Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

The present application provides an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. The electrophotographic photoreceptor has a conductive base body and at least one photosensitive layer containing a specific photosensitive layer. The specific photosensitive layer contains a charge generating agent, a binding resin, an electron transporting agent, and a hole transporting agent. The binding resin contains a polyarylate resin. The polyarylate resin has repeating units (1), (2), (3), and (4). The content ratio of the repeating unit (3) is greater than 0% and less than 50% with respect to the total number of the repeating units (1) and (3). The content ratio of the repeating unit (4) is 35% or more and less than 70% with respect to the total number of the repeating units (2) and (4). The electron transporting agent contains a compound represented by formula (11), (12), (13), (14), (15), (16), or (17).

Description

Technical Field

[0001] This invention relates to an electrophotographic photosensitive element, a processing cartridge, and an image forming apparatus. Background Technology

[0002] Electrophotographic photosensitive elements serve as image carriers in electrophotographic image forming apparatuses (e.g., printers or multifunction printers). Electrophotographic photosensitive elements possess a photosensitive layer. Examples of electrophotographic photosensitive elements include single-layer electrophotographic photosensitive elements and multilayer electrophotographic photosensitive elements. A single-layer electrophotographic photosensitive element possesses a single photosensitive layer, which has both charge generation and charge transport functions. A multilayer electrophotographic photosensitive element contains a charge generation layer and a charge transport layer; the charge generation layer has a charge generation function, and the charge transport layer has a charge transport function.

[0003] For example, an electrophotographic photosensitive material is known whose surface layer contains a polyarylate resin obtained from a dicarboxylic acid component and a diphenol component, as shown in the following formula.

[0004] Summary of the Invention

[0005] However, through research, the inventors have found that the aforementioned electrophotographic photoresist is insufficient in improving the solubility of the binder resin in the solvent to effectively form the photosensitive layer. Furthermore, the inventors have also found that the aforementioned electrophotographic photoresist is insufficient in terms of resistance to fogging.

[0006] The present invention was made in view of the above-mentioned problems, and its object is to provide an electrophotographic photosensitive material that has a well-formed photosensitive layer and excellent anti-fogging properties. Furthermore, another object of the present invention is to provide a processing cartridge and an image forming apparatus capable of forming images with less fog.

[0007] The electrophotographic photoreceptor of the present invention comprises a conductive substrate and at least one photosensitive layer. The at least one photosensitive layer comprises a specific photosensitive layer. The specific photosensitive layer is located on the outermost surface of the at least one photosensitive layer. The specific photosensitive layer contains a charge-generating agent, a binding resin, an electron transporter, and a hole transporter. The binding resin comprises a polyaryl ester resin. The polyaryl ester resin has repeating units as shown in formulas (1), (2), (3), and (4). The content of repeating units shown in formula (3) is greater than 0% and less than 50% relative to the total number of repeating units shown in formulas (1) and (3). The content of repeating units shown in formula (4) is more than 35% and less than 70% relative to the total number of repeating units shown in formulas (2) and (4). The electron transporter contains a compound shown in formula (11), (12), (13), (14), (15), (16), or (17).

[0008]

[0009] In the above formula (1), R 1 and R 2 X represents a methyl group, and X is a divalent group represented by formula (X1). Alternatively, R 1 and R 2 X represents a hydrogen atom, and X is a divalent group as shown in formula (X2).

[0010]

[0011] In equations (X1) and (X2), * represents a bonding bond.

[0012]

[0013] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23 and Q 24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q 42 and Q 43 Q in equation (15) 51 Q 52 Q 53 and Q 54 Q in equation (16) 61 and Q 62 and Q in equation (17) 71 Q 72 Q 73 Q 74 Q 75 and Q 76 Each of these terms independently represents a hydrogen atom, a halogen atom, a cyano group, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C1-C6 alkoxy group, an unsubstituted C6-C14 aryl group, or a C6-C14 aryl group substituted with at least one substituent selected from the group consisting of C1-C6 alkyl and halogen atoms. Y in formula (17) 1 and Y 2 Each can be used independently to represent either an oxygen atom or a sulfur atom.

[0014] The processing box of the present invention includes at least one device selected from the group consisting of a charging device, an exposure device, a developing device, and a transfer device, as well as the above-described electrophotographic photosensitive element.

[0015] The image forming apparatus of the present invention includes: an image carrier; a charging device for charging the surface of the image carrier to a positive polarity; 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 and developing the electrostatic latent image into a toner image; and a transfer device for transferring the toner image from the image carrier to a transfer substrate. The image carrier is the aforementioned electrophotographic photosensitive material.

[0016] The electrophotographic photosensitive layer of the present invention is well formed and exhibits excellent resistance to fogging. The processing cartridge and image forming apparatus of the present invention are capable of forming images with less fogging. Attached Figure Description

[0017] Figure 1 This is a partial cross-sectional view of a single-layer electrophotographic photosensitive element, which is an example of an electrophotographic photosensitive element according to the first embodiment of the present invention.

[0018] Figure 2 This is a partial cross-sectional view of a single-layer electrophotographic photosensitive element, which is an example of an electrophotographic photosensitive element according to the first embodiment of the present invention.

[0019] Figure 3 This is a partial cross-sectional view of a single-layer electrophotographic photosensitive element, which is an example of an electrophotographic photosensitive element according to the first embodiment of the present invention.

[0020] Figure 4 This is a partial cross-sectional view of a positively charged laminated electrophotographic photosensitive unit, which is an example of an electrophotographic photosensitive unit according to the first embodiment of the present invention.

[0021] Figure 5 This is a partial cross-sectional view of a positively charged laminated electrophotographic photosensitive unit, which is an example of an electrophotographic photosensitive unit according to the first embodiment of the present invention.

[0022] Figure 6 This is a partial cross-sectional view of a positively charged laminated electrophotographic photosensitive unit, which is an example of an electrophotographic photosensitive unit according to the first embodiment of the present invention.

[0023] Figure 7 This is an example of an image forming apparatus according to the second embodiment of the present invention.

[0024] Figure 8 It is polyaryl ester resin (R-1) 1 H-NMR spectrum.

[0025] Figure 9 This is an example structural diagram of a scraping device.

[0026] Figure 10 yes Figure 9 A cross-sectional view of line XX in the diagram.

[0027] Figure 11 yes Figure 9 Side view of the stationary stage, scraping needle, and electrophotographic photosensitive element.

[0028] Figure 12 This refers to scratches formed on the surface of the photosensitive layer. Detailed Implementation

[0029] The embodiments of the present invention will now be described in detail. However, the present invention is not limited to the embodiments described below, and appropriate modifications can be made within the scope of the present invention. Hereinafter, the term "class" is sometimes added after the compound name to collectively refer to the compound and its derivatives. Also, when "class" is added after the compound name to indicate the name of a polymer, it indicates that the repeating unit of the polymer originates from the compound or its derivative. Furthermore, "general formula" and "chemical formula" are collectively referred to as "formula". "Independent" in the description of a formula means that the same group or different groups can be represented. Unless otherwise stated, each component described in this specification can be used alone or in combination of two or more.

[0030] First, the substituents used in this specification will be explained. Examples of halogen atoms (halogen groups) include: fluorine atoms (fluorinyl groups), chlorine atoms (chloroyl groups), bromine atoms (bromoyl groups), and iodine atoms (iodoyl groups).

[0031] Unless otherwise stated, C1-C8 alkyl, C1-C6 alkyl, C1-C5 alkyl, C1-C4 alkyl and C1-C3 alkyl are straight-chain or branched and are unsubstituted. Examples of C1-C8 alkyl groups 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 and 3-ethylbutyl, heptyl in both linear and branched forms, and octyl in both linear and branched forms. Examples of C1-C6 alkyl, C1-C5 alkyl, C1-C4 alkyl, and C1-C3 alkyl are examples of C1-C8 alkyl with the corresponding number of carbon atoms.

[0032] Unless otherwise stated, C1-C10 perfluoroalkyl, C3-C10 perfluoroalkyl, C5-C7 perfluoroalkyl, and C6 perfluoroalkyl are all straight-chain or branched and are unsubstituted. Examples of C1-C10 perfluoroalkyl groups include: trifluoromethyl, perfluoroethyl, perfluoron-propyl, perfluoroisopropyl, perfluoron-butyl, perfluorosec-butyl, perfluorotert-butyl, perfluoron-pentyl, perfluoro-1-methylbutyl, perfluoro-2-methylbutyl, perfluoro-3-methylbutyl, perfluoro-1-ethylpropyl, perfluoro-2-ethylpropyl, perfluoro-1,1-dimethylpropyl, perfluoro-1,2-dimethylpropyl, perfluoro-2,2-dimethylpropyl, perfluoron-hexyl, perfluoro-1-methylpentyl, perfluoro-2-methylpentyl, perfluoro-3-methylpentyl, perfluoro-4-methyl... Perfluoropentyl, perfluoro-1,1-dimethylbutyl, perfluoro-1,2-dimethylbutyl, perfluoro-1,3-dimethylbutyl, perfluoro-2,2-dimethylbutyl, perfluoro-2,3-dimethylbutyl, perfluoro-3,3-dimethylbutyl, perfluoro-1,1,2-trimethylpropyl, perfluoro-1,2,2-trimethylpropyl, perfluoro-1-ethylbutyl, perfluoro-2-ethylbutyl and perfluoro-3-ethylbutyl, linear and branched perfluoroheptyl, linear and branched perfluorooctyl, linear and branched perfluorononyl and linear and branched perfluorodecyl. Examples of C3-C10 perfluoroalkyl, C5-C7 perfluoroalkyl and C6 perfluoroalkyl are examples of C1-C10 perfluoroalkyl with the corresponding number of carbon atoms.

[0033] Unless otherwise stated, C1-C6 and C1-C3 alkylidenes are straight-chain or branched and are unsubstituted. Examples of C1-C6 alkylidenes include: methylene (methylene), ethoxylide, n-propylidene, isopropylidene, n-butylidene, sec-butylidene, tert-butylidene, n-pentylidene, 1-methylbutylidene, 2-methylbutylidene, 3-methylbutylidene, 1-ethylpropylidene, 2-ethylpropylidene, 1,1-dimethylpropylidene, 1,2-dimethylpropylidene, 2,2-dimethylpropylidene, n-hexaneidene, 1-methylpentylidene Alkyl groups include 2-methylpentylyl, 3-methylpentylyl, 4-methylpentylyl, 1,1-dimethylbutylyl, 1,2-dimethylbutylyl, 1,3-dimethylbutylyl, 2,2-dimethylbutylyl, 2,3-dimethylbutylyl, 3,3-dimethylbutylyl, 1,1,2-trimethylpropenyl, 1,2,2-trimethylpropenyl, 1-ethylbutylyl, 2-ethylbutylyl, and 3-ethylbutylyl. Examples of C1-C3 alkylyl groups are examples of C1-C6 alkylyl groups with the corresponding number of carbon atoms.

[0034] Unless otherwise stated, C1-C8 alkoxy, C1-C6 alkoxy, and C1-C3 alkoxy are straight-chain or branched and are unsubstituted. Examples of C1-C8 alkoxy groups 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-hexoxy, 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, 3-ethylbutoxy, straight-chain and branched heptoxy groups, and straight-chain and branched octoxy groups. Examples of C1-C6 alkoxy and C1-C3 alkoxy are each examples of C1-C8 alkoxy with the corresponding number of carbon atoms.

[0035] Unless otherwise stated, C2-C6 alkenyl groups are linear or branched and are unsubstituted. C2-C6 alkenyl groups have one to three double bonds. Examples of C2-C6 alkenyl groups include vinyl, propenyl, butenyl, butadienyl, pentenyl, hexenyl, hexadienyl, and hexamethylenetriyne.

[0036] Unless otherwise stated, C6-C14 aryl and C6-C10 aryl groups are unsubstituted. Examples of C6-C14 aryl groups include phenyl, naphthyl, indacenyl, biphenylenyl, acenaphthylenyl, anthracene, and phenanthryl. Examples of C6-C10 aryl groups include phenyl and naphthyl. The substituents used in this specification have been described above.

[0037] <First Embodiment: Electrophotographic Photoreceptor>

[0038] A first embodiment of the present invention relates to an electrophotographic photoreceptor (hereinafter, sometimes referred to as a photoreceptor). The photoreceptor of the first embodiment includes a conductive substrate and at least one photosensitive layer. The at least one photosensitive layer includes a first photosensitive layer (equivalent to a specific photosensitive layer). The first photosensitive layer is located on the outermost side of the at least one photosensitive layer. The surface side refers to the outer surface side of the photoreceptor (e.g., the surface on which light is incident during exposure), which is the side opposite to the conductive substrate side of the photoreceptor.

[0039] The photoreceptor in the first embodiment is, for example, a single-layer electrophotographic photoreceptor (hereinafter, sometimes referred to as a single-layer photoreceptor) and a positively charged multilayer electrophotographic photoreceptor (hereinafter, sometimes referred to as a positively charged multilayer photoreceptor).

[0040] (Single-layer photoreceptor)

[0041] The following is for reference Figures 1-3 The single-layer photoreceptor 1, which is an example of a photoreceptor in the first embodiment, will be described. Figures 1-3 Each is a partial cross-sectional view of a single-layer photoreceptor 1.

[0042] like Figure 1 As shown, a single-layer photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 in the single-layer photoreceptor 1 is a single layer (1 layer). The 1-layer photosensitive layer 3 is a single-layer photosensitive layer 3s serving as the first photosensitive layer.

[0043] like Figure 2 As shown, based on the conductive substrate 2 and the monolayer photosensitive layer 3s, the monolayer photoreceptor 1 can further include an intermediate layer 4 (base layer). The intermediate layer 4 is located between the conductive substrate 2 and the monolayer photosensitive layer 3s. Figure 1 As shown, the single-layer photosensitive layer 3s can also be directly applied to the conductive substrate 2. Alternatively, as... Figure 2 As shown, the single-layer photosensitive layer 3s can also be placed on the conductive substrate 2 with the intermediate layer 4 in between.

[0044] like Figure 3 As shown, based on the conductive substrate 2 and the monolayer photosensitive layer 3s, the monolayer photoreceptor 1 can further possess a protective layer 5. The protective layer 5 is on the monolayer photosensitive layer 3s. For example... Figure 1 and Figure 2 As shown, a single-layer photosensitive layer 3s is preferably used as the outermost surface layer of the single-layer photoreceptor 1. By using a single-layer photosensitive layer 3s containing the polyaryl ester resin (PA) and the specific electron transport agent described later as the outermost surface layer, the anti-hazing properties of the single-layer photoreceptor 1 are easily improved. Furthermore, as... Figure 3 As shown, the protective layer 5 can also serve as the outermost surface layer of the single-layer photoreceptor 1.

[0045] The thickness of the single-layer photosensitive layer 3s is not particularly limited, but is preferably 5μm to 100μm, and more preferably 10μm to 50μm.

[0046] The single-layer photosensitive layer 3s, serving as the first photosensitive layer, contains a charge-generating agent, a binder resin, an electron transporter, and a hole transporter. Hereinafter, "the hole transporter contained in the single-layer photosensitive layer 3s" is sometimes referred to as "hole transporter (SL)". Also, "the binder resin contained in the single-layer photosensitive layer 3s" is sometimes referred to as "binding resin (SL)". The single-layer photosensitive layer 3s may also contain additives as needed. As described above, refer to... Figures 1-3 This describes a single-layer photoreceptor 1.

[0047] (Positively charged multilayer photoreceptor)

[0048] The following is for reference Figures 4-6 The positively charged laminated photoreceptor 10 of the first embodiment, which is an example of a photoreceptor, will be described. Figures 4-6 Each is a partial cross-sectional view of a positively charged laminated photoreceptor 10.

[0049] like Figure 4 As shown, the positively charged laminated photoreceptor 10 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 in the positively charged laminated photoreceptor 10 has two layers. The two-layer photosensitive layer 3 consists of a charge generation layer 12 and a charge transport layer 11. The charge generation layer 12 is the first photosensitive layer. The charge transport layer 11 is the second photosensitive layer. The charge generation layer 12, as the first photosensitive layer, is located on the outermost side of the two-layer photosensitive layer 3 (charge generation layer 12 and charge transport layer 11). The charge transport layer 11 is closer to the conductive substrate 2 side than the charge generation layer 12. Since the charge generation layer 12 is located on the outermost side (opposite to the conductive substrate 2 side of the positively charged laminated photoreceptor 10), for example, the charge transport layer 11 is on the conductive substrate 2, and the charge generation layer 12 is on the charge transport layer 11. In the image forming apparatus 100 (see reference...) Figure 7 When a positively charged laminated photoreceptor 10 is provided, the charging device 42 (see reference) Figure 7 The positively charged stacked photoreceptor 10 is charged to the positive polarity.

[0050] like Figure 5 As shown, based on the conductive substrate 2 and the photosensitive layer 3, the positively charged laminated photoreceptor 10 may further include an intermediate layer 4 (base layer). The intermediate layer 4 is located between the conductive substrate 2 and the photosensitive layer 3 (e.g., charge transport layer 11). Figure 4 As shown, the photosensitive layer 3 (e.g., charge transport layer 11) can be directly on the conductive substrate 2. Alternatively, as... Figure 5 As shown, the photosensitive layer 3 (e.g., charge transport layer 11) can also be on the conductive substrate 2 with an intermediate layer 4 in between.

[0051] like Figure 6As shown, based on the conductive substrate 2 and the photosensitive layer 3, the positively charged laminated photoreceptor 10 may further include a protective layer 5. The protective layer 5 is located on the photosensitive layer 3 (e.g., the charge-generating layer 12). Figure 4 and Figure 5 As shown, the photosensitive layer 3 is preferably used as the outermost surface layer of the positively charged laminated photoreceptor 10. By using the photosensitive layer 3 (e.g., charge generating layer 12) containing the polyaryl ester resin (PA) and the specific electron transport agent described later as the outermost surface layer, the anti-fogging properties of the positively charged laminated photoreceptor 10 are easily improved. Furthermore, as... Figure 6 As shown, the protective layer 5 can also serve as the outermost surface layer of the positively charged laminated photoreceptor 10.

[0052] The thickness of the charge generation layer 12 is preferably 2 μm or more and 100 μm or less, more preferably 15 μm or more and 30 μm or less. The thickness of the charge transport layer 11 is preferably 2 μm or more and 100 μm or less, more preferably 3 μm or more and 20 μm or less, and even more preferably 5 μm or more and 15 μm or less.

[0053] The charge generating layer 12, which serves as the first photosensitive layer, contains a charge generating agent, a binder resin, an electron transporter, and a hole transporter. Hereinafter, "the hole transporter contained in the charge generating layer 12" is sometimes referred to as "hole transporter (CG)". Also, "the binder resin contained in the charge generating layer 12" is sometimes referred to as "binding resin (CG)". The charge generating layer 12 may also contain additives as needed.

[0054] The charge transport layer 11, serving as the second photosensitive layer, contains a hole transport agent and a binding resin. Hereinafter, "the hole transport agent contained in the charge transport layer 11" is sometimes referred to as "hole transport agent (CT)". Also, "the binding resin contained in the charge transport layer 11" is sometimes referred to as "binding resin (CT)". The charge transport layer 11 may also contain additives as needed. As described above, refer to... Figures 4-6 This describes the positively charged laminated photoreceptor 10.

[0055] The following is a more detailed explanation of the photoreceptor. Also, when there is no need to specifically distinguish between bonding resin (SL), bonding resin (CG), and bonding resin (CT), it will be referred to simply as "bonding resin". Similarly, when there is no need to specifically distinguish between hole transporter (SL), hole transporter (CG), and hole transporter (CT), it will be referred to simply as "hole transporter".

[0056] (Adhesive resin)

[0057] The first photosensitive layer contains a binder resin (specifically, binder resins (SL) and (CG)) containing a polyarylate resin. The polyarylate resin has repeating units as shown in formulas (1), (2), (3), and (4). The third content of the polyarylate resin is greater than 0% and less than 50%. The third content is the content of the repeating unit shown in formula (3) relative to the total number of repeating units shown in formulas (1) and (3). The fourth content of the polyarylate resin is more than 35% and less than 70%. The fourth content is the content of the repeating unit shown in formula (4) relative to the total number of repeating units shown in formulas (2) and (4).

[0058]

[0059] In equation (1), R 1 and R 2 X represents a methyl group, and X is a divalent group represented by formula (X1). Alternatively, R 1 and R 2 X represents a hydrogen atom, and X is a divalent group as shown in formula (X2).

[0060]

[0061] In formulas (X1) and (X2), * represents a bonding bond. The bonding bond represented by * in formulas (X1) and (X2) is bonded to the carbon atom bonded to X in formula (1).

[0062] Hereinafter, “the repeating units shown in formulas (1), (2), (3) and (4)” are sometimes referred to as “repeating units (1), (2), (3) and (4)” respectively. Also, “a polyarylate resin having repeating units (1), (2), (3) and (4), a third content of greater than 0% and less than 50%, and a fourth content of more than 35% and less than 70%” is sometimes referred to as “polyarylate resin (PA)”.

[0063] As described above, the binder resin (SL) and (CG) contained in the first photosensitive layer necessarily each contain polyarylate resin (PA). Furthermore, the binder resin (CT) contained in the charge transport layer is not particularly limited and may contain polyarylate resin (PA) or other binder resins described later. Also, the binder resin (CG) and the binder resin (CT) may be the same or different from each other.

[0064] Photosensitive layers containing polyaryl ester resin (PA), especially the first photosensitive layer, are less prone to fine scratches. Therefore, toner penetration into these fine scratches is suppressed, improving the photoreceptor's resistance to haze. Furthermore, polyaryl ester resin (PA) exhibits excellent solubility in solvents, thus enabling the formation of photosensitive layers (especially the first photosensitive layer) effectively.

[0065] In equation (1), in R1 and R 2 When X represents a methyl group and is a divalent group as shown in formula (X1), the repeating unit (1) is the repeating unit shown in formula (1-1) (hereinafter, sometimes referred to as repeating unit (1-1)). In formula (1), R 1 and R 2 When X represents a hydrogen atom and is a divalent group as shown in formula (X2), the repeating unit (1) is the repeating unit shown in formula (1-2) (hereinafter, sometimes referred to as repeating unit (1-2)). In polyarylate resin (PA), the repeating unit (1) may have only one repeating unit (1) or two repeating units (1).

[0066]

[0067] The percentage of repeating unit (1) relative to the total number of repeating units (1) and (3) is recorded as the first percentage. The first percentage is equivalent to the percentage of the number of repeating units (1) M1 relative to the total number of repeating units (1) M1 and repeating units (3) M3 in the polyaryl ester resin (PA) (i.e., 100×M1 / (M1+M3)). In addition, when the polyaryl ester resin (PA) has two types of repeating units (1), the number of repeating units (1) M1 is the sum of the two types of repeating units (1).

[0068] The first content rate is preferably less than 100%, more preferably 99% or less, further preferably 90% or less, even more preferably 80% or less, still more preferably 70% or less, even more preferably less than 70%, and particularly preferably 65% ​​or less. Furthermore, the first content rate is preferably greater than 50%, more preferably 51% or more, and even more preferably 55% or more. To improve the photoreceptor's resistance to fogging, the first content rate is preferably greater than 50% and less than 70%, more preferably greater than 50% and less than 70%.

[0069] The percentage of repeating unit (2) relative to the total number of repeating units (2) and (4) is recorded as the second percentage. The second percentage is equivalent to the percentage of the number of repeating units (2) M2 relative to the total number of repeating units (2) M2 and repeating units (4) M4 in the polyarylate resin (PA) (i.e., 100×M2 / (M2+M4)).

[0070] The second content is preferably 65% ​​or less, more preferably 60% or less. Furthermore, the second content is preferably greater than 30%, more preferably 31% or more, further preferably 35% or more, even more preferably 40% or more, and particularly preferably 55% or more. To improve the photoreceptor's resistance to fogging, the second content is preferably greater than 30% and less than 60%. To improve the abrasion resistance of the photoreceptor when the photosensitive layer contains polyarylate resin (PA), the second content is preferably 55% or more and less than 65%.

[0071] As stated above, the third content rate is greater than 0% and less than 50%. The third content rate is equivalent to: the percentage of the number of repeating units (3) M3 relative to the total number of repeating units (1) M1 and repeating units (3) M3 of the polyarylate resin (PA) (i.e., 100×M3 / (M1+M3)).

[0072] By ensuring the third content is less than 50%, the solubility of polyaryl ester resin (PA) in the solvent is improved, enabling the formation of a photosensitive layer. By ensuring the third content is greater than 0%, i.e., not 0%, the abrasion resistance of the photoreceptor when the photosensitive layer contains polyaryl ester resin (PA) is improved. The third content is preferably 1% or more, more preferably 10% or more, further preferably 20% or more, even more preferably 30% or more, still more preferably greater than 30%, and particularly preferably 35% or more. Furthermore, the third content is preferably 49% or less, more preferably 45% or less.

[0073] To improve the photoreceptor's resistance to fogging, the third content is preferably 30% or more and less than 50%, more preferably greater than 30% and less than 50%.

[0074] As stated above, the fourth content is 35% or more and less than 70%. The fourth content is equivalent to: the percentage of the number of repeating units (4) M4 relative to the total number of repeating units (2) M2 and repeating units (4) M4 of the polyarylate resin (PA) (i.e., 100×M4 / (M2+M4)).

[0075] By ensuring the fourth component content is 35% or higher, the photoreceptor's resistance to fogging is improved. Furthermore, by ensuring the fourth component content is 35% or higher, the solubility of the polyaryl ester resin (PA) relative to the solvent is improved, enabling the formation of a photosensitive layer effectively. On the other hand, by ensuring the fourth component content is less than 70%, the photoreceptor's abrasion resistance and resistance to fogging are improved. The fourth component content is preferably 40% or higher. Furthermore, the fourth component content is preferably 69% or lower, more preferably 65% ​​or lower, even more preferably 60% or lower, and even more preferably 45% or lower.

[0076] To improve the photoreceptor's resistance to fogging, the fourth content is preferably 40% or more and less than 70%. To improve the photoreceptor's abrasion resistance when the photosensitive layer contains polyarylate resin (PA), the fourth content is preferably 35% or more and less than 45%.

[0077] Measurement of polyarylate resin (PA) using proton nuclear magnetic resonance spectroscopy 1 H-NMR spectrum, based on the obtained 1 The characteristic peak ratios of each repeating unit in the H-NMR spectrum can be used to calculate the first, second, third, and fourth content rates, respectively.

[0078] To improve solubility in the solvent and the photoreceptor's resistance to fogging and abrasion, it is preferable that the first content rate is a value different from both the second and fourth content rates. For the same reason, it is preferable that the third content rate is a value different from both the second and fourth content rates.

[0079] To further improve the anti-fogging properties of the photoreceptor, it is preferable that: in formula (1), R 1 and R 2 X represents a methyl group, and X is a divalent group represented by formula (X1), with the fourth group having a content of 40% or more and less than 70%.

[0080] To improve the photoreceptor's resistance to fogging and abrasion in a balanced way, the preferred formulation is: In formula (1), R... 1 and R 2 X represents a methyl group, and X is a divalent group represented by formula (X1), with the third group having a content of 30% or more and less than 50%.

[0081] To further improve the abrasion resistance of the photoreceptor, it is preferable that: in formula (1), R 1 and R 2 It represents a hydrogen atom, and X is a divalent group as shown in formula (X2), and the fourth content is more than 35% and less than 45%.

[0082] In order to improve the photosensitivity and abrasion resistance of the photoreceptor without compromising its photosensitivity properties, the polyaryl ester resin (PA) is preferably free of repeating units having a biphenyl structure. Examples of repeating units having a biphenyl structure (construction) include the repeating unit shown in formula (5). Examples of repeating units shown in formula (5) include the repeating units shown in formulas (5-1) and (5-2).

[0083]

[0084] To further improve the abrasion resistance of the photoreceptor when the photosensitive layer contains polyarylate resin (PA), the polyarylate resin (PA) is preferably free of repeating units from isophthalic acid.

[0085] Polyaryl ester resins (PA) may also have terminal groups. Examples of terminal groups in polyaryl ester resins (PA) include those shown in formulas (T-1) and (T-2). The terminal group shown in formula (T-1) is preferably the terminal group shown in formula (T-DMP) (hereinafter sometimes referred to as terminal group (T-DMP)). The terminal group shown in formula (T-2) is preferably the terminal group shown in formula (T-PFH) (hereinafter sometimes referred to as terminal group (T-PFH)).

[0086]

[0087] In equation (T-1), R 11 Represents C1-C6 alkyl or halogen atoms, where p represents an integer between 0 and 5. R 11 Preferably, it represents a C1-C6 alkyl group, more preferably a C1-C3 alkyl group, and even more preferably a methyl group. p is preferably an integer of 1 to 3, more preferably 2.

[0088] In equation (T-2), R 12 R indicates a C1-C6 alkylidene group, and Rf indicates a C1-C10 perfluoroalkyl group. 12 Preferably, it represents a C1-C3 alkylidene group, more preferably a methylene group. Rf preferably represents a C3-C10 perfluoroalkyl group, more preferably a C5-C7 perfluoroalkyl group, and even more preferably a C6 perfluoroalkyl group.

[0089] The asterisk (*) in formulas (T-1), (T-2), (T-DMP), and (T-PFH) indicates a bonding bond. The bonding bond indicated by the asterisk (*) in formulas (T-1), (T-2), (T-DMP), and (T-PFH) is bonded to a repeating unit (more specifically, repeating unit (2) or (4)) located at the end of the polyaryl ester resin (PA) and derived from a dicarboxylic acid.

[0090] To further improve the photoreceptor's resistance to fogging and abrasion, it is preferable that the polyaryl ester resin (PA) contains terminal groups with halogen atoms. For the same reason, it is more preferable that, in formula (1), R 1 and R 2 The methyl group represents the polyarylate resin (PA), and X is a divalent group as shown in formula (X1). PA contains a terminal group with a halogen atom.

[0091] An example of a terminal group with a halogen atom is R in equation (T-1). 11 The terminal group (T-1) represents a halogen atom. Another example of a terminal group with a halogen atom is the terminal group (T-2).

[0092] Preferred examples of polyaryl ester resins (PA) include polyaryl ester resins (PA-1) to (PA-2) in Table 1. Each of polyaryl ester resins (PA-1) to (PA-2) has repeating units (1) to (4) as repeating units in Table 1. Further preferred examples of polyaryl ester resins (PA) include polyaryl ester resins (PA-a) to (PA-d) in Table 2. Each of polyaryl ester resins (PA-a) to (PA-d) has repeating units (1) to (4) as repeating units in Table 2, as well as terminal groups in Table 2. In Tables 1 and 2, "units (1) to (4)" respectively represent "repeating units (1) to (4)".

[0093] Table 1

[0094] Polyaryl resin Unit (1) Unit (2) Unit (3) Unit (4) PA-1 1-1 2 3 4 PA-2 1-2 2 3 4

[0095] Table 2

[0096] Polyaryl resin Unit (1) Unit (2) Unit (3) Unit (4) terminal group PA-a 1-1 2 3 4 T-DMP PA-b 1-2 2 3 4 T-DMP PA-c 1-1 2 3 4 T-PFH PA-d 1-2 2 3 4 T-PFH

[0097] In polyaryl ester resins (PA), repeating units from bisphenol (more specifically, repeating unit (1) or (3)) are adjacent to and bonded to repeating units from dicarboxylic acids (more specifically, repeating unit (2) or (4)). That is, repeating unit (1) can be bonded to repeating unit (2) or repeating unit (4). Also, repeating unit (3) can be bonded to repeating unit (2) or repeating unit (4). The repeating units from bisphenol and repeating units from dicarboxylic acids have substantially the same number, satisfying the formula "number of repeating units from dicarboxylic acids = number of repeating units from bisphenol + 1". Polyaryl ester resins (PA) can be, for example, random copolymers, alternating copolymers, periodic copolymers, or block copolymers.

[0098] The repeating units in the polyaryl ester resin (PA) may further include repeating units other than repeating units (1) to (4). However, in order to improve solubility in solvents and to improve the anti-fogging and abrasion resistance of the photoreceptor, the content of repeating units (1) to (4) is preferably 80% or more, more preferably 90% or more, further preferably 95% or more, even more preferably 99% or more, and particularly preferably 100% relative to the total number of repeating units in the polyaryl ester resin (PA). That is, it is particularly preferred that the repeating units in the polyaryl ester resin (PA) are only repeating units (1) to (4).

[0099] The content of repeating unit (1) is preferably greater than 50% and less than 100% relative to the total number of repeating units derived from bisphenol in the polyaryl ester resin (PA), more preferably 55% to 90%, further preferably 60% to 80%, even more preferably 60% to 70%, and still more preferably 60% to less than 70%. The content of repeating unit (3) is preferably greater than 0% and less than 50% relative to the total number of repeating units derived from bisphenol in the polyaryl ester resin (PA), more preferably 10% to 45%, further preferably 20% to 40%, even more preferably 30% to 40%, and still more preferably more than 30% and less than 40%.

[0100] The content of repeating unit (2) is preferably more than 30% and less than 65% relative to the total number of repeating units derived from dicarboxylic acids in the polyaryl ester resin (PA), more preferably more than 35% and less than 65%, and even more preferably more than 40% and less than 60%. The content of repeating unit (4) is preferably more than 35% and less than 70% relative to the total number of repeating units derived from dicarboxylic acids in the polyaryl ester resin (PA), more preferably more than 35% and less than 65%, and even more preferably more than 40% and less than 60%.

[0101] The viscosity-average molecular weight of the polyaryl ester resin (PA) is preferably 10,000 or more, more preferably 30,000 or more, even more preferably 35,000 or more, even more preferably 50,000 or more, and particularly preferably 55,000 or more. When the viscosity-average molecular weight of the polyaryl ester resin (PA) is 10,000 or more, the abrasion resistance of the photoreceptor is improved when the photosensitive layer of the photoreceptor contains the polyaryl ester resin (PA). When the viscosity-average molecular weight of the polyaryl ester resin (PA) is 35,000 or more, the fracture strain reaches a desired value or more, and the abrasion resistance of the photoreceptor is improved. Furthermore, when the viscosity-average molecular weight of the polyaryl ester resin (PA) is 35,000 or more, the anti-fogging property of the photoreceptor is further improved. On the other hand, the viscosity-average molecular weight of the polyaryl ester resin (PA) is preferably 80,000 or less, more preferably 70,000 or less, and even more preferably 60,000 or less. When the viscosity-average molecular weight of polyaryl ester resin (PA) is below 80,000, the anti-fogging properties of the photoreceptor are further improved. Furthermore, the solubility of polyaryl ester resin (PA) relative to solvents is also improved. The viscosity-average molecular weight of polyaryl ester resin (PA) was measured according to JIS (Japanese Industrial Standard) K7252-1:2016.

[0102] The mass ratio of the binder resin to the first photosensitive layer is preferably 0.35 to 0.50. When the mass ratio of the binder resin to the first photosensitive layer is 0.35 to 0.50, the anti-fogging properties of the photoreceptor are further improved. Furthermore, when the mass ratio of the binder resin to the first photosensitive layer is 0.50 or less, the content of electron transporter and hole transporter in the first photosensitive layer is relatively higher, and the photosensitivity characteristics of the photoreceptor are improved. When the photoreceptor is a single-layer type, the mass ratio of the binder resin to the first photosensitive layer refers to the mass ratio of the binder resin (SL) to the mass of the single-layer type photosensitive layer that serves as the first photosensitive layer. When the photoreceptor is a positively charged multilayer type photoreceptor, the mass ratio of the binder resin to the first photosensitive layer refers to the mass ratio of the binder resin (CG) to the mass of the charge-generating layer that serves as the first photosensitive layer. When the bonding resin (SL) contains polyaryl ester resin (PA) and other bonding resins described later, the mass of the bonding resin (SL) is the total mass of the polyaryl ester resin (PA) and the other bonding resins. When the bonding resin (CG) contains polyaryl ester resin (PA) and other bonding resins described later, the mass of the bonding resin (CG) is the total mass of the polyaryl ester resin (PA) and the other bonding resins. When the bonding resin (SL) contains two or more resins, the mass of the bonding resin (SL) is the total mass of the two or more resins. When the bonding resin (CG) contains two or more resins, the mass of the bonding resin (CG) is the total mass of the two or more resins.

[0103] Next, a method for manufacturing polyaryl ester resin (PA) will be described. One method for manufacturing polyaryl ester resin (PA) is, for example, the polycondensation of bisphenol (used to form repeating units from bisphenol) and dicarboxylic acid (used to form repeating units from dicarboxylic acid). Polycondensation can be performed using well-known synthetic methods (e.g., solution polymerization, melt polymerization, or interfacial polymerization).

[0104] Bisphenols (used to form repeating units from bisphenols) include, for example, compounds of formulas (BP-1) and (BP-3) (hereinafter sometimes referred to as compounds (BP-1) and (BP-3) respectively). Dicarboxylic acids (used to form repeating units from dicarboxylic acids) include, for example, compounds of formulas (DC-2) and (DC-4) (hereinafter sometimes referred to as compounds (DC-2) and (DC-4) respectively). R in formula (BP-1) 1 R 2 And X and R in equation (1) 1 R 2 It has the same meaning as X.

[0105]

[0106] In the manufacture of polyaryl ester resin (PA), the amount of compound (BP-1) added (in moles) is changed relative to the total amount (in moles) of compounds (BP-1) and (BP-3), thereby adjusting the first content rate. The first content rate is equivalent to the mole fraction (in mol%) of repeating unit (1) in the total amount of repeating units (1) and (3) in the polyaryl ester resin (PA). Furthermore, the amount of compound (DC-2) added (in moles) is changed relative to the total amount (in moles) of compounds (DC-2) and (DC-4), thereby adjusting the second content rate. The second content rate is equivalent to the mole fraction (in mol%) of repeating unit (2) in the total amount of repeating units (2) and (4) in the polyaryl ester resin (PA). The amount of compound (BP-3) added (in moles) is changed relative to the total amount (in moles) of compounds (BP-1) and (BP-3), thereby adjusting the third content rate. The third content rate is equivalent to the mole fraction (mol%) of repeating unit (3) in the total amount of repeating units (1) and (3) of the polyaryl ester resin (PA). The fourth content rate is adjusted by changing the amount of compound (DC-4) added (moles) relative to the total amount of compounds (DC-2) and (DC-4). The fourth content rate is equivalent to the mole fraction (mol%) of repeating unit (4) in the total amount of repeating units (2) and (4) of the polyaryl ester resin (PA).

[0107] Bisphenols can also be derived from aromatic diacetates. Dicarboxylic acids can also be derived from other compounds. Examples of dicarboxylic acid derivatives include dicarboxylic acid dichloride, dimethyl dicarboxylic acid, diethyl dicarboxylic acid, and dicarboxylic acid anhydrides. Dicarboxylic acid dichloride is a compound in which both "-C(=O)-OH" groups of a dicarboxylic acid are replaced by "-C(=O)-Cl" groups.

[0108] In the polycondensation of bisphenol and dicarboxylic acid, a terminator can also be added. Examples of terminators include 2,6-dimethylphenol and 1H,1H-perfluoro-1-heptanol. Using 2,6-dimethylphenol as a terminator forms a terminal group (T-DMP). Using 1H,1H-perfluoro-1-heptanol as a terminator forms a terminal group (T-PFH).

[0109] In the polycondensation of bisphenols and dicarboxylic acids, one or both of a base and a catalyst may be added. Examples of bases include sodium hydroxide. Examples of catalysts include benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salts, triethylamine, and trimethylamine.

[0110] In the photosensitive layer (more specifically, each of the single-layer photosensitive layer, charge generating layer, and charge transport layer), the binder resin may contain only one type of polyaryl ester resin (PA), or it may contain two or more types of polyaryl ester resin (PA). Furthermore, in the photosensitive layer (more specifically, each of the single-layer photosensitive layer, charge generating layer, and charge transport layer), the binder resin may contain only polyaryl ester resin (PA), or it may further contain binder resins other than polyaryl ester resin (PA) (hereinafter, sometimes referred to as other binder resins).

[0111] Other bonding resins include, for example, thermoplastic resins (more specifically, polyarylene resins other than polyarylene resins (PA), polycarbonate resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic acid copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-vinyl acetate copolymers, polyester resins, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyvinyl acetal resins, and polyether resins), thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea-formaldehyde resins, melamine resins, and other crosslinked thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic resins and polyurethane-acrylic copolymers).

[0112] (Electron delivery agent)

[0113] The electron transport agent contains compounds represented by formulas (11), (12), (13), (14), (15), (16), or (17) (hereinafter, sometimes referred to as electron transport agents (11), (12), (13), (14), (15), (16), and (17)). By adding electron transport agents (11) to (17) to the first photosensitive layer on top of polyarylate resin (PA), the anti-fogging property is improved.

[0114]

[0115] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23 and Q 24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q 42 and Q 43 Q in equation (15)51 Q 52 Q 53 and Q 54 Q in equation (16) 61 and Q 62 and Q in equation (17) 71 Q 72 Q 73 Q 74 Q 75 and Q 76 Each is independent and represents a hydrogen atom, a halogen atom, a cyano group, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C1-C6 alkoxy group, an unsubstituted C6-C14 aryl group, or a C6-C14 aryl group substituted with at least one substituent selected from the group consisting of C1-C6 alkyl and halogen atoms. Y in formula (17) 1 and Y 2 Each can be used independently to represent either an oxygen atom or a sulfur atom.

[0116] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23 and Q 24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q 42 and Q 43 Q in equation (15) 51 Q 52 Q 53 and Q 54 Q in equation (16) 61 and Q 62 and Q in equation (17) 71 Q 72 Q 73 Q 74 Q 75 and Q 76 Each is independent, preferably representing a hydrogen atom, a C1-C6 alkyl group, an unsubstituted C6-C14 aryl group, or a C6-C14 aryl group substituted with at least one substituent selected from the group consisting of C1-C6 alkyl groups and halogen atoms. 1 and Y 2 Preferably, it represents an oxygen atom.

[0117] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23 and Q24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q 42 and Q 43 Q in equation (15) 51 Q 52 Q 53 and Q 54 Q in equation (16) 61 and Q 62 and Q in equation (17) 71 Q 72 Q 73 Q 74 Q 75 and Q 76 When C1-C6 alkyl is used, C1-C5 alkyl is preferred, and methyl, ethyl, propyl, butyl or pentyl are preferred, with methyl, isopropyl, tert-butyl or 1,1-dimethylpropyl being particularly preferred.

[0118] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23 and Q 24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q 42 and Q 43 Q in equation (15) 51 Q 52 Q 53 and Q 54 Q in equation (16) 61 and Q 62 and Q in equation (17) 71 Q 72 Q 73 Q 74 Q 75 and Q 76When representing a C6-C14 aryl group, a C6-C10 aryl group is preferred, and a phenyl group is more preferred. The C6-C14 aryl group can be: an unsubstituted C6-C14 aryl group or a C6-C14 aryl group substituted with at least one substituent selected from the group consisting of C1-C6 alkyl groups and halogen atoms. The C1-C6 alkyl group as a substituent is preferably a C1-C3 alkyl group, and more preferably methyl or ethyl. The halogen atom as a substituent is preferably a fluorine atom, a chlorine atom, or a bromine atom, and particularly preferably a chlorine atom. When the C6-C14 aryl group has substituents, the number of substituents is preferably one to five, more preferably one or two. The C6-C14 aryl group substituted with at least one substituent selected from the group consisting of C1-C6 alkyl groups and halogen atoms is preferably chlorophenyl, dichlorophenyl, or ethylmethylphenyl, more preferably 4-chlorophenyl, 2,5-dichlorophenyl, or 2-ethyl-6-methylphenyl.

[0119] Further preferred examples of electron transport agents include compounds represented by formulas (E-1) to (E-9) (hereinafter, they are sometimes referred to as electron transport agents (E-1) to (E-9)).

[0120]

[0121] The content of the electron transport agent is preferably 5 parts by mass or less and 150 parts by mass or less, more preferably 10 parts by mass or less and 100 parts by mass or less, and even more preferably 30 parts by mass or less and 70 parts by mass or less, relative to 100 parts by mass of the adhesive resin (SL) (or, relative to 100 parts by mass of the adhesive resin (CG)). Furthermore, the first photosensitive layer may contain only one type of electron transport agent or may contain two or more types of electron transport agents.

[0122] (Cavitation delivery agent)

[0123] Hole delivery agents can be exemplified by: triphenylamine derivatives, diamine derivatives (e.g., N,N,N',N'-tetraphenylbenzidine derivatives, N,N,N',N'-tetraphenylphenyldiamine derivatives, N,N,N',N'-tetraphenylnaphthalenediamine derivatives, N,N,N',N'-tetraphenylphenanthrylenediamine), etc. (diamine) derivatives and bis(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), organopolysilane 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. The monolayer photosensitive layer, charge generation layer, and charge transport layer may each contain only one type of hole transporter, or they may contain two or more types of hole transporters. Furthermore, the hole transporter (CG) contained in the charge generation layer and the hole transporter (CT) contained in the charge transport layer may be the same as or different from each other.

[0124] Preferred examples of hole delivery agents include compounds represented by formulas (20), (21), (22), (23), (24), and (25) (hereinafter sometimes referred to as hole delivery agents (20), (21), (22), (23), (24), and (25)). By containing polyarylate resin (PA) and hole delivery agents (20), (21), (22), (23), (24), or (25) in the photosensitive layer, the photosensitive layer can be formed better, and the anti-fogging properties of the photosensitive material are further improved. The photosensitive layer is more preferably containing hole delivery agents (20), (21), (22), (23), or (24). The compatibility of hole delivery agents (20), (21), (22), (23), or (24) with polyarylate resin (PA) is particularly excellent, so in addition to the improved anti-fogging properties, the abrasion resistance and photosensitivity properties of the photosensitive material are also improved.

[0125]

[0126]

[0127]

[0128] In equation (20), R 16 R 17 R 18 and R 19Each is independent and represents a C1-C6 alkyl group. a6, a7, a8, and a9 are independent and represent integers above 0 and below 5.

[0129] In equation (20), a6 represents a number of R integers greater than 2 and less than 5. 16 They are the same or different. When a7 represents an integer greater than 2 and less than 5, several R... 17 They are the same or different. When a8 represents an integer greater than 2 and less than 5, several R... 18 They are the same or different. When a9 represents an integer greater than 2 and less than 5, several R... 19 They are the same or different from each other.

[0130] In equation (20), R 16 R 17 R 18 and R 19 Each a6, a7, a8, and a9 are independent and preferably represent C1-C3 alkyl groups, more preferably methyl or ethyl. Each a6, a7, a8, and a9 are independent and preferably represent an integer of 1 to 3, more preferably 1.

[0131] In equation (21), R 21 R 22 and R 23 Each is independent and represents a C1-C6 alkyl group. R 24 R 25 and R 26 Each of the following is independent and represents a hydrogen atom, a C1-C6 alkyl group, or a C6-C14 aryl group. b1, b2, and b3 are independent and represent 0 or 1. b4, b5, and b6 are independent and represent integers above 0 and below 5.

[0132] In equation (21), R 21 R 22 and R 23 Each is independent, preferably representing a C1-C3 alkyl group, more preferably representing a methyl group. R 21 R 22 and R 23 Preferably, it is at the meta position relative to the vinyl or butadiene group bonded to the phenyl group. 24 R 25 and R 26 Each of them is preferably a hydrogen atom. b1, b2 and b3 are preferably all 0 or all 1. b4, b5 and b6 are preferably all 1.

[0133] In equation (22), R 31 R 32 and R 33 Each is independent and represents a C1-C6 alkyl group. R 34Represents C1-C6 alkyl groups or hydrogen atoms. d1, d2, and d3 are independent and represent integers above 0 and below 5.

[0134] In equation (22), d1 represents a number of R integers greater than 2 and less than 5. 31 They are either the same or different. When d2 represents an integer greater than 2 and less than 5, several R... 32 They are either the same or different. When d3 represents an integer greater than 2 and less than 5, several R... 33 They are the same or different from each other.

[0135] In equation (22), R 34 Preferably, d1, d2, and d3 represent hydrogen atoms. d1, d2, and d3 are each preferably 0.

[0136] In equation (23), R 50 and R 51 Each can be independent and represent a C1-C6 alkyl, C1-C6 alkoxy, or phenyl group. R 52 R 53 R 54 R 55 R 56 R 57 and R 58 Each is independent and represents a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group, an unsubstituted phenyl group, or a phenyl group with a C1-C6 alkyl substituent. f1 and f2 are independent and represent integers from 0 to 2. f3 and f4 are independent and represent integers from 0 to 5.

[0137] In equation (23), f3 represents a number of R integers greater than 2 and less than 5. 50 They are either the same or different. When f4 represents an integer greater than 2 and less than 5, several R... 51 They are the same or different from each other.

[0138] In equation (23), R 50 and R 51 Each is independent, preferably representing a C1-C6 alkyl group. R 52 and R 53 Each is preferably a phenyl group representing a hydrogen atom, an unsubstituted phenyl group, or a phenyl group having C1-C6 alkyl substituents. 54 ~R 58 Each is independent and preferably represents a hydrogen atom, a C1-C6 alkyl group, or a C1-C6 alkoxy group. f1 and f2 are preferably both 0, both 1, or both 2. f3 and f4 are independent and preferably represent 0 or 1.

[0139] In equation (23), R 50 and R 51When representing C1-C6 alkyl, C1-C3 alkyl is preferred, and methyl is more preferred. 52 and R 53 When referring to an unsubstituted phenyl or a phenyl having C1-C6 alkyl substituents, it is preferably an unsubstituted phenyl or a phenyl having C1-C3 alkyl substituents. A phenyl having C1-C3 alkyl substituents is preferably methylphenyl, more preferably 4-methylphenyl. 54 ~R 58 When representing C1-C6 alkyl, C1-C4 alkyl is preferred, and more preferably methyl, ethyl, or n-butyl. 54 ~R 58 When C1-C6 alkoxy is used, C1-C3 alkoxy is preferred, and ethoxy is more preferred.

[0140] In equation (24), R 61 R 62 R 63 R 64 R 65 and R 66 Each can be independent and represents a C1-C8 alkyl or phenyl group. R 67 and R 68 Each of the following is independent and represents a hydrogen atom, a C1-C8 alkyl group, or a phenyl group. e1, e2, e3, and e4 are independent and represent integers greater than 0 and less than 5. e5 and e6 are independent and represent integers greater than 0 and less than 4. e7 and e8 are independent and represent either 0 or 1.

[0141] In equation (24), e1 represents a number of R integers greater than 2 and less than 5. 61 They can have the same base or different bases. When e2 represents integers greater than 2 and less than 5, several R... 62 They can have the same base or different bases. When e3 represents integers greater than 2 and less than 5, several R... 63 They can have the same base or different bases. When e4 represents integers greater than 2 and less than 5, several R... 64 They can be based on the same base or different bases. When e5 represents integers greater than 2 and less than 4, several R... 65 They can share the same base or have different bases. When e6 represents integers greater than 2 and less than 4, several R... 66 They can be the same base or different bases.

[0142] In equation (24), R 61 ~R 66 Each is independent, preferably representing a C1-C8 alkyl group, more preferably a C1-C3 alkyl group, and even more preferably a methyl or ethyl group. R 67 and R68 Preferably, they represent hydrogen atoms. e1, e2, e3, and e4 are independent and preferably represent integers greater than 0 and less than 2. e5 and e6 preferably represent 0.

[0143] In equation (25), R 41 R 42 R 43 R 44 R 45 and R 46 Each of the following is independent and represents a C1-C8 alkyl, phenyl, or C1-C8 alkoxy group. g1, g2, g4, and g5 are independent and represent integers greater than or equal to 0 and less than or equal to 5. g3 and g6 are independent and represent integers greater than or equal to 0 and less than or equal to 4.

[0144] In equation (25), g1 represents a number of R integers greater than 2 and less than 5. 41 They can be from the same basis or different bases. When g2 represents integers greater than 2 and less than 5, several R... 42 They can be from the same base or different bases. When g4 represents integers greater than 2 and less than 5, several R... 44 They can have the same base or different bases. When g5 represents integers greater than 2 and less than 5, several R... 45 They can have the same basis or different bases. When g3 represents integers greater than 2 and less than 4, several R... 43 They can share the same basis or have different bases. When g6 represents integers greater than 2 and less than 4, several R... 46 They can be the same base or different bases.

[0145] In equation (25), R 41 ~R 46 Each is independent, preferably representing a C1-C8 alkyl group, more preferably a C1-C3 alkyl group, and even more preferably a methyl or ethyl group. g1, g2, g4, and g5 are each independent, preferably representing an integer from 0 to 2. g3 and g6 preferably represent 0. Having R 44 R 45 and R 46 The diphenylaminostyrene group is preferably relative to the group having R 41 R 42 and R 43 The diphenylaminostyrene group is bonded to the para position of the phenyl group.

[0146] Further preferred examples of hole delivery agents include compounds represented by formulas (H-1) to (H-11) (hereinafter, sometimes referred to as hole delivery agents (H-1) to (H-11)).

[0147]

[0148]

[0149]

[0150] The content of cavitation delivery agent (SL) relative to 100 parts by mass of binder resin (SL), the content of cavitation delivery agent (CG) relative to 100 parts by mass of binder resin (CG), and the content of cavitation delivery agent (CT) relative to 100 parts by mass of binder resin (CT) are preferably 10 parts by mass or more and 200 parts by mass, more preferably 50 parts by mass or more and 150 parts by mass, and even more preferably 70 parts by mass or more and 130 parts by mass or less.

[0151] (charge generator)

[0152] Examples of charge-generating agents include: phthalocyanine pigments, perylene pigments, diazo pigments, triazo pigments, dithioketo-pyrrolopyrrole pigments, metal-free naphthalene phthalocyanine pigments, metal naphthalene phthalocyanine pigments, squaric acid pigments, indigo pigments, chamomile blue pigments, cyanine pigments, inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon) powders, pyran pigments, anthraquinone pigments, triphenylmethane pigments, vat pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments. The single-layer photosensitive layer and the charge-generating layer may each contain only one type of charge-generating agent, or they may contain two or more types of charge-generating agents.

[0153] Phthalocyanine pigments are pigments that have a phthalocyanine structure. Examples of phthalocyanine pigments include metal-free phthalocyanines and metallic phthalocyanines. Examples of metallic phthalocyanines include titanium dioxide phthalocyanine, hydroxy gallium phthalocyanine, and gallium chloride phthalocyanine.

[0154] Metal-free phthalocyanines are represented by formula (CGM-1). Titanium phthalocyanines are represented by formula (CGM-2).

[0155]

[0156]

[0157] Phthalocyanine pigments can be crystalline or amorphous. Crystalline metal-free phthalocyanines include, for example, type X crystals of metal-free phthalocyanines (hereinafter sometimes referred to as type X metal-free phthalocyanine). Crystalline titanium phthalocyanines include, for example, type α, type β, and type Y crystals of titanium phthalocyanines (hereinafter sometimes referred to as type α, type β, and type Y titanium phthalocyanines, respectively).

[0158] For example, in digital optical image forming apparatuses (e.g., laser printers or fax machines using light sources such as semiconductor lasers), a photoreceptor with photosensitivity in the wavelength region of 700 nm and above is preferred. From the viewpoint of having high quantum yield in the wavelength region of 700 nm and above, the charge generating agent is preferably a phthalocyanine pigment, more preferably a metal-free phthalocyanine or titanium phthalocyanine, further preferably titanium phthalocyanine, and particularly preferably Y-type titanium phthalocyanine.

[0159] Y-type titanium phthalocyanine exhibits a dominant peak in the characteristic X-ray diffraction spectrum of CuKα, for example, at a Bragg angle of 27.2° (2θ ± 0.2°). A dominant peak in the characteristic X-ray diffraction spectrum of CuKα refers to the peak with the first or second largest intensity in the range of 3° to 40° within the Bragg angle (2θ ± 0.2°). In the characteristic X-ray diffraction spectrum of CuKα, Y-type titanium phthalocyanine shows no peak at 26.2℃.

[0160] The characteristic X-ray diffraction spectrum of CuKα can be measured, for example, by the following method. First, a sample (titanium phthalocyanine) is filled into the sample holder of an X-ray diffraction apparatus (RINT 1100 manufactured by Rigaku Corporation). The X-ray tube is Cu, the tube voltage is 40 kV, the tube current is 30 mA, and the characteristic X-ray wavelength of CuKα is... Under the given conditions, measure the X-ray diffraction spectrum. The measurement range (2θ) is, for example, 3° to 40° (starting angle 3°, stopping angle 40°), and the scanning speed is, for example, 10° / min. Determine the main peak based on the obtained X-ray diffraction spectrum and read the Bragg angle of the main peak.

[0161] The content of the charge generating agent relative to 100 parts by mass of the adhesive resin (SL) and the content of the charge generating agent relative to 100 parts by mass of the adhesive resin (CG) are preferably 0.1 parts by mass or more and 50 parts by mass or less, more preferably 0.5 parts by mass or more and 5 parts by mass or less.

[0162] (additive)

[0163] Additives may include, for example, ultraviolet absorbers, antioxidants, free radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, dispersants, waxes, donors, surfactants, plasticizers, sensitizers, electron acceptor compounds, and leveling agents.

[0164] (Scratch resistance depth)

[0165] The scratch resistance depth of the first photosensitive layer is preferably 0.50 μm or less. The scratch resistance depth of the first photosensitive layer is a value representing the hardness of the first photosensitive layer. A scratch resistance depth of 0.50 μm or less means that the first photosensitive layer has a hardness such that, by the scratch resistance depth measurement method described later, scratches with a scratch resistance depth of 0.50 μm or less are formed on the surface of the first photosensitive layer. When the scratch resistance depth of the first photosensitive layer is 0.50 μm or less, fine scratches are less likely to form on the surface of the photoreceptor. As a result, toner is less likely to penetrate into scratches formed on the surface of the photoreceptor, and haze is less likely to occur in the formed image. Furthermore, when the scratch resistance depth of the first photosensitive layer is 0.50 μm or less, the abrasion resistance of the photoreceptor is improved. To improve the resistance to fogging, the scratch resistance depth of the first photosensitive layer is preferably 0.00 μm or more and 0.50 μm or less, more preferably 0.05 μm or more and 0.40 μm or less, and even more preferably 0.10 μm or more and 0.30 μm or less.

[0166] The scratch resistance depth of the first photosensitive layer is measured using the following method. Using a scratching apparatus specified in JIS (Japanese Industrial Standard) K5600-5-5, the scratch resistance depth of the first photosensitive layer is measured in four steps. The scratching apparatus includes a stage and a scratching needle. The scratching needle has a hemispherical sapphire tip with a diameter of 1 mm. In the first step, the photoreceptor is fixed to the top surface of the stage, with the long side of the photoreceptor parallel to the long side of the stage. In the second step, the scratching needle is brought into perpendicular contact with the surface of the first photosensitive layer. In the third step, with the scratching needle in perpendicular contact with the surface of the first photosensitive layer, the scratching needle applies a 10g load to the first photosensitive layer, and the stage and the photoreceptor fixed to the top surface of the stage are moved 30 mm along the long side of the stage at a speed of 30 mm / min, creating a scratch on the surface of the first photosensitive layer using the scratching needle. In the fourth step, the maximum depth of the scratch is measured, i.e., the scratch resistance depth. As described above, an outline of the method for measuring scratch resistance depth has been given. The method for measuring scratch resistance depth is described in detail in the embodiments.

[0167] The scratch resistance depth of the first photosensitive layer can be adjusted, for example, by changing the type of adhesive resin. Furthermore, the scratch resistance depth of the first photosensitive layer can also be adjusted, for example, by changing the ratio of the mass of the adhesive resin to the mass of the first photosensitive layer.

[0168] (fracture strain)

[0169] The fracture strain of the first photosensitive layer is preferably 7.5% to 21.0%, more preferably 14.0% to 21.0%. When the fracture strain of the first photosensitive layer is 7.5% or more, the photoreceptor's resistance to fogging and abrasion is improved. When the fracture strain of the first photosensitive layer is 21.0% or less, the photoreceptor's resistance to fogging is improved. The fracture strain of the first photosensitive layer is a value obtained by using a tensile testing machine to stretch the first photosensitive layer at a tensile speed of 5 mm / min, as shown in the stress-strain curve. The fracture strain of the first photosensitive layer is measured, for example, by the method described in the later examples. The fracture strain can be adjusted, for example, by changing the type and viscosity-average molecular weight of the adhesive resin.

[0170] (Vickers hardness)

[0171] The Vickers hardness of the first photosensitive layer is preferably 19.0 HV or higher, more preferably 20.0 HV or higher. When the Vickers hardness of the first photosensitive layer is 19.0 HV or higher, the resistance to fogging of the photoreceptor is improved. There is no particular upper limit to the Vickers hardness of the first photosensitive layer, for example, it is 25.0 HV or lower. The Vickers hardness of the first photosensitive layer is measured according to the method of JIS (Japanese Industrial Standard) Z2244. The Vickers hardness of the first photosensitive layer can be adjusted, for example, by changing the type of binder resin and the type of hole delivery agent.

[0172] (Conductive substrate)

[0173] The conductive substrate need only have at least its surface portion formed of a conductive material, and there are no particular limitations. An example of a conductive substrate is one made of a conductive material. Another example is 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, indium, stainless steel, and brass. Among these conductive materials, aluminum or aluminum alloys are preferred, based on the viewpoint of good charge movement from the photosensitive layer to the conductive substrate.

[0174] The shape of the conductive substrate is appropriately selected based on the structure of the image forming apparatus. Examples of conductive substrate shapes include sheet-like and drum-like shapes. Furthermore, the thickness of the conductive substrate is appropriately selected based on its shape.

[0175] (Middle layer)

[0176] The intermediate layer (base layer) may contain inorganic particles and a resin used in the intermediate layer (resin for intermediate layer). It can be considered that the presence of the intermediate layer can maintain an insulating state that can suppress leakage, while allowing the current generated during exposure of the photosensitive material to flow smoothly, thereby suppressing the increase in resistance.

[0177] Inorganic particles include, for example, particles of metals (e.g., aluminum, iron, and copper), particles of metal oxides (e.g., titanium dioxide, aluminum oxide, zirconium oxide, tin oxide, and zinc oxide), and particles of non-metal oxides (e.g., silicon dioxide).

[0178] Examples of resins used in the intermediate layer are the same as those for the other adhesive resins described above. To ensure proper formation of both the intermediate layer and the photosensitive layer, the resin used in the intermediate layer is preferably different from the adhesive resin contained in the photosensitive layer. The intermediate layer may also contain additives. Examples of additives contained in the intermediate layer are the same as those contained in the photosensitive layer.

[0179] (Methods for manufacturing photoreceptors)

[0180] Regarding the manufacturing methods of photoreceptors, an example of a manufacturing method for a single-layer photoreceptor and an example of a manufacturing method for a positively charged multilayer photoreceptor will be described.

[0181] A method for manufacturing a single-layer photoreceptor includes, for example, a single-layer photoreceptor forming step. In the single-layer photoreceptor forming step, a coating solution for forming the single-layer photoreceptor (hereinafter, sometimes referred to as a coating solution for a single-layer photoreceptor) is prepared. The single-layer photoreceptor coating solution is coated onto a conductive substrate. Then, at least a portion of the solvent contained in the coated photoreceptor coating solution is removed, thereby forming a single-layer photoreceptor. The single-layer photoreceptor coating solution, for example, contains a charge generating agent, a binding resin (SL), an electron transport agent, a hole transport agent (SL), and a solvent. The single-layer photoreceptor coating solution is prepared by dissolving or dispersing the charge generating agent, the binding resin (SL), the electron transport agent, and the hole transport agent (SL) in a solvent. If necessary, the single-layer photoreceptor coating solution may further contain additives.

[0182] Methods for manufacturing positively charged laminated photoreceptors include, for example, a charge transport layer formation process and a charge generation layer formation process.

[0183] In the charge transport layer formation process, a charge transport layer coating solution is applied to a conductive substrate. Then, at least a portion of the solvent contained in the applied charge transport layer coating solution is removed, thereby forming the charge transport layer. The charge transport layer coating solution contains a hole transport agent (CT), a binder resin (CT), and a solvent. The charge transport layer coating solution can be prepared by dissolving or dispersing the hole transport agent (CT) and the binder resin (CT) in the solvent. If necessary, the charge transport layer coating solution may further contain additives.

[0184] In the charge generation layer formation process, a charge generation layer is coated onto a charge transport layer using a coating liquid. Then, at least a portion of the solvent contained in the coating liquid is removed, thereby forming the charge generation layer. The coating liquid for the charge generation layer, for example, contains a charge generating agent, a binding resin (CG), an electron transport agent, a hole transport agent (CG), and a solvent. The coating liquid for the charge generation layer is prepared by dissolving or dispersing the charge generating agent, the binding resin (CG), the electron transport agent, and the hole transport agent (CG) in a solvent. If necessary, the coating liquid for the charge generation layer may further contain additives.

[0185] The solvents contained in coating solutions for single-layer photosensitive layers, charge-generating layers, and charge-transporting layers (hereinafter, sometimes collectively referred to as coating solutions) are not particularly limited as long as they can dissolve or disperse the components contained in the coating solution. Examples of solvents 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, dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene), ethers (more specifically, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether), ketones (more specifically, acetone, methyl ethyl ketone, and cyclohexanone), esters (more specifically, ethyl acetate and methyl acetate), dimethylformaldehyde, dimethylformamide, and dimethyl sulfoxide.

[0186] The solvent contained in the coating solution for the charge transport layer is preferably different from the solvent contained in the coating solution for the charge generation layer. The reason for this is that, when coating the charge transport layer with the coating solution for the charge generation layer, it is preferable to use a solvent in which the charge transport layer does not dissolve in the coating solution for the charge generation layer.

[0187] The coating liquid is prepared by mixing and dispersing the various components in a solvent. For example, a bead mill, roller mill, ball mill, grinder, paint vibrator, or ultrasonic disperser can be used for mixing or dispersing.

[0188] Any method that can evenly coat the surface with a coating liquid is acceptable; there are no particular limitations. Examples of coating methods include dip coating, spray coating, spin coating, and rod coating.

[0189] Methods for removing at least a portion of the solvent contained in the coating solution include, for example, heating, depressurization, or a combination of heating and depressurization. More specifically, heat treatment (hot air drying) using a high-temperature dryer or a depressurization dryer can be cited. The temperature of the heat treatment is, for example, between 40°C and 150°C. The time of the heat treatment is, for example, between 3 minutes and 120 minutes.

[0190] Furthermore, the manufacturing method of the photoreceptor may, as needed, include one or both of an intermediate layer formation process and a protective layer formation process. Well-known methods can be appropriately selected for the intermediate layer formation process and the protective layer formation process.

[0191] <Second Embodiment: Image Forming Apparatus>

[0192] The image forming apparatus according to the second embodiment of the present invention will be described below. Hereinafter, reference will be made to... Figure 7 The following explanation will take a series-connected color image forming apparatus as an example. Figure 7 This is a cross-sectional view of an example of an image forming apparatus.

[0193] Figure 7 The image forming apparatus 100 includes image forming units 40a, 40b, 40c and 40d, a transfer belt 50 and a fixing device 54. Hereinafter, without distinction, image forming units 40a, 40b, 40c and 40d will all be referred to as image forming unit 40.

[0194] The image forming unit 40 includes an image carrier 30, a charging device 42, an exposure device 44, a developing device 46, and a transfer device 48. The image carrier 30 is a photoreceptor according to the first embodiment (specifically, a single-layer photoreceptor 1 and a positively charged laminated photoreceptor 10).

[0195] As described above, the photoreceptor of the first embodiment improves resistance to fogging. Therefore, by providing the photoreceptor of the first embodiment as the image carrier 30, the image forming apparatus 100 is able to form an image with less fogging on the recording medium P.

[0196] Image carrier 30 is positioned at the center of image forming unit 40. Image carrier 30 is configured to move along the direction of the arrow ( Figure 7 (rotation direction in counterclockwise direction). Around the image carrier 30, starting from the upstream side of the rotation direction of the image carrier 30, the charging device 42, the exposure device 44, the developing device 46, and the transfer device 48 are arranged in sequence.

[0197] Several colors of toner (e.g., black, cyan, magenta, and yellow) are sequentially superimposed by each of the image forming units 40a to 40d onto the recording medium P on the transfer belt 50.

[0198] The charging device 42 charges the surface (e.g., the peripheral surface) of the image carrier 30 to a positive polarity. In either the case where the image carrier 30 is a single-layer photoreceptor 1 or a positively charged multilayer photoreceptor 10, the surface of the image carrier 30 is charged to a positive polarity. The charging device 42 is, for example, a charged roller.

[0199] The exposure apparatus 44 irradiates the surface of the charged image carrier 30 with light for exposure. That is, the exposure apparatus 44 exposes the surface of the charged image carrier 30. As a result, an electrostatic latent image is formed on the surface of the image carrier 30. The electrostatic latent image is formed based on the image data input to the image forming apparatus 100.

[0200] The developing apparatus 46 supplies toner to the surface of the image carrier 30, developing the electrostatic latent image into a toner image. The developing apparatus 46 (e.g., the surface of the developing apparatus 46, more specifically, the peripheral surface of the developing apparatus 46) contacts the surface of the image carrier 30. That is, the image forming apparatus 100 employs a contact developing method. The developing apparatus 46 is, for example, a developing roller. When the developer is a single-component developer, the developing apparatus 46 supplies toner, which is a single-component developer, to the electrostatic latent image formed on the image carrier 30. When the developer is a two-component developer, the developing apparatus 46 supplies toner contained in the two-component developer and toner in the carrier to the electrostatic latent image formed on the image carrier 30. Thus, the image carrier 30 carries the toner image.

[0201] The transfer belt 50 transports the recording medium P between the image carrier 30 and the transfer section 48. The transfer belt 50 is a loop. The transfer belt 50 is configured to move along the direction of the arrow ( Figure 7 Rotate clockwise.

[0202] After the developing unit 46 develops the toner image, the transfer unit 48 transfers the toner image from the surface of the image carrier 30 onto the recording medium P. During the toner image transfer, the image carrier 30 is in contact with the recording medium P. That is, the image forming apparatus 100 employs a direct transfer method. The transfer device 48 is, for example, a transfer roller.

[0203] After the toner image is transferred from the transfer device 48 onto the recording medium P, the recording medium P is conveyed to the fixing device 54 by the transfer belt 50. The fixing device 54 is, for example, a heated roller and / or a pressure roller. The unfixed toner image transferred from the transfer device 48 is heated and / or pressurized by the fixing device 54. The toner image is heated and / or pressurized, thereby fixing the toner image onto the recording medium P. As a result, an image is formed on the recording medium P.

[0204] As described above, an example of an image forming apparatus has been given, but the image forming apparatus is not limited to the image forming apparatus 100 described above. The image forming apparatus 100 described above is a color image forming apparatus, but it can also be a monochrome image forming apparatus. In such cases, the image forming apparatus may have only one image forming unit. Furthermore, the image forming apparatus 100 described above is in series configuration, but it may also be in a rotary configuration. The charging device 42 is described using a charged roller as an example, but the charging device may also be a charging device other than a charged roller (e.g., a gate corona tube charger, a charged brush, or a corona tube charger). The image forming apparatus 100 described above uses a contact development method, but it may also use a non-contact development method. The image forming apparatus 100 described above uses a direct transfer method, but it may also use an intermediate transfer method. In the case of an intermediate transfer method, the intermediate transfer belt is equivalent to the object being transferred. In the image forming apparatus, the image forming unit 40 described above does not have a cleaning component, but it may further include a cleaning component (e.g., a cleaning blade). In addition, the image forming unit 40 described above does not have an anti-static device, but the image forming unit may further have an anti-static device.

[0205] <Third Implementation Method: Processing Box>

[0206] Next, continue to refer to Figure 7 An example of a processing cartridge according to a third embodiment of the present invention will be described. The processing cartridge corresponds to each of the image forming units 40a to 40d. The processing cartridge includes an image carrier 30. The image carrier 30 is a photosensitive element of the first embodiment. As described above, the photosensitive element of the first embodiment can improve anti-fogging properties. Therefore, by including the photosensitive element of the first embodiment as the image carrier 30, the processing cartridge can form an image with less fogging on the recording medium P. In addition to the image carrier 30, the processing cartridge also includes at least one device selected from the group consisting of a charging device 42, an exposure device 44, a developing device 46, and a transfer device 48. The processing cartridge may further include a cleaning component (not shown) and an anti-static device (not shown). The processing cartridge is designed to be detachable from the image forming apparatus 100. Therefore, the processing cartridge is easy to handle, and if the photosensitivity characteristics of the image carrier 30 deteriorate, the components including the image carrier 30 can be easily and quickly replaced. As described above, referring to Figure 7 The processing box having the photoreceptor of the first embodiment is described.

[0207]

Example

[0208] The present invention will now be described in more detail using examples. However, the present invention is not limited in any way to the scope of the examples.

[0209] <Preparation of polyarylate resins (R-1) to (R-7) and (R-12) to (R-24)>

[0210] The polyaryl ester resins (R-1) to (R-7) involved in the examples and the polyaryl ester resins (R-12) to (R-24) involved in the comparative examples were synthesized by the following method. Hereinafter, "polyaryl ester resins (R-1) to (R-7) and (R-12) to (R-24)" are referred to as "resins (R-1) to (R-7) and (R-12) to (R-24)" respectively. The composition of resins (R-1) to (R-7) and (R-12) to (R-24) is shown in Table 3 below.

[0211] Table 3

[0212]

[0213] In Table 3, “BisCZ”, “BisB”, “BisC”, “BisZ”, “BisCE”, “DHPE”, “DPEC”, “TPC” and “IPC” represent the compounds shown by the following formulas (BisCZ), (BisB), (BisC), (BisZ), (BisCE), (DHPE), (DPEC), (TPC) and (IPC) respectively (hereinafter, they are sometimes referred to as compounds (BisCZ), (BisB), (BisC), (BisZ), (BisCE), (DHPE), (DPEC), (TPC) and (IPC) respectively).

[0214]

[0215] Furthermore, the meanings of the terms in Table 3 are as follows.

[0216] Monomer: The monomer used in the synthesis of polyarylate resins

[0217] Resin: Polyarylate resin

[0218] Bisphenol addition rate: The percentage (in moles) of the amount of bisphenol monomer added relative to the total amount (in moles) of bisphenol monomer added in the synthesis of polyarylate resin.

[0219] Dicarboxylic acid addition rate: The percentage (in moles) of the amount of dicarboxylic acid monomer added relative to the total amount (in moles) of dicarboxylic acid monomer added in the synthesis of polyarylate resin.

[0220] Unit: Repeating unit. Furthermore, the repeating units described in Table 3 are formed from the corresponding monomers described in Table 3.

[0221] Unit (BisC): A repeating unit derived from the compound (BisC).

[0222] Unit (BisZ): A repeating unit derived from the compound (BisZ).

[0223] Unit (BisCE): A repeating unit derived from the compound (BisCE).

[0224] Unit (IPC): A repeating unit derived from a compound (IPC).

[0225] DMP: 2,6-Dimethylphenol

[0226] PFH: 1H,1H-perfluoro-1-heptanol

[0227] -: This monomer was not used.

[0228] (Synthesis of resin (R-1))

[0229] A three-necked flask equipped with a thermometer, a three-way valve, and a dropping funnel was used as the reaction vessel. In the reaction vessel, the following compounds were added: BisCZ (32.8 mmol) as a monomer, DHPE (8.2 mmol) as a monomer, 2,6-dimethylphenol (0.413 mmol) as a terminator, sodium hydroxide (98 mmol), and benzyltributylammonium chloride (0.384 mmol). The air in the reaction vessel was purged with argon. Water (300 mL) was added to the contents of the reaction vessel. The contents of the reaction vessel were stirred at 50°C for 1 hour. The contents of the reaction vessel were cooled to 10°C to obtain an alkaline aqueous solution, SA.

[0230] Next, dichloride dicarboxylic acid (20.8 mmol) as a monomer (DPEC) and dichloride dicarboxylic acid (11.2 mmol) as a monomer (TPC) were dissolved in chloroform (150 mL). This yielded chloroform solution SB.

[0231] Compared to the alkaline aqueous solution SA, a chloroform solution SB was slowly added dropwise over 110 minutes using a dropping funnel. The temperature (liquid temperature) of the contents of the reaction vessel was adjusted to 15±5℃, and the contents of the reaction vessel were stirred for 4 hours to carry out the polymerization reaction. Using a decanter, the upper layer (aqueous layer) of the contents of the reaction vessel was removed to obtain the organic layer. Then, 400 mL of ion-exchanged water was added to an Erlenmeyer flask. The obtained organic layer was then added to the Erlenmeyer flask. Chloroform (400 mL) and acetic acid (2 mL) were further added to the Erlenmeyer flask. The contents of the Erlenmeyer flask were stirred at room temperature (25℃) for 30 minutes. Using a decanter, the upper layer (aqueous layer) of the contents of the Erlenmeyer flask was removed to obtain the organic layer. The obtained organic layer was washed with ion-exchanged water (1 L) using a separatory funnel. The washing with ion-exchanged water was repeated 5 times to obtain a water-washed organic layer. Next, the water-washed organic layer was filtered to obtain the filtrate. The resulting filtrate was slowly added dropwise to methanol (1 L), yielding a precipitate. The precipitate was then removed by filtration. The removed precipitate was then vacuum-dried at 70°C for 12 hours. The result was a resin (R-1) with a viscosity-average molecular weight of 56,000.

[0232] By varying the amount of the terminator added, resins (R-1) with the viscosity-average molecular weights shown in Tables 4-8 and 15-21 were obtained. Alternatively, resins (R-1) with the viscosity-average molecular weights shown in these tables were synthesized using the same method as resin (R-1) with a viscosity-average molecular weight of 56,000. Furthermore, the lower the amount of terminator added, the higher the viscosity-average molecular weight of resin (R-1).

[0233] (Synthesis of resins (R-2) to (R-7) and (R-12) to (R-24))

[0234] Using the monomers listed in Table 3 according to the addition rates, resins (R-2) to (R-7) and (R-12) to (R-24) were obtained using the same synthesis method as resin (R-1). Furthermore, the addition amounts of each bisphenol monomer were set to achieve a total bisphenol monomer content of 41.0 mmol, meeting the bisphenol addition rates specified in Table 3. For example, in the synthesis of resin (R-5), the addition amount of compound (BisB) was 32.8 mmol (=41.0×80 / 100), and the addition amount of compound (DHPE) was 8.2 mmol (=41.0×20 / 100). Additionally, the addition amounts of each dicarboxylic acid monomer were set to achieve a total dicarboxylic acid monomer content of 32.0 mmol, meeting the dicarboxylic acid addition rates specified in Table 3. For example, in the synthesis of resin (R-5), the amount of compound (DPEC) added is 16.0 mmol (=32.0×50 / 100), and the amount of compound (TPC) added is 16.0 mmol (=32.0×50 / 100).

[0235] Using a proton nuclear magnetic resonance spectrometer (manufactured by NEC Corporation, 600MHz), the obtained resins (R-1) to (R-7) and (R-12) to (R-24) were measured. 1 1H-NMR spectra. Deuterated chloroform was used as the solvent. Tetramethylsilane (TMS) was used as the internal standard. Representative example resin (R-1) from resins (R-1) to (R-7) and (R-12) to (R-24) is shown. 1 The H-NMR spectrum indicates that... Figure 8 According to from 1 The chemical shifts read from the H-NMR spectrum confirmed the presence of resin (R-1). Resins (R-2) to (R-7) and (R-12) to (R-24) were also confirmed using the same method.

[0236] <Polycarbonate resins (R-8) to (R-10) and polyarylate resins (R-11)>

[0237] The polycarbonate resins shown in formulas (R-8) to (R-10) and the polyarylate resins shown in formula (R-11) are used as binder resins in the manufacture of the photoreceptor involved in the comparative example. Hereinafter, "the polycarbonate resins shown in formulas (R-8) to (R-10) and the polyarylate resins shown in formula (R-11)" are sometimes referred to as "resins (R-8) to (R-11)". In formula (R-10), m1 and m2, and in formula (R-11), n1, n2, n3, and n4, represent the percentage (in mol%) of the repeating unit relative to the total number of repeating units contained in the resin. In formula (R-10), m1 and m2 are 50 mol% and 50 mol%, respectively. In formula (R-11), n1, n2, n3, and n4 are 25 mol%, 25 mol%, 25 mol%, and 25 mol%, respectively. Furthermore, the viscosity-average molecular weights of resins (R-8) to (R-11) are 65,000, 58,000, 51,000, and 55,000, respectively.

[0238]

[0239] <Manufacturing of Single-Layer Photoreceptors>

[0240] (Manufacturing of a single-layer photoreceptor (A-1))

[0241] Using a rod-shaped acoustic oscillator, 2 parts by mass of Y-type titanium phthalocyanine (as a charge generator), 70 parts by mass of hole transporter (H-1) (as a hole transporter (SL), 50 parts by mass of electron transporter (E-1), 100 parts by mass of resin (R-1) (viscosity-average molecular weight 35200) (as a binder resin (SL), and 500 parts by mass of tetrahydrofuran (as a solvent) were mixed for 20 minutes to obtain a dispersion. The dispersion was filtered using a 5 μm pore size filter to obtain a coating solution for a single-layer photosensitive layer. The coating solution for the single-layer photosensitive layer was coated onto a conductive substrate (an aluminum drum-shaped support) by dip coating and dried with hot air at 120°C for 50 minutes. Thus, a single-layer photosensitive layer (film thickness 30 μm) was formed on the conductive substrate, resulting in a single-layer photoreceptor (A-1). In the single-layer photoreceptor (A-1), a single-layer photosensitive layer is formed directly on a conductive substrate.

[0242] (Manufacturing of single-layer photosensitive materials (A-2) to (A-70) and (B-1) to (B-25))

[0243] Using resins of the types and viscosity-average molecular weights listed in Tables 4 to 10 in the amounts listed in Tables 4 to 10, using hole transport agents of the types listed in Tables 4 to 10 in the amounts listed in Tables 4 to 10, using electron transport agents of the types listed in Tables 4 to 10 in the amounts listed in Tables 4 to 10, and in addition, manufacturing monolayer photoreceptors (A-2) to (A-70) and (B-1) to (B-25) respectively according to the manufacturing method of monolayer photoreceptor (A-1).

[0244] <Manufacturing of Positively Charged Laminated Photoreceptors>

[0245] (Manufacturing of a positively charged multilayer photoreceptor (C-1))

[0246] First, a charge transport layer is formed. Specifically, using a rod-shaped acoustic oscillator, 100 parts by mass of hole transport agent (H-10) as a hole transport agent (CT), 100 parts by mass of resin (R-1) (viscosity-average molecular weight 62,000) as a binder resin (CT), and 500 parts by mass of tetrahydrofuran as a solvent are mixed for 20 minutes to obtain a dispersion. The dispersion is filtered using a filter with a pore size of 5 μm to obtain a coating solution for the charge transport layer. The coating solution for the charge transport layer is applied to a conductive substrate (an aluminum drum-shaped support) by dip coating and dried with hot air at 120°C for 50 minutes. Thus, a charge transport layer (15 μm thick) is formed on the conductive substrate.

[0247] Next, a charge-generating layer is formed. Specifically, using a rod-shaped acoustic oscillator, 2 parts by mass of Y-type titanium phthalocyanine (as a charge-generating agent), 70 parts by mass of hole transport agent (H-1) (as a hole transport agent (CG), 50 parts by mass of electron transport agent (E-1), 100 parts by mass of resin (R-1) (viscosity-average molecular weight 35200) (as a binder resin (CG), and 500 parts by mass of 1,2-dichloroethane (as a solvent) are mixed for 20 minutes to obtain a dispersion. The dispersion is filtered using a 5 μm pore size filter to obtain a coating solution for the charge-generating layer. The coating solution for the charge-generating layer is applied to the formed charge transport layer by dip coating and dried with hot air at 120°C for 50 minutes. Thus, a charge-generating layer (15 μm thick) is formed on the charge transport layer, resulting in a positively charged laminated photoreceptor (C-1). In a positively charged laminated photoreceptor (C-1), the charge transport layer is directly on the conductive substrate, and the charge generation layer is directly on the charge transport layer.

[0248] (Manufacturing of positively charged laminated photoreceptors (C-2) to (C-75) and (D-1) to (D-25))

[0249] Using the type and viscosity-average molecular weight of resin listed in the "Charge Transport Layer" column of Tables 15 to 21 as the binder resin (CT), using the type and viscosity-average molecular weight of resin listed in the same column as the binder resin (CG) in the amount indicated in the "Charge Generation Layer" column of Tables 15 to 21, using the type of hole transporter listed in the same column as the hole transporter (CG) in the amount indicated in the "Charge Generation Layer" column of Tables 15 to 21, and using the type of charge transporter listed in the same column as the amount indicated in the "Charge Generation Layer" column of Tables 15 to 21, a charge generation layer is formed with a film thickness as shown in the "Charge Generation Layer" column of Tables 15 to 21. Apart from these, positively charged laminated photoreceptors (C-2) to (C-75) and (D-1) to (D-25) are manufactured according to the manufacturing method of positively charged laminated photoreceptor (C-1). Furthermore, the amounts of binder resin (CT) and hole transporter (CT) added in the manufacture of positively charged laminated photoreceptors (C-2) to (C-75) and (D-1) to (D-25) are the same as those added in the manufacture of positively charged laminated photoreceptor (C-1). Also, the film thickness of the charge generation layer is changed by altering the speed at which the conductive substrate is pulled upwards from the coating liquid used to coat the charge generation layer. The faster the upward pull, the thicker the film thickness of the charge generation layer.

[0250] <Measurement of viscosity-average molecular weight>

[0251] The viscosity-average molecular weight of the resin was measured according to JIS (Japanese Industrial Standard) K7252-1:2016. The measured viscosity-average molecular weights are shown in Tables 4 to 10 and Tables 15 to 21.

[0252] <Measurement of film thickness>

[0253] The film thickness was measured using an eddy current film thickness gauge (manufactured by Kett Electric Laboratory, Ltd., "LH-373"). The measured film thicknesses are shown in Tables 4 to 10 and Tables 15 to 21.

[0254] <Measurement of Scratch Resistance Depth>

[0255] The scratch resistance depth was measured using a scratching device 200 as specified in JIS K5600-5-5 (Japanese Industrial Standard K5600: General Test Methods for Coatings; Part 5: Mechanical Properties of Coatings; Section 5: Scratch Hardness (Load Needle Method)).

[0256] The scratch resistance depth is measured on a photoreceptor (either a single-layer photoreceptor 1 or a positively charged laminated photoreceptor 10). The following explanation uses the case of a single-layer photoreceptor 1 as an example. Regarding the case of a positively charged laminated photoreceptor 10, the measurement is performed using the same method as for measuring the scratch resistance depth of the single-layer photoreceptor 1, except that the single-layer photoreceptor 1 is replaced with a positively charged laminated photoreceptor 10.

[0257] First, refer to Figure 9 The scraping device 200 will be described below. Figure 9 This is an example structural diagram of the scraping device 200. The scraping device 200 includes: a fixed platform 201, a fixing member 202, a scraping needle 203, a support arm 204, two shaft support parts 205, a base 206, two guide rail parts 207, a weight dish 208, and a constant speed motor (not shown).

[0258] Figure 9 In this diagram, the X-axis and Y-axis are horizontal, and the Z-axis is vertical. The X-axis represents the direction of the long side of the fixed platform 201. The Y-axis represents the direction orthogonal to the X-axis in a plane parallel to the top surface 201a (placement surface) of the fixed platform 201. Furthermore, as described later... Figures 10-12 The X-axis, Y-axis, and Z-axis directions are also related to Figure 9 They have the same meaning.

[0259] The mounting platform 201 is equivalent to the test plate mounting platform in JIS (Japanese Industrial Standard) K5600-5-5. The mounting platform 201 has a top surface 201a, one end 201b, and the other end 201c. One end 201b is opposite to two shaft support parts 205.

[0260] The fixing member 202 is disposed on one side of the other end 201c on the top surface 201a of the fixing stage 201. The fixing member 202 fixes the measuring object (single-layer photoreceptor 1) on the top surface 201a of the fixing stage 201. The top surface 201a of the fixing stage 201 is a horizontal plane.

[0261] The scraping needle 203 has a needle tip 203b (see reference). Figure 10 The structure of needle-tip 203b is a hemispherical shape with a diameter of 1 mm. The material of needle-tip 203b is sapphire.

[0262] The support arm 204 supports the scraping needle 203. The support arm 204 rotates about the support shaft 204a in the direction in which the scraping needle 203 approaches and moves away from the single-layer photoreceptor 1.

[0263] Two shaft support portions 205 support the support arm portion 204 so that it can rotate.

[0264] The base 206 has a top surface 206a. Two shaft support portions 205 are provided on one end side of the top surface 206a.

[0265] Two guide rails 207 are provided on the other end of the top surface 206a. The two guide rails 207 are arranged parallel to each other. Each of the two guide rails 207 is arranged parallel to the long side direction (X-axis direction) of the fixed stage 201. The fixed stage 201 is mounted between the two guide rails 207. The fixed stage 201 can move horizontally along the guide rails 207 in the long side direction (X-axis direction) of the fixed stage 201.

[0266] The weight dish 208 is positioned above the scraping needle 203, separated by the support arm 204. Weights 209 are placed on the weight dish 208.

[0267] The constant speed motor moves along the guide rail 207 in the long side direction (X-axis direction) of the fixed platform 201.

[0268] The following describes the method for measuring scratch resistance depth. The method for measuring scratch resistance depth includes four steps: a first step, a second step, a third step, and a fourth step. Scratch resistance depth is measured using a scratching apparatus 200 as specified in JISK 5600-5-5. A surface performance measuring instrument (HEIDON TYPE14, manufactured by Shin-To Science Co., Ltd.) is used as the scratching apparatus 200. The scratch resistance depth measurement is performed at a temperature of 23°C and a relative humidity of 50% RH. The photoreceptor is drum-shaped (cylindrical). By employing the following scratch depth measurement method, the photosensitive layer characteristics that affect the generation of haze in the formed image are measured with high precision.

[0269] (First step)

[0270] In the first step, the single-layer photoreceptor 1 is fixed on the top surface 201a of the stage 201, such that the long side of the single-layer photoreceptor 1 is parallel to the long side of the stage 201. The direction of the central axis L2 (rotation axis) of the single-layer photoreceptor 1 corresponds to the long side direction of the single-layer photoreceptor 1. Furthermore, when the single-layer photoreceptor 1 is sheet-like, the length direction of the single-layer photoreceptor 1 corresponds to the long side direction of the single-layer photoreceptor 1.

[0271] (Second Step)

[0272] In the second step, the scraping needle 203 is brought into perpendicular contact with the surface 3a of the photosensitive layer 3 of the monolayer photoreceptor 1. Figure 9 Based on this, and then refer to Figure 10 and Figure 11 The method of making the scraping needle 203 perpendicularly contact the surface 3a of the photosensitive layer 3 of the drum-shaped single-layer photoreceptor 1 will be described. Figure 10 yes Figure 9 A cross-sectional view of line XX in the diagram. Figure 10 This is a cross-sectional view of the scratching needle 203 when it comes into contact with the single-layer photoreceptor 1. Figure 11 yes Figure 9 Side view of the fixed stage 201, the scraping needle 203 and the single-layer photoreceptor 1.

[0273] The squeegee 203 is brought close to the single-layer photoreceptor 1, such that the extension of the central axis A1 of the squeegee 203 is perpendicular to the top surface 201a of the stage 201. Then, the tip 203b of the squeegee 203 is brought into contact with the point on the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1 that is furthest from the top surface 201a of the stage 201 in the vertical direction (Z-axis direction). Thus, the tip 203b of the squeegee 203 contacts the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1 at contact point P3. Furthermore, the tip 203b of the squeegee 203 contacts the single-layer photoreceptor 1 such that the central axis A1 of the squeegee 203 is perpendicular to the tangent A2. Tangent A2 is the tangent at contact point P3 to the outer circle formed by the cross-section perpendicular to the central axis L2 in the single-layer photoreceptor 1. Therefore, the squeegee 203 is perpendicularly pressed against the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1. In addition, when the single-layer photoreceptor 1 is in sheet form, the squeegee 203 is pressed against the surface 3a of the photosensitive layer 3 such that the extension line of the central axis A1 of the squeegee 203 is perpendicular to the surface 3a (plane) of the photosensitive layer 3 of the single-layer photoreceptor 1.

[0274] After the squeegee 203 is brought into contact using the method described above, the positional relationship between the fixed stage 201, the single-layer photoreceptor 1, and the squeegee 203 is as follows: The extension line of the central axis A1 of the squeegee 203 intersects perpendicularly with the central axis L2 of the single-layer photoreceptor 1 at point P2. The contact point P1 and intersection point P2 between the photosensitive layer 3 and the top surface 201a, and the contact point P3 between the photosensitive layer 3 and the tip 203b of the squeegee 203, are located on the extension line of the central axis A1 of the squeegee 203. Furthermore, the extension line of the central axis A1 of the squeegee 203 is perpendicular to both the top surface 201a and the tangent A2 of the fixed stage 201.

[0275] (Step 3)

[0276] In the third step, with the squeegee 203 perpendicularly abutting against the surface 3a of the photosensitive layer 3, a load W of 10g is applied to the photosensitive layer 3 by the squeegee 203. Specifically, a 10g weight 209 is placed in the weight dish 208. In this state, the fixed stage 201 is moved. Specifically, a constant-speed motor is driven to move horizontally along the guide rail 207 in the long side direction (X-axis direction) of the fixed stage 201. That is, one end 201b of the fixed stage 201 is moved from the first position N1 to the second position N2. Furthermore, in the long side direction of the fixed stage 201, the second position N2 is located downstream of the fixed stage 201 from the first position N1 in the direction away from the two shaft support portions 205. As the fixed stage 201 moves in the long side direction, the single-layer photoreceptor 1 also moves horizontally in the long side direction of the fixed stage 201. The moving speed of the fixed stage 201 and the single-layer photoreceptor 1 is 30mm / min. The moving distance of the fixed stage 201 and the single-layer photoreceptor 1 is 30mm. This moving distance is equivalent to the distance D between the first position N1 and the second position N2. 1-2 As a result of the movement of the fixed stage 201 and the single-layer photoreceptor 1, scratches S are formed on the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1 by the scratching needle 203. Figures 9-11 Based on and refer to Figure 12 The scratch S is explained. Figure 12 This indicates a scratch S formed on the surface 3a of the photosensitive layer 3. The scratch S is perpendicular to both the top surface 201a of the stage 201 and the tangent A2. Furthermore, the scratch S passes through... Figure 11 Line L3 is formed by several contact points P3. Line L3 is parallel to the top surface 201a of the fixed stage 201 and the central axis L2 of the single-layer photoreceptor 1. Line L3 is perpendicular to the central axis A1 of the wiping needle 203.

[0277] (Fourth step)

[0278] In the fourth step, the maximum depth Ds of the scratch S is measured. maxThis refers to the scratch resistance depth. Specifically, the monolayer photoreceptor 1 is removed from the stage 201. Using a three-dimensional interference microscope (Bruker WYKO NT-1100), the scratch S formed on the photosensitive layer 3 of the monolayer photoreceptor 1 is observed at 5x magnification, and the depth Ds of the scratch S is measured. The depth Ds of the scratch S corresponds to the distance from the tangent A2 to the bottom of the scratch S. The maximum depth Ds of the scratch S is then measured. max The scratch resistance depth is used as the measurement of scratch resistance depth (unit: μm). The measured scratch resistance depths are shown in Tables 4–10 and 15–21.

[0279] <Measurement of Fracture Strain>

[0280] Among the manufactured single-layer and positively charged laminated photoreceptors, the single-layer photoreceptor in Table 11 and the positively charged laminated photoreceptor in Table 22 are used as representative examples to measure the fracture strain of the first photosensitive layer. Specifically, the first photosensitive layer is peeled off from the conductive substrate of the photoreceptor (single-layer and positively charged laminated photoreceptor). Then, the first photosensitive layer is cut into a size of 3 mm wide and 30 mm long to obtain a sample. Then, the sample is mounted on a tensile testing machine (Autograph (Japan registered trademark) AGS-J 5kN) manufactured by Shimadzu Corporation. When mounting the sample, the clamp spacing of the tensile testing machine is adjusted to 8 mm. Then, the sample is stretched at a tensile speed of 5 mm / min in an environment of 23°C and 50% RH to obtain a stress-strain curve. The fracture strain is calculated based on the obtained stress-strain curve. The measured fracture strains are shown in Tables 11 and 22.

[0281] <Measurement of Vickers Hardness>

[0282] In the manufactured single-layer and positively charged multilayer photoreceptors, the single-layer photoreceptor in Table 12 and the positively charged multilayer photoreceptor in Table 23 are used as representative examples to measure the Vickers hardness of the first photosensitive layer. Specifically, the Vickers hardness of the first photosensitive layer is measured according to JIS (Japanese Industrial Standard) Z2244. In the Vickers hardness measurement, a hardness tester (Matsuzawa Co., Ltd., formerly known as Matsuzawa Seiki Co., Ltd., "Micro Vickers Hardness Tester DMH-1") is used. The Vickers hardness is measured under the following conditions: temperature 23°C, diamond indenter load (test force) 10 gf, time to reach the test force 5 seconds, diamond indenter approach speed 2 mm / s, and test force holding time 1 second. The measured Vickers hardness is shown in Tables 12 and 23.

[0283] <Evaluation>

[0284] A modified monochrome printer (ECOSYS P2040dw, manufactured by Kyocera Office Information Systems Co., Ltd.) was used as an evaluation machine for assessing fog resistance and abrasion resistance. This evaluation machine is equipped with an electrified roller as a charging device. Furthermore, the evaluation machine employs both contact development and direct transfer methods. It also lacks a cleaning blade. The paper used for evaluation was Kyocera Office Information Systems brand paper VM-A4 (A4 size), sold by Kyocera Office Information Systems Co., Ltd. The developer used for evaluation was a single-component developer (for pilot production samples). The evaluation machine was set with the photoreceptor (specifically, a single-layer photoreceptor and a positively charged laminated photoreceptor) rotating at 240 mm / s and the photoreceptor's electrical potential at +600V.

[0285] (Evaluation of resistance to fog)

[0286] For both single-layer and positively charged multilayer photosensitive materials, the resistance to fogging was evaluated. The evaluation was conducted at 32.5°C and 80% RH. Using an evaluation machine, a 1% coverage image was continuously printed on 12,000 sheets of paper. Next, a blank image was printed on a single sheet of paper. Using a reflectance densitometer (X-rite "RD914"), the reflectance concentration at three points within the blank image on the printed paper was measured, and the arithmetic mean was taken as reflectance concentration A. Also, the reflectance concentration at three points on the unprinted paper was measured, and the arithmetic mean was taken as reflectance concentration B. Then, the fogging density (FD) was calculated based on the formula "FD = reflectance concentration A - reflectance concentration B". Based on the calculated FD, the resistance to fogging was evaluated according to the following criteria. FD and the evaluation results are shown in Tables 4-10 and Tables 15-21. Photoreceptors rated A, B, and C are evaluated as having good resistance to fogging, while photoreceptors rated D are evaluated as having poor resistance to fogging.

[0287] (Criteria for determining resistance to fog)

[0288] Judgment A: FD is below 0.010.

[0289] Judgment B: FD is higher than 0.010 and lower than 0.020.

[0290] Judgment C: FD is higher than 0.020 and less than 0.045.

[0291] Determining D (Defective): FD is 0.045 or higher.

[0292] (Evaluation of wear resistance)

[0293] Among the manufactured single-layer and positively charged laminated photoreceptors, the single-layer photoreceptors in Table 13 and the positively charged laminated photoreceptors in Table 24 are used as representative examples to evaluate abrasion resistance. The abrasion resistance evaluation was conducted at a temperature of 23°C and a relative humidity of 50% RH. The film thickness T1 of the first photosensitive layer was measured. Then, the photoreceptor was mounted in an evaluation machine. Using the evaluation machine, continuous printing of an image with a 1% coverage was performed on 15,000 sheets of paper. After printing, the film thickness T2 of the first photosensitive layer was measured. Furthermore, the film thicknesses T1 and T2 were measured using the method described above in <Film Thickness Measurement>. Then, the abrasion amount of the first photosensitive layer (unit: μm) was calculated according to the formula "Abrasion Amount = T1 - T2". The calculated abrasion amounts are shown in Tables 13 and 24. The lower the abrasion amount, the better the abrasion resistance of the photoreceptor. Furthermore, if the abrasion amount is 6.0 μm or less, it is judged that the abrasion resistance is sufficient for practical use.

[0294] (Evaluation of photosensitivity characteristics)

[0295] Among the manufactured single-layer and positively charged multilayer photoreceptors, the single-layer photoreceptors in Table 14 and the positively charged multilayer photoreceptors in Table 25 were used as representative examples to evaluate photosensitivity characteristics. The photosensitivity characteristics of the photoreceptors were evaluated using a drum photosensitivity tester (manufactured by GENTEC Corporation) at an environment of 23°C and 50% RH. Specifically, the photoreceptor was charged using the drum photosensitivity tester until its surface potential reached +600V. Then, monochromatic light (wavelength 780nm, half-width 20nm, light energy 1.0μJ / cm) was extracted from the light of a halogen lamp using a bandpass filter and irradiated onto the surface of the photoreceptor. The surface potential of the photoreceptor was measured 0.5 seconds after the start of monochromatic light irradiation, and this was recorded as the post-exposure potential (V). L (Unit: +V). The post-exposure potentials of each photoreceptor are shown in Tables 14 and 25. The smaller the post-exposure potential value, the better the photosensitivity characteristics of the photoreceptor. Furthermore, if the post-exposure potential is below +135V, it is considered that the photosensitivity characteristics are sufficient for practical use.

[0296] The following are Tables 4 through 25. Additionally, the meanings of the terms used in Tables 4 through 25 are as follows.

[0297] • Molecular weight: viscosity-average molecular weight

[0298] • Ratio: The ratio of the mass of the adhesive resin to the mass of the first photosensitive layer.

[0299] • Fog: Evaluation of Fog Resistance

[0300] •FD: Fog Density

[0301] • Coating solution cannot be prepared: The resin is insoluble in the solvent used to prepare the coating solution, making it impossible to prepare the coating solution.

[0302] • Unmeasurable: The resin is insoluble in the solvent used for viscosity and molecular weight measurement, making it impossible to measure the viscosity-average molecular weight.

[0303] • Hardness: Vickers hardness

[0304] ·V L Post-exposure potential

[0305]

[0306]

[0307]

[0308]

[0309]

[0310]

[0311]

[0312] Table 11

[0313]

[0314] Table 12

[0315]

[0316] Table 13

[0317]

[0318] Table 14

[0319]

[0320]

[0321]

[0322]

[0323]

[0324]

[0325]

[0326]

[0327] Table 22

[0328]

[0329] Table 23

[0330]

[0331] Table 24

[0332]

[0333] Table 25

[0334]

[0335] As can be seen from formulas (R-8) to (R-11), resins (R-8) to (R-11) are not resins included in polyaryl ester resins (PA). As can be seen from Table 3, resins (R-12) to (R-24) are not resins included in polyaryl ester resins (PA). Therefore, as shown in Table 10, resins (R-12), (R-14), (R-16), (R-21), and (R-24) are insoluble in the solvent used to prepare the coating solution for a single-layer photosensitive layer, and a coating solution for a single-layer photosensitive layer cannot be prepared, thus failing to form a photosensitive layer (more specifically, a single-layer photosensitive layer). Furthermore, as shown in Tables 9 and 10, the single-layer photosensitive layers containing resins (R-8) to (R-11), (R-13), (R-15), (R-17) to (R-20), and (R-22) to (R-23) exhibit poor resistance to fogging. Also, as shown in Table 21, resins (R-12), (R-14), (R-16), (R-21), and (R-24) are insoluble in the solvent used to prepare the coating solution for the charge-generating layer, making it impossible to prepare the coating solution for the charge-generating layer and thus failing to form the photosensitive layer (more specifically, the charge-generating layer). Furthermore, as shown in Tables 20 and 21, the positively charged laminated photoreceptors (D-1) to (D-12), (D-14), (D-16), (D-18) to (D-21), and (D-23) to (D-24) containing resins (R-8) to (R-11), (R-13), (R-15), (R-17) to (R-20), and (R-22) to (R-23) in the charge generation layer have poor anti-fogging properties.

[0336] On the other hand, as shown in Table 3, resins (R-1) to (R-7) are resins contained in polyaryl ester resins (PA). Therefore, as shown in Tables 4 to 8, the single-layer photoreceptors (A-1) to (A-70) containing resins (R-1) to (R-7) in the single-layer photosensitive layer exhibit good anti-fogging properties. Furthermore, as shown in Tables 15 to 19, the positively charged multilayer photoreceptors (C-1) to (C-75) containing resins (R-1) to (R-7) in the charge-generating layer exhibit good anti-fogging properties.

[0337] As shown in Table 11, the fracture strain of the single-layer photosensitive layer in the single-layer photosensitive material (A-21) is less than 7.5%. As shown in Table 13, the wear of single-layer photosensitive materials (A-1) to (A-20) and (A-22) is less than that of single-layer photosensitive material (A-21). As shown in Table 22, the fracture strain of the charge-generating layer in the positively charged laminated photosensitive material (C-21) is less than 7.5%. As shown in Table 22, the wear of single-layer photosensitive materials (C-1) to (C-20) and (C-22) is less than that of single-layer photosensitive material (A-21). Therefore, photosensitive materials with a fracture strain of 7.5% or higher in the first photosensitive layer (single-layer photosensitive layer and charge-generating layer) exhibit excellent resistance to fogging and excellent wear resistance.

[0338] As shown in Table 11, the fracture strain of the single-layer photosensitive layer in the monolayer photosensitive material (A-22) exceeds 21.0%. As shown in Table 5, the fog resistance of the monolayer photosensitive material (A-22) is determined to be B. As shown in Table 22, the fracture strain of the charge-generating layer in the positively charged multilayer photosensitive material (C-22) exceeds 21.0%. As shown in Table 16, the fog resistance of the positively charged multilayer photosensitive material (C-22) is determined to be B. It is determined that by reducing the fracture strain of the first photosensitive layer (the monolayer photosensitive layer and the charge-generating layer) to below 21.0%, the fog resistance of the photosensitive material can be improved even further than determination B.

[0339] As shown in Table 12, the Vickers hardness of single-layer photoresists (A-14) to (A-19), (A-52) to (A-67), and (A-70) is above 19.0 HV. The Vickers hardness of single-layer photoresists (B-5) to (B-8), (B-14), (B-16), (B-18) to (B-21), and (B-23) to (B-24) is less than 19.0 HV. As shown in Tables 4 to 10, the fog resistance of single-layer photoresists (A-14) to (A-19), (A-52) to (A-67), and (A-70) is superior to that of single-layer photoresists (B-5) to (B-8), (B-14), (B-16), (B-18) to (B-21), and (B-23) to (B-24). As shown in Table 23, the Vickers hardness of positively charged multilayer photoreceptors (C-52) to (C-75) is above 19.0 HV. The Vickers hardness of positively charged multilayer photoreceptors (D-5) to (D-8), (D-14), (D-16), (D-18) to (D-21), and (D-23) to (D-24) is less than 19.0 HV. As shown in Tables 15 to 21, the fog resistance of positively charged multilayer photoreceptors (C-52) to (C-75) is superior to that of positively charged multilayer photoreceptors (D-5) to (D-8), (D-14), (D-16), (D-18) to (D-21), and (D-23) to (D-24). Therefore, it was determined that by making the Vickers hardness of the first photosensitive layer (single-layer photosensitive layer and charge generation layer) above 19.0 HV, the resistance of the photosensitive material to fog can be further improved.

[0340] As shown in Table 7, the monolayer photoreceptor (A-49) contains the hole transporter (H-11) included in formula (25) as a hole transporter (SL). As shown in Table 14, the post-exposure potential of the monolayer photoreceptor (A-49) exceeds +130V. As shown in Tables 5 to 7, the monolayer photoreceptors (A-23) to (A-48) and (A-50) contain the hole transporter included in formulas (20), (21), (22), (23), or (24). As shown in Table 14, the post-exposure potential of the monolayer photoreceptors (A-23) to (A-48) and (A-50) is below +130V. As shown in Table 18, the positively charged multilayer photoreceptor (C-49) contains the hole transporter (H-11) included in formula (25) as a hole transporter (CG). As shown in Table 25, the post-exposure potential of the positively charged multilayer photoreceptor (C-49) exceeds +130V. As shown in Tables 16 to 18, the positively charged multilayer photoreceptors (C-23) to (C-48) and (C-50) contain hole transport agents contained in formulas (20), (21), (22), (23), or (24). As shown in Table 25, the post-exposure potential of the positively charged multilayer photoreceptors (C-23) to (C-48) and (C-50) is below +130V. Therefore, it is determined that by including hole transport agents (20), (21), (22), (23), or (24) in the first photosensitive layer (monolayer photosensitive layer and charge generation layer), the photosensitivity characteristics of the photoreceptor are improved in addition to improving the anti-fogging properties of the photoreceptor.

[0341] As shown in Table 7, the mass ratio of the binder resin (SL) to the mass of the monolayer photoreceptor (A-51) exceeds 0.50. As shown in Table 14, the post-exposure potential of the monolayer photoreceptor (A-51) exceeds +130V. As shown in Tables 5 to 7, the mass ratio of the binder resin (SL) to the mass of the monolayer photoreceptor (A-23) to (A-48) and (A-50) is less than 0.50. As shown in Table 14, the post-exposure potential of the monolayer photoreceptor (A-23) to (A-48) and (A-50) is less than +130V. As shown in Table 18, the mass ratio of the binder resin (CG) to the mass of the charge-generating layer of the positively charged multilayer photoreceptor (C-51) exceeds 0.50. As shown in Table 25, the post-exposure potential of the positively charged multilayer photoreceptor (C-51) exceeds +130V. As shown in Tables 16 to 18, the mass ratio of the binder resin (CG) to the charge-generating layer of the positively charged laminated photoreceptors (C-23) to (C-48) and (C-50) is 0.50 or less. As shown in Table 25, the post-exposure potential of the positively charged laminated photoreceptors (C-23) to (C-48) and (C-50) is +130V or less. Therefore, it was determined that by making the mass ratio of the binder resin (specifically, binder resin (SL) or (CG)) to the first photosensitive layer (specifically, a single-layer photosensitive layer or a charge-generating layer) 0.50 or less, both the anti-fogging properties of the photoreceptor and the photosensitivity characteristics of the photoreceptor can be improved.

[0342] In summary, the photosensitive layer of the present invention, including single-layer photosensitive elements (A-1) to (A-70) and positively charged multilayer photosensitive elements (C-1) to (C-75), is well formed and exhibits excellent resistance to fogging. Furthermore, it has been determined that the processing cartridge and image forming apparatus of the present invention, equipped with the aforementioned photosensitive elements, are capable of forming images with less fogging on the recording medium.

Claims

1. An electrophotographic photoreceptor, provided with a conductive base and at least one photosensitive layer, at least one of the photosensitive layers includes a specific photosensitive layer, the specific photosensitive layer is on the most surface side in at least one of the photosensitive layers, the surface side is an outer surface side as the opposite side of the conductive base side, the specific photosensitive layer contains a charge generating agent, a binding resin, an electron transporting agent, and a hole transporting agent, the binding resin includes a polyarylate resin, the polyarylate resin is composed of repeating units represented by formulae (1), (2), (3), and (4), the content ratio of the repeating unit represented by the formula (3) is greater than 0% and less than 50% with respect to the total number of the repeating units represented by the formula (1) and the formula (3), the content ratio of the repeating unit represented by the formula (4) is 35% or more and less than 70% with respect to the total number of the repeating units represented by the formula (2) and the formula (4), the electron transporting agent contains a compound represented by formula (11), (12), (13), (14), (15), (16), or (17), in the formula (1), R 1 and R 2 represents methyl and X is a divalent radical of formula (X1), or R 1 and R 2 represents a hydrogen atom and X is a divalent group represented by formula (X2), in the formula (X1) and the formula (X2), * represents a binding bond, Q in the formula (11) 1 and Q 2 Q in the formula (12) 21 Q 22 Q 23 and Q 24 Q in the formula (13) 31 and Q 32 Q in the formula (14) 41 Q 42 and Q 43 Q in the formula (15) 51 Q 52 Q 53 and Q 54 Q in the formula (16) 61 and Q 62 and Q in the formula (17) 71 Q 72 Q 73 Q 74 Q 75 and Q 76 each independently represents a hydrogen atom, a halogen atom, a cyano group, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C1-C6 alkoxy group, an unsubstituted C6-C14 aryl group, or a C6-C14 aryl group substituted with at least one substituent selected from the group consisting of C1-C6 alkyl groups and halogen atoms, Y in the formula (17) 1 and Y 2 each independently represents an oxygen atom or a sulfur atom.

2. The electrophotographic photoreceptor according to claim 1, characterized in that, the viscosity average molecular weight of the polyarylate resin is 35,000 or more and 80,000 or less.

3. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that, the ratio of the mass of the binding resin with respect to the mass of the specific photosensitive layer is 0.35 or more and 0.50 or less.

4. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that, the scratch resistance depth of the specific photosensitive layer is 0.50 μm or less.

5. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that, the breaking strain of the specific photosensitive layer is 7.5% or more and 21.0% or less.

6. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that, In the formula (1), R 1 and R 2 represents a divalent group of the formula (X1) the polyarylate resin further has a terminal group, the terminal group has a halogen atom.

7. The electrophotographic photoreceptor according to claim 1 or 2, characterized in that, the hole transporting agent contains a compound represented by formula (20), (21), (22), (23), (24), or (25), In the formula (20), R 16 , R 17 , R 18 and R 19 each independently represent a C1-C6 alkyl group, a6, a7, a8and a9each independently represent an integer of 0 or more but 5 or less, In the formula (21), R 21 , R 22 and R 23 each independently represent a C1-C6 alkyl group, R 24 , R 25 and R 26 each independently represent a hydrogen atom, a C1-C6 alkyl group or a C6-C14 aryl group, b1, b2 and b3 each independently represent 0 or 1, b4, b5 and b6 each independently represent an integer of 0 or more but 5 or less, In the formula (22), R 31 , R 32 , and R 33 each independently represent a C1-C6 alkyl group, R 34 represents a C1-C6 alkyl group or a hydrogen atom, d1, d2, and d3 each independently represent an integer of 0 or more but 5 or less, In the formula (23), R 50 and R 51 each independently represent a C1-C6 alkyl group, a C1-C6 alkoxy group or a phenyl group, R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 each independently represent a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group, an unsubstituted phenyl group or a phenyl group having a C1-C6 alkyl substituent, f1and f2each independently represent an integer of 0 or more but 2 or less, f3and f4each independently represent an integer of 0 or more but 5 or less, In the formula (24), R 61 , R 62 , R 63 , R 64 , R 65 , and R 66 each independently represent a C1-C8 alkyl group or a phenyl group, R 67 and R 68 each independently represent a hydrogen atom, a C1-C8 alkyl group or a phenyl group, e1, e2, e3, and e4 each independently represent an integer of 0 or more but 5 or less, e5 and e6 each independently represent an integer of 0 or more but 4 or less, and e7 and e8 each independently represent 0 or 1. In the formula (25), R 41 , R 42 , R 43 , R 44 , R 45 and R 46 each independently represent a C1-C8 alkyl group, a phenyl group or a C1-C8 alkoxy group, g1, g2, g4 and g5 each independently represent an integer of 0 or more but 5 or less, and g3 and g6 each independently represent an integer of 0 or more but 4 or less.

8. A process cartridge, provided with: at least one device selected from the group consisting of a charging device, an exposure device, a developing device, and a transfer device; and the electrophotographic photoreceptor according to any one of claims 1 to 7.

9. An image forming apparatus, provided with: an image bearer; a charging device that charges a surface of the image bearer to a positive polarity; an exposure device that exposes the surface of the charged image bearer to form an electrostatic latent image on the surface of the image bearer; a developing device that supplies a toner to the surface of the image bearer to develop the electrostatic latent image into a toner image; and a transfer device that transfers the toner image from the image bearer to a transfer body, the image bearer is the electrophotographic photoreceptor according to any one of claims 1 to 7.

Images