Photosensitive body for electrophotography, method for producing same and electrophotographic apparatus

Abstract

An electrophotographic photoreceptor includes a conductive substrate; and a photosensitive layer arranged on the conductive substrate and containing, as a charge generating material, any one material selected from the group consisting of titanyl phthalocyanines, metal-free phthalocyanines, chlorogallium phthalocyanines and hydroxygallium phthalocyanines; and, as an electron transporting material, a naphthalene tetracarboxylic acid diimide compound represented by Formula (1) below, where R.sup.1 and R.sup.2 each represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkylene group, an alkoxy group, an alkyl ester group, a phenyl group optionally having a substituent, a naphthyl group optionally having a substituent, or a halogen element; and R.sup.1 and R.sup.2 are optionally the same or different: ##STR00001##
The photoreceptor realizes a stable print density even in a low-temperature environment by suppressing a reduction in print density that is caused by potential fluctuation of the photoreceptor in the low-temperature environment.

Claims

1. An electrophotographic photoreceptor, comprising: a conductive substrate; and a photosensitive layer that is provided on the conductive substrate, that is a laminate-type positively-chargeable photosensitive layer in which a charge transport layer and a charge generation layer are sequentially laminated on the conductive substrate in that order, wherein (a) the charge transport layer consists essentially of: a hole transporting material that comprises a compound represented by Formulae (2) to (4) below; and a resin binder that comprises a polycarbonate resin having a repeating unit represented by Formula (6) below; and (b) the charge generation layer contains: a charge generating material selected from the group consisting of titanyl phthalocyanines, metal-free phthalocyanines, chlorogallium phthalocyanines and hydroxygallium phthalocyanines; a hole transporting material that comprises a compound represented by Formulae (2) to (4) below; an electron transporting material that is any one compound represented by Formulae (E-2), (E-5) and (E-11) below; and a resin binder that comprises a polycarbonate resin having a repeating unit represented by Formula (6) below: ##STR00199## where Ra represents a methyl group in Formula 2; and Ra represents a hydrogen atom, an optionally branched alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group optionally having a substituent, or a styryl group optionally having a substituent in Formula (3) and Formula (4); where Rd represents a hydrogen atom, an optionally branched alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group optionally having a substituent, or a styryl group optionally having a substituent; where Rb represents a methyl group in Formula (2); and Rb represents a hydrogen atom, an optionally branched alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms in Formula (3); where Rc represents a hydrogen atom, an optionally branched alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; where Rf represents a hydrogen atom, an optionally branched alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group in Formula (4) but not in Formula (3), which phenyl group in Formula (4) optionally has a substituent, a styryl group optionally having a substituent, or a 4-phenyl butadiene group optionally having a substituent; and where x and y each represent an integer of 1 to 5 and are different in Formula (2); x and y each represent an integer of 0 to 5 in Formula (3); x represents an integer of 0 to 5 in Formula (4); p represents an integer of 0 to 5; z represents an integer of 0 to 4; l represents an integer of 0 to 2; and m represents an integer of 2 to 4; ##STR00200## where R.sup.3 and R.sup.4 each represent a hydrogen atom, a methyl group, or an ethyl group; where X represents an oxygen atom, a sulfur atom, or CR.sup.5R.sup.6; and where R.sup.5 and R.sup.6 each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group optionally having a substituent, or R.sup.5 and R.sup.6 are optionally cyclically bound to form a cycloalkyl group having 4 to 6 carbon atoms, the cycloalkyl group optionally has a substituent; and R.sup.5 and R.sup.6 are optionally the same or different; and ##STR00201##

2. A method of producing an electrophotographic photoreceptor according to claim 1, the method comprising: providing the conductive substrate; and forming a photosensitive layer that is a laminate-type positively-chargeable photosensitive layer on the conductive substrate by: providing a coating solution for coating the charge transport layer; coating the coating solution for coating the charge transport layer onto the conductive substrate to provide the charge transport layer; providing a coating solution for coating the charge generating layer; and coating the coating solution for coating the charge generation layer onto the charge transport layer to provide the charge generation layer.

3. An electrophotographic apparatus equipped with the electrophotographic photoreceptor according to claim 1.

4. The electrophotographic photoreceptor according to claim 1, wherein the charge generating material of the charge generation layer comprises a titanyl phthalocyanine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic cross-sectional view showing one example of the electrophotographic photoreceptor of the present invention;

(2) FIG. 2 is a schematic cross-sectional view showing another example of the electrophotographic photoreceptor of the present invention; and

(3) FIG. 3 is a schematic structural view showing one example of the electrophotographic apparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) Concrete embodiments of the electrophotographic photoreceptor of the present invention will now be described in detail referring to the drawings. The present invention, however, is not restricted to the following descriptions by any means.

(5) FIG. 1 is a schematic cross-sectional view showing one example of the electrophotographic photoreceptor of the present invention, which is a positively-chargeable single layer-type electrophotographic photoreceptor. As illustrated, in the positively-chargeable single layer-type photoreceptor, an undercoat layer 2 and a single layer-type photosensitive layer 3, which has both a charge generation function and a charge transport function, are sequentially laminated on a conductive substrate 1.

(6) Further, FIG. 2 is a schematic cross-sectional view showing another example of the electrophotographic photoreceptor of the present invention, which is a positively-chargeable laminate-type electrophotographic photoreceptor. As illustrated, in the positively-chargeable laminate-type photoreceptor, a laminate-type positively-chargeable photosensitive layer 6, in which a charge transport layer 4 having a charge transport function and a charge generation layer 5 having a charge generation function are sequentially laminated, is arranged on the surface of the conductive substrate 1 having a cylindrical form with the undercoat layer 2 in between. It is noted here that the undercoat layer 2 may be arranged as required.

(7) In the photoreceptor according to one embodiment of the present invention, the photosensitive layer comprises: as a charge generating material, any one material selected from the group consisting of titanyl phthalocyanines, metal-free phthalocyanines, chlorogallium phthalocyanines and hydroxygallium phthalocyanines; and, as an electron transporting material, a naphthalene tetracarboxylic acid diimide compound represented by the above-described Formula (1). The use of a combination of the specific charge generating material and the specific electron transporting material in the photosensitive layer enables to suppress potential fluctuation of the photoreceptor in a low-temperature environment and to inhibit a reduction in print density that is caused by the potential fluctuation, whereby a photoreceptor having a stable print density can be realized.

(8) As a titanyl phthalocyanine, for example, -type titanyl phthalocyanine, -type titanyl phthalocyanine, Y-type titanyl phthalocyanine, amorphous titanyl phthalocyanine, or a titanyl phthalocyanine which is described in Japanese Unexamined Patent Application Publication No. H8-209023, U.S. Pat. No. 5,736,282 or 5,874,570 and has a maximum peak at a Bragg angle (2) of 9.6 in CuK:X-ray diffraction spectrum can be used. As a metal-free phthalocyanine, for example, an X-type metal-free phthalocyanine or a T-type metal-free phthalocyanine can be used.

(9) Specific examples of the naphthalene tetracarboxylic acid diimide compound that is represented by the Formula (1) and used as an electron transporting material include compounds represented by Formulae (E-1) to (E-176) below. Thereamong, from the standpoint of the solubility in the preparation of a coating solution, structures in which either or both of R.sup.1 and R.sup.2 is/are an alkyl group(s) are preferred.

(10) TABLE-US-00001 TABLE 1 Compound R.sup.1 R.sup.2 E-1 CH.sub.3 CH.sub.3 E-2 CH.sub.3 C.sub.2H.sub.5 E-3 CH.sub.3 C.sub.3H.sub.7 E-4 CH.sub.3 C.sub.4H.sub.9 E-5 CH.sub.3 C.sub.5H.sub.11 E-6 CH.sub.3 C.sub.6H.sub.13 E-7 CH.sub.3 C.sub.7H.sub.15 E-8 CH.sub.3 C.sub.8H.sub.17 E-9 CH.sub.3 C.sub.9H.sub.19 E-10 CH.sub.3 E-11 CH.sub.3 CH(CH.sub.3).sub.2 E-12 CH.sub.3 CH.sub.2CH(CH.sub.3).sub.2 E-13 CH.sub.3 C.sub.2H.sub.4CH(CH.sub.3).sub.2 E-14 H H E-15 H CH.sub.3 E-16 H C.sub.2H.sub.5 E-17 H C.sub.3H.sub.7 E-18 H C.sub.4H.sub.9 E-19 H C.sub.5H.sub.11 E-20 H C.sub.6H.sub.13 E-21 H C.sub.7H.sub.15 E-22 H C.sub.8H.sub.17 E-23 H C.sub.9H.sub.19 E-24 H

(11) TABLE-US-00002 TABLE 2 Compound R.sup.1 R.sup.2 E-25 C.sub.2H.sub.5 C.sub.2H.sub.5 E-26 C.sub.2H.sub.5 C.sub.3H.sub.7 E-27 C.sub.2H.sub.5 C.sub.4H.sub.9 E-28 C.sub.2H.sub.5 C.sub.5H.sub.11 E-29 C.sub.2H.sub.5 C.sub.6H.sub.13 E-30 C.sub.2H.sub.5 C.sub.7H.sub.15 E-31 C.sub.2H.sub.5 C.sub.8H.sub.17 E-32 C.sub.2H.sub.5 C.sub.9H.sub.19 E-33 C.sub.2H.sub.5 E-34 C.sub.3H.sub.7 C.sub.3H.sub.7 E-35 C.sub.3H.sub.7 C.sub.4H.sub.9 E-36 C.sub.3H.sub.7 C.sub.5H.sub.11 E-37 C.sub.3H.sub.7 C.sub.6H.sub.13 E-38 C.sub.3H.sub.7 C.sub.7H.sub.15 E-39 C.sub.3H.sub.7 C.sub.8H.sub.17 E-40 C.sub.3H.sub.7 C.sub.9H.sub.19 E-41 C.sub.3H.sub.7 E-42 C.sub.4H.sub.9 C.sub.4H.sub.9 E-43 C.sub.4H.sub.9 C.sub.5H.sub.11 E-44 C.sub.4H.sub.9 C.sub.6H.sub.13 E-45 C.sub.4H.sub.9 C.sub.7H.sub.15 E-46 C.sub.4H.sub.9 C.sub.8H.sub.17 E-47 C.sub.4H.sub.9 C.sub.9H.sub.19 E-48 C.sub.4H.sub.9 0

(12) TABLE-US-00003 TABLE 3 Compound R.sup.1 R.sup.2 E-49 H E-50 H E-51 H E-52 H E-53 H E-54 H E-55 H E-56 H E-57 H E-58 H 0 E-59 H E-60 H E-61 H E-62 H E-63 CH.sub.3

(13) TABLE-US-00004 TABLE 4 Compound R.sup.1 R.sup.2 E-64 CH.sub.3 E-65 CH.sub.3 E-66 CH.sub.3 E-67 CH.sub.3 E-68 CH.sub.3 0 E-69 CH.sub.3 E-70 CH.sub.3 E-71 CH.sub.3 E-72 CH.sub.3 E-73 CH.sub.3 E-74 CH.sub.3 E-75 CH.sub.3 E-76 CH.sub.3

(14) TABLE-US-00005 TABLE 5 Compound R.sup.1 R.sup.2 E-77 C.sub.2H.sub.5 E-78 C.sub.2H.sub.5 0 E-79 C.sub.2H.sub.5 E-80 C.sub.2H.sub.5 E-81 C.sub.2H.sub.5 E-82 C.sub.2H.sub.5 E-83 C.sub.2H.sub.5 E-84 C.sub.2H.sub.5 E-85 C.sub.2H.sub.5 E-86 C.sub.2H.sub.5 E-87 C.sub.2H.sub.5 E-88 C.sub.2H.sub.5 0 E-89 C.sub.2H.sub.5 E-90 C.sub.2H.sub.5

(15) TABLE-US-00006 TABLE 6 Compound R.sup.1 R.sup.2 E-91 C.sub.3H.sub.7 E-92 C.sub.3H.sub.7 E-93 C.sub.3H.sub.7 E-94 C.sub.3H.sub.7 E-95 C.sub.3H.sub.7 E-96 C.sub.3H.sub.7 E-97 C.sub.3H.sub.7 E-98 C.sub.3H.sub.7 0 E-99 C.sub.3H.sub.7 E-100 C.sub.3H.sub.7 E-101 C.sub.3H.sub.7 E-102 C.sub.3H.sub.7 E-103 C.sub.3H.sub.7 E-104 C.sub.3H.sub.7

(16) TABLE-US-00007 TABLE 7 Compound R.sup.1 R.sup.2 E-105 C.sub.4H.sub.9 E-106 C.sub.4H.sub.9 E-107 C.sub.4H.sub.9 E-108 C.sub.4H.sub.9 0 E-109 C.sub.4H.sub.9 E-110 C.sub.4H.sub.9 E-111 C.sub.4H.sub.9 E-112 C.sub.4H.sub.9 E-113 C.sub.4H.sub.9 E-114 C.sub.4H.sub.9 E-115 C.sub.4H.sub.9 E-116 C.sub.4H.sub.9 E-117 C.sub.4H.sub.9 E-118 C.sub.4H.sub.9 0

(17) TABLE-US-00008 TABLE 8 Compound R.sup.1 R.sup.2 E-119 C.sub.5H.sub.11 E-120 C.sub.5H.sub.11 E-121 C.sub.5H.sub.11 E-122 C.sub.5H.sub.11 E-123 C.sub.5H.sub.11 E-124 C.sub.5H.sub.11 E-125 C.sub.5H.sub.11 E-126 C.sub.5H.sub.11 E-127 C.sub.5H.sub.11 E-128 C.sub.5H.sub.11 0 E-129 C.sub.5H.sub.11 E-130 C.sub.5H.sub.11 E-131 C.sub.5H.sub.11 E-132 C.sub.5H.sub.11

(18) TABLE-US-00009 TABLE 9 Compound R.sup.1 R.sup.2 E-133 E-134 E-135 00 E-136 01 02 E-137 03 04 E-138 05 06 E-139 07 08 E-140 09 0 E-141 E-142 E-143 E-144 E-145 0 E-146

(19) TABLE-US-00010 TABLE 10 Compound R.sup.1 R.sup.2 E-147 E-148 E-149 E-150 0 E-151 E-152 E-153 E-154 E-155 0 E-156 E-157 E-158 E-159

(20) TABLE-US-00011 TABLE 11 Compound R.sup.1 R.sup.2 E-160 0 E-161 E-162 E-163 E-164 E-165 0 E-166 E-167 E-168 E-169 E-170 0 E-171 E-172

(21) TABLE-US-00012 TABLE 12 Compound R.sup.1 R.sup.2 E-173 E-174 E-175 0 E-176

(22) The conductive substrate 1 not only functions as an electrode of the photoreceptor but also serves as a support of the layers constituting the photoreceptor, and the conductive substrate 1 may take any form, such as a cylindrical form, a plate form or a film form. As the material of the conductive substrate 1, for example, a metal (e.g., aluminum, stainless steel, or nickel), or a material such as glass or resin, having a surface subjected to a conductive treatment, can be used.

(23) The undercoat layer 2 is composed of a layer containing resin as a main component, or a metal oxide film of alumite or the like. The undercoat layer 2 is arranged as required for the purposes of, for example, controlling the injectability of a charge from the conductive substrate 1 into the photosensitive layer, covering surface defects of the conductive substrate, and improving the adhesion between the photosensitive layer and the conductive substrate 1. Examples of a resin material used in the undercoat layer 2 include insulating polymers, such as casein, polyvinyl alcohol, polyamide, melamine and cellulose; and conductive polymers, such as polythiophene, polypyrrole and polyaniline, and these resins may be used individually, or as a mixture of an appropriate combination. Further, a metal oxide such as titanium dioxide or zinc oxide may be incorporated into these resins.

(24) Positively-Chargeable Single Layer-Type Photoreceptor

(25) In the case of a positively-chargeable single layer-type photoreceptor, the single layer-type photosensitive layer 3 functions as a photosensitive layer containing the above-described specific charge generating material and electron transporting material. In the positively-chargeable single layer-type photoreceptor, the single layer-type photosensitive layer 3 is a single layer-type positively-chargeable photosensitive layer which mainly contains, in a single layer, a charge generating material, a hole transporting material, an electron transporting material (acceptor compound), and a resin binder.

(26) The charge generating material of the single layer-type photosensitive layer 3 is required to contain any one material selected from the group consisting of titanyl phthalocyanines, metal-free phthalocyanines, chlorogallium phthalocyanines and hydroxygallium phthalocyanines, and one or more of other widely used charge generating materials may be used in combination as well. Examples of such other charge generating materials that can be used include phthalocyanine pigments other than the above, azo pigments, anthoanthrone pigments, perylene pigments, perinone pigments, polycyclic quinone pigments, squarylium pigments, thiapyrylium pigments, and quinacridone pigments. Particularly, disazo pigments and trisazo pigments can be used as azo pigments; N,N-bis(3,5-dimethylphenyl)-3,4:9,10-perylene-bis(carboximide) can be used as a perylene pigment; and copper phthalocyanines such as e-type copper phthalocyanine can be used as other phthalocyanine pigments. The charge generating material is effective as long as it is added in an amount of 0.1 to 20% by mass with respect to the total amount of the photosensitive layer, and a charge generating material other than titanyl phthalocyanines, metal-free phthalocyanines, chlorogallium phthalocyanines and hydroxygallium phthalocyanines can be added up to a range where the total amount of the charge generating materials is 20% by mass.

(27) The electron transporting material of the single layer-type photosensitive layer 3 is required to contain a naphthalene tetracarboxylic acid diimide compound represented by the Formula (1), and one or more of other widely used electron transporting materials may be used in combination as well. Examples of such other electron transporting materials that can be used in combination include succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, pyromellitic acid, trimellitic acid, trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyanoethylene, tetracyanoquinodimethane, chloranil, bromanil, o-nitrobenzoic acid, malononitrile, trinitrofluorenone, trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, thiopyran compounds, quinone compounds, benzoquinone compounds, diphenoquinone compounds, naphthoquinone compounds, anthraquinone compounds, stilbenequinone compounds, and azoquinone compounds. The electron transporting material represented by the Formula (1) is effective as long as it is added in an amount of 1 to 50% by mass with respect to the total amount of the photosensitive layer, and an electron transporting material other than the one represented by the Formula (1) can be added up to a range where the total amount of the electron transporting materials is 50% by mass.

(28) As the hole transporting material of the single layer-type photosensitive layer 3, for example, hydrazone compounds, pyrazoline compounds, pyrazolone compounds, oxadiazole compounds, oxazole compounds, arylamine compounds, benzidine compounds, stilbene compounds, styryl compounds, poly-N-vinylcarbazoles, and polysilanes can be used and, thereamong, an arylamine compound is preferred. These hole transporting materials may be used individually, or in a combination of two or more thereof. The hole transporting material is preferably one which exhibits an excellent ability to transport holes generated during irradiation with light and is suitable for combining with the charge generating material.

(29) Examples of the suitable hole transporting material include those represented by the above-described Formulae (2) to (5). Further, as a specific example of the suitable hole transporting material, it is preferred that the hole transporting material contain any one arylamine compound represented by Formulae (H-1) to (H-30) below. From the standpoint of the stability of environmental characteristics, it is more preferred that the hole transporting material be an arylamine compound.

(30) ##STR00183## ##STR00184## ##STR00185## ##STR00186##

(31) As the resin binder of the single layer-type photosensitive layer 3, for example, various polycarbonate resins other than the above-mentioned ones, such as bisphenol A-type polycarbonates, bisphenol Z-type polycarbonates, bisphenol A-type polycarbonate-biphenyl copolymers, and bisphenol Z-type polycarbonate-biphenyl copolymers; polyphenylene resins; polyester resins; polyvinyl acetal resins; polyvinyl butyral resins; polyvinyl alcohol resins; vinyl chloride resins; vinyl acetate resins; polyethylene resins; polypropylene resins; acrylic resins; polyurethane resins; epoxy resins; melamine resins; silicone resins; polyamide resins; polystyrene resins; polyacetal resins; polyarylate resins; polysulfone resins; methacrylate polymers; and copolymers of these resins can be used. Further, a mixture of resins of the same kind but with different molecular weights may be used as well.

(32) Examples of a suitable resin binder include polycarbonate resins having a repeating unit represented by the Formula (6). Further, more specific examples of the suitable resin binder include polycarbonate resins having any one repeating unit represented by Formulae (B-1) to (B-10) below:

(33) ##STR00187##

(34) The content of the charge generating material(s) in the single layer-type photosensitive layer 3 is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, with respect to the solid content of the single layer-type photosensitive layer 3. The content of the hole transporting material(s) in the single layer-type photosensitive layer 3 is preferably 3 to 80% by mass, more preferably 5 to 60% by mass, with respect to the solid content of the single layer-type photosensitive layer 3. The content of the electron transport material(s) in the single layer-type photosensitive layer 3 is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, with respect to the solid content of the single layer-type photosensitive layer 3. The content of the resin binder in the single layer-type photosensitive layer 3 is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, with respect to the solid content of the single layer-type photosensitive layer 3.

(35) In order to maintain a practically effective surface potential, the thickness of the single layer-type photosensitive layer 3 is in a range of preferably 3 to 100 m, more preferably 5 to 40 m.

(36) Positively-Chargeable Laminate-Type Photoreceptor

(37) In the case of a positively-chargeable laminate-type photoreceptor, the laminate-type positively-chargeable photosensitive layer 6 constituted by the charge transport layer 4 and the charge generation layer 5 functions as a photosensitive layer containing the above-described specific charge generating material and electron transporting material. In the positively-chargeable laminate-type photoreceptor, the charge transport layer 4 contains at least a hole transporting material and a resin binder, and the charge generation layer 5 contains at least a charge generating material, a hole transporting material, an electron transporting material, and a resin binder.

(38) As the hole transporting material and the resin binder in the charge transport layer 4, the same materials as those exemplified above for the single layer-type photosensitive layer 3 can be used.

(39) The content of the hole transporting material in the charge transport layer 4 is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, with respect to the solid content of the charge transport layer 4. The content of the resin binder in the charge transport layer 4 is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, with respect to the solid content of the charge transport layer 4.

(40) In order to maintain a practically effective surface potential, the thickness of the charge transport layer 4 is in a range of preferably 3 to 50 m, more preferably 15 to 40 m.

(41) As the hole transporting material and the resin binder in the charge generation layer 5, the same materials as those exemplified above for the single layer-type photosensitive layer 3 can be used. Further, as the charge generating material in the charge generation layer 5, in the same manner as in the single layer-type photosensitive layer 3, one or more of other widely used charge generating materials may be additionally used in combination with the above-described specific charge generating material. Moreover, as the electron transporting material in the charge generation layer 5, in the same manner as in the single layer-type photosensitive layer 3, one or more of other widely used electron transporting materials may be additionally used in combination with the above-described naphthalene tetracarboxylic acid diimide compound. The contents of the respective materials and the thickness of the charge generation layer 5 can also be the same as in the single layer-type photosensitive layer 3 of the single layer-type photoreceptor.

(42) In one embodiment of the present invention, for the purposes of improving the leveling of the resulting film and imparting lubricity, a leveling agent such as a silicone oil or a fluorine-based oil may also be incorporated into the laminate-type or single layer-type photosensitive layer. In addition, for the purposes of adjusting the film hardness, reducing the frictional coefficient, imparting lubricity and the like, plural kinds of inorganic oxides may be incorporated. For example, fine particles of a metal oxide (e.g., silica, titanium oxide, zinc oxide, calcium oxide, alumina, or zirconium oxide), a metal sulfate (e.g., barium sulfate or calcium sulfate) or a metal nitride (e.g., silicon nitride or aluminum nitride), particles of a fluorine-based resin such as tetrafluoroethylene resin, or a fluorine-based comb-type graft polymer resin may be incorporated as well. Moreover, as required, other known additive(s) may also be incorporated within a range that does not markedly impair the electrophotographic properties.

(43) Furthermore, in the photosensitive layer, deterioration inhibitors such as an antioxidant and a light stabilizer may also be incorporated for the purpose of improving the environmental resistance and the stability against damaging light. Examples of compounds used for such a purpose include chromanol derivatives such as tocopherol, as well as esterified compounds, polyarylalkane compounds, hydroquinone derivatives, etherified compounds, dietherified compounds, benzophenone derivatives, benzotriazole derivatives, thioether compounds, phenylenediamine derivatives, phosphonates, phosphites, phenolic compounds, hindered phenol compounds, linear amine compounds, cyclic amine compounds, and hindered amine compounds.

(44) Method of Producing Photoreceptor

(45) The photoreceptor according to one embodiment of the present invention can be produced by forming a photosensitive layer using any one material selected from the group consisting of titanyl phthalocyanines, metal-free phthalocyanines, chlorogallium phthalocyanines and hydroxygallium phthalocyanines as a charge generating material along with a naphthalene tetracarboxylic acid diimide compound represented by the Formula (1) above as an electron transporting material. The method of producing the photoreceptor may also include: a step of preparing a conductive substrate; and a step of preparing a coating solution in which the above-described specific charge generating material and electron transporting material as well as arbitrary hole transporting material and resin binder are dissolved or dispersed in a solvent.

(46) Specifically, a single layer-type photoreceptor can be produced by a method comprising: a step of preparing a coating solution for the formation of a single layer-type photosensitive layer by dissolving or dispersing the above-described specific charge generating material and electron transporting material as well as arbitrary hole transporting material and resin binder in a solvent; and a step of forming a photosensitive layer by coating and then drying the thus prepared coating solution for the formation of a single layer-type photosensitive layer on the outer periphery of a conductive substrate via an undercoat layer as desired.

(47) In the case of a laminate-type photoreceptor, first, a charge transport layer is formed by a method comprising: a step of preparing a coating solution for the formation of a charge transport layer by dissolving arbitrary hole transporting material and resin binder in a solvent; and a step of forming a charge transport layer by coating and then drying the thus prepared coating solution for the formation of a charge transport layer on the outer periphery of a conductive substrate via an undercoat layer as desired. Next, a charge generation layer is formed by a method comprising: a step of preparing a coating solution for the formation of a charge generation layer by dissolving or dispersing the above-described specific charge generating material and electron transporting material as well as arbitrary hole transporting material and resin binder in a solvent; and a step of forming a charge generation layer by coating and then drying the thus prepared coating solution for the formation of a charge generation layer on the above-formed charge transport layer. The laminate-type photoreceptor of one embodiment can be produced by such a production method. The above-described coating solutions can be applied to a variety of coating methods, such as dip coating and spray coating, and are not restricted to any one coating method. Further, the types of the solvents used for the preparation of the coating solutions, the coating conditions, the drying conditions and the like can be selected as appropriate in accordance with a conventional method and are not particularly restricted.

(48) Electrophotographic Apparatus

(49) The electrophotographic photoreceptor according to one embodiment of the present invention exerts desired effects when applied to various machine processes. Specifically, sufficient effects can be obtained not only in charging processes such as contact charging systems using a charging member (e.g., a roller or a brush) and non-contact charging systems using a corotron or a scorotron, but also in development processes such as non-contact development and contact development systems using, for example, a non-magnetic single-component, magnetic single-component or two-component developing agent.

(50) The electrophotographic apparatus according to one embodiment of the present invention is equipped with the above-described electrophotographic photoreceptor. FIG. 3 is a schematic structural view showing one example of the structure of the electrophotographic apparatus according to the present invention. As illustrated, an electrophotographic apparatus 60 is equipped with a photoreceptor 7 according to one embodiment of the present invention, which comprises: a conductive substrate 1; and an undercoat layer 2 and a photosensitive layer 300, which cover the outer periphery of the conductive substrate 1. This electrophotographic apparatus 60 comprises: a charging member 21 which is arranged on the outer periphery of the photoreceptor 7 and has a roller shape in the example shown in the drawing; a high-voltage power source 22 which supplies applied voltage to the charging member 21; an image exposure member 23; a developer 24 which is equipped with a development roller 241; a paper-feeding member 25 which is equipped with a paper-feeding roller 251 and a paper feed guide 252; and a transfer charger (direct charging-type) 26. The electrophotographic apparatus 60 may further comprise a cleaning device 27 equipped with a cleaning blade 271, and a charge-removing member 28. The electrophotographic apparatus 60 according to one embodiment of the present invention can be configured as a color printer.

EXAMPLES

(51) Concrete embodiments of the present invention will now be described in more detail by way of examples thereof.

(52) The present invention, however, is not restricted to the following Examples as long as they do not deviate from the gist of the present invention.

(53) Laminate-Type Photoreceptor

Example 1

(54) As a conductive substrate, a 0.75 mm-thick aluminum tube machined to have a size of 30 mm252.6 mm (length) and a surface roughness (Rmax) of 0.2 m was used.

(55) Charge Transport Layer

(56) After dissolving 100 parts by mass of a compound represented by Formula (H-5) below as a hole transporting material and 100 parts by mass of a polycarbonate resin (viscosity-average molecular weight: 50,000) represented by Formula (BD-1) below as a resin binder in 800 parts by mass of tetrahydrofuran, 0.1 parts by mass of a silicone oil (KP-340, manufactured by Shin-Etsu Polymer Co., Ltd.) was added to prepare a coating solution. This coating solution was coated on the above-described conductive substrate, and the resultant was dried at 100 C. for 30 minutes, whereby a 15 m-thick charge transport layer was formed.

(57) ##STR00188##

(58) Charge Generation Layer

(59) After dissolving 7.0 parts by mass of the compound represented by the Formula (H-5) as a hole transporting material, 3 parts by mass of a compound represented by Formula (E-2) below as an electron transporting material, 9.6 parts by mass of the polycarbonate resin having a repeating unit represented by the Formula (BD-1) as a resin binder, 0.04 parts by mass of a silicone oil (KF-54, manufactured by Shin-Etsu Polymer Co., Ltd.) and 0.1 parts by mass of dibutylhydroxytoluene (BHT) in 80 parts by mass of tetrahydrofuran, 0.3 parts by mass of a Y-type titanyl phthalocyanine (CG-1) was added thereto as a charge generating substance, and the resultant was subsequently subjected to a dispersion treatment using a sand grind mill to prepare a coating solution. This coating solution was coated on the above-formed charge transport layer, and the resultant was dried at 110 C. for 30 minutes to form a 15 m-thick charge generation layer, whereby a 30 m-thick laminate-type electrophotographic photoreceptor was obtained.

(60) ##STR00189##

Example 2

(61) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the compound represented by the Formula (H-5) that was used in Example 1 was changed to the compound represented by the Formula (H-1).

Example 3

(62) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the compound represented by the Formula (H-5) that was used in Example 1 was changed to the compound represented by the Formula (H-20).

Example 4

(63) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the compound represented by the Formula (H-5) that was used in Example 1 was changed to the compound represented by the Formula (H-14).

Example 5

(64) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the compound represented by the Formula (H-5) that was used in Example 1 was changed to the compound represented by the Formula (H-27).

Example 6

(65) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the compound represented by the Formula (E-2) that was used in Example 1 was changed to a compound represented by the following Formula (E-5).

(66) ##STR00190##

Example 7

(67) An electrophotographic photoreceptor was produced in the same manner as in Example 2, except that the compound represented by the Formula (E-2) that was used in Example 2 was changed to the compound represented by the Formula (E-5).

Example 8

(68) An electrophotographic photoreceptor was produced in the same manner as in Example 3, except that the compound represented by the Formula (E-2) that was used in Example 3 was changed to the compound represented by the Formula (E-5).

Example 9

(69) An electrophotographic photoreceptor was produced in the same manner as in Example 4, except that the compound represented by the Formula (E-2) that was used in Example 4 was changed to the compound represented by the Formula (E-5).

Example 10

(70) An electrophotographic photoreceptor was produced in the same manner as in Example 5, except that the compound represented by the Formula (E-2) that was used in Example 5 was changed to the compound represented by the Formula (E-5).

Example 11

(71) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the compound represented by the Formula (E-2) that was used in Example 1 was changed to a compound represented by the following Formula (E-11).

(72) ##STR00191##

Example 12

(73) An electrophotographic photoreceptor was produced in the same manner as in Example 2, except that the compound represented by the Formula (E-2) that was used in Example 2 was changed to the compound represented by the Formula (E-11).

Example 13

(74) An electrophotographic photoreceptor was produced in the same manner as in Example 3, except that the compound represented by the Formula (E-2) that was used in Example 3 was changed to the compound represented by the Formula (E-11).

Example 14

(75) An electrophotographic photoreceptor was produced in the same manner as in Example 4, except that the compound represented by the Formula (E-2) that was used in Example 4 was changed to the compound represented by the Formula (E-11).

Example 15

(76) An electrophotographic photoreceptor was produced in the same manner as in Example 5, except that the compound represented by the Formula (E-2) that was used in Example 5 was changed to the compound represented by the Formula (E-11).

Example 16

(77) An electrophotographic photoreceptor was produced in the same manner as in Example 6, except that the charge transporting material used in Example 6 was changed to the X-type metal-free phthalocyanine (CG-2) described in Japanese Unexamined Patent Application Publication No. 2001-228637.

Example 17

(78) An electrophotographic photoreceptor was produced in the same manner as in Example 6, except that the charge transporting material used in Example 6 was changed to a hydroxygallium phthalocyanine (CG-3).

Example 18

(79) An electrophotographic photoreceptor was produced in the same manner as in Example 6, except that the resin represented by the Formula (BD-1) that was used in the charge generation layer of Example 6 was changed to a resin represented by the following Formula (BD-2).

(80) ##STR00192##

Example 19

(81) An electrophotographic photoreceptor was produced in the same manner as in Example 6, except that the resin represented by the Formula (BD-1) that was used in the charge generation layer of Example 6 was changed to a compound represented by the following Formula (BD-3).

(82) ##STR00193##

Example 20

(83) An electrophotographic photoreceptor was produced in the same manner as in Example 6, except that the resin represented by the Formula (BD-1) that was used in the charge generation layer of Example 6 was changed to a compound represented by the following Formula (BD-4).

(84) ##STR00194##

Example 21

(85) An electrophotographic photoreceptor was produced in the same manner as in Example 6, except that the resin represented by the Formula (BD-1) that was used in the charge generation layer of Example 6 was changed to a compound represented by the following Formula (BD-5).

(86) ##STR00195##

Example 22

(87) An electrophotographic photoreceptor was produced in the same manner as in Example 6, except that the resin represented by the Formula (BD-1) that was used in the charge generation layer of Example 6 was changed to a compound represented by the following Formula (BD-6).

(88) ##STR00196##

Comparative Example 1

(89) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the compound represented by the Formula (E-2) that was used in Example 1 was changed to a compound represented by the following Formula (E-R1).

(90) ##STR00197##

Comparative Example 2

(91) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the compound represented by the Formula (E-2) that was used in Example 1 was changed to a compound represented by the following Formula (E-R2).

(92) ##STR00198##

(93) Single Layer-Type Photoreceptor

Example 23

(94) As a conductive substrate, a 0.75 mm-thick aluminum tube machined to have a size of 30 mm244.5 mm (length) and a surface roughness (Rmax) of 0.2 m was used.

(95) After dissolving 7.0 parts by mass of the compound represented by the Formula (H-5) as a hole transporting material, 3 parts by mass of the compound represented by the Formula (E-2) as an electron transporting substance, 9.6 parts by mass of the polycarbonate resin (viscosity-average molecular weight: 50,000) having a repeating unit represented by the Formula (BD-1) as a resin binder, 0.04 parts by mass of a silicone oil (KF-54, manufactured by Shin-Etsu Polymer Co., Ltd.) and 0.1 parts by mass of dibutylhydroxytoluene (BHT) in 80 parts by mass of tetrahydrofuran, 0.3 parts by mass of the X-type metal-free phthalocyanine (CG-2) described in Example 16 was added thereto as a charge generating substance, and the resultant was subsequently subjected to a dispersion treatment using a sand grind mill to prepare a coating solution. This coating solution was coated on the above-described conductive substrate, and the resultant was dried at 100 C. for 60 minutes to form a single layer-type photosensitive layer having a thickness of about 25 m, whereby a positively-chargeable single layer-type electrophotographic photoreceptor was obtained.

Example 24

(96) An electrophotographic photoreceptor was produced in the same manner as in Example 23, except that the compound represented by the Formula (H-5) that was used in Example 23 was changed to the compound represented by the Formula (H-1).

Example 25

(97) An electrophotographic photoreceptor was produced in the same manner as in Example 23, except that the compound represented by the Formula (H-5) that was used in Example 23 was changed to the compound represented by the Formula (H-20).

Example 26

(98) An electrophotographic photoreceptor was produced in the same manner as in Example 23, except that the compound represented by the Formula (H-5) that was used in Example 23 was changed to the compound represented by the Formula (H-14).

Example 27

(99) An electrophotographic photoreceptor was produced in the same manner as in Example 23, except that the compound represented by the Formula (H-5) that was used in Example 23 was changed to the compound represented by the Formula (H-27).

Example 28

(100) An electrophotographic photoreceptor was produced in the same manner as in Example 23, except that the compound represented by the Formula (E-2) that was used in Example 23 was changed to the compound represented by the Formula (E-5).

Example 29

(101) An electrophotographic photoreceptor was produced in the same manner as in Example 28, except that the compound represented by the Formula (H-5) that was used in Example 28 was changed to the compound represented by the Formula (H-1).

Example 30

(102) An electrophotographic photoreceptor was produced in the same manner as in Example 28, except that the compound represented by the Formula (H-5) that was used in Example 28 was changed to the compound represented by the Formula (H-20).

Example 31

(103) An electrophotographic photoreceptor was produced in the same manner as in Example 28, except that the compound represented by the Formula (H-5) that was used in Example 28 was changed to the compound represented by the Formula (H-14).

Example 32

(104) An electrophotographic photoreceptor was produced in the same manner as in Example 28, except that the compound represented by the Formula (H-5) that was used in Example 28 was changed to the compound represented by the Formula (H-27).

Example 33

(105) An electrophotographic photoreceptor was produced in the same manner as in Example 23, except that the compound represented by the Formula (E-2) that was used in Example 23 was changed to the compound represented by the Formula (E-11).

Example 34

(106) An electrophotographic photoreceptor was produced in the same manner as in Example 33, except that the compound represented by the Formula (H-5) that was used in Example 33 was changed to the compound represented by the Formula (H-1).

Example 35

(107) An electrophotographic photoreceptor was produced in the same manner as in Example 33, except that the compound represented by the Formula (H-5) that was used in Example 33 was changed to the compound represented by the Formula (H-20).

Example 36

(108) An electrophotographic photoreceptor was produced in the same manner as in Example 33, except that the compound represented by the Formula (H-5) that was used in Example 33 was changed to the compound represented by the Formula (H-14).

Example 37

(109) An electrophotographic photoreceptor was produced in the same manner as in Example 33, except that the compound represented by the Formula (H-5) that was used in Example 33 was changed to the compound represented by the Formula (H-27).

Comparative Example 3

(110) An electrophotographic photoreceptor was produced in the same manner as in Example 23, except that the compound represented by the Formula (E-2) that was used in Example 23 was changed to the compound represented by the Formula (E-R1).

Comparative Example 4

(111) An electrophotographic photoreceptor was produced in the same manner as in Example 23, except that the compound represented by the Formula (E-2) that was used in Example 23 was changed to the compound represented by the Formula (E-R2).

(112) Evaluation of Photoreceptors

(113) Fatigue Property (Electrical Property)

(114) For the photoreceptors of Examples 1 to 22 and Comparative Examples 1 and 2, each photoreceptor was integrated into a commercially available 26-ppm monochrome laser printer (HL-2240) manufactured by Brother Industries, Ltd., and 5,000 prints of an image having a print area ratio of 4% were made at 10-second intervals under a low-temperature low-humidity environment of 10 C. and 20% RH, followed by measurement of the change in potential of the developing part.

(115) For the photoreceptors of Examples 23 to 37 and Comparative Examples 3 and 4, each photoreceptor was integrated into a commercially available 16-ppm color LED printer (HL-3040) manufactured by Brother Industries, Ltd., and 5,000 prints of an image having a print area ratio of 4% were made at 10-second intervals under a low-temperature low-humidity environment of 10 C. and 20% RH, followed by measurement of the change in potential of the developing part of each black-toner photoreceptor.

(116) The results of these evaluations are shown in Tables 13 and 14 below.

(117) TABLE-US-00013 TABLE 13 Charge generation layer or single layer-type photosensitive layer material Property Electron Charge Hole Change in Photorecept transporting generating transporting environmental or layer material material material Resin potential structure Compound Compound Compound Compound (V) Example 1 laminated E-2 CG-1 H-5 BD-1 17 Example 2 laminated E-2 CG-1 H-1 BD-1 20 Example 3 laminated E-2 CG-1 H-20 BD-1 19 Example 4 laminated E-2 CG-1 H-14 BD-1 18 Example 5 laminated E-2 CG-1 H-27 BD-1 23 Example 6 laminated E-5 CG-1 H-5 BD-1 14 Example 7 laminated E-5 CG-1 H-1 BD-1 15 Example 8 laminated E-5 CG-1 H-20 BD-1 17 Example 9 laminated E-5 CG-1 H-14 BD-1 15 Example 10 laminated E-5 CG-1 H-27 BD-1 18 Example 11 laminated E-11 CG-1 H-5 BD-1 18 Example 12 laminated E-11 CG-1 H-1 BD-1 21 Example 13 laminated E-11 CG-1 H-20 BD-1 20 Example 14 laminated E-11 CG-1 H-14 BD-1 21 Example 15 laminated E-11 CG-1 H-27 BD-1 22 Example 16 laminated E-5 CG-2 H-5 BD-1 22 Example 17 laminated E-5 CG-3 H-5 BD-1 18 Example 18 laminated E-5 CG-1 H-5 BD-2 14 Example 19 laminated E-5 CG-1 H-5 BD-3 16 Example 20 laminated E-5 CG-1 H-5 BD-4 17 Example 21 laminated E-5 CG-1 H-5 BD-5 14 Example 22 laminated E-5 CG-1 H-5 BD-6 15

(118) TABLE-US-00014 TABLE 14 Charge generation layer or single layer-type photosensitive layer material Property Electron Charge Hole Change in Photorecept transporting generating transporting environmental or layer material material material Resin potential structure Compound Compound Compound Compound (V) Example 23 single layer E-2 CG-2 H-5 BD-1 20 Example 24 single layer E-2 CG-2 H-1 BD-1 22 Example 25 single layer E-2 CG-2 H-20 BD-1 21 Example 26 single layer E-2 CG-2 H-14 BD-1 20 Example 27 single layer E-2 CG-2 H-27 BD-1 25 Example 28 single layer E-5 CG-2 H-5 BD-1 16 Example 29 single layer E-5 CG-2 H-1 BD-1 17 Example 30 single layer E-5 CG-2 H-20 BD-1 19 Example 31 single layer E-5 CG-2 H-14 BD-1 18 Example 32 single layer E-5 CG-2 H-27 BD-1 19 Example 33 single layer E-11 CG-2 H-5 BD-1 22 Example 34 single layer E-11 CG-2 H-1 BD-1 21 Example 35 single layer E-11 CG-2 H-20 BD-1 24 Example 36 single layer E-11 CG-2 H-14 BD-1 24 Example 37 single layer E-11 CG-2 H-27 BD-1 25 Comparative laminated E-R1 CG-1 H-5 BD-1 44 Example 1 Comparative laminated E-R2 CG-1 H-5 BD-1 40 Example 2 Comparative single layer E-R1 CG-2 H-5 BD-1 54 Example 3 Comparative single layer E-R2 CG-2 H-5 BD-1 46 Example 4

(119) As apparent from the above Tables, it was confirmed that, in the photoreceptors of Examples in which a specific combination of a charge generating material and an electron transporting material was used in each photosensitive layer, the potential fluctuation in a low-temperature environment was suppressed as compared to the photoreceptors of Comparative Examples in which different combinations were used.