JP6724855B2 - Electrophotographic photoreceptor, image forming apparatus and process cartridge - Google Patents

Description

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

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

The electrophotographic photosensitive member described in Patent Document 1 has photosensitivity of positive and negative polarities, and the ratio of exposure energy (E _1/2 (negative polarity)/E _1/2 ( Positive polarity)) is 0.5 to 3.

JP, 2007-108671, A

However, in the electrophotographic photoreceptor described in Patent Document 1, it is not possible to suppress the occurrence of exposure memory and maintain excellent sensitivity stability during repeated use of image formation for a long period of time.

The present invention has been made in view of the above problems, and an object thereof is to provide an electrophotographic photoreceptor in which the occurrence of exposure memory is suppressed even in repeated use of image formation for a long period of time, and which is excellent in sensitivity stability. That is. Another object of the present invention is to provide an image forming apparatus and a process cartridge which suppress the occurrence of image defects (for example, image defects caused by the occurrence of exposure memory or the deterioration of sensitivity stability).

The electrophotographic photosensitive member of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer type photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin. The optical response time is 0.05 ms or more and 1.00 ms or less. The light response time is such that the surface potential of the photosensitive layer is attenuated from +800 V to +400 V after the surface of the photosensitive layer charged with a surface potential of +800 V is irradiated with pulsed light having a wavelength of 780 nm and a half width of 40 microseconds. It's time to do it. The intensity of the pulsed light is such that the surface potential changes from +800V to +200V 400 milliseconds after the pulsed light is applied to the surface of the photosensitive layer charged to +800V.

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

The image forming apparatus of the present invention includes an image carrier, a charging unit, an exposing unit, a developing unit, and a transfer unit. The image carrier is the electrophotographic photoreceptor described above. The charging unit charges the surface of the image carrier with a positive polarity. The exposure unit exposes the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier. The developing unit develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the image carrier to a recording medium. The process time is 100 milliseconds or less. The process time is the time from the exposure of a predetermined portion of the surface of the image bearing member by the exposure unit to the development by the developing unit.

The electrophotographic photosensitive member of the present invention can suppress the occurrence of exposure memory even when repeatedly used for image formation for a long period of time, and is excellent in sensitivity stability. Further, the image forming apparatus and the process cartridge of the present invention can suppress the occurrence of image defects.

(A), (b) and (c) are schematic sectional views showing an example of the electrophotographic photosensitive member according to the first exemplary embodiment of the present invention. It is a figure which shows the attenuation curve of the surface potential of a photosensitive layer. It is a figure which shows the measuring device of the optical response time. It is a figure which shows an example of the image forming apparatus which concerns on 2nd embodiment of this invention. It is a figure which shows the image in which the image ghost generate|occur|produced. It is a figure which shows the image for evaluation.

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object of the present invention. It should be noted that although the description may be omitted as appropriate for the overlapping description, the gist of the invention is not limited.

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

Hereinafter, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 3 carbon atoms, carbon Alkenyl groups having 2 to 4 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, aryl groups having 6 to 14 carbon atoms, aralkyl groups having 7 to 20 carbon atoms, and 3 to 14 carbon atoms The heterocyclic group, amino group and cycloalkylidene group having 5 to 7 carbon atoms have the following meanings unless otherwise specified.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

The alkyl group having 1 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, Examples include neopentyl group and hexyl group.

The alkyl group having 1 to 5 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group or Examples include neopentyl group.

The alkyl group having 1 to 4 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group or t-butyl group.

The alkyl group having 1 to 3 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group or an isopropyl group.

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

The alkoxy group having 1 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, s-butoxy group, t-butoxy group, pentyloxy group and iso Examples thereof include a pentyloxy group, a neopentyloxy group and a hexyloxy group.

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

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

The heterocyclic group having 3 to 14 carbon atoms is unsubstituted. The heterocyclic group having 3 or more and 14 or less carbon atoms includes, for example, one or more (preferably 1 or more and 3 or less) heteroatoms and has aromaticity and is a 5- or 6-membered monocyclic heterocycle. A group; a heterocyclic group in which such monocycles are condensed with each other; or a heterocyclic group in which such a monocycle is condensed with a 5- or 6-membered hydrocarbon ring. The heteroatom is one or more selected from the group consisting of a nitrogen atom, a sulfur atom, and an oxygen atom. Examples of the heterocyclic group having 3 to 14 carbon atoms include thiophenyl group, furanyl group, pyrrolyl group, imidazolyl group, pyrazolyl group, isothiazolyl group, isoxazolyl group, oxazolyl group, isoxazolyl group, thiazolyl group, isothiazolyl group, flazanyl. Group, pyranyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, indolyl group, 1H-indazolyl group, isoindolyl group, chromenyl group, quinolinyl group, isoquinolinyl group, purinyl group, pteridinyl group, triazolyl group, tetrazolyl group, 4H A quinolizinyl group, a naphthyridinyl group, a benzofuranyl group, a 1,3-benzodioxolyl group, a benzoxazolyl group, a benzothiazolyl group or a benzimidazolyl group.

The amino group is unsubstituted.

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

<First Embodiment: Electrophotographic Photoreceptor>
With reference to FIG. 1, an electrophotographic photosensitive member (hereinafter, also referred to as a photosensitive member) according to a first embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing an example of the photoconductor 1 according to the first embodiment.

As shown in FIG. 1A, the photoconductor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a single-layer type photosensitive layer. The single-layer type photosensitive layer is one photosensitive layer 3. As shown in FIG. 1A, the photosensitive layer 3 may be directly arranged on the conductive substrate 2.

As shown in FIG. 1B, the photoconductor 1 may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer (undercoat layer) 4. The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. As shown in FIG. 1B, the photosensitive layer 3 may be arranged indirectly on the conductive substrate 2 via the intermediate layer 4. Further, as shown in FIG. 1C, a protective layer 5 may be provided on the photosensitive layer 3.

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

The photosensitive layer contains a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin. The photosensitive layer may further contain additives.

The photoreceptor according to the first embodiment can suppress the occurrence of exposure memory even when repeatedly used for image formation over a long period of time, and has excellent sensitivity stability. The reason is presumed as follows.

For convenience, the exposure memory will be described first. In electrophotographic image formation, for example, an image forming process including the following steps 1) to 4) is performed.
1) A charging step of positively charging the surface of an image carrier (corresponding to a photoconductor),
2) an exposure step of exposing the charged surface of the image bearing member to form an electrostatic latent image on the surface of the image bearing member,
3) a developing step of developing the electrostatic latent image as a toner image, and 4) a transferring step of transferring the toner image from the image carrier to a transfer body.

In such an image forming process, since the image bearing member is rotated and used, an exposure memory may occur due to the exposure step. Specifically, it is as follows. In the charging step, the surface of the image carrier is uniformly charged to a constant positive potential. Subsequently, in the exposure step, the surface of the charged image carrier is exposed to form an electrostatic latent image on the surface of the image carrier. Specifically, photocharges are generated in the photosensitive layer in the exposed area (hereinafter, also referred to as exposed area) on the surface of the image bearing member, and carriers (electrons and holes) are present in the photosensitive layer. , And an electrostatic latent image is formed. The carrier may remain in the photosensitive layer. When the carrier remains, the exposed area is less likely to be charged to a desired positive polarity potential in the charging process of the next circumference with the circumference on which the image carrier forms an image (hereinafter, also referred to as a reference circumference) as a reference. Become. On the other hand, the non-exposed region is likely to be charged to a desired positive potential in the charging process on the next circumference of the reference circumference. As a result, the charged potential differs between the exposed region and the non-exposed region, and it may be difficult to uniformly charge the surface of the image carrier to a constant positive potential. As described above, the exposure in the image forming process (image forming process) on the reference circumference of the image carrier may be affected by the decrease in potential, and the chargeability of the exposed area may be decreased. A phenomenon in which a potential difference occurs in such a charging potential is called an exposure memory.

In the photoconductor according to the first embodiment, since the photoresponse time is 0.05 msec or more and 1.00 msec or less, the carrier generated in the exposure process of the image forming process is promptly exposed on the surface of the photosensitive layer or the conductive layer. Tends to reach the substrate. Therefore, the carrier is unlikely to remain in the photosensitive layer even if images are repeatedly formed. From the above, it is considered that the photoreceptor according to the first embodiment can suppress the occurrence of exposure memory even when image formation is repeated for a long period of time and is excellent in sensitivity stability.

(Optical response time)
The photo response time is the time from the irradiation of the surface of the photosensitive layer charged with a surface potential of +800V with a pulsed light having a wavelength of 780 nm and a half width of 40 microseconds until the surface potential of the photosensitive layer decays from +800V to +400V. is there.

The optical response time will be described with reference to FIG. FIG. 2 shows a decay curve of the surface potential of the photosensitive layer. The vertical axis represents the surface potential (unit: V) of the photosensitive layer. The horizontal axis represents time. In the decay curve of the surface potential of the photosensitive layer, the time that the surface of the photosensitive layer is irradiated with the pulsed light is 0.00 milliseconds. As shown by the decay curve of the surface potential of the photosensitive layer, the surface potential of the photosensitive layer is attenuated from +800V to +200V 400 milliseconds after the surface of the photosensitive layer charged with the surface potential +800V is irradiated with the pulsed light. At this time, the time τ from the irradiation of the surface of the photosensitive layer charged with +800V with the pulsed light to the decay of the surface potential of the photosensitive layer from +800V to +400V is defined as the photoresponse time. The light intensity of the pulsed light is set to an intensity at which the surface potential changes from +800V to +200V 400 milliseconds after the surface of the photosensitive layer charged with +800V is irradiated with the pulsed light.

The photoresponse time of the photoconductor is 0.05 ms or more and 1.00 ms or less, and preferably 0.05 ms or more and 0.70 ms or less.

(Optical response time measurement method)
A method of measuring the photoresponse time of the photoconductor will be described with reference to FIG. FIG. 3 shows an apparatus 50 for measuring the photoresponse time of a photoconductor. The measuring device 50 includes a charging device 52, an exposure device 54, a transparent probe 56, and a potential detection device 58. A drum sensitivity tester (manufactured by Gentec Co., Ltd.) is used as the measuring device 50. First, the photoconductor 1 is attached to the measuring device 50.

The charging device 52 charges the surface 3a of the photosensitive layer 3 of the photoconductor 1 to +800V. As a result, the surface 3a of the photosensitive layer 3 is charged to +800V at the charging position A. The charging position A is a position where the charging device 52 and the surface 3 a of the photosensitive layer 3 come into contact with each other.

In FIG. 3, the photoconductor 1 is rotated in the direction indicated by the solid line arrow to move the charged surface 3a of the photosensitive layer 3 to the exposure position B. The exposure position B is a position where pulsed light is emitted. After the movement, the rotation of the photoconductor 1 is stopped and the position of the photoconductor 1 is fixed. The measurement of the potential (surface potential) of the surface 3a of the photosensitive layer 3 is performed with the photoconductor 1 fixed. The exposure device 54 irradiates the surface 3a of the photosensitive layer 3 charged at the exposure position B with pulsed light (wavelength 780 nm, half value width 40 microseconds). As described above, the light intensity of the pulsed light is set to an intensity at which the surface potential changes from +800 V to +200 V 400 milliseconds after the surface of the photosensitive layer charged with +800 V is irradiated with the pulsed light. The pulsed light is emitted once (one pulse is emitted). A xenon flash lamp (“C4479” manufactured by Hamamatsu Photonics KK) is used as a light source of the exposure device 54. The wavelength and light intensity of the pulsed light are adjusted by an optical filter (not shown). Strictly speaking, the charging device 52 charges the surface 3a of the photosensitive layer 3 to a value slightly larger than +800V. Next, after a predetermined time has passed, when the surface potential of the photosensitive layer 3 is darkly attenuated to +800 V, the exposure device 54 irradiates the surface 3a of the photosensitive layer 3 with pulsed light.

The transparent probe 56 measures the surface potential of the photosensitive layer. The transparent probe 56 is installed on the optical axis of the pulsed light and transmits the pulsed light. In FIG. 3, a dashed arrow pointing from the exposure device 54 to the photoconductor 1 indicates the optical axis of the pulsed light. As the transparent probe 56, a surface electrometer (“3629A” manufactured by Trek Japan KK) is used.

The potential detecting device 58 is electrically connected to the transparent probe 56. The potential detecting device 58 obtains the surface potential of the photosensitive layer 3 for each time measured by the transparent probe 56. Thereby, the decay curve of the surface potential of the photosensitive layer 3 is obtained. From the obtained attenuation curve, the time τ from the irradiation of the surface of the photosensitive layer 3 with the pulsed light to the attenuation of the surface potential of the photosensitive layer 3 from +800 V to +400 V is obtained. The obtained time τ is defined as the optical response time.

Hereinafter, a conductive substrate, an electron transfer material, a hole transfer material, a charge generating agent, a binder resin and an additive will be described as elements of the photoreceptor. Further, a method of manufacturing the photoconductor will be described.

[1. Conductive substrate]
The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoconductor. At least the surface portion of the conductive substrate may be made of a material having conductivity. An example of the conductive substrate is a conductive substrate formed of a material having conductivity. Another example of the conductive substrate is a conductive substrate coated with a material having conductivity. Examples of the material having conductivity include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium or indium. These conductive materials may be used alone or in combination of two or more. Examples of the combination of two or more kinds include alloys (more specifically, aluminum alloys, stainless steel, brass, etc.). Among these materials having conductivity, aluminum or aluminum alloy is preferable because the transfer of charges from the photosensitive layer to the conductive substrate is good. In addition, the conductive substrate may have an oxide film of these conductive materials on its surface.

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

[2. Electron transport material]
Examples of the electron transfer agent include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, Examples thereof include dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, and dibromomaleic anhydride. Examples of the quinone compound include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds and dinitroanthraquinone compounds. These electron transfer agents may be used alone or in combination of two or more.

Among these electron transfer agents, compounds represented by the general formula (ETM1), the general formula (ETM2) or the general formula (ETM3) (hereinafter, may be referred to as electron transfer agents (ETM1) to (ETM3), respectively). ) Is preferably included.

In formula (ETM1), R ⁶¹ and R ⁶⁴ each independently have one or more substituents, an alkyl group having 1 to 6 carbon atoms, and one or more substituents. An alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms which may have one or more substituents, or 7 or more carbon atoms which may have one or more substituents It represents 20 or less aralkyl groups. R ⁶¹ and R ⁶⁴ may be the same or different from each other.

In general formula (ETM1), the alkyl group having 1 to 6 carbon atoms represented by R ⁶¹ and R ⁶⁴ is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a 2-methyl-2-butyl group. .. The alkyl group having 1 to 6 carbon atoms may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group.

In the general formula (ETM1), the alkoxy group having 1 to 6 carbon atoms represented by R ⁶¹ and R ⁶⁴ may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group.

In the general formula (ETM1), the aryl group having 6 to 14 carbon atoms represented by R ⁶¹ and R ⁶⁴ may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, or a carbon atom having 6 to 14 carbon atoms. The following aryl groups may be mentioned.

In general formula (ETM1), the aralkyl group having 7 to 20 carbon atoms represented by R ⁶¹ and R ⁶⁴ may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, or a carbon atom having 6 to 14 carbon atoms. The following aryl groups may be mentioned.

In formula (ETM1), R ⁶¹ and R ⁶⁴ each independently represent an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 5 carbon atoms, and 2-methyl. More preferably, it represents a 2-butyl group. Examples of the electron transfer agent (ETM1) include compounds represented by the chemical formula (ETM-1) (hereinafter, sometimes referred to as electron transfer agent (ETM-1)).

In the general formula (ETM2), R ⁴¹ , R ^42, and R ⁴³ each independently represent a halogen atom, an alkyl group having 1 or more and 6 or less carbon atoms which may have one or more substituents, and one substituent. Alternatively, an alkoxy group having 1 to 6 carbon atoms, which may have a plurality, an aryl group having 6 to 14 carbon atoms, which may have 1 or a plurality of substituents, and one or a plurality of substituents It represents a good aralkyl group having 7 to 20 carbon atoms or a heterocyclic group having 3 to 14 carbon atoms which may have one or more substituents. R ⁴¹ , R ⁴² and R ⁴³ may be the same or different from each other.

In the general formula (ETM2), the alkyl group having 1 to 6 carbon atoms represented by R ⁴¹ , R ⁴² and R ⁴³ is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a t-butyl group. The alkyl group having 1 to 6 carbon atoms may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group.

In general formula (ETM2), the alkoxy group having 1 to 6 carbon atoms represented by R ⁴¹ , R ^42, and R ⁴³ may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group.

In the general formula (ETM2), the aryl group having 6 to 14 carbon atoms represented by R ⁴¹ , R ⁴² and R ⁴³ is preferably a phenyl group. The aryl group having 6 to 14 carbon atoms may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, or a carbon atom having 6 to 14 carbon atoms. The following aryl groups may be mentioned. Of these substituents, a halogen atom is preferable, and a chlorine atom is more preferable. In general formula (ETM2), the aryl group having 6 or more and 14 or less carbon atoms which may have one or more substituents represents an aryl group having 6 or more and 14 or less carbon atoms having one or more substituents. Is more preferable, a phenyl group having one halogen atom is more preferable, and a chlorophenyl group is still more preferable.

In the general formula (ETM2), the aralkyl group having 7 to 20 carbon atoms represented by R ⁴¹ , R ^42, and R ⁴³ may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, or a carbon atom having 6 to 14 carbon atoms. The following aryl groups may be mentioned.

In the general formula (ETM2), the heterocyclic group having 3 to 14 carbon atoms represented by R ⁴¹ , R ⁴² and R ⁴³ may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, or a carbon atom having 6 to 14 carbon atoms. The following aryl groups may be mentioned.

In the general formula (ETM2), R ⁴¹ , R ^42, and R ⁴³ are each independently an aryl group having 6 to 14 carbon atoms which may have a halogen atom, or an alkyl group having 1 to 6 carbon atoms. Is more preferable, a phenyl group having a halogen atom or an alkyl group having 1 to 4 carbon atoms is more preferable, and a chlorophenyl group or a t-butyl group is still more preferable. Examples of the electron transfer agent (ETM2) include a compound represented by the chemical formula (ETM-2) (hereinafter sometimes referred to as electron transfer agent (ETM-2)).

In formula (ETM3), R ³⁹ and R ⁴⁰ each independently have a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have one or more substituents, and one or more substituents. Represents an alkoxy group having 1 to 20 carbon atoms which may be present, an aryl group having 6 to 14 carbon atoms which may have one or more substituents, and an amino group which may have one or more substituents. .. R ³⁹ and R ⁴⁰ may be the same or different from each other.

In the general formula (ETM3), the alkyl group having 1 to 6 carbon atoms represented by R ³⁹ and R ⁴⁰ may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group.

In general formula (ETM3), the alkoxy group having 1 to 6 carbon atoms represented by R ³⁹ and R ⁴⁰ may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group.

In the general formula (ETM3), the aryl group having 6 to 14 carbon atoms represented by R ³⁹ and R ⁴⁰ is preferably a phenyl group. The aryl group having 6 to 14 carbon atoms may have one or more substituents. Examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, or a carbon atom having 6 to 14 carbon atoms. The following aryl groups may be mentioned. Among these substituents, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group or an ethyl group is still more preferable. In the general formula (ETM3), the aryl group having 6 to 14 carbon atoms represented by R ³⁹ and R ⁴⁰ is preferably an aryl group having 6 to 14 carbon atoms and having a plurality of substituents, and 1 to 6 carbon atoms. A phenyl group having a plurality of the following alkyl groups is more preferable, a phenyl group having a plurality of alkyl groups having 1 to 3 carbon atoms is further preferable, and a phenyl group having a methyl group and an ethyl group is particularly preferable.

In the general formula (ETM3), the amino group represented by R ³⁹ and R ⁴⁰ may have one or more substituents. Examples of such a substituent include an alkyl group having 1 to 6 carbon atoms.

In general formula (ETM3), R ³⁹ and R ⁴⁰ preferably represent an aryl group having a plurality of substituents and having 6 to 14 carbon atoms, and a phenyl group having a plurality of alkyl groups having 1 to 6 carbon atoms. Is more preferable, a phenyl group having a plurality of alkyl groups having 1 to 3 carbon atoms is more preferable, and a phenyl group having a methyl group and an ethyl group is particularly preferable. Examples of the electron transfer agent (ETM3) include a compound represented by the chemical formula (ETM-3) (hereinafter sometimes referred to as electron transfer agent (ETM-3)).

The content of the electron transfer agent is 40 parts by mass or more with respect to 100 parts by mass of the binder resin, from the viewpoints of further suppressing the occurrence of exposure memory and further improving the sensitivity stability even in the repeated use of image formation for a long time. Is more preferable, 40 parts by mass or more and 80 parts by mass or less is more preferable, 60 parts by mass or more and 80 parts by mass or less is further preferable, and 70 parts by mass or more and 80 parts by mass or less is further preferable. ..

[3. Hole transport material]
Examples of the hole transfer agent include diamine derivatives (more specifically, N,N,N′,N′-tetraphenylphenylenediamine derivatives, N,N,N′,N′-tetraphenylnaphthylenediamine derivatives). Or N,N,N′,N′-tetraphenylphenanthrylenediamine derivative, etc.), an oxadiazole compound (more specifically, 2,5-di(4-methylaminophenyl)-1,3,3) 4-oxadiazole and the like), styryl compound (more specifically, 9-(4-diethylaminostyryl)anthracene and the like), carbazole compound (more specifically, polyvinylcarbazole and the like), organic polysilane compound, pyrazoline compound (More specifically, 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline, etc.), hydrazone compound, indole compound, oxazole compound, isoxazole compound, thiazole compound, thiadiazole compound, imidazole. System compounds, pyrazole compounds or triazole compounds. These hole transporting agents may be used alone or in combination of two or more.

Among these hole transfer agents, general formula (HTM1), general formula (HTM2), general formula (HTM3), general formula (HTM4), general formula (HTM5), general formula (HTM6) or general formula (HTM7) It is preferable to include at least one of the compounds represented by (hereinafter, sometimes described as hole transport agents (HTM1) to (HTM7), respectively). That is, the photosensitive layer contains at least one of hole transport materials (HTM1) to (HTM-7). The photosensitive layer may contain one type of hole transport material or may contain two or more types of hole transport materials.

From the viewpoint of further suppressing the occurrence of exposure memory and further improving the sensitivity stability of the photoreceptor, the photosensitive layer preferably contains two or more hole transport agents. Examples of the two or more hole transfer agents include hole transfer agents (HTM1) and (HTM3), or hole transfer agents (HTM1) and (HTM4). As the hole-transporting agents (HTM1) and (HTM3), for example, a combination of the hole-transporting agents (HTM-1) and (HTM-3) described later or the hole-transporting agents (HTM-1) and (HTM-). 10) and the combination thereof. Examples of the hole transfer agents (HTM1) and (HTM4) include combinations of hole transfer agents (HTM-1) and (HTM-8) described later.

In formula (HTM1), Q ⁸ , Q ¹⁰ , Q ¹¹ , Q ¹² , Q ¹³ and Q ¹⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 1 to 6 carbon atoms. The following alkoxy group or phenyl group is represented. Q ⁹ and Q ¹⁵ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. b represents an integer of 0 or more and 5 or less. When b represents an integer of 2 or more and 5 or less, a plurality of Q ⁹ bonded to the same phenyl group may be the same or different from each other. c represents an integer of 0 or more and 4 or less. When c represents an integer of 2 or more and 4 or less, a plurality of Q ¹⁵ bonded to the same phenylene group may be the same or different from each other. k represents 0 or 1.

In formula (HTM1), it is preferable that Q ⁸ , Q ¹⁰ , Q ¹¹ , Q ¹² , Q ¹³ and Q ¹⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and hydrogen. An atom or an alkyl group having 1 to 3 carbon atoms is more preferable, and a hydrogen atom, a methyl group or an ethyl group is further preferable. It is preferable that b and c represent 0.

In formula (HTM2), Q ¹⁶ , Q ¹⁷ and Q ¹⁸ each independently represent an alkenyl group having 2 to 4 carbon atoms, which may have one or more phenyl groups, and 1 to 6 carbon atoms. Represents an alkyl group, a phenyl group or an alkoxy group having 1 to 6 carbon atoms. q represents an integer of 0 or more and 4 or less. When q represents an integer of 2 or more and 4 or less, a plurality of Q ¹⁸ bonded to the same phenylene group may be the same or different from each other. m and n each independently represent an integer of 0 or more and 5 or less. When m represents an integer of 2 or more and 5 or less, a plurality of Q ¹⁷ bonded to the same phenyl group may be the same or different from each other. When n represents an integer of 2 or more and 5 or less, a plurality of Q ¹⁶ bonded to the same phenyl group may be the same or different from each other.

In general formula (HTM2), it is preferable that Q ¹⁶ and Q ¹⁷ each independently represent an alkenyl group having 2 to 4 carbon atoms having a plurality of phenyl groups or an alkyl group having 1 to 6 carbon atoms, It is more preferable to represent an ethenyl group having a plurality of phenyl groups or an alkyl group having 1 to 3 carbon atoms, and further preferable to represent a diphenylethenyl group or a methyl group. It is preferable that q represents 0. It is preferable that m and n each independently represent an integer of 0 or more and 2 or less.

In general formula (HTM3), Q ¹ represents a phenyl group which may have an alkyl group having 1 to 6 carbon atoms, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 1 to 6 carbon atoms. The following alkoxy groups are represented. The two Q ¹ may be the same or different from each other. Q ² represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. Q ³ , Q ⁴ , Q ⁵ , Q ⁶ and Q ⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or a phenyl group. Adjacent two of Q ³ , Q ⁴ , Q ⁵ , Q ⁶ , and Q ⁷ may combine with each other to form a ring. a represents an integer of 0 or more and 5 or less. When a represents an integer of 2 or more and 5 or less, a plurality of Q ^{2 s} bonded to the same phenyl group may be the same or different from each other. t represents an integer of 0 or more and 2 or less. The two t's may be the same or different from each other.

In general formula (HTM3), Q ¹ preferably represents a phenyl group which may have an alkyl group having 1 to 6 carbon atoms or a hydrogen atom, and has an alkyl group having 1 to 3 carbon atoms. More preferably, it represents a phenyl group or hydrogen atom which may be present, and even more preferably represents a phenyl group or hydrogen atom which may have a methyl group. Q ² preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and further preferably a methyl group. It is preferable that Q ³ , Q ⁴ , Q ⁵ , Q ⁶ and Q ⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, It is more preferable to represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and a hydrogen atom, a methyl group, an ethyl group, an n-butyl group or an ethoxy group. Is more preferable. It is preferable that a represents 0 or 1. Of Q ³ , Q ⁴ , Q ⁵ , Q ⁶ and Q ⁷ , adjacent two are bonded to each other to form a cycloalkylidene group having 5 to 7 carbon atoms (more specifically, a cyclohexylidene group or the like). It may be formed.

From the viewpoint of further suppressing the generation of exposure memory, the hole transport material preferably has a symmetrical structure. Specifically, in general formula (HTM3), it is preferable that two Q ^1's are the same as each other. Two a's are preferably the same as each other. When a represents an integer of 2 or more, a plurality of Q ² bonded to different benzene rings are preferably the same as each other. Two t's are preferably the same as each other.

In formula (HTM4), Q ¹⁹ , Q ²⁰ , Q ²¹ and Q ²² each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. j represents 0 or 1.

In formula (HTM4), Q ¹⁹ , Q ²⁰ , Q ²¹ and Q ²² each independently represent preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. preferable.

In formula (HTM5), Q ²³ , Q ²⁴ , Q ²⁵ and Q ²⁶ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. u, v, y and z each independently represent an integer of 0 or more and 5 or less. w represents 2 or 3.

In formula (HTM5), Q ²³ , Q ²⁴ , Q ²⁷ and Q ²⁸ preferably represent an alkyl group having 1 to 6 carbon atoms, and preferably an alkyl group having 1 to 3 carbon atoms. It is more preferable that it represents a methyl group. u, v, y and z preferably represent 0 or 1.

In formula (HTM6), Q ³¹ , Q ^33, and Q ³⁵ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. d, e, and f each independently represent an integer of 0 or more and 5 or less. Q ³² , Q ³⁴ and Q ³⁶ are each independently a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a carbon atom number. Represents 1 to 6 alkoxy groups. g, h and i each independently represent 0 or 1.

In general formula (HTM6), Q ³¹ , Q ³³ and Q ³⁵ preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms, More preferably, it represents a methyl group. It is preferable that d, e and f represent 0. Q ³² , Q ³⁴ and Q ³⁶ preferably represent a hydrogen atom. It is preferable that g, h and i represent 1.

In formula (HTM7), Q ⁴⁰ , Q ⁴¹ , Q ⁴² , Q ⁴³ , Q ⁴⁴ and Q ⁴⁵ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. Represents a group. n1, n2, n3, n4, n5 and n6 each independently represent an integer of 0 or more and 5 or less. x, r, and s each independently represent an integer of 0 or more and 5 or less.

In the general formula (HTM7), Q ⁴⁰ and Q ⁴³ represent an alkyl group having 1 to 6 carbon atoms, n1 and n4 represent 1, n2, n3, n5 and n6 represent 0, and x represents 2 It is preferred that r and s represent 0.

In formula (HTM8), Q ⁴⁶ , Q ⁴⁷ , Q ⁴⁸ , Q ⁴⁹ and Q ⁵⁰ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. p represents 0 or 1.

In the general formula ^{(HTM8), Q 46, Q} 47, Q 48, Q 49 and Q ⁵⁰ represents a hydrogen atom.

From the viewpoint of further suppressing the generation of the exposure memory, among the hole transfer agents (HTM1) to (HTM7), the hole transfer agents (HTM1) to (HTM4), (HTM6) and (HTM7) are preferable, and the hole transfer agents are preferable. The agent (HTM6) or (HTM7) is more preferable. From the viewpoint of further improving the sensitivity stability of the photoconductor, among the hole transfer agents (HTM1) to (HTM7), the hole transfer agents (HTM1) to (HTM4), (HTM6) or (HTM7) are preferable, and positive. The hole transport agent (HTM1), (HTM3) or (HTM7) is more preferable, and the hole transport agent (HTM7) is further preferable.

Examples of the hole transport material (HTM1) include compounds represented by the chemical formula (HTM-1) or (HTM-2). Examples of the hole transport material (HTM2) include compounds represented by the chemical formula (HTM-13), (HTM-14) or (HTM-15). Examples of the hole transport material (HTM3) include compounds represented by chemical formulas (HTM-3) to (HTM-6) or (HTM-10) to (HTM-12). Examples of the hole transport material (HTM4) include compounds represented by the chemical formula (HTM-8) or (HTM-9). Examples of the hole transfer agent (HTM5) include compounds represented by the chemical formula (HTM-16) or (HTM-17). Examples of the hole transport material (HTM6) include compounds represented by the chemical formula (HTM-7). Examples of the hole transport material (HTM7) include compounds represented by the chemical formula (HTM-19). Examples of the hole transport material (HTM8) include compounds represented by the chemical formula (HTM-18). Hereinafter, the compounds represented by the chemical formulas (HTM-1) to (HTM-19) may be described as hole transport agents (HTM-1) to (HTM-19), respectively.

From the viewpoint of further suppressing the generation of the exposure memory, the hole transport materials (HTM-1), (HTM-2), (HTM-4) to (HTM-9) and (HTM-11) to (HTM-19). Of these, hole transport agents (HTM-1), (HTM-2), (HTM-4) to (HTM-9), (HTM-11) to (HTM-15) or (HTM-19) are preferable. , Hole transport agents (HTM-2), (HTM-4) to (HTM-7), (HTM-11), (HTM-12) or (HTM-19) are more preferable.

From the viewpoint of further improving the sensitivity stability of the photoreceptor, the hole transport materials (HTM-1), (HTM-2), (HTM-4) to (HTM-9) and (HTM-11) to (HTM-). 19), the hole transport material (HTM-1), (HTM-2), (HTM-4) to (HTM-9), (HTM-11) to (HTM-15) or (HTM-19). Are preferred, and a hole transport material (HTM-2), (HTM-5), (HTM-6) or (HTM-19) is more preferred.

The content of the hole transfer agent is preferably 90 parts by mass or more, more preferably 90 parts by mass or more and 180 parts by mass or less, and 110 parts by mass or more and 180 parts by mass with respect to 100 parts by mass of the binder resin. The amount is more preferably the following, and particularly preferably 150 parts by mass or more and 180 parts by mass or less. Even when the hole transport material is any one of the hole transport materials (HTM1) to (HTM19), the content of the hole transport material is 90 with respect to 100 parts by mass of the binder resin. It can be more than part by mass.

The content of the hole transport material in the photosensitive layer is preferably 30% by mass or more and 60% by mass or less. Examples of components contained in the photosensitive layer include a charge generating agent, a hole transporting agent, an electron transporting agent and a binder resin. When the content of the hole transport material in the photosensitive layer is 30% by mass or more and 60% by mass or less, the occurrence of exposure memory can be further suppressed, and the sensitivity stability of the photoconductor can be further improved.

The ratio m _HTM /m _ETM of the content m _HTM of the hole transfer material to the content m _ETM of the electron transfer material preferably satisfies the mathematical expression (1).
1.2 <m _HTM /m _ETM <3.0...(1)
When the ratio m _HTM /m _ETM satisfies the formula (1), the generation of exposure memory can be further suppressed, and the sensitivity stability of the photoconductor can be further improved.

[4. Charge generator]
As the charge generating agent, for example, perylene pigment, bisazo pigment, trisazo pigment, dithioketopyrrolopyrrole pigment, metal-free naphthalocyanine pigment, metal naphthalocyanine pigment, squaraine pigment, indigo pigment, azurenium pigment, cyanine pigment, inorganic photoconductive pigment Material (more specifically, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon) powder, pyrylium pigment, ansanthuron pigment, triphenylmethane pigment, slene pigment, toluidine pigment, pyrazoline pigment or Examples include quinacridone pigments. The different charge generating agents may be used alone or in combination of two or more.

Examples of the phthalocyanine pigment include metal phthalocyanine and metal-free phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (CGM-1) (hereinafter sometimes referred to as charge generating agent (CGM-1)), hydroxygallium phthalocyanine, or chlorogallium phthalocyanine. As the metal-free phthalocyanine, for example, the metal-free phthalocyanine pigment represented by the chemical formula (CGM-2) (hereinafter, sometimes referred to as a charge generating agent (CGM-2)) phthalocyanine pigment may be a crystal, It may be amorphous. The crystal shape of the phthalocyanine pigment (for example, X type, α type, β type, Y type, V type or II type) is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

Examples of the metal-free phthalocyanine crystals include X-type crystals of metal-free phthalocyanine (hereinafter sometimes referred to as X-type metal-free phthalocyanine). Examples of the crystal of titanyl phthalocyanine include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter may be described as α-type titanyl phthalocyanine, β-type titanyl phthalocyanine, and Y-type titanyl phthalocyanine, respectively). .. Examples of hydroxygallium phthalocyanine crystals include V-type crystals of hydroxygallium phthalocyanine. Examples of the chlorogallium phthalocyanine crystal include II type crystal of chlorogallium phthalocyanine.

For example, in a digital optical image forming apparatus, it is preferable to use a photoconductor having sensitivity in a wavelength region of 700 nm or more. Examples of the digital optical image forming apparatus include a laser beam printer or a facsimile using a light source such as a semiconductor laser. As the charge generating agent, a phthalocyanine pigment is preferable, a titanyl phthalocyanine or a metal-free phthalocyanine is more preferable, and a Y-type titanyl phthalocyanine is more preferable, because it has a high quantum yield in a wavelength region of 700 nm or more.

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

(Measurement method of CuKα characteristic X-ray diffraction spectrum)
A method of measuring the CuKα characteristic X-ray diffraction spectrum will be described. A sample (titanyl phthalocyanine) was filled in a sample holder of an X-ray diffractometer (“RINT (registered trademark) 1100” manufactured by Rigaku Corporation), and an X-ray tube Cu, tube voltage 40 kV, tube current 30 mA, and CuKα characteristic X were obtained. The X-ray diffraction spectrum is measured under the condition that the wavelength of the ray is 1.542Å. The measurement range (2θ) is 3° or more and 40° or less (start angle 3°, stop angle 40°), and the scanning speed is, for example, 10°/min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

Ansanthuron pigment is preferably used as a charge generating agent in a photoreceptor applied to an image forming apparatus using a short wavelength laser light source. The wavelength of the short wavelength laser light is, for example, 350 nm or more and 550 nm or less.

The content of the charge generating agent is preferably 0.1 parts by mass or more and 50 parts by mass or less, more preferably 0.5 parts by mass or more and 30 parts by mass or less, with respect to 100 parts by mass of the binder resin, It is particularly preferable that the amount is 0.5 parts by mass or more and 6 parts by mass or less.

[5. Binder resin]
Examples of the binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include polycarbonate resin, polyarylate resin, styrene-butadiene resin, styrene-acrylonitrile resin, styrene-maleic acid resin, acrylic acid-based resin, styrene-acrylic acid resin, polyethylene resin, ethylene-vinyl acetate resin. , Chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate resin, alkyd resin, polyamide resin, urethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyester resin or Examples include polyether resins. Examples of the thermosetting resin include silicone resin, epoxy resin, phenol resin, urea resin and melamine resin. Examples of the photocurable resin include epoxy-acrylic acid type resins (more specifically, acrylic acid derivative adducts of epoxy compounds) or urethane-acrylic acid type resins (acrylic acid derivative adducts of urethane compounds). Can be mentioned. These binder resins may be used alone or in combination of two or more.

Among these resins, a polycarbonate resin is preferable because it provides a photosensitive layer having an excellent balance of processability, mechanical strength, optical characteristics, and abrasion resistance, and is preferably a polycarbonate represented by the chemical formula (PC-1). A polycarbonate resin having a unit (hereinafter sometimes referred to as a polycarbonate resin (PC-1)) is more preferable.

The binder resin has a viscosity average molecular weight of preferably 20,000 or more, more preferably 30,000 or more and 70,000 or less, and further preferably 40,000 or more and 60,000 or less. When the viscosity average molecular weight of the binder resin is 3000 or more, it is easy to improve the abrasion resistance of the photoconductor. When the viscosity average molecular weight of the binder resin is 70,000 or less, the binder resin is easily dissolved in the solvent during formation of the photosensitive layer, and the viscosity of the photosensitive layer coating solution does not become too high. As a result, it becomes easy to form the photosensitive layer.

[6. Additive]
The photosensitive layer may contain various additives as required. Examples of the additives include deterioration inhibitors (more specifically, antioxidants, radical scavengers, quenchers or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersions. Examples include stabilizers, waxes, donors, surfactants, plasticizers, sensitizers or leveling agents.

[7. Manufacturing Method of Photoreceptor]
The photoconductor is manufactured, for example, by applying a coating solution for photosensitive layer on a conductive substrate, forming a coating film, and drying the coating film. The coating liquid for the photosensitive layer is prepared, for example, by dissolving or dispersing a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and an additive added as necessary in a solvent. To be done.

The solvent contained in the photosensitive layer coating liquid (hereinafter, also referred to as coating liquid) is not particularly limited as long as it can dissolve or disperse each component contained in the coating liquid. Examples of the solvent include alcohols (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbons (more specifically, n-hexane, octane, cyclohexane, etc.), aromatic hydrocarbons ( More specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, etc.), ethers (more specifically, dimethyl ether, diethyl ether, Tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or propylene glycol monomethyl ether, etc.), ketone (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), ester (more specifically, ethyl acetate or methyl acetate, etc.), dimethyl Formaldehyde, dimethylformamide or dimethylsulfoxide may be mentioned. These solvents may be used alone or in combination of two or more. A non-halogen solvent (a solvent other than a halogenated hydrocarbon) is preferably used as the solvent in order to improve workability during the production of the photoreceptor.

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

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

The method for applying the coating liquid is not particularly limited as long as it is a method capable of uniformly applying the coating liquid on the conductive substrate. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

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

The method for producing the photoreceptor may further include one or both of the step of forming the intermediate layer and the step of forming the protective layer, if necessary. In the step of forming the intermediate layer and the step of forming the protective layer, known methods are appropriately selected.

<Second embodiment: image forming apparatus>
The second embodiment relates to an image forming apparatus. Hereinafter, one aspect of the image forming apparatus according to the second embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of the image forming apparatus according to the second embodiment. The image forming apparatus 90 according to the second embodiment includes an image forming unit 40. The image forming unit 40 includes an image carrier 30, a charging unit 42, an exposing unit 44, a developing unit 46, and a transfer unit 48. The image carrier 30 is the photoconductor according to the first embodiment. The charging unit 42 positively charges the surface of the image carrier 30. The exposure unit 44 exposes the charged surface of the image carrier 30 to form an electrostatic latent image on the surface of the image carrier 30. The developing unit 46 develops the electrostatic latent image as a toner image. The transfer unit 48 transfers the toner image from the image carrier 30 to the recording medium M. The process time is 100 milliseconds or less. The process time is the time from the exposure of a predetermined portion on the surface of the image carrier 30 by the exposure unit 44 to the development by the developing unit 46. The outline of the image forming apparatus 90 according to the second embodiment has been described above.

The image forming apparatus 90 according to the second embodiment can suppress an image defect due to the occurrence of an exposure memory and a decrease in sensitivity stability. The reason is presumed as follows. The image forming apparatus 90 according to the second embodiment includes the photoconductor according to the first embodiment as the image carrier 30. The photoconductor according to the first embodiment can suppress the occurrence of exposure memory even when repeatedly used for image formation over a long period of time, and is excellent in sensitivity stability. Therefore, the image forming apparatus 90 according to the second embodiment can suppress the image defect due to the occurrence of the exposure memory and the deterioration of the sensitivity stability.

An image defect caused by the occurrence of the exposure memory will be described. When the exposure memory is generated in the image forming process as described above, a region where the surface of the image carrier 30 cannot obtain a desired electric potential is desired in the charging process of the next circumference with respect to the reference circumference of the photoreceptor in the image formation. The potential tends to be lower than the region where the potential is obtained. Specifically, in the exposed area of the reference circumference on the surface of the image carrier 30, the electric potential tends to be lower during charging of the next circumference of the reference circumference than in the unexposed area of the reference circumference. For this reason, in the exposed area of the reference circumference, the potential during charging tends to be lower than in the non-exposed area of the reference circumference, so that the positively charged toner is easily attracted during development. As a result, an image that reflects the image portion (exposure area) of the reference circumference is easily formed. An image defect in which an image that reflects the image portion of the reference circumference is formed is an image defect that occurs due to the exposure memory (hereinafter, also referred to as an image ghost).

An image having an image defect will be described with reference to FIG. FIG. 5 is a diagram showing an image 60 in which an image ghost has occurred. The image 60 includes a region 62 and a region 64. The area 62 is an area corresponding to one revolution of the image carrier, and the area 64 is also an area corresponding to one revolution of the image carrier. Therefore, when the circumference of the photoconductor for forming the image of the area 62 is the reference circumference, the circumference of the photoconductor for forming the image of the area 64 is the next circumference of the reference circumference. Region 62 includes image 66. The image 66 is composed of a donut-shaped solid image. Region 64 includes image 68 and image 69. The image 68 is a donut-shaped white halftone image. The image 68 has an image density equivalent to the design image density. The image 69 is a donut-shaped halftone image in the area 64. The image 69 has a higher image density than the image 68. The image 69 is an image defect (image ghost) that reflects the image 66 of the exposed region of the region 62 and is darker than the design image density. It should be noted that the image of the area 64 is composed of a full-tone halftone image on the design image.

Hereinafter, each unit included in the image forming apparatus 90 will be described in detail. An image forming apparatus 90 according to the second embodiment will be described with reference to FIG. The image forming apparatus 90 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 90 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. When the image forming apparatus 90 is a color image forming apparatus, the image forming apparatus 90 adopts a tandem system, for example. Hereinafter, the tandem type image forming apparatus 90 will be described as an example.

The image forming apparatus 90 further includes a transfer belt 38 and a fixing unit 36. The image forming apparatus 90 can employ a so-called chargeless system. That is, in the image forming apparatus 90 that adopts the static elimination less method, the image carrier 30 is recharged by the charging unit 42 to the area that has been transferred to the recording medium M without performing static elimination. Normally, in an image forming apparatus that employs a static elimination-free system, an image defect due to an exposure memory is likely to occur. However, the image forming apparatus 90 according to the second embodiment includes the photoconductor according to the first embodiment as the image carrier 30. The photoconductor according to the first embodiment can suppress the occurrence of exposure memory even when the image formation is repeatedly used for a long time. Therefore, the image forming apparatus 90 according to the second embodiment can suppress the occurrence of image defects due to the exposure memory even if the static elimination less method is adopted.

The image forming unit 40 can further include a cleaning unit (more specifically, a blade cleaning unit) and a charge eliminating unit (both shown in the drawing). The image carrier 30 is provided at the center of the image forming unit 40. The image carrier 30 is rotatably provided in the arrow direction (counterclockwise). Around the image carrier 30, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48 are provided in order from the upstream side in the rotation direction of the image carrier 30 with the charging unit 42 as a reference. The image forming unit 40 does not have to include a cleaning blade, that is, a blade cleaning less method can be adopted.

Toner images of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) are sequentially superposed on the recording medium M on the transfer belt 38 by each of the image forming units 40a to 40d. When the image forming apparatus 90 is a monochrome image forming apparatus, the image forming apparatus 90 includes the image forming unit 40a and the image forming units 40b to 40d are omitted.

The charging unit 42 is a charging roller. The charging roller charges the surface of the image carrier 30 while contacting the surface of the image carrier 30. As another example of the contact charging type charging unit, a charging brush may be used. The charging unit 42 may be a non-contact type. Examples of the non-contact type charging unit include a corotron charging unit and a scorotron charging unit.

The voltage applied by the charging unit 42 is not particularly limited. Examples of the voltage applied by the charging unit 42 include a DC voltage, an AC voltage, and a superposed voltage (a voltage obtained by superposing an AC voltage on a DC voltage), and more preferably a DC voltage. The DC voltage has the following advantages over the AC voltage or the superimposed voltage. When the charging unit 42 applies only the DC voltage, the voltage value applied to the image carrier 30 is constant, so that the surface of the image carrier 30 is easily uniformly charged to a constant potential. Further, when the charging unit 42 applies only the DC voltage, the abrasion amount of the photosensitive layer tends to decrease. As a result, a suitable image can be formed.

The exposure unit 44 exposes the surface of the charged image carrier 30. As a result, an electrostatic latent image is formed on the surface of the image carrier 30. The electrostatic latent image is formed based on the image data input to the image forming apparatus 90.

The developing unit 46 develops the electrostatic latent image as a toner image using a developer. The developer may be a one-component developer or a two-component developer. The process time between the exposure section 44 and the development section 46 is 100 milliseconds or less. This process time is the time from the exposure of the predetermined portion on the surface of the image carrier 30 by the exposure unit 44 to the development by the developing unit 46. More precisely, it is the time from the start of irradiation of a predetermined portion of the surface of the image carrier 30 with exposure light to the start of development. This process time corresponds to the peripheral speed of the image carrier 30.

The transfer belt 38 conveys the recording medium M between the image carrier 30 and the transfer section 48. The transfer belt 38 is an endless belt. The transfer belt 38 is provided so as to be rotatable in the arrow direction (clockwise direction).

The transfer unit 48 transfers the toner image developed by the developing unit 46 from the surface of the image carrier 30 to the recording medium M. Examples of the transfer unit 48 include a transfer roller.

The fixing unit 36 heats and/or pressurizes the unfixed toner image transferred onto the recording medium M by the transfer unit 48. The fixing unit 36 is, for example, a heating roller and/or a pressure roller. The toner image is fixed on the recording medium M by heating and/or pressing the toner image. As a result, an image is formed on the recording medium M.

<Third Embodiment: Process Cartridge>
The third embodiment relates to a process cartridge. The process cartridge according to the third embodiment includes the photoconductor according to the first embodiment. A process cartridge according to the third embodiment will be described with reference to FIG.

The process cartridge includes a unitized image carrier. The process cartridge employs a configuration in which, in addition to the image carrier 30, at least one selected from the group consisting of a charging section 42, an exposing section 44, a developing section 46, and a transfer section 48 is unitized. The process cartridge corresponds to, for example, each of the image forming units 40a to 40d. The process cartridge may further include a static eliminator (not shown). The process cartridge is designed to be attachable to and detachable from the image forming apparatus 90. Therefore, the process cartridge is easy to handle, and when the sensitivity stability of the image carrier 30 is deteriorated, the process cartridge including the image carrier 30 can be replaced easily and quickly.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is in no way limited to the scope of the examples.

<1. Material of photoconductor>
As materials for forming the single-layer type photosensitive layer of the single-layer type photoreceptor, the following electron transporting agent, hole transporting agent, charge generating agent and binder resin were prepared.

[1-1. Electron transport material]
The electron transfer materials (ETM-1) to (ETM-3) described in the first embodiment were prepared.

[1-2. Hole transport material]
The hole transport materials (HTM-1) to (HTM-19) described in the first embodiment were prepared. In addition, a hole-transporting agent represented by the chemical formula (HTM-20) (hereinafter sometimes referred to as a hole-transporting agent (HTM-20)) was prepared.

[1-3. Charge generator]
[1-3-1. Y-type titanyl phthalocyanine]
The charge generating agents (CGM-1) to (CGM-2) described in the first embodiment were prepared. The charge generating agent (CGM-1) was titanyl phthalocyanine (Y-type titanyl phthalocyanine) represented by the chemical formula (CGM-1). The crystal structure of the charge generating agent (CGM-2) was Y-type.

The Y-type titanyl phthalocyanine crystal has a Bragg angle 2θ±0.2°=9.2°, 14.5°, 18.1°, 24.1°, 27.2° in the CuKα characteristic X-ray diffraction spectrum chart. It had a peak, and the main peak was 27.2°. The CuKα characteristic X-ray diffraction spectrum was measured with the measuring device and the measuring conditions described in the first embodiment.

In the differential scanning calorimetry spectrum, Y-type titanyl phthalocyanine does not have a peak in the range of 50° C. or higher but lower than 270° C. and has a single peak in the range of 270° C. or higher but 400° C. or lower in addition to the peak associated with vaporization of adsorbed water. Had. The differential scanning calorimetry spectrum was measured with the measuring device and measuring conditions described in the first embodiment.

[1-3-2. X-type metal-free phthalocyanine]
The charge generating agent (CGM-2) was a metal-free phthalocyanine represented by the chemical formula (CGM-2) (X-type metal-free phthalocyanine). The crystal structure of the charge generating agent (CGM-2) was X-type.

[1-4. Binder resin]
As the binder resin, the polycarbonate resin (PC-1) described in the first embodiment (viscosity average molecular weight: 40,000) was prepared.

<2. Manufacture of photoconductor>
Photoconductors (A-1) to (A-27) and photoconductors (B-1) to (B-3) were produced using the materials for forming the photoconductive layer.

[2-1. Production of Photoreceptor (A-1)]
4 parts by mass of charge generating agent (CGM-1), 110 parts by mass of hole transferring material (HTM-1), 55 parts by mass of electron transferring material (ETM-1), and 100 parts by mass of polycarbonate resin (PC-1). And 800 parts by mass of tetrahydrofuran as a solvent were charged into the container. Using a ball mill, the materials in the container (charge generation agent (CGM-1), hole transfer agent (HTM-1), electron transfer agent (ETM-1) and polycarbonate resin (PC-1)) and the solvent were mixed. Mix for 50 hours to disperse the material in the solvent. As a result, a photosensitive layer coating liquid was obtained. The photosensitive layer coating liquid was coated on a drum-shaped support made of aluminum as a conductive substrate by a dip coating method to form a coating film. The coating film was dried with hot air at 120° C. for 60 minutes. As a result, a single-layer type photosensitive layer (film thickness 28 μm) was formed on the conductive substrate. As a result, a photoconductor (A-1) was obtained. In the photoconductor (A-1), the content ratio of the hole transfer agent to the mass of the photosensitive layer ({110 parts by mass/(4 parts by mass+110 parts by mass+55 parts by mass+100 parts by mass)}×100) is 41. %Met. The ratio m _HTM /m _ETM (110 parts/55 parts by mass) of the content m _HTM of the hole transferring material to the content m _ETM of the electron transferring material was 2.00.

[2-2. Production of Photoreceptors (A-2) to (A-27) and Photoreceptors (B-1) to (B-3)]
Except for changing the following points, the photoconductors (A-2) to (A-27) and the photoconductors (B-1) to (B-3) were produced in the same manner as in the production of the photoconductor (A-1). ) Were produced respectively. The charge generating agent (CGM-1) used in the production of the photoconductor (A-1) was changed to the type of charge generating agent shown in any one of Tables 1 to 3. 55 parts by mass of the electron transfer agent (ETM-1) used in the production of the photoconductor (A-1) was changed to the type and content of the electron transfer agent shown in any of Tables 1 to 3. 110 parts by mass of the hole transfer agent (HTM-1) used in the production of the photoconductor (A-1) was changed to the kind and content of the hole transfer agent shown in any of Tables 1 to 3.

Tables 1 to 3 show the configurations of the photoconductors (A-1) to (A-27) and the photoconductors (B-1) to (B-3). In Tables 1 to 3, CGM, HTM and ETM represent a charge generating agent, a hole transferring material and an electron transferring material, respectively. In Tables 1 to 3, C-1 and C-2 in the column "CGM" represent Y-type titanyl phthalocyanine crystals (charge-generating agent (CGM-1)) and X-type metal-free phthalocyanine (charge-generating agent (CGM-2), respectively. )) is shown. HTM-1 to HTM-20 in the column "HTM" represent hole transport materials (HTM-1) to (HTM-20), respectively. The content (parts) in the column “HTM” indicates the content (unit: parts by mass) of the hole transfer agent with respect to 100 parts by mass of the binder resin. ETM-1 to ETM-3 in the column "ETM" represent electron transfer agents (ETM-1) to (ETM-3), respectively. The content (parts) in the column “ETM” indicates the content (unit: parts by mass) of the electron transfer agent with respect to 100 parts by mass of the binder resin. The content in the column “HTM” indicates the ratio (unit: %) of the mass of the hole transfer agent to the total mass of the components (charge generation agent, hole transfer agent, electron transfer agent and binder resin) in the photosensitive layer. ..

<3. Characteristics of photoconductor>
[3-1. Optical response time measurement method]
The photoresponse time of the photoconductor was measured using the photoresponse time measurement method described in the first embodiment. The photoresponsive time of the photoreceptor was measured under an environment of a temperature of 25° C. and a relative humidity of 50% RH.

<4. Evaluation of photoconductor>
[4-1. Image defect (image ghost) evaluation]
An image defect (image ghost) was evaluated for each of the photoconductors (A-1) to (A-27) and the photoconductors (B-1) to (B-3). The image defect was evaluated under the environment of a temperature of 10° C. and a relative humidity of 15% RH.

The photoreceptor was attached to the evaluation machine. As the evaluation machine, a color image forming apparatus ("FS-C5250DN" modified machine manufactured by Kyocera Document Solutions Co., Ltd.) was used. This evaluation machine was equipped with a scorotron charging device as a non-contact charging type charging unit. This evaluation machine was not provided with a charge removal section and a cleaning blade as a cleaning section. The charging potential was set to +700V. The peripheral speed of the photoconductor was adjusted so that the exposure-development process time was 75 milliseconds.

First, a printing test was conducted by printing 3,000 print patterns (printing rate 4%) on a recording medium (A4 size paper) at intervals of 15 seconds. Then, an image for evaluation was created by the following operation.

The evaluation image will be described with reference to FIG. FIG. 6 is a diagram showing the evaluation image 70. The evaluation image 70 includes a region 72 and a region 74. The area 72 is an area corresponding to one round of the image carrier. Region 72 includes image 76. The image 76 is composed of a donut-shaped solid image (image density 100%). This solid image is composed of two sets of concentric circles. The area 74 is an area corresponding to one rotation of the image carrier. Region 74 includes image 78. The image 78 is composed of an entire halftone image (image density 40%). First, an image 76 of the area 72 was formed, and then an image 78 of the area 74 was formed. The circumference of the photoconductor on which the image 78 is formed is the next circumference with respect to the reference circumference of the photoconductor on which the image 76 is formed.

Next, the image obtained after the printing test was used as an evaluation image. The evaluation image was visually observed to confirm the presence or absence of an image corresponding to the image 76 in the area 74. Here, the visual observation is an observation with the naked eye (visual observation) or an observation through a magnifying glass (magnification 10 times, TL-SL10K manufactured by TRUSCO) (loupe observation). It was confirmed whether an image defect (image ghost) due to the exposure memory occurred. From the observation result of the evaluation image, the presence or absence of the image ghost was evaluated based on the following criteria. The evaluation results are shown in Tables 1 to 3. The evaluations A to C were passed.
(Evaluation criteria for image ghosts)
Evaluation A: No image ghost corresponding to the image 76 was observed.
Evaluation B: A slight image ghost corresponding to the image 76 was observed.
Evaluation C: An image ghost corresponding to the image 76 was observed, but the level was not a problem in practical use.
Evaluation D: An image ghost corresponding to the image 76 was clearly observed, which was at a practically problematic level.

[4-2. Evaluation of sensitivity stability: measurement of desensitization amount]
The sensitivity stability of each of the photoconductors (A-1) to (A-27) and the photoconductors (B-1) to (B-3) was evaluated. The evaluation of sensitivity stability was performed in an environment of a temperature of 10° C. and a relative humidity of 15% RH.

The photoreceptor was attached to the evaluation machine. As the evaluation machine, a color image forming apparatus ("FS-C5250DN" modified machine manufactured by Kyocera Document Solutions Co., Ltd.) was used. This evaluation machine was equipped with a scorotron charging device as a non-contact charging type charging unit. This evaluation machine was not provided with a charge removal section and a cleaning blade as a cleaning section. The charging potential was set to +700V. The peripheral speed of the photoconductor was adjusted so that the exposure-development process time was 75 milliseconds.

The surface of the photoconductor was charged to +700 V, exposed, and the surface potential of the photoconductor was measured at the developing position. The measured surface potential of the photoconductor was defined as the initial post-exposure potential V _L1 (unit: V).

Next, a printing test was conducted by printing 3,000 print patterns (printing rate 4%) on a recording medium (A4 size paper) at intervals of 15 seconds. After the printing test, the surface of the photoconductor was charged to +700 V and exposed. The surface potential of the photoconductor was measured at the developing position. The measured surface potential of the photoconductor was used as the post-exposure potential V _L2 (unit: V) after the printing test. The light amount of exposure was a light amount for forming a halftone image (image density 60%).

The desensitization amount (unit: V) was calculated from the obtained initial post-exposure potential V _L1 and the post-exposure potential V _L2 after the printing test using the mathematical expression (2).
Desensitizing amount _{= V L2 -V L1 ··· (2} )

Based on the obtained desensitization amount, the sensitivity stability of the photoconductor was evaluated based on the following criteria. The evaluation results are shown in Tables 1 to 3. The evaluations A to C were passed.
(Evaluation criteria for sensitivity stability)
Evaluation A: The desensitization amount was less than 10V.
Evaluation B: The desensitization amount was 10 V or more and less than 25 V.
Evaluation C: The desensitization amount was 25 V or more and less than 40 V.
Evaluation D: The desensitization amount was 40 V or more.

As shown in Tables 1 and 2, in the photoconductors (A-1) to (A-27), the photosensitive layer contains a charge generating agent, a hole transfer agent, an electron transfer agent, and a binder resin. I was out. The photoresponse time was 0.18 milliseconds or more and 0.97 milliseconds or less. For the photoconductors (A-1) to (A-27), the desensitization amount evaluation was one of evaluations A, B and C, and the image evaluation was one of evaluations A, B and C.

As shown in Table 3, in the photoconductors (B-1) to (B-3), the photoresponse time was 2.49 ms or more and 82.00 ms or less, respectively. For the photoconductors (B-1) to (B-3), the desensitization amount evaluation was evaluation D, and the image evaluation was evaluation D.

Compared to the photoconductors (B-1) to (B-3), the photoconductors (A-1) to (A-27) can suppress the occurrence of exposure memory even when image formation is repeated over a long period of time. And has excellent sensitivity stability. Further, the image forming apparatus including any of the photoconductors (A-1) to (A-27) has a defective image as compared with the image forming apparatus including the photoconductors (B-1) to (B-3). Can be suppressed.

The photoconductor according to the present invention can be used in an image forming apparatus.

1 Electrophotographic Photoreceptor 2 Conductive Substrate 3 Photosensitive Layer

Claims (11)

An electrophotographic photoreceptor for positive charging comprising a conductive substrate and a photosensitive layer,
The photosensitive layer is a single-layer type photosensitive layer,
The photosensitive layer contains a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin,
The content of the hole transport material is 110 parts by mass or more and 180 parts by mass or less with respect to 100 parts by mass of the binder resin,
The ratio mHTM/mETM of the content mHTM of the hole transfer material to the content mETM of the electron transfer material is 2.0 or more and 2.3 or less,
The hole transport material contains at least one of the compounds represented by the general formulas (HTM1) to (HTM4), (HTM6) and (HTM7),
The optical response time is 0.05 ms or more and 0.57 ms or less,
The optical response time is attenuated after being irradiated on the front surface of the photosensitive layer pulsed light having a wavelength of 780nm and a half value width 40 microseconds is charged to a surface potential + 800 V, the surface potential of the photosensitive layer is from + 800 V to + 400V It's time to do
The electrophotographic photoreceptor, wherein the intensity of the pulsed light is such that the surface potential changes from +800V to +200V 400 milliseconds after the pulsed light is applied to the surface of the photosensitive layer charged to +800V.

In the general formula (HTM1),
Q ⁸ , Q ¹⁰ , Q ¹¹ , Q ¹² , Q ¹³ and Q ¹⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or a phenyl group. Represents
Q ⁹ and Q ¹⁵ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group,
b represents an integer of 0 or more and 5 or less, and when b represents an integer of 2 or more and 5 or less, a plurality of Q ⁹ bonded to the same phenyl group may be the same or different from each other,
c represents an integer of 0 or more and 4 or less, and when c represents an integer of 2 or more and 4 or less, a plurality of Q ¹⁵ bonded to the same phenylene group may be the same or different from each other,
k represents 0 or 1,
In the general formula (HTM2),
Q ¹⁶ , Q ¹⁷ and Q ¹⁸ are each independently an alkenyl group having 2 to 4 carbon atoms, which may have one or more phenyl groups, an alkyl group having 1 to 6 carbon atoms, a phenyl group or Represents an alkoxy group having 1 to 6 carbon atoms,
q represents an integer of 0 or more and 4 or less, and when q represents an integer of 2 or more and 4 or less, a plurality of Q ¹⁸ bonded to the same phenylene group may be the same or different from each other,
m and n each independently represent an integer of 0 or more and 5 or less, and when m represents an integer of 2 or more and 5 or less, a plurality of Q ¹⁷ bonded to the same phenyl group may be the same or different from each other. Well, when n represents an integer of 2 or more and 5 or less, a plurality of Q ¹⁶ bonded to the same phenyl group may be the same or different from each other,
In the general formula (HTM3),
Q ¹ represents a phenyl group which may have an alkyl group having 1 to 6 carbon atoms, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms,
The two Q ¹ may be the same or different from each other,
Q ² represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group,
Q ³ , Q ⁴ , Q ⁵ , Q ⁶ and Q ⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or a phenyl group; Adjacent two of Q ³ , Q ⁴ , Q ⁵ , Q ⁶ and Q ⁷ may combine with each other to form a ring,
a represents an integer of 0 or more and 5 or less, and when a represents an integer of 2 or more and 5 or less, a plurality of Q ^{2 s} bonded to the same phenyl group may be the same or different from each other,
t represents an integer of 0 or more and 2 or less, and two t may be the same or different from each other,
In the general formula (HTM4),
Q ¹⁹ , Q ²⁰ , Q ²¹ and Q ²² each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
j represents 0 or 1,
In the general formula (HTM6),
Q ³¹ , Q ³³ and Q ³⁵ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or a phenyl group,
d, e and f each independently represent an integer of 0 or more and 5 or less,
Q ³² , Q ³⁴ and Q ³⁶ are each independently a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a carbon atom number. Represents an alkoxy group of 1 or more and 6 or less,
g, h, and i each independently represent 0 or 1.
In the general formula (HTM7),
Q ⁴⁰ , Q ⁴¹ , Q ⁴² , Q ⁴³ , Q ⁴⁴ and Q ⁴⁵ each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms,
n1, n2, n3, n4, n5 and n6 each independently represent an integer of 0 or more and 5 or less,
x, r, and s each independently represent an integer of 0 or more and 5 or less. The electrophotographic photosensitive member according to claim 1, wherein the content ratio of the hole transport material with respect to the mass of the photosensitive layer is 30% by mass or more and 60% by mass or less. In the general formula (HTM1),
Q ⁸ , Q ¹⁰ , Q ¹¹ , Q ¹² , Q ¹³ and Q ¹⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,
b and c represent 0,
In the general formula (HTM2),
Q ¹⁶ and Q ¹⁷ each independently represent an alkenyl group having 2 to 4 carbon atoms having a plurality of phenyl groups or an alkyl group having 1 to 6 carbon atoms,
q represents 0,
m and n each independently represent an integer of 0 or more and 2 or less,
In the general formula (HTM3),
Q ¹ represents a phenyl group which may have an alkyl group having 1 to 6 carbon atoms or a hydrogen atom,
Q ² represents an alkyl group having 1 to 6 carbon atoms,
Q ³ , Q ⁴ , Q ⁵ , Q ⁶ and Q ⁷ each independently represent a hydrogen atom, an alkoxy group having 1 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms,
Q ^3, Q ^4, Q ^5, among the Q ⁶ and Q ^7, bound two adjacent to each other may form a cycloalkylidene group having 5 to 7 carbon atoms,
a represents 0 or 1,
In the general formula (HTM4),
Q ¹⁹ , Q ²⁰ , Q ²¹ and Q ²² each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms ,
During the previous following general formula (HTM6),
Q ³¹ , Q ³³ and Q ³⁵ represent an alkyl group having 1 to 6 carbon atoms,
d, e and f represent 0,
Q ³² , Q ³⁴ and Q ³⁶ represent a hydrogen atom,
g, h and i represent 1,
In the general formula (HTM7),
Q ⁴⁰ and Q ⁴³ represent an alkyl group having a carbon source prime number of 1 or more and 6 or less,
n1 and n4 represent 1,
n2, n3, n5 and n6 represent 0,
x represents 2,
r and s represent 0, electrophotographic photosensitive member according to claim 1 or 2. The hole transport material is at least one of compounds represented by the formula (HTM-1) ~ (HTM -15) and (HTM-19), according to any one of claims 1 to 3 Electrophotographic photoreceptor.

The electrophotographic photoreceptor according to claim 1, wherein the hole transport material contains a compound represented by the general formula (HTM7). The electrophotographic photosensitive member according to claim 4, wherein the hole transport material is a compound represented by the chemical formula (HTM-19). 7. The electrophotographic photosensitive member according to claim 5, wherein the photosensitive layer contains only one kind of the hole transport material. The electrophotographic photoreceptor according to claim 1, wherein the charge generating agent is Y-type titanyl phthalocyanine. A process cartridge comprising the electrophotographic photosensitive member according to claim 1. An image carrier,
A charging unit that charges the surface of the image carrier to a positive polarity,
An exposure unit that exposes the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier;
A developing unit for developing the electrostatic latent image as a toner image,
An image forming apparatus comprising: a transfer unit that transfers the toner image from the image carrier to a recording medium,
The image carrier is the electrophotographic photosensitive member according to any one of claims 1 to 8,
The process time is less than 100 ms,
The image forming apparatus is an image forming apparatus, wherein the process time is a time from when a predetermined portion of the surface of the image carrier is exposed in the exposure section to when it is developed in the developing section. The image forming apparatus according to claim 10, wherein the image carrier is recharged by the charging unit without performing static elimination on a region that has been transferred to the recording medium.

Images