Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1999-10-20
2001-01-23
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C564S434000
Reexamination Certificate
active
06177220
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a stilbene derivative having excellent electric charge transferring capability and a method of producing the same, and an electrophotosensitive material containing the stilbene derivative, which is used in image forming apparatuses such as electrostatic copying machine, facsimile, laser beam printer and the like.
In the image forming apparatuses, various organic photoconductors having a sensitivity within a wavelength range of a light source used in said apparatuses have been used. These organic photoconductors have widely been used because of easier production than that in the case of a conventional inorganic photoconductor, various selective photosensitive materials (e.g. electric charge transferring material, electric charge generating material, binding resin, etc.) and high design freedom.
Examples of the organic photoconductor include a single-layer type photoconductor wherein an electric charge transferring material and an electric charge generating material are dispersed in the same photosensitive layer, and a multi-layer photoconductor comprising an electric charge generating layer containing an electric charge generating material and an electron transferring layer containing an electron transferring material, which are mutually laminated.
As the electric charge transferring material used in the above organic photoconductor, a stilbene derivative is disclosed in Japanese Patent Kokai Publication Nos. 31773/1975 and 244389/1996.
However, since the stilbene derivative disclosed in the above publications is usually inferior in compatibility with a binding resin and is not uniformly dispersed in the photosensitive layer, electric charges hardly move. Therefore, although the above stilbene derivative itself has high electric charge mobility, when using this stilbene derivative as the electric charge transferring material in the photoconductor, its characteristics can not be sufficiently exhibited. Accordingly, the residual potential of the photoconductor becomes higher and the photosensitivity becomes insufficient.
SUMMARY OF THE INVENTION
Thus, an object of the present invention is to solve the above technical problems and to provide a novel stilbene derivative suited for use an electric charge transferring material of the electrophotosensitive material, and a method of producing the same.
Another object of the present invention is to provide an electrophotosensitive material whose sensitivity is improved compared with the prior art.
The present inventors have intensively studied to attain the above objects and found a new fact that a compound, wherein diphenylamino groups at a molecular end are not symmetric and one phenyl group of the diphenylamino group has no substituent while at least the other phenyl group has a substituent at the 2 (ortho, o-) position, has better compatibility with a binder resin than that of a conventional stilbene derivative and large electric charge mobility, thus completing the present invention.
That is, the stilbene derivative of the present invention is characterized in that it is represented by the general formula (1):
wherein R
1
and R
3
are the same or different and represent an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, or an alkoxy group which may have a substituent, and R
2
and R
4
are the same or different and represent a hydrogen atom, an alkyl group which may have a substituent, or an alkoxy group which may have a substituent.
The stilbene derivative represented by the general formula (1) according to the present invention is a compound wherein one phenyl ring of the diphenylamino group is substituted at the 2 (ortho, o-) position, which is not specifically disclosed in Japanese Patent Kokai Publication Nos. 7-244389 and 50-31773, and has high compatibility with a binding resin and high electric charge mobility in comparison with the compounds disclosed in the above publications.
Accordingly, a high-sensitivity electrophotosensitive material can be obtained by using such a stilbene derivative (1) as an electric charge (hole) transferring material in the electrophotosensitive material.
Furthermore, in order to obtain an electrophotosensitive material having higher sensitivity, it is preferred to use a stilbene derivative, wherein one phenyl group of the diphenylamino group at the molecular end has no substituent while the other phenyl group has a substituent at the 2-/3-positions, 2-/5-positions or 2-/6-positions or has a substituent only at the 2-position (i.e. stilbene derivative wherein the 4 (para, para-) position is a hydrogen atom) among the above stilbene derivative (1).
The present inventors have studied about a method of efficiently producing a formyl compound (2) of triphenylamine described below, as a starting material, in the method of producing the above stilbene derivative (1). As a result, they have found a new fact that, when a triphenylamine derivative (5) having a substituent at the 2-position of the phenyl group is formylated by the Vilsmeier method, the above compound (2), wherein the phenyl group having a substituent among three phenyl groups of the compound (5) is not formylated and only non-substituted phenyl group is formylated, can be efficiently produced, resulting in improvement of the productivity of the stilbene derivative (1). Thus, the present invention has been accomplished.
That is, the method of producing the stilbene derivative (1) of the present invention is characterized by reacting a formylated triphenylamine derivative represented by the general formula (2):
wherein R
1
represent an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, or an alkoxy group which may have a substituent, and R
2
represents a hydrogen atom, an alkyl group which may have a substituent, or an alkoxy group which may have a substituent, with a bisphosphate derivative represented by the general formula (3):
The above formylated triphenylamine derivative (2) used in the production method of the present invention is a compound obtained by reacting an aniline derivative represented by the general formula (4):
wherein R
1
represent an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, or an alkoxy group which may have a substituent, and R
2
represents a hydrogen atom, an alkyl group which may have a substituent, or an alkoxy group which may have a substituent, with iodobenzene to obtain a triphenylamine derivative represented by the general formula (5):
wherein R
1
represent an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, or an alkoxy group which may have a substituent, and R
2
represents a hydrogen atom, an alkyl group which may have a substituent, or an alkoxy group which may have a substituent, and formylating this compound (5) by using the Vilsmeier method.
The reason why only the formyl compound (2) of triphenylamine as the raw material of the stilbene derivative (1) is produced in high yield when the above triphenylamine derivative (5) is formylated by the Vilsmeier method is not apparent. However, regarding the phenyl group having a substituent R
1
at the ortho-position among three phenol groups of the compound (5), an axis of bonding between the nitrogen atom and phenyl group in the compound (5) is distorted by an influence of the substituent R
1
and giving and receiving of electrons from the nitrogen atom become poor and, therefore, nucleophilicity of the phenyl group is lowered in comparison with the other phenyl. As a result, the phenyl group is not formylated at the para-position and the other phenyl group is formylated only at the para-position.
The electrophotosensitive material of the present invention is an electrophotosensitive material comprising a conductive substrate and a photosensitive layer pr
Kawaguchi Hirofumi
Watanabe Yukimasa
Goodrow John
Kyocera Mita Corporation
Smith , Gambrell & Russell, LLP
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