WO2018061368A1 - Electrographic photoreceptor, process cartridge, and image formation device - Google Patents

Abstract

An electrographic photoreceptor (1) is provided with an electroconductive base (2) and a photosensitive layer (3). The photosensitive layer (3) is a single-layer photosensitive layer. The photosensitive layer (3) includes a charge-generating agent, a hole transport agent, an electron transport agent, a binder resin, and an acid anhydride. The acid anhydride is represented by formula (1), formula (2), or formula (3). In formulae (1) and (2), R^a, R^b, R^c, and R^d each represent, independently: a C1-6 alkyl group that optionally having a hydrogen atom, a halogen atom, and a first substituent group; a C1-6 alkoxy group that optionally has a second substituent group; or a C6-14 aryl group that optionally has a third substituent group. In formula (3), X represents a methylene group or an oxygen atom.

Description

Electrophotographic photosensitive member, process cartridge, and image forming apparatus

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

The electrophotographic photoreceptor is used as an image carrier in an electrophotographic image forming apparatus (for example, a printer or a multifunction machine). In general, an electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer contains, for example, a charge generator, a charge transport agent (more specifically, a hole transport agent or an electron transport agent), and a resin (binder resin) that binds these. For example, an electrophotographic photoreceptor contains a charge generating agent and a charge transport agent in the same layer (photosensitive layer), and has both functions of charge generation and charge transport in the same layer. Such an electrophotographic photoreceptor is referred to as a single layer type electrophotographic photoreceptor.

Patent Document 1 describes an organic photoelectric conversion film. The organic photoelectric conversion film is used for, for example, an optical sensor or a solar cell. The organic photoelectric conversion film includes a p-type material layer and an n-type material layer. The n-type material layer is formed from 1,4,5,8-naphthalenetetracarboxylic dianhydride.

JP 2009-290190 A

However, the technique described in Patent Document 1 is insufficient to improve the transferability of the toner image by the electrophotographic photosensitive member.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photoreceptor excellent in toner image transferability. Another object of the present invention is to provide a process cartridge and an image forming apparatus that suppress image defects.

The electrophotographic photoreceptor of the present invention comprises a conductive substrate and a photosensitive layer. The photosensitive layer is a single-layer type photosensitive layer. The photosensitive layer includes a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and an acid anhydride. The acid anhydride is represented by general formula (1), general formula (2), or general formula (3).

In the general formula (1) and the general formula (2), R ^a , R ^b , R ^c and R ^d are each independently a hydrogen atom, a halogen atom, or a carbon atom which may have a first substituent. An alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms which may have a second substituent, or an aryl group having 6 to 14 carbon atoms which may have a third substituent Represents. The first substituent is selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom. The second substituent is selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom. The third substituent is selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen atom. In the general formula (3), X represents a methylene group or an oxygen atom.

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

The image forming apparatus of the present invention includes an image carrier, a charging unit, an exposure unit, a developing unit, and a transfer unit. The image carrier is the above-described electrophotographic photosensitive member. The charging unit charges the surface of the image carrier. The charging polarity of the charging unit is positive. 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 transfer body.

The electrophotographic photosensitive member of the present invention is excellent in toner image transferability. In addition, the process cartridge and the image forming apparatus of the present invention can suppress image defects.

It is a schematic sectional drawing which shows the structure of the electrophotographic photoreceptor which concerns on 1st embodiment. It is a schematic sectional drawing which shows the structure of the electrophotographic photoreceptor which concerns on 1st embodiment. It is a schematic sectional drawing which shows the structure of the electrophotographic photoreceptor which concerns on 1st embodiment. It is the schematic which shows an example of the image forming apparatus which concerns on 2nd embodiment. It is a schematic diagram which shows the image in which the image defect generate | occur | produced. It is a schematic diagram which shows the image for evaluation.

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

Hereinafter, a compound and its derivatives may be generically named by adding “system” after the compound name. In addition, when “polymer” is added after the compound name to indicate the polymer name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

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 An alkoxy group having 1 to 6 atoms and an aryl group having 6 to 14 carbon atoms have the following meanings unless otherwise specified.

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

An alkyl group having 1 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, A neopentyl group or a hexyl group is mentioned.

An 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 a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, or A neopentyl group is mentioned.

An 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 a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group.

An 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, and an isopropyl group.

An 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, sec-butoxy group, tert-butoxy group, pentyloxy group, and hexyl. An oxy group is mentioned.

An aryl group having 6 to 14 carbon atoms is unsubstituted. Examples of the aryl group having 6 to 14 carbon atoms include an unsubstituted aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms and an unsubstituted aromatic condensed bicyclic carbon group having 6 to 14 carbon atoms. 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.

<First embodiment: electrophotographic photoreceptor>
The electrophotographic photoreceptor according to the first embodiment (hereinafter sometimes referred to as “photoreceptor”) has excellent toner image transferability. The reason is presumed as follows.

First, for the sake of convenience, the deterioration of transferability will be described. An electrophotographic image forming apparatus includes, for example, an image carrier (photosensitive member), a charging unit, an exposure unit, a developing unit, and a transfer unit. The transfer unit transfers the toner image from the photosensitive member to the transfer member. In the transfer process executed by the transfer unit, if the surface potential of the exposure area of the photosensitive member decreases and becomes less than 0 V, the transferability of the toner image from the photosensitive member to the transfer member may decrease. Such a drop in toner image transferability is likely to occur particularly in a high temperature and high humidity environment.

In the photoreceptor according to the first embodiment, the photosensitive layer includes an acid anhydride represented by the general formula (1), the general formula (2), or the general formula (3) (hereinafter, the acid anhydrides (1) to ( 3)). Acid anhydrides (1) to (3) are anhydrides of phthalic acid derivatives or 1,8-naphthalenedicarboxylic acid derivatives, and have a relatively small molecular weight and an asymmetric structure. It is easy to dissolve in the photosensitive layer and to disperse in the photosensitive layer. In the photoreceptor according to the first embodiment, the photosensitive layer tends to have an appropriate electrical resistance. As a result, the photoreceptor according to the first embodiment is likely to stably hold the surface potential and the electrostatic latent image. Therefore, it is considered that the photoconductor according to the first embodiment is excellent in toner image transferability.

The transferability of the toner image can be evaluated from the image. Further, the transferability of the toner image can be evaluated by the surface potential of the photoconductor in the exposed area after transfer. These evaluation methods will be described in detail in Examples. Here, the surface potential of the photoreceptor after transfer will be described. In the image forming apparatus according to the second embodiment, which will be described later, the surface potential of the photosensitive member is charged by the charging unit after the transfer unit transfers the toner image from the surface of the photosensitive member to the transfer member. Measured before. The next round means the round of the next image forming process of the photoconductor using the circumference of the photoconductor in the image forming process as a reference circumference. When the surface potential of the photosensitive member is a positive value and its absolute value is small, it indicates that the toner image is excellent in transferability. The surface potential of the photoreceptor is preferably −50 V or more, more preferably 0 V or more, more preferably 0 V or more and +90 V or less, and further preferably 0 V or more and +70 V or less. When the surface potential of the photoconductor is 0 V or more, the electrostatic attraction is less likely to act between the positively charged toner and the exposed area on the surface of the photoconductor, so that the toner image is easily transferred from the photoconductor to the transfer body.

The photoreceptor will be described with reference to FIGS. 1A to 1C. 1A to 1C are schematic cross-sectional views showing the structure of the photoreceptor 1. The photoreceptor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a single layer type photosensitive layer. The photosensitive layer 3 is provided directly or indirectly on the conductive substrate 2. For example, as shown in FIG. 1A, the photosensitive layer 3 may be provided directly on the conductive substrate 2. For example, an intermediate layer 4 may be provided between the conductive substrate 2 and the photosensitive layer 3 as shown in FIG. 1B. Further, as shown in FIGS. 1A and 1B, the photosensitive layer 3 may be exposed as the outermost layer. As shown in FIG. 1C, a protective layer 5 may be provided on the photosensitive layer 3. Hereinafter, the conductive substrate, the photosensitive layer, and the intermediate layer will be described. In addition, a method for manufacturing the photoreceptor 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 photoreceptor. As the conductive substrate, a conductive substrate formed of a material having at least a surface portion having conductivity (hereinafter sometimes referred to as a conductive material) can be used. An example of the conductive substrate is a conductive substrate made of a conductive material. Another example of a conductive substrate is a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, and indium. These materials having conductivity may be used alone or in combination of two or more. Examples of the combination of two or more include alloys (more specifically, aluminum alloy, stainless steel, brass, etc.). Among these materials having conductivity, aluminum or an aluminum alloy is preferable because charge transfer from the photosensitive layer to the conductive substrate is good.

The shape of the conductive substrate can be appropriately selected according to the structure of the image forming apparatus to be used. Examples of the shape of the conductive substrate include a sheet shape or a drum shape. Further, the thickness of the conductive substrate can be appropriately selected according to the shape of the conductive substrate.

[2. Photosensitive layer]
The photosensitive layer contains a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and any one of acid anhydrides (1) to (3). The photosensitive layer may contain various additives as required. Hereinafter, an acid anhydride, a charge generator, an electron transport agent, a hole transport agent, a binder resin, and an additive will be described.

(2-1. Acid anhydride)
The acid anhydrides (1) to (3) are represented by general formula (1), general formula (2) or general formula (3), respectively.

In General Formula (1) and General Formula (2), R ^a , R ^b , R ^c, and R ^d each independently represent a hydrogen atom, a halogen atom, or a carbon atom that may have a first substituent. Represents an alkyl group having 6 or less carbon atoms, an alkoxy group having 1 to 6 carbon atoms which may have a second substituent, or an aryl group having 6 to 14 carbon atoms which may have a third substituent. . The first substituent is selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom. The second substituent is selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom. The third substituent is selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen atom. In general formula (3), X represents a methylene group or an oxygen atom.

In general formulas (1) to (2), the halogen atom represented by R ^a to R ^d is preferably a chlorine atom.

In general formulas (1) to (2), the alkyl group having 1 to 6 carbon atoms represented by R ^a to R ^d may have a substituent. The substituent of the alkyl group having 1 to 6 carbon atoms represented by R ^a to R ^d is a substituent selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom.

In general formulas (1) to (2), the alkoxy group having 1 to 6 carbon atoms represented by R ^a to R ^d may have a substituent. The substituent of the alkyl group having 1 to 6 carbon atoms represented by R ^a to R ^d is a substituent selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom.

In general formulas (1) to (2), the aryl group having 6 to 14 carbon atoms represented by R ^a to R ^d may have a substituent. The substituent of the aryl group having 6 to 14 carbon atoms represented by R ^a to R ^d is selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen atom. Is the selected substituent.

In general formula (1), R ^a and R ^b represent a hydrogen atom. In general formula (2), R ^c and R ^d preferably represent a hydrogen atom or a halogen atom, and a hydrogen atom or a chlorine atom represents More preferred.

Specific examples of the acid anhydride include chemical formula (ADD-1), chemical formula (ADD-2), chemical formula (ADD-3), chemical formula (ADD-4), chemical formula (ADD-5), or chemical formula (ADD-6). (Hereinafter, may be referred to as acid anhydrides (ADD-1) to (ADD-6), respectively).

Of the acid anhydrides (ADD-1) to (ADD-6), acid anhydrides (ADD-1) or (ADD-6) are preferred. Among acid anhydrides (ADD-1) to (ADD-6), acid anhydrides (ADD-1), (ADD-4) or (ADD-) are used from the viewpoint of further improving the transferability of the toner image by the photoreceptor. 5) is preferred.

The content of the acid anhydrides (1) to (3) is preferably 0.01 parts by mass or more and 10 parts by mass or less, and 0.02 parts by mass or more and 7.00 parts by mass with respect to 100 parts by mass of the binder resin. The amount is more preferably 0.02 parts by mass or more and 4.00 parts by mass or less, and particularly preferably 0.02 parts by mass or more and 0.07 parts by mass or less. When the content of the acid anhydride is 0.02 parts by mass or more and 7.00 parts by mass or less with respect to 100 parts by mass of the binder resin, the photoreceptor has excellent toner image transferability and excellent sensitivity characteristics. When the content of the acid anhydride is 0.02 parts by mass or more and 4.00 parts by mass or less with respect to 100 parts by mass of the binder resin, the toner image is further improved in toner image transferability.

(2-2. Charge generator)
Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, and cyanine pigments. Powders of inorganic photoconductive materials (more specifically, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, etc.), pyrylium salts, ansanthrone pigments, triphenylmethane pigments, selenium pigments, Toluidine pigments, pyrazoline pigments or quinacridone pigments may be mentioned.

Examples of the phthalocyanine pigment include metal-free phthalocyanine or metal phthalocyanine represented by the chemical formula (CGM-1). Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (CGM-2) or phthalocyanine coordinated with a metal other than titanium oxide (more specifically, V-type hydroxygallium phthalocyanine). The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape of the phthalocyanine pigment (for example, α type, β type, or Y type) is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

Examples of the crystal of metal-free phthalocyanine include a metal-free phthalocyanine X-type crystal (hereinafter sometimes referred to as X-type metal-free phthalocyanine). Examples of the titanyl phthalocyanine crystal include α-type crystal, β-type crystal, and Y-type crystal of titanyl phthalocyanine. When the photosensitive layer contains any one of acid anhydrides (1) to (3), among these charge generators, phthalocyanine pigments are preferable, metal-free phthalocyanines are more preferable, and X-type metal-free phthalocyanines are still more preferable.

A charge generator having an absorption wavelength in a desired region may be used alone, or two or more charge generators may be used in combination. Further, 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. Therefore, for example, phthalocyanine pigments are preferable, and metal-free phthalocyanine or titanyl phthalocyanine is more preferable. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

For a photoreceptor applied to an image forming apparatus using a short wavelength laser light source, an ansanthrone pigment or a perylene pigment is preferably used as a charge generating agent. In addition, as a short wavelength laser, the laser which has a wavelength about 350 nm or more and 550 nm or less is mentioned, for example.

The content of the charge generating agent is preferably from 0.1 to 50 parts by mass, and more preferably from 0.5 to 30 parts by mass with respect to 100 parts by mass of the binder resin.

(2-3. Electron transport agent)
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 or dibromomaleic anhydride. Examples of quinone compounds 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 transport agents, compounds represented by general formula (ETM1), general formula (ETM2), general formula (ETM3), general formula (ETM4), or general formula (ETM5) (hereinafter referred to as electron transport agents (each ETM1) to (ETM5) are sometimes preferred.

In the general formulas (ETM1) to (ETM5), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently Represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms. The alkyl group having 1 to 6 carbon atoms may have a halogen atom. The aryl group having 6 to 14 carbon atoms may have a halogen atom or one or more alkyl groups having 1 to 6 carbon atoms.

In general formula (ETM1), the alkyl group having 1 to 6 carbon atoms represented by R ¹ and R ² is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a 2-methyl-2-butyl group. In general formula (ETM1), it is preferable that R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Examples of the electron transfer agent (ETM1) include a compound represented by the chemical formula (ETM1-1) (hereinafter, sometimes referred to as an electron transfer agent (ETM1-1)).

In general formula (ETM2), the alkyl group having 1 to 6 carbon atoms represented by R ³ , R ⁴ , R ⁵ and R ⁶ is preferably an alkyl group having 1 to 4 carbon atoms, such as a methyl group or tert- A butyl group is more preferred. In general formula (ETM2), R ³ , R ⁴ , R ⁵ and R ⁶ preferably represent an alkyl group having 1 to 6 carbon atoms. Examples of the electron transfer agent (ETM2) include a compound represented by the chemical formula (ETM2-1) (hereinafter sometimes referred to as an electron transfer agent (ETM2-1)).

In general formula (ETM3), the alkyl group having 1 to 6 carbon atoms represented by R ⁷ , R ⁸ and R ⁹ is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a tert-butyl group. The halogen atom represented by R ⁷ , R ⁸ and R ⁹ is preferably a chlorine atom. In general formula (ETM3), the aryl group having 6 to 14 carbon atoms represented by R ⁷ , R ⁸ and R ⁹ is preferably an aryl group having 6 to 14 carbon atoms having a halogen atom, and having a chlorine atom. A phenyl group is more preferred, and a p-chlorophenyl group is still more preferred. In General Formula (ETM3), R ⁷ , R ^8, and R ⁹ each independently represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms having a halogen atom. preferable. Examples of the electron transfer agent (ETM3) include a compound represented by the chemical formula (ETM3-1) (hereinafter sometimes referred to as an electron transfer agent (ETM3-1)).

In General Formula (ETM4), an aryl group having 6 to 14 carbon atoms that may have one or more alkyl groups having 1 to 6 carbon atoms represented by R ¹⁰ and R ¹¹ is a plurality of carbon atoms. An aryl group having 6 to 14 carbon atoms having an alkyl group having 1 to 6 carbon atoms is preferred, more preferably a phenyl group having a plurality of alkyl groups having 1 to 3 carbon atoms, more preferably 2-ethyl- More preferred is a 6-methylphenyl group. In General Formula (ETM4), R ¹⁰ and R ¹¹ preferably represent an aryl group having 6 to 14 carbon atoms having a plurality of alkyl groups having 1 to 6 carbon atoms. Examples of the electron transfer agent (ETM4) include a compound represented by the chemical formula (ETM4-1) (hereinafter, sometimes referred to as an electron transfer agent (ETM4-1)).

In general formula (ETM5), the alkyl group having 1 to 6 carbon atoms which may have a halogen atom represented by R ¹² is preferably an alkyl group having 1 to 6 carbon atoms having a halogen atom. And more preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a 4-chloro-n-butyl group. In General Formula (ETM5), R ¹² preferably represents an alkyl group having 1 to 6 carbon atoms having a halogen atom. Examples of the electron transfer agent (ETM5) include a compound represented by the chemical formula (ETM5-1) (hereinafter sometimes referred to as an electron transfer agent (ETM5-1)).

The content of the electron transport agent is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the binder resin.

(2-4. Hole transport agent)
Examples of the hole transporting agent include nitrogen-containing cyclic compounds and condensed polycyclic compounds. Examples of nitrogen-containing cyclic compounds and condensed polycyclic compounds include triphenylamine derivatives; diamine derivatives (more specifically, N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ', N'-tetraphenylphenylenediamine derivative, N, N, N', N'-tetraphenylnaphthylenediamine derivative, di (aminophenylethenyl) benzene derivative or N, N, N ', N'-tetraphenyl Phenanthrylenediamine derivatives, etc.); oxadiazole compounds (more specifically, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole, etc.); styryl compounds (more Specifically, 9- (4-diethylaminostyryl) anthracene etc.); carbazole compounds (more specifically, polyvinyl carbazole etc.); organic poly Lan compounds; pyrazoline compounds (more specifically, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, etc.); hydrazone compounds; indole compounds; oxazole compounds; isoxazole compounds; thiazole compounds A thiadiazole compound; an imidazole compound; a pyrazole compound; or a triazole compound. These hole transport agents may be used alone or in combination of two or more.

Of these hole transport agents, compounds represented by the general formula (HTM) are preferred.

In the general formula (HTM), R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ and R ²⁶ are each independently an alkyl group having 1 to 6 carbon atoms or an alkoxy having 1 to 6 carbon atoms. Represents a group. p, q, v and w each independently represent an integer of 0 or more and 5 or less. m and n each independently represents an integer of 0 or more and 4 or less.

In the general formula (HTM), R ²¹ and R ²⁵ each independently represents an alkyl group having 1 to 6 carbon atoms, p and v represent 1, q, w, m and n represent 0. It is preferable to represent.

Specific examples of the hole transport agent include a compound represented by the chemical formula (HTM-1) (hereinafter sometimes referred to as a hole transport agent (HTM-1)).

The content of the hole transporting agent is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin.

(2-5. Binder resin)
Examples of the binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include polyester resin, polycarbonate resin, styrene resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic copolymer. Polymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polyarylate resin , Polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin or polyether resin. Examples of the thermosetting resin include a silicone resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, and other crosslinkable thermosetting resins. Examples of the photocurable resin include an epoxy acrylate resin or a urethane-acrylic acid copolymer. These binder resins may be used individually by 1 type, and may be used in combination of 2 or more type.

Of these binder resins, polycarbonate resins are preferred. When the binder resin is a polycarbonate resin, it is easy to obtain a photosensitive layer having an excellent balance of processability, mechanical strength, optical characteristics, and wear resistance. Among the polycarbonate resins, bisphenol Z-type polycarbonate resin, bisphenol CZ-type polycarbonate resin, or bisphenol C-type polycarbonate resin is preferable, and the polycarbonate represented by the chemical formula (Z) is preferable because the transferability of the toner image by the photoreceptor is easy to improve. A resin is more preferable. In chemical formula (Z), the subscript of the repeating unit indicates the mole fraction of the repeating unit to which the subscript is attached relative to the total number of moles of the repeating unit in the resin.

The viscosity average molecular weight of the binder resin is preferably 40,000 or more, and more preferably 40,000 or more and 52,500 or less. When the viscosity average molecular weight of the binder resin is 40,000 or more, it is easy to improve the wear resistance of the photoreceptor. Further, when the viscosity average molecular weight of the binder resin is 52,500 or less, the binder resin is easily dissolved in the solvent at the time of forming the photosensitive layer, and the viscosity of the coating solution for the photosensitive layer does not become too high. As a result, it becomes easy to form a photosensitive layer.

(2-6. Additives)
Additives include, for example, deterioration inhibitors (more specifically, antioxidants, radical scavengers, quenchers or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersions. Stabilizers, waxes, acceptors, donors, surfactants, plasticizers, sensitizers or leveling agents can be mentioned. Examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone, or a derivative thereof, an organic sulfur compound, or an organic phosphorus compound.

[3. Middle layer]
An intermediate | middle layer contains an inorganic particle and resin (resin for intermediate | middle layers), for example. It is considered that the presence of the intermediate layer 4 maintains an insulating state that can suppress the occurrence of current leakage. In addition, it is considered that the presence of the intermediate layer 4 smoothes the flow of current generated when the photosensitive member 1 is exposed and suppresses an increase in electrical resistance.

Examples of the inorganic particles include metal (more specifically, aluminum, iron, copper, etc.) particles, metal oxide (more specifically, titanium oxide, alumina, zirconium oxide, tin oxide, zinc oxide, etc.). Or particles of a non-metal oxide (more specifically, silica or the like). These inorganic particles may be used individually by 1 type, and may use 2 or more types together.

The intermediate layer resin is not particularly limited as long as it is a resin that can be used as a resin for forming the intermediate layer.

The intermediate layer may contain various additives as long as the electrophotographic characteristics of the photoreceptor are not adversely affected. The additive is the same as the additive for the photosensitive layer.

[4. Photoconductor manufacturing method]
With reference to FIG. 1, the manufacturing method of the photoreceptor 1 is demonstrated. The method for manufacturing the photoreceptor 1 includes a photosensitive layer forming step. Hereinafter, the photosensitive layer forming step will be described.

(4-1. Photosensitive layer forming step)
In the photosensitive layer forming step, a photosensitive layer forming coating solution (hereinafter sometimes referred to as a coating solution) is applied onto the conductive substrate 2, and at least part of the solvent of the applied coating solution is removed. The photosensitive layer 3 is formed. The photosensitive layer forming step includes, for example, a coating solution preparing step, a coating step, and a drying step. Hereinafter, a coating liquid preparation process, a coating process, and a drying process will be described.

(4-1-1. Coating solution preparation process)
In the coating liquid preparation step, a coating liquid is prepared. The coating liquid contains at least one of acid anhydrides (1) to (3), a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and a solvent. An additive may be included in the coating liquid as necessary. As the coating solution, for example, any one of acid anhydrides (1) to (3), a charge generator, a hole transport agent, an electron transport agent, a binder resin, and an additive are dissolved in a solvent. Alternatively, it can be prepared by dispersing.

The solvent contained in the coating solution is not particularly limited as long as each component contained in the coating solution can be dissolved or dispersed. Examples of the solvent include alcohol (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbon (more specifically, n-hexane, octane, cyclohexane, etc.), aromatic hydrocarbon ( More specifically, benzene, toluene, xylene and the like), halogenated hydrocarbon (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, etc.), ether (more specifically, dimethyl ether, diethyl ether, Tetrahydrofuran, ethylene glycol dimethyl ether or diethylene glycol dimethyl ether), ketone (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), ester (more specifically, ethyl acetate, methyl acetate, etc.), dimethylform Aldehydes, N, include N- dimethylformamide (DMF) or dimethyl sulfoxide. These solvents may be used alone or in combination of two or more. Of these solvents, non-halogen solvents are preferred.

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

The coating liquid may contain, for example, a surfactant or a leveling agent in order to improve the dispersibility of each component or the surface smoothness of each layer formed.

(4-1-2. Application process)
In the coating process, a coating solution is applied onto the conductive substrate 2. The method for applying the coating solution is not particularly limited as long as it is a method that can uniformly apply the coating solution on the conductive substrate 2. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

Since it is easy to adjust the thickness of the photosensitive layer 3 to a desired value, a dip coating method is preferable as a method of applying the coating solution. When the coating process is performed by a dip coating method, in the coating process, the conductive substrate 2 is immersed in a coating solution. Subsequently, the immersed conductive substrate 2 is pulled up from the coating solution. Thereby, a coating liquid is apply | coated to the electroconductive base | substrate 2, and a coating film is formed.

(4-1-3. Drying step)
In the drying step, at least a part of the solvent contained in the coating film is removed. The method for removing the solvent contained in the coating film is not particularly limited as long as it is a method capable of evaporating the solvent in the coating film. Examples of the removal method include heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of heat treatment (hot air drying) using a high-temperature dryer or a vacuum 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.

Note that the method for manufacturing the photoreceptor 1 may further include one or both of a step of forming the intermediate layer 4 and a step of forming the protective layer 5 as necessary. In the step of forming the intermediate layer 4 and the step of forming the protective layer 5, a known method is appropriately selected.

<Second Embodiment: Image Forming Apparatus>
The image forming apparatus according to the second embodiment will be described below with reference to FIG. FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus according to the second embodiment. The image forming apparatus 100 according to the second embodiment includes an image forming unit 40 (for example, an image forming unit 40a). The image forming unit 40 includes an image carrier 30, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. The image carrier 30 is a photoconductor according to the first embodiment. The charging unit 42 charges the surface of the image carrier 30. The charging polarity of the charging unit 42 is positive. 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 transfer body. The outline of the image forming apparatus 100 according to the second embodiment has been described above.

The image forming apparatus 100 according to the second embodiment can suppress image defects. Examples of such image defects include image defects caused by at least one of a decrease in toner image transferability and a decrease in sensitivity characteristics. As an example of the image defect, an image defect caused by a decrease in toner image transferability will be described. *

As described above, when the transferability of the toner image is deteriorated, the toner that could not be transferred to the transfer body remains on the image carrier 30. Residual toner may be transferred to an image formed in the next round with the circumference of the image carrier in the image forming step as a reference circumference. An image defect in which an image reflecting the image of the reference circumference of the image carrier 30 is formed is an image defect caused by a decrease in transferability.

Referring to FIG. 2 and FIG. 3, an image in which an image defect has occurred will be further described. FIG. 3 is a schematic diagram showing an image in which an image defect has occurred. The image 120 includes a region 102, a region 104, and a region 106. The region 102, the region 104, and the region 106 are regions corresponding to one turn of the image carrier 30. The image 108 in the region 102 includes a rectangular solid image (image density 100%). Each of the area 104 and the area 106 includes an entire blank image (image density 0%) on the design image. The image 108 in the region 102 is first formed along the direction a (conveying direction a) in which the recording medium is conveyed, then the blank image in the region 104 is formed, and finally, the blank image in the region 106 is formed. The blank paper image in the region 104 is an image corresponding to one round of the next rotation of the image carrier 30, and 1 of the image carrier 30 in the second round with reference to the first round of the image carrier 30 forming the image 108. It is an image corresponding to the circumference. The blank paper image in the area 106 is an image corresponding to one round of the next rotation of the image carrier 30, and 1 of the image carrier 30 on the third round with reference to the first round of the image carrier 30 forming the image 108. It is an image corresponding to the circumference.

The blank image in the area 110 of the area 104 is an image corresponding to the image 108 in the second turn of the image carrier 30. A blank image in the area 112 of the area 106 is an image corresponding to the image 108 in the third round of the photoconductor. In this case, an image reflecting the image 108 is formed in the area 110 and / or the area 112 as an image defect. As described above, the image defect due to the decrease in the transferability of the toner image by the image carrier 30 occurs in a cycle with the circumference of the image carrier 30 as a unit. Images reflecting the image 108 are easily formed on both ends of the recording medium. This is considered to be because the pressing force to both ends of the recording medium is relatively strong. Here, the both end portions of the recording medium are, for example, both end portions in the vertical direction b (region 110L and region 110R) in the region 110 of the recording medium, and both end portions (region 112L and region 112R in the vertical direction b in the region 112. ).

The reason why the image forming apparatus 100 according to the second embodiment suppresses image defects is estimated as follows. The image forming apparatus 100 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 is excellent in toner image transferability. The photoreceptor according to the first embodiment also has excellent sensitivity characteristics. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image defects.

Hereinafter, returning to FIG. 2, each part of the image forming apparatus 100 will be described in detail. The image forming apparatus 100 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 100 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. When the image forming apparatus 100 is a color image forming apparatus, the image forming apparatus 100 employs, for example, a tandem method. Hereinafter, the tandem image forming apparatus 100 will be described as an example.

The image forming apparatus 100 employs a direct transfer method. When the image forming apparatus 100 adopts the direct transfer method, the transfer body is the recording medium P. Usually, in an image forming apparatus that employs a direct transfer method, an image carrier is likely to be affected by a transfer bias, and thus a transfer memory is usually easily generated. However, the image forming apparatus 100 according to the second embodiment includes the photoconductor according to the first embodiment as the image carrier 30. Since the photoreceptor according to the first embodiment also has excellent sensitivity characteristics, it is possible to suppress the generation of a transfer memory. Therefore, if the image bearing member 30 includes the photoconductor according to the first embodiment, it is considered that the occurrence of image defects due to the transfer memory can be suppressed even when the image forming apparatus 100 adopts the direct transfer method. It is done. The image forming apparatus 100 can also employ an intermediate transfer method. When the image forming apparatus 100 adopts the intermediate transfer method, the transfer member is an intermediate transfer member (for example, an intermediate transfer belt or an intermediate transfer drum).

The image forming apparatus 100 can employ a contact development method. In the image forming apparatus 100 employing the contact development method, the developing unit 46 develops the electrostatic latent image as a toner image while being in contact with the surface of the image carrier 30. The image forming apparatus 100 according to the second embodiment can suppress the occurrence of image defects due to a decrease in transferability of the toner image by the image carrier 30 even when the contact development method is employed.

The image forming apparatus 100 can include a charging roller as the charging unit 42. When charging the surface of the image carrier 30, the charging roller comes into contact with the surface of the image carrier 30. That is, the image forming apparatus usually tends to generate a transfer memory in an image forming apparatus including a charging roller. However, the image forming apparatus 100 includes the photoconductor according to the first embodiment as the image carrier 30. Since the photoreceptor according to the first embodiment also has excellent sensitivity characteristics, it is possible to suppress the generation of a transfer memory. Therefore, even if the image forming apparatus 100 according to the second embodiment includes a charging roller as the charging unit 42, it is possible to suppress the occurrence of image defects due to the generation of the transfer memory.

The image forming apparatus 100 can employ a so-called blade cleaner-less method. In the image forming apparatus 100 employing the blade cleaner-less method, the developing unit 46 cleans the surface of the image carrier 30. Specifically, the developing unit 46 can remove residual components. In such an image forming apparatus 100, residual components on the surface of the image carrier 30 are not scraped off by a cleaning unit (for example, a cleaning blade). For this reason, in the image forming apparatus 100 that employs the blade cleaner-less method, a residual component usually tends to remain on the surface of the image carrier 30. However, the photoreceptor of the first embodiment is excellent in toner transferability. Therefore, even if the image forming apparatus 100 including such a photoconductor employs a blade cleaner-less method, residual components, particularly minute components (for example, paper dust) of the recording medium P are unlikely to remain on the surface of the photoconductor. As a result, the image forming apparatus 100 can suppress the occurrence of image defects.

The image forming apparatus 100 includes image forming units 40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing unit 52. Hereinafter, when it is not necessary to distinguish, each of the image forming units 40a, 40b, 40c, and 40d is referred to as an image forming unit 40. When the image forming apparatus 100 is a monochrome image forming apparatus, the image forming apparatus 100 includes an image forming unit 40a, and the image forming units 40b to 40d are omitted.

As already described with reference to FIG. 2, the image forming unit 40 includes the image carrier 30, the charging unit 42, the exposure unit 44, the developing unit 46, and the transfer unit 48. The image forming unit 40 includes an image carrier 30 at the center position. The image carrier 30 is provided to be rotatable 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 respect to the charging unit 42. . The image forming unit 40 may further include a cleaning unit or a charge removal unit (not shown).

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

The charging unit 42 charges the surface of the image carrier 30. The charging unit 42 is a charging roller. The charging roller charges the surface of the image carrier 30 while being in contact with the surface of the image carrier 30. The charging polarity of the charging unit is positive. The charging unit 42 is a non-contact type or contact type charging unit. Examples of the non-contact charging unit 42 include a corotron charger and a scorotron charger. Examples of the contact-type charging unit 42 include a charging roller or a charging brush.

The voltage applied by the charging unit 42 is not particularly limited, and examples thereof include a DC voltage, an AC voltage, or a superimposed voltage obtained by superimposing a DC current on an AC current. The charging unit 42 that applies only the DC voltage has the following advantages compared to the case where the charging unit applies an AC voltage or the charging unit applies a superimposed voltage obtained by superimposing the AC voltage on the DC voltage. When the charging unit 42 applies only a DC voltage, the voltage value applied to the image carrier 30 is constant, so that the surface of the image carrier 30 is easily charged uniformly to a constant potential. Further, when the charging unit 42 applies only a DC voltage, the wear amount of the photosensitive layer tends to decrease. As a result, a suitable image can be formed.

When the voltage applied by the charging unit 42 is a DC voltage, a transfer memory tends to be generated more easily than an AC voltage. However, the image forming apparatus 100 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 also suppress the generation of a transfer memory. Therefore, even if the image forming apparatus 100 according to the second embodiment includes the charging unit 42 that contacts the image carrier 30 and applies a DC voltage, it is possible to suppress the occurrence of image defects due to the transfer memory. .

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 image data input to the image forming apparatus 100.

The developing unit 46 supplies toner to the surface of the image carrier 30 and develops the electrostatic latent image as a toner image. The developing unit 46 can develop the electrostatic latent image as a toner image while in contact with the image carrier 30. Further, the developing unit 46 can clean the surface of the image carrier 30.

In order for the developing unit 46 to efficiently clean the surface of the image carrier 30, it is preferable to satisfy the following conditions (a) and (b).
Condition (a): A contact developing method is employed, and a peripheral speed (rotational speed) difference is provided between the image carrier 30 and the developing unit 46.
Condition (b): The surface potential of the image carrier 30 and the potential of the developing bias satisfy the following formulas (b-1) and (b-2).
0 (V) <potential of developing bias (V) <surface potential of unexposed area of image carrier 30 (V) (b-1)
Developing bias potential (V)> Surface potential (V) of exposed area of image carrier 30> 0 (V) (b-2)

When the contact development method shown in the condition (a) is employed and a peripheral speed difference is provided between the image carrier 30 and the development unit 46, the surface of the image carrier 30 comes into contact with the development unit 46, and the image Adhering components on the surface of the carrier 30 are removed by friction with the developing unit 46. The peripheral speed of the developing unit 46 is preferably faster than the peripheral speed of the image carrier 30.

In condition (b), it is assumed that the development method is a reversal development method. In order to improve the electrical characteristics of the image carrier 30 having a positive polarity, the charging polarity of the toner, the surface potential of the unexposed area of the image carrier 30, and the surface potential of the exposed area of the image carrier 30 It is preferable that both the potential of the developing bias and the potential of the developing bias are positive. The surface potential of the unexposed area and the surface potential of the exposed area of the image carrier 30 are the image carrier 30 that forms an image after the transfer unit 48 transfers the toner image from the image carrier 30 to the recording medium P. Is used before the charging unit 42 charges the surface of the image carrier 30 on the next round of the reference circumference.

When the mathematical expression (b-1) of the condition (b) is satisfied, it acts between the toner remaining on the image carrier 30 (hereinafter sometimes referred to as residual toner) and the unexposed area of the image carrier 30. The electrostatic repulsive force is larger than the electrostatic repulsive force acting between the residual toner and the developing unit 46. Therefore, the residual toner in the unexposed area of the image carrier 30 moves from the surface of the image carrier 30 to the developing unit 46 and is collected.

When the mathematical expression (b-2) of the condition (b) is satisfied, an electrostatic repulsive force that acts between the residual toner and the exposed area of the image carrier 30 acts between the residual toner and the developing unit 46. Smaller than electric repulsion. Therefore, the residual toner in the exposed area of the image carrier 30 is held on the surface of the image carrier 30. The toner held in the exposure area of the image carrier 30 is used for image formation as it is.

The transfer belt 50 conveys the recording medium P between the image carrier 30 and the transfer unit 48. The transfer belt 50 is an endless belt. The transfer belt 50 is provided to be rotatable in the arrow direction (clockwise).

The transfer unit 48 transfers the toner image developed by the developing unit 46 from the surface of the image carrier 30 to the recording medium P. When the toner image is transferred from the image carrier 30 to the recording medium P, the image carrier 30 is in contact with the recording medium P. An example of the transfer unit 48 is a transfer roller.

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

<Third embodiment: Process cartridge>
A process cartridge according to the third embodiment includes the photoconductor according to the first embodiment. Next, the process cartridge according to the third embodiment will be described with reference to FIG.

The process cartridge includes a unitized part. The unitized portion includes the image carrier 30. The unitized portion may include at least one selected from the group consisting of a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48 in addition to the image carrier 30. The process cartridge corresponds to each of the image forming units 40a to 40d, for example. The process cartridge may further include a static eliminator (not shown). The process cartridge is designed to be detachable from the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics and the like of the image carrier 30 are deteriorated, the process cartridge including the image carrier 30 can be easily and quickly replaced.

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

[1. Photoconductor Material]
As materials for forming the photosensitive layer of the photoreceptor, the following charge generator, hole transport agent, electron transport agent and binder resin were prepared. The acid anhydrides (ADD-1) to (ADD-6) described in the first embodiment were prepared. The charge generating agent (CGM-1) described in the first embodiment was prepared. The charge generation agent (CGM-1) was a metal-free phthalocyanine represented by the chemical formula (CGM-1). The crystal structure of the charge generator (CGM-1) was X-type. The hole transport agent (HTM-1) described in the first embodiment was prepared. The electron transport agents (ETM1-1) to (ETM5-1) described in the first embodiment were prepared. A polycarbonate resin (Z) was prepared as a binder resin. The polycarbonate resin (Z) was a polycarbonate resin represented by the chemical formula (Z) described in the first embodiment.

[2. Production of photoconductor]
Photoconductors (A-1) to (A-21) and photoconductors (B-1) to (B-5) were produced using the materials for forming the photosensitive layer of the prepared photoconductor.

(2-1. Production of Photosensitive Member (A-1))
A photosensitive layer forming step was performed. First, a coating solution was prepared. 1.00 parts by weight of an acid anhydride (ADD-1), 2 parts by weight of a charge generating agent (CGM-1), 60 parts by weight of a hole transporting agent (HTM-1), and an electron transporting agent (ETM1-1) 35 parts by mass, 100 parts by mass of a polycarbonate resin (Z) as a binder resin, and 800 parts by mass of tetrahydrofuran as a solvent were charged into a container. The contents of the container were mixed and dispersed for 50 hours using a ball mill to obtain a coating solution.

Next, using a dip coating method, a coating solution was applied on the conductive substrate to form a coating film on the conductive substrate. The conductive substrate was made of aluminum having a diameter of 160 mm, a length of 365 mm, and a thickness of 2 mm. Specifically, the conductive substrate was immersed in the coating solution. Next, the immersed conductive substrate was pulled up from the coating solution. Thereby, the coating solution was applied to the conductive substrate to form a coating film.

Next, the conductive substrate on which the coating film was formed was dried with hot air at 100 ° C. for 40 minutes. Thereby, the solvent (tetrahydrofuran) contained in the coating film was removed. As a result, a photosensitive layer was formed on the conductive substrate. As a result, a photoreceptor (A-1) was obtained.

(2-2. Production of photoconductors (A-2) to (A-21) and photoconductors (B-1) to (B-5))
The photoconductors (A-2) to (A-21) and the photoconductors (B-1) to (B-5) were manufactured in the same manner as in the production of the photoconductor (A-1) except that the following points were changed. ) Was manufactured. Instead of 1.00 parts by weight of acid anhydride (ADD-1) and electron transport agent (ETM-1), the types of acid anhydrides, acid anhydride contents and types of electron transport agents shown in Table 1 were used. Using. In this way, photoreceptors (A-2) to (A-21) and photoreceptors (B-1) to (B-5) were obtained, respectively.

Table 1 shows the configurations of the photoconductors (A-1) to (A-21) and the photoconductors (B-1) to (B-5). In Table 1, ETM1-1 to ETM5-1 in the column “Type of ETM” indicate the electron transfer agents (ETM1-1) to (ETM5-1), respectively. In the column “Types of acid anhydrides”, ADD-1 to ADD-6 indicate acid anhydrides (ADD-1) to (ADD-6), respectively. The column “content of acid anhydride” indicates the content (part by mass) of the acid anhydride with respect to 100 parts by mass of the binder resin.

[3. Evaluation methods]
(3-1. Evaluation of sensitivity characteristics of photoreceptor: measurement of potential after exposure of photoreceptor)
The sensitivity characteristics of the photoreceptor were evaluated by measuring the post-exposure potential of the photoreceptor. A surface potential meter (“MODEL244” manufactured by Monroe Electronics) was used to measure the post-exposure potential of the photoreceptor. A surface potential probe (“MODEL1017AE” manufactured by Monroe Electronics) was placed at the position of the developing unit. That is, the surface potential of the photoreceptor in the exposure area after the charging process and the exposure process was measured. The obtained surface potential was defined as a post-exposure potential. The post-exposure potential of the photoreceptor was measured under the conditions of a temperature of 23 ° C., a humidity of 50% RH, a charging potential of +600 V, an exposure wavelength of 780 nm, and an exposure dose of 1.2 μJ / cm ² . The sensitivity characteristics of the photoreceptor were evaluated based on the evaluation criteria from the obtained post-exposure potential. Table 1 shows the post-exposure potential of the photoreceptor.
(Evaluation criteria for sensitivity characteristics)
Evaluation A (good): The post-exposure potential of the photoreceptor is less than + 140V.
Evaluation B (normal): The post-exposure potential of the photoreceptor is +140 V or more and less than +160 V.
Evaluation C (bad): The post-exposure potential of the photoreceptor is +160 V or more.

(3-2. Evaluation of transferability of toner image by photoreceptor: measurement of surface potential of photoreceptor)
The transferability of the toner image by the photoconductor was evaluated by measuring the surface potential of the photoconductor. A surface potential meter (“MODEL244” manufactured by Monroe Electronics) was used. A surface potential probe (“MODEL1017AS” manufactured by Monroe Electronics) was placed at the position after transfer. That is, the surface potential (unit: V) of the photoconductor in the exposure area after the transfer process was measured. The surface potential of the photoreceptor was measured under the conditions of a temperature of 23 ° C., a humidity of 50% RH, a drum linear speed of 165 mm / second, a grid voltage of 600 V, and a flowing current of 300 μA. Table 1 shows the surface potential of the photoreceptor.

(3-3. Evaluation of transferability of toner image by photoconductor: image evaluation)
The photoconductor was mounted on an evaluation machine. A printer (“FS-1300D” manufactured by Kyocera Document Solutions Inc., dry electrophotographic printer using a semiconductor laser) was used as an evaluation machine. The evaluator was provided with a charging roller as a charging unit. A DC voltage was applied to the charging roller. The evaluation machine was provided with a direct transfer type transfer section (transfer roller). The evaluator was equipped with a contact developing type developing unit. For the transferability evaluation, “Kyocera Document Solutions Brand Paper VM-A4 (A4 size)” sold by Kyocera Document Solutions Inc. was used as the paper. In the transferability evaluation, “TK-131” manufactured by Kyocera Document Solutions Co., Ltd. was used as a toner. The measurement of the transferability evaluation was performed in a high temperature and high humidity (temperature: 32.5 ° C., humidity: 80% RH) environment.

An evaluation image was formed on paper using an evaluation machine equipped with a photoreceptor and toner. Details of the evaluation image will be described later with reference to FIG. The image forming condition was set to a linear velocity of 165 mm / sec. The current applied by the transfer roller to the photoconductor was set to -25 μA.

Next, the obtained image was visually confirmed, and the presence or absence of an image corresponding to the image 208 in the region 210 and the region 212 was confirmed. From the obtained visual observation results, the transferability of the toner image by the photoconductor was evaluated according to the following criteria. A (very good) and B (good) were accepted. Table 1 shows the evaluation results of the transferability of the toner image.

The image for evaluation will be described with reference to FIG. FIG. 4 is a schematic diagram showing an evaluation image. The evaluation image 200 includes a region 202, a region 204, and a region 206. The area 202 is an area corresponding to one turn of the image carrier 30. The image 208 in the region 202 includes a solid image (image density 100%). This solid image had a rectangular shape. Each of the region 204 and the region 206 is a region corresponding to one turn of the image carrier 30 and is composed of a blank paper image (image density 0%). First, the image 208 of the region 202 was formed along the transport direction a, and then blank images of the region 204 and the region 206 were formed. The blank image in the area 204 is an image formed on the second turn with reference to the circumference on which the image 208 is formed. An area 210 is an area corresponding to the image 208 in the area 204. A blank paper image in the area 206 is an image formed on the third circumference with the circumference on which the image 108 is formed as a reference. An area 212 is an area corresponding to the image 208 in the area 206.

(Evaluation criteria for transferability)
Evaluation A (very good): Images corresponding to the image 208 were not confirmed in the areas 210 and 212.
Evaluation B (good): Images corresponding to the image 208 were slightly confirmed at both ends of the area 210 in the vertical direction b. An image corresponding to the image 208 was not confirmed in the area 212.
Evaluation C (bad): Images corresponding to the image 208 were clearly confirmed at both ends of the area 210 in the vertical direction b. An image corresponding to the image 208 was not confirmed in the area 212.

As shown in Table 1, in the photoreceptors (A-1) to (A-21), the photosensitive layer includes a charge generator, a hole transport agent, an electron transport agent, a binder resin, an acid anhydride, and the like. including. The acid anhydride is any one of acid anhydrides (ADD-1) to (ADD-6). The acid anhydrides (ADD-1) to (ADD-6) are represented by general formula (1), general formula (2), or general formula (3). In the photoconductors (A-1) to (A-21), the evaluation results of the transferability of the toner image by the photoconductor are all evaluation A (good).

As shown in Table 1, in the photoreceptors (B-1) to (B-5), the photosensitive layers are all acid anhydrides represented by the general formula (1), the general formula (2), or the general formula (3). Does not include things. In the photoconductors (B-1) to (B-5), the evaluation results of the transferability of the toner image by the photoconductor are all evaluation C (bad).

From the above, it is clear that the photoconductors (A-1) to (A-21) are superior in toner image transferability to the photoconductors (B-1) to (B-5).

As shown in Table 1, in the photoreceptors (A-1) and (A-15) to (A-19), the content of acid anhydride is 0.02 parts by mass or more to 100 parts by mass of the binder resin. 0.000 part by mass or less. In the photoreceptors (A-1) and (A-15) to (A-19), the surface potential is +55 V or more and +79 V or less in the evaluation of the transferability of the toner image, and all the evaluation results of the sensitivity characteristics are evaluation A (good). ).

As shown in Table 1, in the photoreceptors (A-20) to (A-21), the content of the acid anhydride is 0.01 parts by mass and 10.0 parts by mass with respect to 100 parts by mass of the binder resin, respectively. It is. In the photoreceptor (A-20), the surface potential is −34V. In the photoreceptor (A-21), the evaluation result of the sensitivity characteristic is evaluation B (normal).

From the above, the photoconductors (A-1) and (A-15) to (A-19) have both toner image transferability and sensitivity characteristics as compared with the photoconductors (A-20) to (A-21). Is also clearly superior.

The photoreceptor according to the present invention can be suitably used in an electrophotographic image forming apparatus.

Claims (14)

1. An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer,
   The photosensitive layer is a single-layer type photosensitive layer,
   The photosensitive layer includes a charge generating agent, a hole transport agent, an electron transport agent, a binder resin, and an acid anhydride,
   The acid anhydride is an electrophotographic photosensitive member represented by the general formula (1), the general formula (2), or the general formula (3).
   

   

   

   

   In the general formula (1) and the general formula (2),
   R ^a , R ^b , R ^c and R ^d each independently have a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a first substituent, and a second substituent. Represents an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may have a third substituent,
   The first substituent is selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom,
   The second substituent is selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom,
   The third substituent is selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen atom,
   In the general formula (3),
   X represents a methylene group or an oxygen atom.
2. In the general formula (1), R ^a and R ^b represent a hydrogen atom,
   2. The electrophotographic photosensitive member according to claim 1, wherein in the general formula (2), R ^c and R ^d represent a hydrogen atom or a halogen atom.
3. The acid anhydride is represented by chemical formula (ADD-1), chemical formula (ADD-2), chemical formula (ADD-3), chemical formula (ADD-4), chemical formula (ADD-5), or chemical formula (ADD-6). The electrophotographic photosensitive member according to claim 1.
   

   

   

   

   

   

   
4. The electrophotographic photoreceptor according to claim 1, wherein the content of the acid anhydride is 0.02 parts by mass or more and 7.00 parts by mass or less with respect to 100 parts by mass of the binder resin.
5. The electrophotographic photosensitive member according to claim 1, wherein the electron transfer agent is represented by a general formula (ETM1), a general formula (ETM2), a general formula (ETM3), a general formula (ETM4), or a general formula (ETM5). .
   

   

   

   

   

   

   In the general formula (ETM1), the general formula (ETM2), the general formula (ETM3), the general formula (ETM4) and the general formula (ETM5),
   R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently a hydrogen atom, a halogen atom, or a carbon atom number. It represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms. The alkyl group having 1 to 6 carbon atoms may have a halogen atom. The aryl group having 6 to 14 carbon atoms may have a halogen atom or one or more alkyl groups having 1 to 6 carbon atoms.
6. In the general formula (ETM1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,
   In the general formula (ETM2), R ³ , R ⁴ , R ⁵ and R ⁶ represent an alkyl group having 1 to 6 carbon atoms,
   In the general formula (ETM3), R ⁷ , R ⁸ and R ⁹ each independently represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 14 carbon atoms having a halogen atom,
   In the general formula (ETM4), R ¹⁰ and R ¹¹ represent an aryl group having 6 to 14 carbon atoms having a plurality of alkyl groups having 1 to 6 carbon atoms,
   6. The electrophotographic photosensitive member according to claim 5, wherein in the general formula (ETM5), R ¹² represents an alkyl group having 1 to 6 carbon atoms having a halogen atom.
7. The electron transport agent is represented by a chemical formula (ETM1-1), a chemical formula (ETM2-1), a chemical formula (ETM3-1), a chemical formula (ETM4-1), or a chemical formula (ETM5-1). Electrophotographic photoreceptor.
   

   

   

   

   

   
8. The electrophotographic photosensitive member according to claim 1, wherein the hole transport agent is represented by a general formula (HTM).
   

   

   In the general formula (HTM), R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ and R ²⁶ are each independently an alkyl group having 1 to 6 carbon atoms or 1 to 6 carbon atoms. Represents an alkoxy group,
   p, q, v and w each independently represent an integer of 0 to 5,
   m and n each independently represents an integer of 0 or more and 4 or less.
9. A process cartridge comprising the electrophotographic photosensitive member according to claim 1.
10. An image carrier;
    A charging unit that charges the surface of the image carrier;
    An exposure unit that exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier;
    A developing unit for developing the electrostatic latent image as a toner image;
    A transfer unit that transfers the toner image from the image carrier to a transfer body,
    The charging polarity of the charging part is positive.
    The image forming apparatus according to claim 1, wherein the image carrier is the electrophotographic photosensitive member according to claim 1.
11. The image forming apparatus according to claim 10, wherein the developing unit develops the electrostatic latent image as the toner image while being in contact with the image carrier.
12. The image forming apparatus according to claim 10, wherein the developing unit cleans the surface of the image carrier.
13. The image forming apparatus according to claim 10, wherein the transfer member is a recording medium.
14. The image forming apparatus according to claim 10, wherein the charging unit is a charging roller.

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