Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2001-05-21
2004-06-15
Rodee, Christopher (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S070000, C430S072000, C430S073000, C430S076000, C430S083000, C430S056000
Reexamination Certificate
active
06749979
ABSTRACT:
BACKGROUND TO THE INVENTION
The present invention relates to a photosensitive body for electrophotography (henceforth may also be referred to as simply “photosensitive body”) and to an electrophotography device equipped with this electrophotography photosensitive body.
In recent years, in the field of electrophotography photosensitive bodies, many of what are called organic electrophotography photosensitive bodies, which use organic photoconductive materials, have been proposed and implemented. These are non-polluting and have low cost, and because there is a large degree of freedom in the choice of materials, they can be designed to have varied photosensitive body properties.
The photosensitive layer of an organic electrophotography photosensitive body comprises mainly a layer in which organic photoconductive materials are dispersed in a resin. Many laminated constructions and single layer constructions have been proposed. In a laminated construction, a layer in which a charge generating substance is dispersed in a resin and a layer in which a charge transport substance is dispersed in a resin are layered. A single-layer construction comprises a single layer in which a charge generating substance and a charge transport substance are dispersed in a resin.
Among these, a photosensitive body using a function-separated model for the construction of the photosensitive layer has been widely implemented because of its excellent photosensitive body properties and durability. A function-separated model has a charge transport layer laminated on top of a charge generating layer. In this function-separated laminated photosensitive body, a hole transport material is mainly used for the charge transport layer. As a result, they are generally used with a negative charging process. Negative corona charging used in the negative charging process is unstable compared to positive corona charging, and the amount of generated ozone is also large. As a result, there are problems of having a negative impact on the photosensitive body and a negative impact on the usage environment.
For solving these problems, an organic electrophotography photosensitive body that can use a positive charging is effective. As a result, currently there is a demand for a positive charge photosensitive body with high sensitivity. For this positive charge photosensitive body, there have been many proposals for a function-separated photosensitive body or a single-layer photosensitive body. The function-separated photosensitive body has a photosensitive layer in which a charge generating layer is layered on top of a hole transport layer or a photosensitive layer in which an electron transport layer is layered on top of a charge generating layer. A single layer photosensitive body has a photosensitive layer containing a charge generating substance and a charge transporting substance in a single layer.
In recent years, in Japanese Laid Open Patent Publication Number 1-206349, Japanese Laid Open Patent Publication number 4-360148, Denshishashin Gakkaishi (Electrophotography Society Journal) Vol. 30, p. 266~273 (1991), Japanese Laid-Open Patent Publication Number 3-290666, Japanese Laid Open Patent Publication Number 5-92936, Pan-Pacific Imaging Conference/Japan Hardcopy '98 Jul. 15-17, 1998 J A HALL, Tokyo, Japan, preliminary draft collection p. 207-210, Japanese Laid-Open Patent Publication Number 9-151157, Japan Hardcopy '97 Collection of papers Jul. 9, 10, 11, 1997 J A Hall (Tokyo-Ohtemachi) p.21-24, Japanese Laid Open Patent Publication Number 5-279582, Japanese Laid Open Patent Publication Number 7-179775, Japan Hardcopy '92 collection of papers Jul. 6, 7, 8, 1992 J A Hall (Tokyo-Ohtemachi) p. 173-176, Japanese Laid Open Patent Publication Number 10-73937, and the like, many electron transport substances and electrophotography photosensitive bodies using these electron transport substances have been proposed and described, and there has been much interest in them. Furthermore, as described in Japanese Laid Open Patent Publication Number 5-150481, Japanese Laid Open Patent Publication Number 6-130688, Japanese Laid-Open patent Publication Number 9-281728, Japanese Laid-Open patent Publication Number 9-281729, Japanese Laid-Open Patent Publication number 10-239874, a photosensitive body using a combination of a hole transport substance and an electron transport substance in a single layer photosensitive layer has been attracting attention as having high sensitivity, and this has been implemented by some. However, with the positive charge photosensitive body, the electrical properties of sensitivity and the like are still deficient compared to the negative charge function-separated photosensitive body.
Furthermore, for the charge generating substance, various studies have been conducted from the prior art. In general, for the charge generating substance, various pigments are used according to the sensitivity range of the photosensitive body. In particular, for photosensitive bodies responding to light of semiconductor laser light or infrared LED light and the like which have wavelengths in the infrared or near-infrared region, phthalocyanine pigments such as metal free phthalocyanine, titanyl phthalocyanine, and the like are widely used. There are various crystal types for these phthalocyanine pigments. It is known that the wavelength region and quantum efficiency of the absorbed light are different depending on the different crystal types, and for the electrophotography photosensitive body using these pigments as a charge generating substance, the different crystal types also affect the sensitivity and electrical properties such as the residual voltage, dark attenuation, as well as the stability of the photosensitive body over repeated use, and the like. Various studies have been conducted on the relationship between the crystal type and the photosensitive body electrical properties.
For example, in Japanese Laid Open Patent Publication Number 61-217050, there is proposed a single layer photosensitive body having a photosensitive layer comprising an alpha titanyl phthalocyanine dispersed in a binding resin. In an X ray diffraction spectrum having CuK alpha as the radiation source, this alpha titanyl phthalocyanine shows strong diffraction peaks at Bragg angles (2&thgr;±0.2 degrees) of 7.5, 12.3, 16.3, 25.3, and 28.7 degrees.
In addition in Japanese Laid Open Patent Publication Number 9-73182, there is proposed an electrophotography photosensitive body that is a single layer photosensitive body containing a charge transport substance and a charge generating substance in a photosensitive layer. The charge generating substance comprises, in an x-ray diffraction spectrum as described above, a mixture of a metal free phthalocyanine showing diffraction peaks at Bragg angles (2&thgr;±0.2 degrees) of 7.5, 9.1, 16.7, 17.4, 22.3, and 28.6 degrees and a titanyl phthalocyanine showing diffraction peaks at Bragg angles (2&thgr;±0.2 degrees) of 9.5, 14.2, 24.0, and 27.2 degrees. The content ratio of the titanyl phthalocyanine to the total weight of the charge generating substance is greater than 50 weight %.
However, even with these numerous single layer electrophotography photosensitive bodies that have been proposed, the electrical properties of sensitivity and the like are not adequate compared to the function-separated photosensitive body of negative charge of the prior art. Photosensitive bodies that can use positive charge and that have good electrical properties have still not been satisfactorily achieved.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electrophotography photosensitive body which solves the above problems.
It is a further object of the present invention to provide an electrophotography photosensitive body and an electrophotography device equipped with the same, in which for an electrophotography photosensitive body having a single layer photosensitive layer, the electrical properties with positive charging are excellent and there is e
Ohkura Kenichi
Takeuchi Masaru
Darby & Darby
Rodee Christopher
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