Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1999-06-11
2001-01-30
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C399S159000, C430S058850
Reexamination Certificate
active
06180303
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, process cartridge and electrophotographic apparatus which use the same photosensitive member, and process for producing the same photosensitive member, more particularly to the photosensitive member having a photosensitive layer containing a specific compound, process cartridge and electrophotographic apparatus which use the same photosensitive member, and process for producing the same photosensitive member.
2. Related Background Art
Inorganic materials, e.g., selenium, cadmium sulfide and zinc oxide, are known as the photoconductive materials for employing electrophotographic photosensitive members. On the other hand, organic materials, e.g., polyvinyl carbazole, phthalocyanine and azo-based pigments, have been widely used because of their advantages of, e.g., high productivity and being less polluting environments, in spite of their inferiority to inorganic materials in, e.g., photoconductive characteristics and durability.
These electrophotographic photosensitive members are frequently of a function-separated type, which is laminated with the separate charge-generating and charge-transporting layers, in order to simultaneously satisfy the required electric and mechanical properties. It is needless to say that an electrophotographic photosensitive member is required to have sufficient sensitivity, electric properties and optical properties for the electrophotographic process to which it is applied. Moreover, it is required to be sufficiently resistant to various external electric and mechanical forces generated during the various steps, e.g., electrification, exposure, toner development, transferring images to paper and cleaning, which will be applied to the surface of the photosensitive member for repeated use.
Concretely, it is required to be resistant to surface wear and scratching caused by an object coming into contact with the surface, to surface deterioration caused by electrification, e.g., decreased transfer efficiency and slip characteristics, and to electrical deterioration, e.g., decreased sensitivity and potential.
The surface layer for electrophotographic photosensitive members of organic photoconductive materials is generally a thin layer of resin, and its functions are largely determined by properties of the resin. Recently, acrylic resin, polycarbonate resin and the like are used as the ones which can satisfy the above requirements to some extent. However, none of these resins can simultaneously satisfy all of the above requirements. In particular, their insufficient hardness is one of the largest problems to be solved for further improving durability of the photosensitive members. The surface layer, even when the above resin is used therefor, will be worn or damaged when used repeatedly.
Recently, low-molecular-weight compounds, e.g., charge-transporting compounds, are frequently used in large quantities to satisfy the requirements for higher sensitivity. However, strength of films of such compounds will be greatly decreased, because of their plasticizing functions, aggravating wear and/or scratching-caused damages of the surface layer when it is repeatedly used. Another type of possible problems resulting from use of such compounds is tendency of these compounds to separation while the electrophotographic photosensitive member is stored.
One of the means proposed to solve these problems is use of a settable resin for the charge-transporting layer, as disclosed by, e.g., Japanese Patent Application Laid-Open No. 2-127652. Such a resin will greatly improve resistance of the charge-transporting layer to cracking and damages when used repeatedly by promoting hardening and cross-linking of the layer.
It should be noted, however, that a low-molecular-weight compound inherently works as a plasticizer in the binder resin, even when a settable resin is used, and will not drastically improve the above-mentioned problems resulting from separation. In a charge-transporting layer composed of an organic charge-transporting material and binder resin, its charge-transporting capacity largely depends on properties of the resin, by which is meant that it is difficult to sufficiently satisfy the requirements of high hardness and electrophotographic characteristics simultaneously, because, for example, a settable resin of sufficiently high hardness tends to decrease the charge-transporting capacity, to possibly increase residual potential when the member is repeatedly used.
For example, Japanese Patent Application Laid-Open Nos. 5-216249 and 7-72640 disclose an electrophotographic photosensitive member with a charge-transporting layer containing a monomer with carbon-carbon double bond, where the double bond works as the charge-transporting agent, when excited by heat or light energy. However, the charge-transporting agent is merely attached to the main skeleton of the polymer like a pendant, difficult to sufficiently improve mechanical strength because of insufficient removal of the above-mentioned plasticizing function. Increasing concentration of the charge-transporting material in an attempt to improve the charge-transporting capacity decreases cross-linking density, leading to insufficient mechanical strength. This may also cause adverse effects of necessary additives for polymerization, e.g., initiator, on the electrophotographic characteristics.
As another means to solve the above problems, Japanese Patent Application Laid-Open No. 8-248649 discloses an electrophotographic photosensitive member whose charge-transporting layer is composed of a thermoplastic resin with a group having charge-transporting capacity in the main skeleton. This charge-transporting layer is more resistant to the separation and mechanically stronger than the conventional, molecule-dispersion type layer. However, improvement of strength is limited, when a thermoplastic resin is used, and handling and productivity-related characteristics of the member, including solubility of the resin, are not sufficient.
Therefore, there are demands for the photosensitive members which can simultaneously satisfy the requirements for mechanical strength and charge-transporting capacity to a higher extent.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electrophotographic photosensitive member of higher resistance to wear and scratching, and also of higher resistance to the separation by solving the problems involved in the conventional electrophotographic photosensitive member to increase film strength.
It is another object of the present invention to provide an electrophotographic photosensitive member which shows greatly reduced changes or deterioration in photosensitive characteristics, e.g., increased residual potential, when it is repeatedly used, and secures required functions stably even when it is repeatedly used.
It is still another object of the present invention to provide a process cartridge and electrophotographic apparatus which use the above electrophotographic photosensitive member.
It is yet another object of the present invention to provide a process for producing the above electrophotographic photosensitive member.
More concretely, the present invention provides an electrophotographic photosensitive member, comprising a support and photosensitive layer thereon,
wherein said photosensitive layer contains at least one of a hole-transporting compound with two or more chain-polymerizing functional groups in the same molecule and the compound hardened by polymerizing or cross-linking the above hole-transporting compound.
The present invention also provides a process cartridge comprising an electrophotographic photosensitive member and at least one of the means selected from the group consisting of those for electrification, development and cleaning, which are monolithically supported to form an assembly freely attachable to or detachable from an electrophotographic apparatus body, said electrophotographic photosensitive member compris
Kikuchi Toshihiro
Maruyama Akio
Uematsu Hiroki
Canon Kabushiki Kaisha
Fitzpatrick,Cella Harper & Scinto
Goodrow John
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