Abstract: Provided is an excellent phthalocyanine crystal having high sensitivity and little fluctuation in sensitivity for a humidity change in a use environment and applicable to the martial for solar battery, electronic paper, electrophotographic photoreceptor, etc. Namely, phthalocyanine crystal obtained by bringing a phthalocyanine crystal precursor into contact with an aromatic aldehyde compound to convert the crystal form. Also, provided is an electrophotographic photoreceptor that not only exhibits high sensitivity but also has little fluctuation in sensitivity for a humidity change in a use environment. Further, provided is an electrophotographic photoreceptor cartridge and an image-forming device, both of which can produce a stable quality images for a humidity change in a use environment by using the electrophotographic photoreceptor.

Abstract: To provide an electrophotographic photoreceptor which is excellent in electrical characteristics and image characteristics even at a low content of a charge transport material and which is less susceptible to a change in characteristics due to a change in the environment and has high durability with little deterioration, and an image forming apparatus having such an electrophotographic photoreceptor. An electrophotographic photoreceptor comprising an electroconductive substrate, and a charge transport layer and a charge generation layer formed on the substrate, characterized in that the charge transport layer comprises a charge transport material represented by the is following formula (1) and a binder resin, and the mass ratio of the charge transport material to the binder resin (i.e.

Abstract: Provided is an image-forming apparatus and a cartridge that are low in occurrence of smears in white areas, residual images, scattering, lines, thin spots, and dead dots, which are caused by particle size distribution of a toner and mismatching of a toner and a photoreceptor, exhibit satisfactory image quality, thin-line reproducibility, and cleaning properties, and can form high-resolution images without smears after long-time operation and selective development even in a high speed printing. The image-forming apparatus includes an electrophotographic photoreceptor of which photosensitive layer contains oxytitanium phthalocyanine showing main diffraction peaks at Bragg angles (2?) of 9.0° and 27.2° and at least one main diffraction peak in the range of 9.3° to 9.8° to CuK? rays, and the toner satisfies all the following requirements (1) to (3): (1) the volume median diameter (Dv50) is 4.0 ?m or more and 7.0 ?m or less, (2) the average sphericity is 0.

Abstract: An electrophotographic photoreceptor comprising a conductive support and a photosensitive layer formed thereon, wherein the photosensitive layer comprises a polyarylate resin having a repeating structure represented by the following formula [1] and a compound represented by the following formula [6]. This electrophotographic photoreceptor has excellent wearing resistance under load in the practical use of the photoreceptor and has high mechanical strength and extremely satisfactory electrical characteristcis.

Abstract: An electrophotographic photoreceptor having high performance that hardly generates image defects such as black spots, color spots, and interference fringes is provided. The electrophotographic photoreceptor includes an undercoat layer containing metal oxide particles and a binder resin on an electroconductive substrate having a maximum height surface roughness Rz in the range of 0.8?Rz?2 ?m, and a photosensitive layer disposed on the undercoat layer, wherein the metal oxide particles have a volume average particle diameter of 0.1 ?m or less and a 90% cumulative particle diameter of 0.3 ?m or less which are measured by a dynamic light-scattering method in a liquid containing the undercoat layer dispersed in a solvent mixture of methanol and 1-propanol at a weight ratio of 7:3.

Abstract: To provide an electrophotographic photoreceptor excellent in electric characteristics and various characteristics, capable of forming a uniform photosensitive layer and excellent in repetitive characteristics, an image forming apparatus using it and an electrophotgraphic cartridge. A lamination type electrophotographic photoreceptor comprising an electroconductive substrate and a photosensitive layer formed thereon, characterized in that the photosensitive layer contains a compound represented by the following formula (1), the ratio of the weight of the compound represented by the formula (1) to the weight content of all binder resins contained in the photosensitive layer is from 0.15 to 0.

Abstract: Provided is an electrophotographic photoreceptor that is excellent in electric characteristics and can form a high-quality image having reduced ghosting. In the electrophotographic photoreceptor including an undercoat layer containing metal oxide particles and a binder resin on an electroconductive support, and a photosensitive layer disposed on the undercoat layer, the metal oxide particles have a volume average particle diameter of 0.1 ?m or less and a 90% cumulative particle diameter of 0.3 ?m or less which are measured by a dynamic light-scattering method in a liquid containing the undercoat layer dispersed in a solvent mixture of methanol and 1-propanol at a weight ratio of 7:3; and the photosensitive layer contains a compound represented by the following Formula (I): where Formula (I), Ar1 to Ar6 each independently represent an aromatic moiety that may have a substituent; X represents an organic moiety that may have a substituent; and n1 and n2 each independently represent an integer of 0 to 2.

Abstract: To provide an electrophotographic photoreceptor showing suitable electric characteristics, capable of forming a favorable image even after repeated use for long term and capable of forming a high quality image free from image defects such as a memory phenomenon, an electrophotographic process cartridge using such an electrophotographic photoreceptor, and an image forming apparatus using such an electrophotographic photoreceptor. An electrophotographic photoreceptor comprising a photosensitive layer containing oxytitanium phthalocyanine showing chief diffraction peaks at Bragg angles (2?±0.2°) of 9.6°, 24.1° and 27.2° to CuK? characteristic X-ray (wavelength: 1.

Abstract: Provided are a coating liquid for forming an undercoat layer exhibiting high stability, a process for forming the coating liquid, a high-performance electrophotographic photoreceptor that is capable of forming a high-quality image under various use environments and exhibiting reduced image defects such as black spots and color spots, and an image-forming apparatus and electrophotographic cartridge including the electrophotographic photoreceptor. In the coating liquid for forming an undercoat layer of an electrophotographic photoreceptor containing metal oxide particles and a binder resin, the metal oxide particles have a number average particle diameter of 0.10?m or less and a 10% cumulative particle diameter of 0.060 ?m or less which are measured by a dynamic light-scattering method in the coating liquid for forming an undercoat layer.

Abstract: An electrophotographic photoreceptor having high sensitivity and hardly affected by the transfer in an electrophotographic process is provided. The electrophotographic photoreceptor includes an undercoat layer containing metal oxide particles and a binder resin and a photosensitive layer disposed on the undercoat layer, wherein the metal oxide particles have a volume average particle diameter of 0.1 ?m or less and a 90% cumulative particle diameter of 0.3 ?m or less which are measured by a dynamic light-scattering method in a liquid of the undercoat layer dispersed in a solvent mixture of methanol and 1-propanol at a weight ratio of 7:3, and the photosensitive layer contains a binder resin having an ester bond.

Abstract: A coating fluid for photosensitive-layer formation having high productivity and stability and a process thereof are provided. Also provided are a high-performance electrophotographic photoreceptor and an image-forming apparatus which are capable of forming high-quality images even in various use environments and are less apt to cause image defects such as black spots or color spots. The objects are accomplished with a process for producing a coating fluid which is for forming a photosensitive layer of an electrophotographic photoreceptor and comprises a charge-generating material and a binder resin, wherein a dispersing medium having an average particle diameter in the range of from 1.0 ?m to 350 ?m is used as a dispersing medium for dispersing the charge-generating material in the coating fluid for photosensitive-layer formation. The coating fluid for photosensitive-layer formation produced by this process is preferable as a photosensitive layer of an electrophotographic photoreceptor.

Abstract: To provide an image forming apparatus which is able to improve image quality while suppressing soiling of image white parts, scattering in the apparatus, streaks, fading, etc. due to non-uniformity in the particle size distribution of a toner or mismatching between a toner and a photoreceptor, and which has good cleaning properties, and even when a high speed printing machine is used, is able to reduce a problem of soiling, etc. in long-term use and provide excellent image stability.

Abstract: An electrophotographic photoreceptor having high sensitivity and low residual potential is provided. The electrophotographic photoreceptor includes an undercoat layer containing metal oxide particles and a binder resin on an electroconductive substrate, and a photosensitive layer disposed on the undercoat layer, wherein the metal oxide particles have a volume average particle diameter of 0.1 ?m or less and a 90% cumulative particle diameter of 0.3 ?m or less which are measured by a dynamic light-scattering method in a liquid of the undercoat layer dispersed in a solvent mixture of methanol and 1-propanol at a weight ratio of 7:3; and the photosensitive layer contains crystalline phthalocyanine showing at least one distinct main diffraction peak at a Bragg angle (2?±0.2°) of 27.0° to 29.0° in an X-ray diffraction spectrum.

Abstract: To provide a toner excellent in the image stability, whereby the image quality can be improved while suppressing soiling of image white parts, residual images (ghosts), fading (blotted image follow-up properties), etc., cleaning properties are good, and even when a high speed printing machine is used, it is possible to reduce a problem of soiling, etc. An image forming apparatus comprising an electrophotographic photoreceptor and a toner for developing an electrostatic charge image, wherein a photosensitive layer of the electrophotographic photoreceptor contains a resin having a structural unit represented by the following formula (A); the toner for developing an electrostatic charge image is a toner for developing an electrostatic charge image containing toner matrix particles formed in an aqueous medium; the toner has a volume median diameter (Dv50) of from 4.0 ?m to 7.

Abstract: To provide an image forming apparatus which is capable of suppressing soiling of image white parts, residual images (ghosts), fading, etc. due to non-uniformity in the particle size distribution of a toner or mismatching between a toner and a photoreceptor and which is able to improve image quality, provides good fixing properties and cleaning properties with little fogging or dot missing, presents good reproducibility of fine lines, and even when a high speed printing machine is used, can reduce a problem of e.g. soiling in a long-term use and presents excellent image stability.

Abstract: To provide an electrophotographic photoreceptor having a high sensitivity, a good balance of various electric properties such as chargeability and residual potential, a good stability of the coating solution, and an excellent light resistance. An electrophotographic photoreceptor comprising an electroconductive support having thereon a photosensitive layer, wherein the photosensitive layer contains a compound represented by the following formula (1): (wherein R1 represents a group having a chiral center, R2 represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent, R3 and R4 each independently represents an alkylene group which may have a substituent, or an arylene group which may have a substituent, and R5, R6, R7 and R8 each independently represents an alkyl group which may have a substituent, or an aryl group which may have a substituent, and at least one member of R5 to R8 is an aryl group having a substituent).

Abstract: A high-sensitivity and long-life electrophotographic photoreceptor comprising an electroconductive substrate and at least a photosensitive layer on the electroconductive substrate is provided, wherein the photosensitive layer contains a polyarylate resin not having a nitrogen atom in its repeating unit, and the Hall mobility at an electric field strength of 3×105 (V/cm) and at a temperature of 21° C. of the photosensitive layer is 3×10−6 (cm2/Vs) or more.

Abstract: A high-sensitivity and long-life electrophotographic photoreceptor comprising an electroconductive substrate and at least a photosensitive layer on the electroconductive substrate is provided, wherein the photosensitive layer contains a polyarylate resin not having a nitrogen atom in its repeating unit, and the Hall mobility at an electric field strength of 3×105 (V/cm) and at a temperature of 21° C. of the photosensitive layer is 3×10−6 (cm2/Vs) or more.

Abstract: A high-sensitivity and long-life electrophotographic photoreceptor comprising an electroconductive substrate and at least a photosensitive layer on the electroconductive substrate is provided, wherein the photosensitive layer contains a polyarylate resin not having a nitrogen atom in its repeating unit, and the Hall mobility at an electric field strength of 3×105 (V/cm) and at a temperature of 21° C. of the photosensitive layer is 3×10−6 (cm2/Vs) or more.

Abstract: A high-sensitivity and long-life electrophotographic photoreceptor comprising an electroconductive substrate and at least a photosensitive layer on the electroconductive substrate is provided, wherein the photosensitive layer contains a polyarylate resin not having a nitrogen atom in its repeating unit, and the Hall mobility at an electric field strength of 3×105 (V/cm) and at a temperature of 21° C. of the photosensitive layer is 3×10−6 (cm2/Vs) or more.