CN109696806B - Electrophotographic photoreceptor - Google Patents

Abstract

The inventionAn electrophotographic photoreceptor is provided. An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generator, a hole transport agent, and a binder resin. The hole-transporting agent is a terphenyl derivative represented by the general formula (HTM). In the general formula (HTM), R¹And R⁵One of them represents a methyl group or an ethyl group, and the other represents a hydrogen atom, a methyl group or an ethyl group. R²、R⁴、R⁶、R⁸And R⁹Each independently represents a hydrogen atom or a methyl group. R is³And R⁷Each independently represents a hydrogen atom, a methyl group or a methoxy group. [ CHEM 1 ]

Description

Electrophotographic photoreceptor

Technical Field

The present invention relates to an electrophotographic photoreceptor.

Background

Electrophotographic photoreceptors are used in electrophotographic image forming apparatuses. The electrophotographic photoreceptor is, for example, a laminated electrophotographic photoreceptor or a single-layer electrophotographic photoreceptor. The electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer of the laminated electrophotographic photoreceptor comprises: a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The single-layer electrophotographic photoreceptor includes a single-layer photosensitive layer having charge generation and charge transport functions as a photosensitive layer.

For example, an electrophotographic photoreceptor includes a photosensitive layer containing a compound represented by the following chemical formula (HTM-a), for example.

[ CHEM 1 ]

Disclosure of Invention

However, the sensitivity characteristics of the electrophotographic photoreceptor are insufficient, and crystallization of the surface of the photoreceptor cannot be sufficiently suppressed.

In view of the above-described problems, an object of the present invention is to provide an electrophotographic photoreceptor having excellent sensitivity characteristics and drum appearance.

The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer includes: a charge generating agent, a hole transporting agent and a binder resin. The hole-transporting agent is a terphenyl derivative represented by the general formula (HTM).

[ CHEM 2 ]

In the general formula (HTM), R¹And R⁵In (A), one represents a methyl group or an ethyl group, and the other represents a hydrogen atom, a methyl group or an ethyl group. R²、R⁴、R⁶、R⁸And R⁹Each independently represents a hydrogen atom or a methyl group. R³And R⁷Each independently represents a hydrogen atom, a methyl group or a methoxy group.

The electrophotographic photoreceptor of the present invention is excellent in sensitivity characteristics and drum appearance.

Drawings

Fig. 1(a), 1(b) and 1(c) are schematic cross-sectional views of an example of an electrophotographic photoreceptor according to the embodiment of the present invention.

Fig. 2(a), 2(b), and 2(c) are schematic cross-sectional views of other examples of the electrophotographic photoreceptor according to the embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object of the present invention. Note that, although the description may be omitted as appropriate, the gist of the present invention is not limited thereto.

Hereinafter, the compound and its derivatives may be collectively referred to by adding "class" to the compound name. When a "class" is added after the compound name to indicate the polymer name, the repeating unit indicating the polymer is derived from the compound or a derivative thereof. When a "class" is added after the compound name to indicate the polymer name, the repeating unit indicating the polymer is derived from the compound or a derivative thereof. The "group which may have a substituent", the "group which may have a halogen atom" and the "group which may have a halogen atom" each represent a group which may be "substituted with a certain group", a group which may be "substituted with a halogen atom", and a "group which may be" substituted with a halogen atom ".

Hereinafter, unless otherwise specified, C1-C10 alkyl group, C1-C6 alkyl group, C1-C4 alkyl group, C1-C3 alkyl group, C1-C6 alkoxy group, C6-C14 aryl group and C5-C12 cycloalkylene (cycloakylidine) each have the following meanings.

The C1-C10 alkyl group is linear or branched and unsubstituted. C1-C10 alkyl such as: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, nonyl or decyl.

The C1-C6 alkyl group is linear or branched and unsubstituted. C1-C6 alkyl such as: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl or hexyl.

The C1-C4 alkyl group is linear or branched and unsubstituted. C1-C4 alkyl such as: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl.

The C1-C3 alkyl group is linear or branched and unsubstituted. C1-C3 alkyl such as: methyl, ethyl, n-propyl or isopropyl.

The C1-C6 alkoxy group is linear or branched and unsubstituted. C1-C6 alkoxy for example: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, s-butoxy, t-butoxy, n-pentyloxy, t-pentyloxy or n-hexyloxy.

C6-C14 aryl, for example: C6-C14 unsubstituted aromatic monocyclic hydrocarbon group, C6-C14 unsubstituted aromatic condensed bicyclic hydrocarbon group or C6-C14 unsubstituted aromatic condensed tricyclic hydrocarbon group. C6-C14 aryl, for example: phenyl, naphthyl, anthryl or phenanthryl.

C5-C12 cycloalkylene is unsubstituted. C5-C12 cycloalkylene for example: cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, cyclononyl, cyclodecylene, cycloundecylene or cyclododecylene. The C5-C12 cycloalkylene group is a divalent group represented by the following general formula (W). In the general formula (W), m represents an integer of 1 to 8. m preferably represents 2 or 8.

[ CHEM 3 ]

< this embodiment: electrophotographic photoreceptor

An electrophotographic photoreceptor (hereinafter, referred to as a photoreceptor) according to an embodiment of the present invention includes a conductive substrate and a photosensitive layer. The photoreceptor is, for example: a single-layer electrophotographic photoreceptor (hereinafter, sometimes referred to as a single-layer photoreceptor) or a laminated electrophotographic photoreceptor (hereinafter, sometimes referred to as a laminated photoreceptor).

[1. Single layer type photoreceptor ]

Hereinafter, the structure of the single-layer type photoreceptor will be described with reference to fig. 1. Fig. 1 is a schematic cross-sectional view of an example of the photoreceptor 1 according to the present embodiment.

In fig. 1, the photoreceptor 1 is a single-layer type photoreceptor. As shown in fig. 1(a), the single-layer photoreceptor includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 of the single layer type photoreceptor is a single layer type photosensitive layer 3 a. The monolayer type photosensitive layer 3a is a photosensitive layer 3 of one layer. As shown in fig. 1(a), the photosensitive layer 3 may be disposed directly on the conductive substrate 2.

As shown in fig. 1(b), the single-layer type photoreceptor may include: a conductive substrate 2, a monolayer type photosensitive layer 3a, and an intermediate layer (undercoat layer) 4. The intermediate layer 4 is provided between the conductive substrate 2 and the monolayer photosensitive layer 3 a. As shown in fig. 1(b), the photosensitive layer 3 may be indirectly disposed on the conductive substrate 2 via the intermediate layer 4. Further, as shown in fig. 1(c), a protective layer 5 may be provided on the monolayer type photosensitive layer 3 a.

The thickness of the monolayer photosensitive layer 3a is not particularly limited as long as it sufficiently functions as a monolayer photosensitive layer. The thickness of the monolayer type photosensitive layer 3a is preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm.

[2 ] laminated photoreceptor

In the laminated photoreceptor, the photosensitive layer includes a charge generation layer and a charge transport layer. Hereinafter, the structure of the laminated photoreceptor will be described with reference to fig. 2. Fig. 2 is a schematic cross-sectional view of another example of the photoreceptor 1 according to the present embodiment.

In fig. 2, the photoreceptor 1 is a laminated photoreceptor. As shown in fig. 2(a), the laminated photoreceptor includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 includes a charge generation layer 3b and a charge transport layer 3 c. In order to improve the abrasion resistance of the laminated photoreceptor, as shown in fig. 2(a), it is preferable to provide a charge generation layer 3b on the conductive substrate 2 and a charge transport layer 3c on the charge generation layer 3 b. As shown in fig. 2(b), in the laminated photoreceptor, a charge transport layer 3c may be provided on the conductive substrate 2, and a charge generation layer 3b may be provided on the charge transport layer 3 c.

As shown in fig. 2(c), the laminated photoreceptor may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer (undercoat layer) 4. The intermediate layer 4 is located between the conductive substrate 2 and the photosensitive layer 3. Further, a protective layer 5 may be provided on the photosensitive layer 3 (see fig. 1 (c)).

The thickness of the charge generation layer 3b and the charge transport layer 3c is not particularly limited as long as they sufficiently function as the respective layers. The thickness of the charge generation layer 3b is preferably 0.01 μm to 5 μm, and more preferably 0.1 μm to 3 μm. The thickness of the charge transport layer 3c is preferably 2 μm to 100 μm, and more preferably 5 μm to 50 μm.

The photoreceptor 1 according to the present embodiment includes a photosensitive layer 3. The photosensitive layer includes: a charge generating agent, a terphenyl derivative represented by a general formula (HTM) (hereinafter, may be referred to as a terphenyl derivative (HTM)) as a hole transporting agent, and a binder resin. The terphenyl derivative represented by the general formula (HTM) is also referred to as a compound represented by the general formula (HTM). In the single layer type photoreceptor, the single layer type photosensitive layer 3a includes, for example: a charge generating agent, a terphenyl derivative (HTM), and a binder resin. In the laminated photoreceptor, the charge generation layer 3b contains, for example, a charge generating agent and a binder resin for the charge generating agent (hereinafter, may be referred to as a matrix resin). The charge transport layer 3c contains, for example, a terphenyl derivative (HTM) and a binder resin. The monolayer type photosensitive layer 3a, the charge generation layer 3b and the charge transport layer 3c may further contain an additive.

The photoreceptor 1 according to the present embodiment is excellent in sensitivity characteristics and drum appearance. The reason is presumed as follows.

The photoreceptor 1 according to the present embodiment includes a terphenyl derivative (HTM). In the case of terphenyl derivatives (HTM), in the general formula (HTM), R¹And R⁵One of them represents a methyl group or an ethyl group, and the other represents a hydrogen atom, a methyl group or an ethyl group. That is, in the terphenyl derivative (HTM), one phenyl group of the terminal 2 phenyl groups has no substituent at 2 ortho-positions with respect to the nitrogen atom, and the other phenyl group has a methyl group or an ethyl group at least one of the 2 ortho-positions with respect to the nitrogen atom. The terphenyl derivative (HTM) has such a structure, and therefore has excellent solubility in a solvent, is easy to prepare a coating liquid for a photosensitive layer, has excellent compatibility with a binder resin, and has excellent dispersibility in the photosensitive layer 3. Therefore, the terphenyl derivative (HTM) is not easily crystallized in the photosensitive layer 3. The photoreceptor 1 according to the present embodiment is considered to have excellent drum appearance.

Further, since the terphenyl derivative (HTM) has a large steric extension of the pi-conjugated system, the intramolecular movement distance in the terphenyl derivative (HTM) of the carrier (hole) generated in the image forming process tends to be large. In addition, in the photosensitive layer 3, since the overlap of the pi-conjugated system between the terphenyl derivatives (HTM) is increased, the intermolecular transfer distance of the holes tends to be small. Further, as described above, the terphenyl derivative (HTM) is excellent in dispersibility in the photosensitive layer 3. As described above, the photoreceptor 1 according to the present embodiment is considered to have excellent sensitivity characteristics.

Hereinafter, preferred combinations of the elements of the photoreceptor, that is, the conductive substrate, the electron transporting agent, the electron acceptor compound, the hole transporting agent, the charge generating agent, the binder resin, the matrix resin, the additive, the material, and the intermediate layer will be described. Further, a method for manufacturing the photoreceptor will be described.

[3. conductive substrate ]

At least the surface portion of the conductive substrate 2 may be formed of a conductive material (hereinafter, may be referred to as a conductive material). The conductive substrate 2 is, for example, a conductive substrate formed of a conductive material. The conductive substrate 2 is, for example, a conductive substrate coated with a conductive material. Conductive materials such as: aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, or indium. These conductive materials may be used alone, or two or more of them may be used in combination. A combination of two or more such as an alloy (more specifically, an aluminum alloy, stainless steel, brass, or the like). Among these conductive materials, aluminum or an aluminum alloy is preferable in terms of the favorable property of transferring charges from the photosensitive layer 3 to the conductive substrate 2. The surface of the conductive substrate 2 may have an oxide film of these conductive materials.

The shape of the conductive substrate 2 can be appropriately selected according to the structure of the image forming apparatus. The conductive substrate 2 has a sheet-like or drum-like shape, for example. The thickness of the conductive substrate 2 can be appropriately selected according to the shape of the conductive substrate.

[4. Electron transport agent, Electron acceptor Compound ]

In the single-layer photoreceptor, the single-layer photosensitive layer 3a may contain an electron-transporting agent. In the laminated photoreceptor, the charge transport layer 3c may contain an electron acceptor compound.

Electron transport agents and electron acceptor compounds such as: quinone compounds, imide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3, 4, 5, 7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2, 4, 8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride or dibromomaleic anhydride. Quinone compounds are exemplified by: a diphenoquinone compound, an azoquinone compound, an anthraquinone compound, a naphthoquinone compound, a nitroanthraquinone compound or a dinitroanthraquinone compound. These electron transport agents and electron acceptor compounds may be used alone or in combination of two or more.

Among these electron transport agents and electron acceptor compounds, compounds represented by the general formula (E) (hereinafter, sometimes referred to as compounds (E)) are preferably contained.

[ CHEM 4 ]

In the general formula (E), R³³、R³⁴、R³⁵And R³⁶Independently of one another, represents a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a C6-C14 aryl group.

In the general formula (E), R³³、R³⁴、R³⁵And R³⁶Preferably represents a C1-C6 alkyl group, more preferably represents a C1-C4 alkyl group, and still more preferably represents a methyl group or a tert-butyl group. The compound represented by the general formula (E) is, for example, a compound represented by the chemical formula (E-1) (hereinafter, sometimes referred to as the compound (E-1)).

[ CHEM 5 ]

The content of the electron acceptor compound is preferably 1 part by mass or more and 100 parts by mass or less, more preferably 1 part by mass or more and 50 parts by mass or less, and particularly preferably 1 part by mass or more and 30 parts by mass or less, with respect to 100 parts by mass of the binder resin of the charge transport layer 3 c.

[5. hole-transporting agent ]

The photosensitive layer 3 contains a terphenyl derivative (HTM) as a hole transporting agent. The terphenyl derivative (HTM) is represented by the general formula (HTM).

[ CHEM 6 ]

In the general formula (HTM), R¹And R⁵One of them represents a methyl group or an ethyl group, and the other represents a hydrogen atom, a methyl group or an ethyl group. R is²、R⁴、R⁶、R⁸And R⁹Each independently represents a hydrogen atom or a methyl group. R is³And R⁷Each independently represents a hydrogen atom, a methyl group or a methoxy group.

In the general formula (HTM), R²、R⁴、R⁶、R⁸And R⁹Preferably represents a hydrogen atom.

Terphenyl derivatives (HTM) are preferably exemplified by: compounds represented by chemical formula (HTM-1), (HTM-2), (HTM-3), (HTM-4) or (HTM-5) (hereinafter, may be referred to as terphenyl derivatives (HTM-1) to (HTM-5), respectively). The terphenyl derivative (HTM-4) is preferable from the viewpoint of further improving the sensitivity characteristics of the photoreceptor 1 among the terphenyl derivatives (HTM-1) to (HTM-5).

[ CHEM 7 ]

When the photoreceptor 1 is a single-layer photoreceptor, the content of the hole transporting agent is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 10 parts by mass or more and 100 parts by mass or less, and particularly preferably 10 parts by mass or more and 75 parts by mass or less, with respect to 100 parts by mass of the binder resin contained in the single-layer photosensitive layer 3 a.

When the photoreceptor 1 is a multilayer photoreceptor, the content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 20 parts by mass or more and 100 parts by mass or less, with respect to 100 parts by mass of the binder resin contained in the charge transport layer 3 c.

[6. Charge-generating agent ]

When the photoreceptor 1 is a single-layer photoreceptor, the single-layer photosensitive layer 3a contains a charge generator. When the photoreceptor 1 is a laminated photoreceptor, the charge generation layer 3b contains a charge generating agent.

Charge generators such as: phthalocyanine pigments, perylene pigments, disazo pigments, trisazo pigments, dithione pyrrolopyrrole (dithioketo-pyrolole) pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squarylium pigments, indigo pigments, azulene pigments, cyanine pigments, powders of inorganic photoconductive materials (more specifically, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, or the like), pyran pigments, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, or quinacridone pigments. One kind of charge generating agent may be used alone, or two or more kinds may be used in combination.

Phthalocyanine pigments such as: a metal phthalocyanine pigment or a metal-free phthalocyanine pigment. Metal phthalocyanine pigments such as: hydroxygallium phthalocyanine pigment, chlorogallium phthalocyanine pigment or oxytitanium phthalocyanine pigment represented by the formula (CGM-A). The metal-free phthalocyanine pigment is represented by the chemical formula (CGM-B). The crystal shape (for example, X-type, α -type, β -type, Y-type, V-type, or II-type) of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes can be used.

[ CHEM 8 ]

Crystals of metal-free phthalocyanine pigments such as: an X-type crystal of metal-free phthalocyanine (hereinafter, sometimes referred to as X-type metal-free phthalocyanine). Crystals of oxytitanium phthalocyanine pigments such as: an α -type, β -type or Y-type crystal of a oxytitanium phthalocyanine pigment (hereinafter, sometimes referred to as an α -type oxytitanium phthalocyanine pigment, a β -type oxytitanium phthalocyanine pigment and a Y-type oxytitanium phthalocyanine pigment, respectively). Crystals of hydroxygallium phthalocyanine pigments such as the V-type crystals of hydroxygallium phthalocyanine pigments. Crystals of chlorogallium phthalocyanine such as type II crystals of chlorogallium phthalocyanine pigments.

For example, in a digital optical image forming apparatus, a photoreceptor having sensitivity in a wavelength region of 700nm or more is preferably used. Examples of the digital optical image forming apparatus include a laser printer or a facsimile machine using a light source such as a semiconductor laser. The charge generating agent is preferably a phthalocyanine-based pigment, more preferably a oxytitanium phthalocyanine pigment, from the viewpoint of having a high quantum yield in a wavelength region of 700nm or more. In order to further improve the sensitivity characteristics and drum appearance of the photoreceptor 1 when the photosensitive layer contains a terphenyl derivative (HTM), the charge generating agent is more preferably a Y-type oxytitanium phthalocyanine pigment.

The Y-type oxytitanium phthalocyanine crystal has a main peak at 27.2 ° of the bragg angle (2 θ ± 0.2 °) in the CuK α characteristic X-ray diffraction spectrum, for example. The main peak in the CuK α characteristic X-ray diffraction spectrum means a peak having a first or second large intensity in a range where the bragg angle (2 θ ± 0.2 °) is 3 ° or more and 40 ° or less.

(method for measuring CuK alpha characteristic X-ray diffraction Spectrum)

An example of a method for measuring CuK α characteristic X-ray diffraction spectrum will be described. A sample (Y-type oxytitanium phthalocyanine pigment) was charged into a sample holder of an X-ray diffraction apparatus (for example, "RINT (registered trademark) 1100" manufactured by Rigaku Corporation) under an X-ray tube Cu, a tube voltage of 40kV, a tube current of 30mA, and a wavelength of CuKa characteristic X-rays of CuK alpha

Under the conditions of (1), an X-ray diffraction spectrum was measured. For example, the measurement range (2 θ) is 3 ° to 40 ° (start angle: 3 °; stop angle: 40 °), and the scanning speed is 10 °/min.

When the photoreceptor 1 is a single-layer photoreceptor, the content of the charge generating agent is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 30 parts by mass, and particularly preferably 0.5 to 4.5 parts by mass, based on 100 parts by mass of the binder resin contained in the single-layer photosensitive layer 3 a.

When the photoreceptor 1 is a laminated photoreceptor, the content of the charge generating agent is preferably 5 parts by mass or more and 1000 parts by mass or less, and more preferably 30 parts by mass or more and 500 parts by mass or less, with respect to 100 parts by mass of the matrix resin contained in the charge generating layer 3 b.

[7. Binder resin ]

Examples of binding resins are: a thermoplastic resin, a thermosetting resin, or a photocurable resin. Thermoplastic resins such as: a polycarbonate resin, a polyarylate resin, a styrene-butadiene resin, a styrene-acrylonitrile resin, a styrene-maleic acid resin, an acrylic resin, a styrene-acrylic resin, a polyethylene resin, an ethylene-vinyl acetate resin, a chlorinated polyethylene resin, a polyvinyl chloride resin, a polypropylene resin, an ionomer resin, a vinyl chloride-vinyl acetate resin, an alkyd resin, a polyamide resin, a polyurethane resin, a polysulfone resin, a diallyl phthalate resin, a ketone resin, a polyvinyl butyral resin, a polyester resin, or a polyether resin. Thermosetting resins such as: silicone resins, epoxy resins, phenolic resins, urea-formaldehyde resins or melamine resins. The photocurable resin is, for example: an epoxy-acrylic resin (more specifically, an acrylic acid derivative adduct of an epoxy compound, etc.) or a urethane-acrylic resin (an acrylic acid derivative adduct of a urethane compound). These binder resins may be used alone or in combination of two or more.

Among these binder resins, a polycarbonate resin or a polyarylate resin is preferable, and a polycarbonate resin having a repeating unit represented by the chemical formula (PC-1) or (PC-2) (hereinafter, sometimes referred to as polycarbonate resins (PC-1) and (PC-2), respectively) or a polyarylate resin represented by the general formula (PAR) (hereinafter, sometimes referred to as polyarylate resin (PAR)) is more preferable, from the viewpoint of further improving the sensitivity characteristics and the drum appearance of the photoreceptor 1.

[ CHEM 9 ]

In the general formula (PAR), R¹¹And R¹⁴Represents a hydrogen atom or a methyl group. R¹²、R¹³、R¹⁵And R¹⁶Each independently represents a hydrogen atom or a C1-C10 alkyl group. R¹²And R¹³May be combined with each other to represent C5-C12 cycloalkylene. R¹⁵And R¹⁶May be combined with each other to represent C5-C12 cycloalkylene. X is a divalent group represented by the formula (1-1) or (1-2). r, s, t and u are each independently a number greater than 0. r + s + t + u is 100, and r + s is t + u.

[ CHEM 10 ]

In the general formula (PAR), R¹²、R¹³、R¹⁵And R¹⁶The C1-C10 alkyl group preferably represents a C1-C6 alkyl group, more preferably a C1-C4 alkyl group, still more preferably a C1-C3 alkyl group, and particularly preferably represents a methyl group or an ethyl group.

In the general formula (PAR), R¹²And R¹³C5-C12 cycloalkylene and R in combination with each other¹⁵And R¹⁶The C5-C12 cycloalkylene radicals which are formed in combination with one another are preferably cyclohexylene or cyclododecylene. Cyclohexylene (cyclohexylidene) is a group in which m in the above general formula (W) is 2. Cyclododecylene (cyclododecene) is a group in which m in the above general formula (W) is 8.

Polyarylate resin (PAR) comprises: the repeating units represented by the general formulae (PAR-r), (PAR-s), (PAR-t) and (PAR-u) (hereinafter, may be referred to as the repeating units (PAR-r), (PAR-s), (PAR-t) and (PAR-u), respectively). R in the general formula (PAR-R)¹¹、R¹²And R¹³X in the general formula (PAR-s) and R in the general formula (PAR-t)¹⁴、R¹⁵And R¹⁶Are each independently of R in the general formula (PAR)¹¹、R¹²、R¹³、X、R¹⁴、R¹⁵And R¹⁶Have the same meaning.

[ CHEM 11 ]

r represents the percentage of the number of repeating units (PAR-r) to the total number of repeating units (PAR-r), (PAR-s), (PAR-t) and (PAR-u) contained in the polyarylate resin (PAR). s represents the percentage of the number of repeating units (PAR-s) relative to the total number of repeating units (PAR-r), (PAR-s), (PAR-t) and (PAR-u) contained in the polyarylate resin (PAR). t represents the percentage of the number of repeating units (PAR-t) to the total number of repeating units (PAR-r), (PAR-s), (PAR-t) and (PAR-u) contained in the polyarylate resin (PAR). u represents the percentage of the number of repeating units (PAR-u) relative to the total number of repeating units (PAR-r), (PAR-s), (PAR-t) and (PAR-u) contained in the polyarylate resin (PAR).

r, s, t and u are each independently a number of preferably more than 0 and less than 50, more preferably a number of 20 to 30, and still more preferably 25.

The polyarylate resin (PAR) may comprise only the repeating units (PAR-r), (PAR-s), (PAR-t) and (PAR-u) as the repeating units. The polyarylate resin (PAR) may further contain a repeating unit other than the repeating units (PAR-r), (PAR-s), (PAR-t) and (PAR-u) as the repeating unit.

Polyarylate resin (PAR) such as: polyarylate resins having a repeating unit represented by the formula (PAR-1), the formula (PAR-2), the formula (PAR-3) or the formula (PAR-4) (hereinafter, referred to as polyarylate resins (PAR-1) to (PAR-4), respectively, in some cases).

[ CHEM 12 ]

When the photoreceptor 1 contains a terphenyl derivative (HTM) as a hole transporting agent, the polyarylate resin (PAR-3) or (PAR-4) is preferable from the viewpoint of further improving the sensitivity characteristics of the photoreceptor 1, and the polycarbonate resins (PC-1) and (PC-2) are preferably polyarylate resins (PAR-1) and (PAR-4), or polycarbonate resin (PC-1).

The viscosity average molecular weight of the binder resin is preferably 25,000 or more, more preferably 30,000 or more and 70,000 or less, and further preferably 45,000 or more and 54,000 or less. When the viscosity average molecular weight of the binder resin is 30,000 or more, the abrasion resistance of the photoreceptor is easily improved. When the viscosity average molecular weight of the binder resin is 70,000 or less, the binder resin is easily dissolved in a solvent when forming the photosensitive layer, and the viscosity of the coating liquid for the charge transport layer or the coating liquid for the single-layer photosensitive layer does not become too high. Thereby easily forming a charge transport layer or a monolayer type photosensitive layer.

[8. base resin ]

When the photoreceptor is a laminated photoreceptor, the charge generation layer contains a matrix resin. The base resin is not particularly limited as long as it is a base resin that can be applied to a photoreceptor. Matrix resins such as: thermoplastic resins, thermosetting resins or photocurable resins. Thermoplastic resins such as: styrene-butadiene resin, styrene-acrylonitrile resin, maleic acid resin, styrene-acrylic acid resin, acrylic resin, polyethylene resin, ethylene-vinyl acetate resin, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate resin, alkyd resin, polyamide resin, polyurethane resin, polycarbonate resin, polyarylate resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl acetal resin, polyether resin, or polyester resin. Thermosetting resins such as: silicone resins, epoxy resins, phenolic resins, urea-formaldehyde resins, melamine resins or other cross-linking thermosetting resins. The photocurable resin is, for example: an epoxy-acrylic resin (more specifically, an acrylic acid derivative adduct of an epoxy compound, etc.) or a urethane-acrylic resin (more specifically, an acrylic acid derivative adduct of a urethane compound, etc.). The base resin may be used alone or in combination of two or more.

The matrix resin contained in the charge generating layer is preferably different from the binder resin contained in the charge transporting layer. This is because the charge generation layer is not dissolved in the solvent of the coating liquid for charge transport layer. The reason is that: in the production of a laminated photoreceptor, a charge generation layer is generally formed on a conductive substrate, a charge transport layer is formed on the charge generation layer, and a charge transport layer coating solution is applied to the charge generation layer when the charge transport layer is formed.

[9. additive ]

The photosensitive layer 3 (the charge generation layer 3b, the charge transport layer 3c, or the single-layer photosensitive layer 3a) of the photoreceptor may contain various additives as needed. Additives such as: a deterioration inhibitor (more specifically, an antioxidant, a radical scavenger, a quencher or an ultraviolet absorber, etc.), a softening agent, a surface modifier, an extender, a thickener, a dispersion stabilizer, a wax, a donor, a surfactant, a plasticizer, a sensitizer or a leveling agent. The antioxidant is preferably a hindered phenol antioxidant. The leveling agent is preferably dimethyl silicone oil.

[10. combination of materials ]

When the photoreceptor is a laminated photoreceptor, the hole-transporting agent and the binder resin contained in the charge-transporting layer are preferably in any combination shown in table 1. More preferably, the hole-transporting agent and the binder resin contained in the charge-transporting layer are in any combination shown in table 1, and the electron acceptor compound is compound (E-1). More preferably, the hole transport agent and the binder resin contained in the charge transport layer are in any combination shown in table 1, the electron acceptor compound is compound (E-1), and the additive is a hindered phenol antioxidant and a dimethylsilicone oil. More preferably, the hole transporting agent and the binder resin contained in the charge transporting layer are in any combination of the above, and the charge generating agent contained in the charge generating layer is a Y-type oxytitanium phthalocyanine pigment. More preferably, the hole transporting agent, the binder resin and the electron acceptor compound contained in the charge transporting layer are in any combination of the above, and the charge generating agent contained in the charge generating layer is a Y-type oxytitanium phthalocyanine pigment. More preferably, the hole transporting agent, the binder resin, the electron acceptor compound and the additive contained in the charge transport layer are in any combination of the above, and the charge generating agent contained in the charge generating layer is a Y-type oxytitanium phthalocyanine pigment.

[ TABLE 1 ]

In table 1, HTM and Resin represent a hole transport agent and a binder Resin, respectively. In Table 1, HTM-1 to HTM-5 in the HTM column represent terphenyl derivatives (HTM-1) to (HTM-5), respectively. In Table 1, PAR-1 to PAR-6 and PC-1 to PC-5 in the column for binder resins represent polyarylate resins (PAR-1) to PAR-6) and polycarbonate resins (PC-1) to PC-5, respectively. In the following, the polyarylate resins (PAR-5) to (PAR-6) and the polycarbonate resins (PC-3) to (PC-5) will be described in examples.

[11. intermediate layer ]

The intermediate layer (undercoat layer) 4 contains, for example, inorganic particles and a resin (intermediate layer resin). It is considered that the presence of the intermediate layer 4 allows smooth flow of current generated when the photoreceptor 1 is exposed while maintaining an insulating state to such an extent that generation of current leakage can be suppressed, and thus can suppress an increase in resistance.

Inorganic particles such as: particles of a metal (more specifically, aluminum, iron, copper, or the like), particles of a metal oxide (more specifically, titanium oxide, aluminum oxide, zirconium oxide, tin oxide, zinc oxide, or the like), or particles of a non-metal oxide (more specifically, silicon dioxide, or the like). These inorganic particles may be used singly or in combination of two or more.

The resin for the intermediate layer is not particularly limited as long as it can be used as a resin for forming the intermediate layer 4. The intermediate layer 4 may also contain various additives. Examples of the additive contained in the intermediate layer 4 are the same as those of the additive contained in the photosensitive layer 3.

[12. method for producing photoreceptor ]

When the photoreceptor 1 is a single-layer photoreceptor, for example, a single-layer photoreceptor is produced by applying a coating liquid for a single-layer photosensitive layer onto the conductive substrate 2 to form a coating liquid, and drying the coating liquid. For example, a charge generating agent, a terphenyl derivative (HTM) as a hole transporting agent, an electron transporting agent, a binder resin, and an additive added as needed are dissolved or dispersed in a solvent to prepare a coating liquid for a monolayer type photosensitive layer.

When the photoreceptor 1 is a laminated photoreceptor, the laminated photoreceptor is manufactured, for example, as follows. First, a coating liquid for a charge generating layer and a coating liquid for a charge transporting layer are prepared. The coating liquid for the charge generation layer is applied to the conductive substrate 2 to form a coating film. The charge generation layer 3b is formed by drying the coating film. Next, the charge transport layer coating solution is applied to the charge generation layer 3b to form a coating film. The charge transport layer 3c is formed by drying the coating film. Thus, a laminated photoreceptor was produced.

The coating liquid for a charge generating layer is prepared by, for example, dissolving or dispersing a charge generating agent, a matrix resin, and an additive added as needed in a solvent. The coating liquid for a charge transport layer is prepared by dissolving or dispersing a terphenyl derivative (HTM) as a hole transport agent, an electron acceptor compound, a binder resin, and an additive added as needed in a solvent.

The solvent contained in the coating liquid for the monolayer type photosensitive layer, the coating liquid for the charge generating layer, and the coating liquid for the charge transporting layer (hereinafter, these three coating liquids may be referred to as coating liquids) is not particularly limited as long as it can dissolve or disperse each component contained in the coating liquid and can be removed from the coating film. Solvents such as: alcohols (more specifically, methanol, ethanol, isopropanol, butanol, or the like), aliphatic hydrocarbons (more specifically, n-hexane, octane, cyclohexane, or the like), aromatic hydrocarbons (more specifically, benzene, toluene, xylene, or the like), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, or the like), ethers (more specifically, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, or the like), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, or the like), esters (more specifically, ethyl acetate, methyl acetate, or the like), dimethyl formaldehyde, dimethyl formamide, or dimethyl sulfoxide. These solvents may be used alone or in combination of two or more. In order to improve the workability in manufacturing the photoreceptor 1, a non-halogenated solvent (a solvent other than halogenated hydrocarbon) is preferably used as the solvent.

The components are mixed and dispersed in a solvent to prepare a coating liquid. For the mixing or dispersing, for example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used.

The coating liquid may contain a surfactant, for example, in order to improve dispersibility of each component.

The method of coating with the coating liquid is not particularly limited as long as the coating liquid can be uniformly applied to the conductive substrate. Examples of the coating method include: dip coating, spray coating, spin coating or bar coating.

The method for drying the coating film is not particularly limited as long as it is a method capable of evaporating the solvent in the coating liquid. For example, there is a method of performing heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer. The heat treatment conditions are, for example, a temperature of 40 ℃ to 150 ℃ and a time of 3 minutes to 120 minutes.

The method for manufacturing the photoreceptor 1 may further include a step of forming an intermediate layer, a step of forming a protective layer, or both steps, as necessary. The step of forming the intermediate layer and the step of forming the protective layer can be realized by appropriately selecting a known method.

[ examples ] A method for producing a compound

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the scope of the examples.

<1. materials for photoreceptors >

As a material for forming the photosensitive layer of the laminated photoreceptor, an electron acceptor compound, a hole transporting agent, a charge generating agent, and a binder resin, which are described below, are prepared.

[1-1. Electron acceptor Compound ]

The compound (E-1) is prepared as the electron acceptor compound described in this embodiment.

[1-2. hole-transporting agent ]

Terphenyl derivatives (HTM-1) to (HTM-5) were prepared as the hole transporting agent described in the present embodiment. Further, hole-transporting agents (HTM-6) to (HTM-9) were prepared. The hole-transporting agents (HTM-6) to (HTM-9) are represented by the chemical formulas (HTM-6) to (HTM-9), respectively.

[ CHEM 13 ]

[1-3. Charge generators ]

The charge generating agent (CGM-A) described in the present embodiment was prepared. The charge generating agent (CGM-A) is a oxytitanium phthalocyanine pigment represented by the chemical formula (CGM-A), and the crystal structure is Y-type.

In a CuK α characteristic X-ray diffraction spectrum, the Y-type oxytitanium phthalocyanine crystal has peaks at bragg angles 2 θ ± 0.2 ° of 9.2 °, 14.5 °, 18.1 °, 24.1 ° and 27.2 °, and the main peak is 27.2 °. The CuK α characteristic X-ray diffraction spectrum is measured by the measurement device and the measurement conditions described in this embodiment.

[1-4. Binder resin ]

Polycarbonate resins (PC-1) to (PC-2) (viscosity average molecular weights of 50,000 and 51,000, respectively) and polyarylate resins (PAR-1) to (PAR-4) (viscosity average molecular weights of 48,700, 45,900, 51,200, and 53,200, respectively) described in the present embodiment were prepared as binder resins.

Polyarylate resins (PAR-5) to (PAR-6) and polycarbonate resins (PC-3) to (PC-5) were prepared as binder resins. The polyarylate resins (PAR-5) to (PAR-6) are represented by the chemical formulas (PAR-5) to (PAR-6), respectively. The polycarbonate resins (PC-3) to (PC-5) are represented by the chemical formulas (PC-3) to (PC-5), respectively.

[ CHEM 14 ]

<2 > production of photoreceptor

Photoreceptors (A-1) to (A-15) and photoreceptors (B-1) to (B-4) were produced using the material for forming the photosensitive layer.

[2-1 ] production of photoreceptor (A-1 ]

(formation of undercoat layer)

First, a surface-treated titanium dioxide (Tayca corporation, "test sample SMT-A", number average primary particle diameter 10nm) was prepared. Specifically, the surface-treated titanium dioxide is obtained by performing surface treatment with alumina and silica, and performing surface treatment with polymethylhydrosiloxane while wet-dispersing the surface-treated titanium dioxide. Subsequently, surface-treated titanium dioxide (2 parts by mass) and a copolymerized polyamide resin ("AMILAN (japanese registered trademark) CM 8000", manufactured by toyo corporation) (1 part by mass) were added to the mixed solvent. The copolymerized polyamide resin is a quaternary copolymerized polyamide resin of 6, 12, 66 and 610. The mixed solvent contained methanol (10 parts by mass), butanol (1 part by mass), and toluene (1 part by mass). These materials (surface-treated titanium dioxide and copolyamide resin) were mixed with the mixed solvent for 5 hours by a bead mill to disperse the materials in the mixed solvent. Thus, a coating liquid for an undercoat layer was produced.

The obtained coating liquid for undercoat layer was filtered through a filter having a pore size of 5 μm. Thereafter, a coating liquid for an undercoat layer was applied to the surface of an aluminum drum support (diameter 30mm, total length 246mm) as a conductive substrate by a dip coating method. Subsequently, the applied coating liquid for an undercoat layer was dried at 130 ℃ for 30 minutes to form an undercoat layer (film thickness: 2 μm) on the conductive substrate (drum support).

(formation of Charge generating layer)

Next, to the mixed solvent was added: a compound (CGM-A) (Y-type oxytitanium phthalocyanine pigment) (1.5 parts by mass) as a charge generating agent, and a polyvinyl acetal resin (S-LEC BX-5, waterlogging chemical Co., Ltd.) (1 part by mass) as a binder resin. The mixed solvent contained propylene glycol monomethyl ether (40 parts by mass) and tetrahydrofuran (40 parts by mass). These materials (Y-type oxytitanium phthalocyanine pigment and polyvinyl acetal resin) were mixed for 2 hours by a bead mill, and the materials were dispersed in a mixed solvent to prepare a coating liquid for a charge generating layer. The obtained coating liquid for a charge generation layer was filtered through a filter having a pore size of 3 μm. Next, the obtained filtrate was coated on the undercoat layer formed as described above using a dip coating method, and dried at 50 ℃ for 5 minutes. Thus, a charge generation layer (film thickness: 0.3 μm) was formed on the undercoat layer.

(formation of Charge transport layer)

Next, to the mixed solvent was added: terphenyl derivative (HTM-1) (60 parts by mass) as a hole transporting agent, antioxidant (hindered phenol antioxidant, "IRGANOX (japanese registered trademark) 1010" manufactured by BASF corporation) (0.5 parts by mass) and leveling agent (dimethicone K96-50CS "manufactured by shin-Etsu chemical Co., Ltd.) (0.05 parts by mass), compound (E-1) (2 parts by mass) as an electron acceptor compound, polyarylate resin (PAR-1) (100 parts by mass) as a binder resin. The mixed solvent contained tetrahydrofuran (350 parts by mass) and toluene (350 parts by mass). These materials and a mixed solvent are mixed, and the materials are dispersed in the mixed solvent to prepare a coating liquid for a charge transport layer. The prepared coating liquid for a charge transport layer was applied onto the charge generation layer by the same method as the coating liquid for a charge generation layer, and dried at 120 ℃ for 40 minutes to form a charge transport layer having a film thickness of 20 μm, thereby producing a photoreceptor (a-1). The conductive substrate of the photoreceptor (A-1) is laminated with an undercoat layer, a charge generation layer and a charge transport layer in this order. [2-2 ] production of photoreceptors (A-2) to (A-15) and photoreceptors (B-1) to (B-4) ]

The photoreceptors (A-2) to (A-15) and the photoreceptors (B-1) to (B-4) were manufactured by the same method as that for the photoreceptor (A-1) except for the following modifications. The terphenyl derivative (HTM-1) as the hole-transporting agent used for producing the photoreceptor (A-1) was changed to the type of the hole-transporting agent shown in Table 2. The polyarylate resin (PAR-1) as the binder resin used for the production of the photoreceptor (A-1) was changed to the binder resin of the kind shown in Table 2.

<3. evaluation of photoreceptor >

[3-1. evaluation of Electrical characteristics of photoreceptor ]

(3. evaluation of charging characteristics of photoreceptor)

The charging characteristics of the manufactured photoreceptors (A-1) to (A-15) and photoreceptors (B-1) to (B-4) were evaluated. The charging characteristics were evaluated in an environment at a temperature of 10 ℃ and a humidity of 20% RH. First, the surface of the photoreceptor was charged by a drum sensitivity tester (manufactured by GENTEC corporation) under conditions of a drum rotation speed of 31rpm and a drum current of-10. mu.A. The surface potential of the photoreceptor immediately after charging was measured. The measured surface potential is taken as the charged potential (V)₀Unit V). Measured charged potential (V) of the photoreceptor₀) As shown in table 2.

(3-1. evaluation of sensitivity characteristics of photoreceptor)

The manufactured photoreceptors (A-1) to (A-15) and photoreceptors (B-1) to (B-4) were evaluated for sensitivity characteristics. Photosensibility specialThe evaluation of the properties was carried out at a temperature of 10 ℃ and a humidity of 20% RH. First, the surface of the photoreceptor was charged to-600V by a drum sensitivity tester (manufactured by GENTEC corporation). Then, monochromatic light (wavelength 780nm, light intensity 0.26 μ J/m) was extracted from the white light of the halogen lamp by a band-pass filter²). The extracted monochromatic light is irradiated to the surface of the photoreceptor. The surface potential of the photoreceptor was measured after 50 milliseconds had elapsed from the start of irradiation. The measured surface potential is taken as the post-exposure potential (V)_LUnit V). Measured potential (V) after exposure of the photoreceptor_L) As shown in table 2. Further, post-exposure potential (V)_L) The smaller the absolute value of (a) is, the more excellent the electrical characteristics of the photoreceptor are.

[3-2. evaluation of appearance of photoreceptor ]

The appearances of the manufactured photoreceptors (A-1) to (A-15) and photoreceptors (B-1) to (B-4) were evaluated. The appearance of the photoreceptor surface (drum appearance) was evaluated at a temperature of 23 ℃ and a relative humidity of 50% RH. The photoreceptor surface was observed visually, and the determination was made based on the following criteria.

(evaluation criteria of Drum appearance)

Evaluation a (good): no white fog (white paste) was observed on the photoreceptor surface.

Evaluation B (normal): although a slight white haze was observed on the surface of the photoreceptor, it did not affect practical use.

Evaluation C (poor): white fog was observed on the surface of the photoreceptor, which affects practical applications.

Table 2 shows the structures of the photoreceptors (A-1) to (A-15) and the photoreceptors (B-1) to (B-4). In table 2, HTM and Resin represent a hole transporting agent and a binder Resin, respectively. In Table 2, HTM-1 to HTM-5 and HTM-6 to HTM-9 in the HTM column represent terphenyl derivatives (HTM-1) to (HTM-5) and hole transport agents (HTM-6) to (HTM-9), respectively. In Table 2, PAR-1 to PAR-6 and PC-1 to PC-5 in the column for binder resins represent polyarylate resins (PAR-1) to PAR-6) and polycarbonate resins (PC-1) to PC-5, respectively.

[ TABLE 2 ]

As shown in Table 2, in the photoreceptors (A-1) to (A-15), the charge generation layer contained a charge generation agent. The charge transport layer contains a hole transport agent and a binder resin. Specifically, the hole-transporting agent is any one of terphenyl derivatives (HTM-1) to (HTM-5). The terphenyl derivatives (HTM-1) to (HTM-5) are compounds contained in the terphenyl derivatives (HTM).

As shown in Table 2, the photoreceptors (A-1) to (A-15) had post-exposure potentials of-124V to-103V, and the drum appearance was evaluated as A (good) or B (normal).

As shown in Table 2, the hole-transporting agent in the photoreceptors (B-1) to (B-4) was one of the hole-transporting agents (HTM-6) to (HTM-9). The hole-transporting agents (HTM-6) to (HTM-9) are not compounds contained in the hole-transporting agent (HTM).

As shown in Table 2, the potential after exposure of the photoreceptors (B-1) to (B-4) was from-156V to-137V. The evaluation results of the drum appearance of all of the photoreceptors (B-1) to (B-3) were C (poor).

The photoreceptors (A-1) to (A-15) are superior in sensitivity characteristics and drum appearance to the photoreceptors (B-1) to (B-4).

Claims (7)

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer,

the photosensitive layer contains a charge generator, a hole transporting agent and a binder resin,

the photosensitive layer is provided with a charge generation layer and a charge transport layer,

the charge generation layer contains the charge generation agent,

the charge transport layer contains the hole transport agent and the binder resin,

the hole-transporting agent is a terphenyl derivative represented by the general formula (HTM),

in the general formula (HTM) described above,

R¹and R⁵One of them represents a methyl group or an ethyl group, the other represents a hydrogen atom, a methyl group or an ethyl group,

R²、R⁴、R⁶、R⁸and R⁹Each independently represents a hydrogen atom or a methyl group,

R³and R⁷Each independently represents a hydrogen atom, a methyl group or a methoxy group.

2. The electrophotographic photoreceptor according to claim 1,

in the general formula (HTM) described above,

R²、R⁴、R⁶、R⁸and R⁹Represents a hydrogen atom.

3. The electrophotographic photoreceptor according to claim 1 or 2,

the terphenyl derivative is represented by the chemical formula (HTM-1), (HTM-2), (HTM-3), (HTM-4) or (HTM-5),

4. the electrophotographic photoreceptor according to claim 1 or 2,

the binder resin has a repeating unit represented by the formula (PC-1) or (PC-2),

5. the electrophotographic photoreceptor according to claim 1 or 2,

the binder resin is a polyarylate resin represented by the general formula (PAR),

in the general formula (PAR) described,

R¹¹and R¹⁴Represents a hydrogen atom or a methyl group,

R¹²、R¹³、R¹⁵and R¹⁶Each independently represents a hydrogen atom or a C1-C10 alkyl group,

R¹²and R¹³May be combined with each other to represent C5-C12 cycloalkylene,

R¹⁵and R¹⁶May be combined with each other to represent C5-C12 cycloalkylene,

x is a divalent group represented by the formula (1-1) or (1-2),

r, s, t and u each independently represent a number greater than 0, and r + s + t + u is 100, r + s is t + u,

6. the electrophotographic photoreceptor according to claim 5,

the polyarylate resin is represented by formula (PAR-1), (PAR-2), (PAR-3) or (PAR-4),

7. the electrophotographic photoreceptor according to claim 1 or 2,

the charge generating agent is a Y-type oxytitanium phthalocyanine pigment.

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