JPWO2018061542A1 - Electrophotographic photosensitive member, process cartridge and image forming apparatus - Google Patents

Abstract

The electrophotographic photoreceptor (100) comprises a conductive substrate (101) and a single photosensitive layer (102). The photosensitive layer contains a charge generating agent, a hole transporting agent, and two or more electron transporting agents. The total mass of the two or more electron transport agents is greater than the mass of the hole transport agent. The charging potential of the electrophotographic photosensitive member when charged using a corotron charger whose current value is set to -5 μA is -550 V or more and less than 0 V. Positive rotation, exposure and transfer are performed on each circumference while rotating the electrophotographic photosensitive member three times, the charging potential on each circumference is the same positive value, the exposure amount is the same, and the transfer current value is the same Sometimes, the surface potential VpLA of the exposed area of the electrophotographic photosensitive member after exposure in the first cycle and before transfer, and the surface potential VpLC of the exposed area of the electrophotographic photosensitive member after exposure in the third cycle and before transfer Difference VpLA-VpLC is 0 V or more.

Description

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

  The electrophotographic photosensitive member is used in an electrophotographic image forming apparatus. As the electrophotographic photosensitive member, for example, a laminated type electrophotographic photosensitive member or a single layer type electrophotographic photosensitive member is used. The multi-layered electrophotographic photosensitive member includes, as a photosensitive layer, a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The single-layer type electrophotographic photosensitive member includes a single-layer photosensitive layer having a charge generation function and a charge transport function as a photosensitive layer.

  2. Description of the Related Art In recent years, in order to reduce the size and speed of an image forming apparatus, an image forming apparatus that employs a static elimination method has been studied. The image forming apparatus described in Patent Document 1 adopts a static elimination method. The image forming apparatus includes an electrophotographic photosensitive member. The electrophotographic photosensitive member comprises a photosensitive layer containing a tristyryl triphenylamine compound having a specific structure on a conductive substrate.

JP, 2011-64963, A

  However, since the image forming apparatus adopting the static elimination method does not have the static elimination portion, the surface potential of the electrophotographic photosensitive member tends to be uneven, and an image defect may occur in the formed image. In the image forming apparatus described in Patent Document 1, the suppression of the generation of the image ghost due to the exposure memory is not sufficient.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an electrophotographic photosensitive member capable of suppressing the occurrence of an image ghost in a formed image. Another object of the present invention is to provide a process cartridge and an image forming apparatus capable of suppressing the generation of an image ghost in a formed image by providing such an electrophotographic photosensitive member.

The electrophotographic photosensitive member of the present invention comprises a conductive substrate and a single-layer photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transporting agent, and two or more electron transporting agents. The total mass of the two or more electron transport agents is greater than the mass of the hole transport agent. The charging potential of the electrophotographic photosensitive member when charged using a corotron charger whose current value is set to -5 μA is -550 V or more and less than 0 V. Positive rotation, exposure and transfer are performed on each circumference while rotating the electrophotographic photosensitive member three times, the charging potential on each circumference is the same positive value, the exposure amount is the same, and the transfer current value is the same. At a certain time, the surface potential Vp _LA of the exposed area of the electrophotographic photosensitive member after exposure in the first cycle and before transfer, and the exposed area of the electrophotographic photosensitive member after exposure in the third cycle and before transfer difference Vp _LA -Vp _LC between the surface potential Vp _LC of is not less than 0V.

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

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

  The electrophotographic photosensitive member of the present invention can suppress the generation of an image ghost in a formed image. Further, the process cartridge and the image forming apparatus of the present invention can suppress the generation of the image ghost in the formed image by including such an electrophotographic photosensitive member.

FIG. 1 is a schematic cross-sectional view showing an example of an electrophotographic photosensitive member according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view showing an example of an electrophotographic photosensitive member according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view showing an example of an electrophotographic photosensitive member according to an embodiment of the present invention. FIG. 6 is a graph showing the relationship between the current value of the corotron charger and the charging potential of the electrophotographic photosensitive member. It is a figure which shows the structure of a 1st measuring apparatus. It is a figure which shows the structure of a 2nd measuring apparatus. It is a flowchart illustrating a method of measuring the potential difference Vp _LA -Vp _LC. FIG. 1 is a view showing an example of the configuration of an image forming apparatus, and the image forming apparatus includes an electrophotographic photosensitive member according to an embodiment of the present invention. FIG. 7 is a diagram showing another example of the configuration of the image forming apparatus, which includes the electrophotographic photosensitive member according to the embodiment of the present invention. It is a < ¹ > H-NMR spectrum of a compound represented by Chemical formula (1-1), This compound is contained in the electrophotographic photoreceptor which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited at all to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, although description may be suitably abbreviate | omitted about the location where description overlaps, the summary of invention is not limited.

  Hereinafter, “system” may be added after the compound name to generically generically refer to the compound and its derivative. Moreover, when a "system" is attached after a compound name and it represents a polymer name, it means that the repeating unit of a polymer originates in a compound or its derivative (s).

  Hereinafter, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 4 carbon atoms, carbon An alkyl group having 1 to 3 atoms, an alkyl group having 2 to 5 carbon atoms, an alkyl group having 2 to 3 carbon atoms, an alkyl group having 4 to 10 carbon atoms, 4 to 6 carbon atoms Alkyl groups having 5 to 7 carbon atoms, alkenyl groups having 2 to 6 carbon atoms, alkenyl groups having 2 to 4 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, carbon atoms Alkoxy group having 1 to 3 carbon atoms, aryl group having 6 to 14 carbon atoms, cycloalkyl group having 3 to 10 carbon atoms, cycloalkane having 5 to 7 carbon atoms, carbon atoms 1 to 6 alkylene group and cycloalkylidene group having a carbon number of 5 to 7 of, unless defines any, respectively following meanings.

  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 10 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 4 carbon atoms, 1 to 3 carbon atoms The following alkyl groups, alkyl groups having 2 to 5 carbon atoms, alkyl groups having 2 to 3 carbon atoms, alkyl groups having 4 to 10 carbon atoms, alkyl groups having 4 to 6 carbon atoms, and carbon The alkyl group having 5 or more and 7 or less atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and isopentyl Groups, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, heptyl group, octyl group, nonyl group or decyl 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 the examples of the alkyl group having 1 to 10 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 the examples of the alkyl group having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms are groups having 1 to 4 carbon atoms among the groups described as the examples of the alkyl group having 1 to 10 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 the examples of the alkyl group having 1 to 10 carbon atoms. Examples of the alkyl group having 2 to 5 carbon atoms are groups having 2 to 5 carbon atoms among the groups described as the examples of the alkyl group having 1 to 10 carbon atoms. Examples of the alkyl group having 2 to 3 carbon atoms are groups having 2 to 3 carbon atoms among the groups described as the examples of the alkyl group having 1 to 10 carbon atoms. Examples of the alkyl group having 4 to 10 carbon atoms are groups having 4 to 10 carbon atoms among the groups described as the examples of the alkyl group having 1 to 10 carbon atoms. Examples of the alkyl group having 4 to 6 carbon atoms are groups having 4 to 6 carbon atoms among the groups described as the examples of the alkyl group having 1 to 10 carbon atoms. Examples of the alkyl group having 5 to 7 carbon atoms are groups having 5 to 7 carbon atoms among the groups described as the examples of the alkyl group having 1 to 10 carbon atoms.

  The alkenyl group having 2 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkenyl group having 2 to 6 carbon atoms include ethenyl group, propenyl group, butenyl group, pentenyl group and hexenyl group.

  The alkenyl group having 2 to 4 carbon atoms is linear or branched and unsubstituted. As an alkenyl group having 2 to 4 carbon atoms, there may be mentioned, for example, an ethenyl group, a propenyl group or a butenyl group.

  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 group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, n-pentoxy group, An isopentoxy group, a neopentoxy group or a hexyl group may be mentioned. Examples of the alkoxy group having 1 to 3 carbon atoms are groups having 1 to 3 carbon atoms among the groups described as the examples of the alkoxy group having 1 to 6 carbon atoms.

  The aryl group having 6 or more and 14 or less carbon atoms is, for example, an unsubstituted aromatic monocyclic hydrocarbon group having 6 or more and 14 or less carbon atoms, and an unsubstituted aromatic fused bicyclic ring having 6 or more and 14 or less carbon atoms. It is a hydrogen group or an unsubstituted aromatic fused tricyclic hydrocarbon group having 6 to 14 atomic atoms. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an anthryl group or a phenanthryl group.

  The cycloalkyl group having 3 to 10 carbon atoms is unsubstituted. As a C3-C10 cycloalkyl group, a cyclopropyl group, cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, or a cyclodecyl group is mentioned, for example.

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

  The alkylene group having 1 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkylene group having 1 to 6 carbon atoms include a methylene group, an ethylene group, an n-propylene group, a 1-methylethylene group, a 2-methylethylene group, an n-butylene group, a 1-methylpropylene group, And -methylpropylene, 3-methylpropylene, 1,1-dimethylethylene, 1,2-dimethylethylene, 2,2-dimethylethylene, ethylmethylmethylene, pentylene or hexylene.

  The cycloalkylidene group having 5 to 7 carbon atoms is unsubstituted. Examples of the cycloalkylidene group having 5 to 7 carbon atoms include a cyclopentylidene group, a cyclohexylidene group or a cycloheptylidene group.

<Electrophotographic photosensitive member>
The electrophotographic photosensitive member according to the present embodiment (hereinafter, referred to as a photosensitive member) can suppress the generation of an image ghost due to the exposure memory in the formed image. The exposure memory is a phenomenon in which the charge potential of the area corresponding to the exposure area of the previous circumference is lower than the charge potential of the area corresponding to the non-exposure area of the previous circumference on the photosensitive member surface due to the influence of exposure. . Since an area corresponding to the exposure area can not be sufficiently charged, an image ghost due to the exposure memory is an image in which the image density of the area corresponding to the exposure area in the front of the photosensitive member increases in the formed image. It becomes a defect (a so-called image defect called fog or background stain).

  The structure of the photosensitive member 100 will be described below with reference to FIGS. 1A to 1C. 1A to 1C are cross-sectional views showing an example of the photosensitive member 100 according to the present embodiment.

  As shown in FIG. 1A, the photosensitive member 100 includes a conductive substrate 101 and a photosensitive layer 102. The photosensitive layer 102 is a single layer. The photosensitive member 100 is a so-called single layer type photosensitive member provided with a single layer photosensitive layer 102.

  As shown in FIG. 1B, the photosensitive member 100 may include a conductive substrate 101, a photosensitive layer 102, and an intermediate layer 103 (undercoat layer). The intermediate layer 103 is provided between the conductive substrate 101 and the photosensitive layer 102. As shown in FIG. 1A, the photosensitive layer 102 may be provided directly on the conductive substrate 101, and as shown in FIG. 1B, the photosensitive layer 102 may be formed indirectly on the conductive substrate 101 via the intermediate layer 103. May be provided.

  As shown in FIG. 1C, the photoreceptor 100 may include a conductive substrate 101, a photosensitive layer 102, and a protective layer 104. The protective layer 104 is provided on the photosensitive layer 102.

  The thickness of the photosensitive layer 102 is not particularly limited as long as the function as the photosensitive layer can be sufficiently exhibited. The thickness of the photosensitive layer 102 is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

  The structure of the photosensitive member 100 has been described above with reference to FIGS. 1A to 1C. Hereinafter, the photosensitive member will be described in more detail.

<Conductive substrate>
An example of the conductive substrate is a conductive substrate composed of a material having conductivity (hereinafter, may be described as a conductive material). Another example of the conductive substrate is a conductive substrate provided with a covering layer composed of a conductive material. As the conductive material, for example, aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium or indium can be mentioned. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). As an alloy, an aluminum alloy, stainless steel, or a brass is mentioned, for example. Among these conductive materials, aluminum or an aluminum alloy is preferable because charge transfer from the photosensitive layer to the conductive substrate is good. The surface of the conductive substrate may have an oxide film.

  The shape of the conductive substrate is appropriately selected in accordance with the structure of the image forming apparatus. Examples of the shape of the conductive substrate include a sheet or a drum. In addition, the thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

<Photosensitive layer>
The photosensitive layer contains a charge generating agent, a hole transporting agent, and two or more electron transporting agents. The photosensitive layer may further contain a binder resin. The photosensitive layer may contain an additive, if necessary. The charge generating agent, the two or more electron transporting agents, the hole transporting agent, and the component (for example, the binder resin or the additive) optionally added are contained in the photosensitive layer of one layer (single layer) Be done.

(Ratio M _ETM / M _HTM )
In the photosensitive layer of the photosensitive member according to the present embodiment, the total mass of the two or more electron transport agents is larger than the mass of the hole transport agent. That is, the ratio (M _ETM / M _HTM ) of the mass (M _ETM ) of the two or more electron transport agents to the mass (M _HTM ) of the hole transfer agent contained in the photosensitive layer is greater than 1.00. When the total mass of the electron transfer agent is larger than the mass of the hole transfer agent, the generation of an image ghost in the formed image can be suppressed.

  When the photoreceptor comprises a single-layer photosensitive layer containing a charge generating agent, an electron transferring agent and a hole transferring agent, usually, the mass of the hole transferring agent is larger than the mass of the electron transferring agent. Explain the reason to help understanding. When the photosensitive member is exposed in image formation, electrons and holes are generated from the charge generating agent in the photosensitive layer. The generated electrons are transported to the surface of the photosensitive layer by the electron transport agent. The generated holes are transported to the conductive substrate by the hole transport agent. The absorptivity of the exposed light is high near the surface of the photosensitive layer and low at the deep portion (conductive substrate side) of the photosensitive layer. Therefore, a large number of electrons and holes tend to be generated from the charge generating agent present in the vicinity of the surface of the photosensitive layer having high absorption of exposed light. When electrons and holes are generated from the charge generating agent present near the surface of the photosensitive layer, the movement distance of the holes from near the surface of the photosensitive layer to the conductive substrate is from near the surface of the photosensitive layer to the surface of the photosensitive layer Longer than the electron's travel distance. Therefore, for the purpose of improving the hole transport efficiency, the hole transport agent is usually contained in the photosensitive layer in a larger amount than the electron transport agent. However, the inventors of the present invention conducted intensive studies and found that the generation of an image ghost in a formed image can be suppressed by making the total mass of the electron transport agent larger than the mass of the hole transport agent.

To further suppress the occurrence of image ghosting in the formed image, the ratio of the total mass of two or more electron transfer agents (M _ETM ) to the mass of the hole transfer agent (M _HTM ) (M _ETM / M _HTM ) Is preferably more than 1.00 and 1.50 or less, more preferably more than 1.00 and 1.20 or less, and still more preferably 1.05 or more and 1.20 or less.

(Charge potential Vn _{0 under} negative charge measurement conditions)
In the photosensitive member according to the present embodiment, the charging potential Vn ₀ of the photoreceptor when was charged with a corotron charging device sets the current value Ic to -5 .mu.A (hereinafter referred to as the charge potential Vn ₀ in negative charging measurement conditions May be -550V or more and less than 0V. When the charge potential Vn ₀ under the negative charge measurement condition is −550 V or more and less than 0 V, the generation of the exposure memory can be suppressed, and the generation of the image ghost in the formed image can be suppressed.

Hereinafter, the relationship between the current value Ic of the corotron charger and the charging potential of the photosensitive member will be described with reference to FIG. FIG. 2 is a graph showing the relationship between the current value of the corotron charger and the charging potential of the electrophotographic photosensitive member. The horizontal axis of FIG. 2 indicates the current value Ic (unit: μA) of the corotron charger. The vertical axis in FIG. 2 indicates the charging potential Vn ₀ (unit: V) of the photosensitive member. The solid line in FIG. 2 shows the relationship between the current value Ic of the corotron charger and the charging potential Vn ₀ of the photoreceptor (PA) when the photoreceptor (PA) according to this embodiment is to be measured. Show. Broken line in FIG. 2 shows the relationship between the charge potential Vn ₀ corotron charger current value Ic and the photosensitive member (P-B) when the photosensitive member of Reference Example (P-B) was measured. When the photoconductor (PA) of the present embodiment is charged using a corotron charger having a current value Ic of -5 μA, the charging potential Vn ₀ of the photoconductor (PA) is -550 V or more and less than 0 V It is. On the other hand, when the photosensitive member (P-B) of the reference example is charged using a corotron charger whose current value Ic is set to -5 μA, the charging potential Vn ₀ of the photosensitive member (P-B) is less than -550 V is there. Above with reference to FIG. 2, it described the relationship between the current value Ic of the corotron charger, a charging potential Vn ₀ of the photosensitive member.

A photoreceptor provided with a single-layer photosensitive layer usually forms an image by positively charging the surface of the photoreceptor. Therefore, in a photoreceptor provided with a single-layer photosensitive layer, attention is focused on the positive charge characteristic of the photoreceptor. However, the present inventors intensively studied and found that the charge potential Vn ₀ under the negative charge measurement conditions contributes to the suppression of the occurrence of exposure memory in the photosensitive member provided with a single-layer photosensitive layer. The present inventors have found that the charging potential Vn ₀ of the photosensitive member when charged using a corotron charger, in which the current value Ic is set to -5 μA, in particular, contributes to the suppression of the generation of the exposure memory. . In the photosensitive member of the present embodiment, by setting the charging potential Vn ₀ under the measurement condition of negative charge of the photosensitive member to −550 V or more and less than 0 V, generation of exposure memory can be suppressed and generation of image ghost in a formed image is suppressed. Can.

In the photosensitive member of the present embodiment, it is preferable that the surface of the photosensitive member be positively charged to form an image. In the photosensitive member of the present embodiment in which the charge potential Vn ₀ under negative charge measurement conditions is −550 V or more and less than 0 V, generation of an image ghost in the formed image is achieved by setting the charge potential at the time of image formation to a positive value. Can be suitably suppressed.

In order to suppress the generation of an image ghost in a formed image, the charging potential Vn _{0 under} the negative charge measurement conditions is preferably −550 V or more and −400 V or less.

The charging potential Vn _{0 under} negative charge measurement conditions is measured using the first measuring device. Referring to FIG. 3, illustrating a method of measuring the charge potential Vn ₀ in negative charging measurement conditions. FIG. 3 shows the configuration of the first measuring device 210. The first measuring device 210 includes a corotron charger 200 and a charge potential measuring device 212. The first measuring device 210 may further include a static eliminator 214.

  The corotron charger 200 charges the surface of the photosensitive member 100. The corotron charger 200 comprises a wire 202, a casing 204, a power supply 206 and an ammeter 208.

  The corotron charger 200 charges the photosensitive member 100 by applying a current of -5 μA to the wire 202. The current flowing through the wire 202 is a direct current. The wire 202 is connected to one end of the ammeter 208.

  The casing 204 accommodates the wire 202. The casing 204 is grounded.

  The power supply 206 causes a current to flow through the wire 202. One end of the power supply 206 is grounded. The other end of the power supply 206 is connected to the other end of the ammeter 208.

  The ammeter 208 measures a current value Ic flowing from the power supply 206 to the wire 202. The current value Ic of the corotron charger 200 is the value of the current flowing from the power supply 206 of the corotron charger 200 to the wire 202. The current value Ic of the corotron charger 200 is set to -5 μA.

  The charge potential measuring device 212 measures the surface potential of the charged photosensitive member 100. The charge removing device 214 removes the charge on the surface of the photosensitive member 100.

  The photosensitive member 100 can be rotatably set in the first measuring device 210. The corotron charger 200, the charge potential measuring device 212, and the static eliminator 214 are disposed around the photosensitive member 100. The corotron charger 200, the charge potential measuring device 212, and the static eliminator 214 are arranged in the order described from the upstream side of the rotational direction of the photosensitive member 100.

The charging potential Vn _{0 under} negative charge measurement conditions is measured by performing the following steps (a) and (b) using the first measuring device 210.
(A) A charging step of charging the photosensitive member 100 by supplying a current of -5 μA to the wire 202 provided in the corotron charger 200 of the first measuring device 210, and (b) the charging potential measuring device 212 corresponds to the photosensitive member 100. charging potential measuring step of measuring the charge potential Vn _0.

Above with reference to FIG. 3, it described a method for measuring the charge potential Vn ₀ in negative charging measurement conditions. The method of measuring the charge potential Vn _{0 under} the negative charge measurement conditions will be described in detail in the Examples.

(Potential difference Vp _LA- Vp _{LC under} positive charge measurement conditions)
Positive rotation, exposure and transfer are performed on each circumference while rotating the photosensitive drum three times, the charging potential on each circumference is the same positive value, the exposure amount is the same, and the transfer current value is the same A difference Vp _LA between the surface potential Vp _LA of the exposed area of the photosensitive member after exposure in the first cycle and before transfer, and the surface potential Vp _LC of the exposed area of the photosensitive member after exposure and before transfer in the third cycle -Vp _LC (Hereinafter, it may be described as electric potential difference Vp _LA -Vp _LC in positive charge measurement conditions.) Is 0 V or more. When the potential difference Vp _LA −Vp _{LC under the} positive charge measurement condition is 0 V or more, the generation of the exposure memory can be suppressed, and the generation of the image ghost in the formed image can be suppressed. The units of the surface potential Vp _LA , the surface potential Vp _LC and the potential difference Vp _LA -Vp _LC are all V (volts).

Since the photosensitive member is positively charged and then exposed, the surface potential Vp _LA of the exposed area of the photosensitive member after exposure in the first cycle and before transfer, and after exposure in the third cycle and before transfer The surface potential Vp _LC of the exposed area of the photosensitive member has a positive value. That is, the inequalities “Vp _LA > 0” and “Vp _LC > 0” are satisfied. When the potential difference Vp _LA -Vp _{LC under} positive charge measurement conditions is 0 V or more, the surface potential Vp _LA of the exposed area of the photosensitive member after exposure in the first cycle and before transfer is after exposure in the third cycle and transfer The surface potential Vp _LC of the exposure area of the previous photoreceptor is equal to or larger than the surface potential Vp _LC . That is, the inequality "Vp _LA V Vp _LC " is satisfied.

In order to suppress the generation of an image ghost in a formed image, the potential difference Vp _LA -Vp _{LC under} positive charge measurement conditions is preferably 0 V or more and 20 V or less, and more preferably 0 V or more and 15 V or less.

The potential difference Vp _LA -Vp _{LC under} positive charge measurement conditions is measured using a second measuring device. The second measuring device 300 will be described below with reference to FIG. FIG. 4 shows an example of the configuration of the second measurement apparatus 300. The second measurement apparatus 300 includes a charging unit 302, an exposure unit 304, a potential measurement unit 306, and a transfer unit 308. The charging unit 302 charges the surface 100 a of the photosensitive member 100. The exposure unit 304 exposes the surface 100 a of the photosensitive member 100. The potential measurement unit 306 measures the surface potential (for example, surface potentials Vp _L1 , Vp _LA and Vp _LC ) of the exposed photosensitive member 100. When a transfer current flows to the transfer unit 308, the transfer unit 308 applies a transfer bias to the photosensitive member 100. The transfer current value of the transfer current flowing to the transfer unit 308 is, for example, -20 μA or more and -5 μA or less.

  The photosensitive member 100 can be rotatably set in the second measuring device 300. The charging unit 302, the exposure unit 304, the potential measurement unit 306, and the transfer unit 308 are disposed around the photosensitive member 100. The charging unit 302, the exposure unit 304, the potential measurement unit 306, and the transfer unit 308 are arranged in the order described from the upstream side of the rotational direction of the photosensitive member 100.

The method of measuring the potential difference Vp _LA -Vp _LC under positive charge measurement conditions will be described with further reference to FIG. 5. The potential difference Vp _LA -Vp _{LC under the} positive charge measurement conditions is measured by performing the following steps (A) to (M) using the second measuring device 300 while rotating the photosensitive member 100 three times.
Step (A) An exposure amount setting step of setting the exposure amount of the exposure unit 304 so that the surface potential Vp _L1 of the exposure region of the photosensitive member 100 becomes +150 V when the surface of the photosensitive member 100 charged to +750 V is exposed. Step S402),
Step (B): a first positive charging step (step S404) in which the charging unit 302 charges the surface of the photosensitive member 100 to +750 V in the first cycle of the photosensitive member 100;
Step (C) A first exposure step (step S406) in which the exposure unit 304 exposes the light having the exposure amount set in the exposure amount setting step on the surface of the photosensitive member 100 in the first cycle.
Step (D) A first potential measurement step (step S408) in which the potential measurement unit 306 measures the surface potential Vp _LA of the exposed area of the photosensitive member 100 in the first cycle.
Step (E) In the first cycle, the transfer unit 308 applies a transfer bias to the photosensitive member 100 by supplying a transfer current to the transfer unit 308 (Step S410). A second positive charging step (step S412) in which the charging unit 302 charges the surface of the photosensitive member 100 to +750 V in the second cycle;
Step (G) a second exposure step (step S414) in which the exposure unit 304 exposes the light having the exposure amount set in the exposure amount setting step on the surface of the photosensitive member 100 in the second cycle.
Step (H) A second transfer step in which the transfer unit 308 applies a transfer bias to the photosensitive member 100 by supplying a transfer current having the same value as that in the first transfer step to the transfer unit 308 in the second cycle (step S416) ,
Step (I) A third positive charging step (Step S418) in which the charging unit 302 charges the surface of the photosensitive member 100 to +750 V in the third cycle of the photosensitive member 100.
Step (J) Third exposure step (step S420) in which the exposure unit 304 exposes the light having the exposure amount set in the exposure amount setting step on the surface of the photosensitive member 100 in the third cycle.
Step (K) A third potential measurement step (step S422) in which the potential measurement unit 306 measures the surface potential Vp _LC of the exposed area of the photosensitive member 100 in the third cycle.
Step (L) A third transfer step in which the transfer unit 308 applies a transfer bias to the photosensitive member 100 by supplying a transfer current having the same value as in the first transfer step to the transfer unit 308 in the third cycle (step S424) And Step (M) Calculate the potential difference Vp _LA −Vp _LC from the surface potential Vp _LA of the exposed area of the photosensitive member 100 in the first round and the surface potential Vp _LC of the exposed area of the photosensitive body 100 in the third round. Calculation step (step S426).

Above with reference to FIGS. 4 and 5, has been described a method for measuring the potential difference Vp _LA -Vp _LC in the positive charge measurement conditions. The method of measuring the potential difference Vp _LA -Vp _LC under positive charge measurement conditions will be described in detail in the Examples.

(Electron transport agent)
The photosensitive layer contains two or more electron transport agents. The photosensitive layer can contain, for example, two electron transport agents. Examples of the electron transfer agent include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds Compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride or dibromomaleic anhydride can be mentioned. Examples of the quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds or dinitroanthraquinone compounds.

  Preferred examples of the electron transfer agent are compounds represented by the following general formulas (1), (2), (3), (4), (5), (6) or (7). Hereinafter, the compounds represented by the general formulas (1), (2), (3), (4), (5), (6) and (7) are compounds (1), (2) and (3) respectively. It may be described as (4), (5), (6) and (7).

  The compound (1) will be described below. The compound (1) is a quinone derivative represented by the general formula (1).

In General Formula (1), at least one of R ¹ , R ² and R ³ represents an alkyl group having 4 to 10 carbon atoms or an alkyl group having 2 to 5 carbon atoms. The alkyl group having 2 to 5 carbon atoms has an aryl group having 6 to 14 carbon atoms. The remainder of R ¹ , R ² and R ³ represents an alkyl group having 1 to 3 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cycloalkyl group having 3 to 10 carbon atoms. At least two of R ¹ , R ² and R ³ may be bonded to each other to represent a ring. At least one of R ⁴ , R ⁵ and R ⁶ is an alkyl group having 2 to 5 carbon atoms having an alkyl group having 4 to 10 carbon atoms or an aryl group having 6 to 14 carbon atoms. Represent. The alkyl group having 2 to 5 carbon atoms has an aryl group having 6 to 14 carbon atoms. The remainder of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 1 to 3 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cycloalkyl group having 3 to 10 carbon atoms. At least two of R ⁴ , R ⁵ and R ⁶ may be linked to each other to represent a ring.

In the general formula (1), the alkyl group having 4 to 10 carbon atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is an alkyl group having 4 to 6 carbon atoms. Preferably, n-butyl, isohexyl or n-hexyl is more preferable. At least two of R ¹ , R ² and R ³ may be bonded to each other to represent a ring. At least two of R ⁴ , R ⁵ and R ⁶ may be linked to each other to represent a ring. As such a ring, for example, a cycloalkylidene group or a cyclic hydrocarbon group can be mentioned. The cycloalkylidene group includes, for example, a cycloalkylidene group having 5 to 7 carbon atoms (more specifically, a cyclohexylidene group etc.). As a cyclic hydrocarbon group, an adamantyl group is mentioned, for example.

In the general formula (1), as an alkyl group having 2 to 5 carbon atoms, having an aryl group having 6 to 14 carbon atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ Is preferably an alkyl group having 2 to 5 carbon atoms having a phenyl group, more preferably a phenylethyl group.

In the general formula (1), the ^{R 1, R 2, R 3} , R 4, R 5 and 3 an alkyl group having a carbon atom number of 1 or more represented by R ^6, a methyl group is preferable.

In the general formula (1), R ^1, examples of ^{R 2, R 3, R 4} , R 5 and 6 or more carbon atoms represented by R ⁶ 14 The following aryl group, a phenyl group is preferable.

In order to suppress the occurrence of an image ghost in a formed image, a compound in which R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ^{6 in} the general formula (1) are as follows is preferable. At least one of R ¹ , R ² and R ³ represents an alkyl group having 2 to 5 carbon atoms having an aryl group having 6 to 14 carbon atoms. The remainder of R ¹ , R ² and R ³ represents an alkyl group having 1 to 3 carbon atoms. At least one of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 2 to 5 carbon atoms having an aryl group having 6 to 14 carbon atoms. The remainder of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 1 to 3 carbon atoms.

In order to suppress the occurrence of an image ghost in a formed image, a compound in which R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ in the general formula (1) are as follows is more preferable. In General Formula (1), ^one of R ¹ , R ² and R ³ represents an alkyl group having a phenyl group and having 2 or more and 3 or less carbon atoms. The remainder of R ¹ , R ² and R ³ represents a methyl group. At least two of R ¹ , R ² and R ³ are linked together and do not represent a ring. One of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 2 to 3 carbon atoms having a phenyl group. The remainder of R ⁴ , R ⁵ and R ⁶ represents a methyl group. At least two of R ⁴ , R ⁵ and R ⁶ are linked to each other and do not represent a ring.

In another preferred embodiment, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ in the general formula (1) are as follows. In General Formula (1), at least one of R ¹ , R ² and R ³ represents an alkyl group having 4 to 6 carbon atoms or an alkyl group having 2 to 5 carbon atoms having a phenyl group. . The remainder of R ¹ , R ² and R ³ represents an alkyl group having 1 to 3 carbon atoms. At least one of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 4 to 6 carbon atoms or an alkyl group having 2 to 5 carbon atoms having a phenyl group. The remainder of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 1 to 3 carbon atoms.

In another preferred embodiment, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ in the general formula (1) are as follows. In General Formula (1), one or two of R ¹ , R ² and R ³ are each an alkyl group having 2 to 3 carbon atoms having a phenyl group or an alkyl group having 5 to 7 carbon atoms. Represents The remainder of R ¹ , R ² and R ³ represents a methyl group. At least two of R ¹ , R ² and R ³ are linked together and do not represent a ring. One or two of R ⁴ , R ⁵ and R ⁶ represent a phenyl group-containing alkyl group having 2 to 3 carbon atoms or an alkyl group having 5 to 7 carbon atoms. The remainder of R ⁴ , R ⁵ and R ⁶ represents a methyl group. At least two of R ⁴ , R ⁵ and R ⁶ are linked to each other and do not represent a ring.

In general formula (1), it is preferable that R ¹ and R ⁴ represent the same group, R ² and R ⁵ represent the same group, and R ³ and R ⁶ represent the same group.

  Preferred examples of the compound (1) include compounds represented by chemical formulas (1-1) to (1-7) (hereinafter, may be described as compounds (1-1) to (1-7)) Can be mentioned. The compound (1-1) is more preferable as the compound (1) in order to suppress the occurrence of an image ghost in the formed image.

  Compound (1) can be, for example, according to or in accordance with the reactions represented by reaction formulas (R-1) to (R-3) (hereinafter sometimes referred to as (R-1) to (R-3)) Manufactured by the method.

In reaction (R-1), R ^1, R ² and R ³ are the same meanings as R ^1, R ² and R ³ in the general formula (1).

  In the reaction (R-1), 1 equivalent of the compound (1-naphthol) represented by the chemical formula (A) and the compound (alcohol compound) represented by the general formula (B) (hereinafter referred to as the alcohol compound (B) And 1 equivalent) are reacted in the presence of concentrated sulfuric acid in a solvent, and may be described as a compound represented by the general formula (C) as an intermediate (hereinafter referred to as naphthol derivative (C) ) Get 1 equivalent. In the reaction (R-1), it is preferable to add 1 mol or more and 2.5 mol or less of the alcohol compound (B) to 1 mol of 1-naphthol. If one mole or more of the alcohol compound (B) is added to one mole of 1-naphthol, the yield of the naphthol derivative (C) is easily improved. On the other hand, when 2.5 mol or less alcohol compound (B) is added with respect to 1 mol 1-naphthol, unreacted alcohol compound (B) hardly remains after reaction (R-1), and compound (1) Purification of It is preferable that the reaction temperature of reaction (R-1) is room temperature (for example, 25 degreeC). The reaction time of the reaction (R-1) is preferably 1 hour or more and 10 hours or less. The reaction (R-1) can be carried out in a solvent. Examples of the solvent include organic acid aqueous solutions (more specifically, acetic acid etc.).

  More specifically, in the reaction (R-1), 1-naphthol is reacted with an alcohol compound (B). After the reaction, ion-exchanged water is added to the reaction solution to extract it into the organic layer. As an organic solvent contained in an organic layer, chloroform or ethyl acetate is mentioned, for example. The organic layer is added with an alkaline aqueous solution, and the organic layer is washed and neutralized. Examples of the alkali include hydroxides of alkali metals (more specifically, sodium hydroxide or potassium hydroxide and the like) or hydroxides of alkaline earth metals (more specifically, calcium hydroxide and the like). It can be mentioned.

In reaction (R-2), R ^4, R ⁵ and R ⁶ are the same meanings as R ^4, R ⁵ and R ⁶ in the general formula (1).

  In the reaction (R-2), 1 equivalent of a compound (1-naphthol) represented by the chemical formula (A) and a compound (alcohol compound) represented by the general formula (D) (hereinafter referred to as an alcohol compound (D) Compound (1) may be reacted in the presence of concentrated sulfuric acid in a solvent to describe the compound represented by the general formula (E) as an intermediate (hereinafter referred to as naphthol derivative (E) ) Get 1 equivalent. The reaction (R-2) is the same reaction as the reaction (R-1) except that the alcohol compound (B) is changed to the alcohol compound (D).

In the reaction (R-3), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ^{5 in the} general formula (1) It has the same meaning as R ^6.

  In reaction (R-3), one equivalent of naphthol derivative (C) and one equivalent of naphthol derivative (E) are reacted in the presence of an oxidizing agent to obtain one equivalent of compound (1). In the reaction (R-3), it is preferable to add 1 mol of an oxidizing agent to 1 mol of the naphthol derivative (C) and 1 mol of the naphthol derivative (E). As an oxidizing agent, chloranil, potassium permanganate or silver oxide is mentioned, for example. It is preferable that the reaction temperature of reaction (R-3) is room temperature (for example, 25 degreeC). The reaction time of the reaction (R-3) is preferably 1 hour or more and 10 hours or less. Examples of the solvent include chloroform and dichloromethane.

  The production of compound (1) may include other steps as necessary. Other steps include, for example, purification steps. Examples of the purification method include known methods (more specifically, filtration, chromatography, crystallization, etc.).

  Next, compounds (2) to (7) will be described.

In the general formulas (2) and (4) to (7), R ²¹ , R ²² , R ²³ , R ²⁴ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² , R ⁶¹ , R ⁶² , R ⁶³ R ⁶⁴ , R ⁷¹ , R ⁷² and R ⁷³ each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, carbon It represents an alkoxy group having 1 to 6 atoms, or an aryl group having 6 to 14 carbon atoms. The aryl group having 6 to 14 carbon atoms may have at least one alkyl group having 1 to 6 carbon atoms. In General Formula (3), R ³¹ and R ³² each represent an alkyl group having 1 to 6 carbon atoms. In the general formula (4), W is, -CO-O-or -CO-O-CH ₂ - represents a.

In the general formulas (2) and (4) to (7), R ²¹ , R ²² , R ²³ , R ²⁴ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² , R ⁶¹ , R ⁶² , R ⁶³ The halogen atom represented by R ⁶⁴ , R ⁷¹ , R ⁷² and R ⁷³ is preferably a chlorine atom (chloro group).

R ²¹ , R ²² , R ²³ , R ²⁴ , R ³¹ , R ³² , R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² , R ⁶¹ , R ⁶² in the general formulas (2) to (7) As an alkyl group having 1 to 6 carbon atoms represented by R ⁶³ , R ⁶⁴ , R ⁷¹ , R ⁷² and R ⁷³ , an alkyl group having 1 to 5 carbon atoms is preferable, and a methyl group, a tert-butyl group or More preferred is a 1,1-dimethylpropyl group.

In the general formulas (2) and (4) to (7), R ²¹ , R ²² , R ²³ , R ²⁴ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² , R ⁶¹ , R ⁶² , R ⁶³ Examples of the alkenyl group having 2 to 6 carbon atoms represented by R ⁶⁴ , R ⁷¹ , R ⁷² and R ⁷³ include alkenyl groups having 2 to 4 carbon atoms.

In the general formulas (2) and (4) to (7), R ²¹ , R ²² , R ²³ , R ²⁴ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² , R ⁶¹ , R ⁶² , R ⁶³ Examples of the alkoxy group having 1 to 6 carbon atoms represented by R ⁶⁴ , R ⁷¹ , R ⁷² and R ⁷³ include an alkoxy group having 1 to 3 carbon atoms.

In the general formulas (2) and (4) to (7), R ²¹ , R ²² , R ²³ , R ²⁴ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² , R ⁶¹ , R ⁶² , R ⁶³ As the aryl group having 6 to 14 carbon atoms which R ⁶⁴ , R ⁷¹ , R ⁷² and R ⁷³ represent, a phenyl group is preferable. The aryl group having 6 to 14 carbon atoms may have at least one (preferably 1 or 2) alkyl group having 1 to 6 carbon atoms. As a C1-C6 alkyl group which a C6-C14 aryl group has, a C1-C3 alkyl group is preferable and a methyl group or an ethyl group is more preferable. As an aryl group having 6 to 14 carbon atoms having at least one alkyl group having 1 to 6 carbon atoms, a 2-ethyl-6-methylphenyl group is preferable.

In the general formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ each preferably represent an alkyl group having 1 to 6 carbon atoms, and represent an alkyl group having 1 to 4 carbon atoms. Is more preferable, and it is further preferable to represent a methyl group or a tert-butyl group.

In general formula (3), R ³¹ and R ³² each preferably represent an alkyl group having 1 to 5 carbon atoms, and more preferably a 1,1-dimethylpropyl group.

In the general formula (4), R ⁴¹ , R ⁴² and R ⁴³ preferably each independently represent a hydrogen atom or an aryl group having 6 to 14 carbon atoms. Each of R ⁴¹ and R ⁴² preferably represents an aryl group having 6 to 14 carbon atoms, and more preferably a phenyl group. R ⁴³ preferably represents a hydrogen atom. W is, -CO-O-CH ₂ - preferably represents a. In formula (4), R ⁴¹ , R ⁴² and R ⁴³ each independently represent a hydrogen atom or an aryl group having 6 to 14 carbon atoms, and W represents -CO-O-CH _2- Is preferred.

In the general formula (5), each of R ⁵¹ and R ⁵² independently has an aryl group having 6 to 14 carbon atoms which may have one or two alkyl groups having 1 to 6 carbon atoms. Is preferably represented, more preferably a 2-ethyl-6-methylphenyl group.

In the general formula (6), R ⁶¹ , R ⁶² , R ⁶³ and R ⁶⁴ each preferably represent an alkyl group having 1 to 6 carbon atoms, and represent an alkyl group having 1 to 4 carbon atoms. Is more preferable, and it is further preferable to represent a methyl group or a tert-butyl group.

In the general formula (7), R ⁷¹ and R ⁷² each preferably represent an alkyl group having 1 to 6 carbon atoms, more preferably an isopropyl group or a tert-butyl group, and a tert-butyl group It is particularly preferred to represent. R ⁷³ in the general formula (7) preferably represents a halogen atom, and more preferably represents a chlorine atom (chloro group). In the general formula (7), R ⁷¹ and R ⁷² each preferably represent an alkyl group having 1 to 6 carbon atoms, and R ⁷³ preferably represents a halogen atom.

  A preferred example of the compound (2) is a compound represented by the chemical formula (2-1). Preferred examples of the compound (3) are compounds represented by chemical formula (3-1). Preferred examples of the compound (4) are compounds represented by chemical formula (4-1). A preferred example of the compound (5) is a compound represented by the chemical formula (5-1). Preferred examples of the compound (6) are compounds represented by chemical formula (6-1). A preferred example of the compound (7) is a compound represented by the chemical formula (7-1). Each of the compounds represented by the chemical formulas (2-1), (3-1), (4-1), (5-1), (6-1) and (7-1) is a compound (2-1) , (3-1), (4-1), (5-1), (6-1) and (7-1).

  Electron transport agents are 2 or more types. The two or more electron transfer agents preferably include at least a first electron transfer agent and a second electron transfer agent. When the photosensitive layer contains two or more electron transport agents, the solubility of the electron transport agent in the solvent for forming the photosensitive layer can be improved. Thereby, many electron transfer agents can be dissolved in the solvent for forming the photosensitive layer, and the mass of the electron transfer agent in the photosensitive layer can be increased. As a result, the generation of the exposure memory can be suppressed, and the generation of the image ghost in the formed image can be suppressed. The two or more electron transport agents can be, for example, two electron transport agents. When two types of electron transfer agents are contained in the photosensitive layer, the two types of electron transfer agents include a first electron transfer agent and a second electron transfer agent.

The electron transfer agent is preferably two or more of the compounds (1) to (7). In order to adjust the charge potential Vn _{0 under} negative charge measurement conditions and the potential difference Vp _LA -Vp _LC under positive charge measurement conditions to desired values and to suppress the generation of image ghosts in the formed image, the first electron transfer agent is a compound (1), and the second electron transfer agent is preferably the compound (2), (3), (4), (5), (6) or (7). For the same reason, it is more preferable that the first electron transfer agent is the compound (1) and the second electron transfer agent is the compound (2).

In order to adjust the charge potential Vn _{0 under} negative charge measurement conditions and the potential difference Vp _LA -Vp _LC under positive charge measurement conditions to desired values and to suppress the generation of image ghosts in the formed image, the first electron transfer agent is a compound (1-1), and the second electron transfer agent is a compound (2-1), (3-1), (4-1), (5-1), (6-1) or (7-1) Is preferred. For the same reason, it is more preferable that the first electron transfer agent is the compound (1-1) and the second electron transfer agent is the compound (2-1).

  It is preferable that content of 1 type of electron transfer agents is 20 mass parts or more and 30 mass parts or less with respect to 100 mass parts of binder resin contained in a photosensitive layer. When 2 or more types of electron transfer agents are contained, the total content of 2 or more types of electron transfer agents is 50 parts by mass or more and 75 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the photosensitive layer. It is preferable, and it is more preferable that it is 50 to 60 mass parts.

The ratio (M _ETM / M _L ) of the mass (M _ETM ) of the electron transfer agent to the mass (M _L ) of the photosensitive layer is preferably 0.25 or more and 0.28 or less. When the ratio (M _ETM / M _L ) is 0.25 or more and 0.28 or less, the generation of an image ghost in a formed image can be further suppressed.

(Hole transport agent)
The photosensitive layer contains, for example, a hole transport agent. Examples of the hole transport agent include triphenylamine derivatives, diamine derivatives (more specifically, N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ′, N′-tetraphenyl Phenylenediamine derivative, N, N, N ', N'-tetraphenyl naphthylene diamine derivative, N, N, N', N'-tetraphenyl phenanthrylene diamine derivative or di (aminophenyl ethenyl) benzene derivative etc.) , Oxadiazole compounds (more specifically, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole etc.), styryl compounds (more specifically, 9- (4-diethylaminostyryl) anthracene etc., carbazole type compounds (more specifically, polyvinyl carbazole etc.), organic polysilane compounds, pyrazoline type Compound (more specifically, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline etc.), hydrazone compound, indole compound, oxazole compound, isoxazole compound, thiazole compound, thiadiazole compound And imidazole compounds, pyrazole compounds and triazole compounds. The hole transport agent may be used alone or in combination of two or more.

  Preferred examples of the hole transport agent are compounds represented by the following general formulas (10), (11), (12), (13), (14) or (15). Hereinafter, each of the compounds represented by the general formulas (10), (11), (12), (13), (14) and (15) can be treated with the compounds (10), (11), (12), ( 13) It may be described as (14) and (15).

  The compound (10) will be described below.

In general formula (10), each of R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ and R ¹⁰⁵ independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or carbon It represents an aryl group having 6 to 14 atoms. The aryl group having 6 to 14 carbon atoms may have an alkyl group having 1 to 6 carbon atoms. Each of b ₁ , b ₂ and b ₃ independently represents an integer of 0 or more and 5 or less.

In the general formula (10), R ¹⁰¹ , R ¹⁰² and R ¹⁰³ each preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably represent an alkyl group having 1 to 3 carbon atoms. More preferably, it represents a methyl group. R ¹⁰⁴ and R ¹⁰⁵ 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 It is more preferable to represent a phenyl group which may have a substituent, more preferably a methylphenyl group or a phenyl group, and particularly preferably a p-methylphenyl group or a phenyl group.

In general formula (10), b ₁ , b ₂ and b ₃ each independently represent an integer of 0 or more and 5 or less. If b ₁ represents an integer of 2 to 5, a plurality of R ¹⁰¹ attached to the same phenyl group may be the same or different from each other. If b ₂ represents an integer of 2 to 5, a plurality of R ¹⁰² attached to the same phenyl group may be the same or different from each other. If b ₃ represents an integer of 2 to 5, a plurality of R ¹⁰³ attached to the same phenyl group may be the same or different from each other. Each of b ₁ , b ₂ and b ₃ preferably represents 0 or 1.

The bonding position of R ^{101 to} R ¹⁰³ is not particularly limited. R ^{101 to} R ¹⁰³ may be bonded (positioned) to any of the ortho, meta and para positions of the phenyl group. Each of R ^{101 to} R ¹⁰³ is preferably bonded to the para position of a phenyl group.

In formula (10), R ¹⁰¹ , R ¹⁰² and R ¹⁰³ each represent an alkyl group having 1 to 6 carbon atoms, and R ¹⁰⁴ and R ¹⁰⁵ each represent an alkyl group having 1 to 6 carbon atoms. The aryl group preferably has 6 or more and 14 or less carbon atoms, and preferably b ₁ , b ₂ and b ₃ each independently represent 0 or 1.

  Preferred examples of the compound (10) include compounds represented by the following chemical formulas (10-1), (10-2) or (10-3) (hereinafter, compounds (10-1) and (10-2) respectively) And (10-3)).

  Next, the compound (11) will be described.

In the general formula (11), each of R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ and R ¹¹⁶ independently represents an alkyl group having 1 to 6 carbon atoms and an alkoxy having 1 to 6 carbon atoms A group or an aryl group having 6 to 14 carbon atoms. Each of d ₁ , d ₂ , d ₃ and d ₄ independently represents an integer of 0 or more and 5 or less. d ₅ and d ₆ each independently represent an integer of 0 or more and 4 or less.

In the general formula (11), R ^{111 to} R ¹¹⁶ each preferably represent an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and a methyl group Particularly preferably, it represents an ethyl group.

In the general formula (11), when d ₁ represents an integer of 2 or more and 5 or less, plural R ¹¹¹ bonded to the same phenyl group may be the same or different. When d ₂ represents an integer of 2 or more and 5 or less, plural R ¹¹² bonded to the same phenyl group may be the same or different. If d ₃ represents an integer of 2 to 5, a plurality of R ¹¹³ attached to the same phenyl group may be the same or different from each other. When d ₄ represents an integer of 2 or more and 5 or less, a plurality of R ¹¹⁴ bonded to the same phenyl group may be the same as or different from each other. If d ₅ represents an integer of 2 to 4, a plurality of R ¹¹⁴ to bind to the same phenylene group may be the same or different from each other. When d ₆ represents an integer of 2 or more and 4 or less, a plurality of R ¹¹⁶ bonded to the same phenylene group may be the same or different.

The bonding position of R ^{111 to} R ¹¹⁴ is not particularly limited. R ^{111 to} R ¹¹⁴ may be bonded (positioned) at any of the ortho, meta and para positions of the phenyl group. R ¹¹³ and R ¹¹⁴ are each preferably bonded to the ortho position of the phenyl group. The bonding position of R ¹¹⁵ and R ¹¹⁶ is not particularly limited. R ¹¹⁵ and R ¹¹⁶ may be bonded (positioned) in either the ortho position or the meta position with respect to the nitrogen atom to which the phenylene group is bonded.

Preferably, d ₁ , d ₂ , d ₃ and d ₄ each independently represent an integer of 0 or more and 2 or less. Preferably, d ₅ and d ₆ each represent 0.

In the general formula (11), R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ and R ¹¹⁶ each represent an alkyl group having 1 to 6 carbon atoms, d ₁ , d ₂ , d ₃ and d It is preferable that ₄ each independently represent an integer of 0 or more and 2 or less, and d ₅ and d ₆ each represent 0.

  The preferable example of a compound (11) is a compound (Hereinafter, it may describe as a compound (11-1).) Represented by following Chemical formula (11-1).

  Next, the compound (12) will be described.

In the general formula (12), each of R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ and R ¹²⁶ independently represents an alkyl group having 1 to 6 carbon atoms and an alkoxy having 1 to 6 carbon atoms And an aryl group having 6 to 14 carbon atoms or an alkenyl group having 2 to 6 carbon atoms. Each of e ₁ , e ₂ , e ₃ and e ₄ independently represents an integer of 0 or more and 5 or less. Each of e ₅ and e ₆ independently represents an integer of 0 or more and 4 or less.

In general formula (12), e ₁ , e ₂ , e ₃ and e ₄ each independently represent an integer of 0 or more and 5 or less. When e ₁ represents an integer of 2 or more and 5 or less, a plurality of R ¹²¹ bonded to the same phenyl group may be the same as or different from each other. When e ₂ represents an integer of 2 or more and 5 or less, plural R ¹²² bonded to the same phenyl group may be the same as or different from each other. When e ₃ represents an integer of 2 or more and 5 or less, plural R ¹²³ bonded to the same phenyl group may be the same or different. When e ₄ represents an integer of 2 or more and 5 or less, plural R ¹²⁴ bonded to the same phenyl group may be the same as or different from each other. Preferably, e ₁ , e ₂ , e ₃ and e ₄ each independently represent an integer of 0 or more and 2 or less. More preferably, one of e ₁ and e ₂ represents 2 and the other represents 0 or 1. More preferably, one of e ₃ and e ₄ represents 2 and the other represents 0 or 1.

The bonding position of R ^{121 to} R ¹²⁴ is not particularly limited. R ^{121 to} R ¹²⁴ may be bonded (positioned) at any of the ortho position, meta position and para position of the phenyl group. Each of R ^{121 to} R ¹²⁴ is preferably bonded to the ortho or para position of the phenyl group.

In the general formula (12), e ₅ and e ₆ each independently represent an integer of 0 to 4. When e ₅ represents an integer of 2 or more and 4 or less, a plurality of R ¹²⁵ bonded to the same phenylene group may be the same as or different from each other. When e ₆ represents an integer of 2 or more and 4 or less, plural R ¹²⁶ bonded to the same phenylene group may be the same or different. Each of e ₅ and e ₆ preferably represents 0.

The bonding position of R ¹²⁵ and R ¹²⁶ is not particularly limited. Each of R ¹²⁵ and R ¹²⁶ may be bonded (positioned) to either the ortho position or the meta position with respect to the nitrogen atom to which the phenylene group is bonded.

In the general formula (12), R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ and R ¹²⁶ each preferably represent an alkyl group having 1 to 6 carbon atoms, and represent a methyl group or an ethyl group. Is more preferred. Preferably, e ₁ , e ₂ , e ₃ and e ₄ each independently represent an integer of 0 or more and 2 or less. Each of e ₅ and e ₆ preferably represents 0.

In the general formula (12), R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ and R ¹²⁶ each represent an alkyl group having 1 to 6 carbon atoms, and e ₁ , e ₂ , e ₃ and e It is preferable that ₄ represents each independently an integer of 0 or more and 2 or less, and e ₅ and e ₆ each represent 0.

  Preferred examples of the compound (12) may be described as compounds represented by the following chemical formula (12-1) or (12-2) (hereinafter referred to as the compounds (12-1) and (12-2) respectively ).

  Next, the compound (13) will be described.

In the general formula (13), each of R ¹³¹ , R ¹³² , R ¹³³ and R ¹³⁴ independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 carbon atoms 14 or more represents an aryl group. f ₁ , f ₂ and f ₃ each independently represent an integer of 0 or more and 5 or less. f ₄ represents 0 or 1;

In the general formula (13), R ^{131 to} R ¹³³ each preferably represent an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and a methyl group It is particularly preferred to represent R ¹³⁴ preferably represents an aryl group having 6 to 14 carbon atoms, and more preferably a phenyl group.

In the general formula (13), when f ₁ represents an integer of 2 or more and 5 or less, a plurality of R ¹³¹ bonded to the same phenyl group may be the same or different. When f ₂ represents an integer of 2 or more and 5 or less, a plurality of R ¹³² bonded to the same phenyl group may be the same as or different from each other. When f ₃ represents an integer of 2 or more and 5 or less, a plurality of R ¹³³ bonded to the same phenyl group may be the same as or different from each other. f ₁ preferably represents 0 or 1, and more preferably 1. f ₂ preferably represents 1 or 2, and more preferably 1. f ₃ preferably represents 0 or 1, and more preferably 0.

The bonding position of R ^{131 to} R ¹³³ is not particularly limited. R ^{131 to} R ¹³³ may be bonded (positioned) to any of the ortho position, meta position and para position of the phenyl group. R ¹³¹ is preferably bonded to the para position of the phenyl group. R ¹³² is preferably bonded to the para position of the phenyl group.

When f ₂ represents 2 and two R ¹³² are bonded at adjacent bonding positions (eg, ortho position and meta position, or meta position and para position) of a phenyl group, two R ¹³² are bonded to each other May represent a ring. As a ring formed by bonding two adjacent R ¹³² to each other, for example, a cycloalkane having 5 to 7 carbon atoms can be mentioned. When two adjacent R ¹³² bond together to form a cycloalkane having 5 to 7 carbon atoms, the cycloalkane having 5 to 7 carbon atoms is a phenyl group to which 2 R ¹³² bond. And form a bicyclic fused ring group. In this case, the condensation site of a cycloalkane having 5 to 7 carbon atoms and a phenyl group may contain a double bond. It is preferred that two adjacent R ¹³² bond together to form a cycloalkane having 5 to 7 carbon atoms, and more preferably cyclohexane.

  Preferred examples of the compound (13) may be described as compounds represented by the following chemical formula (13-1) or (13-2) (hereinafter referred to as the compounds (13-1) and (13-2) respectively ).

  Next, the compound (14) will be described.

In the general formula (14), each of R ¹⁴¹ , R ¹⁴² , R ¹⁴³ and R ¹⁴⁴ independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. g ₁ , g ₂ , g ₃ and g ₄ each independently represent an integer of 0 or more and 5 or less.

If g ₁ represents an integer of 2 to 5, a plurality of R ¹⁴¹ may be the same or different from each other. If g ₂ represents an integer of 2 to 5, a plurality of R ¹⁴² may be the same or different from each other. When g ₃ represents an integer of 2 or more and 5 or less, the plurality of R ¹⁴³ may be the same as or different from each other. When g ₄ represents an integer of 2 to 5, the plurality of R ¹⁴⁴ may be the same as or different from each other.

In the general formula (14), R ¹⁴¹ , R ¹⁴² , R ¹⁴³ and R ¹⁴⁴ each independently preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group. Preferably, one of g ₁ and g ₄ represents 1 and the other represents 0. Preferably, one of g ₂ and g ₃ represents 1 and the other represents 0.

  The preferable example of a compound (14) is a compound (Hereinafter, it may describe as a compound (14-1).) Represented by following Chemical formula (14-1).

  Next, the compound (15) will be described.

In general formula (15), each of R ¹⁵¹ , R ¹⁵² and R ¹⁵³ independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 to 14 carbon atoms. Represents an aryl group of h ₁ , h ₂ and h ₃ each independently represent an integer of 0 or more and 5 or less.

In the general formula (15), R ^{151 to} R ¹⁵³ preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably an n-butyl group.

In general formula (15), h ₁ , h ₂ and h ₃ each independently represent an integer of 0 or more and 5 or less. When h ₁ represents an integer of 2 or more and 5 or less, a plurality of R ¹⁵¹ bonded to the same phenyl group may be the same or different. If h ₂ represents an integer of 2 to 5, a plurality of R ¹⁵² attached to the same phenyl group may be the same or different from each other. When h ₃ represents an integer of 2 or more and 5 or less, a plurality of R ¹⁵³ bonded to the same phenyl group may be the same as or different from each other. h ₁ preferably represents 1. Preferably, h ₂ and h ₃ represent 0.

The bonding position of R ^{151 to} R ¹⁵³ is not particularly limited. R ^{151 to} R ¹⁵³ may be bonded (positioned) at any of the ortho, meta and para positions of the phenyl group. R ¹⁵¹ is preferably bonded to the para position of the phenyl group.

In formula (15), R ¹⁵¹ , R ¹⁵² and R ¹⁵³ each represent an alkyl group having 1 to 6 carbon atoms, and h ₁ , h ₂ and h ₃ each independently represent 0 or 1 Is preferred.

  The suitable example of a compound (15) is a compound (Hereinafter, it may describe as a compound (15-1).) Represented by following Chemical formula (15-1).

In order to adjust the charge potential Vn _{0 under} negative charge measurement conditions and the potential difference Vp _LA -Vp _LC under positive charge measurement conditions to desired values and to suppress the generation of image ghosts in the formed image, the photosensitive layer Preferably, the agent contains the compound (10), (11), (12) or (15), more preferably the compound (10), the compound (10-1), (10-2) or It is further preferable to include 10-3).

In order to adjust the charge potential Vn _{0 under} negative charge measurement conditions and the potential difference Vp _LA -Vp _LC under positive charge measurement conditions to desired values and to suppress the occurrence of image ghosts in the formed image, two or more electron transport agents Contains at least a first electron transfer agent and a second electron transfer agent, the first electron transfer agent is the compound (1), and the second electron transfer agent is the compound (2), (3), (4), (( 5), (6) or (7), and the hole transport agent preferably contains the compound (10), (11), (12) or (15). For the same reason, two or more electron transport agents contain at least a first electron transport agent and a second electron transport agent, the first electron transport agent is the compound (1), and the second electron transport agent is the compound (2) More preferably, the hole transport agent comprises the compound (10). For the same reason, two or more electron transport agents contain at least a first electron transport agent and a second electron transport agent, the first electron transport agent is a compound (1-1), and the second electron transport agent is a compound It is still more preferable that it is (2-1) and a positive hole transport agent contains a compound (10-1), (10-2), or (10-3).

  When the hole transfer agent contains the compound (10), (11), (12), (13), (14) or (15), the compound (10), (11), (12), (13), The content of (14) or (15) is preferably 80% by mass or more, more preferably 90% by mass or more, based on the mass of the hole transfer agent contained in the photosensitive layer. Particularly preferred is mass%. When the hole transfer agent contains the compound (10), (11), (12) or (15), the content of the compound (10), (11), (12) or (15) is contained in the photosensitive layer The amount is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, with respect to the mass of the hole transport agent to be

  The content of the hole transfer agent contained in the photosensitive layer is preferably 10 parts by mass or more and 200 parts by mass or less and 40 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferably, it is 50 to 60 parts by mass.

(Charge generating agent)
The photosensitive layer contains a charge generating agent. The charge generating agent is not particularly limited as long as it is a charge generating agent for a photoreceptor. Examples of charge generating agents include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squalene pigments, indigo pigments, azulenium pigments, cyanines Pigment, powder of inorganic photoconductive material (eg, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide or amorphous silicon), pyrylium pigment, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, A pyrazoline pigment or a quinacridone pigment is mentioned. The charge generating agent may be used alone or in combination of two or more.

  As a phthalocyanine-type pigment, a metal free phthalocyanine or metal phthalocyanine is mentioned, for example. Examples of the metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine and chlorogallium phthalocyanine represented by the chemical formula (C-1). The phthalocyanine pigment may be crystalline or non-crystalline. The crystal form (for example, α-type, β-type, Y-type, V-type or II-type) of the phthalocyanine-based pigment is not particularly limited, and phthalocyanine-based pigments having various crystal forms are used.

  As a crystal of a metal free phthalocyanine, the X-type crystal of a metal free phthalocyanine is mentioned, for example. Examples of crystals of titanyl phthalocyanine include α-type, β-type or Y-type crystals of titanyl phthalocyanine (hereinafter sometimes referred to as α-type, β-type or Y-type titanyl phthalocyanine). Examples of hydroxygallium phthalocyanine crystals include V-type crystals of hydroxygallium phthalocyanine.

  For example, in a digital optical image forming apparatus (more specifically, a laser beam printer or a facsimile using a light source such as a semiconductor laser), a photoreceptor having sensitivity in a wavelength region of 700 nm or more is used. Is preferred. As a charge generating agent, phthalocyanine pigments are preferable, metal-free phthalocyanines or titanyl phthalocyanines are more preferable, and X-type metal-free phthalocyanines or Y-type titanyl phthalocyanines are more preferable because they have high quantum yield in a wavelength region of 700 nm or more. , Y-type titanyl phthalocyanine is particularly preferred.

  Y-type titanyl phthalocyanine has, for example, a main peak at 27.2 ° of a Bragg angle (2θ ± 0.2 °) in a CuKα characteristic X-ray diffraction spectrum. The main peak in the CuKα characteristic X-ray diffraction spectrum is a peak having the first or second 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 of 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 40 kV, a tube current 30 mA, and CuKα The X-ray diffraction spectrum is measured under the conditions of the wavelength of 1.542 Å of the characteristic X-ray. The measurement range (2θ) is, for example, 3 ° or more and 40 ° or less (start angle: 3 °, stop angle: 40 °), and the scanning speed is, for example, 10 ° / minute.

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

  An example of the measuring method of a differential scanning calorimetry spectrum is demonstrated. A sample for evaluation of titanyl phthalocyanine crystal powder is placed on a sample pan, and a differential scanning calorimetry spectrum is measured using a differential scanning calorimeter (for example, "TAS-200 type DSC 8230D" manufactured by Rigaku Corporation). The measurement range is, for example, 40 ° C. or more and 400 ° C. or less, and the temperature rising rate is, for example, 20 ° C./minute.

  The 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 disperses in a photosensitive layer.

  In a photosensitive member applied to an image forming apparatus using a short wavelength laser light source, an anthanthrone pigment is suitably used as a charge generating agent. As a wavelength of a short wavelength laser, the wavelength of the range of 350 to 550 nm is mentioned, for example.

  The content of the charge generating agent is preferably 0.1 parts by mass to 50 parts by mass, and more preferably 0.5 parts by mass to 30 parts by mass with respect to 100 parts by mass of the binder resin contained in the photosensitive layer. And more preferably 0.5 parts by mass or more and 4.5 parts by mass or less.

(Binder resin)
The photosensitive layer may contain a binder resin. As binder resin, a thermoplastic resin, a thermosetting resin, or a photocurable resin is mentioned, for example. As a thermoplastic resin, for example, polycarbonate resin, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic acid polymer, styrene-acrylic acid copolymer, Polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polysulfone resin, diallyl phthalate Resin, ketone resin, polyvinyl butyral resin, polyester resin or polyether resin is mentioned. As a thermosetting resin, a silicone resin, an epoxy resin, a phenol resin, a urea resin, or a melamine resin is mentioned, for example. As a photocurable resin, the acrylic acid adduct of an epoxy compound or the acrylic acid adduct of a urethane compound is mentioned, for example. One of these binder resins may be used alone, or two or more thereof may be used in combination.

  Among these resins, polycarbonate resins are preferable because a photosensitive layer having excellent balance of processability, mechanical strength, optical properties and abrasion resistance can be obtained. As an example of polycarbonate resin, bisphenol Z-type polycarbonate resin, bisphenol ZC-type polycarbonate resin, bisphenol C-type polycarbonate resin, or bisphenol A-type polycarbonate resin is mentioned. As polycarbonate resin, resin (Hereinafter, it may describe as resin (20).) Represented by following General formula (20) is preferable.

In the general formula (20), R ²⁰¹ ~R ²⁰⁶ each independently represents a hydrogen atom, an alkyl group or a carbon atom number of 6 to 14 aryl group 1 to 6 carbon atoms. However, R ²⁰³ and R ²⁰⁴ may be bonded to each other to form a cycloalkylidene group having 5 to 7 carbon atoms. It is x + y = 1.00. It is 0.00 <x <= 1.00. That is, x is a number greater than 0.00 and not more than 1.00.

The general formula (20) an alkyl group having 1 to 6 carbon atoms R ²⁰¹ to R ²⁰⁶ represents in, preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group.

The general formula (20) an aryl group having a carbon number of 6 to 14 of R ²⁰¹ to R ²⁰⁶ represents in a phenyl group is preferable.

In the general formula (20), R ²⁰¹ , R ²⁰² , R ²⁰⁵ and R ²⁰⁶ each preferably represent an alkyl group having 1 to 6 carbon atoms or a hydrogen atom, and more preferably a hydrogen atom or a methyl group preferable. R ²⁰³ and R ²⁰⁴ are preferably bonded to each other to represent a cycloalkylidene group having 5 to 7 carbon atoms, and more preferably to each other to represent a cyclohexylidene group.

The resin (20) is a repeating structural unit represented by the general formula (20a) (hereinafter sometimes referred to as a repeating unit (20a)) and a repeating structural unit represented by the general formula (20b) (hereinafter referred to as And repeating unit (20b)). In general formula (20a) R ²⁰¹ to R ²⁰⁴ in are each synonymous with R ²⁰¹ to R ²⁰⁴ in formula (20). R ²⁰⁵ and R ²⁰⁶ in the general formula (20b) are respectively synonymous with R ²⁰⁵ and R ²⁰⁶ in formula (20).

  In the general formula (20), x represents a ratio (molar fraction) of the substance (mole number) of the repeating unit (20a) to the substance (mole number) of all the repeating units in the resin (20). y represents the ratio (molar fraction) of the substance (number of moles) of the repeating unit (20b) to the substance (number of moles) of all the repeating units in the resin (20).

  The resin (20) may be a random copolymer in which the repeating units (20a) and the repeating units (20b) are randomly copolymerized. Alternatively, the resin (20) may be an alternating copolymer in which repeating units (20a) and repeating units (20b) are copolymerized alternately. Alternatively, the resin (20) may be a periodic copolymer in which one or more repeating units (20a) and one or more repeating units (20b) are periodically copolymerized. Alternatively, the resin (20) may be a block copolymer obtained by copolymerizing a block consisting of a plurality of repeating units (20a) and a block consisting of a plurality of repeating units (20b).

  The resin (20) may have a group represented by the following general formula (20e) or (20f) as a terminal group.

In the general formula (20e), R ²⁰⁷ represents a -CO-O- or -O-. However, when combined with the ether moiety of the repeating unit (20a) or the repeating unit (20b) (-O-), R 207 represents a -CO-O-. When combined with the ester moiety of the repeating unit (20a) or the repeating unit (20b) (-CO-O-) , R 207 represents -O-. Each of R ²⁰⁸ and R ²⁰⁹ independently represents an alkylene group having 1 to 6 carbon atoms which may have at least one (preferably, 1 to 12) halogen atoms. As R ²⁰⁸ and R ²⁰⁹ , a methylene group having 2 or more and 4 or less halogen atoms or an ethylene (—CH ₂ —CH ₂ —) group is preferable. R ²¹⁰ represents an alkyl group having 1 to 6 carbon atoms which may have at least one (preferably 1 to 13) halogen atoms. As R ²¹⁰ , an alkyl group having 1 to 4 carbon atoms having 1 to 9 halogen atoms is preferable, and a 2-methylpropyl group having 9 halogen atoms is more preferable.

In the general formula (20f), R ²⁰⁷ represents a -CO-O- or -O-. However, when combined with the ether moiety of the repeating unit (20a) or the repeating unit (20b) (-O-), R 207 represents a -CO-O-. When combined with the ester moiety of the repeating unit (20a) or the repeating unit (20b) (-CO-O-) , R 207 represents -O-. R ²¹¹ represents an alkyl group having 1 to 6 carbon atoms which may have at least one (preferably, 1 to 13) halogen atoms. As R ²¹¹ , an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 4 carbon atoms is more preferable, and a tert-butyl group is particularly preferable.

  As a specific example of resin (20), polycarbonate resin represented by following General formula (PC-1), General formula (PC-2), or Chemical formula (PC-3) is mentioned. Hereinafter, polycarbonate resins represented by the following chemical formula (PC-1), general formula (PC-2) and chemical formula (PC-3) are polycarbonate resins (PC-1), (PC-2) and (PC-), respectively. It may be described as 3).

  In general formula (PC-2), x 2 + y 2 = 1.00. x2 represents a number of 0.56 or more and 0.62 or less. y2 represents a number of 0.38 or more and 0.44 or less. In general formula (PC-2), x2 represents the amount (mol) of the repeating unit to which x2 is added with respect to the total amount (mol) of repeating units in the polycarbonate resin represented by general formula (PC-2) Represents the ratio (molar fraction) of numbers. y2 is the ratio (molar fraction) of the substance mass (number of moles) of the repeating unit to which y2 is added to the total mass (number of moles) of repeating units in the polycarbonate resin represented by the general formula (PC-2) Represents

  The polycarbonate resin represented by the chemical formula (PC-3) is a resin in which y in the general formula (20) is 0.00 and x is 1.00. The polycarbonate resin represented by chemical formula (PC-3) is composed of only the repeating unit (20a).

The method for producing the binder resin is not particularly limited as long as the resin (20) can be produced. As an example of the manufacturing method of resin (20), the method (so-called, phosgene method) of condensation-polymerizing the diol compound and phosgene for comprising the repeating unit of polycarbonate resin is mentioned. More specifically, for example, a method of subjecting a diol compound represented by the general formula (20c), a diol compound represented by the general formula (20d), and phosgene to condensation polymerization can be mentioned. In general formula (20c) R ²⁰¹ to R ²⁰⁴ in are each synonymous with R ²⁰¹ to R ²⁰⁴ in formula (20). R ²⁰⁵ and R ²⁰⁶ in the general formula (20d) are respectively synonymous with R ²⁰⁵ and R ²⁰⁶ in formula (20). As another example of the method for producing the resin (20), a method in which a diol compound and diphenyl carbonate are transesterified is also mentioned.

In the reaction for producing the resin (20), desired end groups can be introduced into the resin (20) by adding a desired terminator. When the end group is the following general formula (20e), a compound represented by the following general formula (20 g) is added as a termination agent. R ²⁰⁷ in the general formula (20 g) to R ²¹⁰ are the same meanings as R ²⁰⁷ to R ²¹⁰ in formula (20e). When the terminal group is the following general formula (20f), a compound represented by the following general formula (20h) is added as a termination agent. R ²⁰⁷ R ²¹¹ and in the general formula (20h) are respectively synonymous with R ²⁰⁷ R ²¹¹ and in the general formula (20f).

  The photosensitive layer may further contain a binder resin other than the resin (20) in addition to the resin (20). The content of the resin (20) based on the mass of the binder resin contained in the photosensitive layer is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. .

To the mass of the photosensitive layer (M _L), the ratio of the binder resin mass _{(M RESIN) (M RESIN /} M L) can be less than 0.50. When the ratio (M _RESIN / M _L ) is less than 0.50, the ratio of the mass of materials other than the binder resin to the mass of the photosensitive layer is increased. Specifically, the ratio of the mass of the charge generating agent, the hole transporting agent, and the two or more electron transporting agents to the mass of the photosensitive layer is increased. The ratio (M _RESIN / M _L ) is more preferably 0.49 or less, still more preferably 0.45 or more and 0.49 or less, and still more preferably 0.45 or more and 0.47 or less .

  The viscosity average molecular weight of the binder resin is preferably 25,000 or more, and more preferably 25,000 or more and 52,500 or less. When the viscosity average molecular weight of the binder resin is 25,000 or more, the abrasion resistance of the photosensitive member can be easily improved. When the viscosity average molecular weight of the binder resin is 52,500 or less, the binder resin is easily dissolved in the solvent when the photosensitive layer is formed, and the viscosity of the coating solution for the photosensitive layer does not become too high. As a result, it becomes easy to form a photosensitive layer.

<Middle class>
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used for the intermediate layer. Due to the presence of the intermediate layer, it is considered that the flow of current generated when the photosensitive member is exposed can be smoothed and the increase in resistance can be suppressed while maintaining the insulation state to the extent that the occurrence of current leakage can be suppressed. .

  As the inorganic particles, for example, particles of metal (more specifically, aluminum, iron or copper etc.), metal oxide (more specifically, titanium oxide, alumina, zirconium oxide, tin oxide or zinc oxide etc.) Or particles of non-metallic oxides (more specifically, silica etc.). One of these inorganic particles may be used alone, or two or more thereof 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 various additives.

<Method of manufacturing photoreceptor>
The photoreceptor is manufactured, for example, as follows. The photosensitive member is manufactured by applying a coating solution for photosensitive layer (hereinafter sometimes referred to as a coating solution) on a conductive substrate to form a coating film, and drying the coating film. The coating solution is prepared by dissolving or dispersing the charge generating agent, two or more electron transporting agents, the hole transporting agent, and the components (for example, the binder resin and the various additives) added as needed in a solvent. It is manufactured by

  The solvent contained in the coating solution is not particularly limited as long as each component contained in the coating solution can be dissolved or dispersed. Examples of solvents include alcohols (more specifically, methanol, ethanol, isopropanol or butanol etc.), aliphatic hydrocarbons (more specifically, n-hexane, octane or cyclohexane etc.), aromatic hydrocarbons (more specifically, More specifically, benzene, toluene or xylene etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride or chlorobenzene etc.), ethers (more specifically, dimethyl ether, diethyl ether, Tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or propylene glycol monomethyl ether etc., ketones (more specifically, acetone, methyl ethyl ketone or cyclohexanone etc.), esters (more specifically, acetic acid Le or methyl acetate, etc.), dimethylformamide, dimethylformamide or dimethyl sulfoxide and the like. These solvents are used singly or in combination of two or more. In order to improve the workability at the time of production of the photosensitive member, it is preferable to use a non-halogen solvent (a solvent other than a halogenated hydrocarbon) as the solvent.

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

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

  The method for applying the coating solution is not particularly limited as long as it is a method capable of uniformly applying the coating solution on the conductive substrate. As a coating method, a dip coating method, a spray coating method, a spin coating method or a bar coating method may, for example, be mentioned.

  The method for drying the coating solution is not particularly limited as long as the solvent in the coating solution can be evaporated. For example, the method of heat-processing (hot-air drying) using a high temperature dryer or a reduced-pressure dryer is mentioned. The heat treatment conditions are, for example, a temperature of 40 ° C. to 150 ° C., and a time of 3 minutes to 120 minutes.

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

<Image forming apparatus>
Next, with reference to FIG. 6, an image forming apparatus 110 including the photosensitive member 100 according to the present embodiment will be described. FIG. 6 is a view showing an example of the configuration of the image forming apparatus 110. The image forming apparatus 110 includes the photosensitive member 100 according to the present embodiment. The image forming apparatus 110 shown in FIG. 6 employs a direct transfer method. The image forming apparatus 110 adopting the intermediate transfer method will be described later with reference to FIG.

  The image forming apparatus 110 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 110 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. When the image forming apparatus 110 is a color image forming apparatus, the image forming apparatus 110 employs, for example, a tandem system. Hereinafter, the tandem type image forming apparatus 110 will be described as an example.

  The image forming apparatus 110 includes image forming units 40 a, 40 b, 40 c and 40 d, a transfer belt 50, and a fixing unit 52. Hereinafter, each of the image forming units 40 a, 40 b, 40 c, and 40 d will be referred to as an image forming unit 40 unless it is necessary to distinguish between them. When the image forming apparatus 110 is a monochrome image forming apparatus, the image forming apparatus 110 includes an image forming unit 40a, and the image forming units 40b to 40d are omitted.

  The image forming unit 40 includes a photosensitive member 100, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. At the central position of the image forming unit 40, the photosensitive member 100 is provided. The photosensitive member 100 is provided rotatably in the arrow direction (counterclockwise). The charging unit 42, the exposure unit 44, the developing unit 46, and the transfer unit 48 are provided around the photosensitive member 100 in order from the upstream side of the rotational direction of the photosensitive member 100 with respect to the charging unit 42. The image forming unit 40 may further include one or both of a cleaning unit (not shown) and a charge removing unit (not shown).

  The charging unit 42 positively charges the surface (peripheral surface) of the photosensitive member 100. The charging unit 42 is a noncontact system or a contact system. 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 of the photosensitive member 100. Thus, an electrostatic latent image is formed on the surface of the photosensitive member 100. The electrostatic latent image is formed based on the image data input to the image forming apparatus 110.

  The developing unit 46 supplies toner to the electrostatic latent image formed on the photosensitive member 100. Thereby, the electrostatic latent image is developed as a toner image. The photosensitive member 100 corresponds to an image carrier that carries a toner image.

  The transfer belt 50 conveys the recording medium P between the photosensitive member 100 and the transfer unit 48. The transfer belt 50 is an endless belt. The transfer belt 50 is provided rotatably in the arrow direction (clockwise).

  The transfer unit 48 transfers the toner image developed by the developing unit 46 from the photosensitive member 100 to the transfer target. When the image forming apparatus 110 adopts the direct transfer method, the transfer target corresponds to the recording medium P. When the image forming apparatus 110 adopts the direct transfer method, when the toner image is transferred from the photosensitive member 100 to the recording medium P, the photosensitive member 100 is in contact with the recording medium P. The transfer unit 48 is, for example, a transfer roller.

  The toner images of a plurality of colors (for example, four colors of black, cyan, magenta and yellow) are sequentially superimposed on the recording medium P on the transfer belt 50 by each of the image forming units 40a to 40d.

  The image forming apparatus 110 can be designed without the charge removal unit. That is, the image forming apparatus 110 can adopt a static elimination method in which the static elimination unit is omitted. When the image forming apparatus 110 adopts the direct transfer method and the static elimination-less method, the toner image is transferred from the photosensitive member 100 to the transfer target (corresponding to the recording medium P) by the transfer unit 48 on the surface (peripheral surface) of the photosensitive member 100 The area on the surface of the transferred photosensitive member 100 is again charged to a positive polarity by the charging unit 42 without being discharged. In the static elimination-less image forming apparatus 110 which does not include the static elimination unit, the influence of the exposure is likely to remain, so that the exposure memory is generated and the image ghost is apt to occur in the formed image. However, the photosensitive member 100 according to the present embodiment can suppress the occurrence of an image ghost in a formed image. Therefore, when the image forming apparatus 110 includes the photosensitive member 100 according to the present embodiment, the generation of an image ghost in a formed image can be suppressed even when the image forming apparatus 110 does not include the charge removal unit.

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

  The image forming apparatus 110 can also adopt an intermediate transfer method. Hereinafter, with reference to FIG. 7, the image forming apparatus 110 adopting the intermediate transfer method will be described. FIG. 7 is a view showing another example of the configuration of the image forming apparatus 110. The image forming apparatus 110 includes the photosensitive member 100 according to the present embodiment. In order to avoid redundancy, the same components as those of the image forming apparatus 110 shown in FIG.

  When the image forming apparatus 110 adopts the intermediate transfer method, the transfer unit 48 described in the direct transfer method corresponds to the primary transfer unit 54 and the secondary transfer unit 58. When the image forming apparatus 110 employs an intermediate transfer method, the transfer target corresponds to the intermediate transfer belt 56 and the recording medium P. The primary transfer portion 54 applies a primary transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the intermediate transfer belt 56. The intermediate transfer belt 56 is an endless belt. The intermediate transfer belt 56 rotates in the arrow (counterclockwise) direction. When the primary transfer bias is applied, the toner image formed on the surface of the photosensitive member 100 from the photosensitive member 100 to the intermediate transfer belt 56 is transferred (primary transfer) between the photosensitive member 100 and the primary transfer portion 54 .

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

  When the image forming apparatus 110 adopts an intermediate transfer method and a charge-elimination-less method, on the surface (peripheral surface) of the photosensitive member 100, the toner is transferred from the photosensitive member 100 to a transfer target (equivalent to the intermediate transfer belt 56) by the primary transfer portion 54. The area on which the image has been transferred is again positively charged by the charging unit 42 without being discharged.

  The image forming apparatus 110 including the photosensitive member 100 according to the present embodiment has been described above with reference to FIGS. 6 and 7.

<Process cartridge>
Next, with continued reference to FIGS. 6 and 7, a process cartridge provided with the photosensitive member 100 according to the present embodiment will be described. The process cartridge is a cartridge for image formation. The process cartridge corresponds to each of the image forming units 40a to 40d. The process cartridge comprises a unitized photoreceptor 100. The process cartridge adopts a configuration in which at least one unit selected from the group consisting of a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48 (or a primary transfer unit 54) in addition to the photosensitive member 100 is unitized. Be done. The process cartridge may further include one or both of a cleaning unit (not shown) and a charge removing unit (not shown). The process cartridge may adopt a static elimination method. The process cartridge is designed to be removable from the image forming apparatus 110. Therefore, the process cartridge is easy to handle, and can be easily and quickly replaced including the photosensitive member 100 when the sensitivity characteristic of the photosensitive member 100 is deteriorated.

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

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

(Charge generating agent)
As a charge generator, titanyl phthalocyanine was prepared. The titanyl phthalocyanine was a compound represented by the chemical formula (C-1) described in the embodiment. Further, this titanyl phthalocyanine had a main peak at 27.2 ° of the Bragg angle (2θ ± 0.2 °) and no peak at 26.2 ° C. in the CuKα characteristic X-ray diffraction spectrum. This titanyl phthalocyanine has no peak in the range of 50 ° C. or more and less than 270 ° C. other than the peak accompanying vaporization of adsorbed water in thermal characteristics by DSC, and has one peak in the range of 270 ° C. or more and 400 ° C. or less It was

(Hole transport agent)
Compounds (10-1), (10-2), (10-3), (11-1), (12-1), (12-2), (13) described in the embodiment as a hole transport agent -1), (13-2), (14-1) and (15-1) were prepared.

(Binder resin)
The polycarbonate resin represented by General formula (PC-3) was prepared as binder resin. The viscosity average molecular weight of the polycarbonate resin represented by the general formula (PC-3) used in the examples was 50,000.

(Electron transport agent)
As the electron transfer agent, the compounds (1-1), (2-1), (3-1), (4-1), (5-1), (6-1), and (7-) described in the embodiments. I prepared 1). Among the compounds (1-1), (2-1), (3-1), (4-1), (5-1), (6-1) and (7-1) as the electron transfer agent Two kinds were selected and used. Each of the two electron transport agents used is described as a first electron transport agent and a second transport agent. The compound (1-1) was synthesized by the following method.

(Synthesis of Compound (1-1))
Compound (1-1) according to the reaction represented by the reaction formula (r-1) and the reaction formula (r-3) (hereinafter sometimes referred to as reaction (r-1) and (r-3), respectively) Manufactured.

  In the reaction (r-1), the naphthol compound (1A) (1-naphthol) and the alcohol compound (1B) were reacted to obtain a naphthol derivative (1C) as an intermediate product. Specifically, 1.44 g (0.010 mol) of naphthol compound (1A), 1.64 g (0.010 mol) of alcohol compound (1B), and 30 mL of acetic acid were charged into a flask to prepare an acetic acid solution. 0.98 g (0.010 mol) of concentrated sulfuric acid was added dropwise to the contents of the flask, and the mixture was stirred at room temperature (25 ° C.) for 8 hours. Ion-exchanged water and chloroform were added to the contents of the flask to obtain an organic layer. The organic layer was washed with aqueous sodium hydroxide and neutralized. Subsequently, anhydrous sodium sulfate was added to the organic layer, and the organic layer was dried. The dried organic layer was evaporated under reduced pressure to obtain a crude product containing naphthol derivative (1C).

  In the reaction (r-3), the naphthol derivative (1C) was oxidized to obtain a compound (1-1). Specifically, a crude product containing naphthol derivative (1C) and 100 mL of chloroform were charged into a flask to prepare a chloroform solution. 2.46 g (0.010 mol) of chloranil was added to the contents of the flask and stirred at room temperature (25 ° C.) for 8 hours. Subsequently, the contents of the flask were filtered to obtain a filtrate. The solvent of the obtained filtrate was distilled off to obtain a residue. The residue obtained was purified by silica gel column chromatography using chloroform as a developing solvent. Thereby, a compound (1-1) was obtained. The yield of the compound (1-1) was 1.73 g, and the yield of the compound (1-1) from the naphthol compound (1A) was 60 mol%.

Next, the ¹ H-NMR spectrum of the compound (1-1) was measured using a proton nuclear magnetic resonance spectrometer (manufactured by JASCO Corporation, 300 MHz). CDCl ₃ was used as a solvent. Tetramethylsilane (TMS) was used as an internal standard sample. FIG. 8 shows the ¹ H-NMR spectrum of compound (1-1). In FIG. 8, the vertical axis represents signal intensity (unit: arbitrary unit), and the horizontal axis represents chemical shift (unit: ppm). The chemical shift value of the compound (1-1) is shown below.
Compound (1-1): ¹ H-NMR (300 MHz, CDCl ₃ ) δ = 8.32-8.35 (m, 2H), 8.02 (s, 2H), 7.84-7.88 (m , 2H), 7.60-7.67 (m, 4H), 7.03-7.18 (m, 10H), 2.39-2.45 (m, 4H), 2.22-2.29 (M, 4H), 1.38 (s, 12H).

<Manufacture of photoconductor>
Photosensitive members (P-A1) to (P-A20) and (P-B1) to (P-B11) were manufactured using materials for forming a photosensitive layer.

(Production of Photoreceptor (P-A1))
In a container, 3 parts by mass of a charge generator, 50 parts by mass of a compound (10-1) as a hole transfer agent, 30 parts by mass of a compound (1-1) as a first electron transfer agent, and a second electron 30 parts by mass of a compound (2-1) as a transport agent, 100 parts by mass of a binder resin, and 800 parts by mass of tetrahydrofuran as a solvent were charged. The contents of the container are mixed using a ball mill for 50 hours to disperse the materials (charge generating agent, compound (10-1), compound (1-1), compound (2-1) and binder resin) in a solvent I did. Thus, a coating solution for photosensitive layer was obtained.

  Next, the prepared coating solution for a photosensitive layer was applied onto a conductive substrate (a drum-like support made of aluminum) using a dip coating method. Thus, a coating film was formed on the conductive substrate. The conductive substrate on which the coating film was formed was dried at 100 ° C. for 60 minutes to remove tetrahydrofuran from the coating film. Thus, a photosensitive layer (film thickness 25 μm) was formed on the conductive substrate. As a result, a photoreceptor (P-A1) was obtained.

(Production of Photoreceptors (P-A2) to (P-A20) and (P-B1) to (P-B11))
Photosensitive members (PA2) to (PA2) and (P-A20) and (P-B1) to (P-A2) and (P-A2) and (P-A2) and (P-A2) and (P-A2) and (P-A2) and Each of (P-B11) was manufactured.
(1) Although the compound (1-1) was used as the first electron transfer agent in the production of the photosensitive member (A-1), the photosensitive members (P-A2) to (P-A20) and (P-B1) to For each preparation of (P-B11), a first electron-transporting agent of the type shown in Tables 1 to 3 was used.
(2) In the production of the photoreceptor (A-1), 30 parts by mass of the first electron transfer agent was used, but photoreceptors (P-A2) to (P-A20) and (P-B1) to (P-B11) The first electron-transporting agent of the mass shown in Tables 1 to 3 was used in the preparation of each).
(3) Although the compound (2-1) was used as the second electron transfer agent in the production of the photosensitive member (A-1), the photosensitive members (PA2) to (PA2) and (PA1) to (PA1) to For each preparation of (P-B11), a second electron transport agent of the type shown in Tables 1 to 3 was used.
(4) In the production of the photosensitive member (A-1), 30 parts by mass of the second electron transfer agent was used, but the photosensitive members (P-A2) to (P-A20) and (P-B1) to (P-B11) are used. The second electron-transporting agent of the mass shown in Tables 1 to 3 was used in the preparation of each). The second electron transfer agent was not added in the production of each of the photoreceptors (P-B1) to (P-B3).
(5) In the production of the photosensitive member (A-1), the compound (1-1) was used as a hole transporting agent, but the photosensitive members (PA2) to (PA2) and (PA1) to (PA1) In the preparation of each of P-B11), hole transport agents of the type shown in Tables 1 to 3 were used.
(6) In the production of the photosensitive member (A-1), 30 parts by mass of the hole transfer agent was used, but the photosensitive members (P-A2) to (P-A20) and (P-B1) to (P-B11) In each of the preparation of the above, the hole transport agent of mass shown in Tables 1 to 3 was used.

<Measurement of Charged Potential Vn ₀ under Negative Charge Measurement Condition>
For each of the photoreceptor (P-A1) ~ (P -A20) and (P-B1) ~ (P -B11), were measured charge potential Vn ₀ in negative charging measurement conditions. The measurement of the charge potential Vn _{0 under} the negative charge measurement conditions was performed under the conditions of a temperature of 23 ° C. and a relative humidity of 50% RH. A drum sensitivity tester (manufactured by Gentec Co., Ltd.) was used as the first measuring device described in the embodiment. The drum sensitivity tester as a first measuring device includes a corotron charger, a charge potential measuring device, and a static eliminator. The photoreceptor was set in the drum sensitivity tester. The setting conditions of the drum sensitivity tester were as follows.

(Setting conditions)
Rotation speed of the photosensitive body (circumferential speed): 125 rpm
Current value Ic of corotron charger: -5 μA (DC current)
Gap width between the wire of the corotron charger and the surface of the photoreceptor: 10 mm
Timing to measure the charging potential Vn ₀ : At the point where 80 milliseconds have passed after charging Type of static elimination: static elimination bias with red LED of wavelength 660 nm: +24 V

In order to stabilize the operation of the drum sensitivity testing machine, the photosensitive body was negatively charged in advance while rotating the photosensitive body 5 times using the drum sensitivity testing machine. Next, the photosensitive member was rotated nine times using a drum sensitivity tester, and negative charging and discharging were performed on each circumference. Next, in the tenth cycle of the photosensitive member, steps (a) and (b) described in the embodiment were performed using a drum sensitivity tester. Next, the photosensitive member was further discharged while the photosensitive member was rotated five times using a drum sensitivity tester. The charge potential Vn ₀ under the negative charge measurement conditions measured in the step (b) is shown in Tables 1 to 3.

<Measurement of potential difference Vp _LA −Vp _LC under positive charge measurement conditions (transfer current value −5 μA)>
The potential difference Vp _LA -Vp _LC under positive charge measurement conditions was measured for each of the photosensitive members (P-A1) to (P-A20) and (P-B1) to (P-B11). The measurement of the potential difference Vp _LA -Vp _LC under positive charge measurement conditions was performed under the conditions of a temperature of 25 ° C. and a relative humidity of 45% RH. As a second measuring device described in the embodiment, a modified machine obtained by removing a static eliminator from a color printer ("FS-C5300 DN" manufactured by KYOCERA Document Solutions Inc.) was used. The modified device as the second measuring device includes the charging unit, the exposure unit, the potential measuring unit, and the transfer unit. The photoconductor was set in the modified machine.

  Steps (A) to (M) described in the embodiment were performed while rotating the photosensitive member three times using a modified machine as a second measuring device. The transfer current value of the transfer current supplied to the transfer unit in steps (E), (H) and (L) was set to -5 μA. Then, after printing a blank paper image on three sheets of paper, the solid image (image density 100%) was printed on one sheet of paper, thereby performing step (A). Further, steps (B) to (L) were performed by printing a solid image (image density: 100%) on three sheets of paper. Then, step (M) was performed. The setting conditions of the modified machine were as follows.

(Setting conditions)
Rotation speed (peripheral speed) of photoconductor: 94 rpm
Type of charging unit: Type of scorotron charger exposure unit: Exposure unit with LED as light source Exposure wavelength: 780 nm
Timing to measure the surface potentials Vp _L1 , Vp _LA and Vp _LC : When 80 milliseconds have elapsed after exposure Type of transfer unit: Transfer unit of transfer belt type Transfer current value: -5 μA
Nip width between transfer unit and photoreceptor: 1 mm

Tables 1 to 3 show the potential differences Vp _LA -Vp _LC under positive charge measurement conditions when the transfer current value is set to 5 μA. The measured surface potentials Vp _LA and Vp _LC were respectively positive values.

<Measurement of potential difference Vp _LA −Vp _LC under positive charge measurement conditions (transfer current value −20 μA)>
In the steps (E), (H) and (L), except that the transfer current value of the transfer current supplied to the transfer unit is changed from -5 μA to -20 μA, the potential difference Vp under positive charge measurement conditions at the transfer current value -5 μA setting in the same manner as the measuring method of the _LA -Vp _LC, it was measured potential difference Vp _LA -Vp _LC in the positive charge measurement conditions at the time of transfer current value -20μA setting. Tables 1 to 3 show the potential differences Vp _LA- Vp _LC under positive charge measurement conditions when the transfer current value is set to -20 μA. The measured surface potentials Vp _LA and Vp _LC were respectively positive values.

<Evaluation of image ghost suppression>
Evaluation of image ghost suppression was performed on each of the manufactured photosensitive members (P-A1) to (P-A20) and (P-B1) to (P-B11). Evaluation of image ghost suppression was performed under the environment of temperature 25 ° C. and relative humidity 45% RH. The photoreceptor was mounted on the evaluation machine. As the evaluation machine, a modified machine obtained by removing the cleaning blade from a monochrome printer ("FS-1300D" manufactured by Kyocera Document Solutions Inc.) was used. Moreover, this evaluation machine adopted the static elimination-less system. As the paper, ("fine-quality PPC paper manufactured by Fuji Xerox Co., Ltd., A4 size") was used.

  The image I (pattern image with a printing rate of 4%) was continuously printed on 5000 sheets of paper using the evaluation machine. Then, an evaluation image including the image II and the image III was printed on one sheet of paper. Image II was an image in which one black (100% image density) square appeared on a white (0% image density) background. The image II corresponded to the image formed in the first rotation of the photosensitive member. Image III was an image of full halftone (image density 12.5%). The image III corresponds to an image formed in the second and third rounds of the photosensitive member.

  The obtained image III was observed with the naked eye to confirm the presence or absence of an image ghost derived from the image II. When an exposure memory is generated in the photosensitive member, an image ghost (positive ghost) is generated in the formed image. The image ghost is an image in which the area corresponding to the black square of the image II printed in the first round of the photosensitive member appears black in the full halftone image III printed in the second and third rounds of the photosensitive member It is bad. Based on the confirmation result of the image ghost, it was evaluated whether the occurrence of the image ghost was suppressed according to the following criteria. The evaluation results of the image ghost suppression are shown in Tables 1 to 3.

(Evaluation criteria for suppression of transfer memory)
A (especially good): No image ghost was found.
B (good): Image ghost was slightly confirmed.
C (defective): The image ghost was clearly confirmed.

  In Tables 1 to 3, the first ETM, the second ETM, the HTM, and the part respectively represent a first electron transfer agent, a second electron transfer agent, a hole transfer agent, and a part by weight.

In Tables 1 to 3, “M _ETM / M _HTM ” indicates the ratio of the total mass of the electron transfer agent to the mass of the hole transfer agent. “M _ETM / M _HTM ” was calculated from the following formula. When “M _ETM / M _HTM ” is more than 1.00, it indicates that the total mass of the electron transport agent is larger than the mass of the hole transport agent.
M _ETM / M _HTM = (mass of first electron transfer agent + mass of second electron transfer agent) / mass of hole transfer agent

In Tables 1 to 3, “M _ETM / M _L ” indicates the ratio of the total mass of the electron transfer agent to the mass of the photosensitive layer. M _ETM / M _L was calculated from the following formula.
M _ETM / M _L = (mass of first electron transfer agent + mass of second electron transfer agent) / (mass of charge generating agent + mass of binder resin + mass of hole transfer agent + mass of first electron transfer agent + Mass of second electron transport agent)

In Tables 1 to 3, “M _RESIN / M _L ” indicates the ratio of the mass of the binder resin to the mass of the photosensitive layer. M _RESIN / M _L was calculated from the following equation.
M _RESIN / M _L = (mass of binder resin) / (mass of charge generating agent + mass of binder resin + mass of hole transporting agent + mass of first electron transporting agent + mass of second electron transporting agent)

As shown in Tables 1 and 2, the photoreceptors (P-A1) to (P-A20) were provided with the conductive substrate and the photosensitive layer. The photosensitive layer was a single layer. The photosensitive layer contained a charge generating agent, a hole transporting agent, and two or more electron transporting agents. The total content of the electron transfer agent was higher than the content of the hole transfer agent. The charging potential Vn ₀ under the negative charge measurement conditions was −550 V or more and less than 0 V. The potential difference Vp _LA -Vp _{LC under} positive charge measurement conditions was 0 V or more. As apparent from Tables 1 and 2, in the photosensitive members (P-A1) to (P-A20), the evaluation of the image ghost suppression was A (especially good) or B (good).

  As shown in Tables 1 and 2, in each of the photosensitive members (P-A1), (P-A7) to (P-A10) and (P-A18) to (P-A20), two or more types of electrons are used. The transport agent comprises a first electron transport agent and a second electron transport agent, the first electron transport agent is a compound (1), the second electron transport agent is a compound (2), and the hole transport agent is a compound 10) included. As apparent from Tables 1 and 2, in the photoreceptors (P-A1), (P-A7) to (P-A10), and (P-A18) to (P-A20), evaluation of image ghost suppression is It was A (especially good).

On the other hand, as shown in Table 3, in the photosensitive members (P-B1) to (P-B3), the photosensitive layer did not contain two or more types of electron transfer agents. The total content of the electron transfer agent was not more than the content of the hole transfer agent. The charging potential Vn ₀ under negative charge measurement conditions was not more than −550 V and less than 0 V. The potential difference Vp _LA -Vp _{LC under} positive charge measurement conditions was not 0 V or more.

As shown in Table 3, in the photosensitive members (P-B4) to (P-B6), the total content of the electron transfer agents was not larger than the content of the hole transfer agents. The charging potential Vn ₀ under negative charge measurement conditions was not more than −550 V and less than 0 V. The potential difference Vp _LA -Vp _{LC under} positive charge measurement conditions was not 0 V or more.

As shown in Table 3, in the photosensitive members (P-B7) to (P-B11), the charging potential Vn ₀ under the negative charge measurement conditions was not more than −550 V and less than 0 V. The potential difference Vp _LA -Vp _{LC under} positive charge measurement conditions was not 0 V or more.

  As is clear from Table 3, in the photosensitive members (P-B1) to (P-B11), the evaluation of the image ghost suppression was C (defective).

  From the above, it has been shown that the photoreceptor according to the present invention suppresses the occurrence of image ghosting in the formed image. Further, it has been shown that the image forming apparatus according to the present invention suppresses the generation of an image ghost in a formed image.

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

Claims (9)

An electrophotographic photosensitive member comprising a conductive substrate and a single layer photosensitive layer,
The photosensitive layer contains a charge generating agent, a hole transporting agent, and two or more electron transporting agents.
The total mass of the two or more electron transport agents is greater than the mass of the hole transport agent,
The charging potential of the electrophotographic photosensitive member when charged using a corotron charger whose current value is set to -5 μA is -550 V or more and less than 0 V,
Positive rotation, exposure and transfer are performed on each circumference while rotating the electrophotographic photosensitive member three times, the charging potential on each circumference is the same positive value, the exposure amount is the same, and the transfer current value is the same. At a certain time, the surface potential Vp _LA of the exposed area of the electrophotographic photosensitive member after exposure in the first cycle and before transfer, and the exposed area of the electrophotographic photosensitive member after exposure in the third cycle and before transfer An electrophotographic photosensitive member, wherein a difference Vp _LA -Vp _{LC from} the surface potential Vp _{LC of} 0 is 0 V or more. The two or more electron transfer agents at least include a first electron transfer agent and a second electron transfer agent,
The first electron transfer agent is a compound represented by the general formula (1),
The second electron transfer agent is a compound represented by the general formula (2), (3), (4), (5), (6) or (7),
The electrophotographic photosensitive member according to claim 1, wherein the hole transport agent comprises a compound represented by the general formula (10), (11), (12) or (15).

In the general formula (1),
At least one of R ¹ , R ² and R ³ represents an alkyl group having 4 to 10 carbon atoms or an alkyl group having 2 to 5 carbon atoms,
The alkyl group having 2 to 5 carbon atoms has an aryl group having 6 to 14 carbon atoms,
The remainder of R ¹ , R ² and R ³ represents an alkyl group having 1 to 3 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cycloalkyl group having 3 to 10 carbon atoms,
At least two of R ¹ , R ² and R ³ may be bonded to each other to represent a ring,
At least one of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 4 to 10 carbon atoms or an alkyl group having 2 to 5 carbon atoms,
The alkyl group having 2 to 5 carbon atoms has an aryl group having 6 to 14 carbon atoms,
The remainder of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 1 to 3 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cycloalkyl group having 3 to 10 carbon atoms,
At least two of R ⁴ , R ⁵ and R ⁶ may be linked to each other to represent a ring.

In the above general formulas (2), (4), (5), (6) and (7), R ²¹ , R ²² , R ²³ , R ²⁴ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² , R ⁶¹ , R ⁶² , R ⁶³ , R ⁶⁴ , R ⁷¹ , R ⁷² and R ⁷³ are each independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, the number of carbon atoms 2 or more and 6 or less alkenyl groups, C 1 or more and 6 or less alkoxy groups, or C 6 or more and 14 or less carbon atoms represent an aryl group,
The aryl group having 6 to 14 carbon atoms may have at least one alkyl group having 1 to 6 carbon atoms,
In the general formula (3), R ³¹ and R ³² each represent an alkyl group having 1 to 6 carbon atoms,
In the general formula (4), W is, -CO-O-or -CO-O-CH ₂ - represents a.

In the general formula (10),
R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ and R ¹⁰⁵ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 to 14 carbon atoms Represents an aryl group,
The aryl group having 6 to 14 carbon atoms may have an alkyl group having 1 to 6 carbon atoms,
Each of b ₁ , b ₂ and b ₃ independently represents an integer of 0 or more and 5 or less.

In the general formula (11),
R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ and R ¹¹⁶ are each independently an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 or more carbon atoms 14 or less aryl groups,
d ₁ , d ₂ , d ₃ and d ₄ each independently represent an integer of 0 or more and 5 or less,
d ₅ and d ₆ each independently represent an integer of 0 or more and 4 or less.

In the general formula (12),
R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ and R ¹²⁶ are each independently an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, 6 or more carbon atoms 14 or less aryl groups or alkenyl groups having 2 to 6 carbon atoms,
e ₁ , e ₂ , e ₃ and e ₄ each independently represent an integer of 0 or more and 5 or less,
Each of e ₅ and e ₆ independently represents an integer of 0 or more and 4 or less.

In the general formula (15),
R ¹⁵¹ , R ¹⁵² and R ¹⁵³ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms,
h ₁ , h ₂ and h ₃ each independently represent an integer of 0 or more and 5 or less. In the general formula (1),
At least one of R ¹ , R ² and R ³ represents an alkyl group having 2 to 5 carbon atoms having an aryl group having 6 to 14 carbon atoms,
The remainder of R ¹ , R ² and R ³ represents an alkyl group having 1 to 3 carbon atoms,
At least one of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 2 to 5 carbon atoms, having an aryl group having 6 to 14 carbon atoms,
The remainder of R ⁴ , R ⁵ and R ⁶ represents an alkyl group having 1 to 3 carbon atoms,
In the above general formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ each represent an alkyl group having 1 to 6 carbon atoms,
In the general formula (3), R ³¹ and R ³² each represent an alkyl group having 1 to 5 carbon atoms,
In the general formula (4), R ⁴¹ , R ⁴² and R ⁴³ each independently represent a hydrogen atom or an aryl group having 6 to 14 carbon atoms, and W represents —CO—O—CH ₂ — Represent
In the general formula (5), each of R ⁵¹ and R ⁵² independently represents an aryl group having 6 to 14 carbon atoms which may have one or two alkyl groups having 1 to 6 carbon atoms. Represents
In the general formula (6), each of R ⁶¹ , R ⁶² , R ⁶³ and R ⁶⁴ represents an alkyl group having 1 to 6 carbon atoms,
In the general formula (7), R ⁷¹ and R ⁷² each represent an alkyl group having 1 or more and 6 or less carbon atoms, and R ⁷³ represents a halogen atom,
In the general formula (10), R ¹⁰¹ , R ¹⁰² and R ¹⁰³ each represent an alkyl group having 1 to 6 carbon atoms, and R ¹⁰⁴ and R ¹⁰⁵ each represent an alkyl group having 1 to 6 carbon atoms And an aryl group having 6 to 14 carbon atoms which may have a, b ₁ , b ₂ and b ₃ each independently represent 0 or 1;
In the above general formula (11), R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ and R ¹¹⁶ each represent an alkyl group having 1 to 6 carbon atoms, and d ₁ , d ₂ , d ₃ and d ₄ each independently represents an integer of 0 or more and 2 or less, and d ₅ and d ₆ each represent 0,
In the general formula (12), R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ and R ¹²⁶ each represent an alkyl group having 1 to 6 carbon atoms, and e ₁ , e ₂ , e ₃ and e ₄ each independently represents an integer of 0 or more and 2 or less, and e ₅ and e ₆ each represent 0,
In the general formula (15), R ¹⁵¹ , R ¹⁵² and R ¹⁵³ each represent an alkyl group having 1 to 6 carbon atoms, and h ₁ , h ₂ and h ₃ each independently represent 0 or 1 An electrophotographic photosensitive member according to claim 2, which represents. The first electron transfer agent is a compound represented by the general formula (1),
The second electron transfer agent is a compound represented by the general formula (2),
The electrophotographic photosensitive member according to claim 2, wherein the hole transport agent contains a compound represented by the general formula (10). The compound represented by the general formula (1) is a compound represented by a chemical formula (1-1),
The compound represented by the general formula (2) is a compound represented by a chemical formula (2-1),
The electrophotographic photosensitive member according to claim 4, wherein the compound represented by the general formula (10) is a compound represented by a chemical formula (10-1), (10-2) or (10-3).

  The electrophotographic photosensitive member according to claim 1, wherein a ratio of a total mass of the two or more electron transport agents to a mass of the hole transport agent is greater than 1.00 and 1.20 or less.   A process cartridge comprising the electrophotographic photosensitive member according to claim 1. An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging unit, an exposure unit, a developing unit, and a transfer unit.
The charging unit positively charges the surface of the electrophotographic photosensitive member, and
The exposure unit exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image on the surface of the electrophotographic photosensitive member.
The developing unit develops the electrostatic latent image as a toner image,
The image forming apparatus, wherein the transfer unit transfers the toner image from the electrophotographic photosensitive member to a transfer target.   The area on the surface of the electrophotographic photosensitive member on which the toner image has been transferred from the electrophotographic photosensitive member to the transfer target by the transfer unit is again charged to a positive polarity by the charging unit without being discharged. An image forming apparatus according to claim 8.

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