JP6784238B2 - Electrophotographic photosensitive member, process cartridge and image forming apparatus - Google Patents

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 electrophotographic photosensitive member or a single-layer electrophotographic photosensitive member is used. The laminated 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 electrophotographic photosensitive member includes, as the photosensitive layer, a single-layer photosensitive layer having a function of generating charges and a function of transporting charges. The multilayer photosensitive device described in Patent Document 1 includes an electron transport layer. The electron transport layer contains a compound represented by the following chemical formula.

Japanese Unexamined Patent Publication No. 60-69657

However, according to the study by the present inventor, it has been found that the multilayer photosensitive device described in Patent Document 1 is insufficient in suppressing the generation of a ghost image in the formed image.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrophotographic photosensitive member capable of suppressing the generation of a ghost image 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 a ghost image in a formed image by providing such an electrophotographic photosensitive member.

The electrophotographic photosensitive member of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer. The photosensitive layer contains a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The ratio of the mass of the hole transporting agent to the mass of the electron transporting agent is 2.0 or more. The ratio of the total mass of the hole transporting agent and the electron transporting agent to the mass of the binder resin is 0.80 or more and 1.20 or less. While rotating the electrophotographic photosensitive member 5 times, it is charged under a predetermined charging condition in the 1st lap, exposed under a predetermined exposure condition in the 2nd, 3rd and 4th laps, and the 5th lap. The predetermined charging condition is a condition in which the wire current is a DC current of +180 μA and the grid bias is +540 V, and the predetermined exposure condition is an exposure light having a wavelength of 780 nm. The difference V _{01 −} V ₀₂ between the charging potential V ₀₁ in the first lap and the charging potential V ₀₂ in the fifth lap is the following formula (1) under the condition that the amount of light of is 1.2 μJ / cm ^2. Meet. In this case, the difference V _L2 -V _L1 between the potential after exposure V _L2 and the potential after exposure V _L1 in the fourth round of the second round satisfies the following formula (2).
+ 70V ≤ V ₀₁ -V ₀₂ ≤ + 90V ... (1)
+ 5V ≤ V _L2 −V _L1 ≤ + 14V ・ ・ ・ (2)

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

The image forming apparatus of the present invention includes an image carrier, a charged portion, an exposed portion, a developing portion, and a transfer portion. The charged portion charges the surface of the image carrier. The exposed portion exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier. The developing unit develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the image carrier to a recording medium. The charging polarity of the charged portion is positive. The transfer unit transfers the toner image from the image carrier to the recording medium while bringing the surface of the image carrier into contact with the recording medium. The image carrier is the above-mentioned electrophotographic photosensitive member.

According to the electrophotographic photosensitive member of the present invention, the generation of a ghost image in the formed image can be suppressed. Further, according to the process cartridge and the image forming apparatus of the present invention, the generation of a ghost image in the formed image can be suppressed by providing such an electrophotographic photosensitive member.

(A), (b) and (c) are schematic cross-sectional views showing an example of an electrophotographic photosensitive member according to an embodiment of the present invention, respectively. It is a figure which shows the structure of the measuring apparatus. It is an enlarged view of the charging device shown in FIG. It is a flowchart which shows the measurement procedure of the charge potential difference V ₀₁ −V ₀₂ and the post-exposure potential difference V _L2 −V _L1 . It is a figure which shows an example of the structure of the image forming apparatus, and this image forming apparatus includes an electrophotographic photosensitive member which concerns on embodiment of this invention. It is a figure which shows the image for evaluation. It is a figure which shows the image which generated the ghost image.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. The present invention can be carried out with appropriate modifications within the scope of the object of the present invention. In addition, although the description may be omitted as appropriate for the parts where the description is duplicated, the gist of the invention is not limited.

Hereinafter, the compound and its derivative may be collectively referred to by adding "system" after the compound name. When the polymer name is represented by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative.

Hereinafter, halogen atoms, alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 3 carbon atoms, alkyl groups having 4 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms and carbons. Alkoxy groups having 1 or more and 3 or less atoms have the following meanings, unless otherwise specified.

Examples of the halogen atom (halogen group) include a fluorine atom (fluoro group), a chlorine atom (chloro group), a bromine atom (bromo group) and an iodine atom (iodine group).

The alkyl group having 1 to 6 carbon atoms, the alkyl group having 1 to 3 carbon atoms and the alkyl group having 4 to 6 carbon atoms are linear or branched and unsubstituted, respectively. Examples of alkyl groups having 1 or more and 6 or less carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group and isopentyl. Examples include groups, neopentyl groups, 1,2-dimethylpropyl groups and hexyl groups. An example of an alkyl group having 1 or more and 3 or less carbon atoms is a group having 1 or more and 3 or less carbon atoms among the groups described as examples of an alkyl group having 1 or more and 6 or less carbon atoms. An example of an alkyl group having 4 or more and 6 or less carbon atoms is a group having 4 or more and 6 or less carbon atoms among the groups described as examples of an alkyl group having 1 or more and 6 or less carbon atoms.

The alkoxy group having 1 or more and 6 or less carbon atoms and the alkoxy group having 1 or more and 3 or less carbon atoms are linear or branched and unsubstituted, respectively. Examples of alkoxy groups having 1 or more and 6 or less carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, n-pentoxy group, and the like. Examples thereof include an isopentoxy group, a neopentoxy group and a hexyl group. An example of an alkoxy group having 1 or more and 3 or less carbon atoms is a group having 1 or more and 3 or less carbon atoms among the groups described as examples of an alkoxy group having 1 or more and 6 or less carbon atoms.

<Electrophotophotoreceptor>
The present embodiment relates to an electrophotographic photosensitive member (hereinafter referred to as a photosensitive member). The photoconductor of the present embodiment can suppress the generation of a ghost image in the formed image. Examples of the ghost image include a ghost image caused by an exposure memory and a ghost image caused by a transfer memory.

The ghost image caused by the exposure memory is an image defect in which the region corresponding to the exposed region in front of the photoconductor is darkened in the formed image. The exposure memory is a phenomenon in which the charging potential of the region corresponding to the exposed region on the previous circumference is lower than the region corresponding to the non-exposed region on the previous circumference on the surface of the photoconductor due to the influence of exposure. Exposure memory tends to occur especially in a low temperature and low humidity environment.

The ghost image caused by the transfer memory is an image defect in which the region corresponding to the unexposed region in front of the photoconductor is darkened in the formed image. In the transfer memory, due to the influence of the transfer bias (bias of the polarity opposite to the charging polarity), the charging potential of the region corresponding to the non-exposed region of the previous circumference on the surface of the photoconductor corresponds to the exposed region of the previous circumference. It is a phenomenon that is lower than. Transfer memory tends to occur especially in a high temperature and high humidity environment.

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

As shown in FIG. 1A, the photoconductor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a single layer. The photoconductor 1 is a so-called single-layer electrophotographic photosensitive member including the single-layer photosensitive layer 3.

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

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

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

The photoconductor 1 has been described above with reference to FIGS. 1 (a) to 1 (c). Hereinafter, the photoconductor will be described in more detail.

<Charging potential difference V _01- V ₀₂ and post-exposure potential difference V _L2- V _L1 >
While rotating the photoconductor five times, the photoconductor is charged under predetermined charging conditions in the first lap, and the photoconductor is exposed under predetermined exposure conditions in the second, third, and fourth laps. When the photoconductor is charged under predetermined charging conditions in the fifth lap, the difference between the charging potential V ₀₁ of the photoconductor in the first lap and the charging potential V ₀₂ of the photoconductor in the fifth lap is V ₀₁ −V _02. , The following formula (1) is satisfied. The predetermined charging conditions and the predetermined exposure conditions will be described later.
+ 70V ≤ V ₀₁ -V ₀₂ ≤ + 90V ... (1)

That is, the difference between the charging potential V ₀₁ of the photoconductor in the first lap and the charging potential V ₀₂ of the photoconductor in the fifth lap V _01- V ₀₂ (hereinafter, the charging potential difference V _01- V ₀₂ ) may be described. Yes) is + 70V or more and + 90V or less. When the charging potential difference V ₀₁ −V ₀₂ is + 70 V or more and + 90 V or less, the generation of a ghost image in the formed image can be suppressed. When the charging potential difference V ₀₁ −V ₀₂ is + 70 V or more, it is possible to suppress the generation of a ghost image in the formed image, particularly in a high temperature and high humidity environment. When the charging potential difference V ₀₁ −V ₀₂ is + 90 V or less, it is possible to suppress the generation of a ghost image in the formed image, particularly in a low temperature and low humidity environment.

In the first and fifth laps, the photoconductor is positively charged under the predetermined charging conditions described later, so that the charging potential V ₀₁ and the charging potential V ₀₂ are positive values, respectively. Therefore, when the mathematical formula (1) is satisfied, the charging potential V ₀₂ of the photoconductor in the fifth lap is lower than the charging potential V ₀₁ of the photoconductor in the first lap.

In order to suppress the occurrence of a ghost image in the formed image, the charging potential difference V ₀₁ −V ₀₂ is preferably + 75 V or more. For the same reason, the charging potential difference V ₀₁ −V ₀₂ is preferably + 85 V or less, more preferably + 80 V or less, further preferably + 78 V or less, and particularly preferably + 77 V or less. For the same reason, the charging potential difference V ₀₁ −V ₀₂ is within two values selected from + 70V, + 75V, + 76V, + 77V, + 78V, + 79V, + 80V, + 81V, + 82V, + 83V, + 84V, + 85V, + 86V and + 90V. Is also preferable.

The charging potential difference V _01- V ₀₂ can be adjusted by changing the type of the hole transporting agent, the type of the electron transporting agent, and the type of the binder resin. The charging potential V ₀₁ -V _02, by changing the ratio M _HTM / M _ETM mass M _HTM in the hole-transporting material to the mass M _ETM of the electron transport agent, it can be adjusted. Further, the charging potential difference V ₀₁ −V ₀₂ changes the ratio ( _MHTM + _METM ) / M _Resin of the total mass ( _MHTM + _METM ) of the hole transporting agent and the electron transporting agent to the mass M _Resin of the binder resin. This can be adjusted.

While rotating the photoconductor five times, the photoconductor is charged under predetermined charging conditions in the first lap, and the photoconductor is exposed under predetermined exposure conditions in the second, third, and fourth laps. When the photoconductor is charged under predetermined charging conditions in the 5th lap, the difference between the post-exposure potential V _L1 of the photoconductor in the 2nd lap and the post-exposure potential V _L2 of the photoconductor in the 4th lap V _L2- V _L1 satisfies the following formula (2). The predetermined charging conditions and the predetermined exposure conditions will be described later.
+ 5V ≤ V _L2 −V _L1 ≤ + 14V ・ ・ ・ (2)

That is, the difference between the post-exposure potential V _L1 of the photoconductor in the second lap and the post-exposure potential V _L2 of the photoconductor in the fourth lap V _L2- V _L1 (hereinafter, the post-exposure potential difference V _L2- V _L1 ). (May be described) is + 5V or more and + 14V or less. When the post-exposure potential difference V _L2- V _L1 is + 5 V or more and + 14 V or less, the generation of a ghost image in the formed image can be suppressed. When the post-exposure potential difference V _L2- V _L1 is + 5 V or more, it is possible to suppress the generation of a ghost image in the formed image, particularly in a high temperature and high humidity environment and a low temperature and low humidity environment. When the post-exposure potential difference V _L2- V _L1 is + 14 V or less, it is possible to suppress the generation of a ghost image in the formed image particularly in a high temperature and high humidity environment and a low temperature and low humidity environment.

In the first and fifth laps, the photoconductor is positively charged under the predetermined charging conditions described later, so that the post-exposure potential V _L1 and the post-exposure potential V _L2 are positive values, respectively. .. Therefore, when satisfying Equation (2), the potential after exposure V _L2 of the photosensitive member in the fourth lap is higher than the potential after exposure V _L1 of the photosensitive member at the second round.

In order to suppress the occurrence of a ghost image in the formed image, the post-exposure potential difference V _L2- V _L1 is preferably + 7 V or more. For the same reason, the post-exposure potential difference V _L2- V _L1 is preferably + 10 V or less. For the same reason, the post-exposure potential difference V _L2- V _L1 is preferably within the range of two values selected from + 5V, + 6V, + 7V, + 8V, + 9V, + 10V, + 11V, + 12V, + 13V and + 14V.

The post-exposure potential difference V _L2- V _L1 can be adjusted by changing the type of hole transporting agent, the type of electron transporting agent, and the type of binder resin. Furthermore, post-exposure potential V _L2 -V _L1 by changing the ratio M _HTM / M _ETM mass M _HTM in the hole-transporting material to the mass M _ETM of the electron transport agent, can be adjusted. In addition, the post-exposure potential difference V _L2- V _L1 changes the ratio (M _HTM + M _ETM ) / M _Resin of the total mass ( _MHTM + _METM ) of the hole transporting agent and the electron transporting agent to the mass M _Resin of the binder resin. By doing so, it can be adjusted.

(Measuring method of charging potential difference V _01- V ₀₂ and post-exposure potential difference V _L2- V _L1 )
Hereinafter, a method for measuring the charging potential difference V ₀₁ −V ₀₂ and the post-exposure potential difference V _L2- V _L1 will be described with reference to FIGS. 2 to 4.

[measuring device]
The charging potential difference V ₀₁ −V ₀₂ and the post-exposure potential difference V _L2- V _L1 are measured using the measuring device 20 shown in FIG. The measuring device 20 includes a scorotron charging device 21, an exposure device 22, and a potential measurement probe 23. The scorotron charging device 21 charges the surface 1a of the photoconductor 1. The exposure apparatus 22 exposes the surface 1a of the photoconductor 1. The potential measurement probe 23 measures the potential of the surface 1a of the photoconductor 1 (for example, charging potential V ₀₁ , charging potential V ₀₂ , post-exposure potential V _L1 , and post-exposure potential V _{L 2} ). The photoconductor 1 is rotatably provided in the measuring device 20 about the rotation axis 1s of the photoconductor 1. The scorotron charging device 21, the exposure device 22, and the potential measurement probe 23 are arranged around the photoconductor 1 in the order described from the upstream side in the rotation direction of the photoconductor 1.

Next, the scorotron charging device 21 will be further described with reference to FIG. FIG. 3 is an enlarged view of the scorotron charging device 21 shown in FIG. The scorotron charging device 21 includes a wire 211, a casing 212, a power supply 213, an ammeter 214, a voltage applying device 215, and a grid 216. The wire 211 is connected to one end of the ammeter 214. A power supply 213 is connected to the other end of the ammeter 214. The power supply 213 passes a current through the wire 211 via the ammeter 214. The ammeter 214 measures the current flowing from the power supply 213 to the wire 211. The grid 216 is connected to the voltage application device 215. The voltage application device 215 applies a grid bias to the grid 216. The casing 212 accommodates the wire 211 and the grid 216. The current flowing from the scorotron charging device 21 to the photoconductor 1 is controlled by the current flowing through the wire 211 and the grid bias applied to the grid 216.

The wire 211 of the scorotron charging device 21 is arranged in parallel with the rotation axis 1s of the photoconductor 1. The grid 216 of the scorotron charging device 21 is arranged perpendicular to each of the wire 211 and the rotation axis 1s of the photoconductor 1.

As the measuring device 20, a drum sensitivity tester (manufactured by Gentec Co., Ltd.) can be used. As the potential measurement probe 23, "MODEL1017AS" manufactured by Monore Electronics can be used.

[Predetermined charging conditions and predetermined exposure conditions]
The charging potential difference V ₀₁ −V ₀₂ and the post-exposure potential difference V _L2- V _L1 are measured under predetermined charging conditions and predetermined exposure conditions. The predetermined charging condition is a condition in which the wire current is a direct current of +180 μA and the grid bias is +540V. The wire current is a current flowing through the wire 211 of the scorotron charging device 21. The grid bias is a bias applied to the grid 216 of the scorotron charging device 21. The predetermined exposure condition is a condition in which the wavelength of the exposure light is 780 nm and the amount of the exposure light is 1.2 μJ / cm ² . The exposure light is light that the exposure apparatus 22 irradiates the surface 1a of the photoconductor 1.

[Measurement condition]
The charging potential difference V _01- V ₀₂ and the post-exposure potential difference V _L2- V _L1 are measured under the following measurement conditions in addition to the predetermined charging conditions and the predetermined exposure conditions. The measurement environment is an environment with a temperature of 23 ° C. and a relative humidity of 50% RH. The peripheral speed of the photoconductor 1 is 109 rpm. The distance D ₂₁₁ from the wire 211 of the scorotron charging device 21 to the surface 1a of the photoconductor 1 is 8.0 mm. The distance D ₂₁₆ from the grid 216 of the scorotron charging device 21 to the surface 1a of the photoconductor 1 is 1.0 mm. The time from when a specific region of the surface 1a of the photoconductor 1 (for example, one point on the surface 1a) passes through the charging position A to when it reaches the exposure position B is 0.115 seconds. The time from when the specific region of the surface 1a of the photoconductor 1 (for example, one point on the surface 1a) passes through the exposure position B to reach the potential measurement position C is 0.092 seconds. The charging position A is a position where the line passing through the rotation axis 1s of the photoconductor 1 and the wire 211 of the scorotron charging device 21 (the line orthogonal to each of the rotation axis 1s and the wire 211) intersects the surface 1a of the photoconductor 1. Shown. The exposure position B indicates a position where the exposure apparatus 22 irradiates the surface 1a of the photoconductor 1 with the exposure light. The potential measurement position C indicates a position where the potential measurement probe 23 measures the potential of the surface 1a of the photoconductor 1.

[Potentiometric titration measurement procedure]
The charging potential difference V _01- V ₀₂ and the post-exposure potential difference V _L2- V _L1 are measured by the potential difference measuring procedure shown in FIG. FIG. 4 is a flowchart showing a measurement procedure of the charging potential difference V ₀₁ −V ₀₂ and the post-exposure potential difference V _L2- V _L1 . The charging potential difference V _01- V ₀₂ and the post-exposure potential difference V _L2- V _L1 are measured by performing the following steps (1) to (11).
Step (1): Pre-charging step (S301), in which the scorotron charging device 21 precharges the surface 1a of the photoconductor 1 under predetermined charging conditions while rotating the photoconductor 1 four times.
Step (2): In the first round of the photoconductor 1, the first charging step (S302), in which the scorotron charging device 21 charges the surface 1a of the photoconductor 1 under predetermined charging conditions.
Step (3): In the first round of the photoconductor 1, the potential measurement probe 23 measures the charging potential V ₀₁ of the surface 1a of the photoconductor 1, and the charging potential V ₀₁ measuring step (S303).
Step (4): In the second lap of the photoconductor 1, the first exposure step (S304), in which the exposure apparatus 22 exposes the surface 1a of the photoconductor 1 under predetermined exposure conditions.
Step (5): In the second lap of the photoconductor 1, the potential measurement probe 23 measures the post-exposure potential V _L1 on the surface 1a of the photoconductor 1, and the post-exposure potential V _L1 measurement step (S305).
Step (6): In the third lap of the photoconductor 1, the second exposure step (S306), in which the exposure apparatus 22 exposes the surface 1a of the photoconductor 1 under predetermined exposure conditions.
Step (7): In the fourth lap of the photoconductor 1, a third exposure step (S307), in which the exposure apparatus 22 exposes the surface 1a of the photoconductor 1 under predetermined exposure conditions.
Step (8): In the fourth round of the photoconductor 1, the potential measurement probe 23 measures the post-exposure potential V _L2 of the surface 1a of the photoconductor 1, and the post-exposure potential V _L2 measurement step (S308).
Step (9): In the fifth round of the photoconductor 1, a second charging step (S309) in which the scorotron charging device 21 charges the surface 1a of the photoconductor 1 under predetermined charging conditions.
Step (10): In the fifth round of the photoconductor 1, the potential measuring probe 23 measures the charging potential V ₀₂ of the surface 1a of the photoconductor 1, and the charging potential V ₀₂ measuring step (S310), and the step (11): Calculation step (S311) to calculate the charging potential difference V ₀₁ −V ₀₂ and the post-exposure potential difference V _L2- V _L1 from the measured charging potential V ₀₁ , charging potential V ₀₂ , post-exposure potential V _L1 , and post-exposure potential V _L2. ..

In the step (11), the charging potential difference V _01- V ₀₂ is calculated from the calculation formula "charging potential difference V _01- V ₀₂ = charging potential V ₀₁ -charging potential V ₀₂ ". The post-exposure potential difference V _L2- V _L1 is calculated from the formula “post-exposure potential difference V _L2- V _L1 = post-exposure potential V _L2 -post-exposure potential V _L1 ”.

The four laps of the precharging step are not counted as the number of laps of the photoconductor 1, but the rotation of the photoconductor 1 in the first charging step is counted as the first lap. Further, in the first round of the photoconductor 1, the surface 1a of the photoconductor 1 continues to be charged while the photoconductor 1 makes one round. In the first round of the photoconductor 1, the photoconductor 1 is not exposed. In the second round of the photoconductor 1, the surface 1a of the photoconductor 1 is continuously exposed while the photoconductor 1 makes one round. In the third round of the photoconductor 1, the surface 1a of the photoconductor 1 is continuously exposed while the photoconductor 1 makes one round. In the fourth round of the photoconductor 1, the surface 1a of the photoconductor 1 is continuously exposed while the photoconductor 1 makes one round. In the second to fourth laps of the photoconductor 1, the photoconductor 1 is not charged. In the fifth round of the photoconductor 1, the surface 1a of the photoconductor 1 continues to be charged while the photoconductor 1 makes one round. In the fifth round of the photoconductor 1, the photoconductor 1 is not exposed.

As described above, the measurement method of the charging potential difference V ₀₁ −V ₀₂ and the post-exposure potential difference V _L2- V _L1 has been described with reference to FIGS. 2 to 4.

<Photosensitive layer>
The photosensitive layer contains a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The photosensitive layer may contain additives, if necessary.

(Ratio M _HTM / M _ETM )
The ratio of the mass M _HTM of the hole transporting agent to the mass M _ETM of the electron transporting agent M _HTM / M _ETM is 2.0 or more. When the ratio M _HTM / M _ETM is 2.0 or more, it is possible to suppress the occurrence of a ghost image in the formed image, particularly in a high temperature and high humidity environment and a low temperature and low humidity environment.

In order to suppress the generation of ghost images in the formed image in a high temperature and high humidity environment and a low temperature and low humidity environment, the ratio M _HTM / _METM is preferably 2.3 or more, and 2.4 or more. More preferably, it is more preferably 2.5 or more, and even more preferably 2.6 or more. For the same reason, the ratio M _HTM / _METM is preferably less than 4.0, more preferably 3.9 or less, and even more preferably 3.8 or less. For the same reason, the ratio _MHTM / _METM is 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 3.0, 3.8 and 3. It is also preferable that it is within the range of two values selected from 9.

(Ratio (M _HTM + M _ETM ) / M _Resin )
With respect to the mass M _Resin binder resin, the ratio _{(M HTM + M ETM) /} M Resin of the total weight of the hole transferring material and electron transferring material (M _HTM + M _ETM) is 0.80 to 1.20. When the ratio (M _HTM + M _ETM ) / M _Resin is 0.80 or more, it is possible to suppress the generation of ghost images in the formed images in a high temperature and high humidity environment and a low temperature and low humidity environment. When the ratio (M _HTM + M _ETM ) / M _Resin is 1.20 or less, it is possible to suppress the generation of ghost images in the formed images in a high temperature and high humidity environment and a low temperature and low humidity environment.

In order to suppress the generation of ghost images in the formed images in a high temperature and high humidity environment and a low temperature and low humidity environment, the ratio ( _MHTM + _METM ) / M _Resin is preferably 0.85 or more, and is 0. It is more preferably .90 or more. For the same reason, the ratio ( _MHTM + _METM ) / M _Resin is preferably 1.10 or less. For the same reason, the ratio (M _HTM + M _ETM ) / M _Resin is 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15 and 1. It is also preferably within the range of two values selected from 20.

(Hole transport agent)
Examples of the hole transporting agent include triphenylamine derivatives and diamine derivatives (for example, N, N, N', N'-tetraphenylbenzidine derivatives, N, N, N', N'-tetraphenylphenylenediamine derivatives, etc. N, N, N', N'-tetraphenylnaphthylene diamine derivative, N, N, N', N'-tetraphenylphenanthrylene diamine derivative or di (aminophenylethenyl) benzene derivative), oxadiazole-based Compounds (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), styryl compounds (eg, 9- (4-diethylaminostyryl) anthracene), carbazole compounds (eg) , Polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (eg 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline), hydrazone compounds, indol compounds, oxazole compounds, isooxazole compounds, thiazole compounds. Examples thereof include compounds, thiadiazol compounds, imidazole compounds, pyrazole compounds and triazole compounds. The photosensitive layer may contain only one type of hole transporting agent, or may contain two or more types.

Preferable examples of the hole transporting agent include compounds represented by the general formulas (10), (11), (12), (13) and (14). Hereinafter, each of the compounds represented by the general formulas (10), (11), (12), (13) and (14) will be referred to as compounds (10), (11), (12), (13) and ( 14) may be described. When the photosensitive layer contains the compounds (10), (11), (12), (13) or (14) as hole transporters, the charging potential difference V _01- V ₀₂ and the post-exposure potential difference V _L2- V _L1 Can be suitably adjusted to a desired value.

Hereinafter, compound (10) will be described.

In the general formula (10), R ¹ and R ² independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms. a ₁ and a ₂ each independently represent an integer of 0 or more and 5 or less. R ³ and R ⁴ may independently have an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms, or −CR ⁵ = CR ⁶ R ⁷ Represents. R ⁵ , R ⁶ and R ⁷ each independently represent an alkyl group having 1 or more and 6 or less carbon atoms or a phenyl group or a hydrogen atom which may have an alkoxy group having 1 or more and 6 or less carbon atoms. W represents a single bond or a p-phenylene group.

In order to suppress the occurrence of a ghost image in the formed image, in the general formula (10), the alkyl group represented by R ¹ and R ² having 1 or more and 6 or less carbon atoms includes an alkyl having 1 or more and 3 or less carbon atoms. A group is preferable, and a methyl group is more preferable.

In order to suppress the occurrence of a ghost image in the formed image, in the general formula (10), the alkoxy group represented by R ¹ and R ² having 1 or more and 6 or less carbon atoms includes an alkoxy group having 1 or more and 3 or less carbon atoms. A group is preferable, and a methoxy group is more preferable.

In the general formula (10), if a ₁ is an integer of 2 to 5, a plurality of R ¹ may be different may be the same as each other. If a ₂ represents an integer of 2 to 5, a plurality of R ² may be different may be the same as each other. In order to suppress the occurrence of a ghost image in the formed image, a ₁ preferably represents an integer of 0 or more and 2 or less, and more preferably 1 or 2. In order to suppress the occurrence of a ghost image in the formed image, a ₂ preferably represents an integer of 0 or more and 2 or less, and more preferably 1 or 2.

The bonding position of R ¹ and R ² is not particularly limited. R ¹ and R ² may be bonded (positioned) to any of the ortho-position, meta-position and para-position of the phenyl group, respectively. When a ₁ is 1, R ¹ is preferably bonded to the para position of the phenyl group. When a ₁ is 2, two R ¹ is preferably bonded to the ortho and para positions of the phenyl group. When a ₂ is 1, R ² is preferably attached to the para position of the phenyl group. When a ₂ is 2, two R ² is preferably bonded in the ortho-position and para-position of the phenyl group.

In the general formula (10), R ³ and R ⁴ each independently represent a phenyl group or −CR ⁵ = CR ⁶ R ⁷ . The case where R ³ and R ⁴ represent a phenyl group will be described. The phenyl group represented by R ³ and R ⁴ may have an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms as a substituent. As the alkyl group having 1 or more and 6 or less carbon atoms of the phenyl group, an alkyl group having 1 or more and 3 or less carbon atoms is preferable, and a methyl group is more preferable. As the alkoxy group having 1 or more and 6 or less carbon atoms in the phenyl group, an alkoxy group having 1 or more and 3 or less carbon atoms is preferable, and a methoxy group is more preferable. When the phenyl group has an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms as a substituent, the number of substituents of the phenyl group is preferably 1 to 5 or less. It is preferably 1 or more and 3 or less, and more preferably 1 or 2. In order to suppress the generation of a ghost image in the formed image, R ³ and R ⁴ are preferably a phenyl group having an alkyl group having 1 or more and 6 or less carbon atoms, and preferably 1 or more and 3 or less carbon atoms. A phenyl group which may have an alkyl group of the above is more preferable, a phenyl group which may have a methyl group is further preferable, and a phenyl group or a p-methylphenyl group is particularly preferable.

The case where R ³ and R ⁴ represent −CR ⁵ = CR ⁶ R ⁷ will be described. R ⁵ , R ⁶ and R ⁷ each independently represent a phenyl group or a hydrogen atom. The phenyl group represented by R ⁵ , R ⁶ and R ⁷ may have an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms as a substituent. R ⁵ preferably represents a hydrogen atom. It is preferable that R ⁶ and R ⁷ each represent a phenyl group.

W represents a single bond or a p-phenylene group. In order to suppress the occurrence of a ghost image in the formed image, W preferably represents a p-phenylene group.

In order to suppress the occurrence of a ghost image in the formed image, in the general formula (10), R ¹ and R ² are independently alkyl groups having 1 or more and 6 or less carbon atoms or 1 or more and 6 or less carbon atoms. A ₁ and a ₂ each independently represent 1 or 2, and R ³ and R ⁴ may each independently have an alkyl group having 1 or more and 6 or less carbon atoms. A phenyl group, or -CR ⁵ = CR ⁶ R ⁷ , R ⁵ , R ⁶ and R ⁷ each independently represent a phenyl group or a hydrogen atom, and W represents a single bond or p-phenylene group. Is preferable.

In order to suppress the occurrence of a ghost image in the formed image, in the general formula (10), R ¹ and R ² are independently alkyl groups having 1 or more and 6 or less carbon atoms or 1 or more and 6 or less carbon atoms. A ₁ and a ₂ represent 1 respectively, and R ³ and R ⁴ each represent a phenyl group which may have an alkyl group having 1 or more and 6 or less carbon atoms. More preferably represents a p-phenylene group.

In order to suppress the occurrence of a ghost image in the formed image, in the general formula (10), R ¹ and R ² each independently represent a methyl group or a methoxy group, and a ₁ and a ₂ are 1 respectively. , R ³ and R ⁴ each represent a phenyl group or a p-methylphenyl group, and W more preferably represents a p-phenylene group.

Preferable examples of compound (10) include chemical formulas (H-1), (H-2), (H-3), (H-4), (H-5), (H-6) and (H). Compounds represented by -7) (hereinafter, each of which is compound (H-1), (H-2), (H-3), (H-4), (H-5), (H-6) and (H-7) may be described). Among these compounds, the compounds (H-4), (H-5) or (H-6) are more preferable in order to suppress the generation of ghost images in the formed image.

Next, compound (11) will be described.

In the general formula (11), R ¹¹ , R ¹² , R ¹³ and R ¹⁴ independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms. b ₁ , b ₂ , b ₃ and b ₄ each independently represent an integer of 0 or more and 5 or less.

In the general formula (11), if b ₁ represents an integer of 2 to 5, a plurality of R ¹¹ may be different may be the same as each other. When b ₂ represents an integer of 2 or more and 5 or less, the plurality of R ^12s may be the same as or different from each other. When b ₃ represents an integer of 2 or more and 5 or less, the plurality of R ^13s may be the same as or different from each other. When b ₄ represents an integer of 2 or more and 5 or less, the plurality of R ^14s may be the same as or different from each other. The bonding positions of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are not particularly limited. R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be bonded (positioned) to any of the ortho-position, meta-position and para-position of the phenyl group, respectively. It is preferable that R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each bonded to the para position of the phenyl group.

In the general formula (11), R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each preferably represent an alkyl group having 1 or more and 6 or less carbon atoms, and each represent an alkyl group having 1 or more and 3 or less carbon atoms. It is more preferable, and it is further preferable to represent a methyl group. It is preferable that b ₁ , b ₂ , b ₃ and b ₄ independently represent 0 or 1, respectively. It is more preferable that b ₁ and b ₂ each represent 1, and b ₃ and b ₄ each represent 0.

Preferable examples of the compound (11) include a compound represented by the chemical formula (H-12) (hereinafter, may be referred to as a compound (H-12)).

Next, compound (12) will be described.

In the general formula (12), R ²¹ , R ²² and R ²³ independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. e ₁ , e ₂ and e ₃ independently represent integers of 0 or more and 5 or less. R ²⁴ and R ²⁵ each independently represent an alkyl group having 1 or more and 6 or less carbon atoms, a phenyl group which may have an alkoxy group having 1 or more and 6 or less carbon atoms, or a hydrogen atom.

In the general formula (12), when e ₁ represents an integer of 2 or more and 5 or less, the plurality of R ^21s may be the same as or different from each other. When e ₂ represents an integer of 2 or more and 5 or less, the plurality of R ^22s may be the same as or different from each other. When e ₃ represents an integer of 2 or more and 5 or less, the plurality of R ^23s may be the same as or different from each other. The bonding positions of R ²¹ , R ²² and R ²³ are not particularly limited. R ²¹ , R ²² and R ²³ may be bonded (positioned) to any of the ortho-position, meta-position and para-position of the phenyl group, respectively.

e1, e ₂ and e ₃ are each independently preferably represents an integer of 0 to 2, and more preferably represents 0 or 2. It is more preferable that e ₁ represents ₂ and e ₂ and e ₃ represent 0. When e ₁ represents 2, the two R ^21s are preferably attached to the ortho and para positions of the phenyl group. When e ₂ represents 2, the two R ^22s are preferably bonded to the ortho and para positions of the phenyl group. When e ₃ represents 2, two R ²³ are preferably bound to the ortho and para positions of the phenyl group.

In the general formula (12), R ²¹ , R ²² and R ²³ each independently preferably represent an alkyl group having 1 or more and 6 or less carbon atoms, and each of them represents an alkyl group having 1 or more and 3 or less carbon atoms. Is more preferable, and it is further preferable to represent a methyl group. R ²⁴ and R ²⁵ each preferably represent a phenyl group. Alternatively, R ²⁴ and R ²⁵ preferably represent hydrogen atoms, respectively.

Preferable examples of the compound (12) may be described as compounds represented by the chemical formulas (H-10) and (H-11) (hereinafter, compounds (H-10) and (H-11), respectively. ).

Next, compound (13) will be described.

In the general formula (13), R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. .. f ₁ , f ₂ , f ₃ , f ₄ and f ₅ each independently represent an integer of 0 or more and 5 or less.

In the general formula (13), when f ₁ represents an integer of 2 or more and 5 or less, the plurality of R ^31s may be the same as or different from each other. When f ₂ represents an integer of 2 or more and 5 or less, the plurality of R ^32s may be the same as or different from each other. When f ₃ represents an integer of 2 or more and 5 or less, the plurality of R ^33s may be the same as or different from each other. When f ₄ represents an integer of 2 or more and 5 or less, the plurality of R ^34s may be the same as or different from each other. When f ₅ represents an integer of 2 or more and 5 or less, the plurality of R ^35s may be the same as or different from each other. The bonding positions of R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ are not particularly limited. R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ may be bonded (positioned) to any of the ortho-position, meta-position and para-position of the phenyl group, respectively. It is preferable that R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ are each bonded to the para position of the phenyl group.

In the general formula (13), R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ each preferably represent an alkyl group having 1 or more and 6 or less carbon atoms, and alkyl having 1 or more and 3 or less carbon atoms, respectively. It is more preferable to represent a group, and even more preferably to represent a methyl group. It is preferable that f ₁ , f ₂ , f ₃ , f ₄ and f ₅ each independently represent 0 or 1, and more preferably 1.

Preferable examples of the compound (13) include a compound represented by the chemical formula (H-8) (hereinafter, may be referred to as a compound (H-8)).

Next, compound (14) will be described.

In the general formula (14), R ⁴¹ , R ⁴² and R ⁴³ independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms. g1, g ₂ and g ₃ are each independently an integer of 0 to 5.

In the general formula (14), when g ₁ represents an integer of 2 or more and 5 or less, the plurality of R ^41s may be the same or different from each other. When g ₂ represents an integer of 2 or more and 5 or less, the plurality of R ^42s may be the same as or different from each other. When g ₃ represents an integer of 2 or more and 5 or less, the plurality of R ^43s may be the same as or different from each other. The bonding positions of R ⁴¹ , R ⁴² and R ⁴³ are not particularly limited. R ⁴¹ , R ⁴² and R ⁴³ may be bonded (positioned) to any of the ortho-position, meta-position and para-position of the phenyl group, respectively. It is preferable that R ⁴¹ , R ⁴² and R ⁴³ are each bonded to the meta position of the phenyl group.

In the general formula (14), R ⁴¹ , R ⁴² and R ⁴³ each preferably represent an alkyl group having 1 or more and 6 or less carbon atoms, and more preferably an alkyl group having 1 or more and 3 or less carbon atoms. It is preferable, and it is more preferable to represent a methyl group. g1, g ₂ and g ₃ are each independently preferably represents 0 or 1, and more preferably represents 1.

Preferable examples of the compound (14) include a compound represented by the chemical formula (H-9) (hereinafter, may be referred to as a compound (H-9)).

In order to suppress the generation of ghost images in the formed image, the hole transporting agent is preferably compound (10), more preferably compound (H-4), (H-5) or (H-6). Compound (H-5) or (H-6) is more preferred. A compound (H-6) is preferable as the hole transporting agent in order to particularly improve the sensitivity characteristics of the photoconductor while suppressing the generation of a ghost image in the formed image.

The photosensitive layer may contain only one of the compounds (10) to (14) as the hole transporting agent. Alternatively, the photosensitive layer may contain two or more of the compounds (10) to (14) as the hole transporting agent. Further, the photosensitive layer may contain only the compounds (10) to (14) as the hole transporting agent. Alternatively, as the hole transporting agent, the photosensitive layer may further contain a hole transporting agent other than the compounds (10) to (14) in addition to the compounds (10) to (14). The content of the compounds (10) to (14) is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total mass of the hole transporting agent contained in the photosensitive layer. , 100% by mass is particularly preferable.

The content of the hole transporting agent contained in the photosensitive layer is preferably 10 parts by mass or more and 120 parts by mass or less, and 55 parts by mass or more and 95 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferred.

(Electronic transport agent)
Examples of electron transporting agents include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, and dinitroanthracene compounds. Examples thereof include compounds, dinitroacridin compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroaclysin, succinic anhydride, maleic anhydride and dibromomaleic anhydride. Examples of the quinone compound include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds and dinitroanthraquinone compounds. The photosensitive layer may contain only one type of electron transporting agent, or may contain two or more types.

Preferable examples of the electron transporting agent include compounds represented by the general formulas (20), (21) and (22). Hereinafter, the compounds represented by the general formulas (20), (21) and (22) may be referred to as compounds (20), (21) and (22), respectively. By containing the compound (20), (21) or (22) as an electron transporting agent in the photosensitive layer, the charge mobility of the photosensitive layer is improved, and the charging potential difference V ₀₁ −V ₀₂ and the post-exposure potential difference V _L2- V _L1 can be suitably adjusted to a desired value.

Hereinafter, compound (20) will be described.

In the general formula (20), Q ¹ and Q ² independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms.

In the general formula (20), Q ¹ and Q ² each preferably represent an alkyl group having 1 or more and 6 or less carbon atoms, and more preferably represent an alkyl group having 4 or more and 6 or less carbon atoms. It is more preferable to represent a group, and it is particularly preferable to represent a 1,1-dimethylpropyl group.

Preferable examples of the compound (20) include a compound represented by the chemical formula (E-1) (hereinafter, may be referred to as a compound (E-1)).

Next, compound (21) will be described.

In the general formula (21), Q ¹¹ and Q ¹² each independently represent an alkyl group having 1 or more and 6 or less carbon atoms or a phenyl group which may have an alkoxy group having 1 or more and 6 or less carbon atoms.

In the general formula (21), the phenyl group represented by Q ¹¹ and Q ¹² may have an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms as a substituent. As the substituent contained in such a phenyl group, an alkyl group having 1 or more and 6 or less carbon atoms is preferable, an alkyl group having 1 or more and 3 or less carbon atoms is more preferable, and a methyl group or an ethyl group is further preferable. When a phenyl group has an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms as a substituent, the number of substituents in the phenyl group is preferably 1 to 3 or less. It is more preferably 1 or 2, and particularly preferably 2. Each of Q ¹¹ and Q ¹² is preferably a phenyl group having an alkyl group having 1 or more and 6 or less carbon atoms, and more preferably a phenyl group having an alkyl group having 1 or more and 3 or less carbon atoms. It is more preferably a phenyl group having a methyl group and an ethyl group, and particularly preferably a 2-ethyl-6-methylphenyl group.

Preferable examples of the compound (21) include a compound represented by the chemical formula (E-2) (hereinafter, may be referred to as a compound (E-2)).

Next, compound (22) will be described.

In the general formula (22), Q ²¹ and Q ²² independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms, and Q ²³ has a halogen atom. Represents a optionally phenyl group.

In the general formula (22), Q ²¹ and Q ²² each independently preferably represent an alkyl group having 1 or more and 6 or less carbon atoms, and more preferably represent an alkyl group having 4 or more and 6 or less carbon atoms. , Butyl group is more preferable, and tert-butyl group is particularly preferable.

In the general formula (22), Q ²³ is preferably a phenyl group having a halogen atom, more preferably a phenyl group having a chlorine atom, and even more preferably a p-chlorophenyl group.

Preferable examples of the compound (22) include a compound represented by the chemical formula (E-3) (hereinafter, may be referred to as a compound (E-3)).

In order to suppress the generation of ghost images in the formed image, the electron transporting agent is preferably compound (20), (21) or (22), and compound (E-1), (E-2) or (E). -3) is more preferable.

The photosensitive layer may contain only one of the compounds (20) to (22) as the electron transporting agent. Alternatively, the photosensitive layer may contain two or more of the compounds (20) to (22) as the electron transporting agent. Further, the photosensitive layer may contain only the compounds (20) to (22) as the electron transporting agent. Alternatively, the photosensitive layer may further contain an electron transporting agent other than the compounds (20) to (22) in addition to the compounds (20) to (22) as the electron transporting agent. The content of the compounds (20) to (22) is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total mass of the electron transporting agent contained in the photosensitive layer. It is particularly preferably 100% by mass.

The content of the electron transporting agent contained in the photosensitive layer is preferably 10 parts by mass or more and 120 parts by mass or less, and more preferably 20 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin. It is preferably 25 parts by mass, and more preferably 25 parts by mass.

(Binder resin)
Examples of the binder resin include thermoplastic resins, thermosetting resins and photocurable resins. Examples of the thermoplastic resin include polyarylate resins, polycarbonate resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic acid polymers, and styrene-acrylic acid copolymers. Polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polysulfone resin, diallyl phthalate Examples thereof include resins, ketone resins, polyvinyl butyral resins, polyester resins and polyether resins. Examples of the thermosetting resin include silicone resin, epoxy resin, phenol resin, urea resin and melamine resin. Examples of the photocurable resin include an acrylic acid adduct of an epoxy compound and an acrylic acid adduct of a urethane compound. The photosensitive layer may contain only one type of binder resin, or may contain two or more types.

In order to suppress the occurrence of a ghost image in the formed image, a polyarylate resin is preferable as the binder resin, and at least one of the repeating units represented by the chemical formulas (30A) and (30B) and the chemical formula (31) are represented. A polyarylate resin containing the repeating unit to be used and at least one of the repeating units represented by the chemical formulas (32A) and (32B) is more preferable.

Hereinafter, at least one of the repeating units represented by the chemical formulas (30A) and (30B), the repeating unit represented by the chemical formula (31), and at least the repeating unit represented by the chemical formulas (32A) and (32B). A polyarylate resin containing one type may be referred to as a polyarylate resin (PA). Further, the repeating units represented by the chemical formulas (30A), (30B), (31), (32A) and (32B) are represented by the repeating units (30A), (30B), (31), (32A) and (32A), respectively. It may be described as (32B).

Preferable examples of the polyarylate resin (PA) in order to suppress the generation of ghost images in the formed image are polyarylate resins (PA-1), (PA-2), (PA-3) and (PA-). 4) can be mentioned. The polyarylate resin (PA-1) contains repeating units (30A), (31) and (32B). The polyarylate resin (PA-1) does not contain a repeating unit (30B).

The polyarylate resin (PA-2) contains repeating units (30A), (31) and (32A). The polyarylate resin (PA-2) does not contain a repeating unit (30B).

The polyarylate resin (PA-3) contains repeating units (30A), (30B), (31) and (32B).

The polyarylate resin (PA-4) contains repeating units (30A), (30B), (31) and (32A).

In order to suppress the occurrence of a ghost image in the formed image, the polyarylate resin (PA) preferably contains the repeating unit (30A) of the repeating unit (30A) and (30B). Alternatively, the polyarylate resin (PA) preferably contains both the repeating units (30A) and (30B) in order to suppress the generation of ghost images in the formed image. When the polyarylate resin (PA) contains both the repeating units (30A) and (30B), the number of repeating units (30A) with respect to the sum of the number of repeating units (30A) and the number of repeating units (30B). The ratio (hereinafter, may be referred to as ratio m) is preferably 0.10 or more and 0.90 or less, more preferably 0.20 or more and 0.80 or less, and 0.30 or more and 0. It is more preferably 70 or less, further preferably 0.40 or more and 0.60 or less, and particularly preferably 0.50.

In order to suppress the occurrence of a ghost image in the formed image, the number of the repeating units (31) is the sum of the number of the repeating units (31) and the number of at least one of the repeating units (32A) and (32B). The ratio (hereinafter, may be referred to as ratio n) is preferably 0.10 or more and 0.90 or less, more preferably 0.20 or more and 0.80 or less, and 0.30 or more and 0. It is more preferably 70 or less, further preferably 0.40 or more and 0.60 or less, and particularly preferably 0.50.

The ratio m and the ratio n are not values obtained from one molecular chain, but average values obtained from the entire polyarylate resin (PA) contained in the photosensitive layer (plural molecular chains). .. The ratio m and the ratio n can be calculated from the ¹ H-NMR spectrum obtained by measuring the ¹ H-NMR spectrum of the polyarylate resin (PA) using a proton nuclear magnetic resonance spectrometer.

In the polyarylate resin (PA), the alcohol-derived repeating unit and the carboxylic acid-derived repeating unit are adjacent to each other. Examples of the alcohol-derived repeating unit include repeating units (30A) and (30B). Examples of the repeating unit derived from carboxylic acid include repeating units (31), (32A) and (32B). The sequences of the repeating units (30A), (30B), (31), (32A) and (32B) in the polyarylate resin (PA) are as long as the repeating units derived from alcohol and the repeating units derived from carboxylic acid are adjacent to each other. , Not particularly limited. For example, the repeating unit (30A) is adjacent to the repeating unit (31), the repeating unit (32A), or the repeating unit (32B) and is coupled to each other. Further, for example, the repeating unit (30B) is adjacent to the repeating unit (31), the repeating unit (32A), or the repeating unit (32B) and is coupled to each other. The polyarylate resin (PA) may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer or a block copolymer.

The polyarylate resin (PA) contains at least one of the repeating units (30A) and (30B), the repeating unit (31), and at least one of the repeating units (32A) and (32B) as the repeating unit. You may be. Further, the polyarylate resin (PA) is added to at least one of the repeating units (30A) and (30B), the repeating unit (31) and at least one of the repeating units (32A) and (32B), and these repetitions. It may further include repeating units other than the unit. The number of at least one of the repeating units (30A) and (30B), the number of repeating units (31), and the number of repeating units (32A) and (32B) with respect to the number of all repeating units contained in the polyarylate resin (PA). The total ratio with the number of at least one kind is preferably 0.80 or more, more preferably 0.90 or more, and further preferably 1.00.

The photosensitive layer may contain only one type of polyarylate resin (PA) as the binder resin. Alternatively, the photosensitive layer may contain two or more types of polyarylate resin (PA) as the binder resin. Further, the photosensitive layer may contain only polyarylate resin (PA) as the binder resin. Alternatively, the photosensitive layer may further contain a binder resin other than the polyarylate resin (PA) as the binder resin in addition to the polyarylate resin (PA).

The viscosity average molecular weight of the polyarylate resin (PA) is preferably 10,000 or more, more preferably 20,000 or more, and even more preferably 30,000 or more. When the viscosity average molecular weight of the polyarylate resin (PA) is 10,000 or more, the photosensitive layer is less likely to wear. On the other hand, the viscosity average molecular weight of the polyarylate resin (PA) is preferably 80,000 or less, more preferably 70,000 or less, and further preferably 40,000 or less. When the viscosity average molecular weight of the polyarylate resin (PA) is 80,000 or less, the polyarylate resin (PA) is easily dissolved in the solvent for forming the photosensitive layer, and the photosensitive layer is easily formed.

The method for producing the polyarylate resin (PA) is not particularly limited. Examples of the method for producing the polyarylate resin (PA) include a method of polycondensing an alcohol for forming a repeating unit and a carboxylic acid for forming the repeating unit. As a method for polycondensation, a known synthesis method (more specifically, solution polymerization, melt polymerization, interfacial polymerization, etc.) can be adopted.

Examples of alcohols for constituting the repeating unit are described as compounds represented by the chemical formulas (BP-30A) and (BP-30B) (hereinafter, they are referred to as compounds (BP-30A) and (BP-30B), respectively. There are times).

Examples of the carboxylic acid for constituting the repeating unit include compounds represented by the chemical formulas (DC-31), (DC-32A) and (DC-32B) (hereinafter, each of which is compound (DC-31), ( DC-32A) and (DC-32B) may be described).

The alcohol used to form the repeating unit may be transformed into an aromatic diacetate and used. Further, the carboxylic acid for forming the repeating unit may be derivatized and used. Examples of carboxylic acid derivatives include dicarboxylic acid dichloride, dicarboxylic acid dimethyl ester, dicarboxylic acid diethyl ester and dicarboxylic acid anhydride. A dicarboxylic acid dichloride is a compound in which two "-C (= O) -OH" groups of a dicarboxylic acid are each substituted with a "-C (= O) -Cl" group.

In the polycondensation of alcohol and carboxylic acid, one or both of the base and the catalyst may be added. The base and catalyst can be appropriately selected from known bases and catalysts. Examples of bases include sodium hydroxide. Examples of catalysts include benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salts, triethylamine and trimethylamine.

(Charge generator)
Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaline pigments, indigo pigments, azulenium pigments, and cyanine. Pigments, powders of inorganic photoconductive materials (eg, selenium, selenium-tellu, selenium-arsenic, cadmium sulfide or amorphous silicon), pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, slen pigments, toluidine pigments, Examples thereof include pyrazoline pigments and quinacridone pigments. The photosensitive layer may contain only one type of charge generating agent, or may contain two or more types.

Examples of the phthalocyanine pigment include metal-free phthalocyanine and metal phthalocyanine. Examples of the metallic phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine and chlorogallium phthalocyanine. Titanyl phthalocyanine is represented by, for example, the chemical formula (CGM1). The metal-free phthalocyanine is represented by, for example, the chemical formula (CGM2).

The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape of the phthalocyanine pigment (for example, α-type, β-type, Y-type, V-type or II-type) is not particularly limited, and phthalocyanine-based pigments having various crystal shapes are used. Examples of the crystal of the metal-free phthalocyanine include an X-type crystal of the metal-free phthalocyanine (hereinafter, may be referred to as an X-type metal-free phthalocyanine). Examples of the crystals of titanyl phthalocyanine include α-type, β-type and Y-type crystals of titanyl phthalocyanine (hereinafter, each may be referred to as α-type, β-type and Y-type titanyl phthalocyanine).

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

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

An example of a method for measuring the CuKα characteristic X-ray diffraction spectrum will be described. A sample (titanyl phthalocyanine) is filled in a sample holder of an X-ray diffractometer (for example, "RINT (registered trademark) 1100" manufactured by Rigaku Co., Ltd.), and an X-ray tube Cu, a tube voltage of 40 kV, a tube current of 30 mA, and CuKα The X-ray diffraction spectrum is measured under the condition of a characteristic X-ray wavelength of 1.542 Å. 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 ° / min.

Ansanthron pigments are preferably used as the charge generator in the photoconductor applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of 350 nm or more and 550 nm or less).

The content of the charge generator is preferably 0.1 part by mass or more and 50 parts by mass or less, and 0.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the photosensitive layer. It is more preferable that the amount is 1 part by mass or more and 5 parts by mass or less.

(Combination of materials)
In order to suppress the generation of a ghost image in the formed image, the binder resin, the electron transporting agent and the hole transporting agent are preferably any of the following combinations. Further, it is more preferable that the binder resin, the electron transporting agent and the hole transporting agent are any of the following combinations, and the charge generating agent is X-type metal-free phthalocyanine.

Is the binder resin a polyarylate resin (PA-1), the electron transport agent is a compound (E-1), and the hole transport agent is a compound (H-1);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent is a compound (E-1), and the hole transport agent is a compound (H-2);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-3);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-4);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-5);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-7);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-8);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-10);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-11);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-12);
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-1)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-2)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-3)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-4)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-5)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-6)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-7)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-8)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-9)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-10)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-11)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-12)?
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-1);
Whether the binder resin is a polyarylate resin (PA-1), the electron transporting agent is the compound (E-3), and the hole transporting agent is the compound (H-2);
Is the binder resin a polyarylate resin (PA-1), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-3);
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-4)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-5)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-6)?
Is the binder resin a polyarylate resin (PA-1), the electron transport agent is compound (E-3), and the hole transport agent is compound (H-7)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-8)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-9)?
Is the binder resin a polyarylate resin (PA-1), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-10)?
Whether the binder resin is a polyarylate resin (PA-1), the electron transport agent is a compound (E-3), the hole transport agent is a compound (H-11); or the binder resin is a polyarylate resin ( PA-1), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-12).

In order to suppress the generation of a ghost image in the formed image, it is also preferable that the binder resin, the electron transporting agent and the hole transporting agent are any of the following combinations. Further, it is more preferable that the binder resin, the electron transporting agent and the hole transporting agent are any of the following combinations, and the charge generating agent is X-type metal-free phthalocyanine.

Is the binder resin a polyarylate resin (PA-2), the electron transporting agent is compound (E-1), and the hole transporting agent is compound (H-1);
Whether the binder resin is a polyarylate resin (PA-2), the electron transporting agent is the compound (E-1), and the hole transporting agent is the compound (H-2);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-3)?
Is the binder resin a polyarylate resin (PA-2), the electron transporting agent is compound (E-1), and the hole transporting agent is compound (H-4)?
Whether the binder resin is a polyarylate resin (PA-2), the electron transporting agent is the compound (E-1), and the hole transporting agent is the compound (H-5);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-7)?
Is the binder resin a polyarylate resin (PA-2), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-8);
Whether the binder resin is a polyarylate resin (PA-2), the electron transporting agent is the compound (E-1), and the hole transporting agent is the compound (H-9);
Is the binder resin a polyarylate resin (PA-2), the electron transporting agent is compound (E-1), and the hole transporting agent is compound (H-10)?
Is the binder resin a polyarylate resin (PA-2), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-11)?
Is the binder resin a polyarylate resin (PA-2), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-12)?
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-1);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent is a compound (E-2), and the hole transport agent is a compound (H-2);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-3);
Is the binder resin a polyarylate resin (PA-2), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-4)?
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-5);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-7);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-8);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-10);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-11);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-12);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-1);
Is the binder resin a polyarylate resin (PA-2), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-2)?
Is the binder resin a polyarylate resin (PA-2), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-3)?
Whether the binder resin is a polyarylate resin (PA-2), the electron transporting agent is the compound (E-3), and the hole transporting agent is the compound (H-4);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-5);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-7);
Is the binder resin a polyarylate resin (PA-2), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-8);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-2), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-10);
Whether the binder resin is a polyarylate resin (PA-2), the electron transport agent is a compound (E-3), the hole transport agent is a compound (H-11); or the binder resin is a polyarylate resin ( PA-2), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-12).

In order to suppress the generation of a ghost image in the formed image, it is also preferable that the binder resin, the electron transporting agent and the hole transporting agent are any of the following combinations. Further, it is more preferable that the binder resin, the electron transporting agent and the hole transporting agent are any of the following combinations, and the charge generating agent is X-type metal-free phthalocyanine.

Is the binder resin a polyarylate resin (PA-3), the electron transporting agent is compound (E-1), and the hole transporting agent is compound (H-1)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-2)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-3)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-4)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-5)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-7)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-8)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-10)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-11)?
Is the binder resin a polyarylate resin (PA-3), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-12)?
Whether the binder resin is a polyarylate resin (PA-3), the electron transporting agent is the compound (E-2), and the hole transporting agent is the compound (H-1);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-2);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-3);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-4);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-5);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-7);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-8);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-10);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-11);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-12);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-1);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-2);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-3);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-4);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-5);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-7);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-8);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-3), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-10);
Whether the binder resin is a polyarylate resin (PA-3), the electron transport agent is a compound (E-3), and the hole transport agent is a compound (H-11); or the binder resin is a polyallylate resin ( PA-3), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-12).

In order to suppress the generation of a ghost image in the formed image, it is also preferable that the binder resin, the electron transporting agent and the hole transporting agent are any of the following combinations. Further, it is more preferable that the binder resin, the electron transporting agent and the hole transporting agent are any of the following combinations, and the charge generating agent is X-type metal-free phthalocyanine.

Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-1);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-2)?
Is the binder resin a polyarylate resin (PA-4), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-3)?
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-4);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-5);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-7);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-8);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-1), and the hole transport agent a compound (H-10);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-11)?
Is the binder resin a polyarylate resin (PA-4), the electron transport agent is compound (E-1), and the hole transport agent is compound (H-12)?
Is the binder resin a polyarylate resin (PA-4), the electron transport agent is compound (E-2), and the hole transport agent is compound (H-1)?
Is the binder resin a polyarylate resin (PA-4), the electron transporting agent is compound (E-2), and the hole transporting agent is compound (H-2)?
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-3);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-4);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-5);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-7);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-8);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-10);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-11);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-2), and the hole transport agent a compound (H-12);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-1);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-2);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-3);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-4);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-5);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-6);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-7);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-8);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-9);
Is the binder resin a polyarylate resin (PA-4), the electron transport agent a compound (E-3), and the hole transport agent a compound (H-10);
Whether the binder resin is a polyarylate resin (PA-4), the electron transport agent is a compound (E-3), the hole transport agent is a compound (H-11); or the binder resin is a polyarylate resin ( PA-4), the electron transporting agent is compound (E-3), and the hole transporting agent is compound (H-12).

(Additive)
Additives include, for example, antioxidants (eg, antioxidants, radical scavengers, singlet quenchers or UV absorbers), softeners, surfactants, bulking agents, thickeners, dispersion stabilizers. , Waxes, acceptors, donors, surfactants, plasticizers, sensitizers and leveling agents. Antioxidants include, for example, hindered phenol (eg, di (tert-butyl) p-cresol), hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organosulfur compounds and Examples include organic phosphorus compounds.

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

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

<Middle layer>
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (resin for the intermediate layer) used for the intermediate layer. It is considered that the presence of the intermediate layer smoothes the flow of the current generated when the photoconductor is exposed while maintaining an insulating state to the extent that leakage can be suppressed, and suppresses an increase in resistance.

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

The resin for the intermediate layer is not particularly limited as long as it can be used as the resin for forming the intermediate layer. The intermediate layer may contain additives. The example of the additive contained in the intermediate layer is the same as the example of the additive contained in the photosensitive layer.

<Manufacturing method of photoconductor>
The photoconductor is manufactured, for example, as follows. The photoconductor is produced by applying a coating liquid for a photosensitive layer on a conductive substrate and drying the photoconductor. The coating liquid for a photosensitive layer is produced by dissolving or dispersing a charge generator, an electron transporting agent, a binder resin, a hole transporting agent, and a component (for example, an additive) added as needed in a solvent. ..

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

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

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

The method for applying the coating liquid for the photosensitive layer is not particularly limited as long as the coating liquid can be uniformly applied on the conductive substrate. Examples of the coating method include a blade coating method, a dip coating method, a spray coating method, a spin coating method and a bar coating method.

The method for drying the coating liquid for the photosensitive layer is not particularly limited as long as the solvent in the coating liquid can be evaporated. For example, a method of heat treatment (hot air drying) using a high temperature dryer or a vacuum dryer can be mentioned. The heat treatment temperature is, for example, 40 ° C. or higher and 150 ° C. or lower. The heat treatment time is, for example, 3 minutes or more and 120 minutes or less.

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

<Image forming device>
Hereinafter, an image forming apparatus including the photoconductor of the present embodiment will be described. Hereinafter, as one aspect of the image forming apparatus including the photoconductor of the present embodiment, a tandem type color image forming apparatus will be described as an example with reference to FIG.

The image forming apparatus 100 shown in FIG. 5 includes image forming units 40a, 40b, 40c and 40d, a transfer belt 50, and a fixing portion 52. Hereinafter, when it is not necessary to distinguish between them, each of the image forming units 40a, 40b, 40c and 40d will be referred to as an image forming unit 40.

The image forming unit 40 includes an image carrier 30, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. The image carrier 30 is the photoconductor 1 of the present embodiment. The photoconductor 1 is provided at the center position of the image forming unit 40. The photoconductor 1 is provided so as to be rotatable in the arrow direction (counterclockwise). Around the photoconductor 1, a charged unit 42, an exposed unit 44, a developing unit 46, and a transfer unit 48 are provided in order from the upstream side in the rotation direction of the photoconductor 1 with reference to the charged unit 42. The image forming unit 40 may be further provided with one or both of a cleaning unit (not shown) and a static elimination unit (not shown).

Each of the image forming units 40a to 40d superimposes toner images of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) on the recording medium P on the transfer belt 50 in order.

The charging unit 42 charges the surface 1a (for example, the peripheral surface) of the photoconductor 1. The charging polarity of the charging unit 42 is positive. That is, the charging unit 42 charges the surface 1a of the photoconductor 1 positively. The charging unit 42 is a charging roller. The charging roller charges the surface 1a of the photoconductor 1 while contacting the surface 1a of the photoconductor 1. That is, the image forming apparatus 100 employs a contact charging method. Examples of the charging part of the contact charging method other than the charging roller include a charging brush. The charged portion may be of a non-contact type. Examples of the non-contact type charging unit include a corotron charging device and a scorotron charging device.

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

The developing unit 46 supplies toner to the surface 1a of the photoconductor 1 and develops the electrostatic latent image as a toner image. The photoconductor 1, which is the image carrier 30, carries a toner image. The toner may be used as a one-component developer. Alternatively, the toner and the desired carrier may be mixed and the toner may be used in the two-component developer. When the toner is used as the one-component developer, the developing unit 46 supplies the toner, which is the one-component developer, to the electrostatic latent image formed on the photoconductor 1. When the toner is used in the two-component developer, the developing unit 46 supplies the electrostatic latent image formed on the photoconductor 1 with the toner among the toner and the carrier contained in the two-component developer.

The developing unit 46 can develop the electrostatic latent image as a toner image while contacting the surface 1a of the photoconductor 1. That is, the image forming apparatus 100 can adopt the contact developing method.

The developing unit 46 can clean the surface 1a of the photoconductor 1. That is, the image forming apparatus 100 can adopt a blade cleanerless method. In the case of a blade cleanerless image forming apparatus, the toner remaining on the surface of the photoconductor is not scraped off by the cleaning blade. Therefore, in a blade cleanerless type image forming apparatus, toner usually tends to remain on the surface of the photoconductor. The portion of the surface of the photoconductor to which the toner adheres is unlikely to be charged to a desired value, and image defects including a ghost image are likely to occur. Further, since the toner blocks the exposure light at the portion of the surface of the photoconductor to which the toner adheres, image defects including a ghost image are likely to occur. However, the photoconductor 1 of the present embodiment can suppress the generation of a ghost image in the formed image. Therefore, the image forming apparatus 100 provided with such a photoconductor 1 can suppress the occurrence of image defects including a ghost image even when the blade cleanerless method is adopted.

In order for the developing unit 46 to efficiently clean the surface 1a of the photoconductor 1 while developing, it is preferable to satisfy the following conditions (a) and (b).
Condition (a): A contact developing method is adopted, and a peripheral speed (rotational speed) difference is provided between the photoconductor 1 and the developing unit 46.
Condition (b): The surface potential of the photoconductor 1 and the potential of the development bias satisfy the following mathematical formulas (b-1) and (b-2).
0 (V) <Development bias potential (V) <Surface potential (V) of the unexposed region of the photoconductor 1 ... (b-1)
Development bias potential (V)> Surface potential (V)> 0 (V) ... (b-2) in the exposed region of the photoconductor 1.

When the contact developing method shown in the condition (a) is adopted and a peripheral speed difference is provided between the photoconductor 1 and the developing unit 46, the surface 1a of the photoconductor 1 comes into contact with the developing unit 46 and the photoconductor 1 Adhering components on the surface 1a of 1 are removed by friction with the developing unit 46. The peripheral speed of the developing unit 46 is preferably faster than the peripheral speed of the photoconductor 1.

In the condition (b), it is assumed that the development method is the reverse development method. In order to improve the sensitivity characteristics of the photoconductor 1, which is a single-layer electrophotographic photosensitive member, the charging polarity of the toner, the surface potential of the unexposed region of the photoconductor 1, the surface potential of the exposed region of the photoconductor 1, and the development bias It is preferable that all of the potentials of are positive. Regarding the surface potential of the unexposed region and the surface potential of the exposed region of the photoconductor 1, after the transfer unit 48 transfers the toner image from the photoconductor 1 to the recording medium P, the charged unit 42 of the photoconductor 1 in the next circuit. It is measured before charging the surface 1a.

When the mathematical formula (b-1) of the condition (b) is satisfied, the static electricity acting between the toner remaining on the photoconductor 1 (hereinafter, may be referred to as residual toner) and the unexposed region of the photoconductor 1 The repulsive force is larger than the electrostatic repulsive force acting between the residual toner and the developing unit 46. Therefore, the residual toner in the unexposed region of the photoconductor 1 moves from the surface 1a of the photoconductor 1 to the developing unit 46 and is recovered.

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

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

The transfer unit 48 transfers the toner image developed by the developing unit 46 from the surface 1a of the photoconductor 1 to the recording medium P. The transfer unit 48 transfers the toner image from the surface 1a of the photoconductor 1 to the recording medium P while bringing the surface 1a of the photoconductor 1 into contact with the recording medium P. That is, the image forming apparatus 100 employs a direct transfer method.

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 portion 52 is, for example, a heating roller and / or a pressure roller. By heating and / or pressurizing the toner image, the toner image is fixed on the recording medium P. As a result, an image is formed on the recording medium P.

Although an example of the image forming apparatus has been described above, the image forming apparatus is not limited to the above-mentioned image forming apparatus 100. The image forming apparatus 100 described above was a color image forming apparatus, but the image forming apparatus may be a monochrome image forming apparatus. In this case, the image forming apparatus may include, for example, only one image forming unit. Further, although the image forming apparatus 100 described above has adopted the tandem method, the image forming apparatus may adopt, for example, the rotary method.

<Process cartridge>
Next, an example of the process cartridge including the photoconductor 1 of the present embodiment will be described with reference to FIG. 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 includes a photoconductor 1 which is an image carrier 30. In addition to the photoconductor 1, the process cartridge may further include at least one selected from the group consisting of a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. The process cartridge may further include one or both of a cleaning unit (not shown) and a static elimination unit (not shown). The process cartridge is designed to be detachably attached to the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics of the photoconductor 1 deteriorates, the process cartridge including the photoconductor 1 can be easily and quickly replaced. As described above, the process cartridge including the photoconductor 1 of the present embodiment has been described with reference to FIG.

The photoconductor of the present embodiment described above can suppress the generation of a ghost image in the formed image. Further, by providing the photoconductor of the present embodiment in the process cartridge and the image forming apparatus, it is possible to suppress the generation of a ghost image in the formed image.

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

<Material for forming the photosensitive layer>
The following charge generators, hole transport agents, electron transport agents, and binder resins were prepared as materials for forming the photosensitive layer of the photoconductor.

(Charge generator)
X-type metal-free phthalocyanine was prepared as a charge generator.

(Hole transport agent)
As the hole transporting agent, the compounds (H-1) to (H-12) described in the embodiment were prepared. Further, as the hole transporting agent used in the comparative example, the compounds represented by the chemical formulas (Ha) to (Hd) (hereinafter, each of them will be referred to as compounds (Ha) to (Hd)). I also prepared.

(Electronic transport agent)
The compounds (E-1) to (E-3) described in the embodiment were prepared as electron transport agents. Further, as the electron transporting agent used in the comparative example, the compounds represented by the chemical formulas (Ea) to (Eb) (hereinafter, each of them shall be described as compounds (Ea) to (Eb). There is) also prepared.

(Binder resin)
As the binder resin, polyarylate resins represented by the following chemical formulas (R-1) to (R-4) (hereinafter, each of them may be described as polyarylate resins (R-1) to (R-4). ) Was synthesized by the method shown below. The polyarylate resins (R-1), (R-2), (R-3) and (R-4) are the polyarylate resins (PA-1), (PA-2), respectively described in the embodiments. It is a specific example of (PA-3) and (PA-4). The number attached to the lower right of each repeating unit indicates the percentage of the number of each repeating unit to the total number of repeating units.

(Synthesis of polyarylate resin (R-1))
A 1 L volume three-necked flask equipped with a thermometer, a three-way cock, and a dropping funnel was used as the reaction vessel. In a reaction vessel, 12.2 g (41.3 mmol) of compound (BP-30A), 1.65 g (0.25 mmol) of tert-butylphenol as a terminal terminator, and 3.9 g (98 mmol) of sodium hydroxide. , Benzyltributylammonium chloride 0.12 g (0.38 mmol) was added. Then, the air in the reaction vessel was replaced with argon gas. Then, 600 mL of water was put into the reaction vessel. The internal temperature of the reaction vessel was maintained at 20 ° C., and the contents of the reaction vessel were stirred for 1 hour. Next, the contents of the reaction vessel were cooled, and the internal temperature of the reaction vessel was lowered to 10 ° C. An alkaline aqueous solution was prepared in this way.

On the other hand, 4.8 g (16.2 mmol) of dicarboxylic acid dichloride of compound (DC-32B) and 4.1 g (16.2 mmol) of dicarboxylic acid dichloride of compound (DC-31) were dissolved in 300 g of chloroform. , Chloroform solution was prepared.

The chloroform solution was added to the alkaline aqueous solution while maintaining the temperature of the alkaline aqueous solution at 10 ° C. and stirring the contents of the reaction vessel. As a result, the polymerization reaction was started. Next, the contents of the reaction vessel were stirred for 3 hours while maintaining the internal temperature of the reaction vessel at 13 ± 3 ° C. After stirring, the upper layer (aqueous layer) was removed using a decant to obtain an organic layer. The obtained organic layer was put into 500 mL of ion-exchanged water to obtain a mixture. 300 g of chloroform and 6 mL of acetic acid were further added to the mixture to obtain a liquid. The solution was stirred at room temperature (25 ° C.) for 30 minutes. Then, the upper layer (aqueous layer) in the liquid was removed using a decant to obtain an organic layer. The organic layer obtained with 500 mL of ion-exchanged water was washed 8 times with a separating funnel. As a result, an organic layer washed with water was obtained. The organic layer washed with water was filtered to obtain a filtrate. The obtained filtrate was slowly added dropwise to 1.5 L of methanol to obtain a precipitate. The precipitate was removed by filtration. The obtained precipitate was vacuum dried at a temperature of 70 ° C. for 12 hours. As a result, a polyarylate resin (R-1) was obtained. The viscosity average molecular weight of the polyarylate resin (R-1) was 36,700.

(Synthesis of polyarylate resin (R-2))
The same method as the polyarylate resin (R-1) except that the dicarboxylic acid dichloride (16.2 mmol) of the compound (DC-32B) was changed to the dicarboxylic acid dichloride (16.2 mmol) of the compound (DC-32A). A polyarylate resin (R-2) was obtained. The viscosity average molecular weight of the polyarylate resin (R-2) was 32,400.

(Synthesis of polyarylate resin (R-3))
In the same manner as the polyarylate resin (R-1), except that 41.3 mmol of compound (BP-30A) was changed to 20.7 mmol of compound (BP-30A) and 20.7 mmol of (BP-30B). A polyarylate resin (R-3) was obtained. The viscosity average molecular weight of the polyarylate resin (R-3) was 31,600.

(Synthesis of polyarylate resin (R-4))
Converting 41.3 mmol of compound (BP-30A) to 20.7 mmol of compound (BP-30A) and 20.7 mmol of (BP-30B), and dicarboxylic acid dichloride (16.) of compound (DC-32B). The polyallylate resin (R-4) is obtained in the same manner as the polyallylate resin (R-1) except that the compound (DC-32A) is changed to the dicarboxylic acid dichloride (16.2 mmol). It was. The viscosity average molecular weight of the polyarylate resin (R-4) was 31,900.

Further, as a binder resin used in the comparative example, a polyarylate resin represented by the following chemical formula (RA) (hereinafter, may be referred to as a polyarylate resin (RA)) was also prepared. The number attached to the lower right of each repeating unit indicates the percentage of the number of each repeating unit to the total number of repeating units.

<Manufacturing of photoconductor>
Photoreceptors (A-1) to (A-21) and (B-1) to (B-10) were produced using the material for forming the photosensitive layer.

(Manufacturing of photoconductor (A-1))
In the container, 3.0 parts by mass of the charge generator, 65.0 parts by mass of the compound (H-1) as a hole transport agent, 25.0 parts by mass of the compound (E-1) as an electron transport agent, and a binder resin. 100.0 parts by mass of the polyarylate resin (R-1) as a solvent and 800.0 parts by mass of tetrahydrofuran as a solvent were added. The contents of the container were mixed using a ball mill for 50 hours to disperse the material in a solvent. As a result, a coating liquid for the photosensitive layer was obtained. Next, the prepared coating liquid for the photosensitive layer was applied onto the conductive substrate (drum-shaped support made of aluminum) by using the dip coating method. As a result, a coating film was formed on the conductive substrate. The conductive substrate on which the coating film was formed was dried at 130 ° C. for 60 minutes to remove tetrahydrofuran from the coating film. As a result, a single photosensitive layer (thickness 25 μm) was formed on the conductive substrate. As a result, a photoconductor (A-1) was obtained.

(Manufacturing of Photoreceptors (A-2) to (A-21) and (B-1) to (B-10))
Each of the photoconductors (A-2) to (A-21) and (B-1) to (B-10) is produced in the same manner as in the production of the photoconductor (A-1) except that the following points are changed. Manufactured. In the production of the photoconductor (A-1), 65.0 parts by mass of the compound (H-1) was used as the hole transport agent, but the photoconductors (A-2) to (A-21) and (B-) were used. In each of the productions 1) to (B-10), the hole transporting agents of the types and amounts shown in Tables 1 to 3 were used. In the production of the photoconductor (A-1), 25.0 parts by mass of the compound (E-1) was used as the electron transporting agent, but the photoconductors (A-2) to (A-21) and (B-1) were used. ) To (B-10), the types and amounts of electron transporting agents shown in Tables 1 to 3 were used. In the production of the photoconductor (A-1), 100.0 parts by mass of the polycarbonate resin (R-1) was used as the binder resin, but the photoconductors (A-2) to (A-21) and (B-1) were used. ) To (B-10), 100.0 parts by mass of binder resins of the types shown in Tables 1 to 3 were used.

<Measurement of charging potential difference V _01- V ₀₂ and post-exposure potential difference V _L2- V _L1 >
In the same manner as the measuring method of charging potential V ₀₁ -V ₀₂ and post-exposure potential V _L2 -V _L1 described in embodiments, photoconductive (A-1) ~ (A -21) and (B-1) ~ ( The charging potential difference V _01- V ₀₂ and the post-exposure potential difference V _L2- V _L1 of each of B-10) were measured. A drum sensitivity tester (manufactured by Gentec Co., Ltd.) was used as the measuring device. As the potential measurement probe, "MODEL1017AS" manufactured by Monore Electronics was used. The measured charging potential difference V _01- V ₀₂ and the post-exposure potential difference V _L2- V _L1 are shown in Tables 1 to 3.

<Evaluation of ghost image>
It was evaluated whether or not the generation of ghost images was suppressed for each of the photoconductors (A-1) to (A-21) and (B-1) to (B-10). The ghost image is evaluated in an environment with a temperature of 32.5 ° C and a relative humidity of 80% RH (high temperature and high humidity environment, hereinafter referred to as HH environment), and an environment with a temperature of 10.0 ° C and a relative humidity of 10% RH (referred to as HH environment). It was carried out in a low temperature and low humidity environment (hereinafter referred to as LL environment).

First, the evaluation image 60 used for evaluating the ghost image will be described with reference to FIG. FIG. 6 shows an evaluation image 60. The evaluation image 60 includes a first region 61, a second region 62, and a third region 63. The first region 61, the second region 62, and the third region 63 correspond to the regions of the images formed on the first, second, and third laps of the image carrier 30 (see FIG. 5), respectively. The first region 61 includes a first image 64 and a second image 65. The first image 64 includes a first solid image 64a (image density 100%) and a first blank image 64b. The first solid image 64a has a circular shape. The first blank image 64b is the background of the first solid image 64a. The second image 65 includes a second blank image 65a and a second solid image 65b (image density 100%). The second blank image 65a has a circular shape. The second solid image 65b is the background of the second blank image 65a. The second region 62 includes the third image 66. The third image 66 is a full-face halftone image (image density 50%). The third region 63 includes the fourth image 67. The fourth image 67 is a full-face halftone image (image density 50%).

Next, the image 70 in which the ghost image is generated will be described with reference to FIG. 7. The image 70 is the first region 61, the second region 62, the third region 63, the first image 64, the first solid image 64a, the first blank image 64b, the second image 65, and the first image 60 described in the evaluation image 60. 2 Includes a blank image 65a, a second solid image 65b, a third image 66, and a fourth image 67.

When the evaluation image 60 is printed and a ghost image is generated, the third image 66 should be printed in the second area 62, but the ghost image G1 and the ghost image are in the third image 66 in the second area 62. One or both of G2 appear. The image densities of the ghost image G1 and the ghost image G2 are higher than those of the third image 66, respectively. The ghost image G1 is an image defect caused by the exposure memory, which is darker than the design image density reflecting the first solid image 64a in the exposure region of the first image 64. The ghost image G2 is an image defect caused by the transfer memory, which is darker than the design image density reflecting the second blank image 65a in the non-exposed region of the second image 65.

When the evaluation image 60 is printed and a ghost image is generated, the fourth image 67 should be printed in the third area 63, but the ghost image G3 and the ghost image are in the fourth image 67 in the third area 63. One or both of G4 appear. The image densities of the ghost image G3 and the ghost image G4 are higher than those of the fourth image 67, respectively. The ghost image G3 is an image defect caused by the exposure memory, which is darker than the design image density reflecting the first solid image 64a in the exposure region of the first image 64. The ghost image G4 is an image defect caused by the transfer memory, which is darker than the design image density reflecting the second blank image 65a in the non-exposed region of the second image 65. The evaluation image 60 and the image 70 in which the ghost image is generated have been described above.

Next, the photoconductor was attached to the evaluation machine for evaluation of the ghost image. As an evaluation machine, a modified machine of a color image forming apparatus (“FS-C5250DN” manufactured by Kyocera Document Solutions Co., Ltd.) was used. This evaluation machine adopted a direct transfer method. This evaluation machine was equipped with a charging roller as a charging unit. The charging potential was set to + 600V. This evaluation machine did not have a cleaning blade as a cleaning unit. This evaluation machine had a configuration in which the developing unit cleans the surface of the image carrier. This evaluation machine used a contact development method.

After printing image I (print pattern image with a printing rate of 1%) on 500 recording media (A4 size paper) using an evaluation machine, FIG. 6 shows on one recording medium (A4 size paper). The evaluation image 60 shown was printed. This operation was repeated 6 times in succession, and a total of 3000 images I and a total of 6 evaluation images 60 were obtained. The six evaluation images 60 obtained were observed with the naked eye, respectively, and it was confirmed whether or not the ghost images G1, G2, G3 and G4 shown in FIG. 7 were generated. From the confirmation results, it was evaluated whether or not the generation of ghost images was suppressed based on the following criteria. The worst result among the evaluation results of the six evaluation images 60 was taken as the evaluation result of the ghost image of each photoconductor. The evaluation results of the ghost images of each photoconductor under the HH environment and the evaluation results of the ghost images of each photoconductor under the LL environment are shown in Tables 1 to 3. Photoreceptors having evaluations A to B were evaluated as having suppressed generation of ghost images.

(Evaluation criteria for ghost images)
Evaluation A: No ghost images G1, G2, G3 and G4 were observed.
Evaluation B: One or both of the ghost images G1 and G2 were slightly observed. However, neither ghost images G3 nor G4 were observed.
Evaluation C: One or both of the ghost images G1 and G2 were clearly observed. However, neither ghost images G3 nor G4 were observed.
Evaluation D: One or both of the ghost images G1 and G2 were clearly observed. Furthermore, one or both of the ghost images G3 and G4 were observed.

<Evaluation of sensitivity characteristics>
Sensitivity characteristics were evaluated for each of the photoconductors (A-1) to (A-21) and (B-1) to (B-10). The sensitivity characteristics were evaluated in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH. First, the surface of the photoconductor was charged to + 620 V using a drum sensitivity tester (manufactured by Gentec Co., Ltd.). Next, monochromatic light (wavelength 780 nm, half width 20 nm, light energy 1.3 μJ / cm ² ) was extracted from the white light of the halogen lamp using a bandpass filter. The surface of the photoconductor was irradiated with the extracted monochromatic light. The surface potential of the photoconductor was measured 0.08 seconds after the start of irradiation. The measured surface potential was defined as the post-exposure potential ( _VLS , unit: + V) of the sensitivity characteristic. The post-exposure potentials ( _VLS ) of the measured sensitivity characteristics are shown in Tables 1 to 3.

In Tables 1 to 3, the resin, ETM, HTM, part, HH environment, and LL environment are binder resin, electron transporting agent, hole transporting agent, mass part, high temperature and high humidity environment, and low temperature and low humidity environment, respectively. Shown. In Tables 1 to 3, "30A / 30B" indicates that the repeating unit (30A) and (30B) are contained in the polyarylate resin as the repeating unit derived from alcohol. In Tables 1 to 3, "31 / 32A" indicates that the polyarylate resin contains repeating units (31) and (32A) as repeating units derived from carboxylic acid. In Tables 1 to 3, "31 / 32B" indicates that the polyarylate resin contains repeating units (31) and (32B) as repeating units derived from carboxylic acid.

In Tables 1 to 3, " _MHTM / _METM " indicates the ratio of the mass of the hole transporting agent to the mass of the electron transporting agent. "M _HTM / M _ETM " is calculated from the formula "M _HTM / M _ETM = amount of hole transport agent (M _HTM , unit: parts by mass) / amount of electron transport agent (M _ETM , unit: parts by mass)". I asked.

In Tables 1 to 3, "( _MHTM + M _ETM ) / M _Resin " indicates the ratio of the total mass of the hole transporting agent and the electron transporting agent to the mass of the binder resin. "(M _HTM + M _ETM ) / M _Resin " is calculated by the formula "(M _HTM + M _ETM ) / M _Resin = {Amount of hole transporter ( _MHTM , unit: parts by mass) + amount of electron transporter (M) _ETM , unit: parts by mass)} / amount of binder resin (M _Resin , unit: parts by mass) ”.

The photoconductors (A-1) to (A-21) each provided a conductive substrate and a single-layer photosensitive layer. The photosensitive layer contained a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The ratio of the mass of the hole transporting agent to the mass of the electron transporting agent M _HTM / M _ETM was 2.0 or more. The ratio of the total mass of the hole transporting agent and the electron transporting agent to the mass of the binder resin ( _MHTM + _METM ) / M _Resin was 0.80 or more and 1.20 or less. The charging potential difference V ₀₁ −V ₀₂ satisfied the mathematical formula (1) “+ 70V ≦ V ₀₁ −V ₀₂ ≦ + 90V”. The post-exposure potential difference V _L2- V _L1 satisfied the mathematical formula (2) "+ 5V ≤ V _L2- V _L1 ≤ + 14V". Therefore, as is clear from Tables 1 and 2, in the photoconductors (A-1) to (A-21), the evaluation of the ghost image in the HH environment is A or B, and the ghost in the HH environment. The generation of images was suppressed. Further, in the photoconductors (A-1) to (A-21), the evaluation of the ghost image in the LL environment was A or B, and the generation of the ghost image in the LL environment was suppressed. Further, in the photoconductors (A-1) to (A-21), the generation of ghost images was suppressed without impairing the sensitivity characteristics of the photoconductors.

On the other hand, in the photoconductor (B-1), the charging potential difference V ₀₁ −V ₀₂ exceeded +90 V, and the post-exposure potential difference V _L2- V _L1 exceeded + 14 V. Therefore, as is clear from Table 3, in the photoconductor (B-1), the evaluation of the ghost image in the HH environment was C, and the generation of the ghost image in the HH environment was not suppressed. Further, in the photoconductor (B-1), the evaluation of the ghost image in the LL environment was D, and the generation of the ghost image in the LL environment was not suppressed.

In each of the photoconductors (B-2), (B-3), (B-5) and (B-7), the post-exposure potential difference V _L2- V _L1 exceeded + 14 V. Therefore, as is clear from Table 3, in the photoconductors (B-2), (B-3), (B-5) and (B-7), the evaluation of the ghost image in the HH environment is C or D. Therefore, the generation of ghost images in the HH environment was not suppressed. Further, in the photoconductors (B-2), (B-3), (B-5) and (B-7), the evaluation of the ghost image in the LL environment is C or D, and the evaluation in the LL environment is C or D. The generation of ghost images was not suppressed.

In the photoconductor (B-4), the charging potential difference V _{01 −} V ₀₂ was less than + 70 V. Therefore, as is clear from Table 3, in the photoconductor (B-4), the evaluation of the ghost image in the HH environment was C, and the generation of the ghost image in the HH environment was not suppressed.

In the photoconductor (B-6), the charging potential difference V _{01 −} V ₀₂ exceeded + 90 V. Therefore, as is clear from Table 3, in the photoconductor (B-6), the evaluation of the ghost image in the LL environment was D, and the generation of the ghost image in the LL environment was not suppressed.

In the photoconductor (B-8), the ratio of the mass of the hole transporting agent to the mass of the electron transporting agent is less than 2.0, and the hole transporting agent and the electron transporting agent have a ratio of M _HTM / _METM to the mass of the binder resin. The total mass ratio (M _HTM + M _ETM ) / M _Resin was less than 0.80. Therefore, as is clear from Table 3, in the photoconductor (B-8), the evaluation of the ghost image in the HH environment was C, and the generation of the ghost image in the HH environment was not suppressed. Further, in the photoconductor (B-8), the evaluation of the ghost image in the LL environment was D, and the generation of the ghost image in the LL environment was not suppressed.

In the photoconductor (B-9), the ratio of the total mass of the hole transporting agent and the electron transporting agent to the mass of the binder resin ( _MHTM + _METM ) / M _Resin exceeded 1.20. Further, in the photoconductor (B-9), the charging potential difference V _{01 −} V ₀₂ was less than + 70 V. Therefore, as is clear from Table 3, in the photoconductor (B-9), the evaluation of the ghost image in the HH environment was D, and the generation of the ghost image in the HH environment was not suppressed. Further, in the photoconductor (B-9), the evaluation of the ghost image in the LL environment was C, and the generation of the ghost image in the LL environment was not suppressed.

In the photoconductor (B-10), the ratio of the mass of the hole transporting agent to the mass of the electron transporting agent M _HTM / M _ETM was less than 2.0. Further, in the photoconductor (B-10), the post-exposure potential difference V _L2- V _L1 was less than + 5 V. Therefore, as is clear from Table 3, in the photoconductor (B-10), the evaluation of the ghost image in the HH environment was C, and the generation of the ghost image in the HH environment was not suppressed. Further, in the photoconductor (B-10), the evaluation of the ghost image in the LL environment was D, and the generation of the ghost image in the LL environment was not suppressed.

From the above, it was shown that the photoconductor according to the present invention suppresses the generation of ghost images in the formed image. Further, it was shown that the process cartridge and the image forming apparatus according to the present invention suppress the generation of ghost images in the formed images.

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

1 Photoreceptor 1a Surface of photoconductor 2 Conductive substrate 3 Photosensitive layer 30 Image carrier 42 Charging part 44 Exposure part 46 Developing part 48 Transfer part 100 Image forming device P Recording medium

Claims (11)

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer.
The photosensitive layer is a single layer, and the photosensitive layer contains a charge generator, a hole transport agent, an electron transport agent, and a binder resin.
The ratio of the mass of the hole transporting agent to the mass of the electron transporting agent is 2.0 or more.
The ratio of the total mass of the hole transporting agent and the electron transporting agent to the mass of the binder resin is 0.80 or more and 1.20 or less.
While rotating the electrophotographic photosensitive member 5 times, it is charged under a predetermined charging condition in the 1st lap, exposed under a predetermined exposure condition in the 2nd, 3rd and 4th laps, and the 5th lap. The predetermined charging condition is a condition in which the wire current is a DC current of +180 μA and the grid bias is +540 V, and the predetermined exposure condition is that the wavelength of the exposure light is 780 nm and the exposure light. The difference V ₀₁ −V ₀₂ between the charging potential V ₀₁ in the first lap and the charging potential V ₀₂ in the fifth lap is the following formula (1) under the condition that the amount of light of is 1.2 μJ / cm ^2. the filled, difference V _L2 -V _L1 between the potential after exposure V _L2 and the potential after exposure V _L1 in the fourth lap of the second lap meets the following equation (2),
The hole transporting agent contains a compound represented by the general formula (10), (11), (12), (13) or (14).
The electron transporting agent contains a compound represented by the general formula (20), (21) or (22).
The binder resin is an electrophotographic photosensitive member containing a polyarylate resin represented by the chemical formulas (R-1), (R-2), (R-3) or (R-4) .
+ 70V ≤ V ₀₁ -V ₀₂ ≤ + 90V ... (1)
+ 5V ≤ V _L2 −V _L1 ≤ + 14V ・ ・ ・ (2)

(In the general formula (10),
R ¹ and R ² independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms.
a ₁ and a ₂ each independently represent an integer of 0 or more and 5 or less.
R ³ and R ⁴ may independently have an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms, or −CR ⁵ = CR ⁶ R ⁷ Represents
R ⁵ , R ⁶ and R ⁷ each independently represent an alkyl group having 1 or more and 6 or less carbon atoms or a phenyl group or a hydrogen atom which may have an alkoxy group having 1 or more and 6 or less carbon atoms.
W represents a single bond or a p-phenylene group. )

(In the general formula (11),
R ¹¹ , R ¹² , R ¹³ and R ¹⁴ independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms.
b ₁ , b ₂ , b ₃ and b ₄ each independently represent an integer of 0 or more and 5 or less. )

(In the general formula (12),
R ²¹ , R ²² and R ²³ independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms.
e ₁ , e ₂ and e ₃ each independently represent an integer of 0 or more and 5 or less.
R ²⁴ and R ²⁵ each independently represent an alkyl group having 1 or more and 6 or less carbon atoms, a phenyl group which may have an alkoxy group having 1 or more and 6 or less carbon atoms, or a hydrogen atom. )

(In the general formula (13),
R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms.
f ₁ , f ₂ , f ₃ , f ₄ and f ₅ each independently represent an integer of 0 or more and 5 or less. )

(In the general formula (14),
R ⁴¹ , R ⁴² and R ⁴³ independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms.
g1, g ₂ and g ₃ are each independently an integer of 0 to 5. )

(In the general formula (20), Q ¹ and Q ² independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms.)

(In the general formula (21), Q ¹¹ and Q ¹² each independently have an alkyl group having 1 or more and 6 or less carbon atoms or a phenyl group having 1 or more and 6 or less carbon atoms. Represent.)

(In the general formula (22), Q ²¹ and Q ²² independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms, and Q ²³ is a halogen atom. Represents a phenyl group which may have.)

The hole transporting agent contains a compound represented by the general formula (10), and in the general formula (10), R ¹ And R ² Independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms. ₁ And a ₂ Represent each 1 and R ³ And R ^Four The electrophotographic photosensitive member according to claim 1, wherein each represents a phenyl group which may have an alkyl group having 1 or more carbon atoms and 6 or less carbon atoms, and W represents a p-phenylene group. The hole transporting agent has chemical formulas (H-1), (H-2), (H-3), (H-4), (H-5), (H-6), (H-7), and more. The electrophotographic photosensitive member according to claim 1, which comprises a compound represented by (H-8), (H-9), (H-10), (H-11) or (H-12).

The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the hole transporting agent contains a compound represented by the chemical formula (H-5) or (H-6).

The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the electron transporting agent contains a compound represented by a chemical formula (E-1), (E-2) or (E-3).

The hole transporting agent contains a compound represented by the general formula (10), and in the general formula (10), R ¹ And R ² Independently represent an alkyl group having 1 or more and 6 or less carbon atoms or an alkoxy group having 1 or more and 6 or less carbon atoms. ₁ And a ₂ Represent each 1 and R ³ And R ^Four Represents a phenyl group which may have an alkyl group having 1 or more carbon atoms and 6 or less carbon atoms, and W represents a p-phenylene group.
The electrophotographic photosensitive member according to claim 1 or 2, wherein the electron transporting agent contains a compound represented by a chemical formula (E-1), (E-2) or (E-3).

A process cartridge comprising the electrophotographic photosensitive member according to any one of claims 1 to 6. Image carrier and
A charged portion that charges the surface of the image carrier and
An exposed portion that exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier.
A developing unit that develops the electrostatic latent image as a toner image,
An image forming apparatus including a transfer unit that transfers the toner image from the image carrier to a recording medium.
The charging polarity of the charged portion is positive and positive.
The transfer unit transfers the toner image from the image carrier to the recording medium while bringing the surface of the image carrier into contact with the recording medium.
The image forming apparatus, wherein the image carrier is the electrophotographic photosensitive member according to any one of claims 1 to 6. The image forming apparatus according to claim 8, wherein the charging unit is a charging roller. The image forming apparatus according to claim 8 or 9, wherein the developing unit develops the electrostatic latent image as the toner image while contacting the surface of the image carrier. The image forming apparatus according to any one of claims 8 to 10, wherein the developing unit cleans the surface of the image carrier.

Images