Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1998-05-15
2001-03-06
Dote, Janis L. (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S056000, C430S057100, C430S066000, C430S067000
Reexamination Certificate
active
06197463
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to electrophotographic photosensitive bodies or drums used in copying machines, printers, etc. which employ an electrophotographic process. In particular, the present invention relates to electrophotographic photosensitive bodies or drums which can withstand long periods of repeated use without undergoing substantial wear, exhibit excellent cleaning and scratch resistance, and exhibit a high printing sensitivity.
Discussion of the Background
According to the electrophotographic image-forming process by Carlson, the surface of a photosensitive body is uniformly electrically charged, is exposed to light in accordance with information on an image to be formed, the electric charge is dissipated, and an electrostatic latent image is formed on the surface of the photosensitive body. The electrostatic latent image is developed and made visible by a toner, and the toner image is transferred from the photosensitive body onto transfer paper, etc., and fixed.
Next, the photosensitive body has its surface renewed by the removal of any residual toner and electric charge therefrom, and is repeatedly used. Therefore, the electrophotographic photosensitive body is not only required to have good chargeability and sensitivity, and photosensitive properties such as low attenuation, but is also required, for repeated, use to have good mechanical properties such as printing, wear and scratch resistance, and good resistance to destructive substances produced at the time of corona discharge, such as ozone, and ultraviolet radiation at the time of exposure.
Inorganic photoconductive materials, such as selenium, a selenium-tellurium alloy, arsenic selenide, cadmium sulfide and zinc oxide, have hitherto been widely used for the electrophotographic photosensitive body. These inorganic photoconductive materials are, however, harmful to the human body, and have had a problem of disposal, and the associated high costs thereof have been another problem.
For these reasons, a great deal of research has been performed on the use of organic photoconductive materials in photosensitive layers, because such organic photoconductive materials are less likely to cause environmental pollution and are easy to manufacture; and the practical use thereof has been promoted. Of main interest has been a laminated photosensitive body composed of a charge generating layer (CGL) and a charge transport layer (CTL) having the function of absorbing light and generating an electric charge as well as transporting the generated charge. These photosensitive bodies are widely used in the fields of copying machines, laser printers, etc.
Recent requirements of electrophotographic copying machines and printers have included the ability to create a large number of images rapidly, with continued ease of maintenance. In order to satisfy these requirements, it is essential to use a photosensitive body having a high printing sensitivity. However, electrophotographic photosensitive bodies which contain organic photoconductive materials have the drawback of poor mechanical properties and are more easily worn and damaged if used repeatedly, as compared with electrophotographic photosensitive bodies which contain inorganic photoconductive materials.
Decreasing the amount of the charge transport substance brings about a reduction of wear but also lowers the photosensitivity properties. The use of a binder having a higher molecular weight for the charge transport layer brings about a reduction of wear, but as the coating solution has a higher viscosity, defects such as sagging and unevenness are likely to arise from its application. There have been recent developments regarding dispersing inorganic filler, or lubricant particles in the charge transport layer, but the dispersed particles have the drawback of scattering incident light and thereby causing a serious decrease in sensitivity. Settling in the coating solution if it is left to stand, has also been shown, and there has not yet been available any electrophotographic photosensitive body having improved mechanical properties without the sacrifice of other properties such as photosensitizability and ease and quality of application and manufacture.
Thus, there remains a need for improved electrophotographic photosensitive bodies which exhibit extended lifetimes under operating conditions, without sacrificing sensitivity.
SUMMARY OF THE INVENTION
Accordingly, it is one object of the present invention to provide novel electrophotographic photosensitive bodies.
It is another object of the present invention to provide novel electrophotographic photosensitive bodies which exhibit an improved lifetime.
It is another object of the present invention to provide novel electrophotographic photosensitive bodies which exhibit reduced friction with the surfaces of the charge roller, toner, and wiper blade in a laser printer or photocopier cartridge.
It is another object of the present invention to provide novel electrophotographic photosensitive bodies which afford better image quality as a result of more homogeneous wear.
It is another object of the present invention to provide novel electrophotographic photosensitive bodies which exhibit improved scratch resistance.
It is another object of the present invention to provide novel electrophotographic photosensitive bodies which exhibit high photosensitivity.
It is another object of the present invention to provide novel electrophotographic photosensitive bodies which can withstand a long period of repeated use without undergoing substantial wear, and exhibit excellent cleaning and scratch resistance, while retaining other properties including electrical properties, commercial viability, and ease and quality of application.
These and other objects, which will become better understood during the course of the following detailed description, have been achieved by the inventors' discovery that electrophotographic photosensitive bodies, having a photosensitive layer on a conductive support, which contain a wax having an ester group in the outermost layer, exhibit improved wear and printing resistance without sacrificing their photosensitizability properties, such as chargeability and sensitivity, or ease and quality of application.
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Cais Rudolf E.
Debnath Santanu
Makino Moto
Suzuki Shin'ichi
Dote Janis L.
Mitsubishi Chemical Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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