JP6361581B2 - Positively charged single layer type electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a positively charged single layer type electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

  The electrophotographic photosensitive member is used in an electrophotographic image forming apparatus. The electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer contains, for example, a charge generator, a charge transport agent (for example, a hole transport agent and an electron transport agent), and a resin (binder resin) that binds them. An electrophotographic photoreceptor having such a photosensitive layer is called an electrophotographic organic photoreceptor. The photosensitive layer contains a charge generating agent and a charge transport agent in the same layer, and can have both functions of charge generation and charge transport in the same layer. Such an electrophotographic organic photoreceptor is referred to as a single layer type electrophotographic photoreceptor.

  The electrophotographic organic photoreceptor described in Patent Document 1 contains an arylamine compound (specifically, a diamine compound) in the charge transport layer. Patent Document 1 discloses a compound represented by the chemical formula (HT-23).

Japanese Patent Laid-Open No. 9-244278

  However, even if the electrophotographic organic photoreceptor described in Patent Document 1 is used, it is difficult to stably maintain the surface potential of the electrophotographic organic photoreceptor during charging.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a positively charged single layer type electrophotographic photosensitive member capable of stably maintaining the surface potential during charging. Another object of the present invention is to provide a process cartridge and an image forming apparatus that suppress the occurrence of image defects by including such a positively charged single layer type electrophotographic photosensitive member.

  The positively charged single layer type electrophotographic photosensitive member of the present invention includes a photosensitive layer. The photosensitive layer contains at least a charge generator, a hole transport agent, and a binder resin. As the hole transport agent, a triphenylamine derivative represented by the following general formula (I) (hereinafter sometimes referred to as “triphenylamine derivative (I)”) is contained. As the binder resin, a polycarbonate resin having a fluoro group is contained.

In the general formula (I), R ₁ and R ₂ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Alternatively, R ₁ and R ₂ may be bonded to form a cycloalkyl ring having 3 to 8 carbon atoms together with the carbon atom to which R ₁ is bonded and the carbon atom to which R ₂ is bonded. R ₃ , R ₄ , R ₅ , R ₆ and R ₇ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. m1 and m2 each independently represents an integer of 1 or more and 3 or less.

  The process cartridge of the present invention includes the above-described positively charged single layer type electrophotographic photosensitive member.

  The image forming apparatus of the present invention includes an image carrier, a charging unit, an exposure unit, a developing unit, and a transfer unit. The charging unit charges the surface of the image carrier. The exposure unit exposes the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier. The developing unit develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the image carrier to a transfer target. The charging polarity of the charging unit is positive. The image carrier is the positively charged single layer type electrophotographic photosensitive member described above.

  According to the positively charged single layer type electrophotographic photoreceptor of the present invention, the surface potential during charging can be stably maintained. Further, according to the process cartridge and the image forming apparatus of the present invention, it is possible to suppress the occurrence of image defects by including such a positively charged single layer type electrophotographic photosensitive member.

(A), (b), and (c) are schematic sectional views showing the structure of the positively charged single layer type electrophotographic photosensitive member according to the first embodiment. It is the schematic which shows the structure of the one aspect | mode of the image forming apparatus which concerns on 2nd embodiment. It is the schematic which shows the structure of another aspect of the image forming apparatus which concerns on 2nd embodiment.

  Hereinafter, embodiments of the present invention will be described in detail. However, 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. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

  Hereinafter, a compound and its derivatives may be generically named by adding “system” after the compound name. In addition, when “polymer” is added after the compound name to indicate the polymer name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

[First Embodiment: Positively Charged Single-Layer Electrophotographic Photoreceptor]
The first embodiment relates to a positively charged single layer type electrophotographic photosensitive member (hereinafter sometimes referred to as “photosensitive member”) 1. Hereinafter, the photoreceptor 1 of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the structure of the photoreceptor 1.

  The photoreceptor 1 includes a photosensitive layer 3 as shown in FIG. The photosensitive layer 3 contains at least a charge generator, a hole transport agent, and a binder resin. The photosensitive layer 3 may further contain an electron transport agent.

  The photosensitive layer 3 is provided directly or indirectly on the conductive substrate 2. For example, as shown in FIG. 1A, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, for example, an intermediate layer 4 may be provided between the conductive substrate 2 and the photosensitive layer 3 as shown in FIG. Further, as shown in FIGS. 1A and 1B, the photosensitive layer 3 may be exposed as the outermost layer. Alternatively, a protective layer 5 may be provided on the photosensitive layer 3 as shown in FIG.

  The thickness of the photosensitive layer 3 is not particularly limited as long as it can sufficiently function as a photosensitive layer. The thickness of the photosensitive layer 3 is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

  Hereinafter, the conductive substrate 2 and the photosensitive layer 3 will be described. Furthermore, the manufacturing method of the intermediate | middle layer 4 and the photoreceptor 1 is demonstrated.

[1. Conductive substrate]
The conductive substrate 2 is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor 1. The conductive substrate 2 only needs to be formed of a material having at least a surface portion having conductivity. Examples of the conductive substrate 2 include a conductive substrate formed of a conductive material, or a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). Among these materials having conductivity, aluminum or an aluminum alloy is preferable because charge transfer from the photosensitive layer 3 to the conductive substrate 2 is good.

  The shape of the conductive substrate 2 is appropriately selected according to the structure of an image forming apparatus 6 (see FIGS. 2 and 3) described later in the second embodiment. Examples of the conductive substrate 2 include a sheet-shaped conductive substrate or a drum-shaped conductive substrate. Further, the thickness of the conductive substrate 2 is appropriately selected according to the shape of the conductive substrate 2.

[2. Photosensitive layer]
Hereinafter, the charge generator, the hole transport agent, and the binder resin contained in the photosensitive layer 3 will be described. Moreover, the electron transport agent and additive which may be contained in the photosensitive layer 3 as necessary will be described.

[2-1. Charge generator]
The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, and cyanine pigments. , Powders of inorganic photoconductive materials (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon), pyrylium salts, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples thereof include pyrazoline pigments and quinacridone pigments.

  Examples of the phthalocyanine pigment include metal-free phthalocyanine represented by the chemical formula (CG-1) or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (CG-2) or phthalocyanine coordinated with a metal other than titanium oxide (for example, V-type hydroxygallium phthalocyanine). The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape (for example, α-type, β-type, or Y-type) of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

  Examples of the crystal of metal-free phthalocyanine include an X-type crystal of metal-free phthalocyanine (hereinafter sometimes referred to as “X-type metal-free phthalocyanine”). Examples of the titanyl phthalocyanine crystal include α-type crystal, β-type crystal, and Y-type crystal of titanyl phthalocyanine. Hereinafter, α-type crystal, β-type crystal, and Y-type crystal of titanyl phthalocyanine may be referred to as α-type titanyl phthalocyanine, β-type titanyl phthalocyanine, and Y-type titanyl phthalocyanine, respectively. Y-type titanyl phthalocyanine is preferable among the titanyl phthalocyanines because it has a high quantum yield in the wavelength region of 700 nm or more.

  Y-type titanyl phthalocyanine has a main peak at 27.2 ° with a Bragg angle (2θ ± 0.2 °) in, for example, a CuKα characteristic X-ray diffraction spectrum. The main peak in the CuKα characteristic X-ray diffraction spectrum is a peak having the first or second highest intensity in a range where the Bragg angle (2θ ± 0.2 °) is 3 ° or more and 40 ° or less.

(Measuring method of CuKα characteristic X-ray diffraction spectrum)
An example of a method for measuring the CuKα characteristic X-ray diffraction spectrum will be described. A sample (titanyl phthalocyanine) is filled in a sample holder of an X-ray diffractometer (for example, “RINT (registered trademark) 1100” manufactured by Rigaku Corporation), an X-ray tube Cu, a tube voltage 40 kV, a tube current 30 mA, and CuKα. An X-ray diffraction spectrum is measured under the condition of a characteristic X-ray wavelength of 1.542 mm. The measurement range (2θ) is, for example, 3 ° to 40 ° (start angle: 3 °, stop angle: 40 °), and the scanning speed is, for example, 10 ° / min.

Such Y-type titanyl phthalocyanines are classified into three types depending on the difference in thermal characteristics (specifically, thermal characteristics (A) to (C) shown below) in a differential scanning calorimetry (DSC) spectrum.
Thermal characteristics (A): In the thermal characteristics by DSC, there is one peak in the range of 50 ° C. or higher and 270 ° C. or lower in addition to the peak accompanying vaporization of adsorbed water.
Thermal property (B): In the thermal property by DSC, there is no peak in the range of 50 ° C. or more and 400 ° C. or less other than the peak accompanying vaporization of adsorbed water.
Thermal property (C): In the thermal property by DSC, there is no peak in the range of 50 ° C. or higher and 270 ° C. or lower except for the peak accompanying vaporization of adsorbed water, and one peak in the range of 270 ° C. or higher and 400 ° C. or lower. .

(Measurement method for differential scanning calorimetry)
An example of a method for measuring the differential scanning calorimetry spectrum will be described. A sample for evaluation of titanyl phthalocyanine crystal powder is placed on a sample pan, and a differential scanning calorimetry spectrum is measured using a differential scanning calorimeter (for example, “TAS-200 type DSC8230D” manufactured by Rigaku Corporation). The measurement range is, for example, 40 ° C. or more and 400 ° C. or less, and the temperature rising rate is, for example, 20 ° C./min.

  Y-type titanyl phthalocyanine having thermal characteristics (B) and (C) is preferred because of excellent crystal stability, difficulty in causing crystal transition in an organic solvent, and ease of dispersion in the photosensitive layer 3.

  A charge generator having an absorption wavelength in a desired region may be used alone, or two or more charge generators may be used in combination. Further, for example, in a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use the photoreceptor 1 having sensitivity in a wavelength region of 700 nm or more. . Therefore, for example, phthalocyanine pigments are preferable, and metal-free phthalocyanine or titanyl phthalocyanine is more preferable. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the photoreceptor 1 applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of about 350 nm to 550 nm), an sanslon pigment or a perylene pigment is used as a charge generator. Preferably used.

  The content of the charge generating agent is preferably 0.1 parts by weight or more and 50 parts by weight or less, and 0.5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the binder resin in the photosensitive layer 3. Is more preferable.

[2-2. Hole transport agent]
The photosensitive layer 3 contains a triphenylamine derivative (I) as a hole transport agent. The photoreceptor 1 having the photosensitive layer 3 containing the triphenylamine derivative (I) tends to stably maintain the surface potential during charging. The reason is presumed as follows.

  First, the triphenylamine derivative (I), which is a hole transport agent, has a relatively large molecular structure. When the molecular structure of the hole transfer agent is increased, the hopping distance between the hole transfer agents present in the photosensitive layer 3 tends to be reduced. As a result, it is considered that the hole mobility between the hole transport agents is improved.

  Secondly, the triphenylamine derivative (I), which is a hole transport agent, has one nitrogen atom in the molecule. Therefore, the triphenylamine derivative (I) tends to have less charge bias in the molecule as compared with a compound having two or more nitrogen atoms in the molecule (for example, a diamine compound). As a result, it is considered that the hole mobility in the molecule of the triphenylamine derivative (I), which is a hole transport agent, is also improved.

  As described above, for the first and second reasons, it is considered that the photoreceptor 1 including the photosensitive layer 3 containing the triphenylamine derivative (I) can stably maintain the surface potential during charging. The triphenylamine derivative (I) is represented by the general formula (I).

In general formula (I), R ₁ and R ₂ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Alternatively, R ₁ and R ₂ may be bonded to form a cycloalkyl ring having 3 to 8 carbon atoms together with the carbon atom to which R ₁ is bonded and the carbon atom to which R ₂ is bonded. R ₃ , R ₄ , R ₅ , R ₆ and R ₇ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. m1 and m2 each independently represents an integer of 1 or more and 3 or less.

In the general formula (I), examples of the alkyl group having 1 to 4 carbon atoms represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ include a methyl group, an ethyl group, Examples include n-propyl group, isopropyl group, s-butyl group, n-butyl group, and t-butyl group. Since the surface potential of the photoreceptor 1 during charging can be more stably maintained, the alkyl group having 1 to 4 carbon atoms is preferably a methyl group, an ethyl group, an isopropyl group, or an n-butyl group.

In the general formula (I), examples of the alkoxy group having 1 to 4 carbon atoms represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ include a methoxy group, an ethoxy group, An n-propoxy group, an isopropoxy group, an n-butoxy group, an s-butoxy group, or a t-butoxy group may be mentioned.

In general formula (I), R ₁ and R ₂ may be bonded to form a cycloalkyl ring having 3 to 8 carbon atoms. In this case, the carbon atom to which R ₁ is bonded and the carbon atom to which R ₂ is bonded together with R ₁ and R ₂ form a cycloalkyl ring having 3 to 8 carbon atoms. Examples of the cycloalkyl ring having 3 to 8 carbon atoms formed by combining R ₁ and R ₂ include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane.

In general formula (I), the substitution positions of R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ are not particularly limited. For example, R ₁ may be located at any of the ortho position (o position), meta position (m position), and para position (p position) with respect to the nitrogen atom to which the phenyl group having R ₁ is bonded. .

  m1 and m2 each independently represents an integer of 1 or more and 3 or less. It is preferable that m1 and m2 each represent 2 because the surface potential of the photoreceptor 1 during charging can be more stably maintained. For the same reason, it is also preferable that m1 and m2 each represent 3.

R ₂ , R ₃ , R ₄ , R ₅ , R _6, and R ₇ each preferably represent a hydrogen atom because the surface potential of the photoreceptor 1 during charging can be more stably maintained. For the same reason, R ₁ preferably represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. For the same reason, when R ₁ represents an alkyl group having 1 to 4 carbon atoms, R ₁ is preferably present in the para position with respect to the nitrogen atom to which the phenyl group having R ₁ is bonded. For the same reason, when R ₁ represents an alkoxy group having 1 to 4 carbon atoms, R ₁ is preferably present in the ortho position relative to the nitrogen atom to which the phenyl group having R ₁ is bonded.

  In addition to the triphenylamine derivative (I), another hole transporting agent other than the triphenylamine derivative (I) may be used in combination. Another hole transport agent is appropriately selected from known hole transport agents.

  The total content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin in the photosensitive layer 3. preferable.

  The content of the triphenylamine derivative (I) in the hole transport agent is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total mass of the hole transport agent, It is especially preferable that it is 100 mass%.

  Specific examples of the triphenylamine derivative (I) include triphenylamine derivatives represented by chemical formulas (HT-1) to (HT-20). Hereinafter, the triphenylamine derivatives represented by the formulas (HT-1) to (HT-20) may be referred to as triphenylamine derivatives (HT-1) to (HT-20), respectively.

[2-3. Electron transport agent]
Examples of the electron transfer agent include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, Examples include dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, or dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds. These electron transfer agents may be used alone or in combination of two or more.

  Specific examples of the electron transfer agent include compounds represented by general formulas (V) to (VIII). Each of the compounds represented by the general formulas (V) and (VI) is a diphenoquinone compound. The compound represented by the general formula (VII) is an azoquinone compound. The compound represented by the general formula (VIII) is a diimide compound (for example, naphthalene tetracarboxylic acid diimide derivative).

In the general formulas (V), (VI), (VII) and (VIII), R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₈₁ , R ₈₂ , R ₈₃ and R ₈₄ each independently represents a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. Represents an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. In general formula (VII), R ₇₃ represents a halogen atom, a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkoxy group which may have a substituent, The aralkyl group which may have a substituent, the aryl group which may have a substituent, or the heterocyclic group which may have a substituent is represented.

In the general formulas (V), (VI), (VII), and (VIII), R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ , R ₈₃ and R ₈₄ , examples of the alkyl group include alkyl groups having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, s-butyl, n-butyl, tert-butyl, n-pentyl, and isopentyl. Group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, or decyl group. Among the alkyl groups having 1 to 10 carbon atoms, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 5 carbon atoms is more preferable, a methyl group, an ethyl group, and tert-butyl. A group or a 1,1-dimethylpropyl group is particularly preferred. The alkyl group may be a linear alkyl group, a branched alkyl group, a cyclic alkyl group, or an alkyl group obtained by combining these. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In the general formulas (V), (VI), (VII), and (VIII), R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ , R ₈₃ and R ₈₄ , examples of the alkenyl group include alkenyl groups having 2 to 10 carbon atoms, preferably alkenyl groups having 2 to 6 carbon atoms, and 2 to 4 carbon atoms. The following alkenyl groups are more preferred. The alkenyl group may be a linear alkenyl group, a branched alkenyl group, a cyclic alkenyl group, or an alkenyl group combining these. The alkenyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In the general formulas (V), (VI), (VII), and (VIII), R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ , R ₈₃ and R ₈₄ , examples of the alkoxy group include an alkoxy group having 1 to 10 carbon atoms, preferably an alkoxy group having 1 to 6 carbon atoms, and preferably having 1 to 4 carbon atoms. The following alkoxy groups are more preferred. The alkoxy group may be a linear alkoxy group, a branched alkoxy group, a cyclic alkoxy group, or an alkoxy group that combines these. The alkoxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In the general formulas (V), (VI), (VII), and (VIII), R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ , R ₈₃ and R ₈₄ , examples of the aralkyl group include aralkyl groups having 7 to 15 carbon atoms, preferably aralkyl groups having 7 to 13 carbon atoms, and have 7 to 12 carbon atoms. The following aralkyl groups are more preferred. The aralkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, and a fat having 2 to 4 carbon atoms. An acyl group, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group. The number of substituents is not particularly limited, but is preferably 5 or less, and more preferably 3 or less.

In the general formulas (V), (VI), (VII), and (VIII), R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ , R ₈₃ and R ₈₄ , the aryl group includes, for example, a phenyl group, a group formed by condensing two or three benzene rings, or a single group of two or three benzene rings. Examples thereof include a group formed by linking with a bond. The number of benzene rings contained in the aryl group is, for example, 1 or more and 3 or less, and preferably 1 or 2. Examples of the substituent that the aryl group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, and carbon. Examples thereof include an aliphatic acyl group having 2 to 4 atoms, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group.

In the general formulas (V), (VI), (VII), and (VIII), R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₇₃ , R ₈₁ , In R ₈₂ , R ₈₃ and R ₈₄ , the heterocyclic group is, for example, a 5-membered or 6-membered monocyclic heterocyclic group containing one or more heteroatoms selected from the group consisting of N, S and O A heterocyclic group in which such monocycles are condensed; or a heterocyclic group in which such a single ring is condensed with a 5-membered or 6-membered hydrocarbon ring. When the heterocyclic group is a condensed ring, the number of rings contained in the condensed ring is preferably 3 or less. Examples of the substituent that the heterocyclic group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, Examples thereof include an aliphatic acyl group having 2 to 4 carbon atoms, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group.

In R ₇₃ in general formula (VII), examples of the halogen atom include a fluoro group, a chloro group, a bromo group, and an iodo group, and a chloro group is preferable.

In the general formulas (V), (VI), (VII), and (VIII), R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₈₁ , R ₈₂ , R ₈₃ and R ₈₄ each independently represents an alkyl group having 1 to 6 carbon atoms, and R ₇₃ represents a halogen atom. It is preferable to represent.

  Specific examples of the compounds represented by the general formulas (V) to (VIII) include compounds represented by the chemical formulas (ET-1) to (ET-4).

  The content of the electron transport agent is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the binder resin in the photosensitive layer 3.

[2-4. Binder resin]
The photosensitive layer 3 contains a polycarbonate resin having a fluoro group as a binder resin. It is considered that when the photosensitive layer 3 contains a polycarbonate resin having a fluoro group, the surface potential of the photoreceptor 1 during charging is stably maintained. The reason is presumed as follows.

First, the photosensitive layer 3 containing a polycarbonate resin having a fluoroalkyl group, the gas hardly adheres, such as ozone and NO _X. Therefore, even when the photoreceptor 1 is used in the presence of such a gas, it is considered that deterioration of the photosensitive layer 3 is unlikely to occur.

  Second, when the photoreceptor 1 is used in an image forming apparatus 6 having a cleaning device (for example, a cleaning blade), the photosensitive layer 3 containing a polycarbonate resin having a fluoro group is rubbed by the cleaning device. Therefore, it tends to be charged positively.

  For the above first and second reasons, the surface potential of the photoreceptor 1 during charging (particularly during positive charging) is stably maintained by the photosensitive layer 3 containing a polycarbonate resin having a fluoro group. It is guessed.

  Examples of the polycarbonate resin having a fluoro group include bisphenol Z type polycarbonate resin, bisphenol B type polycarbonate resin, bisphenol CZ type polycarbonate resin, bisphenol C type polycarbonate resin, and bisphenol A type polycarbonate resin. Furthermore, these resins have a fluoro group in the resin.

  Specific examples of the polycarbonate resin having a fluoro group include a polycarbonate resin represented by the general formula (II).

In the general formula (II), R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms which may have a substituent. R ₂₅ and R ₂₆ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms which may have a substituent, or 6 to 14 carbon atoms which may have a substituent. Represents an aryl group. Alternatively, R ₂₅ and R ₂₆ may combine to form a cycloalkylidene group having 3 to 8 carbon atoms which may have a substituent. R ₂₇ , R ₂₈ , R ₂₉ and R ₃₀ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms which may have a substituent. Rt represents a terminal group.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ , R ₂₉ and R _{30 in the} general formula (II) Examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an s-butyl group, an n-butyl group, and a t-butyl group. Among these, a methyl group is preferable because the surface potential of the photoreceptor 1 during charging can be more stably maintained.

In the general formula (II), examples of the aryl group having 6 to 14 carbon atoms represented by R ₂₅ and R ₂₆ include an aryl group having 6 to 14 carbon atoms (for example, a single ring or a condensed ring). It is done. Examples of the monocyclic aryl group include a phenyl group. Examples of the condensed ring aryl group include a bicyclic aryl group (for example, a naphthyl group) or a tricyclic aryl group (for example, an anthryl group or a phenanthryl group). Among these, a phenyl group is preferable because the surface potential of the photoreceptor 1 during charging can be more stably maintained.

In the general formula (II), examples of the cycloalkylidene group having 3 to 8 carbon atoms formed by combining R ₂₅ and R ₂₆ include cyclopropylidene group, cyclobutylidene group, cyclopentylidene group , A cyclohexylidene group, a cycloheptylidene group, or a cyclooctylidene group. Of these, a cyclohexylidene group is preferable because the surface potential of the photoreceptor 1 during charging can be more stably maintained.

  The alkyl group having 1 to 4 carbon atoms, the aryl group having 6 to 14 carbon atoms, and the cycloalkylidene group having 3 to 8 carbon atoms may each have a substituent. Examples of the substituent include a halogen atom, and more specifically, a fluoro group, a chloro group, a bromo group, or an iodo group.

The polycarbonate resin represented by the general formula (II) further satisfies one or both of the following (a) and (b).
(A) One or more of R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ , R ₂₉ and R ₃₀ have a fluoro group.
(B) The terminal group has a fluoro group.

When the polycarbonate resin represented by the general formula (II) satisfies (a), among R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ , R ₂₉ and R ₃₀ One or more of have a fluoro group. If _{R 21, R 22, R 23} , R 24, R 27, R 28, R 29 or R ₃₀ has a fluoro _{group, R 21, R 22, R} 23, R 24, R 27, R 28, R 29 or R ₃₀ represents an alkyl group of 4 or less carbon atoms 1 or more having a fluoroalkyl group. When R ₂₅ or R ₂₆ has a fluoro group, R ₂₅ or R ₂₆ represents an alkyl group having 1 to 4 carbon atoms having a fluoro group, or an aryl group having 6 to 14 carbon atoms having a fluoro group. Represent. Alternatively, R ₂₅ and R ₂₆ may be bonded to form a cycloalkylidene group having 3 to 8 carbon atoms and having a fluoro group. When the polycarbonate resin represented by the general formula (II) satisfies (a), specific examples of Rt include p-tert-butyl-phenyl group, p-phenylphenyl group, and p-cumylphenyl group.

When the aryl group having 6 to 14 carbon atoms represented by R ₂₅ and R ₂₆ has a substituent, the substitution position of the substituent is not particularly limited. For example, when the aryl group is a phenyl group, the substituent is the ortho position (o position), meta position (m position), and para position (p position) of the phenyl group with respect to the carbon atom to which the phenyl group is bonded. It may be located in any of these. Since the surface potential of the photoreceptor 1 during charging can be more stably maintained, the substituent is preferably located at the para position (p position) of the phenyl group with respect to the carbon atom to which the phenyl group is bonded.

When the cycloalkylidene group having 3 to 8 carbon atoms represented by R ₂₅ and R ₂₆ has a substituent, the substitution position of the substituent is not particularly limited. For example, when the cycloalkylidene group having 3 to 8 carbon atoms is a cyclohexylidene group, the substituent is the 2-position, 3-position of the cyclohexylidene group with respect to the carbon atom to which the cyclohexylidene group is bonded. It may be located in any of the 4th, 5th and 6th positions. The substituent is preferably located at the 4-position of the cyclohexylidene group because the surface potential of the photoreceptor 1 during charging can be more stably maintained.

  In general formula (II), it is n1 + n2 = 1.0 and is 0.0 <n1 <= 1.0. The polycarbonate resin represented by the general formula (II) is represented by the repeating unit represented by the general formula (IIa) (hereinafter sometimes referred to as “repeating unit (IIa)”) and the general formula (IIb). (Hereinafter sometimes referred to as “repeat unit (IIb)”). n1 is a ratio of the number of moles of the repeating unit (IIa) to the total number of moles of the repeating unit (IIa) and the repeating unit (IIb) in the polycarbonate resin represented by the general formula (II) Represents. n2 is the ratio of the number of moles of the repeating unit (IIb) to the total number of moles of the repeating unit (IIa) and the repeating unit (IIb) in the polycarbonate resin represented by the general formula (II) Represents.

In the general formulas (IIa) and (IIb), R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ , R ₂₉ and R ₃₀ are each in the general formula (II). of _{R 21, R 22, R 23} , R 24, R 25, R 26, R 27, the same meaning as R _28, R ₂₉ and R _30.

  As a preferred example for more stably maintaining the surface potential of the photoreceptor 1 during charging, n1 is 1.0 and n2 is 0.0. In this case, the polycarbonate resin represented by the general formula (II) is a polymer formed only from the repeating unit (IIa).

  Another preferred example for more stably maintaining the surface potential of the photoreceptor 1 during charging is 0.4 ≦ n1 ≦ 0.8, and more preferred example is 0.5 ≦ n1. ≦ 0.7.

  n1 and n2 are calculated, for example, by measuring the polycarbonate resin represented by the general formula (II) using a nuclear magnetic resonance (NMR) spectrometer. By calculating the ratio of the peak characteristic of the repeating unit (IIa) appearing in the NMR spectrum and the peak characteristic of the repeating unit (IIb), n1 and n2 are obtained.

  Examples of the polycarbonate resin represented by the general formula (II) include a random copolymer, an alternating copolymer, a periodic copolymer, and a block copolymer. The random copolymer is a copolymer in which repeating units (IIa) and repeating units (IIb) are randomly arranged. The alternating copolymer is a copolymer in which repeating units (IIa) and repeating units (IIb) are alternately arranged. The periodic copolymer is a copolymer in which one or more repeating units (IIa) and one or more repeating units (IIb) are periodically arranged. The block copolymer is a copolymer in which a block composed of a plurality of repeating units (IIa) and a block composed of a plurality of repeating units (IIb) are arranged.

  When the polycarbonate resin represented by the general formula (II) satisfies (b), the terminal group has a fluoro group. When the terminal group has a fluoro group, the terminal group is preferably a terminal group represented by the general formula (III) or (IV). First, the terminal group represented by general formula (III) is demonstrated.

In the general formula (III), R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms. An alkoxy group, an alkoxycarbonyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 14 carbon atoms is represented. An alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 14 carbon atoms are each fluoro It has one or more substituents selected from the group consisting of an alkyl group having 1 to 20 carbon atoms having a group, an alkoxy group having 1 to 20 carbon atoms having a fluoro group, and a fluoro group.

R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ are not all hydrogen atoms. That is, in the general formula (III), at least one of R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ is an alkyl group having 1 to 20 carbon atoms, and 1 to 20 carbon atoms. An alkoxy group, an alkoxycarbonyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 14 carbon atoms is represented.

In the general formula (III), examples of the alkyl group having 1 to 20 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ include methyl group, ethyl group, n-propyl group, isopropyl Group, n-butyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, Examples include a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an icosyl group. Since the surface potential of the photoreceptor 1 during charging can be more stably maintained, an alkyl group having 1 to 11 carbon atoms is preferable, an alkyl group having 3 to 11 carbon atoms is more preferable, an n-propyl group, A t-butyl group, a hexyl group, an octyl group, a nonyl group, or an undecyl group is particularly preferable, and a t-butyl group is most preferable.

Examples of the alkoxy group having 1 to 20 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R _{35 in the} general formula (III) include a methoxy group, an ethoxy group, an n-propoxy group, an iso Propoxy group, n-butoxy group, s-butoxy group, t-butoxy group, pentyloxy group, isopentyloxy group, neopentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy group, Examples include an undecyloxy group, a dodecyloxy group, a tridecyloxy group, a tetradecyloxy group, a pentadecyloxy group, a hexadecyloxy group, a heptadecyloxy group, an octadecyloxy group, a nonadecyloxy group, or an icosyloxy group. An alkoxy group having 1 to 8 carbon atoms is preferred, and an octyloxy group is more preferred because the surface potential of the photoreceptor 1 during charging can be more stably maintained.

Examples of the alkoxycarbonyl group having 1 to 20 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R _{35 in the} general formula (III) include a methoxycarbonyl group, an ethoxycarbonyl group, and n-propoxy group. Carbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, s-butoxycarbonyl group, t-butoxycarbonyl group, pentyloxycarbonyl group, isopentyloxycarbonyl group, neopentyloxycarbonyl group, hexyloxycarbonyl group, heptyloxy Carbonyl group, octyloxycarbonyl group, nonyloxycarbonyl group, decyloxycarbonyl group, undecyloxycarbonyl group, dodecyloxycarbonyl group, tridecyloxycarbonyl group, tetradecyloxycarbonyl group, pentadecyloxycarbonyl Boniru group, a hexadecyloxycarbonyl group, the descriptor decyloxycarbonyl group, octadecyloxycarbonyl group, nonadecyl oxycarbonyl group, or icosyl oxycarbonyl group. An alkoxycarbonyl group having 1 to 12 carbon atoms is preferable, an alkoxycarbonyl group having 6 to 12 carbon atoms is more preferable, and hexyloxycarbonyl is more preferable because the surface potential of the photoreceptor 1 during charging can be more stably maintained. Group or dodecyloxycarbonyl group is particularly preferable, and dodecyloxycarbonyl group is most preferable.

In the general formula (III), examples of the aryl group having 6 to 14 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ are as follows: R ₂₅ and R ₂₆ in the general formula (II) This is the same as the aryl group having 6 to 14 carbon atoms. An aryl group having 6 to 10 carbon atoms is preferred, and a phenyl group is more preferred because the surface potential of the photoreceptor 1 during charging can be more stably maintained.

As already described, in general formula (III), R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ represent an alkyl group having 1 to 20 carbon atoms and an alkoxy group having 1 to 20 carbon atoms. The alkoxycarbonyl group having 1 to 20 carbon atoms and the aryl group having 6 to 14 carbon atoms each have one or more substituents. The substituent is selected from the group consisting of an alkyl group having 1 to 20 carbon atoms having a fluoro group, an alkoxy group having 1 to 20 carbon atoms having a fluoro group, and a fluoro group.

Examples of the alkyl group having 1 to 20 carbon atoms having a fluoro group as a substituent include a —C _q1 F _(q1 × _{2 + 1)} group, a —C _q1 HF _(q1 × ₂₎ group, or — A C _q1 H ₂ F _(q1 × _2-1) group. Here, q1 represents an integer of 1 or more and 20 or less. q1 is preferably an integer of 1 to 9. Specific examples of the alkyl group having 1 to 20 carbon atoms having a fluoro group as a substituent include a perfluorononyl group (—C ₉ F ₁₉ group).

Examples of the alkoxy group having 1 to 20 carbon atoms having a fluoro group as a substituent include an —O—C _q2 F _(q2 × _{2 + 1)} group, —O— _Cq2 HF _(q2 × _2). Group, or —O—C _q2 H ₂ F _(q2 × _2-1) group. Here, q2 represents an integer of 1 or more and 20 or less. q2 is preferably an integer of 1 to 13. Specific examples of the alkoxy group having 1 to 20 carbon atoms having a fluoro group as a substituent include 1H, 1H-perfluorododecyloxy group (—OCH ₂ —C ₁₁ F ₂₃ group) or 1H, 1H. - perfluoro tridecyl group (-OCH ₂ -C ₁₂ F ₂₅ group) can be mentioned.

When the aryl group having 6 to 14 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ has a substituent, the substitution position of the substituent is not particularly limited. For example, when the aryl group having 6 to 14 carbon atoms is a phenyl group, the substituent is the ortho position (o position) or meta position (m position) of the phenyl group with respect to the carbon atom to which the phenyl group is bonded. , And the para position (p position). Since the surface potential of the photoreceptor 1 during charging can be more stably maintained, the substituent is preferably located at the para position (p position) of the phenyl group with respect to the carbon atom to which the phenyl group is bonded.

In the general formula (III), R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ are each independently the following functional groups because the surface potential of the photosensitive member 1 during charging can be maintained more stably. Is preferably represented.
Hydrogen atom;
An alkyl group having 1 to 20 carbon atoms, substituted with a fluoro group;
An alkoxy group having 1 to 20 carbon atoms having a fluoro group and an alkyl group having 1 to 20 carbon atoms substituted with a fluoro group;
An alkoxycarbonyl group having 1 to 20 carbon atoms, which is substituted with a fluoro group;
An alkoxy group having 1 to 20 carbon atoms substituted with a fluoro group; or an aryl group having 6 to 14 carbon atoms substituted with an alkyl group having 1 to 20 carbon atoms having a fluoro group.

In the general formula (III), when an alkyl group having 1 to 20 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ is substituted with a fluoro group, the carbon atom substituted with the fluoro group Examples of the alkyl group having a number of 1 or more and 20 or less include a —C _q3 F _(q3 × _{2 + 1)} group, a —C _q3 HF _(q3 × ₂₎ group, or a —C _q3 H ₂ F _(q3 × _{2-1) )} Group. Here, q3 represents an integer of 1 or more and 20 or less. q3 is preferably an integer of 1 to 11. Since the surface potential of the photoreceptor 1 during charging can be more stably maintained, a perfluoro t-butyl group (t-C ₄ F ₉ group), a perfluorohexyl group (—C ₆ F ₁₃ group), perfluorooctyl A group (—C ₈ F ₁₇ group), a perfluorononyl group (—C ₉ F ₁₉ group), or a perfluoroundecyl group (—C ₁₁ F ₂₃ group) is preferred.

In the general formula (III), an alkyl group having 1 to 20 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ is an alkoxy group having 1 to 20 carbon atoms having a fluoro group; When substituted with a fluoro group, the following groups are preferred. That is, an alkyl group having 1 to 3 carbon atoms that is substituted with a fluoro group and an alkoxy group having 1 to 13 carbon atoms and a fluoro group is preferable. Among them, hexafluoro (1H, 1H-perfluorododecyloxy) propyl group (—C ₃ F ₆ (OCH ₂ —C ₁₁ F ₂₃ ) group) or hexafluoro (1H, 1H-perfluorotridecyloxy) propyl The group (—C ₃ F ₆ (OCH ₂ —C ₁₂ F ₂₅ ) group) is more preferred.

In the general formula (III), when an alkoxycarbonyl group having 1 to 20 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ is substituted with a fluoro group, the carbon substituted with the fluoro group Examples of the alkoxycarbonyl group having 1 to 20 atoms include a —CO—O—C _q4 F _(q4 × _{2 + 1)} group, a —CO—O— _Cq4 HF _(q4 × ₂₎ group, or —CO _{-O-C q4 H 2 F (} q4 × 2-1) group. Here, q4 represents an integer of 1 or more and 20 or less. q4 is preferably an integer of 1 or more and 12 or less. Especially, since the surface potential of the photoreceptor 1 during charging can be more stably maintained, a perfluorododecyloxycarbonyl group (—CO—O—n—C ₁₂ F ₂₅ group) or a perfluorohexyloxycarbonyl group ( -CO-O-C ₆ F ₁₃ group) is preferred.

In the general formula (III), when an alkoxy group having 1 to 20 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ is substituted with a fluoro group, the carbon atom substituted with the fluoro group Examples of the alkoxy group having a number of 1 or more and 20 or less include an —O—C _q5 F _(q5 × _{2 + 1)} group, an —O—C _q5 HF _(q5 × ₂₎ group, or an —O—C _q5 H ₂ F group. _(q5 × _2-1) group. Here, q5 is an integer of 1 or more and 20 or less. q5 is preferably an integer of 1 or more and 8 or less. Among these, a 1H, 1H-perfluorooctyloxy group (—O—CH ₂ —C ₇ F ₁₅ group) is preferable because the surface potential of the photoreceptor 1 during charging can be more stably maintained.

In the general formula (III), an aryl group having 6 to 14 carbon atoms represented by R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ is substituted with an alkyl group having 1 to 20 carbon atoms having a fluoro group. In this case, examples of the aryl group having 6 to 14 carbon atoms substituted with an alkyl group having 1 to 20 carbon atoms having a fluoro group include alkyl having 1 to 9 carbon atoms having a fluoro group. An aryl group having 6 to 10 carbon atoms substituted with a group is preferred. Among these, a phenyl group substituted with a perfluorononyl group (—C ₉ F ₁₉ group) is more preferable because the surface potential of the photoreceptor 1 during charging can be more stably maintained.

In order to more stably maintain the surface potential of the photoreceptor 1 during charging, it is preferable that R ₃₁ , R ₃₂ , R _34, and R ₃₅ each represent a hydrogen atom in the general formula (III). R ₃₃ preferably represents an alkyl group having 1 to 20 carbon atoms or an alkoxycarbonyl group having 1 to 20 carbon atoms. The alkyl group having 1 to 20 carbon atoms and the alkoxycarbonyl group having 1 to 20 carbon atoms are each preferably substituted with 3 to 41 fluoro groups.

  Next, the terminal group represented by general formula (IV) is demonstrated.

In the general formula (IV), R ₄₁ represents a single bond or —CO—. R ₄₂ and R ₄₃ each independently represents a hydrogen atom, a fluoromethyl group, a difluoromethyl group, or a trifluoromethyl group. R ₄₄ represents a hydrogen atom, a fluoro group, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, or —OR ₄₅ —OR ₄₆ . P1 represents an integer of 0 or more and 12 or less.

R ₄₂ , R ₄₃ and R ₄₄ are not all hydrogen atoms. That is, when R ₄₂ and R ₄₃ are each a hydrogen atom, R ₄₄ represents a fluoro group, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, or —OR ₄₅ —OR ₄₆ . When R ₄₄ is a hydrogen atom, at least one of R ₄₂ and R ₄₃ represents a fluoromethyl group, a difluoromethyl group, or a trifluoromethyl group.

When R ₄₄ represents —OR ₄₅ —OR ₄₆ , R ₄₅ represents an alkylidene group having 1 to 20 carbon atoms having a fluoro group. R ₄₆ represents an alkyl group having 1 to 20 carbon atoms and having a fluoro group.

In the alkylidene group having 1 to 20 carbon atoms having the fluoro group represented by R ₄₅ , examples of the alkylidene group having 1 to 20 carbon atoms include methylidene group, ethylidene group, n-propylidene group, isopropylidene group, n-butylidene group, s-butylidene group, t-butylidene group, pentylidene group, isopentylidene group, neopentylidene group, hexylidene group, heptylidene group, octylidene group, nonylidene group, decylidene group, undecylidene group, dodecylidene group, tridecylidene group Group, tetradecylidene group, pentadecylidene group, hexadecylidene group, heptadecylidene group, octadecylidene group, nonadecylidene group, or icosilidene group. Among these, an alkylidene group having 1 to 4 carbon atoms is preferable, and an alkylidene group having 1 to 2 carbon atoms is more preferable. The alkylidene group having 1 to 20 carbon atoms preferably has 2 or more and 40 or less fluoro groups, more preferably 2 or more and 8 or less fluoro groups, and more preferably 2 or more and 4 or less. It is particularly preferable to have a fluoro group. In order to more stably maintain the surface potential of the photoreceptor 1 during charging, the alkylidene group having 1 to 20 carbon atoms and having a fluoro group represented by R ₄₅ is preferably a fluoro group having 2 to 8 carbon atoms. And an alkylidene group having 1 to 4 carbon atoms, more preferably a perfluoroethylidene group (—CF ₂ —CF ₂ — group).

In the alkyl group having 1 to 20 carbon atoms having the fluoro group represented by R _46, the alkyl group having 1 to 20 carbon atoms is, for example, R ₃₁ , R ₃₂ , R ₃₃ , The same as the examples of the alkyl group having 1 to 20 carbon atoms represented by R ₃₄ and R ₃₅ . Among these, an alkyl group having 1 to 4 carbon atoms is preferable. The alkyl group having 1 to 20 carbon atoms preferably has 3 or more and 41 or less fluoro groups, and more preferably has 3 or more and 9 or less fluoro groups. In order to more stably maintain the surface potential of the photoreceptor 1 during charging, the alkyl group having 1 to 20 carbon atoms and having a fluoro group represented by R ₄₆ is preferably a fluoro group having 3 to 9 carbon atoms. And an alkyl group having 1 to 4 carbon atoms, more preferably a perfluoro s-butyl group.

  P1 represents an integer of 0 or more and 12 or less. P1 preferably represents an integer of 1 to 5, more preferably an integer of 1 to 3, and particularly preferably 1.

In order to maintain the surface potential of the photoreceptor 1 at the time of charging more stably, in the general formula (IV), R ₄₁ preferably represents a single bond. R ₄₂ and R ₄₃ each preferably represent a hydrogen atom. R ₄₄ preferably represents —OR ₄₅ —OR ₄₆ . R ₄₅ preferably represents an alkylidene group having 1 to 4 carbon atoms having 2 to 8 fluoro groups. R ₄₆ preferably represents an alkyl group having 1 to 4 carbon atoms having 3 to 9 fluoro groups. P1 preferably represents an integer of 1 to 5.

  Specific examples of the polycarbonate resin represented by the general formula (II) include polycarbonate resins represented by the chemical formulas (Resine-1) to (Resine-6). In addition, in the chemical formulas (Resine-1) to (Resine-5), the suffix of the repeating unit corresponds to the number represented by n1 in the general formula (II). In the chemical formula (Resine-6), the suffix of the repeating unit corresponds to the number represented by n1 and n2 in the general formula (II).

  Hereinafter, a method for producing a polycarbonate resin having a fluoro group will be described. An example of a method for producing a polycarbonate resin having a fluoro group is a method (so-called phosgene method) in which a diol compound for forming a repeating unit of a polycarbonate resin is subjected to interfacial condensation polymerization with a carbonyl halide. Another example of a method for producing a polycarbonate resin having a fluoro group is a method of transesterifying a diol compound and diphenyl carbonate. In addition, the manufacturing method of polycarbonate resin which has a fluoro group is not specifically limited. The polycarbonate resin having a fluoro group is produced by appropriately selecting a phosgene method, a transesterification method, or other known methods.

  Hereinafter, the case where a polycarbonate resin represented by the general formula (II) is produced as a polycarbonate resin having a fluoro group using the phosgene method will be described as an example.

  The polycarbonate resin represented by the general formula (II) is produced by interfacial polycondensation of the compound represented by the general formula (IIam) and the compound represented by the general formula (IIbm). Hereinafter, the compound represented by the general formula (IIam) and the compound represented by the general formula (IIbm) may be referred to as a compound (IIam) and a compound (IIbm), respectively. The interfacial polycondensation reaction is performed in the presence of a terminal terminator. The interfacial polycondensation reaction may be performed in the presence of an acid binder and a solvent, for example, using a dicarbonyl halide (eg, phosgene).

In the general formulas (IIam) and (IIbm), R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ , R ₂₉ and R ₃₀ are each in the general formula (II) of _{R 21, R 22, R 23} , R 24, R 25, R 26, R 27, the same meaning as R _28, R ₂₉ and R _30.

  The amount of compound (IIam) added is greater than 0 mol% (n1 = 0.0) and 100 mol% (n1 = n) with respect to the total number of moles of compound (IIam) and compound (IIbm). 1.0) or less. As a preferred example for more stably maintaining the surface potential of the photoreceptor 1 during charging, the amount of compound (IIam) added is more preferably 100 mol% (n1 = 1.0). As another preferred example for more stably maintaining the surface potential of the photoreceptor 1 during charging, the amount of the compound (IIam) added is 40 mol% (n1 = 0.4) or more and 80 mol% (n1 = 0.8) or less, and a more preferable example is 50 mol% (n1 = 0.5) or more and 70 mol% (n1 = 0.7) or less. When the amount of compound (IIam) added is 100 mol% with respect to the total number of moles of compound (IIam) and compound (IIbm), compound (IIbm) is used for the interfacial polycondensation reaction. Not.

  By appropriately selecting a terminal stopper in the interfacial polycondensation reaction, a desired terminal group is introduced into the polycarbonate resin represented by the general formula (II). Examples of the terminal terminator include a monovalent carboxylic acid, a monovalent aliphatic alcohol, a monovalent phenol, or a derivative of a monovalent phenol. Examples of the terminal terminator include compounds represented by the general formula (IIcm).

  In general formula (IIcm), Rt has the same meaning as Rt in general formula (II). When the terminal group has a fluoro group, Rt in the general formula (IIcm) is preferably represented by the general formula (III) or (IV) already described.

  Specific examples of the terminal terminator having no fluoro group include p-tert-butyl-phenol, p-phenylphenol, and p-cumylphenol.

Specific examples of the terminal terminator having a fluoro group include the following compounds.
p-perfluorononylphenol;
p- (perfluorononylphenyl) phenol;
p- (perfluorohexyl) phenol;
p-tert-perfluorobutylphenol;
Perfluorooctylphenol;
Perfluorohexylphenol;
1- (p-hydroxybenzyl) perfluorodecane;
p- (2- (1H, 1H-perfluorotridecyloxy) -1,1,2,3,3,3-hexafluoropropyl) phenol;
3,5-bis (perfluorohexyloxycarbonyl) phenol;
perfluorododecyl p-hydroxybenzoate;
p- (1H, 1H-perfluorooctyloxy) phenol;
2H, 2H, 9H-perfluorononanoic acid;
1,1,1,3,3,3-hexafluoro-2-propanol;
2,2-difluoro-2- (2- (1,1,2,3,3,3-hexafluoro-2-trifluoromethyl) propoxy-1,1,2,2-tetrafluoro) ethoxyethanol;
A compound represented by the general formula “H— (CF ₂ ) r—CH ₂ —OH” (r represents an integer of 1 to 12); or the general formula “F— (CF ₂ ) s—CH ₂ — Compound represented by “OH” (s represents an integer of 1 or more and 12 or less).

  Examples of acid binders include alkali metal hydroxides (eg, sodium hydroxide, potassium hydroxide, lithium hydroxide, or cesium hydroxide), alkaline earth metal hydroxides (eg, magnesium hydroxide, or water) Calcium oxide), alkali metal weak acid salts (for example, sodium carbonate or potassium carbonate), alkaline earth metal weak acid salts (for example, calcium acetate), or organic bases (for example, pyridine). These acid binders may be used alone or in combination of two or more. The amount of the acid binder added is preferably 1 molar equivalent or more, preferably 1 molar equivalent or more and 10 molar equivalents per 1 mole of the total number of moles of the hydroxyl group of the compound (IIam) and the hydroxyl group of the compound (IIbm). The following is more preferable.

  Examples of the solvent include aromatic hydrocarbons (for example, toluene or xylene), halogenated hydrocarbons (for example, methylene chloride, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane). 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, or chlorobenzene), ketones (eg, cyclohexanone, acetone, or acetophenone) , Ethers (for example, tetrahydrofuran or 1,4-dioxane). These solvents may be used alone or in combination of two or more. Further, the interfacial polycondensation reaction may be performed using two kinds of solvents that are not mixed with each other. Heretofore, an example of a method for producing a polycarbonate resin having a fluoro group has been described.

  The molecular weight of the polycarbonate resin having a fluoro group is preferably 40000 or more, more preferably 40000 or more and 52500 or less in terms of viscosity average molecular weight. When the viscosity average molecular weight of the binder resin is 40000 or more, the abrasion resistance of the binder resin can be sufficiently increased, and the photosensitive layer 3 is hardly worn. Further, when the molecular weight of the binder resin is 52500 or less, the binder resin is easily dissolved in the solvent when the photosensitive layer 3 is formed, and the viscosity of the coating solution for the photosensitive layer does not become too high. As a result, the photosensitive layer 3 can be easily formed. The binder resin having a fluoro group may be used alone or in combination of two or more.

  The photosensitive layer 3 may further contain another binder resin other than the polycarbonate resin having a fluoro group as a binder resin. As another binder resin, a thermoplastic resin, a thermosetting resin, or a photocurable resin is mentioned, for example. As the thermoplastic resin, for example, styrene resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic copolymer, polyethylene resin, Ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polyarylate resin, polysulfone resin, diallyl phthalate Examples thereof include resins, ketone resins, polyvinyl butyral resins, polyether resins, and polyester resins. Examples of the thermosetting resin include silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, and other crosslinkable thermosetting resins. As a photocurable resin, an epoxy acrylic acid resin or a urethane-acrylic acid copolymer is mentioned, for example. These may be used individually by 1 type and may be used in combination of 2 or more type.

[2-5. Additive]
The photosensitive layer 3 may contain various additives as long as the electrophotographic characteristics of the photoreceptor 1 are not adversely affected. Examples of additives include deterioration inhibitors (eg, antioxidants, radical scavengers, singlet quenchers, or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, and dispersion stabilizers. Agents, waxes, acceptors, donors, surfactants, plasticizers, sensitizers, or leveling agents. Examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone, or a derivative thereof, an organic sulfur compound, or an organic phosphorus compound.

[3. Middle layer]
In the photoreceptor 1, an intermediate layer 4 (particularly an undercoat layer) may be provided between the conductive substrate 2 and the photosensitive layer 3. The intermediate layer 4 contains, for example, inorganic particles and a resin (interlayer resin) used for the intermediate layer 4. The presence of the intermediate layer 4 makes it easy to suppress an increase in resistance by smoothing the flow of current generated when the photosensitive member 1 is exposed while maintaining an insulating state to the extent that leakage can be suppressed.

  As the inorganic particles, for example, metal (for example, aluminum, iron, or copper), metal oxide (for example, titanium oxide, alumina, zirconium oxide, tin oxide, or zinc oxide) particles, or non-metal oxide (for example, , Silica) particles. These inorganic particles may be used individually by 1 type, and may use 2 or more types together.

  The intermediate layer resin is not particularly limited as long as it is used as a resin for forming the intermediate layer 4.

  The intermediate layer 4 may contain various additives as long as the electrophotographic characteristics of the photoreceptor 1 are not adversely affected. The additives are the same as those for the photosensitive layer 3.

[4. Photoconductor manufacturing method]
Next, an example of a method for manufacturing the photoreceptor 1 will be described with reference to FIG. The method for manufacturing the photoreceptor 1 includes, for example, a photosensitive layer forming step. In the photosensitive layer forming step, the photosensitive layer coating solution is applied onto the conductive substrate 2, and the solvent contained in the applied photosensitive layer coating solution is removed to form the photosensitive layer 3. The photosensitive layer coating solution contains at least a charge generator, a triarylamine derivative (1), a binder resin, and a solvent. The coating solution for the photosensitive layer is prepared by dissolving or dispersing the charge generator, the triarylamine derivative (1), and the binder resin in a solvent. You may add an electron transport agent and various additives to the coating liquid for photosensitive layers as needed.

  The solvent contained in the photosensitive layer coating solution is not particularly limited as long as each component contained in the photosensitive layer coating solution can be dissolved or dispersed. Examples of the solvent include alcohols (for example, methanol, ethanol, isopropanol, or butanol), aliphatic hydrocarbons (for example, n-hexane, octane, or cyclohexane), aromatic hydrocarbons (for example, benzene, toluene, Or xylene), halogenated hydrocarbons (eg, dichloromethane, dichloroethane, carbon tetrachloride, or chlorobenzene), ethers (eg, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, or diethylene glycol dimethyl ether), ketones (eg, acetone) , Methyl ethyl ketone, or cyclohexanone), esters (for example, ethyl acetate or methyl acetate), dimethylformaldehyde, N, N-dimethylformamide (D F), or dimethyl sulfoxide. These solvents may be used alone or in combination of two or more. Of these solvents, solvents other than halogenated hydrocarbons are preferred in order to improve the workability during production of the photoreceptor 1.

  The photosensitive layer coating solution is prepared by mixing each component and dispersing in a solvent. For mixing or dispersing, for example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser is used.

  The photosensitive layer coating solution may contain, for example, a surfactant or a leveling agent in order to improve the dispersibility of each component or the surface smoothness of each formed layer.

  The method for applying the photosensitive layer coating solution is not particularly limited as long as it is a method that can uniformly apply the photosensitive layer coating solution onto the conductive substrate 2. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

  The method for removing the solvent contained in the photosensitive layer coating solution is not particularly limited as long as it is a method capable of evaporating the solvent in the photosensitive layer coating solution. Examples of the method for removing the solvent include heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of performing heat treatment (hot air drying) using a high-temperature dryer or a vacuum dryer can be mentioned. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower and a time of 3 minutes or longer and 120 minutes or shorter.

  The method for manufacturing the photoreceptor 1 may further include a step of forming the intermediate layer 4 and / or a step of forming the protective layer 5 as necessary. In the step of forming the intermediate layer 4 and the step of forming the protective layer 5, a known method is appropriately selected.

  For example, the photoreceptor 1 is used as an image carrier in the image forming apparatus 6 including the charging unit 27 that contacts the image carrier and applies a DC voltage to the image carrier. The image forming apparatus 6 including the charging unit 27 that contacts the image carrier and applies a DC voltage to the image carrier will be described later in the second embodiment.

  Heretofore, the photoreceptor 1 according to the first embodiment has been described with reference to FIG. According to the photoreceptor 1 according to the first embodiment, the surface potential during charging can be stably maintained.

[Second Embodiment: Image Forming Apparatus]
The second embodiment relates to the image forming apparatus 6. Hereinafter, the image forming apparatus 6 according to the present embodiment will be described with reference to FIGS. 2 and 3.

  The image forming apparatus 6 includes a photoreceptor 1 as an image carrier. As described above, the photoreceptor 1 can stably maintain the surface potential during charging. If the surface potential of the photoreceptor 1 during charging is stably maintained, drum scratches and toner filming are less likely to occur on the surface of the photoreceptor 1. Therefore, according to the image forming apparatus 6 including the photoreceptor 1, it is possible to suppress the occurrence of image defects due to drum scratches and toner filming.

  Hereinafter, a case where the image forming apparatus 6 adopts the intermediate transfer method will be described as an example with reference to FIG. The case where the image forming apparatus 6 employs the direct transfer method will be described later. FIG. 2 is a schematic diagram illustrating a configuration of one aspect of the image forming apparatus 6.

  The image forming apparatus 6 includes a photoreceptor 1 as an image carrier, a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit. The photoreceptor 1 is the photoreceptor 1 described in the first embodiment. The charging unit 27 charges the surface of the photoreceptor 1. The charging polarity of the charging unit 27 is positive. The exposure unit 28 exposes the charged surface of the photoconductor 1 to form an electrostatic latent image on the surface of the photoconductor 1. The developing unit 29 develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the photoreceptor 1 to the transfer target. When the image forming apparatus 6 adopts the intermediate transfer method, the transfer unit corresponds to the primary transfer roller 33 and the secondary transfer roller 21. The transfer target corresponds to the intermediate transfer belt 20 and a recording medium (for example, paper P).

  The image forming apparatus 6 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 6 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. The image forming apparatus 6 may be a tandem color image forming apparatus in order to form toner images of the respective colors using different color toners.

  Hereinafter, the image forming apparatus 6 will be described by taking a tandem color image forming apparatus as an example. The image forming apparatus 6 includes a plurality of photoreceptors 1 arranged in parallel in a predetermined direction and a plurality of developing units 29. Each of the plurality of developing units 29 is disposed to face the photoreceptor 1. Each of the plurality of developing units 29 includes a developing roller. The developing roller carries and conveys toner and supplies the toner to the surface of the corresponding photoreceptor 1.

  As shown in FIG. 2, the image forming apparatus 6 further includes a box-shaped device housing 7. In the device housing 7, a paper feeding unit 8, an image forming unit 9, and a fixing unit 10 are provided. The paper feed unit 8 feeds the paper P. The image forming unit 9 transfers the toner image based on the image data to the paper P while conveying the paper P fed from the paper feeding unit 8. The fixing unit 10 fixes the unfixed toner image transferred on the paper P by the image forming unit 9 to the paper P. Further, a paper discharge unit 11 is provided on the upper surface of the device housing 7. The paper discharge unit 11 discharges the paper P fixed by the fixing unit 10.

  The paper supply unit 8 includes a paper supply cassette 12, a first pickup roller 13, paper supply rollers 14, 15 and 16, and a registration roller pair 17. The paper feed cassette 12 is provided so as to be detachable from the device housing 7. Various sizes of paper P are stored in the paper feed cassette 12. The first pickup roller 13 is provided at the upper left position of the paper feed cassette 12. The first pickup roller 13 takes out the sheets P stored in the sheet feeding cassette 12 one by one. The paper feed rollers 14, 15 and 16 convey the paper P taken out by the first pickup roller 13. The registration roller pair 17 temporarily supplies the paper P conveyed by the paper feed rollers 14, 15, and 16 to the image forming unit 9 at a predetermined timing.

  The paper feed unit 8 further includes a manual feed tray (not shown) and a second pickup roller 18. The manual feed tray is attached to the left side surface of the device housing 7. The second pickup roller 18 takes out the paper P placed on the manual feed tray. The paper P taken out by the second pickup roller 18 is conveyed by the paper feed rollers 14, 15 and 16, and is supplied to the image forming unit 9 by the registration roller pair 17 at a predetermined timing.

  The image forming unit 9 includes an image forming unit 19, an intermediate transfer belt 20, and a secondary transfer roller 21. A toner image is primarily transferred onto the intermediate transfer belt 20 by the image forming unit 19 on the surface of the intermediate transfer belt 20 (contact surface with the primary transfer roller 33). The toner image to be primarily transferred is formed based on image data transmitted from a host device such as a computer. The secondary transfer roller 21 secondarily transfers the toner image on the intermediate transfer belt 20 onto the paper P fed from the paper feed cassette 12.

  The image forming unit 19 includes a yellow toner supply unit 25 and a magenta toner supply from the upstream side (right side in FIG. 2) to the downstream side in the rotation direction of the intermediate transfer belt 20 with respect to the yellow toner supply unit 25 as a reference. A unit 24, a cyan toner supply unit 23, and a black toner supply unit 22 are sequentially arranged. In the units 22, 23, 24, and 25, the photoreceptor 1 is disposed at the center position of each unit. The photoreceptor 1 is disposed so as to be rotatable in the direction of an arrow (clockwise). The units 22, 23, 24, and 25 may be process cartridges described later that are detachable from the main body of the image forming apparatus 6.

  Around each photoconductor 1, a charging unit 27, an exposure unit 28, and a developing unit 29 are sequentially arranged from the upstream side in the rotation direction of each photoconductor 1 with respect to the charging unit 27.

  A static eliminator (not shown) and a cleaning device (not shown) may be provided upstream of the charging unit 27 in the rotation direction of the photoreceptor 1. The static eliminator neutralizes the peripheral surface of the photoreceptor 1 after the primary transfer of the toner image to the intermediate transfer belt 20 is completed. The peripheral surface of the photoreceptor 1 cleaned and discharged by the cleaning device and the charge eliminator is sent to the charging unit 27 and newly charged. When the image forming apparatus 6 includes a cleaning device and / or a static eliminator, the charging unit 27, the exposure unit 28, the developing unit 29, and the primary transfer roller 33 with respect to the charging unit 27 from the upstream side in the rotation direction of each photoconductor 1. , Cleaning device, and static eliminator.

  As already described, the charging unit 27 charges the surface of the photoreceptor 1. Specifically, the charging unit 27 uniformly charges the peripheral surface of the photoreceptor 1 rotated in the direction of the arrow to positive polarity. The charging unit 27 may be a non-contact method or a contact method. The non-contact charging unit 27 applies a voltage to the photosensitive member 1 without contacting the photosensitive member 1. Examples of the non-contact charging unit 27 include a corona discharge type charging device, and more specifically, a corotron charger or a scorotron charger. The contact-type charging unit 27 contacts the photoconductor 1 and applies a voltage to the photoconductor 1. Examples of the contact-type charging unit 27 include a contact (proximity) discharge type charger, and more specifically, a charging roller or a charging brush.

  Examples of the charging roller include a charging roller that rotates following the rotation of the photoconductor 1 while in contact with the photoconductor 1. For example, at least a surface portion of the charging roller is formed of a resin. Specifically, the charging roller includes a core metal that is rotatably supported, a resin layer formed on the core metal, and a voltage application unit that applies a voltage to the core metal. The charging unit 27 including such a charging roller charges the surface of the photoreceptor 1 that is in contact with the resin through the resin layer when the voltage application unit applies a voltage to the cored bar.

  The resin that forms the resin layer of the charging roller is not particularly limited as long as the surface (peripheral surface) of the photoreceptor 1 can be charged. Specific examples of the resin forming the resin layer include a silicone resin, a urethane resin, and a silicone-modified resin. The resin layer may contain an inorganic filler.

  In the image forming apparatus 6 including the contact-type charging unit 27, the surface of the photoconductor 1 is converted into ions having high kinetic energy generated by the gap discharge as compared with the image forming apparatus 6 including the non-contact type charging unit 27. May be exposed. For this reason, in the image forming apparatus 6 including the contact-type charging unit 27, the surface potential of the photoconductor usually tends to be difficult to stabilize. However, since the image forming apparatus 6 of the present embodiment includes the photoreceptor 1 according to the first embodiment, even when the image forming apparatus 6 includes the contact-type charging unit 27, the photoreceptor 1 at the time of charging. Can be stably maintained.

  Further, it is considered that the discharge of active gas (for example, ozone or nitrogen oxide) generated from the charging unit 27 can be suppressed by including the contact-type charging unit 27 in the image forming apparatus 6. As a result, it is considered that the deterioration of the photosensitive layer 3 due to the active gas is suppressed and the design considering the office environment can be achieved.

  The voltage applied by the charging unit 27 is not particularly limited. Examples of the voltage applied by the charging unit 27 include an AC voltage, a superimposed voltage obtained by superimposing the AC voltage on the DC voltage, or a DC voltage. Especially, it is preferable that the charging unit 27 applies only a DC voltage. The charging unit 27 that applies only a DC voltage has the following advantages compared to the charging unit 27 that applies an AC voltage or the charging unit 27 that applies a superimposed voltage obtained by superimposing an AC voltage on a DC voltage. When the charging unit 27 applies only a DC voltage, since the voltage value applied to the photoconductor 1 is constant, the surface of the photoconductor 1 is easily charged uniformly to a constant potential. Further, when the charging unit 27 applies only a DC voltage, the wear amount of the photosensitive layer 3 tends to decrease. As a result, a suitable image can be formed.

  The voltage applied to the photosensitive member 1 by the charging unit 27 is preferably 1000 V or more and 2000 V or less, more preferably 1200 V or more and 1800 V or less, and particularly preferably 1400 V or more and 1600 V or less.

  Examples of the exposure unit 28 include an exposure device, and more specifically, a laser scanning unit. The exposure unit 28 exposes the charged surface of the photoconductor 1 to form an electrostatic latent image on the surface of the photoconductor 1. Specifically, the exposure unit 28 irradiates the circumferential surface of the photoreceptor 1 uniformly charged by the charging unit 27 with laser light based on image data input from a host device such as a personal computer. Thereby, an electrostatic latent image based on the image data is formed on the peripheral surface of the photoreceptor 1.

  The developing unit 29 develops the electrostatic latent image as a toner image. Specifically, the developing unit 29 supplies toner to the peripheral surface of the photoreceptor 1 on which the electrostatic latent image is formed, and forms a toner image based on the image data. An example of the developing unit 29 is a developing device.

  The transfer unit (corresponding to the primary transfer roller 33 and the secondary transfer roller 21) transfers the toner image formed on the surface of the photoreceptor 1 to the transfer target (corresponding to the intermediate transfer belt 20 and the paper P). The intermediate transfer belt 20 is an endless belt rotating body. The intermediate transfer belt 20 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of primary transfer rollers 33. The intermediate transfer belt 20 is disposed so that the peripheral surfaces of the plurality of photosensitive members 1 are in contact with the surface (contact surface) of the intermediate transfer belt 20.

  Further, the intermediate transfer belt 20 is pressed against the photoconductor 1 by a primary transfer roller 33 disposed to face each photoconductor 1. In the pressed state, the intermediate transfer belt 20 rotates endlessly in the arrow (counterclockwise) direction by the plurality of drive rollers 30. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 20 endlessly. The driven roller 31, the backup roller 32, and the plurality of primary transfer rollers 33 are rotatably provided. The driven roller 31, the backup roller 32, and the primary transfer roller 33 rotate following the endless rotation of the intermediate transfer belt 20 by the driving roller 30. The driven roller 31, the backup roller 32, and the primary transfer roller 33 are driven to rotate via the intermediate transfer belt 20 according to the main rotation of the driving roller 30 and support the intermediate transfer belt 20.

  The primary transfer roller 33 applies a primary transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the intermediate transfer belt 20. As a result, the toner image formed on each photoconductor 1 is sequentially transferred (primary transfer) to the intermediate transfer belt 20 that circulates between each photoconductor 1 and the primary transfer roller 33. Note that the charging polarity of the toner is positive.

  The secondary transfer roller 21 applies a secondary transfer bias (specifically, a bias having a polarity opposite to the toner charging polarity) to the paper P. As a result, the toner image primarily transferred onto the intermediate transfer belt 20 is transferred onto the paper P between the secondary transfer roller 21 and the backup roller 32. As a result, an unfixed toner image is transferred onto the paper P.

  The fixing unit 10 fixes the unfixed toner image transferred to the paper P by the image forming unit 9. The fixing unit 10 includes a heating roller 34 and a pressure roller 35. The heating roller 34 is heated by an energized heating element. The pressure roller 35 is disposed to face the heating roller 34, and the circumferential surface of the pressure roller 35 is pressed against the circumferential surface of the heating roller 34.

  The transfer image transferred to the paper P by the secondary transfer roller 21 in the image forming unit 9 is fixed to the paper P by a fixing process by heating when the paper P passes between the heating roller 34 and the pressure roller 35. The Then, the paper P subjected to the fixing process is discharged to the paper discharge unit 11. In addition, a plurality of transport rollers 36 are disposed at appropriate positions between the fixing unit 10 and the paper discharge unit 11.

  The paper discharge unit 11 is formed by recessing the top of the device housing 7. A paper discharge tray 37 that receives the discharged paper P is provided at the bottom of the recessed portion. The image forming apparatus 6 according to one aspect of the present embodiment has been described above with reference to FIG.

  Hereinafter, an image forming apparatus 6 according to another aspect of the present embodiment will be described with reference to FIG. FIG. 3 is a schematic diagram illustrating a configuration of another aspect of the image forming apparatus 6 according to the present embodiment. The image forming apparatus 6 shown in FIG. 3 employs a direct transfer method. In the image forming apparatus 6 illustrated in FIG. 3, the transfer unit corresponds to the transfer roller 41. The transfer target corresponds to a recording medium (for example, paper P). In FIG. 3, the same reference numerals are used for the elements corresponding to those in FIG.

  As shown in FIG. 3, the transfer belt 40 is an endless belt-like rotating body. The transfer belt 40 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of transfer rollers 41. The transfer belt 40 is arranged so that the circumferential surface of each photoconductor 1 abuts on the surface (contact surface) of the transfer belt 40. The transfer belt 40 is pressed against the photoconductor 1 by each transfer roller 41 disposed to face each photoconductor 1. In the pressed state, the transfer belt 40 is rotated endlessly by the plurality of rollers 30, 31, 32, and 41. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the transfer belt 40 endlessly. The driven roller 31, the backup roller 32, and the transfer roller 41 are rotatably provided. With the endless rotation of the transfer belt 40 by the driving roller 30, the driven roller 31, the backup roller 32, and the plurality of transfer rollers 41 are driven to rotate. These rollers 31, 32 and 41 are driven to rotate and support the transfer belt 40. The paper P supplied from the registration roller pair 17 is sucked onto the transfer belt 40 by the suction roller 42. The sheet P adsorbed on the transfer belt 40 passes between each photoconductor 1 and the corresponding transfer roller 41 as the transfer belt 40 rotates.

  The transfer roller 41 transfers the toner image from the photoreceptor 1 to the paper P. The photosensitive member 1 is in contact with the paper P when the toner image is transferred. Specifically, each transfer roller 41 applies a transfer bias (specifically, a bias having a polarity opposite to the toner charging polarity) to the paper P adsorbed on the transfer belt 40. As a result, the toner image formed on the photoconductor 1 is transferred onto the paper P between each photoconductor 1 and the corresponding transfer roller 41. The transfer belt 40 circulates in the arrow (clockwise) direction by driving the driving roller 30. Accordingly, the paper P sucked on the transfer belt 40 sequentially passes between each photoconductor 1 and the corresponding transfer roller 41. When passing, the toner images of the corresponding colors formed on the respective photoreceptors 1 are sequentially transferred onto the paper P in the overcoated state. Thereafter, each photoconductor 1 further rotates and proceeds to the next process. The image forming apparatus that employs the direct transfer method according to another aspect of the present embodiment has been described above with reference to FIG.

  As described with reference to FIGS. 2 and 3, the image forming apparatus 6 according to the second embodiment includes the photoconductor 1 according to the first embodiment. The photoreceptor 1 can stably maintain the surface potential during charging. Therefore, by providing such a photoreceptor 1, the image forming apparatus 6 according to the second embodiment can suppress the occurrence of image defects.

[Third embodiment: Process cartridge]
The third embodiment relates to a process cartridge. The process cartridge according to the present embodiment includes the photoreceptor 1 according to the first embodiment as an image carrier. The photoreceptor 1 according to the first embodiment can stably maintain the surface potential during charging. Therefore, when the process cartridge according to the present embodiment is provided in the image forming apparatus 6, it is considered that the occurrence of image defects can be suppressed.

  The process cartridge includes, for example, the photoreceptor 1 according to the first embodiment that is unitized. The process cartridge may be designed to be detachable from the image forming apparatus 6 according to the second embodiment. For example, in addition to the photoreceptor 1, the process cartridge includes at least one selected from the group consisting of the charging unit 27, the exposure unit 28, the developing unit 29, the transfer unit, the cleaning device, and the static eliminator described in the second embodiment. A configuration in which one unit is formed is adopted.

  The process cartridge according to the third embodiment has been described above. The process cartridge according to the third embodiment can suppress the occurrence of image defects. Furthermore, since such a process cartridge is easy to handle, when the sensitivity characteristics of the photoconductor 1 deteriorate, the process cartridge including the photoconductor 1 can be easily and quickly replaced.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the scope of the examples.

<1. Photosensitive Material>
The following charge generator, hole transport agent, electron transport agent, and binder resin were prepared as materials for forming the photosensitive layer of the photoreceptor.

(Charge generator)
Charge generators (CG-1a) and (CG-2a) were prepared as charge generators. The charge generating agent (CG-1a) was a metal-free phthalocyanine represented by the chemical formula (CG-1) described in the embodiment. The crystal structure of the charge generating agent (CG-1a) was X-type.

  The charge generating agent (CG-2a) was titanyl phthalocyanine represented by the chemical formula (CG-2) described in the embodiment. The crystal structure of the charge generating agent (CG-2a) was Y-type. Furthermore, the charge generating agent CG-2a had thermal characteristics (C) in the DSC spectrum. Specifically, the charge generating agent (CG-2a) does not have a peak in the range of 50 ° C. or higher and 270 ° C. or lower in addition to the peak accompanying vaporization of adsorbed water in the thermal characteristics in the DSC spectrum. It had one peak in the range.

(Hole transport agent)
As the hole transport agent, the chemical formulas (HT-1), (HT-6), (HT-10), (HT-11), (HT-12), (HT-15), (HT A triphenylamine derivative represented by -17) was prepared. In addition, compounds represented by chemical formulas (HT-21) to (HT-23) were also prepared.

(Electron transfer agent)
As electron transport agents, the compounds represented by the chemical formulas (ET-1) to (ET-4) described in the embodiment were prepared.

(Binder resin)
Binder resins (Resine-1a), (Resine-2a), (Resine-3a), (Resine-4a), (Resine-5a), (Resine-6a) and (Resine-7a) were prepared as binder resins. .

  The binder resins (Resine-1a), (Resine-2a), (Resine-3a), (Resine-4a), (Resine-5a), and (Resine-6a) are each represented by the chemical formula (Resine). -1), (Resine-2), (Resine-3), (Resine-4), (Resine-5), and (Resine-6). The binder resins (Resine-1a), (Resine-2a), (Resine-3a), (Resine-4a), (Resine-5a), and (Resine-6a) have a viscosity average molecular weight of 50, 000.

  The binder resin (Resine-7a) was a resin represented by the chemical formula (Resine-7). Moreover, the viscosity average molecular weight of binder resin (Resine-7a) was 50,000. In the chemical formula (Resine-7), the suffix of the repeating unit indicates the molar ratio of the repeating unit.

<2. Manufacture of photoconductor>
Photoconductors (A-1) to (A-25) and (B-1) to (B-19) were produced using materials for forming the photosensitive layer of the prepared photoconductor.

(Manufacture of photoconductor (A-1))
In the container, represented by 5 parts by mass of a charge generating agent (CG-1a), 50 parts by mass of a triphenylamine derivative (HT-1) as a hole transporting agent, and a chemical formula (ET-1) as an electron transporting agent. 35 parts by mass of a compound to be prepared, 100 parts by mass of a binder resin (Resine-1a), and 750 parts by mass of tetrahydrofuran as a solvent were added. The contents of the container were mixed and dispersed for 50 hours using a ball mill to prepare a photosensitive layer coating solution.

  Using a dip coating method, a coating solution for a photosensitive layer was applied on a conductive substrate to form a coating film on the conductive substrate. Then, it was made to dry for 40 minutes at 100 degreeC, and tetrahydrofuran was removed from the coating film. As a result, a photoreceptor (A-1) having a 35 μm-thick photosensitive layer on a conductive substrate was obtained.

(Production of photoconductors (A-2) to (A-25) and (B-1) to (B-19))
Except for the following changes, the photoconductors (A-2) to (A-25) and (B-1) to (B-19) were prepared in the same manner as in the production of the photoconductor (A-1). Manufactured. The charge generation agent (CG-1a) used for the production of the photoreceptor (A-1), the triphenylamine derivative (HT-1) as a hole transport agent, and the chemical formula (ET-1) as an electron transport agent In place of the compound and the binder resin (Resine-1a), the types of charge generating agents (CGM), hole transporting agents (HTM), electron transporting agents (ETM) shown in Table 1 and Table 2, respectively. A binder resin was used.

<3. Evaluation of surface potential stability during charging>
Each of the photoreceptors (A-1) to (A-25) and (B-1) to (B-19) was evaluated for the stability of the surface potential during charging.

  The photoreceptor was mounted on an image forming apparatus (“FS-C5250DN” manufactured by Kyocera Document Solutions Inc.). This image forming apparatus includes a contact-type charging roller that applies a DC voltage as a charging unit. As the charging unit, a charging roller that charges the surface of the photosensitive member by bringing a charging sleeve into contact with the photosensitive member was used. The chargeable sleeve is formed of a chargeable rubber in which conductive carbon is dispersed in epichlorohydrin resin. The charging voltage of the charging unit was set to +1.4 kV.

  The charging voltage was continuously applied to the photoreceptor using the charging unit for 30 minutes. During the application of the charging voltage for 30 minutes to the photoconductor, the surface potential of the photoconductor was continuously measured. The surface potential of the photoconductor immediately after starting to apply the charging voltage for 30 minutes to the photoconductor was + 570 ± 30V. The maximum value of the surface potential of the photoconductor measured by applying a charging voltage for 30 minutes to the photoconductor was V0 (unit: + V), and the minimum value was V1 (unit: + V). The measurement environment was a temperature of 23 ° C. and a humidity of 50% RH.

  A difference (ΔV0) in surface potential was calculated from the measured maximum value (V0) and minimum value (V1) of the surface potential according to the equation “ΔV0 = V1−V0”. Table 1 and Table 2 show the difference (ΔV0) in the surface potential of the photoreceptor. The smaller the absolute value of the surface potential difference (ΔV0) of the photoconductor, the more stable the surface potential of the photoconductor during charging.

<4. Image evaluation>
The photoreceptor was mounted on an image forming apparatus (“FS-C5250DN” manufactured by Kyocera Document Solutions Inc.). This image forming apparatus includes a contact-type charging roller that applies a DC voltage as a charging unit. As the charging unit, a charging roller that charges the surface of the photosensitive member by bringing a charging sleeve into contact with the photosensitive member was used. The chargeable sleeve is formed of a chargeable rubber in which conductive carbon is dispersed in epichlorohydrin resin. The surface potential of the photosensitive member was set to 570 ± 10 V by adjusting the charging voltage applied to the photosensitive member by the charging unit.

  The image A was continuously printed on 50,000 sheets using an image forming apparatus. Image A was a character image with a printing rate of 5%. Printing of image A on 50,000 sheets of paper was performed in a normal temperature and humidity environment (temperature 23 ° C. and humidity 50% RH). Subsequently, the image B was printed on a sheet of paper using an image forming apparatus under a normal temperature and humidity environment (temperature 23 ° C. and humidity 50% RH). Image B included a halftone portion and a blank portion. The paper on which the image B was formed was used as a sample for evaluation under a normal temperature and humidity environment. Subsequently, using the image forming apparatus, the image B was printed on one sheet in a low temperature and low humidity environment (temperature 10 ° C. and humidity 20% RH). The paper on which the image B was formed was used as an evaluation sample in a low temperature and low humidity environment. In addition, “Kyocera Document Solutions brand paper VM-A4 (A4 size)” sold by Kyocera Document Solutions Inc. was used as the paper.

  The obtained samples for evaluation under a normal temperature and normal humidity environment and a low temperature and low humidity environment were each visually observed. As a result, the presence or absence of image defects due to drum scratches and the presence or absence of image defects due to toner filming were confirmed. Note that as the surface potential of the photosensitive member at the time of charging becomes less stable, drum scratches and toner filming are more likely to occur on the surface of the photosensitive member. When drum scratches occur on the surface of the photoreceptor, black streaks are likely to appear on the blank paper portion and the halftone portion of the evaluation sample. When toner filming occurs on the surface of the photoreceptor, black streaks tend to appear in the halftone portion of the evaluation sample.

  Next, the photoreceptor was taken out from the image forming apparatus. The surface of the removed photoconductor was observed at a magnification of 50 using a stereomicroscope. Thus, the presence or absence of drum scratches on the surface of the photoreceptor and the presence or absence of toner filming were observed.

Image evaluation was performed based on the following evaluation criteria from the observation results of the sample for evaluation under the normal temperature and normal humidity environment and the low temperature and low humidity environment and the observation result of the surface of the photoreceptor. The results of image evaluation are shown in Tables 1 and 2.
(Evaluation criteria for image evaluation)
A (particularly good): Drum scratches and toner filming did not occur on the surface of the photoreceptor. Furthermore, no image defects due to drum scratches and toner filming were observed.
○ (Good): Drum scratches or toner filming was observed on the surface of the photoreceptor. However, image defects due to drum scratches and toner filming were not observed.
Δ (defect): Drum scratches or toner filming was observed on the surface of the photoreceptor. Image defects due to drum scratches or toner filming were observed in a low temperature and low humidity environment. Image defects due to drum scratches or toner filming were not observed under normal temperature and humidity conditions.
X (particularly poor): Drum scratches or toner filming was observed on the surface of the photoreceptor. Image defects due to drum scratches or toner filming were observed both in a low temperature and low humidity environment and in a normal temperature and normal humidity environment.

In Table 1 and Table 2, CGM, HTM, and ETM represent a charge generating agent, a hole transport agent, and an electron transport agent, respectively.

  As shown in Tables 1 and 2, in the photoreceptors (A-1) to (A-25), the absolute value of the difference (ΔV0) in the surface potential of the photoreceptor at the time of charging was small. From this, it was shown that the surface potential of the photoreceptor at the time of charging was stably maintained. Further, the image formed by the image forming apparatus including the photoconductors (A-1) to (A-25) was excellent in image evaluation results. From this, it was shown that in the image forming apparatus including the photoconductors (A-1) to (A-25), occurrence of image defects due to drum scratches and toner filming was suppressed.

  The photoreceptors (B-1) to (B-3) and (B-13) did not contain the triphenylamine derivative (I) and the polycarbonate resin having a fluoro group. The photoreceptors (B-4) to (B-6) and (B-14) to (B-16) did not contain a polycarbonate resin having a fluoro group. The photoreceptors (B-7) to (B-12) and (B-17) to (B-19) did not contain the triphenylamine derivative (I). Therefore, in the photoconductors (B-1) to (B-19), the absolute value of the difference (ΔV0) in the surface potential of the photoconductor during charging was large. From this, it was shown that in the photoreceptors (B-1) to (B-19), it is difficult to stably maintain the surface potential of the photoreceptor at the time of charging. Further, in the image formed by the image forming apparatus including the photoconductors (B-1) to (B-19), the result of the image evaluation was inferior. From this, it was shown that in the image forming apparatus provided with the photoconductors (B-1) to (B-19), image defects due to drum scratches and toner filming occurred.

  From the above, it is shown that the surface potential of the photosensitive member when charged is stably maintained in the photosensitive member according to the present invention, and the image forming apparatus including such a photosensitive member suppresses the occurrence of image defects. It was.

  The photoreceptor according to the present invention can be suitably used as an electrophotographic photoreceptor.

1 Positively charged single layer type electrophotographic photosensitive member (image carrier)
2 Conductive substrate 3 Photosensitive layer 4 Intermediate layer 5 Protective layer 6 Image forming apparatus 7 Device housing 8 Paper feed unit 9 Image forming unit 10 Fixing unit 11 Paper discharge unit 12 Paper feed cassette 13 First pickup roller 14 Paper feed roller 15 Paper roller 17 Registration roller pair 18 Second pickup roller 19 Image forming unit 20 Intermediate transfer belt 21 Secondary transfer roller 22 Black toner supply unit 23 Cyan toner supply unit 24 Magenta toner supply unit 25 Yellow toner supply unit 27 Charging Section 28 Exposure section 29 Developing section 30 Drive roller 31 Driven roller 32 Backup roller 33 Primary transfer roller 34 Heating roller 35 Pressure roller 36 Transport roller 37 Paper discharge tray 40 Transfer belt 41 Transfer roller 42 Adsorption roller P Paper

Claims (10)

A positively charged single layer type electrophotographic photosensitive member provided with a photosensitive layer,
The photosensitive layer contains at least a charge generator, a hole transport agent, and a binder resin,
The hole transport agent contains a triphenylamine derivative represented by the following general formula (I),
A positively charged single layer type electrophotographic photosensitive member containing a polycarbonate resin having a fluoro group as the binder resin.

(In the general formula (I), m1 and m2 each represent 2, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ each represent a hydrogen atom, and R ₁ represents a carbon atom. Represents an alkoxy group having a number of 1 or more and 4 or less, and R ₁ is present in an ortho position with respect to a nitrogen atom to which a phenyl group having R ₁ is bonded, or
In the general formula (I), m1 and m2 each represent 3, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ each represent a hydrogen atom, and R ₁ represents the number of carbon atoms Represents an alkyl group of 1 or more and 4 or less, and R ₁ is present in the para position with respect to the nitrogen atom to which the phenyl group having R ₁ is bonded . ) The positively charged single layer type electrophotographic photoreceptor according to claim 1, wherein the polycarbonate resin is represented by the following general formula (II).

(In the general formula (II),
R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms which may have a substituent,
R ₂₅ and R ₂₆ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms which may have a substituent, or 6 to 14 carbon atoms which may have a substituent. Or R ₂₅ and R ₂₆ may be bonded to form a cycloalkylidene group having 3 to 8 carbon atoms which may have a substituent,
R ₂₇ , R ₂₈ , R ₂₉ and R ₃₀ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms which may have a substituent,
Rt represents a terminal group,
n1 + n2 = 1.0, 0.0 <n1 ≦ 1.0,
One or both of the following (a) and (b) are satisfied.
(A) One or more of R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ , R ₂₉ and R ₃₀ have a fluoro group as the substituent.
(B) The said terminal group has a fluoro group. ) The terminal group has a fluoro group;
The positively charged single layer type electrophotographic photosensitive member according to claim 2 , wherein the terminal group is represented by the following general formula (III) or (IV).

(In the general formula (III), R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 to 20 carbon atoms. The following alkoxy groups, an alkoxycarbonyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 14 carbon atoms,
One or more of R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ are the alkyl group having 1 to 20 carbon atoms, the alkoxy group having 1 to 20 carbon atoms, and the carbon number. Represents an alkoxycarbonyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 14 carbon atoms,
The alkyl group having 1 to 20 carbon atoms, the alkoxy group having 1 to 20 carbon atoms, the alkoxycarbonyl group having 1 to 20 carbon atoms, and the aryl group having 6 to 14 carbon atoms, Each having one or more substituents selected from the group consisting of an alkyl group having 1 to 20 carbon atoms having a fluoro group, an alkoxy group having 1 to 20 carbon atoms having a fluoro group, and a fluoro group. Have. )

(In the general formula (IV),
R ₄₁ represents a single bond or —CO—.
R ₄₂ and R ₄₃ each independently represents a hydrogen atom, a fluoromethyl group, a difluoromethyl group, or a trifluoromethyl group,
R ₄₄ represents a hydrogen atom, fluoro group, fluoromethyl group, difluoromethyl group, trifluoromethyl group, or a -OR ₄₅ -OR _46,
When R ₄₂ and R ₄₃ are each hydrogen atom, R ₄₄ represents fluoro group, fluoromethyl group, difluoromethyl group, trifluoromethyl group, or a -OR ₄₅ -OR _46,
When R ₄₄ is a hydrogen atom, at least one of R ₄₂ and R ₄₃ represents a fluoromethyl group, a difluoromethyl group, or a trifluoromethyl group,
R ₄₅ represents a —CF ₂ —CF ₂ — group ,
R ₄₆ represents an alkyl group having 1 to 20 carbon atoms having a fluoro group,
P1 represents an integer of 0 or more and 12 or less. ) In the general formula (III),
R ₃₁ , R ₃₂ , R ₃₄ and R ₃₅ each represent a hydrogen atom;
R ₃₃ represents an alkyl group having 1 to 20 carbon atoms, or an alkoxycarbonyl group having 1 to 20 carbon atoms,
The alkyl group having 1 to 20 carbon atoms and the alkoxycarbonyl group having 1 to 20 carbon atoms each have 3 to 41 fluoro groups,
In the general formula (IV),
R ₄₁ represents a single bond,
R ₄₂ and R ₄₃ each represent a hydrogen atom;
R ₄₄ represents -OR ₄₅ -OR ₄₆ ;
R ₄₅ represents a —CF ₂ —CF ₂ — group ,
R ₄₆ represents an alkyl group having 1 to 4 carbon atoms having 3 to 9 fluoro groups,
4. The positively charged single layer type electrophotographic photosensitive member according to claim 3 , wherein P1 represents an integer of 1 to 5. The photosensitive layer further contains an electron transport agent,
The electron transport agent, the following general formula (V), (VI), (VII), or a compound represented by (VIII), positively charged single-layer according to any one of claims 1-4 Type electrophotographic photoreceptor.

(In the general formulas (V), (VI), (VII) and (VIII),
R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₈₁ , R ₈₂ , R ₈₃ and R ₈₄ each independently have a hydrogen atom or a substituent. An alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, Or a heterocyclic group which may have a substituent,
R ₇₃ may have a halogen atom, a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. It represents a good aralkyl group, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. ) In the general formulas (V), (VI), (VII), and (VIII),
R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₆₁ , R ₆₂ , R ₇₁ , R ₇₂ , R ₈₁ , R ₈₂ , R ₈₃ and R ₈₄ each independently has 1 to 6 carbon atoms. Represents an alkyl group,
The positively charged single layer type electrophotographic photosensitive member according to claim 5 , wherein R ₇₃ represents a halogen atom. In the image forming apparatus having the charging portion in contact with the image bearing member to apply a DC voltage to the image bearing member, the image is used as a carrier, positively charged according to any one of claims 1 to 6 Single layer type electrophotographic photoreceptor. A process cartridge comprising the positively charged single layer type electrophotographic photosensitive member according to any one of claims 1 to 7 . An image carrier;
A charging unit that charges the surface of the image carrier;
An exposure unit that exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier;
A developing unit for developing the electrostatic latent image as a toner image;
An image forming apparatus comprising: a transfer unit that transfers the toner image from the image carrier to a transfer target;
The charging polarity of the charging part is positive.
The image carrier is a positively charged single-layer electrophotographic photoconductor according to any one of claim 1 to 7, an image forming apparatus. The image forming apparatus according to claim 9 , wherein the charging unit is in contact with the image carrier and applies a DC voltage to the image carrier.

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