JP2018054744A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that is excellent in potential stability and crack resistance and can reduce exposure memory.SOLUTION: An electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer. The photosensitive layer is a single-layer. The photosensitive layer contains a charge generating agent, a hole transport agent, an electron transport agent, a binder resin, and an additive. The content of the electron transport agent is larger than the content of the hole transport agent. The content of the additive is 10 parts by mass or more and 40 parts by mass or less based on 100 parts by mass of the binder resin. The additive is a compound represented by the general formula (ADD1) and another specific structure.SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

  In recent years, in order to form an image at a high speed, an image forming apparatus employing a static elimination-less method has been studied. The image forming apparatus described in Patent Document 1 employs a static elimination-less method. The image forming apparatus includes an electrophotographic photosensitive member. The electrophotographic photoreceptor includes a photosensitive layer containing a tristyryltriphenylamine compound having a specific structure on a conductive substrate.

JP 2011-64963 A

  However, since the image forming apparatus adopting the static elimination-less method does not include a static elimination unit, the surface potential of the electrophotographic photosensitive member is likely to be non-uniform, the potential stability of the photosensitive member is lowered, and an exposure memory is generated. There are things to do. In the image forming apparatus described in Patent Document 1, the improvement in the potential stability of the photoreceptor and the suppression of the occurrence of exposure memory have been insufficient.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an electrophotographic photosensitive member that is excellent in potential stability and crack resistance and can suppress exposure memory. Another object of the present invention is to provide a process cartridge and an image forming apparatus that are excellent in potential stability and crack resistance and can suppress exposure memory by including such an electrophotographic photosensitive member.

  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, a hole transport agent, an electron transport agent, a binder resin, and an additive. The content of the electron transport agent is greater than the content of the hole transport agent. The content of the additive is 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin. The additive is a compound represented by the following general formula (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6).

In the general formula (ADD1), R ¹¹¹ and R ¹¹² are each independently an alkyl group having 1 to 6 carbon atoms which may have an aryl group having 6 to 14 carbon atoms, and the number of carbon atoms Represents an aryl group or a nitro group of 6 or more and 14 or less. m1 and m2 each independently represents an integer of 0 or more and 5 or less.

In the general formula (ADD2), R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ , R ¹²⁶ , R ¹²⁷ , R ¹²⁸ and R ¹²⁹ are each independently a hydrogen atom, a hydroxyl group, a halogen atom or An alkyl group having 1 to 6 carbon atoms is represented.

In the general formula (ADD3), R ¹³¹ , R ¹³² and R ¹³³ each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. n1, n2 and n3 each independently represents an integer of 0 or more and 5 or less.

In the general formula (ADD4), R ¹⁴¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ¹⁴⁶ each independently represent a hydrogen atom or an alkyl group having 4 to 8 carbon atoms. At least one of R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ¹⁴⁶ represents an alkyl group having 4 to 8 carbon atoms. R ¹⁴⁴ represents —R ¹⁴⁷ —CO—O—R ¹⁴⁸ —, and R ¹⁴⁷ and R ¹⁴⁸ each independently represents an alkylene group having 1 to 8 carbon atoms.

In the general formula (ADD5), R ¹⁵¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ each independently represent a hydrogen atom or an alkyl group having 4 to 8 carbon atoms. At least one of R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ represents an alkyl group having 4 to 8 carbon atoms. R ¹⁵⁴ is a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms having an aryl group having 6 to 14 carbon atoms. Or an alkyl group having 1 to 8 carbon atoms having an alkoxycarbonyl group having 1 to 20 carbon atoms.

In the general formula (ADD6), R ¹⁶¹ and R ¹⁶² each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. p1 and p2 each independently represent an integer of 0 or more and 5 or less.

  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 to a positive polarity. 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 transfer target.

  According to the electrophotographic photoreceptor of the present invention, it is possible to improve potential stability and crack resistance and to suppress exposure memory. In addition, according to the process cartridge and the image forming apparatus of the present invention, by providing such an electrophotographic photosensitive member, it is possible to improve potential stability and crack resistance and to suppress exposure memory.

(A), (b) and (c) are sectional views showing an example of an electrophotographic photoreceptor according to an embodiment of the present invention. 2 is an example of a CuKα characteristic X-ray diffraction spectrum chart of titanyl phthalocyanine used in the electrophotographic photosensitive member according to the embodiment of the present invention. It is an example of a differential scanning calorimetry spectrum chart of titanyl phthalocyanine used in the electrophotographic photosensitive member according to the embodiment of the present invention. 1 is a diagram illustrating an example of a configuration of an image forming apparatus, and the image forming apparatus includes an electrophotographic photosensitive member according to an embodiment of the present invention. It is a figure which shows another example of a structure of an image forming apparatus, and this image forming apparatus is provided with the electrophotographic photoreceptor which concerns on embodiment of this 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.

  Hereinafter, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 4 carbon atoms, carbon An alkyl group having 1 to 3 atoms, an alkyl group having 4 to 8 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, and 1 to 6 carbon atoms An alkoxy group having 6 to 14 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an aralkyl group having 7 to 9 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, carbon A cycloalkane having 5 to 7 atoms, an alkylene group having 1 to 8 carbon atoms and an alkylene group having 1 to 6 carbon atoms, unless otherwise specified, 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).

  An alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 4 carbon atoms, 1 to 3 carbon atoms The following alkyl groups and alkyl groups having 4 to 8 carbon atoms are each linear or branched and unsubstituted. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group. Group, neopentyl group, 1,2-dimethylpropyl group, hexyl group, heptyl group or octyl group. Examples of the alkyl group having 1 to 6 carbon atoms are examples having 1 to 6 carbon atoms among the examples of the alkyl group having 1 to 8 carbon atoms. The alkyl group having 1 to 5 carbon atoms is an example having 1 to 5 carbon atoms among the alkyl groups having 1 to 8 carbon atoms. The alkyl group having 1 to 4 carbon atoms is an example having 1 to 4 carbon atoms among the examples of alkyl groups having 1 to 8 carbon atoms. The alkyl group having 1 to 3 carbon atoms is an example having 1 to 3 carbon atoms among the alkyl groups having 1 to 8 carbon atoms. The alkyl group having 4 to 8 carbon atoms is an example having 4 to 8 carbon atoms among the examples of alkyl groups having 1 to 8 carbon atoms.

  The alkenyl group having 2 to 6 carbon atoms 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 vinyl group (ethenyl group), propenyl group, butenyl group, pentenyl group, pentadienyl group, hexenyl group, and hexadienyl group.

  The alkoxy group having 1 to 8 carbon atoms and the alkoxy group having 1 to 6 carbon atoms are each linear or branched and unsubstituted. Examples of the alkoxy group having 1 to 8 carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, n-pentoxy group, An isopentoxy group, neopentoxy group, hexyloxy group, heptyloxy group or octyloxy group can be mentioned. Examples of the alkoxy group having 1 to 6 carbon atoms are examples having 1 to 6 carbon atoms among the alkoxy groups having 1 to 8 carbon atoms.

  Examples of the aryl group having 6 to 14 carbon atoms include an unsubstituted aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms and an unsubstituted aromatic condensed bicyclic carbon group having 6 to 14 carbon atoms. A hydrogen group or an unsubstituted aromatic condensed tricyclic hydrocarbon group having 6 to 14 elemental atoms. 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.

  The aralkyl group having 7 to 20 carbon atoms and the aralkyl group having 7 to 9 carbon atoms are unsubstituted. The aralkyl group having 7 to 20 carbon atoms is a group in which an aryl group having 6 to 14 carbon atoms and an alkyl group having 1 to 6 carbon atoms are bonded. The alkyl group having 1 to 6 carbon atoms in the aralkyl group having 7 to 20 carbon atoms is linear or branched and unsubstituted. Examples of the aralkyl group having 7 to 20 carbon atoms include a phenylmethyl group (benzyl group), a 2-phenylethyl group (phenethyl group), a 1-phenylethyl group, a 3-phenylpropyl group, and a 4-phenylbutyl group. Is mentioned. Examples of the aralkyl group having 7 to 9 carbon atoms are phenylmethyl group (benzyl group), 2-phenylethyl group (phenethyl group), 1-phenylethyl group or 3-phenylpropyl group.

  A cycloalkyl group having 3 to 10 carbon atoms is unsubstituted. Examples of the cycloalkyl group having 3 to 10 carbon atoms 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.

  A cycloalkane having 5 to 7 carbon atoms is unsubstituted. Examples of the cycloalkane having 5 to 7 carbon atoms include cyclopentane, cyclohexane, and cycloheptane.

  The alkylene group having 1 to 8 carbon atoms and the alkylene group having 1 to 6 carbon atoms are each linear or branched and unsubstituted. Examples of the alkylene group having 1 to 8 carbon atoms are methylene group, ethylene group, n-propylene group, 1-methylethylene group, 2-methylethylene group, n-butylene group, 1-methylpropylene group, 2- Methylpropylene group, 3-methylpropylene group, 1,1-dimethylethylene group, 1,2-dimethylethylene group, 2,2-dimethylethylene group, ethylmethylmethylene group, pentylene group, hexylene group, heptylene group or octylene Groups. Examples of the alkylene group having 1 to 6 carbon atoms are examples having 1 to 6 carbon atoms among the alkylene groups having 1 to 8 carbon atoms.

<1. Photoconductor>
The present embodiment relates to an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor). The photoreceptor is used in an electrophotographic image forming apparatus. According to the photoconductor of this embodiment, potential stability and crack resistance can be improved, and exposure memory can be suppressed.

  When an image is formed at a high speed, it is necessary to increase the sensitivity of the photoreceptor. For this purpose, it is preferable to contain as much charge generating agent and hole transporting agent as possible in the photosensitive layer of the photoreceptor. However, a photosensitive member containing a large amount of charge generating agent and a large amount of hole transport agent in the photosensitive layer tends to gradually decrease the charged potential of the photosensitive member when charging of the photosensitive member is repeated in image formation. That is, the potential stability of the photoconductor tends to decrease. In addition, an exposure memory may be generated on a photoreceptor in which a photosensitive layer contains a large amount of charge generating agent and a large amount of hole transporting agent. The exposure memory is a phenomenon in which the exposure region (image region) of the photosensitive member whose potential has been lowered by exposure is not charged to a desired positive potential in the next charging step. When an exposure memory is generated on the photoreceptor, a positive ghost is generated on the formed image. The positive ghost is an image defect in which a region corresponding to the exposure region on the periphery in front of the photoreceptor is blackened in the formed image.

  Here, in the photosensitive layer of the photoreceptor of this embodiment, the content of the electron transport agent is larger than the content of the hole transport agent. Usually, when the photoreceptor includes a single-layer photosensitive layer containing a charge generating agent, an electron transporting agent and a hole transporting agent, the content of the hole transporting agent is larger than the content of the electron transporting agent. For ease of understanding, the reason is explained. When the photoreceptor is exposed during image formation, electrons and holes are generated from the charge generating agent in the photosensitive layer. The generated electrons are transported to the surface of the photosensitive layer by the electron transport agent. The generated holes are transported to the conductive substrate by the hole transport agent. The transmittance of the exposed light is high near the surface of the photosensitive layer, and low at the deep part of the photosensitive layer (on the conductive substrate side). Therefore, many electrons and holes tend to be generated from the charge generating agent present near the surface of the photosensitive layer having a high transmittance of the exposed light. When electrons and holes are generated from the charge generating agent present near the surface of the photosensitive layer, the distance of movement of holes to the conductive substrate is longer than the distance of movement of electrons to the surface of the photosensitive layer. Therefore, it is common to contain more hole transporting agents than electron transporting agents. However, the present inventors diligently studied that the potential stability of the photoreceptor can be improved and the occurrence of exposure memory can be suppressed by making the content of the electron transport agent greater than the content of the hole transport agent. I found it.

  However, when the amount of the electron transport agent, hole transport agent and charge generator contained in the photosensitive layer increases, cracks may occur in the photosensitive layer. This is because cracks are easily generated in the binder resin due to the presence of the electron transport agent, the hole transport agent and the charge generator in the binder resin. Here, the photosensitive layer of the present embodiment has, as an additive, a compound represented by the general formula (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6) (hereinafter referred to as compound ( ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6)). Furthermore, the content of the compound (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6) is 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin. is there. Thus, it is considered that fine voids generated in the photosensitive layer are filled with the compounds (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6). As a result, the crack resistance of the photoreceptor can be improved.

  Hereinafter, the structure of the photoconductor 30 will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing an example of the photoreceptor 30 according to the present embodiment.

  As shown in FIG. 1A, the photoreceptor 30 includes, for example, a conductive substrate 32 and a photosensitive layer 34. The photosensitive layer 34 is a single layer. The photoconductor 30 is a so-called single-layer type photoconductor provided with a single-layer photoconductive layer 34.

  As shown in FIG. 1B, the photoreceptor 30 may include a conductive substrate 32, a photosensitive layer 34, and an intermediate layer 36 (undercoat layer). The intermediate layer 36 is provided between the conductive substrate 32 and the photosensitive layer 34. As shown in FIG. 1A, the photosensitive layer 34 may be provided directly on the conductive substrate 32. As shown in FIG. 1B, the photosensitive layer 34 is formed on the conductive substrate 32 as an intermediate layer. It may be provided indirectly via 36.

  As shown in FIG. 1C, the photoreceptor 30 may include a conductive substrate 32, a photosensitive layer 34, and a protective layer 38. The protective layer 38 is provided on the photosensitive layer 34.

  The thickness of the photosensitive layer 34 is not particularly limited as long as the function as the photosensitive layer can be sufficiently expressed. The thickness of the photosensitive layer 34 is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

  The photosensitive layer 34 contains a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and an additive. The additive is a compound represented by the general formula (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6). Hereinafter, the compounds represented by the general formulas (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) and (ADD6) are respectively represented by the compounds (ADD1), (ADD2), (ADD3), (ADD3), ADD4), (ADD5), and (ADD6). The charge generating agent, the hole transport agent, the electron transport agent, the binder resin, and the additive are contained in one layer (single layer) of the photosensitive layer 34.

  The structure of the photoreceptor 30 has been described above with reference to FIGS. 1 (a) to 1 (c). Next, the elements of the photoreceptor will be described.

<1-1. Conductive substrate>
As an example of the conductive substrate, a conductive substrate formed of a conductive material can be given. Another example of the conductive substrate includes a conductive substrate including a coating layer made of a material having conductivity. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. 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.

<1-2. Photosensitive layer>
The photosensitive layer comprises a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and an additive compound (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or ( ADD6). In the photosensitive layer, the content of the electron transport agent is larger than the content of the hole transport agent. The ratio of the mass of the electron transport agent to the mass of the hole transporting material contained in the photosensitive layer _{(M HTM) (M ETM)} (M ETM / M HTM) is greater than 1.00. When the content of the electron transport agent is larger than the content of the hole transport agent, the potential stability of the photoreceptor can be improved. Moreover, generation | occurrence | production of the exposure memory in a formation image can be suppressed because there is more content of an electron transport agent than content of a hole transport agent. The ratio (M _ETM / M _HTM ) is preferably greater than 1.00 and not greater than 1.50. When the photosensitive layer contains two or more types of electron transport agents, the ratio (M _ETM / M _HTM ) is 2 or more types relative to the mass of the hole transport agent (M _HTM ) contained in the photosensitive layer. This corresponds to the ratio of the total mass (M _ETM ) of the electron transfer agent.

(Additive)
The additive is a compound (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6). The compounds (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) and (ADD6) are each a crack inhibitor.

  The compound (ADD1) is represented by the general formula (ADD1).

In the general formula (ADD1), R ¹¹¹ and R ¹¹² are each independently an alkyl group having 1 to 6 carbon atoms which may have an aryl group having 6 to 14 carbon atoms, and 6 carbon atoms. It represents an aryl group or a nitro group of 14 or more. m1 and m2 each independently represents an integer of 0 or more and 5 or less.

When m1 represents an integer of 2 or more and 5 or less, the plurality of R ¹¹¹ may be the same or different. When m2 represents an integer of 2 or more and 5 or less, the plurality of R ¹¹² may be the same or different.

The aryl group having 6 to 14 carbon atoms represented by R ¹¹¹ and R ¹¹² in the general formula (ADD1) is preferably a phenyl group.

The alkyl group having 1 to 6 carbon atoms represented by R ¹¹¹ and R ¹¹² in the general formula (ADD1) is preferably a methyl group. The alkyl group having 1 to 6 carbon atoms may have an aryl group having 6 to 14 carbon atoms. As such an aryl group having 6 to 14 carbon atoms, a phenyl group is preferable.

  It is preferable that m1 and m2 each independently represent 0 or 1. m1 preferably represents 0. m2 preferably represents 1.

The bonding position of R ¹¹¹ and R ¹¹² is not particularly limited. R ¹¹¹ may be located at any of the ortho, meta and para positions of the phenyl group. R ¹¹² may be located at any of the ortho, meta, and para positions of the phenyl group, and is preferably located at the meta position.

R ¹¹¹ and R ¹¹² in the general formula (ADD1) preferably represent an aryl group having 6 to 14 carbon atoms, and more preferably a phenol group.

  A preferred example of the compound (ADD1) is a compound represented by the chemical formula (ADD1-1) (hereinafter sometimes referred to as the compound (ADD1-1)).

  The compound (ADD2) is represented by the general formula (ADD2).

In general formula (ADD2), R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ , R ¹²⁶ , R ¹²⁷ , R ¹²⁸ and R ¹²⁹ are each independently a hydrogen atom, hydroxyl group, halogen atom or carbon An alkyl group having 1 to 6 atoms is represented.

As the halogen atom represented by R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ , R ¹²⁶ , R ¹²⁷ , R ¹²⁸ and R ^{129 in the} general formula (ADD2), a chloro group is preferable.

The alkyl group having 1 to 6 carbon atoms represented by R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ , R ¹²⁶ , R ¹²⁷ , R ¹²⁸ and R ^{129 in the} general formula (ADD2) is a carbon atom. An alkyl group having a number of 1 to 4 is preferred, and a methyl group or a tert-butyl group is more preferred.

  A preferred example of the compound (ADD2) is a compound represented by the chemical formula (ADD2-1) (hereinafter sometimes referred to as the compound (ADD2-1)).

  The compound (ADD3) is represented by the general formula (ADD3).

In General Formula (ADD3), R ¹³¹ , R ^132, and R ¹³³ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. n1, n2 and n3 each independently represents an integer of 0 or more and 5 or less.

When n1 represents an integer of 2 or more and 5 or less, the plurality of R ¹³¹ may be the same or different. When n2 represents an integer of 2 or more and 5 or less, the plurality of R ¹³² may be the same or different. When n3 represents an integer of 2 or more and 5 or less, the plurality of R ¹³³ may be the same or different.

As the alkyl group having 1 to 6 carbon atoms represented by R ¹³¹ , R ¹³² and R ^{133 in the} general formula (ADD3), a methyl group is preferable.

As the alkoxy group having 1 to 6 carbon atoms represented by R ¹³¹ , R ¹³² and R ^{133 in the} general formula (ADD3), a methoxy group is preferable.

R ¹³¹ , R ¹³² and R ^{133 in} general formula (ADD3) preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group. In the general formula (ADD3), n1, n2, and n3 each preferably represent 1.

The bonding position of R ¹³¹ , R ¹³² and R ¹³³ is not particularly limited. R ¹³¹ may be located at any of the ortho, meta, and para positions of the phenyl group, and is preferably located at the para position. R ¹³² may be located at any of the ortho, meta, and para positions of the phenyl group, and is preferably located at the para position. R ¹³³ may be located at any of the ortho, meta, and para positions of the phenyl group, and is preferably located at the para position.

  A suitable example of the compound (ADD3) is a compound represented by the chemical formula (ADD3-1) (hereinafter sometimes referred to as the compound (ADD3-1)).

  The compound (ADD4) is represented by the general formula (ADD4). The compound (ADD4) is a so-called hindered phenol compound.

In General Formula (ADD4), R ¹⁴¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ¹⁴⁶ each independently represent a hydrogen atom or an alkyl group having 4 to 8 carbon atoms. However, at least one of R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ¹⁴⁶ represents an alkyl group having 4 to 8 carbon atoms. R ¹⁴⁴ represents —R ¹⁴⁷ —CO—O—R ¹⁴⁸ —, and R ¹⁴⁷ and R ¹⁴⁸ each independently represents an alkylene group having 1 to 8 carbon atoms.

As the alkyl group having 1 to 8 carbon atoms represented by R ¹⁴¹ in the general formula (ADD4), an octyl group is preferable.

As the alkyl group having 4 to 8 carbon atoms represented by R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ^{146 in the} general formula (ADD4), an alkyl group having 4 or 5 carbon atoms is preferable, and a tert-butyl group or A 1,1-dimethylpropyl group is more preferred.

R ¹⁴⁴ in the general formula (ADD4) represents —R ¹⁴⁷ —CO—O—R ¹⁴⁸ —. R ¹⁴⁷ and R ¹⁴⁸ each represent an alkylene group having 1 to 8 carbon atoms. The alkylene group having 1 to 8 carbon atoms represented by R ¹⁴⁷ and R ¹⁴⁸ is preferably a methylene group (—CH ₂ —) or an ethylene group (—CH ₂ —CH ₂ —).

In general formula (ADD4), R ¹⁴¹ preferably represents a hydrogen atom. R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ¹⁴⁶ each independently represent a hydrogen atom or an alkyl group having 4 to 8 carbon atoms. It is preferable that one or two of R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ¹⁴⁶ represent an alkyl group having 4 to 8 carbon atoms, and one of R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ^{146 is} the number of carbon atoms. More preferably, it represents 4 or more and 8 or less alkyl groups. R ¹⁴⁴ represents —R ¹⁴⁷ —CO—O—R ¹⁴⁸ —. R ¹⁴⁷ and R ¹⁴⁸ preferably each independently represent a methylene group (—CH ₂ —) or an ethylene group (—CH ₂ —CH ₂ —).

  A preferable example of the compound (ADD4) is a compound represented by the chemical formula (ADD4-1) (hereinafter sometimes referred to as the compound (ADD4-1)).

  The compound (ADD5) is represented by the general formula (ADD5). The compound (ADD5) is a so-called hindered phenol compound.

In General Formula (ADD5), R ¹⁵¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ each independently represent a hydrogen atom or an alkyl group having 4 to 8 carbon atoms. However, at least one of R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ represents an alkyl group having 4 to 8 carbon atoms. R ¹⁵⁴ is a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms having an aryl group having 6 to 14 carbon atoms. Or an alkyl group having 1 to 8 carbon atoms having an alkoxycarbonyl group having 1 to 20 carbon atoms.

The alkyl group having 1 to 8 carbon atoms represented by R ¹⁵¹ in the general formula (ADD5) is preferably an octyl group.

As the alkyl group having 4 to 8 carbon atoms represented by R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ^{156 in the} general formula (ADD5), an alkyl group having 4 or 5 carbon atoms is preferable, and a tert-butyl group or A 1,1-dimethylpropyl group is more preferred.

The alkoxy group having 1 to 8 carbon atoms represented by R ¹⁵⁴ in the general formula (ADD5) is preferably a methoxy group or an octyloxy group.

The alkyl group having 1 to 8 carbon atoms represented by R ¹⁵⁴ in the general formula (ADD5) is preferably an alkyl group having 1 to 3 carbon atoms, and preferably a methyl group or an ethyl group. The alkyl group having 1 to 8 carbon atoms may have an aryl group having 6 to 14 carbon atoms or an alkoxycarbonyl group having 1 to 20 carbon atoms. As the aryl group having 6 to 14 carbon atoms, the alkyl group having 1 to 8 carbon atoms preferably has a phenyl group. As the alkoxycarbonyl group having 1 to 20 carbon atoms in the alkyl group having 1 to 8 carbon atoms, an octadecanoxycarbonyl group is preferable.

R ¹⁵¹ in the general formula (ADD5) preferably represents a hydrogen atom. R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ each independently represent a hydrogen atom or an alkyl group having 4 to 8 atoms. It is preferable that one or two of R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ represent an alkyl group having 4 to 8 carbon atoms, and two of R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ are carbon atoms. More preferably, it represents 4 or more and 8 or less alkyl groups. R ¹⁵⁴ preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and particularly preferably represents a methyl group.

  A preferred example of the compound (ADD5) is a compound represented by the chemical formula (ADD5-1) (hereinafter sometimes referred to as the compound (ADD5-1)).

  The compound (ADD6) is represented by the general formula (ADD6).

In General Formula (ADD6), R ¹⁶¹ and R ¹⁶² each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. p1 and p2 each independently represent an integer of 0 or more and 5 or less.

When p1 represents an integer of 2 or more and 5 or less, the plurality of R ¹⁶¹ may be the same or different. When p2 represents an integer of 2 or more and 5 or less, the plurality of R ¹⁶² may be the same or different.

R ¹⁶¹ and R ¹⁶² in the general formula (ADD6) are preferably an alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group.

  In the general formula (ADD6), p1 and p2 each preferably represent 1.

The bonding position of R ¹⁶¹ and R ¹⁶² is not particularly limited. R ¹⁶¹ may be located at any of the ortho, meta, and para positions of the phenyl group, and is preferably located at the ortho position. R ¹⁶² may be located at any of the ortho, meta, and para positions of the phenyl group, and is preferably located at the ortho position.

  A suitable example of the compound (ADD6) is a compound represented by the chemical formula (ADD6-1) (hereinafter sometimes referred to as the compound (ADD6-1)).

  The content of the compound (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6) as the additive is 10 parts by mass or more and 40 parts by mass with respect to 100 parts by mass of the binder resin. The following is preferable. When the content of the additive is less than 10 parts by mass with respect to 100 parts by mass of the binder resin, the potential stability and crack resistance of the photoreceptor are lowered. When the content of the additive is more than 40 parts by mass with respect to 100 parts by mass of the binder resin, the crack resistance of the photoreceptor is lowered.

  In addition to the compound (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6), the photosensitive layer is composed of the compound (ADD1), (ADD2), (ADD3), (ADD4), (ADD4), Additives other than (ADD5) and (ADD6) (hereinafter, may be referred to as other additives) may be contained. Other additives are appropriately selected from known additives. The content of the compound (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6) is 80% by mass or more based on the mass of the additive contained in the photosensitive layer. Is more preferable, 90% by mass is more preferable, and 100% by mass is particularly preferable.

(Electron transfer agent)
Examples of electron transfer agents include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds Examples thereof include compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, or dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds.

  Suitable examples of the electron transporting agent are compounds represented by the following general formula (ET1), (ET2), (ET3), (ET4) or (ET5). Hereinafter, the compounds represented by the general formula (ET1), (ET2), (ET3), (ET4) or (ET5) are converted into the compounds (ET1), (ET2), (ET3), (ET4) or (ET, respectively). ET5).

In the general formula (ET1), (ET2), (ET4) and ^{(ET5), R 1, R} 2, R 3, R 4, R 5, R 8, R 9, R 10, R 11, R 12, R ¹³ and R ¹⁴ are each independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a carbon atom which may have a substituent. It represents an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, and an aryl group having 6 to 14 carbon atoms which may have a substituent. In General Formula (ET2), W represents —CO—O— or —CO—.

In General Formula (ET3), R ⁶ and R ⁷ are each independently an aryl group having 6 to 14 carbon atoms; 6 or more carbon atoms having at least one alkyl group having 1 to 6 carbon atoms An aryl group having 14 or less aryl atoms; an aryl group having 6 to 14 carbon atoms having a phenylcarbonyl group; an aralkyl group having 7 to 20 carbon atoms; a carbon which may have an alkoxy group having 1 to 6 carbon atoms Represents a group selected from the group consisting of an alkyl group having 1 to 8 atoms; and a cycloalkyl group having 3 to 10 carbon atoms. The selected group may be substituted with one or more halogen atoms.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R in the general formulas (ET1), (ET2), (ET4) and (ET5) ^The halogen atom (halogen group) represented by ¹³ and R ¹⁴ is preferably a chlorine atom (chloro group).

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R in the general formulas (ET1), (ET2), (ET4) and (ET5) The alkyl group having 1 to 6 carbon atoms represented by ¹³ and R ¹⁴ is preferably an alkyl group having 1 to 5 carbon atoms, and a methyl group, a tert-butyl group or a 1,1-dimethylpropyl group is More preferred. The alkyl group having 1 to 6 carbon atoms may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms which may further have a substituent, or a cyano group. The substituent that the alkyl group having 1 to 6 carbon atoms has is preferably an aryl group having 6 to 14 carbon atoms, and more preferably a phenyl group. The number of substituents is not particularly limited, but is preferably 3 or less. Examples of the substituent further included in the aryl group having 6 to 14 carbon atoms as the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, and an alkoxy having 1 to 6 carbon atoms. Group, nitro group, cyano group, alkanoyl group having 2 to 7 carbon atoms (carbonyl group having an alkyl group having 1 to 6 carbon atoms), benzoyl group, phenoxy group, alkoxy having 2 to 7 carbon atoms Examples thereof include a carbonyl group (a carbonyl group having an alkoxy group having 1 to 6 carbon atoms) or a phenoxycarbonyl group.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R in the general formulas (ET1), (ET2), (ET4) and (ET5) The alkenyl group having 2 to 6 carbon atoms represented by ¹³ and R ¹⁴ may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, and a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R in the general formulas (ET1), (ET2), (ET4) and (ET5) The alkoxy group having 1 to 6 carbon atoms represented by ¹³ and R ¹⁴ may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, and a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R in the general formulas (ET1), (ET2), (ET4) and (ET5) The aryl group having 6 to 14 carbon atoms represented by ¹³ and R ¹⁴ is preferably a phenyl group. The aryl group having 6 to 14 carbon atoms may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkanoyl having 2 to 7 carbon atoms. Group (carbonyl group having an alkyl group having 1 to 6 carbon atoms), benzoyl group, phenoxy group, alkoxycarbonyl group having 2 to 7 carbon atoms (carbonyl group having an alkoxy group having 1 to 6 carbon atoms) ), A phenoxycarbonyl group, an aryl group having 6 to 14 carbon atoms, or a biphenyl group. The aryl group having 6 to 14 carbon atoms is preferably an alkyl group or nitro group having 1 to 6 carbon atoms, and more preferably a methyl group, an ethyl group, or a nitro group. The number of substituents is not particularly limited, but is preferably 3 or less.

R ¹ and R ² in the general formula (ET1) each preferably independently represent an alkyl group having 1 to 6 carbon atoms. R ¹ and R ² may represent the same group among alkyl groups having 1 to 6 carbon atoms, or may represent different groups among alkyl groups having 1 to 6 carbon atoms. Each of R ¹ and R ² preferably represents a tert-butyl group or a 1,1-dimethylpropyl group, and more preferably represents a 1,1-dimethylpropyl group.

R ³ , R ⁴ and R ^{5 in} general formula (ET2) are each independently a hydrogen atom or an alkyl having 1 to 6 carbon atoms which may have an aryl group having 6 to 14 carbon atoms. And an aryl group having 6 to 14 carbon atoms which may have a group or a nitro group. R ³ , R ⁴ and R ⁵ 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 6 carbon atoms. More preferably, it represents an aryl group of 14 or less. R ³ preferably represents an alkyl group having 1 to 6 carbon atoms having an aryl group having 6 to 14 carbon atoms, and preferably represents an alkyl group having 1 to 6 carbon atoms having a phenyl group. More preferably, it represents a phenylmethyl group. R ⁴ preferably represents an aryl group having 6 to 14 carbon atoms, and more preferably a phenyl group. R ⁵ preferably represents a hydrogen atom. W in the general formula (ET2) preferably represents -CO-O-.

  The compound (ET3) preferably satisfies the condition (3-A) or (3-B), and more preferably satisfies the condition (3-B).

Hereinafter, the condition (3-A) will be described. In the case where the condition (3-A) is satisfied, R ⁶ and R ⁷ in the general formula (ET3) are each independently 6 or more carbon atoms having at least one alkyl group having 1 to 6 carbon atoms. 14 or less aryl groups are represented.

When the compound (ET3) satisfies the condition (3-A), the aryl group having 6 to 14 carbon atoms represented by R ⁶ and R ⁷ is preferably a phenyl group. The aryl group having 6 to 14 carbon atoms represented by R ⁶ and R ⁷ may have at least one (preferably one or two) alkyl group having 1 to 6 carbon atoms. The alkyl group having 1 to 6 carbon atoms, which the aryl group having 6 to 14 carbon atoms has, is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group. An example of an aryl group having 6 to 14 carbon atoms and having at least one alkyl group having 1 to 6 carbon atoms represented by R ⁶ and R ⁷ is a 2-ethyl-6-methylphenyl group.

Hereinafter, the condition (3-B) will be described. In the case where the condition (3-B) is satisfied, R ⁶ and R ⁷ in the general formula (ET3) are each independently an aryl group having 6 to 14 carbon atoms; alkyl having 1 to 6 carbon atoms An aryl group having 6 to 14 carbon atoms having at least one group; an aryl group having 6 to 14 carbon atoms having a phenylcarbonyl group; an aralkyl group having 7 to 20 carbon atoms; 1 to 8 carbon atoms And a group selected from the group consisting of the following alkyl groups; and a cycloalkyl group having 3 to 10 carbon atoms. A group selected from such groups may be substituted with one or more halogen atoms. At least one of R ⁶ and R ⁷ has one or more halogen atoms. That is, the compound (ET3) satisfying the condition (3-B) has a halogen atom as essential.

When the compound (ET3) satisfies the condition (3-B), in the general formula (ET3), the aryl group having 6 to 14 carbon atoms represented by R ⁶ and R ⁷ is preferably a phenyl group. The aryl group having 6 to 14 carbon atoms may have a substituent. Examples of such a substituent include a halogen atom, an alkyl group having 1 to 6 carbon atoms (preferably an alkyl group having 1 to 3 carbon atoms), and a phenylcarbonyl group. As such a substituent, a chlorine atom, a methyl group, an ethyl group or a phenylcarbonyl group is preferable. The number of substituents is preferably an integer of 1 or more and 3 or less. When the aryl group having 6 to 14 carbon atoms is a phenyl group, the position of the substituent in the phenyl group is, for example, an ortho position (o position) or a meta position with respect to the position where the phenyl group is bonded to the nitrogen atom (M-position), para-position (p-position), or at least two of these. An example of the aryl group having 6 to 14 carbon atoms having a substituent may be substituted with one or more (preferably 1 to 3) halogen atoms, and is an alkyl having 1 to 6 carbon atoms. An aryl group having 6 to 14 carbon atoms, which may have at least one group. Suitable examples of the aryl group having 6 to 14 carbon atoms which may be substituted with one or more halogen atoms and may have at least one alkyl group having 1 to 6 carbon atoms include 2, 6-dichlorophenyl group, 2,4,6-trichlorophenyl group or 2-ethyl-6-methylphenyl group. Another example of the aryl group having 6 to 14 carbon atoms having a substituent may be substituted with one or more (preferably 1 or more and 3 or less) halogen atoms, and having a phenylcarbonyl group Or an aryl group having 6 to 14 carbon atoms. A preferred example of the aryl group having 6 to 14 carbon atoms which may be substituted with one or more halogen atoms and may have a phenylcarbonyl group is a 4-chloro-2-phenylcarbonylphenyl group. .

When the compound (ET3) satisfies the condition (3-B), the aralkyl group having 7 to 20 carbon atoms represented by R ⁶ and R ^{7 in} the general formula (ET3) has 7 to 9 carbon atoms. Aralkyl groups are preferred, and 1-phenylethyl groups are more preferred. The aralkyl group having 7 to 20 carbon atoms may have a phenylcarbonyl group. Aralkyl groups having 7 to 20 carbon atoms may be substituted with one or more halogen atoms. Examples of the aralkyl group having 7 to 20 carbon atoms having a halogen atom include 1- (2,4-dichlorophenyl) ethyl group.

As the compound (ET3) satisfying the condition (3-B), a compound in which R ⁶ and R ⁷ in the general formula (ET3) are as follows is preferable. R ⁶ and R ⁷ are each independently an aryl group having 6 to 14 carbon atoms; an aryl group having 6 to 14 carbon atoms having at least one alkyl group having 1 to 6 carbon atoms; A group selected from the group consisting of an aryl group having 6 to 14 carbon atoms having a carbonyl group; and an aralkyl group having 7 to 20 carbon atoms. The selected group may be substituted with one or more halogen atoms. At least one of R ⁶ and R ⁷ has one or more halogen atoms. That is, a suitable example of the compound (ET3) that satisfies the condition (3-B) has a halogen atom as an essential component.

  In addition, the compound (ET3) which satisfy | fills conditions (3-B) can be manufactured by the method as described in an Example, or its alternative method.

R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ in general formula (ET4) each independently preferably represent an alkyl group having 1 to 6 carbon atoms, and represent a methyl group or a tert-butyl group. It is more preferable.

R ¹² and R ^{13 in} general formula (ET5) each independently preferably represent an alkyl group having 1 to 6 carbon atoms, more preferably an isopropyl group or a tert-butyl group, and tert It is particularly preferred to represent a butyl group. R ¹⁴ in the general formula (ET5) preferably represents a halogen atom, and more preferably represents a chlorine atom (chloro group).

  A suitable example of the compound (ET1) is a compound represented by the chemical formula (ET1-1). A suitable example of the compound (ET2) is a compound represented by the chemical formula (ET2-1). A suitable example of the compound (ET3) satisfying the condition (3-A) is a compound represented by the chemical formula (ET3-A1). A suitable example of the compound (ET3) that satisfies the condition (3-B) is a compound represented by the chemical formula (ET3-B1), (ET3-B2), or (ET3-B3). A suitable example of the compound (ET4) is a compound represented by the chemical formula (ET4-1). A suitable example of the compound (ET5) is a compound represented by the chemical formula (ET5-1). Hereinafter, chemical formulas (ET1-1), (ET2-1), (ET3-A1), (ET3-B1), (ET3-B2), (ET3-B3), (ET4-1) and (ET5-1) Are represented by the compounds (ET1-1), (ET2-1), (ET3-A1), (ET3-B1), (ET3-B2), (ET3-B3), (ET4-1), respectively. ) And (ET5-1).

  The number of electron transfer agents is preferably two or more of the compounds (ET1), (ET2), (ET3), (ET4) and (ET5), more preferably two. When the photosensitive layer contains two or more of the compounds (ET1), (ET2), (ET3), (ET4) and (ET5) as electron transporting agents, electron transport to the solvent for forming the photosensitive layer The solubility of the agent can be improved. Thereby, many electron transfer agents can be dissolved in the solvent for forming the photosensitive layer, and the content of the electron transfer agent in the photosensitive layer can be increased. As a result, the potential stability of the photoreceptor can be improved and the occurrence of exposure memory can be suppressed. In addition, when two types are selected from the compounds (ET1), (ET2), (ET3), (ET4) and (ET5), one general formula (for example, any one of the general formulas (ET1) to (ET5)) You may select 2 types of different types of compounds represented by these. When two types are selected from the compounds (ET1), (ET2), (ET3), (ET4) and (ET5), they are represented by one general formula (for example, any one of the general formulas (ET1) to (ET5)). One compound selected may be selected, and one compound represented by another general formula may be selected.

In order to improve the potential stability and crack resistance of the photoreceptor and suppress the occurrence of exposure memory, the photosensitive layer preferably contains two compounds of the following combinations as electron transport agents.
Compound (ET1) and Compound (ET2);
Compound (ET3) that satisfies Compound (ET1) and Condition (3-A);
Compound (ET1) and Compound (ET4);
Compound (ET1) and Compound (ET5);
Compound (ET4) and Compound (ET5);
Compound (ET2) and Compound (ET5);
Compound (ET3) and Compound (ET1) satisfying Condition (3-A); or Compound (ET3) and Compound (ET1) satisfying Condition (3-B).

In order to improve the potential stability and crack resistance of the photoreceptor and to suppress the occurrence of exposure memory, the photosensitive layer more preferably contains two compounds of the following combinations as electron transport agents.
Compound (ET1) and Compound (ET4);
Compound (ET1) and Compound (ET5);
Compound (ET3) and Compound (ET1) that satisfy Compound (ET4) and Compound (ET5); or Condition (3-B).

In order to improve the potential stability and crack resistance of the photoreceptor and suppress the occurrence of exposure memory, the photosensitive layer further preferably contains two compounds of the following combinations as electron transport agents.
Compound (ET3) and compound (ET1) satisfying the condition (3-B).

In order to improve the potential stability of the photoreceptor and to suppress the occurrence of exposure memory, and to particularly improve the crack resistance of the photoreceptor, the photosensitive layer is composed of one additive and two kinds of combinations shown below. It is preferable to contain these electron transport agents.
The additive is the compound (ADD2) and the two electron transporting agents are the compounds (ET1) and (ET4);
The additive is the compound (ADD5), and the two electron transfer agents are the compounds (ET1) and (ET4);
The additive is compound (ADD2) and the two electron transport agents are compounds (ET1) and (ET5);
The additive is compound (ADD2) and the two electron transport agents are compounds (ET4) and (ET5);
The additive is the compound (ADD3) and the two electron transporting agents are the compounds (ET4) and (ET5);
The additive is compound (ADD5) and the two electron transport agents are compounds (ET4) and (ET5);
The additive is the compound (ADD6) and the two electron transport agents are the compounds (ET4) and (ET5); or the additive is the compound (ADD2) and the two electron transport agents are the conditions (3- Compound (ET3) and compound (ET1) satisfying B).

In order to particularly improve the crack resistance and potential stability of the photoreceptor, the photosensitive layer preferably contains one type of additive and two types of electron transport agents in the following combinations.
The additive is the compound (ADD2) and the two electron transporting agents are the compounds (ET1) and (ET4);
The additive is compound (ADD2) and the two electron transport agents are compounds (ET1) and (ET5);
The additive is the compound (ADD2) and the two electron transport agents are the compounds (ET4) and (ET5); or the additive is the compound (ADD2) and the two electron transport agents are the conditions (3- Compound (ET3) and compound (ET1) satisfying B).

In order to achieve a well-balanced improvement in the potential stability and crack resistance of the photoreceptor and the suppression of the occurrence of exposure memory in the formed image, the photosensitive layer is composed of one additive and two kinds of combinations shown below. It preferably contains an electron transport agent.
The additive is the compound (ADD2), and the two electron transfer agents are the compound (ET3) and the compound (ET1) that satisfy the condition (3-B).

In order to achieve a well-balanced improvement in the potential stability and crack resistance of the photoreceptor and the suppression of the occurrence of exposure memory in the formed image, the photosensitive layer is composed of one additive and two kinds of combinations shown below. It preferably contains an electron transport agent.
The additive is the compound (ADD2-1), and the two electron transporting agents are the compound (ET3-B1) and the compound (ET1);
The additive is the compound (ADD2-1) and the two electron transport agents are the compound (ET3-B2) and the compound (ET1); or the additive is the compound (ADD2-1) and the two kinds of electrons The transport agent is the compound (ET3-B3) and the compound (ET1).

In another preferred example for improving the potential stability and crack resistance of the photoreceptor and suppressing the occurrence of exposure memory, the photosensitive layer comprises one additive and two electrons in the following combinations: Including a transport agent.
The additive is the compound (ADD1) and the two electron transporting agents are the compounds (ET1) and (ET2);
The additive is the compound (ADD1), and the two electron transfer agents are the compound (ET1) and (ET3) that satisfies the condition (3-A);
The additive is the compound (ADD1) and the two electron transporting agents are the compounds (ET1) and (ET4);
The additive is the compound (ADD1) and the two electron transporting agents are the compounds (ET1) and (ET5);
The additive is compound (ADD1) and the two electron transport agents are compounds (ET2) and (ET5);
The additive is the compound (ADD1) and the two electron transport agents are the compounds (ET4) and (ET5); or the additive is the compound (ADD1) and the two electron transport agents are the conditions (3- Compounds (ET3) and (ET5) satisfying A).

  The content of one kind of electron transport agent is more preferably 10 parts 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. When two or more types of electron transfer agents are contained, the total content of the two or more types of electron transfer agents is 55 parts by mass or more and 75 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the photosensitive layer. It is preferably 60 parts by mass or more and 70 parts by mass or less.

The ratio of the mass of the electron transport agent to the mass of the photosensitive layer _{(M L) (M ETM)} (M ETM / M L) is preferably 0.24 to 0.30. When the ratio (M _ETM / M _L) is at 0.24 to 0.30, the potential stability of the photosensitive member can be further improved.

(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. A hole transport agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  A suitable example of the hole transporting agent is a compound represented by the following general formula (HT1), (HT2), (HT3), (HT4), (HT5) or (HT6). Hereinafter, the compounds represented by the general formulas (HT1), (HT2), (HT3), (HT4), (HT5) and (HT6) are converted into compounds (HT1), (HT2), (HT3), (HT3), HT4), (HT5) and (HT6). The photosensitive layer preferably contains a compound (HT5) as a hole transport agent.

  Hereinafter, the compound (HT1) will be described.

In General Formula (HT1), R ^{20 to} R ²⁵ are each independently an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or aryl having 6 to 14 carbon atoms. Represents a group. R ^{20 to} R ²⁵ each preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and represents a methyl group or an ethyl group. Is particularly preferred.

In general formula (HT1), a1, a2, a3, and a4 each independently represent an integer of 0 or more and 5 or less. When a1 represents an integer of 2 or more and 5 or less, a plurality of R ²⁰ bonded to the same phenyl group may be the same or different from each other. When a2 represents an integer of 2 or more and 5 or less, the plurality of R ²¹ bonded to the same phenyl group may be the same as or different from each other. When a3 represents an integer of 2 or more and 5 or less, the plurality of R ²² bonded to the same phenyl group may be the same as or different from each other. When a4 represents an integer of 2 to 5, a plurality of R ²³ bonded to the same phenyl group may be the same as or different from each other. It is preferable that a1 and a2 each represent 0. a3 and a4 each independently preferably represent an integer of 1 to 5, more preferably 2.

The bonding position of R ^{20 to} R ²³ is not particularly limited. R ^{20 to} R ²³ may be bonded (positioned) to any of the ortho, meta and para positions of the phenyl group. R ²² and R ²³ are each preferably bonded to the ortho position of the phenyl group.

In general formula (HT1), a5 and a6 each independently represent an integer of 0 or more and 4 or less. When a5 represents an integer of 2 or more and 4 or less, the plurality of R ²⁴ bonded to the same phenylene group may be the same as or different from each other. When a6 represents an integer of 2 or more and 4 or less, the plurality of R ²⁵ bonded to the same phenylene group may be the same as or different from each other. It is preferable that a5 and a6 each represent 0.

The bonding position of R ²⁴ and R ²⁵ is not particularly limited. R ²⁴ and R ²⁵ may each be bonded (positioned) to either the ortho position or the meta position with respect to the nitrogen atom to which the phenylene group is bonded.

  A preferred example of the compound (HT1) is a compound represented by the following chemical formula (HT1-1) (hereinafter sometimes referred to as the compound (HT1-1)).

  Hereinafter, the compound (HT2) will be described.

In general formula (HT2), R ^{26 to} R ³¹ are each independently an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl having 6 to 14 carbon atoms. Or an alkenyl group having 2 to 6 carbon atoms which may have a group or a substituent. When the alkenyl group having 2 to 6 carbon atoms has a substituent, the substituent is preferably an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms, more preferably a phenyl group. preferable. The number of substituents of the alkenyl group having 2 to 6 carbon atoms is not particularly limited, but is preferably 3 or less, and more preferably 2.

In general formula (HT2), b1, b2, b3, and b4 each independently represent an integer of 0 or more and 5 or less. When b1 represents an integer of 2 or more and 5 or less, a plurality of R ²⁶ bonded to the same phenyl group may be the same as or different from each other. When b2 represents an integer of 2 or more and 5 or less, the plurality of R ²⁷ bonded to the same phenyl group may be the same or different from each other. When b3 represents an integer of 2 or more and 5 or less, the plurality of R ²⁸ bonded to the same phenyl group may be the same as or different from each other. When b4 represents an integer of 2 to 5, a plurality of R ²⁹ bonded to the same phenyl group may be the same as or different from each other. One of b1 and b2 represents 2, and the other preferably represents 0 or 1. It is preferable that one of b3 and b4 represents 2 and the other represents 0 or 1.

The bonding position of R ^{26 to} R ²⁹ is not particularly limited. R ^{26 to} R ²⁹ may be bonded (positioned) to any of the ortho, meta, and para positions of the phenyl group. R ^{26 to} R ²⁹ are each preferably bonded to the ortho position or para position of the phenyl group.

In general formula (HT2), b5 and b6 each independently represent an integer of 0 or more and 4 or less. When b5 represents an integer of 2 or more and 4 or less, the plurality of R ³⁰ bonded to the same phenylene group may be the same as or different from each other. When b6 represents an integer of 2 or more and 4 or less, the plurality of R ³¹ bonded to the same phenylene group may be the same as or different from each other. b5 and b6 each preferably represent 0.

The bonding position of R ³⁰ and R ³¹ is not particularly limited. R ³⁰ and R ³¹ may be bonded (positioned) to either the ortho position or the meta position with respect to the nitrogen atom to which the phenylene group is bonded.

When b1 represents 2 and b2 represents 0 or 1, it is preferable that two R ²⁶ each independently represent an alkyl group having 1 to 6 carbon atoms, and include a methyl group and an ethyl group, or two It is more preferable to represent the methyl group. When b1 represents 2 and b2 represents 0 or 1, R ²⁷ represents an optionally substituted alkenyl group having 2 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms. It is more preferable to represent an alkenyl group having 2 to 6 carbon atoms or an alkyl group having 1 to 3 carbon atoms having two aryl groups having 6 to 14 carbon atoms. More preferably, it represents a diphenylethenyl group or a methyl group, and particularly preferably a methyl group. When b1 represents 2 and b2 represents 0 or 1, two R ²⁶ are preferably bonded to the two ortho positions of the phenyl group, or bonded to the ortho position or the para position of the phenyl group. More preferably, it is bonded to the ortho position or para position. In this case, R ²⁷ is preferably bonded to the para position of the phenyl group.

When b2 represents 2 and b1 represents 0 or 1, it is preferable that two R ²⁷ each independently represent an alkyl group having 1 to 6 carbon atoms, and include a methyl group and an ethyl group, or two It is more preferable to represent the methyl group. When b2 represents 2 and b1 represents 0 or 1, R ²⁶ represents an alkenyl group having 2 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms which may have a substituent. It is more preferable to represent an alkenyl group having 2 to 6 carbon atoms or an alkyl group having 1 to 3 carbon atoms having two aryl groups having 6 to 14 carbon atoms. It is particularly preferred that it represents a diphenylethenyl group or a methyl group. When b2 represents 2 and b1 represents 0 or 1, two R ²⁷ are preferably bonded to the two ortho positions of the phenyl group, or bonded to the ortho position and the para position of the phenyl group. More preferably, it is bonded to the ortho-position and para-position. In this case, R ²⁶ is preferably bonded to the para position of the phenyl group.

When b3 represents 2 and b4 represents 0 or 1, it is preferable that two R ²⁸ each independently represents an alkyl group having 1 to 6 carbon atoms, and represents a methyl group and an ethyl group. More preferred. When b3 represents 2 and b4 represents 0 or 1, R ²⁹ represents an optionally substituted alkenyl group having 2 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms. It is more preferable to represent an alkenyl group having 2 to 6 carbon atoms or an alkyl group having 1 to 3 carbon atoms having two aryl groups having 6 to 14 carbon atoms. More preferably, it represents a diphenylethenyl group or a methyl group, and particularly preferably a methyl group. When b3 represents 2 and b4 represents 0 or 1, it is preferable that two R ²⁸ are bonded to the two ortho positions of the phenyl group or to the ortho position and the para position of the phenyl group. More preferably, it is bonded to the ortho-position and para-position. In this case, R ²⁹ is preferably bonded to the para position of the phenyl group.

When b4 represents 2 and b3 represents 0 or 1, it is preferable that two R ²⁹ each independently represent an alkyl group having 1 to 6 carbon atoms, and may represent a methyl group and an ethyl group. More preferred. When b3 represents 2 and b4 represents 0 or 1, R ²⁸ represents an optionally substituted alkenyl group having 2 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms. And preferably represents an alkenyl group having 2 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms having two aryl groups having 6 to 14 carbon atoms. More preferably, it represents a diphenylethenyl group or a methyl group, and particularly preferably a methyl group. When b4 represents 2 and b3 represents 0 or 1, it is preferable that two R ²⁹ are bonded to the two ortho positions of the phenyl group or to the ortho position and the para position of the phenyl group. More preferably, it is bonded to the ortho-position and para-position. In this case, R ²⁸ is preferably bonded to the para position of the phenyl group.

  A suitable example of the compound (HT2) is a compound represented by the chemical formula (HT2-1) or (HT2-2). Hereinafter, the compounds represented by the chemical formulas (HT2-1) and (HT2-2) may be referred to as compounds (HT2-1) and (HT2-2).

  Hereinafter, the compound (HT3) will be described.

In the general formula (HT3), R ^{32 to} R ³⁵ are each independently an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl having 6 to 14 carbon atoms. Represents a group. R ^{32 to} R ³⁴ each preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group. . R ³⁵ preferably represents an aryl group having 6 to 14 carbon atoms, and more preferably a phenyl group.

In general formula (HT3), f1, f2, and f3 each independently represent an integer of 0 or more and 5 or less. When f1 represents an integer of 2 or more and 5 or less, a plurality of R ³² bonded to the same phenyl group may be the same as or different from each other. When f2 represents an integer of 2 or more and 5 or less, the plurality of R ³³ bonded to the same phenyl group may be the same as or different from each other. When f3 represents an integer of 2 or more and 5 or less, the plurality of R ³⁴ bonded to the same phenyl group may be the same as or different from each other. f1 preferably represents 0 or 1, and more preferably represents 1. f2 preferably represents 1 or 2, and more preferably represents 1. f3 preferably represents 0 or 1, and more preferably represents 0.

  In general formula (HT3), f4 represents 0 or 1.

The bonding position of R ^{32 to} R ³⁴ is not particularly limited. R ^{32 to} R ³⁴ may be bonded (positioned) to any of the ortho, meta, and para positions of the phenyl group. R ³² is preferably bonded to the para position of the phenyl group. R ³³ is preferably bonded to the para position of the phenyl group. R ³⁴ is preferably bonded to the para position of the phenyl group.

When f2 represents 2 and two R ³³ are bonded to adjacent bond positions of the phenyl group (for example, ortho-position and meta-position, or meta-position and para-position), two R ³³ are bonded to each other. A ring may be formed. Examples of the ring formed by bonding two adjacent R ³³ to each other include cycloalkanes having 5 to 7 carbon atoms. When two adjacent R ³³ are bonded to each other to form a cycloalkane having 5 to 7 carbon atoms, the cycloalkane having 5 to 7 carbon atoms is a phenyl group to which two R ³³ are bonded. To form a bicyclic fused ring group. In this case, the condensation site between the cycloalkane having 5 to 7 carbon atoms and the phenyl group may contain a double bond. Two adjacent R ^33's are preferably bonded to each other to form a cycloalkane having 5 to 7 carbon atoms, more preferably cyclohexane.

  A preferred example of the compound (HT3) is a compound represented by the following chemical formula (HT3-1) or (HT3-2). Hereinafter, the compounds represented by chemical formulas (HT3-1) and (HT3-2) may be referred to as compounds (HT3-1) and (HT3-2), respectively.

  Hereinafter, the compound (HT4) will be described.

In the general formula (HT4), R ^{36 to} R ³⁸ are each independently an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl having 6 to 14 carbon atoms. Represents a group. R ^{36 to} R ³⁸ preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably an n-butyl group.

In general formula (HT4), d1, d2, and d3 each independently represent an integer of 0 or more and 5 or less. When d1 represents an integer of 2 or more and 5 or less, a plurality of R ³⁶ bonded to the same phenyl group may be the same as or different from each other. When d2 represents an integer of 2 or more and 5 or less, a plurality of R ³⁷ bonded to the same phenyl group may be the same as or different from each other. When d3 represents an integer of 2 or more and 5 or less, a plurality of R ³⁸ bonded to the same phenyl group may be the same or different from each other. d1 preferably represents 1. d2 and d3 preferably represent 0.

The bonding position of R ^{36 to} R ³⁸ is not particularly limited. R ^{36 to} R ³⁸ may be bonded (positioned) to any of the ortho, meta and para positions of the phenyl group. R ³⁶ is preferably bonded to the para position of the phenyl group.

  A suitable example of the compound (HT4) is a compound represented by the following chemical formula (HT4-1) (hereinafter sometimes referred to as the compound (HT4-1)).

  Hereinafter, the compound (HT5) will be described.

In General Formula (HT5), R ^{39 to} R ⁴³ each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. An aryl group having 6 to 14 carbon atoms which may have a group. R ^{39 to} R ⁴¹ each preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group. . R ^{42 to} R ⁴³ each preferably represents an aryl group having 6 to 14 carbon atoms which may have an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 3 carbon atoms. It is more preferably a phenyl group which may have a group, more preferably a methylphenyl group, and particularly preferably a p-methylphenyl group.

In general formula (HT5), e1, e2 and e3 each independently represent an integer of 0 or more and 5 or less. When e1 represents an integer of 2 or more and 5 or less, a plurality of R ³⁹ bonded to the same phenyl group may be the same as or different from each other. When e2 represents an integer of 2 or more and 5 or less, a plurality of R ⁴⁰ bonded to the same phenyl group may be the same as or different from each other. When e3 represents an integer of 2 or more and 5 or less, the plurality of R ⁴¹ bonded to the same phenyl group may be the same as or different from each other. e1, e2 and e3 each preferably represent 1.

The bonding position of R ^{39 to} R ⁴¹ is not particularly limited. R ^{39 to} R ⁴¹ may be bonded (positioned) to any of the ortho, meta and para positions of the phenyl group. R ^{39 to} R ⁴¹ are each preferably bonded to the para position of the phenyl group.

  A preferred example of the compound (HT5) is a compound represented by the following chemical formula (HT5-1) (hereinafter sometimes referred to as the compound (HT5-1)).

  Hereinafter, the compound (HT6) will be described.

In the general formula (HT6), R ^{44 to} R ⁴⁹ are each independently an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl having 6 to 14 carbon atoms. Represents a group. R ^{44 to} R ⁴⁹ each preferably represent an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group. .

In general formula (HT6), g1, g2, g3 and g4 each independently represent an integer of 0 or more and 5 or less. When g1 represents an integer of 2 or more and 5 or less, the plurality of R ⁴⁴ bonded to the same phenyl group may be the same as or different from each other. When g2 represents an integer of 2 to 5, a plurality of R ⁴⁵ bonded to the same phenyl group may be the same as or different from each other. When g3 represents an integer of 2 or more and 5 or less, the plurality of R ⁴⁶ bonded to the same phenyl group may be the same as or different from each other. When g4 represents an integer of 2 or more and 5 or less, the plurality of R ⁴⁷ bonded to the same phenyl group may be the same as or different from each other. It is preferable that g1 and g4 each represent 1. More preferably, g2 and g3 each represent 0.

The bonding position of R ^{44 to} R ⁴⁷ is not particularly limited. R ^{44 to} R ⁴⁷ may be bonded (positioned) to any of the ortho, meta, and para positions of the phenyl group. R ⁴⁴ and R ⁴⁷ are each preferably bonded to the para position of the phenyl group.

In general formula (HT6), g5 and g6 each independently represent an integer of 0 or more and 4 or less. When g5 represents an integer of 2 or more and 4 or less, the plurality of R ⁴⁸ bonded to the same phenylene group may be the same as or different from each other. When g6 represents an integer of 2 or more and 4 or less, the plurality of R ⁴⁹ bonded to the same phenylene group may be the same as or different from each other. It is preferable that g5 and g6 each represent 0.

The bonding position of R ⁴⁸ and R ⁴⁹ is not particularly limited. R ⁴⁸ and R ⁴⁹ may be bonded (positioned) to either the ortho position or the meta position with respect to the nitrogen atom to which the phenylene group is bonded.

  A preferred example of the compound (HT6) is a compound represented by the following chemical formula (HT6-1) (hereinafter sometimes referred to as the compound (HT6-1)).

  The content of the hole transport agent contained in the photosensitive layer is preferably 10 parts by mass or more and 200 parts by mass or less, and 40 parts by mass or more and 55 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferred.

(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. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the phthalocyanine pigment include metal-free phthalocyanine or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (CG1), 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 metal-free phthalocyanine crystal include an X-type crystal of 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.

  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 more preferably an X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine. Y-type titanyl phthalocyanine is particularly preferred. In addition, Y-type titanyl phthalocyanine has the advantages of high charge generation efficiency and less charge remaining in the photosensitive layer.

  Y-type titanyl phthalocyanine has a main peak at 27.2 ° of the Bragg angle (2θ ± 0.2 °) in the CuKα characteristic X-ray diffraction spectrum, for example. The main peak in the CuKα characteristic X-ray diffraction spectrum is a peak having the first or second highest intensity in a range where the Bragg angle (2θ ± 0.2 °) is 3 ° or more and 40 ° or less. Y-type titanyl phthalocyanine has no peak at 26.2 ° in the CuKα characteristic X-ray diffraction spectrum.

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

  FIG. 2 is an example of a CuKα characteristic X-ray diffraction spectrum chart of titanyl phthalocyanine used in the photoreceptor according to the present embodiment. In FIG. 2, the horizontal axis indicates the Bragg angle 2θ (°), and the vertical axis indicates the intensity (cps). From the CuKα characteristic X-ray diffraction spectrum chart of FIG. 2, it can be estimated that the measured crystal form of titanyl phthalocyanine is Y-type.

Y-type titanyl phthalocyanine is classified into three types according to differences in thermal characteristics (specifically, thermal characteristics (a) to (c) shown below) in a differential scanning calorimetry (DSC) spectrum.
(A) The thermal characteristics by DSC have a peak (for example, one peak) in the range of 50 ° C. or higher and 270 ° C. or lower in addition to the peak accompanying vaporization of adsorbed water.
(B) In the thermal characteristics by DSC, there is no peak in the range of 50 ° C. or more and 400 ° C. or less other than the peak accompanying vaporization of adsorbed water.
(C) In the thermal characteristics by DSC, there is no peak in the range from 50 ° C. to less than 270 ° C. other than the peak accompanying vaporization of the adsorbed water, and a peak in the range from 270 ° C. to 400 ° C. (for example, one peak) Have

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

  FIG. 3 is an example of a differential scanning calorimetry spectrum chart of titanyl phthalocyanine used in the photoreceptor according to the present embodiment. Specifically, it is a differential scanning calorimetry spectrum chart of titanyl phthalocyanine shown in the CuKα characteristic X-ray diffraction spectrum chart of FIG. In FIG. 3, the horizontal axis represents temperature (° C.), and the vertical axis represents heat flux (mcal / second). In the differential scanning calorimetry spectrum chart of FIG. 3, no peak is observed in the range from 50 ° C. to less than 270 ° C. other than the peak accompanying vaporization of adsorbed water, and one peak is observed at 296 ° C. (range of 270 ° C. to 400 ° C.). A peak is observed. Therefore, it can be estimated that the measured titanyl phthalocyanine crystal is Y-type titanyl phthalocyanine mainly having thermal properties (c).

  Y-type titanyl phthalocyanine having thermal characteristics (b) and (c) is excellent in crystal stability, hardly undergoes crystal transition in an organic solvent, and is easily dispersed in the photosensitive layer. In order to improve potential stability and crack resistance and suppress exposure memory, Y-type titanyl phthalocyanine having thermal characteristics (c) is 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 weight or more and 50 parts by weight or less, and 0.5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the binder resin contained in the photosensitive layer. More preferably, it is 1 to 5 parts by mass.

(Binder resin)
The photosensitive layer may contain a binder resin. Examples of the binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include polycarbonate resin, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic acid polymer, 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 Examples thereof include resins, ketone resins, polyvinyl butyral resins, polyester resins, and polyether resins. As a thermosetting resin, a silicone resin, an epoxy resin, a phenol resin, a urea resin, or a melamine resin is mentioned, for example. As photocurable resin, the acrylic acid adduct of an epoxy compound or the acrylic acid adduct of a urethane compound is mentioned, for example. These binder resins may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these resins, a polycarbonate resin is preferable because a photosensitive layer having an excellent balance of processability, mechanical properties, optical properties, and abrasion resistance can be obtained. Examples of the polycarbonate resin include bisphenol Z type polycarbonate resin, bisphenol ZC type polycarbonate resin, bisphenol C type polycarbonate resin, and bisphenol A type polycarbonate resin. As the polycarbonate resin, a resin represented by the following general formula (PC) (hereinafter sometimes referred to as resin (PC)) is preferable.

In the general formula (PC), R ^{50 to} R ⁵⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms. However, R ⁵² and R ⁵³ may be bonded to each other to form a cycloalkylidene group having 5 to 7 carbon atoms. x + y = 1.00. 0.00 <x ≦ 1.00. That is, x is a number greater than 0.00 and less than or equal to 1.00.

The alkyl group having 1 to 6 carbon atoms represented by R ^{50 to} R ⁵⁵ in the general formula (PC) is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group.

The aryl group having 6 to 14 carbon atoms represented by R ^{50 to} R ⁵⁵ in the general formula (PC) is preferably a phenyl group.

In the general formula (PC), R ⁵⁰ , R ⁵¹ , R ⁵⁴ and R ⁵⁵ each preferably represent an alkyl group having 1 to 6 carbon atoms or a hydrogen atom, and may represent a hydrogen atom or a methyl group. More preferred. R ⁵² and R ⁵³ are preferably bonded to each other to represent a cycloalkylidene group having 5 to 7 carbon atoms, and more preferably bonded to each other to represent a cyclohexylidene group.

The resin (PC) is represented by a general structural formula (PC-b) and a repeating structural unit represented by the general formula (PC-a) (hereinafter sometimes referred to as a repeating unit (PC-a)). Repeating structural units (hereinafter sometimes referred to as repeating units (PC-b)). Incidentally, R ⁵⁰ to R ⁵³ in the general formula (PC-a) has the same meaning as R ⁵⁰ to R ⁵³ each in the general formula (PC). R ⁵⁴ and R ⁵⁵ in the general formula (PC-b) has the same meaning as R ⁵⁴ and R ⁵⁵ each in the general formula (PC).

  In the general formula (PC), x represents the ratio (molar fraction) of the substance amount (mole number) of the repeating unit (PC-a) to the substance amount (mole number) of all repeating units in the resin (PC). . y represents the ratio (molar fraction) of the substance amount (mole number) of the repeating unit (PC-b) to the substance amount (mole number) of all repeating units in the resin (PC).

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

  The resin (PC) may have a group represented by the following general formula (PC-e) or (PC-f) as a terminal group.

In the general formula (PC-e), R ⁵⁶ represents —CO—O— or —O—. However, when joining the repeating units ether moiety of (PC-a) or repeating units (PC-b) (-O-) , R 56 represents -CO-O-. R ⁵⁶ represents —O— when bonded to the ester unit (—CO—O—) of the repeating unit (PC-a) or the repeating unit (PC-b). R ⁵⁷ and R ⁵⁸ each independently represents an alkylene group having 1 to 6 carbon atoms which may have at least one halogen atom (preferably 1 to 12 halogen atoms). R ⁵⁷ and R ⁵⁸ are preferably a methylene group having 2 to 4 halogen atoms and an ethylene (—CH ₂ —CH ₂ —) group. R ⁵⁹ represents an alkyl group having 1 to 6 carbon atoms which may have at least one halogen atom (preferably 1 to 13 halogen atoms). R ⁵⁹ is preferably an alkyl group having 1 to 4 carbon atoms having 1 to 9 halogen atoms, and more preferably a 2-methylpropyl group having 9 halogen atoms.

In the general formula (PC-f), R ⁵⁶ represents —CO—O— or —O—. However, when joining the repeating units ether moiety of (PC-a) or repeating units (PC-b) (-O-) , R 56 represents -CO-O-. R ⁵⁶ represents —O— when bonded to the ester unit (—CO—O—) of the repeating unit (PC-a) or the repeating unit (PC-b). R ⁶⁰ represents an alkyl group having 1 to 6 carbon atoms which may have at least one halogen atom (preferably 1 to 13 halogen atoms). R ⁶⁰ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a tert-butyl group.

  Specific examples of the resin (PC) include polycarbonate resins represented by the following general formula (PC-1), general formula (PC-2), or chemical formula (PC-3). Hereinafter, polycarbonate resins represented by the following chemical formula (PC-1), general formula (PC-2) and chemical formula (PC-3) are respectively converted into polycarbonate resins (PC-1), (PC-2) and (PC). -3).

  In the general formula (PC-2), x2 + y2 = 1.00. x2 represents a number from 0.56 to 0.62. y2 represents a number from 0.38 to 0.44. In the general formula (PC-2), x2 represents the amount of the repeating unit to which x2 is attached (mol) relative to the total amount of the repeating unit (mole number) in the polycarbonate resin represented by the general formula (PC-2). Number) (molar fraction). y2 is the ratio (molar fraction) of the substance amount (mole number) of the repeating unit with y2 to the total substance amount (mole number) of the repeating unit in the polycarbonate resin represented by the general formula (PC-2). Represents.

  The polycarbonate resin represented by the chemical formula (PC-3) is a resin in which y in the general formula (PC) is 0.00 and x is 1.00. The polycarbonate resin represented by the chemical formula (PC-3) is composed of only the repeating unit (PC-a).

The method for producing the binder resin is not particularly limited as long as the resin (PC) can be produced. As an example of a method for producing a resin (PC), there is a method (so-called phosgene method) in which a diol compound for constituting a repeating unit of a polycarbonate resin and phosgene are subjected to condensation polymerization. More specifically, for example, a method of polycondensing a diol compound represented by the general formula (PC-c), a diol compound represented by the general formula (PC-d), and phosgene can be mentioned. Incidentally, R ⁵⁰ to R ⁵³ in the general formula (PC-c) has the same meaning as R ⁵⁰ to R ⁵³ each in the general formula (PC). R ⁵⁴ and R ⁵⁵ in the general formula (PC-d) has the same meaning as R ⁵⁴ and R ⁵⁵ each in the general formula (PC). Another example of a method for producing a resin (PC) is a method of transesterifying a diol compound and diphenyl carbonate.

In the reaction for producing the resin (PC), a desired end group can be introduced into the resin (PC) by adding a desired end terminator. When the terminal group is the following general formula (PC-e), a compound represented by the following general formula (PC-g) is added as a terminal terminator. R ⁵⁶ in the general formula (PC-g) ~R ⁵⁹ has the same meaning as R ⁵⁶ to R ⁵⁹ each in the general formula (PC-e). When the terminal group is the following general formula (PC-f), a compound represented by the following general formula (PC-h) is added as a terminal terminator. R ⁵⁶ and R ⁶⁰ in the general formula (PC-h) has the same meaning as R ⁵⁶ and R ⁶⁰ each in the general formula (PC-f).

  The photosensitive layer may further contain a binder resin other than the resin (PC) in addition to the resin (PC). The content of the resin (PC) with respect to the mass of the binder resin contained in the photosensitive layer is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. .

The ratio (M _RESIN / M _L ) of the mass (M _RESIN ) of the binder resin to the mass (M _L ) of the photosensitive layer may be less than 0.50. When the ratio (M _RESIN / M _L ) is less than 0.50, the ratio of the mass of the material other than the binder resin to the mass of the photosensitive layer increases. Specifically, the ratio of the mass of the charge generator, the hole transport agent, the electron transport agent and the compounds (ADD1) to (ADD6) with respect to the mass of the photosensitive layer is increased. If the ratio of the mass of the material other than the binder resin to the mass of the photosensitive layer is increased, cracks are likely to occur in the binder resin, and the crack resistance of the photoreceptor tends to be reduced. However, in the photoreceptor of this embodiment, any one of the compounds (ADD1) to (ADD6) is contained in the photosensitive layer with a predetermined content. Therefore, even if the ratio (M _RESIN / M _L ) is less than 0.50, the crack resistance of the photoreceptor can be improved. The ratio (M _RESIN / M _L ) is more preferably 0.47 or less, further preferably 0.40 or more and 0.47 or less, and further preferably 0.40 or more and 0.45 or less. .

  The viscosity average molecular weight of the binder resin 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 binder resin is 25,000 or more, it is easy to improve the abrasion resistance of the photoreceptor. When the viscosity average molecular weight of the binder resin is 52,500 or less, the binder resin is easily dissolved in a solvent during 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.

<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 various additives.

<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 photosensitive layer coating solution comprises a charge generating agent, an electron transport agent, a hole transport agent, a binder resin, and compounds (ADD-1), (ADD-2), (ADD-3), and (ADD-4) as additives. ), (ADD-5) or (ADD-6), and components added as necessary (for example, other additives) are dissolved or dispersed 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, the image forming apparatus 100 including the photoconductor 30 according to the present embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of the configuration of the image forming apparatus 100, and the image forming apparatus 100 includes the photoconductor 30 according to the present embodiment. The image forming apparatus 100 shown in FIG. 4 employs a direct transfer method. The image forming apparatus 100 employing the intermediate transfer method will be described later with reference to FIG.

  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. 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 image forming unit 40 includes a photoconductor 30, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. A photoreceptor 30 is provided at the center position of the image forming unit 40. The photoconductor 30 is provided so as to be rotatable in the arrow direction (counterclockwise). Around the photoconductor 30, 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 photoconductor 30 with respect to the charging unit 42. The image forming unit 40 may further include one or both of a cleaning unit (not shown, for example, a cleaning blade) and a charge removal unit (not shown, for example, a static eliminator).

  The charging unit 42 charges the surface (for example, the peripheral surface) of the photoreceptor 30 to a positive polarity. 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 exposure unit 44 exposes the surface of the charged photoreceptor 30. As a result, an electrostatic latent image is formed on the surface of the photoreceptor 30. The electrostatic latent image is formed based on image data input to the image forming apparatus 100.

  Examples of the light source of the exposure unit 44 are a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), or electroluminescence (EL). In order to irradiate only light in a desired wavelength range, the exposure unit 44 may further include a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, or a color temperature conversion filter. Since the image forming apparatus 100 can be downsized, a light emitting diode is preferable as the light source of the exposure unit 44.

  The developing unit 46 supplies toner to the electrostatic latent image formed on the photoconductor 30. As a result, the electrostatic latent image is developed as a toner image. The photoreceptor 30 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 30. When the toner is used in the two-component developer, the developing unit 46 supplies the toner of the toner and carrier contained in the two-component developer to the electrostatic latent image formed on the photoreceptor 30.

  The transfer belt 50 conveys the recording medium P between the photoconductor 30 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 30 to the transfer target. When the image forming apparatus 100 employs the direct transfer method, the transfer target corresponds to the recording medium P. When the image forming apparatus 100 employs the direct transfer method, the photoconductor 30 is in contact with the recording medium P when the toner image is transferred from the photoconductor 30 to the recording medium P. 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.

  The image forming apparatus 100 can be designed not to include a charge removal unit. That is, the image forming apparatus 100 can employ a static elimination-less method that does not include a static elimination unit. When the image forming apparatus 100 employs the direct transfer method and the static elimination-less method, a toner image is transferred from the photoconductor 30 to the transfer target (corresponding to the recording medium P) by the transfer unit 48 on the surface (circumferential surface) of the photoconductor 30. The transferred area is charged again by the charging unit 42 without being neutralized. In the image forming apparatus 100 of the static elimination-less system that does not include the static eliminating unit, the influence of the decrease in the surface potential of the photosensitive member due to the exposure tends to remain, and the potential stability is reduced and the exposure memory is easily generated. However, according to the photoconductor 30 of this embodiment, as described above, the potential stability can be improved and the occurrence of exposure memory can be suppressed. Therefore, by providing the image forming apparatus 100 with the photoreceptor 30 of the present embodiment, it is possible to suppress the occurrence of exposure memory even when the image forming apparatus 100 does not include a charge removal unit.

  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.

  The image forming apparatus 100 can also employ an intermediate transfer method. Hereinafter, the image forming apparatus 100 that employs the intermediate transfer method will be described with reference to FIG. FIG. 5 is a diagram illustrating another example of the configuration of the image forming apparatus 100, and the image forming apparatus 100 includes the photoconductor 30 according to the present embodiment. In order to avoid redundancy, the same components as those included in the image forming apparatus 100 shown in FIG.

  When the image forming apparatus 100 adopts the intermediate transfer method, the transfer unit 48 described in the direct transfer method corresponds to the primary transfer unit 54 and the secondary transfer unit 58. When the image forming apparatus 100 employs the intermediate transfer method, the transfer target corresponds to the intermediate transfer belt 56 and the recording medium P. The primary transfer unit 54 applies a primary transfer bias (specifically, a bias having a polarity opposite to the toner charging polarity) to the intermediate transfer belt 56. The intermediate transfer belt 56 is an endless belt. The intermediate transfer belt 56 rotates in the direction of the arrow (counterclockwise). When the primary transfer bias is applied, the toner image formed on the surface of the photoconductor 30 is transferred (primary transfer) from the photoconductor 30 to the intermediate transfer belt 56 between the photoconductor 30 and the primary transfer portion 54. .

  The secondary transfer unit 58 applies a secondary transfer bias (specifically, a bias having a polarity opposite to that of the toner image) to the recording medium P. As a result, the toner image primarily transferred onto the intermediate transfer belt 56 is transferred (secondary transfer) from the intermediate transfer belt 56 to the recording medium P between the secondary transfer portion 58 and the intermediate transfer belt 56. As a result, the unfixed toner image is transferred to the recording medium P.

  When the image forming apparatus 100 employs the intermediate transfer method and the static elimination-less method, toner is transferred from the photosensitive member 30 to the transfer target (corresponding to the intermediate transfer belt 56) by the primary transfer unit 54 on the surface (circumferential surface) of the photosensitive member 30. The area where the image has been transferred is charged again by the charging unit 42 without being neutralized.

  The image forming apparatus 100 including the photoconductor 30 according to the present embodiment has been described above with reference to FIGS. 4 and 5.

<3. Process cartridge>
Next, with reference to FIG. 4 and FIG. 5 again, a process cartridge including the photoconductor 30 of this embodiment will be described. The process cartridge is an image forming cartridge. The process cartridge corresponds to each of the image forming units 40a to 40d. The process cartridge includes a photoreceptor 30. In addition to the photoreceptor 30, the process cartridge includes 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 (or a primary transfer unit 54). The process cartridge may further include one or both of a cleaning unit (not shown) and a charge removal unit (not shown). The process cartridge may employ a static elimination-less method. 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 characteristic of the photoconductor 30 is deteriorated, the process cartridge including the photoconductor 30 can be easily and quickly replaced.

  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.

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

(Charge generator)
Titanyl phthalocyanine was prepared as a charge generator. Titanyl phthalocyanine was a compound represented by the chemical formula (CG1) described in the embodiment. Further, this titanyl phthalocyanine had a main peak at 27.2 ° in the Bragg angle (2θ ± 0.2 °) and no peak at 26.2 ° in the CuKα characteristic X-ray diffraction spectrum. This titanyl phthalocyanine has no peak in the range of 50 ° C. or more and less than 270 ° C. other than the peak accompanying vaporization of adsorbed water in the thermal characteristics by DSC, and has one peak in the range of 270 ° C. or more and 400 ° C. or less. It was.

(Hole transport agent)
The compound (HT5-1) described in the embodiment was prepared as a hole transport agent.

(Binder resin)
The polycarbonate resin (PC-3) described in the embodiment was prepared as a binder resin. The viscosity average molecular weight of the polycarbonate resin (PC-3) was 30000.

(Additive)
As additives, the compounds (ADD1-1), (ADD2-1), (ADD3-1), (ADD4-1), (ADD5-1) and (ADD6-1) described in the embodiment were prepared.

(Electron transfer agent)
As the electron transport agent, the compounds (ET1-1), (ET2-1), (ET3-A1), (ET3-B1), (ET3-B2), (ET3-B3), (ET4- 1) and (ET5-1) were prepared. As an electron transport agent, compounds (ET1-1), (ET2-1), (ET3-A1), (ET3-B1), (ET3-B2), (ET3-B3), (ET4-1) and (ET5 Two types of -1) were selected and used. When two types of electron transfer agents are used, each of the two types of electron transfer agents is described as a first electron transfer agent and a second electron transfer agent.

  The compounds (ET3-B1), (ET3-B2) and (ET3-B3) were synthesized by the following method.

(Production of Compound (ET3-B1))
Compound (ET3-B1) was produced according to the reaction represented by reaction formula (r-4) (hereinafter sometimes referred to as reaction (r-4)).

  In the reaction (r-4), 2.68 g (10 mmol) of the compound (F) (naphthalene-1,4,5,8-tetracarboxylic dianhydride) and the compound represented by the chemical formula (1G) 4. 64 g (20 mmol) and 50 mL of picoline were put into a flask to prepare a picoline solution. The temperature of the flask contents was raised to 100 ° C. and maintained at 100 ° C., and the flask contents were stirred for 4 hours. After the reaction, ion exchange water was put into the flask and extracted with chloroform. The solvent (picoline) in the organic layer was removed to obtain a residue. The obtained residue was purified by silica gel column chromatography using chloroform as a developing solvent. This obtained compound (ET3-B1). The yield of compound (ET3-B1) was 4.16 g, and the yield of compound (ET3-B1) from compound (F) in reaction (r-4) was 60 mol%.

(Production of Compound (ET3-B3))
A compound (ET3-B3) was produced in the same manner as in the production of the compound (ET3-B1) except that the following points were changed. In the production of compound (ET3-B3), compound (1G) (4.64 g, 20 mmol) used in reaction (r-4) was changed to compound (5G) (3.80 g, 20 mmol). The compound (5G) is represented by the following chemical formula (5G). As a result, a compound (ET3-B3) was obtained instead of the compound (ET3-B1). The yield of compound (ET3-B3) was 3.98 g, and the yield of compound (ET3-B3) from compound (F) in reaction (r-4) was 65 mol%.

(Production of Compound (ET3-B2))
Reactions represented by reaction formulas (r′-1), (r′-2) and (r′-3) (hereinafter, reaction (r′-1), reaction (r′-2) and reaction (r, respectively) The compound (ET3-B2) was produced according to (sometimes described as' -3).

  In the reaction (r′-1), 3.42 g (10 mmol) of the compound (1A), 1.35 g (10 mmol) of the compound (2E), 1.3 g (10 mmol) of N, N-diisopropylethylamine, Dioxane 50mL was put into the flask to prepare a dioxane solution. The temperature of the flask contents was raised to 100 ° C. and maintained at 100 ° C., and the flask contents were stirred for 2 hours. After the reaction, dioxane was removed to obtain a residue. The residue obtained by silica gel column chromatography was purified using ethyl acetate / hexane (volume ratio V / V = 1/2) as a developing solvent. As a result, an intermediate product represented by the chemical formula (2C ′) (hereinafter sometimes referred to as compound (2C ′)) was obtained.

  In reaction (r′-2), compound (2C ′) and 15 mL of trifluoroacetic acid were charged into a flask to prepare a trifluoroacetic acid solution. Compound (2C ′) was used in reaction (r′-2) in the total amount obtained in reaction (r′-1). The temperature of the flask contents was raised to 80 ° C. and maintained at 80 ° C., and the flask contents were stirred for 24 hours. After the reaction, trifluoroacetic acid was removed to obtain a residue. The residue obtained by silica gel column chromatography was purified using ethyl acetate / hexane (volume ratio V / V = 1/4) as a developing solvent. As a result, an intermediate product represented by the chemical formula (2D ′) (hereinafter sometimes referred to as compound (2D ′)) was obtained.

  In the reaction (r′-3), a compound (2D ′), 2.32 g (10 mmol) of the compound represented by the chemical formula (2B), 1.3 g (10 mmol) of diisopropylethylamine, and 50 mL of dioxane were added to a flask. To prepare a dioxane solution. The temperature of the flask contents was raised to 100 ° C. and maintained at 100 ° C., and the flask contents were stirred for 2 hours. After the reaction, dioxane was removed to obtain a residue. The residue obtained by silica gel column chromatography was purified using ethyl acetate as a developing solvent. This obtained the compound (ET3-B2). The yield of compound (ET3-B2) was 2.69 g, and the yield of compound (ET3-B2) from compound (1A) in reactions (r′-1) to (r′-3) was 45 mol%. there were.

Next, ¹ H-NMR spectra of the produced compounds (ET3-B1) to (ET3-B3) were measured using a proton nuclear magnetic resonance spectrometer (manufactured by JASCO Corporation, 300 MHz). CDCl ₃ was used as the solvent. Tetramethylsilane (TMS) was used as an internal standard sample. Of these, the chemical shift value of (ET3-B1) is shown as a representative example. It was confirmed by the chemical shift value of the ¹ H-NMR spectrum that (ET3-B1) was obtained. It was confirmed that the compounds (ET3-B2) and (ET3-B3) were obtained from the chemical shift values of the ¹ H-NMR spectrum for the compounds (ET3-B2) and (ET3-B3).
Compound (ET3-B1): ¹ H-NMR (300 MHz, CDCl ₃ ) δ = 8.70 (d, 4H), 7.62-7.75 (m, 8H), 7.36-7.55 (m , 8H).

<Manufacture of photoconductor>
Photoreceptors (A-1) to (A-33) and (B-1) to (B-16) were produced using materials for forming the photosensitive layer.

(Manufacture of photoconductor (A-1))
In the container, 3 parts by mass of the charge generating agent, 50 parts by mass of the hole transporting agent, 30 parts by mass of the compound (ET1-1) as the first electron transporting agent, and the compound (ET4-1) 30 as the second electron transporting agent. 10 parts by mass of a compound (ADD1-1) as an additive, 100 parts by mass of a binder resin, and 800 parts by mass of tetrahydrofuran were added. The contents of the container were mixed for 50 hours using a ball mill to disperse the material in the solvent. This obtained the coating liquid for photosensitive layers. Next, the prepared photosensitive layer coating solution was applied onto a conductive substrate (aluminum drum-shaped support) by using a dip coating method. Thus, a coating film was formed on the conductive substrate. The conductive substrate on which the coating film was formed was dried at 100 ° C. for 60 minutes to remove tetrahydrofuran from the coating film. As a result, a single photosensitive layer (thickness: 25 μm) was formed on the conductive substrate. As a result, a photoreceptor (A-1) was obtained.

(Production of photoconductors (A-2) to (A-33) and (B-1) to (B-16))
Photoconductors (A-2) to (A-33) and (B-1) to (B-1) are the same as the production of photoconductor (A-1) except that the following points (1) to (7) are changed. Each of (B-16) was manufactured.
(1) In the production of the photoreceptor (A-1), 50 parts by mass of a hole transport agent was added, but the photoreceptors (A-2) to (A-33) and (B-1) to (B-16). In each production of), the amount of hole transport agent shown in Tables 1 to 5 was added.
(2) Although the compound (ET1-1) was used as the first electron transfer agent in the production of the photoreceptor (A-1), the photoreceptors (A-2) to (A-33) and (B-1) to In each production of (B-16), the first electron transfer agents of the types shown in Tables 1 to 5 were used.
(3) In the production of the photoreceptor (A-1), 30 parts by mass of the first electron transfer agent was added, but the photoreceptors (A-2) to (A-33) and (B-1) to (B-). In each production of 16), the amount of the first electron transfer agent shown in Tables 1 to 5 was added.
(4) In the production of the photoreceptor (A-1), the compound (ET4-1) was used as the second electron transfer agent, but the photoreceptors (A-2) to (A-33) and (B-1) to In each manufacture of (B-16), the 2nd electron transport agent of the kind shown in Table 1-Table 5 was used. In the production of the photoreceptors (B-1) to (B-9), no second electron transfer agent was added.
(5) In the production of the photoreceptor (A-1), 30 parts by mass of the second electron transfer agent was added, but the photoreceptors (A-2) to (A-33) and (B-1) to (B-). In each production of 16), the amount of the second electron transfer agent shown in Tables 1 to 5 was added.
(6) Although the compound (ADD1-1) was used as an additive in the production of the photoreceptor (A-1), the photoreceptors (A-2) to (A-33) and (B-1) to (B-) were used. In each production of 16), the types of additives shown in Tables 1 to 5 were used. In the production of the photoconductors (B-1), (B-10) and (B-11), no additive was added.
(7) In the production of the photoreceptor (A-1), 10 parts by mass of an additive was added, but the photoreceptors (A-2) to (A-33) and (B-1) to (B-16) In each production, the amounts of additives shown in Tables 1 to 5 were added.

<Evaluation of potential stability>
The potential stability was evaluated for each of the photoreceptors (A-1) to (A-33) and (B-1) to (B-16). The potential stability was evaluated in an environment of a temperature of 10 ° C. and a relative humidity of 15% RH. The photoreceptor was charged using a drum sensitivity tester (manufactured by Gentec) so that the surface potential V _0A (unit: + V) of the photoreceptor was +750 V under the condition of a peripheral speed of 125 rpm. Next, monochromatic light (light intensity: 0.3 μJ / cm ² ) was extracted from the light from the halogen lamp using a bandpass filter, and the extracted monochromatic light was irradiated (exposed) on the surface of the photoreceptor for 80 milliseconds. This charging and exposure were repeated for 1 hour. After repeating for 1 hour, the surface of the photoconductor was charged again, and the surface potential of the photoconductor was measured. The measured surface potential was _{defined as} a charging potential V _0B (unit: + V) after charging and exposure were repeated for 1 hour. ΔV ₀ (unit: V) was calculated from the calculation formula “ΔV ₀ = V _0A −V _0B ”. The obtained ΔV ₀ is shown in Tables 1-5. The smaller ΔV ₀ is, the better the potential stability of the photoreceptor is.

<Evaluation of exposure memory suppression>
For each of the photoreceptors (A-1) to (A-33) and (B-1) to (B-16), it was evaluated whether or not the occurrence of exposure memory was suppressed. Whether or not the generation of exposure memory was suppressed was evaluated in an environment of a temperature of 25 ° C. and a relative humidity of 45% RH.

  First, the photoconductor was mounted on an evaluation machine. As an evaluation machine, a modified machine of a monochrome printer (“FS-1300D” manufactured by Kyocera Document Solutions Inc.) was used. The point of modification in the modified machine was that the static eliminator and the cleaning blade were removed. That is, this evaluation machine employs a static elimination-less system and a cleaner-less system. Further, the modified machine was further modified by changing the light source of the exposure unit to LED. The charging potential was set to + 750V. The exposure time was set to 80 milliseconds. “High-quality PPC paper” (A4 size) manufactured by Fuji Xerox Co., Ltd. was used as the paper. In order to stabilize the operation of the photoconductor mounted on the evaluation machine, an image with a printing rate of 4% was continuously printed on 5000 sheets.

  Subsequently, one evaluation image including images A and B was printed. The image A was an image in which one black (image density 100%) circular pattern appeared on a white (image density 0%) background. Image A corresponds to an image formed on the first round of the photoreceptor. The image B was an entire halftone image (image density 12.5%). Image B corresponded to an image formed on the second round of the photoreceptor.

  The obtained image B was observed with the naked eye, and the presence or absence of an image ghost derived from the image A was confirmed. When an exposure memory is generated on the photosensitive member, an image ghost (particularly a positive ghost) is generated on the formed image. The image ghost is an image defect in which an area corresponding to the black circular pattern of the image A printed on the first round of the photoconductor appears black in the entire halftone image B printed on the second round of the photoconductor. is there. Based on the confirmation result of the image ghost, it was evaluated whether or not the occurrence of exposure memory was suppressed according to the following criteria. The evaluation results are shown in Tables 1 to 5.

(Evaluation criteria for exposure memory suppression)
Good (◯): Image ghost was not confirmed.
Defect (x): Image ghost was confirmed.

<Evaluation of crack resistance: Evaluation of the number of cracks generated>
Crack resistance was evaluated for each of the photoreceptors (A-1) to (A-33) and (B-1) to (B-16). First, pseudo dandruff was adhered to 10 measurement points on the surface of the photoreceptor. Pseudo dandruff was a prototype that simulated human dandruff. The photoreceptor to which pseudo dandruff was adhered was left for 10 days in a light-shielded environment at a temperature of 20 ° C. and a relative humidity of 60% RH. After standing for 10 days, the pseudo dandruff adhered to the surface of the photoreceptor was wiped off. Next, using the optical microscope, 10 measurement points on the surface of the photoreceptor were observed at a magnification of 50 times. The number of cracks observed at 10 measurement locations on the surface of the photoreceptor was counted. Tables 1 to 5 show the number of cracks observed. The smaller the number of cracks, the better the crack resistance.

<Evaluation of crack resistance: Image evaluation>
In the evaluation of the number of occurrences of cracks, image evaluation was performed using a photoconductor from which pseudo dandruff adhered to the surface of the photoconductor was wiped off. The image evaluation was performed in an environment at a temperature of 25 ° C. and a relative humidity of 45% RH. The evaluation machine and paper used in the image evaluation were the same as the evaluation machine and paper used for the evaluation of exposure memory suppression. In the evaluation of the number of occurrences of cracks, a photoconductor from which pseudo dandruff adhered to the surface of the photoconductor was wiped was mounted on an evaluation machine. Using an evaluation machine, a solid image having an image density of 100% was printed on one sheet. The printed image was observed with the naked eye to confirm the presence or absence of image defects. Note that when a crack occurs on the surface of the photoreceptor, an image defect in which white stripes occur in the formed image occurs. Image evaluation was performed according to the following criteria from the result of confirmation of image failure. The evaluation results are shown in Tables 1 to 5.

(Evaluation criteria for image evaluation)
○ (Good): No image defect was observed.
X (defect): Image defect was observed.

  In Tables 1 to 5, “part”, “HTM”, “first ETM”, and “second ETM” represent a mass part, a hole transport agent, a first electron transport agent, and a second electron transport agent, respectively.

In Tables 1 to 5, “ _METM / _MHTM ” is the ratio of the total mass (total amount, unit: mass part) of the electron transport agent to the mass (amount, unit: mass part) of the hole transport agent. Show. M _ETM / M _HTM was calculated from the following formula. When M _ETM / M _HTM is larger than 1.00, it indicates that the content of the electron transport agent is larger than the content of the hole transport agent.
M _ETM / M _HTM = (Amount of first electron transfer agent + Amount of second electron transfer agent) / (Amount of hole transfer agent)

In Table 1 to Table 5, "M _ETM / M _L", the weight of the photoconductive layer (amount, unit: parts by weight): shows the ratio of relative, total mass (weight parts total weight, unit) of the electron transport agent. M _ETM / M _L was calculated from the following equation.
M _ETM / M _L = (Amount of first electron transfer agent + Amount of second electron transfer agent) / (Amount of charge generating agent + Amount of binder resin + Amount of hole transfer agent + Amount of first electron transfer agent) + Amount of second electron transport agent + amount of additive)

In Table 1 to Table 5, "M _RESIN / M _L", the weight of the photoconductive layer (amount, unit: parts by weight): shows the ratio of relative, of the binder resin weight (parts by volume, units). M _RESIN / M _L was calculated from the following equation.
M _RESIN / M _L = (amount of binder resin) / (amount of charge generating agent + amount of binder resin + amount of hole transport agent + amount of first electron transport agent + amount of second electron transport agent + additive Amount)

Each of the photoreceptors (A-1) to (A-33) was provided with a conductive substrate and a photosensitive layer. The photosensitive layer was a single layer and contained a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and an additive. The content of the electron transport agent was larger than the content of the hole transport agent. The content of the additive was 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin. The additive was a compound represented by the general formula (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6). Specifically, the additive was the compound (ADD1-1), (ADD2-1), (ADD3-1), (ADD4-1), (ADD5-1) or (ADD6-1). Therefore, as is clear from Tables 1 to 3, in Photoreceptors (A-1) to (A-33), ΔV ₀ was a small value of 37 or less, and the potential stability of the photoconductor was excellent. In the photoconductors (A-1) to (A-33), the evaluation of the exposure memory suppression was good (◯), and the generation of the exposure memory was suppressed. Furthermore, in the photoconductors (A-1) to (A-33), the number of generated cracks was 2 or less, the image evaluation was good (◯), and the photoconductor was excellent in crack resistance.

  On the other hand, the photosensitive layer of the photoreceptor (B-1) did not contain an additive. In the photoreceptor (B-1), the content of the electron transport agent was not more than the content of the hole transport agent. Therefore, as apparent from Table 4, in the photoreceptor (B-1), the potential stability and crack resistance of the photoreceptor were inferior, and exposure memory was generated.

  In each of the photoreceptors (B-2) to (B-9) and (B-12) to (B-14), the content of the electron transport agent was not larger than the content of the hole transport agent. Therefore, as is apparent from Tables 4 and 5, in the photoreceptors (B-2) to (B-9) and (B-12) to (B-14), the potential stability of the photoreceptor is inferior, and exposure is performed. Memory was occurring.

  The photosensitive layers of the photoreceptors (B-10) and (B-11) did not contain additives. Therefore, as is clear from Tables 4 and 5, the photoreceptors (B-10) and (B-11) were inferior in the potential stability and crack resistance of the photoreceptor.

  In the photoreceptor (B-15), the content of the additive was less than 10 parts by mass with respect to 100 parts by mass of the binder resin. Therefore, as apparent from Table 5, the photoreceptor (B-15) was inferior in the potential stability and crack resistance of the photoreceptor.

  In the photoreceptor (B-16), the additive content was more than 40 parts by mass with respect to 100 parts by mass of the binder resin. Therefore, as is apparent from Table 5, in the photoreceptor (B-16), no crack was generated in the evaluation of the number of cracks, but a dent was confirmed in the photosensitive layer. In addition, due to the dents in the photosensitive layer, clear white spots were confirmed in the formed image in the crack resistance image evaluation. For these reasons, the photoreceptor (B-16) was inferior in crack resistance, in particular, oil resistance against adhesion of oils and fats such as human dandruff.

  From the above, it was shown that the photoreceptor according to the present invention is excellent in potential stability and crack resistance and can suppress exposure memory. Further, it has been shown that the process cartridge and the image forming apparatus according to the present invention are excellent in potential stability and crack resistance and can suppress exposure memory.

  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.

30 Electrophotographic photoreceptor 32 Conductive substrate 34 Photosensitive layer 42 Charging unit 44 Exposure unit 46 Development unit 48 Transfer unit 100 Image forming apparatus P Recording medium

Claims (17)

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer,
The photosensitive layer is a single layer,
The photosensitive layer contains a charge generator, a hole transport agent, an electron transport agent, a binder resin and an additive,
The content of the electron transport agent is greater than the content of the hole transport agent,
The content of the additive is 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin.
The additive is an electrophotographic photoreceptor, which is a compound represented by the following general formula (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) or (ADD6).

In the general formula (ADD1),
R ¹¹¹ and R ¹¹² are each independently an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms, Represents a nitro group,
m1 and m2 each independently represents an integer of 0 or more and 5 or less.

In the general formula (ADD2),
R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ , R ¹²⁶ , R ¹²⁷ , R ¹²⁸ and R ¹²⁹ are each independently a hydrogen atom, a hydroxyl group, a halogen atom or a carbon atom number of 1 to 6 Represents an alkyl group.

In the general formula (ADD3),
R ¹³¹ , R ¹³² and R ¹³³ each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms,
n1, n2 and n3 each independently represents an integer of 0 or more and 5 or less.

In the general formula (ADD4),
R ¹⁴¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms,
R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ¹⁴⁶ each independently represents a hydrogen atom or an alkyl group having 4 to 8 carbon atoms, and at least one of R ¹⁴² , R ¹⁴³ , R ¹⁴⁵ and R ¹⁴⁶ is Represents an alkyl group having 4 to 8 carbon atoms,
R ¹⁴⁴ represents —R ¹⁴⁷ —CO—O—R ¹⁴⁸ —, and R ¹⁴⁷ and R ¹⁴⁸ each independently represents an alkylene group having 1 to 8 carbon atoms.

In the general formula (ADD5),
R ¹⁵¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms,
R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ each independently represent a hydrogen atom or an alkyl group having 4 to 8 carbon atoms, and at least one of R ¹⁵² , R ¹⁵³ , R ¹⁵⁵ and R ¹⁵⁶ is Represents an alkyl group having 4 to 8 carbon atoms,
R ¹⁵⁴ is a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms having an aryl group having 6 to 14 carbon atoms. Or an alkyl group having 1 to 8 carbon atoms having an alkoxycarbonyl group having 1 to 20 carbon atoms.

In the general formula (ADD6),
R ¹⁶¹ and R ¹⁶² each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms,
p1 and p2 each independently represent an integer of 0 or more and 5 or less. The compound represented by the general formula (ADD1) is a compound represented by the following chemical formula (ADD1-1),
The compound represented by the general formula (ADD2) is a compound represented by the following chemical formula (ADD2-1),
The compound represented by the general formula (ADD3) is a compound represented by the following chemical formula (ADD3-1),
The compound represented by the general formula (ADD4) is a compound represented by the following chemical formula (ADD4-1),
The compound represented by the general formula (ADD5) is a compound represented by the following chemical formula (ADD5-1),
The electrophotographic photoreceptor according to claim 1, wherein the compound represented by the general formula (ADD6) is a compound represented by the following chemical formula (ADD6-1).

  The electrophotographic photosensitive member according to claim 1, wherein the compounds represented by the general formulas (ADD1), (ADD2), (ADD3), (ADD4), (ADD5) and (ADD6) are crack inhibitors. body. Two or more types of the electron transfer agent are contained,
The ratio of the total mass of the said 2 or more types of said electron transport agent with respect to the mass of the said hole transport agent is larger than 1.00 and is 1.50 or less, The electrophotography as described in any one of Claims 1-3. Photoconductor. The electron transport agent is any one of the compounds represented by the following general formulas (ET1), (ET2), (ET3), (ET4), and (ET5), according to any one of claims 1 to 4. The electrophotographic photosensitive member according to one item.

Formula (ET1), (ET2), (ET4) and (ET5) ^{in, R 1, R 2, R} 3, R 4, R 5, R 8, R 9, R 10, R 11, R 12, R ¹³ and R ¹⁴ are each independently a hydrogen atom, a halogen atom, a cyano group, an optionally substituted alkyl group having 1 to 6 carbon atoms, or an optionally substituted carbon atom. An alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, and an aryl group having 6 to 14 carbon atoms which may have a substituent,
In the general formula (ET2), W represents -CO-O- or -CO-,
In the general formula (ET3),
R ⁶ and R ⁷ are each independently
An aryl group having 6 to 14 carbon atoms,
An aryl group having 6 to 14 carbon atoms having at least one alkyl group having 1 to 6 carbon atoms,
An aryl group having 6 to 14 carbon atoms and having a phenylcarbonyl group,
An aralkyl group having 7 to 20 carbon atoms,
Represents a group selected from the group consisting of an alkyl group having 1 to 8 carbon atoms which may have an alkoxy group having 1 to 6 carbon atoms, and a cycloalkyl group having 3 to 10 carbon atoms, The selected group may be substituted with one or more halogen atoms. In the general formula (ET1), R ¹ and R ² each independently represents an alkyl group having 1 to 6 carbon atoms,
In the general formula (ET2), R ³ , R ⁴ and R ⁵ each independently have a hydrogen atom, an aryl group having 6 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms. Represents an alkyl group having 1 to 6 carbon atoms, W represents -CO-O-,
The compound represented by the general formula (ET3) satisfies the condition (3-A) or (3-B),
In the condition (3-A), R ⁶ and R ⁷ are each independently
An aryl group having 6 to 14 carbon atoms and having at least one alkyl group having 1 to 6 carbon atoms,
In the condition (3-B), R ⁶ and R ⁷ are each independently
An aryl group having 6 to 14 carbon atoms,
An aryl group having 6 to 14 carbon atoms having at least one alkyl group having 1 to 6 carbon atoms,
An aryl group having 6 to 14 carbon atoms and having a phenylcarbonyl group,
An aralkyl group having 7 to 20 carbon atoms,
It represents a group selected from the group consisting of an alkyl group having 1 to 8 carbon atoms and a cycloalkyl group having 3 to 10 carbon atoms, and the selected group is substituted with one or more halogen atoms. And at least one of R ⁶ and R ⁷ has one or more halogen atoms,
In the general formula (ET4), R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ each independently represents an alkyl group having 1 to 6 carbon atoms,
In the general formula (ET5), R ¹² and R ¹³ each independently represent an alkyl group having 1 to 6 carbon atoms, R ¹⁴ represents a halogen atom, an electrophotographic of claim 5 Photoconductor. The compound represented by the general formula (ET1) is a compound represented by the following chemical formula (ET1-1),
The compound represented by the general formula (ET2) is a compound represented by the following chemical formula (ET2-1),
The compound represented by the general formula (ET3) that satisfies the condition (3-A) is a compound represented by the following chemical formula (ET3-A1),
The compound represented by the general formula (ET3) that satisfies the condition (3-B) is a compound represented by the following chemical formula (ET3-B1), (ET3-B2), or (ET3-B3),
The compound represented by the general formula (ET4) is a compound represented by the following chemical formula (ET4-1),
The electrophotographic photoreceptor according to claim 6, wherein the compound represented by the general formula (ET5) is a compound represented by the following chemical formula (ET5-1).

Two or more kinds of the electron transport agents are two kinds of the electron transport agents,
Whether the additive is a compound represented by the general formula (ADD2) and the two electron transporting agents are compounds represented by the general formulas (ET1) and (ET4);
Whether the additive is a compound represented by the general formula (ADD5), and the two electron transport agents are compounds represented by the general formulas (ET1) and (ET4),
The additive is a compound represented by the general formula (ADD2), and the two electron transport agents are compounds represented by the general formulas (ET1) and (ET5),
Whether the additive is a compound represented by the general formula (ADD2), and the two electron transport agents are compounds represented by the general formulas (ET4) and (ET5),
The additive is a compound represented by the general formula (ADD3), and the two types of electron transport agents are compounds represented by the general formulas (ET4) and (ET5),
Whether the additive is a compound represented by the general formula (ADD5), and the two electron transport agents are compounds represented by the general formulas (ET4) and (ET5),
The additive is a compound represented by the general formula (ADD6), and the two electron transport agents are compounds represented by the general formulas (ET4) and (ET5), or the additive is A compound represented by the general formula (ADD2), wherein the two electron transfer agents satisfy the condition (3-B) and the general formula (ET3) and the general formula (ET1) The electrophotographic photosensitive member according to claim 6, wherein the electrophotographic photosensitive member is a represented compound. Two or more kinds of the electron transport agents are two kinds of the electron transport agents,
Whether the additive is a compound represented by the general formula (ADD2) and the two electron transporting agents are compounds represented by the general formulas (ET1) and (ET4);
The additive is a compound represented by the general formula (ADD2), and the two electron transport agents are compounds represented by the general formulas (ET1) and (ET5),
The additive is a compound represented by the general formula (ADD2), and the two electron transport agents are compounds represented by the general formulas (ET4) and (ET5), or the additive is A compound represented by the general formula (ADD2), wherein the two electron transfer agents satisfy the condition (3-B) and the general formula (ET3) and the general formula (ET1) The electrophotographic photosensitive member according to any one of claims 6 to 8, which is a represented compound. Two or more kinds of the electron transport agents are two kinds of the electron transport agents,
The additive is a compound represented by the general formula (ADD2), and the two types of electron transport agents satisfy the condition (3-B) and the compound represented by the general formula (ET3) and the general formula The electrophotographic photosensitive member according to any one of claims 6 to 9, which is a compound represented by (ET1). The compound represented by the general formula (ET3) that satisfies the condition (3-B) is a compound represented by the following chemical formula (ET3-B1), (ET3-B2), or (ET3-B3), Item 11. The electrophotographic photosensitive member according to Item 10.

  The electrophotographic photosensitive member according to any one of claims 1 to 11, wherein a ratio of a mass of the electron transfer agent to a mass of the photosensitive layer is 0.24 or more and 0.30 or less.   The electrophotographic photosensitive member according to any one of claims 1 to 12, wherein a ratio of a mass of the binder resin to a mass of the photosensitive layer is less than 0.50.   A process cartridge comprising the electrophotographic photosensitive member according to claim 1. An image forming apparatus comprising the electrophotographic photosensitive member according to any one of claims 1 to 13, a charging unit, an exposure unit, a developing unit, and a transfer unit,
The charging unit charges the surface of the electrophotographic photosensitive member to a positive polarity,
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 is an image forming apparatus that transfers the toner image from the electrophotographic photosensitive member to a transfer target.   The image forming apparatus according to claim 15, wherein a light source of the exposure unit is a light emitting diode.   The area on the surface of the electrophotographic photosensitive member on which the toner image is transferred from the electrophotographic photosensitive member to the transfer target by the transfer unit is charged again by the charging unit without being neutralized. The image forming apparatus according to 15 or 16.

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