Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2001-03-15
2002-04-23
Rodee, Christopher (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S078000
Reexamination Certificate
active
06376142
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotosensitive material containing a maleimide derivative having an excellent electric charge transferability, which is used in image forming apparatuses such as electrostatic copying machine, facsimile and laser beam printer.
In the image forming apparatuses, a so-called organic photosensitive material has widely been used, which comprises an electric charge generating material generating an electric charge under light radiation, an electric charge transferring material transferring thus generated electric charge and a binder resin constituting a layer in which the above substances are dispersed.
The organic photosensitive material is divided into tow main classes of a single-layer type photosensitive material wherein an electric charge generating material and an electric charge transferring material are dispersed in the same photosensitive layer and a multi-layer type photosensitive material having a laminated structure of an electric charge generating layer containing an electric charge generating material and an electric charge transferring layer containing an electric charge transferring material. Further, in the multi-layer type photosensitive material, the electric charge transferring layer having a film thickness larger than that of the charge generating layer is deposited at the outermost layer of the photosensitive material in view of the mechanical strength.
The electric charge transferring material used in these photosensitive materials includes a hole transferability type one and an electron transferability type one, and among the electric charge transferring materials known until now almost all of electric charge transferring materials having high carrier mobility so as to provide practically useful sensitivity with the photosensitive material have hole transferability. Therefore, in the organic photosensitive material which is now put into practical use, the multi-layer type photosensitive material comprises the electric charge transferring layer at the outermost layer becomes a negatively charging type one inevitably.
However, this negatively charging type organic photosensitive material must be charged by negative corona charge accompanied with the generation of a large amount of ozone, thereby to cause problems such as influence on the environment and deterioration of the photosensitive material itself.
To solve the problems described above, it has been studied to use an electron transferring material as the electric charge transferring material.
Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho Hei) No. 1-206349 suggests to use, as the electron transferring material, a compound having a structure of diphenoquinone or benzoquinone.
However, a compound having diphenoquinone structure or benzoquinone structure is poor in matching with the electric charge generating material and insufficient in injection of electrons into the electron transferring material from the electric charge generating material. Since such an electron transferring material has low compatibility with a binder resin and is not uniformly dispersed in a photosensitive layer, the hopping distance of electrons becomes longer and electrons are less likely to move at low electric field.
Accordingly, as is apparent from electrical characteristics test described in Examples described hereinafter, the above-described conventional photosensitive material containing an electron transferring material had problems such as high residual potential and poor sensitivity.
The single-layer photosensitive material has advantages that one photosensitive material can be used in both of positively and negatively charging type apparatuses by using electron and hole transferring materials in combination. However, there arise problems that, when using diphenomaleimide derivative as the electron transferring material, a charge transfer complex is formed by an interaction between the electron and hole transferring materials, thereby inhibiting transfer of electrons and holes.
SUMMARY OF THE INVENTION
Thus, an object of the present invention is to solve the technical problems described above and to provide an electrophotosensitive material whose sensitivity has been improved as compared with a conventional one.
While studying intensively to solve the problems described above, the present inventors have found a new fact that: a maleimide derivative represented by the general formula (1)[hereinafter referred to as “maleimide derivative (1)”]:
wherein R represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, has higher electron transferability as compared with a conventional electron transferring material such as a compound having diphenoquinone structure or benzoquinone structure and good compatibility with a binder resin. Said maleimide derivatives (1) are known compounds described in J. Org. Chem. Vol. 63, No.8, 1998 2646-2655.
Thus, the present invention includes the following inventions.
1) An electrophotosensitive material comprising a conductive substrate and a photosensitive layer formed on the conductive substrate, the photosensitive layer containing a maleimide derivative represented by the general formula (1).
2) The electrophotosensitive material according to the above item 1), wherein said photosensitive layer contains an electron acceptor.
3) The electrophotosensitive material according to the above item 1), wherein said photosensitive layer is a single-layer type one contains at least a binder resin, an electric charge generating material and a hole transferring material, and 5 to 100 parts by weight of said maleimide derivative represented by the general formula (1) based on 100 parts by weight of the binder resin.
4) The electrophotosensitive material according to the above item 1), wherein said photosensitive layer comprises at least an electric charge generating layer and an electric charge transferring layer which contains at least a binder resin and 10 to 500 parts by weight of said maleimide derivative represented by the general formula (1) based on 100 parts by weight of the binder resin.
Said maleimide derivative (1) has excellent electron acceptability and further good compatibility with a binder resin, thereby making it possible to uniformly disperse in the binder resin. Furthermore, maleimide derivative (1) is superior in matching with the electric charge generating material and injection of electrons from the electric charge generating material is smoothly conducted. Accordingly, maleimide derivatives (1) exhibit excellent electric charge transferability even at low electric field and are suited for use as the electron transferring material in the electrophotosensitive material.
Moreover, since maleimide derivative (1) does not form a charge transfer complex with the hole transferring material, they are used particularly preferably in the single-layer type photosensitive layer using the electron transferring material in combination with the hole transferring material.
The electrophotosensitive material of the present invention has high sensitivity because of containing one or more of said maleimide derivatives as electron transferring material.
The electrophotosensitive material of the present invention is characterized in that the photosensitive layer is formed on the conductive substrate and said photosensitive layer contains one or more of maleimide derivatives represented by the general formula (1).
Since such electrophotosensitive material contains maleimide derivative (1) which has excellent properties as described above in the photosensitive layer, the residual potential is lower and the sensitivity is higher as compared with those of the electrophotosensitive material containing conventional electron transferring material.
Thus, the photosensitive layer containing maleimide derivative (1) is superior in electron transferability at low electric field and less likely to cause recombination ratio of electrons and holes in the photosensitive, whereby apparent electric c
Hamasaki Kazunari
Sugai Fumio
Kyocera Mita Corporation
Rodee Christopher
Smith , Gambrell & Russell, LLP
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