Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

The invention provides an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. The electrophotographic photoreceptor includes: a conductive substrate; an undercoat layer that is provided on the conductive substrate and contains a binder resin and an electron-transporting material represented by general formula (P); and a photosensitive layer provided on the undercoat layer, in which R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. [Chemical Formula 1] # imgabs0 #

Description

Technical Field

[0001] The present invention relates to an electronic photographic photosensitive body, a processing box and an image forming device Background Art

[0002] In an image forming apparatus using an electrophotographic method, the surface of an electrophotographic photoreceptor is usually charged to a predetermined polarity and potential by a charging member, and the charged surface of the electrophotographic photoreceptor is selectively destaticized by image exposure, thereby forming an electrostatic latent image. Then, a toner is attached to the electrostatic latent image by a developing member, and the latent image is developed into a toner image. Then, the toner image is transferred to a transfer medium by a transfer member, and the image formation is discharged. In recent years, electrophotographic photoreceptors have the advantages of achieving high speed and high printing quality, and are therefore widely used in the fields of copiers and laser printers.

[0003] At present, in most cases, an electrophotographic photosensitive body forms an undercoat layer on a conductive support layer such as an aluminum substrate, and a single-layer photosensitive layer containing a charge generating agent and a charge transporting agent in the same layer or a so-called functionally separated photosensitive layer stacked with a charge generating layer containing a charge generating agent and a charge transporting layer containing a charge transporting agent is sequentially formed on the undercoat layer.

[0004] The undercoat layer is required to conceal defects of the substrate, suppress charge injection into the photosensitive layer when voltage is applied to the electrophotographic photoreceptor, and control resistance. On the other hand, the undercoat layer is also required to suppress the charge generated in the photosensitive layer from being retained inside the photoreceptor, that is, to have charge transport properties.

[0005] Patent document 1 discloses an electronic photographic photoreceptor, characterized in that it has a conductive support layer, a photosensitive layer containing a pigment, and an intermediate layer arranged between the conductive support layer and the photosensitive layer, the intermediate layer contains zinc oxide particles and a binder resin, the maximum primary particle size of the zinc oxide particles contained in the intermediate layer is less than 300nm, and the average particle size is 20 to 200nm, and the layer thickness of the intermediate layer is 15 to 50μm.

[0006] Patent document 2 discloses an electronic photographic photoreceptor comprising a conductive support layer, a photosensitive layer containing a pigment, and an intermediate layer arranged between the conductive support layer and the photosensitive layer. The electronic photographic photoreceptor is characterized in that the intermediate layer comprises metal oxide particles and a binder resin coated with a coupling agent, the thickness of the intermediate layer is greater than 20 μm and less than 50 μm, and the binder resin is a thermosetting resin.

[0007] Patent Document 3 discloses an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer in this order on a support, wherein the intermediate layer contains a polymer of an electron transporting substance having a non-hydrolyzable polymerizable functional group.

[0008] Patent Document 4 discloses an electrophotographic photoreceptor including an intermediate layer and a photosensitive layer in this order on a support, wherein the intermediate layer contains a specific resin.

[0009] Patent Document 5 discloses an asymmetric imide compound having two substituents having different structures.

[0010] Patent document 6 discloses a method for manufacturing an electrophotographic photosensitive body, which comprises: step (i), forming an intermediate layer on a conductive support using an intermediate layer coating containing polynaphthalene diimide particles; and step (ii), forming a photosensitive layer on the intermediate layer. In the method for manufacturing an electrophotographic photosensitive body, the polynaphthalene diimide particles are polynaphthalene diimide particles having repeating units containing a naphthalene diimide structure represented by the following general formula (2).

[0011] Patent document 7 discloses an electronic photographic photoreceptor, which is formed by sequentially arranging an intermediate layer and a photosensitive layer on a conductive support. The electronic photographic photoreceptor is characterized in that the intermediate layer contains a polyolefin resin and an organic electron transport substance, the polyolefin resin is a specific polyolefin resin, and the organic electron transport substance is a compound selected from the group consisting of imide compounds, benzimidazole compounds, quinone compounds, cyclopentadienyl compounds, azo compounds and their derivatives.

[0012] Patent document 8 discloses an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer on a support in this order, and the photosensitive layer contains a charge generating substance and a charge transporting substance. The electrophotographic photoreceptor is characterized in that, in an electrophotographic photoreceptor in which an electrostatic latent image is formed on the surface by a semiconductor laser, the intermediate layer contains a specific electron transporting substance, and the volume resistivity of the intermediate layer under an environment of 30°C and 80% RH is 1×10 12 Ω·cm or more, and a value (Rz / λ) of the ratio of the ten-point average roughness (Rz) of the surface of the support on the photosensitive layer side to the wavelength (λ) of the semiconductor laser is 0.6 or more and 2.5 or less.

[0013] Patent Document 1: Japanese Patent No. 3991638

[0014] Patent Document 2: Japanese Patent Application Publication No. 2003-091086

[0015] Patent Document 3: Japanese Patent Application Publication No. 2003-330209

[0016] Patent Document 4: Japanese Patent Application Publication No. 2003-345044

[0017] Patent Document 5: Japanese Patent No. 5147274

[0018] Patent Document 6: Japanese Patent No. 4411232

[0019] Patent Document 7: Japanese Patent Application Publication No. 2011-095665

[0020] Patent Document 8: Japanese Patent No. 3958154 Summary of the invention

[0021] There is a known method for adjusting the charge retention property of an existing electrophotographic photoreceptor having a conductive substrate, an undercoat layer, and a photosensitive layer by using an undercoat layer containing a binder resin and an electron transport material (for example, the following electron transport material (A), (B), or (C) can be cited). However, there is a demand for developing an electrophotographic photoreceptor having a better charge retention property.

[0022] The present invention aims to provide an electrophotographic photoreceptor having excellent charge retention properties compared to an electrophotographic photoreceptor using an undercoat layer containing a binder resin and a conventional electron transporting material (for example, the electron transporting material (A), (B) or (C) described below).

[0023] [Chemical formula 1]

[0024]

[0025] Specific means for solving the above-mentioned problems include the following aspects.

[0026] <1> An electrophotographic photoreceptor comprising:

[0027] Conductive substrate;

[0028] an undercoat layer disposed on the conductive substrate and containing a binder resin and an electron transport material represented by the following general formula (P); and

[0029] The photosensitive layer is disposed on the lower coating layer.

[0030] [Chemical formula 2]

[0031]

[0032] In the above general formula (P), R 1 , R 2 , R 3, R 4 , R 5 , R 6 , R 7 and R 8 Each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group or a halogen atom.

[0033] <2> according to <1> The electrophotographic photoreceptor, wherein

[0034] In the general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Each independently represents a hydrogen atom or a halogen atom.

[0035] <3> according to <1> or <2> The electrophotographic photoreceptor, wherein

[0036] In the general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Represents a hydrogen atom.

[0037] <4> according to <1> to <3> The electrophotographic photoreceptor according to any one of the preceding claims, wherein

[0038] The electron transport material has an average primary particle size of 1 μm or less.

[0039] <5> according to <4> The electrophotographic photoreceptor, wherein

[0040] The electron transport material has an average primary particle size of 0.03 μm or more and 1 μm or less.

[0041] <6> according to <1> to <5> The electrophotographic photoreceptor according to any one of the preceding claims, wherein

[0042] The content of the electron transport material is less than 70 mass % based on the total solid content of the undercoat layer.

[0043] <7> according to <1> to <6> The electrophotographic photoreceptor according to any one of the preceding claims, wherein

[0044] The undercoat layer has a thickness of 5 μm or more and 15 μm or less.

[0045] <8> according to <1> to <7> The electrophotographic photoreceptor according to any one of the preceding claims, wherein

[0046] The bonding resin is a thermosetting resin.

[0047] <9> according to <8> The electrophotographic photoreceptor, wherein

[0048] The thermosetting resin includes at least one resin selected from the group consisting of urethane resin, melamine resin, and benzoguanamine resin.

[0049] <10> according to <1> The electrophotographic photoreceptor, wherein

[0050] The content of the metal oxide in the undercoat layer is 5% by mass or less based on the total solid content of the undercoat layer.

[0051] <11> A processing box having <1> to <10> The electrophotographic photoreceptor according to any one of the preceding claims, wherein

[0052] The process cartridge is attachable to and detachable from the image forming apparatus.

[0053] <12> An image forming device comprising:

[0054] <1> to <10> The electrophotographic photoreceptor described in any one of the above;

[0055] A charging device for charging the surface of the electrophotographic photoreceptor;

[0056] An electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0057] a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and

[0058] The transfer device transfers the toner image to the surface of a recording medium.

[0059] Effects of the Invention

[0060] according to <1> , <2> Or the invention according to <3> provides an electrophotographic photoreceptor having excellent charge retention properties compared to the case of using an undercoat layer containing a binder resin and a conventional electron transporting material (for example, the aforementioned electron transporting material (A), (B) or (C)).

[0061] according to <4> The present invention provides an electrophotographic photoreceptor having excellent charge retention performance compared to a case where the average primary particle size of the electron transport material exceeds 1 μm.

[0062] according to <5> The present invention provides an electrophotographic photoreceptor having excellent film-forming properties and charge retention properties compared to a case where the average primary particle size of the electron transport material is less than 0.03 μm or exceeds 1 μm.

[0063] according to <6> The present invention provides an electrophotographic photoreceptor having excellent film-forming properties and charge retention properties compared to a case where the content of the electron transport material is 70% by mass or more based on the total solid content of the undercoat layer.

[0064] according to <7> The present invention provides an electrophotographic photoreceptor having excellent charge retention performance compared with a case where the thickness of the undercoat layer is less than 5 μm or exceeds 15 μm.

[0065] according to <8> The present invention provides an electrophotographic photoreceptor having excellent charge retention performance compared to a case where the binder resin is a thermoplastic resin.

[0066] according to <9> The present invention provides an electrophotographic photoreceptor having excellent charge retention performance compared to the case where the thermosetting resin is nylon polyamide.

[0067] according to <10> The present invention provides an electrophotographic photoreceptor having excellent charge retention performance compared with a case where the content of the metal oxide in the undercoat layer exceeds 5% by mass based on the total solid content of the undercoat layer.

[0068] according to <11> or <12> The invention involved provides a processing box or image forming device having an electrophotographic photosensitive body with excellent charge retention compared to a processing box or image forming device having an electrophotographic photosensitive body with an undercoat layer containing a binding resin and an existing electron transporting material (for example, the aforementioned electron transporting material (A), (B) or (C), etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0070] Figure 1 is a schematic partial cross-sectional view showing an example of a layer structure of an electrophotographic photoreceptor according to the present embodiment;

[0071] Figure 2 is a schematic structural diagram showing an example of an image forming apparatus according to the present embodiment;

[0072] Figure 3 It is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

[0073] Explanation of symbols

[0074] 1-undercoat layer, 2-charge generating layer, 3-charge transporting layer, 4-conductive substrate, 5-photosensitive layer, 7A-photoreceptor, 7-electrophotographic photoreceptor, 8-charging device, 9-exposure device, 11-developing device, 13-cleaning device, 14-lubricant, 40-transfer device, 50-intermediate transfer body, 100-image forming device, 120-image forming device, 131-cleaning blade, 132-fibrous component (roller-shaped), 133-fibrous component (flat brush-shaped), 300-processing box. DETAILED DESCRIPTION

[0075] Hereinafter, embodiments of the present invention will be described. These descriptions and examples are intended to illustrate the embodiments and do not limit the scope of the embodiments.

[0076] In the present specification, a numerical range expressed using "to" indicates a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0077] In the numerical ranges recorded in stages in the present invention, the upper limit or lower limit recorded in one numerical range may also be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical ranges recorded in the present invention, the upper limit or lower limit of the numerical range may also be replaced by the value shown in the embodiment.

[0078] In the present invention, each component may also include a plurality of corresponding substances. In the present invention, when referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it indicates the total amount of the plurality of substances present in the composition.

[0079] In the present invention, the electrophotographic photoreceptor is also simply referred to as a photoreceptor.

[0080] <Electrophotographic Photoreceptor>

[0081] The electrophotographic photoreceptor according to the present embodiment includes a conductive substrate, an undercoat layer provided on the conductive substrate and containing a binder resin and an electron transport material represented by the following general formula (P), and a photosensitive layer provided on the undercoat layer.

[0082] [Chemical formula 3]

[0083]

[0084] In the above general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R8 Each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group or a halogen atom.

[0085] The photoreceptor according to the present embodiment includes a conductive substrate, an undercoat layer disposed on the conductive substrate, and a photosensitive layer disposed on the undercoat layer.

[0086] Figure 1 An example of the layer structure of the photoreceptor according to the present embodiment is schematically shown. Figure 1 The photoreceptor 7A shown has a structure in which an undercoat layer 1, a charge generating layer 2, and a charge transporting layer 3 are sequentially stacked on a conductive substrate 4. The charge generating layer 2 and the charge transporting layer 3 constitute a photosensitive layer 5. The photoreceptor 7A may have a layer structure in which a protective layer is further provided on the charge transporting layer 3.

[0087] In the photoreceptor according to this embodiment, Figure 1 The photosensitive layer of the photoreceptor 7A shown may be a functional separation type photosensitive layer in which the charge generating layer 2 and the charge transporting layer 3 are separated, or may be a single layer photosensitive layer having charge generating capability and charge transporting capability instead of the charge generating layer 2 and the charge transporting layer 3 .

[0088] The electrophotographic photoreceptor according to the present embodiment has an undercoat layer containing a binder resin and an electron transport material represented by the above general formula (P).

[0089] In order to make the charge maintenance of the electrophotographic photoreceptor excellent, it is required to improve the electron transportability in the lower coating layer and reduce the hole transportability. As existing electron transport materials, for example, the aforementioned electron transport materials (A), (B) and (C) are used, but these have high properties of transmitting electrons, but have the property of slightly moving holes, so when a voltage is applied to the electrophotographic photoreceptor, the holes move in the lower coating layer, thereby generating charge injection into the photosensitive layer. As a result, the hole blocking property is insufficient, the dark decay becomes larger, and there is a tendency for the charge maintenance to decrease.

[0090] On the other hand, the electrophotographic photoreceptor involved in the present embodiment contains an electron transport material represented by the general formula (P) in addition to the binder resin in the lower coating layer. As a result of in-depth research by the present inventors, it was found that the electron transport material represented by the general formula (P) is the so-called perylene tetracarboxylic dianhydride, which is an electron transport material matched in the lower coating layer and has the properties of excellent electron transport and low hole transport. In this way, it is believed that the electrophotographic photoreceptor involved in the present embodiment has excellent charge maintenance due to the excellent electron transport of the lower coating layer and the reduced dark decay.

[0091] Hereinafter, each layer of the photoreceptor according to the present embodiment will be described in detail.

[0092] [Undercoat]

[0093] The undercoat layer contains a binder resin and an electron transport material represented by the following general formula (P).

[0094] The undercoat layer may further contain other materials in addition to the binder resin and the electron transport material represented by the following general formula (P).

[0095] [Chemical formula 4]

[0096]

[0097] In the above general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group or a halogen atom.

[0098] The electron transport material represented by the general formula (P) has excellent electron transport properties and low hole transport properties. Therefore, it is believed that if the undercoat layer contains the electron transport material represented by the general formula (P), the undercoat layer has excellent electron transport properties and reduces dark decay, so the charge retention is excellent.

[0099] In the general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 For example, each independently preferably represents a hydrogen atom or a halogen atom, and more preferably represents a hydrogen atom.

[0100] It is believed that when R in the general formula (P) 1 ~R 8 When it is a hydrogen atom or a halogen atom (for example, a hydrogen atom is more preferable), the electron transport property of the undercoat layer is more excellent, and the dark decay is further reduced, so the charge retention property is more excellent.

[0101] As R in the general formula (P) 1 ~R 8 The alkyl group represented by may be a substituted or unsubstituted alkyl group.

[0102] As R in the general formula (P) 1 ~R 8The unsubstituted alkyl group represented by the present invention includes a straight-chain alkyl group having 1 to 20 carbon atoms (for example, preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), a branched alkyl group having 3 to 20 carbon atoms (for example, preferably 3 to 10 carbon atoms), and a cyclic alkyl group having 3 to 20 carbon atoms (for example, preferably 3 to 10 carbon atoms).

[0103] Examples of the straight-chain alkyl group having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, tridecyl, n-tetradecyl, n-pentadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosyl.

[0104] Examples of the branched alkyl group having 3 to 20 carbon atoms include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, tert-decyl, isododecyl, sec-dodecyl, tert-dodecyl, tert-tetradecyl, and tert-pentadecyl.

[0105] Examples of the cyclic alkyl group having 3 to 20 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups in which these monocyclic alkyl groups are linked.

[0106] Among the above, the unsubstituted alkyl group is preferably a linear alkyl group such as a methyl group or an ethyl group.

[0107] Examples of the substituent in the alkyl group include an alkoxy group, a hydroxyl group, a carboxyl group, a nitro group, and a halogen atom (a fluorine atom, a bromine atom, an iodine atom, etc.).

[0108] Examples of the alkoxy group substituting the hydrogen atom in the alkyl group include: 1 ~R 8 The same groups as the unsubstituted alkoxy groups represented.

[0109] As R in the general formula (P) 1 ~R 8 The alkoxy group represented by may be a substituted or unsubstituted alkoxy group.

[0110] As R in the general formula (P) 1 ~R 8Examples of the unsubstituted alkoxy group represented by the above include linear, branched or cyclic alkoxy groups having 1 to 10 carbon atoms (for example, preferably 1 to 6, more preferably 1 to 4).

[0111] Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, and an n-decyloxy group.

[0112] Specifically, examples of the branched alkoxy group include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy, tert-hexyloxy, isoheptyloxy, sec-heptyloxy, tert-heptyloxy, isooctyloxy, sec-octyloxy, tert-octyloxy, isononyloxy, sec-nonyloxy, tert-nonyloxy, isodecyloxy, sec-decyloxy, and tert-decyloxy.

[0113] Specific examples of the cyclic alkoxy group include a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, a cyclohexyloxy group, a cycloheptyloxy group, a cyclooctyloxy group, a cyclononyloxy group, and a cyclodecyloxy group.

[0114] Among them, as the unsubstituted alkoxy group, for example, a linear alkoxy group is preferred.

[0115] Examples of the substituent in the alkoxy group include an aryl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a hydroxyl group, a carboxyl group, a nitro group, and a halogen atom (such as a fluorine atom, a bromine atom, and an iodine atom).

[0116] Examples of the aryl group that replaces the hydrogen atom in the alkoxy group include the following: 1 ~R 8 The same groups as those represented by the unsubstituted aryl groups.

[0117] Examples of the alkoxycarbonyl group that replaces the hydrogen atom in the alkoxy group include the following: 1 ~R 8 The same groups as the unsubstituted alkoxycarbonyl groups represented.

[0118] Examples of the aryloxycarbonyl group that replaces the hydrogen atom in the alkoxy group include the following: 1 ~R 8 The same groups as the unsubstituted aryloxycarbonyl groups represented.

[0119] As R in the general formula (P) 1 ~R 8 The aralkyl group represented by may be a substituted or unsubstituted aralkyl group.

[0120] As R in the general formula (P) 1 ~R 8The unsubstituted aralkyl group represented is, for example, preferably an aralkyl group having 7 to 30 carbon atoms, more preferably an aralkyl group having 7 to 16 carbon atoms, and still more preferably an aralkyl group having 7 to 12 carbon atoms.

[0121] Examples of the unsubstituted aralkyl group having 7 to 30 carbon atoms include benzyl, phenylethyl, phenylpropyl, 4-phenylbutyl, phenylpentyl, phenylhexyl, phenylheptyl, phenyloctyl, phenylnonyl, naphthylmethyl, naphthylethyl, anthracenylmethyl, and phenyl-cyclopentylmethyl.

[0122] Examples of the substituent in the aralkyl group include an alkoxy group, an alkoxycarbonyl group, and a halogen atom (a fluorine atom, a bromine atom, an iodine atom, etc.).

[0123] Examples of the alkoxy group substituting the hydrogen atom in the aralkyl group include the following: 1 ~R 8 The same groups as the unsubstituted alkoxy groups represented.

[0124] Examples of the alkoxycarbonyl group that replaces the hydrogen atom in the aralkyl group include the following: 1 ~R 8 The same groups as the unsubstituted alkoxycarbonyl groups represented.

[0125] As R in the general formula (P) 1 ~R 8 The aryl group represented by may be a substituted or unsubstituted aryl group.

[0126] As R in the general formula (P) 1 ~R 8 The unsubstituted aryl group represented by is, for example, preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and further preferably an aryl group having 6 to 10 carbon atoms.

[0127] Examples of the aryl group having 6 to 30 carbon atoms include phenyl, biphenyl, 1-naphthyl, 2-naphthyl, 9-anthryl, 9-phenanthrenyl, 1-pyrenyl, 5-naphthyl, 1-indenyl, 2-azulyl, 9-fluorenyl, biphenylene, indaceny1, fluoranthenyl, acenaphthenyl, acenaphthene, phenanthrenyl, fluorenyl, anthracene, anthracene, quaternary anthracene, anthraquinolyl, phenanthrenyl, triphenylene, pyrenyl, chrysenyl, naphthyl, pleiadenyl, picenyl, peryl, pentaphenyl, pentacene, tetraphenylene, hexaphenyl, hexacenyl, ruthenyl, and coronenyl. Among the above, for example, phenyl is preferred.

[0128] Examples of the substituent in the aryl group include an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a halogen atom (a fluorine atom, a bromine atom, an iodine atom, etc.).

[0129] Examples of the alkyl group that replaces the hydrogen atom in the aryl group include the following: 1 ~R 8 The same groups as the unsubstituted alkyl groups represented.

[0130] Examples of the alkoxy group substituting the hydrogen atom in the aryl group include the following: 1 ~R 8 The same groups as the unsubstituted alkoxy groups represented.

[0131] Examples of the alkoxycarbonyl group substituting the hydrogen atom in the aryl group include the following: 1 ~R 8 The same groups as the unsubstituted alkoxycarbonyl groups represented.

[0132] As R in the general formula (P) 1 ~R 8 Examples of the alkoxycarbonyl group represented by include substituted or unsubstituted alkoxycarbonyl groups.

[0133] As R in the general formula (P) 1 ~R 8 The number of carbon atoms in the alkyl chain of the unsubstituted alkoxycarbonyl group represented is, for example, preferably 1 or more and 20 or less, more preferably 1 or more and 15 or less, and further preferably 1 or more and 10 or less.

[0134] Examples of the alkoxycarbonyl group having an alkyl chain with a carbon number of 1 to 20 include methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl, sec-butoxybutylcarbonyl, tert-butoxycarbonyl, pentyloxycarbonyl, hexyloxycarbonyl, heptyloxycarbonyl, octyloxycarbonyl, nonyloxy, decyloxycarbonyl, dodecyloxycarbonyl, tridecanyloxycarbonyl, tetradecanyloxycarbonyl, pentadecyloxycarbonyl, hexadecyloxycarbonyl, heptadecanyloxycarbonyl, hexadecyloxycarbonyl, heptadecanyloxycarbonyl, octadecyloxycarbonyl, and eicosyloxycarbonyl.

[0135] Examples of the substituent in the alkoxycarbonyl group include an aryl group, a hydroxyl group and a halogen atom (a fluorine atom, a bromine atom, an iodine atom, etc.).

[0136] Examples of the aryl group substituting the hydrogen atom in the alkoxycarbonyl group include the following: 1 ~R 8 The same groups as those represented by the unsubstituted aryl groups.

[0137] As R in the general formula (P) 1 ~R 8Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0138] Hereinafter, exemplary compounds of the electron transport material represented by the general formula (P) are shown, but the present embodiment is not limited thereto. In addition, the following exemplary compound numbers are denoted as exemplary compounds (P-numbers).

[0139] [Chemical formula 5]

[0140]

[0141] [Chemical formula 6]

[0142]

[0143] The electron transport material represented by the general formula (P) has an average primary particle size of, for example, preferably 1 μm or less, more preferably 0.03 μm to 1 μm, further preferably 0.03 μm to 0.8 μm, and particularly preferably 0.05 μm to 0.7 μm.

[0144] If the average primary particle size of the electron transport material represented by the general formula (P) is less than 1 μm, the electron transport material is difficult to localize in the lower coating layer and is likely to exist with high dispersion, so the electron transport property is more excellent and the hole transport property is more likely to be reduced. If the average primary particle size of the electron transport material is greater than 0.03 μm, the aggregation of the electron transport material is suppressed, and it is likely to exist with high dispersion in the lower coating layer, so the electron transport property is more excellent and the hole transport property is more likely to be reduced.

[0145] The average primary particle size of the electron transport material represented by the general formula (P) was determined as follows.

[0146] The laminated cross section in the thickness direction of the electrophotographic photoreceptor is observed by SEM (scanning electron microscope) at a magnification of 100,000 times to determine the electron transport material represented by the general formula (P). Then, the particle size of any 10 points of the electron transport material represented by the general formula (P) present as primary particles in the obtained SEM image is calculated. The arithmetic mean of the obtained particle sizes is set as the average primary particle size of the electron transport material.

[0147] The electron transport material represented by the general formula (P) has an aspect ratio of, for example, preferably 1.0 to 5, more preferably 1.1 to 3, and even more preferably 1.2 to 2.5.

[0148] If the aspect ratio of the electron transport material represented by the general formula (P) is 2.5 or less, the electron transport material is likely to exist with high dispersion in the lower coating layer, so the electron transport property is more excellent, and the hole transport property is more likely to become low. If the aspect ratio of the electron transport material is 1.0 or more and 5 or less, the electron transport material is likely to exist with high dispersion in the lower coating layer, so the electron transport property is more excellent, and the charge retention is maintained.

[0149] The aspect ratio of the electron transport material represented by the general formula (P) refers to the ratio of the length of the major axis of the electron transport material to the length of the minor axis of the electron transport material (length of the major axis / length of the minor axis).

[0150] The length of the electron transport material in the long axis direction represents the longest straight line distance when connecting one end of the electron transport material in the long axis direction to the other end. The length of the electron transport material in the short axis direction represents the longest straight line distance when connecting one end of the electron transport material in the direction orthogonal to the long axis to the other end.

[0151] The photosensitive layer is removed from the electrophotographic photoreceptor (and the protective layer is removed as needed), and the lower coating layer is observed at 3000 to 100000 times using a field emission scanning electron microscope (JEOL JSM-6700F) to determine the electron transport material represented by the general formula (P). The length of the major axis and the length of the minor axis of the electron transport material at any 10 points are measured from the obtained microscope photograph, and the aspect ratio (length of the major axis / length of the minor axis) is calculated respectively. The arithmetic mean of each aspect ratio is set as the aspect ratio of the electron transport material.

[0152] There is no particular limitation on the method for setting the average primary particle size and aspect ratio of the electron transport material represented by the general formula (P) within the above ranges, but examples thereof include a method of pulverizing using a ball mill, a bead mill, a mortar, a sand mill, a kneader, an attritor, or the like; a method of precipitating microcrystals by dissolving in fluoroacetic acid, sulfuric acid, or the like and then contacting with water or a poor solvent; and the like.

[0153] The undercoat layer may further contain an electron transporting material other than the electron transporting material represented by the general formula (P) within a range in which the effects of the present invention can be exerted.

[0154] The proportion of the electron transport material represented by the general formula (P) in the total amount of the electron transport material in the lower coating layer is, for example, preferably 80 mass % or more and 100 mass % or less, more preferably 90 mass % or more and 100 mass % or less, and further preferably 95 mass % or more and 100 mass % or less.

[0155] The content of the electron transport material represented by the general formula (P) is, for example, preferably less than 70 mass %, more preferably 45 mass % or more and less than 60 mass %, further preferably 50 mass % or more and less than 60 mass % relative to the total solid content of the undercoat layer.

[0156] In the past, it was believed that from the perspective of ensuring both electron mobility and charge maintenance, the content of the electron transport material represented by the general formula (P) in the lower coating layer relative to the total solid content of the lower coating layer is preferably 70% by mass or more. In contrast, in the present embodiment, an electron transport material represented by the general formula (P) having low hole transport in addition to excellent electron transport is included, so even if the content of the electron transport material is less than 70% by mass, both electron mobility and charge maintenance can be taken into account.

[0157] The content of the electron transport material represented by the general formula (P) can be 60% by mass or more, or 60% by mass or more and 70% by mass or less relative to the total solid content of the lower coating. If the content of the electron transport material is 70% by mass or less, the film becomes brittle, the film-forming property is reduced, and the surface roughness of the lower coating is suppressed, so that the charge maintenance is better. On the other hand, if the content of the electron transport material is 60% by mass or more, it has sufficient electron transport energy and the charge maintenance is better.

[0158] As the binding resin, for example, acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, diallyl phthalate resin, polyamide resin, nylon resin, nylon polyamide resin, cellulose resin, gelatin, carbamate resin, melamine resin, benzoguanamine resin (for example, methylated benzoguanamine resin, etc.), polyester resin, unsaturated polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenolic resin (for example, resol phenolic resin), phenol-formaldehyde resin, alkyd resin, epoxy resin and other well-known polymer compounds; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; silane coupling agents and other well-known materials.

[0159] As the binder resin used in the lower coating layer, for example, a charge transport resin having a charge transport group, a conductive resin (such as polyaniline, etc.) and the like can also be cited. The binder resin can be used alone or in combination of two or more. When two or more binder resins are used in combination, the mixing ratio is set as required.

[0160] In this specification, the binder resin is a concept including a resin obtained by a reaction between the resin exemplified above and a curing agent and a resin obtained by a reaction of a curing agent.

[0161] In this specification, for the sake of convenience, a resin obtained by a reaction between a urethane resin and a curing agent is referred to as a "curable urethane resin".

[0162] The binder resin may be any of a thermoplastic resin and a thermosetting resin, but is preferably a thermosetting resin, for example. If the binder resin is a thermosetting resin, for example, when forming a coating film of an upper layer, the film will not dissolve or swell, which is preferred.

[0163] Among them, as the binder resin used in the lower coating layer, for example, it is preferably a resin that is insoluble in the coating solvent of the upper layer, preferably a resin obtained by the reaction between at least one resin selected from the group consisting of diallyl phthalate resin, polyamide resin, nylon resin, carbamate resin, melamine resin, benzoguanamine resin, and phenolic resin and a curing agent, and more preferably at least one resin selected from the group consisting of carbamate resin, melamine resin, and benzoguanamine resin. If the binder resin includes at least one resin selected from the group, the hole barrier is high and the charge retention is excellent.

[0164] The proportion of at least one resin selected from the group consisting of urethane resins, melamine resins and benzoguanamine resins in the total amount of the binder resin in the undercoat layer is, for example, preferably greater than 80% by mass and less than 100% by mass, more preferably greater than 90% by mass and less than 100% by mass, and further preferably greater than 95% by mass and less than 100% by mass.

[0165] The undercoat layer may further contain inorganic particles.

[0166] Examples of inorganic particles include powder resistance (volume resistivity) of 10 2 Ω·cm or more and 10 11 Inorganic particles with a particle size of less than Ω·cm.

[0167] Among them, as the inorganic particles having the above resistance value, for example, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles are preferred, and zinc oxide particles are particularly preferred.

[0168] The specific surface area of ​​the inorganic particles based on the BET method is preferably 10 m 2 / g or more. If the specific surface area is 10m 2 / g or more, there is a tendency that a decrease in charging properties is suppressed.

[0169] The volume average particle diameter of the inorganic particles is, for example, preferably 50 nm or more and 2000 nm or less (for example, preferably 60 nm or more and 1000 nm or less).

[0170] The content of the inorganic particles is, for example, preferably 0 mass % to 80 mass % and more preferably 0 mass % to 70 mass % relative to the total solid content of the undercoat layer.

[0171] The inorganic particles may be subjected to surface treatment. Two or more inorganic particles having different surface treatments or particles having different particle sizes may be used in combination.

[0172] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. In particular, for example, a silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

[0173] Examples of the silane coupling agent having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0174] Silane coupling agents can be used in combination of two or more. For example, silane coupling agents with amino groups can be used in combination with other silane coupling agents. As other silane coupling agents, for example, vinyl trimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3, 4-epoxycyclohexyl) ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyl dimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, 3-chloropropyl trimethoxysilane, etc. can be cited, but it is not limited thereto.

[0175] The surface treatment method using the surface treatment agent may be any method as long as it is a known method, and may be either a dry method or a wet method.

[0176] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0177] The dry method is, for example, a method in which a surface treatment agent dissolved in an organic solvent is directly dripped or added while stirring the inorganic particles by a mixer with a large shear force, and the surface treatment agent is sprayed together with dry air or nitrogen to make the surface treatment agent adhere to the surface of the inorganic particles. When the surface treatment agent is dripped or sprayed, for example, it can be carried out at a temperature below the boiling point of the solvent. After the surface treatment agent is dripped or sprayed, sintering can also be carried out at 100°C or above. There is no particular limitation on the sintering temperature and time as long as the electrophotographic characteristics can be obtained.

[0178] The wet method is, for example, a method in which inorganic particles are dispersed in a solvent by stirring, ultrasonic waves, a sand mill, a grinder, a ball mill, etc., and after adding a surface treatment agent and stirring or dispersing, the solvent is removed to attach the surface treatment agent to the surface of the inorganic particles. The solvent removal method is, for example, to remove the solvent by filtering or distilling. After removing the solvent, sintering can also be performed at a condition of 100°C or above. Sintering is not particularly limited as long as the temperature and time are such that electronic photographic properties can be obtained. In the wet method, the water content of the inorganic particles can be removed before the surface treatment agent is added. As examples thereof, a method of removing the water content of the inorganic particles while stirring and heating in a solvent and a method of removing the water content of the inorganic particles by azeotropy with a solvent can be cited.

[0179] In order to improve electrical characteristics, improve environmental stability and improve image quality, various additives may be included in the undercoat layer.

[0180] As additives, there can be mentioned known materials such as polycyclic condensation type, azo type and other electron transporting materials, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, etc. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but as additives, they can also be added to the undercoat layer.

[0181] Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tri(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0182] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0183] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octanediol, ammonium lactate titanium, titanium lactate, ethyl lactate titanium, triethanolamine titanium, and polyhydroxystearate titanium.

[0184] Examples of the aluminum chelate compound include aluminum isopropoxide, monobutoxyaluminum diisopropoxide, aluminum butoxide, diethyl acetoacetate aluminum diisopropoxide, and tris(ethyl acetoacetate)aluminum.

[0185] These additives may be used alone or in the form of a mixture or polycondensate of a plurality of compounds.

[0186] The volume resistivity of the lower coating layer is preferably 1×10 10 Ω·cm or more and 1×10 12 Ω·cm or less.

[0187] In the undercoat layer, for example, the Vickers hardness is preferably 35 or more.

[0188] In order to suppress interference moire images, the surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to, for example, 1 / (4n) (n is the refractive index of the upper layer) to 1 / 2 of the exposure laser wavelength λ used.

[0189] In order to adjust the surface roughness, resin particles or the like may be added to the undercoat layer. Examples of the resin particles include silicone resin particles and cross-linked polymethacrylate methyl resin particles. In addition, in order to adjust the surface roughness, the surface of the undercoat layer may be ground. Examples of the grinding method include polishing, sandblasting, wet grinding, grinding, and the like.

[0190] -Method for forming lower coating layer-

[0191] The formation of the undercoat layer is not particularly limited and can be performed by a known formation method. For example, the undercoat layer can be formed by forming a coating film of an undercoat layer-forming coating liquid in which the above-mentioned components are added to a solvent, drying the coating film, and heating as necessary.

[0192] Examples of the solvent used for preparing the coating solution for forming an undercoat layer include known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents.

[0193] Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

[0194] Examples of a method for dispersing the inorganic particles when preparing the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0195] Electron transport materials (especially electron transport materials represented by general formula (P)) are difficult to dissolve in organic solvents, so for example, they are preferably dispersed in organic solvents. As the dispersion method, for example, known methods such as roller mills, ball mills, vibrating ball mills, grinders, sand mills, colloid mills, paint stirrers, etc. can be cited. When metal oxide particles are combined in the lower coating, for example, the metal oxide particles are preferably dispersed in the organic solvent by the same dispersion method.

[0196] Examples of a method for applying the coating liquid for forming an undercoat layer onto the conductive substrate include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0197] The content of the metal oxide in the undercoat layer is, for example, preferably 5 mass % or less, more preferably 3 mass % or less, further preferably 0 mass % (ie, containing no metal oxide) or 2 mass % or less, relative to the total solid content of the undercoat layer.

[0198] Generally, metal oxides have a tendency to have low resistance. Therefore, if the content of the metal oxide in the undercoat layer is less than 5% by mass, the resistance of the undercoat layer becomes low and the reduction of the chargeability is suppressed. In addition, from the viewpoint of manufacturing for the purpose of low environmental load, for example, it is also preferred to reduce the content of the metal oxide.

[0199] From the viewpoint of better charge retention, the thickness of the undercoat layer is, for example, preferably 5 μm to 15 μm, more preferably 7 μm to 14 μm, and further preferably 8 μm to 13 μm.

[0200] The thickness of the undercoat layer may be 15 μm or more, or 20 μm or more and 50 μm or less.

[0201] Existing organic pigment electron transport materials have not only electron transport properties but also hole transport properties. When used in the lower coating layer, it is easy to cause hole injection from the conductive substrate or hole injection to the upper charge generation layer when the electrophotographic photosensitive body is charged, and it is easy to cause problems such as reduced chargeability or increased dark decay after charging, and adverse effects on image quality caused by deterioration of charge maintenance. This trend indicates that the thicker the film of the lower coating layer, the greater the trend of this effect. Therefore, it is necessary to set it as a thin film (for example, less than 5μm) in actual use.

[0202] However, if the lower coating is thin, when forming an image, when foreign matter from the outside (toner carrier, wear sheet of plastic parts, etc.), especially needle-shaped foreign matter such as carbon fiber, is attached to the surface of the photoreceptor, the foreign matter sometimes punctures the surface of the photoreceptor due to the contact pressure with the intermediate transfer body, and a leakage current is generated. In contrast, in the present embodiment, the lower coating contains an electron transport material represented by the general formula (P) with excellent electron transport and low hole transport and good charge maintenance, so the film thickness can be made thicker (for example, set to 5 μm or more) compared to the lower coating using the existing organic pigment as the main agent. Therefore, even in the case where foreign matter punctures the lower coating from the surface of the electrophotographic photoreceptor, it is difficult to generate leakage current, so it is considered that the charge maintenance is excellent.

[0203] When the thickness of the undercoat layer is at least 15 μm or less, sufficient electron transport properties are exhibited during the processing time of the electrophotographic photoreceptor, and the internal resistance of the undercoat layer can be maintained high, thereby maintaining anti-leakage due to foreign matter and long-term charge retention.

[0204] [Conductive substrate]

[0205] As the conductive substrate, for example, metal plates, metal drums and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.) can be cited. In addition, as the conductive substrate, for example, conductive compounds (such as conductive polymers, indium oxide, etc.); paper coated, vapor-deposited or laminated with metals (such as aluminum, palladium, gold, etc.) or alloys; resin films; belts, etc. Here, "conductive" means that the volume resistivity is less than 10 13 Ω·cm.

[0206] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to 0.04 μm or more and 0.5 μm or less in terms of center line average roughness Ra for the purpose of suppressing interference fringes generated when irradiating a laser beam. In addition, when incoherent light is used as a light source, roughening to prevent interference fringes is not particularly necessary, but the generation of defects caused by the unevenness of the conductive substrate surface is suppressed, so it is suitable for a longer life.

[0207] Examples of the roughening method include wet grinding in which an abrasive is suspended in water and sprayed onto the conductive substrate, centerless grinding in which the conductive substrate is pressed against a rotating grinding wheel and continuously ground, and anodizing.

[0208] As a method of roughening, there is also a method in which, without roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and roughening is performed by particles dispersed in the layer.

[0209] The roughening treatment based on anodization is to use a metal (e.g., aluminum) conductive substrate as an anode and perform anodization in an electrolyte solution, thereby forming an oxide film on the surface of the conductive substrate. As an electrolyte solution, for example, sulfuric acid solution, oxalic acid solution, etc. can be cited. However, the porous anodized film formed by anodization has chemical activity in its original state, is easily contaminated, and the resistance change caused by the environment is also large. Therefore, for example, it is preferred that the porous anodized film is blocked by the volume expansion caused by water and reaction in pressurized water vapor or boiling water (metal salts such as nickel can be added) to change the micropores of the oxide film to the sealing treatment of a more stable hydrated oxide.

[0210] The film thickness of the anodized film is preferably, for example, 0.3 μm or more and 15 μm or less. When the film thickness is within the above range, the barrier property against injection tends to function and the increase in residual potential due to repeated use tends to be suppressed.

[0211] The conductive substrate may be subjected to a treatment using an acidic treatment liquid or a boehmite treatment.

[0212] The treatment based on the acidic treatment solution is implemented, for example, in the following manner. First, an acidic treatment solution containing phosphoric acid, chromic acid and hydrofluoric acid is prepared. The proportion of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment solution is, for example, in the range of 10 mass % to 11 mass % for phosphoric acid, in the range of 3 mass % to 5 mass % for chromic acid, and in the range of 0.5 mass % to 2 mass % for hydrofluoric acid, and the concentration of the total amount of these acids is preferably in the range of 13.5 mass % to 18 mass %. The treatment temperature is, for example, preferably 42° C. to 48° C. The film thickness of the film is, for example, preferably 0.3 μm to 15 μm.

[0213] The boehmite treatment is carried out, for example, by immersing in pure water at 90°C to 100°C for 5 to 60 minutes or contacting in heated water vapor at 90°C to 120°C for 5 to 60 minutes. The film thickness of the film is preferably 0.1 μm to 5 μm. An anodizing treatment can be further performed using an electrolyte solution with low film solubility such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0214] (Middle layer)

[0215] Although not shown in the figure, an intermediate layer may be provided between the undercoat layer and the photosensitive layer.

[0216] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, melamine resins and other polymer compounds.

[0217] The intermediate layer may be a layer containing an organic metal compound. Examples of the organic metal compound used in the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0218] The compounds used in the intermediate layer may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0219] Among them, the intermediate layer is preferably a layer containing an organic metal compound containing zirconium atoms or silicon atoms, for example.

[0220] The formation of the intermediate layer is not particularly limited and can be performed by a known formation method. For example, the intermediate layer can be formed by forming a coating film of an intermediate layer-forming coating liquid in which the above-mentioned components are added to a solvent, drying the coating film, and heating as necessary.

[0221] As a coating method for forming the intermediate layer, a common method such as a dip coating method, a push coating method, a wire bar coating method, a spray coating method, a blade coating method, an air knife coating method, a curtain coating method, etc. can be used.

[0222] The film thickness of the intermediate layer is preferably set within a range of, for example, 0.1 μm or more and 3 μm or less.

[0223] (Charge Generation Layer)

[0224] The charge generating layer is, for example, a layer containing a charge generating material and a binder resin. Furthermore, the charge generating layer may be a vapor-deposited layer of the charge generating material. The vapor-deposited layer of the charge generating material is suitable for the case where an incoherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array is used.

[0225] Examples of the charge generating material include azo pigments such as disazo and trisazo; condensed ring aromatic pigments such as dibromoanthraquinone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0226] Among them, in order to cope with laser exposure in the near-infrared region, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge generating materials, and more specifically, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and oxytitanium phthalocyanine are more preferred.

[0227] On the other hand, in order to cope with laser exposure in the near-ultraviolet region, preferred charge generating materials include condensed ring aromatic pigments such as dibromoanthraquinone, thioindigo pigments, porphyrazine compounds, zinc oxide, trigonal selenium, and disazo pigments.

[0228] The above-mentioned charge generating material can be used even when an incoherent light source such as an LED or an organic EL array having a central wavelength of light emitted in the range of 450 nm to 780 nm is used.

[0229] On the other hand, when an n-type semiconductor such as a condensed aromatic pigment, perylene pigment, or azo pigment is used as a charge generating material, dark current is less likely to be generated, and image defects called black spots can be suppressed even in a thin film.

[0230] The n-type is determined by using the commonly used time-of-flight method based on the polarity of the photocurrent flowing, and a semiconductor in which electrons flow more easily as carriers than holes is defined as the n-type.

[0231] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins, and can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl pyrene, and polysilane.

[0232] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (condensation products of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, etc. Here, "insulation" means that the volume resistivity is 10 13 Ω·cm or more.

[0233] These binder resins may be used alone or in combination of two or more.

[0234] The mixing ratio of the charge generating material to the binder resin is preferably in the range of 10:1 to 1:10, for example, in terms of mass ratio.

[0235] Other well-known additives may be contained in the charge generating layer.

[0236] The formation of the charge generating layer is not particularly limited, and a known formation method can be used, but for example, a coating film of a charge generating layer forming coating liquid is formed by adding the above-mentioned components to a solvent, and the coating film is dried and heated as needed. In addition, the charge generating layer can be formed by vapor deposition of the charge generating material. The formation of the charge generating layer by vapor deposition is particularly suitable for the case where a condensed ring aromatic pigment or a perylene pigment is used as the charge generating material.

[0237] Examples of the solvent used for preparing the charge generating layer-forming coating solution include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0238] As a method for dispersing particles (e.g., charge generating material) in the coating liquid for forming the charge generating layer, for example, a medium disperser such as a ball mill, a vibrating ball mill, a grinder, a sand mill, a horizontal sand mill, or a stirrer, an ultrasonic disperser, a roll mill, a high-pressure homogenizer, or a medium-free disperser can be used. As a high-pressure homogenizer, for example, a collision method in which the dispersion is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by penetrating a fine flow path under high pressure, etc. can be cited.

[0239] In the dispersion, it is effective to set the average particle size of the charge generating material in the charge generating layer forming coating liquid to 0.5 μm or less, for example, preferably 0.3 μm or less, more preferably 0.15 μm or less.

[0240] Examples of a method for applying the charge generating layer forming coating liquid onto the undercoat layer (or the intermediate layer) include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0241] The film thickness of the charge generating layer is preferably set within the range of, for example, 0.1 μm to 5.0 μm, and more preferably within the range of 0.2 μm to 2.0 μm.

[0242] (Charge Transport Layer)

[0243] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymer charge transport material.

[0244] As charge transport materials, there can be cited quinone compounds such as p-benzoquinone, chloranil, tetrabromobenzoquinone, anthraquinone, etc.; tetracyanoterephthalene compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; anthrone compounds; benzophenone compounds; cyanoethylene compounds; ethylene compounds and other electron transport compounds. As charge transport materials, there can also be cited hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. These charge transport materials can be used alone or in combination of two or more, but are not limited thereto.

[0245] From the viewpoint of charge mobility, the charge transport material is preferably, for example, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2).

[0246] [Chemical formula 7]

[0247]

[0248] In the structural formula (a-1), Ar T1 ,Ar T2 and Ar T3 Each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ) or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). T4 , R T5 , R T6 , R T7 and R T8 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0249] Examples of substituents of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. In addition, examples of substituents of the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0250] [Chemical formula 8]

[0251]

[0252] In the structural formula (a-2), R T91 and R T92 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted by an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ) or -CH=CH-CH=C(R T15 )(R T16 ), R T12 , R T13 , R T14 , R T15 and R T16 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1 and Tn2 each independently represent an integer of 0 or more and 2 or less.

[0253] Examples of substituents of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. In addition, examples of substituents of the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0254] Here, from the viewpoint of charge mobility, among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), for example, those having "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 )" benzidine derivatives.

[0255] As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinyl carbazole and polysilane can be cited. In particular, polyester-based polymer charge transport materials are particularly preferred. The polymer charge transport material can be used alone or in combination with a binder resin.

[0256] The binder resin used in the charge transport layer can be polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinyl carbazole, polysilane, etc. Among them, as a binder resin, for example, preferably polycarbonate resin or polyarylate resin. These binder resins are used alone or in combination of two or more.

[0257] The mixing ratio of the charge transport material to the binder resin is preferably, for example, 10:1 to 1:5 in terms of mass ratio.

[0258] Other well-known additives may be contained in the charge transport layer.

[0259] The charge transport layer can be formed by any known method without particular limitation, and can be formed by, for example, forming a coating film of a charge transport layer-forming coating liquid in which the above components are added to a solvent, drying the coating film, and heating as necessary.

[0260] As the solvent for preparing the coating solution for forming the charge transport layer, there can be mentioned aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and dichloroethane; cyclic or linear ethers such as tetrahydrofuran and diethyl ether, and other common organic solvents. These solvents can be used alone or in combination of two or more.

[0261] Examples of a coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0262] The film thickness of the charge transport layer is preferably set within the range of, for example, 5 μm to 50 μm, and more preferably within the range of 10 μm to 30 μm.

[0263] (Protective layer)

[0264] The protective layer is provided on the photosensitive layer as required. The protective layer is provided, for example, to prevent chemical changes in the photosensitive layer during charging or to further improve the mechanical strength of the photosensitive layer.

[0265] Therefore, for example, a layer composed of a cured film (crosslinked film) is preferably used as the protective layer. Examples of these layers include the layers shown in the following 1) or 2).

[0266] 1) A layer consisting of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer containing a polymer or a crosslinked body of the reactive group-containing charge transport material)

[0267] 2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a non-charge transport material having a reactive group but not having a charge transport skeleton (i.e., a layer comprising a non-reactive charge transport material and a polymer or a crosslinked body of the non-charge transport material having a reactive group)

[0268] Examples of the reactive group of the charge transport material containing a reactive group include a chain polymerizable group, an epoxy group, -OH, -OR [wherein R represents an alkyl group], -NH2, -SH, -COOH, -SiR Q1 3-Qn (OR Q2 ) Qn [Among them, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R Q2 represents a hydrogen atom, an alkyl group, a trialkylsilyl group, and Qn represents an integer of 1 to 3] and the like.

[0269] As a chain polymerizable group, there is no particular limitation as long as it is a functional group capable of free radical polymerization, and for example, it is a functional group having a group containing at least a carbon double bond. Specifically, there can be mentioned a group containing at least one selected from vinyl, vinyl ether, vinyl sulfide, styryl (vinyl phenyl), acryloyl, methacryloyl and their derivatives. Among them, due to its excellent reactivity, as a chain polymerizable group, for example, it is preferably a group containing at least one selected from vinyl, styryl (vinyl phenyl), acryloyl, methacryloyl and their derivatives.

[0270] The charge transport skeleton of the charge transport material containing a reactive group is not particularly limited as long as it is a known structure in an electrophotographic photoreceptor, and examples thereof include skeletons derived from nitrogen-containing hole transport compounds such as triarylamine compounds, benzidine compounds, and hydrazone compounds, and structures conjugated with nitrogen atoms. Among them, for example, a triarylamine skeleton is preferred.

[0271] The reactive group-containing charge transport material, the non-reactive charge transport material, and the reactive group-containing non-charge transport material having these reactive groups and charge transport skeletons may be selected from known materials.

[0272] Other well-known additives may be contained in the protective layer.

[0273] The protective layer can be formed by any known method without particular limitation, and can be formed by, for example, forming a coating film of a protective layer-forming coating liquid in which the above-mentioned components are added to a solvent, drying the coating film, and performing a curing treatment such as heating as necessary.

[0274] Examples of the solvent used to prepare the protective layer-forming coating solution include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; alcohol solvents such as isopropyl alcohol and butanol, etc. These solvents may be used alone or in combination of two or more.

[0275] In addition, the protective layer-forming coating liquid may be a solvent-free coating liquid.

[0276] Examples of a method for applying the protective layer-forming coating liquid onto a photosensitive layer (eg, charge transport layer) include common methods such as dip coating, push coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating.

[0277] The film thickness of the protective layer is preferably set within the range of, for example, 1 μm to 20 μm, and more preferably within the range of 2 μm to 10 μm.

[0278] [Single-layer photosensitive layer]

[0279] The single-layer photosensitive layer (charge generating layer / charge transport layer) is, for example, a layer containing a charge generating material, a charge transport material, and, if necessary, a binder resin and other known additives. These materials are the same as those described in the charge generating layer and the charge transport layer.

[0280] In the single-layer photosensitive layer, the content of the charge generating material relative to the total solid content may be, for example, 0.1% by mass or more and 10% by mass or less, preferably 0.8% by mass or more and 5% by mass or less. In addition, in the single-layer photosensitive layer, the content of the charge transporting material relative to the total solid content may be, for example, 5% by mass or more and 50% by mass or less.

[0281] The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generating layer or the charge transporting layer.

[0282] The film thickness of the single-layer photosensitive layer may be, for example, 5 μm or more and 50 μm or less, and preferably 10 μm or more and 40 μm or less.

[0283] [Image forming apparatus, process cartridge]

[0284] The image forming apparatus according to the present embodiment comprises an electrophotographic photoreceptor, a charging device for charging the surface of the electrophotographic photoreceptor, an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image, and a transfer device for transferring the toner image to the surface of a recording medium. As the electrophotographic photoreceptor, the electrophotographic photoreceptor according to the present embodiment is applied.

[0285] The image forming apparatus involved in this embodiment is applicable to the following well-known image forming apparatuses: an apparatus equipped with a fixing device for fixing a toner image transferred to the surface of a recording medium; an apparatus using a direct transfer method for directly transferring a toner image formed on the surface of an electrophotographic photosensitive body to a recording medium; an apparatus using an intermediate transfer method for transferring a toner image formed on the surface of an electrophotographic photosensitive body once to the surface of an intermediate transfer body, and for a second time transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; an apparatus equipped with a cleaning device for cleaning the surface of the electrophotographic photosensitive body after transferring the toner image but before charging; an apparatus equipped with a static elimination device for removing static electricity by irradiating the surface of the electrophotographic photosensitive body with static elimination light after transferring the toner image and before charging; and an apparatus equipped with an electrophotographic photosensitive body heating component for increasing the temperature of the electrophotographic photosensitive body and lowering the relative temperature, etc.

[0286] In the case of an intermediate transfer type device, the transfer device, for example, is applicable to the following structure, which has an intermediate transfer body having a toner image transferred on its surface, a primary transfer device for transferring the toner image formed on the surface of the electronic photographic photosensitive body to the surface of the intermediate transfer body, and a secondary transfer device for secondary transferring the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0287] The image forming apparatus according to the present embodiment may be any of a dry developing system image forming apparatus and a wet developing system (development system using a liquid developer) image forming apparatus.

[0288] In addition, in the image forming apparatus according to the present embodiment, for example, the portion having the electrophotographic photosensitive body may be a cartridge structure (processing cartridge) that is detachable from the image forming apparatus. As the processing cartridge, for example, a processing cartridge having the electrophotographic photosensitive body according to the present embodiment is preferably used. In addition, in the processing cartridge, in addition to the electrophotographic photosensitive body, for example, at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device may be provided.

[0289] Hereinafter, an example of the image forming apparatus according to the present embodiment is shown, but the present invention is not limited thereto. In addition, the main parts shown in the drawings are described, and the description of other parts is omitted.

[0290] Figure 2 It is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

[0291] like Figure 2 As shown, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 having an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming device), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In addition, in the image forming apparatus 100, the exposure device 9 is arranged at a position capable of exposing the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 is arranged at a position opposed to the electrophotographic photoreceptor 7 with the intermediate transfer body 50 interposed therebetween, and the intermediate transfer body 50 is arranged so that a part thereof contacts the electrophotographic photoreceptor 7. Although not shown in the figure, a secondary transfer device is further provided for transferring the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). In addition, the intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown in the figure) correspond to an example of a transfer device.

[0292] Figure 2 The process box 300 in the embodiment integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging device), the developing device 11 (an example of a developing device), and the cleaning device 13 (an example of a cleaning device) in the housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is configured to contact the surface of the electrophotographic photoreceptor 7. In addition, the cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and it may be used alone or in combination with the cleaning blade 131.

[0293] In addition, Figure 2 In the example shown, as the image forming apparatus, a fibrous member 132 (roller-shaped) for supplying lubricant 14 to the surface of electrophotographic photoreceptor 7 and a fibrous member 133 (flat brush-shaped) for assisting cleaning are provided, but these may be arranged as necessary.

[0294] Hereinafter, each structure of the image forming apparatus according to the present embodiment will be described.

[0295] A live device -

[0296] As the charging device 8, for example, a contact type charging device such as a charging roller, a charging brush, a charging film, a charging rubber blade, a charging hose, etc. using conductive or semi-conductive charging can be used. In addition, a non-contact type roller charging device, a scorotron charging device or a corotron charging device using corona discharge, etc., which are known per se, can also be used.

[0297] -Exposure device-

[0298] As the exposure device 9, for example, there can be cited an optical system device that exposes semiconductor laser, LED light, liquid crystal shutter light, etc. on the surface of the electrophotographic photoreceptor 7 to a prescribed pattern. The wavelength of the light source is set within the spectral sensitivity region of the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, near-infrared light with an oscillation wavelength near 780nm is the mainstream. However, it is not limited to this wavelength. As an oscillation wavelength laser or a blue laser in the 600nm band, a laser with an oscillation wavelength in the range of more than 400nm and less than 450nm can also be used. In addition, a surface-emitting laser light source of the type that can output multiple beams in order to form a color image is also effective.

[0299] -Developing device-

[0300] As the developing device 11, for example, a general developing device that develops by contact or non-contact with a developer can be cited. As the developing device 11, there is no particular limitation as long as it has the above-mentioned function, and it can be selected according to the purpose. For example, a known developer having a function of attaching a single-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, a roller, etc. can be cited. Among them, for example, a developer using a developing roller that holds the developer on the surface is preferred.

[0301] The developer used in the developing device 11 may be a single-component developer containing only a toner, or may be a two-component developer containing a toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. As these developers, well-known developers are applicable.

[0302] -Cleaning device-

[0303] The cleaning device 13 may be a cleaning blade type device including a cleaning blade 131 .

[0304] In addition to the cleaning blade method, a brush cleaning method and a simultaneous development and cleaning method may also be used.

[0305] -Transfer device-

[0306] Examples of the transfer device 40 include a contact transfer charger using a belt, a roller, a film, a rubber blade, etc.; a corotron transfer charger using corona discharge; a corotron transfer charger, etc., which are known per se.

[0307] -Intermediate transfer body-

[0308] As the intermediate transfer body 50, a belt-shaped transfer body (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity can be used. In addition, as a form of the intermediate transfer body, a roller-shaped transfer body can be used.

[0309] Figure 3 It is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

[0310] Figure 3 The image forming apparatus 120 shown is a multi-color image forming apparatus of a tandem type equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged on the intermediate transfer body 50, respectively, and a single electrophotographic photoreceptor is used for each color. In addition, the image forming apparatus 120 has the same structure as the image forming apparatus 100 except for the tandem type.

[0311] Example

[0312] The following examples are given to further specifically illustrate the electrophotographic photosensitive body of the present invention. The materials, usage amounts, ratios, processing steps, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the purpose of the present invention. Therefore, the scope of the electrophotographic photosensitive body of the present invention should not be interpreted in a restrictive manner by the specific examples shown below.

[0313] -Preparation of the bottom coating-

[0314] (Preparation of Lower Coating Layer 1)

[0315] 32 parts by mass of the electron transport material (P-1) was mixed with 15 parts by mass of a curable urethane resin (thermosetting resin, blocked isocyanate, CORONATE BI-301, manufactured by TOSOH CORPORATION, solid content 75%) and 6.3 parts by mass of a butyral resin (S-LEC BL-S, manufactured by SEKISUI CHEMICAL CO., LTD.) dissolved in 170 parts by mass of methyl ethyl ketone. The glass beads were dispersed in a sand mill for 300 minutes to obtain a dispersion.

[0316] After filtering out the glass beads, 0.005 parts by mass of bismuth carboxylate (K-KAT XK-640) manufactured by KING INDUSTRY was added as a catalyst to the obtained dispersion to obtain a coating solution for forming an undercoat layer. The coating solution was dip-coated on an aluminum substrate by dip coating, and dried and cured at 160° C. for 60 minutes to obtain an undercoat layer 1 having a thickness of 10 μm and comprising a curable urethane resin and an electron transport material represented by the general formula (P).

[0317] (Production of Lower Coating Layer 2)

[0318] 30 parts by mass of the electron transport material (P-1) was mixed with 15 parts by mass of a resol phenolic resin (thermosetting resin, PL-2215, manufactured by Gunei Chemical Industry Co., Ltd.) and 5.0 parts by mass of a butyral resin (S-LEC BL-1, manufactured by SEKISUI CHEMICAL CO., LTD.) dissolved in 120 parts by mass of methyl ethyl ketone and 60 parts by mass of isopropyl alcohol. The glass beads were dispersed in a sand mill for 300 minutes to obtain a dispersion.

[0319] After filtering out the glass beads, 0.003 parts by mass of KING INDUSTRY blocked sulfonic acid (Nacure 2500) as a catalyst was added to the obtained dispersion to obtain a coating solution for forming an undercoat layer. The coating solution was dip-coated on an aluminum substrate by dip coating, and dried and cured at 150° C. for 60 minutes to obtain an undercoat layer 2 having a thickness of 10 μm containing a phenolic resin and an electron transport material represented by the general formula (P).

[0320] (Production of Lower Coating Layer 3)

[0321] 30 parts by mass of the electron transport material (P-1) was mixed with 25 parts by mass of a methylated benzoguanamine resin (thermosetting resin, BL-60, manufactured by SANWA CHEMICAL CO., LTD., solid content 60%) and 5 parts by mass of methylated melamine (MW-390, manufactured by SANWA CHEMICAL CO., LTD.) dissolved in 120 parts by mass of methyl ethyl ketone and 60 parts by mass of isopropyl alcohol. The glass beads were dispersed in a sand mill for 300 minutes to obtain a dispersion. After filtering out the glass beads, 0.003 parts by mass of a KING INDUSTRY-made blocked sulfonic acid (Nacure5225) as a catalyst was added to the obtained dispersion to obtain a coating solution for forming an undercoat layer. The coating solution was dip-coated on an aluminum substrate by dip coating, and dried and cured at 150°C for 60 minutes to obtain an undercoat layer 3 having a thickness of 10 μm containing a guanamine resin and an electron transport material represented by the general formula (P).

[0322] (Production of Lower Coating Layer 4)

[0323] 10 parts by mass of an electron transport material (P-1) with a primary particle size of 1 μm, 10 parts by mass of sodium chloride, and 150 parts by mass of 0.3 mm zirconium oxide beads were added to a zirconium oxide container and pulverized at 500 rpm for 1 hour using a planetary mill manufactured by Fritsch Co., Ltd. The zirconium oxide beads were filtered out with a 50 μm sieve made of polypropylene and washed with methanol. After repeatedly washing the obtained crystals with distilled water, they were dried in a freeze dryer for 48 hours to obtain 7.5 parts by mass of electron transport material (P-1). The treatment was repeated four times to obtain a total of 30 parts by mass of pulverized electron transport material (P-1). The average primary particle size of 10 crystals randomly selected from the SEM image was 0.08 μm.

[0324] The obtained electron transport material (P-1) (30 parts by mass), diallyl phthalate prepolymer (DAISO DAP (registered trademark) A, manufactured by Osaka Gas) (15 parts by mass), trimethylolpropane trimethacrylate (5.0 parts by mass), and methyl ethyl ketone (170 ml) were mixed and used. The glass beads were dispersed in a paint shaker for 180 minutes to obtain a dispersion. A polymerization initiator, PERBUTYL (registered trademark) Z (manufactured by NOF CORPORATION.), was added to the obtained dispersion to obtain a coating solution for forming a lower coating layer. The coating solution was dip-coated on an aluminum substrate by a dip coating method, and dried and cured at 160° C. for 60 minutes under a nitrogen atmosphere to obtain a lower coating layer 4 having a thickness of 10 μm containing a diallyl phthalate resin (thermosetting resin) and an electron transport material represented by the general formula (P).

[0325] (Production of Lower Coating Layer 5)

[0326] In the copolymer of nylon and polyamide, namely nylon polyamide (thermoplastic resin, Amilan TMCM8000, manufactured by TORAY INDUSTRIES, INC.) 20 g was dissolved in 200 ml of methanol, and 30 g of the electron transport material (P-1) pulverized in the same manner as the undercoat layer 4 was added. The glass beads were dispersed in a paint shaker for 180 minutes to obtain a dispersion liquid. The coating liquid was dip-coated on an aluminum substrate by dip coating, and dried at 150° C. for 45 minutes under a nitrogen atmosphere to obtain a lower coating layer 5 having a thickness of 10 μm containing nylon polyamide and an electron transport material represented by the general formula (P).

[0327] (Production of Lower Coating Layer 6)

[0328] An undercoat layer 6 was obtained by the same method as that of the undercoat layer 1 except that the electron transporting material (P-1) was changed to the electron transporting material (P-3).

[0329] (Production of Lower Coating Layer 7)

[0330] An undercoat layer 7 was obtained by the same method as that of the undercoat layer 1 except that the electron transporting material (P-1) was changed to the electron transporting material (P-8).

[0331] (Production of Lower Coating Layer 8)

[0332] Undercoat layer 8 was obtained by the same method as undercoat layer 1 except that the electron transporting material (P-1) in undercoat layer 1 was changed to the electron transporting material (P-1) pulverized in the same method as undercoat layer 4.

[0333] (Production of Lower Coating Layer 9)

[0334] Undercoat layer 9 was obtained in the same manner as undercoat layer 3 except that the methylated benzoguanamine resin was changed to a melamine resin (thermosetting resin, product name MX-750, manufactured by SANWA CHEMICAL CO., LTD.).

[0335] (Production of Undercoat Layers 10 to 14)

[0336] In the undercoat layer 1, except that the electron transporting material (P-1) was changed to the electron transporting material of the type shown in Table 1, the same method as the undercoat layer 1 was carried out to obtain undercoat layers 10 to 14, respectively.

[0337] (Production of Undercoat Layers 15 and 16)

[0338] In the above-mentioned undercoat layer 1, except that the thickness of the undercoat layer was changed to the thickness shown in Table 1, the same method as undercoat layer 1 was carried out to obtain undercoat layers 15 and 16, respectively.

[0339] (Production of Lower Coating Layer 17)

[0340] In the undercoat layer 1, the electron transport material (P-1) was changed to an electron transport material (P-1) having an average primary particle size of 0.01 μm obtained by setting the crushing time to 4 hours in the preparation of the undercoat layer 4. Except for this, the undercoat layer 17 was obtained in the same manner as the undercoat layer 1.

[0341] (Production of Lower Coating Layer 18)

[0342] Undercoat layer 18 was obtained by the same method as undercoat layer 1 except that the electron transport material (P-1) in undercoat layer 1 was changed to an electron transport material (P-1) having a particle size of 1.2 μm obtained by recrystallization with sulfuric acid.

[0343] (Production of Lower Coating Layer 19)

[0344] 32 parts by mass of the electron transport material (P-1), zinc oxide fine particles (Tayca Corporation, average particle size: 75 nm, specific surface area: 14 m) and 15 parts by mass of a curable urethane resin (thermosetting resin, blocked isocyanate, CORONATE BI-301, manufactured by TOSOH CORPORATION, solid content: 75%) and 6.3 parts by mass of a butyral resin (S-LEC BL-S, manufactured by SEKISUI CHEMICAL CO., LTD.) dissolved in 170 parts by mass of methyl ethyl ketone were mixed. 2 / g) 5 parts by mass, using The glass beads were dispersed in a sand mill for 300 minutes to obtain a dispersion.

[0345] After filtering out the glass beads, 0.005 parts by mass of bismuth carboxylate (K-KAT XK-640) manufactured by KING INDUSTRY was added as a catalyst to the obtained dispersion to obtain a coating solution for forming an undercoat layer. The coating solution was dip-coated on an aluminum substrate by dip coating, and dried and cured at 160° C. for 60 minutes to obtain an undercoat layer 19 having a thickness of 10 μm containing a curable urethane resin and an electron transport material represented by the general formula (P).

[0346] (Production of Lower Coating Layer 20)

[0347] An undercoat layer 20 was obtained by the same method as undercoat layer 1 except that the content of the electron transport material (P-1) relative to the total solid content of the undercoat layer was set to the amount shown in Table 1.

[0348] (Preparation of Undercoat Layer 1 for Comparative Example)

[0349] In the undercoat layer 1 , a comparative undercoat layer 1 was prepared in the same manner as the undercoat layer 1 except that the electron transporting material (P-1) was changed to the following imide compound (A).

[0350] (Preparation of Undercoat Layer 2 for Comparative Example)

[0351] A comparative undercoat layer 2 was prepared in the same manner as undercoat layer 1 except that the electron transporting material (P-1) was changed to the following imide compound (B).

[0352] (Preparation of Undercoat Layer 3 for Comparative Example)

[0353] A comparative undercoat layer 3 was prepared in the same manner as undercoat layer 1 except that the electron transporting material (P-1) was changed to the following imide compound (C).

[0354] (Comparative Example: Preparation of Undercoat Layer 4)

[0355] In undercoat layer 1, except that the electron transport material (P-1) was changed to the following imide compound (C), and the amount of the following imide compound (C) was set to the amount shown in Table 1, the same method as undercoat layer 1 was carried out to prepare undercoat layer 4 for comparison.

[0356] [Chemical formula 9]

[0357]

[0358] <Example 1 to Example 20 and Comparative Example 1 to Comparative Example 4>

[0359] (Formation of Charge Generation Layer)

[0360] A mixture of 15 parts by mass of hydroxygallium phthalocyanine having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.3°, 16.0°, 24.9°, and 28.0° in an X-ray diffraction spectrum using Cukα characteristic X-rays as a charge generating material, 10 parts by mass of a vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Company Limited) as a binder resin, and 200 parts by mass of n-butyl acetate was used as a diameter The glass beads were stirred in a sand mill for 4 hours to disperse them. 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added to the obtained dispersion, and stirred to obtain a coating solution for forming a charge generation layer. The coating solution for forming a charge generation layer was dip-coated on the outer peripheral surface of the undercoat layer of the type shown in Table 1, and dried at 150° C. for 15 minutes to form a charge generation layer with a film thickness of 0.2 μm.

[0361] (Formation of Charge Transport Layer)

[0362] 38 parts by mass of the following charge transport agent (HT-1), 10 parts by mass of the following charge transport agent (HT-2), 52 parts by mass of the following polycarbonate resin (A) (viscosity average molecular weight: 46,000), and 0.3 parts by mass of a fluorinated graft polymer (manufactured by TOAGOSEI CO., LTD.: GF-500) as a dispersing aid were added to 800 parts by mass of tetrahydrofuran and dissolved, 8 parts by mass of a tetrafluoroethylene resin (manufactured by DAIKIN INDUSTRIES, Ltd.: Luberon L5, average particle size 300 nm) were added, and a homogenizer (manufactured by IKA: ULTRA-TURRAX) was used to disperse at 5500 rpm for 2 hours to obtain a coating liquid for forming a charge transport layer. The coating liquid was applied to the charge generating layer and dried at 140°C for 40 minutes to form a charge transport layer with a film thickness of 30 μm. It was set as an electrophotographic photoreceptor.

[0363] [Chemical formula 10]

[0364]

[0365] [Chemical formula 11]

[0366]

[0367] In the formula, 15 and 85 represent molar ratios (mol %).

[0368] <Evaluation>

[0369] The electrophotographic photoreceptor of each example or comparative example was mounted on a modified image forming apparatus DocuCentre C5570 manufactured by FUJIFILM Business Innovation, and the following evaluation was performed.

[0370] -Evaluation of charge retention performance-

[0371] Under the environment of 10°C and 15% RH, the electrophotographic photoreceptor was charged by applying a voltage of -710V, and the initial charge potential V1 (before image output) of the outer peripheral surface of the electrophotographic photoreceptor before image output and the charge potential V2 of the outer peripheral surface of the electrophotographic photoreceptor after printing 30,000 sheets of 50% halftone images were measured. Then, the potential difference V1-V2 was calculated and evaluated according to the following criteria. In addition, the acceptable range is A to C.

[0372] A: Less than 20V

[0373] B: 20V or more and less than 25V.

[0374] C: 25V or more and less than 30V.

[0375] D: 30V or more and less than 35V, which is a problematic level.

[0376] E: 35 V or more, which is a problematic level.

[0377] - Evaluation of foreign body penetration -

[0378] The evaluation of foreign matter penetration inhibition was carried out by utilizing the phenomenon that when the carbon fiber penetrates the photosensitive layer and the lower coating layer and reaches the conductive substrate, the current flows and the image defects are generated. At this time, the charged potential is set to -700V normally. Carbon fibers (average diameter 7μm, average length 30μm) are mixed in the developer to make a concentration of 0.2% by mass, and 20,000 images with a concentration of 20% are continuously output on A4 paper. Then, 10 images with a concentration of 20% are output on A4 paper. The presence or absence of dot-shaped image defects in the 10th image is observed with the naked eye, and the degree of image defects is classified into the following A to D. The results are shown in Table 1.

[0379] A: There are no dot-shaped image defects.

[0380] B: There are less than 5 dot-like image defects.

[0381] C: The number of dot-like image defects is 5 or more and less than 10.

[0382] D: There are 10 or more dot-like image defects.

[0383]

[0384] As shown in Table 1, it is found that the electrophotographic photoreceptors of Examples are superior in charge retention properties compared to the electrophotographic photoreceptors of Comparative Examples.

[0385] This embodiment includes the following aspects.

[0386] (1) An electrophotographic photoreceptor comprising:

[0387] Conductive substrate;

[0388] an undercoat layer disposed on the conductive substrate and containing a binder resin and an electron transport material represented by the following general formula (P); and

[0389] The photosensitive layer is disposed on the lower coating layer.

[0390] [Chemical formula 12]

[0391]

[0392] In the above general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group or a halogen atom.

[0393] (2) The electrophotographic photoreceptor according to (1), wherein

[0394] In the general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Each independently represents a hydrogen atom or a halogen atom.

[0395] (3) The electrophotographic photoreceptor according to (1) or (2), wherein

[0396] In the general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Represents a hydrogen atom.

[0397] (4) The electrophotographic photoreceptor according to any one of (1) to (3), wherein

[0398] The electron transport material has an average primary particle size of 1 μm or less.

[0399] (5) The electrophotographic photoreceptor according to (4), wherein

[0400] The electron transport material has an average primary particle size of 0.03 μm or more and 1 μm or less.

[0401] (6) The electrophotographic photoreceptor according to any one of (1) to (5), wherein

[0402] The content of the electron transport material is less than 70 mass % based on the total solid content of the undercoat layer.

[0403] (7) The electrophotographic photoreceptor according to any one of (1) to (6), wherein

[0404] The undercoat layer has a thickness of 5 μm or more and 15 μm or less.

[0405] (8) The electrophotographic photoreceptor according to any one of (1) to (7), wherein

[0406] The bonding resin is a thermosetting resin.

[0407] (9) The electrophotographic photoreceptor according to (8), wherein

[0408] The thermosetting resin includes at least one resin selected from the group consisting of urethane resin, melamine resin, and benzoguanamine resin.

[0409] (10) The electrophotographic photoreceptor according to (1), wherein

[0410] The content of the metal oxide in the undercoat layer is 5% by mass or less based on the total solid content of the undercoat layer.

[0411] (11) A process cartridge comprising the electrophotographic photoreceptor according to any one of (1) to (10), wherein:

[0412] The process cartridge is attachable to and detachable from the image forming apparatus.

[0413] (12) An image forming apparatus comprising:

[0414] The electrophotographic photoreceptor according to any one of (1) to (10);

[0415] A charging device for charging the surface of the electrophotographic photoreceptor;

[0416] An electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0417] a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and

[0418] The transfer device transfers the toner image to the surface of a recording medium.

[0419] The effects of the above method are as follows.

[0420] According to the invention involved in (1), (2) or (3), there is provided an electrophotographic photosensitive body having excellent charge retention properties compared to the case of using an undercoat layer containing a binding resin and an existing electron transporting material (for example, the aforementioned electron transporting material (A), (B) or (C), etc.).

[0421] According to the invention as set forth in (4), there is provided an electrophotographic photoreceptor having excellent charge retention performance compared to a case where the average primary particle size of the electron transport material exceeds 1 μm.

[0422] According to the invention as set forth in (5), there is provided an electrophotographic photoreceptor having excellent film-forming properties and charge retention properties compared to a case where the average primary particle size of the electron transport material is less than 0.03 μm or exceeds 1 μm.

[0423] According to the invention as set forth in (6), there is provided an electrophotographic photoreceptor having excellent film-forming properties and charge retention properties compared to a case where the content of the electron transport material is 70% by mass or more based on the total solid content of the undercoat layer.

[0424] According to the invention as set forth in (7), there is provided an electrophotographic photoreceptor having excellent charge retention performance compared with a case where the thickness of the undercoat layer is less than 5 μm or exceeds 15 μm.

[0425] According to the invention as set forth in (8), there is provided an electrophotographic photoreceptor having excellent charge retention performance compared to a case where the binder resin is a thermoplastic resin.

[0426] According to the invention as set forth in (9), there is provided an electrophotographic photoreceptor having excellent charge retention properties compared to the case where the thermosetting resin is nylon polyamide.

[0427] According to the invention as set forth in (10), there is provided an electrophotographic photoreceptor having excellent charge retention performance compared with a case where the content of the metal oxide in the undercoat layer exceeds 5% by mass based on the total solid content of the undercoat layer.

[0428] According to the invention involved in (11) or (12), there is provided a processing box or an image forming apparatus having an electrophotographic photosensitive body with excellent charge retention properties compared to a processing box or an image forming apparatus having an electrophotographic photosensitive body using an undercoat layer containing a binding resin and an existing electron transporting material (for example, the aforementioned electron transporting material (A), (B) or (C), etc.).

[0429] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. An electrophotographic photoreceptor comprising: Conductive substrate; an undercoat layer disposed on the conductive substrate and containing a binder resin and an electron transport material represented by the following general formula (P); and A photosensitive layer is disposed on the lower coating layer, [Chemical formula 1] In the above general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group or a halogen atom.

2. The electrophotographic photoreceptor according to claim 1, wherein In the general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Each independently represents a hydrogen atom or a halogen atom.

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein In the general formula (P), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Represents a hydrogen atom.

4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein The electron transport material has an average primary particle size of 1 μm or less.

5. The electrophotographic photoreceptor according to claim 4, wherein The electron transport material has an average primary particle size of 0.03 μm or more and 1 μm or less.

6. The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein The content of the electron transport material is less than 70 mass % based on the total solid content of the undercoat layer.

7. The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein The undercoat layer has a thickness of 5 μm or more and 15 μm or less.

8. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein The bonding resin is a thermosetting resin.

9. The electrophotographic photoreceptor according to claim 8, wherein The thermosetting resin includes at least one resin selected from the group consisting of urethane resin, melamine resin, and benzoguanamine resin.

10. The electrophotographic photoreceptor according to claim 1, wherein The content of the metal oxide in the undercoat layer is 5% by mass or less based on the total solid content of the undercoat layer.

11. A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 10, wherein: The process cartridge is attachable to and detachable from the image forming apparatus.

12. An image forming apparatus comprising: The electrophotographic photoreceptor according to any one of claims 1 to 10; A charging device for charging the surface of the electrophotographic photoreceptor; An electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and The transfer device transfers the toner image to the surface of a recording medium.

Images