Polyarylate resin and electrophotographic photoreceptor

Abstract

To provide a polyarylate resin that has excellent solubility in solvent, prevents a failure of a photoreceptor due to a contact with a member when blended in a photosensitive layer, and allows improved wear resistance.SOLUTION: A polyarylate resin has repeat units of formulas (1), (2), (3), and (4). Relative to the total number of the units of formulas (1) and (3), the content of the unit of formula (3) is larger than 0% and smaller than 50%. Relative to the total number of the units of the formulas (2) and (4), the content of the unit of formula (4) is equal to or larger than 35% and smaller than 70%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polyarylate resin and an electrophotographic photoreceptor. [Background technology]

[0002] Electrophotographic photoreceptors are used as image carriers in electrophotographic image forming apparatuses (e.g., printers or multifunction machines). Electrophotographic photoreceptors include a photosensitive layer. As electrophotographic photoreceptors, for example, single-layer electrophotographic photoreceptors and multi-layer electrophotographic photoreceptors are used. The single-layer electrophotographic photoreceptor includes a single photosensitive layer having a charge generation function and a charge transport function. The multi-layer electrophotographic photoreceptor includes a photosensitive layer including a charge generation layer having a charge generation function and a charge transport layer having a charge transport function.

[0003] Patent Document 1 describes an electrophotographic photoreceptor having a surface layer containing a polyarylate resin obtained from a divalent carboxylic acid component and a dihydric phenol component, as shown in the following formula.

[0004] [ka] [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-20514 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the present inventors have found through their studies that the electrophotographic photoreceptor described in Patent Document 1 is insufficient in terms of the solubility of the binder resin in a solvent.The present inventors have also found through their studies that the electrophotographic photoreceptor described in Patent Document 1 is insufficient in terms of abrasion resistance and suppression of defects caused by contact with members of an image forming apparatus.

[0007] The present invention has been made in view of the above problems, and its object is to provide a polyarylate resin that has excellent solubility in a solvent, and when contained in the photosensitive layer of an electrophotographic photosensitive member, suppresses defects of the electrophotographic photosensitive member caused by contact with members and improves the wear resistance of the electrophotographic photosensitive member. Hereinafter, "defects of the electrophotographic photosensitive member caused by contact with members of an image forming apparatus" may be referred to as "member contact defects". Another object of the present invention is to provide an electrophotographic photosensitive member that can form a photosensitive layer well, suppresses member contact defects, and has excellent wear resistance. [Means for solving the problem]

[0008] The polyarylate resin of the present invention has repeating units represented by formulas (1), (2), (3), and (4). A third content, which is the content of the repeating unit represented by formula (3) relative to the total number of repeating units represented by formulas (1) and (3), is greater than 0% and less than 50%. A fourth content, which is the content of the repeating unit represented by formula (4) relative to the total number of repeating units represented by formulas (2) and (4), is 35% or more and less than 70%.

[0009] [ka]

[0010] In the formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1). 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2).

[0011] [ka]

[0012] In the formulae (X1) and (X2), * represents a bond.

[0013] The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating material, a hole transport material, and a binder resin. The binder resin contains the polyarylate resin. Effect of the Invention

[0014] The polyarylate resin of the present invention has excellent solubility in a solvent, and when contained in a photosensitive layer, it can suppress contact problems with members of an electrophotographic photoreceptor and improve wear resistance. The electrophotographic photoreceptor of the present invention can form a good photosensitive layer, can suppress contact problems with members, and has excellent wear resistance. [Brief description of the drawings]

[0015] [Figure 1] FIG. 4 is a partial cross-sectional view of a multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a second embodiment of the present invention. [Diagram 2] FIG. 4 is a partial cross-sectional view of a multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a second embodiment of the present invention. [Diagram 3] FIG. 4 is a partial cross-sectional view of a multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a second embodiment of the present invention. [Diagram 5] FIG. 5 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a second embodiment of the present invention. [Figure 6] FIG. 4 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a second embodiment of the present invention. [Figure 7]1 is a 1H-NMR spectrum of polyarylate resin A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be practiced by making appropriate modifications within the scope of the purpose of the present invention. Note that, although the explanation may be omitted where the explanation overlaps, the gist of the invention is not limited. Hereinafter, the compound and its derivatives may be collectively referred to by adding "system" after the compound name. In addition, when the compound name is followed by "system" to represent the name of the polymer, it means that the repeating unit of the polymer is derived from the compound or its derivative. In addition, "general formula" and "chemical formula" are collectively described as "formula". In the explanation of the formula, "independently" means that the same group or different groups may be represented. Each component described in this specification may be used alone or in combination of two or more types, unless otherwise specified.

[0017] First, the substituents used in this specification will be described. Examples of halogen atoms (halogen groups) include fluorine atoms (fluoro groups), chlorine atoms (chloro groups), bromine atoms (bromo groups), and iodine atoms (iodo groups).

[0018] Unless otherwise specified, the alkyl group having 1 to 8 carbon atoms, the alkyl group having 1 to 6 carbon atoms, and the alkyl group having 1 to 3 carbon atoms are each linear or branched and unsubstituted. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylpropyl group, a 2-ethylpropyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group, a 2,2-dimethylpropyl group, an n-hexyl group, a 1-methylpentyl group, a 2 ... Examples of alkyl groups having 1 to 6 carbon atoms and alkyl groups having 1 to 3 carbon atoms are those groups having the corresponding number of carbon atoms among the groups given as examples of alkyl groups having 1 to 8 carbon atoms.

[0019] Perfluoroalkyl groups having 1 to 10 carbon atoms, perfluoroalkyl groups having 3 to 10 carbon atoms, perfluoroalkyl groups having 5 to 7 carbon atoms, and perfluoroalkyl groups having 6 carbon atoms are linear or branched and unsubstituted, unless otherwise specified. Examples of perfluoroalkyl groups having 1 to 10 carbon atoms include trifluoromethyl, perfluoroethyl, perfluoro-n-propyl, perfluoroisopropyl, perfluoro-n-butyl, perfluoro-sec-butyl, perfluoro-tert-butyl, perfluoro-n-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, perfluoro-n-hexyl, perfluoro-1-methylpentyl, perfluoro-2-methylpent ... Examples of perfluoroalkyl groups include fluoro-3-methylpentyl, perfluoro-4-methylpentyl, 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 groups, linear and branched perfluoroheptyl groups, linear and branched perfluorooctyl groups, linear and branched perfluorononyl groups, and linear and branched perfluorodecyl groups. Examples of perfluoroalkyl groups having 3 to 10 carbon atoms, perfluoroalkyl groups having 5 to 7 carbon atoms, and perfluoroalkyl groups having 6 carbon atoms are groups having the corresponding numbers of carbon atoms among the groups mentioned as examples of perfluoroalkyl groups having 1 to 10 carbon atoms.

[0020] The alkanediyl group having 1 to 6 carbon atoms and the alkanediyl group having 1 to 3 carbon atoms are each linear or branched and unsubstituted, unless otherwise specified. Examples of the alkanediyl group having 1 to 6 carbon atoms include a methanediyl group (methylene group), an ethanediyl group, an n-propanediyl group, an isopropanediyl group, an n-butanediyl group, a sec-butanediyl group, a tert-butanediyl group, an n-pentanediyl group, a 1-methylbutanediyl group, a 2-methylbutanediyl group, a 3-methylbutanediyl group, a 1-ethylpropanediyl group, a 2-ethylpropanediyl group, a 1,1-dimethylpropanediyl group, a 1,2-dimethylpropanediyl group, a 2,2-dimethylpropanediyl group, an n-hexane group, and the like. Examples of the alkanediyl group having 1 to 3 carbon atoms include a diyl group, a 1-methylpentanediyl group, a 2-methylpentanediyl group, a 3-methylpentanediyl group, a 4-methylpentanediyl group, a 1,1-dimethylbutanediyl group, a 1,2-dimethylbutanediyl group, a 1,3-dimethylbutanediyl group, a 2,2-dimethylbutanediyl group, a 2,3-dimethylbutanediyl group, a 3,3-dimethylbutanediyl group, a 1,1,2-trimethylpropanediyl group, a 1,2,2-trimethylpropanediyl group, a 1-ethylbutanediyl group, a 2-ethylbutanediyl group, and a 3-ethylbutanediyl group. Examples of the alkanediyl group having 1 to 3 carbon atoms are groups having the corresponding number of carbon atoms among the groups mentioned as examples of the alkanediyl group having 1 to 6 carbon atoms.

[0021] The alkoxy group having 1 to 8 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the alkoxy group having 1 to 3 carbon atoms are each linear or branched and unsubstituted unless otherwise specified. Examples of the alkoxy group having 1 to 8 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, a 1-methylbutoxy group, a 2-methylbutoxy group, a 3-methylbutoxy group, a 1-ethylpropoxy group, a 2-ethylpropoxy group, a 1,1-dimethylpropoxy group, a 1,2-dimethylpropoxy group, a 2,2-dimethylpropoxy group, an n-hexyloxy group, a 1-methylpentyloxy group, a 2 ... Examples of alkoxy groups having 1 to 6 carbon atoms and alkoxy groups having 1 to 3 carbon atoms are the groups having the corresponding carbon atoms among the groups mentioned as examples of alkoxy groups having 1 to 8 carbon atoms.

[0022] Cycloalkanes having 5 to 7 carbon atoms are unsubstituted unless otherwise specified. Examples of cycloalkanes having 5 to 7 carbon atoms include cyclopentane, cyclohexane, and cycloheptane. The substituents used in this specification have been described above.

[0023] <First embodiment: Polyarylate resin> The first embodiment of the present invention relates to a polyarylate resin. The polyarylate resin of the first embodiment has repeating units represented by formulas (1), (2), (3), and (4). In the polyarylate resin of the first embodiment, the third content is greater than 0% and less than 50%. The third content is the content of the repeating units represented by formula (3) relative to the total number of repeating units represented by formulas (1) and (3). In the polyarylate resin of the first embodiment, the fourth content is greater than 35% and less than 70%. The fourth content is the content of the repeating units represented by formula (4) relative to the total number of repeating units represented by formulas (2) and (4).

[0024] [ka]

[0025] In formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1). 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2).

[0026] [ka]

[0027] In formulae (X1) and (X2), * represents a bond. The bond represented by * in formulae (X1) and (X2) is bonded to the carbon atom to which X in formula (1) is bonded.

[0028] Hereinafter, "repeating units represented by formulas (1), (2), (3), and (4)" may be referred to as "repeating units (1), (2), (3), and (4)," respectively. Also, "a polyarylate resin having repeating units (1), (2), (3), and (4), in which the third content is greater than 0% and less than 50%, and the fourth content is 35% or more and less than 70%" may be referred to as "polyarylate resin (PA)."

[0029] Polyarylate resin (PA) has excellent solubility in solvents. In addition, when polyarylate resin (PA) is contained in a photosensitive layer, it can suppress member contact failure of an electrophotographic photoreceptor (hereinafter, sometimes referred to as a photoreceptor) and improve wear resistance. Examples of member contact failure include a failure in which a dent occurs on the surface of a photoreceptor when a member (e.g., a charging roller) provided in an image forming apparatus is stored in contact with the photoreceptor, and a failure in which a component of the member adheres to the surface of the photoreceptor. Member contact failure tends to occur particularly in a high-temperature and high-humidity environment.

[0030] In formula (1), R 1 and R 2 When R represents a methyl group and X represents a divalent group represented by formula (X1), the repeating unit (1) is a repeating unit represented by formula (1-1) (hereinafter, sometimes referred to as repeating unit (1-1)). 1 and R 2 When represents a hydrogen atom and X represents a divalent group represented by formula (X2), the repeating unit (1) is a repeating unit represented by formula (1-2) (hereinafter, may be referred to as repeating unit (1-2)). The polyarylate resin (PA) may have only one type of repeating unit (1), or may have two types of repeating units (1).

[0031] [ka]

[0032] The content of the repeating unit (1) relative to the total number of the repeating units (1) and (3) is referred to as the first content. The first content is the number N of the repeating units (1) contained in the polyarylate resin (PA). 1 and the number of repeating units (3), N 3 The number of repeating units (1) N 1 Percentage of (i.e., 100 x N 1 / (N 1 +N 3In addition, when the polyarylate resin (PA) has two kinds of repeating units (1), the number N of repeating units (1) corresponds to 1 is the total number of two types of repeating units (1).

[0033] The first content is preferably less than 100%, more preferably 99% or less, even more preferably 90% or less, even more preferably 80% or less, even more preferably 70% or less, even more preferably less than 70%, and particularly preferably 65% ​​or less. The first content is preferably greater than 50%, more preferably 51% or more, and even more preferably 55% or more. In order to suppress contact problems between the photoconductor and the members and improve the wear resistance of the photoconductor when the polyarylate resin (PA) is contained in the photosensitive layer, the first content is preferably greater than 50% and less than 70%, and more preferably greater than 50% and less than 70%.

[0034] The content of the repeating unit (2) relative to the total number of the repeating units (2) and (4) is referred to as the second content. The second content is expressed as the number N of the repeating units (2) contained in the polyarylate resin (PA). 2 and the number N of repeating units (4) 4 The number of repeating units (2) N 2 Percentage of (i.e., 100 x N 2 / (N 2 +N 4 )).

[0035] The second content is preferably 65% ​​or less, more preferably 60% or less. The second content is preferably greater than 30%, more preferably 31% or more, even more preferably 35% or more, even more preferably 40% or more, and particularly preferably 55% or more. In order to suppress contact problems between members of the photoreceptor when the polyarylate resin (PA) is contained in the photosensitive layer, the second content is preferably greater than 30% and 60% or less. In order to improve the wear resistance of the photoreceptor when the polyarylate resin (PA) is contained in the photosensitive layer, the second content is preferably 55% or more and 65% or less.

[0036] As already described, the third content is greater than 0% and less than 50%. The third content is determined by the number N of repeating units (1) contained in the polyarylate resin (PA). 1 and the number of repeating units (3), N 3 The number of repeating units (3) N 3 Percentage of (i.e., 100 x N 3 / (N 1 +N 3 )).

[0037] When the third content is less than 50%, the solubility of the polyarylate resin (PA) in a solvent is improved. When the third content is greater than 0%, i.e., the third content is not 0%, the abrasion resistance of the photoreceptor when the polyarylate resin (PA) is contained in the photosensitive layer can be improved. The third content is preferably 1% or more, more preferably 10% or more, even more preferably 20% or more, even more preferably 30% or more, still more preferably greater than 30%, and particularly preferably 35% or more. In addition, the third content is preferably 49% or less, and more preferably 45% or less.

[0038] In order to suppress contact problems with components of the photoreceptor and improve the wear resistance of the photoreceptor when polyarylate resin (PA) is contained in the photosensitive layer, the third content is preferably 30% or more and less than 50%, and more preferably greater than 30% and less than 50%.

[0039] As already described, the fourth content is 35% or more and less than 70%. The fourth content is determined by the number N of repeating units (2) contained in the polyarylate resin (PA). 2 and the number N of repeating units (4) 4 The number of repeating units (4) N 4 Percentage of (i.e., 100 x N 4 / (N 2 +N 4 )).

[0040] When the fourth content is 35% or more, contact problems with members of the photoreceptor are suppressed when the polyarylate resin (PA) is contained in the photosensitive layer. Furthermore, when the fourth content is 35% or more, the solubility of the polyarylate resin (PA) in a solvent is improved. On the other hand, when the fourth content is less than 70%, the abrasion resistance of the photoreceptor is improved when the polyarylate resin (PA) is contained in the photosensitive layer. The fourth content is preferably 40% or more. Furthermore, the fourth content is preferably 69% or less, more preferably 65% ​​or less, even more preferably 60% or less, and even more preferably 45% or less.

[0041] In order to suppress contact problems with members of a photoreceptor when the photosensitive layer contains polyarylate resin (PA), the fourth content is preferably 40% or more and less than 70%.In order to improve the wear resistance of a photoreceptor when the photosensitive layer contains polyarylate resin (PA), the fourth content is preferably 35% or more and 45% or less.

[0042] The first content, the second content, the third content, and the fourth content are each determined by measuring the amount of the polyarylate resin (PA) using a proton nuclear magnetic resonance spectrometer. 1 The H-NMR spectrum was measured and1 It can be calculated from the ratio of peaks characteristic of each repeating unit in the H-NMR spectrum.

[0043] In order to improve the solubility in a solvent, suppress contact problems with the photoconductor when contained in the photosensitive layer, and improve the wear resistance, it is preferable that the first content is different from the second content and different from the fourth content. For the same reason, it is preferable that the third content is different from the second content and different from the fourth content.

[0044] In order to further suppress contact problems with the photoconductor when contained in the photosensitive layer, R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), and the fourth content is preferably 40% or more and less than 70%.

[0045] In order to achieve a good balance between suppressing contact problems with the photoconductor members and improving wear resistance when contained in the photosensitive layer, R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), and the third content is preferably 30% or more and less than 50%.

[0046] In order to further improve the abrasion resistance of the photoreceptor when contained in the photosensitive layer, R 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2), and the fourth content is preferably 35% or more and 45% or less.

[0047] When contained in the photosensitive layer, in order to suppress contact failure of the photoreceptor and improve wear resistance without impairing the charging characteristics and sensitivity characteristics of the photoreceptor, it is preferable that the polyarylate resin (PA) does not have a repeating unit having a biphenyl structure. Examples of the repeating unit having a biphenyl structure include a repeating unit represented by formula (5). Examples of the repeating unit represented by formula (5) include a repeating unit represented by formula (5-1) and (5-2).

[0048] [ka]

[0049] [ka]

[0050] In order to further improve the abrasion resistance of the photoreceptor when contained in the photosensitive layer, the polyarylate resin (PA) preferably does not have a repeating unit derived from isophthalic acid.

[0051] The polyarylate resin (PA) may have a terminal group. Examples of the terminal group of the polyarylate resin (PA) include terminal groups represented by formulas (T-1) and (T-2). The terminal group represented by formula (T-1) is preferably a terminal group represented by formula (T-DMP) (hereinafter, may be referred to as terminal group (T-DMP)). The terminal group represented by formula (T-2) is preferably a terminal group represented by formula (T-PFH) (hereinafter, may be referred to as terminal group (T-PFH)).

[0052] [ka]

[0053] In formula (T-1), R 11 represents an alkyl group having 1 to 6 carbon atoms or a halogen atom, and p represents an integer of 0 to 5. 11preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and even more preferably represents a methyl group. p preferably represents an integer of 1 to 3, and more preferably represents 2.

[0054] In formula (T-2), R 12 represents an alkanediyl group having 1 to 6 carbon atoms, and Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. 12 Rf preferably represents an alkanediyl group having from 1 to 3 carbon atoms, and more preferably represents a methylene group. Rf preferably represents a perfluoroalkyl group having from 3 to 10 carbon atoms, more preferably a perfluoroalkyl group having from 5 to 7 carbon atoms, and even more preferably a perfluoroalkyl group having 6 carbon atoms.

[0055] The * in the formulae (T-1), (T-2), (T-DMP), and (T-PFH) represents a bond. The bond represented by the * in the formulae (T-1), (T-2), (T-DMP), and (T-PFH) is bonded to a repeating unit derived from a dicarboxylic acid (more specifically, repeating unit (2) or (4)) located at the end of the polyarylate resin (PA).

[0056] In order to further suppress contact problems with members of the photoreceptor and further improve the wear resistance of the photoreceptor when the polyarylate resin (PA) is contained in the photosensitive layer, it is preferable that the polyarylate resin (PA) has a terminal group having a halogen atom. 1 and R 2 It is more preferable that X represents a divalent group represented by the formula (X1), and the polyarylate resin (PA) has a terminal group having a halogen atom.

[0057] An example of a terminal group having a halogen atom is R 11 represents a halogen atom. Another example of an end group having a halogen atom is the end group (T-2).

[0058] Suitable examples of the polyarylate resin (PA) include polyarylate resins (PA-1) to (PA-2) shown in Table 1. The polyarylate resins (PA-1) to (PA-2) each have the repeating units (1) to (4) shown in Table 1. More suitable examples of the polyarylate resin (PA) include polyarylate resins (PA-a) to (PA-d) shown in Table 2. The polyarylate resins (PA-a) to (PA-d) each have the repeating units (1) to (4) shown in Table 2 and the terminal groups shown in Table 2. In Tables 1 and 2, "units (1) to (4)" respectively refer to "repeating units (1) to (4)".

[0059] [Table 1]

[0060] [Table 2]

[0061] In the polyarylate resin (PA), the repeating unit derived from bisphenol (more specifically, the repeating unit (1) or (3)) and the repeating unit derived from dicarboxylic acid (more specifically, the repeating unit (2) or (4)) are adjacent to each other and bonded to each other. That is, the repeating unit (1) may be bonded to the repeating unit (2) or to the repeating unit (4). The repeating unit (3) may be bonded to the repeating unit (2) or to the repeating unit (4). The number of the repeating units derived from bisphenol is approximately the same as the number of the repeating units derived from dicarboxylic acid, and satisfies the formula "the number of repeating units derived from dicarboxylic acid = the number of repeating units derived from bisphenol + 1". The polyarylate resin (PA) may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer.

[0062] The polyarylate resin (PA) may further have repeating units other than the repeating units (1) to (4) as repeating units. However, in order to improve solubility in a solvent, suppress contact problems with the photoreceptor when contained in a photosensitive layer, and improve abrasion resistance, the content of the repeating units (1) to (4) in the total number of repeating units contained in the polyarylate resin (PA) is preferably 80% or more, more preferably 90% or more, even more preferably 95% or more, even more preferably 99% or more, and particularly preferably 100%. That is, it is particularly preferable that the polyarylate resin (PA) has only the repeating units (1) to (4) as repeating units.

[0063] The content of repeating unit (1) relative to the total number of repeating units derived from bisphenol contained in the polyarylate resin (PA) is preferably greater than 50% and less than 100%, more preferably 55% to 90%, even more preferably 60% to 80%, even more preferably 60% to 70%, and even more preferably 60% to 70%. The content of repeating unit (3) relative to the total number of repeating units derived from bisphenol contained in the polyarylate resin (PA) is preferably greater than 0% and less than 50%, more preferably 10% to 45%, even more preferably 20% to 40%, even more preferably 30% to 40%, and even more preferably more than 30% to 40%.

[0064] The content of the repeating unit (2) relative to the total number of repeating units derived from dicarboxylic acid contained in the polyarylate resin (PA) is preferably more than 30% and not more than 65%, more preferably 35% or more and not more than 65%, and even more preferably 40% or more and not more than 60%. The content of the repeating unit (4) relative to the total number of repeating units derived from dicarboxylic acid contained in the polyarylate resin (PA) is preferably 35% or more and less than 70%, more preferably 35% or more and not more than 65%, and even more preferably 40% or more and not more than 60%.

[0065] The viscosity average molecular weight of the polyarylate resin (PA) is preferably 10,000 or more, more preferably 30,000 or more, even more preferably 50,000 or more, and particularly preferably 55,000 or more. When the viscosity average molecular weight of the polyarylate resin (PA) is 10,000 or more, the abrasion resistance of the photoreceptor is improved when the polyarylate resin (PA) is contained in the photosensitive layer of the photoreceptor. On the other hand, the viscosity average molecular weight of the polyarylate 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 the polyarylate resin (PA) is 80,000 or less, the solubility of the polyarylate resin (PA) in a solvent is improved. The viscosity average molecular weight of the polyarylate resin (PA) is measured according to JIS (Japanese Industrial Standards) K7252-1:2016.

[0066] Next, the method for producing polyarylate resin (PA) will be described. For example, the method for producing polyarylate resin (PA) includes a method of polycondensing bisphenol for forming a repeating unit derived from bisphenol and dicarboxylic acid for forming a repeating unit derived from dicarboxylic acid. For polycondensation, a known synthesis method (for example, solution polymerization, melt polymerization, or interfacial polymerization) can be adopted.

[0067] Examples of bisphenols for constituting the repeating units derived from bisphenols include compounds represented by formulae (BP-1) and (BP-3) (hereinafter, these may be referred to as compounds (BP-1) and (BP-3), respectively). Examples of dicarboxylic acids for constituting the repeating units derived from dicarboxylic acids include compounds represented by formulae (DC-2) and (DC-4) (hereinafter, these may be referred to as compounds (DC-2) and (DC-4), respectively). R in formula (BP-1) 1 , R 2 , and X is R in formula (1). 1 , R 2 , and X.

[0068] [ka]

[0069] In the production of polyarylate resin (PA), the first content can be adjusted by changing the amount of compound (BP-1) added (unit: mole) relative to the total amount of compounds (BP-1) and (BP-3) added (unit: mole). The second content can be adjusted by changing the amount of compound (DC-2) added (unit: mole) relative to the total amount of compounds (DC-2) and (DC-4) added (unit: mole). The third content can be adjusted by changing the amount of compound (BP-3) added (unit: mole) relative to the total amount of compounds (BP-1) and (BP-3) added (unit: mole). The fourth content can be adjusted by changing the amount of compound (DC-4) added (unit: mole) relative to the total amount of compounds (DC-2) and (DC-4) added (unit: mole).

[0070] Bisphenols may be derivatized to aromatic diacetates for use. Dicarboxylic acids may be derivatized for use. Examples of dicarboxylic acid derivatives include dicarboxylic acid dichlorides, dicarboxylic acid dimethyl esters, dicarboxylic acid diethyl esters, and dicarboxylic acid anhydrides. Dicarboxylic acid dichlorides are compounds in which two "-C(=O)-OH" groups of a dicarboxylic acid are each replaced with a "-C(=O)-Cl" group.

[0071] In the polycondensation of bisphenol and dicarboxylic acid, a terminal terminator may be added. Examples of the terminal terminator include 2,6-dimethylphenol and 1H,1H-perfluoro-1-heptanol. By using 2,6-dimethylphenol as the terminal terminator, a terminal group (T-DMP) can be formed. By using 1H,1H-perfluoro-1-heptanol as the terminal terminator, a terminal group (T-PFH) can be formed.

[0072] In the polycondensation of bisphenol and dicarboxylic acid, a base and / or a catalyst may be added. An example of the base is sodium hydroxide. An example of the catalyst is benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salt, triethylamine, and trimethylamine.

[0073] <Second embodiment: photoreceptor> The second embodiment of the present invention relates to a photoreceptor. The photoreceptor of the second embodiment includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transport agent, and a binder resin. The photoreceptor is, for example, a single-layer electrophotographic photoreceptor (hereinafter, sometimes referred to as a single-layer photoreceptor) or a multi-layer electrophotographic photoreceptor (hereinafter, sometimes referred to as a multi-layer photoreceptor).

[0074] (Layered photoconductor) Hereinafter, a multi-layer photoreceptor 1, which is an example of a photoreceptor, will be described with reference to Figures 1 to 3. Each of Figures 1 to 3 shows a partial cross-sectional view of the multi-layer photoreceptor 1.

[0075] As shown in Fig. 1, the laminated photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 includes a charge generating layer 3a and a charge transport layer 3b. That is, the laminated photoreceptor 1 includes, as the photosensitive layer 3, a charge generating layer 3a and a charge transport layer 3b. The charge generating layer 3a is, for example, a single layer. The charge transport layer 3b is, for example, a single layer.

[0076] As shown in Fig. 1, a charge generating layer 3a may be provided on a conductive substrate 2, and a charge transporting layer 3b may be provided on the charge generating layer 3a. Alternatively, as shown in Fig. 2, a charge transporting layer 3b may be provided on a conductive substrate 2, and a charge generating layer 3a may be provided on the charge transporting layer 3b.

[0077] As shown in FIG. 3, the laminated photoreceptor 1 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2 and the photosensitive layer 3. The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. As shown in FIGS. 1 and 2, in the laminated photoreceptor 1, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, as shown in FIG. 3, in the laminated photoreceptor 1, the photosensitive layer 3 may be provided on the conductive substrate 2 via the intermediate layer 4. When the laminated photoreceptor 1 includes the intermediate layer 4, as shown in FIG. 3, the intermediate layer 4 may be provided on the conductive substrate 2, the charge generating layer 3a may be provided on the intermediate layer 4, and the charge transport layer 3b may be provided on the charge generating layer 3a. Alternatively, the intermediate layer 4 may be provided on the conductive substrate 2, the charge transport layer 3b may be provided on the intermediate layer 4, and the charge generating layer 3a may be provided on the charge transport layer 3b.

[0078] The laminated photoreceptor 1 may further include a protective layer 5 (see FIG. 6) in addition to the conductive substrate 2 and the photosensitive layer 3. The protective layer 5 is provided on the photosensitive layer 3. As shown in FIGS. 1 to 3, the photosensitive layer 3 (e.g., the charge transport layer 3b or the charge generation layer 3a) may be provided as the outermost layer of the laminated photoreceptor 1. Alternatively, the protective layer 5 may be provided as the outermost layer of the laminated photoreceptor 1.

[0079] 1, the photosensitive layer 3 (preferably, the charge transport layer 3b) is preferably provided as the outermost layer of the laminated photoreceptor 1. It is more preferable that the charge transport layer 3b is a single layer and is provided as the outermost layer of the laminated photoreceptor 1. By providing the charge transport layer 3b containing a polyarylate resin (PA) as the outermost layer, the wear resistance of the laminated photoreceptor 1 is further improved.

[0080] The charge generating layer 3a contains a charge generating agent. The charge generating layer 3a may contain a base resin as necessary. The charge generating layer 3a may contain an additive as necessary. The thickness of the charge generating layer 3a is not particularly limited, but is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 3 μm or less.

[0081] The charge transport layer 3b contains a hole transport agent and a binder resin. The charge transport layer 3b may contain additives as necessary. The thickness of the charge transport layer 3b is not particularly limited, but is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less. The multi-layer photoreceptor 1 has been described above with reference to FIGS. 1 to 3.

[0082] (single-layer photoreceptor) Next, a single-layer type photoreceptor 10, which is an example of a photoreceptor, will be described with reference to Figures 4 to 6. Figures 4 to 6 each show a partial cross-sectional view of the single-layer type photoreceptor 10.

[0083] 4, the single-layer photoreceptor 10 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 included in the single-layer photoreceptor 10 is a single layer. Hereinafter, the "single-layer photosensitive layer 3" may be referred to as a "single-layer photosensitive layer 3c."

[0084] As shown in Fig. 5, the single-layer photoreceptor 10 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2 and the single-layer photosensitive layer 3c. The intermediate layer 4 is provided between the conductive substrate 2 and the single-layer photosensitive layer 3c. As shown in Fig. 4, the single-layer photosensitive layer 3c may be provided directly on the conductive substrate 2. Alternatively, as shown in Fig. 5, the single-layer photosensitive layer 3c may be provided on the conductive substrate 2 via the intermediate layer 4.

[0085] As shown in Fig. 6, the single-layer photoreceptor 10 may further include a protective layer 5 in addition to the conductive substrate 2 and the single-layer photosensitive layer 3c. The protective layer 5 is provided on the single-layer photosensitive layer 3c. As shown in Figs. 4 and 5, the single-layer photosensitive layer 3c may be provided as the outermost layer of the single-layer photoreceptor 10. Alternatively, as shown in Fig. 6, the protective layer 5 may be provided as the outermost layer of the single-layer photoreceptor 10.

[0086] 4 and 5, the photosensitive layer 3 (more specifically, the single-layer photosensitive layer 3c) is preferably provided as the outermost layer of the single-layer photoreceptor 10. By providing the single-layer photosensitive layer 3c containing a polyarylate resin (PA) as the outermost layer, the wear resistance of the single-layer photoreceptor 10 is further improved.

[0087] The single-layered photosensitive layer 3c contains a charge generating material, a hole transporting material, and a binder resin. The single-layered photosensitive layer 3c may further contain an electron transporting material as required. The single-layered photosensitive layer 3c may contain an additive as required.

[0088] The thickness of the single-layer photosensitive layer 3c is not particularly limited, but is preferably from 5 μm to 100 μm, and more preferably from 10 μm to 50 μm. The single-layer photoreceptor 10 has been described above with reference to FIGS.

[0089] (binder resin) The binder resin contains the polyarylate resin (PA) described in the first embodiment. By using the polyarylate resin (PA) which has excellent solubility in a solvent, the photosensitive layer of the photoreceptor can be formed well. In addition, by the photosensitive layer containing the polyarylate resin (PA), contact problems with the photoreceptor members are suppressed and wear resistance is improved.

[0090] The photosensitive layer may contain only one type of polyarylate resin (PA) as a binder resin, or may contain two or more types of polyarylate resin (PA). The photosensitive layer may contain only polyarylate resin (PA) as a binder resin, or may further contain binder resins other than polyarylate resin (PA) (hereinafter, may be referred to as other binder resins). Examples of other binder resins include thermoplastic resins (more specifically, polyarylate resins other than polyarylate resins (PA), polycarbonate resins, styrene-based resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-vinyl acetate copolymers, polyester resins, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyvinyl acetal resins, and polyether resins), thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, and other crosslinkable thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic acid-based resins, and urethane-acrylic acid-based copolymers).

[0091] (Hole transport agent) Examples of the hole transport agent include triphenylamine derivatives, diamine derivatives (e.g., N,N,N',N'-tetraphenylbenzidine derivatives, N,N,N',N'-tetraphenylphenylenediamine derivatives, N,N,N',N'-tetraphenylnaphthylenediamine derivatives, N,N,N',N'-tetraphenylphenanthrylenediamine derivatives, and di(aminophenylethenyl)benzene derivatives), oxadiazole compounds (e.g., 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazo Examples of the hole transport agent include 9-(4-diethylaminostyryl)anthracene, ...

[0092] Suitable examples of the hole transport agent include compounds represented by formulas (19), (20), (21), and (22) (hereinafter, these may be referred to as hole transport agents (19), (20), (21), and (22), respectively). When the photosensitive layer contains the hole transport agent (19), (20), (21), or (22) together with the polyarylate resin (PA), the photosensitive layer can be formed more satisfactorily, contact problems between the photoreceptor members can be further suppressed, and wear resistance can be further improved.

[0093] [ka]

[0094] [ka]

[0095] In formula (19), R 16 , R17 , R 18 , and R 19 each independently represents an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; a6, a7, a8, and a9 each independently represent an integer of 0 to 5.

[0096] In formula (19), when a6 represents an integer of 2 or more and 5 or less, a plurality of R 16 may represent the same group or different groups. When a7 represents an integer of 2 or more and 5 or less, multiple R 17 may represent the same group or different groups. When a8 represents an integer of 2 or more and 5 or less, multiple R 18 may represent the same group or different groups. When a9 represents an integer of 2 or more and 5 or less, multiple R 19 may represent the same group or different groups.

[0097] In formula (19), R 16 , R 17 , R 18 , and R 19 each independently preferably represents an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group; a6, a7, a8, and a9 each independently preferably represent an integer of 1 to 3, more preferably 1.

[0098] In formula (20), R 21 and R 22 R each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. 23 , R 24 , R 25 , R 26 , R 27 , R 28 , and R 29 R each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a phenyl group which may be substituted with an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms. 25 , R26 , R 27 , R 28 , and R 29 adjacent two of a1 and a2 may be bonded to form a ring. a1 and a2 each independently represent an integer of 0 or more and 5 or less.

[0099] In formula (20), when a1 represents an integer of 2 or more and 5 or less, a plurality of R 21 may represent the same group or different groups. When a2 represents an integer of 2 to 5, multiple R 22 may represent the same group or different groups.

[0100] In formula (20), R 21 and R 22 each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and further preferably represents a methyl group.

[0101] In formula (20), R 23 and R 24 R preferably each independently represents a phenyl group which may be substituted with an alkyl group having 1 to 8 carbon atoms, or a hydrogen atom. 23 and R 24 The phenyl group which may be substituted with an alkyl group having 1 to 8 carbon atoms, represented by the formula (I), is preferably a phenyl group substituted with an alkyl group having 1 to 8 carbon atoms, more preferably a phenyl group substituted with an alkyl group having 1 to 3 carbon atoms, further preferably a methylphenyl group, and particularly preferably a 4-methylphenyl group.

[0102] In formula (20), R 25 ~R 29 R preferably each independently represents a hydrogen atom or an alkoxy group having 1 to 8 carbon atoms. 25 ~R 29 The alkoxy group having 1 to 8 carbon atoms represented by R is preferably an alkoxy group having 1 to 3 carbon atoms, more preferably a methoxy group or an ethoxy group. 25 ~R 29When two adjacent ones of R are bonded to each other to form a ring, this ring and R 25 ~R 29 is condensed with the phenyl group to which it is bonded to form a bicyclic fused ring group. In this case, the condensation site between the ring and the phenyl group may contain a double bond. 25 ~R 29 When adjacent two of these are bonded to form a ring, such a ring is preferably a cycloalkane having 5 to 7 carbon atoms, and more preferably cyclohexane.

[0103] In formula (20), it is preferable that a1 and a2 each independently represent 0 or 1.

[0104] In formula (21), R 31 , R 32 , R 33 , R 34 , R 35 , and R 36 R each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group. 37 and R 38 each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. b1, b2, b3, and b4 each independently represent an integer of 0 to 5. b5 and b6 each independently represent an integer of 0 to 4. d and e each independently represent 0 or 1.

[0105] In formula (21), when b1 represents an integer of 2 or more and 5 or less, a plurality of R 31 may represent the same group or different groups. When b2 represents an integer of 2 to 5, multiple R 32 may represent the same group or different groups. When b3 represents an integer of 2 or more and 5 or less, multiple R 33 may represent the same group or different groups. When b4 represents an integer of 2 or more and 5 or less, 34 may represent the same group or different groups. When b5 represents an integer of 2 to 4, multiple R 35may represent the same group or different groups. When b6 represents an integer of 2 or more and 4 or less, 36 may represent the same group or different groups.

[0106] In formula (21), R 31 ~R 36 R each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and further preferably represents a methyl group or an ethyl group. 37 and R 38 preferably represents a hydrogen atom. b1, b2, b3, and b4 each independently preferably represent an integer of 0 or more and 2 or less. b5 and b6 preferably represent 0.

[0107] In formula (22), R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. f1, f2, f4, and f5 each independently represent an integer of 0 to 5. f3 and f6 each independently represent an integer of 0 to 4.

[0108] In formula (22), when f1 represents an integer of 2 to 5, a plurality of R 41 may represent the same group or different groups. When f2 represents an integer of 2 to 5, multiple R 42 may represent the same group or different groups. When f4 represents an integer of 2 to 5, multiple R 44 may represent the same group or different groups. When f5 represents an integer of 2 to 5, multiple R 45 may represent the same group or different groups. When f3 represents an integer of 2 to 4, multiple R 43 may represent the same group or different groups. When f6 represents an integer of 2 to 4, multiple R46 may represent the same group or different groups.

[0109] In formula (22), R 41 ~R 46 Each of f1, f2, f4, and f5 independently preferably represents an integer of 0 to 2. Each of f3 and f6 preferably represents 0. R 44 , R 45 , and R 46 The diphenylaminophenylethenyl group having R 41 , R 42 , and R 43 For a diphenylaminophenylethenyl group having the formula:

[0110] More suitable examples of the hole transport agent include compounds represented by formulas (HTM-1) to (HTM-7) (hereinafter, these may be referred to as hole transport agents (HTM-1) to (HTM-7), respectively).

[0111] [ka]

[0112] [ka]

[0113] [ka]

[0114] When the photoreceptor is a multi-layer photoreceptor, the content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 20 parts by mass or more and 100 parts by mass or less, and even more preferably 40 parts by mass or more and 60 parts by mass or less, relative to 100 parts by mass of the binder resin. When the photoreceptor is a single-layer photoreceptor, the content of the hole transport agent is preferably 50 parts by mass or more and 200 parts by mass or less, more preferably 50 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0115] (Charge generating material) Examples of the charge generating agent include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azulenium pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon), pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments. The photosensitive layer may contain only one type of charge generating agent, or may contain two or more types of charge generating agents.

[0116] Phthalocyanine pigments are pigments having a phthalocyanine structure. Examples of phthalocyanine pigments include metal-free phthalocyanine and metal phthalocyanine. Examples of metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Metal-free phthalocyanine is represented by formula (CGM-1). Titanyl phthalocyanine is represented by formula (CGM-2).

[0117] [ka]

[0118] [ka]

[0119] The phthalocyanine pigment may be crystalline or non-crystalline. Examples of the metal-free phthalocyanine crystals include X-type crystals of metal-free phthalocyanine (hereinafter, may be referred to as X-type metal-free phthalocyanine). Examples of the titanyl phthalocyanine crystals include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter, may be referred to as α-type, β-type, and Y-type titanyl phthalocyanine, respectively).

[0120] For example, in a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoreceptor having sensitivity in a wavelength region of 700 nm or more. As the charge generating agent, a phthalocyanine pigment is preferable because it has a high quantum yield in a wavelength region of 700 nm or more, a metal-free phthalocyanine or titanyl phthalocyanine is more preferable, titanyl phthalocyanine is further preferable, and Y-type titanyl phthalocyanine is particularly preferable.

[0121] The Y-type titanyl phthalocyanine has a main peak at, for example, 27.2° of Bragg angle (2θ±0.2°) in the CuKα characteristic X-ray diffraction spectrum. The main peak in the CuKα characteristic X-ray diffraction spectrum is the peak having the first or second largest intensity in the range of Bragg angle (2θ±0.2°) from 3° to 40°. The Y-type titanyl phthalocyanine does not have a peak at 26.2° in the CuKα characteristic X-ray diffraction spectrum.

[0122] The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, a sample (titanyl phthalocyanine) is loaded into a sample holder of an X-ray diffractometer (for example, Rigaku Corporation's "RINT (registered trademark) 1100"), and the X-ray diffraction spectrum is measured under the conditions of an X-ray tube Cu, a tube voltage of 40 kV, a tube current of 30 mA, and a wavelength of CuKα characteristic X-ray of 1.542 Å. The measurement range (2θ) is, for example, 3° to 40° (start angle 3°, stop angle 40°), and the scanning speed is, for example, 10° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0123] When the photoreceptor is a laminated type photoreceptor, the content of the charge generating agent is preferably 10 parts by mass or more and 300 parts by mass or less, and more preferably 100 parts by mass or more and 200 parts by mass or less, relative to 100 parts by mass of the base resin. When the photoreceptor is a single-layer type photoreceptor, the content of the charge generating agent is preferably 0.1 parts by mass or more and 50 parts by mass or less, and more preferably 0.5 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0124] (Base resin) Examples of the base resin contained in the charge generating layer are the same as the examples of the other binder resins contained in the charge transport layer.

[0125] (Additives) Examples of additives include ultraviolet absorbers, antioxidants, radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, donors, surfactants, plasticizers, sensitizers, electron acceptor compounds, and leveling agents. As the antioxidant, a hindered phenol antioxidant is preferred, and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) is more preferred.

[0126] (Material Combination) In order to form a good photosensitive layer, suppress contact problems with the photoreceptor members, and improve wear resistance, it is preferable that the combination of the hole transport agent and the binder resin is one of combinations No. a-1 to a-14 and b-1 to b-28 shown in Table 3, and combinations No. c-1 to c-49 shown in Table 4. For the same reason, it is preferable that the combination of the hole transport agent and the binder resin is one of combinations No. a-1 to a-14 and b-1 to b-28 shown in Table 3, and combinations No. c-1 to c-49 shown in Table 4, and that the charge generating agent is Y-type titanyl phthalocyanine. For the same reason, the combinations of the hole transport agent and the binder resin are combinations No. a-1 to a-14 and b-1 to b-28 shown in Table 3, and combinations No. c-1 to c-49 shown in Table 4, and the additive contained in the charge transport layer is more preferably a hindered phenol antioxidant (more preferably, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)). In Tables 3 and 4, "No." indicates "combination No.", "HTM" indicates "hole transport agent", and "resin" indicates "polyarylate resin" which is the binder resin. Polyarylate resins A to G in Table 4 will be described in detail in the Examples.

[0127] [Table 3]

[0128] [Table 4]

[0129] (Conductive substrate) The conductive substrate is not particularly limited, and at least the surface portion may be made of a material having electrical conductivity. An example of the conductive substrate is a conductive substrate made of a material having electrical conductivity. Another example of the conductive substrate is a conductive substrate coated with a material having electrical conductivity. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. Among these conductive materials, aluminum and aluminum alloys are preferred because they have good charge transfer from the photosensitive layer to the conductive substrate.

[0130] The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus. The shape of the conductive substrate may be, for example, a sheet or a drum. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

[0131] (Middle class) The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used in the intermediate layer. The presence of the intermediate layer makes it possible to maintain an insulating state sufficient to suppress leakage, while facilitating the flow of current generated when the photoreceptor is exposed to light, thereby suppressing an increase in resistance.

[0132] Inorganic particles include, for example, particles of metals (e.g., aluminum, iron, and copper), particles of metal oxides (e.g., titanium oxide, alumina, zirconium oxide, tin oxide, and zinc oxide), and particles of non-metal oxides (e.g., silica).

[0133] Examples of the resin for the intermediate layer are the same as the examples of other binder resins already described. In order to form the intermediate layer and the photosensitive layer well, it is preferable that the resin for the intermediate layer is different from the binder resin contained in the photosensitive layer. The intermediate layer may contain an additive. Examples of the additive contained in the intermediate layer are the same as the examples of the additive contained in the photosensitive layer.

[0134] (Photoreceptor manufacturing method) As a method for producing a photoreceptor, an example of a method for producing a multi-layer type photoreceptor and an example of a method for producing a single-layer type photoreceptor will be described.

[0135] The method for manufacturing a laminated photoreceptor includes, for example, a charge generation layer forming step and a charge transport layer forming step. In the charge generation layer forming step, first, a coating liquid for forming a charge generation layer (hereinafter, sometimes referred to as a charge generation layer coating liquid) is prepared. The charge generation layer coating liquid is applied onto a conductive substrate. Then, at least a part of the solvent contained in the applied charge generation layer coating liquid is removed to form a charge generation layer. The charge generation layer coating liquid contains, for example, a charge generation agent, a base resin, and a solvent. Such a charge generation layer coating liquid is prepared by dissolving or dispersing the charge generation agent and the base resin in a solvent. The charge generation layer coating liquid may further contain an additive as necessary.

[0136] In the charge transport layer forming step, first, a coating liquid for forming a charge transport layer (hereinafter, sometimes referred to as a coating liquid for a charge transport layer) is prepared. The coating liquid for a charge transport layer is applied onto the charge generating layer. Then, at least a part of the solvent contained in the applied coating liquid for a charge transport layer is removed to form a charge transport layer. The coating liquid for a charge transport layer contains a hole transport agent, a binder resin, and a solvent. The coating liquid for a charge transport layer can be prepared by dissolving or dispersing a hole transport agent and a binder resin in a solvent. The coating liquid for a charge transport layer may further contain an additive, if necessary.

[0137] The method for producing a single-layer photoreceptor includes, for example, a single-layer photosensitive layer forming step. In the single-layer photosensitive layer forming step, a coating liquid for forming a single-layer photosensitive layer (hereinafter, sometimes referred to as a coating liquid for a single-layer photosensitive layer) is prepared. The coating liquid for a single-layer photosensitive layer is applied onto a conductive substrate. Then, at least a part of the solvent contained in the applied coating liquid for a single-layer photosensitive layer is removed to form a single-layer photosensitive layer. The coating liquid for a single-layer photosensitive layer contains, for example, a charge generating agent, a hole transport agent, a binder resin, and a solvent. The coating liquid for a single-layer photosensitive layer is prepared by dissolving or dispersing a charge generating agent, a hole transport agent, and a binder resin in a solvent. The coating liquid for a single-layer photosensitive layer may further contain one or both of an electron transport agent and an additive, if necessary.

[0138] The solvent contained in the coating liquid for the single-layer photosensitive layer, the coating liquid for the charge generating layer, and the coating liquid for the charge transport layer (hereinafter, these may be collectively referred to as coating liquids) is not particularly limited as long as it can dissolve or disperse each component contained in the coating liquid. Examples of the solvent include alcohol (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbons (more specifically, n-hexane, octane, cyclohexane, etc.), aromatic hydrocarbons (more specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, etc.), ethers (more specifically, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc.), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), esters (more specifically, ethyl acetate, methyl acetate, etc.), dimethylformaldehyde, dimethylformamide, and dimethylsulfoxide.

[0139] The solvent contained in the coating liquid for the charge transport layer is preferably different from the solvent contained in the coating liquid for the charge generation layer, because when the coating liquid for the charge transport layer is applied onto the charge generation layer, it is preferable that the charge generation layer is not dissolved in the solvent of the coating liquid for the charge transport layer.

[0140] The coating liquid is prepared by mixing the respective components and dispersing them in a solvent. For example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used for mixing or dispersing.

[0141] The method for applying the coating liquid is not particularly limited as long as the coating liquid can be uniformly applied, and examples of the coating method include dip coating, spray coating, spin coating, and bar coating.

[0142] Methods for removing at least a part of the solvent contained in the coating liquid include, for example, heating, reducing pressure, or a combination of heating and reducing pressure. More specifically, a method for heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer can be mentioned. The temperature for heat treatment is, for example, 40°C or higher and 150°C or lower. The time for heat treatment is, for example, 3 minutes or higher and 120 minutes or lower.

[0143] The method for producing a photoreceptor may further include one or both of a step of forming an intermediate layer and a step of forming a protective layer, if necessary. The step of forming an intermediate layer and the step of forming a protective layer can be appropriately selected from known methods. EXAMPLES

[0144] The present invention will be described in more detail below using examples, but the present invention is not limited to the scope of the examples.

[0145] <Preparation of polyarylate resins A to T> Polyarylate resins A to G according to the examples and polyarylate resins H to T according to the comparative examples were synthesized by the methods described below. The compositions of polyarylate resins A to T are shown in Table 5 below. Polyarylate resin Q had the same repeating units in the same ratio as the resin used in Example 4 of Patent Document 1 (JP Patent Publication 10-20514 A).

[0146] [Table 5]

[0147] In Table 5, "BisCZ", "BisB", "BisC", "BisZ", "BisCE", "DHPE", "DPEC", "TPC", and "IPC" respectively represent compounds represented by the following formulas (BisCZ), (BisB), (BisC), (BisZ), (BisCE), (DHPE), (DPEC), (TPC), and (IPC) (hereinafter, each may be referred to as compounds (BisCZ), (BisB), (BisC), (BisZ), (BisCE), (DHPE), (DPEC), (TPC), and (IPC)).

[0148] [ka]

[0149] Furthermore, the meanings of the terms in Table 5 are as follows: Monomer: Monomer used in the synthesis of polyarylate resin Forming unit: Repeating unit formed from the corresponding monomer Resin: Polyarylate resin Bisphenol addition rate: The percentage (unit: %) of the amount of the corresponding bisphenol monomer (unit: mole) to the total amount (unit: mole) of bisphenol monomer added in the synthesis of polyarylate resin Dicarboxylic acid addition rate: The percentage (unit: %) of the amount (unit: mole) of the corresponding dicarboxylic acid monomer to the total amount (unit: mole) of dicarboxylic acid monomer added in the synthesis of polyarylate resin Molecular weight: viscosity average molecular weight Unit: Repeating unit Unit (BisC): A repeating unit derived from the compound (BisC) Unit (BisZ): A repeating unit derived from the compound (BisZ). Unit (BisCE): A repeating unit derived from the compound (BisCE) Unit (IPC): Repeating unit derived from compound (IPC) DMP: 2,6-dimethylphenol PFH: 1H,1H-perfluoro-1-heptanol -: No corresponding monomer is used Unmeasurable: Polyarylate resin was not dissolved in the solvent used for viscosity and molecular weight measurement, and the viscosity average molecular weight could not be measured.

[0150] (Synthesis of polyarylate resin A) A three-neck flask equipped with a thermometer, a three-way cock, and a dropping funnel was used as the reaction vessel. The monomer compound (BisCZ) (32.8 mmol), the monomer compound (DHPE) (8.2 mmol), the end terminator 2,6-dimethylphenol (0.413 mmol), sodium hydroxide (98 mmol), and benzyltributylammonium chloride (0.384 mmol) were placed in the reaction vessel. The air in the reaction vessel was replaced with argon gas. 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.

[0151] Next, the dicarboxylic acid dichloride (20.8 mmol) of the monomer compound (DPEC) and the dicarboxylic acid dichloride (11.2 mmol) of the monomer compound (TPC) were dissolved in chloroform (150 mL), thereby obtaining a chloroform solution SB.

[0152] The chloroform solution SB was slowly dropped into the alkaline aqueous solution SA over 110 minutes using a dropping funnel. The contents of the reaction vessel were stirred for 4 hours while controlling the temperature (liquid temperature) of the contents of the reaction vessel to 15±5°C to allow the polymerization reaction to proceed. The upper layer (aqueous layer) of the contents of the reaction vessel was removed using a decant to obtain an organic layer. Next, ion-exchanged water (400 mL) was added to the Erlenmeyer flask. The obtained organic layer was further 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°C) for 30 minutes. The upper layer (aqueous layer) of the contents of the Erlenmeyer flask was removed using a decant to obtain an organic layer. The obtained organic layer was washed with ion-exchanged water (1 L) using a separating funnel. Washing with ion-exchanged water was repeated five times to obtain a water-washed organic layer. Next, the water-washed organic layer was filtered to obtain a filtrate. The obtained filtrate was slowly dropped into methanol (1 L) to obtain a precipitate. The precipitate was collected by filtration and then vacuum-dried at 70° C. for 12 hours. As a result, polyarylate resin A was obtained.

[0153] (Synthesis of polyarylate resins B to T) Each of the polyarylate resins B to T was synthesized in the same manner as the synthesis of the polyarylate resin A, except that the monomers shown in Table 5 were used at the addition rates shown in Table 5. The amount of each bisphenol monomer added was set so that the total amount of the bisphenol monomers was 41.0 millimoles and the bisphenol addition rate shown in Table 5 was achieved. For example, in the synthesis of the polyarylate resin E, the amount of the compound (BisB) added was 32.8 millimoles (=41.0×80 / 100), and the amount of the compound (DHPE) added was 8.2 millimoles (=41.0×20 / 100). The amount of each dicarboxylic acid monomer added was set so that the total amount of the dicarboxylic acid monomers was 32.0 millimoles and the dicarboxylic acid addition rate shown in Table 5 was achieved. For example, in the synthesis of polyarylate resin E, the amount of compound (DPEC) added was 16.0 mmol (=32.0×50 / 100), and the amount of compound (TPC) added was 16.0 mmol (=32.0×50 / 100).

[0154] The obtained polyarylate resins A to T were analyzed using a proton nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., 600 MHz). 1 H-NMR spectrum was measured. Deuterated chloroform was used as the solvent. Tetramethylsilane (TMS) was used as the internal standard sample. As a representative example of polyarylate resins A to T, polyarylate resin A was 1 The H-NMR spectrum is shown in FIG. 1 From the chemical shifts read from the H-NMR spectrum, it was confirmed that polyarylate resin A was obtained. By using the same method for polyarylate resins B to T, it was confirmed that polyarylate resins B to T were obtained.

[0155] <Measurement of Viscosity Average Molecular Weight> The viscosity average molecular weight of the polyarylate resin was measured according to JIS (Japanese Industrial Standards) K7252-1: 2016. The measured viscosity average molecular weight is shown in Table 5.

[0156] <Manufacture of multi-layer photoreceptor> (Manufacture of multi-layer photoreceptor (A-1)) First, an intermediate layer was formed. Surface-treated titanium oxide ("Prototype SMT-A" manufactured by Teika Co., Ltd., number average primary particle size 10 nm) was prepared. SMT-A was prepared by surface-treating titanium oxide with alumina and silica, and further surface-treating the surface-treated titanium oxide with methylhydrogenpolysiloxane while wet-dispersing it. Next, 2 parts by mass of SMT-A, 1 part by mass of polyamide resin ("Amilan (registered trademark) CM8000" manufactured by Toray Industries, Inc., tetrapolymer polyamide resin of polyamide 6, polyamide 12, polyamide 66 and polyamide 610), 10 parts by mass of methanol, 1 part by mass of butanol and 1 part by mass of toluene were mixed for 5 hours using a bead mill to obtain an intermediate layer coating liquid. The intermediate layer coating liquid was filtered using a filter with an opening of 5 μm. Then, the intermediate layer coating liquid was applied to the surface of the conductive substrate by a dip coating method. As the conductive substrate, an aluminum drum-shaped support was used. Subsequently, the applied intermediate layer coating liquid was dried at 130° C. for 30 minutes to form an intermediate layer (film thickness: 2 μm) on the conductive substrate.

[0157] Next, a charge generation layer was formed. In detail, 1.5 parts by mass of Y-type titanyl phthalocyanine as a charge generation agent, 1.0 parts by mass of polyvinyl acetal resin ("S-LEC BX-5" manufactured by Sekisui Chemical Co., Ltd.) as a base resin, 40.0 parts by mass of propylene glycol monomethyl ether, and 40.0 parts by mass of tetrahydrofuran were mixed for 2 hours using a bead mill to obtain a coating liquid for a charge generation layer. The coating liquid for a charge generation layer was filtered using a filter with an opening of 3 μm. The obtained filtrate was applied onto the intermediate layer by a dip coating method and dried at 50° C. for 5 minutes. In this way, a charge generation layer (film thickness: 0.3 μm) was formed on the intermediate layer.

[0158] Next, a charge transport layer was formed. In detail, 50 parts by mass of a hole transport agent (HTM-1), 100 parts by mass of polyarylate resin A, which is a binder resin, 2 parts by mass of a hindered phenol antioxidant (BASF's "Irganox (registered trademark) 1010", content: pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate)), 595 parts by mass of tetrahydrofuran, and 105 parts by mass of toluene were mixed to obtain a coating liquid for a charge transport layer. The coating liquid for a charge transport layer was applied onto the charge generation layer by a dip coating method, and dried at 120 ° C. for 40 minutes. In this way, a charge transport layer (film thickness: 20 μm) was formed on the charge generation layer, and a laminated photoreceptor (A-1) was obtained. In the laminated photoreceptor (A-1), an intermediate layer was provided on the conductive substrate, a charge generation layer was provided on the intermediate layer, and a charge transport layer was provided on the charge generation layer.

[0159] (Manufacture of multi-layer photoreceptors (A-2) to (A-14) and (B-1) to (B-13)) Each of the multilayer photoreceptors (A-2) to (A-14) and (B-1) to (B-13) was produced in the same manner as the multilayer photoreceptor (A-1), except that the hole transport agent and polyarylate resin shown in Table 7 were used.

[0160] <Evaluation of solubility in solvent> In an environment at a temperature of 22°C, 3 g of polyarylate resin and an amount of tetrahydrofuran such that the concentration of the polyarylate resin was 15% by mass were stirred for 60 minutes to obtain an evaluation liquid. The evaluation liquid was checked with the naked eye, and the solubility of the polyarylate resin in the solvent tetrahydrofuran was evaluated according to the following criteria. Polyarylate resins with an evaluation of A or B were judged to have good solubility in the solvent, and polyarylate resins with an evaluation of C were judged to have poor solubility in the solvent. The evaluation results of each polyarylate resin are shown in Table 6. (Evaluation criteria for solubility in solvents) A: The polyarylate resin was completely dissolved in tetrahydrofuran, and neither clouding nor gelation was observed in the evaluation liquid. B: The evaluation liquid became cloudy, but gelation of the evaluation liquid was not observed. C: Gelation of the evaluation liquid was confirmed.

[0161] <Evaluation of charging characteristics> The charging characteristics of the photoconductor were evaluated under an environment of 25°C temperature and 50% RH relative humidity. More specifically, the surface of the photoconductor was charged using a drum sensitivity tester (manufactured by Gentec Co., Ltd.) under the conditions that the charging current flowing through the charger was -10 μA and the rotation speed of the photoconductor was 31 rpm. The surface potential of the photoconductor after charging was measured. The measured surface potential was defined as the charging potential (V 0 The charge potential of each photoconductor is shown in Table 7. If the charge potential is -700V or more and -640V or less, it is judged that the photoconductor has sufficient charging characteristics for practical use.

[0162] <Evaluation of sensitivity characteristics> The sensitivity characteristics of the photoconductor were evaluated using a drum sensitivity tester (manufactured by Gentec Co., Ltd.) in an environment of 25°C temperature and 50% relative humidity. Specifically, the photoconductor was charged using the drum sensitivity tester so that the surface potential of the photoconductor was -600 V. Then, monochromatic light (wavelength: 780 nm, exposure: 0.8 μJ / cm2) extracted from the light of a halogen lamp was applied using a bandpass filter. 2 ) was irradiated onto the surface of the photoconductor. The surface potential of the photoconductor was measured 80 milliseconds after the monochromatic light irradiation, and the post-exposure potential (V L The post-exposure potential of each photoconductor is shown in Table 7.

[0163] <Abrasion resistance evaluation> The coating solution for the charge transport layer prepared in the above <Production of a laminated photoreceptor> was applied to a polypropylene sheet (thickness: 0.3 mm) wrapped around an aluminum pipe (diameter: 78 mm) and dried at 120°C for 40 minutes. In this manner, a polypropylene sheet on which a charge transport layer (film thickness: 30 μm) was formed was produced. The charge transport layer was then peeled off from the polypropylene sheet. The peeled charge transport layer was attached to a card-shaped member ("S-36" manufactured by Taber). The mass M of the card-shaped member to which the charge transport layer was attached was Awas measured. Next, the card-shaped member was attached to the rotating table of a rotary abrasion tester (Toyo Seiki Seisakusho, Ltd.). Then, with an abrasive wheel ("CS-10" manufactured by Taber) with a load of 500 gf placed on the photosensitive layer on the card-shaped member, the rotating table was rotated 1000 times at a rotation speed of 60 rpm. In this way, the charge transport layer on the rotating table was abraded. After abrasion, the mass M of the card-shaped member to which the charge transport layer was attached was B The mass loss (M A -M B The measured abrasion loss is shown in Table 7. The abrasion resistance of the photoreceptor was evaluated based on the abrasion loss according to the following criteria. (Evaluation criteria for wear resistance) Good: Wear loss is 7.5 mg or less. Poor: Wear loss exceeds 7.5 mg.

[0164] <Evaluation of suppression of component contact defects> A photoconductor was mounted on an image drum ("DR-C4BC" manufactured by OKI Data Corporation), and a member (specifically, a charging roller) of the image drum was brought into contact with a part of the peripheral surface of the photoconductor. Hereinafter, the part of the peripheral surface of the photoconductor that was in contact with the member will be referred to as the "member contact area". In addition, the peripheral surface area of ​​the photoconductor that was not in contact with the member will be referred to as the "non-member contact area". The image drum with the photoconductor mounted thereon was left for 4 weeks in an environment with a temperature of 50°C and a relative humidity of 85%RH. Immediately after leaving it for 4 weeks, the photoconductor was mounted on an evaluation machine, and an image (a halftone image with a printing rate of 50%) was printed on one sheet of paper using the evaluation machine. The printed image was observed, and whether or not the occurrence of image defects caused by contact with a member of the image forming apparatus was suppressed was evaluated according to the following criteria. The evaluation results are shown in Table 7. Photoconductors with evaluations A or B were judged to have member contact defects suppressed, and photoconductors with evaluations C were judged to have member contact defects not suppressed. (Evaluation criteria for suppression of component contact defects) A: No image density difference is observed between the image area corresponding to the member contact area and the image area corresponding to the non-member contact area. B: A slight difference in image density is observed between the image area corresponding to the member contact area and the image area corresponding to the non-member contact area. C: A clear image density difference is observed between the image area corresponding to the member contact area and the image area corresponding to the non-member contact area.

[0165] In Table 6, "resin" refers to polyarylate resin, and "solubility" refers to the evaluation of the solubility of polyarylate resin in a solvent. The terms in Table 7 have the following meanings: "photoreceptor" refers to a laminated photoreceptor. "HTM" refers to a hole transport material. "resin" refers to a polyarylate resin. "V 0 " indicates the charge potential. "V L " indicates the potential after exposure. "Unable to prepare coating solution" indicates that the polyarylate resin was not dissolved in a solvent for forming a coating solution for the charge transport layer, and therefore a coating solution for the charge transport layer could not be prepared.

[0166] [Table 6]

[0167] [Table 7]

[0168] As can be seen from Table 5, polyarylate resins H to T were not included in polyarylate resin (PA). Therefore, as shown in Tables 6 and 7, polyarylate resins H, J, L, Q, and T had poor solubility in solvents, and it was not possible to prepare a coating solution for a charge transport layer using each of polyarylate resins H, J, L, Q, and T, and it was not possible to form a photosensitive layer (more specifically, a charge transport layer). Also, as shown in Table 7, polyarylate resins I, K, R, and S could not suppress contact problems with members of the photoreceptor when contained in the photosensitive layer. Also, as shown in Table 7, polyarylate resins M, N, O, P, R, and S could not improve the wear resistance of the photoreceptor when contained in the photosensitive layer.

[0169] On the other hand, as can be seen from Table 5, polyarylate resins A to G were resins that are included in polyarylate resin (PA). Therefore, as shown in Table 6, polyarylate resins A to G had good solubility in solvents. Furthermore, as shown in Table 7, when polyarylate resins A to G were contained in a photosensitive layer, they could suppress contact problems with members of the photoreceptor and improve wear resistance. Furthermore, as shown in Table 7, when polyarylate resins A to G were contained in a photosensitive layer, they could suppress contact problems with members of the photoreceptor and improve wear resistance without impairing the charging characteristics and sensitivity characteristics of the photoreceptor.

[0170] From the above, it was shown that the polyarylate resin of the present invention including polyarylate resins A to G has excellent solubility in solvents, and when contained in a photosensitive layer, it can suppress contact problems with members of the photosensitive body and improve abrasion resistance. Also, it was shown that the photosensitive body of the present invention including laminated photosensitive bodies (A-1) to (A-14) containing polyarylate resins A to G in the photosensitive layer can form a good photosensitive layer, suppress contact problems with members, and improve abrasion resistance. [Industrial Applicability]

[0171] The photoreceptor according to the present invention can be used in an image forming apparatus. [Explanation of symbols]

[0172] 1: Multilayer photoconductor (multilayer electrophotographic photoconductor) 2: Conductive substrate 3: Photosensitive layer 3a: Charge generating layer 3b: Charge transport layer 3c: Single-layer photosensitive layer 10: Single-layer photoreceptor (single-layer electrophotographic photoreceptor)

Claims

1. Having repeating units represented by formulas (1), (2), (3), and (4), a third content, which is the content of the repeating unit represented by the formula (3) relative to the total number of repeating units represented by the formulas (1) and (3), is greater than 0% and less than 50%, A polyarylate resin, wherein a fourth content, which is a content of the repeating unit represented by the formula (4) relative to the total number of the repeating units represented by the formulas (2) and (4), is 35% or more and less than 70%. 【Chemistry 1】 (In the above formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), or R 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2). 【Chemistry 2】 (In the formulas (X1) and (X2), * represents a bond.)

2. In the formula (1), R 1 and R 2 The polyarylate resin according to claim 1 , wherein X represents a divalent group represented by formula (X1).

3. In the formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), The polyarylate resin according to claim 1 or 2, wherein the fourth content is 40% or more and less than 70%.

4. In the formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), The polyarylate resin according to any one of claims 1 to 3, wherein the third content is 30% or more and less than 50%.

5. In the formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), The polyarylate resin according to any one of claims 1 to 4, further having a terminal group having a halogen atom.

6. In the formula (1), R 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2), The polyarylate resin according to claim 1 , wherein the fourth content is 35% or more and 45% or less.

7. the first content rate is a value different from the second content rate and a value different from the fourth content rate; the third content rate is a value different from the second content rate and a value different from the fourth content rate, the first content is a content of the repeating unit represented by formula (1) relative to the total number of repeating units represented by formulas (1) and (3), The polyarylate resin according to any one of claims 1 to 6, wherein the second content is the content of the repeating unit represented by the formula (2) relative to the total number of repeating units represented by the formulas (2) and (4).

8. The polyarylate resin according to any one of claims 1 to 7, wherein the third content is greater than 30% and less than 50%.

9. The polyarylate resin according to any one of claims 1 to 8, which does not have a repeating unit represented by formula (5). 【Chemistry 3】

10. A conductive substrate and a photosensitive layer are provided. the photosensitive layer contains a charge generating material, a hole transport material, and a binder resin; The electrophotographic photoreceptor, wherein the binder resin comprises the polyarylate resin according to any one of claims 1 to 9.

11. The electrophotographic photoreceptor according to claim 10, wherein the hole transport agent comprises a compound represented by formula (19), (20), (21), or (22). 【Chemistry 4】 【Chemistry 5】 (In the above formula (19), R 16 , R 17 , R 18 , and R 19 each independently represents an alkyl group having from 1 to 6 carbon atoms, or an alkoxy group having from 1 to 6 carbon atoms; a6, a7, a8, and a9 each independently represent an integer of from 0 to 5; In the formula (20), R 21 and R 22 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms; R 23 ~R 29 each independently represents a hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, a phenyl group which may be substituted with an alkyl group having from 1 to 8 carbon atoms, or an alkoxy group having from 1 to 8 carbon atoms; R 25 ~R 29 adjacent two of a1 and a2 may be bonded to form a ring, a1 and a2 each independently represent an integer of 0 to 5, In the formula (21), R 31 ~R 36 each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group; R 37 and R 38 each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group; b1, b2, b3, and b4 each independently represent an integer of 0 to 5; b5 and b6 each independently represent an integer of 0 to 4; and d and e each independently represent 0 or 1; In the formula (22), R 41 ~R 46 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms; f1, f2, f4, and f5 each independently represent an integer of 0 to 5; and f3 and f6 each independently represent an integer of 0 to 4.

12. The electrophotographic photoreceptor according to claim 10 or 11, wherein the hole transport agent comprises a compound represented by formula (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), (HTM-6), or (HTM-7). 【Chemistry 6】 【Chemistry 7】 【Chemistry 8】

13. the photosensitive layer includes a charge generating layer containing the charge generating material, and a charge transport layer containing the hole transport material and the binder resin, 13. The electrophotographic photoreceptor according to claim 10, wherein the charge transport layer is provided as an outermost layer.

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