Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that is excellent in electrification characteristics and prevents the occurrence of ghost during continuous printing.SOLUTION: An electrophotographic photoreceptor has a conductive support, an undercoat layer provided on the conductive support, and a charge generating layer provided on the undercoat layer. The charge generating layer includes a phthalocyanine compound. The undercoat layer includes an electron transport compound. The difference between the energy level of the lowest unoccupied molecular orbital of the phthalocyanine compound and the energy level of the lowest unoccupied molecular orbital of the electron transport compound is less than 0.45 eV.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 describes a conductive support having at least a charge generation layer and a charge transport layer in that order, wherein the charge generation layer contains at least a binder resin, α-type titanyl phthalocyanine having peaks at Bragg angles (2θ±0.2°) of 7.5°, 12.3°, 16.3°, 25.3°, and 28.6° in the CuKα X-ray diffraction spectrum, and an electron transport material, and the energy level E_lumo of the LUMO obtained as a result of structural optimization calculation by density functional calculation B3LYP / 6-31G(d,p) of the electron transport material is given by the following equation E_lumo(eV)<-3.45 An electrophotographic photoreceptor is disclosed that satisfies the following conditions.

[0003] Patent Document 2 discloses an electrophotographic photoreceptor comprising a conductive support and a photosensitive layer provided on the conductive support, wherein the photosensitive layer comprises a charge generating material and an electron transport material, the electron transport material comprises a first and a second electron transport material, the difference between the LUMO energy of the first electron transport material and the LUMO energy of the charge generating material is in the range of 1.0 to 1.5 eV, the difference between the LUMO energy of the second electron transport material and the LUMO energy of the charge generating material is in the range of 0.6 to 0.9 eV, and the ratio of the content of the second electron transport material to the content of the first and second electron transport materials is in the range of 3 to 40 mass%. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-167332 [Patent Document 2] International Publication No. 2019 / 142608 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide an electrophotographic photoreceptor that exhibits superior chargeability and suppresses the occurrence of ghosting during continuous printing, compared to a case where the charge generation layer contains a phthalocyanine compound, the undercoat layer contains an electron-transporting compound, and the difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron-transporting compound is 0.45 eV or more. [Means for solving the problem]

[0006] Means for solving the aforementioned problem include the following embodiments. <1> An electrophotographic photoreceptor comprising a conductive support, an undercoat layer provided on the conductive support, and a charge generating layer provided on the undercoat layer, wherein the charge generating layer contains a phthalocyanine compound, the undercoat layer contains an electron transport compound, and the difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron transport compound is less than 0.45 eV. <2> The difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron-transporting compound is 0.40 eV or less. <1> The electrophotographic photoreceptor described above. <3> The difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron-transporting compound is 0.30 eV or less. <2> The electrophotographic photoreceptor described above. <4> The average thickness of the aforementioned underlayer is 2 μm or more and 12 μm or less. <1> ~ <3> An electrophotographic photoreceptor as described in any one of the following. <5> The average thickness of the aforementioned underlayer is 3 μm or more and 9 μm or less. <4> The electrophotographic photoreceptor described above. <6> The average thickness of the aforementioned underlayer is 4 μm or more and 7 μm or less. <5> The electrophotographic photoreceptor described above. <7> The electrophotographic photoreceptor according to any one of <1> to <6>, wherein the electron transporting compound is a compound represented by any one of the following formulas (P1) to (P8).

[0007]

Chemical formula

[0008] In formula (P1), R 28 , 26 , 22 , 21 , 27 , 22 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group or a halogen atom, and R 11 and R 12 , R 12 and R 13 and R 13 and R 14 each independently may be linked to each other to form a ring, and R 15 and R 16 , R 16 and R 17 and R 17 and R 18 each independently may be linked to each other to form a ring. In formula (P2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group or a halogen atom, and R 21 and R 22 , R 22 and R23 and R 23 and R 24 Each of them may be independent, or they may be connected to each other to form a ring, R 25 and R 26 , R 26 and R 27 and R 27 and R 28 These elements may be connected to each other independently to form a ring. In formula (P3), R 31 , R 32 , R 33 , R 34 , R 35 and R 36 Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47 , R 48 , R 49 and R 50 Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P5), R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P6), R 61 , R 62 , R 63 and R 64 Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P7), R 71 , R 72 , R 73, R 74 , R 75 , R 76 , R 77 and R 78 Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2). In formula (P8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 and R 87 Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0009] <8> The electron-transporting compound is a compound represented by any of the above formulas (P1) to (P4). <7> The electrophotographic photoreceptor described above. <9> The electron-transporting compound is a compound represented by formula (P1). <8> The electrophotographic photoreceptor described above. <10> The content of the electron-transporting compound is 30% by mass or more and 80% by mass or less, relative to the total mass of the lower layer. <1> ~ <9> An electrophotographic photoreceptor as described in any one of the following. <11> The content of the electron-transporting compound is 50% by mass or more and 80% by mass or less, relative to the total mass of the lower layer. <10> The electrophotographic photoreceptor described above. <12> <1> ~ <11> A process cartridge equipped with an electrophotographic photoreceptor as described in any one of the following, which can be attached to and detached from an image forming apparatus. <13> <1> ~ <11> An image forming apparatus comprising: an electrophotographic photoreceptor as described in any one of the above; charging means for charging the surface of the electrophotographic photoreceptor; electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; and transfer means for transferring the toner image to the surface of a recording medium. [Effects of the Invention]

[0010] <1> According to the invention, compared to a case where the charge generating layer contains a phthalocyanine compound, the undercoat layer contains an electron-transporting compound, and the difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron-transporting compound is 0.45 eV or more, the present invention provides an electrophotographic photoreceptor that exhibits superior chargeability and suppresses the occurrence of ghosting during continuous printing. <2> According to the present invention, an electrophotographic photoreceptor is provided in which the occurrence of ghosting during continuous printing is further suppressed compared to the case where the difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron-transporting compound is greater than 0.40 eV. <3> According to the present invention, an electrophotographic photoreceptor is provided in which the occurrence of ghosting during continuous printing is further suppressed compared to the case where the difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron-transporting compound is greater than 0.30 eV. <4> According to the invention, an electrophotographic photoreceptor is provided that exhibits superior electrostatic properties and suppresses the occurrence of ghosting during continuous printing compared to cases where the average thickness of the undercoat layer is less than 2 μm or greater than 12 μm. <5> According to the invention, an electrophotographic photoreceptor is provided that exhibits superior electrostatic properties and suppresses the occurrence of ghosting during continuous printing compared to cases where the average thickness of the undercoat layer is less than 3 μm or greater than 9 μm. <6> According to the invention, an electrophotographic photoreceptor is provided that exhibits superior electrostatic properties and suppresses the occurrence of ghosting during continuous printing compared to cases where the average thickness of the undercoat layer is less than 4 μm or greater than 7 μm. <7> , <8> or <9> According to the invention, an electrophotographic photoreceptor is provided that has superior chargeability and suppresses the occurrence of ghosting during continuous printing compared to when the electron-transporting compound particles are anthraquinone-based compound particles. <10> According to the invention, an electrophotographic photoreceptor is provided that exhibits superior electrostatic properties and further suppresses the occurrence of ghosting during continuous printing, compared to cases where the content of the electron transporting compound is less than 30% by mass or more than 80% by mass relative to the total mass of the undercoat layer. <11> According to the invention, an electrophotographic photoreceptor is provided that exhibits superior electrostatic properties and suppresses the occurrence of ghosting during continuous printing, compared to cases where the content of the electron transporting compound is less than 50% by mass or more than 80% by mass relative to the total mass of the undercoat layer. <12> or <13> According to the present invention, compared to a case where the charge generation layer of the electrophotographic photoreceptor contains a phthalocyanine compound, the undercoat layer contains an electron-transporting compound, and the difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron-transporting compound is 0.45 eV or more, a process cartridge and an image forming apparatus are provided in which the electrophotographic photoreceptor exhibits superior charging performance and the occurrence of ghosting during continuous printing is suppressed. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic partial cross-sectional view showing an example of the layer structure of an electrophotographic photoreceptor according to this embodiment. [Figure 2] This is a schematic diagram showing an example of an image forming apparatus according to this embodiment. [Figure 3] This is a schematic diagram showing another example of the image forming apparatus according to this embodiment. [Modes for carrying out the invention]

[0012] The embodiments of this disclosure are described below. These descriptions and embodiments are illustrative and do not limit the scope of the embodiments.

[0013] In this disclosure, the numerical range indicated using "~" represents a range that includes the numbers before and after "~" as the minimum and maximum values, respectively.

[0014] In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0015] In this disclosure, the term "process" includes not only independent processes but also any process that cannot be clearly distinguished from other processes, provided that its intended purpose is achieved.

[0016] In this disclosure, each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition in this disclosure, if there are multiple types of the substance corresponding to each component in the composition, it means the total amount of those multiple types of substances present in the composition unless otherwise specified.

[0017] In this disclosure, "main component" means the primary component. For example, in a mixture of multiple components, the main component is the component that accounts for 30% or more of the total mass of the mixture.

[0018] In this disclosure, the electrophotographic photoreceptor is also simply referred to as the photoreceptor.

[0019] <Electrophotographic photoconductor> The electrophotographic photoreceptor according to this embodiment comprises a conductive support, an undercoat layer provided on the conductive support, and a charge generation layer provided on the undercoat layer, wherein the charge generation layer contains a phthalocyanine compound, the undercoat layer contains an electron transport compound, and the difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the electron transport compound is less than 0.45 eV.

[0020] Figure 1 schematically shows an example of the layer configuration of an electrophotographic photoreceptor according to this embodiment. The photoreceptor 7A shown in Figure 1 has a structure in which an undercoat layer 1, a charge generation layer 2, and a charge transport layer 3 are laminated in this order on a conductive support 4. The charge generation layer 2 and the charge transport layer 3 constitute the photosensitive layer 5. The photoreceptor 7A may also have a layer configuration in which a protective layer is further provided on the charge transport layer 3.

[0021] In the electrophotographic photoreceptor according to this embodiment, the photosensitive layer may be a stacked photosensitive layer in which the charge generation layer 2 and the charge transport layer 3 are separated, as shown in the photoreceptor 7A in Figure 1, or it may be a single-layer photosensitive layer that has charge generation and charge transport capabilities instead of the charge generation layer 2 and the charge transport layer 3.

[0022] Conventional electrophotographic photoreceptors have known undercoats containing metal oxides with high electron mobility, but their low resistance meant that their chargeability was insufficient. Furthermore, in conventional electrophotographic photoreceptors, charge generation layers containing phthalocyanine compounds with high charge generation efficiency are known. However, because of the large number of generated carriers, the number of carriers accumulated at the interface of the charge generation layer also increases, and despite having high electron mobility, ghosting sometimes occurred during continuous printing. In this embodiment, the electrophotographic photoreceptor has a charge generation layer containing a phthalocyanine compound and an undercoat layer containing an electron transport compound. The difference between the lowest unoccupied orbital of the phthalocyanine compound and the lowest unoccupied orbital of the electron transport compound is less than 0.45 eV. As a result, the undercoat layer has high resistance and exhibits good chargeability. Furthermore, by making the difference in energy levels between the lowest unoccupied orbitals of the phthalocyanine compound and the electron transport compound less than 0.45 eV, electron transportability is improved, carrier accumulation at the interface of the charge generation layer is suppressed, and the occurrence of ghosting during continuous printing is suppressed.

[0023] [The difference between the energy levels of the lowest unoccupied orbitals of phthalocyanine compounds and electron-transporting compounds] In the electrophotographic photoreceptor according to this embodiment, the difference (the value obtained by subtracting the smaller value from the larger value, the absolute value of the difference) between the energy level (LUMO) of the lowest unoccupied orbital of the phthalocyanine compound contained in the charge generation layer and the lowest unoccupied orbital (LUMO) of the electron transport compound contained in the underlayer is less than 0.45 eV. From the viewpoint of suppressing the occurrence of ghosts during continuous printing (hereinafter also simply referred to as "ghost suppression"), it is preferably 0.40 eV or less, and more preferably 0.30 eV or less.

[0024] In this embodiment, the energy level of the lowest unoccupied orbital (LUMO) and the energy level of the highest occupied orbital (HOMO) of the compound shall be measured according to the following method. The HOMO of each compound is measured as follows. The ionization potential of 5 mg of each compound was measured using an airborne photoelectron spectrometer (AC-2, manufactured by RIKEN KEKI Co., Ltd.), and this value was defined as the HOMO. 20 mg of each compound is dissolved in 200 mL of toluene. To 2 mL of this solution, toluene is added to make a 50 mL solution. The absorbance of this prepared solution is measured using a UV-Vis-NIR spectrophotometer (model: Cary5000, manufactured by Agilent Technologies) in the wavelength range of 200 nm to 800 nm. The absorption edge at wavelengths of 400 nm to 700 nm is calculated, and this value is defined as the S0-S1 transition energy gap (HOMO-LUMO energy difference ΔE). LUMO is calculated using the following formula. LUMO = HOMO + ΔE

[0025] The following describes in detail each layer of the photoreceptor according to this embodiment.

[0026] [Sublayer] The electrophotographic photoreceptor according to this embodiment has an undercoat, and the undercoat contains an electron-transporting compound.

[0027] <<Electron transporting compounds>> Examples of electron-transporting compounds used in the lower layer, from the viewpoint of chargeability and ghost suppression, include perinone compounds, naphthalenediimide compounds, perylenediimide compounds, fluorenone compounds, dinaphthoquinone compounds, diphenoquinone compounds, and xanthone compounds. One electron-transporting compound may be used alone, or two or more may be used in mixture, but it is preferable to use one alone. In particular, the electron transport compound is preferably a naphthalene diimide compound or a perylene diimide compound, more preferably a naphthalene tetracarboxylic acid diimide compound or a perylene tetracarboxylic acid diimide compound, and especially preferably a naphthalene tetracarboxylic acid diimide compound, from the viewpoint of chargeability and ghost suppression. Furthermore, the electron-transporting compound is preferably in the form of particles.

[0028] Further, from the viewpoints of chargeability and ghost suppression property, the organic compound is preferably particles of a compound represented by any one of the following formulas (P1) to (P8), more preferably particles of a compound represented by any one of the following formulas (P1) to (P4), and particularly preferably particles of a compound represented by the following formula (P1). In the above aspect, it is excellent in chargeability, has a low LUMO value, and is excellent in ghost suppression property.

[0029]

Chemical formula

[0030] In formula (P1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group or a halogen atom, and R 11 and R 12 , R 12 and R 13 and R 13 and R 14 each independently may be linked to each other to form a ring, and R 15 and R 16 , R 16 and R 17 and R 17 and R 18 each independently may be linked to each other to form a ring. In formula (P2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom, R 21 and R 22 , R 22 and R 23 and R 23 and R 24 Each of them may be independent, or they may be connected to each other to form a ring, R 25 and R 26 , R 26 and R 27 and R 27 and R 28 These elements may be connected to each other independently to form a ring. In formula (P3), R 31 , R 32 , R 33 , R 34 , R 35 and R 36 Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47 , R 48 , R 49 and R 50 Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P5), R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P6), R 61 , R62 , R 63 and R 64 Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P7), R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 and R 78 Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2). In formula (P8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 and R 87 Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0031] - Compounds represented by formula (P1) or formula (P2) - The compounds represented by formula (P1) or formula (P2) will be described below.

[0032] [ka]

[0033] In formula (P1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 (Hereafter simply "R 11 ~R 18It is also called ). Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 11 and R 12 , R 12 and R 13 and R 13 and R 14 These elements may be connected to each other independently to form a ring. 15 and R 16 , R 16 and R 17 and R 17 and R 18 These elements may be connected to each other independently to form a ring. In formula (P2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 (Hereafter simply "R 21 ~R 28 It is also called ). Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 21 and R 22 , R 22 and R 23 and R 23 and R 24 These elements may be connected to each other independently to form a ring. 25 and R 26 , R 26 and R 27 and R 27 and R 28 These elements may be connected to each other independently to form a ring. In formula (P1), R 11 ~R 18 Examples of alkyl groups represented by include substituted or unsubstituted alkyl groups.

[0034] In formula (P1), R 11 ~R 18 Examples of unsubstituted alkyl groups represented by include linear alkyl groups having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), branched alkyl groups having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms), and cyclic alkyl groups having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms).

[0035] Examples of linear alkyl groups having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, tridecyl group, n-tetradecyl group, n-pentadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, and n-icosyl group.

[0036] Examples of branched alkyl groups having 3 to 20 carbon atoms include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert-decyl group, isododecyl group, sec-dodecyl group, tert-dodecyl group, tert-tetradecyl group, and tert-pentadecyl group.

[0037] Examples of cyclic alkyl groups having 3 to 20 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl groups, as well as polycyclic alkyl groups (e.g., bicyclic, tricyclic, spirocyclic) formed by linking these monocyclic alkyl groups.

[0038] Among the above, linear alkyl groups such as methyl groups and ethyl groups are preferred as unsubstituted alkyl groups.

[0039] Substituents in alkyl groups include alkoxy groups, hydroxyl groups, carboxyl groups, nitro groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As an alkoxy group that substitutes a hydrogen atom in an alkyl group, R in formula (P1) 11 ~R 18 Examples of groups similar to the unsubstituted alkoxy group represented by include:

[0040] In formula (P1), R 11 ~R 18 Examples of alkoxy groups represented by include substituted or unsubstituted alkoxy groups.

[0041] In formula (P1), R 11 ~R 18 Examples of unsubstituted alkoxy groups represented by include linear, branched, or cyclic alkoxy groups having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms).

[0042] Specific examples of linear alkoxy groups include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, and n-decyloxy groups. Examples of branched alkoxy groups include isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, sec-hexyloxy group, tert-hexyloxy group, isoheptyloxy group, sec-heptyloxy group, tert-heptyloxy group, isooctyloxy group, sec-octyloxy group, tert-octyloxy group, isononyloxy group, sec-nonyloxy group, tert-nonyloxy group, isodecyloxy group, sec-decyloxy group, and tert-decyloxy group. Examples of cyclic alkoxy groups include cyclopropoxy, cyclobutoxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, cyclooctyloxy, cyclononyloxy, and cyclodecyloxy groups. Among these, linear alkoxy groups are preferred as unsubstituted alkoxy groups.

[0043] Substituents in alkoxy groups include aryl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, hydroxyl groups, carboxyl groups, nitro groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As an aryl group that substitutes a hydrogen atom in an alkoxy group, in formula (P1), R 11 ~R 18 Examples include unsubstituted aryl groups represented by . As an alkoxycarbonyl group that substitutes a hydrogen atom in an alkoxy group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxycarbonyl group represented by include . As an aryloxycarbonyl group that substitutes a hydrogen atom in an alkoxy group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted aryloxycarbonyl group represented by include .

[0044] In formula (P1), R 11 ~R 18 Aralkyl groups represented by include substituted or unsubstituted aralkyl groups.

[0045] In formula (P1), R 11 ~R 18 The unsubstituted aralkyl group represented by is preferably an aralkyl group having 7 to 30 carbon atoms, more preferably an aralkyl group having 7 to 16 carbon atoms, and even more preferably an aralkyl group having 7 to 12 carbon atoms.

[0046] Examples of unsubstituted aralkyl groups having 7 to 30 carbon atoms include benzyl group, phenylethyl group, phenylpropyl group, 4-phenylbutyl group, phenylpentyl group, phenylhexyl group, phenylheptyl group, phenyloctyl group, phenylnonyl group, naphthylmethyl group, naphthylethyl group, anthratilmethyl group, and phenylcyclopentylmethyl group.

[0047] Substituents in an aralkyl group include alkoxy groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and halogen atoms (such as fluorine, bromine, and iodine atoms). As for the alkoxy group that substitutes a hydrogen atom in the aralkyl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxy group represented by include: As for the alkoxycarbonyl group that substitutes the hydrogen atom in the aralkyl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxycarbonyl group represented by include . As for the aryloxycarbonyl group that substitutes a hydrogen atom in the aralkyl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted aryloxycarbonyl group represented by include .

[0048] In formula (P1), R 11 ~R 18 Examples of aryl groups represented by this symbol include substituted and unsubstituted aryl groups.

[0049] In formula (P1), R 11 ~R 18 The unsubstituted aryl group represented by is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and even more preferably an aryl group having 6 to 10 carbon atoms.

[0050] Examples of aryl groups having 6 to 30 carbon atoms include phenyl group, biphenyl group, 1-naphthyl group, 2-naphthyl group, 9-anthuryl group, 9-phenanthryl group, 1-pyrenyl group, 5-naphthacenyl group, 1-indenyl group, 2-azlenyl group, 9-fluorenyl group, biphenylenyl group, indacenyl group, fluoranthenyl group, acenaphthyleneyl group, aceantrilenyl group, phenalenyl group, fluorenyl group, Examples include anthryl group, bianthracenyl group, teranthracenyl group, quarteranthracenyl group, anthraquinolyl group, phenanthryl group, triphenylenyl group, pyrenyl group, chrysenyl group, naphthacenyl group, pleiadenyl group, picenyl group, perilenyl group, pentaphenyl group, pentacenyl group, tetraphenylenyl group, hexaphenyl group, hexacenyl group, rubicenyl group, coronenyl group, etc. Among the above, the phenyl group is preferred.

[0051] Substituents in an aryl group include alkyl groups, alkoxy groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As the alkyl group that substitutes the hydrogen atom in the aryl group, in formula (P1), R 11 ~R 18 Examples of groups similar to unsubstituted alkyl groups represented by include . As an alkoxy group that substitutes a hydrogen atom in an aryl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxy group represented by include: As for the alkoxycarbonyl group that substitutes a hydrogen atom in the aryl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxycarbonyl group represented by include . As an aryloxycarbonyl group that substitutes a hydrogen atom in the aryl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted aryloxycarbonyl group represented by include .

[0052] In formula (P1), R 11~R 18 Examples of aryloxy groups represented by -O-Ar (where Ar represents an aryl group) include substituted and unsubstituted aryloxy groups.

[0053] In formula (P1), R 11 ~R 18 The unsubstituted aryloxy group represented by is preferably an aryloxy group having 6 to 30 carbon atoms, more preferably an aryloxy group having 6 to 14 carbon atoms, and even more preferably an aryloxy group having 6 to 10 carbon atoms.

[0054] Aryloxy groups with 6 to 30 carbon atoms include phenyloxy group (phenoxy group), biphenyloxy group, 1-naphthyloxy group, 2-naphthyloxy group, 9-anthryloxy group, 9-phenanthryloxy group, 1-pyrenyloxy group, 5-naphthacenyloxy group, 1-indenyloxy group, 2-azlenyloxy group, 9-fluorenyloxy group, biphenylenyloxy group, indacenyloxy group, fluoranthenyloxy group, acenaphthyleneyloxy group, aceanthrlenyloxy group, phenalenyloxy group, and fluorenyloxy group. Examples include the phenyloxy group, anthryloxy group, bianthrencenyloxy group, teranthrencenyloxy group, quarteranthrencenyloxy group, anthraquinolyloxy group, phenanthryloxy group, triphenylenyloxy group, pyrenyloxy group, crisenyloxy group, naphthacenyloxy group, pleiadenyloxy group, picenyloxy group, perilennyloxy group, pentaphenyloxy group, pentacenyloxy group, tetraphenylenyloxy group, hexaphenyloxy group, hexacenyloxy group, rubicenyloxy group, coronenyloxy group, etc. Among the above, the phenyloxy group (phenoxy group) is preferred.

[0055] Substituents in the aryloxy group include alkyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As the alkyl group that substitutes the hydrogen atom in the aryloxy group, in formula (P1), R 11 ~R 18Examples of groups similar to unsubstituted alkyl groups represented by include . As for the alkoxycarbonyl group that substitutes the hydrogen atom in the aryloxy group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxycarbonyl group represented by include . As an aryloxycarbonyl group that substitutes a hydrogen atom in the aryloxy group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted aryloxycarbonyl group represented by include .

[0056] In formula (P1), R 11 ~R 18 Examples of alkoxycarbonyl groups represented by (-CO-OR, where R represents an alkyl group) include substituted or unsubstituted alkoxycarbonyl groups.

[0057] In formula (P1), R 11 ~R 18 The number of carbon atoms in the alkyl chain of the unsubstituted alkoxycarbonyl group represented by is preferably 1 to 20, more preferably 1 to 15, and even more preferably 1 to 10.

[0058] Examples of alkoxycarbonyl groups with 1 to 20 carbon atoms in the alkyl chain include methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, sec-butoxybutylcarbonyl group, tert-butoxycarbonyl group, pentaoxycarbonyl group, hexaoxycarbonyl group, heptaoxycarbonyl group, octaoxycarbonyl group, nonaoxycarbonyl group, decaoxycarbonyl group, dodecaoxycarbonyl group, tridecaoxycarbonyl group, tetradecaoxycarbonyl group, pentadecaoxycarbonyl group, hexadecaoxycarbonyl group, heptadecaoxycarbonyl group, octadecaoxycarbonyl group, nonadecaoxycarbonyl group, and eicosaoxycarbonyl group.

[0059] Examples of substituents on an alkoxycarbonyl group include aryl groups, hydroxyl groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As an aryl group that substitutes a hydrogen atom in an alkoxycarbonyl group, in formula (P1), R 11 ~R 18 Examples include unsubstituted aryl groups represented by .

[0060] In formula (P1), R 11 ~R 18 Examples of aryloxycarbonyl groups represented by -CO-OAr (where Ar represents an aryl group) include substituted and unsubstituted aryloxycarbonyl groups.

[0061] In formula (P1), R 11 ~R 18 In the unsubstituted aryloxycarbonyl group represented by , the number of carbon atoms in the aryl group is preferably 6 to 30, more preferably 6 to 14, and even more preferably 6 to 10.

[0062] Examples of aryloxycarbonyl groups having aryl groups with 6 to 30 carbon atoms include phenoxycarbonyl group, biphenyloxycarbonyl group, 1-naphthyloxycarbonyl group, 2-naphthyloxycarbonyl group, 9-anthuryloxycarbonyl group, 9-phenanthryloxycarbonyl group, 1-pyrenyloxycarbonyl group, 5-naphthacenyloxycarbonyl group, 1-indenyloxycarbonyl group, 2-azlenyloxycarbonyl group, 9-fluorenyloxycarbonyl group, biphenylenyloxycarbonyl group, indacenyloxycarbonyl group, fluoranthenyloxycarbonyl group, acenaphthyleneyloxycarbonyl group, aceanthryleneyloxycarbonyl group, phenalenyloxycarbonyl group, fluorenyloxycarbonyl group, Examples include anthryloxycarbonyl group, biantracenyloxycarbonyl group, terantracenyloxycarbonyl group, quarterantracenyloxycarbonyl group, anthraquinolyloxycarbonyl group, phenanthryloxycarbonyl group, triphenylenyloxycarbonyl group, pyrenyloxycarbonyl group, chrysenyloxycarbonyl group, naphthacenyloxycarbonyl group, pleiadenyloxycarbonyl group, picenyloxycarbonyl group, perilennyloxycarbonyl group, pentaphenyloxycarbonyl group, pentacenyloxycarbonyl group, tetraphenylenyloxycarbonyl group, hexaphenyloxycarbonyl group, hexacenyloxycarbonyl group, rubicenyloxycarbonyl group, coronenyloxycarbonyl group, etc. Among the above, the phenoxycarbonyl group is preferred.

[0063] Substituents in the aryloxycarbonyl group include alkyl groups, hydroxyl groups, and halogen atoms (such as fluorine, bromine, and iodine atoms). As an alkyl group that substitutes a hydrogen atom of the aryloxycarbonyl group, in formula (P1), R 11 ~R 18 Examples of groups similar to unsubstituted alkyl groups represented by include .

[0064] In formula (P1), R 11 ~R 18The alkoxycarbonylalkyl group (-(C n H 2n )-CO-OR, where R represents an alkyl group and n represents an integer of 1 or more.) includes a substituted or unsubstituted alkoxycarbonylalkyl group.

[0065] In formula (P1), R 11 ~R 18 As the alkoxycarbonyl group (-CO-OR) in the unsubstituted alkoxycarbonylalkyl group represented by, in formula (P1), R 11 ~R 18 Groups similar to the alkoxycarbonyl groups represented by are included.

[0066] In formula (P1), R 11 ~R 18 As the alkylene chain (-(C n H 2n -) in the unsubstituted alkoxycarbonylalkyl group represented by, linear alkylene chains having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), branched alkylene chains having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms), and cyclic alkylene chains having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms) are included.

[0067] Examples of the linear alkylene chain having 1 to 20 carbon atoms include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-nonylene group, an n-decylene group, an n-undecylene group, an n-dodecylene group, a tridecylene group, an n-tetradecylene group, an n-pentadecylene group, an n-heptadecylene group, an n-octadecylene group, an n-nonadecylene group, an n-icosylene group, and the like.

[0068] Examples of the branched alkylene chain having 3 to 20 carbon atoms include isopropylene group, isobutylene group, sec-butylene group, tert-butylene group, isopentylene group, neopentylene group, tert-pentylene group, isohexylene group, sec-hexylene group, tert-hexylene group, isoheptylene group, sec-heptylene group, tert-heptylene group, isooctylene group, sec-octylene group, tert-octylene group, isononylene group, sec-nonylene group, tert-nonylene group, isodecylene group, sec-decylene group, tert-decylene group, isododecylene group, sec-dodecylene group, tert-dodecylene group, tert-tetradecylene group, tert-pentadecylene group, and the like.

[0069] Examples of the cyclic alkylene chain having 3 to 20 carbon atoms include cyclopropylene group, cyclobutylene group, cyclopentylene group, cyclohexylene group, cycloheptylene group, cyclooctylene group, cyclononylene group, cyclodecylene group, and the like.

[0070] Examples of the substituent in the alkoxycarbonylalkyl group include aryl group, hydroxy group, and halogen atoms (such as fluorine atom, bromine atom, iodine atom, etc.). Examples of the aryl group that substitutes the hydrogen atom of the alkoxycarbonylalkyl group include, in formula (P1), R 11 ~R 18 and groups similar to the unsubstituted aryl group represented thereby.

[0071] In formula (P1), R 11 ~R 18 Examples of the aryloxycarbonylalkyl group (-(C n H 2n ) -CO-OAr, where Ar represents an aryl group and n represents an integer of 1 or more) include substituted or unsubstituted aryloxycarbonylalkyl groups.

[0072] In formula (P1), R 11 ~R 18In the unsubstituted aryloxycarbonylalkyl group represented by (P1), the aryloxycarbonyl group (-CO-OAr, where Ar represents an aryl group) is R 11 ~R 18 Examples of groups similar to the aryloxycarbonyl group represented by [the symbol] include [the symbol].

[0073] In formula (P1), R 11 ~R 18 Alkylene chain (-C) in unsubstituted aryloxycarbonylalkyl groups represented by n H 2n -) In equation (P1), R 11 ~R 18 Examples of groups similar to the alkylene chain in the alkoxycarbonylalkyl group represented by include .

[0074] Substituents in aryloxycarbonylalkyl groups include alkyl groups, hydroxyl groups, and halogen atoms (such as fluorine, bromine, and iodine atoms). As the alkyl group that substitutes the hydrogen atom of the aryloxycarbonylalkyl group, in formula (P1), R 11 ~R 18 Examples of groups similar to unsubstituted alkyl groups represented by include .

[0075] In formula (P1), R 11 ~R 18 Examples of halogen atoms represented by this formula include fluorine, chlorine, bromine, and iodine atoms.

[0076] In formula (P1), R 11 ~R 14 Two or more of the following, or R 15 ~R 18The ring structure formed by the linkage of two or more of these elements may be an aliphatic hydrocarbon ring structure, a heterocyclic ring structure, an aromatic hydrocarbon ring structure, or a heteroaromatic ring structure, but an aromatic hydrocarbon ring structure is preferred. Among these, preferred ring structures include benzene rings, condensed rings having 10 to 18 carbon atoms (naphthalene rings, anthracene rings, phenanthrene rings, chrysene rings (benzo[α]phenanthrene rings), tetracene rings, tetrafen rings (benzo[α]anthracene rings), triphenylene rings, etc.), with benzene rings being particularly preferred.

[0077] In formula (P2), R 21 ~R 28 The alkyl group represented by is R in formula (P1). 11 ~R 18 Examples of groups similar to the alkyl groups represented are shown. In formula (P2), R 21 ~R 28 The alkoxy group represented by formula (P1) is R 11 ~R 18 Examples of groups similar to the alkoxy group represented by can be cited. In formula (P2), R 21 ~R 28 The aralkyl group represented by is R in formula (P1). 11 ~R 18 Examples of groups similar to the aralkyl group represented by this symbol include: In formula (P2), R 21 ~R 28 As an aryl group represented by formula (P1), R 11 ~R 18 Examples of groups similar to the aryl group represented by include . In formula (P2), R 21 ~R 28 The aryloxy group represented by is, in formula (P1), R 11 ~R 18 Examples of groups similar to the aryloxy group represented by can be cited. In formula (P2), R 21 ~R 28 The alkoxycarbonyl group represented by formula (P1) is R 11 ~R18 Examples of groups similar to the alkoxycarbonyl group represented by include . In formula (P2), R 21 ~R 28 The aryloxycarbonyl group represented by is, in formula (P1), R 11 ~R 18 Examples of groups similar to the aryloxycarbonyl group represented by [the symbol] include [the symbol]. In formula (P2), R 21 ~R 28 As an alkoxycarbonylalkyl group represented by formula (P1), R 11 ~R 18 Examples of groups similar to the alkoxycarbonylalkyl groups represented by include . In formula (P2), R 21 ~R 28 As an aryloxycarbonylalkyl group represented by formula (P1), R 11 ~R 18 Examples of groups similar to the aryloxycarbonylalkyl group represented by [the formula shown] include [the formula shown]. In formula (P2), R 21 ~R 28 As for halogen atoms represented by formula (P1), R 11 ~R 18 Examples of atoms similar to halogen atoms represented by [the symbol] include [the symbol].

[0078] In formula (P2), R 21 and R 22 , R 22 and R 23 , R 23 and R 24 , R 25 and R 26 , R 26 and R 27 or R 27 and R 28 However, examples of ring structures formed by the linking of these rings include benzene rings and condensed rings having 10 to 18 carbon atoms (naphthalene rings, anthracene rings, phenanthrene rings, chrysene rings (benzo[α]phenanthrene rings), tetracene rings, tetrafen rings (benzo[α]anthracene rings), triphenylene rings, etc.). Among the above, benzene rings are preferred as the ring structure formed.

[0079] In formula (P1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 are each independently preferably a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group or an aryloxycarbonylalkyl group.

[0080] In formula (P2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 are each independently preferably a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group or an aryloxycarbonylalkyl group.

[0081] Hereinafter, specific examples of the compound represented by formula (P1) or formula (P2) are shown, but the present embodiment is not limited thereto. In addition, Ph represents a phenyl group.

[0082] [Chemical formula]

[0083] [Chemical formula]

[0084] [Chemical formula]

[0085] [Chemical formula]

[0086] [ka]

[0087] [ka]

[0088] The compound represented by formula (P1) and the compound represented by formula (P2) are isomers (i.e., cis and trans isomers). A common synthesis method involves heating and condensing 2 moles of orthophenylenediamine compound and 1 mole of naphthalenetetracarboxylic acid compound, yielding a mixture of cis and trans isomers, with the cis isomer usually being more abundant than the trans isomer. The cis and trans isomers can be separated, for example, by heating and washing with a potassium hydroxide alcohol solution, which separates the soluble cis isomer from the sparingly soluble trans isomer.

[0089] - Compound represented by formula (P3) - The compound represented by formula (P3) will be explained below.

[0090] [ka]

[0091] In formula (P3), R 31 , R 32 , R 33 , R 34 , R 35 and R 36 (Hereafter simply "R 31 ~R 36 It is also called ). Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P3), R 31 ~R 36 The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by formula (P1) are R 11~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0092] The following are example compounds of the compound represented by formula (P3), but this embodiment is not limited to these. The example compound numbers below will be denoted as example compound (3-number), etc. Specifically, for example, example compound 5 below will be denoted as "example compound (3-5)," etc. The same applies to each formula below.

[0093] [ka]

[0094] The abbreviations and symbols in the above example compounds have the following meanings. • Pr: n-propyl group · c-C6H 11 : Cyclohexyl group • C6H5: Phenyl group • p-Cl-C6H4: parachlorophenyl group • C6H5CH2: Benzyl group • C6H5CH2CH2: Phenethyl group

[0095] - Compound represented by formula (P4) - The compound represented by formula (P4) will be described below.

[0096] [ka]

[0097] In formula (P4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47 , R 48 , R 49 and R 50 (Hereafter simply "R 51 ~R50 It is also called ). Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P4), R 41 ~R 46 The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by formula (P1) are R 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0098] The following are examples of compounds represented by formula (P4), but this embodiment is not limited to these. The example compound numbers below will be referred to as example compound (3-number). Specifically, for example compound 5 will be referred to as "example compound (3-5)" below.

[0099] [ka]

[0100] The abbreviations and symbols in the above example compounds have the following meanings. •Bu:n-butyl group · c-C6H 11 : Cyclohexyl group • p-CH3-C6H4: paratril group • C6H5: Phenyl group • p-Cl-C6H4: parachlorophenyl group • o-Cl-C6H4: orthochlorophenyl group • C6H5CH2: Benzyl group • 3,5-(CH3)2-C6H4: 3,5-dimethylphenyl group • 3,5-Cl2-C6H4: 3,5-dichlorophenyl group

[0101] - Compound represented by formula (P5) - The compound represented by formula (P5) will be explained below.

[0102] [ka]

[0103] In formula (P5), R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 (Hereinafter referred to as “R 51 ~R 58 It is also called ). Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom.

[0104] In formula (P5), R 51 ~R 58 The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by formula (P1) are R 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0105] In formula (P5), R 51 ~R 58 Each of these may independently be represented by a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group.

[0106] In formula (P5), R 51 and R 58Each of these groups is independently preferred from the viewpoint of electron transport properties to be an alkyl group having 3 to 12 carbon atoms, an alkoxy group having 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; more preferably a branched alkyl group having 3 to 12 carbon atoms, a branched alkoxy group having 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; even more preferably a branched alkyl group having 3 to 8 carbon atoms or a branched alkoxy group having 3 to 8 carbon atoms; and particularly preferred a t-butyl group.

[0107] In formula (P5), R 52 and R 57 Each of these groups is preferably, from the viewpoint of electron transport, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms; more preferably, a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a linear alkoxy group having 1 to 4 carbon atoms; even more preferably, a linear alkyl group having 1 to 3 carbon atoms or a linear alkoxy group having 1 to 3 carbon atoms; and particularly preferably, a methyl group.

[0108] In formula (P5), R 53 , R 54 , R 55 and R 56 It is preferable that this represents a hydrogen atom. In formula (P5), R 51 and R 58 From the viewpoint of electron transport, it is preferable that these be the same group. In formula (P5), R 52 and R 57 From the viewpoint of electron transport, it is preferable that these be the same group. In formula (P5), R 51 and R 52 From the viewpoint of electron transport, it is preferable that these are different groups. In formula (P5), R 57 and R 58 From the viewpoint of electron transport, it is preferable that these are different groups.

[0109] The following are examples of compounds represented by formula (P5), but this embodiment is not limited to these.

[0110] [ka]

[0111] The abbreviations and symbols in the above example compounds have the following meanings. ·t-C4H9: t-butyl group • CH3O: Methoxy group ·t-C4H9O:t-butoxy group · c-C6H 11 : Cyclohexyl group • C6H5: Phenyl group • C6H5CH2: Benzyl group

[0112] - Compound represented by formula (P6) - The compound represented by formula (P6) will be described below.

[0113] [ka]

[0114] In formula (P6), R 61 , R 62 , R 63 and R 64 (Hereafter simply "R 61 ~R 64 It is also called ). Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In formula (P6), R 61 ~R 64 The alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group, and halogen atom represented by formula (P1) are R 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0115] In formula (P6), R 61 ~R 64 Each of these may independently be represented by a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group.

[0116] In formula (P6), R 61 and R 64 Each of these groups is independently preferred from the viewpoint of electron transport properties to be an alkyl group having 3 to 12 carbon atoms, an alkoxy group having 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; more preferably a branched alkyl group having 3 to 12 carbon atoms, a branched alkoxy group having 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; even more preferably a branched alkyl group having 3 to 8 carbon atoms or a branched alkoxy group having 3 to 8 carbon atoms; and particularly preferred a t-butyl group.

[0117] In formula (P6), R 62 and R 64 Each of these groups is preferably, independently from the viewpoint of electron transport, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms; more preferably, a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a linear alkoxy group having 1 to 4 carbon atoms; even more preferably, a linear alkyl group having 1 to 3 carbon atoms or a linear alkoxy group having 1 to 3 carbon atoms; and particularly preferably, a methyl group.

[0118] In formula (P6), R 61 and R 64 It is preferable that they are the same group. In formula (P6), R 62 and R 63 It is preferable that they are the same group. In formula (P6), R 61 and R 62 These are preferably different groups. In formula (P6), R 63 and R 64 These are preferably different groups.

[0119] The following are examples of compounds represented by formula (P6), but this embodiment is not limited to these.

[0120] [ka]

[0121] The abbreviations and symbols in the above example compounds have the following meanings. ·t-C4H9: t-butyl group • CH3O: Methoxy ·t-C4H9O:t-butoxy group · c-C6H 11 : Cyclohexyl group • C6H5: Phenyl group • C6H5CH2: Benzyl group

[0122] - Compound represented by formula (P7) - The compound represented by formula (P7) will be explained below.

[0123] [ka]

[0124] In formula (P7), R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 and R 78 (Hereinafter referred to as “R 71 ~R 78 It is also called ). Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0125] In formula (P7), R 71 ~R 78Examples of alkyl groups represented by include linear or branched alkyl groups having 1 to 4 carbon atoms (preferably 1 to 3 carbon atoms), specifically, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, etc. In formula (P7), R 71 ~R 78 Examples of alkoxy groups include alkoxy groups having 1 to 4 carbon atoms (preferably 1 to 3 carbon atoms), specifically methoxy groups, ethoxy groups, propoxy groups, butoxy groups, and the like.

[0126] In formula (P7), R 71 ~R 78 An example of an aralkyl group represented by -L-Ar is the group denoted as -L-Ar, where L represents an alkylene group and Ar represents an aryl group. Examples of alkylene groups represented by L include linear or branched alkylene groups having 1 to 12 carbon atoms, such as methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, tert-butylene group, n-pentylene group, isopentylene group, neopentylene group, and tert-pentylene group. Examples of aryl groups represented by Ar include phenyl group, methylphenyl group, dimethylphenyl group, and ethylphenyl group. In formula (P7), R 71 ~R 78 Specific examples of the aralkyl group shown include, for example, the benzyl group, methylbenzyl group, dimethylbenzyl group, phenylethyl group, methylphenylethyl group, phenylpropyl group, and phenylbutyl group.

[0127] In formula (P7), R 71 ~R 78 Examples of aryl groups include phenyl, methylphenyl, dimethylphenyl, and ethylphenyl groups. Among these, the phenyl group is preferred.

[0128] In formula (P7), R 71 ~R78 The acyl group (-C(=O)-R) shown by AC , the R AC ∫ represents a hydrocarbon group. Examples of such groups include acyl groups having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms), specifically including acetyl groups, propanoyl groups, benzoyl groups, cyclohexanecarbonyl groups, and the like.

[0129] In formula (P7), R 71 ~R 78 The alkoxycarbonyl group represented by is R in formula (P1). 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0130] In formula (P7), R 71 ~R 78 The alkyl, alkoxy, aralkyl, aryl, and alkoxycarbonyl groups shown are R in general formula (1). 11 ~R 18 The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by may have substituents similar to those listed above. In formula (P7), R 71 ~R 78 The acyl group represented by is R in formula (P1). 11 ~R 18 The alkyl group represented by may have substituents similar to those listed above.

[0131] In formula (P7), R 71 ~R 78 Examples of halogen atoms represented include fluorine, chlorine, bromine, and iodine atoms.

[0132] In formula (P7), R 78 From the perspective of electron transport, the alkoxycarbonyl group (-C(=O)-OR 78A ) is preferable. 78A This is an alkyl group (long-chain alkyl group) with 8 or more carbon atoms or -L181 -OR 182 This indicates L 181 R indicates an alkylene group, 182 This indicates an alkyl group (long-chain alkyl group) with 8 or more carbon atoms.

[0133] In formula (P7), R 78 -L 181 -OR 182 The group represented by L 181 R indicates an alkylene group, 182 This represents an alkyl group (long-chain alkyl group) with 8 or more carbon atoms.

[0134] L 181 Examples of alkylene groups represented by include linear or branched alkylene groups having 1 to 12 carbon atoms, such as methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, tert-butylene group, n-pentylene group, isopentylene group, neopentylene group, and tert-pentylene group.

[0135] R 182 The long-chain alkyl group represented by is not particularly limited as long as it has 8 or more carbon atoms, but from the viewpoint of suppressing cracking of the photosensitive layer, it is preferable that it has 8 to 12 carbon atoms. Furthermore, the long-chain alkyl group may be linear or branched, but it is preferable that it be linear. Examples of linear alkyl groups having 8 to 12 carbon atoms include n-octyl, n-nonyl, n-decyl, n-undecyl, and n-dodecyl groups. Examples of branched alkyl groups having 8 to 12 carbon atoms include isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, and tert-decyl groups.

[0136] The compound represented by formula (P7) may have only one long-chain alkyl group in one molecule, or it may have two or more. From the viewpoint of suppressing cracking of the photosensitive layer, the number of long-chain alkyl groups in one molecule of the compound represented by formula (P7) is preferably 1 to 3, and more preferably 1 to 2.

[0137] In one embodiment, the compound represented by formula (P7) is R from the viewpoint of electron transport. 71 ~R 77 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl group, R 78 Compounds exhibiting a linear alkyl group with 8 or fewer carbon atoms are preferred.

[0138] The following are examples of compounds represented by formula (P7), but are not limited to these. The example compound numbers below will be referred to as Example Compound (7-number). Specifically, for example, Example Compound 5 will be referred to as "Example Compound (7-5)".

[0139] [ka]

[0140] The abbreviations and symbols in the above example compounds have the following meanings. ·=C(CN)2: dicyanomethylene group

[0141] - Compound represented by formula (P8) - The compound represented by formula (P8) will be explained below.

[0142] [ka]

[0143] In formula (P8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 , R 87 and R 88(Hereafter simply "R 81 ~R 88 It is also called ). Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0144] In formula (P8), R 81 ~R 88 The alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, and halogen atom represented by formula (P7) are R 71 ~R 78 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula]. In formula (P8), R 81 ~R 88 The acyl group represented by is R in formula (P1). 11 ~R 18 The alkyl group represented by may have substituents similar to those listed above.

[0145] The following are examples of compounds represented by formula (P8), but are not limited to these. The example compound numbers below will be referred to as Example Compound (8-number). Specifically, for example, Example Compound 5 will be referred to as "Example Compound (8-5)".

[0146] [ka]

[0147] The abbreviations and symbols in the above example compounds have the following meanings. • C(=O)CH3: Acetyl group • OCH3: Methoxy group • CN: cyano group • CH2C6H5: benzyl group ·=C(CN)2: dicyanomethylene group

[0148] From the viewpoint of chargeability and ghost suppression, the content of the electron transport compound is preferably 30% to 80% by mass, more preferably 50% to 80% by mass, even more preferably 52% to 75% by mass, and particularly preferably 55% to 70% by mass, based on the total mass of the undercoat.

[0149] -Binding resin- The undercoat preferably contains a binder resin. The type of binder resin included in the base layer is not limited. Examples of binder resins included in the base layer include polyurethane, polyvinyl alcohol resin, polyvinyl acetal resin (including polyvinyl butyral, i.e., butyral resin), casein resin, polyamide resin, cellulose resin, gelatin, polyester resin, unsaturated polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, alkyd resin, epoxy resin, etc. The binder resin may be used alone or in combination of two or more types.

[0150] From the viewpoint of further improving the charge retention of the undercoat layer, it is preferable to include polyurethane as the binder resin. When polyurethane is used as the binder resin, the charge retention is superior compared to when other types of binder resins are used. The mechanism for this is thought to be that polyurethane has a high effect (trapping effect) of suppressing the injection of the internal charge (dark carriers) of the electron-transporting compound particles contained in the undercoat layer into the electron-transporting compound particles, so the potential on the surface of the photoreceptor does not easily decrease.

[0151] Polyurethane may also be synthesized by a polyaddition reaction between polyisocyanate and polyol.

[0152] Examples of polyisocyanates include methylene diisocyanate, ethylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, and 3,3'-dimethylene diisocyanate. Examples include diisocyanates such as 4,4'-diphenylmethane diisocyanate, 3,3'-dimethylbiphenylenediisocyanate, 4,4'-biphenylenediisocyanate, dicyclohexylmethane diisocyanate, and methylenebis(4-cyclohexylisocyanate); isocyanurates obtained by trimerizing the diisocyanates; and blocked isocyanates obtained by blocking the isocyanate groups of the diisocyanates with a blocking agent. Among the above, polyisocyanates are preferably polyfunctional, such as isocyanurates having multiple isocyanate groups. One type of polyisocyanate may be used, or two or more types may be used in combination.

[0153] Examples of polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 2,2-dimethyl-1,3-propanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 3,3-dimethyl-1,2-butanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,2-diethyl-1,3-propanediol, and 2,4-dimethyl-2,4-pentanediol. Examples of diols include diols such as 1,7-heptanediol, 2-methyl-2-propyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, hydroquinone, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol, poly(oxytetramethylene) glycol, 4,4'-dihydroxydiphenyl-2,2-propane, and 4,4'-dihydroxyphenylsulfone. Examples of polyols include polyester polyols, polycarbonate polyols, polycaprolactone polyols, polyether polyols, and polyvinyl butyral. One type of polyol may be used, or two or more types may be used in combination.

[0154] Examples of urethane curing catalysts (i.e., catalysts for the polyaddition reaction between polyisocyanates and polyols) include amine compounds, organic acid metal salts, and organometallic complexes. Examples of amine compounds include 1,4-diazabicyclo(2,2,2)octane, N,N-dimethylcyclohexylamine, N-methyldicyclohexylamine, N,N,N',N'-tetramethylpropylenediamine, N-ethylmorpholine, N-methylmorpholine, N,N-dimethylethanolamine, 1,8-diazabicyclo[5,4,0]undecene-7 (DBU) and its salts. Examples of organic acid metal salts or organometallic complexes include dibutyltin laurate, stanus octoate, bismuth octoate, bismuth naphthenate, bismuth salicylate, zinc octoate, zinc naphthenate, and zinc salicylate. Examples of commercially available urethane curing catalysts include the K-KAT series from King Industries, Ltd., such as bismuth carboxylate catalysts like K-KAT348, K-KAT XC-C227, K-KAT XK-628, and K-KAT XK-640; aluminum complex catalysts like K-KAT5218; zirconium complex catalysts like K-KAT4205, K-KAT6212, and K-KATA209; and titanium complex catalysts like TA-30 and TC-750 from Matsumoto Fine Chemicals' Orgatics series.

[0155] When butyral resin is included as the binder resin, the butyral resin content is preferably 0.5% to 20% by mass, and more preferably 1% to 10% by mass, relative to the total mass of the undercoat layer, from the viewpoint of electrostatic properties and ghost suppression.

[0156] The binder resin contained in the base layer is preferably composed of polyurethane in an amount of 80% to 100% by mass of the total amount of binder resin, more preferably 90% to 100% by mass of polyurethane, and even more preferably 95% to 100% by mass of polyurethane.

[0157] The mass ratio of the total content of the electron-transporting compound in the undercoat to the content of polyurethane in the undercoat is preferably 90:10 to 50:50 for the electron-transporting compound to polyurethane, and more preferably 80:20 to 70:30.

[0158] <<Inorganic particles>> The undercoat may contain inorganic particles, but from the viewpoint of electrostatic properties, it is preferable that it does not contain them. As for inorganic particles, for example, powder resistance (volume resistivity) 10 2 Ωcm or more 10 11 Examples include inorganic particles smaller than Ωcm. Among these, suitable inorganic particles having the above-mentioned resistance values ​​include, for example, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, with zinc oxide particles being particularly preferred.

[0159] The specific surface area of ​​inorganic particles using the BET method is, for example, 10 m². 2 A value of 10 m² or more is preferable. 2 When the value is above / g, the decrease in chargeability tends to be suppressed. The volume-average particle size of the inorganic particles is preferably between 50 nm and 2000 nm (preferably between 60 nm and 1000 nm).

[0160] The inorganic particle content is preferably 10% by mass or more and 80% by mass or less relative to the binder resin, and more preferably 40% by mass or more and 80% by mass or less.

[0161] The inorganic particles may be surface-treated. Two or more types of inorganic particles with different surface treatments or particle sizes may be mixed and used.

[0162] Examples of surface treatment agents include silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and surfactants. Silane coupling agents are particularly preferred, and silane coupling agents having an amino group are more preferred.

[0163] Examples of silane coupling agents having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0164] Silane coupling agents may be used in combination of two or more types. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0165] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry or wet method.

[0166] The amount of surface treatment agent applied is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0167] The inorganic particle content is preferably, for example, 0.01% by mass or more and 20% by mass or less relative to the inorganic particles, and more preferably 0.01% by mass or more and 10% by mass or less.

[0168] Here, the lower layer may contain electron-accepting compounds (acceptor compounds) along with inorganic particles.

[0169] Examples of electron-accepting compounds include quinone compounds such as chloranil and bromonil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; and diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; as well as other electron-transporting substances. In particular, compounds having an anthraquinone structure are preferred as electron-accepting compounds. Examples of compounds having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds, and specifically, for example, anthraquinone, alizarin, quinizalin, anthralphine, and purpurin are preferred.

[0170] The electron-accepting compound may be dispersed in the underlayer together with inorganic particles, or it may be present attached to the surface of the inorganic particles.

[0171] Methods for attaching electron-accepting compounds to the surface of inorganic particles include, for example, dry methods or wet methods.

[0172] The dry method involves, for example, adding an electron-accepting compound, either directly or dissolved in an organic solvent, dropwise while stirring inorganic particles with a mixer that has a high shear force, or spraying it with dry air or nitrogen gas, to adhere the electron-accepting compound to the surface of the inorganic particles. When adding or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After adding or spraying the electron-accepting compound, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained.

[0173] The wet method involves dispersing inorganic particles in a solvent using methods such as stirring, ultrasound, sand milling, attritoring, and ball milling, while adding an electron-accepting compound. After stirring or dispersion, the solvent is removed to adhere the electron-accepting compound to the surface of the inorganic particles. Solvent removal methods include, for example, filtration or distillation. After solvent removal, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may be removed before adding the electron-accepting compound. Examples of this include removing water while stirring and heating in the solvent, or removing water by azeotrope with the solvent.

[0174] Furthermore, the attachment of the electron-accepting compound may be performed before or after surface treatment with a surface treatment agent on the inorganic particles, or it may be performed simultaneously with the attachment of the electron-accepting compound and surface treatment with the surface treatment agent.

[0175] The content of the electron-accepting compound is preferably, for example, 0.01% by mass or more and 20% by mass or less relative to the inorganic particles, and more preferably 0.01% by mass or more and 10% by mass or less.

[0176] <<Additives>> The undercoat may contain various additives to improve electrical properties, environmental stability, and image quality. Examples of known additives include polycyclic condensation compounds, azo compounds, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but they may also be added to the undercoat as an additive.

[0177] Examples of silane coupling agents used as additives include vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0178] Examples of zirconium chelate compounds include zirconium butoxide, ethyl zirconium acetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0179] Examples of titanium chelate compounds include tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0180] Examples of aluminum chelating compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0181] These additives may be used individually or as a mixture or polycondensate of multiple compounds.

[0182] <<Other properties of the lower layer>> The thickness of the undercoat layer is preferably 1 μm or more, and more preferably 3 μm or more. From the viewpoint of superior charge retention, the thickness of the undercoat layer is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

[0183] The volume resistivity of the lower layer is 1 × 10⁻⁶ 10 Ωcm or more, 1 × 10 12 It is preferable that the density is Ωcm or less.

[0184] The underlayer should ideally have a Vickers hardness of 35 or higher. The surface roughness (ten-point average roughness) of the undercoat layer should be adjusted to between 1 / (4n) (where n is the refractive index of the upper layer) and 1 / 2 of the exposure laser wavelength λ used, in order to suppress moiré patterns. Resin particles may be added to the undercoat to adjust the surface roughness. Examples of resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. The surface of the undercoat may also be polished to adjust the surface roughness. Polishing methods include buffing, sandblasting, wet honing, and grinding.

[0185] <<Method for forming the lower layer>> There are no particular restrictions on the formation of the undercoat layer, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of an undercoat-forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0186] Examples of solvents for preparing the coating solution for forming the undercoat include known organic solvents such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellsolve, ethyl cellsolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. In particular, solvents having at least one hydroxyl group (e.g., alcohols) or ether solvents (e.g., tetrahydrofuran) are preferred.

[0187] Known methods for dispersing electron-transporting compounds when preparing a coating solution for forming an undercoat include, for example, roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, and paint shakers. When electron-transporting compounds are poorly soluble in organic solvents, it is desirable to disperse them in the organic solvent. Known dispersion methods include, for example, roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, and paint shakers.

[0188] Conventional methods for applying the undercoating solution onto a conductive support include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0189] [Charge generation layer] The charge generation layer contains a phthalocyanine compound, and preferably contains a phthalocyanine compound and a binder resin. Alternatively, the charge generation layer may be a vapor-deposited layer of the phthalocyanine compound. A vapor-deposited layer of the phthalocyanine compound is suitable when using non-coherent light sources such as LEDs (Light Emitting Diodes) and organic EL (Electro-Luminescence) image arrays.

[0190] For phthalocyanine compounds, it is preferable to use metallic phthalocyanine compounds or metal-free phthalocyanine compounds to accommodate laser exposure in the near-infrared region. Specifically, for example, hydroxygallium phthalocyanine disclosed in Japanese Patent Publication No. 5-263007, Japanese Patent Publication No. 5-279591, etc.; chlorogallium phthalocyanine disclosed in Japanese Patent Publication No. 5-98181, etc.; dichlorotin phthalocyanine disclosed in Japanese Patent Publication No. 5-140472, Japanese Patent Publication No. 5-140473, etc.; and titanyl phthalocyanine disclosed in Japanese Patent Publication No. 4-189873, etc. are more preferable.

[0191] Among the phthalocyanine compounds, gallium phthalocyanine compounds or titanyl phthalocyanine compounds are preferred from the viewpoint of electrostatic charge and ghost suppression, gallium phthalocyanine compounds are more preferred, and hydroxygallium phthalocyanine compounds are particularly preferred.

[0192] The binder resin used in the charge generation layer can be selected from a wide range of insulating resins, or it may be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Examples of binder resins include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenols and aromatic divalent carboxylic acids, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinylpyrrolidone resin. Here, "insulating properties" refers to a volume resistivity of 10 13 This refers to a value of Ωcm or greater. These binder resins can be used individually or in combination of two or more types.

[0193] Furthermore, the mixing ratio of the phthalocyanine compound to the binder resin is preferably within the range of 10:1 to 1:10 by mass.

[0194] The charge generation layer may also contain other well-known additives.

[0195] The formation of the charge generation layer is not particularly limited, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of a coating solution for forming a charge generation layer by adding the above components to a solvent, drying the coating film, and heating it as necessary. The charge generation layer may also be formed by vapor deposition of the charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when using fused ring aromatic compounds or perylene compounds as the charge generation material.

[0196] Solvents for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellsolve, ethyl cellsolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. These solvents may be used individually or in mixtures of two or more.

[0197] Methods for dispersing particles (e.g., phthalocyanine compounds) in a coating solution for forming a charge generation layer include, for example, media dispersers such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, as well as media-less dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include collision methods, which disperse the dispersion by causing liquid-liquid collisions or liquid-wall collisions under high pressure, and penetration methods, which disperse the dispersion by penetrating fine channels under high pressure. Furthermore, during this dispersion, it is effective to set the average particle size of the phthalocyanine compound in the coating solution for forming the charge generation layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0198] Conventional methods for applying the charge-generating layer forming solution onto the undercoat (or intermediate layer) include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0199] The thickness of the charge generation layer is preferably set to a range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

[0200] [Charge transport layer] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer containing a polymer charge transport material.

[0201] Examples of charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds, which are electron transport compounds. Other examples of charge transport materials include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used individually or in combination of two or more, but are not limited to these uses.

[0202] As charge transport materials, from the viewpoint of charge mobility, the triarylamine derivative shown in the following structural formula (a-1) and the benzidine derivative shown in the following structural formula (a-2) are preferred.

[0203] [ka]

[0204] In structural formula (a-1), Ar T1 Ar T2 , and Ar T3 These are, independently, a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ) indicates R T4 , R T5 , R T6 , R T7 , and R T8 Each of these independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0205] [ka]

[0206] In structural formula (a-2), R T91 and R T92 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 Each of these independently consists of a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, and -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) represents R T12 , R T13 , R T14 , R T15 and R T16 Each of these independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer between 0 and 2, inclusive. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0207] Here, among the triarylamine derivative represented by structural formula (a-1) and the benzidine derivative represented by structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(RT7 )(R T8 Triarylamine derivatives having ")" and "-CH=CH-CH=C(R T15 )(R T16 A benzidine derivative having ) is preferred from the viewpoint of charge mobility.

[0208] As the polymer charge transport material, known materials with charge transport properties such as poly-N-vinylcarbazole and polysilane can be used. In particular, polyester-based polymer charge transport materials disclosed in Japanese Patent Publication No. 8-176293, Japanese Patent Publication No. 8-208820, etc. are especially preferred. The polymer charge transport material may be used alone, or it may be used in combination with a binder resin.

[0209] Examples of binder resins used in the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, and polysilane. Among these, polycarbonate resin or polyarylate resin is preferred as the binder resin. These binder resins can be used individually or in combination of two or more. The preferred mixing ratio of the charge transport material to the binder resin is between 10:1 and 1:5 by mass.

[0210] The charge transport layer may also contain other well-known additives.

[0211] The formation of the charge transport layer is not particularly limited, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of a charge transport layer forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0212] Solvents for preparing the coating solution for forming the charge transport layer include common organic solvents such as aromatic hydrocarbons like benzene, toluene, xylene, and chlorobenzene; ketones like acetone and 2-butanone; halogenated aliphatic hydrocarbons like methylene chloride, chloroform, and ethylene chloride; and cyclic or linear ethers like tetrahydrofuran and ethyl ether. These solvents can be used individually or in mixtures of two or more.

[0213] Conventional methods for applying a charge transport layer forming coating solution onto a charge generation layer include blade coating, wire bar coating, spray coating, immersion coating, bead coating, air knife coating, and curtain coating.

[0214] The thickness of the charge transport layer is set, for example, preferably within the range of 5 μm to 50 μm, and more preferably within the range of 10 μm to 30 μm.

[0215] [Conductive support] Examples of conductive supports include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Other examples of conductive supports include paper, resin films, belts, etc., coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. Here, "conductivity" refers to a volume resistivity of 10 13 This refers to a value less than Ωcm.

[0216] When an electrophotographic photoreceptor is used in a laser printer, the surface of the conductive support is preferably roughened to a center-line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiated with laser light. While roughening to prevent interference fringes is not particularly necessary when using non-interfering light as the light source, it is beneficial for extending the lifespan of the conductive support by suppressing the occurrence of defects due to surface irregularities.

[0217] Methods for roughening the surface include, for example, wet honing, which is performed by suspending an abrasive in water and spraying it onto a conductive support; centerless grinding, which is performed by pressing a conductive support against a rotating grinding wheel and continuously grinding it; and anodizing.

[0218] One method for roughening the surface is to disperse conductive or semiconductive powder in a resin without roughening the surface of the conductive support, to form a layer on the surface of the conductive support, and then roughen the surface with the particles dispersed in that layer.

[0219] Anodizing roughening treatment involves forming an oxide film on the surface of a conductive support by using a metal (e.g., aluminum) conductive support as the anode and anodic oxidizing it in an electrolyte solution. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodizing is chemically active, easily contaminated, and exhibits large resistance fluctuations depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film to block the micropores of the oxide film by volume expansion due to a hydration reaction using pressurized steam or boiling water (metal salts such as nickel may be added), thereby converting it into a more stable hydrated oxide.

[0220] The thickness of the anodic oxide film is preferably, for example, 0.3 μm to 15 μm. When the film thickness is within this range, it tends to exhibit barrier properties against injection and tends to suppress the increase in residual potential due to repeated use.

[0221] The conductive support may be treated with an acidic treatment solution or with boehmite. Treatment with an acidic solution is carried out, for example, as follows: First, an acidic solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic solution is, for example, in the range of 10% to 11% by mass for phosphoric acid, 3% to 5% by mass for chromic acid, and 0.5% to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness is preferably 0.3 μm to 15 μm.

[0222] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting it with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. This can be further treated with anodic oxidation using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0223] [Middle class] Although not shown in the diagram, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer (preferably a charge generation layer). The intermediate layer is, for example, a layer containing a resin. Examples of resins used in the intermediate layer include polymer compounds such as acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin. The intermediate layer may contain an organometallic compound. Examples of organometallic compounds used in the intermediate layer include those containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in these intermediate layers may be used individually, as a mixture of multiple compounds, or as polycondensates.

[0224] Among these, the intermediate layer is preferably a layer containing an organometallic compound that contains zirconium atoms or silicon atoms.

[0225] There are no particular restrictions on the formation of the intermediate layer, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of an intermediate layer-forming coating solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary. Conventional methods such as immersion coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating are used to form the intermediate layer.

[0226] The thickness of the intermediate layer is preferably set to a range of 0.1 μm to 3 μm, for example. The intermediate layer may also be used as a base layer.

[0227] [Protective layer] A protective layer is provided on the photosensitive layer as needed. The protective layer is provided, for example, to prevent chemical changes in the photosensitive layer when charged, or to further improve the mechanical strength of the photosensitive layer. Therefore, it is preferable to apply a protective layer composed of a cured film (crosslinked film). Examples of such layers include those shown in 1) or 2) below.

[0228] 1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge transport skeleton within the same molecule (i.e., a layer containing a polymer or crosslinked form of the reactive group-containing charge transport material). 2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a non-charge transport material containing reactive groups that does not have a charge transport skeleton but has reactive groups (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked form of the non-charge transport material containing reactive groups).

[0229] The reactive groups in the reactive group-containing charge transport materials include chain polymerizable groups, epoxy groups, -OH, -OR [where R represents an alkyl group], -NH2, -SH, -COOH, and -SiR. Q1 3-Qn (OR Q2 ) Qn [However, R Q1 R represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group. Q2 Examples of well-known reactive groups include hydrogen atoms, alkyl groups, and trialkylsilyl groups. Qn represents an integer from 1 to 3.

[0230] The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, for example, a functional group having at least one carbon double bond. Specifically, examples include groups containing at least one selected from vinyl groups, vinyl ether groups, vinyl thioether groups, styryl groups (vinyl phenyl groups), acryloyl groups, methacryloyl groups, and their derivatives. Among these, the chain polymerizable group is preferably a group containing at least one selected from vinyl groups, styryl groups (vinyl phenyl groups), acryloyl groups, methacryloyl groups, and their derivatives, due to its excellent reactivity.

[0231] The charge-transporting skeleton of the reactive group-containing charge-transporting material is not particularly limited as long as it is a known structure in electrophotographic photoreceptors. Examples include skeletons derived from nitrogen-containing hole-transporting compounds such as triarylamine compounds, benzidine compounds, and hydrazone compounds, in which the nitrogen atom is conjugated. Among these, the triarylamine skeleton is preferred.

[0232] These reactive groups and charge-transporting skeletons, including reactive group-containing charge transport materials, non-reactive charge transport materials, and reactive group-containing non-charge transport materials, can be selected from well-known materials.

[0233] The protective layer may also contain other well-known additives.

[0234] There are no particular restrictions on the formation of the protective layer, and well-known formation methods can be used. For example, it can be formed by adding the above components to a solvent to create a protective layer coating solution, drying the coating, and then performing a curing treatment such as heating as necessary.

[0235] Solvents for preparing coating solutions for forming a protective layer include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; and alcohol solvents such as isopropyl alcohol and butanol. These solvents can be used individually or in combination of two or more. Furthermore, the coating solution for forming the protective layer may be a solvent-free coating solution.

[0236] Conventional methods for applying a protective layer-forming coating solution onto a photosensitive layer (e.g., a charge transport layer) include immersion coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

[0237] The thickness of the protective layer is set, for example, preferably within the range of 1 μm to 20 μm, and more preferably within the range of 2 μm to 10 μm.

[0238] [Single-layer photosensitive layer] A single-layer photosensitive layer (charge generation layer) is a layer comprising, for example, a charge generation material (phthalocyanine compound), a charge transport material, and optionally a binder resin and other well-known additives. These materials are the same as those described for the charge generation layer and charge transport layer. Furthermore, the content of the phthalocyanine compound in the single-layer photosensitive layer is preferably 0.1% to 10% by mass, and more preferably 0.8% to 5% by mass, relative to the total mass. In addition, the content of the charge transport material in the single-layer photosensitive layer is preferably 5% to 50% by mass, relative to the total mass. The method for forming a single-layer photosensitive layer is the same as the method for forming a charge generation layer or a charge transport layer. The thickness of the single-layer photosensitive layer is, for example, preferably 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

[0239] (Image forming apparatus and process cartridges) The image forming apparatus according to this embodiment comprises an electrophotographic photoreceptor, a charging means for charging the surface of the electrophotographic photoreceptor, an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, and a transfer means for transferring the toner image to the surface of a recording medium. The electrophotographic photoreceptor according to this embodiment is used as the electrophotographic photoreceptor.

[0240] The image forming apparatus according to this embodiment includes a fixing means for fixing a toner image transferred to the surface of a recording medium; a direct transfer method apparatus for directly transferring a toner image formed on the surface of an electrophotographic photoreceptor to a recording medium; an intermediate transfer method apparatus for first transferring a toner image formed on the surface of an electrophotographic photoreceptor to the surface of an intermediate transfer body, and secondarily transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; a cleaning means for cleaning the surface of the electrophotographic photoreceptor after the transfer of the toner image and before it is charged; a static elimination means for irradiating the surface of the electrophotographic photoreceptor with static elimination light to eliminate static charge after the transfer of the toner image and before it is charged; and a well-known image forming apparatus such as an electrophotographic photoreceptor heating member for raising the temperature of the electrophotographic photoreceptor and reducing the relative temperature.

[0241] In the case of an intermediate transfer method apparatus, the transfer means may include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer means for primaryly transferring the toner image formed on the surface of an electrophotographic photoreceptor to the surface of the intermediate transfer body; and a secondary transfer means for secondary transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium.

[0242] The image forming apparatus according to this embodiment may be either a dry developing type image forming apparatus or a wet developing type image forming apparatus (a developing method using a liquid developer).

[0243] In the image forming apparatus according to this embodiment, for example, the portion comprising the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge comprising the electrophotographic photoreceptor according to this embodiment is preferably used. In addition to the electrophotographic photoreceptor, the process cartridge may also include at least one selected from the group consisting of, for example, a charging means, an electrostatic latent image forming means, a developing means, and a transfer means.

[0244] The following is an example of an image forming apparatus according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will be omitted from the explanation.

[0245] Figure 2 is a schematic diagram showing an example of an image forming apparatus according to this embodiment. As shown in Figure 2, the image forming apparatus 100 according to this embodiment includes a process cartridge 300 equipped with an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming means), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is positioned to expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 is positioned facing the electrophotographic photoreceptor 7 via the intermediate transfer body 50, with a portion of the intermediate transfer body 50 in contact with the electrophotographic photoreceptor 7. Although not shown, the apparatus also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) are examples of transfer means.

[0246] In Figure 2, the process cartridge 300 integrally supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging means), a developing device 11 (an example of a developing means), and a cleaning device 13 (an example of a cleaning means) within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is positioned to contact the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member, rather than a cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

[0247] Figure 2 shows an example of an image forming apparatus equipped with a fibrous member 132 (roll-shaped) for supplying lubricant 14 to the surface of the electrophotographic photoreceptor 7, and a fibrous member 133 (flat brush-shaped) for assisting cleaning. These can be arranged as needed.

[0248] The following describes the various components of the image forming apparatus according to this embodiment.

[0249] -Charging device- As the charging device 8, for example, a contact-type charger using conductive or semiconductive charging rollers, charging brushes, charging films, charging rubber blades, charging tubes, etc. may be used. Non-contact roller chargers, known chargers such as scorotron chargers and corotron chargers that utilize corona discharge may also be used.

[0250] -Exposure equipment- Examples of exposure devices 9 include optical equipment that exposes the surface of an electrophotographic photoreceptor 7 to a predetermined image using light such as semiconductor laser light, LED light, or liquid crystal shutter light. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photoreceptor. As for the wavelength of the semiconductor laser, near-infrared lasers with an oscillation wavelength of around 780 nm are the mainstream. However, the wavelength is not limited to this, and lasers with oscillation wavelengths in the 600 nm range or blue lasers with oscillation wavelengths between 400 nm and 450 nm may also be used. Furthermore, for color image formation, surface-emitting laser light sources capable of outputting multiple beams are also effective.

[0251] -Developing equipment- Examples of developing devices 11 include general developing devices that develop by contacting or not contacting the developing agent. There are no particular restrictions on the developing device 11 as long as it has the above-described functions, and it can be selected according to the purpose. For example, known developing devices that have the function of applying a one-component or two-component developing agent to the electrophotographic photoreceptor 7 using a brush, roller, etc. Among these, those that use a developing roller that holds the developing agent on its surface are preferred.

[0252] The developer used in the developing device 11 may be a one-component developer consisting of toner alone, or a two-component developer containing toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. Well-known developers are applicable.

[0253] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131. In addition to the cleaning blade method, a fur brush cleaning method or a developing-simultaneous cleaning method may also be used.

[0254] -Transfer device- Examples of the transfer device 40 include contact-type transfer chargers using belts, rollers, films, rubber blades, etc., and transfer chargers that are known themselves, such as scorotron transfer chargers and corotron transfer chargers that utilize corona discharge.

[0255] -Intermediate Transcript- As the intermediate transfer body 50, a belt-shaped material (intermediate transfer belt) containing semiconducting polyimide, polyamide-imide, polycarbonate, polyarylate, polyester, rubber, etc. is used. In addition to the belt shape, a drum-shaped intermediate transfer body may also be used.

[0256] Figure 3 is a schematic diagram showing another example of the image forming apparatus according to this embodiment. The image forming apparatus 120 shown in Figure 3 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one electrophotographic photoreceptor is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem type. [Examples]

[0257] The electrophotographic photoreceptor according to this embodiment will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing procedures, etc., shown in the following examples can be modified as appropriate without departing from the spirit of this embodiment. Therefore, the scope of the electrophotographic photoreceptor according to this embodiment should not be interpreted as being limited by the specific examples shown below.

[0258] [Example 1] (Formation of the lower layer) 33 parts by mass of ETM3, 6 parts by mass of blocked isocyanate (product name: Sumijule 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), 1 part by mass of a compound represented by the following structural formula (AK-1), and 25 parts by mass of methyl ethyl ketone were mixed for 30 minutes. Then, 5 parts by mass of butyral resin (product name: Esrec BM-1, manufactured by Sekisui Chemical Co., Ltd.), 3 parts by mass of silicone balls (product name: Tospar 120, manufactured by Momentive Performance Materials, Inc.), and 0.01 parts by mass of Toray Dow Corning silicone oil (product name: SH29PA, manufactured by Dow Corning) as a leveling agent were added, and the mixture was dispersed in a sand mill for 1.8 hours (i.e., the dispersion time was 1.8 hours) to obtain a coating solution for forming an undercoat.

[0259] [ka]

[0260] [ka]

[0261] Furthermore, the coating solution for forming the undercoat layer obtained by the immersion coating method was applied to an aluminum substrate (conductive support) with a diameter of 47 mm, a length of 357 mm, and a wall thickness of 1 mm, and dried and cured at 180°C for 30 minutes to obtain an undercoat layer with a thickness of 5 μm.

[0262] (Formation of charge generation layer 1) As a charge generating material, The CGM3 described later A mixture of 15 parts by mass of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.), 10 parts by mass of vinyl chloride / vinyl acetate copolymer resin, and 200 parts by mass of n-butyl acetate was dispersed in a sand mill for 4 hours using glass beads with a diameter of 1 mm. 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added to the resulting dispersion and stirred to obtain a coating solution for forming the charge generation layer. This coating solution was applied to the undercoat by immersion and dried at 150°C for 10 minutes to form a charge generation layer 1 with a thickness of 0.2 μm.

[0263] (Formation of charge transport layer 1) 38 parts by mass of charge transport agent (HT-1), 10 parts by mass of charge transport agent (HT-2), and 52 parts by mass of polycarbonate (A) (viscosity average molecular weight 48,000) were dissolved in 800 parts by mass of tetrahydrofuran. 8 parts by mass of tetrafluoroethylene resin (Lubron L5, manufactured by Daikin Industries, Ltd., average particle size 300 nm) were added, and the mixture was dispersed at 5,500 rpm for 2 hours using a homogenizer (Ultra-Turrax, manufactured by IKA) to obtain a coating solution for forming the charge transport layer. This coating solution was immersed and coated onto the charge generating layer 1, and dried at 140°C for 40 minutes to form a charge transport layer 1 with a thickness of 26 μm. The electrophotographic photoreceptor of Example 1 was obtained by the above treatment.

[0264] [ka]

[0265] [ka]

[0266] [Examples 2 to 14, and Comparative Example 1 to 3, 5, 7 through 10 and 12 ] An electrophotographic photoreceptor was obtained in the same manner as in Example 1, except that the formation of the undercoat layer, the charge generation layer 1, and the charge transport layer 1 were modified as appropriate as shown in Table 1.

[0267] (Formation of charge generation layer 2) A charge generation layer 2 was obtained in the same manner as charge generation layer 1, except that the thickness of charge generation layer 1 was changed to 0.15 μm.

[0268] (Formation of charge transport layer 2) In forming the charge transport layer 1, the charge transport layer 2 was obtained in the same manner as the charge transport layer 1, except that the thickness was changed to 32.0 μm.

[0269] <Rating> -Evaluation of electrostatic properties- The electrostatic properties of the photoreceptor were evaluated as follows. The photoreceptor was incorporated into a photoreceptor electrical characteristics evaluation device manufactured by Fujifilm Business Innovation Co., Ltd., which is equipped with a photoreceptor charging device, an exposure device, and a static elimination device. After performing a series of steps of charging, exposure, and static elimination in one cycle under the conditions described below, charging was performed again, and the charge potential of the photoreceptor surface was measured, with this value defined as VH1. Subsequently, the evaluation device was operated for one cycle under the conditions described below without performing the series of steps of charging, exposure, and static elimination, and the charge potential of the photoreceptor surface was measured, with this value defined as VH2. The absolute value of ΔVH was then calculated as the difference between VH1 and VH2. The electrostatic potential of the photoreceptor surface was measured at a distance of 1 mm from the surface using a surface potential meter (Trek 334, manufactured by Trek). (conditions) ·Measurement environment: temperature 20℃ / humidity 40%RH • Charging potential: -400V ·Exposure light amount: 4mJ / m 2 • Exposure wavelength: 780nm • Static elimination light source: Halogen lamp (manufactured by Hayashi Clock Industry Co., Ltd.) · Static elimination light wavelength: 600nm or more and 800nm ​​or less ·Electrostatic light intensity: 30mJ / m 2 • Rotation speed of the photoconductor: 66.7 rpm A: ΔVH is 5V or less B: ΔVH is greater than 5V and less than or equal to 10V C:ΔVH is greater than 10V and less than or equal to 15V D:ΔVH exceeds 15V

[0270] -Sensitivity evaluation- The sensitivity of the photoreceptor was evaluated as follows. The photoreceptor was incorporated into a photoreceptor electrical characteristics evaluation system manufactured by Fujifilm Business Innovation Co., Ltd., which is equipped with a photoreceptor charging device, an exposure device, and a static elimination device. After performing a series of steps of charging, exposure, and static elimination under the following conditions for one cycle, charging and exposure were performed again, and the surface potential of the photoreceptor surface was measured, with the value defined as VL. The electrostatic potential of the photoreceptor surface was measured at a distance of 1 mm from the surface using a surface potential meter (Trek 334, manufactured by Trek). (conditions) ·Measurement environment: temperature 20℃ / humidity 40%RH • Charging potential: -400V ·Exposure light amount: 4mJ / m 2 • Exposure wavelength: 780nm • Static elimination light source: Halogen lamp (manufactured by Hayashi Clock Industry Co., Ltd.) · Static elimination light wavelength: 600nm or more and 800nm ​​or less ·Electrostatic light intensity: 30mJ / m 2 • Rotation speed of the photoconductor: 66.7 rpm A: VL is 15V or less B:VL is between 15V and 35V. C:VL exceeds 35V

[0271] -Image retention (ghost suppression) evaluation- The image retention performance of the photoreceptor was evaluated as follows. The photoreceptor fabricated above was incorporated into a modified DocuPrint P450d manufactured by Fujifilm Business Innovation Co., Ltd., and evaluated under conditions of 28°C and 85% RH. Furthermore, the modified DocuPrint P450d had its photoreceptor charged with an applied voltage of -400V. For ghosting evaluation, 1,000 charts containing the letter "G" and "solid black areas" were printed, and the degree to which the "G" letter (ghosting) appeared in the solid black areas was visually observed and evaluated according to the following criteria. A: The letter "G" cannot be seen in the solid black area. B: The letter "G" can be faintly seen in the solid black area. C: The letter "G" can be faintly seen in the solid black area. D: The letter "G" is clearly visible in the solid black area.

[0272] [Table 1]

[0273] The following details the abbreviations listed in Table 1, other than those mentioned above. ETM1: The following compounds ETM6: The following compounds ETM7: The following compounds ETM8: The following compounds 4-1: Exemplary compound 1 in formula (P4) described above CGM1: Hydroxygallium phthalocyanine having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 16.3°, 25.0°, and 28.3° in its X-ray diffraction spectrum using CuKα characteristic X-rays. CGM2: Titanylphthalocyanine CGM3: Metallic phthalocyanine CGM4: Copper Phthalocyanine

[0274] [ka]

[0275] As shown in Table 1, the electrophotographic photoreceptor of the example was found to be superior to the electrophotographic photoreceptor of the comparative example in terms of chargeability and ghost suppression. [Explanation of Symbols]

[0276] 1: Undercoat layer, 2: Charge generation layer, 3: Charge transport layer, 4: Conductive support, 5: Photosensitive layer, 7A: Electrophotographic photoreceptor, 7: Electrophotographic photoreceptor, 8: Charging device, 9: Exposure device, 11: Developing device, 13: Cleaning device, 14: Lubricant, 40: Transfer device, 50: Intermediate transfer body, 100: Image forming device, 120: Image forming device, 131: Cleaning blade, 132: Fibrous member (roll type), 133: Fibrous member (flat brush type), 300: Process cartridge

Claims

1. It comprises a conductive support, a base layer provided on the conductive support, and a charge generating layer provided on the base layer. The charge generation layer contains a phthalocyanine compound, The aforementioned lower layer contains, as an electron transport compound, a compound represented by the following formula (P1): The difference between the energy level of the lowest unoccupied orbital of the phthalocyanine compound and the energy level of the lowest unoccupied orbital of the compound represented by formula (P1) is 0.1 eV or less. Electrophotographic photoreceptor. 【Chemistry 1】 In formula (P1), R １１ R １２ R １３ R １４ R １５ R １６ R １７ and R １８ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group or a halogen atom, and R １１ and R １２ R １２ and R １３ and R １３ and R １４ each independently may be linked to each other to form a ring, and R １５ and R １６ R １６ and R １７ and R １７ and R １８ each independently may be linked to each other to form a ring.

2. The electrophotographic photoreceptor according to claim 1, wherein the content of the electron-transporting compound is 30% by mass or more and 80% by mass or less with respect to the total mass of the underlayer.

3. The electrophotographic photoreceptor according to claim 2, wherein the content of the electron-transporting compound is 50% by mass or more and 80% by mass or less with respect to the total mass of the underlayer.

4. The electrophotographic photoreceptor is provided according to any one of claims 1 to 3, A process cartridge that is attached to and detached from an image forming apparatus.

5. An electrophotographic photoreceptor according to any one of claims 1 to 3, A charging means for charging the surface of the electrophotographic photoreceptor, An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, A developing means that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, A transfer means for transferring the toner image onto the surface of a recording medium, An image forming apparatus equipped with the following features.

Images