Electrophotographic photoreceptor

Abstract

This electrophotographic photosensitive body comprises a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transport agent, a first resin, and a second resin. The first resin is contained in the same layer in which the second resin is contained. The content of the second resin with respect to the total mass of the first resin and the second resin is 1% to 3%. The first resin has repeating units represented by formulae (1), (2), (3), and (4). The content of the repeating unit represented by formula (3) with respect to the total number of repeating units represented by formulae (1) and (3) is more than 0% and less than 20%. The second resin is a polyester resin that is different from the first resin.

Description

[Technical field]

[0001] The present invention relates to 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 investigations that the electrophotographic photoreceptor described in Patent Document 1 is insufficient in terms of increasing the solubility of the binder resin in a solvent for forming the photosensitive layer to thereby favorably form the photosensitive layer, in terms of abrasion resistance, and in terms of suppressing peeling of the photosensitive layer (hereinafter, sometimes referred to as film peeling).

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photoreceptor in which a photosensitive layer can be favorably formed, which has excellent abrasion resistance, and which can suppress film peeling. [Means for solving the problem]

[0008] The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transport agent, a first resin, and a second resin. The first resin is contained in the same layer as the second resin. The content of the second resin with respect to the total mass of the first resin and the second resin is 1% or more and 3% or less. The first resin has repeating units represented by formulas (1), (2), (3), and (4). The content of the repeating unit represented by formula (3) with respect to the total number of repeating units represented by formulas (1) and (3) is more than 0% and less than 20%. The second resin is a polyester resin different from the first resin.

[0009] [ka]

[0010] In the formula (1), R 1 and R 2 each independently represents 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).

[0011] [ka]

[0012] In the formula (X1), t represents an integer of 1 to 3, and * represents a bond. 3 and R 4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R 3 and R 4 represent different groups, and * represents a bond.

[0013] [ka]

[0014] In the formulae (W1) and (W2), * represents a bond. Effect of the Invention

[0015] The electrophotographic photoreceptor of the present invention can form a good photosensitive layer, has excellent abrasion resistance, and can suppress film peeling. [Brief description of the drawings]

[0016] [Figure 1] 1 is a partial cross-sectional view of a multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention. [Diagram 2] 1 is a partial cross-sectional view of a multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention. [Diagram 3] 1 is a partial cross-sectional view of a multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention. [Figure 4] 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention. [Diagram 5] 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention. [Figure 6] 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to an embodiment of the present invention. [Figure 7] This is a 1H-NMR spectrum of resin (1-H). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 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 appropriate for overlapping parts, the gist of the invention is not limited thereto. Hereinafter, the compound and its derivatives may be collectively referred to by adding "system" after the compound name. In addition, when the compound name is followed by "system" to represent the name of a polymer, it means that the repeating unit of the polymer is derived from the compound or its derivative. 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. Unless otherwise specified, the glass transition temperature (Tg) is a value measured according to "JIS (Japanese Industrial Standards) K7121-2012" using a differential scanning calorimeter (Seiko Instruments Inc.'s "DSC-6220"). In an endothermic curve (vertical axis: heat flow (DSC signal), horizontal axis: temperature) measured by a differential scanning calorimeter, the temperature of the inflection point due to glass transition (specifically, the temperature of the intersection of the extrapolated line of the baseline and the extrapolated line of the falling line) corresponds to the glass transition point. The measured value of the number average molecular weight (Mn) is a value measured using gel permeation chromatography unless otherwise specified. The measured values ​​of the acid value and hydroxyl value are values ​​measured in accordance with "JIS (Japanese Industrial Standards) K0070-1992" unless otherwise specified.

[0018] Next, the substituents used in the present 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).

[0019] Unless otherwise specified, the alkyl group having 1 to 8 carbon atoms, the alkyl group having 1 to 6 carbon atoms, the alkyl group having 1 to 4 carbon atoms, the alkyl group having 1 to 3 carbon atoms, and the alkyl group having 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, alkyl groups having 1 to 4 carbon atoms, alkyl groups having 1 to 3 carbon atoms, and alkyl groups having 3 carbon atoms are the groups having the corresponding number of carbon atoms among the groups mentioned as examples of alkyl groups having 1 to 8 carbon atoms.

[0020] 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.

[0021] 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 include diyl group, 1-methylpentanediyl group, 2-methylpentanediyl group, 3-methylpentanediyl group, 4-methylpentanediyl group, 1,1-dimethylbutanediyl group, 1,2-dimethylbutanediyl group, 1,3-dimethylbutanediyl group, 2,2-dimethylbutanediyl group, 2,3-dimethylbutanediyl group, 3,3-dimethylbutanediyl group, 1,1,2-trimethylpropanediyl group, 1,2,2-trimethylpropanediyl group, 1-ethylbutanediyl group, 2-ethylbutanediyl group, and 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 described as examples of the alkanediyl group having 1 to 6 carbon atoms. The substituents used in this specification have been described above.

[0022] [Electrophotographic photoreceptor] An embodiment of the present invention relates to an electrophotographic photoreceptor (hereinafter, referred to as photoreceptor). The photoreceptor of this embodiment includes a conductive substrate and a photosensitive layer. The photosensitive layer is preferably provided as the outermost layer of the photoreceptor. The photosensitive layer contains a charge generating agent, a hole transport agent, a first resin, and a second resin. In order to improve abrasion resistance and suppress film peeling, the outermost layer of the photoreceptor preferably contains at least the first resin and the second resin.

[0023] The photoreceptor is, for example, a single-layer type electrophotographic photoreceptor (hereinafter, may be referred to as a single-layer type photoreceptor) or a multi-layer type electrophotographic photoreceptor (hereinafter, may be referred to as a multi-layer type photoreceptor).

[0024] <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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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 the first resin and the second resin as the outermost layer, the abrasion resistance of the laminated photoreceptor 1 is further improved and film peeling is further suppressed.

[0030] 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.

[0031] The charge transport layer 3b contains a hole transport agent, a first resin, and a second resin. The charge transport layer 3b may contain an additive, if 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 laminated photoreceptor 1 has been described above with reference to FIGS. 1 to 3.

[0032] <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.

[0033] 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."

[0034] 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.

[0035] 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.

[0036] 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 the first resin and the second resin as the outermost layer, the wear resistance of the single-layer photoreceptor 10 is further improved and film peeling is further suppressed.

[0037] The single-layered photosensitive layer 3c contains a charge generating material, a hole transport material, a first resin, and a second resin. The single-layered photosensitive layer 3c may further contain an electron transport material as required. The single-layered photosensitive layer 3c may contain an additive as required.

[0038] 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.

[0039] <First resin> The first resin is contained in the photosensitive layer as, for example, a binder resin. The first resin is a polyarylate resin. The first resin has repeating units represented by formulas (1), (2), (3), and (4). 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 20%.

[0040] [ka]

[0041] In formula (1), R 1 and R 2 each independently represents 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).

[0042] [ka]

[0043] In formula (X1), t represents an integer of 1 to 3, and * represents a bond. 3 and R 4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R 3 and R 4 represent different groups, and * represents a bond.

[0044] [ka]

[0045] In formulae (W1) and (W2), * represents a bond.

[0046] Hereinafter, the repeating units represented by formulas (1), (2), (3), and (4) may be referred to as "repeating units (1), (2), (3), and (4)," respectively. The content of repeating unit (3) relative to the total number of repeating units (1) and (3) may be referred to as "content (3)." A resin having repeating units (1), (2), (3), and (4) and having a content (3) greater than 0% and less than 20% may be referred to as "resin (PA)."

[0047] The resin (PA) has excellent solubility in the solvent used to form the photosensitive layer. By using the resin (PA) with excellent solubility as the first resin, the photosensitive layer of the photoreceptor can be formed satisfactorily. In addition, by including the resin (PA) as the first resin, the wear resistance of the photoreceptor is improved.

[0048] The content (3) is the percentage of the number N3 of repeating units (3) relative to the total number N1 of repeating units (1) and the number N3 of repeating units (3) contained in the resin (PA) (i.e., 100×N3 / (N1+N3)). When the content (3) is less than 20%, the solubility of the resin (PA) in a solvent is improved. When the content (3) is greater than 0%, i.e., when the content (3) is not 0%, the abrasion resistance of the photoreceptor is improved when the resin (PA) is contained in the photosensitive layer. The content (3) is preferably 1% or more, and more preferably 5% or more. Moreover, the content (3) is preferably 19% or less, and more preferably 10% or less.

[0049] The content of the repeating unit (4) relative to the total number of the repeating units (2) and (4) is greater than 0% and less than 100%. The content of the repeating unit (4) relative to the total number of the repeating units (2) and (4) may be referred to as "content (4)". The content (4) is the percentage of the number N4 of the repeating units (4) relative to the sum of the number N2 of the repeating units (2) and the number N4 of the repeating units (4) contained in the resin (PA) (i.e., 100×N4 / (N2+N4)). The content (4) is greater than 0%, i.e., the content (4) is not 0%, so the resin (PA) contains the repeating unit (4). The presence of the repeating unit (4) improves the solubility of the resin (PA) in a solvent, and when the resin (PA) is contained in a photosensitive layer, the wear resistance of the photoreceptor is improved. On the other hand, the content (4) is less than 100%, i.e., the content (4) is not 100%, so the resin (PA) has a repeating unit (2). By having the repeating unit (2), when the resin (PA) is contained in the photosensitive layer, the abrasion resistance of the photoreceptor is improved. The content (4) is preferably 1% or more, more preferably 10% or more, and even more preferably 35% or more. In addition, the content (4) is preferably 99% or less, more preferably 80% or less, and even more preferably 65% ​​or less.

[0050] The contents (3) and (4) were determined by using a proton nuclear magnetic resonance spectrometer. 1 The H-NMR spectrum was measured and 1 It can be calculated from the ratio of peaks characteristic of each repeating unit in the H-NMR spectrum.

[0051] In formula (1), R 1 and R 2 preferably represents a methyl group.

[0052] In formula (X1), t preferably represents 2.

[0053] In formula (X2), R 3 represents a hydrogen atom and R 4 represents a methyl group, an ethyl group, or an alkyl group having 3 carbon atoms; R3 represents a methyl group and R 4 represents an ethyl group or an alkyl group having 3 carbon atoms, or R 3 represents an ethyl group and R 4 Preferably, R represents an alkyl group having 3 carbon atoms. 3 represents a methyl group and R 4 More preferably, represents an ethyl group.

[0054] The bond represented by * in formulae (X1) and (X2) is bonded to the carbon atom to which X in formula (1) is bonded. The bond represented by * in formulae (W1) and (W2) is bonded to the carbon atom to which W in formula (2) is bonded.

[0055] Examples of the repeating unit (1) include repeating units represented by formulas (1-1), (1-2), and (1-3) (hereinafter, these may be referred to as repeating units (1-1), (1-2), and (1-3), respectively).

[0056] [ka]

[0057] The repeating unit (2) is a repeating unit represented by formula (2-1) or (2-2) (hereinafter, these may be referred to as repeating units (2-1) and (2-2), respectively).

[0058] [ka]

[0059] In one embodiment, in formula (1), R 1 and R 2It is preferable that X represents a methyl group, and X represents a divalent group represented by the 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 it is further preferable that the repeating unit (1) is the repeating unit (1-1) and the repeating unit (2) is the repeating unit (2-2).

[0060] In another embodiment, in formula (1), R 1 and R 2 It is preferable that represents a hydrogen atom, and X represents a divalent group represented by formula (X2). It is more preferable that the repeating unit (1) is a repeating unit (1-2). It is further preferable that the repeating unit (1) is a repeating unit (1-2) and the repeating unit (2) is a repeating unit (2-1); or it is more preferable that the repeating unit (1) is a repeating unit (1-2) and the repeating unit (2) is a repeating unit (2-2). By including the resin (PA) described in another embodiment in the photosensitive layer, the abrasion resistance of the photoreceptor is further improved.

[0061] The resin (PA) may have a terminal group. Examples of the terminal group that the resin (PA) has 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)).

[0062] [ka]

[0063] 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.

[0064] 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.

[0065] The * in formulae (T-1), (T-2), (T-DMP), and (T-PFH) represents a bond. The bond represented by the * in 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 resin (PA).

[0066] In order to further improve the abrasion resistance of the photoreceptor, it is preferable that the first resin (PA) has a terminal group having a halogen atom. For the same reason, in formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), and it is more preferable that the resin (PA) has a terminal group having a halogen atom.

[0067] 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).

[0068] Suitable examples of the resin (PA) include resins (PA-1) to (PA-4) shown in Table 1. The resins (PA-1) to (PA-4) each have the repeating units (1) to (4) shown in Table 1. In Table 1 and Table 2 described later, units (1) to (4) respectively represent the repeating units (1) to (4).

[0069] [Table 1]

[0070] Further suitable examples of the resin (PA) include the resins (PA-a) to (PA-h) shown in Table 2. The resins (PA-a) to (PA-h) each have the repeating units (1) to (4) shown in Table 2 and the terminal groups shown in Table 2.

[0071] [Table 2]

[0072] In the 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 "number of repeating units derived from dicarboxylic acid = number of repeating units derived from bisphenol + 1". The resin (PA) may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer.

[0073] The resin (PA) may have only one type of repeating unit (1) as the repeating unit (1), or may have two or more (e.g., two) types of repeating units (1).The resin (PA) may have only one type of repeating unit (2) as the repeating unit (2), or may have two types of repeating units (2).

[0074] The resin (PA) may further have repeating units other than the repeating units (1) to (4) as repeating units. However, in order to improve the solubility in a solvent and to improve the abrasion resistance of a photoreceptor when the resin (PA) is contained in a photosensitive layer, the content of the repeating units (1) to (4) in the total number of repeating units contained in the resin (PA) is preferably 90% or more, more preferably 95% or more, even more preferably 99% or more, and particularly preferably 100%. That is, it is particularly preferable that the resin (PA) has only the repeating units (1) to (4) as repeating units.

[0075] In order to improve solubility in a solvent, the content of the repeating unit (3) in the total number of repeating units derived from bisphenol contained in the resin (PA) is preferably 20% or less, and more preferably less than 20%.

[0076] The first resin may be only one type of resin (PA), or may be two or more types of resin (PA).

[0077] The viscosity average molecular weight of the 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 resin (PA) is 10,000 or more, the abrasion resistance of the photoreceptor is improved when the resin (PA) is contained in the photosensitive layer of the photoreceptor. On the other hand, the viscosity average molecular weight of the 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 resin (PA) is 80,000 or less, the solubility of the resin (PA) in a solvent is improved. The viscosity average molecular weight of the resin (PA) is measured according to JIS (Japanese Industrial Standards) K7252-1:2016.

[0078] Next, the method for producing the resin (PA) will be described. For example, the method for producing the 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 the polycondensation, a known synthesis method (for example, solution polymerization, melt polymerization, or interfacial polymerization) can be adopted.

[0079] 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. W in formula (DC-2) has the same meaning as W in formula (2).

[0080] [ka]

[0081] In the production of resin (PA), the content (3) can be adjusted by changing the amount (unit: mole) of compound (BP-3) added relative to the total amount (unit: mole) of compounds (BP-1) and (BP-3) added. Also, the content (4) can be adjusted by changing the amount (unit: mole) of compound (DC-4) added relative to the total amount (unit: mole) of compounds (DC-2) and (DC-4) added.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] <Second resin> By including the second resin in the photosensitive layer, the photosensitive layer is improved in adhesion to the surface with which it is in contact, suppressing peeling of the film, and by including the second resin in the photosensitive layer, the sensitivity characteristics of the photoreceptor are also improved.

[0086] The second resin is a polyester resin. The second resin is a polyester resin different from the first resin, i.e., a polyester resin other than resin (PA). The second resin is different from the first resin in that the second resin does not satisfy at least one condition selected from the group consisting of the condition that the second resin has a repeating unit (1), the condition that the second resin has a repeating unit (2), the condition that the second resin has a repeating unit (3), the condition that the second resin has a repeating unit (4), and the condition that the content (3) is greater than 0% and less than 20%. Alternatively, the second resin is different from the first resin in that the Vickers hardness of the second resin is different from the Vickers hardness of the first resin.

[0087] The polyester resin, which is the second resin, is obtained by polycondensation of one or more polyhydric alcohol monomers and one or more polycarboxylic acid monomers. The polyester resin, which is the second resin, is a polymer of one or more polyhydric alcohol monomers and one or more polycarboxylic acid monomers.

[0088] Examples of polyhydric alcohol monomers include diol monomers, bisphenol monomers, and trihydric or higher alcohol monomers.

[0089] Examples of diol monomers include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 2-butene-1,4-diol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,4-benzenediol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0090] Examples of bisphenol monomers include bisphenol A, hydrogenated bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A.

[0091] Examples of trihydric or higher alcohol monomers include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

[0092] Examples of polycarboxylic acid monomers include dicarboxylic acid monomers and tricarboxylic or higher carboxylic acid monomers.

[0093] Examples of divalent carboxylic acid monomers include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, 5-sulfoisophthalic acid, 5-sodium sulfoisophthalate, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, succinic acid, alkyl succinic acid, and alkenyl succinic acid. Examples of alkyl succinic acid include n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, and isododecyl succinic acid. Examples of alkenyl succinic acid include n-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid, and isododecenyl succinic acid.

[0094] Examples of trivalent or higher carboxylic acid monomers include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid.

[0095] The glass transition point of the polyester resin as the second resin is preferably 45°C or more and 100°C or less, more preferably 47°C or more and 95°C or less. The number average molecular weight of the polyester resin as the second resin is preferably 10000 or more and 30000 or less, more preferably 16000 or more and 17000 or less. The hydroxyl value of the polyester resin as the second resin is preferably 1 mgKOH / g or more and 10 mgKOH / g or less, more preferably 6 mgKOH / g or more and 7 mgKOH / g or less. The acid value of the polyester resin as the second resin is preferably 0.1 mgKOH / g or more and 10 mgKOH / g or less, more preferably 0.1 mgKOH / g or more and 5 mgKOH / g or less, and even more preferably 0.1 mgKOH / g or more and less than 2 mgKOH / g.

[0096] The first resin is contained in the same layer as the second resin. When the photoreceptor is a laminated photoreceptor, the first resin and the second resin are contained in the same layer, that is, the charge transport layer. When the photoreceptor is a single-layer photoreceptor, the first resin and the second resin are contained in the same layer, that is, the single-layer photosensitive layer. The photosensitive layer may contain one type of second resin, or may contain two or more types of second resins.

[0097] <Second resin content> The content of the second resin relative to the total mass of the first resin and the second resin is 1% or more and 3% or less. Hereinafter, the "content of the second resin relative to the total mass of the first resin and the second resin" may be referred to as the "second resin content". The second resin content is calculated by the formula "second resin content = 100 x mass of the second resin / (mass of the first resin + mass of the second resin)". When the photosensitive layer contains two or more types of first resins, the mass of the first resin is the total mass of the two or more types of first resins. When the photosensitive layer contains two or more types of second resins, the mass of the second resin is the total mass of the two or more types of second resins.

[0098] When the content of the second resin is 1% or more, peeling of the film of the photoconductor is suppressed, and when the content of the second resin is 3% or less, the wear resistance of the photoconductor is improved.

[0099] <Vickers hardness> In this embodiment, the Vickers hardness refers to the Vickers hardness at 45° C. The Vickers hardness is measured by a method conforming to Japanese Industrial Standards (JIS) Z2244.

[0100] In order to improve the adhesion of the photosensitive layer to the surface with which it is in contact and to suppress peeling, it is preferable that the Vickers hardness of the second resin is lower than that of the first resin. The second resin with a low Vickers hardness imparts appropriate flexibility to the photosensitive layer, thereby increasing the adhesion of the photosensitive layer to the surface with which it is in contact.

[0101] In order to prevent the film from peeling off from the photoreceptor, the Vickers hardness of the second resin is preferably 10.0 HV or more and 20.0 HV or less, and more preferably 15.5 HV or more and 16.5 HV or less.

[0102] In order to prevent film peeling of the photoreceptor, the Vickers hardness of the first resin is preferably 25.0 HV or more and 40.0 HV or less, more preferably 30.0 HV or more and 35.0 HV or less, even more preferably 30.5 HV or more and 33.5 HV or less, and even more preferably 33.0 HV or more and 33.5 HV or less.

[0103] In order to suppress the peeling of the photoreceptor, the Vickers hardness of the photosensitive layer is preferably 24.0HV to 40.0HV, more preferably 29.0HV to 34.0HV, even more preferably 30.0HV to 33.5HV, and even more preferably 33.0HV to 33.5HV. In the case of a multi-layered photoreceptor, the Vickers hardness of the charge transport layer corresponds to the Vickers hardness of the photosensitive layer. In the case of a single-layered photoreceptor, the Vickers hardness of the single-layered photosensitive layer corresponds to the Vickers hardness of the photosensitive layer.

[0104] In order to prevent the film from peeling off of the photoconductor, the difference (H1-H2) between the Vickers hardness H1 of the first resin and the Vickers hardness H2 of the second resin is preferably 14.5HV or more, more preferably 15.0HV or more, even more preferably 15.5HV or more, even more preferably 16.0HV or more, even more preferably 16.5HV or more, and particularly preferably 16.6HV or more. In order to prevent the film from peeling off of the photoconductor, the difference (H1-H2) between the Vickers hardness H1 of the first resin and the Vickers hardness H2 of the second resin is preferably 18.0HV or less, more preferably 17.5HV or less, even more preferably 17.1HV or less, and even more preferably 17.0HV or less.

[0105] In order to prevent the film from peeling off of the photoconductor, it is preferable that the Vickers hardness of the photosensitive layer is lower than the Vickers hardness of the first resin. P Difference from (H1-H P ) is preferably 0.2 HV or more and 1.0 HV or less. In order to prevent the film of the photoconductor from peeling off, the Vickers hardness H1 of the first resin and the Vickers hardness H P Difference from (H1-H P It is also preferred that the range of two values ​​selected from the group consisting of 0.2HV, 0.3HV, 0.4HV, 0.5HV, 0.6HV, 0.7HV, 0.8HV, 0.9HV, and 1.0HV.

[0106] <Base resin> Examples of the base resin include thermoplastic resins (more specifically, polyarylate resins, 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). In order to form the charge generating layer and the charge transport layer well, it is preferable that the base resin is different from the first resin and the second resin.

[0107] <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, ...

[0108] A suitable example of the hole transport agent is a compound represented by formula (21) (hereinafter, may be referred to as hole transport agent (21)). When the photosensitive layer contains the hole transport agent (21) together with the first resin and the second resin, the photosensitive layer can be formed more satisfactorily, the abrasion resistance of the photoreceptor can be further improved, and peeling of the film can be further suppressed.

[0109] [ka]

[0110] 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 38each 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.

[0111] 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 35 may 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.

[0112] 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.

[0113] A more suitable example of the hole transport agent is a compound represented by formula (HTM-1) (hereinafter, may be referred to as hole transport agent (HTM-1)).

[0114] [ka]

[0115] 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.

[0116] <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.

[0117] 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).

[0118] [ka]

[0119] [ka]

[0120] 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).

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[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 leveling agent, silicone oil is preferred, and silicone oil having a dimethylpolysiloxane structure is more preferred.

[0126] <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.

[0127] 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.

[0128] <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.

[0129] 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).

[0130] 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.

[0131] <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.

[0132] 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.

[0133] 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 first resin, a second resin, and a solvent. The coating liquid for a charge transport layer can be prepared by dissolving or dispersing the hole transport agent, the first resin, and the second resin in a solvent. The coating liquid for a charge transport layer may further contain an additive, if necessary.

[0134] 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 first resin, a second resin, and a solvent. The coating liquid for a single-layer photosensitive layer is prepared by dissolving or dispersing the charge generating agent, the hole transport agent, the first resin, and the second 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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

[0141] 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.

[0142] <Preparation of the first resin> Resins (1-A) to (1-I) used in the examples and resins (1-J) to (1-N) used in the comparative examples were synthesized by the following method. The compositions of resins (1-A) to (1-N) are shown in the following Table 3. Resins (1-A) to (1-N) were used as the first resin in the production of a laminated photoreceptor described later.

[0143] [Table 3]

[0144] In Table 3, "BisCZ," "BisB," "BisZ," "BP," "14NACC," "26NACC," "DPEC," "TPC," and "IPC" respectively represent compounds represented by the following formulas (BisCZ), (BisB), (BisZ), (BP), (14NACC), (26NACC), (DPEC), (TPC), and (IPC) (hereinafter, these may be referred to as compounds (BisCZ), (BisB), (BisZ), (BP), (14NACC), (26NACC), (DPEC), (TPC), and (IPC), respectively).

[0145] [ka]

[0146] Furthermore, the meanings of the terms in Table 3 are as follows: Monomer: The monomer used to synthesize the resin. Forming unit: Repeating unit formed from the corresponding monomer Resin 1-A to 1-N: Resin (1-A) to (1-N) 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 the 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 the resin Molecular weight: viscosity average molecular weight Unit: Repeating unit TPC / IPC: A mixture of compounds (TPC) and (IPC) in a molar ratio of 1 / 1 50 / 50 in the TPC / IPC column: The dicarboxylic acid addition rate of the compound (TPC) is 50% and the dicarboxylic acid addition rate of the compound (IPC) is 50%. DMP: 2,6-dimethylphenol PFH: 1H,1H-perfluoro-1-heptanol Unmeasurable: The resin did not dissolve in the solvent used for viscosity and molecular weight measurement, and the viscosity average molecular weight could not be measured. -: No corresponding monomer is used

[0147] (Synthesis of resin (1-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) (38.95 mmol), the monomer compound (BP) (2.05 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.

[0148] Next, the dicarboxylic acid dichloride (16.0 mmol) of the monomer compound (14NACC) and the dicarboxylic acid dichloride (16.0 mmol) of the monomer compound (26NACC) were dissolved in chloroform (150 mL), thereby obtaining a chloroform solution SB.

[0149] 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 to obtain a resin (1-A).

[0150] (Synthesis of Resins (1-B) to (1-N)) Resins (1-B) to (1-N) were each synthesized in the same manner as in the synthesis of resin (1-A), except that the monomers shown in Table 3 were used at the addition rates shown in Table 3. The amount of each bisphenol monomer added was set so that the total amount of bisphenol monomers was 41.0 millimoles and the bisphenol addition rate shown in Table 3 was achieved. For example, in the synthesis of resin (1-B), the amount of compound (BisB) added was 38.95 millimoles (=41.0×95 / 100), and the amount of compound (BP) added was 2.05 millimoles (=41.0×5 / 100). The amount of each dicarboxylic acid monomer added was set so that the total amount of dicarboxylic acid monomers was 32.0 millimoles and the dicarboxylic acid addition rate shown in Table 3 was achieved. For example, in the synthesis of resin (1-B), the amount of compound (14NACC) added was 16.0 mmol (=32.0×50 / 100), and the amount of compound (26NACC) added was 16.0 mmol (=32.0×50 / 100).

[0151] The obtained resins (1-A) to (1-N) 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 resins (1-A) to (1-N), 1 The H-NMR spectrum is shown in FIG. 1 From the chemical shifts read from the H-NMR spectrum, it was confirmed that resin (1-H) was obtained. The same method was used for resins (1-A) to (1-G) and (1-I) to (1-N), and it was confirmed that resins (1-A) to (1-G) and (1-I) to (1-N) were obtained.

[0152] (Preparation of resin (1-O)) Resin (1-O) used in the comparative example was prepared. Resin (1-O) is represented by the following formula (1-O). The numbers on the right and bottom of the repeating units derived from bisphenol in formula (1-O) indicate the content (unit: %) of the repeating units derived from bisphenol relative to the total number of repeating units derived from bisphenol contained in resin (1-O). The numbers on the right and bottom of the repeating units derived from dicarboxylic acid in formula (1-O) indicate the content (unit: %) of the repeating units derived from dicarboxylic acid relative to the total number of repeating units derived from dicarboxylic acid contained in resin (1-O). Resin (1-O) had a terminal group derived from 2,6-dimethylphenol as an end group. The viscosity average molecular weight of resin (1-O) was 54,400.

[0153] [ka]

[0154] <Measurement of Viscosity Average Molecular Weight of First Resin> The viscosity average molecular weight of the first resin was measured in accordance with JIS (Japanese Industrial Standards) K7252-1:2016. The measured viscosity average molecular weights of resins (1-A) to (1-N) are shown in Table 3. The viscosity average molecular weight of resin (1-O) was as described above.

[0155] <Evaluation of solubility of the first resin in a solvent> In an environment at a temperature of 22°C, 3 g of the first resin and an amount of tetrahydrofuran such that the concentration of the first 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 resin in the solvent tetrahydrofuran was evaluated according to the following criteria. The first resins that were evaluated as A or B were determined to have good solubility in the solvent, and the first resins that were evaluated as C were determined to have poor solubility in the solvent. The evaluation results are shown in Table 4.

[0156] (Evaluation criteria for solubility in solvents) A: The first 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.

[0157] [Table 4]

[0158] <Preparation of the second resin> The following resins (R-1) to (R-4) were prepared as second resins to be used in the manufacture of a multi-layer photoreceptor. All of the resins (R-1) to (R-4) were polyester resins different from the resin (PA). Resin (R-1): Polyester resin ("Vylon (registered trademark) 200" manufactured by Toyobo Co., Ltd., glass transition point: 67°C, number average molecular weight: 17000, hydroxyl value: 6 mgKOH / g, acid value: less than 2 mgKOH / g) Resin (R-2): Polyester resin ("Vylon (registered trademark) 600" manufactured by Toyobo Co., Ltd., glass transition point: 47°C, number average molecular weight: 16000, hydroxyl value: 7 mgKOH / g, acid value: less than 2 mgKOH / g) Resin (R-3): Polyester resin ("Vylon (registered trademark) GK-360" manufactured by Toyobo Co., Ltd., glass transition point: 56°C, number average molecular weight: 16000, hydroxyl value: 7 mgKOH / g, acid value: 5 mgKOH / g) Resin (R-4): Polyester resin ("ALTESTER (registered trademark) S2000" manufactured by Mitsubishi Gas Chemical Company, glass transition point: 95°C)

[0159] <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: 1.5 μm) on the conductive substrate.

[0160] Next, a charge generation layer was formed. Specifically, 1.5 parts by mass of Y-type titanyl phthalocyanine as a charge generation agent, 1 part by mass of polyvinyl acetal resin ("S-LEC BX-5" manufactured by Sekisui Chemical Co., Ltd.) as a base resin, 40 parts by mass of propylene glycol monomethyl ether, and 40 parts by mass of tetrahydrofuran were mixed for 12 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.

[0161] Next, a charge transport layer was formed. In detail, 45 parts by mass of the hole transport agent (HTM-1) described in the embodiment, 99 parts by mass of the resin (1-A) which is the first resin, 1 part by mass of the resin (R-1) which is the second resin, 0.07 parts by mass of silicone oil ("KF96-50cs" manufactured by Shin-Etsu Chemical Co., Ltd., a silicone oil having a dimethylpolysiloxane structure), 560 parts by mass of tetrahydrofuran, and 140 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: 30 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.

[0162] (Manufacture of multi-layer photoreceptors (A-2) to (A-14) and (B-1) to (B-9)) Each of the laminated photoreceptors (A-2) to (A-14) and (B-1) to (B-9) was produced in the same manner as the production of the laminated photoreceptor (A-1), except that the first resin and the second resin shown in Tables 6 and 7 described below were used in the amounts shown in Tables 6 and 7.

[0163] <Vickers hardness measurement> A first resin layer, a second resin layer, and a photosensitive layer were prepared as objects for measuring Vickers hardness. The first resin layer to be measured was prepared as follows. 100 parts by mass of the first resin (each of resins (1-A) to (1-O)), 560 parts by mass of tetrahydrofuran, and 140 parts by mass of toluene were mixed to obtain a first resin solution. The first resin solution was applied onto an aluminum substrate by a dip coating method, and dried at 120°C for 40 minutes. In this manner, a first resin layer (film thickness: 30 μm) was obtained.

[0164] The second resin layer to be measured was prepared as follows: The second resin layer was obtained by the same method as that for preparing the first resin layer, except that the first resin was changed to the second resin (each of the resins (R-1) to (R-4) used in the examples).

[0165] The charge transport layer provided on each multi-layer photoreceptor obtained in the above <Manufacture of multi-layer photoreceptor> was used as the photosensitive layer to be measured.

[0166] Next, the Vickers hardness of the measurement object was measured by a method conforming to Japanese Industrial Standards (JIS) Z2244. First, the measurement object was heated using a heater to raise the temperature of the measurement object to 45°C. Next, while maintaining the temperature of the measurement object at 45°C, the Vickers hardness of the measurement object was measured using a hardness tester ("Micro Vickers Hardness Tester DMH-1 Type" manufactured by Matsuzawa Co., Ltd.). The Vickers hardness was measured under the conditions of a load (test force) of 10gf for the diamond indenter of the hardness tester, a time required to reach the test force of 5 seconds, an approach speed of the diamond indenter of 2mm / sec, and a holding time of the test force of 1 second. The measured Vickers hardness of the first resin layer and the second resin layer at 45°C is shown in Table 5. The measured Vickers hardness of the tourist layer at 45°C is shown in Tables 6 and 7 described later. In Table 5, "measurable" indicates that the first resin was not dissolved in the solvent for forming the first resin solution, and therefore the first resin layer could not be formed, and therefore the Vickers hardness could not be measured.

[0167] [Table 5]

[0168] <Evaluation of sensitivity characteristics> The sensitivity characteristics of the laminated photoreceptor were evaluated using a drum sensitivity tester (manufactured by Gentec Co., Ltd.) in an environment of a temperature of 25°C and a relative humidity of 50% RH. Specifically, the laminated photoreceptor was charged using the drum sensitivity tester so that the surface potential of the laminated photoreceptor was -550 V. Then, monochromatic light (wavelength: 780 nm, exposure amount: 1.0 μJ / cm2) extracted from the light of a halogen lamp was applied using a bandpass filter. 2 ) was irradiated onto the surface of the multi-layer photoconductor. The surface potential of the multi-layer photoconductor was measured 50 milliseconds after the monochromatic light irradiation, and the post-exposure potential (V L The post-exposure potential of each multi-layer photoreceptor is shown in Tables 6 and 7. The sensitivity characteristics of the multi-layer photoreceptor were evaluated based on the post-exposure potential according to the following criteria.

[0169] (Evaluation criteria for sensitivity characteristics) Good: the absolute value of the potential after exposure is 90 V or less. Poor: The absolute value of the potential after exposure exceeds 90V.

[0170] <Abrasion resistance evaluation> The evaluation machine used for the evaluation of wear resistance was a color printer ("C711dn" manufactured by OKI Data Corporation). The toner cartridge of the evaluation machine was filled with cyan toner. First, the thickness T1 of the charge transport layer of the laminated photoreceptor was measured. Then, the laminated photoreceptor was mounted on the evaluation machine. Then, in a normal temperature and normal humidity environment (temperature 23°C and relative humidity 50% RH), the evaluation machine was used to print image I (a pattern image with a printing rate of 1%) on 10,000 sheets of paper. Then, in a high temperature and high humidity environment (temperature 32°C and relative humidity 85% RH), the evaluation machine was used to print image I on 10,000 sheets of paper. Then, in a low temperature and low humidity environment (temperature 10°C and relative humidity 15% RH: hereinafter, sometimes referred to as LL environment), the evaluation machine was used to print image I on 10,000 sheets of paper. After printing in the LL environment, the evaluation machine was left to stand for 2 hours. Next, a solid image (a solid image with an image density of 100%) was printed on one sheet of paper under an LL environment. Then, the thickness T2 of the charge transport layer of the laminated photoreceptor was measured. Then, the amount of wear (T1-T2, unit: μm), which is the amount of change in the thickness of the charge transport layer before and after printing, was determined. The amount of wear thus determined is shown in Tables 6 and 7. The wear resistance of the laminated photoreceptor was evaluated from the amount of wear according to the following criteria.

[0171] (Evaluation criteria for wear resistance) Good: The amount of wear is 2.0 μm or less. Poor: The amount of wear is 2.0 μm.

[0172] <Evaluation of film peeling prevention> Using a cutter knife, 16 square cuts measuring 5 mm in length and 5 mm in width were made in region A on the surface of the laminated photoreceptor (specifically, the surface of the charge transport layer). An adhesive tape ("Cellotape (registered trademark) CT-24" manufactured by Nichiban Co., Ltd., width: 24 mm) was attached to region A. The adhesive tape was peeled off in a direction perpendicular to the axial direction of the laminated photoreceptor. The number of the cuts that remained without peeling (remaining number) among the 16 cuts was counted. The remaining number was also counted in the same manner as for region A for regions B and C on the surface of the laminated photoreceptor. Note that regions A, B, and C were regions on one end side, the other end side, and the intermediate position between them on the surface of the laminated photoreceptor, respectively, in the axial direction of the laminated photoreceptor. The remaining number is shown in Tables 6 and 7. From the remaining number, the suppression of film peeling of the laminated photoreceptor was evaluated according to the following criteria.

[0173] (Evaluation criteria for suppression of film peeling) Good: 1 or more remaining. Defective: The remaining quantity is 0.

[0174] The meanings of the terms in Tables 6 and 7 are as follows: "Photoreceptor" refers to a laminated photoreceptor. "Parts" refers to "parts by mass". "Content" refers to the second resin content. Since the total amount of the first resin and the second resin is 100 parts by mass, the amount (unit: parts by mass) and content (unit: %) of the second resin are the same value. For this reason, the amount and content of the second resin are shown together in the "Amount [parts] (Content [%])" column. "Hardness" refers to the Vickers hardness (unit: HV) of the photosensitive layer. "V L " indicates the post-exposure potential of the multi-layer photoreceptor. "Number remaining" indicates the number remaining in the evaluation of film peeling inhibition. "Not measurable" indicates that the first resin was not dissolved in the solvent used to form the coating liquid for the charge transport layer, and therefore the multi-layer photoreceptor could not be manufactured, and therefore the corresponding measurement or evaluation could not be performed. "-" indicates that the corresponding component is not contained.

[0175] [Table 6]

[0176] [Table 7]

[0177] As shown in Table 3, resins (1-J) to (1-N) were not included in resin (PA). Also, as can be understood from formula (1-O), resin (1-O) was not included in resin (PA). As shown in Table 7, the photosensitive layers of the laminated photoreceptors (B-1) to (B-4) and (B-8) to (B-9) did not contain resin (PA) as the first resin. Therefore, as shown in Tables 4 and 7, the solubility of resins (1-J) and (1-M) in solvents was poor, and the photosensitive layers of the laminated photoreceptors (B-1) and (B-4) could not be formed well. As shown in Table 7, the wear resistance of the laminated photoreceptors (B-2), (B-3), (B-8), and (B-9) was poor.

[0178] As shown in Table 7, the photosensitive layer of the multi-layer photoreceptor (B-5) did not contain the second resin. Therefore, the multi-layer photoreceptor (B-5) was evaluated as poor in terms of sensitivity characteristics and suppression of film peeling.

[0179] As shown in Table 7, the second resin content of the photosensitive layer of the multi-layer photoreceptors (B-6) and (B-7) exceeded 3%. Therefore, the abrasion resistance of the multi-layer photoreceptors (B-6) and (B-7) was poor.

[0180] On the other hand, as shown in Table 6, the photosensitive layers of the laminated photoreceptors (A-1) to (A-14) contained a charge generating agent, a hole transport agent, a first resin, and a second resin. The first resin was contained in the same layer as the second resin (specifically, the charge transport layer). The second resin content was 1% or more and 3% or less. The first resin was resin (PA). The second resin was a polyester resin different from the first resin. Therefore, the laminated photoreceptors (A-1) to (A-14) were able to form a photosensitive layer well, had excellent abrasion resistance, and were able to suppress film peeling. Furthermore, the laminated photoreceptors (A-1) to (A-14) were able to form a photosensitive layer well without impairing the sensitivity characteristics, had excellent abrasion resistance, and were able to suppress film peeling.

[0181] From the above, it was shown that the photoreceptors of the present invention, including the multilayer photoreceptors (A-1) to (A-14), can form a good photosensitive layer, have excellent abrasion resistance, and can suppress film peeling. [Industrial Applicability]

[0182] The photoreceptor according to the present invention can be used in an image forming apparatus.

Claims

1. A conductive substrate and a photosensitive layer are provided. The photosensitive layer includes a charge generating layer and a charge transport layer, The charge generating layer contains a charge generating material, the charge transport layer contains a hole transport agent, a first resin, and a second resin; The charge transport layer is provided as an outermost layer, the first resin is contained in the same layer as the second resin, and a content of the second resin with respect to a total mass of the first resin and the second resin is 1% or more and 3% or less; the first resin has repeating units represented by formulas (1), (2), (3), and (4), and a content of the repeating unit represented by formula (3) relative to the total number of the repeating units represented by formulas (1) and (3) is greater than 0% and less than 20%; The second resin is a polyester resin different from the first resin. 【Chemistry 1】 (In the above formula (1), R 1 and R 2 each independently represents 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 the formula (W1) or (W2). 【Chemistry 2】 In the formula (X1), t represents an integer of 1 or more and 3 or less, * represents a bond, In the formula (X2), R 3 and R 4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R 3 and R 4 represent different groups, and * represents a bond. 【Chemistry 3】 (In the formulas (W1) and (W2), * represents a bond.)

2. The electrophotographic photoreceptor according to claim 1 , wherein the first resin further has a terminal group having a halogen atom.

3. 2. The electrophotographic photoreceptor according to claim 1, wherein the repeating unit represented by formula (1) is a repeating unit represented by formula (1-1). 【Chemistry 4】

4. 2. The electrophotographic photoreceptor according to claim 1, wherein the repeating unit represented by formula (1) is a repeating unit represented by formula (1-1), and the repeating unit represented by formula (2) is a repeating unit represented by formula (2-1). 【Chemistry 5】

5. The electrophotographic photoreceptor according to claim 1, wherein the repeating unit represented by formula (1) is a repeating unit represented by formula (1-1), and the repeating unit represented by formula (2) is a repeating unit represented by formula (2-2). 【Chemistry 6】

6. 2. The electrophotographic photoreceptor according to claim 1, wherein the repeating unit represented by formula (1) is a repeating unit represented by formula (1-2). 【Chemistry 7】

7. The repeating unit represented by formula (1) is a repeating unit represented by formula (1-2), and the repeating unit represented by formula (2) is a repeating unit represented by formula (2-1). 【Chemistry 8】

8. The electrophotographic photoreceptor according to claim 1 , wherein the second resin has a lower Vickers hardness than the first resin.

9. The electrophotographic photoreceptor according to claim 1 , wherein the second resin has a Vickers hardness of 10.0 HV or more and 20.0 HV or less.

10. The electrophotographic photoreceptor according to claim 1 , wherein the first resin has a Vickers hardness of 25.0 HV or more and 40.0 HV or less.

11. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer has a Vickers hardness of 24.0 HV or more and 40.0 HV or less.

12. The electrophotographic photoreceptor according to claim 1 , wherein the hole transport agent comprises a compound represented by formula (21): 【Chemistry 9】 (In the above 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.

13. 2. The electrophotographic photoreceptor according to claim 1, wherein the hole transport agent comprises a compound represented by formula (HTM-1): 【Chemistry 10】

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