Titanylphthalocyanine crystal and method of producing the titanylphthalocyanine crystal, and electrophotographic photoreceptor, method, apparatus and process cartridge using the titanylphthalocyanine crystal

Abstract

A titanylphthalocyanine crystal having an X-ray diffraction spectrum having plural diffraction peaks and a primary particle diameter not greater than 0.2 μm, wherein a maximum diffraction peak is observed at a Bragg (2 θ) angle of 27.2±0.2°; main peaks are observed at 9.4°, 9.6° and 24.0°; and a minimum diffraction peak is observed at 7.3°; and preferably no diffraction peak is observed at an angle greater than 7.3° and less than 9.4° when a specific X-ray of CuKα having a wavelength of 1.542 Å irradiates the titanylphthalocyanine crystal.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a titanylphthalocyanine crystal and a method of producing the titanylphthalocyanine crystal, and to an electrophotographic photoreceptor, method, apparatus and process cartridge using the titanylphthalocyanine crystal.[0003]2. Discussion of the Background[0004]An organic pigment has been used as a filler for a coating material since comparatively a long ago. In particular, the organic pigment has the advantage over an inorganic pigment in its abundance of color variation. Further, recently as an application of the organic pigment, a variety of materials have been produced because it was spotlighted as a material for an organic photoelectric transfer device.[0005]Almost all methods of forming a film including the organic pigment are wet coating methods. It is not exaggerated to say quality of a film coated by the wet coating methods depends on quality of a dispersion liquid including the ...

AI Technical Summary

Benefits of technology

The present invention provides a titanylphthalocyanine crystal with small particle size and high stability. The crystal can be used to prepare a stable dispersion liquid and an electrophotographic photoreceptor with high sensitivity and low abnormal image formation. The crystal also allows for high-speed printing and reduces abnormal images when used in a stable electrophotographic method and apparatus. The crystal has a unique X-ray diffraction spectrum with specific peaks and no diffraction peak at a certain angle.

Problems solved by technology

However, background of a produced copy corresponds to a non-irradiated part (high potential part) of the photoreceptor, and when a photosensitive layer (particularly a charge generation layer) has a coating defect, a background portion (white background portion) of the photoreceptor which should have maintained potential decreases potential, resulting in occasional occurrence of point defects such as background fouling and black spots.

These defects are occasionally mistaken for points in drawings and periods and commas in English drafts, and it can be said that the defects are fatal defects as images.

However, it is quite difficult to reduce the particle size more than the primary particle size, and a limit of the particle size in the dispersion liquid basically depends on the primary particle size of the pigment.

Methods of pulverizing the primary particle with an enormous energy are included in the methods, but these break the crystal and have problems such as deterioration of dispersion efficiency and transform of the crystal form as mentioned later.

Because this crystal has considerably a lower photo carrier generation efficiency than the above-mentioned crystal, when even a partly transformed crystal is used for a charge generation material for a photoreceptor, problems such as deterioration of photosensitivity and increase of residual potential in repeated use occur.

When such a dispersion liquid including a pigment having a large average particle diameter is used, surface area of the total charge generation materials becomes small, and it becomes difficult for the material to give and receive a charge to and from charge transport material, resulting in problems such as deterioration of photosensitivity and increase of residual potential in repeated use of the resultant photoreceptor occur.

When the coarse particles remain, the resultant image has problems such as background fouling and black spots occur in the negative and positive development.

As just described, in the dispersion of the titanylphthalocyanine pigment particles, stability of the crystal form and miniatulization of the particles have a trade-off relation and means to easily solve this problem have not been available.

However, approaches in terms of pigment synthesis have hardly been seen so far.

However, considering the dispersion liquid is used for a coating liquid, a crystal conversion solvent is not limited to a suitable coating solvent and the method has a drawback of having a restriction in coating.

In addition, because the dispersion liquid cannot be stored as a pigment powder, the method also has a drawback of having a restriction in storage.

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