Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1998-12-03
2001-04-17
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...
C430S120400
Reexamination Certificate
active
06218065
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a toner for developing electrostatic images in image forming methods, such as electrophotography and electrostatic recording, or an image forming method of the toner jet recording scheme, and a developing method using the toner.
It is necessary for such a toner to be provided with a positive or negative charge depending on the polarity of an electrostatic image to be developed and the developing mode (normal development mode or reversal development mode).
A toner can be charged by utilizing a triboelectric chargeability of a resin as a toner component, but the toner chargeability in this case is unstable so that the resultant image density cannot be raised quickly at the start of image formation and the resultant images are liable to be foggy. For this reason, it has been frequently practiced to add a charge control agent to the toner to provide the toner with a desired triboelectric chargeability.
The charge control agents known in the art nowadays include: negatively chargeable charge control agents inclusive of metal complex salts of monoazo dyes; metal complex salts of hydroxycarboxylic acids, dicarboxylic acids and aromatic diols; and resins containing an acidic component. On the other hand, known positively chargeable charge control agents include: nigrosine dyes, azine dyes, triphenylmethane dyes and pigments, quaternary ammonium salts, and polymers having a quaternary ammonium salt as a side chain.
However, most of such known charge control agents applicable to color toners have still left functionally unsatisfactory points, such as difficulty in formation of uniform highlight images and a large fluctuation in image density during continuous image formation.
Other points to be further improved may include: a difficulty in obtaining a good balance between image density and fog prevention, a difficulty in obtaining a sufficient image density in a high humidity environment, a poor dispersibility in a resin, and adverse effects on storage stability, fixability and anti-offset property of the resultant toner.
As known charge control agents, metal complexes or metal salts of aromatic carboxylic acids have been proposed in Japanese Laid-Open Patent Application (JP-A) 53-127726, JP-A 57-111541, JP-A 57-124357, JP-A 57-104940, JP-A 61-69073, JP-A 61-73963, JP-A 61-267058, JP-A 62-105156, JP-A 62-145255, JP-A 62-163061, JP-A 63-208865, JP-A 3-276166, JP-A 4-84141, and JP-A 8-160668. Charge control agents proposed in these references are generally excellent in performance of imparting triboelectric chargeability, but few of them are satisfactory in providing a stable developing performance regardless of environmental condition change, continued use and condition of use even when used in a simple developing device structure. Few of them provide a stable developing performance in a long term of continuous image formation when used in a high-speed image forming machine. Further, many of them are affected by other toner materials, thus posing a constraint on the selection of such other toner materials.
SUMMARY OF THE INVENTION
A generic object of the present invention is to provide a toner having a negative triboelectric chargeability and having solved the above-mentioned problems.
A more specific object of the present invention is to provide a toner having a negative triboelectric chargeability and a developing method using the toner capable of stably providing high image qualities even when used in a low humidity environment or in a high humidity environment and not causing image defects with lapse of time.
Another object of the present invention is provide a toner having a negative triboelectric chargeability which is less liable to result in deteriorated toner even when used in a cartridge-type developing device of either a replenishment-type or a use-up type and exhibits excellent developing performance, and a developing method using such a toner.
Still another object of the present invention is to provide a toner having a negative triboelectric chargeability and a developing method for developing electrostatic images capable of continually providing developed images faithful to electrostatic images even in a long term of continuous image formation.
According to the present invention, there is provided a toner having a negative triboelectric chargeability, comprising at least a binder resin, a colorant and an organic metal compound,
wherein the organic metal compound is an organic zirconium compound comprising a coordination or/and a bonding of zirconium and an aromatic compound as a ligand or/and an acid source selected from the group consisting of aromatic diols, aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids, and aromatic polycarboxylic acids.
According to another aspect of the present invention, there is provided a method for developing an electrostatic image, comprising the steps of:
forming a layer of a mono-component developer comprising the above-mentioned toner having a negative triboelectric charge in a regulated thickness on a developer-carrying member by a developer thickness-regulation means, and
developing an electrostatic image on an electrostatic image-bearing member disposed opposite to the developer-carrying member with the mono-component developer carried on the developer-carrying member.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
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Kanbayashi Makoto
Ohtake Takeshi
Tanikawa Hirohide
Unno Makoto
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Goodrow John
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