Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

The invention provides an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. The electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer provided directly or indirectly on the conductive substrate, the photosensitive layer having a charge generation layer and a charge transport layer, the charge transport layer containing a binder resin, a hole transport agent, and a phthalocyanine pigment, the binder resin containing a specific polyarylate resin, and the hole transport agent containing a specific polyarylate resin. The specific polyarylate resin has a first repeating unit represented by the following general formula (1), a second repeating unit represented by the following chemical formula (2), a third repeating unit represented by the following chemical formula (3), and a fourth repeating unit represented by the following chemical formula (4). The ratio of the number of moles of the third repeating units to the total number of moles of the first repeating units and the third repeating units is greater than 0.0 mol% and less than 50.0 mol%, and the ratio of the number of moles of the fourth repeating units to the total number of moles of the second repeating units and the fourth repeating units is 30.0 mol% or more and less than 70.0 mol%. # imgabs0 #

Description

Technical Field

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

[0002] Electrophotographic photoreceptors are required to have excellent sensitivity characteristics, wear resistance, and storage stability, and to suppress the generation of image memory and fog. In response to this requirement, electrophotographic photoreceptors with polyarylate resin added to the surface layer have been proposed.

[0003] However, it is difficult for the above-mentioned electrophotographic photoreceptors to simultaneously satisfy excellent sensitivity characteristics, abrasion resistance and storage stability, and suppression of image memory and fog. Summary of the invention

[0004] The present invention is made in view of the above problems, and its purpose is to provide an electrophotographic photoreceptor having excellent sensitivity characteristics, wear resistance and storage properties, and capable of suppressing the generation of image memory and fog. In addition, another purpose of the present invention is to provide a process cartridge and an image forming apparatus including such an electrophotographic photoreceptor.

[0005] The electrophotographic photoreceptor of the present invention comprises a conductive substrate and a photosensitive layer directly or indirectly disposed on the conductive substrate. The photosensitive layer comprises a charge generating layer and a charge transporting layer. The charge transporting layer comprises a binder resin, a hole transporting agent and a phthalocyanine pigment. The binder resin comprises a specific polyarylate resin. The specific polyarylate resin comprises a first repeating unit represented by the following general formula (1), a second repeating unit represented by the following chemical formula (2), a third repeating unit represented by the following chemical formula (3) and a fourth repeating unit represented by the following chemical formula (4). The ratio of the number of moles of the third repeating unit to the total number of moles of the first repeating unit and the third repeating unit is greater than 0.0 mol% and less than 50.0 mol%. The ratio of the number of moles of the fourth repeating unit to the total number of moles of the second repeating unit and the fourth repeating unit is greater than 30.0 mol% and less than 70.0 mol%.

[0006] [Chemistry 1]

[0007]

[0008] In the general formula (1), X represents a divalent group having 1 to 10 carbon atoms, and R 1 and R 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0009] The process cartridge of the present invention includes the above-mentioned electrophotographic photoreceptor.

[0010] The image forming device of the present invention comprises: an image carrier; a charging device for charging the surface of the image carrier; an exposure device for exposing the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier; a developing device for supplying a toner to the surface of the image carrier to develop the electrostatic latent image into a toner image; and a transfer device for transferring the toner image from the image carrier to a transferee. The image carrier is the above-mentioned electrophotographic photoreceptor.

[0011] The electrophotographic photoreceptor of the present invention has excellent sensitivity characteristics, wear resistance and storage properties, and can suppress the generation of image memory and fog. In addition, the process cartridge of the present invention and the image forming apparatus of the present invention have excellent sensitivity characteristics, wear resistance and storage properties of the electrophotographic photoreceptor, and can suppress the generation of image memory and fog. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a partial cross-sectional view showing an example of the electrophotographic photoreceptor according to the first embodiment.

[0013] Figure 2 This is a partial cross-sectional view showing another example of the electrophotographic photoreceptor according to the first embodiment.

[0014] Figure 3 FIG. 1 is a diagram showing an example of an image forming apparatus according to a second embodiment. DETAILED DESCRIPTION

[0015] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

[0016] Sometimes acryl and methacryl are collectively referred to as "(meth)acryl". Sometimes acrylate and methacrylate are collectively referred to as "(meth)acrylate". Unless otherwise specified, the number average primary particle size refers to the number average value of the equivalent circular diameter (Heywood diameter: the diameter of a circle with the same area as the projected area of ​​the primary particle) of the primary particles measured using a scanning electron microscope. The number average primary particle size is, for example, the number average value of the equivalent circular diameters of 100 primary particles. The viscosity average molecular weight of the resin is measured in accordance with JIS (Japanese Industrial Standards) K7252-1: 2016. Sometimes "class" is added after the compound name to collectively refer to the compound and its derivatives. In addition, when "class" is added after the compound name to indicate the polymer name, it means that the repeating unit of the polymer comes from the compound or its derivative. "Respectively independently" in the general formula description means that it can represent the same group or different groups. Unless otherwise specified, each component described in this specification can be used alone or in combination of two or more. For example, "at least one of A, B, and C" and "at least one of A, B, and C" have the same meaning as "at least one selected from the group consisting of A, B, and C".

[0017] [First Embodiment: Electrophotographic Photoreceptor]

[0018] The first embodiment of the present invention relates to an electrophotographic photoreceptor (hereinafter, sometimes described as a photoreceptor). The photoreceptor of this embodiment includes a conductive substrate and a photosensitive layer directly or indirectly provided on the conductive substrate. The photosensitive layer has a charge generating layer and a charge transporting layer. The charge transporting layer contains a binder resin, a hole transporting agent and a phthalocyanine pigment. The binder resin contains a specific polyarylate resin. The specific polyarylate resin has: a first repeating unit represented by the following general formula (1), a second repeating unit represented by the following chemical formula (2), a third repeating unit represented by the following chemical formula (3) and a fourth repeating unit represented by the following chemical formula (4). The ratio of the number of moles of the third repeating unit to the total number of moles of the first repeating unit and the third repeating unit (hereinafter, sometimes described as ratio (3)) is greater than 0.0 mol% and less than 50.0 mol%. The ratio of the number of moles of the fourth repeating unit to the total number of moles of the second repeating unit and the fourth repeating unit (hereinafter, sometimes described as ratio (4)) is 30.0 mol% or more and less than 70.0 mol%.

[0019] [Chemistry 2]

[0020]

[0021] In the general formula (1), X represents a divalent group having 1 to 10 carbon atoms. 1 and R 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0022] Since the photoreceptor of the present embodiment includes the above-mentioned structure, it has excellent sensitivity characteristics, wear resistance and storage properties, and can suppress the generation of image memory and fog. The reason is presumed to be as follows. In the photoreceptor of the present embodiment, the charge transport layer contains a specific polyarylate resin. The specific polyarylate resin has a first repeating unit to a fourth repeating unit. The first repeating unit imparts rigidity to the specific polyarylate resin. The second repeating unit and the third repeating unit impart flexibility to the specific polyarylate resin. The fourth repeating unit adjusts the physical property balance of the specific polyarylate resin. Since the specific polyarylate resin has the first repeating unit to the fourth repeating unit, and the ratio (3) and the ratio (4) are set to a specific range, it is possible to impart excellent sensitivity characteristics, wear resistance and storage properties to the photoreceptor of the present embodiment. In particular, since the ratio (3) of the third repeating unit of the specific polyarylate resin is greater than 0.0 mol%, it is possible to impart excellent wear resistance to the photoreceptor of the present embodiment. In addition, the specific polyarylate resin can suppress gelation of the coating liquid prepared when forming the charge transport layer because the ratio (3) of the third repeating unit is less than 50.0 mol%. In addition, the specific polyarylate resin can impart excellent storage properties to the photoreceptor of the present embodiment because the ratio (4) of the fourth repeating unit is 30.0 mol% or more. In addition, the specific polyarylate resin can impart excellent wear resistance to the photoreceptor of the present embodiment because the ratio (4) of the fourth repeating unit is less than 70.0 mol%.

[0023] On the other hand, in known photoreceptors using polyarylate resin as a binder resin for a charge transport layer, there is a tendency for charges to be easily accumulated in the charge transport layer. In known photoreceptors, if charges are accumulated in the charge transport layer, image memory and fog will result. In response to this, in the photoreceptor of the present embodiment, the charge transport layer contains a phthalocyanine pigment. The pigment can eliminate the charges accumulated in the charge transport layer and suppress the generation of fog. Among pigments, phthalocyanine pigments can effectively eliminate the charges accumulated in the charge transport layer, suppress the generation of fog, and can also suppress the generation of image memory. Since the charge transport layer of the photoreceptor of the present embodiment contains a phthalocyanine pigment, it can suppress the generation of image memory and fog. The photoreceptor is further described below.

[0024] The photoreceptor of this embodiment is, for example, a photoreceptor having a negatively charged stacked photosensitive layer. Figure 1 The structure of a photoreceptor 1 as an example of a photoreceptor according to the present embodiment will be described. Figure 1 FIG. 2 shows a partial cross-sectional view of the photoreceptor 1. Figure 1As shown, the photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 includes a charge generating layer 3a and a charge transporting layer 3b. That is, the photoreceptor 1 includes: a conductive substrate 2, a charge generating layer 3a provided on the conductive substrate 2, and a charge transporting layer 3b provided on the charge generating layer 3a.

[0025] The thickness of the charge generating layer 3a is not particularly limited, but is preferably 0.01 μm to 5 μm, and more preferably 0.1 μm to 3 μm. Figure 1 In the example shown, the charge generation layer 3a has a single-layer structure. However, the charge generation layer 3a may have a multi-layer structure.

[0026] The thickness of the charge transport layer 3b is not particularly limited, but is preferably 2 μm to 100 μm, and more preferably 5 μm to 50 μm. Figure 1 In the example shown, the charge transport layer 3b has a single-layer structure. However, the charge transport layer 3b may also have a multi-layer structure. Figure 1 The structure of the photoreceptor 1 as an example of the photoreceptor according to the present embodiment has been described.

[0027] Next, refer to Figure 2 The structure of the photoreceptor 11 as another example of the photoreceptor according to the present embodiment will be described. Figure 2 FIG. 1 is a partial cross-sectional view of the photoreceptor 11. Figure 2 As shown, the photoreceptor 11 includes, for example, a conductive substrate 12, an intermediate layer 14, and a photosensitive layer 13. The photosensitive layer 13 includes a charge generating layer 13a and a charge transporting layer 13b. That is, Figure 2 The photoreceptor 11 shown includes a conductive substrate 12, an intermediate layer 14 provided on the conductive substrate 12, a charge generating layer 13a provided on the intermediate layer 14, and a charge transporting layer 13b provided on the charge generating layer 13a.

[0028] The thickness of the intermediate layer 14 is preferably 1.0 μm or more and 20.0 μm or less, and more preferably 1.0 μm or more and 5.0 μm or less.

[0029] Figure 2 The photoreceptor 11 shown in the figure has a conductive substrate 12, a photosensitive layer 13, a charge generating layer 13a and a charge transporting layer 13b. Figure 1 The conductive substrate 2 , the photosensitive layer 3 , the charge generating layer 3 a , and the charge transporting layer 3 b included in the photoreceptor 1 shown are the same, and thus their description is omitted.

[0030] Above, refer to Figure 1 and Figure 2, the structures of the photoreceptor 1 as an example of the photoreceptor of this embodiment and the photoreceptor 11 as another example are described. However, the structure of the photoreceptor of this embodiment may be different from Figure 1 and Figure 2 Different. In the photoreceptor of this embodiment, the charge transport layer is preferably the outermost surface layer. By making the charge transport layer the outermost surface layer, the photoreceptor of this embodiment can maximize the excellent wear resistance of the charge transport layer brought about by the specific polyarylate resin. However, in the photoreceptor of this embodiment, the charge transport layer may not be the outermost surface layer. For example, the photoreceptor of this embodiment may further include a protective layer disposed on the photosensitive layer. When the photoreceptor of this embodiment further includes a protective layer, it can also exhibit excellent wear resistance because the above-mentioned structure is satisfied. The reason is that when the protective layer is worn and the charge transport layer is exposed, the excellent wear resistance of the charge transport layer brought about by the specific polyarylate resin will be exerted. In addition, the photoreceptor of this embodiment may further include other layers other than the intermediate layer, the photosensitive layer and the protective layer.

[0031] [Conductive substrate]

[0032] The conductive substrate is not particularly limited, as long as it is composed of a material having conductivity at least on the surface. An example of a conductive substrate can be: a conductive substrate composed of a conductive material. Other examples of conductive substrates can be: a conductive substrate coated with a conductive material. Examples of conductive materials include: aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium and indium. It is also possible to combine two or more conductive materials to form an alloy (more specifically, aluminum alloy, stainless steel, or brass, etc.) for use. From the perspective of good movement of charges from the photosensitive layer to the conductive substrate, the conductive material is preferably aluminum or an aluminum alloy. The shape of the conductive substrate is appropriately selected according to the structure of the image forming device. Examples of the shape of the conductive substrate include sheet and drum. In addition, the thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

[0033] [Photosensitive layer]

[0034] The photosensitive layer is directly disposed on the conductive substrate or indirectly disposed on the conductive substrate via another layer (eg, an intermediate layer). The photosensitive layer has a charge generating layer and a charge transporting layer.

[0035] [Charge Generation Layer]

[0036] The charge generating layer contains a charge generating agent. The charge generating layer may further contain a binder resin for a charge generating layer (hereinafter, sometimes referred to as a "base resin"). The charge generating layer may further contain an additive as necessary.

[0037] (Charge Generator)

[0038] Examples of the charge generating agent include phthalocyanine pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaric acid pigments, indigo pigments, azulene pigments, cyanine pigments, powders of inorganic photoconductive materials (such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon), pyran pigments, anthraquinone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, and pyrazoline pigments.

[0039] Phthalocyanine pigments have a phthalocyanine structure. Examples of phthalocyanine pigments include metal phthalocyanine and metal-free phthalocyanine. Examples of metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Metal phthalocyanine is preferably titanyl phthalocyanine. Titanyl phthalocyanine is represented by the following chemical formula (CG-1). Metal-free phthalocyanine is represented by the following chemical formula (CG-2).

[0040] [Chemistry 3]

[0041]

[0042] Phthalocyanine pigments may be crystalline or amorphous. Examples of metal-free phthalocyanine crystals include X-type metal-free phthalocyanine crystals (hereinafter, sometimes described as X-type metal-free phthalocyanine). Examples of phthalocyanine titanyl crystals include α-type, β-type, and Y-type phthalocyanine titanyl crystals (hereinafter, sometimes described as α-type, β-type, and Y-type phthalocyanine titanyl).

[0043] For example, a digital optical image forming device (e.g., a laser printer or a fax machine using a light source such as a semiconductor laser) preferably uses a photoreceptor having sensitivity in a wavelength region of 700 nm or more. From the perspective of having a high quantum yield in a wavelength region of 700 nm or more, the charge generating agent is preferably a phthalocyanine pigment, more preferably phthalocyanine titanyl, and particularly preferably a Y-type phthalocyanine titanyl.

[0044] In the CuKα characteristic X-ray diffraction spectrum, Y-type titanium phthalocyanine has a main peak at a Bragg angle (2θ±0.2°) of 27.2°, for example. The main peak in the CuKα characteristic X-ray diffraction spectrum refers to a peak with the maximum intensity or the second largest intensity in the range of the Bragg angle (2θ±0.2°) of 3° to 40°. Y-type titanium phthalocyanine has no peak at 26.2° in the CuKα characteristic X-ray diffraction spectrum.

[0045] The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, a sample (phthalocyanine titanyl) is placed in a sample holder of an X-ray diffraction apparatus (e.g., "RINT (registered trademark) 1100" manufactured by Rigaku Co., Ltd.), and the CuKα characteristic X-ray is measured at a Cu tube, a tube voltage of 40 kV, a tube current of 30 mA, and a wavelength of 1.5 ℃. The X-ray diffraction spectrum is measured under the conditions of. The measurement range (2θ) is, for example, 3° or more and 40° or less (starting angle 3°, ending angle 40°), and the scanning speed is, for example, 10° / minute. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0046] The content of the charge generating agent in the charge generating layer is preferably from 0.1 parts by mass to 10.0 parts by mass, and more preferably from 1.0 parts by mass to 4.0 parts by mass, relative to 100 parts by mass of the base resin.

[0047] (Base resin)

[0048] Examples of base resins include thermoplastic resins, thermosetting resins, and photocurable resins. Examples of thermoplastic resins include polycarbonate resins, polyarylate resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic polymers, styrene-acrylic acid copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomer resins, vinyl chloride-vinyl acetate copolymers, alkyd resins, polyamide resins, polyurethane resins, polymaple resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyester resins, polyvinyl acetal resins, and polyether resins. Examples of thermosetting resins include silicone resins, epoxy resins, phenol resins, urea-formaldehyde resins, and melamine resins. Examples of photocurable resins include acrylic acid adducts of epoxy compounds and acrylic acid adducts of polyurethane compounds. The base resin is preferably polyvinyl acetal resin.

[0049] The content ratio of the base resin in the charge generating layer is preferably from 10.0 mass % to 60.0 mass %, and more preferably from 20.0 mass % to 40.0 mass %.

[0050] (additive)

[0051] Examples of additives in the charge generation layer include anti-aging agents (e.g., antioxidants, free radical scavengers, singlet quenchers, or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptor compounds (e.g., electron acceptor compounds), donors, surfactants, plasticizers, sensitizers, and leveling agents. Examples of antioxidants include hindered phenol compounds, hindered amine compounds, thioether compounds, and phosphite compounds. Examples of leveling agents include dimethyl silicone oil.

[0052] [Charge transport layer]

[0053] The charge transport layer contains a binder resin, a hole transport agent, and a phthalocyanine pigment. The charge transport layer may further contain an additive.

[0054] (Binder resin)

[0055] The binder resin includes a specific polyarylate resin. Although the binder resin may also include resins other than the specific polyarylate resin, it is preferred that only the specific polyarylate resin is included. In the binder resin, the content of the specific polyarylate resin is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. In the charge transport layer, the content of the binder resin is preferably 50.0% by mass or more and 90.0% by mass or less, and more preferably 60.0% by mass or more and 75.0% by mass or less.

[0056] (Specific polyarylate resin)

[0057] The specific polyarylate resin is, for example, a polymer of a dicarboxylic acid monomer and a bisphenol compound monomer. The dicarboxylic acid monomer includes: a dicarboxylic acid or a dicarboxylic acid derivative (for example, a dicarboxylic acid dichloride, a dimethyl dicarboxylate, a diethyl dicarboxylate, and a dicarboxylic anhydride). The bisphenol compound monomer includes: a bisphenol compound or a bisphenol compound derivative (for example, an aromatic diacetate derived from a bisphenol compound). In the specific polyarylate resin, the ratio of the total number of moles of repeating units derived from the dicarboxylic acid monomer to the total number of moles of repeating units derived from the bisphenol compound monomer is about 1:1.

[0058] The specific polyarylate resin has a first repeating unit represented by general formula (1), a second repeating unit represented by chemical formula (2), a third repeating unit represented by chemical formula (3), and a fourth repeating unit represented by chemical formula (4). The specific polyarylate resin may further have repeating units other than the first to fourth repeating units, but preferably has only the first to fourth repeating units. Of all the repeating units in the specific polyarylate resin, the total content of the first to fourth repeating units is preferably 80.0 mol% or more, more preferably 95.0 mol% or more, and particularly preferably 100.0 mol%.

[0059] (First repeating unit)

[0060] The first repeating unit is represented by the general formula (1). Among all the repeating units possessed by the specific polyarylate resin, the content ratio of the first repeating unit is preferably 20.0 mol% or more and 45.0 mol% or less, and more preferably 35.0 mol% or more and 45.0 mol% or less. By setting the content ratio of the first repeating unit to 20.0 mol% or more, the photoreceptor of this embodiment can more effectively suppress the gelation of the coating liquid prepared when forming the charge transport layer. By setting the content ratio of the first repeating unit to 45.0 mol% or less, the photoreceptor of this embodiment can exert better wear resistance.

[0061] [Chemistry 4]

[0062]

[0063] In the general formula (1), X represents a divalent group having 1 to 10 carbon atoms. 1 and R 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0064] In the general formula (1), R 1 and R 2 The alkyl group having 1 to 6 carbon atoms is preferably a methyl group, an ethyl group or a propyl group, and more preferably a methyl group. 1 and R 2 Preferably, both represent the same group, and more preferably, both represent a hydrogen atom or both represent a methyl group.

[0065] In the general formula (1), the divalent group represented by X having 1 to 10 carbon atoms is preferably an alkanediyl group having 2 to 5 carbon atoms or a cycloalkanediyl group having 5 to 7 carbon atoms, and more preferably a group represented by the chemical formula (X1) or (X2). In the chemical formula (X1) or (X2), * represents a bond.

[0066] [Chemistry 5]

[0067]

[0068] The first repeating unit is preferably represented by Chemical Formula (1-1) or Chemical Formula (1-2).

[0069] [Chemistry 6]

[0070]

[0071] The first repeating unit is derived from a compound represented by the general formula (1a). In the general formula (1a), R 1 , R 2and X have the same meanings as in the general formula (1).

[0072] [Chemistry 7]

[0073]

[0074] (Second repeating unit)

[0075] The second repeating unit is represented by chemical formula (2). Among all the repeating units possessed by the specific polyarylate resin, the content of the second repeating unit is preferably 10.0 mol% or more and 40.0 mol% or less, and more preferably 27.5 mol% or more and 37.5 mol% or less. By setting the content of the second repeating unit to 10.0 mol% or more, the photoreceptor of this embodiment can exhibit better wear resistance. By setting the content of the second repeating unit to 40.0 mol% or less, the photoreceptor of this embodiment can exhibit better storage properties and more effectively suppress the generation of fog.

[0076] [Chemistry 8]

[0077]

[0078] The second repeat unit is derived, for example, from 4,4'-oxybisbenzoic acid chloride.

[0079] (Third Repeating Unit)

[0080] The third repeating unit is represented by chemical formula (3). Among all the repeating units possessed by the specific polyarylate resin, the content ratio of the third repeating unit is preferably 5.0 mol% or more and 30.0 mol% or less, and more preferably 5.0 mol% or more and 15.0 mol% or less. By setting the content ratio of the third repeating unit to 5.0 mol% or more, the photoreceptor of this embodiment can exert better wear resistance. By setting the content ratio of the third repeating unit to 30.0 mol% or less, the gelation of the coating liquid prepared when forming the charge transport layer can be more effectively suppressed.

[0081] [Chemistry 9]

[0082]

[0083] The third repeating unit is derived, for example, from 4,4'-dihydroxydiphenyl ether.

[0084] (Fourth Repeating Unit)

[0085] The fourth repeating unit is represented by chemical formula (4). Among all the repeating units possessed by the specific polyarylate resin, the content of the fourth repeating unit is preferably 10.0 mol% to 40.0 mol%, and more preferably 12.5 mol% to 22.5 mol%. By setting the content of the fourth repeating unit to 10.0 mol% or more, the photoreceptor of this embodiment can exhibit better storage properties and more effectively suppress the generation of fog. By setting the content of the fourth repeating unit to 40.0 mol% or less, the wear resistance of the photoreceptor of this embodiment can be further optimized.

[0086] [Chemistry 10]

[0087]

[0088] The fourth repeating unit is derived, for example, from terephthalic acid dichloride.

[0089] In the specific polyarylate resin, the ratio (3) of the number of moles of the third repeating unit to the total number of moles of the first repeating unit and the third repeating unit is greater than 0.0 mol% and less than 50.0 mol%, preferably greater than 5.0 mol% and less than 45.0 mol%, and more preferably greater than 15.0 mol% and less than 25.0 mol%.

[0090] In the specific polyarylate resin, the ratio (4) of the molar number of the fourth repeating unit to the total molar number of the second repeating unit and the fourth repeating unit is 30.0 mol% or more and less than 70.0 mol%, preferably 30.0 mol% or more and 67.0 mol% or less, and more preferably 30.0 mol% or more and 40.0 mol% or less.

[0091] Preferably, with respect to all repeating units possessed by the specific polyarylate resin, the content ratio of the first repeating unit is 20.0 mol% to 45.0 mol%, the content ratio of the second repeating unit is 10.0 mol% to 40.0 mol%, the content ratio of the third repeating unit is 5.0 mol% to 30.0 mol%, and the content ratio of the fourth repeating unit is 10.0 mol% to 40.0 mol%.

[0092] The content ratio of each repeating unit in the specific polyarylate resin can be measured by using a proton nuclear magnetic resonance spectrometer. 1 H-NMR spectrum, and according to the obtained 1 The ratio of the characteristic peaks of each repeating unit in the H-NMR spectrum was calculated.

[0093] The specific polyarylate resin may have an end group. Examples of the end groups possessed by the specific polyarylate resin include: end groups represented by the general formula (T-1) and the general formula (T-2). The end group represented by the general formula (T-1) is preferably an end group represented by the chemical formula (T-DMP) (hereinafter, sometimes described as the end group (T-DMP)). The end group represented by the general formula (T-2) is preferably an end group represented by the chemical formula (T-PFH) (hereinafter, sometimes described as the end group (T-PFH)).

[0094] [Chemistry 11]

[0095]

[0096] In the general formula (T-1), R 21 represents an alkyl group having 1 to 6 carbon atoms or a halogen atom, and p represents an integer of 0 to 5. 21 It preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and particularly preferably represents a methyl group. p preferably represents an integer of 1 to 3, and more preferably represents 2.

[0097] In the general formula (T-2), R 22 R represents an alkanediyl group having 1 to 6 carbon atoms. Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. 22 Preferably, it represents an alkanediyl group having 1 to 3 carbon atoms, and more preferably represents a methylene group. Rf preferably represents a perfluoroalkyl group having 3 to 10 carbon atoms, more preferably represents a perfluoroalkyl group having 5 to 7 carbon atoms, and particularly preferably represents a perfluoroalkyl group having 6 carbon atoms.

[0098] The * in the general formula (T-1), the general formula (T-2), the chemical formula (T-DMP), and the chemical formula (T-PFH) represents a bond. The bond represented by the * in the general formula (T-1), the general formula (T-2), the chemical formula (T-DMP), and the chemical formula (T-PFH) is bonded to the repeating unit derived from the dicarboxylic acid monomer located at the end of the specific polyarylate resin (more specifically, the second repeating unit or the fourth repeating unit).

[0099] From the viewpoint of improving the film formation resistance and scratch resistance of the photoreceptor of the present embodiment, the specific polyarylate resin preferably has a terminal group containing a halogen atom.

[0100] Examples of terminal groups containing halogen atoms include: 21 Terminal group (T-1) when representing a halogen atom. Other examples of terminal groups containing a halogen atom include terminal group (T-2).

[0101] In the specific polyarylate resin, repeating units derived from the bisphenol compound monomer and repeating units derived from the dicarboxylic acid monomer are adjacent to each other and bonded to each other. The specific polyarylate resin may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer.

[0102] The specific polyarylate resin is preferably the polyarylate resin (a) to (d) shown in Table 1. In Table 1, the numerical range of each repeating unit represents the numerical range of the content ratio of each repeating unit relative to the total repeating units possessed by the polyarylate resin. The types of the first repeating unit "1-1" and "1-2" respectively represent repeating units represented by chemical formula (1-1) or chemical formula (1-2). For example, the polyarylate resin (a) has a repeating unit represented by chemical formula (1-1) as the first repeating unit. Relative to the total repeating units possessed by the polyarylate resin (a), the content ratio of the first repeating unit is 75.0 mol% or more and 85.0 mol% or less, the content ratio of the second repeating unit is 15.0 mol% or more and 25.0 mol% or less, the content ratio of the third repeating unit is 62.0 mol% or more and 68.0 mol% or less, and the content ratio of the fourth repeating unit is 32.0 mol% or more and 38.0 mol% or less. The polyarylate resins (a) to (d) may further have the above-mentioned terminal groups.

[0103] [Table 1]

[0104]

[0105] The specific polyarylate resin is particularly preferably a resin represented by chemical formula (PA-1) to (PA-4) (hereinafter referred to as polyarylate resin (PA-1) to (PA-4)). In addition, in chemical formula (PA-1) to (PA-4), the number recorded at the lower right of each repeating unit represents the content ratio of each repeating unit relative to all repeating units possessed by polyarylate resin (PA-1) to (PA-4). In addition to the repeating units represented by chemical formula (PA-1) to (PA-4), polyarylate resin (PA-1) to (PA-4) may further have the above-mentioned terminal groups.

[0106] [Chemistry 12]

[0107]

[0108] The viscosity average molecular weight of the specific polyarylate resin is preferably 10,000 or more, more preferably 30,000 or more, particularly preferably 35,000 or more, and particularly preferably 50,000 or more. If the viscosity average molecular weight of the specific polyarylate resin is 10,000 or more, the photoreceptor of the present embodiment can be further optimized in terms of wear resistance. On the other hand, the viscosity average molecular weight of the specific polyarylate resin is preferably 80,000 or less, more preferably 70,000 or less, and particularly preferably 60,000 or less. If the viscosity average molecular weight of the specific polyarylate resin is 80,000 or less, the solubility of the specific polyarylate resin in solvents is improved. The viscosity average molecular weight of the specific polyarylate resin is measured in accordance with JIS (Japanese Industrial Standard) K7252-1:2016.

[0109] Next, the method for producing the specific polyarylate resin is described. The method for producing the specific polyarylate resin can be, for example, a method of polycondensing a bisphenol compound monomer and a dicarboxylic acid monomer. The polycondensation can be performed by a known synthesis method (such as solution polymerization, melt polymerization or interfacial polymerization). The bisphenol compound monomer includes compounds that form the above-mentioned first repeating unit and the third repeating unit. The dicarboxylic acid monomer includes compounds that form the above-mentioned second repeating unit and the fourth repeating unit.

[0110] In the polycondensation of bisphenol and dicarboxylic acid, a terminal terminator may be added. Examples of the terminal terminator include 2,6-dimethylphenol and 1H,1H-perfluoro-1-heptanol. By using 2,6-dimethylphenol as the terminal terminator, a terminal group (T-DMP) is formed. By using 1H,1H-perfluoro-1-heptanol as the terminal terminator, a terminal group (T-PFH) is formed.

[0111] In the polycondensation of the bisphenol compound monomer and the dicarboxylic acid compound monomer, one or both of a base and a catalyst may be added. Examples of the base include sodium hydroxide. Examples of the catalyst include benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salts, triethylamine, and trimethylamine.

[0112] (Hole Transport Agent)

[0113] Examples of the hole transport agent include triphenylamine derivatives, diamine derivatives (e.g., N,N,N',N'-tetraphenylbenzidine derivatives, N,N,N',N'-tetraphenylphenylenediamine derivatives, N,N,N',N'-tetraphenylnaphthalenediamine derivatives, N,N,N',N'-tetraphenylphenanthrenediamine derivatives, and di(aminophenylvinyl)benzene derivatives), oxadiazole compounds (e.g., 2,5-bis(4-methylaminophenyl)-1,3,4-oxadiazole), styrene 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.

[0114] Examples of the hole transport agent include compounds represented by general formulae (20), (23), (24) and (25) (hereinafter, sometimes referred to as hole transport agents (20), (23), (24) and (25) respectively).

[0115] [Chemistry 13]

[0116]

[0117] In the general formula (20), R 50 and R 51 Each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. 52 , R 53 , R 54 , R 55 , R 56 , R 57 , and R 58 Each independently represents a phenyl group which may or may not be substituted by an alkyl group having 1 to 6 carbon atoms, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. f1 and f2 each independently represent an integer of 0 to 2. f3 and f4 each independently represent an integer of 0 to 5.

[0118] In the general formula (20), when f3 represents an integer of 2 to 5, a plurality of R 50 When f4 represents an integer of 2 to 5, multiple R 51 They may represent the same group or different groups.

[0119] In the general formula (20), R 50 and R51 Preferably, each independently represents an alkyl group having 1 to 3 carbon atoms. 52 and R 53 Preferably, each independently represents a phenyl group which may or may not be substituted with a methyl group, or a hydrogen atom. 54 To R 58 Preferably, each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms. Preferably, both f1 and f2 represent 0, or both represent 1. Preferably, each independently represents 0 or 1.

[0120] [Chemistry 14]

[0121]

[0122] In the general formula (23), R 41 , R 42 , R 43 , R 44 , R 45 and R 46 Each independently represents an alkyl group having 1 to 6 carbon atoms, or a phenyl group. 47 and R 48 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group. e1, e2, e3, and e4 each independently represent an integer from 0 to 5. e5 and e6 each independently represent an integer from 0 to 4. e7 and e8 each independently represent 0 or 1.

[0123] In the general formula (23), when e1 to e6 represent an integer of 2 or more and 4 or less, a plurality of R 41 To multiple R 46 They may represent the same group or different groups.

[0124] In the general formula (23), R 41 To R 46 Preferably, each independently represents an alkyl group having 1 to 3 carbon atoms. 47 and R 48 Preferably, it represents a hydrogen atom. e1, e2, e5 and e6 preferably represent 0. e3 and e4 preferably represent 2. e7 and e8 preferably both represent 0 or both represent 1.

[0125] In the general formula (24), R 11 , R 12 , R 13 and R 14 Each independently represents an alkyl group having a carbon number of 1 to 6 or an alkoxy group having a carbon number of 1 to 6. a1, a2, a3 and a4 each independently represent an integer of 0 to 5.

[0126] In the general formula (24), when a1 to a4 represent an integer of 2 or more and 5 or less, a plurality of R 11 To multiple R 14 They may represent the same group or different groups.

[0127] In the general formula (24), R 11 , R 12 , R 13 and R 14 Preferably, each independently represents an alkyl group having a carbon number of 1 to 3. Preferably, a1, a2, a3, and a4 each independently represent 0 or 1.

[0128] [Chemistry 15]

[0129]

[0130] In the general formula (25), R 60 represents a phenyl group which may or may not be substituted by 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. 61 , R 62 and R 63 Each independently represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. g1, g2 and g3 each independently represent an integer of 0 to 5. g4 represents 0 or 1. R 60 Preferably, R represents phenyl. 61 , R 62 and R 63 Preferably, each independently represents an alkyl group having 1 to 3 carbon atoms. Preferably, g1 and g2 represent 1. Preferably, g3 represents 0.

[0131] In the general formula (25), when g1 to g3 represent an integer of 2 or more and 5 or less, a plurality of R 61 To multiple R 63 They may represent the same group or different groups.

[0132] The hole transport agent is preferably a compound represented by Chemical Formulae (H-1) to (H-5), General Formula (H-6) and Chemical Formula (H-7) (hereinafter, sometimes referred to as hole transport agents (H-1) to (H-7)).

[0133] [Chemistry 16]

[0134]

[0135] [Chemistry 17]

[0136]

[0137] In the general formula (H-6), R 100 To R 103 Each independently represents a hydrogen atom or a methyl group. 100 To R 103 At least two of them represent methyl groups.

[0138] The hole transport agent (H-6) is preferably a mixture of a hole transport agent (H-6a), a hole transport agent (H-6b) and a hole transport agent (H-6c) (hereinafter referred to as a hole transport agent (H-6 mixture)); the hole transport agent (H-6a) is a hole transport agent in the general formula (H-6) wherein R 100 To R 103 wherein 2 of them represent methyl groups and the remaining 2 represent hydrogen atoms; a hole transport agent (H-6b) is a compound in which R 100 To R 103 wherein three of the three are methyl groups and the remaining one is a hydrogen atom; a hole transport agent (H-6c) is a compound in which R 100 To R 103 A compound in which 4 of the moieties represent methyl groups.

[0139] The hole transport agent may include at least one of hole transport agents (20), (23), (24) and (25), and the total content of hole transport agents (20) and (23) to (25) relative to the total amount of the hole transport agents is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0140] In the charge transport layer, the content of the hole transport agent is preferably 10 parts by mass to 200 parts by mass, and more preferably 30 parts by mass to 60 parts by mass, relative to 100 parts by mass of the binder resin. By setting the content of the hole transport agent to 10 parts by mass to 200 parts by mass, the photoreceptor of the present embodiment can more effectively suppress the generation of fog.

[0141] (Phthalocyanine Pigments)

[0142] The phthalocyanine pigment contained in the charge transport layer has a phthalocyanine structure. Examples of the phthalocyanine pigment include compounds that are the same as the compounds exemplified as the charge generating agent, and the charge generating agent is contained in the charge generating layer. The phthalocyanine pigment contained in the charge transport layer is preferably a metal-free phthalocyanine (the compound represented by the above chemical formula (CG-2)) or a compound represented by the general formula (P-1) (metal phthalocyanine), more preferably phthalocyanine titanyl, and particularly preferably Y-type phthalocyanine titanyl.

[0143] [Chemistry 18]

[0144]

[0145] In the general formula (P-1), M represents a metal atom which may have a ligand. The metal atom represented by M is preferably titanium which may have a ligand.

[0146] In the charge transport layer, the content of the phthalocyanine pigment is preferably 0.1 to 0.5 parts by mass, and more preferably 0.2 to 0.4 parts by mass, relative to 100.0 parts by mass of the binder resin. By setting the content of the phthalocyanine pigment to 0.1 parts by mass or more, the photoreceptor of the present embodiment can more effectively suppress the generation of image memory and fog. By setting the content of the phthalocyanine pigment to 0.5 parts by mass or less, the photoreceptor of the present embodiment can further optimize the sensitivity characteristics.

[0147] (additive)

[0148] The additives contained in the charge transport layer include, for example, ultraviolet absorbers, antioxidants, free radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, donors, surfactants, plasticizers, sensitizers, electron acceptor compounds, and leveling agents. The leveling agent includes, for example, silicone oil, more specifically, dimethyl silicone oil.

[0149] The charge transport layer preferably contains silicone oil. In this case, the content of the silicone oil in the charge transport layer is preferably 0.01 parts by mass or more and 0.5 parts by mass or less relative to 100 parts by mass of the binder resin.

[0150] The charge transport layer preferably contains only the specific polyarylate resin, the hole transport agent, the phthalocyanine pigment and the additive (especially silicone oil). In the charge transport layer, the total content of the specific polyarylate resin, the hole transport agent, the phthalocyanine pigment and the additive (especially silicone oil) is preferably 90% by mass or more, more preferably 100% by mass.

[0151] The preferred combination of the type of specific polyarylate resin in the charge transport layer, the type and content of the hole transport agent, and the type and content of the phthalocyanine pigment is shown in Table 2. In Table 2, the content represents the content (parts by mass) of each component relative to 100.0 parts by mass of the binder resin. The numerical range of the content represents the numerical range of the content ratio of each component. "K-1" and "K-2" of the phthalocyanine pigment represent Y-type phthalocyanine oxytitanium and metal-free phthalocyanine, respectively. For example, combination 1 represents: the charge transport layer contains only polyarylate resin (pa-1) as a binder resin, only hole transport agent (H-1) as a hole transport agent, and only Y-type phthalocyanine oxytitanium pigment as a phthalocyanine pigment, the content ratio of the hole transport agent relative to 100.0 parts by mass of the binder resin is 40.0 parts by mass or more and 50.0 parts by mass or less, and the content ratio of the phthalocyanine pigment relative to 100.0 parts by mass of the binder resin is 0.05 parts by mass or more and 0.15 parts by mass or less. In combination 1, the charge transport layer may further contain additives.

[0152] [Table 2]

[0153]

[0154] [Middle layer]

[0155] The intermediate layer is provided between the conductive substrate and the photosensitive layer. The intermediate layer contains, for example, an intermediate layer resin and inorganic particles. Due to the presence of the intermediate layer, the current flow generated when the photosensitive body of this embodiment is exposed can be stabilized while maintaining an insulating state that can suppress the occurrence of leakage, thereby suppressing the increase in resistance.

[0156] Examples of the intermediate layer resin include the same resins as those exemplified as the base resin in the charge generating layer. The intermediate layer resin is preferably a polyamide resin, and more preferably a quaternary copolymer polyamide resin of nylon 6, nylon 12, nylon 66, and nylon 610.

[0157] The content ratio of the resin for the intermediate layer in the intermediate layer is preferably 20.0 mass % or more and 50.0 mass % or less, and more preferably 25.0 mass % or more and 40.0 mass % or less.

[0158] Examples of the inorganic particles include particles of metals (eg, aluminum, iron, or copper), metal oxides (eg, titanium oxide, aluminum oxide, zirconium oxide, tin oxide, or zinc oxide), and particles of non-metallic oxides (eg, silicon dioxide).

[0159] In the intermediate layer, the content of the inorganic particles is preferably 100 parts by mass to 300 parts by mass, and more preferably 150 parts by mass to 250 parts by mass, based on 100 parts by mass of the intermediate layer resin.

[0160] The intermediate layer may contain additives. Examples of additives contained in the intermediate layer are the same as those of additives contained in the charge transport layer. However, the intermediate layer preferably contains only the intermediate layer resin and the inorganic particles. Specifically, in the intermediate layer, the total content of the intermediate layer resin and the inorganic particles is preferably 90% by mass or more, more preferably 99% by mass or more, and particularly preferably 100% by mass.

[0161] [Photoreceptor Manufacturing Method]

[0162] Next, an example of a method for manufacturing a photoreceptor according to the present embodiment is described. The method for manufacturing a photoreceptor includes, for example, a photosensitive layer forming step. The photosensitive layer forming step includes, for example, a charge generating layer forming step and a charge transporting layer forming step. In the method for manufacturing a photoreceptor, before the photosensitive layer forming step, an intermediate layer forming step may be further included.

[0163] (Intermediate Layer Formation Step)

[0164] In the intermediate layer forming step, a coating liquid for forming the intermediate layer (hereinafter sometimes referred to as the intermediate layer coating liquid) is prepared. The intermediate layer coating liquid contains, for example, an intermediate layer resin, inorganic particles, and a solvent. Next, the intermediate layer coating liquid is applied to the conductive substrate. Next, at least a portion of the solvent contained in the applied intermediate layer coating liquid is removed to form the intermediate layer.

[0165] (Charge Generation Layer Formation Step)

[0166] In the charge generating layer forming step, a coating liquid for forming the charge generating layer (hereinafter sometimes described as a coating liquid for the charge generating layer) is prepared. The coating liquid for the charge generating layer contains, for example, a charge generating agent, a base resin, a solvent, and any component (such as an additive). The coating liquid for the charge generating layer is prepared by mixing the above components. Next, the coating liquid for the charge generating layer is applied on a conductive substrate or an intermediate layer. Next, at least a portion of the solvent contained in the applied coating liquid for the charge generating layer is removed to form a charge generating layer.

[0167] (Charge Transport Layer Formation Step)

[0168] In the charge transport layer forming step, a coating liquid for forming a charge transport layer (hereinafter, sometimes described as a charge transport layer coating liquid) is prepared. The charge transport layer coating liquid contains a hole transport agent, a binding resin, a phthalocyanine pigment, a solvent and an optional component (such as an additive). The charge transport layer coating liquid is prepared by mixing the above components. Next, the charge transport layer coating liquid is applied on the charge generating layer. Next, at least a portion of the solvent contained in the applied charge transport layer coating liquid is removed to form a charge transport layer.

[0169] The solvent contained in the intermediate layer coating liquid, charge generating layer coating liquid, and charge transporting layer coating liquid (hereinafter, these coating liquids may be collectively referred to as coating liquids) is not particularly limited as long as it can dissolve or disperse the components contained in the coating liquids. Examples of the solvent include alcohols (more specifically methanol, ethanol, isopropanol and butanol), aliphatic hydrocarbons (more specifically n-hexane, octane and cyclohexane), aromatic hydrocarbons (more specifically benzene, toluene and xylene), halogenated hydrocarbons (more specifically methyl chloride, chloroform, vinyl chloride, methylene chloride, dichloroethane, carbon tetrachloride and chlorobenzene), ethers (more specifically dioxane, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, propylene glycol monomethyl ether and diethylene glycol dimethyl ether), ketones (more specifically acetone, methyl ethyl ketone, 2-butanone and cyclohexanone), esters (more specifically ethyl acetate and methyl acetate), dimethylformaldehyde, dimethylformamide and dimethyl sulfoxide.

[0170] The coating liquid is prepared by mixing the components separately and dissolving or dispersing them in a solvent. For example, a beads mill, a ball mill, a roll mill, a paint shaker, or an ultrasonic disperser can be used for mixing.

[0171] The method of applying the coating liquid is not particularly limited as long as it is a method that can uniformly apply the coating liquid. Examples of the coating method include dip coating, spray coating, droplet coating, knife coating, and roll coating.

[0172] The method of removing at least a part of the solvent contained in the coating liquid for the intermediate layer, the coating liquid for the charge generating layer, and the coating liquid for the charge transporting layer may be, for example, heating, reducing pressure, or a combination of heating and reducing pressure. More specifically, the method may be, for example, heat treatment (hot air drying) using a high temperature dryer or a reduced pressure dryer. The temperature of the heat treatment is, for example, 40° C. to 150° C. The time of the heat treatment is, for example, 3 minutes to 150 minutes.

[0173] [Second Embodiment: Image Forming Apparatus]

[0174] The second embodiment of the present invention relates to an image forming device. The image forming device includes: an image carrier; a charging device that charges the surface of the image carrier; an exposure device that exposes the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier; a developing device that provides a toner to the surface of the image carrier to develop the electrostatic latent image into a toner image; and a transfer device that transfers the toner image from the image carrier to a transferee. The image carrier is the electrophotographic photoreceptor described in the first embodiment.

[0175] Reference Figure 3 , an image forming apparatus 110 which is an example of the image forming apparatus of the present embodiment will be described. Figure 3 1 is a diagram showing an example of the configuration of the image forming apparatus 110. The image forming apparatus 110 is, for example, a tandem color printer.

[0176] Figure 3 The illustrated image forming apparatus 110 includes: a supply 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 .

[0177] The image forming device 110 may further include a control device. The control device controls the operation of each part of the image forming device 110 (more specifically, the supply part 20, the conveying part 30, the image forming units 40Y, 40M, 40C and 40K, the transfer part 60, the belt cleaning part 70, the fixing part 80 and the paper discharge part 90). The control device is configured at an appropriate position in the main body shell of the image forming device 110. The control device includes, for example: a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and an input and output interface. The control device realizes control by performing various calculations based on the detection results of various sensors and pre-set programs.

[0178] The supply unit 20 includes a cassette 22. The cassette 22 accommodates a plurality of recording media P. The supply unit 20 supplies the recording medium P from the cassette 22 to the conveying unit 30. The recording medium P is, for example, a sheet of paper, cloth, or synthetic resin.

[0179] The transport section 30 transports the recording medium P to the image forming units 40Y, 40M, 40C, and 40K.

[0180] The image forming units 40Y, 40M, 40C and 40K include: corresponding image carriers 100Y, 100M, 100C and 100K, charging devices 42Y, 42M, 42C and 42K, exposure devices 44Y, 44M, 44C and 44K, developing devices 46Y, 46M, 46C and 46K, cleaning devices 48Y, 48M, 48C and 48K, and static elimination devices 50Y, 50M, 50C and 50K. Hereinafter, when it is not necessary to distinguish, the letters "Y", "M", "C" and "K" attached to the components of the image forming device 110 are omitted. For example, when it is not necessary to distinguish, the image forming units 40Y, 40M, 40C and 40K are all described as image forming units 40.

[0181] The transfer unit 60 includes four transfer devices 62Y, 62M, 62C and 62K, a driving 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 respectively arranged on the inner circumference 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 mounted on the driving roller 64, the driven roller 67 and the tension roller 68. The transfer belt 66 is rotated by the driving roller 64 and moves along the arrow direction ( Figure 3 Clockwise rotation in the .

[0182] An image carrier 100 is provided at the center of the image forming unit 40. The image carrier 100 is rotatable in the direction of the arrow ( Figure 3 Around the image carrier 100, the charging device 42, the exposure device 44, the developing device 46, the transfer device 62, the cleaning device 48 and the static elimination device 50 are arranged in the order described from the upstream side of the rotation direction of the image carrier 100.

[0183] The image carrier 100 is the above-mentioned photosensitive body (for example Figure 1 Photoreceptor 1).

[0184] The charging device 42 charges the surface (eg, peripheral surface) of the image carrier 100 to positively charge the surface. The charging device 42 is, for example, a scorotron charger.

[0185] The exposure device 44 exposes the charged surface of the image carrier 100 . Thus, 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 .

[0186] The developing device 46 supplies toner to the surface of the image carrier 100 to develop 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 device 110 adopts a contact development method. The developing device 46 is, for example, a developing roller.

[0187] The developer is preferably a single-component developer. At this time, the developing device 46 provides a single-component developer, i.e., a toner, to the electrostatic latent image formed on the image carrier 100. However, the developer may also be a two-component developer. At this time, the developing device 46 provides the toner contained in the two-component developer and the toner in the carrier to the electrostatic latent image formed on the image carrier 100. The image carrier 100 carries a toner image formed by the provided toner.

[0188] The transfer belt 66 conveys 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 transfer object. During the transfer, the surface of the image carrier 100 contacts the recording medium P. That is, the image forming apparatus 110 adopts a direct transfer method. The transfer device 62 is, for example, a transfer roller.

[0189] The image forming unit 40Y and the transfer device 62Y, the image forming unit 40M and the transfer device 62M, the image forming unit 40C and the transfer device 62C, and the image forming unit 40K and the transfer device 62K respectively overlap a multi-color (for example, four colors such as yellow, magenta, cyan and black) colorant image on the recording medium P on the transfer belt 66 in sequence to form an unfixed colorant image.

[0190] The cleaning devices 48Y, 48M, 48C and 48K each include: a corresponding shell 481Y, 481M, 481C and 481K, and cleaning members 482Y, 482M, 482C and 482K. The cleaning member 482 is arranged in the shell 481. The cleaning member 482 abuts against the surface of the image carrier 100. The cleaning member 482 grinds the surface of the image carrier 100 and recovers the toner attached to the surface of the image carrier 100 into the shell 481. In this way, the cleaning device 48 recovers the toner attached to the surface of the image carrier 100. The cleaning member 482 is, for example, a cleaning roller or a cleaning brush.

[0191] The static eliminating device 50 eliminates static electricity from the surface of the image carrier 100 .

[0192] The recording medium P on which the unfixed toner image is formed is conveyed to the fixing section 80. The fixing section 80 includes a pressure member 82 and a heating member 84. The recording medium P is pressed and heated by the pressure member 82 and the heating member 84, and the unfixed toner image is fixed on the recording medium P.

[0193] The recording medium P on which the toner image is fixed is discharged from the paper discharge section 90 .

[0194] An example of the image forming apparatus of the present embodiment has been described above, but the image forming apparatus of the present embodiment is not limited to the above-mentioned image forming apparatus 110, and for example, the following aspects may be further changed. Although the above-mentioned image forming apparatus 110 is a color image forming apparatus, the image forming apparatus of the present embodiment may also be a monochrome image forming apparatus. In this case, the image forming apparatus of the present embodiment only needs to include a single image forming unit, for example. In addition, although the above-mentioned image forming apparatus 110 adopts a tandem method, the image forming apparatus of the present embodiment may also adopt a rotation method, for example. Although the charging device 42 is described as a grid-controlled corona charger, the charging device may also be a charging device other than a grid-controlled corona charger (for example, a charging roller, a charging brush, or a corona (corotron) charger). Although the above-mentioned image forming apparatus 110 adopts a contact development method, the image forming apparatus may also adopt a non-contact development method. Although the above-mentioned image forming apparatus 110 adopts a direct transfer method, the image forming apparatus may also adopt an intermediate transfer method. In a known image forming apparatus of a direct transfer method, when a toner image is transferred from a photosensitive body to a recording medium, transfer damage is caused to the photosensitive body. As a result, image memory and fog are easily generated in the known image forming apparatus of a direct transfer method. In contrast, the image forming apparatus of the present embodiment includes the photosensitive body of the first embodiment, and thus can effectively suppress the generation of image memory and fog. The image forming apparatus of the present embodiment has been described above.

[0195] [Third Embodiment: Process Cartridge]

[0196] A third embodiment of the present invention relates to a process cartridge. The process cartridge of this embodiment includes the photosensitive body of the first embodiment.

[0197] Continue to refer to Figure 3 , a first process box 101, a second process box 102, a third process box 103, and a fourth process box 104 as an example of a process box of the present embodiment are described. The first process box 101 to the fourth process box 104 of the present embodiment correspond to the image forming units 40Y, 40M, 40C, and 40K, respectively. The first process box 101 to the fourth process box 104 each include: a corresponding image carrier 100Y, 100M, 100C, or 100K as an image carrier 100. The image carrier 100 is the photosensitive body of the first embodiment. As described in the first embodiment, the photosensitive body of the first embodiment has excellent sensitivity characteristics, wear resistance, and storage properties, and can suppress the generation of image memory and fog. Therefore, the process box of the present embodiment has excellent sensitivity characteristics, wear resistance, and storage properties of the photosensitive body, and can suppress the generation of image memory and fog.

[0198] The processing box of this embodiment may further include, in addition to the image carrier 100, at least one (for example, more than one and less than seven) selected from a charging device 42, an exposure device 44, a developing device 46, a transfer device 62, a cleaning device 48 or a cleaning member 482, and a static removing device 50.

[0199] Similar to the image forming units 40Y, 40M, 40C, and 40K, Figure 3 The first process cartridge 101, the second process cartridge 102, the third process cartridge 103, and the fourth process cartridge 104 shown in the figure each include: corresponding image carriers 100Y, 100M, 100C, and 100K as the image carrier 100, corresponding charging devices 42Y, 42M, 42C, and 42K as the charging device 42, corresponding exposure devices 44Y, 44M, 44C, and 44K as the exposure device 44, corresponding developing devices 46Y, 46M, 46C, and 46K as the developing device 46, corresponding cleaning devices 48Y, 48M, 48C, and 48K as the cleaning device 48, and corresponding static elimination devices 50Y, 50M, 50C, and 50K as the static elimination device 50. However, the process cartridge of this embodiment is not limited to the first process cartridge 101 to the fourth process cartridge 104. As described above, the process cartridge of this embodiment may further include a transfer device 62. In short, the process cartridge of the present embodiment only needs to include the photosensitive body of the first embodiment as the image carrier 100 .

[0200] The process cartridge of this embodiment is designed to be freely attachable and detachable to 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 image carrier 100 and the like can be easily and quickly replaced. Figure 3 The process cartridge according to the present embodiment has been described.

[0201] [Substituent]

[0202] The substituents used in the present specification are described below. Examples of the halogen atom (halogen group) include a fluorine atom (fluoro group), a chlorine atom (chloro group), a bromine atom (bromo group), and an iodine atom (iodo group).

[0203] Unless otherwise specified, an alkyl group is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 8 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 2-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethylbutyl, 2-ethylbutyl, 3-ethylbutyl, straight-chain and branched-chain heptyl, and straight-chain and branched-chain octyl. Examples of other alkyl groups having different carbon number include alkyl groups having a predetermined carbon number among the above-mentioned alkyl groups.

[0204] Unless otherwise specified, alkoxy groups are linear or branched and unsubstituted. Examples of alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, 1-methylbutoxy, 2-methylbutoxy, 3-methylbutoxy, 1-ethylpropoxy, 2-ethylpropoxy, 1,1-dimethylpropoxy, 1,2-dimethylpropoxy, 2,2-dimethylpropoxy, n-hexyloxy, 1-methylpentoxy, 2-methylpentoxy, 3-methylpentoxy, 4-methylpentoxy, 1,1-dimethylbutoxy, 1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,2-dimethylbutoxy, 2,3-dimethylbutoxy, 3,3-dimethylbutoxy, 1,1,2-trimethylpropoxy, 1,2,2-trimethylpropoxy, 1-ethylbutoxy, 2-ethylbutoxy, and 3-ethylbutoxy. Examples of other alkoxy groups having different numbers of carbon atoms include alkoxy groups having a predetermined number of carbon atoms among the above-mentioned alkoxy groups. The substituents used in the present specification have been described above.

[0205] [Example]

[0206] Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to the scope of the examples.

[0207] [Synthesis of polyarylate resin]

[0208] Polyarylate resins (PA-1) to (PA-10) were synthesized by the following method. The monomers used in the synthesis of each polyarylate resin are represented by chemical formulas (BisCZ), (BisB), (DHPE), (BisBP), (OBBOC), (1,4-NADOC), (2,6-NADOC) and (TPC) (hereinafter, the compounds represented by the chemical formulas are respectively referred to as compounds (BisCZ), (BisB), (DHPE), (BisBP), (OBBOC), (1,4-NADOC), (2,6-NADOC) and (TPC)).

[0209] [Chemistry 19]

[0210]

[0211] The reaction vessel uses a three-necked flask including a thermometer, a three-way stopcock and a dropping funnel. Compound (BisCZ) (32.8 mmol), compound (DHPE) (8.2 mmol), 2,6-dimethylphenol (0.413 mmol) as a terminal terminator, sodium hydroxide (98 mmol), and benzyltributylammonium chloride (0.384 mmol) are added to the reaction vessel. The air in the reaction vessel is replaced with argon. Water (300 mL) is added to the contents of the reaction vessel. The contents of the reaction vessel are stirred at 50° C. for 1 hour. The contents of the reaction vessel are cooled to 10° C. to obtain an alkaline aqueous solution SA. Among the bisphenol compounds contained in the alkaline aqueous solution SA, the proportion of compound (BisCZ) is 80.0 mol%, and the proportion of compound (DHPE) is 20.0 mol%.

[0212] Next, compound (OBBOC) (20.8 mmol) and compound (TPC) (11.2 mmol) were dissolved in chloroform (150 mL) to obtain chloroform solution SB. In the dicarboxylic acid dichloride contained in chloroform solution SB, the ratio of compound (OBBOC) was 65.0 mol%, and the ratio of compound (TPC) was 35.0 mol%.

[0213] In the alkaline aqueous solution SA, the chloroform solution SB is slowly added dropwise using a dropping funnel over 110 minutes. While adjusting the temperature (liquid temperature) of the reaction vessel contents to 15°C ± 5°C, the contents of the reaction vessel are stirred for 4 hours to carry out a polymerization reaction. Use a decanter to remove the upper layer (water layer) of the contents of the reaction vessel to obtain an organic layer. Next, ion exchange water (400mL) is added to the conical flask. The obtained organic layer is then added to the conical flask. Chloroform (400mL) and acetic acid (2mL) are then added to the conical flask. The contents of the conical flask are stirred at room temperature (25°C) for 30 minutes. The upper layer (water layer) of the contents of the conical flask is removed using a decanter to obtain an organic layer. Using a separatory funnel, the obtained organic layer is washed with ion exchange water (1L). Repeat the washing with ion exchange water 5 times to obtain a washed organic layer. Next, the washed organic layer is filtered to obtain a filtrate. The obtained filtrate is slowly added dropwise to methanol (1L) to obtain a precipitate. The precipitate was taken out by filtration and vacuum dried at 70° C. for 12 hours. As a result, a polyarylate resin (PA-1) was obtained.

[0214] The polyarylate resins (PA-2) to (PA-10) can be synthesized by the same method as the synthesis of the polyarylate resin (PA-1) except that the monomers of the types and amounts shown in Table 3 are used. In addition, in the synthesis of the polyarylate resins (PA-2) to (PA-10), the total amount of the bisphenol compound is set to 41.0 mmol, and the total amount of the dicarboxylic acid dichloride is set to 32.0 mmol. In Table 3, "%" represents molar %. In Table 3, "ratio (3)" and "ratio (4)" represent ratio (3) and ratio (4), respectively.

[0215] The obtained polyarylate resins (PA-1) to (PA-10) were measured using a proton nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., 600 MHz). 1 H-NMR spectrum. Deuterated chloroform was used as solvent. Tetramethylsilane (TMS) was used as internal standard sample. 1 The chemical shifts read from the H-NMR spectrum confirmed that the polyarylate resins (PA-1) to (PA-10) had repeating units represented by the chemical formulas (PA-1) to (PA-10), respectively. In the polyarylate resins (PA-1) to (PA-10), the content ratio of the repeating unit derived from the bisphenol compound was about 50.0 mol%, and the content ratio of the repeating unit derived from the dicarboxylic acid dichloride was about 50.0 mol% relative to all the repeating units possessed by each resin. Among the polyarylate resins (PA-1) to (PA-10), the polyarylate resins (PA-1) to (PA-4) were specific polyarylate resins.

[0216] [Table 3]

[0217]

[0218] [Chemistry 20]

[0219]

[0220] [Chemistry 21]

[0221]

[0222] [pigment]

[0223] As pigments added to the charge transport layer, compounds represented by the following chemical formulas (K-1) to (K-5) are prepared (hereinafter, sometimes described as pigments (K-1) to (K-5)). Among the pigments (K-1) to (K-5), the pigments (K-1) to (K-2) are phthalocyanine pigments. The pigment (K-1) is Y-type titanyl phthalocyanine. The pigment (K-2) is metal-free phthalocyanine.

[0224] [Chemistry 22]

[0225]

[0226] [Chemistry 23]

[0227]

[0228] <Manufacturing of photoreceptors>

[0229] The photoreceptors of Examples 1 to 13 and Comparative Examples 1 to 18, which are photoreceptors having a negatively chargeable laminated photosensitive layer, were produced by the following method.

[0230] [Example 1]

[0231] (Middle layer formation)

[0232] The metal oxide particles are the trial product "SMT-A" manufactured by Tayca Co., Ltd. The metal oxide particles are particles (number average primary particle size 10 nm) obtained by sequentially performing a primary surface treatment using aluminum oxide and silicon dioxide and a secondary surface treatment using methyl hydrogen polysiloxane on titanium oxide particles. 2 parts by mass of the above-mentioned metal oxide particles, 1 part by mass of polyamide resin ("Amiran (registered trademark) CM8000" manufactured by Toray Co., Ltd., a copolymer of nylon 6, nylon 12, nylon 66 and nylon 610), 10 parts by mass of methanol, 1 part by mass of n-butanol, and 1 part by mass of toluene are mixed. The obtained mixed solution is stirred for 5 hours using a bead mill to fully disperse the titanium oxide particles in the solvent (a mixed organic solvent of methanol, n-butanol and toluene). The dispersed mixed solution is filtered using a 5 μm filter. Thus, a coating solution for an intermediate layer is prepared.

[0233] The conductive substrate is an aluminum drum support (diameter 30 mm). The intermediate layer coating solution is applied to the conductive substrate by dip coating. Then, the coated conductive substrate is heated and dried at 130° C. for 30 minutes. Thus, an intermediate layer (film thickness: 1.5 μm) is formed on the conductive substrate.

[0234] (Charge Generation Layer Formation)

[0235] 2.3 parts by mass of Y-type phthalocyanine titanyl, 1.0 part by mass of a polyvinyl acetal resin as a base resin ("Esleck (registered trademark) BX-5" manufactured by Sekisui Chemical Co., Ltd.), 40.0 parts by mass of propylene glycol monomethyl ether, and 40.0 parts by mass of tetrahydrofuran are mixed to obtain a mixed solution. The obtained mixed solution is dispersed for 12 hours using a bead mill. The dispersed mixed solution is filtered using a 3 μm filter. Thus, a coating solution for a charge generating layer is obtained. Next, the coating solution for a charge generating layer is applied on the intermediate layer by dip coating. The applied coating solution for a charge generating layer is dried at 50°C for 5 minutes to form a charge generating layer (film thickness: 0.3 μm) on the intermediate layer.

[0236] (Charge Transport Layer Formation)

[0237] 45.0 parts by mass of hole transport agent (H-1), 100.0 parts by mass of polyarylate resin (PA-1) as a binder resin, 0.1 parts by mass of pigment (K-1), 0.05 parts by mass of silicone oil ("KF96-50CS" of Shin-Etsu Chemical Co., Ltd., dimethyl silicone oil), 560.0 parts by mass of tetrahydrofuran, and 140.0 parts by mass of toluene were mixed to obtain a coating liquid for a charge transport layer. Next, the coating liquid for a charge transport layer was applied on the charge generating layer by dip coating. The applied coating liquid for a charge transport layer was dried at 120° C. for 40 minutes to form a charge transport layer (film thickness: 20 μm) on the charge generating layer. Thus, the photoreceptor of Example 1 was obtained.

[0238] [Examples 2 to 13 and Comparative Examples 1 to 18]

[0239] The photoreceptors of Examples 2 to 13 and Comparative Examples 1 to 18 were manufactured by the same method as that of the photoreceptor of Example 1 except that the following aspects were changed. In the manufacture of the photoreceptors of Examples 2 to 13 and Comparative Examples 1 to 18, the types of polyarylate resins and hole transport agents used to form the charge transport layer, and the types and amounts of pigments were changed as shown in Table 4. In the manufacture of the photoreceptor of Comparative Example 16, the charge transport layer coating liquid gelled and the photoreceptor could not be manufactured. In addition, in the manufacture of the photoreceptor of Comparative Example 18, although the photoreceptor could be manufactured, the charge transport layer coating liquid was turbid.

[0240] [Table 4]

[0241]

[0242]

[0243] <Evaluation>

[0244] The sensitivity characteristics, abrasion resistance, storage stability, and the presence or absence of image memory and fogging of each photoreceptor were evaluated by the following methods. The evaluation results are shown in Table 5.

[0245] [Sensitivity characteristics]

[0246] The sensitivity characteristics are evaluated using a photoreceptor electrical characteristic detection device (manufactured by GENTEC Corporation) in an environment of temperature 23°C and humidity 50% RH. In the evaluation of the sensitivity characteristics, two types of sensitivity characteristics (sensitivity characteristics A and B) are evaluated. A photoreceptor that passes both sensitivity characteristics A and B is judged to have excellent sensitivity characteristics. On the other hand, a photoreceptor that fails at least one of the sensitivity characteristics A and B is judged to have insufficient sensitivity characteristics. In addition, sensitivity characteristic B is equivalent to the exposure condition when expressing halftones. Therefore, a photoreceptor that passes sensitivity characteristic B is judged to have excellent halftone expression.

[0247] (Sensitivity Characteristics A)

[0248] The surface potential of the photoreceptor was charged to -500 V (charged potential) using the above device. Then, the surface of the photoreceptor was irradiated with exposure light (wavelength 780 nm, exposure amount 0.30 μJ / cm 2 ). Next, the surface potential of the photoreceptor 77 milliseconds after exposure (post-exposure potential A) was measured. The obtained post-exposure potential A was used as the measured value of the sensitivity characteristic A. The sensitivity characteristic A was determined according to the following criteria.

[0249] (Standard for sensitivity characteristic A)

[0250] A (acceptable): The absolute value of the potential A after exposure is 100 V or less.

[0251] B (failure): The absolute value of the potential A after exposure is greater than 100V.

[0252] (Sensitivity Characteristics B)

[0253] The surface potential of the photoreceptor was charged to -500 V (charged potential) using the above device. Then, the surface of the photoreceptor was irradiated with exposure light (wavelength 780 nm, exposure amount 0.15 μJ / cm 2). Next, the surface potential of the photoreceptor 77 milliseconds after exposure (post-exposure potential B) was measured. The obtained post-exposure potential B was used as the measured value of the sensitivity characteristic B. The sensitivity characteristic B was determined according to the following criteria.

[0254] (Standard for sensitivity characteristic B)

[0255] A (acceptable): The absolute value of the potential B after exposure is 250 V or less.

[0256] B (failure): The absolute value of the potential B after exposure is greater than 250V.

[0257] [Abrasion resistance]

[0258] In the evaluation of abrasion resistance, a color printer ("C844dnw" manufactured by OKI Industry Co., Ltd.) was used as the evaluation machine. Cyan toner was filled in the toner box of the evaluation machine. First, the film thickness T1 of the charge transport layer of the photoreceptor to be evaluated was measured. Next, the photoreceptor to be evaluated was mounted on a cyan box, and the cyan box was mounted on the evaluation machine. Next, in a normal temperature and humidity environment (temperature 23°C and humidity 50% RH), the evaluation machine was used to print image I (a pattern image with a printing rate of 1%) on 4,000 sheets of paper. Next, in a high temperature and high humidity environment (temperature 32°C and humidity 85% RH), the evaluation machine was used to print image I on 4,000 sheets of paper. Next, in a low temperature and low humidity environment (temperature 10°C and humidity 15% RH: sometimes referred to as LL environment below), the evaluation machine was used to print image I on 4,000 sheets of paper. After printing under the LL environment, let the evaluation machine stand for 2 hours. Next, print a solid image (image with an image density of 100%) on a sheet of paper under the LL environment. Then, take the photoreceptor to be evaluated out of the evaluation machine. Then, measure the film thickness T2 of the charge transport layer of the photoreceptor. Next, find the change in the film thickness of the charge transport layer before and after printing, i.e., the amount of wear (T1-T2, unit: μm). Based on the amount of wear, determine the wear resistance of the photoreceptor according to the following criteria.

[0259] (Standard for wear resistance)

[0260] A (good): The wear amount is 2.0 μm or less.

[0261] B (bad): The wear amount is greater than 2.0 μm.

[0262] [Image Memory]

[0263] In the evaluation of image memory, a color printer ("C844dnw" manufactured by OKI Industries, Ltd.) was used as the evaluation machine. Cyan toner was filled in the toner box of the evaluation machine. The photoreceptor to be evaluated was installed on the cyan box, and the cyan box was installed on the evaluation machine. Next, for the evaluation machine, the print medium type (recording medium) was set to thick paper, and the paper feed direction was set to vertical feed. Next, 100 cyan solid images were printed on an A4-sized recording medium ("Reserpie WETY-145" manufactured by Oji Paper Industries, Ltd.) using the evaluation machine. Next, a cyan halftone image (image density of 50%) was printed on A3-sized plain paper. The halftone image printed on A3-sized plain paper was used as the evaluation image. When printing a cyan solid image, in the photoreceptor, the paper passing area through which the A4-sized recording medium passes is indirectly damaged by transfer due to the passage of the recording medium (charge is accumulated on the charge transport layer). On the other hand, in the photoreceptor, the non-paper passing area through which the A4-sized recording medium does not pass is directly damaged by transfer. Therefore, in the evaluation image, there is sometimes a concentration difference between the image formed by the paper passing area of ​​the photoreceptor (paper passing area image) and the image formed by the non-paper passing area of ​​the photoreceptor (non-paper passing area image). Specifically, the non-paper passing area image is sometimes darker than the paper passing area image. In the evaluation of image memory, the concentration difference between the paper passing area image and the non-paper passing area image is compared visually. Next, the photoreceptor with less concentration difference is evaluated as being able to suppress the generation of image memory. Image memory is determined according to the following criteria.

[0264] (Standards for image memory)

[0265] Particularly good (A): No difference in image density was observed between the image in the paper-passing region and the image in the non-paper-passing region.

[0266] Good (B): A slight difference in image density is observed between the image in the paper passing region and the image in the non-paper passing region.

[0267] Bad (C): A clear difference in image density was observed between the image in the paper-passing region and the image in the non-paper-passing region.

[0268] [Gray fog]

[0269] In the evaluation of fog, a color printer ("C844dnw" manufactured by OKI Industries, Ltd.) was used as the evaluation machine. Cyan toner was filled in the toner box of the evaluation machine. The photoreceptor to be evaluated was mounted on the cyan box, and the cyan box was mounted on the evaluation machine. Image I (a pattern image with a printing rate of 1%) was printed on 2,000 sheets of paper using the evaluation machine at a temperature of 32°C and a humidity of 85% RH (under an HH environment). Next, the evaluation machine was left to stand for 12 hours under the HH environment. Next, a white paper image was printed on 1 sheet of paper under the HH environment. Next, the photoreceptor was removed from the evaluation machine. Next, a tape ("Scott (registered trademark) Mending Tape" manufactured by 3M) was used to collect the toner attached to the surface of the photoreceptor. Next, the image density of the tape was measured using a fluorescence spectrophotometer ("FD-5" manufactured by Konica Minolta, Inc.). Fog was determined based on the following criteria.

[0270] (Gray fog standard)

[0271] A (particularly good): The image density is 1.3 or less.

[0272] B (good): The image density is more than 1.3 and 1.6 or less.

[0273] C (poor): The image density is greater than 1.6.

[0274] [Storage]

[0275] The photosensitive body to be evaluated is mounted on an imaging drum ("DR-C3BC" manufactured by OKI Industry Co., Ltd.). Next, the charging roller of the imaging drum is brought into contact with a portion of the peripheral surface of the photosensitive body. Hereinafter, in the photosensitive body, the portion of the peripheral surface that is in contact with the charging roller is recorded as the "component contact area". In addition, in the photosensitive body, the area other than the component contact area is recorded as the "non-component contact area". The imaging drum with the photosensitive body mounted is left to stand for four weeks in an environment with a temperature of 50°C and a humidity of 85% RH. After standing for four weeks, the imaging drum with the photosensitive body mounted is immediately mounted on the above-mentioned evaluation machine. Next, an image (a cyan halftone image with a printing rate of 50%) is printed on a sheet of paper using the evaluation machine. This image is used as an evaluation image. In addition, in the component contact area of ​​the photosensitive body, due to the contact with the charging roller, the charge transport layer is subjected to pressure, and components seeping out from the charging roller adhere to the surface of the charge transport layer. As a result, in the evaluation image, the image density of the image (image A) formed by the component contact area of ​​the photoreceptor is sometimes greater than the image density of the image (image B) formed by the non-component contact area of ​​the photoreceptor. However, in a photoreceptor with excellent storage properties, the above-mentioned image density difference is difficult to occur. In the storage evaluation of the photoreceptor, the image density difference between images A and B is compared by visual observation. Then, the photoreceptor with a small image density difference is evaluated as having excellent storage properties. The storage properties of the photoreceptor are determined according to the following criteria.

[0276] (Standards for preservation)

[0277] A (particularly good): No difference in image density was observed between images A and B.

[0278] B (good): A slight difference in image density was observed between images A and B.

[0279] C (poor): A difference in image density was clearly observed between images A and B.

[0280] [Table 5]

[0281]

[0282] As shown in Tables 3 to 5, the photoreceptors of Examples 1 to 13 have a conductive substrate and a photosensitive layer indirectly disposed on the conductive substrate. The photosensitive layer has a charge generating layer and a charge transporting layer. The charge transporting layer contains a binder resin, a hole transporting agent and a phthalocyanine pigment. The binder resin contains a specific polyarylate resin. The specific polyarylate resin has: a first repeating unit represented by general formula (1), a second repeating unit represented by chemical formula (2), a third repeating unit represented by chemical formula (3), and a fourth repeating unit represented by chemical formula (4). The ratio (3) of the number of moles of the third repeating unit to the total number of moles of the first repeating unit and the third repeating unit is greater than 0.0 mol% and less than 50.0 mol%. The ratio (4) of the number of moles of the fourth repeating unit to the total number of moles of the second repeating unit and the fourth repeating unit is greater than 30.0 mol% and less than 70.0 mol%. The photoreceptors of Examples 1 to 13 have excellent sensitivity characteristics, wear resistance and storage properties, and can suppress the generation of image memory and fog.

[0283] On the other hand, in the photoreceptor of Comparative Example 1, the charge transport layer did not contain a pigment. As a result, the photoreceptor of Comparative Example 1 generated image memory and fog. In the photoreceptors of Comparative Examples 2 to 4, the charge transport layer contained a pigment other than the phthalocyanine pigment. The photoreceptors of Comparative Examples 2 to 4 were able to suppress the generation of fog as compared with the photoreceptor of Comparative Example 1. However, the photoreceptors of Comparative Examples 2 to 4 were unable to suppress the generation of image memory.

[0284] The photoreceptors of Comparative Examples 5 to 9 used a polyarylate resin (PA-5) different from the specific polyarylate resin as a binder resin for the charge transport layer. In addition, in the photoreceptors of Comparative Examples 4, 6 to 9, the charge transport layer did not contain a phthalocyanine pigment. As a result, the photoreceptors of Comparative Examples 4, 6 to 9 had poor wear resistance and could not suppress the generation of image memory. The photoreceptor of Comparative Example 5 was able to suppress the generation of image memory because the charge transport layer contained a phthalocyanine pigment. However, the photoreceptor of Comparative Example 5 also had poor wear resistance.

[0285] The photoreceptors of Comparative Examples 10 to 14 used a polyarylate resin (PA-6) different from the specific polyarylate resin as a binder resin for the charge transport layer. In addition, in the photoreceptors of Comparative Examples 10, 12 to 14, the charge transport layer did not contain a phthalocyanine pigment. As a result, the photoreceptors of Comparative Examples 10, 12 to 14 had poor storage properties and could not suppress the generation of image memory and fog. The photoreceptor of Comparative Example 11 was able to suppress the generation of image memory because the charge transport layer contained a phthalocyanine pigment. However, the photoreceptor of Comparative Example 5 also had poor storage properties and could not suppress the generation of fog.

[0286] The photoreceptor of Comparative Example 15 used a polyarylate resin (PA-7) different from the specific polyarylate resin as a binder resin for the charge transport layer. The polyarylate resin (PA-7) did not have the third repeating unit. As a result, the photoreceptor of Comparative Example 15 had poor abrasion resistance.

[0287] In the manufacture of the photoreceptor of Comparative Example 16, a polyarylate resin (PA-8) different from the specific polyarylate resin was used as a binder resin for the charge transport layer. The ratio (3) of the polyarylate resin (PA-8) was 50.0 mol % or more. As a result, in the manufacture of the photoreceptor of Comparative Example 16, the charge transport layer coating liquid was gelled, and thus the photoreceptor could not be manufactured.

[0288] The photoreceptor of Comparative Example 17 used a polyarylate resin (PA-9) different from the specific polyarylate resin as a binder resin for the charge transport layer. The polyarylate resin (PA-9) did not have a fourth repeating unit. As a result, the storage stability of the photoreceptor of Comparative Example 17 was poor.

[0289] The photoreceptor of Comparative Example 18 used a polyarylate resin (PA-10) different from the specific polyarylate resin as a binder resin for the charge transport layer. The ratio (4) of the polyarylate resin (PA-10) was 70.0 mol % or more. As a result, the photoreceptor of Comparative Example 18 had poor abrasion resistance.

Claims

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer directly or indirectly disposed on the conductive substrate, The photosensitive layer has a charge generating layer and a charge transporting layer. The charge transport layer contains a binder resin, a hole transport agent and a phthalocyanine pigment. The binder resin contains a specific polyarylate resin, The specific polyarylate resin has a first repeating unit represented by the following general formula (1), a second repeating unit represented by the following chemical formula (2), a third repeating unit represented by the following chemical formula (3), and a fourth repeating unit represented by the following chemical formula (4). The ratio of the mole number of the third repeating unit to the total mole number of the first repeating unit and the third repeating unit is greater than 0.0 mol % and less than 50.0 mol %, The ratio of the molar number of the fourth repeating unit to the total molar number of the second repeating unit and the fourth repeating unit is 30.0 mol% or more and less than 70.0 mol%, In the general formula (1), X represents a divalent group having 1 to 10 carbon atoms, and R 1 and R 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

2. The electrophotographic photoreceptor according to claim 1, wherein The first repeating unit is represented by the following chemical formula (1-1) or (1-2), [Chemistry 2] 3. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that: The phthalocyanine pigment includes at least one of metal-free phthalocyanine and a compound represented by the following general formula (P-1), In the general formula (P-1), M represents a metal atom which may have a ligand.

4. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that: The phthalocyanine pigment includes titanyl phthalocyanine.

5. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that: In the charge transport layer, the content of the phthalocyanine pigment is 0.1 parts by mass or more and 0.5 parts by mass or less relative to 100.0 parts by mass of the binder resin.

6. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that: With respect to all repeating units of the specific polyarylate resin, The content ratio of the first repeating unit is 20.0 mol% or more and 45.0 mol% or less, The content ratio of the second repeating unit is 10.0 mol% or more and 40.0 mol% or less, The content ratio of the third repeating unit is 5.0 mol% or more and 30.0 mol% or less, The content ratio of the fourth repeating unit is 10.0 mol % or more and 40.0 mol % or less.

7. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that: The specific polyarylate resin includes at least one of the resins represented by the following chemical formulas (pa-1) to (pa-4), 8. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that: The charge transport layer is the outermost surface layer. 9 . A process cartridge comprising the electrophotographic photoreceptor according to claim 1 .

10. An image forming device comprising: An image carrier; A charging device for charging the surface of the image carrier; an exposure device for exposing the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier; a developing device for supplying toner to the surface of the image carrier to develop the electrostatic latent image into a toner image; as well as a transfer device for transferring the toner image from the image carrier to a transfer object, The image carrier is the electrophotographic photoreceptor according to any one of claims 1 to 8.

Images