JPWO2017208700A1 - Electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Abstract

The electrophotographic photoreceptor (1) includes a conductive substrate (2) and a photosensitive layer (3). The photosensitive layer (3) is a single layer. The photosensitive layer (3) contains a charge generator, an electron transport agent, a hole transport agent and a binder resin. The binder resin includes a polycarbonate resin represented by the following general formula (1). In general formula (1), R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a substituent. Represents an optionally substituted alkoxy group having 1 to 6 carbon atoms or a phenyl group optionally having a substituent.
[Chemical 1]

Description

  The present invention relates to an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor), a process cartridge, and an image forming apparatus.

  The photoreceptor is used in an electrophotographic image forming apparatus. The photoreceptor includes a photosensitive layer. As the photoreceptor, a so-called multilayer photoreceptor or single layer photoreceptor is used. The multilayer photoreceptor includes a charge generation layer having a charge generation function and a charge transport layer having a charge transport function as a photosensitive layer. The single-layer type photoreceptor includes a single photosensitive layer having a charge generation function and a charge transport function as a photosensitive layer.

  For example, in the photoreceptor described in Patent Document 1, a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate. As a binder resin for the charge transport layer, a polymer containing a bisphenol skeleton is contained.

JP-A-4-44048

  However, with the photoreceptor described in Patent Document 1, it is difficult to suppress the occurrence of oil cracks. Further, in the photoreceptor described in Patent Document 1, suppression of filming is insufficient.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a photoconductor that can simultaneously suppress the occurrence of oil cracks and the occurrence of filming. Another object of the present invention is to provide a process cartridge and an image forming apparatus that are provided with such a photoconductor, and that can simultaneously suppress the occurrence of oil cracks and the occurrence of filming.

  The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer. The photosensitive layer contains a charge generator, an electron transport agent, a hole transport agent, and a binder resin. The binder resin includes a polycarbonate resin represented by the following general formula (1).

In the general formula (1), R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, or an alkyl having 1 to 6 carbon atoms which may have a substituent. Represents an alkoxy group having 1 to 6 carbon atoms which may have a group or a substituent, or a phenyl group which may have a substituent. X has a single bond, an alkylene group having 2 to 18 carbon atoms which may have a substituent, an alkylidene group having 1 to 18 carbon atoms which may have a substituent, and a substituent. A cycloalkylene group having 5 to 15 carbon atoms which may be substituted, a cycloalkylidene group having 5 to 15 carbon atoms which may have a substituent, -S-, -SO-, -O- or -CO- is represented. m and n each independently represent a positive number, m + n = 1.00, and 0.30 ≦ n ≦ 0.70.

  The process cartridge of the present invention includes the above-described electrophotographic photosensitive member.

  An image forming apparatus of the present invention includes the above-described electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit. The charging unit charges the surface of the electrophotographic photosensitive member. The exposure unit exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image on the surface of the electrophotographic photosensitive member. The developing unit develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the electrophotographic photosensitive member to a recording medium. When the transfer unit transfers the toner image from the electrophotographic photosensitive member to the recording medium, the electrophotographic photosensitive member is in contact with the recording medium.

  According to the photoreceptor of the present invention, it is possible to achieve both suppression of oil cracking and suppression of filming. Further, according to the process cartridge and the image forming apparatus of the present invention, by providing such a photoconductor, it is possible to achieve both suppression of oil cracking and suppression of filming.

1 is a cross-sectional view illustrating an example of a photoreceptor according to an embodiment of the present invention. 1 is a cross-sectional view illustrating an example of a photoreceptor according to an embodiment of the present invention. 1 is a cross-sectional view illustrating an example of a photoreceptor according to an embodiment of the present invention. 1 is a diagram illustrating an example of a configuration of an image forming apparatus including a photoreceptor according to an embodiment of the present invention.

  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, about the location where description overlaps, although description may be abbreviate | omitted suitably, 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. Furthermore, the reactions represented by reaction formulas (R-1) to (R-4) may be described as reactions (R-1) to (R-4), respectively.

  Hereinafter, unless otherwise specified, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an aryl group having 6 to 14 carbon atoms have the following meanings. It is.

  The halogen atom (halogen group) is, for example, a fluorine atom (fluoro group), a chlorine atom (chloro group), a bromine atom (bromo group), or an iodine atom (iodo group).

  The alkyl group having 1 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group. Or a hexyl group is mentioned.

  The alkoxy group having 1 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, pentyloxy, iso A pentyloxy group, a neopentyloxy group, or a hexyloxy group may be mentioned.

  The aryl group having 6 to 14 carbon atoms is, for example, an aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms, an aromatic condensed bicyclic hydrocarbon group having 6 to 14 carbon atoms, or the number of elementary atoms. 6 or more and 14 or less aromatic condensed tricyclic hydrocarbon group. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

<1. Photoconductor>
The photoreceptor according to this embodiment includes a conductive substrate and a photosensitive layer. Hereinafter, the structure of the photoreceptor 1 will be described with reference to FIGS. 1A to 1C. 1A to 1C are cross-sectional views illustrating an example of the photoreceptor 1 according to the present embodiment.

  As shown in FIG. 1A, the photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a single layer. The photosensitive layer 3 is a so-called single layer type photosensitive layer. The photosensitive layer 3 contains a charge generating agent, an electron transport agent, a hole transport agent, and a binder resin in one layer. The photoreceptor 1 is a so-called single layer type photoreceptor.

  As shown in FIG. 1B, the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer 4 (undercoat layer). The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. As shown in FIG. 1A, the photosensitive layer 3 may be provided directly on the conductive substrate 2, or as shown in FIG. 1B, the photosensitive layer 3 is indirectly formed on the conductive substrate 2 via the intermediate layer 4. May be provided.

  As shown in FIG. 1C, the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and a protective layer 5. The protective layer 5 is provided on the photosensitive layer 3.

  The thickness of the photosensitive layer 3 is not particularly limited as long as the function as the photosensitive layer can be sufficiently expressed. 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.

  In order to achieve both the suppression of the occurrence of oil cracks and the suppression of the occurrence of filming, the photosensitive layer 3 is preferably disposed as the outermost surface layer of the photoreceptor 1. The structure of the photoreceptor 1 has been described above with reference to FIGS. 1A to 1C. Next, the elements of the photoreceptor will be described.

<1-1. Photosensitive layer>
(Binder resin)
The photosensitive layer contains, as a binder resin, a polycarbonate resin represented by the following general formula (1) (hereinafter sometimes referred to as a polycarbonate resin (1)).

In general formula (1), R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a substituent. Represents an optionally substituted alkoxy group having 1 to 6 carbon atoms or a phenyl group optionally having a substituent. X has a single bond, an alkylene group having 2 to 18 carbon atoms which may have a substituent, an alkylidene group having 1 to 18 carbon atoms which may have a substituent, and a substituent. A cycloalkylene group having 5 to 15 carbon atoms which may be substituted, a cycloalkylidene group having 5 to 15 carbon atoms which may have a substituent, -S-, -SO-, -O- or -CO- is represented. m and n each independently represent a positive number. m + n = 1.00, and 0.30 ≦ n ≦ 0.70. That is, m and n each independently represent a positive number that satisfies the calculation formula “m + n = 1.00” and the calculation formula “0.30 ≦ n ≦ 0.70”. The sum of m and n is 1.00. n represents a positive number from 0.30 to 0.70.

The polycarbonate resin (1) includes a repeating structural unit represented by the following general formula (5) (hereinafter sometimes referred to as repeating unit (5)) and a repeating structural unit represented by the general formula (6) ( Hereinafter, it may be described as a repeating unit (6). The polycarbonate resin (1) is a copolymer of the repeating unit (5) and the repeating unit (6). Incidentally, R ¹ and R ² in the general formula (5) has the same meaning as R ¹ and R ² in each formula (1). R ^3, R ⁴ and X in the general formula (6) has the same definition as R ^3, R ⁴ and X each in the general formula (1).

  In general formula (1), m is the amount of substance (number of moles) of repeating unit (6) relative to the total amount of substance (number of moles) of repeating unit (5) and repeating unit (6) in polycarbonate resin (1). The ratio (molar fraction) of n is the ratio (molar fraction) of the substance amount (mole number) of the repeating unit (5) to the total substance amount (mole number) of the repeating unit (5) and the repeating unit (6) in the resin (1). Represent.

  The polycarbonate resin (1) has substantially only the repeating unit (5) and the repeating unit (6) as repeating units. In the present specification, the polycarbonate resin (1) having substantially only the repeating unit (5) and the repeating unit (6) as repeating units means that the amount of all repeating units contained in the polycarbonate resin (1). The ratio (molar fraction) of the total substance amount (mole number) of the substance amount (mole number) of the repeating unit (5) and the substance amount (mole number) of the repeating unit (6) to (mole number) is 0. Is greater than 97. The ratio (molar fraction) of the total number of moles of the number of moles of the repeating unit (5) and the number of moles of the repeating unit (6) to the number of moles of all repeating units contained in the polycarbonate resin (1) is 0.00. It is preferably 98 or more, and more preferably 1.00. When this ratio is 1.00, the polycarbonate resin (1) has only the repeating unit (5) and the repeating unit (6) as repeating units.

  The polycarbonate resin (1) may be a random copolymer in which the repeating unit (5) and the repeating unit (6) are randomly copolymerized. Alternatively, the polycarbonate resin (1) may be an alternating copolymer in which the repeating unit (5) and the repeating unit (6) are alternately copolymerized. Alternatively, the polycarbonate resin (1) may be a periodic copolymer in which one or more repeating units (5) and one or more repeating units (6) are periodically copolymerized. Alternatively, the polycarbonate resin (1) may be a block copolymer in which a block composed of a plurality of repeating units (5) and a block composed of a plurality of repeating units (6) are copolymerized.

  According to the photoconductor of the present embodiment, it is possible to suppress filming and oil cracks. In order to facilitate understanding, filming and oil cracks will be described. Filming is a phenomenon in which minute components adhering to the surface of the photoreceptor are solidified on the surface of the photoreceptor when an image is formed on a recording medium using an image forming apparatus provided with the photoreceptor and toner. Examples of the minute component include a toner component (specifically, toner or an external additive detached from the toner) or a non-toner component (specifically, paper powder derived from a recording medium). Oil cracking is a phenomenon in which cracking occurs on the surface of the photoreceptor when finger oil or other oil adheres to the surface of the photoreceptor (for example, the photosensitive layer). The reason why the photoconductor of this embodiment can achieve both suppression of filming and suppression of oil cracking is presumed as follows.

The polycarbonate resin (1) has a repeating unit (5) containing a “—SO ₂ —” bond. By having the repeating unit (5) containing the “—SO ₂ —” bond in the polycarbonate resin (1), the Vickers hardness of the photosensitive layer, particularly the Vickers hardness of the photosensitive layer in a high temperature environment (for example, 40 ° C.) can be improved. it can. When the Vickers hardness of the photosensitive layer in a high temperature environment is improved, the contact area between the surface of the photosensitive member and the above-described minute component tends to decrease even when the temperature in the image forming apparatus provided with the photosensitive member is increased. is there. When the contact area between the surface of the photoreceptor and the minute component decreases, it becomes easier to clean (remove) the minute component from the surface of the photoreceptor. As a result, the occurrence of filming can be suppressed.

  In general formula (1), n represents a number of 0.30 or more. That is, in the polycarbonate resin (1), the ratio (molar fraction) of the number of moles of the repeating unit (5) to the total number of moles of the repeating unit (5) and the repeating unit (6) is 0.30 or more. When n in the general formula (1) is less than 0.30, filming is likely to occur. This is because, since the molar fraction of the repeating unit (5) in the polycarbonate resin (1) is small, the effect of suppressing the occurrence of filming obtained by including the repeating unit (5) is reduced.

Further, the polycarbonate resin (1) is "- SO ₂ -" in addition to the repeating unit (5) comprising coupling, "- SO ₂ -" having the repeating unit (6) containing no binding. Since the polycarbonate resin (1) has the repeating unit (6) that does not contain the “—SO ₂ —” bond, the occurrence of oil cracks can be suppressed. In general formula (1), n represents a number of 0.70 or less. That is, in the polycarbonate resin (1), the ratio (molar fraction) of the number of moles of the repeating unit (5) to the total number of moles of the repeating unit (5) and the repeating unit (6) is 0.70 or less. If n in the general formula (1) becomes larger than 0.70, oil cracks are likely to occur. While the molar fraction of the repeating unit (5) in the polycarbonate resin (1) increases, the molar fraction of the repeating unit (6) decreases. This is because the effect of suppressing the occurrence of oil cracks obtained by including the repeating unit (6) is reduced. For the reasons described above, it is considered that the photoreceptor of this embodiment containing the polycarbonate resin (1) can achieve both suppression of filming and suppression of oil cracks.

The alkyl group having 1 to 6 carbon atoms represented by R ^{1 to} R ⁴ in the general formula (1) is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. The alkyl group having 1 to 6 carbon atoms represented by R ^{1 to} R ⁴ may have a substituent. Examples of the substituent of the alkyl group having 1 to 6 carbon atoms include a halogen atom (preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group)), an alkoxy group having 1 to 6 carbon atoms, It is a phenyl group. The number of substituents of the alkyl group having 1 to 6 carbon atoms is, for example, 1 or more and 3 or less.

The alkoxy group having 1 to 6 carbon atoms represented by R ^{1 to} R ⁴ in the general formula (1) is preferably an alkoxy group having 1 to 3 carbon atoms. The alkoxy group having 1 to 6 carbon atoms represented by R ^{1 to} R ⁴ may have a substituent. Examples of the substituent of the alkoxy group having 1 to 6 carbon atoms include a halogen atom (preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group)), an alkoxy group having 1 to 6 carbon atoms, It is a phenyl group. The number of substituents of the alkoxy group having 1 to 6 carbon atoms is, for example, 1 or more and 3 or less.

The phenyl group represented by R ^{1 to} R ⁴ in the general formula (1) may have a substituent. Examples of the substituent of the phenyl group include a halogen atom (preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group)), an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 6 carbon atoms. An alkoxy group or a phenyl group. The number of substituents possessed by the phenyl group is, for example, 1 or more and 3 or less.

In general formula (1), R ^{1 to} R ⁴ preferably each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a hydrogen atom or an alkyl having 1 to 3 carbon atoms. It is more preferable to represent a group, and it is particularly preferable to represent a hydrogen atom or a methyl group. In general formula (1), it is more preferable that R ¹ and R ² each represent a hydrogen atom.

  The alkylene group having 2 to 18 carbon atoms represented by X in the general formula (1) is linear or branched and has one bond at each of the carbon atoms located at both ends of the alkyl group. It is a divalent group bonded to each other. Examples of the alkylene group having 2 to 18 carbon atoms include ethylene group, n-propylene group, methylethylene group, n-butylene group, methylpropylene group, dimethylethylene group, ethylethylene group, pentylene group, hexylene group, Examples include a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, and an octadecylene group. The alkylene group having 2 to 18 carbon atoms is preferably an alkylene group having 2 to 6 carbon atoms. The alkylene group having 2 to 18 carbon atoms represented by X may have a substituent. Examples of the substituent that the alkylene group having 2 to 18 carbon atoms represented by X is a halogen atom, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. The number of substituents of the alkylene group having 2 to 18 carbon atoms is, for example, 1 or more and 3 or less.

The alkylidene group having 1 to 18 carbon atoms represented by X in the general formula (1) is linear or branched, and is a divalent bond in which two bonds are bonded to one carbon atom. It is a group. Examples of the alkylidene group having 1 to 18 carbon atoms include a methylidene group, an ethylidene group, an n-propylidene group, a dimethylmethylidene group (= C (CH ₃ ) ₂ ), an n-butylidene group, and an ethylmethylmethylidene group. (= C (CH ₃ ) (CH ₂ CH ₃ )), 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 or octadecylidene group. The alkylidene group having 1 to 18 carbon atoms is preferably an alkylidene group having 1 to 6 carbon atoms, and is a dimethylmethylidene group (= C (CH ₃ ) ₂ ) or an ethylmethylmethylidene group (= C (CH ₃ ) (CH ₂ CH ₃ )) is more preferred. The alkylidene group having 1 to 18 carbon atoms represented by X may have a substituent. Examples of the substituent that the alkylidene group having 1 to 18 carbon atoms represented by X is a halogen atom, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. The number of substituents of the alkylidene group having 1 to 18 carbon atoms is, for example, 1 or more and 3 or less.

  The cycloalkylene group having 5 to 15 carbon atoms represented by X in the general formula (1) is a divalent group in which one bond is bonded to each of two carbon atoms among the carbon atoms forming the cycloalkane. It is the basis of. Examples of the cycloalkylene group having 5 to 15 carbon atoms include a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cycloundecylene group, a cyclododecylene group, and a cyclotridecylene group. , A cyclotetradecylene group or a cyclopentadecylene group. The cycloalkylene group having 5 to 15 carbon atoms is preferably a cycloalkylene group having 5 to 7 carbon atoms. The cycloalkylene group having 5 to 15 carbon atoms represented by X may have a substituent. Examples of the substituent of the cycloalkylene group having 5 to 15 carbon atoms represented by X are a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. is there. The number of substituents of the cycloalkylene group having 5 to 15 carbon atoms is, for example, 1 or more and 3 or less.

  The cycloalkylidene group having 5 to 15 carbon atoms represented by X in the general formula (1) is a divalent group in which two bonds are bonded to one carbon atom forming a cycloalkane. It is. Examples of the cycloalkylidene group having 5 to 15 carbon atoms include a cyclopentylidene group, a cyclohexylidene group, a cycloheptylidene group, a cyclooctylidene group, a cyclononylidene group, a cyclodecylidene group, and a cycloundecylidene group. , Cyclododecylidene group, cyclotridecylidene group, cyclotetradecylidene group, or cyclopentadecylidene group. The cycloalkylidene group having 5 to 15 carbon atoms is preferably a cycloalkylidene group having 5 to 7 carbon atoms, and more preferably a cyclohexylidene group. The cycloalkylidene group having 5 to 15 carbon atoms represented by X may have a substituent. Examples of the substituent of the cycloalkylidene group having 5 to 15 carbon atoms represented by X are a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. is there. The number of substituents of the cycloalkylidene group having 5 to 15 carbon atoms is, for example, 1 or more and 3 or less.

  X preferably represents a cycloalkylidene group having 5 to 15 carbon atoms, more preferably a cycloalkylidene group having 5 to 7 carbon atoms, and particularly preferably a cyclohexylidene group.

  n represents a number from 0.30 to 0.70. In order to further improve the oil crack resistance, n preferably represents a number of 0.30 to 0.50. That is, it is preferable that 0.30 ≦ n ≦ 0.50. In order to further improve the filming resistance, n preferably represents a number from 0.50 to 0.70. That is, it is preferable that 0.50 ≦ n ≦ 0.70.

  Preferable examples of the polycarbonate resin (1) include polycarbonate resins represented by the following general formulas (1-A) and (1-B).

_{M A} and n _A in the general formula (1-A) have the same meanings as m and n in the general formula (1), respectively. Suitable examples of m _A and n _A in general formula (1-A) are the same as the preferred examples of m and n in general formula (1), respectively. M _B and n _B in the general formula (1-B) have the same meanings as m and n in the general formula (1), respectively. Suitable examples of m _B and n _B in general formula (1-B) are the same as the preferred examples of m and n in general formula (1), respectively.

  A more preferable example of the polycarbonate resin (1) is a polycarbonate resin represented by the following chemical formula (1-1), (1-2) or (1-3) (hereinafter, the polycarbonate resin (1-1), (May be described as (1-2) and (1-3)). A suitable example of the polycarbonate resin (1) is a polycarbonate resin represented by the general formula (1-A), and a suitable example of the polycarbonate resin represented by the general formula (1-A) is a polycarbonate resin (1). -1) and (1-2). Another suitable example of the polycarbonate resin (1) is a polycarbonate resin represented by the general formula (1-B), and a suitable example of the polycarbonate resin represented by the general formula (1-B) is a polycarbonate resin. (1-3).

  The viscosity average molecular weight of the polycarbonate resin (1) is preferably 25,000 or more, and more preferably 25,000 or more and 52,500 or less. When the viscosity average molecular weight of the polycarbonate resin (1) is 25,000 or more, it is easy to improve the wear resistance of the photoreceptor. When the viscosity average molecular weight of the polycarbonate resin (1) is 52,500 or less, the polycarbonate resin (1) is easily dissolved in a solvent during the formation of the photosensitive layer, and the viscosity of the coating solution for the photosensitive layer does not become too high. As a result, it becomes easy to form a photosensitive layer.

  The photosensitive layer may contain only the polycarbonate resin (1). In addition to the polycarbonate resin (1), the photosensitive layer may further contain a binder resin other than the polycarbonate resin (1) (hereinafter sometimes referred to as other binder resin). Examples of other binder resins include thermoplastic resins, thermosetting resins, and photocurable resins. Examples of the thermoplastic resin include polycarbonate resins other than the polycarbonate resin (1), polyarylate resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic acid polymers, styrene- Acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin Polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyester resin or polyether resin. Examples of thermosetting resins are silicone resins, epoxy resins, phenol resins, urea resins or melamine resins. Examples of the photocurable resin are epoxy acrylate (acrylic acid adduct of epoxy compound) or urethane-acrylate (acrylic acid adduct of urethane compound). One of these binder resins may be used alone, or two or more thereof may be used in combination.

  The content of the polycarbonate resin (1) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass with respect to the total mass of the binder resin. The total mass of the binder resin is the sum of the mass of the polycarbonate resin (1) and the mass of other binder resins.

The method for producing the polycarbonate resin (1) is not particularly limited as long as the polycarbonate resin (1) can be produced. As an example of the method for producing the polycarbonate resin (1), there may be mentioned a method (so-called phosgene method) in which a diol compound for constituting a repeating unit of the polycarbonate resin (1) and phosgene are subjected to condensation polymerization. More specifically, for example, a method of polycondensing a diol compound represented by the following general formula (7), a diol compound represented by the following general formula (8), and phosgene is mentioned. Incidentally, R ¹ and R ² in the general formula (7) has the same meaning as R ¹ and R ² in each formula (1). R ^3, R ⁴ and X in the general formula (8) has the same meaning as R ^3, R ⁴ and X each in the general formula (1). Another example of the method for producing the polycarbonate resin (1) includes a method of transesterifying a diol compound and diphenyl carbonate.

(Vickers hardness of photosensitive layer)
The Vickers hardness of the photosensitive layer at 40 ° C. is preferably 19.5 HV or more, more preferably 20.0 HV or more, and particularly preferably 20.0 HV or more and 23.0 HV or less. When the Vickers hardness of the photosensitive layer is within such a range, the contact area between the surface of the photoreceptor and the minute component can be reduced, and the minute component can be easily cleaned (removed) from the surface of the photoreceptor. As a result, the occurrence of filming can be suitably suppressed. Vickers hardness can be adjusted, for example, by changing one or both of the type of binder resin and the type of electron transport agent.

  The Vickers hardness of the photosensitive layer is measured, for example, by the following method. The Vickers hardness of the measurement sample (photosensitive layer) is measured by a method based on Japanese Industrial Standard (JIS) Z2244. For measuring the Vickers hardness, a hardness meter (for example, “Micro Vickers hardness meter DMH-1 type” manufactured by Matsuzawa Co., Ltd. (former Matsuzawa Seiki Co., Ltd.)) is used. Vickers hardness is measured, for example, at a temperature of 40 ° C., a diamond indenter load (test force) of 10 gf, a time required to reach the test force of 5 seconds, a diamond indenter approach speed of 2 mm / second, and a test force holding time of 1 second. Can be performed under the following conditions.

(Electron transfer agent)
The electron transport agent transports electrons in the photosensitive layer, for example, and imparts bipolar (bipolar) characteristics to the photosensitive layer. Examples of electron transfer agents are quinone compounds, diimide compounds, hydrazone compounds, malononitrile derivatives, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, dinitroanthracenes. Compound, dinitroacridine compound, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride or dibromomaleic anhydride. Examples of quinone compounds are diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, or dinitroanthraquinone compounds. One kind of electron transport agent may be used alone, or two or more kinds may be used in combination.

  The electron transfer agent is a compound represented by the following general formula (2) (hereinafter sometimes referred to as compound (2)) or a compound represented by the following general formula (4) (hereinafter referred to as compound (4)). May be described), and it is more preferable that the compound (2) is included.

  First, the compound (2) will be described. Compound (2) is an example of a malononitrile derivative.

In general formula (2), R ⁵ represents an alkyl group having 1 to 8 carbon atoms having one or more halogen atoms; a cycloalkyl group having 3 to 10 carbon atoms having one or more halogen atoms; An aryl group having 6 to 14 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms; a 5- to 14-membered heterocyclic ring having one or more halogen atoms Group: or an aralkyl group having 7 or more and 20 or less carbon atoms having at least one halogen atom.

  Generation | occurrence | production of filming can be further suppressed because an electron carrying agent contains a compound (2). The reason is presumed as follows. When a recording medium (for example, paper) and a photoconductor are in contact with each other in image formation, a minute component (for example, paper dust) of the recording medium may adhere to the surface of the photoconductor. The adhesion of minute components of the recording medium to the surface of the photoreceptor is a cause of filming. In particular, filming is likely to occur when a minute component (for example, paper dust) of a recording medium is rubbed by a photosensitive member and the minute component is charged to a negative polarity or a positive polarity lower than a desired value. Here, since the compound (2) has a halogen atom, the electronegativity is high. When the photosensitive layer contains the compound (2), the minute component of the recording medium comes into contact with the photoconductor, and when the minute component is rubbed by the photoconductor containing the compound (2) having a high electronegativity, It is considered that a minute component is charged to a positive polarity of a desired value or more. When the surface of the photoreceptor is positively charged in the charging process of image formation, the surface of the photoreceptor charged positively and a minute component having a positive polarity exceeding a desired value are electrically repelled. This makes it difficult for minute components to adhere to the surface of the photoreceptor. As a result, the occurrence of filming can be suppressed. In order for the electron transporting agent to contain the compound (2) to further suppress the occurrence of filming, the photoreceptor is preferably a positively charged single layer type photoreceptor.

The alkyl group having 1 to 8 carbon atoms represented by R ⁵ in the general formula (2) is linear or branched. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group. Hexyl group, heptyl group or octyl group. The alkyl group having 1 to 8 carbon atoms is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 3 to 5 carbon atoms, an n-propyl group, an n-butyl group, Neopentyl groups are more preferred, and n-butyl groups are particularly preferred. The alkyl group having 1 to 8 carbon atoms represented by R ⁵ has one or more halogen atoms. The halogen atom contained in the alkyl group having 1 to 8 carbon atoms represented by R ⁵ is preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group), and is a chlorine atom (chloro group). Is more preferable. The number of halogen atoms contained in the alkyl group having 1 to 8 carbon atoms represented by R ⁵ is preferably 1 or 2, and more preferably 1.

Examples of the cycloalkyl group having 3 to 10 carbon atoms represented by R ⁵ include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group. It is done. A cycloalkyl group having 3 to 10 carbon atoms has at least one halogen atom. The halogen atom contained in the cycloalkyl group having 3 to 10 carbon atoms represented by R ⁵ is preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group). The number of halogen atoms contained in the cycloalkyl group having 3 to 10 carbon atoms represented by R ⁵ is preferably 1 or 2.

The aryl group having 6 to 14 carbon atoms represented by R ⁵ is preferably a phenyl group. The aryl group having 6 to 14 carbon atoms represented by R ⁵ has one or more halogen atoms. The halogen atom contained in the aryl group having 6 to 14 carbon atoms represented by R ⁵ is preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group), and preferably a chlorine atom (chloro group). Is more preferable. The number of halogen atoms contained in the aryl group having 6 to 14 carbon atoms represented by R ⁵ is preferably 1 or 2. The aryl group having 6 to 14 carbon atoms may further have an alkyl group having 1 to 6 carbon atoms in addition to the halogen atom.

The ^5- to 14-membered heterocyclic group represented by R ⁵ contains at least one heteroatom in addition to the carbon atom. The hetero atom is at least one selected from the group consisting of a nitrogen atom, a sulfur atom and an oxygen atom. The 5- to 14-membered heterocyclic group includes, for example, a 5-membered or 6-membered monocyclic heterocyclic group containing 1 to 3 heteroatoms in addition to the carbon atom; A heterocyclic group in which two monocyclic rings are fused; a heterocyclic group in which such a monocyclic heterocyclic ring is fused with a 5- or 6-membered monocyclic hydrocarbon ring; and three such monocyclic heterocyclic rings A fused heterocyclic group; a heterocyclic group fused with two such monocyclic heterocycles and one 5- or 6-membered monocyclic hydrocarbon ring; or such monocyclic heterocycle 1 And a heterocyclic group formed by condensing two and five or six-membered monocyclic hydrocarbon rings. Specific examples of the 5- to 14-membered heterocyclic group include piperidinyl group, piperazinyl group, morpholinyl group, thiophenyl group, furanyl group, pyrrolyl group, imidazolyl group, pyrazolyl group, isothiazolyl group, isoxazolyl group, oxazolyl group, isoxazolyl group Group, thiazolyl group, isothiazolyl group, furazanyl group, pyranyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, indolyl group, 1H-indazolyl group, isoindolyl group, chromenyl group, quinolinyl group, isoquinolinyl group, purinyl group, pteridinyl Group, triazolyl group, tetrazolyl group, 4H-quinolidinyl group, naphthyridinyl group, benzofuranyl group, 1,3-benzodioxolyl group, benzoxazolyl group, benzothiazolyl group, benzimidazolyl group, Rubazoriru group, phenanthridinyl group, acridinyl group, phenazinyl group or include phenanthrolinyl group. The 5- to 14-membered heterocyclic group is preferably a 5- or 6-membered monocyclic heterocyclic group containing 1 to 3 hetero atoms (preferably a nitrogen atom) in addition to the carbon atom. Groups are more preferred. The ^5- to 14-membered heterocyclic group represented by R ⁵ has one or more halogen atoms. The halogen atom contained in the 5- to 14-membered heterocyclic group represented by R ⁵ is preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group). The number of halogen atoms contained in the 5- to 14-membered heterocyclic group represented by R ⁵ is preferably 1 or 2.

The aralkyl group having 7 to 20 carbon atoms represented by R ⁵ is an alkyl group having 1 to 6 carbon atoms to which an aryl group having 6 to 14 carbon atoms is bonded. The aralkyl group having 7 to 20 carbon atoms is preferably an alkyl group having 1 to 6 carbon atoms to which a phenyl group is bonded, and more preferably a phenylmethyl group (benzyl group) or a phenylethyl group. The aralkyl group having 7 to 20 carbon atoms represented by R ⁵ has one or more halogen atoms. The halogen atom contained in the aralkyl group having 7 to 20 carbon atoms represented by R ⁵ is preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group). The number of halogen atoms contained in the aralkyl group having 7 to 20 carbon atoms represented by R ⁵ is preferably one or two.

In the general formula (2), the bonding position (substitution position) of the group represented by the general formula “—COOR ⁵ ” is not particularly limited. The group represented by the general formula “—COOR ⁵ ” may be bonded to any of the 1-position, 2-position, 3-position and 4-position in the following chemical formula. The group represented by the general formula “—COOR ⁵ ” is preferably bonded to the 1-position, 2-position or 4-position in the following chemical formula, and more preferably bonded to the 4-position.

R ⁵ preferably represents an alkyl group having 1 to 8 carbon atoms and having one or more halogen atoms. When R ⁵ represents an alkyl group having 1 to 8 carbon atoms having one halogen atom, the existence probability of the compound (2) in the vicinity of the surface of the photosensitive layer tends to increase. As a result, when the minute component (for example, paper dust) of the recording medium is rubbed by the photoconductor, the minute component of the recording medium tends to have a large positive charge amount. Thereby, it is thought that generation | occurrence | production of filming can be suppressed suitably.

  Specific examples of the compound (2) are compounds represented by the following chemical formulas (2-1) to (2-9) (hereinafter may be referred to as compounds (2-1) to (2-9)). is there. Of these, compound (2-1) is preferred.

[Production Method of Compound (2)]
Compound (2) is produced, for example, according to the following reactions (R-1) and (R-2) or by a method analogous thereto. In addition to these reactions, appropriate steps may be included as necessary. R ⁵ in the reaction formulas shown in the reaction (R-1) and (R-2) has the same meaning as R ⁵ in the general formula (2). Further, the compounds represented by the following chemical formula (A), general formula (B), general formula (C), and chemical formula (D) are respectively represented by compounds (A), (B), (C), and (D). May be described.

  In the reaction (R-1), 1 molar equivalent of the compound (A) and 1 molar equivalent of the compound (B) are reacted to obtain 1 molar equivalent of the compound (C). It is preferable to add 1 mol or more and 5 mol or less of compound (B) with respect to 1 mol of compound (A). The reaction temperature for reaction (R-1) is preferably 80 ° C. or higher and 150 ° C. or lower. The reaction time for reaction (R-1) is preferably 2 hours or longer and 10 hours or shorter.

  Reaction (R-1) may be carried out in the presence of a catalyst. Examples of the catalyst include an acid catalyst, and more specifically, p-toluenesulfonic acid, camphorsulfonic acid, or pyridinium-p-toluenesulfonic acid. These catalysts may be used individually by 1 type, and may be used in combination of 2 or more type. The addition amount of the catalyst is a small amount with respect to 1 mol of the compound (A), and specifically, it is preferably 0.01 mol or more and 0.5 mol or less.

  Reaction (R-1) may be carried out in a solvent. Examples of the solvent include ethers (specifically, tetrahydrofuran, diethyl ether or dioxane), halogenated hydrocarbons (specifically, methylene chloride, chloroform or dichloroethane) or aromatic hydrocarbons (specifically, Benzene or toluene).

  In the reaction (R-2), 1 molar equivalent of the compound (C) and 1 molar equivalent of the compound (D, malononitrile) are reacted to obtain 1 molar equivalent of the compound (2). It is preferable to add 1 mol or more and 5 mol or less of compound (D) with respect to 1 mol of compound (C). The reaction temperature for reaction (R-2) is preferably 40 ° C. or higher and 120 ° C. or lower. The reaction time for reaction (R-2) is preferably from 1 hour to 10 hours.

  Reaction (R-2) may be carried out in the presence of a catalyst. Examples of the catalyst include a base catalyst, and more specifically, piperidine and piperazine.

  Reaction (R-2) may be performed in a solvent. Examples of the solvent include polar solvents, and more specifically, methanol, ethanol, n-propanol, acetone, or dioxane.

  By purifying the reaction product obtained in the reaction (R-2) as necessary, the target compound (2) can be isolated. As a purification method, a known method is appropriately employed. Purification may be performed, for example, by crystallization or silica gel chromatography. An example of the solvent used for purification is chloroform.

  When the photosensitive layer contains the compound (2) as an electron transport agent, the content of the compound (2) is preferably 80% by mass or more, and 90% by mass or more with respect to the total mass of the electron transport agent. More preferably, it is particularly preferably 100% by mass.

  The content of the compound (2) as the electron transfer agent is preferably 20 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin. When the content of the compound (2) is 20 parts by mass or more with respect to 100 parts by mass of the binder resin, it is easy to improve electrical characteristics (hereinafter referred to as sensitivity characteristics) of the photoreceptor. When the content of the compound (2) is 40 parts by mass or less with respect to 100 parts by mass of the binder resin, the compound (2) is easily dissolved in the solvent for forming the photosensitive layer, and a uniform photosensitive layer is formed. It becomes easy.

  Next, the compound (4) will be described. The compound (4) is represented by the following general formula (4).

In general formula (4), R ^{18 to} R ²¹ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may have an aryl group having 6 to 14 carbon atoms, or carbon. An alkenyl group having 2 to 6 atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a heterocyclic group having 5 to 14 members.

The alkenyl group having 2 to 6 carbon atoms represented by R ^{18 to} R ²¹ in the general formula (4) is linear or branched and unsubstituted. The alkenyl group having 2 to 6 carbon atoms has, for example, 1 to 3 double bonds. Examples of the alkenyl group having 2 to 6 carbon atoms include a vinyl group (ethenyl group), propenyl group, butenyl group, pentenyl group, pentadienyl group, hexenyl group, and hexadienyl group.

Examples of the 5- to 14-membered heterocyclic group represented by R ^{18 to} R ²¹ in the general formula (4) are those of the 5- to 14-membered heterocyclic group represented by R ⁵ in the general formula (2). Same as example.

In General Formula (4), R ^{18 to} R ²¹ each independently preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group or a tert-butyl group.

  A specific example of the compound (4) is a compound represented by the following chemical formula (4-1) (hereinafter sometimes referred to as the compound (4-1)).

  When the photosensitive layer contains the compound (4) as an electron transport agent, the content of the compound (4) is preferably 80% by mass or more, and 90% by mass or more with respect to the total mass of the electron transport agent. More preferably, it is particularly preferably 100% by mass.

  The content of the compound (4) as the electron transfer agent is preferably 20 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin. When the content of the compound (4) is 20 parts by mass or more with respect to 100 parts by mass of the binder resin, it is easy to improve the sensitivity characteristics of the photoreceptor. When the content of the compound (4) is 40 parts by mass or less with respect to 100 parts by mass of the binder resin, the compound (4) is easily dissolved in the solvent for forming the photosensitive layer, and a uniform photosensitive layer is formed. It becomes easy.

(Hole transport agent)
The photosensitive layer contains, for example, a hole transport agent. Examples of the hole transport agent include triphenylamine derivatives and diamine derivatives (for example, N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ′, N′-tetraphenylphenylenediamine derivatives, N, N, N ′, N′-tetraphenylnaphthylenediamine derivative, N, N, N ′, N′-tetraphenylphenanthrylenediamine derivative or di (aminophenylethenyl) benzene derivative), oxadiazole series A compound (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), a styryl compound (eg, 9- (4-diethylaminostyryl) anthracene), a carbazole compound (eg, , Polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (for example, 1-phenyl-3- (p- Methylamino phenyl) pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compound, or triazole-based compounds. One kind of hole transport agent may be used alone, or two or more kinds may be used in combination.

  The hole transport agent preferably contains a compound represented by the following general formula (3) (hereinafter sometimes referred to as compound (3)).

In the general formula (3), R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ are each independently hydrogen. An atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms is represented.

When the photosensitive layer contains the compound (3), generation of oil cracks can be further suppressed. The reason is presumed as follows. Compound (3) has a diamine structure. R ^{6 to} R ^{17 in the} compound (3) each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. R ^{6 to} R ¹⁷ included in the compound (3) are not a conjugated group such as an alkenyl group or an aryl group. Therefore, the molecular weight of compound (3) is relatively small. It is considered that the compound (3) having such a chemical structure is combined with the polycarbonate resin (1) and contained in the photosensitive layer, so that the compound (3) fills voids (fine voids) in the photosensitive layer. As a result, it is considered that the occurrence of oil cracks can be suitably suppressed.

The alkyl group having 1 to 6 carbon atoms represented by R ^{6 to} R ¹⁷ is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

The alkoxy group having 1 to 6 carbon atoms represented by R ^{6 to} R ¹⁷ is preferably an alkoxy group having 1 to 3 carbon atoms, more preferably a methoxy group or an ethoxy group, and particularly preferably a methoxy group.

In order to suppress the occurrence of oil cracks and filming, in general formula (3), R ^{6 to} R ¹⁷ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. It is more preferable to represent a hydrogen atom, a methyl group, an ethyl group, a methoxy group or an ethoxy group, and it is particularly preferable to represent a hydrogen atom or a methyl group.

In order to suppress the occurrence of oil cracks and filming, in general formula (3), R ⁶ and R ⁹ are preferably the same group. R ⁷ and R ¹⁰ are preferably the same group. R ⁸ and R ¹¹ are preferably the same group.

In order to suppress the occurrence of oil cracks and filming, it is preferable that R ^{12 to} R ¹⁷ in the general formula (3) represent hydrogen atoms.

  Specific examples of the compound (3) are compounds represented by the following chemical formulas (3-1) to (3-4) (hereinafter may be referred to as compounds (3-1) to (3-4)). is there. Of these, compound (3-1) is preferred.

  When the photosensitive layer contains the compound (3) as a hole transport agent, the content of the compound (3) is preferably 80% by mass or more, and 90% by mass with respect to the total mass of the hole transport agent. The above is more preferable, and 100% by mass is particularly preferable.

  The content of the compound (3) as a hole transport agent contained in the photosensitive layer is preferably 40 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the photosensitive layer. When the content of the compound (3) is within such a range, it is easy to improve the Vickers hardness of the photosensitive layer. As a result, it is considered that the occurrence of filming can be suppressed.

(Charge generator)
The photosensitive layer contains a charge generating agent. 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, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azurenium pigments, cyanine Pigments, inorganic photoconductive materials (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide or amorphous silicon), pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples include pyrazoline pigments and quinacridone pigments. One kind of charge generating agent may be used alone, or two or more kinds may be used in combination.

  Examples of the phthalocyanine pigment include metal-free phthalocyanine or metal phthalocyanine represented by the chemical formula (CGM-1). Examples of the metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, or chlorogallium phthalocyanine. The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape of the phthalocyanine pigment (for example, α type, β type, Y type, V type or II type) 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 crystal of titanyl phthalocyanine include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter sometimes referred to as α-type, β-type, or Y-type titanyl phthalocyanine). Examples of the crystal of hydroxygallium phthalocyanine include a V-type crystal of hydroxygallium phthalocyanine. Examples of chlorogallium phthalocyanine crystals include chlorogallium phthalocyanine type II crystals.

  For example, in a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoreceptor having sensitivity in a wavelength region of 700 nm or more. Since it has a high quantum yield in a wavelength region of 700 nm or more, the charge generator is preferably a phthalocyanine pigment, more preferably a metal-free phthalocyanine or titanyl phthalocyanine, and even more preferably an X-type metal-free phthalocyanine or a Y-type titanyl phthalocyanine. X-type metal-free phthalocyanine is particularly preferred.

  In a photoreceptor applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of 350 nm or more and 550 nm or less), an sanslon pigment is preferably used as a charge generating agent.

  The content of the charge generating agent is preferably 0.1 parts by mass or more and 50 parts by mass or less, and preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the photosensitive layer. Is more preferable.

(Additive)
The photosensitive layer may contain an additive as necessary. Examples of additives include deterioration inhibitors (for example, antioxidants, radical scavengers, singlet quenchers or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersion stabilizers. , Waxes, acceptors, donors, surfactants, plasticizers, sensitizers or leveling agents. Antioxidants include, for example, hindered phenols (eg, di (tert-butyl) p-cresol), hindered amines, paraphenylenediamine, arylalkanes, hydroquinones, spirochromans, spirodinones or their derivatives, organic sulfur compounds or An organic phosphorus compound is mentioned.

<1-2. Conductive substrate>
The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor. The conductive substrate may be formed of a material having at least a surface portion having conductivity. An example of the conductive substrate is a conductive substrate formed of a conductive material. Another example of the conductive substrate is 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 to the conductive substrate is good.

  The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus. Examples of the shape of the conductive substrate include a sheet shape or a drum shape. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

<1-3. Intermediate layer>
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used for the intermediate layer. The presence of the intermediate layer is considered to suppress the increase in resistance by smoothing the flow of current generated when the photosensitive member is exposed while maintaining an insulating state capable of suppressing the occurrence of leakage.

  Examples of the inorganic particles include 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 resin for the intermediate layer is not particularly limited as long as it can be used as a resin for forming the intermediate layer. The intermediate layer may contain an additive. Examples of the additive for the intermediate layer are the same as those for the additive for the photosensitive layer.

<1-4. Photoconductor manufacturing method>
The photoreceptor is manufactured, for example, as follows. The photoreceptor is manufactured by applying a coating solution for the photosensitive layer onto a conductive substrate and drying. The coating solution for the photosensitive layer is produced by dissolving or dispersing a charge generator, an electron transport agent, a hole transport agent, a binder resin, and a component added as necessary (for example, an additive) in a solvent. .

  The solvent contained in the photosensitive layer coating solution is not particularly limited as long as each component contained in the coating solution can be dissolved or dispersed. Examples of solvents include alcohols (eg, methanol, ethanol, isopropanol or butanol), aliphatic hydrocarbons (eg, n-hexane, octane or cyclohexane), aromatic hydrocarbons (eg, benzene, toluene or xylene), Halogenated hydrocarbons (eg dichloromethane, dichloroethane, carbon tetrachloride or chlorobenzene), ethers (eg dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or propylene glycol monomethyl ether), ketones (eg acetone, Methyl ethyl ketone or cyclohexanone), esters (eg ethyl acetate or methyl acetate), dimethylformaldehyde, dimethylform Amide or dimethyl sulfoxide. These solvents are used alone or in combination of two or more. In order to improve the workability during the production of the photoreceptor, it is preferable to use a non-halogen solvent (a solvent other than the halogenated hydrocarbon) as the solvent.

  The 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 can be used.

  The photosensitive layer coating solution may contain, for example, a surfactant in order to improve the dispersibility of each component.

  The method for applying the photosensitive layer coating solution is not particularly limited as long as the coating solution can be uniformly applied on the conductive substrate. 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 drying the photosensitive layer coating solution is not particularly limited as long as the solvent in the coating solution can be evaporated. For example, the method of heat-processing (hot-air drying) is mentioned using a high-temperature dryer or a vacuum dryer. 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.

  In addition, the manufacturing method of a photoreceptor may further include one or both of a step of forming an intermediate layer and a step of forming a protective layer as necessary. A known method is appropriately selected in the step of forming the intermediate layer and the step of forming the protective layer.

<2. Image forming apparatus>
Next, an image forming apparatus 100 including the photoreceptor 1 according to the present embodiment will be described with reference to FIG. FIG. 2 shows an example of the configuration of the image forming apparatus 100.

  The image forming apparatus 100 is not particularly limited as long as it is an electrophotographic image forming apparatus. For example, the image forming apparatus 100 may be a monochrome image forming apparatus or a color image forming apparatus. When the image forming apparatus 100 is a color image forming apparatus, the image forming apparatus 100 employs, for example, a tandem method. Hereinafter, the tandem image forming apparatus 100 will be described as an example.

  The image forming apparatus 100 includes image forming units 40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing unit 52. Hereinafter, when it is not necessary to distinguish, each of the image forming units 40a, 40b, 40c, and 40d is referred to as an image forming unit 40.

  The image forming unit 40 includes the photoreceptor 1, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. The photoreceptor 1 is provided at the center position of the image forming unit 40. The photoreceptor 1 is provided so as to be rotatable in the arrow direction (counterclockwise). Around the photosensitive member 1, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48 are provided in order from the upstream side in the rotation direction of the photosensitive member 1 with respect to the charging unit 42. The image forming unit 40 may further include one or both of a cleaning unit (not shown) and a charge removal unit (not shown).

  The charging unit 42 charges the surface of the photoreceptor 1. The charging unit 42 is a non-contact method or a contact method. An example of the non-contact charging unit 42 is a corotron charger or a scorotron charger. An example of the contact-type charging unit 42 is a charging roller or a charging brush.

  The image forming apparatus 100 can include a charging roller as the charging unit 42. When charging the surface of the photoreceptor 1, the charging roller contacts the photoreceptor 1. When a minute component is attached to the surface of the photoreceptor 1, the minute component is pressed against the surface of the photoreceptor 1 by the charging roller that has come into contact. Thereby, a minute component is easily fixed on the surface of the photoreceptor 1. However, the image forming apparatus 100 includes the photoreceptor 1 that can suppress the occurrence of filming caused by the adhesion of minute components. For this reason, even when the image forming apparatus 100 includes a charging roller as the charging unit 42, it is difficult for minute components to adhere to the surface of the photoreceptor 1, and the occurrence of filming in the formed image is suppressed. it can.

  In order to improve the sensitivity characteristics of the photoreceptor 1 that is a single-layer photoreceptor, the charging unit 42 preferably charges the surface of the photoreceptor 1 to a positive polarity. When the photosensitive layer 3 (see FIGS. 1A to 1C) contains the compound (2) as an electron transfer agent, the photosensitive member 1 and the recording medium P are rubbed to charge the recording medium P to positive polarity. The tendency to be strengthened. When the surface of the photoreceptor 1 is positively charged by the charging unit 42, the surface of the photoreceptor 1 and the recording medium P that is frictionally charged to the positive polarity are electrically repelled. As a result, minute components (for example, paper dust) of the recording medium P are difficult to adhere to the surface of the photoreceptor 1, and the occurrence of filming can be suitably suppressed.

  The exposure unit 44 exposes the surface of the charged photoreceptor 1. As a result, an electrostatic latent image is formed on the surface of the photoreceptor 1. The electrostatic latent image is formed based on image data input to the image forming apparatus 100.

  The developing unit 46 supplies toner to the electrostatic latent image formed on the photoreceptor 1. As a result, the electrostatic latent image is developed as a toner image. The photoreceptor 1 corresponds to an image carrier that carries a toner image. The toner may be used as a one-component developer. Alternatively, the toner and the desired carrier may be mixed and used in the two-component developer. When toner is used as a one-component developer, the developing unit 46 supplies toner that is a one-component developer to the electrostatic latent image formed on the photoreceptor 1. When toner is used in the two-component developer, the developing unit 46 supplies toner from the toner and carrier contained in the two-component developer to the electrostatic latent image formed on the photoreceptor 1.

  The developing unit 46 can develop the electrostatic latent image as a toner image while in contact with the photoreceptor 1. That is, the image forming apparatus 100 can employ a so-called contact development method. When a minute component adheres to the surface of the photoreceptor 1, the minute component is pressed against the surface of the photoreceptor 1 by the developing unit 46 that has come into contact. Thereby, a minute component is easily fixed on the surface of the photoreceptor 1. However, the image forming apparatus 100 includes the photoreceptor 1 that can suppress the occurrence of filming caused by the adhesion of minute components. For this reason, even when the image forming apparatus 100 adopts the contact development method, it is difficult for the minute components to adhere to the surface of the photoreceptor 1 and the occurrence of filming can be suppressed.

  The developing unit 46 can clean the surface of the photoreceptor 1. That is, the image forming apparatus 100 can employ a so-called cleaner-less method. The developing unit 46 can remove minute components remaining on the surface of the photoreceptor 1. When the cleaner-less method is employed, the image forming apparatus 100 does not include a cleaning unit. In the image forming apparatus 100 that employs the cleaner-less method, a minute component remaining on the surface of the photoreceptor 1 is not scraped off by a cleaning unit (for example, a cleaning blade). For this reason, in the image forming apparatus 100 that employs the cleaner-less method, usually, minute components tend to remain on the surface of the photoreceptor 1. However, the photoconductor 1 of the present embodiment can suppress the occurrence of filming caused by the adhesion of minute components. Therefore, even if the image forming apparatus 100 including such a photoreceptor 1 adopts a cleaner-less method, minute components hardly remain on the surface of the photoreceptor 1 and can suppress filming.

In order for the developing unit 46 to efficiently clean the surface of the photoreceptor 1, it is preferable to satisfy the following conditions (a) and (b).
Condition (a): A contact developing method is adopted, and a circumferential speed (rotational speed) difference is provided between the photoreceptor 1 and the developing unit 46.
Condition (b): The surface potential of the photoreceptor 1 and the potential of the developing bias satisfy the following formulas (b-1) and (b-2).
0 (V) <potential of developing bias (V) <surface potential of unexposed area of photoreceptor 1 (V) (b-1)
Potential of developing bias (V)> surface potential of exposed area of photoreceptor 1 (V)> 0 (V) (b-2)

  When the contact development method shown in the condition (a) is employed and a peripheral speed difference is provided between the photosensitive member 1 and the developing unit 46, the surface of the photosensitive member 1 comes into contact with the developing unit 46, and the photosensitive member 1 The minute components on the surface are removed by friction with the developing section 46. The peripheral speed of the developing unit 46 is preferably faster than the peripheral speed of the photoreceptor 1.

  Condition (b) assumes a case where the development method is a reversal development method. In order to improve the sensitivity characteristics of the photoreceptor 1, the toner charging polarity, the surface potential of the unexposed area of the photoreceptor 1, the surface potential of the exposed area of the photoreceptor 1 and the potential of the developing bias are all positive. It is preferable. It should be noted that the surface potential of the unexposed area and the exposed area of the photoreceptor 1 are the same as the surface potential of the photoreceptor 1 in which the transfer section 48 transfers the toner image from the photoreceptor 1 to the recording medium P and then the charging section 42 performs the next round. Measured before charging the surface.

  When the mathematical expression (b-1) of the condition (b) is satisfied, the electrostatic force acting between the toner remaining on the photoreceptor 1 (hereinafter sometimes referred to as “residual toner”) and the unexposed area of the photoreceptor 1. The repulsive force is larger than the electrostatic repulsive force acting between the residual toner and the developing unit 46. Therefore, the residual toner in the unexposed area of the photoreceptor 1 moves from the surface of the photoreceptor 1 to the developing unit 46 and is collected.

  When the mathematical expression (b-2) of the condition (b) is satisfied, the electrostatic repulsive force acting between the residual toner and the exposed area of the photoreceptor 1 acts on the electrostatic force acting between the residual toner and the developing unit 46. Smaller than the repulsive force. Therefore, the residual toner in the exposed area of the photoconductor 1 is held on the surface of the photoconductor 1. The toner held in the exposure area of the photoreceptor 1 is used as it is for image formation.

  The transfer belt 50 conveys the recording medium P between the photoreceptor 1 and the transfer unit 48. The transfer belt 50 is an endless belt. The transfer belt 50 is provided to be rotatable in the arrow direction (clockwise).

  The transfer unit 48 transfers the toner image developed by the developing unit 46 from the photoreceptor 1 to the recording medium P. When the toner image is transferred from the photoreceptor 1 to the recording medium P, the photoreceptor 1 is in contact with the recording medium P. That is, the image forming apparatus 100 employs a so-called direct transfer method. In the image forming apparatus 100 that employs the direct transfer method, when the photosensitive member 1 comes into contact with the recording medium P, minute components (for example, paper dust) of the recording medium P are easily attached to the surface of the photosensitive member 1 and solidify easily. . Therefore, filming is likely to occur on the surface of the photoreceptor 1 in the image forming apparatus 100 employing the direct transfer method. However, the image forming apparatus 100 includes the photoreceptor 1 that can suppress the occurrence of filming caused by the adhesion of minute components. For this reason, even when the image forming apparatus 100 adopts the direct transfer method, it is difficult for the minute components to adhere to the surface of the photoreceptor 1 and solidify, and the occurrence of filming can be suppressed. The transfer unit 48 is, for example, a transfer roller.

  Each of the image forming units 40a to 40d sequentially superimposes toner images of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) on the recording medium P on the transfer belt 50. When the image forming apparatus 100 is a monochrome image forming apparatus, the image forming apparatus 100 includes an image forming unit 40a, and the image forming units 40b to 40d are omitted.

  The fixing unit 52 heats and / or pressurizes the unfixed toner image transferred to the recording medium P by the transfer unit 48. The fixing unit 52 is, for example, a heating roller and / or a pressure roller. The toner image is fixed on the recording medium P by heating and / or pressurizing the toner image. As a result, an image is formed on the recording medium P.

<3. Process cartridge>
Next, with reference to FIG. 2 again, a process cartridge including the photoreceptor 1 of the present embodiment will be described. The process cartridge corresponds to each of the image forming units 40a to 40d. The process cartridge includes a photoreceptor 1. In addition to the photoreceptor 1, the process cartridge may further include at least one selected from the group consisting of a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. The process cartridge may further include one or both of a cleaning device (not shown) and a static eliminator (not shown). The process cartridge is designed to be detachable from the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics of the photoconductor 1 deteriorate, the process cartridge including the photoconductor 1 can be replaced easily and quickly.

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

<1. Photosensitive Material>
As materials for forming the photosensitive layer of the photoreceptor, the following binder resin, charge generating agent, hole transporting agent and electron transporting agent were prepared.

<1-1. Binder resin>
Polycarbonate resins (1-1) to (1-3) described in the embodiment were prepared as binder resins. The viscosity average molecular weights of the polycarbonate resins (1-1) to (1-3) were 51200, respectively.

  Polycarbonate resins (1-4) to (1-9) were prepared as binder resins for comparison. Each of the polycarbonate resins (1-4) to (1-9) is represented by the following chemical formulas (1-4) to (1-9). The viscosity average molecular weights of the polycarbonate resins (1-4) to (1-9) were 50300, respectively. In addition, the subscript attached | subjected to the repeating unit in Chemical formula (1-4)-(1-9) represents the mole fraction of each repeating unit. The subscript “1.00” in chemical formulas (1-4) and (1-7) is a repeating unit in which the polycarbonate resins (1-4) and (1-7) are subscripted, respectively. It is composed of only.

<1-2. Charge generator>
An X-type crystal of metal-free phthalocyanine was prepared as a charge generating agent. Metal-free phthalocyanine is represented by the chemical formula (CGM-1) described in the embodiment.

<1-3. Hole transport agent>
The compound (3-1) described in the embodiment was prepared as a hole transport agent. In addition, a compound represented by the following chemical formula (3-5) (hereinafter sometimes referred to as compound (3-5)) was also prepared.

<1-4. Electron transport agent>
As the electron transfer agent, the compounds (2-1) and (4-1) described in the embodiment were prepared. Compound (2-1) was produced according to the following reactions (R-3) and (R-4). Compounds represented by chemical formulas (A-1), (B-1), (C-1), (D), and (2-1) in the following reaction formulas are respectively represented by compounds (A-1), ( B-1), (C-1), (D), and (2-1) may be described.

  In reaction (R-3), compound (A-1) and compound (B-1) were reacted to obtain compound (C-1). 2.24 g (0.01 mol) of compound (A-1), 3.26 g (0.03 mol) of compound (B-1) and toluene (100 mL) were added to the flask to dissolve the contents of the flask. . P-Toluenesulfonic acid (0.001 mol) was added into the flask. The flask was set in a Dean-Stark apparatus. The contents of the flask were refluxed at 90 ° C. for 5 hours while dehydrating. The contents of the obtained flask were decompressed, and toluene was distilled off. Ion exchange water was added to the mixture after distillation under reduced pressure, and the mixture was extracted with chloroform. After the obtained organic layer was dried, the organic layer was depressurized and chloroform was distilled off. As a result, compound (C-1) was obtained as a crude product. The yield of compound (C-1) was 2.84 g, and the yield of compound (C-1) from compound (A-1) was 90 mol%.

  In reaction (R-4), compound (C-1) and compound (D, malononitrile) were reacted to obtain compound (1-1). 1.57 g (0.005 mol) of compound (C-1) and 0.66 g (0.01 mol) of compound (D) were added to methanol (100 mL) to obtain a methanol solution. To the methanol solution, 0.08 g (0.001 mol) of piperidine was added to obtain a mixture. The mixture was stirred at 80 ° C. for 3 hours at reflux. Subsequently, the mixture was added to ion exchange water (200 mL) to precipitate a solid, and the solid was collected by filtration. The obtained solid was purified by silica gel column chromatography using chloroform as a developing solvent. As a result, compound (2-1) was obtained. The yield of compound (2-1) was 1.45 g, and the yield of compound (2-1) from compound (C-1) was 80 mol%.

Next, with reference to ¹ H-NMR (proton nuclear magnetic resonance spectroscopy), it was analyzed by ¹ H-NMR spectrum of the compound prepared (2-1). The magnetic field strength was set to 300 MHz. Deuterated chloroform (CDCl ₃ ) was used as the solvent. Tetramethylsilane (TMS) was used as an internal standard substance. The chemical shift value of the ¹ H-NMR spectrum of the compound (2-1) is shown below. From the measured ¹ H-NMR spectrum and chemical shift value, it was confirmed that the compound (2-1) was obtained.

Compound (2-1): ¹ H-NMR (300 MHz, CDCl ₃ ) δ = 8.53 (dd, 1H), 8.39 (d, 1H), 8.18 (d, 1H), 7.85 ( dd, 1H), 7.49 (dt, 1H), 7.35 (t, 1H), 7.34 (dt, 1H), 4.45 (t, 2H), 3.63 (t, 2H), 1.90-2.07 (m, 4H).

<2. Manufacture of photoconductor>
Photoconductors (P-1) to (P-11) were produced using materials for forming the photosensitive layer.

<2-1. Production of photoconductor (P-1)>
In the container, 2 parts by mass of X-type metal-free phthalocyanine as a charge generator, 55 parts by mass of compound (3-1) as a hole transport agent, 35 parts by mass of compound (2-1) as an electron transport agent, a binder 100 parts by mass of polycarbonate resin (1-1) as a resin and 700 parts by mass of tetrahydrofuran as a solvent were added. The contents of the container were mixed for 12 hours using a ball mill to disperse the material in the solvent. This obtained the coating liquid for photosensitive layers. The photosensitive layer coating solution was coated on an aluminum drum-shaped support (diameter 30 mm, total length 238.5 mm) as a conductive substrate by using a dip coating method. The coated photosensitive layer coating solution was dried with hot air at 120 ° C. for 50 minutes. As a result, a single photosensitive layer (having a thickness of 30 μm) was formed on the conductive substrate. As a result, a photoreceptor (P-1) was obtained.

<2-2. Production of photoconductors (P-2) to (P-11)>
Each of the photoreceptors (P-2) to (P-11) was produced by the same method as the production of the photoreceptor (P-1) except that the following points were changed. The polycarbonate resin (1-1) as the binder resin used for the production of the photoreceptor (P-1) was changed to the type of binder resin shown in Table 1. The compound (2-1) as the electron transport agent used for the production of the photoreceptor (P-1) was changed to the type of electron transport agent shown in Table 1. The compound (3-1) as the hole transport agent used for the production of the photoreceptor (P-1) was changed to the type of hole transport agent shown in Table 1.

<3. Measurement of Vickers hardness>
The Vickers hardness of the photosensitive layer was measured for each of the obtained photoreceptors (P-1) to (P-11). The Vickers hardness of the photosensitive layer was measured by a method based on Japanese Industrial Standard (JIS) Z2244. For the measurement of Vickers hardness, a hardness meter (“Micro Vickers hardness meter DMH-1 type” manufactured by Matsuzawa Co., Ltd. (formerly Matsuzawa Seiki Co., Ltd.)) was used. Vickers hardness is measured under the conditions of a temperature of 40 ° C., a diamond indenter load (test force) of 10 gf, a time required to reach the test force of 5 seconds, a diamond indenter approach speed of 2 mm / second, and a test force holding time of 1 second. I went there. Table 1 shows the measured Vickers hardness (unit: HV) of the photosensitive layer.

<4. Evaluation of filming resistance>
Filming resistance was evaluated for each of the obtained photoreceptors (P-1) to (P-11). As an evaluation machine, the image forming apparatus (a modified machine of “Monochrome Printer FS-1300D” manufactured by Kyocera Document Solutions Co., Ltd.) was installed. This image forming apparatus employs a direct transfer system, a contact development system, and a cleaner-less system. In this image forming apparatus, the developing unit cleans the toner remaining on the photoreceptor. This image forming apparatus includes a charging roller as a charging unit. The charging polarity of the charging roller was set to positive polarity. Using this image forming apparatus, images (printing) are printed on 20000 sheets (“Kyocera Document Solutions Brand Paper VM-A4”, A4 size, sold by Kyocera Document Solutions Co., Ltd.) under the condition that the rotational speed of the photosensitive member is 168 mm / sec. 1%) was printed continuously. Printing was performed in an environment of a temperature of 35 ° C. and a humidity of 85% RH. A one-component developer (prototype) was used for printing.

  After printing, the photoreceptor was removed from the image forming apparatus, and the degree of toner filming on the surface of the photoreceptor was observed. Specifically, the surface of the photoreceptor was observed at a magnification of 50 using an optical microscope (“Sennar KK” manufactured by Nikon Corporation) to obtain an observation image. The pixels constituting the obtained observation image each had a luminance value of 0 or more and 255 or less. Using the image analysis software (Image J), the observed image was subjected to a binarization process using the luminance value 180 as a threshold value. A pixel having a luminance value less than the threshold corresponds to a region where filming has occurred. On the other hand, a pixel having a luminance value equal to or higher than the threshold corresponds to a region where filming has not occurred.

By binarization processing, the area (Af) of the region where filming occurred and the area (An) of the region where filming did not occur were obtained. From the obtained Af and An, the area ratio of the filming region (filming area ratio) was obtained according to the following calculation formula.
Filming area ratio [%] = 100 × Af / (Af + An)

  Table 1 shows the evaluation results of filming resistance (filming area ratio). A photoreceptor having a filming area ratio of less than 1.55% was evaluated as having good filming resistance.

<5. Evaluation of oil crack resistance>
Oil crack resistance was evaluated for each of the obtained photoreceptors (P-1) to (P-11). Specifically, fats and oils (oleic acid triglyceride) were attached to the surface (10 measurement points) of the photoreceptor and left for 2 days in an environment of a temperature of 23 ° C. and a humidity of 50% RH. Thereafter, the surface of the photoreceptor was observed with the naked eye, and the presence or absence of cracks was confirmed at each measurement location. From the confirmation results, the oil crack resistance of the photoreceptor was evaluated according to the following criteria. Table 1 shows the evaluation results of oil crack resistance. A photoreceptor having an evaluation of A or B was evaluated as having good oil crack resistance.
(Evaluation criteria for oil crack resistance)
Evaluation A: The number of cracks generated was zero.
Evaluation B: The number of cracks generated was 1 or more and 3 or less.
Evaluation C: The number of cracks generated was 4 or more and 10 or less.
Evaluation D: The number of cracks generated was 11 or more.

  In Table 1, each of ETM and HTM represents an electron transport agent and a hole transport agent.

  The photosensitive layers of the photoreceptors (P-1) to (P-3) and (P-10) were a single photosensitive layer containing a charge generator, an electron transport agent, a hole transport agent, and a binder resin. . The binder resin contained polycarbonate resin (1), specifically, polycarbonate resin (1-1), (1-2) or (1-3). Therefore, as apparent from Table 1, the photoreceptors (P-1) to (P-3) and (P-10) had good oil crack resistance. In the photoreceptors (P-1) to (P-3) and (P-10), the filming area ratio was less than 1.55%, and the filming resistance was also good.

  On the other hand, the photosensitive layers of the photoreceptors (P-4) to (P-9) and (P-11) did not contain the polycarbonate resin (1). Specifically, the polycarbonate resin (1-4) contained in the photosensitive layer of the photoreceptor (P-4) did not have the repeating unit (6) described in the embodiment. Therefore, as is clear from Table 1, the photoreceptor (P-4) was inferior in oil crack resistance.

  In the polycarbonate resin (1-5) contained in the photosensitive layer of the photoreceptor (P-5), n in the general formula (1) was larger than 0.70. Therefore, as is clear from Table 1, the photoreceptor (P-5) was inferior in oil crack resistance.

  In the polycarbonate resin (1-6) contained in the photosensitive layer of the photoreceptor (P-6), n in the general formula (1) was less than 0.30. Therefore, as apparent from Table 1, the photoreceptor (P-6) had a filming area ratio of 1.55% or more, and was inferior in filming resistance.

  The polycarbonate resin (1-7) contained in the photosensitive layer of the photoreceptor (P-7) did not have the repeating unit (5) described in the embodiment. Therefore, as apparent from Table 1, the photoreceptor (P-7) was inferior in oil crack resistance. Further, the photoreceptor (P-7) had a filming area ratio of 1.55% or more, and was inferior in filming resistance.

  The polycarbonate resin (1-8) contained in the photosensitive layer of the photoreceptor (P-8) had two types of repeating units. However, one of the two types of repeating units was not the repeating unit (5) described in the embodiment. Therefore, as apparent from Table 1, the photoreceptor (P-8) had a filming area ratio of 1.55% or more and was inferior in filming resistance.

  The polycarbonate resin (1-9) contained in the photosensitive layers of the photoreceptors (P-9) and (P-11) had a repeating unit containing a siloxane bond. Therefore, as is clear from Table 1, the photoreceptors (P-9) and (P-11) were inferior in oil crack resistance. Further, the photoreceptors (P-9) and (P-11) had a filming area ratio of 1.55% or more and were inferior in filming resistance.

  From the above, it has been shown that the photoreceptor according to the present invention can achieve both suppression of oil cracking and suppression of filming. Further, it has been shown that the process cartridge and the image forming apparatus according to the present invention can achieve both suppression of oil cracking and suppression of filming.

  The photoreceptor according to the present invention can be used in an image forming apparatus. The process cartridge and the image forming apparatus according to the present invention can be used for forming an image on a recording medium.

Claims (15)

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer,
The photosensitive layer is a single layer, and the photosensitive layer contains a charge generator, an electron transport agent, a hole transport agent, and a binder resin,
The binder resin is an electrophotographic photosensitive member containing a polycarbonate resin represented by the following general formula (1).

(In the general formula (1),
R ¹ , R ² , R ³ and R ⁴ each independently have a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a substituent. Represents an optionally substituted alkoxy group having 1 to 6 carbon atoms or a phenyl group optionally having a substituent,
X has a single bond, an alkylene group having 2 to 18 carbon atoms which may have a substituent, an alkylidene group having 1 to 18 carbon atoms which may have a substituent, and a substituent. A cycloalkylene group having 5 to 15 carbon atoms which may be substituted, a cycloalkylidene group having 5 to 15 carbon atoms which may have a substituent, -S-, -SO-, -O- or -CO-
m and n each independently represent a positive number, m + n = 1.00, and 0.30 ≦ n ≦ 0.70. )   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a Vickers hardness at 40 ° C. of 20.0 HV or more. In the general formula (1),
R ¹ , R ² , R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,
The electrophotographic photoreceptor according to claim 1, wherein X represents a cycloalkylidene group having 5 to 15 carbon atoms. The electrophotographic photosensitive member according to claim 1, wherein the polycarbonate resin represented by the general formula (1) is a polycarbonate resin represented by the following general formula (1-A) or (1-B).

(In the general formula (1-A), m _A and n _A each independently represents a positive number, m _A + n _A = 1.00, and 0.30 ≦ n _A ≦ 0.70. And
In the general formula (1-B), m _B and n _B each independently represent a positive number, m _B + n _B = 1.00, and 0.30 ≦ n _B ≦ 0.70. is there. ) The electrophotographic image according to claim 1, wherein the polycarbonate resin represented by the general formula (1) is a polycarbonate resin represented by the following chemical formula (1-1), (1-2), or (1-3). Photoconductor.

  The electrophotographic photosensitive member according to claim 1, wherein 0.30 ≦ n ≦ 0.50 in the general formula (1). The electrophotographic photosensitive member according to claim 1, wherein the electron transfer agent includes a compound represented by the following general formula (2).

(In the general formula (2), R ⁵ is
An alkyl group having 1 or more and 8 or less carbon atoms having one or more halogen atoms,
A cycloalkyl group having 3 or more and 10 or less carbon atoms having one or more halogen atoms,
An aryl group having 6 or more and 14 or less carbon atoms, which may have one or more halogen atoms and may have an alkyl group having 1 to 6 carbon atoms,
It represents a 5- to 14-membered heterocyclic group having 1 or more halogen atoms, or an aralkyl group having 7 to 20 carbon atoms having one or more halogen atoms. ) The electrophotographic photosensitive member according to claim 7, wherein in the general formula (2), R ⁵ represents an alkyl group having 1 to 8 carbon atoms and having one or more halogen atoms. The electrophotographic photosensitive member according to claim 1, wherein the hole transport agent includes a compound represented by the following general formula (3).

(In the general formula (3), R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ are each independently Represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.) In the general formula (3), R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ are each independently The electrophotographic photosensitive member according to claim 9, which represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.   A process cartridge comprising the electrophotographic photosensitive member according to claim 1. The electrophotographic photosensitive member according to claim 1, a charging unit, an exposure unit, a developing unit, and a transfer unit,
The charging unit charges the surface of the electrophotographic photosensitive member,
The exposing unit exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image on the surface of the electrophotographic photosensitive member;
The developing unit develops the electrostatic latent image as a toner image,
The transfer unit transfers the toner image from the electrophotographic photosensitive member to a recording medium,
The image forming apparatus, wherein the electrophotographic photosensitive member is in contact with the recording medium when the transfer unit transfers the toner image from the electrophotographic photosensitive member to the recording medium.   The image forming apparatus according to claim 12, wherein the developing unit develops the electrostatic latent image as the toner image while being in contact with the electrophotographic photosensitive member.   The image forming apparatus according to claim 12, wherein the developing unit cleans the surface of the electrophotographic photosensitive member.   The image forming apparatus according to claim 12, wherein the charging unit is a charging roller.

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