A compound has a structure represented by the following formula (C1):

##STR00001## wherein R.sub.a1, R.sub.a2, R.sub.a3, R.sub.a41, R.sub.a42, R.sub.a43, R.sub.a44, R.sub.a45, R.sub.a5, R.sub.a6, R.sub.a7, R.sub.a8, R.sub.a9, R.sub.a10, and R.sub.a11 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aralkyl group, an aryl group, a cyano group, a halogen atom, or a group obtained by combining two or more of the above groups, and a combination of R.sub.a1 and R.sub.a2, R.sub.a41 and R.sub.a42, R.sub.a42 and R.sub.a43, R.sub.a43 and R.sub.a44, R.sub.a44 and R.sub.a45, R.sub.a5 and R.sub.a6, R.sub.a8 and R.sub.a9, or R.sub.a10 and R.sub.a11 each independently may form a ring.

An image forming apparatus includes an electrophotographic photoreceptor that includes a photosensitive layer that contains a charge generation material, a charge transport material, and a binder resin; a charging unit; an electrostatic latent image forming unit; a developing unit; and a transfer unit. A charge amount Q(C/m.sup.2), which is accumulated in the photosensitive layer by exposure conducted by using the electrostatic latent image forming unit, per unit area of a surface of the electrophotographic photoreceptor, a charge potential VH(V) after the surface of the electrophotographic photoreceptor is charged by using the charging unit, and an exposure potential VL(V) of a portion of the surface of the electrophotographic photoreceptor exposed by using the electrostatic latent image forming unit satisfy the following formula: 20(V.Math.m.sup.2/C)[VHVL](V)/Q(C/m.sup.2)60(V.Math.m.sup.2/C)

The present invention is to provide a charge transport substance having high resistance to stress within electrophotographic processes, an electrophotographic photoreceptor which has excellent high-speed responsiveness, shows a sufficient residual potential, and has high resistance to stress within electrophotographic processes, an electrophotographic cartridge, and an image-forming apparatus. The invention provides a charge transport substance having a specific structure. The invention further provides an electrophotographic photoreceptor including a photosensitive layer which contains the charge transport substance having a specific structure, an electrophotographic cartridge, and an image-forming apparatus, equipped with this electrophotographic photoreceptor.

An electrophotographic photosensitive member includes a photosensitive layer. The photosensitive layer contains a charge generating material and a hole transport material represented by general formula (1) shown below in a single layer. Titanyl phthalocyanine contained as the charge generating material exhibits a main peak at a Bragg angle 20.2=27.2 in a CuK characteristic X-ray diffraction spectrum and satisfies either (B) or (C), shown below, in a differential scanning calorimetry spectrum. (B) A peak is not present in a range from 50 C. to 400 C., other than a peak resulting from vaporization of adsorbed water. (C) A peak is not present in a range from 50 C. to 270 C., other than a peak resulting from vaporization of adsorbed water, and a peak is present in a range from 270 C. to 400 C. ##STR00001##

A triarylamine derivative is represented by general formula (I). In general formula (I), R.sub.1 and R.sub.2 each represent, independently of one another, a chemical group selected from the group consisting of a halogen atom, an optionally substituted alkyl group having a carbon number of 1-6, an optionally substituted alkoxy group having a carbon number of 1-6, and an optionally substituted aryl group having a carbon number of 6-12. In general formula (I), k and l each represent an integer of at least 0 and no greater than 4. When k and l represent integers greater than 1, chemical groups R.sub.1 bonded to the same aromatic ring and chemical groups R.sub.2 bonded to the same aromatic ring may be the same or different to one another. In general formula (I), m and n each represent a different integer of at least 1 and no greater than 3. ##STR00001##

A triphenylamine derivative is represented by general formula (1). In general formula (1), R.sub.1 to R.sub.7 each represent, independently of one another, a chemical group selected from the group consisting of a halogen atom, an optionally substituted alkyl group having a carbon number of at least 1 and no greater than 6, an optionally substituted alkoxy group having a carbon number of at least 1 and no greater than 6, and an optionally substituted aryl group having a carbon number of at least 6 and no greater than 12. Also, k, l, m, n, o, and p each represent, independently of one another, an integer of at least 0 and no greater than 4. When any of k, l, m, n, o, or p represents an integer greater than 1, chemical groups R.sub.3, R.sub.4, R.sub.5, R.sub.6, or R.sub.7 bonded to the same aromatic ring may be the same or different. ##STR00001##

A diamine compound is represented by general formula (1). In the general formula (1), R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, and R.sub.10 each represent, independently of one another, a hydrogen atom, a halogen atom, an optionally substituted alkyl group having a carbon number of at least 1 and no greater than 6, an optionally substituted alkoxy group having a carbon number of at least 1 and no greater than 6, or an optionally substituted aryl group having a carbon number of at least 6 and no greater than 14. m represents an integer of at least 1 and no greater than 3. n represents an integer of at least 0 and no greater than 2. ##STR00001##

An electrophotographic photoconductor includes a conductive support; and a photoconductive layer that contains at least a charge generation material, a hole transport material, an electron transport material and a binder resin, and that is provided on the conductive support, wherein the photoconductive layer has an outermost layer that contains a charge generation material, a hole transport material, an electron transport material, a binder resin and a highly branched polymer that is obtained by polymerizing, in the presence of a polymerization initiator, a monomer having, in a molecule, two or more radically polymerizable double bonds and a monomer having, in a molecule, a long-chain alkyl group or an alicyclic group and at least one radically polymerizable double bond. The electrophotographic photoconductor exhibits superior operational stability and stably high image quality, without problems with image memory, a contact member, or image defects due to cracks caused by contamination by oils/fats or sebum.

A charge transporting layer of an electrophotographic photosensitive member contains a polysiloxane resin having a terminal structure represented by the formula (1), at least one selected from the group consisting of a polycarbonate resin A having a structural unit represented by the formula (A) and a polyarylate resin B having a structural unit represented by the formula (B), and a charge transporting substance, wherein the content of the siloxane structure in the polysiloxane resin is not less than 0.5% by mass and not more than 10% by mass based on the total mass of whole resin in the charge transporting layer.

Provided are an asymmetric butadiene-based charge transporting compound represented by one of Formula (1) and (1) as in claim 1, an electrophotographic photoreceptor including the asymmetric butadiene-based charge transporting compound, and an electrophotographic imaging apparatus. The electrophotographic photoreceptor including the organic photoconductive material as a charge transporting material may not cause a problem, such as partial crystallization during film formation and may have a high charge potential, a sufficient photoresponsive property with high sensitivity, and a high durability. Moreover, these properties may be all maintained even in the case of exposure to light as well as use in low-temperature environments or high-speed processes, thus having high reliability.