Compositions – Electrically conductive or emissive compositions – Light sensitive
Reexamination Certificate
2000-04-26
2002-11-26
Kopec, Mark (Department: 1751)
Compositions
Electrically conductive or emissive compositions
Light sensitive
C430S076000, C430S078000, C540S139000
Reexamination Certificate
active
06485658
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a phthalocyanine composition having diffraction peaks at 7.0°, 9.0°, 14.1°, 18.0°, 23.7° and 27.3° of Bragg angles (2&thgr;±0.2°) in an X-ray diffraction spectrum with a 1.541 Å X-ray of Cu K&agr;, a phthalocyanine composition having diffraction peaks at 7.0°, 9.3°, 10.5°, 13.1°, 20.6°, 23.7°, 26.2° and 27.2° of Bragg angles, and an oxytitanium phthalocyanine having diffraction peaks at 7.5°, 10.2°, 16.3°, 22.5°, 24.2°, 25.4°, 27.2° and 28.7° of Bragg angles, wherein the intensity of peak at 7.5° of a Bragg angle is the strongest among the above peaks. It also relates to a process for producing the same and to an electrophotographic photoreceptor using the same.
2. Prior Art
In recent years, the utilization of an electrophotography has not been limited to the field of a copying machine, but has spread in fields of a conventional photography, for example, the field of a printing plate material, a slide film or a microfilm. In addition, the application thereof has been also studied in the field of a high-speed printer using a laser, LED or CRT as a light source. Further, the application thereof has been lately directed to the use of a photoconductive material other than an electrophotographic photoreceptor, for example, the use of an electrostatic recording element, a sensor material or an EL element. Therefore, demands for a photoconductive material and an electrophotographic photoreceptor using the same have been increasing and become high level.
As the conventional photoreceptor of an electrophotography, an inorganic photoconductive substance, such as selenium, cadmium sulfide, zinc oxide or silicon, has been known, widely studied and already used practically. An inorganic substance has various problems although it has a number of advantages. For example, selenium has problems in that it is difficult to optimize production conditions thereof and it is easily crystallized due to heat and mechanical impact. Cadmium sulfide and zinc oxide have poor resistance to humidity and durability. It is pointed out that silicon has a poor electrostatic chargeability and is difficult to be produced. Further, selenium and cadmium sulfide also have problems on toxicity.
On the other hand, an organic photoconductive substance is advantageous in that it has an excellent film-formability and flexibility as well as in that it is lightweight and has an excellent transparency. Further, it also has advantages in that a photoreceptor to be used in a wide range of wavelength is easily designed therefrom by using an appropriate sensitization method. Therefore, attention is now drawn to the practical use of an organic photoconductive substance.
By the way, the photoreceptor used in the electrophotography is necessary to meet, as general basic properties, the following requirements: (1) that the electrostatic chargeability for the corona discharge in darkness be high; (2) that the leakage in darkness (dark decay) of the obtained electric charge be small; (3) that the dissipation (light decay) of the electric charge by light irradiation be rapid; and (4) that the residual electric charge after light irradiation be small.
A number of studies have been made on photoconductive polymers as organic photoconductive substances, including polyvinyl carobazole as of today. However, they do not necessarily have satisfactory film-formability, flexibility and adhesion property. Further, they do not have the above-mentioned basic properties required for a photoreceptor satisfactorily.
On the other hand, an organic photoconductive compound having a low molecular weight is advantageous in that a photoreceptor having an excellent film-formability, an excellent adhesion property and a high mechanical strength, such as flexibility, can be obtained by appropriately selecting a binder used in the photoreceptor formation. However, it is difficult to find an appropriate compound suitable to maintain high sensitivity.
For improving such properties, an organic photoreceptor having higher sensitivity has been developed in which different substances individually have a charge generation function and a charge transportation function. The characteristic feature of such a photoreceptor, which is called “function separation type”, resides in that it is possible to select materials suitable for the respective functions from wide varieties. Therefor, a photoreceptor having desired performance can be easily prepared, which have led to a number of researches on the photoreceptor.
As substances responsible for the charge generation function, various substances, such as a phthalocyanine pigment, a squarilium dye, an azo-pigment and a perylene pigment, have been studied. Among them, an azo-pigment is advantageous not only in that it is possible to prepare those having various molecular structures, but also in that a high charge generation efficiency is expected. Therefore, various azo-pigments has been widely researched and put into practical use. However, a relationship between the molecular structure and the charge generation efficiency in the azo-pigment has not yet been elucidated. Currently, although an enormous number of researches have been made on the synthesis of the azo-pigment having an optimum molecular structure, the satisfactory photoreceptor meeting the requirements of the above-mentioned basic properties and high durability has not yet been obtained.
Further, in recent years, according to the progress of information technology, laser beam printers using a laser as a light source instead of the conventional white light have been rapidly and widely expanded since they have advantages of high speed, high image quality and non-impact. In accordance with the expansion, it is desired to develop materials for such printers, which meet the demands for high performance of the printers. Among lasers, especially in a semiconductor laser, the use thereof in a compact disk or an optical disk is recently increased, and thus, the technical advance has been remarkably progressed. Therefore, the semiconductor laser has been vigorously used also in a printer field as a light source material being compact and high reliability. In such a case, the wave-length of the light source is about 780 to 830 nm, and therefore, it is strongly desired to develop a photoreceptor having high sensitivity in a near infrared range. Especially, a photoreceptor using a phthalocyanine with an optical absorption in a near infrared range is energetically developed.
It has been known that phthalocyanines have the different absorption spectrum and photoconductivity depending on the type of the central metal, and, in addition, among phthalocyanines having the same central metal, the properties of such phthalocyanines are different from each other according to the crystal structure thereof. Therefor, a phthalocyanine having a specific crystal structure is selected as an electrophotographic photoreceptor.
Taking as an example an oxytitanium phthalocyanine (hereinafter, referred to as “TiOPc”), an &agr;-TiOPc, which has main diffraction peaks at 7.6°, 10.2°, 22.3°, 25.3° and 28.6° of Bragg angles (2&thgr;±0.2°) in an X-ray diffraction spectrum, has been described in Japanese Unexamined Patent Publication No. 217050/1986. A &bgr;-TiOPc, which has main diffraction peaks at 9.3°, 10.6°, 13.2°, 15.1°, 15.7°, 16.1°, 20.8°, 23.3°, 26.3° and 27.1° of Bragg angles, has also been described in Japanese Unexamined Patent Publication No. 67094/1987. However, both of them do not satisfy the required high properties satisfactorily.
Among the TiOPc's having a peak at 27.2° of a Bragg angle, a II-TiOPc described in the above publication has a poor electrostatic chargeability and a low sensitivity. In Japanese Unexamined Patent Publication No. 17066/1989, a Y-TiOPc having a relatively high sensitivity with main diffraction peaks at 9.5°, 9.7°, 11.7°, 15.0°, 23.5°, 24.1° and 27.3° of Bragg angles is described. However, this TiOPc has problems in that the crystal structure thereof
Horiuchi Tamotsu
Nagamura Hideki
Okaji Makoto
Kopec Mark
Manelli Denison & Selter PLLC
Mitsubishi Paper Mills Limited
White, Jr. Paul E.
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