JP6635021B2 - Positively-charged laminated electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Description

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

  As one example of the electrophotographic photosensitive member, an electrophotographic photosensitive member for positive charging is known. The electrophotographic photosensitive member for positive charging described in Patent Document 1 has a carrier transport layer and a carrier generation layer on a conductive support in this order. The carrier generation layer contains a P-type carrier transporting substance and an N-type carrier transporting substance.

JP-A-4-242259

  However, in the electrophotographic photosensitive member for positive charging described in Patent Document 1, the amount ratio of the N-type carrier transporting substance to the P-type carrier transporting substance in the carrier generation layer is 0.01 to 1.0. The present inventors have found that such a positively charged electrophotographic photoreceptor is insufficient in suppressing generation of transfer memory.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a positively-charged laminated electrophotographic photoreceptor capable of suppressing both crystallization of a photosensitive layer and generation of a transfer memory. is there. Another object of the present invention is to provide a process cartridge and an image forming apparatus that include such a positively-charged laminated electrophotographic photosensitive member and that can suppress occurrence of image defects due to a transfer memory in a formed image. is there.

  The positively charged laminated electrophotographic photoreceptor of the present invention includes a conductive substrate, a charge transport layer provided on the conductive substrate, and a charge generation layer provided on the charge transport layer. The charge generating layer contains a charge generating agent, a first hole transporting agent, a first electron transporting agent, and a first binder resin. The first electron transporting agent contains at least two of the compounds represented by the general formulas (1-1), (2), (3), (4) and (5-1). The ratio of the total mass of the two or more first electron transporting agents to the mass of the first binder resin is 0.45 or more. The total mass of the two or more first electron transporting agents is greater than the mass of the first hole transporting agent. The charge transport layer contains a second hole transport agent and a second electron transport agent.

In the general formulas (1-1), (2) and (3), R ¹ , R ² , R ³ , R ⁴ , 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 nitro group, a cyano group, an alkyl group having 1 to 6 carbon atoms which may have a substituent, and 2 carbon atoms which may have a substituent. An alkenyl group having at least 6 or less, an alkoxy group having at least 1 and at most 6 carbon atoms which may have a substituent, an aryl group having at least 6 and at most 14 carbon atoms which may have a substituent or a substituent. Represents a cycloalkyl group having 3 to 8 carbon atoms which may be substituted. However, R ¹⁴ is not a hydrogen atom. In the general formula (4), R ⁶ and R ⁷ each independently represent a hydrogen atom, a nitro group, a cyano group, an alkenyl group having 2 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. A cycloalkyl group having 3 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms which may have at least one alkoxy group having 1 to 6 carbon atoms, or 1 to 6 carbon atoms Represents an aryl group having 6 to 14 carbon atoms which may have at least one of the following alkyl groups. In the general formula (5-1), Q ⁶ and Q ⁷ each independently represent an aryl group having 6 or more and 14 or less carbon atoms, which may have one or more halogen atoms, and one or more halogen atoms. A benzoyl group which may have an atom, an aryl group having 6 or more and 14 or less carbon atoms having at least one alkyl group having 1 or more and 6 or less carbon atoms, and which may have one or more halogen atoms. At least one aryl group having 6 or more and 14 or less carbon atoms, an aralkyl group having 7 or more and 20 or less carbon atoms which may have one or more halogen atoms, or one or more halogen atoms may be present. 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 which may have one or more halogen atoms. At least one of Q ⁶ and Q ⁷ has one or more halogen atoms.

  A process cartridge of the present invention includes the above-described positively-charged laminated electrophotographic photosensitive member.

  An image forming apparatus of the present invention includes the above-described positively-charged laminated electrophotographic photosensitive member, a charging unit, an exposure unit, a development unit, and a transfer unit. The charging unit positively charges the surface of the positively-charged electrophotographic photosensitive member. The exposure unit exposes the charged surface of the positively-charged electrophotographic photosensitive member to form an electrostatic latent image on the surface of the positively-charged electrophotographic photoconductor. The developing unit supplies toner to the electrostatic latent image and develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the positively-charged laminated electrophotographic photosensitive member to a transfer target.

  ADVANTAGE OF THE INVENTION According to the positively-charged electrophotographic photosensitive member of this invention, suppression of crystallization of a photosensitive layer and suppression of generation | occurrence | production of transfer memory can be compatible. Further, 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 suppress the occurrence of image ghost due to the transfer memory in the formed image.

(A), (b) and (c) are partial cross-sectional views each showing an example of a positively charged laminated electrophotographic photosensitive member according to an embodiment of the present invention. It is an example of a CuKα characteristic X-ray diffraction spectrum chart of titanyl phthalocyanine. It is an example of a differential scanning calorimetry spectrum chart of titanyl phthalocyanine. FIG. 1 is a diagram illustrating an example of a configuration of an image forming apparatus. The image forming apparatus includes a positively-charged laminated electrophotographic photosensitive member according to an embodiment of the present disclosure. FIG. 5 is an enlarged view of a region V shown in FIG. 4.

  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 present invention. In addition, although the description may be omitted as appropriate for portions where the description is duplicated, the gist of the invention is not limited.

  Hereinafter, a compound and its derivative may be generically referred to by adding “system” after the compound name. Further, when a polymer name is indicated by adding “system” after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative.

  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 3 carbon atoms, carbon atom Alkenyl group having 2 to 6 atoms, alkenyl group having 2 to 4 carbon atoms, alkoxy group having 1 to 6 carbon atoms, alkoxy group having 1 to 3 carbon atoms, 6 to 14 carbon atoms An aryl group having 6 to 10 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 The cycloalkyl group having 3 to 8 atoms and the cycloalkyl group having 5 to 7 carbon atoms have the following meanings unless otherwise specified.

  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, and an alkyl group having 1 to 3 carbon atoms are each straight-chain. Or branched and unsubstituted. Examples of the alkyl group having 1 to 8 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl. Group, neopentyl group, 1,2-dimethylpropyl group, 1-ethyl-1-methylpropyl group, n-hexyl group, heptyl group and octyl group. Examples of the alkyl group having 1 to 6 carbon atoms are groups having 1 to 6 carbon atoms among the groups described as examples of the alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 5 carbon atoms are groups having 1 to 5 carbon atoms among the groups described as examples of the alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms are groups having 1 to 3 carbon atoms among the groups described as examples of the alkyl group having 1 to 8 carbon atoms.

  The alkenyl group having 2 to 6 carbon atoms and the alkenyl group having 2 to 4 carbon atoms are each linear or branched and unsubstituted. An alkenyl group having 2 to 6 carbon atoms has, for example, 1 to 3 double bonds. Examples of the alkenyl group having 2 to 6 carbon atoms include a vinyl group (ethenyl group), a propenyl group, a butenyl group, a pentenyl group, a pentadienyl group, a hexenyl group, and a hexadienyl group. Examples of the alkenyl group having 2 to 4 carbon atoms are groups having 2 to 4 carbon atoms among the groups described as examples of the alkenyl group having 2 to 6 carbon atoms.

  The alkoxy group having 1 to 6 carbon atoms and the alkoxy group having 1 to 3 carbon atoms are each linear or branched and unsubstituted. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, Isopentoxy, neopentoxy and hexyl groups. Examples of the alkoxy group having 1 to 3 carbon atoms are groups having 1 to 3 carbon atoms among the groups described as examples of the alkoxy group having 1 to 6 carbon atoms.

  Each of the aryl group having 6 to 14 carbon atoms and the aryl group having 6 to 10 carbon atoms is unsubstituted. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an indacenyl group, a biphenylenyl group, an acenaphthenyl group, an anthryl group, and a phenanthryl group. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group.

  The aralkyl group having 7 to 20 carbon atoms and the aralkyl group having 7 to 9 carbon atoms are each unsubstituted. The aralkyl group having 7 to 20 carbon atoms is, for example, an alkyl group having 1 to 6 carbon atoms having an aryl group having 6 to 14 carbon atoms. The alkyl group having 1 to 6 carbon atoms in the aralkyl group having 7 to 20 carbon atoms is linear or branched. 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.

  The cycloalkyl group having 3 to 10 carbon atoms, the cycloalkyl group having 3 to 8 carbon atoms, and the cycloalkyl group having 5 to 7 carbon atoms are each 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. Examples of the cycloalkyl group having 3 to 8 carbon atoms are groups having 3 to 8 carbon atoms among the groups described as examples of the cycloalkyl group having 3 to 10 carbon atoms. Examples of the cycloalkyl group having 5 to 7 carbon atoms are groups having 5 to 7 carbon atoms among the groups described as examples of the cycloalkyl group having 3 to 10 carbon atoms.

<1. Photoconductor>
The present embodiment relates to a positively-charged laminated electrophotographic photosensitive member (hereinafter, referred to as a photosensitive member). Hereinafter, the structure of the photoconductor 30 will be described with reference to FIGS. 1A to 1C are cross-sectional views each showing an example of the photoconductor 30 according to the present embodiment.

  As shown in FIG. 1A, the photoconductor 30 includes, for example, a conductive substrate 31, a charge transport layer 32, and a charge generation layer 33. The charge transport layer 32 is provided on the conductive substrate 31. The charge generation layer 33 is provided on the charge transport layer 32. The photosensitive layer includes a charge transport layer 32 and a charge generation layer 33. The photoconductor 30 is a laminated electrophotographic photoconductor including a charge transport layer 32 and a charge generation layer 33 as photosensitive layers. The photoconductor 30 can be positively charged. Specifically, when the photoconductor 30 is provided in the image forming apparatus 100 (see FIG. 4), the charging unit 42 (see FIG. 4) can charge the photoconductor 30 to a positive polarity.

  The photoconductor 30 of the positively-charged laminated type has the following advantages as compared with the negatively-charged electrophotographic photoreceptor. In the negatively charged laminated electrophotographic photoreceptor, a charge generation layer is usually provided on a conductive substrate, and a charge transport layer is provided on the charge generation layer. When the negatively charged laminated electrophotographic photosensitive member is provided in an image forming apparatus, it is charged to a negative polarity by a charging section.

  The first advantage of the positively-charged photoconductor 30 is that the resolution is improved. In the negatively charged laminated electrophotographic photosensitive member, charges (holes and electrons) are generated in the charge generation layer on the conductive substrate during exposure. The generated holes move through the charge generation layer and the charge transport layer on the charge generation layer, and reach the surface of the charge transport layer. Then, the holes that reach the surface of the charge transport layer cancel the negative charges on the surface of the charge transport layer. In the negatively charged laminated electrophotographic photoreceptor, since the hole travels a long distance, the hole may reach a position slightly away from the exposed portion while the hole is moving. Therefore, the resolution may be reduced in the negatively-charged laminated electrophotographic photosensitive member. However, in the photoconductor 30 of the positively charged lamination type, charges (holes and electrons) are generated in the charge generation layer 33 near the surface 30a (see FIG. 5) of the photoconductor 30 during exposure. The generated electrons move through the charge generation layer 33 and reach the surface of the charge generation layer 33. Then, the electrons reaching the surface of the charge generation layer 33 cancel the positive charges on the surface of the charge generation layer 33. Since the moving distance of the electrons in the photoconductor 30 is short, the electrons tend to reach the same location as the exposed location. Therefore, the resolution of the photoconductor 30 of the positively charged laminated type is improved.

  A second advantage of the positively-charged photoconductor 30 is that ozone is hardly generated. Since the negatively charged laminated electrophotographic photosensitive member is negatively charged, ozone may be generated during image formation. However, since the photoconductor 30 is charged to a positive polarity, it is considered that generation of ozone can be suppressed.

  As shown in FIG. 1B, the photoconductor 30 may include a conductive substrate 31, a charge transport layer 32, a charge generation layer 33, and an intermediate layer 34 (undercoat layer). The intermediate layer 34 is provided between the conductive substrate 31 and the charge transport layer 32. As shown in FIG. 1A, the charge transport layer 32 may be provided directly on the conductive base 31, or as shown in FIG. It may be provided over the intermediate layer 34.

  As shown in FIG. 1C, the photoconductor 30 may include a conductive substrate 31, a charge transport layer 32, a charge generation layer 33, and a protective layer 35. The protection layer 35 is provided on the charge generation layer 33. However, in order to improve the photosensitivity of the photoconductor 30 at the time of exposure, it is preferable that the photoconductor 30 does not include the protective layer 35. When the photoconductor 30 does not include the protective layer 35, the charge generation layer 33 is provided as the outermost surface layer of the photoconductor 30.

  The thicknesses of the charge generation layer 33 and the charge transport layer 32 are not particularly limited as long as they can function as the respective layers. The thickness of the charge generation layer 33 is preferably 0.01 μm or more and 30 μm or less, more preferably 5 μm or more and 20 μm or less, and even more preferably 8 μm or more and 15 μm or less. The thickness of the charge transport layer 32 is preferably 2 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less.

  The photoreceptor 30 according to the present embodiment can achieve both suppression of crystallization of the photosensitive layer and suppression of occurrence of transfer memory. The reason is presumed as follows.

  First, a transfer memory will be described for easy understanding. When an image is formed on the recording medium P (see FIG. 4) using the image forming apparatus 100 including the photoconductor 30, the charging process, the exposure process, the developing process, and the transfer process are performed while the photoconductor 30 rotates once. Done. In the charging step, the surface 30a (see FIG. 5) of the photoconductor 30 is charged to a certain positive potential. Subsequently, through an exposure step and a development step, in the transfer step, a transfer bias (negative transfer bias) having a polarity opposite to that of the charging is exposed to light via the transfer target (for example, the intermediate transfer belt 56, see FIG. 4). Applied to body 30. The potential of the non-exposed area (non-image area) on the surface 30a of the photoreceptor 30 may decrease due to the influence of the applied transfer bias of the opposite polarity, and the state where the potential has decreased may be maintained. Under the influence of the potential drop, the non-exposed area is less likely to be charged to a desired positive potential in the next charging step. On the other hand, since the toner adheres to the exposure area (image area) on the surface 30a of the photoconductor 30, it is difficult to directly apply the transfer bias to the exposure area. Therefore, even when a transfer bias is applied, the potential of the exposed region is unlikely to decrease. As a result, a difference may occur in the charged potential of the surface 30a of the photoconductor 30 in the next circumference between the exposed area and the non-exposed area. As described above, due to the influence of the transfer bias, on the surface 30a of the photoconductor 30, the charging potential of the area corresponding to the previous non-exposed area is lower than that of the area corresponding to the previous exposed area. , Called transfer memory. The transfer memory is likely to occur when an image is formed at a high speed. This is because, when an image is formed at a high speed, the transfer conditions for applying a strong transfer bias to the photoconductor 30 are often set. When a transfer memory is generated in the photoconductor 30, a negative ghost easily occurs in a formed image. The negative ghost is an image defect in which, in a formed image, an area corresponding to a non-exposed area on the periphery in front of the photoconductor 30 is darkened.

  Here, in the charge generation layer 33 of the photoconductor 30 of the present embodiment, the total mass of the two or more first electron transporting agents is larger than the mass of the first hole transporting agent. Usually, in the charge generation layer, the mass of the first electron transporting agent is smaller than the mass of the first hole transporting agent. The reason is as follows. When the photoconductor 30 is exposed during image formation, electrons and holes are generated from the charge generating agent in the charge generating layer 33. The generated electrons are transported to the surface of the charge generation layer 33 by the first electron transport agent. The generated holes are transported to the charge transport layer 32 by the first hole transport agent, and further transported to the conductive substrate 31. The transmittance of the exposed light is high near the surface of the charge generation layer 33 and low in the deep part of the charge generation layer 33 (on the side of the charge transport layer 32). Therefore, many electrons and holes tend to be generated from the charge generating agent existing near the surface of the charge generating layer 33 having high transmittance of the exposed light. When electrons and holes are generated from the charge generating agent existing near the surface of the charge generation layer 33, the distance of the holes to the charge transport layer 32 is longer than the distance of the electrons to the surface of the charge generation layer 33. long. Therefore, it is common to include a larger amount of the first hole transporting agent than the first electron transporting agent. However, the present inventors have studied diligently, and by increasing the total mass of two or more first electron transporting agents in the charge generation layer 33 to be greater than the mass of the first hole transporting agent, the transfer memory Can be suppressed.

  Further, the first electron transporting agent has a chemical structure that is hardly dissolved in a solvent for forming the charge generation layer 33. However, as the first electron transport agent in the charge generation layer 33, two or more of the compounds represented by the general formulas (1-1), (2), (3), (4), and (5-1) , The solubility of the first electron transporting agent in the solvent for forming the charge generation layer 33 can be improved. Thereby, many first electron transporting agents can be dissolved in the solvent for forming the charge generation layer 33. As a result, in the charge generation layer 33, the total mass of the two or more first electron transporting agents can be larger than the mass of the first hole transporting agent. Thereby, the generation of the transfer memory can be suppressed while the crystallization of the charge generation layer 33 is suppressed.

  Further, in the charge generation layer 33, two or more of the compounds represented by the general formulas (1-1), (2), (3), (4) and (5-1) are used as the first electron transporting agent. By containing it, the compatibility between the first binder resin contained in the charge generation layer 33 and the first electron transporting agent is improved. Thereby, while suppressing the crystallization of the charge generation layer 33, the ratio of the total mass of the two or more types of first electron transporting agents to the mass of the first binder resin can be set to 0.45 or more. As a result, the occurrence of transfer memory can be suppressed while the crystallization of the charge generation layer 33 is suppressed.

  The charge transport layer 32 contains a second hole transport agent and a second electron transport agent. As described above, when the photoconductor 30 is exposed during image formation, electrons and holes are generated from the charge generating agent in the charge generating layer 33. The generated electrons are transported to the surface of the charge generation layer 33 by the first electron transporting agent, and the generated holes are transported to the charge transporting layer 32 by the first hole transporting agent. It is transported to the base 31. Therefore, it is considered that it is sufficient that the charge transport layer 32 contains the second hole transport agent. However, the present inventors diligently studied, and found that the generation of transfer memory can be suitably suppressed when the charge transport layer 32 further contains a second electron transport agent in addition to the second hole transport agent.

  In the above, the structure of the photoconductor 30 and the reason why it is assumed that the photoconductor 30 exhibits the effect have been described with reference to FIGS. 1A to 1C. Hereinafter, the photoconductor according to the exemplary embodiment will be further described.

<1-1. Conductive substrate>
As an example of the conductive substrate, a conductive substrate formed of a conductive material is given. Another example of the conductive substrate includes a conductive substrate provided with a coating layer formed 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 conductive materials, aluminum or an aluminum alloy is preferable because charge transfer from the charge transport 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 and a drum shape. Further, the thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

<1-2. Charge generation layer>
The charge generating layer contains a charge generating agent, a first hole transporting agent, a first electron transporting agent, and a first binder resin. The first hole transport agent is a hole transport agent contained in the charge generation layer. The first electron transport agent is an electron transport agent contained in the charge generation layer. The first binder resin is a binder resin contained in the charge generation layer 33. The charge generation layer 33 may contain an additive as needed.

In the charge generating layer, the total weight of the two or more first electron transport material (M _ETM1) is greater than the mass of the first hole transporting material (M _HTM1). That is, in the charge generation layer, with respect to the mass of the first hole transporting material (M _HTM1), a ratio of two or more of the total weight of the first electron transport material _{(M ETM1) (M ETM1 /} M HTM1) is 1. Greater than 00. When two or more of the total weight of the first electron transport material (M _ETM1) is the same or less the mass of the first hole transporting material (M _HTM1), as already mentioned, the transfer memory is produced. In order to further suppress the crystallization of the charge generation layer and the generation of the transfer memory, the ratio ( _METM1 / _MHTM1 ) is preferably larger than 1.00 and smaller than 1.60, and larger than 1.00 and smaller than 1.60. It is more preferably 50 or less, further preferably 1.05 or more and 1.30 or less, further preferably 1.05 or more and 1.20 or less, and more preferably 1.10 or more and 1.13 or less. Is particularly preferred.

The ratio of the total weight of the first electron transporting material of the mass of the first binder resin (M _RESIN1) 2 or more with respect to (preferably two or _{three) (M ETM1) (M ETM1} / M RESIN1) 0.45 That is all. If the ratio ( _METM1 / _MRESIN1 ) is less than 0.45, transfer memory occurs. In order to further suppress the occurrence of transfer memory, the ratio ( _METM1 / _MRESIN1 ) is more preferably 0.50 or more. In order to further suppress crystallization of the charge generation layer, the ratio (M _ETM1 / M _RESIN1 ) is preferably 0.80 or less, more preferably 0.60 or less, and more preferably 0.55 or less. It is even more preferred.

The ratio (M _ETM1 / M _CGL ) of the total mass (M _ETM1 ) of two or more first electron transporting agents to the mass (M _CGL ) of the charge generation layer is preferably 0.20 or more, and 0.24 or more. More preferably, it is more preferably 0.25 or more. Further, the ratio (M _ETM1 / M _CGL ) is preferably 0.50 or less, more preferably 0.30 or less, and even more preferably 0.26 or less. The mass of the charge generation layer (M _CGL ) is the sum of the masses of all the materials included in the charge generation layer. For example, when the charge generation layer includes a charge generation agent, two or more types of first electron transporting agents, a first hole transporting agent, and a first binder resin, the mass of the charge generation layer (M _CGL ) It is the sum of the mass of the generator, the total mass of two or more first electron transport agents, the mass of the first hole transport agent, and the mass of the first binder resin.

The ratio (M _RESIN1 / M _CGL ) of the mass (M _RESIN1 ) of the first binder resin to the mass (M _CGL ) of the charge generation layer is preferably 0.55 or less, more preferably 0.53 or less. It is more preferably 0.52 or less. When the ratio (M _RESIN1 / M _CGL ) is 0.55 or less, the occurrence of transfer memory can be suitably suppressed. Further, the ratio (M _RESIN1 / M _CGL ) is preferably at least 0.40, more preferably at least 0.45, even more preferably at least 0.48. When the ratio (M _RESIN1 / M _CGL ) is 0.40 or more, it is considered that the wear resistance of the photoconductor can be improved.

The ratio (M _HTM1 / M _CGL ) of the mass (M _HTM1 ) of the first hole transporting agent to the mass (M _CGL ) of the charge generation layer is preferably 0.10 or more and 0.50 or less, and 0.20 or less. It is more preferably at least 0.30 and at most 0.30, more preferably at least 0.21 and at most 0.24.

The ratio (M _CGM / M _CGL ) of the mass (M _CGM ) of the charge generating agent to the mass (M _CGL ) of the charge generating layer is preferably 0.005 or more and 0.10 or less, and 0.01 or more and 0.1 or less. It is more preferable that it is 02 or less.

(First electron transport agent)
The first electron transporting agent contains at least two of the compounds represented by formulas (1-1), (2), (3), (4) and (5-1). Hereinafter, each of the compounds represented by the general formulas (1-1), (2), (3), (4), and (5-1) will be referred to as a compound (1-1), (2), (3) , (4) and (5-1). The charge generation layer contains two or more of compounds (1-1), (2), (3), (4) and (5-1) as a first electron transporting agent. Preferably, the reduction potential difference between each of the two or more first electron transporting agents is small.

In the general formulas (1-1), (2) and (3), R ¹ , R ² , R ³ , R ⁴ , 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 nitro group, a cyano group, an alkyl group having 1 to 6 carbon atoms which may have a substituent, and 2 or more carbon atoms which may have a substituent Having an alkenyl group of 6 or less, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, an aryl group having 6 to 14 carbon atoms which may have a substituent or a substituent Represents a cycloalkyl group having 3 to 8 carbon atoms. However, R ¹⁴ is not a hydrogen atom. That is, R ¹⁴ is a halogen atom, a nitro group, a cyano group, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or an alkyl group having 2 to 6 carbon atoms which may have a substituent. An alkenyl group, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, an aryl group having 6 to 14 carbon atoms which may have a substituent or carbon which may have a substituent Represents a cycloalkyl group having 3 to 8 atoms.

In the general formula (4), R ⁶ and R ⁷ are each independently a hydrogen atom; a nitro group; a cyano group; an alkenyl group having 2 to 6 carbon atoms; an alkoxy group having 1 to 6 carbon atoms; A cycloalkyl group having 3 to 8 carbon atoms; an alkyl group having 1 to 6 carbon atoms which may have at least one alkoxy group having 1 to 6 carbon atoms; or 1 to 6 carbon atoms Represents an aryl group having 6 to 14 carbon atoms which may have at least one alkyl group.

In the general formula (5-1), Q ⁶ and Q ⁷ are each independently an aryl group having 6 to 14 carbon atoms which may have one or more halogen atoms; one or more halogen atoms An aryl group having 6 or more and 14 or less carbon atoms having at least one alkyl group having 1 or more and 6 or less carbon atoms; having at least one benzoyl group which may have one or more halogen atoms. One aryl group having 6 to 14 carbon atoms; an aralkyl group having 7 to 20 carbon atoms which may have one or more halogen atoms; a carbon atom having one or more halogen atoms which may have one or more halogen 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 which may have one or more halogen atoms. At least one of Q ⁶ and Q ⁷ has one or more halogen atoms. That is, compound (5-1) has a halogen atom indispensably.

R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in the general formulas (1-1), (2) and (3) The halogen atom (halogen group) represented is preferably a chlorine atom (chloro group).

R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in the general formulas (1-1), (2) and (3) As the alkyl group having 1 to 6 carbon atoms represented, an alkyl group having 1 to 5 carbon atoms is preferable, and a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, a 1,1-dimethylpropyl group , 1-ethyl-1-methylpropyl group, 1,2-dimethylpropyl group or n-pentyl 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, and a cyano group. As the substituent of the alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms is preferable, and a phenyl group is more preferable. The number of substituents is not particularly limited, but is preferably 3 or less. Examples of the substituent further possessed by the aryl group having 6 to 14 carbon atoms include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. Group, nitro group, cyano group, alkanoyl group having 2 to 7 carbon atoms (carbonyl group having alkyl group having 1 to 6 carbon atoms), benzoyl group, phenoxy group, alkoxy having 2 to 7 carbon atoms A carbonyl group (a carbonyl group having an alkoxy group having 1 to 6 carbon atoms) and a phenoxycarbonyl group.

R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in the general formulas (1-1), (2) and (3) The represented alkenyl group having 2 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, 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 ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in the general formulas (1-1), (2) and (3) The alkoxy group having 1 to 6 carbon atoms represented is preferably an alkoxy group having 1 to 3 carbon atoms, and more preferably a methoxy group. The alkoxy 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, 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 ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in the general formulas (1-1), (2) and (3) As the represented aryl group having 6 to 14 carbon atoms, a phenyl group is preferable. 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 and a biphenyl group. As the substituent on the aryl group having 6 to 14 carbon atoms, an alkyl group or a nitro group having 1 to 6 carbon atoms is preferable, and a methyl group, an ethyl group, or a nitro group is more preferable. The number of substituents is not particularly limited, but is preferably 3 or less.

R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ in the general formulas (1-1), (2) and (3) The cycloalkyl group having 3 to 8 carbon atoms represented is preferably a cycloalkyl group having 5 to 7 carbon atoms, and more preferably a cyclohexyl group. The cycloalkyl group having 3 to 8 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, an aryl group having 6 to 14 carbon atoms, and a cyano group. Can be The number of substituents is not particularly limited, but is preferably 3 or less.

In the general formula (1-1), R ¹ , R ² , R ³ and R ⁴ are each independently a carbon atom number of 1 to 6 which may have an aryl group of 6 to 14 carbon atoms. Preferably represents an alkyl group, a hydrogen atom, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cycloalkyl group having 3 to 8 carbon atoms.

In the general formula (1-1), R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms, which may have an aryl group having 6 to 14 carbon atoms; An alkoxy group having 1 to 6 carbon atoms; an aryl group having 6 to 14 carbon atoms; or a cycloalkyl group having 3 to 8 carbon atoms, wherein R ³ and R ⁴ are each independently a carbon atom. More preferably, it represents 1 to 6 alkyl groups or hydrogen atoms.

In the general formula (1-1), R ¹ and R ² each independently represent a methyl group, an isopropyl group, a 1-ethyl-1-methylpropyl group, an n-pentyl group, a cyclohexyl group, a tert-butyl group, Represents a 1,1-dimethylpropyl group, a phenylmethyl group, a phenyl group or a methoxy group; R ¹ and R ² represent the same group; R ³ and R ⁴ each independently represent a methyl group or a hydrogen atom; It is more preferred to represent.

In the general formula (1-1), R ¹ and R ² each independently represent a tert-butyl group, a 1,1-dimethylpropyl group or a methoxy group, and R ¹ and R ² represent the same group. , R ³ and R ⁴ each particularly preferably represent a hydrogen atom.

R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ in the general formula (2) each independently represent an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms or a carbon atom number. It is preferable to represent 3 to 8 cycloalkyl groups. More preferably, R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ in the general formula (2) each independently represent an alkyl group having 1 to 6 carbon atoms. When R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ represent an alkyl group having 1 to 6 carbon atoms, R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ each represent an alkyl group having 1 to 6 carbon atoms. May represent the same group, or may represent different groups among the alkyl groups having 1 to 6 carbon atoms. R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ in the general formula (2) each independently represent a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, an n-pentyl group or 1,1-dimethylpropyl. More preferably it represents a group. R ⁸ and R ¹⁰ in the general formula (2) preferably represent the same group. It is preferable that R ⁹ and R ¹¹ in the general formula (2) represent the same group.

R ¹² and R ¹³ in the general formula (3) each independently preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group, an isopropyl group or a tert-butyl group. R ¹⁴ in the general formula (3) preferably represents a halogen atom. The bonding position of R ^{14 in} the general formula (3) is not particularly limited. To the nitrogen atom of the phenyl group which R ¹⁴ is attached is bound, R ¹⁴ is ortho this phenyl group may be attached at the para-position or meta position, preferably binds at the para position.

As the alkenyl group having 2 to 6 carbon atoms represented by R ⁶ and R ⁷ in the general formula (4), an alkenyl group having 2 to 4 carbon atoms is preferable.

As the alkoxy group having 1 to 6 carbon atoms represented by R ⁶ and R ⁷ in the general formula (4), an alkoxy group having 1 to 3 carbon atoms is preferable.

The cycloalkyl group having 3 to 8 carbon atoms represented by R ⁶ and R ⁷ in the general formula (4) is preferably a cycloalkyl group having 5 to 7 carbon atoms.

As the alkyl group having 1 to 6 carbon atoms represented by R ⁶ and R ⁷ in the general formula (4), an alkyl group having 1 to 5 carbon atoms is preferable, and a methyl group, an ethyl group, an isopropyl group Tert-butyl group, 1,1-dimethylpropyl group, 1-ethyl-1-methylpropyl group, 1,2-dimethylpropyl group or n-pentyl group is more preferable, and ethyl group or 1,2-dimethylpropyl group Is more preferred. The alkyl group having 1 to 6 carbon atoms may have at least one alkoxy group having 1 to 6 carbon atoms. As the alkoxy group having 1 to 6 carbon atoms in the alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 3 carbon atoms is preferable, and an ethoxy group is more preferable. The number of alkoxy groups having 1 to 6 carbon atoms in the alkyl group having 1 to 6 carbon atoms is preferably 3 or less, more preferably 1 or 2, and more preferably 1 or 2. It is even more preferred. As the alkyl group having 1 to 6 carbon atoms which may have an alkoxy group having 1 to 6 carbon atoms, the alkyl group having 1 to 3 carbon atoms may have an alkoxy group having 1 to 3 carbon atoms. An alkyl group of 3 or less is preferred, an ethoxyethyl group is more preferred, and a 2-ethoxyethyl group is even more preferred.

The aryl group having 6 to 14 carbon atoms represented by R ⁶ and R ⁷ in the general formula (4) is preferably an aryl group having 6 to 10 carbon atoms, and more preferably a phenyl group. The aryl group having 6 to 14 carbon atoms may have at least one alkyl group having 1 to 6 carbon atoms. As the alkyl group having 1 to 6 carbon atoms in the aryl group having 6 to 14 carbon atoms, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable. The number of alkyl groups having 1 to 6 carbon atoms in the aryl group having 6 to 14 carbon atoms is preferably 3 or less, more preferably 1 or 2, and more preferably 2 or less. It is even more preferred. The aryl group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms includes phenyl having one or two alkyl groups having 1 to 6 carbon atoms. Groups are preferred, an ethylmethylphenyl group is more preferred, and a 2-ethyl-6-methylphenyl group is even more preferred.

In the general formula (4), R ⁶ and R ⁷ are each independently an aryl group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms; or It preferably represents an alkyl group having 1 to 6 carbon atoms which may have an alkoxy group having 1 to 6 carbon atoms.

In the general formula (5-1), the aryl group having 6 to 14 carbon atoms represented by Q ⁶ and Q ⁷ is preferably an aryl group having 6 to 10 carbon atoms, and more preferably a phenyl group. The aryl group having 6 to 14 carbon atoms may have one or more halogen atoms. As such a halogen atom, a fluorine atom or a chlorine atom is preferable, and a chlorine atom is more preferable. The number of halogen atoms in the aryl group having 6 to 14 carbon atoms is preferably one or more and three or less. As the aryl group having 6 or more and 14 or less carbon atoms having one or more halogen atoms, a phenyl group having one or more and 3 or less halogen atoms is preferable, a dichlorophenyl group or a trichlorophenyl group is more preferable, and 2,6 -Dichlorophenyl or 2,4,6-trichlorophenyl is more preferred.

In the general formula (5-1), the aryl group having 6 to 14 carbon atoms and having at least one alkyl group having 1 to 6 carbon atoms represented by Q ⁶ and Q ⁷ includes 1 to 6 carbon atoms. A phenyl group having one or more and five or less alkyl groups is preferable, a phenyl group having one or two alkyl groups having one or more and three or less carbon atoms is more preferable, and an ethylmethylphenyl group is more preferable. An ethyl-6-methylphenyl group is particularly preferred. The aryl group having 6 to 14 carbon atoms having at least one alkyl group having 1 to 6 carbon atoms may have one or more (preferably 1 to 3) halogen atoms. As such a halogen atom, a fluorine atom or a chlorine atom is preferable, and a chlorine atom is more preferable. When an aryl group having 6 to 14 carbon atoms having at least one alkyl group having 1 to 6 carbon atoms has a halogen atom, the alkyl group having 1 to 6 carbon atoms has a halogen atom. The aryl group having 6 to 14 carbon atoms may have a halogen atom.

In Formula (5-1), the aryl group having at least one benzoyl group represented by Q ⁶ and Q ⁷ and having 6 to 14 carbon atoms is preferably a phenyl group having at least one benzoyl group, and a benzoyl group Is more preferable, a phenyl group having one benzoyl group is more preferable, and a 2-benzoylphenyl group is particularly preferable. The aryl group having 6 to 14 carbon atoms having at least one benzoyl group may have one or more (preferably 1 to 3) halogen atoms. As such a halogen atom, a fluorine atom or a chlorine atom is preferable, and a chlorine atom is more preferable. When the aryl group having 6 to 14 carbon atoms having a benzoyl group has a halogen atom, the benzoyl group may have a halogen atom, and the aryl group having 6 to 14 carbon atoms has a halogen atom. May be. As the aryl group having one or more halogen atoms and a benzoyl group and having 6 to 14 carbon atoms, a phenyl group having one or more and three or less halogen atoms and having a benzoyl group is preferable. A phenyl group having at least one and three or less chlorine atoms and having a benzoyl group is more preferable, a chloro (benzoyl) phenyl group is more preferable, and a 4-chloro-2-benzoylphenyl group is particularly preferable. .

In the general formula (5-1), the aralkyl group having 7 to 20 carbon atoms represented by Q ⁶ and Q ⁷ is preferably an aralkyl group having 7 to 9 carbon atoms, more preferably a phenylethyl group. -Phenylethyl groups are more preferred. The aralkyl group having 7 to 20 carbon atoms may have one or more (preferably one or more and three or less) halogen atoms. As such a halogen atom, a fluorine atom or a chlorine atom is preferable, and a chlorine atom is more preferable. When the aralkyl group having 7 to 20 carbon atoms has a halogen atom, the alkyl moiety of the aralkyl group having 7 to 20 carbon atoms may have a halogen atom, and the aryl moiety has a halogen atom. You may. The aralkyl group having 7 or more and 20 or less carbon atoms having one or more halogen atoms is preferably an aralkyl group having 7 or more and 9 or less carbon atoms having 1 or more and 3 or less halogen atoms. A 1-phenylethyl group having the following chlorine atoms is more preferred, and a 1- (2,4-dichlorophenyl) ethyl group is still more preferred.

In formula (5-1), the alkyl group having 1 to 8 carbon atoms represented by Q ⁶ and Q ⁷ is preferably an alkyl group having 1 to 6 carbon atoms. The alkyl group having 1 to 8 carbon atoms may have one or more (preferably one or more and three or less) halogen atoms. As such a halogen atom, a fluorine atom or a chlorine atom is preferable.

In formula (5-1), the cycloalkyl group having 3 to 10 carbon atoms represented by Q ⁶ and Q ⁷ is preferably a cycloalkyl group having 5 to 7 carbon atoms. The cycloalkyl group having 3 to 10 carbon atoms may have one or more (preferably one or more and three or less) halogen atoms. As such a halogen atom, a fluorine atom or a chlorine atom is preferable.

Q ⁶ and Q ⁷ in the general formula (5-1) are preferably as follows. Q ⁶ and Q ⁷ are each independently an aryl group having 6 to 14 carbon atoms which may have one or more halogen atoms; a carbon atom which may have one or more halogen atoms. An aryl group having 6 or more and 14 or less carbon atoms having at least one alkyl group having 1 or more and 6 or less; 6 or more 14 or more carbon atoms having at least one benzoyl group which may have one or more halogen atoms. The following aryl group; and a group selected from the group consisting of an aralkyl group having 7 to 20 carbon atoms which may have one or more halogen atoms. At least one of Q ⁶ and Q ⁷ has one or more halogen atoms.

Q ⁶ and Q ⁷ in the general formula (5-1) are as follows in more preferred examples. One of Q ⁶ and Q ⁷ is an aryl group having 6 or more and 14 or less carbon atoms having at least one halogen atom; having at least one halogen atom and having 6 or more carbon atoms having at least one benzoyl group. An aryl group having 14 or less; or an aralkyl group having 7 or more and 20 or less carbon atoms having one or more halogen atoms. The other of Q ⁶ and Q ⁷ represents an aryl group having 6 to 14 carbon atoms having at least one alkyl group having 1 to 6 carbon atoms.

Q ⁶ and Q ⁷ in the general formula (5-1) are as follows in another more preferable example. Q ⁶ and Q ⁷ both have one or more halogen atoms and have at least one benzoyl group, and are an aryl group having 6 to 14 carbon atoms; or a carbon atom having one or more halogen atoms having 7 carbon atoms. Represents an aralkyl group of 20 or more and 20 or less. In addition, compound (5-1) can be produced by the method described in Examples or an alternative method thereof.

  The charge generation layer can contain, for example, two of the compounds (1-1), (2), (3), (4) and (5-1) as the first electron transporting agent. When two kinds are selected from the compounds (1-1), (2), (3), (4) and (5-1), the same general formula (specifically, the general formulas (1-1), ( 2), (3), (4) and (5-1)) may be selected from two different types of compounds. When two kinds are selected from the compounds (1-1), (2), (3), (4) and (5-1), two kinds of compounds represented by different general formulas may be selected. .

  The charge generation layer can also contain, for example, three of the compounds (1-1), (2), (3), (4) and (5-1) as the first electron transporting agent. When three kinds are selected from compounds (1-1), (2), (3), (4) and (5-1), the same general formula (specifically, general formulas (1-1), ( 2), (3), (4) and (5-1)) may be selected from three different types of compounds. When three kinds are selected from the compounds (1-1), (2), (3), (4) and (5-1), three kinds of compounds represented by different general formulas may be selected. .

  Preferred examples of the compound (1-1) are compounds represented by the following chemical formulas (ET1-1) to (ET1-12), and more preferred examples are the chemical formulas (ET1-3) and (ET1-12) ). Preferred examples of the compound (2) are compounds represented by the following chemical formulas (ET2-1) to (ET2-10), and more preferred examples are compounds represented by the chemical formula (ET2-4). . Preferred examples of the compound (3) are compounds represented by the following chemical formulas (ET3-1) to (ET3-3), and more preferred examples are compounds represented by the chemical formula (ET3-1). . Preferred examples of the compound (4) are compounds represented by the following chemical formulas (ET4-1) to (ET4-4). Preferred examples of the compound (5-1) are compounds represented by the following chemical formulas (ET5-1) to (ET5-6), and more preferred examples are the chemical formulas (ET5-1) and (ET5-2). ) Or (ET5-3). Hereinafter, the chemical formulas (ET1-1) to (ET1-12), (ET2-1) to (ET2-10), (ET3-1) to (ET3-3), (ET4-1) to (ET4-4) And each of the compounds represented by (ET5-1) to (ET5-6) were converted to compounds (ET1-1) to (ET1-12), (ET2-1) to (ET2-10), and (ET3-1). ) To (ET3-3), (ET4-1) to (ET4-4) and (ET5-1) to (ET5-6).

  In order to suitably suppress the crystallization of the charge generation layer and the generation of the transfer memory, the charge generation layer may be used as the first electron transporting agent in two of the compounds (1-1), (2) and (3). It is preferable to contain at least two types, more preferably two or three of the compounds (1-1), (2) and (3).

  In order to suitably suppress the crystallization of the charge generation layer and the occurrence of transfer memory, the charge generation layer may be used as the first electron transporting agent in the compounds (ET1-1) to (ET1-12), (ET2-1) (ET2-10), (ET3-1) to (ET3-3), (ET4-1) to (ET4-4) and (ET5-1) to (ET5-6). It is more preferable to contain two or more of the compounds (ET1-3), (ET1-12), (ET2-4) and (ET3-1), and the compound (ET1-3) It is more preferable to contain two or three of (ET1-12), (ET2-4) and (ET3-1).

  In order to appropriately suppress the crystallization of the charge generation layer and the generation of the transfer memory, the charge generation layer preferably contains the compound (1-1) and the compound (2) as the first electron transporting agent. It is also preferable that the charge generation layer contains the compound (1-1) and the compound (3) as the first electron transporting agent. It is also preferable that the charge generation layer contains the compound (1-1), the compound (2) and the compound (3) as the first electron transporting agent.

  In order to suitably suppress the crystallization of the charge generation layer and the generation of the transfer memory, the charge generation layer should contain the compound (ET1-3) and the compound (ET3-1) as the first electron transporting agent. preferable. It is also preferable that the charge generation layer contains a compound (ET1-12) and a compound (ET2-4) as the first electron transporting agent. It is also preferable that the charge generation layer contains the compound (ET1-12), (ET2-4) and the compound (ET3-1) as the first electron transporting agent.

  The charge generation layer can contain only two of the compounds (1-1), (2), (3), (4) and (5-1) as the first electron transporting agent. Further, the charge generation layer can contain only three of the compounds (1-1), (2), (3), (4) and (5-1) as the first electron transporting agent. . Further, the charge generation layer may contain only four or more of compounds (1-1), (2), (3), (4) and (5-1) as the first electron transporting agent. it can. In addition, the charge generation layer may include, as a first electron transporting agent, a compound (1-1), (2), (3), (4), and (5-1) in addition to a compound ( Compounds other than 1-1), (2), (3), (4) and (5-1) may be further contained. In order to suitably suppress crystallization of the charge generation layer and generation of transfer memory, two or more of the compounds (1-1), (2), (3), (4) and (5-1) are required. Is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, based on the total mass of the first electron transporting agent.

(Primary hole transport agent)
The charge generation layer contains a first hole transport agent. Examples of the first hole transporting agent include triphenylamine derivatives, diamine derivatives (eg, N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ′, N′-tetraphenylphenylenediamine) Derivatives, N, N, N ', N'-tetraphenylnaphthylenediamine derivatives, N, N, N', N'-tetraphenylphenanthrylenediamine derivatives, or di (aminophenylethenyl) benzene derivatives), oxa Diazole compounds (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), styryl compounds (eg, 9- (4-diethylaminostyryl) anthracene), carbazole compounds Compound (for example, polyvinyl carbazole), organic polysilane compound, pyrazoline-based compound (for example, 1-phenyl-3- p- dimethylaminophenyl) pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds and triazole compounds. As the first hole transporting agent, one type may be used alone, or two or more types may be used in combination.

  Preferable examples of the first hole transporting agent include compounds represented by the following general formulas (10), (11) and (12) (hereinafter referred to as compounds (10), (11) and (12)) There is). In order to further suppress crystallization of the charge generation layer and generation of transfer memory, the charge generation layer preferably contains the compound (12) as a first hole transporting agent.

In the general formula (10), R ^{20 to} R ²² each independently represent 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 ^{20 to} R ²² preferably represent an alkyl group having 1 to 6 carbon atoms, more preferably an n-butyl group.

In the general formula (10), p, q and r each independently represent an integer of 0 or more and 5 or less. When p 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. When q represents an integer of 2 to 5, a plurality of R ²¹ bonded to the same phenyl group may be the same or different. When r represents an integer of 2 or more and 5 or less, a plurality of R ²² bonded to the same phenyl group may be the same or different. p preferably represents 1. Preferably, q and r represent 0.

The bonding position of R ²⁰ to R ²² is not particularly limited. R ²⁰ to R ²² are each ortho position of the phenyl group may be bonded (position) in any of the meta-position and para-position. R ²⁰ is preferably bonded to the para position of the phenyl group.

In the general formula (11), R ^{23 to} R ²⁷ each independently represent 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. Represents an aryl group having 6 to 14 carbon atoms which may have a group. Each of R ^{23 to} R ²⁵ preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and particularly preferably represents a methyl group. . R ^{26 to} R ²⁷ each preferably represent 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. More preferably, it represents a phenyl group which may have a group, more preferably, a methylphenyl group, and particularly preferably, a p-methylphenyl group.

In the general formula (11), s, t and u each independently represent an integer of 0 or more and 5 or less. When s represents an integer of 2 to 5, a plurality of R ²³ bonded to the same phenyl group may be the same or different. When t represents an integer of 2 to 5, a plurality of R ²⁴ bonded to the same phenyl group may be the same or different. When u represents an integer of 2 to 5, a plurality of R ²⁵ bonded to the same phenyl group may be the same or different from each other. Preferably, s, t and u each represent 1.

The bonding position of R ²³ to R ²⁵ is not particularly limited. R ²³ to R ²⁵ are each ortho position of the phenyl group may be bonded (position) in any of the meta-position and para-position. R ^{23 to} R ²⁵ are preferably each bonded to the para position of the phenyl group.

In the general formula (12), R ^{28 to} R ³³ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an aryl having 6 to 14 carbon atoms. Represents an alkenyl group having 2 to 6 carbon atoms which may have a group or a substituent. When the alkenyl group having 2 or more and 6 or less carbon atoms has a substituent, the substituent that the alkenyl group having 2 or more and 6 or less carbon atoms has may be an alkyl group having 1 or more and 6 or less carbon atoms or 6 or more carbon atoms. An aryl group of 14 or less is preferred, and a phenyl group is more preferred. The number of substituents of the alkenyl group having 2 to 6 carbon atoms is not particularly limited, but is preferably 3 or less, more preferably 2. As R ^{28 to} R ³³ , alkyl having 1 to 6 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.

In the general formula (12), g, h, i and j each independently represent an integer of 0 or more and 5 or less. When g represents an integer of 2 to 5, a plurality of R ²⁸ bonded to the same phenyl group may be the same or different. When h represents an integer of 2 or more and 5 or less, a plurality of R ²⁹ bonded to the same phenyl group may be the same or different from each other. When i represents an integer of 2 or more and 5 or less, a plurality of R ³⁰ bonded to the same phenyl group may be the same or different. When j represents an integer of 2 to 5, a plurality of R ³¹ bonded to the same phenyl group may be the same or different. It is preferred that one of g and h represents 2, and the other represents 0 or 1. More preferably, one of g and h represents 2, and the other represents 0. Preferably, one of i and j represents 2, and the other represents 0 or 1. More preferably, one of i and j represents 2, and the other represents 0.

The bonding position of R ²⁸ to R ³¹ is not particularly limited. R ^{28 to} R ³¹ may be bonded (positioned) to any of the ortho, meta and para positions of the phenyl group. R ^{28 to} R ³¹ are preferably each bonded to the ortho or para position of the phenyl group.

In the general formula (12), k and l each independently represent an integer of 0 or more and 4 or less. If k is an integer of 2 to 4, a plurality of R ³² which bind to the same phenylene group may be the same or different. When 1 represents an integer of 2 or more and 4 or less, a plurality of R ³³ bonded to the same phenylene group may be the same or different from each other. Preferably, k and l each represent 0.

The bonding position of R ³² and R ³³ are not particularly limited. R ³² and R ³³ may be bonded (positioned) at any of the ortho position and the meta position with respect to the nitrogen atom to which the phenylene group is bonded.

When g represents 2 and h represents 0 or 1, it is preferable that each of two R ²⁸ independently represents an alkyl group having 1 to 6 carbon atoms, and represents a methyl group and an ethyl group. More preferred. When g represents 2 and h represents 0 or 1, R ²⁹ preferably represents an alkenyl group having 2 or more and 6 or less carbon atoms which may have a substituent, and 2 or more having 6 or more carbon atoms. More preferably, it represents an alkenyl group having 2 to 6 carbon atoms having an aryl group of 14 or less, and particularly preferably a 2,2-diphenylethenyl group. If g represents h is 0 or 1 represents 2, the two R ²⁸ preferably be attached to the ortho position of the phenyl group. In this case, R ²⁹ is preferably bonded to the para position of the phenyl group.

When h represents 2 and g represents 0 or 1, it is preferable that each of two R ²⁹ independently represents an alkyl group having 1 to 6 carbon atoms, and represents a methyl group and an ethyl group. More preferred. When h represents 2 and g represents 0 or 1, R ²⁸ preferably represents an alkenyl group having 2 or more and 6 or less carbon atoms which may have a substituent, and 2 or more having 6 or more carbon atoms. More preferably, it represents an alkenyl group having 2 to 6 carbon atoms having an aryl group of 14 or less, and particularly preferably a 2,2-diphenylethenyl group. When h represents 2 and g represents 0 or 1, it is preferred that two R ²⁹ are bonded to the ortho position of the phenyl group. In this case, R ²⁸ is preferably bonded to the para position of the phenyl group.

When i represents 2 and j represents 0 or 1, it is preferable that each of two R ³⁰ independently represents an alkyl group having 1 to 6 carbon atoms, and represents a methyl group and an ethyl group. More preferred. When i represents 2 and j represents 0 or 1, R ³¹ preferably represents an alkenyl group having 2 or more and 6 or less carbon atoms which may have a substituent, and 2 or more and 6 or more carbon atoms. More preferably, it represents an alkenyl group having 2 to 6 carbon atoms having an aryl group of 14 or less, and particularly preferably a 2,2-diphenylethenyl group. If i is the j-represents 2 represents 0 or 1, two R ³⁰ may preferably be attached at the ortho position of the phenyl group. In this case, R ³¹ is preferably bonded to the para position of the phenyl group.

When j represents 2 and i represents 0 or 1, each of the two R ³¹ preferably independently represents an alkyl group having 1 to 6 carbon atoms, and preferably represents a methyl group and an ethyl group. More preferred. When i represents 2 and j represents 0 or 1, R ³⁰ preferably represents an alkenyl group having 2 to 6 carbon atoms which may have a substituent, and preferably 2 or more and 6 or more carbon atoms. More preferably, it represents an alkenyl group having 2 to 6 carbon atoms having an aryl group of 14 or less, and particularly preferably a 2,2-diphenylethenyl group. If j represents i is 0 or 1 represents 2, the two R ³¹ preferably be attached to the ortho position of the phenyl group. In this case, R ³⁰ is preferably bonded to the para position of the phenyl group.

  A preferred example of the compound (10) is a compound represented by the following chemical formula (HT2). A preferred example of the compound (11) is a compound represented by the following chemical formula (HT3). A preferred example of the compound (12) is a compound represented by the following chemical formula (HT1). Hereinafter, each of the compounds represented by the chemical formulas (HT1) to (HT3) may be described as compounds (HT1) to (HT3).

  In order to suitably suppress the crystallization of the charge generation layer and the occurrence of transfer memory, the charge generation layer contains the compound (1-1) and the compound (2) as the first electron transporting agent, and contains the first hole. It is preferable to contain the compound (12) as a transport agent. It is also preferable that the charge generation layer contains the compound (1-1) and the compound (3) as the first electron transporting agent and the compound (12) as the first hole transporting agent. Further, the charge generation layer may contain the compound (1-1), the compound (2) and the compound (3) as the first electron transporting agent, and may contain the compound (12) as the first hole transporting agent. preferable.

  In order to suitably suppress the crystallization of the charge generation layer and the occurrence of transfer memory, the charge generation layer contains the compound (1-1) and the compound (2) as the first electron transporting agent, and contains the first hole. It is preferable to contain the compound (HT1) as a transport agent. It is also preferable that the charge generation layer contains the compound (1-1) and the compound (3) as the first electron transporting agent and the compound (HT1) as the first hole transporting agent. Further, the charge generation layer may contain the compound (1-1), the compound (2) and the compound (3) as the first electron transporting agent, and may contain the compound (HT1) as the first hole transporting agent. preferable.

  In order to suitably suppress crystallization of the charge generation layer and generation of transfer memory, the charge generation layer contains a compound (ET1-3) and a compound (ET3-1) as a first electron transporting agent. It is preferable to contain the compound (HT1) as a hole transporting agent. It is also preferable that the charge generation layer contains the compound (ET1-12) and the compound (ET2-4) as the first electron transporting agent, and also contains the compound (HT1) as the first hole transporting agent. Further, the charge generation layer contains the compounds (ET1-12), (ET2-4) and the compound (ET3-1) as the first electron transporting agent, and contains the compound (HT1) as the first hole transporting agent. It is also preferable to do so.

(Charge generator)
The charge generation layer contains a charge generation agent. The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. As the charge generator, for example, phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azurenium pigments, cyanine Pigment, powder of an inorganic photoconductive material (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide or amorphous silicon), pyrylium pigment, ancesthrone-based pigment, triphenylmethane-based pigment, selenium-based pigment, toluidine-based pigment, Pyrazoline pigments and quinacridone pigments. One kind of the charge generating agent may be used alone, or two or more kinds may be used in combination.

  Examples of the phthalocyanine pigment include metal-free phthalocyanine and metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine represented by the chemical formula (CG1). The phthalocyanine-based pigment may be crystalline or non-crystalline. The crystal shape (for example, α type, β type, Y type, V type or II type) of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

  Examples of the crystal of metal-free phthalocyanine 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 may be referred to as α-type, β-type and Y-type titanyl 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 photoconductor having sensitivity in a wavelength region of 700 nm or more. Since having a high quantum yield in the wavelength region of 700 nm or more, as the charge generator, a phthalocyanine-based pigment is preferable, a metal-free phthalocyanine or a titanyl phthalocyanine is more preferable, and an X-type metal-free phthalocyanine or a Y-type titanyl phthalocyanine is further preferable. And Y-type titanyl phthalocyanine are particularly preferred. Further, Y-type titanyl phthalocyanine has an advantage that charge generation efficiency is high and charges hardly remain in the charge generation layer.

  Y-type titanyl phthalocyanine has, for example, a main peak at 27.2 ° in Bragg angle (2θ ± 0.2 °) in the CuKα characteristic X-ray diffraction spectrum. The main peak in the CuKα characteristic X-ray diffraction spectrum is a peak having the first or second largest 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 ° C. in the CuKα characteristic X-ray diffraction spectrum.

  An example of a method for measuring a 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), and an X-ray tube Cu, a tube voltage of 40 kV, a tube current of 30 mA and CuKα An X-ray diffraction spectrum is measured under the condition of a characteristic X-ray wavelength of 1.542 °. The measurement range (2θ) is, for example, not less than 3 ° and not more than 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. 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 in FIG. 2, it can be estimated that the measured crystal form of titanyl phthalocyanine is the Y form.

Y-type titanyl phthalocyanines are classified into three types according to differences in thermal characteristics (specifically, the following thermal characteristics (a) to (c)) in a differential scanning calorimetry (DSC) spectrum.
(A) In the thermal characteristics by DSC, there is a peak (for example, one peak) in a range of 50 ° C. or more and 270 ° C. or less in addition to the peak accompanying the vaporization of the 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 associated with the vaporization of the adsorbed water.
(C) In the thermal characteristics by DSC, there is no peak in the range of 50 ° C. or more and less than 270 ° C. other than the peak accompanying the vaporization of the adsorbed water, and the peak is in the range of 270 ° C. or more and 400 ° C. or less (eg, one peak) Having.

  An example of a method for measuring a 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 DSC8230D” manufactured by Rigaku Corporation). The measurement range is, for example, 40 ° C. or more and 400 ° C. or less, and the temperature rise rate is, for example, 20 ° C./min.

  FIG. 3 is an example of a differential scanning calorimetry spectrum chart of titanyl phthalocyanine. Specifically, it is a differential scanning calorimetric analysis spectrum chart of titanyl phthalocyanine shown in the CuKα characteristic X-ray diffraction spectrum chart of FIG. In FIG. 3, the horizontal axis indicates temperature (° C.), and the vertical axis indicates heat flux (mcal / sec). In the differential scanning calorimetry spectrum chart of FIG. 3, no peak is observed in the range of 50 ° C. or more and less than 270 ° C. in addition to the peak associated with the vaporization of the adsorbed water, and one peak is observed at 296 ° C. A peak is observed. Therefore, it can be estimated that the measured titanyl phthalocyanine crystal is a Y-type titanyl phthalocyanine having mainly the thermal characteristics (c).

  Y-type titanyl phthalocyanine having thermal properties (b) and (c) is excellent in crystal stability, hardly causes crystal transition in an organic solvent, and easily dispersed in the charge generation layer. Y-type titanyl phthalocyanine having thermal characteristics (c) is preferable in order to achieve both suppression of crystallization of the charge generation layer and suppression of generation of transfer memory.

  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 ensenzlon-based pigment is suitably used as a charge generating agent.

(First binder resin)
The charge generation layer contains a first binder resin. Examples of the first binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include a polycarbonate resin, a polyarylate resin, a styrene-butadiene copolymer, a styrene-acrylonitrile copolymer, a styrene-maleic acid copolymer, an acrylic acid polymer, a styrene polymer (polystyrene), and 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 Resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyester resins, and polyether resins. Examples of the thermosetting resin include a silicone resin, an epoxy resin, a phenol resin, a urea resin, and a melamine resin. Examples of the photocurable resin include an acrylic acid adduct of an epoxy compound and an acrylic acid adduct of a urethane compound. One of these first binder resins may be used alone, or two or more thereof may be used in combination.

  Among these resins, a polycarbonate resin is preferable as the first binder resin because a charge generation layer having an excellent balance of processability, mechanical properties, optical properties, and abrasion resistance can be obtained. Examples of the polycarbonate resin include a bisphenol Z-type polycarbonate resin, a bisphenol ZC-type polycarbonate resin, a bisphenol C-type polycarbonate resin, and a bisphenol A-type polycarbonate resin. As the polycarbonate resin, a bisphenol Z-type polycarbonate resin having a repeating unit represented by the following chemical formula (R-1) (hereinafter sometimes referred to as polycarbonate resin (R-1)) is preferable.

  The viscosity average molecular weight of the first binder resin is preferably 25,000 or more, more preferably 25,000 or more and 52,500 or less. When the viscosity average molecular weight of the first binder resin is 25,000 or more, the abrasion resistance of the photoconductor is easily improved. When the viscosity average molecular weight of the first binder resin is 52,500 or less, the first binder resin is easily dissolved in the solvent of the charge generation layer coating solution, and the viscosity of the charge generation layer coating solution does not become too high. As a result, the charge generation layer is easily formed.

<1-3. Charge transport layer>
The charge transporting layer contains a second hole transporting agent and a second electron transporting agent. The charge transport layer may contain a second binder resin. The second hole transport agent is a hole transport agent contained in the charge transport layer. The second electron transport agent is an electron transport agent contained in the charge transport layer. The second binder resin is a binder resin contained in the charge transport layer. The charge transport layer may contain an additive as needed.

  When the charge transporting layer contains the second hole transporting agent and the second electron transporting agent, as described above, the occurrence of transfer memory can be suppressed. Further, it is considered that when the charge transporting layer contains the second electron transporting agent, the space charge remaining in the charge transporting layer is neutralized by the second electron transporting agent. Further, it is considered that when the charge transporting layer contains the second electron transporting agent, the second electron transporting agent absorbs visible light and the light resistance of the photoconductor is improved. Further, it is considered that when the charge transport layer contains the second electron transporting agent, the sensitivity of the photoconductor to light exposed to the photoconductor is improved.

(Second electron transport agent)
Examples of the second electron transport agent include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds. Compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride and dibromomaleic anhydride. Examples of the quinone compound include a diphenoquinone compound, an azoquinone compound, an anthraquinone compound, a naphthoquinone compound, a nitroanthraquinone compound, and a dinitroanthraquinone compound. As the second electron transporting agent, one type may be used alone, or two or more types may be used in combination.

  In order to suppress the occurrence of transfer memory, the second electron transporting agent preferably contains a compound represented by the following general formula (5-2) or (1-2). Hereinafter, the compounds represented by formulas (5-2) and (1-2) may be referred to as compounds (5-2) and (1-2), respectively. The charge transporting layer preferably contains the compound (5-2) or (1-2) as the second electron transporting agent. When the charge transport layer contains a second electron transport agent in addition to the second hole transport agent, crystallization of the charge transport layer is likely to occur. However, when the compound (5-2) or (1-2) is contained as the second electron transporting agent, generation of a transfer memory can be suppressed while suppressing crystallization of the charge transporting layer.

In the general formula (5-2), Q ¹⁰⁶ and Q ¹⁰⁷ each independently represent an aryl group having 6 to 14 carbon atoms which may have one or more halogen atoms; one or more halogen atoms An aryl group having 6 or more and 14 or less carbon atoms having at least one alkyl group having 1 or more and 6 or less carbon atoms; having at least one benzoyl group which may have one or more halogen atoms. One aryl group having 6 to 14 carbon atoms; an aralkyl group having 7 to 20 carbon atoms which may have one or more halogen atoms; a carbon atom having one or more halogen atoms which may have one or more halogen 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 which may have one or more halogen atoms. At least one of Q ¹⁰⁶ and Q ¹⁰⁷ has one or more halogen atoms.

Q ¹⁰⁶ and Q ¹⁰⁷ in the general formula (5-2) have the same meanings as Q ⁶ and Q ⁷ in the general formula (5-1), respectively. Preferred examples of Q ¹⁰⁶ and Q ^{107 in} the general formula (5-2) are the same as the preferred examples of Q ⁶ and Q ^{7 in} the general formula (5-1), respectively. Preferred examples of the compound (5-2) are the same as the preferred examples of the compound (5-1). In addition, compound (5-2) can be produced by the method described in Examples or an alternative method thereof.

In the general formula (1-2), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ and R ¹⁰⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, or a carbon atom which may have a substituent. An alkyl group having 1 to 6 or less, an alkenyl group having 2 to 6 carbon atoms which may have a substituent, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, Represents an aryl group having 6 to 14 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms which may have a substituent.

R ¹⁰¹ , R ¹⁰² , R ¹⁰³ and R ¹⁰⁴ in the general formula (1-2) have the same meanings as R ¹ , R ² , R ³ and R ^{4 in} the general formula (1-1), respectively. Preferable examples of R ¹⁰¹ , R ¹⁰² , R ¹⁰³ and R ^{104 in} the general formula (1-2) are respectively preferable examples of R ¹ , R ² , R ³ and R ^{4 in} the general formula (1-1). It is the same as a simple example. Preferred examples of the compound (1-2) are the same as the preferred examples of the compound (1-1).

  The charge transport layer may contain one kind of the compounds (5-2) and (1-2) alone or may contain two or more kinds as the second electron transporting agent. The charge transporting layer may contain only the compound (5-2) or (1-2) as the second electron transporting agent. The content of the compound (5-2) or (1-2) is preferably at least 80% by mass, more preferably at least 90% by mass, and preferably 100% by mass, based on the mass of the second electron transporting agent. It is particularly preferred that the content is mass%. The content of the second electron transporting agent is preferably from 10 parts by mass to 200 parts by mass, more preferably from 20 parts by mass to 100 parts by mass, based on 100 parts by mass of the second binder resin.

(Second hole transport agent)
Preferred examples of the second hole transport agent are the same as the preferred examples of the first hole transport agent. As the second hole transporting agent, one type may be used alone, or two or more types may be used in combination. The second hole transporting agent may be the same as or different from the first hole transporting agent. The content of the second hole transporting agent is preferably from 10 parts by mass to 200 parts by mass, more preferably from 20 parts by mass to 100 parts by mass, based on 100 parts by mass of the second binder resin. .

(Second binder resin)
Examples of the second binder resin are the same as those of the first binder resin and the preferred examples. As the second binder resin, one kind may be used alone, or two or more kinds may be used in combination. The second binder resin may be the same as or different from the first binder resin. The second binder resin contained in the charge transport layer is preferably different from the first binder resin contained in the charge generation layer. In the production of a photoreceptor, for example, a charge transport layer is formed on a conductive substrate, and a charge generation layer is formed on the charge transport layer. At this time, a charge generation layer coating solution is applied on the charge transport layer. Therefore, the charge transport layer is preferably not dissolved in the solvent of the coating solution for the charge generation layer. When the first binder resin is a polycarbonate resin, polystyrene is preferable as the second binder resin.

  In order to suitably suppress the occurrence of transfer memory, the charge transport layer may contain the compound (12) as a second hole transport agent and the compound (5-2) as a second electron transport agent. preferable. For the same reason, the charge transport layer contains the compound (12) as the second hole transport agent and the compound (ET5-1), (ET5-2) or (ET5-3) as the second electron transport agent. Is preferred. For the same reason, it is preferable that the charge transport layer contains the compound (HT1) as the second hole transport agent and the compound (5-2) as the second electron transport agent. For the same reason, the charge transport layer contains the compound (HT1) as the second hole transport agent, and contains the compound (ET5-1), (ET5-2) or (ET5-3) as the second electron transport agent. Is preferred.

  In order to suitably suppress the occurrence of transfer memory, the charge transport layer may contain the compound (12) as a second hole transporting agent and the compound (1-2) as a second electron transporting agent. preferable. For the same reason, it is preferable that the charge transporting layer contains the compound (12) as the second hole transporting agent and the compound (ET1-3) or (ET1-12) as the second electron transporting agent. For the same reason, it is preferable that the charge transport layer contains the compound (HT1) as the second hole transport agent and the compound (1-2) as the second electron transport agent. For the same reason, it is preferable that the charge transport layer contains the compound (HT1) as the second hole transport agent and the compound (ET1-3) or (ET1-12) as the second electron transport agent.

In order to suitably suppress crystallization of the charge generation layer, crystallization of the charge transport layer, and generation of transfer memory, the first electron transporting agent and the first hole transporting agent contained in the charge generating layer, and the charge transporting It is preferable that the second electron transporting agent and the second hole transporting agent contained in the layer have the following combinations.
The first electron transporting agent is a compound (1-1) and a compound (3), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (1-2). The second hole transporting agent is the compound (12);
The first electron transporting agent is a compound (1-1) and a compound (2), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (1-2). The second hole transporting agent is the compound (12); or the first electron transporting agent is the compound (1-1) and the compound (3), and the first hole transporting agent is the compound (12). 12), the second electron transporting agent is compound (5), and the second hole transporting agent is compound (12).

  In order to suitably suppress crystallization of the charge generation layer, crystallization of the charge transport layer, and generation of transfer memory, the first electron transporting agent and the first hole transporting agent contained in the charge generating layer, and the charge transporting It is more preferable that the second electron transporting agent and the second hole transporting agent contained in the layer have the following combinations. The first electron transporting agent is a compound (1-1) and a compound (3), the first hole transporting agent is a compound (12), the second electron transporting agent is a compound (5), The second hole transporting agent is the compound (12).

In order to suitably suppress crystallization of the charge generation layer, crystallization of the charge transport layer, and generation of transfer memory, the first electron transporting agent and the first hole transporting agent contained in the charge generating layer, and the charge transporting It is preferable that the second electron transporting agent and the second hole transporting agent contained in the layer have the following combinations.
The first electron transport agent is a compound (1-1) and a compound (3), the first hole transport agent is a compound (HT1), and the second electron transport agent is a compound (1-2). The second hole transport agent is a compound (HT1);
The first electron transport agent is a compound (1-1) and a compound (2), the first hole transport agent is a compound (HT1), and the second electron transport agent is a compound (1-2). The second hole transporting agent is a compound (HT1); or the first electron transporting agent is a compound (1-1) and a compound (3), and the first hole transporting agent is a compound (HT1). HT1), the second electron transporting agent is the compound (5), and the second hole transporting agent is the compound (HT1).

  In order to suitably suppress crystallization of the charge generation layer, crystallization of the charge transport layer, and generation of transfer memory, the first electron transporting agent and the first hole transporting agent contained in the charge generating layer, and the charge transporting It is more preferable that the second electron transporting agent and the second hole transporting agent contained in the layer have the following combinations. The first electron transporting agent is a compound (1-1) and a compound (3), the first hole transporting agent is a compound (HT1), the second electron transporting agent is a compound (5), The second hole transporting agent is the compound (HT1).

In order to suitably suppress crystallization of the charge generation layer, crystallization of the charge transport layer, and generation of transfer memory, the first electron transporting agent and the first hole transporting agent contained in the charge generating layer, and the charge transporting It is preferable that the second electron transporting agent and the second hole transporting agent contained in the layer have the following combinations.
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET1-3). ) Wherein the second hole transport agent is compound (12);
The first electron transporting agent is a compound (ET1-12) or a compound (ET2-4), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET1-12). ) Wherein the second hole transport agent is compound (12);
The first electron transporting agent is a compound (ET1-12) and a compound (ET2-4), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET1-3). ) Wherein the second hole transport agent is compound (12);
The first electron transporting agent is a compound (ET1-12) or a compound (ET2-4), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET1-12). ) Wherein the second hole transport agent is compound (12);
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET5-1). ) Wherein the second hole transport agent is compound (12);
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET5-2). ) Wherein the second hole transport agent is compound (12);
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET5-3). ) Wherein the second hole transport agent is compound (12);
The first electron transporting agent is a compound (ET1-12), a compound (ET2-4) or a compound (ET3-1), the first hole transporting agent is a compound (12), and the second electron transporting is The agent is compound (ET1-12) and the second hole transporting agent is compound (12); or the first electron transporting agent is compound (ET1-3) and compound (ET3-1). The first hole transport agent is the compound (12), the second electron transport agent is the compound (ET1-12), and the second hole transport agent is the compound (12).

In order to suitably suppress crystallization of the charge generation layer, crystallization of the charge transport layer, and generation of transfer memory, the first electron transporting agent and the first hole transporting agent contained in the charge generating layer, and the charge transporting It is more preferable that the second electron transporting agent and the second hole transporting agent contained in the layer have the following combinations.
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET5-1). ) Wherein the second hole transport agent is compound (12);
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (12), and the second electron transporting agent is a compound (ET5-2). And the second hole transporting agent is compound (12); or the first electron transporting agent is compound (ET1-3) and compound (ET3-1), and the first hole transporting agent is The agent is compound (12), the second electron transport agent is compound (ET5-3), and the second hole transport agent is compound (12).

In order to suitably suppress crystallization of the charge generation layer, crystallization of the charge transport layer, and generation of transfer memory, the first electron transporting agent and the first hole transporting agent contained in the charge generating layer, and the charge transporting It is preferable that the second electron transporting agent and the second hole transporting agent contained in the layer have the following combinations.
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET1-3). ), Wherein the second hole transporting agent is a compound (HT1);
The first electron transporting agent is a compound (ET1-12) and a compound (ET2-4), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET1-12). ), Wherein the second hole transporting agent is a compound (HT1);
The first electron transporting agent is a compound (ET1-12) and a compound (ET2-4), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET1-3). ), Wherein the second hole transporting agent is a compound (HT1);
The first electron transporting agent is a compound (ET1-12) and a compound (ET2-4), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET1-12). ), Wherein the second hole transporting agent is a compound (HT1);
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET5-1). ), Wherein the second hole transporting agent is a compound (HT1);
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET5-2). ), Wherein the second hole transporting agent is a compound (HT1);
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET5-3). ), Wherein the second hole transporting agent is a compound (HT1);
The first electron transporting agent is a compound (ET1-12), a compound (ET2-4) and a compound (ET3-1), the first hole transporting agent is a compound (HT1), and the second electron transporting is The agent is the compound (ET1-12) and the second hole transporting agent is the compound (HT1); or the first electron transporting agent is the compound (ET1-3) and the compound (ET3-1). The first hole transport agent is a compound (HT1), the second electron transport agent is a compound (ET1-12), and the second hole transport agent is a compound (HT1).

In order to suitably suppress crystallization of the charge generation layer, crystallization of the charge transport layer, and generation of transfer memory, the first electron transporting agent and the first hole transporting agent contained in the charge generating layer, and the charge transporting It is more preferable that the second electron transporting agent and the second hole transporting agent contained in the layer have the following combinations.
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET5-1). ), Wherein the second hole transporting agent is a compound (HT1);
The first electron transporting agent is a compound (ET1-3) and a compound (ET3-1), the first hole transporting agent is a compound (HT1), and the second electron transporting agent is a compound (ET5-2). ) And the second hole transport agent is a compound (HT1); or the first electron transport agent is a compound (ET1-3) and a compound (ET3-1), The agent is the compound (HT1), the second electron transporting agent is the compound (ET5-3), and the second hole transporting agent is the compound (HT1).

In the charge transport layer, to the mass of the second hole transporting agent (M _HTM2), the ratio of the total mass of the second electron transfer agent _{(M ETM2) (M ETM2 /} M HTM2) is 0.90 to 1.10 Is preferably 0.95 or more and 1.05 or less, more preferably 1.00. It in the charge transporting layer, the ratio of the second electron transfer agent the total mass of to the mass of the second binder resin _{(M RESIN2) (M ETM2)} (M ETM2 / M RESIN2) is 0.30 to 0.50 Is preferably 0.35 or more and 0.45 or less, and more preferably 0.40. The ratio (M _ETM2 / M _CTL ) of the total mass (M _ETM2 ) of the second electron transport agent to the mass (M _CTL ) of the charge transport layer is preferably 0.20 or more and 0.25 or less, and 0.21 or less. It is more preferably at least 0.23 and more preferably at most 0.22. The ratio (M _RESIN2 / M _CTL ) of the mass (M _RESIN2 ) of the second binder resin to the mass (M _CTL ) of the charge transport layer is preferably from 0.50 to 0.60, and more preferably from 0.55 to 0. .57 or less, and even more preferably 0.56. Note that the mass of the charge transport layer (M _CTL ) is the sum of the masses of all the materials included in the charge transport layer. For example, when the charge transport layer contains a second electron transport agent, a second hole transport agent, and a second binder resin, the mass of the charge transport layer (M _CTL ) is the mass of the second electron transport agent, It is the sum of the mass of the second hole transporting agent and the mass of the second binder resin.

<1-4. Intermediate layer>
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin used for the intermediate layer (a resin for the intermediate layer). It is considered that the presence of the intermediate layer smoothes the flow of current generated when the photosensitive member is exposed and suppresses a rise in resistance while maintaining an insulating state that can suppress the occurrence of leakage.

  Examples of the inorganic particles include particles of a metal (for example, aluminum, iron or copper), particles of a metal oxide (for example, titanium oxide, alumina, zirconium oxide, tin oxide or zinc oxide), and non-metal oxides (for example, silica). Particles. One type of these inorganic particles may be used alone, or two or more types may be used in combination.

  The resin for the intermediate layer is not particularly limited as long as it can be used as a resin for forming the intermediate layer. The intermediate layer may contain an additive.

<1-5. Photoconductor Production Method>
The photoreceptor is manufactured, for example, as follows. First, a coating solution for the charge transport layer and a coating solution for the charge generation layer are prepared. A charge transport layer is formed by applying the coating solution for the charge transport layer to the conductive substrate and drying. Subsequently, the charge generation layer coating liquid is applied to the charge transport layer and dried to form a charge generation layer. Thereby, a photoconductor is manufactured.

  The coating solution for the charge transport layer is prepared by dissolving or dispersing the second hole transport agent, the second binder resin, and optionally added components (eg, additives) in a solvent. The coating solution for the charge generation layer is prepared by dissolving a charge generation agent, a first electron transport agent, a first hole transport agent, a first binder resin and optionally added components (for example, additives) in a solvent or It is prepared by dispersing.

  The solvent contained in the coating liquid (the coating liquid for the charge transport layer or the coating liquid for the charge generation layer) is not particularly limited as long as each component contained in the coating liquid can be dissolved or dispersed. Examples of the solvent include alcohols (for example, methanol, ethanol, isopropanol or butanol), aliphatic hydrocarbons (for example, n-hexane, octane or cyclohexane), aromatic hydrocarbons (for example, benzene, toluene or xylene), Halogenated hydrocarbons (eg, dichloromethane, dichloroethane, carbon tetrachloride or chlorobenzene), ethers (eg, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, 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 And 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 a halogenated hydrocarbon) as the solvent.

  The coating liquid is prepared by mixing the components and dispersing the components in a solvent. For mixing or dispersion, for example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used.

  The coating solution (the coating solution for the charge transport layer or the coating solution for the charge generation layer) may contain, for example, a surfactant in order to improve the dispersibility of each component.

  The method for applying the coating liquid (the coating liquid for the charge transport layer or the coating liquid for the charge generation layer) is not particularly limited as long as the coating liquid can be uniformly applied to 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 coating liquid (the coating liquid for the charge transport layer or the coating liquid for the charge generation layer) is not particularly limited as long as the solvent in the coating liquid can be evaporated. For example, a method of performing heat treatment (hot-air drying) using a high-temperature dryer or a reduced-pressure dryer is exemplified. The heat treatment conditions are, for example, a temperature of 40 ° C. or more and 150 ° C. or less, and a time of 3 minutes or more and 120 minutes or less.

  The method for manufacturing the photoconductor may further include, if necessary, one or both of a step of forming an intermediate layer and a step of forming a protective layer. In the step of forming the intermediate layer and the step of forming the protective layer, a known method is appropriately selected.

<2. Image Forming Apparatus>
Hereinafter, an image forming apparatus including the photoconductor according to the present embodiment will be described. The image forming apparatus includes the photoconductor according to the exemplary embodiment, a charging unit, an exposing unit, a developing unit, and a transfer unit. The charging unit charges the surface of the photoconductor with a positive polarity. The exposure unit exposes the charged surface of the photoconductor to form an electrostatic latent image on the surface of the photoconductor. The developing unit supplies toner to the electrostatic latent image and develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the photoconductor to the transfer target.

  The photoreceptor according to this embodiment can achieve both suppression of crystallization of the photosensitive layer and suppression of occurrence of transfer memory. With the photoconductor according to the present embodiment, the image forming apparatus can suppress the occurrence of image ghost due to the transfer memory in the formed image.

  Hereinafter, a tandem-type and intermediate-transfer-type color image forming apparatus will be described as an example of an image forming apparatus including the photoconductor according to the present embodiment, with reference to FIG.

  The image forming apparatus 100 includes image forming units 40a, 40b, 40c, and 40d, an intermediate transfer belt 56, a secondary transfer unit 58, and a fixing unit 52. Hereinafter, each of the image forming units 40a, 40b, 40c, and 40d will be referred to as an image forming unit 40 unless it is necessary to distinguish them.

  The image forming unit 40 includes the photoconductor 30, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit. When the image forming apparatus 100 employs the intermediate transfer method, the transfer units correspond to the primary transfer unit 54 and the secondary transfer unit 58. The photoconductor 30 is provided at a central position of the image forming unit 40. The photoconductor 30 is provided so as to be rotatable in the arrow direction (clockwise). Around the photoconductor 30, a charging unit 42, an exposure unit 44, a development unit 46, and a primary transfer unit 54 are provided in the stated order from the upstream side in the rotation direction of the photoconductor 30.

  The image forming unit 40 may further include one or both of a cleaning unit (not shown) and a charge removing unit (not shown). When the image forming unit 40 includes a cleaning unit and a charge removing unit, the charging unit 42, the exposure unit 44, the developing unit 46, and the primary transfer unit 54 are arranged around the photoconductor 30 from the upstream side in the rotation direction of the photoconductor 30. , A cleaning unit and a static elimination unit are provided in the stated order.

  The charging unit 42 positively charges the surface 30a (specifically, the peripheral surface, see FIG. 5) of the photoconductor 30. The charging unit 42 is a non-contact type or a contact type. 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 charged surface 30 a of the photoconductor 30. As a result, an electrostatic latent image is formed on the surface 30a of the photoconductor 30. The electrostatic latent image is formed based on the image data input to the image forming apparatus 100.

  The developing unit 46 supplies toner to the electrostatic latent image formed on the surface 30a of the photoconductor 30. Thereby, the electrostatic latent image is developed as a toner image. The photoconductor 30 corresponds to an image carrier that carries a toner image. Details of the developing unit 46 will be described later.

  The transfer unit 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 intermediate transfer method, the transfer unit 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 charging polarity of the toner) to the photoconductor 30 via the intermediate transfer belt 56. The intermediate transfer belt 56 is an endless belt. The intermediate transfer belt 56 rotates in an arrow (counterclockwise) direction. When the primary transfer bias is applied, between the photoconductor 30 and the primary transfer section 54, the photoconductor 30 moves to the surface of the intermediate transfer belt 56 (the contact surface with the photoconductor 30) and to the surface 30a of the photoconductor 30. The formed toner image is transferred (primary transfer).

  Next, the recording medium P is transported between the secondary transfer unit 58 and the intermediate transfer belt 56. 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 transported recording medium P. As a result, the toner image primarily transferred to the surface of the intermediate transfer belt 56 is transferred between the secondary transfer unit 58 and the intermediate transfer belt 56 from the surface of the intermediate transfer belt 56 to the surface of the recording medium P (the intermediate transfer belt 56). (Secondary transfer). Thus, the unfixed toner image is transferred to the recording medium P.

  By each of the image forming units 40a to 40d, toner images of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) are sequentially stacked on the intermediate transfer belt 56. Then, the toner images of a plurality of colors superimposed on the intermediate transfer belt 56 are secondarily transferred to the recording medium P by the secondary transfer unit 58 at one time.

  The image forming apparatus 100 may include a cleaning unit (not shown). Examples of the cleaning unit are a cleaning blade or a cleaning roller. In order to reduce abrasion of the charge generation layer 33 of the photoconductor 30, the cleaning unit is preferably a cleaning roller. However, the image forming apparatus 100 may be designed without a cleaning unit (not shown). That is, the image forming apparatus 100 can adopt a cleanerless system without a cleaning unit. In order to reduce the wear of the charge generation layer 33 of the photoconductor 30, it is preferable that the image forming apparatus 100 does not include a cleaning blade. The surface 30 a (peripheral surface) of the photoconductor 30 may be cleaned (cleaned) by the developing unit 46. The developing unit 46 for cleaning the surface 30a of the photoconductor 30 will be described later.

  The image forming apparatus 100 can be designed without the charge removing unit. That is, the image forming apparatus 100 can adopt a static elimination-less method that does not include the static elimination unit. When the image forming apparatus 100 employs the intermediate transfer method and the chargeless method, the primary transfer unit 54 applies a toner image from the surface 30 a of the photoconductor 30 to the surface of the intermediate transfer belt 56 (contact surface with the photoconductor 30). Transcribed. The area on the surface 30a of the photoconductor 30 where the toner image has been transferred is charged again by the charging unit 42 without being neutralized. In the image forming apparatus 100 of the non-static elimination type having no static elimination unit, the influence of the transfer current is apt to remain, and a transfer memory is easily generated. However, according to the photoconductor 30 of the present embodiment, the transfer memory can be suppressed as described above. Therefore, since the image forming apparatus 100 includes the photoconductor 30 of the present embodiment, even when the image forming apparatus 100 does not include the charge removing unit, the generation of the transfer memory can be suppressed.

  The fixing unit 52 heats and / or presses the unfixed toner image secondarily transferred to the recording medium P by the secondary transfer unit 58. The fixing unit 52 is, for example, a heating roller and / or a pressure roller. By heating and / or pressurizing the toner image, the toner image is fixed on the recording medium P. As a result, an image is formed on the recording medium P.

(Developing unit)
The developing unit 46 can adopt a non-magnetic one-component developing system. Thereby, abrasion of the charge generation layer 33 of the photoconductor 30 can be reduced. Hereinafter, the developing section 46 adopting the non-magnetic one-component developing method will be described with reference to FIG. FIG. 5 is an enlarged view of the V region shown in FIG.

  The developing unit 46 includes a housing frame 210, a supply roller 220, a developing roller 230, and a regulating blade 400. The length of the supply roller 220 and the developing roller 230 in the axial direction (the direction perpendicular to the plane of FIG. 5) is substantially the same as the length of the photoconductor 30.

  The storage frame 210 stores a non-magnetic one-component developer therein. The non-magnetic one-component developer corresponds to a toner. The toner does not contain magnetic powder. The housing frame 210 also houses therein a supply roller 220, a developing roller 230, and a regulating blade 400. The housing frame 210 has an opening 211 that is arranged to face the photoconductor 30. The opening 211 exposes a part of the developing roller 230 to the outside of the housing frame 210.

  The supply roller 220 is disposed inside the storage frame 210. The supply roller 220 is arranged to face the developing roller 230. The supply roller 220 includes a supply roller shaft member 221 and a roller unit 222. The supply roller shaft member 221 is arranged to extend in the direction of the rotation axis 223 of the supply roller 220. The supply roller shaft member 221 is rotatably supported by a shaft support (not shown) of the housing frame 210. The supply roller 220 is rotatable in the arrow direction (counterclockwise). The roller portion 222 is a cylindrical member attached to the outside of the supply roller shaft member 221.

  The supply roller 220 holds the toner, which is a non-magnetic one-component developer, stored in the storage frame 210 on the surface 220 a (peripheral surface) of the supply roller 220. Specifically, the roller portion 222 rotates integrally with the supply roller shaft member 221 as the supply roller shaft member 221 rotates. The roller unit 222 holds the toner stored in the storage frame 210 on the outer peripheral surface of the roller unit 222. The outer peripheral surface of the roller portion 222 corresponds to the surface 220a of the supply roller 220. The supply roller 220 supplies the toner held on the surface 220 a to the developing roller 230.

  The developing roller 230 is arranged to face the photoconductor 30. The developing roller 230 is disposed to face the photoconductor 30 via the opening 211 of the housing frame 210. Further, the developing roller 230 is arranged to face the supply roller 220. The supply roller 220 is arranged to face the photoconductor 30 via the developing roller 230.

  The developing roller 230 includes a developing roller shaft member 231 and a roller unit 232. The developing roller shaft member 231 is arranged to extend in the direction of the rotation axis 233 of the developing roller 230. The developing roller shaft member 231 is rotatably supported by a shaft support (not shown) of the housing frame 210. The developing roller 230 is rotatable in the arrow direction (counterclockwise). The developing roller shaft member 231 has one or more magnet units (not shown). Since the developing roller shaft member 231 has one or more magnets, a predetermined interval is provided between the regulating blade 400 and the surface 230a of the developing roller 230. The roller portion 232 is a cylindrical member attached to the outside of the developing roller shaft member 231. The roller portion 232 rotates integrally with the developing roller shaft member 231 as the developing roller shaft member 231 rotates.

  The developing roller 230 receives supply of toner from the supply roller 220. The toner supplied from the supply roller 220 is held as a toner layer TL on the surface 230a (peripheral surface) of the developing roller 230. The toner layer TL includes the toner supplied from the supply roller 220. The surface 230 a of the developing roller 230 corresponds to the surface of the roller unit 232. For example, the toner is held on the surface 230 a of the developing roller 230 by the mirror image force of the developing roller 230.

  The thickness of the toner layer TL held on the surface 230 a of the developing roller 230 is regulated by the regulating blade 400. To regulate the thickness of the toner layer TL means to uniformly adjust the thickness of the toner layer TL to a predetermined value.

  The regulating blade 400 has a plate shape. The regulating blade 400 has one end 401 fixed to the housing frame 210 and the other end 402 a free end. The other end 402 (free end) is formed by bending the vicinity of the outer edge of the plate-shaped member constituting the regulating blade 400 toward the side opposite to the developing roller 230 side.

  The regulating blade 400 is arranged so as to abut (specifically, surface-contact) with the toner layer TL held on the surface 230 a of the developing roller 230. A regulating nip N1 is formed between the regulating blade 400 and the developing roller 230.

  As described above, the developing roller shaft member 231 has one or more magnet units. Further, the regulating blade 400 has magnetism. Further, the regulating blade 400 can be flexibly deformed so that the other end 402 side approaches the developing roller 230 side. Thus, the other end 402 (free end) of the regulating blade 400 is urged toward the developing roller 230 by the urging force generated by the magnetic force from the magnet portion. Then, the regulating blade 400 contacts the toner layer TL held on the surface 230a of the developing roller 230 with a predetermined pressure. Thus, the thickness of the toner layer TL held on the surface 230a of the developing roller 230 can be regulated (uniformly adjusted to a predetermined value).

  The regulating blade 400 can also be flexibly deformed so that the other end 402 moves to a side away from the developing roller 230. Accordingly, the regulating blade 400 can smoothly guide the toner supplied from the supply roller 220 to the developing roller 230 to the regulating nip N1.

  The toner contained in the toner layer TL is charged by being rubbed by the contact with the regulating blade 400. The regulating blade 400 regulates the thickness of the toner layer TL and charges the toner contained in the toner layer TL.

  The photoconductor 30 has, for example, a cylindrical shape. The photoconductor 30 is rotatable around the rotation axis 301 of the photoconductor 30 in an arrow direction (clockwise). The rotation axis 301 of the photoconductor 30 is orthogonal to the paper surface of FIG.

  After the thickness of the toner layer TL is regulated by the regulating blade 400, the developing roller 230 forms the toner contained in the toner layer TL held on the surface 230a on the surface 30a (peripheral surface) of the photoconductor 30. Supplied to the electrostatic latent image. Thereby, the electrostatic latent image is developed as a toner image. To efficiently move the toner from the surface 230a of the developing roller 230 to the surface 30a of the photoconductor 30, it is preferable to apply a developing bias. The developing unit 46 employing the one-component developing method has been described above.

  Next, the developing section 46 for cleaning the surface 30a of the photoconductor 30 will be described. The developing unit 46 cleans the surface 30a of the photoconductor 30, so that the surface 30a of the photoconductor 30 can be cleaned even when a cleaning unit (particularly, a cleaning blade) is not provided. Thus, the surface 30a of the photoconductor 30 can be cleaned while reducing the wear of the charge generation layer 33 of the photoconductor 30.

  The developing unit 46 can remove components remaining on the surface 30a of the photoconductor 30 (hereinafter, sometimes referred to as “residual components”). An example of the residual component is a toner component, more specifically, a toner or a free external additive. Another example of the residual component is a non-toner component, and more specifically, a minute component (for example, paper dust) of the recording medium P.

In order for the developing unit 46 to efficiently clean the surface 30a of the photoconductor 30, it is preferable that one or both of the following conditions (a) and (b) are satisfied.
Condition (a): A contact developing method is adopted, and a peripheral speed (rotational speed) difference is provided between the photoconductor 30 and the developing unit 46.
Condition (b): The surface potential of the photoconductor 30 and the potential of the developing bias satisfy the following mathematical expressions (b-1) and (b-2).
0 (V) <the potential of the developing bias (V) <the surface potential of the unexposed area of the photoconductor 30 (V) (b-1)
Developing bias potential (V)> surface potential of exposed area of photoconductor 30 (V)> 0 (V) (b-2)

  If the contact developing method shown in the condition (a) is adopted and a peripheral speed difference is provided between the photoconductor 30 and the developing unit 46 (specifically, the developing roller 230), the surface 30a of the photoconductor 30 becomes The developer is brought into contact with the developing roller 230, and the adhered components on the surface 30a of the photoconductor 30 are removed by friction with the developing roller 230. The peripheral speed of the developing roller 230 is preferably higher than the peripheral speed of the photoconductor 30.

  The condition (b) assumes that the developing method is a reversal developing method. In order to improve the electrical characteristics of the photoconductor 30, which is a single-layer photoconductor, the charging polarity of the toner, the surface potential of the unexposed area of the photoconductor 30, the surface potential of the exposed area of the photoconductor 30, and the potential of the developing bias Are preferably of positive polarity. The surface potential of the unexposed area and the surface potential of the exposed area of the photoconductor 30 are determined by the following procedure: after the primary transfer unit 54 transfers the toner image from the photoconductor 30 to the intermediate transfer belt 56, the charging unit 42 It is measured before charging the surface 30a of 30.

  When the mathematical expression (b-1) of the condition (b) is satisfied, the electrostatic force acting between the toner remaining on the photoconductor 30 (hereinafter sometimes referred to as a residual toner) and the unexposed area of the photoconductor 30 The repulsive force is larger than the electrostatic repulsive force acting between the residual toner and the developing unit 46 (specifically, the developing roller 230). For this reason, the residual toner in the unexposed area of the photoconductor 30 moves from the surface 30 a of the photoconductor 30 to the developing roller 230 and is collected.

  When the mathematical expression (b-2) of the condition (b) is satisfied, the electrostatic repulsion acting between the residual toner and the exposed region of the photoconductor 30 causes the electrostatic repulsion acting between the residual toner and the developing roller 230 to change. It is smaller than the target repulsion. Therefore, the residual toner in the exposed area of the photoconductor 30 is held on the surface 30a of the photoconductor 30. The toner held in the exposed area of the photoconductor 30 is used for image formation as it is.

  The example of the image forming apparatus 100 including the photoconductor 30 of the present embodiment has been described above with reference to FIGS. 4 and 5. Note that the image forming apparatus including the photoconductor 30 of the present embodiment is not limited to the image forming apparatus 100 described above. For example, the image forming apparatus may be a monochrome image forming apparatus. In this case, the image forming apparatus may include, for example, only one image forming unit. Further, although the above-described image forming apparatus 100 is a tandem type image forming apparatus, the image forming apparatus may employ, for example, a rotary type. Further, although the above-described image forming apparatus 100 is an image forming apparatus of the intermediate transfer type, the image forming apparatus may employ, for example, a direct transfer type. When the image forming apparatus employs the direct transfer method, the transfer object corresponds to a recording medium.

<3. Process cartridge>
Subsequently, an example of a process cartridge including the photoconductor 30 according to the present embodiment will be described with reference to FIG. The process cartridge is a cartridge for forming an image. The process cartridge corresponds to each of the image forming units 40a to 40d. The process cartridge includes the photoconductor 30 according to the embodiment. The process cartridge may further include at least one selected from the group consisting of a charging unit 42, an exposing unit 44, a developing unit 46, and a transfer unit (corresponding to the primary transfer unit 54), in addition to the photoconductor 30. . The process cartridge may further include one or both of a cleaning unit (not shown) and a charge removing unit (not shown). Preferably, the process cartridge does not include a cleaning blade. The process cartridge may adopt 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 characteristics and the like of the photoconductor 30 deteriorate, the process cartridge including the photoconductor 30 can be easily and quickly replaced. The process cartridge including the photoconductor 30 of the present embodiment has been described above with reference to FIG.

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

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

(Charge generator)
As the charge generating agent, the Y-type titanyl phthalocyanine described in the embodiment was prepared. Titanyl phthalocyanine was a compound represented by the chemical formula (CG1) described in the embodiment. This titanyl phthalocyanine had a main peak at a Bragg angle (2θ ± 0.2 °) of 27.2 ° and no peak at 26.2 ° C. in a CuKα characteristic X-ray diffraction spectrum. This titanyl phthalocyanine does not have a peak in the range of 50 ° C. or more and less than 270 ° C. other than the peak accompanying the vaporization of the adsorbed water, and has one peak in the range of 270 ° C. or more and 400 ° C. or less in the thermal characteristics by DSC. I was

(Primary hole transport agent)
The compound (HT1) described in the embodiment was prepared as the first hole transporting agent.

(First electron transport agent)
The compounds (ET1-3), (ET1-12), (ET2-4) and (ET3-1) described in the embodiment were prepared as the first electron transporting agent. Two or three of these compounds were selected and used as the first electron transporting agent. Each of the two first electron transporting agents used is referred to as a first electron transporting agent A and a first electron transporting agent B. Further, each of the three types of first electron transporting agents used is described as a first electron transporting agent A, a first electron transporting agent B, and a first electron transporting agent C.

(First binder resin)
As the first binder resin for forming the charge generation layer, the polycarbonate resin (R-1) described in the embodiment was prepared. The viscosity average molecular weight of the polycarbonate resin (R-1) was 30,000.

<Material for Forming Charge Transport Layer>
The following second hole transport agent, second electron transport agent, and second binder resin were prepared as materials for forming the charge transport layer of the photoreceptor.

(Second hole transport agent)
The compound (HT1) described in the embodiment was prepared as the second hole transporting agent.

(Second binder resin)
A polystyrene resin (“PSJ-polystyrene HIPS” manufactured by PS Japan Co., Ltd.) was prepared as the second binder resin.

(Second electron transport agent)
The compounds (ET1-3), (ET1-12), (ET5-1), (ET5-2) and (ET5-3) described in the embodiment were prepared as the second electron transporting agent. Compounds (ET5-1), (ET5-2) and (ET5-3) were synthesized by the following method.

(Production of Compound (ET5-1))
Compound (ET5-1) 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) was added to the compound 4 represented by the chemical formula (1G). 64 g (20 mmol) and 50 mL of picoline were charged into a flask to prepare a picoline solution. The temperature of the contents of the flask was increased to 100 ° C. and maintained at 100 ° C., and the contents of the flask were stirred for 4 hours. After the reaction, ion-exchanged water was charged 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. Thereby, the compound (ET5-1) was obtained. The yield of compound (ET5-1) was 4.16 g, and the yield of compound (ET5-1) from compound (F) in reaction (r-4) was 60 mol%.

(Production of compound (ET5-3))
Compound (ET5-3) was produced in the same manner as in the production of compound (ET5-1) except for the following points. In the production of compound (ET5-3), 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 (ET5-3) was obtained instead of the compound (ET5-1). The yield of compound (ET5-3) was 3.98 g, and the yield of compound (ET5-3) from compound (F) in reaction (r-4) was 65 mol%.

(Production of compound (ET5-2))
Reactions represented by the reaction formulas (r'-1), (r'-2) and (r'-3) (hereinafter referred to as reaction (r'-1), reaction (r'-2), and reaction ( Compound (ET5-2) was produced according to the method described in r′-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, 50 mL of dioxane was charged into the flask to prepare a dioxane solution. The temperature of the contents of the flask was increased to 100 ° C. and maintained at 100 ° C., and the contents of the flask were stirred for 2 hours. After the reaction, dioxane was removed to obtain a residue. The residue obtained was purified by silica gel column chromatography 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 the reaction (r'-2), the compound (2C ') and 15 mL of trifluoroacetic acid were charged into a flask to prepare a trifluoroacetic acid solution. For the compound (2C '), the entire amount obtained in the reaction (r'-1) was used in the reaction (r'-2). The temperature of the contents of the flask was raised to 80 ° C. and maintained at 80 ° C., and the contents of the flask were stirred for 24 hours. After the reaction, trifluoroacetic acid was removed to obtain a residue. The residue obtained was purified by silica gel column chromatography 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), the 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 placed in a flask. To prepare a dioxane solution. The temperature of the contents of the flask was increased to 100 ° C. and maintained at 100 ° C., and the contents of the flask were stirred for 2 hours. After the reaction, dioxane was removed to obtain a residue. The residue obtained was purified by silica gel column chromatography using ethyl acetate as a developing solvent. Thus, compound (ET5-2) was obtained. The yield of compound (ET5-2) was 2.69 g, and the yield of compound (ET5-2) from compound (1A) in reactions (r′-1) to (r′-3) was 45 mol%. there were.

Next, ¹ H-NMR spectra of the manufactured compounds (ET5-1) to (ET5-3) were measured using a proton nuclear magnetic resonance spectrometer (300 MHz, manufactured by JASCO Corporation). CDCl ₃ was used as a solvent. Tetramethylsilane (TMS) was used as an internal standard sample. Among these, the chemical shift value of (ET5-1) is shown as a typical example. It was confirmed from the chemical shift value of the ¹ H-NMR spectrum that (ET5-1) was obtained. Similarly, for the compounds (ET5-2) and (ET5-3), it was confirmed from the chemical shift values of the ¹ H-NMR spectrum that the compounds (ET5-2) and (ET5-3) were obtained.
Compound (ET5-1): 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>
Photoconductors (A-1) to (A-9) and (B-1) to (B-6) were manufactured using the materials for forming the charge generation layer and the charge transport layer.

(Production of Photoconductor (A-1))
First, a charge transport layer was formed. Specifically, in a container, 40 parts by mass of a compound (HT1) as a second hole transporting agent, compound (ET1-3) as a second electron transporting agent, 100 parts by mass of a second binder resin, and tetrahydrofuran 300 as a solvent Parts by mass were charged. The contents of the container were mixed using a ball mill for 10 hours to dissolve the material in the solvent. Thus, a coating liquid for a charge transport layer was obtained. Using a dip coating method, a coating solution for a charge transport layer was applied to a conductive substrate (a drum-shaped support made of aluminum, diameter 30 mm, total length 247 mm) to form a coating film on the conductive substrate. The conductive substrate on which the coating film was formed was dried at 100 ° C. for 30 minutes to remove tetrahydrofuran from the coating film. As a result, a charge transport layer (film thickness: 20 μm) was formed on the conductive substrate.

  Next, a charge generation layer was formed. Specifically, 3 parts by mass of a charge generating agent, 50 parts by mass of a compound (HT1) as a first hole transporting agent, 25 parts by mass of a compound (ET1-3) as a first electron transporting agent A, and a first electron transporting agent B Of the compound (ET3-1), 100 parts by mass of the first binder resin, and 800 parts by mass of toluene as the solvent. The contents of the container were mixed using a ball mill for 50 hours to disperse the material in the solvent. Thus, a coating solution for a charge generation layer was obtained. The coating liquid for a charge generation layer was applied to the charge transport layer formed on the conductive substrate using a dip coating method, and a coating film was formed on the charge transport layer. The conductive substrate provided with the charge transport layer on which the coating film was formed was dried at 100 ° C. for 60 minutes. Thereby, toluene was removed from the coating film, and a charge generation layer (thickness: 10 μm) was formed on the charge transport layer. As a result, a photoreceptor (A-1) was obtained.

(Production of Photoconductors (A-2) to (A-9) and (B-1) to (B-6))
Except for the following points (1) to (7), the photoconductors (A-2) to (A-9) and (B-1) to Each of (B-6) was manufactured.
(1) In the formation of the charge transport layer of the photoconductor (A-1), the compound (ET1-3) was added as the second electron transporting agent, but the photoconductors (A-2) to (A-9) and ( In the formation of the charge transport layers of B-4) to (B-6), a second electron transport agent of the type shown in Table 1 was added. In the formation of the charge transport layers of the photoconductors (B-1) to (B-3), the second electron transport agent was not added.
(2) In forming the charge generation layer of the photoconductor (A-1), the compound (ET1-3) was added as the first electron transporting agent A, but the photoconductors (A-2) to (A-9) and In forming the charge generation layers (B-1) to (B-6), the first electron transporting agent A of the type shown in Table 2 was added.
(3) In the formation of the charge generation layer of the photoconductor (A-1), 25 parts by mass of the first electron transporting agent A was added, but the photoconductors (A-2) to (A-9) and (B- In the formation of the charge generation layers 1) to (B-6), the amount of the first electron transporting agent A shown in Table 2 (mass M _ETM1A ) was added.
(4) In the formation of the charge generation layer of the photoconductor (A-1), the compound (ET3-1) was added as the first electron transporting agent B, but the photoconductors (A-2) to (A-9) and In the formation of the charge generation layers (B-1), (B-2) and (B-4) to (B-6), the first electron transporting agent B of the type shown in Table 2 was added. In the formation of the charge generation layer of the photoconductor (B-3), the first electron transporting agent B was not added.
(5) In the formation of the charge generation layer of the photoconductor (A-1), 30 parts by mass of the first electron transporting agent B was added, but the photoconductors (A-2) to (A-9) and (B- 1), (B-2), and (B-4) to (B-6) in forming the charge generation layers, the first electron transporting agent B in an amount (mass M _ETM1B ) shown in Table 2 was added.
(6) In the formation of the charge generation layer of the photoreceptor (A-8), in addition to the first electron transporting agent A and the first electron transporting agent B, a first electron transporting agent C of the type shown in Table 2 is used. 2 (mass M _ETM1C ).
(7) In the formation of the charge generation layer of the photoconductor (A-1), 50 parts by mass of the first hole transporting agent was added, but the photoconductors (A-2) to (A-9) and (B- In forming the charge generation layers 1) to (B-6), the amount of the first hole transporting agent shown in Table 2 (mass _MHTM1 ) was added.

<Evaluation of transfer memory suppression>
For each of the manufactured photoconductors (A-1) to (A-9) and (B-1) to (B-6), it was evaluated whether or not the occurrence of transfer memory was suppressed. The evaluation of whether or not the occurrence of transfer memory was suppressed was performed in an environment at a temperature of 25 ° C. and a relative humidity of 45% RH.

  First, the photoconductor was mounted on an evaluation machine. As the evaluation machine, a modified machine in which a static eliminator and a cleaning blade were removed from a monochrome printer ("FS-1300D" manufactured by Kyocera Document Solutions Inc.) was used. The evaluation machine employed a non-magnetic one-component developing system, a static elimination-less system, and a cleaner-less system. The developing section of the evaluation machine was provided with a supply roller, a developing roller, and a regulating blade. The developing unit of the evaluation machine had a configuration for cleaning the surface of the photoconductor. The transfer current applied by the transfer unit was set to -15 μA. The rotation speed of the photoconductor was 150 mm / sec. Further, a non-magnetic one-component developer was charged into a developing section of the evaluation machine.

  The image I (pattern image with a printing rate of 4%) was continuously printed on 5000 sheets of paper (“Fine-quality PPC paper” manufactured by Fuji Xerox Co., Ltd.) using an evaluation machine. Subsequently, one evaluation image including the image II and the image III was printed. Image II was an image in which one white (image density 0%) circular pattern appeared on a black (image density 100%) background. Image II corresponded to the image formed in the first rotation of the photoreceptor. Image III was an image of the entire surface halftone (image density of 12.5%). Image III corresponded to an image formed in the second round of the photoconductor.

  The obtained image III was observed with the naked eye, and the presence or absence of an image ghost derived from the image II was confirmed. Further, the obtained image III was observed at a magnification of 10 times using a loupe (“TL-SL10K” manufactured by TRUSCO) to confirm the presence or absence of an image ghost derived from image II. When a transfer memory is generated on the photoconductor, an image ghost (especially, a negative ghost) occurs in a formed image. The image ghost is an image defect in which an area corresponding to the white circular pattern of the image II printed on the first rotation of the photoconductor appears black in the full-halftone image III printed on the second rotation of the photoconductor. is there. Based on the confirmation result of the image ghost, it was evaluated whether or not the occurrence of the transfer memory was suppressed according to the following criteria. Table 3 shows the evaluation results. In addition, the photoreceptor whose evaluation was A or B was evaluated as the occurrence of transfer memory was suppressed.

(Evaluation criteria for transfer memory suppression)
Evaluation A: No image ghost was confirmed by visual observation or loupe observation.
Evaluation B: Image ghost was not confirmed by visual observation, but was confirmed by loupe observation.
Evaluation C: Image ghost was observed with the naked eye.

<Evaluation of suppression of crystallization of photosensitive layer>
For each of the manufactured photoconductors (A-1) to (A-9) and (B-1) to (B-6), whether or not crystallization of the photosensitive layer was suppressed was evaluated. First, the entire surface of the photoreceptor was visually observed to confirm the presence or absence of a crystallized portion in the photosensitive layer. Further, the entire area of the surface of the photoreceptor was observed at a magnification of 10 times using a loupe (“TL-SL10K” manufactured by TRUSCO) to confirm the presence or absence of a crystallized portion in the photosensitive layer. Based on the confirmation results, whether or not crystallization of the photosensitive layer was suppressed was evaluated according to the following criteria. Table 3 shows the evaluation results. In addition, the photoreceptor evaluated as A was evaluated as having suppressed crystallization of the photosensitive layer.

(Evaluation criteria for crystallization suppression)
Evaluation A: The crystallized portion of the photosensitive layer was not confirmed by visual observation or loupe observation.
Evaluation B: The crystallized portion of the photosensitive layer was not confirmed by visual observation, but was confirmed by loupe observation.
Evaluation C: The portion crystallized on the photosensitive layer was observed by visual observation.

In Table 1, parts, _MHTM2 and _METM2 are parts by mass, the mass of the second hole transporting agent contained in the charge transporting layer, and the mass of the second electron transporting agent contained in the charge transporting layer, respectively. Is shown. In Table 1, " _METM2 / _MHTM2 " is the _ratio of the mass ( _METM2 , units: parts by mass) of the second electron transporting agent to the mass ( _MHTM2 , units: parts by mass) of the second hole transporting agent. Is shown. In Table 1, " _METM2 / _MRESIN2 " indicates the _ratio of the mass ( _METM2 , unit: parts by mass) of the second electron transporting agent to the mass ( _MRESIN2 , unit: parts by mass) of the second binder resin. . In Table 1, “M _RESIN2 / M _CTL ” indicates the ratio of the mass (M _RESIN2 , unit: parts by mass) of the second binder resin to the mass of the charge transport layer (M _CTL , units: parts by mass). In Table 1, "M _ETM2 / M _CTL" is the mass of the charge transport layer (M _CTL, unit: parts by weight): shows the ratio of relative, the mass of the second electron transfer agent (parts by mass M _ETM2, units). Note that “M _CTL ” is calculated from a calculation formula “M _CTL = mass of second hole transporting agent M _HTM2 + mass of second electron transporting agent M _ETM2 + mass of second binder resin M _RESIN2 ”.

In Table 2, “parts” and “CGM” indicate parts by mass and the charge generating agent, respectively. In Table 2, M _CGM , M _ETM1A , M _ETM1B , M _ETM1C , M _HTM1 , and M _RESIN1 are respectively the mass of the charge generator, the mass of the first electron transport agent A, The mass of the electron transport agent B, the mass of the first electron transport agent C, the mass of the first hole transport agent, and the mass of the first binder resin are shown.

In Table 2, “M _ETM1 / M _HTM1 ” means the total mass (M _ETM1 , unit: 2) of the two or more first electron transporting agents with respect to the mass (M _HTM1 , unit: parts by mass) of the first hole transporting agent. Parts by mass). M _ETM1 / M _HTM1 is formula "M _ETM1 / M _HTM1 = (mass M _ETM1A + mass M _ETM1C mass M _ETM1B + first electron transport agent C of the first electron-transporting material B of the first electron-transporting material A) / Mass of first hole transporting agent M _HTM1 ". When the ratio M _ETM1 / M _HTM1 is greater than 1.00, indicating that two or more first electron transport material total mass M _ETM1 of greater than the mass M _HTM1 the first hole transporting material.

In Table 2, “M _ETM1 / M _RESIN1 ” is the total mass (M _ETM1 , unit: parts by mass) of two or more first electron transporting agents with respect to the mass of the first binder resin (M _RESIN1 , unit: parts by mass). ). M _ETM1 / M _RESIN1 is formula "M _ETM1 / M _RESIN1 = (mass M _ETM1A + mass M _ETM1C mass M _ETM1B + first electron transport agent C of the first electron-transporting material B of the first electron-transporting material A) / Mass of first binder resin M _RESIN1 ”.

In Table 2, “M _RESIN1 / M _CGL ” indicates the ratio of the mass of the first binder resin (M _RESIN1 , unit: parts by mass) to the mass of the charge generation layer (M _CGL , units: parts by mass). M _RESIN1 / M _CGL is calculated from a calculation formula “M _RESIN1 / M _CGL = mass of first binder resin M _RESIN1 / mass of charge generation layer M _CGL ”. Note that “M _CGL ” is calculated by the formula “M _CGL = Mass of charge generating agent M _CGM + Mass of first electron transporting agent A M _ETM1A + Mass of first electron transporting agent B M _ETM1B + First electron transporting agent C It is calculated from the mass M _ETM1C + first hole transport material mass M _HTM1 + mass M _RESIN1 first binder resin ".

In Table 2, “M _ETM1 / M _CGL ” is the total mass (M _ETM1 , unit: parts by mass) of two or more types of first electron transporting agents with respect to the mass of the charge generation layer (M _CGL , units: parts by mass). Shows the ratio of M _ETM1 / M _CGL is formula "M _ETM1 / M _CGL = (mass M _ETM1A + mass M _ETM1C mass M _ETM1B + first electron transport agent C of the first electron-transporting material B of the first electron-transporting material A) / Mass of charge generation layer M _CGL ”.

Photoconductors (A-1) to (A-9) each had a conductive substrate, a charge transport layer provided on the conductive substrate, and a charge generation layer provided on the charge transport layer. The charge generating layer contained a charge generating agent, a first hole transporting agent, a first electron transporting agent, and a first binder resin. The first electron transporting agent contained at least two of compound (1-1), compound (2), compound (3), compound (4) and compound (5-1). The ratio M _ETM1 / M _RESIN1 of the total mass of the two or more first electron transporting agents to the mass of the first binder resin was 0.45 or more. Total mass M _ETM1 of two or more first electron transporting material was greater than the mass M _HTM1 the first hole transporting material. That is, the ratio _METM1 / _MHTM1 was greater than 1.00. The charge transporting layer contained a second hole transporting agent and a second electron transporting agent. Therefore, as is apparent from Table 3, in the photoconductors (A-1) to (A-9), the evaluation of the transfer memory was evaluated as A or B, and the occurrence of the transfer memory was suppressed. In the photoconductors (A-1) to (A-9), the evaluation of crystallization suppression was A, and the crystallization of the photosensitive layer was also suppressed.

  On the other hand, the charge transport layers of the photoconductors (B-1) and (B-2) did not contain the second electron transport agent. Therefore, as is clear from Table 3, in the photoconductors (B-1) and (B-2), the evaluation of transfer memory suppression was C, and transfer memory was generated.

  The charge transport layer of the photoconductor (B-3) did not contain the second electron transport agent. In addition, the charge generation layer of the photoconductor (B-3) has a compound (1-1), a compound (2), a compound (3), a compound (4), and a compound (5-1) as a first electron transporting agent. Did not contain two or more of these. Therefore, as is clear from Table 3, in the photoreceptor (B-3), the evaluation of transfer memory suppression was C, and transfer memory occurred. In the photoconductor (B-3), the evaluation of the crystallization suppression was C, and the crystallization of the photosensitive layer was not suppressed.

In the photoconductor (B-4), the ratio M _ETM1 / M _RESIN1 of the total mass of the two or more first electron transporting agents to the mass of the first binder resin was less than 0.45. In the photoreceptor (B-4), the total mass _METM1 of the two or more first electron transporting agents was not _larger than the mass _MHTM1 of the first hole transporting agent. That is, the ratio _METM1 / _MHTM1 was 1.00 or less. Therefore, as is clear from Table 3, in the photoreceptor (B-4), the evaluation of transfer memory suppression was C, and transfer memory was generated.

In the photoreceptor (B-5), the total mass _METM1 of the two or more first electron transporting agents was not _larger than the mass _MHTM1 of the first hole transporting agent. That is, the ratio _METM1 / _MHTM1 was 1.00 or less. Therefore, as is clear from Table 3, in the case of the photoconductor (B-5), the evaluation of transfer memory suppression was C, and transfer memory occurred.

In the photoreceptor (B-6), the total mass _METM1 of the two or more first electron transporting agents was not _larger than the mass _MHTM1 of the first hole transporting agent. That is, the ratio _METM1 / _MHTM1 was 1.00 or less. Therefore, as is clear from Table 3, in the photoconductor (B-6), the evaluation of the transfer memory suppression was C, and the transfer memory was generated. In the photoconductor (B-6), the evaluation of the crystallization suppression was B, and the crystallization of the photosensitive layer was not suppressed.

  From the above, it was shown that the photoreceptor according to the present invention can achieve both suppression of crystallization of the photosensitive layer and suppression of occurrence of transfer memory. Further, it has been shown that the process cartridge and the image forming apparatus according to the present invention can suppress generation of image ghost due to the transfer memory in a formed image by including such a photoconductor.

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

30 Positively Charged Laminated Electrophotographic Photoreceptor 30a Photoreceptor Surface 31 Conductive Substrate 32 Charge Transport Layer 33 Charge Generation Layer 42 Charger 44 Exposure 46 Development 54 Primary Transfer 56 Intermediate Transfer Belt 58 Secondary Transfer 100 Image Forming device 220 Supply roller 220a Supply roller surface 230 Developing roller 230a Developing roller surface 400 Regulator blade TL Toner layer P Recording medium

Claims (12)

A conductive substrate, a charge transport layer provided on the conductive substrate, and a charge generation layer provided on the charge transport layer,
The charge generation layer contains a charge generation agent, a first hole transporting agent, a first electron transporting agent, and a first binder resin,
The first electron transporting agent contains two or more of the compounds represented by general formulas (1-1), (2), (3), (4), and (5-1),
The ratio of the total mass of the two or more first electron transporting agents to the mass of the first binder resin is 0.45 or more,
The total mass of the two or more first electron transporting agents is greater than the mass of the first hole transporting agent,
The charge transport layer contains a second hole transport agent and a second electron transport agent ,
The positively-charged electrophotographic photosensitive member, wherein the second electron transporting agent contains a compound represented by the chemical formula (ET5-1), (ET5-2) or (ET5-3) .

(In the above general formulas (1-1), (2) and (3), R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ^{13) 14} is each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 1 to 6 carbon atoms which may have a substituent, and a carbon atom optionally having a substituent. An alkenyl group having 2 to 6 or less, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, an aryl group having 6 to 14 carbon atoms which may have a substituent or a substituent. Represents a cycloalkyl group having 3 or more and 8 or less carbon atoms, wherein R ¹⁴ is not a hydrogen atom,
In the general formula (4), R ⁶ and R ⁷ each independently represent a hydrogen atom, a nitro group, a cyano group, an alkenyl group having 2 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. A cycloalkyl group having 3 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms which may have at least one alkoxy group having 1 to 6 carbon atoms, or 1 to 6 carbon atoms Represents an aryl group having 6 to 14 carbon atoms which may have at least one of the following alkyl groups,
In the general formula (5-1), Q ⁶ and Q ⁷ are each independently:
An aryl group having 6 or more and 14 or less carbon atoms which may have one or more halogen atoms,
An aryl group having 6 or more and 14 or less carbon atoms having at least one alkyl group having 1 or more and 6 or less carbon atoms, which may have one or more halogen atoms;
An aryl group having 6 or more and 14 or less carbon atoms having at least one benzoyl group, which may have one or more halogen atoms,
An aralkyl group having 7 or more and 20 or less carbon atoms which may have one or more halogen atoms,
A group consisting of an alkyl group having 1 to 8 carbon atoms which may have one or more halogen atoms, and a cycloalkyl group having 3 to 10 carbon atoms which may have one or more halogen atoms; And at least one of Q ⁶ and Q ⁷ has one or more halogen atoms. )

2. The positively-charged laminated electrophotograph according to claim 1, wherein the first electron transporting agent contains at least two of the compounds represented by the general formulas (1-1), (2), and (3). Photoconductor. In the general formula (1-1), R ¹ , R ² , R ^3, and R ⁴ each independently represent an aryl group having 1 to 6 carbon atoms, which may have an aryl group having 6 to 14 carbon atoms. The following alkyl group, a hydrogen atom, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms,
In the general formula (2), R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ each independently represent an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a carbon atom. Represents a cycloalkyl group having a number of 3 or more and 8 or less,
The positive charge according to claim 2 , wherein, in the general formula (3), R ¹² and R ¹³ each independently represent an alkyl group having 1 to 6 carbon atoms, and R ¹⁴ represents a halogen atom. Laminated electrophotographic photoreceptor. Two or more of the compounds represented by the general formulas (1-1), (2) and (3) are represented by the chemical formulas (ET1-3), (ET1-12), (ET2-4) and (ET3). The positively charged laminated electrophotographic photoreceptor according to claim 2 or 3 , which is two or more of the compounds represented by -1).

The ratio according to any one of claims 1 to 4 , wherein a ratio of a total mass of the two or more first electron transporting agents to a mass of the first hole transporting agent is larger than 1.00 and equal to or smaller than 1.60. The positively-charged laminated electrophotographic photosensitive member as described in the above. The positively-charged electrophotographic photosensitive member according to any one of claims 1 to 5 , wherein a ratio of a mass of the first binder resin to a mass of the charge generation layer is 0.55 or less. The positively-charged electrophotographic photosensitive member according to any one of claims 1 to 6 , wherein the charge generation layer is provided as an outermost surface layer. It comprises a positively charged laminated electrophotographic photoconductor according to any one of claim 1 to 7 a process cartridge. An image forming apparatus comprising a positively-charged laminated electrophotographic photoreceptor according to any one of claims 1 to 7 , a charging unit, an exposure unit, a development unit, and a transfer unit,
The charging unit charges the surface of the positively charged laminated electrophotographic photosensitive member to a positive polarity,
The exposure unit exposes the charged surface of the positively-charged laminated electrophotographic photosensitive member to form an electrostatic latent image on the surface of the positively-charged laminated electrophotographic photosensitive member,
The developing unit supplies toner to the electrostatic latent image, develops the electrostatic latent image as a toner image,
The image forming apparatus, wherein the transfer unit transfers the toner image from the positively charged laminated electrophotographic photosensitive member to a transfer target. The developing unit includes a supply roller, a developing roller, and a regulating blade,
The supply roller supplies the toner, which is a non-magnetic one-component developer, to the development roller,
The developing roller holds a toner layer containing the toner on the surface of the developing roller,
The regulating blade regulates the thickness of the toner layer held on the surface of the developing roller,
The toner thickness is included in the toner layer is regulated, said supplied from the surface of the developing roller to the electrostatic latent image, the electrostatic latent image is developed as the toner image, claim 9 An image forming apparatus according to claim 1. The developing unit cleans the surface of the positively charged laminated type electrophotographic photoconductor, an image forming apparatus according to claim 9 or 10. The region of the surface of the material to be transferred to said toner image is transferred positively charged multilayer electrophotographic photoreceptor is again charged by the charging unit without being neutralization, claim 9-11 An image forming apparatus according to claim 1.

Images