JP2015132655A - Electrophotographic photoreceptor, electrophotographic photoreceptor cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having high responsiveness enduring high-speed printing and satisfactory wear resistance essential for long-term use, while reducing image density changes due to external-light exposure, an electrophotographic photoreceptor cartridge, and an image forming apparatus.SOLUTION: An electrophotographic photoreceptor having a photosensitive layer formed on a conductive support simultaneously contains, in an outermost layer, a charge transport material represented by a formula (1), a hindered phenolic compound having a specific structure, and an amine compound.

Description

  The present invention relates to an electrophotographic photosensitive member having excellent electrical characteristics and stability upon exposure to light, an electrophotographic photosensitive member cartridge produced using the electrophotographic photosensitive member, and an image forming apparatus.

The electrophotographic technology is widely used as a copying machine, a printer, and a printing machine because a high-quality image can be obtained immediately. The electrophotographic photoreceptor (hereinafter referred to as “photoreceptor” as appropriate), which is the core of electrophotographic technology, is a photosensitive material that uses organic photoconductive materials and has the advantages of being pollution-free and easy to form and manufacture. The body is widely used.
Electrophotographic image forming apparatuses are required to have higher image quality, higher speed, and higher durability year by year. Processes around the photoconductor such as charging, exposure, development, and transfer have been improved to meet these requirements, but there are still many cases where improvement of the photoconductor itself is still necessary.

For example, in order to meet the demand for higher speed, it is necessary to increase the electrical responsiveness by quickly attenuating the surface potential in a short time from exposure to development. In order to increase the electrical responsiveness of the photoreceptor, it is usually necessary to increase the ratio of the charge transport material to the binder resin in the photosensitive layer and increase the charge mobility. The entanglement density of the binder resin is reduced, whereby the photosensitive layer is easily worn and cannot meet the demand for high durability. In such a situation, it has a large conjugated system as described in Patent Document 1. Since the charge transport material exhibits a large charge mobility and a very low residual potential, it has a possibility of achieving both electrical properties and wear resistance. In addition to the mechanical properties described above, it is also important to improve the chemical durability in order to develop a high-quality and long-life photoconductor, in order to prevent deterioration due to acid gas generated in the machine. Antioxidants as described in Patent Documents 2 to 4 have been added.

Japanese Patent Laid-Open No. 9-292724 JP 2000-241998 A JP-A-4-308852 JP-A-4-328852

  According to the study by the inventors, the charge transport material described in Patent Document 1 has a small polarity as a molecule and a large conjugated system, so that it is sufficiently large in the film thickness direction even when dispersed in a binder resin. Has charge mobility. However, when the charge transport material described in Patent Document 1 is used for the outermost photosensitive layer, the surface electrical resistance (hereinafter referred to as “surface resistance” as appropriate) is reduced, and white light, ultraviolet light, etc. Unexpected light exposure (hereinafter referred to as external light exposure) during non-image formation during manufacture, maintenance, etc. of the photoconductor / cartridge / image forming apparatus causes the surface resistance of the portion to It was found that there is a problem that it is lower than that.

Even if the surface resistance value of the outermost photosensitive layer is small, the surface resistance value is uniform over the entire image area, and there is no problem if the image does not flow. However, when the surface resistance is partially reduced by exposure to external light, the problem shown in FIG. 1 occurs. That is, in order to express a halftone, after irradiating a dot pattern with a size of several μm to several tens of μm, the charge of the portion that should originally be a white background (highly charged portion) is partially directed to the black background (low charged portion). Will move to. As a result, the potential of the area between the dots, which should originally be a white background, decreases, as shown in FIG. 2, the dots become thick after development, and when viewed macroscopically, only the portion exposed to external light, The halftone image density becomes high, and the uniformity of image quality is impaired as density unevenness.

  The surface resistance of the photosensitive layer is not necessarily proportional to the charge mobility in the film thickness direction. The degree of segregation on the surface due to the degree of compatibility of the charge transport material with the binder resin and the charge on the surface. Since it depends on the orientation state of the transport material, etc., the surface resistance is not always low for all materials having high mobility in the film thickness direction. Further, as described above, the phenomenon in which the surface resistance is reduced by exposure to external light also depends on the structure of the charge transport material, and this phenomenon is also observed in the charge transport material described in Patent Document 1.

  Regarding the change in the surface resistance of the photoreceptor, Patent Documents 2 to 4 disclose that an antioxidant is added to improve image flow prevention due to a decrease in surface resistance under high temperature and high humidity. However, these documents do not describe a change in surface resistance due to exposure to external light, and do not disclose a solution for that purpose. In addition, as a countermeasure against external light exposure, a light absorber and a light shielding agent are generally used, but this does not exclusively control the surface resistance of the surface of the photosensitive layer, but a photochemical reaction generated by a photochemical reaction. This is a measure for suppressing an increase in volume resistance and an increase in residual potential due to charge trapping in the layer bulk, and the technical idea is different from the measure for reducing surface resistance of the present application.

  The present invention has been made in view of the above-described background art, and its problem is that it has high response that can withstand high-speed printing and sufficient wear resistance that is indispensable for long life use, and image density due to exposure to external light. An object of the present invention is to provide an electrophotographic photosensitive member with small fluctuation.

  As a result of intensive studies, the inventor has added a hindered phenol compound and an amine compound having a specific structure in the photosensitive layer at the same time, while maintaining sufficient abrasion resistance essential for long life use. Therefore, it is possible to provide an electrophotographic photosensitive member, an electrophotographic photosensitive member cartridge, and an image forming apparatus that do not adversely affect the electrical characteristics, have a small change in surface resistance due to exposure to external light, and are less likely to cause image unevenness. The headline, the following invention was completed.

The gist of the present invention resides in the following <1> to <5>.
<1> In an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, a charge transport material represented by the following formula (1) in the outermost layer and a partial structure represented by the following formula (2): An electrophotographic photosensitive member comprising a hindered phenol compound having an amine compound represented by the following formula (3) in the same layer.

(In Formula (1), Ar < ¹ > -Ar < ⁵ > represents the aryl group which may each independently have a substituent, and Ar < ⁶ > -Ar < ⁹ > may each independently have a substituent. Represents an arylene group, and m and n each independently represents an integer of 1 to 3.

(In formula (2), R ¹ and R ² represent an alkyl group which may have a substituent. However, when both R ¹ and R ² are methyl groups, they are represented by formula (2). (There is only one partial structure in the molecule.)

(In the formula (3), R ³ , R ⁴ and R ⁵ represent an alkylene group having 3 or less carbon atoms which may have a substituent, Ar ¹⁰ and Ar ¹¹ have a hydrogen atom and a substituent. An alkyl group that may be substituted or an aryl group that may have a substituent, Ar ¹² represents an aryl group that may have a substituent, and k represents an integer of 1 or 2.
<2> The formula (1) is a compound represented by the following formula (1a), and a hindered phenol compound having a partial structure represented by the formula (2) is represented by the following formula (2) -1 or ( 2) The electrophotographic photoreceptor according to <1>, which is a compound represented by -4, and wherein the amine compound represented by the formula (3) is a compound represented by the following formula (3) -1.

(In Formula (1a), R ^a represents an alkyl group, an alkoxy group, an aryloxy group, or an aralkyloxy group, and R ^{b to} R ^e each independently represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. )

<3> The electrophotographic photosensitive member according to <1> or <2>, which is used in a contact charging process.
<4> The electrophotographic photosensitive member according to any one of <1> to <3>, a charging device for charging the electrophotographic photosensitive member, and exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. An electrophotographic photosensitive member cartridge comprising: an exposure device to be formed; and at least one selected from the group consisting of a developing device for developing an electrostatic latent image formed on the electrophotographic photosensitive member. <5> The electrophotographic photosensitive member according to any one of <1> to <3>, a charging device that charges the electrophotographic photosensitive member, and an electrostatic latent image formed by exposing the charged electrophotographic photosensitive member An image forming apparatus comprising: an exposure device that performs the above-described processing; and a developing device that develops the electrostatic latent image formed on the electrophotographic photosensitive member.

  The present invention maintains an adequate wear resistance essential for long life use, has a small change in surface resistance due to exposure to external light, and does not adversely affect electrical characteristics, and is less likely to cause image unevenness. It is possible to provide a photographic photosensitive member cartridge and an image forming apparatus.

FIG. 5 is a conceptual diagram for explaining that a potential decrease in a white background portion occurs due to a decrease in surface resistance of a photoreceptor due to external exposure exposure and movement of a charged charge in the surface direction. It is a conceptual diagram for explaining that dot thickening and halftone image density increase occur due to a decrease in surface resistance of the photoreceptor due to exposure to external exposure. 1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and is appropriately modified and implemented without departing from the spirit of the present invention. can do.

<Charge transport material of the present invention>
The charge transport material of the present invention is represented by the following formula (1).

(Formula (1) Ar ^{1 to} Ar ⁵ each independently represents an aryl group which may have a substituent, and Ar ^{6 to} Ar ⁹ each independently represents an arylene group which may have a substituent. M and n each independently represents an integer of 1 to 3.
In the above formula (1), Ar ^{1 to} Ar ⁵ each independently represents an aryl group which may have a substituent. The number of carbon atoms of the aryl group is 30 or less, preferably 20 or less, more preferably 15 or less. Specific examples include a phenyl group, a naphthyl group, a biphenyl group, an anthryl group, and a phenanthryl group. Among these, in consideration of the characteristics of the electrophotographic photosensitive member, a phenyl group, a naphthyl group, and an anthryl group are preferable. From the viewpoint of charge transport capability, a phenyl group and a naphthyl group are more preferable, and a phenyl group is further preferable. Examples of the substituent that Ar ^{1 to} Ar ⁵ may have include an alkyl group, an alkoxy group, and a halogen atom. Specifically, examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, and an n group. -A linear alkyl group such as a butyl group, a branched alkyl group such as an isopropyl group or an ethylhexyl group, or a cyclic alkyl group such as a cyclohexyl group. As the aryl group, a phenyl group which may have a substituent , Naphthyl groups, etc., and examples of the alkoxy group include linear alkoxy groups such as methoxy group, ethoxy group, n-propoxy group and n-butoxy group, and branched alkoxy groups such as isopropoxy group and ethylhexyloxy group. , Cyclic alkoxy groups such as cyclohexyloxy group, trifluoromethoxy group, pentafluoroethoxy group, 1,1,1-trifluoroethoxy They include alkoxy groups having a fluorine atom in groups such as the halogen atom fluorine atom, chlorine atom, bromine atom and the like. Among these, an alkyl group having 1 to 20 carbon atoms and an alkoxy group having 1 to 20 carbon atoms are preferable from the versatility of production raw materials, and an alkyl group having 1 to 12 carbon atoms and carbon number from the viewpoint of handleability during production. An alkoxy group having 1 to 12 carbon atoms is more preferable, and an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms are more preferable from the viewpoint of light attenuation characteristics as an electrophotographic photoreceptor. In the case where Ar ^{1 to} Ar ⁵ are phenyl groups, it is preferable to have a substituent from the viewpoint of charge transport ability, and the number of substituents can be 1 to 5, but from the versatility of manufacturing raw materials, 1 1 to 3 are preferable, and from the viewpoint of the characteristics of the electrophotographic photosensitive member, 1 to 2 are more preferable, and when Ar ^{1 to} Ar ⁵ are naphthyl groups, the number of substituents from the versatility of the production raw material Is preferably 2 or less or not having a substituent, and more preferably, the number of substituents is 1 or having no substituent. Ar ¹ preferably has at least one substituent at the ortho-position or para-position relative to the nitrogen atom, and the substituent preferably has an alkyl group from the viewpoint of suppressing surface resistance reduction, Twenty alkyl groups are more preferred. From the viewpoint of solubility, an alkyl group having 4 to 12 carbon atoms is preferable.

In the above formula (1), Ar ^{6 to} Ar ⁹ each independently represents an arylene group which may have a substituent. The carbon number of the arylene group is 30 or less, preferably 20 or less, and more preferably 15 or less. Specific examples include a phenylene group, a biphenylene group, a naphthylene group, an anthrylene group, and a phenanthrylene group. Among these, a phenylene group and a naphthylene group are preferable, and a phenylene group is more preferable in consideration of the characteristics of the electrophotographic photoreceptor. is there. As the substituent that Ar ^{6 to} Ar ⁹ may have, those exemplified as the substituent that Ar ^{1 to} Ar ⁵ may have are applicable. Among these, a C1-C6 alkyl group and a C1-C6 alkoxy group are preferable from the versatility of a manufacturing raw material, and a C1-C4 alkyl group and carbon number from the surface of the handling property at the time of manufacture 1-4 alkoxy groups are more preferable, and a methyl group, an ethyl group, a methoxy group, and an ethoxy group are more preferable from the viewpoint of light attenuation characteristics as an electrophotographic photosensitive member. When Ar ^{6 to} Ar ⁹ have a substituent, the molecular structure is twisted, and π-conjugate expansion in the molecule may be hindered, and the electron transport ability may be reduced. Therefore, Ar ^{6 to} Ar ⁹ may be substituted. In view of the characteristics of the electrophotographic photosensitive member, 1,3-phenylene group, 1,4-phenylene group, 1,4-naphthylene group, 2,6-naphthylene group, 2,8-naphthylene are preferable. A group is more preferable, and a 1,4-phenylene group is still more preferable.

  m and n each independently represent an integer of 1 to 3. When m and n are large, the solubility in a coating solvent tends to decrease. Therefore, it is preferably 2 or less, and more preferably 1 from the viewpoint of charge transport ability as a charge transport material. When m and n are 1, it represents an ethenyl group and has a geometric isomer, but from the viewpoint of electrophotographic photoreceptor characteristics, a trans isomer structure is preferred. When m and n are 2, it represents a butadienyl group, which also has a geometric isomer, but is preferably a mixture of two or more geometric isomers from the viewpoint of coating solution storage stability.

The electrophotographic photoreceptor of the present invention may contain the compound represented by the formula (1) as a single component in the photosensitive layer, or may contain it as a mixture of the compounds represented by the formula (1). Is possible.
Moreover, the compound represented by the following formula (1a) is particularly preferable. In formula (1a), Ar ¹ in formula (1) is a phenyl group having an alkyl group, an alkoxy group, an aryloxy group, or an aralkyloxy group, and Ar ^{2 to} Ar ⁵ are each independently a substituent. A phenyl group which may have an alkyl group having 1 to 6 carbon atoms, Ar ^{6 to} Ar ⁹ are all unsubstituted 1,4-phenylene groups, and R ^{1 to} R ⁴ are all hydrogen. An atom, and m and n are both 1.

(In Formula (1a), R ^a represents an alkyl group, an alkoxy group, an aryloxy group, or an aralkyloxy group, and R ^{b to} R ^e each independently represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. )
The ratio of the binder resin in the photosensitive layer to the compound represented by the formula (1) is usually 5 parts by mass or more of the charge transport material with respect to 100 parts by mass of the binder resin in the same layer. 10 parts by mass or more is preferable from the viewpoint of reducing the residual potential, and 15 parts by mass or more is more preferable from the viewpoint of stability and charge mobility when repeatedly used. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, the charge transport material is usually used at 120 parts by mass or less. 100 parts by mass or less is preferable from the viewpoint of compatibility between the compound represented by the formula (1) and the binder resin, 90 parts by mass or less is more preferable from the viewpoint of heat resistance, and 80 parts by mass or less is preferable from the viewpoint of scratch resistance. From the viewpoint of wear resistance, 50 parts by mass or less is particularly preferable.

The structure of the charge transport material suitable for the present invention is exemplified below. The following structures are illustrated to make the present invention more concrete, and are not limited to the following structures unless departing from the concept of the present invention.

<Method for producing charge transport material of the present invention>
The charge transport materials exemplified above can be produced according to the scheme described below.
Taking the above compound as an example, it can be produced, for example, by reacting a compound having a triphenylamine skeleton having a formyl group with a phosphate compound having a triphenylamine skeleton. (Scheme 1)

  As another production method, it can also be produced by performing a coupling reaction between a triphenylamine derivative having a halogen atom as described below and an aniline compound. (Scheme 2)

  Among the above schemes 1 and 2, scheme 2 is preferable from the viewpoint of production cost, and in particular, in scheme 2, it is more preferable to manufacture using a palladium catalyst from the viewpoint of purity and electrical characteristics. The purity is usually 97.0% or more, preferably 98.0% or more from the viewpoint of electrical characteristics. From the viewpoint of solubility, it is usually 99.8% or less, preferably 99.5% or less. The charge transport material can be identified by NMR, IR, mass spectrum or the like.

<Hindered phenol compound having a partial structure represented by formula (2)>
The photosensitive layer of the present invention contains a hindered phenol compound having a partial structure represented by the formula (2) in the same layer as the charge transport material represented by the formula (1).

In said formula (2), R < ¹ >, R < ² > represents the alkyl group which may have a substituent. However, when both R ¹ and R ² are methyl groups, the molecule has only one partial structure represented by the formula (2). As the alkyl group, those having 5 or less carbon atoms are preferable, and a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a 1,1-dimethylpropyl group, a t-butyl group, and the like are more preferable. Among these, a t-butyl group is particularly preferable from the viewpoint of a balance between an image drift prevention function and stability. As for the partial structure represented by the said Formula (2), it is preferable that 1-4 normally exist in a compound, and 1-3 are more preferable. Suitable examples of the hindered phenol compound having the partial structure represented by the formula (2) are shown below. Among these, from the viewpoint of electrical characteristics, (2) -1, (2) -3, (2) -4, (2) -5, (2) -9, (2) -11 are preferable, and surface resistance From the viewpoint, (2) -1 or (2) -4 is more preferable, and (2) -1 is particularly preferable.

  In addition, the usage-amount in the photosensitive layer of the hindered phenol compound which has the partial structure represented by said Formula (2) is a lower limit normally 0.01 mass part with respect to 100 mass parts of binder resins in the same layer. As mentioned above, Preferably it is 0.1 mass part or more, More preferably, it is 1 mass part or more, and an upper limit is 30 mass parts or less normally, Preferably it is 16 mass parts or less, More preferably, it is 8 mass parts or less. When the amount used is small, the effect of suppressing the reduction of surface resistance due to exposure to external light is small. When the amount is too large, the residual potential increases, and the electrical characteristics deteriorate and the wear resistance also deteriorates.

  Moreover, from a viewpoint of suppression of surface resistance reduction, it is 0.02 mass part or more normally with respect to 100 mass parts of all charge transport substances, Preferably it is 0.2 mass part or more, More preferably, it is 2 mass part or more. Moreover, from a viewpoint of a residual potential and abrasion resistance, Preferably it is 60 mass parts or less, More preferably, it is 30 mass parts or less, Most preferably, it is 16 mass parts or less.

<Amine compound represented by formula (3)>
In the present invention, in addition to the hindered phenol compound having the partial structure represented by the formula (2), in order to sufficiently exhibit the effect of suppressing the reduction of the surface resistance due to exposure to external light without affecting the electrical characteristics. The amine compound represented by the following formula (3) is contained in the surface layer.

In the above formula (3), R ^{3 to} R ⁵ represent an alkylene group having 3 or less carbon atoms which may have a substituent, and Ar ¹⁰ and Ar ¹¹ may have a hydrogen atom and a substituent. An alkyl group or an aryl group which may have a substituent is represented, and Ar ¹² represents an aryl group which may have a substituent. k represents an integer of 1 or 2.
In the above formula (3), R ^{3 to} R ⁵ represent an alkylene group having 3 or less carbon atoms which may have a substituent, and in view of electrical characteristics, it preferably has 2 or less carbon atoms, and more preferably Has 1 carbon. Examples of the substituent that R ^{3 to} R ⁵ may have include an alkyl group, an aryl group, an alkoxy group, and a halogen atom. Considering the influence on the residual potential, it is preferable that R ^{3 to} R ⁵ do not have a substituent.

Ar ¹⁰ and Ar ¹¹ represent a hydrogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent, and the total carbon number of the alkyl group that may have a substituent. Is usually 20 or less, preferably 15 or less, more preferably 10 or less. The total number of carbon atoms of the aryl group which may have a substituent is usually 30 or less, preferably 20 or less, more preferably 15 or less. Examples of the substituent that Ar ¹⁰ and Ar ¹¹ may have include an alkyl group, an aryl group, an alkoxy group, and a halogen atom. Specifically, examples of the alkyl group include a methyl group, an ethyl group, and an n-propyl group. , A linear alkyl group such as an n-butyl group, a branched alkyl group such as an isopropyl group or an ethylhexyl group, or a cyclic alkyl group such as a cyclohexyl group. The aryl group may have a substituent. Examples thereof include a phenyl group, a naphthyl group and the like, and examples of the alkoxy group include a branched alkoxy group such as a linear alkoxy group such as a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group, an isopropoxy group, and an ethylhexyloxy group. Cyclic alkoxy groups such as alkoxy groups and cyclohexyloxy groups, trifluoromethoxy groups, pentafluoroethoxy groups, 1,1,1-trifluoro An alkoxy group having a fluorine atom such as an ethoxy group is exemplified, and a halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and the like. Considering the relationship between the ionization potential and the charge transport material, Ar ¹⁰ and Ar ¹¹ are
It preferably has no substituent.

Ar ¹² represents an aryl group which may have a substituent. Examples of the aryl group which may have a substituent include those described above for Ar ¹⁰ and Ar ¹¹ . In view of the ionization potential relationship with the charge transport material, Ar ¹² preferably has no substituent. When k is 2, Ar ¹² may be directly bonded to the other Ar ¹² via a single bond, or may be bonded to the other Ar ¹² via a substituent.

k represents an integer of 1 or 2. From the viewpoint of production, 1 is preferable.
The lower limit of the molecular weight of the amine compound of the present invention is usually 100 or more, preferably 200 or more, from the viewpoint of ozone resistance. From the viewpoint of electrical characteristics, the upper limit is usually 900 or less, preferably 700 or less, more preferably 600 or less.
The content of the amine compound of the present invention is usually 0.01 parts by mass or more, preferably 0.1 parts by mass or more, with respect to 100 parts by mass of the binder resin in the same layer, from the viewpoint of suppressing surface resistance reduction. Preferably it is 0.3 mass part or more. In order to maintain a low residual potential, it is usually 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 2 parts by mass or less.

Further, from the viewpoint of suppressing the reduction of surface resistance, it is usually 0.02 parts by mass or more, preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the total charge transport material. . Moreover, from a viewpoint of a residual potential and abrasion resistance, Preferably it is 25 mass parts or less, More preferably, it is 10 mass parts or less, Most preferably, it is 5 mass parts or less.
Examples of preferred amine compounds are shown below. Among these, from the viewpoint of suppression of surface resistance reduction, (3) -1, (3) -4, (3) -6, (3) -19, (3) -20, (3) -21, (3 ) -27 and (3) -28 are preferable, and (3) -1, (3) -19, (3) -20, (3) -21, and (3) -28 are preferable from the viewpoint of electrical characteristics. 3) -1 is particularly preferred.

These amine compounds have moderate basicity, oxidation potential of the charge transport material, or oxidation potential greater than the ionization potential, or ionization potential, so that the residual potential is kept low and the electrical characteristics are stabilized. Therefore, it is preferable. In addition, the amino group (—NH—) serves as a charge trap in the photosensitive layer and significantly adversely affects the electrical characteristics. Further, the boiling point is preferably 100 ° C. or higher so as not to volatilize in the drying process at the time of producing the photoreceptor. As exemplified compounds, amine compounds having one or more aralkyl groups such as benzyl groups are preferred. Such amine compounds have moderate basicity and oxidation potential in addition to the effect of suppressing surface resistance reduction due to exposure to external light, so that the benzylic position of the amine compound is selectively oxidized prior to the charge transport material. Therefore, it is considered that the function of trapping gases such as ozone and NOx is excellent. Of these, those having two or more aralkyl groups are preferred, and those having three are more preferred. Since the ionization potential is easily oxidized when it is sufficiently higher than the charge transport material, the lower limit is usually 6.00 eV or more, preferably 6.25 eV or more, more preferably 6.40 eV or more. The upper limit is usually 7.00 eV or less, preferably 6.80 eV or less, from the viewpoint of electrical characteristics. Since the electron affinity is easily oxidized when it is sufficiently lower than the charge transport material, the upper limit is usually 2.00 eV or less, preferably 1.80 eV or less, more preferably 1.50 ev or less. The lower limit is usually 0.50 eV or more, preferably 1.
00 eV or more, more preferably 1.20 eV or more.

By containing in the surface layer the charge transport material represented by the above (1), the hindered phenol compound having the partial structure represented by the above formula (2), and the amine compound represented by the above formula (3), The mechanism for the effect of suppressing the reduction in surface resistance after exposure to external exposure is not necessarily clear, but is estimated as follows. The charge transport material shown in the above (1) has a large rod-like molecule and relatively low compatibility with the binder resin. For this reason, it is considered that there is more on the surface of the photosensitive layer and in the vicinity thereof, and there is a tendency opposite to the case where a so-called resin segregation layer is formed in the vicinity of the surface of the photosensitive layer. Therefore, it is considered that the chemical structure of the charge transport material shown in (1) is easily denatured by exposure to a relatively short wavelength of external light in the ultraviolet to visible region, resulting in a decrease in surface resistance. On the other hand, the hindered phenol compound having the partial structure represented by the formula (2) is more easily exposed on the photosensitive layer surface side than the charge transport material shown in the above (1), and is considered to protect the external exposure exposure to some extent. It is done. In addition, the amine compound represented by the formula (3) is a surface trap because the charge transport material shown in the above (1) becomes an appropriate trap for the electrical conductivity of the surface even if it is modified by exposure to external exposure. It is thought to suppress the decrease in resistance.

  The ratio of the hindered phenol compound having the partial structure represented by the formula (2) and the amine compound represented by the formula (3) is the suppression of surface resistance reduction with respect to 100 parts by mass of the hindered phenol compound. From this viewpoint, the amine compound is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 5 parts by mass or more. From the viewpoint of electrical characteristics, it is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and still more preferably 100 parts by mass or less.

≪Electrophotographic photoreceptor≫
The configuration of the electrophotographic photosensitive member of the present invention will be described below. The electrophotographic photosensitive member of the present invention comprises, on a conductive support, a charge transport material represented by the above formula (1), a hindered phenol compound having a partial structure represented by the above formula (2), and The configuration is not particularly limited as long as the amine compound represented by the formula (3) is contained in the outermost layer. In the case where the photosensitive layer of the electrophotographic photosensitive member is a laminated type described later, the charge transport layer has a charge transport material represented by the formula (1) and a hinder having a partial structure represented by the formula (2). It contains a dophenol compound, an amine compound represented by the above formula (3), and, if necessary, an antioxidant, a leveling agent and other additives. In addition, when the electrophotographic photosensitive layer is a single layer type, which will be described later, in addition to the components used for the charge transport layer of the above-mentioned multilayer photoconductor, a charge generating material and an electron transport material may be used. It is common.

<Conductive support>
There are no particular restrictions on the conductive support, but for example, metal materials such as aluminum, aluminum alloys, stainless steel, copper and nickel, and conductive powders such as metal, carbon and tin oxide can be added to make the conductive material conductive. Mainly used are resin, glass, paper, or the like obtained by depositing or applying the applied resin material or a conductive material such as aluminum, nickel, ITO (indium tin oxide) on the surface. These may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and arbitrary ratios. As a form of the conductive support, a drum form, a sheet form, a belt form or the like is used. Furthermore, a conductive material having an appropriate resistance value may be used on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

Moreover, when using metal materials, such as an aluminum alloy, as an electroconductive support body, you may use, after giving an anodic oxide film. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
The surface of the conductive support may be smooth, or may be roughened by using a special cutting method or performing a polishing treatment. Further, it may be roughened by mixing particles having an appropriate particle size with the material constituting the conductive support. In order to reduce the cost, it is possible to use the drawing tube as it is without performing the cutting process.

<Underlayer>
An undercoat layer may be provided between the conductive support and the photosensitive layer described later for improving adhesion and blocking properties. As the undercoat layer, a resin or a resin in which particles such as a metal oxide are dispersed is used. The undercoat layer may be a single layer or a plurality of layers.

  Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of a several crystal state may be contained.

In addition, various particle sizes of metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is preferably 10 nm or more and 100 nm or less, and particularly 10 nm or more and 50 nm or less. preferable. This average primary particle size can be obtained from a TEM photograph or the like.
The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. The binder resin used for the undercoat layer is epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, chloride resin. Cellulose esters such as vinylidene resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacryl resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, nitrocellulose Resin, cellulose ether resin, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, zirconium chelate compound, zirconium The organic zirconium compound alkoxide compounds, titanyl chelate compounds, organic titanyl compounds such as titanium alkoxide compounds include known binder resins such as a silane coupling agent. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.

The use ratio of the inorganic particles to the binder resin used in the undercoat layer can be arbitrarily selected. From the viewpoint of the stability of the dispersion and the coating property, the binder resin is usually 10% by mass or more, It is preferable to use in the range of 500 mass% or less.
The thickness of the undercoat layer is arbitrary as long as the effects of the present invention are not significantly impaired, but the viewpoint of improving the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and coating properties during production of the electrophotographic photosensitive member. Therefore, it is usually 0.01 μm or more, preferably 0.1 μm or more, and usually 30 μm or less, preferably 20 μm or less. A known antioxidant or the like may be mixed in the undercoat layer. For the purpose of preventing image defects, pigment particles, resin particles and the like may be included.

<Photosensitive layer>
The photosensitive layer is formed on the above-mentioned conductive support (or on the undercoat layer when the above-described undercoat layer is provided). The photosensitive layer contains a charge transport material represented by the formula (1), a hindered phenol compound having a partial structure represented by the formula (2), and an amine compound represented by the formula (3). The surface layer is preferably a single layer structure in which the charge generation material and the charge transport material (including the charge transport material of the present invention) are present in the same layer and dispersed in the binder resin. A charge generation layer in which a charge generation material is dispersed in a binder resin, and a charge transport material (including the charge transport material of the present invention).
Is a functionally separated type having a laminated structure composed of two or more layers including a charge transporting layer dispersed in a binder resin (hereinafter referred to as “laminated photosensitive layer” as appropriate). There may be.

  In addition, as the laminated photosensitive layer, a charge-generating layer and a charge transport layer are laminated in this order from the conductive support side, and conversely, a charge transport layer and a charge generation layer are formed from the conductive support side. There are reverse laminated photosensitive layers provided in order, and any of them can be adopted, but a forward laminated photosensitive layer capable of exhibiting balanced photoconductivity is particularly preferable.

<Laminated photosensitive layer>
[Charge generation layer]
The charge generation layer of the laminated photosensitive layer (function-separated type photosensitive layer) contains a charge generation material and usually contains a binder resin and other components used as necessary. Such a charge generation layer is prepared, for example, by dissolving or dispersing a charge generation material and a binder resin in a solvent or dispersion medium to prepare a coating solution, and in the case of a sequentially laminated photosensitive layer, this is formed on a conductive support. (If an undercoat layer is provided, it can be obtained on the undercoat layer). In the case of a reverse laminated type photosensitive layer, it can be obtained by coating on a charge transport layer and drying.

  Examples of the charge generation material include inorganic photoconductive materials such as selenium and its alloys, cadmium sulfide, and organic photoconductive materials such as organic pigments. Organic photoconductive materials are preferred, and organic photoconductive materials are particularly preferable. Pigments are preferred. Examples of organic pigments include phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments. . Among these, phthalocyanine pigments or azo pigments are particularly preferable. When organic pigments are used as the charge generating substance, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

  When using a phthalocyanine pigment as a charge generating material, specifically, metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, aluminum or other metal or oxide thereof, halide, Those having each crystal form of coordinated phthalocyanines such as hydroxides and alkoxides, and phthalocyanine dimers using oxygen atoms as bridging atoms are used. In particular, titanyl phthalocyanines (also known as oxytitanium) such as X-type, τ-type metal-free phthalocyanine, A-type (also known as β-type), B-type (also known as α-type), and D-type (also known as Y-type), which are highly sensitive crystal types Phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, hydroxyindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and type I, type II, etc. The [mu] -oxo-aluminum phthalocyanine dimer is preferred.

  Among these phthalocyanines, A-type (also known as β-type), B-type (also known as α-type), and powder X-ray diffraction angle 2θ (± 0.2 °) are 27.1 ° or 27.3 °. D-type (Y-type) titanyl phthalocyanine, II-type chlorogallium phthalocyanine, V-type hydroxygallium phthalocyanine, hydroxygallium phthalocyanine having the strongest peak at 28.1 °, or 26. Hydroxygallium phthalocyanine having no peak at 2 °, a clear peak at 28.1 °, and a full width at half maximum W of 25.9 ° of 0.1 ° ≦ W ≦ 0.4 ° G-type μ-oxo-gallium phthalocyanine dimer and the like are particularly preferable.

The oxytitanium phthalocyanine crystal is preferably a crystal having main diffraction peaks at Bragg angles (2θ ± 0.2 °), 24.1 °, and 27.2 ° with respect to CuKα characteristic X-rays (wavelength 1.541Å). As another diffraction peak, a crystal having a peak near 26.2 ° is inferior in crystal stability at the time of dispersion, and therefore it is preferable that no peak is present near 26.2 °. Among them, 7.3 °, 9.6 °, 11.6 °, 14.2 °, 18.0 °, 24.1 ° and 27.2 °, or 7.3 °, 9.5 °, 9 Dark decay and residual potential when crystals having main diffraction peaks at 0.7 °, 11.6 °, 14.2 °, 18.0 °, 24.2 ° and 27.2 ° are used as electrophotographic photoreceptors. From the viewpoint of

  When a metal-free phthalocyanine compound or a metal-containing phthalocyanine compound is used as the charge generation material, a highly sensitive photoreceptor can be obtained with respect to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm. Further, when an azo pigment such as monoazo, diazo, or trisazo is used, white light, laser light having a wavelength around 660 nm, or laser light having a relatively short wavelength (for example, a wavelength in the range of 380 nm to 500 nm). It is possible to obtain a photoreceptor having sufficient sensitivity to the laser beam).

  The phthalocyanine compound may be a single compound or several mixed or mixed crystal states. As the mixed state in the phthalocyanine compound or crystal state here, those obtained by mixing the respective constituent elements later may be used, or the mixed state in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, crystallization, etc. It may be the one that gave rise to. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known. In order to generate a mixed crystal state, as described in JP-A-10-48859, two types of crystals are mixed, mechanically ground and made amorphous, and then converted into a specific crystal state by solvent treatment. The method of doing is mentioned.

On the other hand, when an azo pigment is used as a charge generation material, various known azo pigments can be used as long as they have sensitivity to a light source for light input. Trisazo pigments are preferably used.
When the organic pigments exemplified above are used as the charge generation material, one kind may be used alone, or two or more kinds of pigments may be mixed and used. In this case, it is preferable to use a combination of two or more kinds of charge generating materials having spectral sensitivity characteristics in different spectral regions of the visible region and the near red region. Among them, a disazo pigment, a trisazo pigment and a phthalocyanine pigment are preferably used in combination. More preferred.

  The binder resin used for the charge generation layer constituting the multilayer photosensitive layer is not particularly limited. For example, polyvinyl butyral resin, polyvinyl formal resin, partially acetalized polyvinyl butyral resin in which part of butyral is modified with formal, acetal, or the like. Polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, modified ether polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, etc. Polyacrylamide resin, polyamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, Vinyl chloride such as zein, vinyl chloride-vinyl acetate copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer -Insulating resin such as vinyl acetate copolymer, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, styrene-alkyd resin, silicon-alkyd resin, phenol-formaldehyde resin, and poly-N-vinylcarbazole , Organic photoconductive polymers such as polyvinyl anthracene and polyvinyl perylene. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.

Specifically, the charge generation layer is prepared by dispersing a charge generation material in a solution obtained by dissolving the above-described binder resin in an organic solvent to prepare a coating solution, which is then formed on a conductive support (when an undercoat layer is provided). Is formed by coating (on the undercoat layer).
The solvent used for preparing the coating solution is not particularly limited as long as it dissolves the binder resin. For example, saturated aliphatic solvents such as pentane, hexane, octane, and nonane, and aromatics such as toluene, xylene, and anisole. Group solvents, halogenated aromatic solvents such as chlorobenzene, dichlorobenzene, chloronaphthalene, amide solvents such as dimethylformamide, N-methyl-2-pyrrolidone, methanol, ethanol, isopropanol, n-butanol, benzyl alcohol, etc. Alcohol solvents, aliphatic polyhydric alcohols such as glycerin and polyethylene glycol, chain or cyclic ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, 4-methoxy-4-methyl-2-pentanone, methyl formate, ethyl acetate, Acetic acid n-bu Chains such as ester solvents such as benzene, halogenated hydrocarbon solvents such as methylene chloride, chloroform, 1,2-dichloroethane, diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, etc. Or cyclic ether solvents, acetonitrile, dimethyl sulfoxide, sulfolane, aprotic polar solvents such as hexamethylphosphoric triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, triethylenediamine, triethylamine-containing nitrogen Compound, mineral oil such as ligroin, water and the like. Any one of these may be used alone, or two or more of these may be used in combination. In addition, when providing the above-mentioned undercoat layer, what does not melt | dissolve this undercoat layer is preferable.

  In the charge generation layer, the compounding ratio (mass ratio) of the binder resin and the charge generation material is usually 10 parts by mass or more, preferably 30 parts by mass or more, and usually 1000 parts by mass with respect to 100 parts by mass of the binder resin. The range is not more than part by mass, preferably not more than 500 parts by mass. The thickness of the charge generation layer is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material. On the other hand, if the ratio of the charge generating substance is too low, the sensitivity as a photoreceptor may be reduced.

  As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, or a sand mill dispersion method can be used. At this time, it is effective to refine the particles to a particle size in the range of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

<Charge transport layer>
The charge transport layer of the multilayer photoreceptor contains the above-described charge transport material and binder resin, and other components used as necessary. Specifically, such a charge transport layer is prepared by dissolving or dispersing a charge transport material or the like and a binder resin in a solvent to prepare a coating solution. In addition, in the case of a reverse lamination type photosensitive layer, it can be obtained by coating and drying on a conductive support (on the undercoat layer when an undercoat layer is provided).

  As the charge transport material, in addition to the charge transport material represented by the above formula (1), other known charge transport materials may be used in combination. When other charge transport materials are used in combination, the type is not particularly limited, but for example, carbazole derivatives, hydrazone compounds, aromatic amine derivatives, enamine derivatives, butadiene derivatives and those in which a plurality of these derivatives are bonded are preferable. Any of these charge transport materials may be used alone, or a plurality of types may be used in any combination.

In the photoreceptor of the present invention, a charge transport material represented by the formula (1), a hindered phenol compound having a partial structure represented by the formula (2), an amine compound represented by the formula (3), and In the surface layer, a binder resin is used for securing the film strength. Binder resins include butadiene resins, styrene resins, vinyl acetate resins, vinyl chloride resins, acrylic ester resins, methacrylic ester resins, vinyl alcohol resins, polymers of vinyl compounds such as ethyl vinyl ether, copolymers, and polyvinyl butyral resins. Polyvinyl formal resin, partially modified polyvinyl acetal, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicone resin, silicone-alkyd resin, poly-N-vinylcarbazole resin, polycarbonate resin, polyester resin are preferably used. . Of these, polycarbonate resins and polyester resins are preferred. Polyarylate resins, which are names for polyester resins, especially wholly aromatic polyester resins, can increase the elastic deformation rate, and are particularly preferable from the viewpoint of mechanical properties such as wear resistance, scratch resistance, and filming resistance. In general, a polyester resin is superior to a polycarbonate resin from the viewpoint of mechanical properties, but is inferior to a polycarbonate resin from the viewpoint of electrical characteristics and light fatigue. This is thought to be due to the fact that the ester bond is more polar than the carbonate bond and has a strong acceptor property. In addition, these resins may be used as a mixture of two or more kinds within a range that does not impair the function.

First, the polyester resin will be described. Generally, a polyester resin is obtained by polycondensing a polyhydric alcohol component and a polyvalent carboxylic acid component such as a carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid ester as a raw material monomer.
As the polyhydric alcohol component, polyoxypropylene (2.2) -2,2-bis (4
-Hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (
4-Hydroxyphenyl) propane and other bisphenol A alkylene (2 to 3 carbon atoms) oxide (average added mole number 1 to 10) adduct, ethylene glycol, propylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane , Hydrogenated bisphenol A, sorbitol, or alkylene thereof (2 carbon atoms)
-3) Oxide (average added mole number 1 to 10) adduct, aromatic bisphenol and the like, and those containing one or more of these are preferable.

The polyvalent carboxylic acid component includes dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid and maleic acid, carbon numbers such as dodecenyl succinic acid and octyl succinic acid.
Succinic acid, trimellitic acid, pyromellitic acid, anhydrides of these acids and alkyl (1 to 3 carbon atoms) esters of these acids substituted with -20 alkyl groups or C2-C20 alkenyl groups The thing containing 1 or more types of these is preferable.
Among these polyester resins, preferred is a wholly aromatic polyester resin (polyarylate resin) having a structural unit represented by the following formula (4).

In formula (4), Ar ^{13 to} Ar ¹⁶ each independently represent an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or an alkylene group. s is 0 or more and 2
Represents the following integers: Y represents a single bond, an oxygen atom, a sulfur atom, or an alkylene group. In the above formula (4), Ar ^{13 to} Ar ¹⁶ each independently represent an arylene group that may have a substituent. As carbon number which an arylene group has, it is 6 or more normally, and the upper limit is 20 or less normally, Preferably it is 10 or less, More preferably, it is 6. If the number of carbon atoms is too large, the production cost increases and the electrical characteristics may deteriorate.

Specific examples of Ar ^{13 to} Ar ¹⁶ include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, naphthylene group, anthrylene group, phenanthrylene group and the like. Among these, the arylene group is preferably a 1,4-phenylene group from the viewpoint of electrical characteristics. An arylene group may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

Moreover, as a substituent which Ar < ¹³ > -Ar < ¹⁶ > may have, an alkyl group, an aryl group, a halogen group, an alkoxy group, etc. are mentioned. Among them, considering the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the alkyl group is preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, and is preferably an aryl group. Is preferably a phenyl group or a naphthyl group, a halogen group is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and an alkoxy group is preferably a methoxy group, an ethoxy group, a propoxy group or a butoxy group. In addition, when a substituent is an alkyl group, carbon number of the alkyl group is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 2 or less.

More specifically, Ar ¹⁵ and Ar ¹⁶ each independently preferably has 0 or more and 2 or less substituents, more preferably have a substituent from the viewpoint of adhesiveness, and among them, substitution from the viewpoint of wear resistance. It is particularly preferable that the number of groups is one. Moreover, as a substituent, an alkyl group is preferable and a methyl group is particularly preferable.
On the other hand, Ar ¹³ and Ar ¹⁴ each independently preferably has 0 or more and 2 or less substituents, and more preferably has no substituent from the viewpoint of wear resistance.

In the above formula (4), Y is a single bond, an oxygen atom, a sulfur atom, or an alkylene group. As the alkylene group, —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and cyclohexylene are preferable, and —CH ₂ —, —CH (CH ₃ ) —, — are more preferable. C (CH ₃ ) ₂ — and cyclohexylene are preferable, and —CH ₂ — and —CH (CH ₃ ) — are particularly preferable.
In the above formula (4), X is a single bond, an oxygen atom, a sulfur atom, or an alkylene group, and among them, X is preferably an oxygen atom. In this case, s is particularly preferably 1.

Specific examples of preferred dicarboxylic acid residues when s is 1 include diphenyl ether-2,2′-dicarboxylic acid residues, diphenyl ether-2,3′-dicarboxylic acid residues, and diphenyl ether-2,4′-dicarboxylic acid. Residue, diphenyl ether-3,3′-dicarboxylic acid residue, diphenyl ether-3,4′-dicarboxylic acid residue, diphenyl ether-4,4′-dicarboxylic acid residue and the like. Among these, considering the simplicity of production of the dicarboxylic acid component, diphenyl ether-2,2′-dicarboxylic acid residue, diphenyl ether-2,4′-dicarboxylic acid residue, diphenyl ether-4,4′-dicarboxylic acid Residues are more preferred, and diphenyl ether-4,4′-dicarboxylic acid residues are particularly preferred.

Specific examples of the dicarboxylic acid residue when s is 0 include phthalic acid residue, isophthalic acid residue, terephthalic acid residue, toluene-2,5-dicarboxylic acid residue, p-xylene-2,5- Dicarboxylic acid residue, naphthalene-1,4-dicarboxylic acid residue, naphthalene-2,3-dicarboxylic acid residue, naphthalene-2,6-dicarboxylic acid residue, biphenyl-2,2′-dicarboxylic acid residue, Biphenyl-4,4′-dicarboxylic acid residue may be mentioned, preferably phthalic acid residue, isophthalic acid residue, terephthalic acid residue, naphthalene-1,4-dicarboxylic acid residue, naphthalene-2,6- Dicarboxylic acid residues, biphenyl-2,2′-dicarboxylic acid residues, biphenyl-4,4′-dicarboxylic acid residues, particularly preferably isophthalic acid residues and terephthalic acid residues. It is also possible to use a combination of a plurality of rubonic acid residues. The ratio of isophthalic acid residue to terephthalic acid residue is usually 50:50, but can be arbitrarily changed. In that case, the higher the ratio of terephthalic acid residues, the better from the viewpoint of electrical characteristics.

  The viscosity average molecular weight of the polyester resin used in the present invention is arbitrary as long as the effects of the present invention are not significantly impaired, but from the viewpoint of mechanical strength, the lower limit is usually 20,000 or more, preferably 30,000 or more, more Preferably it is 40,000 or more. From the viewpoint of productivity such as the dispersibility of the compound and the viscosity of the coating solution, the upper limit is usually 100,000 or less, preferably 90,000 or less, more preferably 80,000 or less. In addition, a viscosity average molecular weight can be measured by the method as described in an Example using an Ubbelohde type capillary viscometer etc., for example.

Next, the polycarbonate resin will be described. Polycarbonate resin is produced by a solvent method such as interfacial method (interfacial polycondensation method) or solution method in which bisphenols and phosgene are reacted in solution, and polycondensation of bisphenol and carbonic acid diester by transesterification. The thing by the melting method to make it react is known.
Of these, polycarbonate resin produced by the interfacial method is widely used for electrophotographic photoreceptors because it can be made high molecular weight, purified by liquid-liquid washing, and applicable to various types of bisphenol. It has been. However, since the phosgene is used as a raw material in the interface method, there is a problem in safety. On the other hand, for polycarbonate resin by the melt method, there are restrictions on the types of bisphenol that can be polymerized, it is difficult to increase the molecular weight, and it is difficult to remove impurities by washing, but because phosgene is not used in the polymerization process, it is a safety issue. The use is also considered for electrophotographic photoreceptors.

  In the electrophotographic photosensitive member of the present invention, one or a mixture of two or more kinds of polycarbonate resins obtained by copolymerizing known bisphenols may be used. Among known bisphenols, a polycarbonate resin containing a structural unit represented by the following formula (5) is preferably used from the viewpoints of electrical characteristics, surface hardness, elastic deformation rate, and adhesiveness.

  The polycarbonate resin used in the present invention may be a homopolymer composed of a single unit represented by the above formula (5), but may be used in block or random copolymerization with other bisphenol units. Examples of bisphenol units that may be copolymerized are shown below. As for the copolymerization ratio, the ratio of the above formula (5) is 50% by mass or more, more preferably 60% by mass or more.

The preferable range of the viscosity average molecular weight of the polycarbonate resin used in the present invention is the same as that of the polyester resin.
The polyester resin having the component represented by the above formula (4) and the polycarbonate resin having the component represented by the above formula (5) of the present invention are electrophotographic photoreceptors having a photosensitive layer on a conductive support. In the case of providing a protective layer on the photosensitive layer as described in detail below, it is contained in the protective layer.

  The film thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, on the other hand, usually 50 μm or less, preferably 45 μm or less, from the viewpoints of long life, image stability, and charging stability. Furthermore, in the range of 30 μm or less, 25 μm or less is particularly preferably used from the viewpoint of high resolution.

<Single layer type photosensitive layer>
The single-layer type photosensitive layer is represented by a charge generation material, a charge transport material represented by the formula (1), a hindered phenol compound having a partial structure represented by the formula (2), and the formula (3). In addition to the amine compound, a binder resin is used to secure the film strength in the same manner as the charge transport layer of the multilayer photoreceptor. Specifically, a charge generation material, a charge transport material, and various binder resins are dissolved or dispersed in a solvent to prepare a coating solution, and on a conductive support (or an undercoat layer when an undercoat layer is provided). It can be obtained by coating and drying.

Charge transport materials represented by the formula (1), hindered phenol compounds having a partial structure represented by the formula (2), types of amine compounds and binder resins represented by the formula (3), and these The usage ratio is the same as in the case of the charge transport layer of the multilayer photoconductor.
As the charge generation material, the same materials as those described for the charge generation layer of the multilayer photoreceptor can be used. However, in the case of a photosensitive layer of a single layer type photoreceptor, it is necessary to sufficiently reduce the particle size of the charge generating material. Specifically, the range is usually 1 μm or less, preferably 0.5 μm or less.

In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. It is 30 mass parts or less, Preferably it is the range of 10 mass parts or less.
The film thickness of the single-layer type photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less.

<Other additives>
For the purpose of improving film-forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, etc., in both the photosensitive layer and each layer constituting it, both in the multilayer type photosensitive member and the single layer type photosensitive member. Additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents may be included.

<Other functional layers>
In both the multilayer type photoreceptor and the single-layer type photoreceptor, the photosensitive layer formed by the above procedure is the uppermost layer, that is, the surface layer. However, another layer may be provided on the photosensitive layer and used as the surface layer. . For example, a protective layer may be provided for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to discharge products generated from a charger or the like. In that case, the charge transport material represented by the formula (1) in the protective layer, a hindered phenol compound having a partial structure represented by the formula (2), an amine compound represented by the formula (3), and A binder resin is contained.

  Further, for the purpose of reducing the frictional resistance and wear on the surface of the photoconductor, and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper, etc., the surface layer is made of fluorine resin, silicon resin, polyethylene resin, etc. You may contain the particle | grains which consist of these resin, and the particle | grains of inorganic compounds, such as a silica and an alumina.

<Method for forming each layer>
Each layer constituting the above-described photoreceptor is formed by dip coating, spray coating, nozzle coating, bar coating, roll coating, blade coating on a conductive support obtained by dissolving or dispersing a substance to be contained in a solvent. It is formed by repeating a coating / drying step sequentially for each layer by a known method such as coating.

There are no particular restrictions on the solvent or dispersion medium used in the preparation of the coating solution, but specific examples include alcohols such as methanol, ethanol, propanol and 2-methoxyethanol, tetrahydrofuran, 1,4-dioxane, dimethoxyethane and the like. Ethers, esters such as methyl formate and ethyl acetate, acetone, methyl ethyl ketone, cyclohexanone, ketones such as 4-methoxy-4-methyl-2-pentanone, aromatic hydrocarbons such as benzene, toluene, xylene, dichloromethane, Chlorinated hydrocarbons such as chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, n-butylamine, isopropanolamine, Diethyla Emissions, triethanolamine, ethylenediamine, nitrogen-containing compounds such as triethylenediamine, acetonitrile, N- methylpyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and kinds.

The amount of the solvent or dispersion medium used is not particularly limited, but considering the purpose of each layer and the properties of the selected solvent / dispersion medium, it is appropriate so that the physical properties such as solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust.
For example, in the case of a charge transport layer of a single layer type photoreceptor or a function separation type photoreceptor, the solid content concentration of the coating solution is usually 5% by mass or more, preferably 10% by mass or more, and usually 40% by mass or less. The range is preferably 35% by mass or less. In addition, the viscosity of the coating solution is usually 10 mPa · s or higher, preferably 50 mPa · s or higher, and usually 500 mPa · s or lower, preferably 400 mPa · s or lower, at the temperature during use.

  In the case of a charge generation layer of a multilayer photoreceptor, the solid content concentration of the coating solution is usually 0.1% by mass or more, preferably 1% by mass or more, and usually 15% by mass or less, preferably 10% by mass. % Or less. In addition, the viscosity of the coating solution is usually 0.01 mPa · s or higher, preferably 0.1 mPa · s or higher, and usually 20 mPa · s or lower, preferably 10 mPa · s or lower, at the temperature during use.

Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used.
The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. Further, the heating temperature may be constant, or heating may be performed while changing the temperature during drying.

≪Image forming device≫
Next, a drum cartridge and an image forming apparatus using the electrophotographic photosensitive member of the present invention will be described with reference to FIG.
In FIG. 3, reference numeral 1 denotes a drum-shaped photoconductor, which is rotationally driven in the direction of the arrow at a predetermined peripheral speed. The photosensitive member 1 is uniformly charged at a predetermined positive or negative potential on the surface thereof by the charging unit 2 during the rotation process, and then exposure for forming a latent image is performed by the image exposure unit in the exposure unit 3.

  The formed electrostatic latent image is then developed with toner by the developing means 4, and the toner developed image is sequentially transferred onto the transfer body (paper or the like) P fed from the paper feeding unit by the corona transfer means 5. . In FIG. 3, the developing unit 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45. The developing unit 4 stores toner T inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing unit 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

  The image-transferred transfer body is then sent to the fixing means 7 where the image is fixed and printed out of the apparatus. The fixing unit 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 3 shows an example in which a heating device 73 is provided inside the upper fixing member 71. The upper and lower fixing members 71 and 72 include a fixing roll in which a metal base tube made of stainless steel, aluminum or the like is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, a fixing sheet, or the like. A member can be used. Further, the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve the releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

  When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P. The surface of the photoreceptor 1 after the image transfer is cleaned by the cleaning unit 6 to remove the transfer residual toner, and is neutralized by the neutralization unit for the next image formation.

  In using the electrophotographic photosensitive member of the present invention, as a charger, in addition to a corona charger such as corotron or scorotron, a direct charging means for charging a charged member by contacting a directly charged member to which a voltage is applied is provided. It may be used. Examples of direct charging means include contact chargers such as charging rollers and charging brushes. As the direct charging means, any one that involves air discharge or injection charging that does not involve air discharge is possible. In addition, as a voltage applied at the time of charging, in the case of only a direct current voltage, an alternating current can be superimposed on a direct current.

  Incidentally, in the photoconductor using the charge transport material represented by the formula (1) described in the present application, when the contact charging, particularly the contact charging by applying a direct current (DC) voltage is used, the image density unevenness due to the exposure to the external exposure is reduced. It is easy to generate. This is because the charging ability is inferior to that of the scorotron method, so surface potential control by applying sufficient surface charge is not necessarily performed, the influence of in-plane unevenness of the surface resistance cannot be canceled, and images are likely to appear. It is done. Therefore, in the contact charging method, in particular, the direct current contact charging method, there is a great merit in using the predetermined photoreceptor.

For the exposure, a halogen lamp, a fluorescent lamp, a laser (semiconductor, He—Ne), LED, a photoreceptor internal exposure system, or the like is used. As a digital electrophotographic system, it is preferable to use a laser, an LED, an optical shutter array, or the like. . As the wavelength, in addition to 780 nm monochromatic light, it is possible to use monochromatic light in the 600 to 700 nm region and slightly shorter wavelength.
In the development process, a dry development method such as cascade development, one-component insulating toner development, one-component conductive toner development, two-component magnetic brush development, or the like is used.

  As the toner, in addition to the pulverized toner, chemical toners such as suspension granulation, suspension polymerization, and emulsion polymerization aggregation can be used. In particular, in the case of chemical toners, those having a small particle diameter of about 4 to 8 μm are used, and those having a shape close to a sphere, and those outside a potato-like sphere can also be used. The polymerized toner is excellent in charging uniformity and transferability, and is preferably used for high image quality.

For the transfer process, electrostatic transfer methods such as corona transfer, roller transfer, and belt transfer, pressure transfer methods, and adhesive transfer methods are used. For fixing, heat roller fixing, flash fixing, oven fixing, pressure fixing, IH fixing, belt fixing, IHF fixing, etc. may be used. These fixing methods may be used alone or in combination with a plurality of fixing methods. May be.
For cleaning, brush cleaner, magnetic brush cleaner, electrostatic brush cleaner, magnetic roller cleaner, blade cleaner, etc. are used.

In many cases, the static elimination step is omitted, but when used, a fluorescent lamp, LED, or the like is used, and an exposure energy that is three times or more of the exposure light is often used as the intensity. In addition to these processes, a pre-exposure process and an auxiliary charging process may be included.
A cartridge using the electrophotographic photosensitive member according to the present invention includes the photosensitive member 1 and at least one portion of the group consisting of the charging unit 2, the exposure unit 3, the developing unit 4, and the cleaning unit 6. Good.

In the present invention, a plurality of components such as the drum-shaped photosensitive member 1, the charging unit 2, the developing unit 4 and the cleaning unit 6 are integrally combined as a drum cartridge, and the drum cartridge is copied. It may be configured to be detachable from the main body of an electrophotographic apparatus such as a machine or a laser beam printer. For example, at least one of the charging unit 2, the developing unit 4, and the cleaning unit 6 can be integrally supported together with the drum-shaped photoreceptor 1 to form a cartridge.
The present invention can also be applied to an image forming apparatus including the electrophotographic photosensitive member, the charging unit 2, the exposure unit 3, the developing unit 4, and the cleaning unit 6 according to the present invention.

  Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. However, the following examples are given in order to explain the present invention in detail, and the present invention is not limited to the examples shown below without departing from the gist thereof, and can be arbitrarily modified and implemented. can do. In addition, the description of “parts” in the following examples and comparative examples indicates “parts by mass” or “parts by weight” unless otherwise specified.

[Example 1]
<Manufacture of coating liquid for undercoat layer formation>
Rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by mass of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were mixed using a Henschel mixer. The surface-treated titanium oxide obtained by mixing was dispersed by a ball mill in a mixed solvent having a mass ratio of methanol / 1-propanol of 7/3 to obtain a surface-treated titanium oxide dispersed slurry. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula (B ) / Hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following formula ( The compound represented by E)] has a composition molar ratio of 60% / 15% / 5% / 15% / 5% and is agitated and mixed with pellets of copolymerized polyamide to dissolve the polyamide pellets. Then, by ultrasonic dispersion treatment, the mass ratio of methanol / 1-propanol / toluene is 7/1/2, and the surface-treated titanium oxide / copolymerized polyamide. Containing in a weight ratio 3/1, to prepare a coating liquid for forming an undercoat layer having a solid concentration of 18.0%.

<Manufacture of coating solution for forming charge generation layer>
First, as a charge generation material, 20 parts of Y-type (also called D-type) oxytitanium phthalocyanine, which has a strong diffraction peak at 27.3 ° in the Bragg angle (2θ ± 0.2) in X-ray diffraction by CuKα rays, 280 parts of 2-dimethoxyethane was mixed and pulverized with a sand grind mill for 1 hour for atomization dispersion treatment. Subsequently, 10 parts of polyvinyl butyral (trade name “Denka Butyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) was added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl. A binder liquid obtained by dissolving in 85 parts of 2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a coating solution for forming a charge generation layer.

<Manufacture of coating liquid for charge transport layer formation>
100 parts of polyarylate resin (4) -1 (viscosity average molecular weight 40,000) having the following repeating structural unit, compound represented by (1) -1 as a charge transport material (in Scheme 2, palladium catalyst) 40 parts), 4 parts of the compound represented by (2) -1 above, 1 part of the compound represented by (3) -1 above, silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd .: trade name) A coating solution for forming a charge transport layer was prepared by dissolving 0.05 part of KF96) in 520 parts of a mixed solvent of tetrahydrofuran / toluene (8/2 (mass ratio)).

<Manufacture of photoconductor>
The undercoat layer-forming coating solution obtained as described above was applied to a polyethylene terephthalate sheet with aluminum deposited on the surface with a wire bar so that the film thickness after drying was about 1.3 μm, and dried at room temperature. An undercoat layer was provided.
Subsequently, the coating solution for forming the charge generation layer obtained as described above was applied on the undercoat layer with a wire bar so that the film thickness after drying was about 0.3 μm, and dried at room temperature. A charge generation layer was provided.
Subsequently, the coating solution for forming a charge transport layer obtained as described above was applied onto the charge generation layer with an applicator so that the film thickness after drying was about 25 μm, and dried at 125 ° C. for 20 minutes. Thus, a photoreceptor was produced.

<Electrical characteristics test>
An electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404 to 405) is used, and the sheet-like photoreceptor is Wound around an 80 mm aluminum cylinder, grounded and charged so that the initial surface potential was about −700 V, and the halogen lamp light was converted to monochromatic light of 780 nm with an interference filter and exposed to 1.3 μJ / cm ^2. The surface potential (exposed portion potential; referred to as VL) was determined. The time from exposure to potential measurement was 100 ms. The measurement environment was 25 ° C. and 50% RH. When the absolute value of VL is large, it indicates that the response to exposure is poor. The results are shown in Table-1.

<Surface resistance measurement>
The charge transport layer coating solution prepared in Example 1 was applied on a 100 μm PET film so that the film thickness after drying was 20 μm. For this charge transport layer sample, the surface resistivity (R1) of the photoreceptor before light exposure was measured under the following conditions using a high resistivity meter, Hiresta-UP and MCP-HT450 (manufactured by Mitsubishi Chemical).
Probe: UR100
・ Applied voltage: 1000V
Measurement time: Subsequently, this sample was irradiated with a fluorescent lamp (MITSUBISHI OSRAM Neormi Super FL15W) at 2000 lux for 10 minutes, and the surface resistance value (R2) was measured immediately thereafter. Table 1 shows the surface resistance values (R1, R2) before and after exposure to light.

<Manufacture of photosensitive drum>
Charge generation used in the manufacture of the photoreceptor of Example 1 on an aluminum cylinder having an outer diameter of 30 mm, a length of 246 mm, and a wall thickness of 0.75 mm, which has been subjected to rough cutting finish, anodized, and cleaned. The layer forming coating solution and the charge transport layer forming coating solution are sequentially applied and dried by a dip coating method, and the charge generation layer and the charge transport layer are formed so that the film thicknesses after drying are 0.4 μm and 18 μm, respectively. The photosensitive drum was manufactured. The charge transport layer was dried at 130 ° C. for 20 minutes.

<Image test>
The obtained photoreceptor is mounted on a cyan photoreceptor cartridge of a tandem full-color printer C711dn (DC roller charging, LED exposure, contact non-magnetic single component development) manufactured by Oki Data Co., Ltd. A halftone image was printed. Next, a fluorescent lamp (MITSUBISHI OSRAM Neorumi Super FL15W) was irradiated on a part of the photoconductor at 2000 lux for 10 minutes, and halftone image printing was performed in the same manner immediately after standing overnight and fluorescent part exposed / non-exposed part. The image density difference was confirmed. The results are shown in Table-1.

[Examples 2 to 5]
In Example 1, a measurement sample was prepared and evaluated in the same manner as in Example 1 except that the charge transport material (1), the compound (2), and the compound (3) were changed as shown in Table-1. Results are shown in Table 1.
Shown in
[Comparative Example 1]
In Example 1, a measurement sample was prepared and evaluated in the same manner as in Example 1 except that Compound (2) and Compound (3) were not used. The results are shown in Table-1.

[Comparative Example 2]
In Example 1, a measurement sample was prepared and evaluated in the same manner as in Example 1 except that the compound (3) was not used. The results are shown in Table-1.
[Comparative Example 3]
In Example 1, a photoreceptor was prepared and evaluated in the same manner as in Example 1 except that 0.1 part of compound (3) was used without using compound (2). The results are shown in Table-1.

[Comparative Example 4]
In Comparative Example 1, a measurement sample was prepared and evaluated in the same manner as Comparative Example 1 except that the charge transport material (1) -1 was changed to (1) -8. The results are shown in Table-1.
[Comparative Example 5]
In Comparative Example 1, a photoconductor was manufactured in the same manner except that the length of the photoconductor drum was changed to 285 mm, and the image test was mounted on a scorotron charging type Epson LP-1500C. Carried out. As a result, density unevenness due to exposure to external exposure was not observed.

[Reference Example 1]
In Comparative Example 1, a measurement sample was prepared and evaluated in the same manner except that CT-A having the following chemical structural formula was used in place of the charge transport material (1) -1. The results are shown in Table-1.

[Reference Example 2]
In Example 1, a measurement sample was prepared and evaluated in the same manner except that CT-A having the above chemical structural formula was used instead of the charge transport material (1) -1. The results are shown in Table-1.
[Reference Example 3]
In Example 1, a measurement sample was prepared and evaluated in the same manner except that CT-B having the following chemical structural formula was used instead of the charge transport material (1) -1. The results are shown in Table-1.

[Reference Example 4]
In Example 1, a measurement sample was prepared and evaluated in the same manner except that CT-C having the following chemical structural formula was used instead of the charge transport material (1) -1. The results are shown in Table-1.

  As shown in Table 1, the photoconductors of Examples 1 to 5 have small surface resistance (R2) after light exposure, but also have a small change in resistance value (R1-R2) due to light exposure, and change in image density. There were few, if any, and it was recovered after being left overnight. On the other hand, in the photoconductors of Comparative Examples 1 to 3, the image resistance difference is observed because the surface resistance value (R2) after light exposure is smaller or the change amount of resistance value (R1-R2) due to light exposure is large. And did not recover even if left overnight. Regarding Reference Examples 1 to 4, the residual potential tended to be high. Particularly in Reference Example 2, when a hindered phenol compound having a partial structure represented by the following formula (2) and an amine compound represented by the following formula (3) were used, the residual potential was further deteriorated.

1 Photoconductor (Electrophotographic photoconductor)
2 Charging device (charging roller; charging unit)
3 Exposure equipment (exposure section)
4 Development device (development unit)
DESCRIPTION OF SYMBOLS 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Control member 71 Upper fixing member (fixing roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper (paper, medium)

Claims (5)

In an electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, a hindered material having a charge transport material represented by the following formula (1) and a partial structure represented by the following formula (2) in the outermost layer. An electrophotographic photoreceptor comprising a phenol compound and an amine compound represented by the following formula (3).
(In Formula (1), Ar < ¹ > -Ar < ⁵ > represents the aryl group which may each independently have a substituent, and Ar < ⁶ > -Ar < ⁹ > may each independently have a substituent. Represents an arylene group, and m and n each independently represents an integer of 1 to 3.
(In formula (2), R ¹ and R ² represent an alkyl group which may have a substituent. However, when both R ¹ and R ² are methyl groups, they are represented by formula (2). (There is only one partial structure in the molecule.)
(In the formula (3), R ³ , R ⁴ and R ⁵ represent an alkylene group having 3 or less carbon atoms which may have a substituent, Ar ¹⁰ and Ar ¹¹ have a hydrogen atom and a substituent. An alkyl group that may be substituted or an aryl group that may have a substituent, Ar ¹² represents an aryl group that may have a substituent, and k represents an integer of 1 or 2. The formula (1) is a compound represented by the following formula (1a), and a hindered phenol compound having a partial structure represented by the formula (2) is represented by the following formula (2) -1 or (2)- The electrophotographic photoreceptor according to claim 1, wherein the amine compound represented by Formula (3) is a compound represented by Formula (3) -1 below.
(In Formula (1a), R ^a represents an alkyl group, an alkoxy group, an aryloxy group, or an aralkyloxy group, and R ^{b to} R ^e each independently represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. )
  The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is used in a contact charging process.   The electrophotographic photosensitive member according to any one of claims 1 to 3, a charging device that charges the electrophotographic photosensitive member, and an exposure that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image. An electrophotographic photosensitive member cartridge comprising: an apparatus; and at least one selected from the group consisting of a developing device that develops an electrostatic latent image formed on the electrophotographic photosensitive member.   The electrophotographic photosensitive member according to claim 1, a charging device that charges the electrophotographic photosensitive member, and an exposure device that forms an electrostatic latent image by exposing the charged electrophotographic photosensitive member. An image forming apparatus comprising: a developing device that develops an electrostatic latent image formed on the electrophotographic photosensitive member.