomplished on the basis of these discoveries.
Namely, the present invention provides a zirconium compound which is obtained from an aromatic hydroxycarboxylic acid or its salt and a compound containing zirconium, further an electrophotographic toner which contains such a zirconium compound as a charge-control agent, and further specifically a zirconium compound which is represented by the following Formula (1):
wherein R
1
is quaternary carbon, methine or methylene, and may contain a hetero atom of N, S, O or P, Y represents a cyclic structure linked by saturated bond(s) or unsaturated bond(s), each of R
2
and R
3
which are independent of each other, is an alkyl group, an alkenyl group, an alkoxy group, an aryl, aryloxy, aralkyl or aralkyloxy group which may have a substituent, a halogen group, hydrogen, a hydroxyl group, an amino group which may have a substituent, a carboxyl group, a carbonyl group, a nitro group, a nitroso group, a sulfonyl group or a cyano group, R
4
is hydrogen or an alkyl group, 1 is 0 or an integer of from 3 to 12, m is an integer of from 1 to 20, n is 0 or an integer of from 1 to 20, o is 0 or an integer of from 1 to 4, p is 0 or an integer of from 1 to 4, q is 0 or an integer of from 1 to 3, r is an integer of from 1 to 20, and s is an integer of from 1 to 20. And, the carbon number for the alkyl group, the alkenyl group and the alkoxy group is from 1 to 9.
Further, the present invention provides an electrophotographic toner containing the zirconium compound represented by the above Formula (1) as a charge-control agent, and an electrophotographic toner which contains a charge-control agent being a zirconium compound represented by the above Formula (1) within a range of from 0.01 to 10 parts by weight per 100 parts by weight of a resin. Further, a representative of the zirconium compound represented by the above Formula (1) is a zirconium compound of 3,5-di-t-butylsalicylic acid being a salicylic acid derivative, and the present invention provides an electrophotographic toner using such a compound as a charge control agents and further an electrophotographic toner wherein the average particle size of such a charge-control agent is within a range of from 0.01 &mgr;m to 10.0 &mgr;m.
Now, the present invention will be described in detail.
The zirconium compound of the present invention represented by the Formula (1) is a novel compound. The alkyl group, the alkenyl group and the alkoxy group in the Formula (1) is an alkyl group, an alkenyl group and an alkoxy group having a carbon number of from about 1 to about 9. The general formula of the zirconium compound of the present invention is supported by proton NMR charts of
FIGS. 2
,
5
,
6
and
7
, IR chart (Nujol method) of FIG.
3
and Raman Spectrum of FIG.
4
.
The electrophotographic toner of the present invention basically comprises a binder resin, a coloring agent (pigment, dye or magnetic material) and a charge control agent comprising a compound of the Formula (1). Examples of a method for preparing the above electrophotographic toner include a method which comprises placing the above mixture in a heat-mixing apparatus to melt a binder resin, kneading, cooling, roughly pulverizing, finely pulverizing and classifying, a method which comprises dissolving the above mixture in a solvent, atomizing to prepare fine particles, drying and classifying, and a method which comprises polymerizing by dispersing a coloring agent and a compound of the Formula (1) in suspended monomer particles.
Examples of a binder resin include polystyrene, styrene-acryl type copolymer, styrene-methacrylate copolymer, styrene
Murakami Rie
Muraoka Taito
Sawano Masataka
Yamaga Hiroyoshi
Yamaguti Katuya
Hodogaya Chemical Co. Ltd.
Martin Roland
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