Polyarylate resins and electrophotographic photoreceptors

Abstract

The polyarylate resin has repeating units represented by formulae (1), (2), (3), and (4). The content ratio of the repeating unit represented by formula (3) is greater than 0% and less than 20% relative to the total number of the repeating units represented by formulae (1) and (3). In formula (1), R 1 and R 2 each independently represent a hydrogen atom or a methyl group, and X is a divalent group represented by formula (X1) or (X2). In formula (2), W is a divalent group represented by formula (W1) or (W2).

Description

TECHNICAL FIELD

[0001] The present application relates to a polyarylate resin and an electrophotographic photoreceptor. BACKGROUND

[0002] An electrophotographic photoreceptor is used in an image forming apparatus (for example, a printer or a multifunction peripheral) of an electrophotographic system as an image bearing member. The electrophotographic photoreceptor has a photosensitive layer. The electrophotographic photoreceptor is, for example, a single-layer type electrophotographic photoreceptor and a layered type electrophotographic photoreceptor. The single-layer type electrophotographic photoreceptor has a single-layer photosensitive layer having a charge generating function and a charge transporting function. The photosensitive layer in the layered type electrophotographic photoreceptor contains a charge generating layer having a charge generating function and a charge transporting layer having a charge transporting function.

[0003] In Patent Literature 1, an electrophotographic photoreceptor is described, which has a surface layer containing a polyarylate resin derived from a dicarboxylic acid component and a diphenol component represented by the following formula.

[0004]

[0005] (Patent Literature)

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 10-20514 SUMMARY

[0007] However, the electrophotographic photoreceptor described in Patent Literature 1 is insufficient in terms of wear resistance. Further, the present inventors have found through their studies that the electrophotographic photoreceptor described in Patent Literature 1 is also insufficient in terms of solubility of a binding resin in a solvent and photosensitive characteristics when charging and exposure are repeated.

[0008] The present application has been made in view of the above problems, and it is an object to provide a polyarylate resin having excellent solubility in a solvent, and when the polyarylate resin is contained in a photosensitive layer of an electrophotographic photoreceptor, the photosensitive characteristics of the electrophotographic photoreceptor when charging and exposure are repeated and the wear resistance of the electrophotographic photoreceptor are improved. Hereinafter, the "photosensitive characteristics when charging and exposure are repeated" is sometimes described as "repeated photosensitive characteristics". Further, another object of the present application is to provide an electrophotographic photoreceptor in which a photosensitive layer can be formed favorably, and which has excellent repeated photosensitive characteristics and wear resistance.

[0009] The polyarylate resin of the present application has 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 20% with respect to the total number of the repeating units represented by the formula (1) and the formula (3).

[0010]

[0011] In the formula (1), R 1 and R 2 each independently represent a hydrogen atom or a methyl group, and X represents a divalent group represented by formula (X1) or (X2). In the formula (2), W represents a divalent group represented by formula (W1) or (W2).

[0012]

[0013] In the formula (X1), t represents an integer of 1 or more and 3 or less, and * represents a binding site. In the formula (X2), R 3 and R 4 represent a hydrogen atom or a C1-C4 alkyl group, and R 3 and R 4 represent different groups from each other, and * represents a binding site.

[0014]

[0015] In the formula (W1) and (W2), * represents a binding site.

[0016] The electrophotographic photoreceptor of the present application has a conductive base and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transporting agent, and a binding resin. The binding resin contains the above-mentioned polyarylate resin.

[0017] [Effects of the Invention]

[0018] The polyarylate resin of the present application has excellent solubility in a solvent, and in the case where the polyarylate resin is contained in a photosensitive layer, the repeated photosensitivity characteristics and the wear resistance of an electrophotographic photoreceptor can be improved. The electrophotographic photoreceptor of the present application can form a photosensitive layer well, and has excellent repeated photosensitivity characteristics and wear resistance. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a partial cross-sectional view of a layered electrophotographic photoreceptor as one example of an electrophotographic photoreceptor according to the second embodiment of the present application.

[0020] Figure 2 is a partial cross-sectional view of a layered electrophotographic photoreceptor as one example of an electrophotographic photoreceptor according to the second embodiment of the present application.

[0021] Figure 3 is a partial cross-sectional view of a layered electrophotographic photoreceptor as one example of an electrophotographic photoreceptor according to the second embodiment of the present application.

[0022] Figure 4is a partial cross-sectional view of a single-layer electrophotographic photoreceptor as one example of an electrophotographic photoreceptor according to the second embodiment of the present invention.

[0023] Figure 5 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor as one example of an electrophotographic photoreceptor according to the second embodiment of the present invention.

[0024] Figure 6 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor as one example of an electrophotographic photoreceptor according to the second embodiment of the present invention.

[0025] Figure 7 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor as one example of an electrophotographic photoreceptor according to the second embodiment of the present invention. 1 H-NMR chart. DETAILED DESCRIPTION

[0026] 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 implemented after being appropriately changed within the scope of the object of the present invention. Also, there are cases where repeated descriptions are appropriately omitted, but the gist of the invention is not limited thereto. Hereinafter, sometimes "class" is added to the name of a compound to collectively refer to the compound and its derivative. Also, in the case where "class" is added to the name of a compound to indicate the name of a polymer, it indicates that the repeating unit of the polymer is derived from the compound or its derivative. Also, "general formula" and "chemical formula" are collectively referred to as "formula". "Each independently" in the description of the formula means that it can indicate the same group or a different group. Unless otherwise specified, each component described in the present specification can be used singly using one kind, or can be used in combination using two or more kinds.

[0027] C1-C8alkyl, C1-C6alkyl, C1-C4alkyl, C1-C3alkyl and C3alkyl are straight-chained or branched, and are unsubstituted. C1-C8alkyl is, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-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, straight-chained and branched heptyl and straight-chained and branched octyl. The examples of C1-C6alkyl, C1-C4alkyl, C1-C3alkyl and C3alkyl are each a group having the corresponding number of carbon atoms from the examples of C1-C8alkyl.

[0028] C1-C10perfluoroalkyl, C3-C10perfluoroalkyl, C5-C7perfluoroalkyl and C6perfluoroalkyl are straight-chained or branched, and are unsubstituted. C1-C10perfluoroalkyl is, for example, trifluoromethyl, perfluoroethyl, perfluoro-n-propyl, perfluoro-i-propyl, perfluoro-n-butyl, perfluoro-sec-butyl, perfluoro-t-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-methylpentyl, perfluoro-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, straight-chained and branched perfluoroheptyl, straight-chained and branched perfluorooctyl, straight-chained and branched perfluorononyl and straight-chained and branched perfluorodecyl. The examples of C3-C10perfluoroalkyl, C5-C7perfluoroalkyl and C6perfluoroalkyl are each a group having the corresponding number of carbon atoms from the examples of C1-C10perfluoroalkyl.

[0029] C1-C8alkoxy and C1-C3alkoxy are linear or branched, and are unsubstituted, unless otherwise stated. C1-C8alkoxy is, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, t-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, heptoxy of linear and branched chains, and octoxy of linear and branched chains. Examples of C1-C3alkoxy are groups having the corresponding number of carbon atoms among the examples of C1-C8alkoxy.

[0030] C5-C7cycloalkane is unsubstituted, unless otherwise stated. C5-C7cycloalkane is, for example, cyclopentane, cyclohexane, and cycloheptane. As described above, substituents in the present specification are explained.

[0031] <First Embodiment: Polyarylate Resin>

[0032] The first embodiment of the present application relates to a polyarylate resin. The polyarylate resin of the first embodiment has repeating units represented by formulae (1), (2), (3), and (4). The content ratio of the repeating unit represented by formula (3) is greater than 0% and less than 20% with respect to the total number of the repeating units represented by formulae (1) and (3).

[0033]

[0034] In formula (1), R 1 and R 2 each independently represent a hydrogen atom or a methyl group, and X represents a divalent group represented by formula (X1) or (X2). In formula (2), W represents a divalent group represented by formula (W1) or (W2).

[0035]

[0036] In formula (X1), t represents an integer of 1 or more and 3 or less, and * represents a bond. In formula (X2), R 3 and R 4 represent a hydrogen atom or a C1-C4alkyl group, R 3 and R 4 represent different groups from each other, and * represents a bond.

[0037]

[0038] In formulae (W1) and (W2), * represents a binding bond.

[0039] Hereinafter, the repeating units represented by formulae (1), (2), (3), and (4) are sometimes referred to as "repeating units (1), (2), (3), and (4)", respectively. Also, the content ratio of the repeating unit (3) with respect to the total number of the repeating units (1) and (3) is sometimes referred to as "content ratio (3)". Also, the polyarylate resin having the repeating units (1), (2), (3), and (4) and having the content ratio (3) of more than 0% and less than 20% is sometimes referred to as "polyarylate resin (PA)".

[0040] The polyarylate resin (PA) must contain the repeating units (1), (2), (3), and (4). By having such repeating units, the polyarylate resin (PA) has excellent solubility in a solvent, and in the case where the polyarylate resin (PA) is contained in a photosensitive layer, it is possible to improve the repeated photosensitivity characteristics and the wear resistance of an electrophotographic photoreceptor (hereinafter, sometimes referred to as a photoreceptor).

[0041] The content ratio (3) means the percentage of the number N3 of the repeating unit (3) with respect to the total of the number N1 of the repeating unit (1) and the number N3 of the repeating unit (3) possessed by the polyarylate resin (PA) (i.e., 100 x N3 / (N1+N3)). By making the content ratio (3) less than 20%, the solubility of the polyarylate resin (PA) in a solvent is improved. By making the content ratio (3) more than 0%, i.e., the content ratio (3) is not 0%, the repeated photosensitivity characteristics and the wear resistance of the photoreceptor in the case where the photosensitive layer contains the polyarylate resin (PA) are improved. The content ratio (3) is preferably 1% or more, and more preferably 5% or more. Also, the content ratio (3) is preferably 19% or less, and more preferably 10% or less.

[0042] The content ratio of the repeating unit (4) with respect to the total number of the repeating units (2) and (4) is greater than 0% and less than 100%. The content ratio of the repeating unit (4) with respect to the total number of the repeating units (2) and (4) is sometimes described as "content ratio (4)". The content ratio (4) means the percentage of the number N4 of the repeating unit (4) with respect to the total of the number N2 of the repeating unit (2) and the number N4 of the repeating unit (4) possessed by the polyarylate resin (PA) (i.e., 100 x N4 / (N2 + N4)). The content ratio (4) is greater than 0%, i.e., the content ratio (4) is not 0%, and thus the polyarylate resin (PA) has the repeating unit (4). By having the repeating unit (4), the solubility of the polyarylate resin (PA) in a solvent is improved, and in the case where the polyarylate resin (PA) is contained in a photosensitive layer, the repeated photosensitive property and the wear resistance of a photoreceptor are improved. On the other hand, the content ratio (4) is less than 100%, i.e., the content ratio (4) is not 100%, and thus the polyarylate resin (PA) has the repeating unit (2). By having the repeating unit (2), in the case where the polyarylate resin (PA) is contained in a photosensitive layer, the wear resistance of a photoreceptor is improved. The content ratio (4) is preferably 1% or more, more preferably 10% or more, and further preferably 35% or more. Also, the content ratio (4) is preferably 99% or less, more preferably 80% or less, and further preferably 65% or less.

[0043] The polyarylate resin (PA) is measured for the 1 H-NMR spectrum, the content ratios (3) and (4) can be calculated, respectively. 1 H-NMR spectrum, the content ratios (3) and (4) can be calculated, respectively.

[0044] In formula (1), R 1 and R 2 is preferably represents a methyl group.

[0045] In formula (X1), t is preferably represents 2.

[0046] In formula (X2), R 3 represents a hydrogen atom and R 4 represents a methyl group, an ethyl group or a C3 alkyl group, or R 3 represents a methyl group and R 4 represents an ethyl group or a C3 alkyl group, or R 3 represents an ethyl group and R 4 represents a C3 alkyl group. More preferably, R 3 represents a methyl group and R 4 represents an ethyl group.

[0047] The binding bond represented by * in formula (X1) and (X2) binds to the carbon atom to which X in formula (1) binds. The binding bond represented by * in formula (W1) and (W2) binds to the carbon atom to which W in formula (2) binds.

[0048] The repeating unit (1) is, for example, a repeating unit represented by formula (1-1), (1-2), and (1-3) (hereinafter, sometimes referred to as repeating unit (1-1), (1-2), and (1-3), respectively).

[0049]

[0050] The repeating unit (2) is a repeating unit represented by formula (2-1) or (2-2) (hereinafter, sometimes referred to as repeating unit (2-1) and (2-2), respectively).

[0051]

[0052] In one embodiment, it is preferable that, in formula (1), R 1 and R 2 represent a methyl group, and X is a divalent group represented by formula (X1). It is more preferable that the repeating unit (1) is the repeating unit (1-1). It is further preferable that the repeating unit (1) is the repeating unit (1-1) and the repeating unit (2) is the repeating unit (2-1); or the repeating unit (1) is the repeating unit (1-1) and the repeating unit (2) is the repeating unit (2-2).

[0053] In another embodiment, it is preferable that, in formula (1), R 1 and R 2 represent a hydrogen atom, and X is a divalent group represented by formula (X2). It is more preferable that the repeating unit (1) is the repeating unit (1-2). It is further preferable that the repeating unit (1) is the repeating unit (1-2) and the repeating unit (2) is the repeating unit (2-1); or the repeating unit (1) is the repeating unit (1-2) and the repeating unit (2) is the repeating unit (2-2). By containing the polyarylate resin (PA) in another embodiment, the wear resistance of the photoreceptor is further improved.

[0054] The polyarylate resin (PA) can also have a terminal group. The terminal group possessed by the polyarylate resin (PA) is, for example, a terminal group represented by formula (T-1) and (T-2). The terminal group represented by formula (T-1) is preferably a terminal group represented by formula (T-DMP) (hereinafter, sometimes 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, sometimes referred to as terminal group (T-PFH)).

[0055]

[0056] In formula (T-1), R 11 represents a C1-C6 alkyl group or a halogen atom, and p represents an integer of 0 or more and 5 or less. R 11 represents a C1-C6 alkyl group, more preferably a C1-C3 alkyl group, and further preferably a methyl group. p preferably represents an integer of 1 or more and 3 or less, and more preferably 2.

[0057] In formula (T-2), R 12 represents a C1-C6 alkanediyl group, and Rf represents a C1-C10 perfluoroalkyl group. R 12 represents a C1-C3 alkanediyl group, more preferably a methylene group. Rf preferably represents a C3-C10 perfluoroalkyl group, more preferably a C5-C7 perfluoroalkyl group, and further preferably a C6 perfluoroalkyl group.

[0058] * in formulae (T-1), (T-2), (T-DMP), and (T-PFH) represents a binding bond. The binding bond represented by * in formulae (T-1), (T-2), (T-DMP), and (T-PFH) binds to a repeating unit (more specifically, a repeating unit (2) or (4)) located at the terminal of the polyarylate resin (PA) and derived from a dicarboxylic acid.

[0059] Preferred examples of the polyarylate resin (PA) can be given as polyarylate resins (PA-1) to (PA-4) in Table 1. Each of the polyarylate resins (PA-1) to (PA-4) has the repeating units (1) to (4) in Table 1. In Table 1 and Table 2 described later, units (1) to (4) respectively represent the repeating units (1) to (4).

[0060]

Table 1

[0061] Polyarylate resin Unit (1) Unit (2) Unit (3) Unit (4) PA-1 1-1 2-1 3 4 PA-2 1-2 2-1 3 4 PA-3 1-1 2-2 3 4 PA-4 1-2 2-2 3 4

[0062] Further preferred examples of the polyarylate resin (PA) can be given as polyarylate resins (PA-a) to (PA-h) in Table 2. Each of the polyarylate resins (PA-a) to (PA-h) has the repeating units in Table 2 as the repeating units (1) to (4) and the terminal group in Table 2.

[0063]

Table 2

[0064] Polyarylate resin Unit (1) Unit (2) Unit (3) Unit (4) Terminal group PA-a 1-1 2-1 3 4 T-DMP PA-b 1-2 2-1 3 4 T-DMP PA-c 1-1 2-2 3 4 T-DMP PA-d 1-2 2-2 3 4 T-DMP PA-e 1-1 2-1 3 4 T-PFH PA-f 1-2 2-1 3 4 T-PFH PA-g 1-1 2-2 3 4 T-PFH PA-h 1-2 2-2 3 4 T-PFH

[0065] In the polyarylate resin (PA), the repeating unit from the bisphenol (more specifically, the repeating unit (1) or (3)) is bonded to the repeating unit from the dicarboxylic acid (more specifically, the repeating unit (2) or (4)) adjacent to each other. That is, the repeating unit (1) can be combined with the repeating unit (2) or the repeating unit (4). Also, the repeating unit (3) can be combined with the repeating unit (2) or the repeating unit (4). The repeating unit from the bisphenol and the repeating unit from the dicarboxylic acid have substantially the same number, satisfying the calculation formula "the number of the repeating unit from the dicarboxylic acid = the number of the repeating unit from the bisphenol + 1". The polyarylate resin (PA) can be, for example, a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer.

[0066] In the polyarylate resin (PA), the repeating unit (1) can contain only one kind of the repeating unit (1) or can contain two or more (for example, two) kinds of the repeating unit (1). In the polyarylate resin (PA), the repeating unit (2) can contain only one kind of the repeating unit (2) or can contain two kinds of the repeating unit (2).

[0067] In the polyarylate resin (PA), the repeating unit can further have a repeating unit other than the repeating units (1) to (4). However, in order to improve the solubility in a solvent and the repeated photosensitive properties and the abrasion resistance of a photoreceptor in the case where the photosensitive layer contains the polyarylate resin (PA), the content ratio of the repeating units (1) to (4) with respect to the total number of the repeating units possessed by the polyarylate resin (PA) is preferably 90% or more, more preferably 95% or more, further preferably 99% or more, and particularly preferably 100%. That is, the polyarylate resin (PA) is particularly preferably a repeating unit having only the repeating units (1) to (4).

[0068] In order to improve the solubility in a solvent, the content ratio of the repeating unit (3) with respect to the total number of the repeating units from the bisphenol possessed by the polyarylate resin (PA) is preferably 20% or less, and more preferably less than 20%.

[0069] The viscosity average molecular weight of the polyarylate resin (PA) is preferably 10,000 or more, more preferably 30,000 or more, further more preferably 50,000, particularly preferably 55,000 or more. When the viscosity average molecular weight of the polyarylate resin (PA) is 10,000 or more, in the case where the polyarylate resin (PA) is contained in the photosensitive layer of the photoreceptor, the wear resistance of the photoreceptor is improved. 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, further 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 in accordance with JIS (Japanese Industrial Standards) K7252-1:2016.

[0070] Next, the method for producing the polyarylate resin (PA) will be described. The method for producing the polyarylate resin (PA) is, for example, a method in which a bisphenol (used for constituting a repeating unit from a bisphenol) and a dicarboxylic acid (used for constituting a repeating unit from a dicarboxylic acid) are subjected to polycondensation. The polycondensation can employ a well-known synthesis method (for example, solution polymerization, melt polymerization, or interfacial polymerization).

[0071] The bisphenol (used for constituting a repeating unit from a bisphenol) is, for example, a compound represented by formula (BP-1) and (BP-3) (hereinafter, sometimes described as compound (BP-1) and (BP-3), respectively). The dicarboxylic acid (used for constituting a repeating unit from a dicarboxylic acid) is, for example, a compound represented by formula (DC-2) and (DC-4) (hereinafter, sometimes described as compound (DC-2) and (DC-4), respectively). R 1 , R 2 , and X in formula (BP-1) have the same meanings as R 1 , R 2 , and X in formula (1). W in formula (DC-2) has the same meaning as W in formula (2).

[0072]

[0073] In the production of the polyarylate resin (PA), the content ratio (3) can be adjusted by changing the added amount (unit: mol) of the compound (BP-3) with respect to the total of the added amounts (unit: mol) of the compounds (BP-1) and (BP-3). Also, the content ratio (4) can be adjusted by changing the added amount (unit: mol) of the compound (DC-4) with respect to the total of the added amounts (unit: mol) of the compounds (DC-2) and (DC-4).

[0074] The bisphenol can also use a derivatized aromatic diacetate. The dicarboxylic acid can also use a derivative. Examples of the derivative of the dicarboxylic acid are: dicarboxylic acid dichloride, dicarboxylic acid dimethyl ester, dicarboxylic acid diethyl ester, and dicarboxylic acid anhydride. The dicarboxylic acid dichloride is a compound in which the two "-C(=O)-OH" groups of the dicarboxylic acid are each substituted with a "-C(=O)-Cl" group.

[0075] In the polycondensation of the bisphenol and the dicarboxylic acid, one or both of a terminal terminator and a base and a catalyst can be added. The terminal terminator is, for example, 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.

[0076] In the polycondensation of the bisphenol and the dicarboxylic acid, one or both of a terminal terminator and a base and a catalyst can be added. The terminal terminator is, for example, 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.

[0077] <Second Embodiment: Photoreceptor>

[0078] The second embodiment of the present application relates to a photoreceptor. The photoreceptor of the second embodiment has an electrically conductive base and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transporting agent, and a binding resin. The photoreceptor is, for example, a single-layer type electrophotographic photoreceptor (hereinafter, sometimes referred to as a single-layer type photoreceptor) or a layered type electrophotographic photoreceptor (hereinafter, sometimes referred to as a layered type photoreceptor).

[0079] (layered type photoreceptor)

[0080] Hereinafter, referring to Figures 1 to 3 , a layered type photoreceptor 1 as an example of a photoreceptor will be described. Figures 1 to 3 Each of the figures represents a partial cross-sectional view of the layered type photoreceptor 1.

[0081] As shown in Figure 1 , the layered type photoreceptor 1 has, for example, an electrically conductive base 2 and a photosensitive layer 3. The photosensitive layer 3 contains a charge generating layer 3a and a charge transporting layer 3b. That is, in the layered type photoreceptor 1, the photosensitive layer 3 has the charge generating layer 3a and the charge transporting layer 3b. The charge generating layer 3a is, for example, one layer. The charge transporting layer 3b is, for example, one layer.

[0082] As shown in Figure 1 , the charge generating layer 3a can be provided on the electrically conductive base 2, and the charge transporting layer 3b can be provided on the charge generating layer 3a. Alternatively, as shown in Figure 2 , the charge transporting layer 3b can be provided on the electrically conductive base 2, and the charge generating layer 3a can be provided on the charge transporting layer 3b.

[0083] As shown in Figure 3 , the layered photoreceptor 1 can further have an intermediate layer 4 (undercoat layer) on the basis of the conductive base 2 and the photosensitive layer 3. The intermediate layer 4 is provided between the conductive base 2 and the photosensitive layer 3. As shown in Figure 1 and Figure 2 , in the layered photoreceptor 1, the photosensitive layer 3 can be directly on the conductive base 2. Alternatively, as shown in Figure 3 , in the layered photoreceptor 1, the photosensitive layer 3 can be on the conductive base 2 with the intermediate layer 4 interposed therebetween. In the case where the layered photoreceptor 1 has the intermediate layer 4, as shown in Figure 3 , the intermediate layer 4 can be provided on the conductive base 2, the charge generation layer 3a can be provided on the intermediate layer 4, and the charge transport layer 3b can be provided on the charge generation layer 3a. Alternatively, the intermediate layer 4 can be provided on the conductive base 2, the charge transport layer 3b can be provided on the intermediate layer 4, and the charge generation layer 3a can be provided on the charge transport layer 3b.

[0084] The layered photoreceptor 1 can further have a protective layer 5 on the basis of the conductive base 2 and the photosensitive layer 3 (refer to Figure 6 ). The protective layer 5 is provided on the photosensitive layer 3. As shown in Figures 1 to 3 , the photosensitive layer 3 (for example, the charge transport layer 3b or the charge generation layer 3a) can be the outermost surface layer of the layered photoreceptor 1. Alternatively, the protective layer 5 can be the outermost surface layer of the layered photoreceptor 1.

[0085] As shown in Figure 1 , it is preferable that the photosensitive layer 3 (preferably, the charge transport layer 3b) be the outermost surface layer of the layered photoreceptor 1. It is more preferable that the charge transport layer 3b be one layer and be the outermost surface layer of the layered photoreceptor 1. By making the charge transport layer 3b containing the polyarylate resin (PA) the outermost surface layer, the wear resistance of the layered photoreceptor 1 is further improved.

[0086] The charge generation layer 3a contains a charge generating agent. The charge generation layer 3a can contain a base resin as needed. The charge generation layer 3a can contain an additive as needed. The thickness of the charge generation layer 3a is not particularly limited, and is preferably 0.01 μm or more and 5 μm or less, more preferably 0.1 μm or more and 3 μm or less.

[0087] The charge transport layer 3b contains a hole transport agent and a binding resin. The charge transport layer 3b can contain an additive as needed. The thickness of the charge transport layer 3b is not particularly limited, and is preferably 2 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less. As described above, the layered photoreceptor 1 is described with reference to Figures 1 to 3 .

[0088] (single-layer type photoreceptor)

[0089] Next, referring to Figures 4 to 6 , a single-layer type photoreceptor 10 as one example of a photoreceptor will be described. Figures 4 to 6 Each is a partial cross-sectional view of the single-layer type photoreceptor 10.

[0090] As Figure 4 indicated, the single-layer type photoreceptor 10 has, for example, a conductive base 2 and a photosensitive layer 3. The photosensitive layer 3 that the single-layer type photoreceptor 10 has is single-layered. Hereinafter, the "single-layered photosensitive layer 3" is sometimes described as "single-layer type photosensitive layer 3c".

[0091] As Figure 5 indicated, on the basis of the conductive base 2 and the single-layer type photosensitive layer 3c, the single-layer type photoreceptor 10 can further have an intermediate layer 4 (primer layer). The intermediate layer 4 is provided between the conductive base 2 and the single-layer type photosensitive layer 3c. As Figure 4 indicated, the single-layer type photosensitive layer 3c can be directly on the conductive base 2. Alternatively, as Figure 5 indicated, the single-layer type photosensitive layer 3c can be on the conductive base 2 with the intermediate layer 4 interposed therebetween.

[0092] As Figure 6 indicated, on the basis of the conductive base 2 and the single-layer type photosensitive layer 3c, the single-layer type photoreceptor 10 can further have a protective layer 5. The protective layer 5 is provided on the single-layer type photosensitive layer 3c. As Figure 4 and Figure 5 indicated, the single-layer type photosensitive layer 3c can be the outermost surface layer of the single-layer type photoreceptor 10. Alternatively, as Figure 6 indicated, the protective layer 5 can be the outermost surface layer of the single-layer type photoreceptor 10.

[0093] As Figure 4 and Figure 5 indicated, it is preferable that the photosensitive layer 3 (more specifically, the single-layer type photosensitive layer 3c) be the outermost surface layer of the single-layer type photoreceptor 10. The single-layer type photoreceptor 10 is further improved in wear resistance by having the single-layer type photosensitive layer 3c containing a polyarylate resin (PA) as the outermost surface layer.

[0094] The single-layer type photosensitive layer 3c contains a charge generating agent, a hole transporting agent, and a binding resin. The single-layer type photosensitive layer 3c can further contain an electron transporting agent as needed. The single-layer type photosensitive layer 3c can contain an additive as needed.

[0095] The thickness of the single-layer type photosensitive layer 3c is not particularly limited, and is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. As described above, the single-layer type photoreceptor 10 will be described with reference to Figures 4 to 6 .

[0096] (binder resin)

[0097] The binder resin contains the polyarylate resin (PA) described in the first embodiment. By using the polyarylate resin (PA) having excellent solubility in a solvent, the photosensitive layer of the photoreceptor can be formed well. Also, by containing the polyarylate resin (PA) in the photosensitive layer, the repeated photosensitivity characteristics and the wear resistance of the photoreceptor are improved.

[0098] In the photosensitive layer, the binder resin can contain only one kind of polyarylate resin (PA), or can contain two or more kinds of polyarylate resin (PA). Also, in the photosensitive layer, the binder resin can contain only the polyarylate resin (PA), or can further contain a binder resin other than the polyarylate resin (PA) (hereinafter, sometimes described as other binder resin). The other binder resin is, for example, a thermoplastic resin (more specifically, a polyarylate resin other than the polyarylate resin (PA), a polycarbonate resin, a styrene-based resin, a styrene-butadiene copolymer, a styrene-acrylonitrile copolymer, a styrene-maleic acid copolymer, a styrene-acrylic acid copolymer, an acrylic copolymer, a polyethylene resin, an ethylene-vinyl acetate copolymer, a chlorinated polyethylene resin, a polyvinyl chloride resin, a polypropylene resin, an ionomer, a chlorovinyl-vinyl acetate copolymer, a polyester resin, an alkyd resin, a polyamide resin, a polyurethane resin, a polysulfone resin, a diallyl phthalate resin, a ketone resin, a polyvinyl butyral resin, a polyvinyl acetal resin, and a polyether resin), a thermosetting resin (more specifically, a silicone resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, and other cross-linking thermosetting resins), and a photocurable resin (more specifically, an epoxy-acrylic resin and a polyurethane-acrylic copolymer).

[0099] (hole transporting agent)

[0100] The hole transporting agent is, for example, a triphenylamine derivative, a diamine derivative (for example, an N,N,N',N'-tetraphenylbenzidine derivative, an N,N,N',N'-tetraphenylphenylenediamine derivative, an N,N,N',N'-tetraphenyl naphthalene diamine derivative, an N,N,N',N'-tetraphenyl phenanthrylene diamine derivative, and a di(amino phenyl vinyl)benzene derivative), an oxadiazole compound (for example, 2,5-di(4-methylamino phenyl)-1,3,4-oxadiazole), a styryl compound (for example, 9-(4-diethylamino styryl)anthracene), a carbazole compound (for example, polyvinyl carbazole), an organopolysilane compound, a pyrazoline compound (for example, 1-phenyl-3-(p-dimethylamino phenyl) pyrazoline), a hydrazone compound, an indole compound, an oxazole compound, an isoxazole compound, a thiazole compound, a thiadiazole compound, an imidazole compound, a pyrazole compound, and a triazole compound. The photosensitive layer can contain only one hole transporting agent, or two or more hole transporting agents.

[0101] Preferred examples of the hole transporting agent can be a compound represented by formula (20), (21), and (22) (hereinafter, sometimes referred to as hole transporting agents (20), (21), and (22), respectively). By containing the polyarylate resin (PA) and the hole transporting agent (20), (21), or (22) in the photosensitive layer, the photosensitive layer can be further favorably formed, and the repeated photosensitivity characteristics and the wear resistance of the photoreceptor are further improved.

[0102]

[0103] In formula (20), R 21 and R 22 each independently represent a C1-C8 alkyl group, a phenyl group, or a C1-C8 alkoxy group. R 23 , R 24 , R 25 , R 26 , R 27 , R 28 and R 29 each independently represent a hydrogen atom, a C1-C8 alkyl group, a C1-C8 alkoxy group, a phenyl group having a C1-C8 alkyl substituent, or an unsubstituted phenyl group. R 25 , R 26 , R 27 , R 28 and R 29 of adjacent two are not bonded to each other or are bonded to each other to form a ring. a1 and a2 each independently represent an integer of 0 or more and 5 or less.

[0104] In formula (20), a1 represents an integer of 2 or more and 5 or less, and the number of R 21 Each of R1and R2may be the same group or a different group. a2 represents an integer of 2 or more and 5 or less, and the number of R 22 Each of R1and R2may be the same group or a different group.

[0105] In formula (20), R 21 and R 22 Each of R1and R2independently represents a C1-C8 alkyl group, preferably a C1-C3 alkyl group, and more preferably a methyl group.

[0106] In formula (20), R 23 and R 24 Each of R1and R2independently represents a hydrogen atom, a phenyl group having a C1-C8 alkyl substituent, or an unsubstituted phenyl group. R 23 and R 24 When R1and R2represent a phenyl group having a C1-C8 alkyl substituent or an unsubstituted phenyl group, R1and R2preferably represent a phenyl group having a C1-C8 alkyl substituent, more preferably a phenyl group having a C1-C3 alkyl substituent, and further preferably a methylphenyl group, and particularly preferably a 4-methylphenyl group.

[0107] In formula (20), R 25 and R 29 Each of R1and R2independently represents a hydrogen atom or a C1-C8 alkoxy group. R 25 and R 29 When R1and R2represent a C1-C8 alkoxy group, R1and R2preferably represent a C1-C3 alkoxy group, and more preferably a methoxy group or an ethoxy group. In the case where 2 adjacent ones of R 25 and R 29 are bonded to each other to form a ring, the ring is condensed with the phenyl group to which R 25 and R 29 are bonded, to form a bicyclic fused ring group. In this case, the condensed portion of the ring and the phenyl group can also have a double bond. In the case where 2 adjacent ones of R 25 and R 29 are bonded to form a ring, the ring is preferably a C5-C7 cycloalkane, and more preferably a cyclohexane.

[0108] In formula (20), a1 and a2 each independently represent 0 or 1.

[0109] In formula (21), R 31 , R 32 , R 33 , R 34 , R 35 , and R 36 Each of R1and R2independently represents a C1-C8 alkyl group or a phenyl group. R 37 and R 38each independently represents a hydrogen atom, a C1-C8 alkyl group 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.

[0110] In formula (21), when b1 represents an integer of 2 to 5, several R 31 each other, or can be different groups. When b2 represents an integer of 2 to 5, several R 32 each other, or can be different groups. When b3 represents an integer of 2 to 5, several R 33 each other, or can be different groups. When b4 represents an integer of 2 to 5, several R 34 each other, or can be different groups. When b5 represents an integer of 2 to 4, several R 35 each other, or can be different groups. When b6 represents an integer of 2 to 4, several R 36 each other, or can be different groups.

[0111] In formula (21), R 31 to R 36 each independently, preferably represents a C1-C8 alkyl group, more preferably represents a C1-C3 alkyl group, further preferably represents a methyl group or an ethyl group. R 37 and R 38 preferably represents a hydrogen atom. b1, b2, b3 and b4 each independently, preferably represent an integer of 0 to 2. b5 and b6 preferably represent 0.

[0112] In formula (22), R 41 , R 42 , R 43 , R 44 , R 45 and R 46 each independently represents a C1-C8 alkyl group, a phenyl group or a C1-C8 alkoxy group. 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.

[0113] In formula (22), when f1 represents an integer of 2 to 5, several R 41 each other, or can be different groups. When f2 represents an integer of 2 to 5, several R 42 each other, or can be different groups. When f4 represents an integer of 2 to 5, several R 44Each of R1to R4may be the same or different. When f5 represents an integer of 2 or more and 5 or less, the number of R 45 Each of R1to R4may be the same or different. When f3 represents an integer of 2 or more and 4 or less, the number of R 43 Each of R1to R4may be the same or different. When f6 represents an integer of 2 or more and 4 or less, the number of R 46 Each of R1to R4may be the same or different.

[0114] In formula (22), R 41 ~R 46 Each of R1to R4may be the same or different. When f3 represents an integer of 2 or more and 4 or less, the number of R 44 , R 45 and R 46 Diphenylamino styryl group having R 41 , R 42 and R 43 is preferably combined to the para position of the phenyl group.

[0115] Further preferable examples of the hole transporting agent can be compounds represented by formulae (HTM-1) to (HTM-6) (hereinafter, sometimes referred to as hole transporting agents (HTM-1) to (HTM-6), respectively).

[0116]

[0117]

[0118] In the case where the photoreceptor is a layered photoreceptor, the content of the hole transporting 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 further preferably 40 parts by mass or more and 60 parts by mass or less, with respect to 100 parts by mass of the binding resin 100. In the case where the photoreceptor is a single-layered photoreceptor, the content of the hole transporting agent is preferably 50 parts by mass or more and 200 parts by mass or less, and more preferably 50 parts by mass or more and 70 parts by mass or less, with respect to 100 parts by mass of the binding resin 100.

[0119] (charge generating agent)

[0120] The charge generating agent is, for example, a phthalocyanine pigment, a perylene pigment, a disazo pigment, a trisazo pigment, a dithioketo-pyrrolopyrrole pigment, a metal-free naphthalocyanine pigment, a metal-containing naphthalocyanine pigment, a squarylium pigment, an indigo pigment, a shikonin blue pigment, a cyanine pigment, a powder of an inorganic photoconductive material (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon), a pyran pigment, an anthanthrone pigment, a triphenylmethane pigment, a sylene pigment, a toluidine pigment, a pyrazoline pigment, and a quinacridone pigment. The photosensitive layer can contain only one charge generating agent, or can contain two or more charge generating agents.

[0121] The phthalocyanine pigment is a pigment having a phthalocyanine structure. The phthalocyanine pigment is, for example, a metal-free phthalocyanine and a metal-containing phthalocyanine. The metal-containing phthalocyanine is, for example, a titanium-oxo phthalocyanine, a gallium-hydroxy phthalocyanine, and a gallium-chloro phthalocyanine. The metal-free phthalocyanine is represented by Formula (CGM-1). The titanium-oxo phthalocyanine is represented by Formula (CGM-2).

[0122]

[0123]

[0124] The phthalocyanine pigment can be crystalline or non-crystalline. The crystal of the metal-free phthalocyanine is, for example, an X-type crystal of the metal-free phthalocyanine (hereinafter, sometimes referred to as an X-type metal-free phthalocyanine). The crystal of the titanium-oxo phthalocyanine is, for example, an α-type, a β-type, and a Y-type crystal of the titanium-oxo phthalocyanine (hereinafter, sometimes referred to as an α-type, a β-type, and a Y-type titanium-oxo phthalocyanine, respectively).

[0125] For example, in a digital optical image forming apparatus (for example, a laser printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoreceptor having photosensitivity in a wavelength region of 700 nm or more. From the viewpoint of having a high quantum yield in a wavelength region of 700 nm or more, the charge generating agent is preferably a phthalocyanine pigment, more preferably a metal-free phthalocyanine or a titanium-oxo phthalocyanine, further preferably a titanium-oxo phthalocyanine, and particularly preferably a Y-type titanium-oxo phthalocyanine.

[0126] The Y-type titanium-oxo phthalocyanine has a main peak at a Bragg angle (2θ ± 0.2°) of 27.2° in a CuKα characteristic X-ray diffraction spectrum. The main peak in the CuKα characteristic X-ray diffraction spectrum means a peak having the first or second largest intensity in a range of a Bragg angle (2θ ± 0.2°) of 3° or more and 40° or less. The Y-type titanium-oxo phthalocyanine has no peak at 26.2° in the CuKα characteristic X-ray diffraction spectrum.

[0127] The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, the sample (oxytitanium phthalocyanine) is filled into a sample holder of an X-ray diffractometer (Rigaku Corporation, "RINT (Japan Registered Trademark) 1100"), and an X-ray diffraction spectrum is measured under conditions of an X-ray tube Cu, a tube voltage of 40 kV, a tube current of 30 mA, and a CuKα characteristic X-ray wavelength of 1.5406 A. The measurement range (2θ) is, for example, 3° or more and 40° or less (start angle 3°, stop angle 40°), and the scanning speed is, for example, 10° / min. From the obtained X-ray diffraction spectrum, the main peak is determined, and the Bragg angle of the main peak is read.

[0128] In the case where the photoreceptor is a layered 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, with respect to 100 parts by mass of the base resin. In the case where the photoreceptor is a single-layered 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, with respect to 100 parts by mass of the binder resin.

[0129] (Base Resin)

[0130] Examples of the base resin contained in the charge generating layer are the same as examples of the other binder resins contained in the charge transport layer.

[0131] (Additives)

[0132] The additives are, for example, ultraviolet absorbers, antioxidants, radical scavengers, singlet quenchers, softening agents, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, donors, surfactants, plasticizers, sensitizers, electron acceptor compounds, and leveling agents. The leveling agent is preferably a silicone oil, and more preferably a silicone oil having a polydimethylsiloxane structure.

[0133] (Combination of Materials)

[0134] In order to form a photosensitive layer well and improve the repeated photosensitive properties and wear resistance of the photoreceptor, the combination of the hole transporting agent and the binding resin is preferably each of the combinations No. a-1 to a-24 and b-1 to b-48 in Table 3 and the combinations No. c-1 to c-60 in Table 4. For the same reason, it is preferable that the combination of the hole transporting agent and the binding resin is each of the combinations No. a-1 to a-24 and b-1 to b-48 in Table 3 and the combinations No. c-1 to c-60 in Table 4, and the charge generating agent is a Y-type titanyl phthalocyanine. For the same reason, it is more preferable that the combination of the hole transporting agent and the binding resin is each of the combinations No. a-1 to a-24 and b-1 to b-48 in Table 3 and the combinations No. c-1 to c-60 in Table 4, and the additive contained in the charge transporting layer is m-terphenyl. For the same reason, it is more preferable that the combination of the hole transporting agent and the binding resin is each of the combinations No. a-1 to a-24 and b-1 to b-48 in Table 3 and the combinations No. c-1 to c-60 in Table 4, and the additive contained in the charge transporting layer is silicone oil (more specifically, silicone oil having a polydimethylsiloxane structure). In Table 3 and Table 4, "No." means "combination No.", "HTM" means "hole transporting agent", and "resin" means "polyarylate resin" as the binding resin. As for the polyarylate resins A to I and P in Table 4, detailed descriptions will be given in the examples.

[0135] [Table 3]

[0136] No. HTM Resin No. HTM Resin No. HTM Resin a-1 HTM-1 PA-1 b-1 HTM-1 PA-a b-25 HTM-1 PA-e a-2 HTM-2 PA-1 b-2 HTM-2 PA-a b-26 HTM-2 PA-e a-3 HTM-3 PA-1 b-3 HTM-3 PA-a b-27 HTM-3 PA-e a-4 HTM-4 PA-1 b-4 HTM-4 PA-a b-28 HTM-4 PA-e a-5 HTM-5 PA-1 b-5 HTM-5 PA-a b-29 HTM-5 PA-e a-6 HTM-6 PA-1 b-6 HTM-6 PA-a b-30 HTM-6 PA-e a-7 HTM-1 PA-2 b-7 HTM-1 PA-b b-31 HTM-1 PA-f a-8 HTM-2 PA-2 b-8 HTM-2 PA-b b-32 HTM-2 PA-f a-9 HTM-3 PA-2 b-9 HTM-3 PA-b b-33 HTM-3 PA-f a-10 HTM-4 PA-2 b-10 HTM-4 PA-b b-34 HTM-4 PA-f a-11 HTM-5 PA-2 b-11 HTM-5 PA-b b-35 HTM-5 PA-f a-12 HTM-6 PA-2 b-12 HTM-6 PA-b b-36 HTM-6 PA-f a-13 HTM-1 PA-3 b-13 HTM-1 PA-c b-37 HTM-1 PA-g a-14 HTM-2 PA-3 b-14 HTM-2 PA-c b-38 HTM-2 PA-g a-15 HTM-3 PA-3 b-15 HTM-3 PA-c b-39 HTM-3 PA-g a-16 HTM-4 PA-3 b-16 HTM-4 PA-c b-40 HTM-4 PA-g a-17 HTM-5 PA-3 b-17 HTM-5 PA-c b-41 HTM-5 PA-g a-18 HTM-6 PA-3 b-18 HTM-6 PA-c b-42 HTM-6 PA-g a-19 HTM-1 PA-4 b-19 HTM-1 PA-d b-43 HTM-1 PA-h a-20 HTM-2 PA-4 b-20 HTM-2 PA-d b-44 HTM-2 PA-h a-21 HTM-3 PA-4 b-21 HTM-3 PA-d b-45 HTM-3 PA-h a-22 HTM-4 PA-4 b-22 HTM-4 PA-d b-46 HTM-4 PA-h a-23 HTM-5 PA-4 b-23 HTM-5 PA-d b-47 HTM-5 PA-h a-24 HTM-6 PA-4 b-24 HTM-6 PA-d b-48 HTM-6 PA-h

[0137] [Table 4]

[0138]

[0139] (conductive base)

[0140] The conductive base is not particularly limited as long as at least a surface portion thereof is formed of a conductive material. One example of the conductive base is a conductive base composed of a conductive material. Another example of the conductive base is a conductive base coated with a conductive material. The conductive material is, for example, aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. Among these conductive materials, aluminum or an aluminum alloy is preferable from the viewpoint of good movement of charges from the photosensitive layer to the conductive base.

[0141] The shape of the conductive base is appropriately selected depending on the structure of the image forming apparatus. The shape of the conductive base is, for example, a sheet shape and a drum shape. Also, the thickness of the conductive base is appropriately selected depending on the shape of the conductive base.

[0142] (intermediate layer)

[0143] The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin used in the intermediate layer (intermediate layer resin). It is considered that, by the presence of the intermediate layer, it is possible to maintain an insulating state to such a degree that the occurrence of electric leakage is suppressed, while making the current flowing at the time of exposure of the photoreceptor smooth, thereby making it possible to suppress an increase in resistance.

[0144] The inorganic particles are, for example, particles of metals (for example, aluminum, iron, and copper), particles of metal oxides (for example, titanium dioxide, aluminum oxide, zirconium oxide, tin oxide, and zinc oxide), and particles of non-metal oxides (for example, silicon dioxide).

[0145] Examples of the intermediate layer resin are the same as those of the aforementioned other binder resins. In order to form the intermediate layer and the photosensitive layer well, the intermediate layer resin is preferably different from the binder resin contained in the photosensitive layer. The intermediate layer can also contain an additive. Examples of the additive contained in the intermediate layer are the same as those of the additive contained in the photosensitive layer.

[0146] (Method for manufacturing photoreceptor)

[0147] With regard to the method for manufacturing the photoreceptor, one example of a method for manufacturing a layered photoreceptor and one example of a method for manufacturing a single-layered photoreceptor will be described.

[0148] The method for manufacturing the layered photoreceptor contains, 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 coated on a conductive base. Then, at least a part of the solvent contained in the coated charge generation layer coating liquid is removed, thereby forming 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 the solvent. The charge generation layer coating liquid can further contain an additive as necessary.

[0149] In the charge transport layer forming step, first, a coating liquid for forming a charge transport layer (hereinafter, sometimes referred to as a charge transport layer coating liquid) is prepared. The charge transport layer coating liquid is coated on the charge generation layer. Then, at least a part of the solvent contained in the coated charge transport layer coating liquid is removed, thereby forming a charge transport layer. The charge transport layer coating liquid contains a hole transport agent, a binder resin, and a solvent. The charge transport layer coating liquid can be prepared by dissolving or dispersing the hole transport agent, the binder resin, and an additive in the solvent. The charge transport layer coating liquid can further contain an additive as necessary.

[0150] The manufacturing method of the single-layer type photosensitive body, for example, includes a single-layer type photosensitive layer forming step. In the single-layer type photosensitive layer forming step, a coating liquid for forming a single-layer type photosensitive layer (hereinafter, sometimes referred to as a single-layer type photosensitive layer coating liquid) is prepared. The single-layer type photosensitive layer coating liquid is coated on a conductive base. Then, at least a part of the solvent contained in the coated photosensitive layer coating liquid is removed, thereby forming a single-layer type photosensitive layer. The single-layer type photosensitive layer coating liquid, for example, contains a charge generating agent, a hole transporting agent, a binding resin, and a solvent. The single-layer type photosensitive layer coating liquid is prepared by dissolving or dispersing the charge generating agent, the hole transporting agent, and the binding resin in the solvent. As necessary, the single-layer type photosensitive layer coating liquid can further contain one or both of an electron transporting agent and an additive.

[0151] The solvent contained in the single-layer type photosensitive layer coating liquid, the charge generating layer coating liquid, and the charge transporting layer coating liquid (hereinafter, sometimes collectively referred to as a coating liquid) is not particularly limited as long as it can dissolve or disperse the respective components contained in the coating liquid. The solvent is, for example, an alcohol (more specifically, methanol, ethanol, isopropanol, butanol, and the like), an aliphatic hydrocarbon (more specifically, n-hexane, octane, and cyclohexane, and the like), an aromatic hydrocarbon (more specifically, benzene, toluene, and xylene, and the like), a halogenated hydrocarbon (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene, and the like), an ether (more specifically, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether, and the like), a ketone (more specifically, acetone, methyl ethyl ketone, and cyclohexanone, and the like), an ester (more specifically, ethyl acetate and methyl acetate, and the like), dimethylformaldehyde, dimethylformamide, and dimethyl sulfoxide.

[0152] The solvent contained in the charge transporting layer coating liquid is preferably different from the solvent contained in the charge generating layer coating liquid. The reason for this is that, in the case of coating the charge transporting layer coating liquid on the charge generating layer, it is preferable that the charge generating layer not be dissolved in the solvent of the charge transporting layer coating liquid.

[0153] The respective components are mixed and dispersed in the solvent, thereby preparing the coating liquid. In the operation of mixing or dispersing, for example, a bead mill, a roll mill, a ball mill, a mortar, a paint shaker, or an ultrasonic disperser can be used.

[0154] The method of coating using the coating liquid is not particularly limited as long as it is a method capable of uniformly coating the coating liquid. The coating method is, for example, a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

[0155] As a method for removing at least a part of the solvent contained in the coating liquid, for example, there are heating, reduced pressure, or a combination of heating and reduced pressure. More specifically, there can be mentioned a method of performing heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer. The temperature of the heat treatment is, for example, 40°C or higher and 150°C or lower. The time of the heat treatment is, for example, 3 minutes or longer and 120 minutes or shorter.

[0156] Further, in the production method of the photoreceptor, one or both of an intermediate layer forming step and a protective layer forming step can be further included as necessary. In the intermediate layer forming step and the protective layer forming step, a publicly known method can be appropriately selected.

[0157]

EXAMPLES

[0158] Hereinafter, the present application will be described more specifically using examples. However, the present application is not limited in any way by the scope of the examples.

[0159] <Preparation of polyarylate resins A to N and P>

[0160] The polyarylate resins A to I and P relating to the examples and the polyarylate resins J to N relating to the comparative examples were synthesized by the following methods. The compositions of the polyarylate resins A to I, P and J to N are shown in Table 5 below.

[0161]

Table 5

[0162]

[0163] In Table 5, "BisCZ", "BisB", "BisZ", "BP", "14NACC", "26NACC", "DPEC", "TPC" and "IPC" respectively mean compounds represented by the following formulas (BisCZ), (BisB), (BisZ), (BP), (14NACC), (26NACC), (DPEC), (TPC) and (IPC) (hereinafter, sometimes written as compounds (BisCZ), (BisB), (BisZ), (BP), (14NACC), (26NACC), (DPEC), (TPC) and (IPC), respectively).

[0164]

[0165] Further, the meanings of the respective terms in Table 5 are as follows.

[0166] Monomer: monomer used in the synthesis of the polyarylate resin

[0167] Forming unit: repeating unit formed from the monomer

[0168] Resin: polyarylate resin

[0169] Bisphenol addition ratio: percentage (%) of the amount (unit: mol) of the bisphenol monomer with respect to the total amount (unit: mol) of the bisphenol monomer added in the synthesis of the polyarylate resin

[0170] Dicarboxylic acid addition ratio: percentage (%) of the amount (unit: mol) of the dicarboxylic acid monomer with respect to the total amount (unit: mol) of the dicarboxylic acid monomer added in the synthesis of the polyarylate resin

[0171] Molecular weight: viscosity average molecular weight

[0172] Unit: repeating unit

[0173] TPC / IPC: mixture of compounds (TPC) and (IPC) at a molar ratio of 1 / 1

[0174] 50 / 50 in the column of TPC / IPC: dicarboxylic acid addition ratio of the compound (TPC) is 50% and dicarboxylic acid addition ratio of the compound (IPC) is 50%

[0175] DMP: 2,6-dimethylphenol

[0176] PFH: 1H, 1H-perfluoro-1-heptanol

[0177] Not measurable: the polyarylate resin was not soluble in the solvent for viscosity molecular weight measurement, and the viscosity average molecular weight could not be measured

[0178] (Synthesis of polyarylate resin A)

[0179] A three-necked flask equipped with a thermometer, a three-way valve, and a dropping funnel was used as a reaction vessel. In the reaction vessel, compound (BisCZ) (38.95 mmol) as a monomer, compound (BP) (2.05 mmol) as a monomer, 2,6-dimethylphenol (0.413 mmol) as a terminal terminator, sodium hydroxide (98 mmol), and benzyltributylammonium chloride (0.384 mmol) were placed. The inside of the reaction vessel was replaced 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 aqueous alkaline solution S-A.

[0180] Next, dicarboxylic acid dichloride (16.0 mmol) of compound (14NACC) as a monomer and dicarboxylic acid dichloride (16.0 mmol) of compound (26NACC) as a monomer were dissolved in chloroform (150 mL). Thus, a chloroform solution S-B was obtained.

[0181] The chloroform solution S-B was slowly added dropwise over 110 minutes using a dropping funnel relative to the basic aqueous solution S-A. The temperature (liquid temperature) of the contents of the reaction vessel was adjusted to 15 ± 5°C, and the contents of the reaction vessel were stirred for 4 hours to perform the polymerization reaction. The upper layer (water layer) was removed from the contents of the reaction vessel using a decanter to obtain an organic layer. Next, ion exchange water (400 mL) was added to a separable flask. The obtained organic layer was added to the separable flask. Further, chloroform (400 mL) and acetic acid (2 mL) were added to the separable flask. The contents of the separable flask were stirred at room temperature (25°C) for 30 minutes. The upper layer (water layer) was removed from the contents of the separable flask using a decanter to obtain an organic layer. The obtained organic layer was washed with ion exchange water (1 L) using a separable funnel. The washing with ion exchange water was repeated 5 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 added dropwise to methanol (1 L) to obtain a precipitate. The precipitate was removed by filtration. The removed precipitate was vacuum-dried at a temperature of 70°C for 12 hours. As a result, a polyarylate resin A was obtained.

[0182] (Synthesis of polyarylate resins B to I, P, and J to N)

[0183] Each of the polyarylate resins B to I, P, and J to N was synthesized in accordance with the synthesis method of the polyarylate resin A except that the monomers in Table 5 were used at the addition rates in Table 5. In addition, the addition amount of each bisphenol monomer was set so that the total amount of the bisphenol monomers was 41.0 mmol and the bisphenol addition rates in Table 5 were achieved. For example, in the synthesis of the polyarylate resin B, the addition amount of the compound (BisB) was 38.95 mmol (= 41.0 x 95 / 100), and the addition amount of the compound (BP) was 2.05 mmol (= 41.0 x 5 / 100). Also, the addition amount of each dicarboxylic acid monomer was set so that the total amount of the dicarboxylic acid monomers was 32.0 mmol and the dicarboxylic acid addition rates in Table 5 were achieved. For example, in the synthesis of the polyarylate resin B, the addition amount of the compound (14NACC) was 16.0 mmol (= 32.0 x 50 / 100), and the addition amount of the compound (26NACC) was 16.0 mmol (= 32.0 x 50 / 100).

[0184] The obtained polyarylate resins A to I, P, and J to N were measured for 1 H-NMR spectra using a deuterated chloroform as a solvent. Tetramethylsilane (TMS) was used as an internal standard. The 1 H-NMR spectrum of a representative example, the polyarylate resin H, among the polyarylate resins A to I, P, and J to N is shown in Figure 7 . The obtained polyarylate resins A to I, P, and J to N were measured for 1The chemical shifts read in the H-NMR spectrum confirmed that the polyarylate resin H was obtained. The polyarylate resins A to G, I, P, and J to N were also confirmed to be obtained by the same method.

[0185] <Preparation of the polyarylate resin O>

[0186] The polyarylate resin O involved in the comparative example was prepared. The polyarylate resin O is represented by the following formula (O). In formula (O), the right lower number of the repeating unit from the bisphenol indicates the content ratio (unit: %) of the repeating unit from the bisphenol with respect to the total number of the repeating units from bisphenols contained in the polyarylate resin O. Also, in formula (O), the right lower number of the repeating unit from the dicarboxylic acid indicates the content ratio (unit: %) of the repeating unit from the dicarboxylic acid with respect to the total number of the repeating units from dicarboxylic acids contained in the polyarylate resin O. The polyarylate resin O has a terminal group, which is a terminal group from 2,6-dimethylphenol. The viscosity average molecular weight of the polyarylate resin O was 54400.

[0187]

[0188] <Measurement of the viscosity average molecular weight>

[0189] The viscosity average molecular weight of the polyarylate resin was measured in accordance with JIS (Japanese Industrial Standards) K7252-1:2016. The measured viscosity average molecular weights are shown in Table 5.

[0190] <Manufacture of the layered photoreceptor>

[0191] (Manufacture of the layered photoreceptor (A-1))

[0192] First, the intermediate layer was formed. A surface-treated titanium oxide (Tayca Corporation, "Trial Production Sample SMT-A", number average primary particle diameter 10 nm) was prepared. The surface-treated titanium oxide was surface-treated with alumina and silica, and then surface-treated with polymethylhydrogen siloxane while being wet-dispersed, and the thus obtained titanium oxide was SMT-A. Then, 2 parts by mass of SMT-A, a polyamide resin (Toray Industries, Inc., "AMILAN (registered trademark) CM8000", a tetrapolymer polyamide resin of polyamide 6, polyamide 12, polyamide 66 and polyamide 610), 1 part 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 having a pore diameter of 5 μm. Then, the intermediate layer coating liquid was coated on the surface of a conductive substrate using a dip coating method. An aluminum drum support was used as the conductive substrate. Next, the coated intermediate layer coating liquid was dried at 130°C for 30 minutes to form an intermediate layer (film thickness: 1 μm) on the conductive substrate.

[0193] Next, the charge generation layer was formed. Specifically, 1.5 parts by mass of Y-type titanium phthalocyanine as a charge generating agent, 1.0 part by mass of a polyvinyl acetal resin (S-LEC BX-5, Chuo 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 charge generation layer coating liquid. The charge generation layer coating liquid was filtered using a filter having a pore diameter of 3 μm. The obtained filtrate was coated on the intermediate layer using a dip coating method and dried at 50°C for 5 minutes. Thus, a charge generation layer (film thickness: 0.3 μm) was formed on the intermediate layer.

[0194] Next, a charge transport layer was formed. Specifically, 50.00 parts by mass of a hole transport agent (HTM-1), 100.00 parts by mass of the polyarylate resin A as a binding resin, 5.00 parts by mass of m-terphenyl, 0.05 parts by mass of silicone oil ("KF96-50cs" manufactured by Shin-Etsu Chemical Co., Ltd., silicone oil having a polydimethylsiloxane structure), 595.00 parts by mass of tetrahydrofuran, and 105.00 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 to the charge generation layer using a dip coating method, and drying was performed using a drying oven for 70 minutes. The heating conditions of the drying oven were: a starting temperature of 60°C, a final reaching temperature of 130°C, and a temperature increase rate of 1°C / min. In this way, a charge transport layer (film thickness: 20 μm) was formed on the charge generation layer, and a layered photoreceptor (A-1) was obtained. In the layered photoreceptor (A-1), the intermediate layer was on the conductive base, the charge generation layer was on the intermediate layer, and the charge transport layer was on the charge generation layer.

[0195] (Manufacture of layered photoreceptors (A-2) to (A-15) and (B-1) to (B-6))

[0196] Layered photoreceptors (A-2) to (A-15) and (B-1) to (B-6) were each manufactured in accordance with the method for manufacturing the layered photoreceptor (A-1), except that the hole transport agent and the polyarylate resin in Table 7 were used.

[0197] <Assessment of solubility in a solvent>

[0198] An evaluation liquid was obtained by stirring 3 g of the polyarylate resin and tetrahydrofuran in an amount such that the concentration of the polyarylate resin became 15% by mass at 22°C for 60 minutes. The evaluation liquid was confirmed by the naked eye, and the solubility of the polyarylate resin in the tetrahydrofuran as the solvent was assessed in accordance with the following criteria. A polyarylate resin that was assessed as A or B was determined to have good solubility in the solvent, and a polyarylate resin that was assessed as C was determined to have poor solubility in the solvent. The results of the assessment of each polyarylate resin are shown in Table 6.

[0199] (Criteria for assessment of solubility in a solvent)

[0200] A: The polyarylate resin was completely dissolved in the tetrahydrofuran, and no clouding or gelation of the evaluation liquid was confirmed.

[0201] B: Clouding of the evaluation liquid was confirmed, but no gelation of the evaluation liquid was confirmed.

[0202] C: Gelation of the evaluation liquid was confirmed.

[0203] <Assessment of charging characteristics>

[0204] The charging characteristics of the photoreceptors were evaluated under conditions of 25°C and 50% RH. Specifically, a drum-type photosensitivity tester (manufactured by GENTEC Corporation) was used to charge the surface of the photoreceptors under conditions of a charging current of -10 μA flowing through the charger and a rotational speed of 31 rpm. The surface potential of the charged photoreceptors was measured. The measured surface potential is recorded as the charged potential of the photoreceptor (V0, unit -V). The charged potentials of each photoreceptor are shown in Table 7. A charged potential between -700V and -650V indicates that the photoreceptor possesses sufficient charging characteristics for practical use.

[0205] <Evaluation of initial sensitivity characteristics and repeat sensitivity characteristics>

[0206] The photosensitivity characteristics of the photoreceptor were evaluated under conditions of 25°C and 50% RH. Specifically, a drum photosensitivity tester (manufactured by GENTEC Corporation) was used, in which the photoreceptor was rotated while being repeatedly charged and exposed. The charging condition was to bring the surface potential of the photoreceptor to -600V. The exposure condition involved using a bandpass filter to extract monochromatic light (wavelength 780nm, exposure dose 0.8μJ / cm²) from the halogen lamp light. 2 The light is shone onto the surface of the photoreceptor. On the 10th rotation of the photoreceptor, 80 milliseconds after the start of exposure (monochromatic light), the surface potential of the photoreceptor is measured, and this is taken as the post-exposure potential (V10) after the 10th rotation. L (Unit: V). Furthermore, at the 1860th rotation of the photoreceptor, 80 milliseconds after the start of exposure (monochromatic light), the surface potential of the photoreceptor is measured as the post-exposure potential (V) after the 1860th rotation. L (Unit: V). The post-exposure potentials for the 10th and 1860th exposures of each photoreceptor are shown in Table 7. Based on the post-exposure potential of the 10th exposure, the initial sensitivity characteristics of the photoreceptor are evaluated according to the following criteria. Furthermore, based on the post-exposure potential of the 1860th exposure, the repeatability sensitivity characteristics of the photoreceptor are evaluated according to the following criteria.

[0207] (Evaluation criteria for initial photosensitivity characteristics)

[0208] Good: The absolute value of the potential after the 10th exposure is below 90V.

[0209] Defect: The absolute value of the potential exceeds 90V after exposure on the 10th ring.

[0210] (Evaluation criteria for repeatability characteristics)

[0211] Good: The absolute value of the potential after exposure ring 1860 is below 130V.

[0212] Good: The absolute value of the post-exposure potential at the 1860th revolution was 130 V or less.

[0213] < Abrasion Resistance Evaluation >

[0214] The charge transport layer prepared in the above-mentioned "Manufacture of the layered photoreceptor" was coated on a polypropylene sheet (thickness: 0.3 mm) wound on an aluminum pipe (diameter: 78 mm) using the coating solution. The coated charge transport layer was dried for 70 minutes using a drying oven. The heating conditions of the drying oven were: starting temperature 60°C, final reaching temperature 130°C, and temperature increasing rate 1°C / min. By drying, a polypropylene sheet on which the charge transport layer (film thickness 30 μm) was formed was produced. Next, the charge transport layer was peeled off from the polypropylene sheet. The peeled charge transport layer was attached to a card-shaped member (TABER Co., Ltd. "S-36"). The mass M A of the card-shaped member to which the charge transport layer was attached was measured. Then, the card-shaped member was mounted on a rotating stage of a rotating abrasion tester (Toyo Seiki Jiki Kogyo Co., Ltd.). Next, the rotating stage was rotated at 60 rpm for 1000 revolutions in a state where a grinding wheel (TABER Co., Ltd. "CS-10") of a load 500 gf was placed on the photoreceptor on the card-shaped member. By this, the charge transport layer on the rotating stage was abraded. After the abrasion, the mass M B of the card-shaped member to which the charge transport layer was attached was measured again. Next, the mass change of the charge transport layer before and after the abrasion, that is, the abrasion amount (= M A - M B , unit: mg) was calculated. The measured abrasion amount is shown in Table 7. From the abrasion amount, the abrasion resistance of the photoreceptor was evaluated in accordance with the following criteria.

[0215] (Criteria for Evaluation of Abrasion Resistance)

[0216] Good: The abrasion amount was 7.5 mg or less.

[0217] Poor: The abrasion amount exceeded 7.5 mg.

[0218] In Table 6, "Resin" indicates a polyarylate resin, and "Solubility" indicates an evaluation of solubility in a solvent. In Table 7, the meanings of the terms are as follows. "Photoreceptor" indicates a layered photoreceptor. "HTM" indicates a hole transport agent. "Resin" indicates a polyarylate resin. "Charging" indicates an evaluation of charging characteristics. "Sensitivity" indicates an evaluation of sensitivity characteristics. "V0" indicates a charging potential. "V L at the 10th revolution" in the column of the "10th revolution" indicates a post-exposure potential of the photoreceptor at the 10th revolution. "V L"Exposure potential at 1860th revolution" means the potential of the photoreceptor after exposure at the 1860th revolution. "Coating liquid cannot be prepared" means that the polyarylate resin is not dissolved in the solvent used for forming the coating liquid for the charge transport layer, and the coating liquid for the charge transport layer cannot be prepared.

[0219] [Table 6]

[0220] Resin Solubility A A B A C A D A E A F A G A H A I A P A J C K A L A M C N A O A

[0221] [Table 7]

[0222]

[0223] As shown in Table 5, polyarylate resins J to N are not resins included in the polyarylate resin (PA). Also, as shown in formula (O), polyarylate resin O is not a resin included in the polyarylate resin (PA). Therefore, as shown in Table 6 and Table 7, the solubility of polyarylate resins J and M in the solvent is poor, and the coating liquid for the charge transport layer cannot be prepared using polyarylate resins J and M, and the photoreceptive layer (more specifically, the charge transport layer) cannot be formed. Also, as shown in Table 7, in the case where the photoreceptive layer contains polyarylate resins K and L, the wear resistance of the photoreceptor is not improved. Also, as shown in Table 7, in the case where the photoreceptive layer contains polyarylate resin N, the repeated photosensitivity characteristics of the photoreceptor are not improved. Also, as shown in Table 7, in the case where the photoreceptive layer contains polyarylate resin O, the wear resistance and the repeated photosensitivity characteristics of the photoreceptor are not improved.

[0224] On the other hand, as shown in Table 5, polyarylate resins A to I and P are resins included in the polyarylate resin (PA). Therefore, as shown in Table 6, the solubility of polyarylate resins A to I and P in the solvent is good. Also, as shown in Table 7, in the case where the photoreceptive layer contains polyarylate resins A to I and P, the repeated photosensitivity characteristics and the wear resistance of the photoreceptor are improved. Also, as shown in Table 7, in the case where the photoreceptive layer contains polyarylate resins A to I and P, the charging characteristics and the initial photosensitivity characteristics of the photoreceptor are not impaired, and the repeated photosensitivity characteristics and the wear resistance of the photoreceptor are improved.

[0225] As described above, the polyarylate resin of the present application including polyarylate resins A to I and P exhibits excellent solubility in the solvent, and in the case where the photoreceptive layer contains such a polyarylate resin, the repeated photosensitivity characteristics and the wear resistance of the photoreceptor can be improved. Also, the photoreceptor of the present application including the layered photoreceptors (A-1) to (A-15) exhibits that the photoreceptive layer can be formed well, and the repeated photosensitivity characteristics and the wear resistance can be improved.

[0226] [Industrial applicability]

[0227] The photoreceptor according to the present application can be used in an image forming apparatus.

Claims

1. A polyarylate resin, having a residue represented by formulae (1), (2), (3), and (4), a content ratio of the residue represented by formula (3) is more than 0% and 19% or less relative to the total number of the residue represented by formula (1) and the residue represented by formula (3), having a repeating unit in which the residue represented by formula (1) and the residue represented by formula (2) or formula (4) are bonded to each other adjacently, and a repeating unit in which the residue represented by formula (3) and the residue represented by formula (2) or formula (4) are bonded to each other adjacently, In the formula (1), R 1 and R 2 each independently represent a hydrogen atom or a methyl group, X is a divalent group represented by formula (X1) or (X2), in the formula (2), W is a divalent group represented by formula (W1) or (W2), in the formula (X1), t represents an integer of 1 or more and 3 or less, and * represents a bond, In the formula (X2), R 3 and R 4 represent a hydrogen atom or a C1-C4 alkyl group, R 3 and R 4 represent different groups from each other, and * represents a binding bond. in the formulae (W1) and (W2), * represents a bond.

2. The polyarylate resin according to claim 1, characterized in that In the formula (1), R 1 and R 2 represent a methyl group, and X is a divalent group represented by the formula (X1).

3. The polyarylate resin according to claim 1, characterized in that the residue represented by formula (1) is a residue represented by formula (1-1), 4. The polyarylate resin according to claim 1, characterized in that the residue represented by formula (1) is a residue represented by formula (1-1), and the residue represented by formula (2) is a residue represented by formula (2-1), 5. The polyarylate resin according to claim 1, characterized in that the residue represented by formula (1) is a residue represented by formula (1-1), and the residue represented by formula (2) is a residue represented by formula (2-2), 6. The polyarylate resin according to claim 1, characterized in that In the formula (1), R 1 and R 2 represent a hydrogen atom, and X is a divalent group represented by the formula (X2).

7. The polyarylate resin according to claim 1, characterized in that the residue represented by formula (1) is a residue represented by formula (1-2), 8. The polyarylate resin according to claim 1, characterized in that the residue represented by formula (1) is a residue represented by formula (1-2), and the residue represented by formula (2) is a residue represented by formula (2-1), 9. An electrophotographic photoreceptor, comprising a conductive base and a photosensitive layer, the photosensitive layer contains a charge generating agent, a hole transporting agent, and a binder resin, the binder resin contains the polyarylate resin according to claim 1.

10. The electrophotographic photoreceptor according to claim 9, characterized in that the hole transporting agent contains a compound represented by formula (20), (21), or (22), in the formula (20), R 21 and R 22 each independently represent a C1-C8 alkyl group, a phenyl group or a C1-C8 alkoxy group, R 23 ~R 29 each independently represent a hydrogen atom, a C1-C8 alkyl group, a C1-C8 alkoxy group, a phenyl group having a C1-C8 alkyl substituent or an unsubstituted phenyl group, R 25 ~R 29 of which 2 adjacent ones do not bond to each other or bond to each other to form a ring, a1 and a2 each independently represent an integer of 0 or more but 5 or less, In the formula (21), R 31 ~R 36 each independently represents a C1-C8 alkyl group or a phenyl group, R 37 and R 38 each independently represents a hydrogen atom, a C1-C8 alkyl group or a phenyl group, b1, b2, b3 and b4 each independently represent an integer of 0 or more and 5 or less, b5 and b6 each independently represent an integer of 0 or more and 4 or less, d and e each independently represent 0 or 1, In the formula (22), R 41 ~R 46 each independently represents a C1-C8 alkyl group, a phenyl group or a C1-C8 alkoxy group, f1, f2, f4and f5each independently represent an integer of 0 or more but 5 or less, and f3and f6each independently represent an integer of 0 or more but 4 or less.

11. The electrophotographic photoreceptor according to claim 9, characterized in that the hole transporting agent contains a compound represented by formula (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), or (HTM-6), 12. The electrophotographic photoreceptor according to claim 9, characterized in that the photosensitive layer comprises a charge generating layer and a charge transporting layer, the charge generating layer contains the charge generating agent, and the charge transporting layer contains the hole transporting agent and the binder resin, the charge transporting layer is one layer and is the outermost surface layer.

Images