Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that can be satisfactorily positively electrified even when positive electrification and negative electrification are repeated and is excellent in wear resistance and storage property in a high temperature environment.SOLUTION: An electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer and contains a charge generating agent, an electron transport agent, a binder resin, a hole transport agent, and an addition agent. The electron transport agent includes a compound represented by the general formula (1). The binder resin includes a polycarbonate resin having a main chain and a terminal group represented by a specific structure. The addition agent includes a compound represented by a specific structure.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. [Background technology]

[0002] An electrophotographic photoreceptor is used as an image carrier in an electrophotographic image forming apparatus (for example, a printer or a multifunction machine). The electrophotographic photoreceptor includes a photosensitive layer. The electrophotographic photoreceptor included in the image forming apparatus described in Patent Document 1 contains a bisphenol Z type polycarbonate resin as a binder resin at least in the photosensitive layer which is the surface layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-234538 Summary of the Invention [Problem to be solved by the invention]

[0004] However, through investigations by the present inventors, it was found that the electrophotographic photosensitive member provided in the image forming apparatus described in Patent Document 1 is insufficient in terms of positive charging property when positive and negative charging are repeated, wear resistance, and storage property in a high-temperature environment.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photoreceptor which can be positively charged well even when positive and negative charging are repeated, and which has excellent wear resistance and storage properties in a high-temperature environment. Another object of the present invention is to provide a process cartridge and an image forming apparatus which are provided with such an electrophotographic photoreceptor and can form good images. [Means for solving the problem]

[0006] The electrophotographic photoreceptor of the present invention comprises a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer and contains a charge generating material, an electron transport material, a binder resin, a hole transport material, and an additive. The electron transport material contains a compound represented by general formula (1). The binder resin contains a polycarbonate resin having a main chain and an end group represented by general formula (10). The additive contains a compound represented by general formula (31), (32), or (33).

[0007] [ka]

[0008] In the general formula (1), R 1 and R 2 each independently represents an aryl group optionally substituted with 1 to 5 substituents selected from the group consisting of a halogen atom, an alkyl group, and an alkoxy group, a hydrogen atom, an alkyl group, a heterocyclic group, an alkoxy group, an aralkyl group, or an allyl group.

[0009] [ka]

[0010] In the general formula (10), R 101 , R 102 , R 103 , and R 104 R each independently represents an alkyl group having 1 to 3 carbon atoms which may be substituted with a halogen atom, a hydrogen atom, or an aryl group having 6 to 14 carbon atoms. 103 and R 104 may be bonded to each other to form a divalent group represented by general formula (X). 105 and R 106each represents an alkyl group having 1 to 3 carbon atoms. m1 and m2 each independently represent 0 or 1. W represents a single bond, -O-, or -CO-. n represents a number greater than 0 and less than 100. When n represents 100, the end group is a first end group having a halogen atom. When n represents a number greater than 0 and less than 100, the end group is the first end group having a halogen atom, or a second end group not having a halogen atom.

[0011] [ka]

[0012] In the general formula (X), t represents an integer of 1 or more and 3 or less.

[0013] [ka]

[0014] In the general formula (31), R 311 , R 312 , and R 313 Each of r1, r2, and r3 independently represents an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and each of r1, r2, and r3 independently represents an integer of 0 to 5. 321 , R 322 , R 323 , R 324 , R 325 , R 326 , R 327 , R 328 , and R 329 Each of R independently represents a hydrogen atom, a hydroxyl group, a halogen atom, or an alkyl group having 1 to 6 carbon atoms. 331 , R 335 , R 336 , and R 340 each independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms which may be substituted with an aryl group having from 6 to 14 carbon atoms, or a nitro group; R 332 , R 333 , R334 , R 337 , R 338 , and R 339 each independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms which may be substituted with an aryl group having from 6 to 14 carbon atoms, an aryl group having from 6 to 14 carbon atoms, or a nitro group.

[0015] The process cartridge of the present invention includes at least one selected from the group consisting of a charging device, an exposure device, a developing device, a transfer device, a cleaning member, and a static eliminator, and the electrophotographic photosensitive member described above.

[0016] The image forming apparatus of the present invention includes an image carrier, a charging device, an exposure device, a developing device, and a transfer device. The charging device charges the surface of the image carrier to a positive polarity. The exposure device exposes the charged surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier. The developing device develops the electrostatic latent image as a toner image. The transfer device transfers the toner image from the image carrier to a transferee. The image carrier is the electrophotographic photosensitive member already described. Effect of the Invention

[0017] The electrophotographic photoreceptor of the present invention can be positively charged well even when it is repeatedly positively charged and negatively charged, and has excellent wear resistance and storage stability in a high-temperature environment. Furthermore, the process cartridge and image forming apparatus of the present invention equipped with such an electrophotographic photoreceptor can form a good image. [Brief description of the drawings]

[0018] [Figure 1] 1 is a partial cross-sectional view showing an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Diagram 2] 1 is a partial cross-sectional view showing an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Diagram 3] 1 is a partial cross-sectional view showing an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Figure 4]FIG. 11 is a cross-sectional view showing an example of an image forming apparatus according to a second embodiment of the present invention. [Diagram 5] 5 is a diagram showing an image carrier and a cleaning member shown in FIG. 4, and a control device. FIG. [Figure 6] 6 is a time chart showing the control of the cleaning member in a printing mode and a cleaning mode. FIG. [Figure 7] 5 is a flow chart showing control of the image forming apparatus shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be practiced with appropriate modifications within the scope of the object of the present invention. Hereinafter, the compound and its derivatives may be collectively referred to by adding "system" after the compound name. In addition, when the compound name is followed by "system" to represent the name of a polymer, it means that the repeating unit of the polymer is derived from the compound or its derivative. "Independently" in the explanation of the general formula means that they may be the same or different. Each component described in the specification may be used alone or in combination of two or more types.

[0020] First, the substituents used in this specification will be described. Examples of halogen atoms (halogen groups) include fluorine atoms (fluoro groups), chlorine atoms (chloro groups), bromine atoms (bromo groups), and iodine atoms (iodo groups).

[0021] Unless otherwise specified, the alkyl group having 1 to 8 carbon atoms, the alkyl group having 1 to 6 carbon atoms, the alkyl group having 1 to 4 carbon atoms, and the alkyl group having 1 to 3 carbon atoms are each linear or branched and unsubstituted. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylpropyl group, a 2-ethylpropyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group, a 2,2-dimethylpropyl group, an n-hexyl group, a 1-methylpentyl group, a 2 ... Examples of alkyl groups having 1 to 6 carbon atoms, examples of alkyl groups having 1 to 4 carbon atoms, and examples of alkyl groups having 1 to 3 carbon atoms are groups having the corresponding number of carbon atoms among the groups mentioned as examples of alkyl groups having 1 to 8 carbon atoms.

[0022] The alkoxy group having 1 to 8 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the alkoxy group having 1 to 3 carbon atoms are each linear or branched and unsubstituted unless otherwise specified. Examples of the alkoxy group having 1 to 8 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, a 1-methylbutoxy group, a 2-methylbutoxy group, a 3-methylbutoxy group, a 1-ethylpropoxy group, a 2-ethylpropoxy group, a 1,1-dimethylpropoxy group, a 1,2-dimethylpropoxy group, a 2,2-dimethylpropoxy group, an n-hexyloxy group, a 1-methylpentyloxy group, a 2 ... Examples of alkoxy groups having 1 to 6 carbon atoms and examples of alkoxy groups having 1 to 3 carbon atoms are groups having the corresponding carbon atom numbers among the groups mentioned as examples of alkoxy groups having 1 to 8 carbon atoms.

[0023] The aryl group having 6 to 14 carbon atoms and the aryl group having 6 to 10 carbon atoms are each unsubstituted unless otherwise specified. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an indacenyl group, a biphenylenyl group, an acenaphthylenyl group, an anthryl group, and a phenanthryl group. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group.

[0024] The aralkyl group having 7 to 20 carbon atoms and the aralkyl group having 7 to 13 carbon atoms are each unsubstituted unless otherwise specified. The aralkyl group having 7 to 20 carbon atoms is, for example, an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 14 carbon atoms. The aralkyl group having 7 to 13 carbon atoms is, for example, an alkyl group having 1 to 3 carbon atoms substituted with an aryl group having 6 to 10 carbon atoms.

[0025] The 5-membered to 14-membered heterocyclic group and the 5-membered or 6-membered heterocyclic group are each unsubstituted unless otherwise specified. Examples of the 5-membered to 14-membered heterocyclic group include a 5-membered or 6-membered monocyclic heterocyclic group containing 1 to 3 heteroatoms other than carbon atoms; a heterocyclic group in which two such monocyclic heterocyclic rings are condensed; a heterocyclic group in which such a monocyclic heterocyclic ring is condensed with a 5-membered or 6-membered monocyclic hydrocarbon ring; a heterocyclic group in which three such monocyclic heterocyclic rings are condensed; a heterocyclic group in which two such monocyclic heterocyclic rings are condensed with one 5-membered or 6-membered monocyclic hydrocarbon ring; or a heterocyclic group in which one such monocyclic heterocyclic ring is condensed with two 5-membered or 6-membered monocyclic hydrocarbon rings. Specific examples of the 5- to 14-membered heterocyclic group include a piperidinyl group, a piperazinyl group, a morpholinyl group, a thiophenyl group, a furanyl group, a pyrrolyl group, an imidazolyl group, a pyrazolyl group, an isothiazolyl group, an isoxazolyl group, an oxazolyl group, an isoxazolyl group, a thiazolyl group, an isothiazolyl group, a furazanyl group, a pyranyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, an indolyl group, and a 1H-indazolyl group. Examples of the heterocyclic group include an isoindolyl group, a chromenyl group, a quinolinyl group, an isoquinolinyl group, a purinyl group, a pteridinyl group, a triazolyl group, a tetrazolyl group, a 4H-quinolizinyl group, a naphthyridinyl group, a benzofuranyl group, a 1,3-benzodioxolyl group, a benzoxazolyl group, a benzothiazolyl group, a benzimidazolyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenazinyl group, and a phenanthrolinyl group. The 5- or 6-membered heterocyclic group is a group having the corresponding number of ring members among the groups described as examples of the heterocyclic group having 5 to 14 members. The substituents used in this specification have been described above.

[0026] [First embodiment: electrophotographic photoreceptor] The first embodiment of the present invention relates to an electrophotographic photoreceptor (hereinafter, may be referred to as a photoreceptor). The structure of a photoreceptor 1 of the first embodiment will be described below with reference to Fig. 1 to Fig. 3. Fig. 1 to Fig. 3 each show a partial cross-sectional view of the photoreceptor 1.

[0027] 1, the photoreceptor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photoreceptor 3 is a single layer. The photoreceptor 1 is a single-layer type electrophotographic photoreceptor including the photosensitive layer 3 which is a single layer.

[0028] As shown in Fig. 2, the photoreceptor 1 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2 and the photosensitive layer 3. The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. As shown in Fig. 1, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, as shown in Fig. 2, the photosensitive layer 3 may be provided on the conductive substrate 2 via the intermediate layer 4.

[0029] As shown in Fig. 3, the photoreceptor 1 may further include a protective layer 5 in addition to the conductive substrate 2 and the photosensitive layer 3. The protective layer 5 is provided on the photosensitive layer 3. As shown in Figs. 1 and 2, the photosensitive layer 3 may be provided as the outermost layer of the photoreceptor 1. Alternatively, as shown in Fig. 3, the protective layer 5 may be provided as the outermost layer of the photoreceptor 1.

[0030] The thickness of the photosensitive layer 3 is not particularly limited, but is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. The structure of the photoreceptor 1 has been described above with reference to FIGS.

[0031] The photoreceptor will be described in more detail below. The photosensitive layer contains a charge generating material, an electron transport material, a binder resin, a hole transport material, and additives. The photosensitive layer may contain additives as necessary. The charge generating material, the electron transport material, the binder resin, the hole transport material, and the additives will be described below.

[0032] (Charge generating material) Examples of the charge generating agent include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azulenium pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon), pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments.

[0033] Examples of phthalocyanine pigments include metal-free phthalocyanine and metal phthalocyanine. Examples of metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Metal-free phthalocyanine is represented by the chemical formula (CGM-1). Titanyl phthalocyanine is represented by the chemical formula (CGM-2).

[0034] [ka]

[0035] [ka]

[0036] The phthalocyanine pigment may be crystalline or non-crystalline. Examples of the metal-free phthalocyanine crystals include X-type crystals of metal-free phthalocyanine (hereinafter, may be referred to as X-type metal-free phthalocyanine). Examples of the titanyl phthalocyanine crystals include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter, may be referred to as α-type, β-type, and Y-type titanyl phthalocyanine, respectively).

[0037] For example, in a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoreceptor having sensitivity in a wavelength region of 700 nm or more. As the charge generating agent, a phthalocyanine pigment is preferable because it has a high quantum yield in the wavelength region of 700 nm or more, a metal-free phthalocyanine or a titanyl phthalocyanine is more preferable, an X-type metal-free phthalocyanine or a Y-type titanyl phthalocyanine is even more preferable, and a Y-type titanyl phthalocyanine is particularly preferable.

[0038] The Y-type titanyl phthalocyanine has a main peak at, for example, 27.2° of Bragg angle (2θ±0.2°) in the CuKα characteristic X-ray diffraction spectrum. The main peak in the CuKα characteristic X-ray diffraction spectrum is the peak having the first or second largest intensity in the range of Bragg angle (2θ±0.2°) from 3° to 40°. The Y-type titanyl phthalocyanine does not have a peak at 26.2° in the CuKα characteristic X-ray diffraction spectrum.

[0039] The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, a sample (titanyl phthalocyanine) is loaded into a sample holder of an X-ray diffractometer (for example, Rigaku Corporation's "RINT (registered trademark) 1100"), and the X-ray diffraction spectrum is measured under the conditions of an X-ray tube Cu, a tube voltage of 40 kV, a tube current of 30 mA, and a wavelength of CuKα characteristic X-ray of 1.542 Å. The measurement range (2θ) is, for example, 3° to 40° (start angle 3°, stop angle 40°), and the scanning speed is, for example, 10° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0040] The content of the charge generating agent is preferably from 0.1 to 50 parts by mass, and more preferably from 1 to 10 parts by mass, relative to 100 parts by mass of the binder resin.

[0041] (Electron transport agent) The electron transport agent includes a compound represented by general formula (1) (hereinafter, may be referred to as electron transport agent (1)).

[0042] [ka]

[0043] In general formula (1), R 1 and R 2 each independently represents an aryl group optionally substituted with 1 to 5 substituents selected from the group consisting of a halogen atom, an alkyl group, and an alkoxy group; a hydrogen atom; an alkyl group; a heterocyclic group; an alkoxy group; an aralkyl group; or an allyl group.

[0044] By containing the electron transport agent (1) in the photosensitive layer, the photosensitive body can be positively charged well even when the photosensitive body is repeatedly positively and negatively charged. The photosensitive body capable of being positively charged well even when the photosensitive body is repeatedly positively and negatively charged is particularly suitable for use in the image forming apparatus of the second embodiment described later. Specifically, the photosensitive body is particularly suitable for use in an image forming apparatus having a configuration in which, in the printing mode, the charging device charges the surface of the photosensitive body to a positive polarity, and a negative first voltage (a voltage having a polarity opposite to that of the toner charging polarity) is applied to the cleaning member. When the photosensitive body is provided in such an image forming apparatus, in the printing mode, the surface of the photosensitive body is repeatedly charged to a positive polarity by the charging device, and the potential of the photosensitive body is repeatedly lowered to a negative polarity by contact with the cleaning member to which the negative first voltage is applied. Therefore, the photosensitive body is repeatedly positively and negatively charged. As already described, the photosensitive body of the first embodiment is positively charged well even when the photosensitive body is repeatedly positively and negatively charged. Therefore, even when the photoconductor of the first embodiment is provided in the image forming apparatus of the second embodiment, it can be suitably charged to a desired positive potential in the charging step of image formation.

[0045] In addition to the charge transport agent (1), the photosensitive layer contains a compound represented by general formula (31), (32), or (33) (hereinafter, these may be referred to as additives (31), (32), or (33)). Hereinafter, "additives (31), (32), or (33)" may be referred to as "predetermined additives". When the photosensitive layer contains the charge transport agent (1) and the predetermined additives, the positive charging property of the photoreceptor can be particularly improved when the photoreceptor is repeatedly positively and negatively charged. Furthermore, when the photosensitive layer contains the charge transport agent (1) and the predetermined additives, the deterioration of the photosensitive layer and the deformation of the photosensitive layer due to contact with a member of the image forming apparatus (e.g., a cleaning member) are suppressed even in a high-temperature environment. An image forming apparatus equipped with such a photoreceptor is unlikely to cause a malfunction even when it is transported, stored, or installed in a high-temperature environment. Furthermore, when the photosensitive layer contains the charge transport agent (1) and the predetermined additives, the wear resistance of the photoreceptor can be improved.

[0046] R in general formula (1) 1 and R 2 The aryl group represented by the formula (I) is, for example, an aryl group having 6 to 14 carbon atoms. The aryl group having 6 to 14 carbon atoms is preferably a phenyl group or a naphthyl group. The naphthyl group is preferably a 1-naphthyl group or a 2-naphthyl group.

[0047] R 1 and R 2The aryl group represented by may be substituted with 1 to 5 substituents selected from the group consisting of halogen atoms, alkyl groups, and alkoxy groups. The halogen atom as the substituent is preferably a chlorine atom or a bromine atom. The alkyl group as the substituent is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group. The alkoxy group as the substituent is preferably an alkoxy group having 1 to 6 carbon atoms, more preferably an alkoxy group having 1 to 3 carbon atoms, and even more preferably a methoxy group. The group consisting of halogen atoms, alkyl groups, and alkoxy groups is preferably a group consisting of halogen atoms, alkyl groups having 1 to 6 carbon atoms, and alkoxy groups having 1 to 6 carbon atoms, more preferably a group consisting of halogen atoms, alkyl groups having 1 to 3 carbon atoms, and alkoxy groups having 1 to 3 carbon atoms, and is particularly preferably a group consisting of chlorine atoms, bromine atoms, methyl groups, and methoxy groups. R 1 and R 2 The number of the substituents possessed by the aryl group represented by is preferably one or two.

[0048] R 1 and R 2 The alkyl group represented by the formula (I) is, for example, an alkyl group having from 1 to 6 carbon atoms. As the alkyl group having from 1 to 6 carbon atoms, an alkyl group having from 1 to 4 carbon atoms is preferable, and a methyl group, an n-propyl group, or a tert-butyl group is more preferable.

[0049] R 1 and R 2The heterocyclic group represented by is, for example, a 5-membered to 14-membered heterocyclic group. As the 5-membered to 14-membered heterocyclic group, a 5-membered to 14-membered heterocyclic group containing at least one heteroatom other than carbon atoms is preferred, a 5-membered to 6-membered heterocyclic group containing at least one heteroatom other than carbon atoms is more preferred, and a 5-membered to 6-membered monocyclic heterocyclic group containing at least one heteroatom other than carbon atoms is even more preferred. The heteroatom is preferably at least one selected from the group consisting of a nitrogen atom, a sulfur atom, and an oxygen atom, more preferably at least one selected from the group consisting of a sulfur atom and an oxygen atom, and even more preferably a sulfur atom or an oxygen atom. As the 5-membered to 14-membered heterocyclic group, a thiophenyl group or a furanyl group is more preferred, and a 2-thiophenyl group or a 2-furanyl group is particularly preferred.

[0050] R 1 and R 2 The alkoxy group represented by the formula (I) is, for example, an alkoxy group having from 1 to 6 carbon atoms. As the alkoxy group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 3 carbon atoms is preferable, and a methoxy group is more preferable.

[0051] R 1 and R 2 The aralkyl group represented by the formula (I) is, for example, an aralkyl group having 7 to 20 carbon atoms. As the aralkyl group having 7 to 20 carbon atoms, an aralkyl group having 7 to 13 carbon atoms is preferable, and a benzyl group, a phenylethyl group, or a naphthylmethyl group is more preferable.

[0052] R 1 and R 2 The allyl group represented by is represented by the chemical formula "CH2=CH-CH2-".

[0053] In order to improve the positive chargeability, abrasion resistance, and storage stability in a high-temperature environment when positive and negative charging are repeated, R 1 and R 2each independently represents an aryl group having 6 to 14 carbon atoms, which may be substituted with 1 to 5 substituents selected from the group consisting of a halogen atom, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms; an alkyl group having 1 to 6 carbon atoms; or a heterocyclic group having 5 to 14 members. For the same reason, in general formula (1), R 1 represents an aryl group having 6 to 14 carbon atoms; an alkyl group having 1 to 6 carbon atoms; or a heterocyclic group having 5 to 14 members; R 2 more preferably represents an aryl group having 6 to 14 carbon atoms which may be substituted with one or two substituents selected from the group consisting of a halogen atom, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms; or an alkyl group having 1 to 6 carbon atoms.

[0054] In order to improve the positive chargeability, abrasion resistance, and storage stability in a high-temperature environment when positive and negative charging are repeated, R 1 and R 2 Each of R preferably independently represents an aryl group having 6 to 14 carbon atoms, which may be substituted with one or two halogen atoms; or an alkyl group having 1 to 6 carbon atoms. For the same reason, in the general formula (1), R 1 represents an aryl group having 6 to 14 carbon atoms; or an alkyl group having 1 to 6 carbon atoms; R 2 more preferably represents an aryl group having 6 to 14 carbon atoms which may be substituted with one or two halogen atoms; or an alkyl group having 1 to 6 carbon atoms.

[0055] Suitable examples of the electron transport agent (1) for improving the positive chargeability when positive and negative charging are repeated, the abrasion resistance, and the storage stability in a high-temperature environment include compounds represented by chemical formulas (ETM1) to (ETM31) (hereinafter, these may be referred to as electron transport agents (ETM1) to (ETM31), respectively).

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] More suitable examples of the electron transport material (1) for improving the positive chargeability when positive and negative charging are repeated, the abrasion resistance, and the storage stability in a high-temperature environment include the electron transport materials (ETM1), (ETM2), (ETM6), (ETM7), (ETM8), (ETM19), (ETM22), (ETM23), (ETM24), (ETM28), and (ETM29).

[0061] The content of the electron transport agent is preferably 5 parts by mass or more and 150 parts by mass or less, more preferably 10 parts by mass or more and 80 parts by mass or less, and even more preferably 20 parts by mass or more and 60 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0062] The photosensitive layer may contain only the electron transport material (1) as the electron transport material. The photosensitive layer may further contain, in addition to the electron transport material (1), other electron transport materials as the electron transport material. Examples of the electron transport material other than the electron transport material (1) include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, and dibromomaleic anhydride. Examples of the quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds.

[0063] (binder resin) The binder resin contains a polycarbonate resin having a main chain represented by general formula (10) and terminal groups.

[0064] [ka]

[0065] In general formula (10), R 101 , R 102 , R 103 , and R 104 R each independently represents an alkyl group having 1 to 3 carbon atoms which may be substituted with a halogen atom, a hydrogen atom, or an aryl group having 6 to 14 carbon atoms. 103 and R 104 may be bonded to each other to form a divalent group represented by general formula (X). 105 and R 106Each of m1 and m2 independently represents an alkyl group having 1 to 3 carbon atoms. Each of m1 and m2 independently represents 0 or 1. W represents a single bond, -O-, or -CO-. n represents a number greater than 0 and less than 100. When n represents 100, the terminal group is a first terminal group having a halogen atom. When n represents a number greater than 0 and less than 100, the terminal group is a first terminal group having a halogen atom, or a second terminal group not having a halogen atom. In the general formula (X), t represents an integer greater than 1 and less than 3.

[0066] [ka]

[0067] Hereinafter, the "main chain represented by general formula (10)" may be referred to as the "main chain (10)". Also, a "polycarbonate resin having a main chain represented by general formula (10) and an end group, in which when n in general formula (10) is 100, the end group is a first end group having a halogen atom, and when n is a number greater than 0 and less than 100, the end group is a first end group having a halogen atom or a second end group not having a halogen atom" may be referred to as the "polycarbonate resin (PC)". Also, the "repeating unit represented by general formula (11)" and the "repeating unit represented by general formula (12)" contained in general formula (10) may be referred to as the "repeating unit (11)" and the "repeating unit represented by general formula (12)", respectively. R in general formulas (11) and (12) 101 ~R 106 , m1, m2, and W each represent R in general formula (10). 101 ~R 106 , m1, m2, and W.

[0068] [ka]

[0069] The photosensitive layer contains polycarbonate resin (PC), which improves the abrasion resistance of the photoreceptor. Also, the photosensitive layer contains polycarbonate resin (PC) in addition to the electron transport material (1) and the specified additives, which improves the positive chargeability of the photoreceptor when positively and negatively charged, and the high-temperature storage stability.

[0070] The main chain (10) will be described below. In the general formula (10), R 101 , R 102 , R 103 , and R 104 The alkyl group having 1 to 3 carbon atoms represented by R is preferably a methyl group or an ethyl group. 101 , R 102 , R 103 , and R 104 The alkyl group having 1 to 3 carbon atoms represented by the formula (I) may be substituted with a halogen atom.

[0071] In general formula (10), R 101 , R 102 , R 103 , and R 104 The aryl group having 6 to 14 carbon atoms represented by is preferably an aryl group having 6 to 10 carbon atoms, more preferably a phenyl group.

[0072] In general formula (10), R 103 and R 104 The divalent group represented by general formula (X) in which R are bonded to each other to form a ring is a divalent group represented by chemical formula (X-1), (X-2), or (X-3). As such a divalent group, a divalent group represented by chemical formula (X-2) is preferable. That is, in general formula (X), t preferably represents 2. In chemical formulas (X-1), (X-2), and (X-3), * represents a bond, and more specifically, R 103 and R 104 represents a bond to the phenylene group to which the carbon atom to which is bonded is bonded.

[0073] [ka]

[0074] In general formula (10), R 105 and R 106 The alkyl group having 1 to 3 carbon atoms represented by is preferably a methyl group.

[0075] Preferably, m1 and m2 each represent 0. It is also preferred that m1 and m2 each represent 1.

[0076] W preferably represents a single bond or -O-.

[0077] As already mentioned, n is a number greater than 0 and equal to or less than 100. Since n is greater than 0, the polycarbonate resin (PC) essentially contains the repeating unit (11). When n is 100, the polycarbonate resin (PC) does not contain the repeating unit (12) and is a homopolymer. When n is a number greater than 0 and less than 100, that is, when n is not 100, the polycarbonate resin (PC) contains the repeating unit (12) and is a copolymer. When n is not 100, n is preferably a number greater than 20, and more preferably a number greater than 40. When n is not 100, n is preferably a number less than 80, and more preferably a number less than 60. n represents the percentage (unit: mol%) of the number of repeating units (11) relative to the total number of repeating units (11) and (12). In order to improve the abrasion resistance of the photoreceptor, it is preferred that the main chain (10) contains only the repeating units (11) and (12).

[0078] In general formula (10), R 101 and R 102 R preferably each independently represents an alkyl group having 1 to 3 carbon atoms, or a hydrogen atom. 101 and R 102 More preferably, R represents the same group. 103 and R 104 R preferably each independently represents an alkyl group having 1 to 3 carbon atoms, or a hydrogen atom. 103 and R 104R preferably combine with each other to form a divalent group represented by general formula (X-2). That is, in general formula (X), t preferably represents 2. 105 and R 106 each preferably represents a methyl group. m1 and m2 preferably represent the same 0 or 1. W preferably represents a single bond or -O-. n preferably represents a number of 40 to 80, or 100.

[0079] The repeating unit (11) contained in the main chain (10) is preferably a repeating unit represented by chemical formulas (11-1) to (11-6).The repeating unit (12) contained in the main chain (10) is preferably a repeating unit represented by chemical formulas (12-1) to (12-4).

[0080] [ka]

[0081] [ka]

[0082] When n in general formula (10) is a number greater than 0 and less than 100, the main chain (10) is preferably a main chain represented by general formulas (10-1) to (10-6) (hereinafter, each may be referred to as main chains (10-1) to (10-6)). When n in general formula (10) is 100, the main chain (10) is preferably a main chain represented by general formulas (10-A) to (10-B) (hereinafter, each may be referred to as main chains (10-A) to (10-B)).

[0083] [ka]

[0084] n1 in the general formula (10-1), n2 in the general formula (10-2), n3 in the general formula (10-3), n4 in the general formula (10-4), n5 in the general formula (10-5), and n6 in the general formula (10-6) each represent a number greater than 0 and less than 100. Preferred examples of n1, n2, n3, n4, n5, and n6 are the same as the preferred examples of n in the general formula (10) already described.

[0085] [ka]

[0086] The main chain (10) has been described above.

[0087] Next, the first end group and the second end group will be described. The first end group has a halogen atom. The second end group does not have a halogen atom. As already mentioned, when n in the general formula (10) represents 100 (i.e., when the polycarbonate resin (PC) is a homopolymer), the end group is the first end group. As already mentioned, when n represents a number greater than 0 and less than 100 (i.e., when the polycarbonate resin (PC) is a copolymer), the end group is the first end group or the second end group. In order to improve the positive chargeability, high-temperature storage property, and abrasion resistance when positively and negatively charged, the end group is preferably the first end group or the second end group, and more preferably the first end group.

[0088] First, the first terminal group will be described. The halogen atom of the first terminal group is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a fluorine atom. An example of the first terminal group is a terminal group represented by general formula (T1) (hereinafter, sometimes referred to as terminal group (T1)).

[0089] [ka]

[0090] In general formula (T1), R 111represents a hydrogen atom, a fluorine atom, or a methyl group, and r represents an integer of 1 or more and 10 or less.

[0091] In general formula (T1), R 111 preferably represents a fluorine atom. r preferably represents an integer of 5 or more and 10 or less, and more preferably represents an integer of 6 or more and 8 or less.

[0092] The terminal group (T1) is preferably a terminal group represented by chemical formula (T1-1) (hereinafter, sometimes referred to as terminal group (T1-1)).

[0093] [ka]

[0094] Another example of the first terminal group is a terminal group represented by general formula (T2) (hereinafter, sometimes referred to as terminal group (T2)).

[0095] [ka]

[0096] In general formula (T2), R 112 , R 113 , and R 114 each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and p and q each independently represent an integer of 1 or more and 10 or less.

[0097] In general formula (T2), R 112 , R 113 , and R 114 Each of R independently preferably represents a fluorine atom or a trifluoromethyl group. 112 , R 113 , and R 114 Two of the groups represent trifluoromethyl groups, and R 112 , R 113 , and R 114It is more preferable that one of p and q represents a fluorine atom. It is preferable that p and q each independently represent an integer of 1 or more and 5 or less, and more preferably 1 or 2.

[0098] The terminal group (T2) is preferably a terminal group represented by chemical formula (T2-1) (hereinafter, sometimes referred to as terminal group (T2-1)).

[0099] [ka]

[0100] Next, the second terminal group will be described. An example of the second terminal group is a terminal group represented by chemical formula (T3) (hereinafter, sometimes referred to as terminal group (T3)).

[0101] [ka]

[0102] In the above general formulae (T1) and (T2) and chemical formulae (T1-1), (T2-1), and (T3), * represents a bond to the main chain (10). The bond represented by * is directly bonded to the -CO- group at one end of the main chain (10). The bond represented by * is bonded to the -O- group at the other end of the main chain (10) via a carbonyl group. The first terminal group and the second terminal group have been described above.

[0103] Suitable examples of the polycarbonate resin (PC) include the following polycarbonate resins (PC-A) to (PC-K).

[0104] In the polycarbonate resin (PC-A), the main chain (10) is the main chain (10-1), the terminal group is the first terminal group, and the first terminal group is the terminal group (T2-1).

[0105] In the polycarbonate resin (PC-B), the main chain (10) is the main chain (10-2), the terminal group is the first terminal group, and the first terminal group is the terminal group (T2-1).

[0106] In the polycarbonate resin (PC-C), the main chain (10) is the main chain (10-3), the terminal group is the first terminal group, and the first terminal group is the terminal group (T2-1).

[0107] In the polycarbonate resin (PC-D), the main chain (10) is the main chain (10-1), the terminal group is the first terminal group, and the first terminal group is the terminal group (T1-1).

[0108] In the polycarbonate resin (PC-E), the main chain (10) is the main chain (10-1), the terminal group is the second terminal group, and the second terminal group is the terminal group (T3).

[0109] In the polycarbonate resin (PC-F), the main chain (10) is the main chain (10-2), the terminal group is the second terminal group, and the second terminal group is the terminal group (T3).

[0110] In the polycarbonate resin (PC-G), the main chain (10) is the main chain (10-4), the terminal group is the second terminal group, and the second terminal group is the terminal group (T3).

[0111] In the polycarbonate resin (PC-H), the main chain (10) is the main chain (10-5), the terminal group is the second terminal group, and the second terminal group is the terminal group (T3).

[0112] In the polycarbonate resin (PC-I), the main chain (10) is the main chain (10-6), the terminal group is the second terminal group, and the second terminal group is the terminal group (T3).

[0113] In the polycarbonate resin (PC-J), the main chain (10) is the main chain (10-A), the terminal group is the first terminal group, and the first terminal group is the terminal group (T1-1).

[0114] In the polycarbonate resin (PC-K), the main chain (10) is the main chain (10-B), the terminal group is the first terminal group, and the first terminal group is the terminal group (T2-1).

[0115] Further suitable examples of the polycarbonate resin (PC) include polycarbonate resins represented by the following chemical formulas (R1) to (R13) (hereinafter, each may be referred to as polycarbonate resin (R1) to (R13)). Rt in the chemical formulas (R1) to (R13) represents an end group represented by the chemical formula shown to the right of "Rt=".

[0116] [ka]

[0117] [ka]

[0118] [ka]

[0119] [ka]

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] [ka]

[0126] [ka]

[0127] [ka]

[0128] [ka]

[0129] When the polycarbonate resin (PC) is a copolymer, the polycarbonate resin (PC) may be a random copolymer, an alternating copolymer, a block copolymer, or a periodic copolymer.

[0130] The viscosity average molecular weight of the polycarbonate resin (PC) is preferably 10,000 or more, more preferably 20,000 or more, and particularly preferably 30,000 or more. When the viscosity average molecular weight of the polycarbonate resin (PC) is 10,000 or more, the abrasion resistance of the photoreceptor is improved. On the other hand, the viscosity average molecular weight of the polycarbonate resin (PC) is preferably 80,000 or less, more preferably 70,000 or less. When the viscosity average molecular weight of the polycarbonate resin (PC) is 80,000 or less, the binder resin is easily dissolved in a solvent for forming the photosensitive layer.

[0131] The photosensitive layer may contain only polycarbonate resin (PC) as the binder resin, or may further contain other binder resins. Examples of binder resins other than polycarbonate resins (PC) include thermoplastic resins (more specifically, polycarbonate resins other than polycarbonate resins (PC), polyarylate resins, styrene-based resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-vinyl acetate copolymers, polyester resins, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, and polyether resins), thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, and other crosslinkable thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic acid-based resins, and urethane-acrylic acid-based copolymers).

[0132] (Hole transport agent) Examples of hole transport agents include oxadiazole compounds (e.g., 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazole), styryl compounds (e.g., 9-(4-diethylaminostyryl)anthracene), carbazole compounds (e.g., polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (e.g., 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and triazole compounds.

[0133] In order to improve the positive chargeability when positive and negative charging are repeated, the abrasion resistance, and the storage stability in a high-temperature environment, the hole transport agent preferably contains a compound represented by general formula (21), (22), (23), (24), (25), (26), or (27). Hereinafter, the compounds represented by general formulas (21) to (27) may be referred to as hole transport agents (21) to (27), respectively.

[0134] [ka]

[0135] [ka]

[0136] In general formula (21), R 11 , R 12 , R 13 , R 14 , R 15 , and R 16 R each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group. 17 and R 18 each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. b1, b2, b3, and b4 each independently represent an integer of 0 to 5. b5 and b6 each independently represent an integer of 0 to 4. d and e each independently represent 0 or 1.

[0137] In the general formula (21), when b1 represents an integer of 2 or more and 5 or less, a plurality of R 11 may represent the same group or different groups. When b2 represents an integer of 2 to 5, multiple R 12 may represent the same group or different groups. When b3 represents an integer of 2 or more and 5 or less, multiple R 13 may represent the same group or different groups. When b4 represents an integer of 2 or more and 5 or less, 14may represent the same group or different groups. When b5 represents an integer of 2 to 4, multiple R 15 may represent the same group or different groups. When b6 represents an integer of 2 or more and 4 or less, 16 may represent the same group or different groups.

[0138] In general formula (21), R 11 , R 12 , R 13 , R 14 , R 15 , and R 16 R each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and further preferably represents a methyl group or an ethyl group. 17 and R 18 preferably represents a hydrogen atom. b1 and b2 preferably represent 0. b3 and b4 preferably represent 2. b5 and b6 preferably represent 0. d and e preferably represent 0.

[0139] In general formula (22), R 20 R represents a hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, an alkoxy group having from 1 to 8 carbon atoms, or a phenyl group which may be substituted with an alkyl group having from 1 to 8 carbon atoms. 21 , R 22 , and R 23 each independently represents an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms. f1, f2, and f3 each independently represent an integer of 0 to 5. f4 represents 0 or 1.

[0140] In the general formula (22), when f1 represents an integer of 2 or more and 5 or less, a plurality of R 21 may represent the same group or different groups. When f2 represents an integer of 2 to 5, multiple R 22 may represent the same group or different groups. When f3 represents an integer of 2 to 5, multiple R 23may represent the same group or different groups.

[0141] In general formula (22), R 20 R preferably represents a phenyl group. 21 , R 22 , and R 23 each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and further preferably represents a methyl group. f1 and f2 preferably represent 1. f3 preferably represents 0. As already mentioned, f4 represents 0 or 1.

[0142] In general formula (23), R 31 , R 32 , R 33 , R 34 , and R 35 each independently represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms; g1, g2, g3, g4, and g5 each independently represent an integer of 0 to 5.

[0143] In the general formula (23), when g1 represents an integer of 2 or more and 5 or less, a plurality of R 31 may represent the same group or different groups. When g2 represents an integer of 2 to 5, multiple R 32 may represent the same group or different groups. When g3 represents an integer of 2 to 5, multiple R 33 may represent the same group or different groups. When g4 represents an integer of 2 to 5, multiple R 34 may represent the same group or different groups. When g5 represents an integer of 2 to 5, multiple R 35 may represent the same group or different groups.

[0144] In general formula (23), R 31 , R 32 , R 33 , R 34 , and R 35each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and further preferably represents a methyl group. g1, g2, g3, g4, and g5 each preferably represent 1.

[0145] In general formula (24), R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. h1, h2, h4, and h5 each independently represent an integer of 0 to 5. h3 and h6 each independently represent an integer of 0 to 4.

[0146] In the general formula (24), when h1 represents an integer of 2 or more and 5 or less, a plurality of R 41 may represent the same group or different groups. When h2 represents an integer of 2 to 5, multiple R 42 may represent the same group or different groups. When h4 represents an integer of 2 to 5, multiple R 44 may represent the same group or different groups. When h5 represents an integer of 2 to 5, multiple R 45 may represent the same group or different groups. When h3 represents an integer of 2 to 4, multiple R 43 may represent the same group or different groups. When h6 represents an integer of 2 to 4, multiple R 46 may represent the same group or different groups.

[0147] In general formula (24), R 41 , R 42 , R 43 , R 44 , R 45 , and R 46each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and further preferably represents a methyl group or an ethyl group. each independently preferably represents an integer having 0 to 2. h3 and h6 preferably represent 0.

[0148] In general formula (25), R 71 , R 72 , R 73 , and R 74 each independently represents an alkyl group having 1 to 8 carbon atoms; j1, j2, j3, and j4 each independently represents an integer of 0 to 5.

[0149] In the general formula (25), when j1 represents an integer of 2 or more and 5 or less, a plurality of R 71 may represent the same group or different groups. When j2 represents an integer of 2 to 5, multiple R 72 may represent the same group or different groups. When j3 represents an integer of 2 to 5, multiple R 73 may represent the same group or different groups. When j4 represents an integer of 2 to 5, multiple R 74 may represent the same group or different groups.

[0150] In general formula (25), R 71 , R 72 , R 73 , and R 74 each independently preferably represents an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group. each independently preferably represents 0 or 1.

[0151] In general formula (26), R 81 , R 82 , and R 83 R each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. 84 and R85 each independently represents a phenyl group which may be substituted with an alkyl group having 1 to 8 carbon atoms, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms. k1, k2, and k3 each independently represent an integer of 0 to 5. k4 and k5 each independently represent 1 or 2.

[0152] In the general formula (26), when k1 represents an integer of 2 or more and 5 or less, a plurality of R 81 may represent the same group or different groups. When k2 represents an integer of 2 to 5, multiple R 82 may represent the same group or different groups. When k3 represents an integer of 2 to 5, multiple R 83 may represent the same group or different groups.

[0153] In general formula (26), R 81 , R 82 , and R 83 R each independently preferably represents an alkoxy group having 1 to 8 carbon atoms, more preferably represents an alkoxy group having 1 to 6 carbon atoms, and further preferably represents an ethoxy group. 84 and R 85 preferably represents a hydrogen atom. k1 and k2 preferably represent 0. k3 preferably represents 1. k4 and k5 preferably represent 1.

[0154] In general formula (27), R 61 , R 62 , and R 63 R each independently represents an alkyl group having 1 to 8 carbon atoms. 64 , R 65 , and R 66 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

[0155] In general formula (27), R 61 , R 62 , and R 63R each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and further preferably represents a methyl group. 64 , R 65 , and R 66 preferably represents a hydrogen atom.

[0156] More suitable examples of the hole transport agent include compounds represented by chemical formulas (HTM1) to (HTM10) (hereinafter, these may be referred to as hole transport agents (HTM1) to (HTM10), respectively).

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] The content of the hole transport agent is preferably from 10 parts by mass to 300 parts by mass, and more preferably from 10 parts by mass to 150 parts by mass, relative to 100 parts by mass of the binder resin.

[0161] (Additives) The additives include the predetermined additives already described. As already described, the photosensitive layer contains both the electron transport agent (1) and the predetermined additives, which improves the positive chargeability of the photoreceptor when it is repeatedly positively and negatively charged, the wear resistance, and the storage stability of the photoreceptor under high temperature conditions. General formulas (31), (32), and (33) are shown below, respectively.

[0162] [ka]

[0163] In general formula (31), R 311 , R 312 , and R 313 each independently represents an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. r1, r2, and r3 each independently represents an integer of 0 to 5.

[0164] When r1 is an integer between 2 and 5, multiple R 311 may represent the same group or different groups. When r2 represents an integer of 2 to 5, multiple R 312 may represent the same group or different groups. When r3 represents an integer of 2 to 5, multiple R 313 may represent the same group or different groups. R 311 , R 312 , and R 313 The bonding position of R is not particularly limited. 311 R may be located at any of the ortho, meta and para positions of the phenyl group, and is preferably located at the para position. 312 R may be located at any of the ortho, meta and para positions of the phenyl group, and is preferably located at the para position. 313 may be located at any of the ortho, meta and para positions of the phenyl group, and is preferably located at the para position.

[0165] In general formula (31), R 311 , R 312 , and R 313 each preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. Each of r1, r2, and r3 preferably represents 0 or 1.

[0166] In general formula (32), R 321 , R 322 , R 323 , R 324 , R 325 , R 326 , R 327 , R 328 , and R 329each independently represents a hydrogen atom, a hydroxyl group, a halogen atom, or an alkyl group having 1 to 6 carbon atoms.

[0167] R in general formula (32) 321 , R 322 , R 323 , R 324 , R 325 , R 326 , R 327 , R 328 and R 329 The halogen atom represented by is preferably a chlorine atom.

[0168] R in general formula (32) 321 , R 322 , R 323 , R 324 , R 325 , R 326 , R 327 , R 328 and R 329 The alkyl group having 1 to 6 carbon atoms represented by the formula (I) is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or a tert-butyl group.

[0169] In general formula (32), R 321 , R 322 , R 323 , R 324 , R 325 , R 326 , R 327 , R 328 , and R 329 It is preferable that each independently represents a hydrogen atom, a hydroxyl group, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.

[0170] In general formula (33), R 331 , R 335 , R 336 , and R 340 R each independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms which may be substituted with an aryl group having from 6 to 14 carbon atoms, or a nitro group. 332 , R 333 , R 334 , R 337 , R338 , and R 339 each independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms which may be substituted with an aryl group having from 6 to 14 carbon atoms, an aryl group having from 6 to 14 carbon atoms, or a nitro group.

[0171] R in general formula (33) 332 , R 333 , R 334 , R 337 , R 338 , and R 339 The aryl group having 6 to 14 carbon atoms represented by is preferably a phenyl group.

[0172] R in general formula (33) 331 ~R 340 The alkyl group having 1 to 6 carbon atoms represented by the formula (I) is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group. The alkyl group having 1 to 6 carbon atoms may be substituted with an aryl group having 6 to 14 carbon atoms.

[0173] In general formula (33), R 331 , R 335 , R 336 , and R 340 Each of R preferably represents a hydrogen atom. 332 , R 333 , R 334 , R 337 , R 338 , and R 339 each independently preferably represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0174] In order to improve the positive chargeability, abrasion resistance, and storage stability in high temperature environments of the photoconductor when it is repeatedly positively and negatively charged, additive (31) is preferably a compound represented by chemical formula (AD1) or (AD6). Additive (32) is preferably a compound represented by chemical formula (AD2) or (AD3). Additive (33) is preferably a compound represented by chemical formula (AD4) or (AD5). Hereinafter, the compounds represented by chemical formulas (AD1) to (AD6) may be referred to as additives (AD1) to (AD6), respectively.

[0175] [ka]

[0176] The melting point of the predetermined additive is preferably 90°C or more and 300°C or less, more preferably 100°C or more and 200°C or less, and even more preferably 117°C or more and 173°C or less. Usually, when a low molecular weight compound such as an additive is mixed with a binder resin, the glass transition point of the resulting mixture tends to be lower than the glass transition point of the binder resin itself. However, when the melting point of the predetermined additive is 90°C or more and 300°C or less, the decrease in the glass transition point of the resulting mixture can be suppressed. Therefore, when the predetermined additive and the binder resin having melting points of 90°C or more and 300°C or less are contained in the photosensitive layer, the decrease in the glass transition point of the photosensitive layer can be suppressed. As a result, the deterioration and deformation of the photosensitive layer can be particularly suppressed even in a high-temperature environment, and the storage property of the photoreceptor in a high-temperature environment is improved. The melting point of the predetermined additive is measured, for example, using a differential scanning calorimeter ("DSC7020" manufactured by Hitachi High-Tech Science Corporation). The starting point of the measured melting peak is taken as the melting point.

[0177] The content of the predetermined additive is preferably more than 0.0 parts by mass, and more preferably 0.5 parts by mass or more, relative to 100.0 parts by mass of the binder resin. The content of the predetermined additive is preferably 50.0 parts by mass or less, and more preferably 30.0 parts by mass or less, relative to 100.0 parts by mass of the binder resin.

[0178] The additive may include only the predetermined additive. The additive may further include additives other than the predetermined additives described above. Examples of additives other than the predetermined additives include radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, donors, surfactants, plasticizers, sensitizers, electron acceptor compounds, and leveling agents.

[0179] (Material Combination) In order to improve the positive chargeability, abrasion resistance, and storage stability in a high-temperature environment when positive and negative charging are repeated, it is preferable that the combination of the predetermined additive, the electron transport agent, and the binder resin is each of the combinations a-1 to a-30 and b-1 to b-32 shown in Tables 1 and 2. For the same reason, it is more preferable that the combination of the predetermined additive, the electron transport agent, and the binder resin is each of the combinations a-1 to a-30 and b-1 to b-32 shown in Tables 1 and 2, and that the charge generating agent is Y-type titanyl phthalocyanine.

[0180] In order to improve the positive chargeability, abrasion resistance, and storage stability in a high-temperature environment when positive and negative charging are repeated, it is preferable that the combination of the predetermined additive, hole transport agent, electron transport agent, and binder resin is each of combinations No. c-1 to c-43 and d-1 to d-45 shown in Tables 3 and 4. For the same reason, it is more preferable that the combination of the predetermined additive, hole transport agent, electron transport agent, and binder resin is each of combinations No. c-1 to c-43 and d-1 to d-45 shown in Tables 3 and 4, and the charge generating agent is Y-type titanyl phthalocyanine.

[0181] The meanings of the terms in Tables 1 to 4 are as follows: "No." indicates the combination number; "HTM" indicates a hole transport material; "ETM" indicates an electron transport material; and "resin" indicates a polycarbonate resin that is a binder resin.

[0182] [Table 1]

[0183] [Table 2]

[0184] [Table 3]

[0185] [Table 4]

[0186] (Conductive substrate) The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor. The conductive substrate may be made of a material having at least a surface portion having conductivity. An example of the conductive substrate is a conductive substrate made of a material having conductivity. Another example of the conductive substrate is a conductive substrate coated with a material having conductivity. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). Among these conductive materials, aluminum and aluminum alloys are preferred because they have good charge transfer from the photosensitive layer to the conductive substrate.

[0187] The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus. The shape of the conductive substrate may be, for example, a sheet or a drum. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

[0188] (Middle class) The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used in the intermediate layer. The presence of the intermediate layer makes it possible to maintain an insulating state sufficient to suppress leakage, while facilitating the flow of current generated when the photoreceptor is exposed to light, thereby suppressing an increase in resistance.

[0189] Inorganic particles include, for example, particles of metals (e.g., aluminum, iron, and copper), particles of metal oxides (e.g., titanium oxide, alumina, zirconium oxide, tin oxide, and zinc oxide), and particles of non-metal oxides (e.g., silica).

[0190] Examples of the resin for the intermediate layer are the same as the examples of the base resin. In order to form the intermediate layer and the photosensitive layer well, it is preferable that the resin for the intermediate layer is different from the base resin and the binder resin contained in the photosensitive layer. The intermediate layer may contain an additive. Examples of the additive contained in the intermediate layer are the same as the examples of the additive contained in the photosensitive layer.

[0191] (Photoreceptor manufacturing method) An example of a method for manufacturing a photoreceptor will be described. The method for manufacturing a photoreceptor includes a photosensitive layer forming step. In the photosensitive layer forming step, a coating liquid for forming a photosensitive layer (hereinafter, sometimes referred to as a coating liquid for a photosensitive layer) is prepared. The coating liquid for a photosensitive layer is applied onto a conductive substrate. Then, at least a part of the solvent contained in the applied coating liquid for a photosensitive layer is removed to form a photosensitive layer. The coating liquid for a photosensitive layer contains, for example, a charge generating agent, an electron transport agent, a hole transport agent, a binder resin, a predetermined additive, and a solvent. The coating liquid for a photosensitive layer is prepared by dissolving or dispersing the charge generating agent, the electron transport agent, the hole transport agent, the binder resin, and the predetermined additive in a solvent. The coating liquid for a photosensitive layer may further contain additives other than the predetermined additives as necessary.

[0192] The solvent contained in the coating liquid for the photosensitive layer is not particularly limited, and examples thereof include alcohols (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbons (more specifically, n-hexane, octane, cyclohexane, etc.), aromatic hydrocarbons (more specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, etc.), ethers (more specifically, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc.), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), esters (more specifically, ethyl acetate, methyl acetate, etc.), dimethylformaldehyde, dimethylformamide, and dimethylsulfoxide.

[0193] The coating solution for the photosensitive layer is prepared by mixing the respective components and dispersing them in a solvent. For example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used for mixing or dispersing.

[0194] The method for applying the coating solution for the photosensitive layer is not particularly limited, but examples thereof include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

[0195] Methods for removing at least a part of the solvent contained in the coating solution for photosensitive layer include, for example, heating, reducing pressure, or a combination of heating and reducing pressure. More specifically, a method for heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer can be mentioned. The temperature for heat treatment is, for example, 40°C or higher and 150°C or lower. The time for heat treatment is, for example, 3 minutes or higher and 120 minutes or lower.

[0196] The method for producing the photoreceptor may further include a step of forming an intermediate layer, if necessary. The step of forming the intermediate layer may be appropriately selected from known methods.

[0197] [Second embodiment: Image forming apparatus] Next, an image forming apparatus 110, which is an example of an image forming apparatus according to a second embodiment of the present invention, will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view of the image forming apparatus 110.

[0198] 4 includes a control device 10 (see FIG. 5), a feeding section 20, a conveying section 30, image forming units 40Y, 40M, 40C, and 40K, a transfer section 60, a belt cleaning section 70, a fixing section 80, and a paper discharge section 90. The belt cleaning section 70 will be described in detail in the description of the <printing mode and cleaning mode> below.

[0199] The control device 10 controls the operation of each part of the image forming apparatus 110 (more specifically, the feeding section 20, the conveying section 30, the image forming units 40Y, 40M, 40C, and 40K, the transfer section 60, the belt cleaning section 70, the fixing section 80, and the paper discharge section 90). The control device 10 is disposed at an appropriate position within the main body housing. The control device 10 includes, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and an input / output interface (not shown). The control device 10 executes control by performing various arithmetic processes based on the detection results of various sensors and preset programs.

[0200] The feeding unit 20 includes a cassette 22. The cassette 22 accommodates a plurality of recording media P. The feeding unit 20 feeds the recording media P from the cassette 22 to the transport unit 30. The recording media P is, for example, a sheet made of paper, cloth, or synthetic resin.

[0201] The conveying section 30 conveys the recording medium P to the image forming units 40Y, 40M, 40C, and 40K.

[0202] The image forming units 40Y, 40M, 40C, and 40K each include a corresponding image carrier 100Y, 100M, 100C, and 100K, a charging device 42Y, 42M, 42C, and 42K, an exposure device 44Y, 44M, 44C, and 44K, a developing device 46Y, 46M, 46C, and 46K, a cleaning device 48Y, 48M, 48C, and 48K, and a charge removing device 50Y, 50M, 50C, and 50K. Hereinafter, when there is no need to distinguish between them, the suffixes "Y", "M", "C", and "K" attached to each member of the image forming apparatus 110 will be omitted. For example, when there is no need to distinguish between them, each of the image forming units 40Y, 40M, 40C, and 40K will be described as an image forming unit 40.

[0203] The transfer unit 60 includes four transfer devices 62Y, 62M, 62C, and 62K, a drive roller 64, an endless transfer belt 66, a driven roller 67, and a tension roller 68. The transfer devices 62Y, 62M, 62C, and 62K are disposed on the inner periphery side of the transfer belt 66, and face the image carriers 100Y, 100M, 100C, and 100K via the transfer belt 66. The transfer belt 66 is stretched over the drive roller 64, the driven roller 67, and the tension roller 68. The transfer belt 66 rotates in the direction of the arrow (clockwise direction in FIG. 4) as the drive roller 64 rotates.

[0204] An image carrier 100 is provided at the center of the image forming unit 40. The image carrier 100 is provided so as to be rotatable in the direction of the arrow (counterclockwise in FIG. 4). Around the image carrier 100, a charging device 42, an exposure device 44, a developing device 46, a transfer device 62, a cleaning device 48, and a static elimination device 50 are provided in this order from the upstream side in the rotation direction of the image carrier 100.

[0205] The image carrier 100 is the photoreceptor 1 of the first embodiment. As already described, the photoreceptor 1 of the first embodiment can be positively charged well even when it is repeatedly positively and negatively charged, and has excellent abrasion resistance and storage stability in a high-temperature environment. Therefore, by providing such a photoreceptor 1 as the image carrier 100, the image forming apparatus 110 can form a good image on the recording medium P.

[0206] The charging device 42 positively charges the surface (for example, the peripheral surface) of the image carrier 100. The charging device 42 is, for example, a scorotron charger.

[0207] The exposure device 44 exposes the charged surface of the image carrier 100. As a result, an electrostatic latent image is formed on the surface of the image carrier 100. The electrostatic latent image is formed based on image data input to the image forming device 110.

[0208] The developing device 46 supplies toner to the surface of the image carrier 100 and develops the electrostatic latent image into a toner image. The toner is a positively charged toner. The developing device 46 is in contact with the surface of the image carrier 100. That is, the image forming apparatus 110 employs a contact development method. The developing device 46 is, for example, a developing roller.

[0209] When the developer is a one-component developer, the developing device 46 supplies toner, which is a one-component developer, to the electrostatic latent image formed on the image carrier 100. When the developer is a two-component developer, the developing device 46 supplies toner, of the toner and carrier contained in the two-component developer, to the electrostatic latent image formed on the image carrier 100. The toner image formed by the supplied toner is carried by the image carrier 100.

[0210] The transfer belt 66 transports the recording medium P between the image carrier 100 and the transfer device 62. The transfer device 62 transfers the toner image developed by the developing device 46 from the surface of the image carrier 100 to the recording medium P, which is a receiving body. During transfer, the surface of the image carrier 100 and the recording medium P are in contact with each other. That is, the image forming apparatus 110 employs a direct transfer method. The transfer device 62 is, for example, a transfer roller.

[0211] Each of image forming unit 40Y and transfer device 62Y, image forming unit 40M and transfer device 62M, image forming unit 40C and transfer device 62C, and image forming unit 40K and transfer device 62K sequentially overlays toner images of multiple colors (for example, four colors: yellow, magenta, cyan, and black) on the recording medium P on the transfer belt 66 to form an unfixed toner image.

[0212] The cleaning devices 48Y, 48M, 48C, and 48K include corresponding housings 481Y, 481M, 481C, and 481K, and cleaning members 482Y, 482M, 482C, and 482K, respectively. The cleaning member 482 is disposed in the housing 481. The cleaning member 482 abuts against the surface of the image carrier 100. The cleaning member 482 polishes the surface of the image carrier 100, and collects the toner adhering to the surface of the image carrier 100 into the housing 481. In this manner, the cleaning device 48 collects the toner adhering to the surface of the image carrier 100. The cleaning member 482 is, for example, a cleaning roller.

[0213] The static eliminator 50 eliminates static electricity from the surface of the image carrier 100 .

[0214] The recording medium P on which the unfixed toner image has been formed is transported to a fixing unit 80. The fixing unit 80 includes a pressure member 82 and a heating member 84. The pressure member 82 and the heating member 84 apply pressure and heat to the recording medium P, thereby fixing the unfixed toner image to the recording medium P.

[0215] The recording medium P on which the toner image has been fixed is discharged from the paper discharge section 90.

[0216] <Printing mode and cleaning mode> Next, the operation of the image forming apparatus 110 executed in the print mode and cleaning mode will be described with further reference to Fig. 5 and Fig. 6 in addition to Fig. 4. Fig. 5 is a diagram showing the image carrier 100 and cleaning member 482 shown in Fig. 4, and the control device 10. Fig. 6 is a time chart showing the control of the cleaning member 482 in the print mode and cleaning mode. The horizontal axis in Fig. 6 indicates time, and the vertical axis indicates the voltage applied to the cleaning member 482. On the vertical axis in Fig. 6, "+" indicates that a positive voltage is applied, "0" indicates that no voltage is applied, and "-" indicates that a negative voltage is applied.

[0217] As already described with reference to Fig. 4, the image forming apparatus 110 includes the control device 10 and the belt cleaning unit 70. Moreover, as shown in Fig. 5, the image forming apparatus 110 further includes voltage application devices 200Y, 200M, 200C, and 200K, and contact / separation mechanisms 300Y, 300M, 300C, and 300K. As already described, the suffixes "Y", "M", "C", and "K" attached to each member of the image forming apparatus 110 will be omitted when there is no need to distinguish between them.

[0218] The control device 10 controls the voltage application device 200 to control the voltage applied to the cleaning member 482 .

[0219] In a cleaning mode, the belt cleaning unit 70 collects toner that has moved from the image carrier 100 to the transfer belt 66. The belt cleaning unit 70 includes a belt cleaning roller 72, a toner collection container 74, and a backup roller 76. The belt cleaning unit 70 is provided below the transfer belt 66. The belt cleaning roller 72 contacts the surface (e.g., the outer peripheral surface) of the transfer belt 66. The backup roller 76 is disposed so as to sandwich the transfer belt 66 between itself and the belt cleaning roller 72. The belt cleaning roller 72 polishes the surface (the outer peripheral surface that is the contact surface) of the transfer belt 66, and collects the toner adhering to the surface of the transfer belt 66 into the toner collection container 74.

[0220] The voltage application devices 200Y, 200M, 200C, and 200K are connected to the cleaning members 482Y, 482M, 482C, and 482K, respectively. The voltage application device 200 applies a voltage to the cleaning member 482.

[0221] The contact / separation mechanisms 300Y, 300M, 300C, and 300K respectively bring the corresponding developing devices 46Y, 46M, 46C, and t into contact with or separate from the image carriers 100Y, 100M, 100C, and 100K.

[0222] (Print Mode) The control by the control device 10 in the print mode and the operation of the image forming device 110 will be described below. When a print job including image data is input from an external device (not shown, for example a personal computer), the control device 10 executes the print mode. In the print mode, an image is printed on the recording medium P.

[0223] 6, at time t11 when printing in the print mode starts, the control device 10 controls the voltage application device 200 to apply a first voltage of negative polarity to the cleaning member 482. Also, at time t11, the control device 10 starts rotational driving of the image carrier 100, the cleaning member 482, and the transfer belt 66. Toner (positively charged toner) remaining on the image carrier 100 after transfer is electrostatically collected by the cleaning member 482 to which the first voltage of negative polarity has been applied.

[0224] More specifically, in the print mode, the control device 10 applies a positive voltage to the charging device 42. Then, the charging device 42 positively charges the surface of the image carrier 100. Therefore, the positively charged toner electrostatically moves from the positively charged surface of the image carrier 100 to the cleaning member 482 to which a negative voltage is applied, and is collected.

[0225] While continuing to collect toner by the cleaning member 482 to which the first voltage of negative polarity has been applied, the control device 10 causes the image carrier 100, which is driven to rotate, to be charged by the charging device 42, exposed by the exposure device 44, developed by the developing device 46, transferred by the transfer device 62, and discharged by the discharge device 50. Then, after the unfixed toner image is transferred to the recording medium P transported between the image carrier 100 and the transfer device 62, the control device 10 causes the fixing section 80 to fix the unfixed toner image, and an image, which is a fixed toner image, is formed on the recording medium P.

[0226] When image formation of all image data included in the print job is completed, that is, at time t12 when the print mode ends, the control device 10 controls the voltage application device 200 to stop application of the negative first voltage to the cleaning member 482. Also, at time t12, the control device 10 stops the rotational driving of the image carrier 100, the cleaning member 482, and the transfer belt 66. This ends the print mode.

[0227] As described in the first embodiment, the photoconductor 1, which is the image carrier 100, is preferably positively charged even when it is repeatedly positively and negatively charged. Therefore, even when the surface of the image carrier 100 is repeatedly positively charged by the charging device 42 in the print mode, and the potential of the image carrier 100 is repeatedly lowered to negative by contact with the cleaning member 482 to which the first voltage of negative polarity is applied, the photoconductor 1, which is the image carrier 100, is preferably charged to a desired positive potential in the charging step. As a result, even when it is repeatedly positively and negatively charged, the image forming apparatus 110 including the photoconductor 1 as the image carrier 100 can form a good image.

[0228] (Cleaning mode) The following describes the control by the control device 10 in the cleaning mode and the operation of the image forming device 110. When the print mode ends, the control device 10 executes the cleaning mode. In the cleaning mode, the toner that adheres to the cleaning member 482 after the print mode ends is collected.

[0229] Specifically, during a first predetermined time T1 (time t12 to t13) in the cleaning mode, the control device 10 controls the contact / separation mechanism 300 to separate the developing device 46 from the image carrier 100 in a separation direction D1. The separation direction D1 is the direction in which the developing device 46 is separated from the image carrier 100.

[0230] After the developing device 46 is separated, at time t13 in the cleaning mode, the control device 10 controls the voltage application device 200 to apply a second voltage of positive polarity (a voltage of the same polarity as the charge polarity of the toner) to the cleaning member 482. Also, at time t13, the control device 10 starts rotational driving of the image carrier 100, the cleaning member 482, and the transfer belt 66. As a result, the toner (positively charged toner) adhering to the cleaning member 482 is electrostatically moved from the cleaning member 482 to which the second voltage of positive polarity has been applied, to the image carrier 100. The toner that has moved to the image carrier 100 moves to the transfer belt 66 as the image carrier 100 rotates. The toner that has moved to the transfer belt 66 is collected by the belt cleaning unit 70 as the transfer belt 66 rotates.

[0231] During a second predetermined time T2 (time t13 to t14) in the cleaning mode, a second voltage of positive polarity is applied to the cleaning member 482. After that, at time t14, the control device 10 controls the voltage application device 200 to stop application of the second voltage of positive polarity to the cleaning member 482.

[0232] During the second predetermined time T2 (time t13 to t14) in the cleaning mode, the control device 10 may not apply a voltage to the charging device 42, or may apply a positive voltage to the charging device 42. When applying a positive voltage to the charging device 42, it is preferable that the positive voltage applied to the charging device 42 is lower than the second voltage of positive polarity applied to the cleaning member 482. This is to electrostatically move the positively charged toner from the cleaning member 482 to the charging device 42 in an appropriate manner.

[0233] During the third predetermined time T3 (times t14 to t15) in the cleaning mode, the control device 10 continues to rotate the image carrier 100, the cleaning member 482, and the transfer belt 66. During the third predetermined time T3, the control device 10 controls the contact / separation mechanism 300 to move the developing device 46 in the approach direction D2. The approach direction D2 is the direction in which the developing device 46 approaches the image carrier 100. Then, at time t15, the control device 10 brings the developing device 46 into contact with the image carrier 100. Also, at time t15, the control device 10 stops the rotation of the image carrier 100, the cleaning member 482, and the transfer belt 66. Time t15 can be defined as the time when the toner, which moved from the cleaning member 482 to the image carrier 100 immediately before the application of the second voltage of positive polarity was stopped, moves from the image carrier 100 to the transfer belt 66, and is then collected from the transfer belt 66 by the belt cleaning unit 70. The cleaning mode ends when the rotational driving of the image carrier 100, the cleaning member 482, and the transfer belt 66 is stopped.

[0234] As described in the first embodiment, the photoconductor 1, which is the image carrier 100, is preferably positively charged even when it is repeatedly positively and negatively charged. Such an image carrier 100 is less susceptible to the influence of fluctuations in the surface potential. Therefore, even if the potential of the photoconductor 1 rises to a positive polarity due to contact with the cleaning member 482 to which the positive second voltage is applied, the image carrier 100 can be preferably charged to a desired positive potential when the printing mode is executed again after the cleaning mode ends.

[0235] The above describes the control by the control device 10 in the printing mode and cleaning mode, and the operation of the image forming apparatus 110. Hereinafter, the control by the control device 10 in the printing mode and cleaning mode will be described in more detail with reference to Fig. 7. Fig. 7 is a flow chart showing the control of the image forming apparatus 110 shown in Fig. 4.

[0236] The control device 10 repeatedly executes the process of the flowchart shown in FIG. 7. Specifically, the control device 10 judges whether or not a print job has been input (S101). If a print job has not been input (No in S101), the process of the flowchart shown in FIG. 7 ends. If a print job has been input (Yes in S101), the print mode is executed. In the print mode, the control device 10 controls the voltage application device 200 to apply a first voltage of negative polarity to the cleaning member 482 (S102). At this time, as already described, the positively charged toner remaining on the image carrier 100 is collected by the cleaning member 482 to which the first voltage of negative polarity has been applied.

[0237] After the print mode is completed, the cleaning mode is executed. In the cleaning mode, the control device 10 separates the developing device 46 from the image carrier 100 (S103). Next, the control device 10 controls the voltage application device 200 to apply a second voltage of positive polarity to the cleaning member 482 (S104). At this time, as already described, the positively charged toner adhering to the cleaning member 482 moves to the image carrier 100. Next, the toner that has moved to the image carrier 100 is collected by the belt cleaning unit 70 via the transfer belt 66. Next, the control device 10 returns the position of the developing device 46 to bring the developing device 46 into contact with the image carrier 100 (S105). Then, the control device 10 ends the process of the flowchart shown in FIG. 7.

[0238] (Modification) The image forming apparatus 110 already described can be modified as shown below: In a multi-color printing mode for printing a multi-color image, the printing mode and cleaning mode already described are executed.

[0239] Meanwhile, unlike the multi-color printing mode, a monochrome printing mode for printing monochrome images can be executed as follows. In the monochrome printing mode (times t11 to t12 in FIG. 6), the control device 10 controls the voltage application device 200K (voltage application device for black) to apply a first voltage of negative polarity to the cleaning member 482K (cleaning member for black). In the monochrome printing mode (times t11 to t12 in FIG. 6), the control device 10 controls the voltage application devices 200Y, 200M, and 200C (voltage application devices for yellow, magenta, and cyan) to apply a third voltage of positive polarity to the cleaning members 482Y, 482M, and 482C (cleaning members for yellow, magenta, and cyan). Microcomponents (e.g., paper dust) of the negatively charged recording medium P may adhere to the image carriers 100Y, 100M, and 100C (yellow, magenta, and cyan image carriers) that are not used in the monochrome printing mode. Therefore, by applying a third voltage (positive polarity voltage) to the cleaning members 482Y, 482M, and 482C, the microcomponents of the negatively charged recording medium P are electrostatically collected by the cleaning members 482Y, 482M, and 482C.

[0240] In addition, during the second predetermined time T2 (times t13 to t14 in FIG. 6) of the cleaning mode after the monochrome printing mode, the control device 10 controls the voltage application device 200K to apply a second voltage of positive polarity to the cleaning member 482K. As a result, the positively charged toner adhering to the cleaning member 482K moves onto the image carrier 100K (black image carrier). During the second predetermined time T2 (times t13 to t14 in FIG. 6) of the cleaning mode after the monochrome printing mode, the control device 10 controls the voltage application devices 200Y, 200M, and 200C to apply a fourth voltage of negative polarity to the cleaning members 482Y, 482M, and 482C. As a result, the negatively charged microcomponents of the recording medium P adhering to the cleaning members 482Y, 482M, and 482C move onto the image carriers 100Y, 100M, and 100C. Next, the toner that has moved onto the image carrier 100K and the minute components of the recording medium P that have moved onto the image carriers 100Y, 100M, and 100C are collected by the belt cleaning unit 70 via the transfer belt 66. The modified examples have been described above.

[0241] Although an example of an image forming apparatus has been described above, the image forming apparatus is not limited to the image forming apparatus 110, and may be further modified in the following respects, for example. The image forming apparatus 110 is a color image forming apparatus, but the image forming apparatus may be a monochrome image forming apparatus. In this case, the image forming apparatus may have only one image forming unit, for example. The image forming apparatus 110 employs a tandem system, but the image forming apparatus may employ, for example, a rotary system. The charging device 42 has been described using a scorotron charger as an example, but the charging device may be a charging device other than a scorotron charger (for example, a charging roller, a charging brush, or a corotron charger). The image forming apparatus 110 employs a contact development system, but the image forming apparatus may employ a non-contact development system. The image forming apparatus 110 employs a direct transfer system, but the image forming apparatus may employ an intermediate transfer system.

[0242] [Third embodiment: process cartridge] Next, a process cartridge according to a third embodiment of the present invention will be described with continued reference to Fig. 4. The process cartridge according to the third embodiment corresponds to each of the image forming units 40Y, 40M, 40C, and 40K. The process cartridge includes an image carrier 100.

[0243] The image carrier 100 is the photoreceptor 1 of the first embodiment. As already described, the photoreceptor 1 of the first embodiment can be positively charged well even when it is repeatedly positively and negatively charged, and has excellent abrasion resistance and storage stability in a high-temperature environment. Therefore, by providing such a photoreceptor 1 as the image carrier 100, the process cartridge of the third embodiment can form a good image on the recording medium P.

[0244] The process cartridge may further include at least one selected from the group consisting of a charging device 42, an exposure device 44, a developing device 46, a transfer device 62, a cleaning member 482, and a static eliminator 50, in addition to the image carrier 100. The process cartridge is designed to be detachable from the image forming apparatus 110. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics of the image carrier 100 deteriorate, the process cartridge can be easily and quickly replaced including the image carrier 100. The process cartridge of the third embodiment has been described above with reference to FIG. 4. EXAMPLES

[0245] The present invention will be described in more detail below using examples, but the present invention is not limited to the scope of the examples.

[0246] First, the following charge generating material, electron transport material, hole transport material, binder resin, and additives were prepared as materials for forming the photosensitive layer of the photoreceptor.

[0247] (Charge generating material) As the charge generating material, the Y-type titanyl phthalocyanine described in the first embodiment was prepared.

[0248] (Electron transport agent) As the electron transport material, the electron transport materials (ETM1), (ETM2), (ETM6), (ETM7), (ETM8), (ETM19), (ETM22), (ETM23), (ETM24), (ETM28), and (ETM29) described in the first embodiment were prepared. In addition, as the electron transport material used in the comparative examples, the compounds represented by the following chemical formulas (ETM32-C) to (ETM37-C) (hereinafter, each may be referred to as the electron transport material (ETM32-C) to (ETM37-C)) were prepared.

[0249] [ka]

[0250] (Hole transport agent) As the hole transport material, the hole transport materials (HTM1) to (HTM10) described in the first embodiment were prepared.

[0251] (binder resin) As the binder resin, the polycarbonate resins (R1) to (R13) described in the first embodiment were prepared. In addition, as the binder resin used in the comparative example, polycarbonate resins represented by the following chemical formulas (R14-C) to (R15-C) (hereinafter, each may be referred to as polycarbonate resins (R14-C) to (R15-C)) were prepared. The viscosity average molecular weights of the polycarbonate resins (R1) to (R13) and (R14-C) to (R15-C) were all 35,000.

[0252] [ka]

[0253] [ka]

[0254] (Additives) As additives, additives (AD1) to (AD6) described in the first embodiment were prepared. In addition, as an additive used in a comparative example, a compound represented by the following chemical formula (AD7-C) (hereinafter, sometimes referred to as additive (AD7-C)) was prepared. The melting points (unit: °C) of each additive are shown in Tables 5 to 8.

[0255] [ka]

[0256] <Production of photoconductors> Photoreceptors (A-1) to (A-39) and (B-1) to (B-10) were produced using the above charge generating material, electron transport material, hole transport material, binder resin, and additives.

[0257] (Production of Photoreceptor (A-1)) 3 parts by mass of Y-type titanyl phthalocyanine as a charge generating agent, 70 parts by mass of a hole transporting agent (HTM1), 100 parts by mass of a polycarbonate resin (R1) as a binder resin, 35 parts by mass of an electron transporting agent (ETM1), 18 parts by mass of an additive (AD1), and 800 parts by mass of a solvent, tetrahydrofuran, were mixed for 50 hours using a ball mill to obtain a coating liquid for a photosensitive layer. The coating liquid for a photosensitive layer was applied onto a conductive substrate (aluminum drum-shaped support) by a dip coating method. The applied coating liquid for a photosensitive layer was dried with hot air at 120°C for 60 minutes. In this way, a photosensitive layer (film thickness 30 μm) was formed on the conductive substrate to obtain a photoreceptor (A-1). In the photoreceptor (A-1), a single layer of a photosensitive layer was provided directly on the conductive substrate.

[0258] (Production of Photoreceptors (A-2) to (A-39) and (B-1) to (B-10)) Photoreceptors (A-2) to (A-39) and (B-2) to (B-10) were each produced in the same manner as photoreceptor (A-1), except that they used the additives, hole transport materials, electron transport materials, and binder resins shown in Tables 5 to 8. Photoreceptor (B-1) was produced in the same manner as photoreceptor (A-1), except that they did not use any additives.

[0259] <Evaluation of positive charging properties when positive and negative charging are repeated> The positive charging property of the photoconductor was evaluated when the photoconductor was repeatedly charged positively and negatively in an environment of 25°C temperature and 50% RH relative humidity. A drum sensitivity tester (Gentec) was used for this evaluation. The photoconductor was set in the drum sensitivity tester. The drum sensitivity tester was equipped with a first charging device, a probe, a second charging device, and a static eliminator from the upstream side of the rotation direction of the photoconductor. The first charging device charges the surface of the photoconductor to a positive polarity. The first charging device is a scorotron charger, and the grid voltage was set to +700V. The probe is provided at the development position and measures the surface potential of the photoconductor. The second charging device is provided at the cleaning position and charges the surface of the photoconductor to a negative polarity. The second charging device is a corotron charger, and the applied voltage was set to -5kV. The static eliminator eliminates static electricity from the surface of the photoconductor.

[0260] The photoconductor was rotated 10 times at a rotation speed of 200 mm / sec with the first charging device for positive charging turned on, the static eliminator turned on, and the second charging device for negative charging turned off. In this manner, the photoconductor was repeatedly positively charged and statically eliminated. During the 10 rotations, the surface potential of the photoconductor was continuously measured using a probe. The average value of the surface potential of the photoconductor for these 10 rotations was taken as the charging potential V1 (unit: +V) of the photoconductor before the repeated positive and negative charging.

[0261] Next, the photoconductor was rotated 200 times at a rotation speed of 200 mm / sec with the first charging device for positive charging, the static eliminator, and the second charging device for negative charging all turned on. In this manner, the photoconductor was repeatedly positively charged, static eliminator, and negatively charged. Using a probe, the surface potential of the photoconductor was continuously measured for 10 revolutions from the 191st revolution to the 200th revolution. The average value of the surface potential of the photoconductor for these 10 revolutions was taken as the charging potential V2 (unit: +V) of the photoconductor after repeated positive and negative charging.

[0262] Then, the amount of charge potential drop (unit: V) of the photoconductor before and after repeated positive and negative charging was calculated from the formula "amount of charge potential drop = V1 - V2". From the amount of charge potential drop, whether the photoconductor could be satisfactorily positively charged when positive and negative charging was repeated was evaluated based on the following criteria. The measured amount of charge potential drop and the evaluation results of positive chargeability when positive and negative charging was repeated are shown in Tables 5 to 8.

[0263] (Evaluation criteria for positive charging when positive and negative charging are repeated) Evaluation A: The amount of decrease in charged potential is less than 90V. Evaluation B: The amount of decrease in the charged potential is 90V or more and less than 120V. Evaluation C: The amount of decrease in the charged potential is 120 V or more.

[0264] <Evaluation of high-temperature storage properties> A cleaning roller coated with 0.1 g of horse oil was pressed against the photoreceptor and stored for 3 days in an environment with a temperature of 50°C and a relative humidity of 80%. After storage, the horse oil on the surface of the photoreceptor was wiped off with ethanol, and the surface of the photoreceptor was observed with the naked eye. The presence or absence of cracks and dents on the surface of the photoreceptor was then confirmed. The high-temperature storage stability of the photoreceptor was evaluated based on the presence or absence of cracks and dents, according to the following criteria. The evaluation results of high-temperature storage stability are shown in Tables 5 to 8.

[0265] (Evaluation criteria for high temperature storage stability) Evaluation A: No cracks or dents were observed. Evaluation B: At least one of cracks and dents was slightly observed, but was not problematic in practical use. Evaluation C: At least one of cracks and dents is clearly observed.

[0266] <Abrasion resistance evaluation> The coating solution for the photosensitive layer prepared in the above <Production of photoreceptor> was applied to a polypropylene sheet wound around an aluminum pipe. The applied coating solution for the photosensitive layer was dried at 120°C for 60 minutes to prepare a polypropylene sheet on which a photosensitive layer (film thickness 30 μm) was formed. The photosensitive layer was then peeled off from the polypropylene sheet. The peeled off photosensitive layer was attached to a card-like member ("S-36" manufactured by Taber). The mass MA of the card-like member to which the photosensitive layer was attached was measured. Next, the card-like member was attached to the turntable of a rotary abrasion tester (Toyo Seiki Seisakusho Co., Ltd.). Then, with an abrasive wheel ("CS-10" manufactured by Taber) with a load of 500 gf placed on the photosensitive layer on the card-like member, the turntable was rotated 500 times at a rotation speed of 60 rpm. In this way, the photosensitive layer on the turntable was abraded. After abrasion, the mass MB of the card-like member to which the photosensitive layer was attached was measured again. Then, the abrasion loss (= MA-MB, unit: mg), which is the change in mass of the photosensitive layer before and after abrasion, was calculated. From the abrasion loss, the abrasion resistance of the photosensitive member was evaluated based on the following criteria. The measured abrasion loss and the evaluation results of the abrasion resistance are shown in Tables 5 to 8.

[0267] (Evaluation criteria for wear resistance) Evaluation A: The abrasion loss is less than 5.0 mg. Evaluation B: The abrasion loss is 5.0 mg or more and less than 8.0 mg. Evaluation C: The abrasion loss is 8.0 mg or more.

[0268] The meanings of the terms in Tables 5 to 8 are as follows: "HTM" refers to a hole transport material. "ETM" refers to an electron transport material. "Resin" refers to polycarbonate resin, which is a binder resin. The "Value" in the "V1-V2" column indicates the amount of charge potential drop (unit: V) of the photoreceptor before and after repeated positive and negative charging. The "Evaluation" in the "V1-V2" column indicates the evaluation result of positive chargeability when positive and negative charging are repeated. The "Evaluation" in the "High temperature storage" column indicates the evaluation result of high temperature storage property. The "Value" in the "Wear resistance" column indicates the amount of wear loss (unit: mg). The "Evaluation" in the "Wear resistance" column indicates the evaluation result of wear resistance.

[0269] [Table 5]

[0270] [Table 6]

[0271] [Table 7]

[0272] [Table 8]

[0273] As shown in Table 8, the photosensitive layer of the photoreceptor (B-1) did not contain any additives. Therefore, as shown in Table 8, the high-temperature storage stability of the photoreceptor (B-1) was evaluated as C, which was poor.

[0274] As shown in Table 8, the photosensitive layer of the photoreceptor (B-2) contained an additive (AD7-C), but the additive (AD7-C) was not a specified additive. Therefore, as shown in Table 8, the high-temperature storage property and abrasion resistance of the photoreceptor (B-2) were both rated C, which was poor.

[0275] As shown in Table 8, the photosensitive layers of the photoreceptors (B-3) to (B-8) did not contain the electron transport agent (1). Therefore, as shown in Table 8, the positive chargeability of the photoreceptors (B-3) to (B-8) when they were repeatedly positively and negatively charged was evaluated as C, which was poor.

[0276] As shown in Table 8, the photosensitive layers of the photoreceptors (B-9) to (B-10) did not contain a polycarbonate resin (PC). Specifically, the polycarbonate resins (R14-C) and (R15-C) contained in the photosensitive layers of the photoreceptors (B-9) and (B-10) were not the first terminal groups having halogen atoms when n in the general formula (10) represents 100. For this reason, as shown in Table 8, the abrasion resistance of the photoreceptors (B-9) to (B-10) was evaluated as C, which was poor.

[0277] On the other hand, as shown in Tables 5 to 7, the photosensitive layers of the photoreceptors (A-1) to (A-39) contained an electron transport agent (1) (more specifically, an electron transport agent (ETM1), (ETM2), (ETM6), (ETM7), (ETM8), (ETM19), (ETM22), (ETM23), (ETM24), (ETM28), or (ETM29)), a specified additive (more specifically, one of the additives (AD1) to (AD6)), and a polycarbonate resin (PC) (more specifically, one of the polycarbonate resins (R1) to (R13)). For this reason, as shown in Tables 5 to 7, the positive chargeability, abrasion resistance, and high-temperature storage stability (i.e., storage stability in a high-temperature environment) of the photoreceptors (A-1) to (A-39) when they were repeatedly positively and negatively charged were all rated A or B, which were good.

[0278] From the above, it has been shown that the photoconductor of the present invention, including the photoconductors (A-1) to (A-39), can be positively charged well even when positive and negative charging are repeated, and has excellent wear resistance and storage properties in high temperature environments. In addition, it is judged that the process cartridge and image forming apparatus of the present invention equipped with such a photoconductor can form good images. [Industrial Applicability]

[0279] The photoconductor and the process cartridge according to the present invention can be used in an image forming apparatus, and the image forming apparatus according to the present invention can be used to form an image on a recording medium. [Explanation of symbols]

[0280] 1: Photoconductor (electrophotographic photoconductor) 2: Conductive substrate 3: Photosensitive layer 10: Control device 42Y, 42M, 42C, 42K: Charging device 44Y, 44M, 44C, 44K: Exposure equipment 46Y, 46M, 46C, 46K: Developing device 50Y, 50M, 50C, 50K: Static eliminator 62Y, 62M, 62C, 62K: Transfer device 100Y, 100M, 100C, 100K: Image carrier 110: Image forming apparatus 482Y, 482M, 482C, 482K: Cleaning materials

Claims

1. A conductive substrate and a photosensitive layer are provided. the photosensitive layer is a single layer and contains a charge generating material, an electron transport material, a binder resin, a hole transport material, and an additive; The electron transport agent includes a compound represented by chemical formula (ETM1), (ETM2), (ETM6), (ETM7), (ETM8), (ETM19), (ETM22), (ETM23), (ETM24), (ETM28), or (ETM29), the binder resin includes a polycarbonate resin having a main chain and an end group represented by (R1), (R2), (R3), (R4), (R5), (R6), (R7), (R8), (R9), (R10), (R11), (R12), or (R13); The hole transport agent includes a compound represented by chemical formula (HTM1), (HTM2), (HTM3), (HTM4), (HTM5), (HTM6), (HTM7), (HTM8), (HTM9), or (HTM10), The additive comprises a compound represented by chemical formula (AD1), (AD2), (AD3), (AD4), (AD5) or (AD6). 【Chemistry 1】 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】 【Chemistry 5】 【Chemistry 6】 【Chemistry 7】 【Chemistry 8】 【Chemistry 9】 【Chemistry 10】

2. The electrophotographic photoreceptor according to claim 1 , wherein the additive has a melting point of 90° C. or higher and 300° C. or lower.

3. 3. The electrophotographic photoreceptor according to claim 1, wherein the charge generating agent contains Y-type crystals of titanyl phthalocyanine.

4. At least one selected from the group consisting of a charging device, an exposure device, a developing device, a transfer device, a cleaning member, and a static eliminator; A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 3.

5. An image carrier; a charging device for charging the surface of the image carrier to a positive polarity; an exposure device that exposes the charged surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier; a developing device for developing the electrostatic latent image into a toner image; a transfer device that transfers the toner image from the image carrier to a transfer medium, An image forming apparatus, wherein the image bearing member is the electrophotographic photoreceptor according to any one of claims 1 to 3.

6. a cleaning member that comes into contact with the surface of the image carrier and collects toner adhering to the surface of the image carrier; a control device that controls a voltage applied to the cleaning member, The image forming apparatus according to claim 5 , wherein the control device applies a first voltage of negative polarity to the cleaning member in a printing mode.

7. 7. The image forming apparatus according to claim 6, wherein the control device applies a second voltage of positive polarity to the cleaning member in the cleaning mode.

8. 8. The image forming apparatus according to claim 5, further comprising a charge eliminating device that eliminates charge from the surface of the image carrier.

Images