CN108363276B

CN108363276B - Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Info

Publication number: CN108363276B
Application number: CN201711416856.7A
Authority: CN
Inventors: 鹤见裕树; 宫本荣一
Original assignee: Kyocera Document Solutions Inc
Current assignee: Kyocera Document Solutions Inc
Priority date: 2017-01-27
Filing date: 2017-12-25
Publication date: 2021-10-22
Anticipated expiration: 2037-12-25
Also published as: CN108363276A; JP6624093B2; JP2018120161A

Abstract

The invention provides an electrophotographic photoreceptor, a process cartridge and an image forming apparatus. An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer. The photosensitive layer is a monolayer type photosensitive layer. The photosensitive layer contains a charge generator, a hole transporting agent, an electron transporting agent, and a binder resin. The hole transport agent contains a triphenylamine derivative. The triphenylamine derivative is represented by the general formula (HT). The binder resin contains a polyarylate resin. The polyarylate resin is represented by the general formula (1). In the general formula (1), Q¹～Q⁴R, s, t, u, X and Y are respectively Q described in the specification¹～Q⁴R, s, t, u, X and Y have the same meaning. R in the formula (HT)¹～R³K, p, q, m1 and m2 are respectively the same as R in the specification¹～R³K, p, q, m1 and m2 have the same meaning. [ CHEM 1 ]

[ CHEM 2 ]

Description

Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Technical Field

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

Background

Electrophotographic photoreceptors are used as image carriers in electrophotographic image forming apparatuses (e.g., printers or multifunction machines). The electrophotographic photoreceptor includes a photosensitive layer. For example, a single-layer type electrophotographic photoreceptor is used as the electrophotographic photoreceptor. The single-layer electrophotographic photoreceptor has a photosensitive layer having a charge generating function and a charge transporting function. The photosensitive layer in the laminated electrophotographic photoreceptor includes a charge generation layer having a charge generation function and a charge transport layer having a charge transport function.

Patent document 1 describes a polyarylate Resin having a repeating unit represented by the chemical formula (Resin-G). Also, an electrophotographic photoreceptor containing the polyarylate resin is described.

[ CHEM 1 ]

[ patent document ]

Patent document 1: japanese laid-open patent publication No. 5-297601

Disclosure of Invention

However, in the technique described in patent document 1, the occurrence of transfer memory cannot be sufficiently suppressed.

The present invention has been made in view of the above problems, and an object thereof is to provide an electrophotographic photoreceptor in which occurrence of transfer memory is suppressed. Another object of the present invention is to provide a process cartridge and an image forming apparatus that suppress occurrence of an image failure.

The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a monolayer type photosensitive layer. The photosensitive layer contains a charge generator, a hole transporting agent, an electron transporting agent, and a binder resin. The hole transport agent contains a triphenylamine derivative. The triphenylamine derivative is represented by general formula (HT). The binder resin contains a polyarylate resin. The polyarylate resin is represented by the general formula (1).

[ CHEM 2 ]

In the general formula (1), Q¹、Q²、Q³And Q⁴Each independently represents a hydrogen atom or a methyl group. r and s represent integers of 0 to 49 inclusive. t and u represent integers of 1 to 50 inclusive. r + s + t + u is 100. r + t is s + u. r and t may be the same or different from each other. s and u may be the same or different from each other. X is a divalent group represented by chemical formula (2A), chemical formula (2B), chemical formula (2C), chemical formula (2D), chemical formula (2E), or chemical formula (2F). Y is a divalent group represented by chemical formula (4A), chemical formula (4B), chemical formula (4C), chemical formula (4D), or chemical formula (4E). X and Y are different from each other.

[ CHEM 3 ]

[ CHEM 4 ]

In the general formula (HT), R¹、R²And R³Each independently represents a group selected from the group consisting of C1-C4 alkoxy and C1-C4 alkyl. k. p and q are each independently an integer of 0 to 5 inclusive. m1 and m2 are each independently an integer of 1 to 3. In the case where k represents an integer of 2 or more, a plurality of R¹May be the same or different from each other. In the case where p represents an integer of 2 or more, several R2 may be the same as or different from each other. In the case where q represents an integer of 2 or more, a plurality of R³May be the same or different from each other.

The process cartridge of the present invention includes the electrophotographic photoreceptor.

The image forming apparatus of the present invention includes an image bearing member, a charging section, an exposure section, a developing section, and a transfer section. The charging unit charges a surface of the image carrier. The exposure unit exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier. The developing section develops the electrostatic latent image into a toner image. The transfer section transfers the toner image from the image bearing member to a transfer body. The image bearing member is the electrophotographic photoreceptor. The charging polarity of the charging section is positive. The charging unit charges the surface of the image bearing member by applying a dc voltage while contacting the surface of the image bearing member. The transfer body is a recording medium. The transfer section transfers the toner image to the transfer body when the surface of the image bearing member comes into contact with the transfer body.

[ Effect of the invention ]

The electrophotographic photoreceptor of the present invention can suppress the occurrence of transfer memory. Also, the process cartridge and the image forming apparatus of the present invention can suppress occurrence of image failure.

Drawings

Fig. 1(a), 1(b), and 1(c) are schematic cross-sectional views each showing the structure of an electrophotographic photoreceptor according to a first embodiment of the present invention.

Fig. 2 shows an example of an image forming apparatus according to a second embodiment of the present invention.

Fig. 3 shows an image in which image sticking occurs.

Fig. 4 shows an evaluation image.

Detailed Description

The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the intended scope of the present invention. Note that, although the description thereof may be omitted as appropriate, the gist of the present invention is not limited thereto. In the present specification, the compound and its derivatives may be collectively referred to by adding "class" to the compound name. When a compound name is followed by "class" to indicate a polymer name, the repeating unit indicating the polymer is derived from the compound or a derivative thereof.

Hereinafter, the halogen atom, C1-C6 alkyl group, C1-C5 alkyl group, C1-C4 alkyl group, C1-C3 alkyl group, C1-C2 alkyl group, C1-C4 alkoxy group, C6-C14 aryl group and C8-C12 phenylalkenyl group have the respective meanings as follows.

Halogen atoms (halogen groups) are for example: a fluorine atom (fluoro group), a chlorine atom (chloro group), a bromine atom (bromo group), or an iodine atom (iodo group).

The C1-C6 alkyl group is linear or branched and unsubstituted. C1-C6 alkyl is, for example: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl or hexyl.

The C1-C5 alkyl group is linear or branched and unsubstituted. C1-C5 alkyl is, for example: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, or neopentyl.

The C1-C4 alkyl group is linear or branched and unsubstituted. C1-C4 alkyl is, for example: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, or tert-butyl.

The C1-C3 alkyl group is linear or branched and unsubstituted. C1-C3 alkyl is, for example: methyl, ethyl, propyl or isopropyl.

The C1-C2 alkyl group is linear and unsubstituted. C1-C2 alkyl is, for example: methyl or ethyl.

The C1-C4 alkoxy group is linear or branched and unsubstituted. C1-C4 alkoxy is, for example: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy or tert-butoxy.

The C6-C14 aryl group is unsubstituted. C6-C14 aryl is, for example: C6-C14 unsubstituted aromatic monocyclic hydrocarbon group, C6-C14 unsubstituted aromatic condensed bicyclic hydrocarbon group or C6-C14 unsubstituted aromatic condensed tricyclic hydrocarbon group. C6-C14 aryl is, for example: phenyl, naphthyl, anthryl or phenanthryl.

C8-C12 phenylalkenyl is a group in which a phenyl group is bonded to a C2-C6 alkylpolyalkenyl group (alkapolyene group). The C8-C12 phenylalkenyl group is linear or branched and unsubstituted. C8-C12 phenylalkenyl is, for example: vinyl, butadienyl or hexanetrienyl.

< first embodiment: electrophotographic photoreceptor

The structure of an electrophotographic photoreceptor (hereinafter, may be referred to as a photoreceptor) according to a first embodiment of the present invention will be described. Fig. 1 is a schematic cross-sectional view showing the structure of a photoreceptor 1 according to the first embodiment. As shown in fig. 1(a), the photoreceptor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a monolayer type photosensitive layer. As shown in fig. 1(a), the photosensitive layer 3 may be directly disposed on the conductive substrate 2. As shown in fig. 1(b), the photoreceptor 1 includes, for example, a conductive substrate 2, an intermediate layer 4 (undercoat layer), and a photosensitive layer 3. As shown in fig. 1(b), the photosensitive layer 3 may be indirectly disposed on the conductive substrate 2. As shown in fig. 1(b), the intermediate layer 4 may be provided between the conductive substrate 2 and the photosensitive layer 3. As shown in fig. 1(c), the photoreceptor 1 may also have a protective layer 5 as the outermost surface layer.

The photosensitive layer 3 contains a charge generator, a hole transporting agent, an electron transporting agent, and a binder resin. The hole-transporting agent contains a triphenylamine derivative represented by general formula (HT) (hereinafter, may be referred to as triphenylamine derivative (HT)). The binder resin contains a polyarylate resin represented by general formula (1) (hereinafter, may be referred to as polyarylate resin (1)). The photoreceptor according to the first embodiment can suppress the occurrence of transfer memory. The reason is presumed as follows.

For ease of understanding, the transfer memory will be explained first. In the electrophotographic image formation, for example, an image formation process including the steps of 1) to 4) below is performed.

1) A charging step of charging the surface of an image carrier (corresponding to a photoreceptor);

2) an exposure step of exposing the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier;

3) a developing step of developing the electrostatic latent image into a toner image; and

4) and a transfer step of transferring the formed toner image from the image bearing member to a recording medium.

In such an image forming method, since the image carrier is rotated when the image carrier is used, transfer memory may be generated in the transfer step. The details are as follows. In the charging step, the surface of the image bearing member is uniformly charged to a positive potential. Next, after passing through an exposure step and a development step, in a transfer step, a transfer bias having a polarity opposite to the charged polarity (negative polarity) is applied to the image bearing member via the recording medium. Specifically, the potential of the non-exposure region (non-image region) on the surface of the image carrier may be greatly lowered by the influence of the transfer bias of the opposite polarity applied, and the potential may be maintained in a lowered state. Due to the influence of such a potential drop, the non-exposure region is less likely to be charged to a desired positive potential in a charging step of a subsequent turn based on one turn of the image formed on the photoreceptor (hereinafter, sometimes referred to as a reference turn). On the other hand, even in a state where a transfer bias is applied, since the toner adheres to the exposed region and the transfer bias is hard to be directly applied to the surface of the photoreceptor, the potential of the exposed region (image region) is hard to be lowered. Therefore, the exposure region is easily charged to a desired positive potential in the next charging step of the reference ring. As a result, the charging potentials at the exposed area and the non-exposed area are different from each other, and it is sometimes difficult to uniformly charge the surface of the image bearing member to a certain positive potential.

In this way, the potential is lowered by the transfer bias in the reference ring image forming process (image forming process) of the photoreceptor 1, and the charging performance in the non-exposure region may be lowered. This phenomenon of generating a potential difference between charged potentials is called transfer memory.

In the triphenylamine structure at the center of the triphenylamine derivative (HT), 2 benzene rings out of 3 benzene rings have a substituent which is a C8-C12 phenylalkenyl group having R2 or R3. Among them, since the spatial range of the pi conjugated system of the triphenylamine derivative (HT) is relatively large, the moving distance of the carrier (hole) in the molecule of the triphenylamine derivative (HT) tends to increase. That is, the intramolecular movement distance of the carrier (hole) tends to increase. In the photosensitive layer 3, pi-conjugated systems of several triphenylamine derivatives (HT) are likely to overlap, and the distance of movement of the carrier (hole) between molecules of several triphenylamine derivatives (HT) tends to decrease. That is, the distance of movement between molecules of the carrier (hole) tends to decrease. On the other hand, since the triphenylamine derivative (HT) has 1 nitrogen atom in the molecule, the uneven distribution of charges in the molecule tends to be less than that of a compound having 2 nitrogen atoms in the molecule (for example, a diamine compound). From this, it is considered that the triphenylamine derivative (HT) can improve the carrier receptivity (injectability) and the carrier transportability of the photoreceptor 1. The photosensitive layer 3 containing the triphenylamine derivative (1) is easy to stabilize the surface potential during charging.

The polyarylate resin (1) has a repeating unit derived from a dicarboxylic acid and a repeating unit derived from a diol as represented by the general formula (1). The repeating unit derived from the dicarboxylic acid has a divalent substituent represented by general formulas (4A) to (4E), and the repeating unit derived from the diol has a fluorenyl group. The polyarylate resin having such a structure easily forms a photosensitive layer having a high layer density and easily forms the photosensitive layer 3 having a high hardness. Therefore, the surface potential during charging is easily kept stable. Since the polyarylate resin (1) has excellent compatibility with the triphenylamine derivative (HT), the polyarylate resin (1) easily disperses the triphenylamine derivative (HT) in the photosensitive layer 3. This makes it easy to improve the carrier transportability of the photosensitive layer 3. As described above, the photoreceptor according to the first embodiment is considered to be capable of suppressing the occurrence of transfer memory.

The elements (the conductive substrate, the photosensitive layer, and the intermediate layer) of the photoreceptor according to the first embodiment will be described below. A method for manufacturing the photoreceptor will be described.

[1. conductive substrate ]

The conductive substrate 2 is not particularly limited as long as it can be used as a conductive substrate of the photoreceptor 1. The conductive substrate 2 may be a conductive substrate having at least a surface portion made of a conductive material (hereinafter, referred to as a conductive substrate). The conductive substrate is, for example: a conductive substrate made of a conductive material or a conductive substrate coated with a conductive material. The conductive material is, for example: aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, or indium. One of these conductive materials may be used alone, or two or more of them may be used in combination. The combination of two or more types is, for example, an alloy (specifically, an aluminum alloy, stainless steel, brass, or the like). Among these conductive materials, aluminum or an aluminum alloy is preferable because the movement of charges from the photosensitive layer 3 to the conductive substrate 2 is good.

The shape of the conductive substrate 2 can be appropriately selected according to the structure of the image forming apparatus to be used. The conductive substrate 2 has a sheet-like or drum-like shape, for example. The thickness of the conductive substrate 2 may be appropriately selected according to the shape of the conductive substrate 2.

[2. photosensitive layer ]

The photosensitive layer 3 contains a charge generator, a hole transporting agent, an electron transporting agent, and a binder resin. The photosensitive layer 3 may also contain additives. The thickness of the photosensitive layer 3 is not particularly limited as long as the photosensitive layer 3 can sufficiently function. Specifically, the thickness of the photosensitive layer 3 may be 5 μm to 100 μm, and preferably 10 μm to 50 μm.

Hereinafter, the charge generating agent, the hole transporting agent, the electron transporting agent, the binder resin, and the additive will be described.

[2-1. Charge-generating agent ]

The charge generating agent is not particularly limited as long as it is a charge generating agent for the photoreceptor 1. Examples of charge generators are: phthalocyanine pigments, perylene pigments, disazo pigments, diketopyrrolopyrrole (dithioketo-pyrropyrrole) pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaric acid pigments, trisazo pigments, indigo pigments, azulene pigments, cyanine pigments; powders of inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon; a pyran salt, an anthanthroquinone pigment, a triphenylmethane pigment, a threne pigment, a toluidine pigment, a pyrazoline pigment, or a quinacridone pigment. Examples of phthalocyanine pigments are: phthalocyanine pigments or pigments of phthalocyanine derivatives. Phthalocyanine pigments are, for example: metal-free phthalocyanine pigment (more specifically, X-type metal-free phthalocyanine pigment (X-H)₂Pc), etc.). Examples of pigments of phthalocyanine derivatives are: a metal phthalocyanine pigment (more specifically, a oxytitanium phthalocyanine pigment or a V-type hydroxygallium phthalocyanine pigment, etc.). The crystal shape of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes can be used. The crystal shape of the phthalocyanine pigment is, for example: alpha, beta or Y. One kind of charge generating agent may be used alone, or two or more kinds may be used in combination. Among these charge generating agents, phthalocyanine pigments are preferable, metal-free phthalocyanine pigments or oxytitanium phthalocyanine pigments are more preferable, and X-type metal-free phthalocyanine pigments (X-H) are even more preferable₂Pc) or a Y-type oxytitanium phthalocyanine pigment (Y-TiOPc).

The Y-type oxytitanium phthalocyanine pigment has a main peak at a bragg angle 2 θ ± 0.2 ° -27.2 ° in a Cu — K α characteristic X-ray diffraction spectrum. The main peak in the CuK α characteristic X-ray diffraction spectrum means a peak having a first or second large intensity in a range where the bragg angle (2 θ ± 0.2 °) is 3 ° or more and 40 ° or less.

(method for measuring CuK alpha characteristic X-ray diffraction Spectrum)

A method for measuring CuK α characteristic X-ray diffraction spectrum will be explained. A sample (oxytitanium phthalocyanine) was charged in a sample holder of an X-ray diffraction apparatus ("R1 NT (Japanese registered trademark) 1100" manufactured by Rigaku Corporation) under X-ray tube Cu, tube voltage 40kV, tube current 30mA, and wavelength of CuK α characteristic X-ray

Under the conditions of (1), an X-ray diffraction spectrum was measured. The measurement range (2 θ) is 3 ° to 40 ° (the start angle is 3 °, and the stop angle is 40 °), and the scanning speed is, for example, 10 °/min. And determining a main peak according to the obtained X-ray diffraction spectrum, and reading out the Bragg angle of the main peak.

The charge generating agent having an absorption wavelength in a desired region may be used alone, or 2 or more kinds of charge generating agents may be used in combination. In addition, for example, in a digital optical image forming apparatus, a photoreceptor having sensitivity in a wavelength region of 700nm or more is preferably used. The digital optical image forming apparatus is, for example: laser printers or facsimile machines using a light source such as a semiconductor laser. Therefore, for example, phthalocyanine pigments are preferable, and X-type metal-free phthalocyanine pigments or Y-type oxytitanium phthalocyanine pigments are more preferable. From the viewpoint of further improving the sensitivity characteristics of the photoreceptor 1, the Y-type oxytitanium phthalocyanine pigment is more preferable. From the viewpoint of further suppressing the occurrence of transfer memory, an X-type metal-free phthalocyanine pigment is more preferable.

In the photoreceptor 1 used in an image forming apparatus using a short-wavelength laser light source, an anthanthrone pigment or a perylene pigment is preferably used as the charge generating agent. The wavelength of the short-wavelength laser light is, for example, 350nm to 550 nm.

The charge generating agent is, for example, phthalocyanine pigments represented by chemical formulas (CGM-1) to (CGM-4) (hereinafter, sometimes referred to as charge generating agents (CGM-1) to (CGM-4), respectively).

[ CHEM 5 ]

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

[2-2. hole-transporting agent ]

The hole transport agent contains a triphenylamine derivative (HT). The triphenylamine derivative (HT) is represented by the general formula (HT).

[ CHEM 6 ]

In the general formula (HT), R¹、R²And R³Each independently represents a group selected from the group consisting of C1-C4 alkyl groups and C1-C4 alkoxy groups. k. p and q are each independently an integer of 0 to 5 inclusive. m1 and m2 are each independently an integer of 1 to 3. In the case where k represents an integer of 2 or more, a plurality of R¹May be the same or different from each other. In the case where p represents an integer of 2 or more, a number of R²May be the same or different from each other. In the case where q represents an integer of 2 or more, several R3 may be the same as or different from each other.

In the general formula (HT), R¹The C1-C4 alkyl radicals represented are preferably methyl, ethyl or n-butyl. R¹The C1-C4 alkoxy radical is preferably ethoxy or n-butoxy. With respect to the bond of the nitrogen atom, R¹The substituents represented may be in any of the ortho (o position), meta (m position) or para (p position) positions of the benzene ring, and are preferably in the ortho or para positions.

In the general formula (HT), preference is given to: r¹Represents a group selected from the group consisting of C1-C4 alkoxy and C1-C4 alkyl, k represents 1 or 2, and in the case where k represents 2, 2R' s¹May be the same or different from each other, p and q represent 0, m1 and m2 represents 2 or 3.

From the viewpoint of further suppressing the occurrence of transfer memory and improving the sensitivity characteristics of the photoreceptor 1, in the general formula (HT), it is preferable that: r¹Represents a C1-C4 alkyl group, and k represents 2. From the viewpoint of further suppressing the occurrence of transfer memory and improving the sensitivity characteristics of the photoreceptor, m1 and m2 preferably represent 2 or 3 in the general formula (HT).

Triphenylamine derivatives (HT) are, for example: the triphenylamine derivative represented by the formula (HT-1), the formula (HT-2), the formula (HT-3), the formula (HT-4), the formula (HT-5), the formula (HT-6) or the formula (HT-7) (hereinafter, may be referred to as a triphenylamine derivative (HT-1), a triphenylamine derivative (HT-2), a triphenylamine derivative (HT-3), a triphenylamine derivative (HT-4), a triphenylamine derivative (HT-5), a triphenylamine derivative (HT-6) or a triphenylamine derivative (HT-7)).

[ CHEM 7 ]

The hole-transporting agent may contain other hole-transporting agents in addition to the triphenylamine derivative (HT). Other hole-transporting agents are, for example: diamine derivatives (more specifically, N '-tetraphenylphenylenediamine derivatives, N' -tetraphenylnaphthalenediamine derivatives, or N, N '-tetraphenylphenylenediamine (N, N' -tetraphenylphenylenediamine) derivatives, etc.); oxadiazole compounds (more specifically, 2, 5-bis (4-methylaminophenyl) -1, 3, 4-oxadiazole and the like); a styrenic compound (more specifically, 9- (4-diethylaminostyryl) anthracene, etc.); carbazole-based compounds (more specifically, polyvinylcarbazole and the like); an organic polysilane compound; pyrazolines (more specifically, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, etc.); a hydrazone compound; indole compounds; an oxazole compound; isoxazoles compounds; thiazole compounds; a thiadiazole compound; imidazole compounds; a pyrazole compound; a triazole compound.

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.

[2-3. Electron-transporting Agents ]

Examples of electron transport agents are: quinone compounds, imide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3, 4, 5, 7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2, 4, 8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride or dibromomaleic anhydride. Quinone compounds are for example: a diphenoquinone compound, an azoquinone compound, an anthraquinone compound, a naphthoquinone compound, a nitroanthraquinone compound or a dinitroanthraquinone compound. These electron transport agents may be used alone in 1 kind, or may be used in combination with 2 or more kinds. Among the above electron transport agents, the electron transport agent represented by the general formula (ET1), the general formula (ET2), the general formula (ET3), the general formula (ET4) or the general formula (ET5) is sometimes described as an electron transport agent (ET1), an electron transport agent (ET2), an electron transport agent (ET3), an electron transport agent (ET4) and an electron transport agent (ET5) in the following description.

[ CHEM 8 ]

In the general formula (ET1), R¹¹And R¹²Each independently represents a C1-C6 alkyl group. In the general formula (ET2), R¹³、R¹⁴、R¹⁵And R¹⁶Each independently represents a C1-C6 alkyl group. In the general formula (ET3), R¹⁷And R¹⁸Independently of one another, represent a C6-C14 aryl radical, the C6-C14 aryl radical possibly having 1 or several C1-C3 alkyl substituents. In the general formula (ET4), R¹⁹And R²⁰Each independently represents a C1-C6 alkyl group. R²¹Represents a C6-C14 aryl group, the C6-C14 aryl group may have 1 or several halogen atoms. In the general formula (ET5), the formula (ET5),R²²、R²³、R²⁴and R²⁵Each independently represents a C1-C6 alkyl group.

From the viewpoint of further suppressing the occurrence of transfer memory, the electron transport agent (ET1) to (ET5) is preferably the electron transport agent (ET1) or (ET 2).

In the general formula (ET1), R¹¹And R¹²Preferably represents a C1-C5 alkyl group, more preferably a 2-methyl-2-butyl group. The electron transport agent (ET1) is, for example, an electron transport agent represented by the chemical formula (ET1-1) (hereinafter, may be referred to as an electron transport agent (ET 1-1)).

In the general formula (ET2), R¹³、R¹⁴、R¹⁵And R¹⁶Preferably represents a C1-C4 alkyl group, more preferably a methyl or tert-butyl group. The electron transport agent (ET2) is, for example, an electron transport agent represented by the chemical formula (ET2-1) (hereinafter, may be referred to as an electron transport agent (ET 2-1)).

In the general formula (ET3), R¹⁷And R¹⁸Preferably represents a phenyl group having several C1-C2 alkyl substituents, more preferably a 2-ethyl-6-methylphenyl group. The electron transport agent (ET3) is, for example, an electron transport agent represented by the chemical formula (ET3-1) (hereinafter, may be referred to as an electron transport agent (ET 3-1)).

In the general formula (ET4), R¹⁹And R²⁰Preferably represents a C1-C4 alkyl group, more preferably a tert-butyl group. R²¹Preferably represents a phenyl group having a halogen atom, more preferably represents a chlorophenyl group, and still more preferably represents a p-chlorophenyl group. The electron transport agent (ET4) is, for example, an electron transport agent represented by the chemical formula (ET4-1) (hereinafter, may be referred to as an electron transport agent (ET 4-1)).

In the general formula (ET5), R²²、R²³、R²⁴And R²⁵Preferably represents a C1-C4 alkyl group, more preferably a methyl or tert-butyl group. The electron transport agent (ET5) is, for example, an electron transport agent represented by the chemical formula (ET5-1) (hereinafter, may be referred to as an electron transport agent (ET 5-1)).

[ CHEM 9 ]

[2-4. Binder resin ]

The binder resin contains a polyarylate resin (1). The polyarylate resin (1) is represented by the general formula (1).

[ CHEM 10 ]

[ CHEM 11 ]

From the viewpoint of further improving the sensitivity characteristics of the photoreceptor 1 and further suppressing the occurrence of transfer memory, in the general formula (1), Q¹、Q²、Q³And Q⁴Preferably represents a methyl group.

In the general formula (1), Y is preferably a divalent group represented by the general formula (4A), the general formula (4B), or the general formula (4C) when s represents 0, from the viewpoint of further improving the sensitivity characteristics of the photoreceptor 1 and further suppressing the occurrence of transfer memory. In the general formula (1), when s represents an integer of 1 or more, it is preferable that: x is a divalent group represented by the general formula (2A), the general formula (2B) or the general formula (2C), and Y is a divalent group represented by the general formula (4A), the general formula (4B) or the general formula (4C).

s may be an integer of 1 or more. Can be as follows: r and s are different from each other, and r and u are different from each other. It can also be: t and s are different from each other, and t and u are different from each other.

The polyarylate resin (1) has a repeating unit represented by the general formula (1-7) (hereinafter, sometimes referred to as a repeating unit (1-7)) and a repeating unit represented by the general formula (1-8) (hereinafter, sometimes referred to as a repeating unit (1-8)). When r and s represent an integer of 1 or more, the polyarylate resin (1) further has a repeating unit represented by the chemical formula (1-5) (hereinafter, sometimes referred to as a repeating unit (1-5)) and a repeating unit represented by the general formula (1-6) (hereinafter, sometimes referred to as a repeating unit (1-6)).

[ CHEM 12 ]

Q in the general formula (1-5)¹And Q²X in the general formula (1-6) or Q in the general formula (1-7)³And Q⁴And Y in the general formulae (1-8) and Q in the general formula (1), respectively¹、Q²、X、Q³、Q₄And Y have the same meaning.

The polyarylate resin (1) may contain a repeating unit other than the repeating units (1-5) to (1-8). In the polyarylate resin (1), the ratio (mole fraction) of the total amount of the substances having the repeating units (1-5) to (1-8) to the total amount of the substances having the repeating units is preferably 0.80 or more, more preferably 0.90 or more, and still more preferably 1.00.

In the polyarylate resin (1), the arrangement of the repeating units (1-5) to (1-8) is not particularly limited as long as the repeating unit derived from the aromatic diol and the repeating unit derived from the aromatic dicarboxylic acid are adjacent to each other. For example, the repeating units (1-5) and the repeating units (1-7) are each independently bonded to each other adjacent to the repeating units (1-6) or the repeating units (1-8).

In the general formula (1), r and s represent integers of 0 to 49 inclusive. t and u represent integers of 1 to 50 inclusive. r + s + t + u is 100. r + t is s + u. s/(s + u) may be 0.30 to 0.70. s/(s + u) represents: in the polyarylate resin (1), the ratio (mole fraction) of the amount of the substance having the repeating unit (1-6) to the total of the amounts of the substance having the repeating unit (1-6) and the substance having the repeating unit (1-8) is determined.

The polyarylate Resin (1) is, for example, polyarylate resins represented by the chemical formulas (Resin-1) to (Resin-11) (hereinafter, sometimes referred to as polyarylate resins (Resin-1) to (Resin-11)).

[ CHEM 13 ]

[ CHEM 14 ]

[ CHEM 15 ]

The viscosity average molecular weight of the binder resin is preferably 10,000 or more, more preferably 14,000 or more, further preferably 20,000 or more, and particularly preferably 48,000 or more. The viscosity average molecular weight of the binder resin is preferably 100,000 or less, more preferably 80,000 or less, still more preferably 70,000 or less, and particularly preferably 53,000 or less. When the viscosity average molecular weight of the binder resin is 20,000 or more, the abrasion resistance of the binder resin can be improved, and the charge transport layer becomes less likely to be abraded. On the other hand, when the viscosity average molecular weight of the binder resin is 70,000 or less, the binder resin is easily dissolved in a solvent at the time of forming the photosensitive layer, and the photosensitive layer is likely to be easily formed.

(method for producing polyarylate resin (1))

The method for producing the polyarylate resin (1) is not particularly limited as long as the polyarylate resin (1) can be produced. Such a manufacturing method is, for example: a method for polycondensing an aromatic diol and an aromatic dicarboxylic acid constituting a repeating unit of the polyarylate resin (1). The method for synthesizing the polyarylate resin (1) is not particularly limited, and a known synthesis method (more specifically, solution polymerization, melt polymerization, interfacial polymerization, or the like) can be used. An example of the method for producing the polyarylate resin (1) will be described below.

For example, the polyarylate resin (1) is produced by the reaction represented by the reaction formula (R-1) (hereinafter, sometimes referred to as reaction (R-1)) or the like. The method for producing a polyarylate resin comprises, for example, the reaction (R-1).

[ CHEM 16 ]

In the reaction (R-1), Q in the general formula (1-11)¹And Q²Q in the general formula (1-12)³And Q⁴X in the general formula (1-9) and Y in the general formula (1-10) are respectively Q in the general formula (1)¹、Q²、Q³、Q⁴X and Y have the same meaning.

In the reaction (R-1), the aromatic dicarboxylic acids represented by the general formulae (1 to 9) and the aromatic dicarboxylic acids represented by the general formulae (1 to 10) (hereinafter, sometimes referred to as the aromatic dicarboxylic acids (1 to 9) and (1 to 10), respectively) are reacted with the aromatic diglycolic acids represented by the general formulae (1 to 11) and the aromatic diols represented by the general formulae (1 to 12) (hereinafter, sometimes referred to as the aromatic diols (1 to 11) and (1 to 12), respectively), to obtain the polyarylate resin (1).

The amount of the total of the aromatic diols (1-11) and (1-12) is preferably 0.9 mol or more and 1.1 mol or less relative to 1 mol of the total of the aromatic carboxylic acids (1-9) and (1-10). The reason is that: when the amount is within the above range, the polyarylate resin (1) can be easily purified, and the yield of the polyarylate resin (1) can be improved.

The reaction (R-1) may be carried out in the presence of a base and a catalyst. Examples of catalysts are: tertiary ammonium (more specifically, trialkylamine, etc.) or quaternary ammonium salt (more specifically, benzyltrimethylammonium bromide, etc.). The base is, for example: hydroxides of alkali metals (more specifically, sodium hydroxide, potassium hydroxide, or the like), hydroxides of alkaline earth metals (more specifically, calcium hydroxide, or the like). The reaction (R-1) may be carried out in a solvent under an inert gas atmosphere. Examples of solvents are: water or chloroform. The inert gas is for example argon. The reaction time of the reaction (R-1) is preferably 2 hours or more and 5 hours or less. The reaction temperature is preferably 5 ℃ to 25 ℃.

Aromatic dicarboxylic acids are, for example: an aromatic dicarboxylic acid having 2 carboxyl groups bonded to an aromatic ring (more specifically, naphthalenedicarboxylic acid, 4 '-diphenyletherdicarboxylic acid, 4' -biphenyldicarboxylic acid, or the like). The aromatic dicarboxylic acid may contain other dicarboxylic acids in addition to the aromatic dicarboxylic acids (1-9) and (1-10). In addition, in the synthesis of the polyarylate resin, an aromatic dicarboxylic acid derivative (more specifically, haloalkanoyl or aromatic dicarboxylic anhydride) may be used instead of the aromatic dicarboxylic acid.

In the synthesis of polyarylate resins, aromatic diols can be used as derivatives such as diacetate salts. The aromatic diol may contain, in addition to the aromatic diols (1 to 11) and (1 to 12), other diols (for example, bisphenol a, bisphenol S, bisphenol E, or bisphenol F).

The production of the polyarylate resin (1) may include other steps as necessary. Such a step is, for example, a purification step. The purification method is, for example, a well-known method (more specifically, filtration, chromatography, crystallization or the like).

[2-5. additives ]

At least one of the photosensitive layer 3 and the intermediate layer 4 may contain various additives within a range that does not adversely affect the electrophotographic characteristics. Examples of additives are: a deterioration inhibitor (more specifically, an antioxidant, a radical scavenger, a quencher, an ultraviolet absorber, or the like), a softening agent, a surface modifier, an extender, a thickener, a dispersion stabilizer, a wax, a donor, a surfactant, or a leveling agent.

[3. intermediate layer ]

The photoreceptor 1 according to the first embodiment may have an intermediate layer 4 (e.g., an undercoat layer). The intermediate layer 4 contains, for example, inorganic particles and a resin (resin for intermediate layer). By providing the intermediate layer 4, it is possible to smoothly flow a current generated when the photoreceptor 1 is exposed, while maintaining an insulating state to such an extent that the occurrence of electric leakage can be suppressed, and to suppress an increase in resistance.

The inorganic particles are, for example: particles of a metal (more specifically, aluminum, iron, copper, or the like), particles of a metal oxide (more specifically, titanium oxide, aluminum oxide, zirconium oxide, tin oxide, zinc oxide, or the like), or particles of a non-metal oxide (more specifically, silicon dioxide, or the like). One of these inorganic particles may be used alone, or 2 or more of these inorganic particles may be used in combination.

[4 ] method for producing photoreceptor

A method for manufacturing the photoreceptor 1 will be described. The method of manufacturing the photoreceptor 1 includes, for example, a photosensitive layer forming step.

In the photosensitive layer forming step, a coating liquid for forming the photosensitive layer 3 (hereinafter, sometimes referred to as a photosensitive layer coating liquid) is prepared. The photosensitive layer is coated on the conductive substrate with the coating liquid. Then, the coating liquid for photosensitive layer is dried by an appropriate method to remove at least a part of the solvent contained in the coating liquid for photosensitive layer to be coated, thereby forming the photosensitive layer 3. The coating liquid for photosensitive layer contains, for example, a charge generator, a hole transporting agent, an electron transporting agent, a binder resin and a solvent. The coating liquid for photosensitive layer is prepared by dissolving or dispersing a charge generator, a hole transporting agent, an electron transporting agent and a binder resin in a solvent. Various additives may be added to the coating liquid for photosensitive layer, if necessary.

The photosensitive layer forming step will be described in detail below. The solvent contained in the coating liquid for photosensitive layer is not particularly limited as long as it can dissolve or disperse each component contained in the coating liquid for photosensitive layer and can be removed from the coating film. Examples of solvents are: alcohols (more specifically, methanol, ethanol, isopropanol, butanol, or the like), aliphatic hydrocarbons (more specifically, n-hexane, octane, cyclohexane, or the like), aromatic hydrocarbons (more specifically, benzene, toluene, xylene, or the like), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, or the like), ethers (more specifically, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or the like), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, or the like), esters (more specifically, ethyl acetate, methyl acetate, or the like), dimethyl formaldehyde, dimethyl formamide, or dimethyl sulfoxide. These solvents may be used alone, or two or more of them may be used in combination. Among these solvents, non-halogenated solvents are preferably used.

The coating liquid for photosensitive layer is prepared by mixing the components and dispersing them in a solvent. For the mixing or dispersing operation, for example, it is possible to use: bead mills, roller mills, ball mills, attritors, paint shakers or ultrasonic dispersers.

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

The method for coating with the coating liquid for photosensitive layer is not particularly limited as long as it can uniformly coat the coating liquid for photosensitive layer. The coating method is, for example: dip coating, spray coating, spin coating or bar coating.

The method for removing at least a part of the solvent contained in the coating liquid for photosensitive layer is not particularly limited as long as it is a method capable of removing (more specifically, evaporating or the like) at least a part of the solvent in the coating liquid for photosensitive layer. The removal method is, for example: heating, reducing pressure or a combination of heating and reducing pressure. More specifically, a method of performing heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer is given. The heat treatment conditions are, for example, a temperature of 40 ℃ to 150 ℃ and a time of 3 minutes to 120 minutes.

The method for manufacturing the photoreceptor 1 may further include a step of forming an intermediate layer, if necessary. The step of forming the intermediate layer may be appropriately selected from known methods.

< second embodiment: image forming apparatus

An embodiment of an image forming apparatus according to a second embodiment will be described below with reference to fig. 2. Fig. 2 shows an example of an image forming apparatus according to a second embodiment.

The image forming apparatus 100 according to the second embodiment includes an image forming unit 40. The image forming unit 40 includes an image carrier 30, a charging section 42, an exposure section 44, a developing section 46, and a transfer section 48. The image carrier 30 is the photoreceptor according to the first embodiment. The charging section 42 applies a dc voltage while contacting the surface of the image carrier 30, thereby charging the surface of the image carrier 30. The charging polarity of the charging section 42 is positive. The exposure section 44 exposes the surface of the charged image carrier 30, and forms an electrostatic latent image on the surface of the image carrier 30. The developing section 46 develops the electrostatic latent image into a toner image. When the surface of the image bearing member 30 comes into contact with the recording medium P as a transfer member, the transfer portion 48 transfers the toner image from the image bearing member 30 onto the recording medium P. The image forming apparatus according to the second embodiment is briefly described above.

The image forming apparatus 100 according to the second embodiment can suppress image failure (for example, image failure due to occurrence of transfer memory). The reason is presumed as follows. The image forming apparatus 100 according to the second embodiment includes the photosensitive member according to the first embodiment as the image carrier 30. The photoreceptor according to the first embodiment can suppress the occurrence of transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image failure.

An image failure caused by transfer memory will be described. After the transfer memory is generated during the image forming process, when one turn (reference turn) of the photoreceptor 1 during the image forming is used as a reference, the potential of a region on the surface of the image carrier 30 where a desired potential cannot be obtained in the charging process of the next turn is often lower than that of a region where a desired potential can be obtained in the charging process of the next turn of the reference turn. Specifically, on the surface of the image carrier 30, the potential of the next turn charged tends to be lower in the non-exposed area of the reference circle than in the exposed area of the reference circle. Therefore, the non-exposed region of the reference ring is more likely to have a lower potential during charging than the exposed region of the reference ring, and to attract positively charged toner during development. As a result, an image reflecting the non-image portion (non-exposure region) of the reference circle is easily formed. The image failure in which the image reflecting the reference circle image portion is formed is an image failure due to transfer memory (hereinafter, sometimes referred to as image sticking).

An image in which an image failure has occurred will be described with reference to fig. 3. Fig. 3 shows an image 60 in which image sticking has occurred. Image 60 contains region 62 and region 64. The region 62 corresponds to one turn of the image carrier, and the region 64 corresponds to one turn of the image carrier. Region 62 contains image 66. The image 66 is composed of a square solid image. Region 64 contains image 68 and image 69. Image 68 is a square halftone image. Image 69 is a halftone image having square spaces in region 64. Image 69 is darker in image density than image 68. The image 69 reflects the non-exposed area of the area 62, and the image 69 is an image failure (image sticking) in which the image density is darker than the design image density. In addition, the image of the region 64 should theoretically be composed of a full-scale halftone image.

Hereinafter, each member will be described in detail with reference to fig. 2. 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 a monochrome image forming apparatus or a color image forming apparatus, for example. When the image forming apparatus 100 is a color image forming apparatus, the image forming apparatus 100 employs, for example, a tandem system. Hereinafter, the image forming apparatus 100 of the tandem system will be described as an example.

The image forming apparatus 100 includes

image forming units

40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing unit 52. Hereinafter, the

image forming units

40a, 40b, 40c, and 40d are all described as the image forming unit 40 in the case where distinction is not necessary. In the case where image forming apparatus 100 is a monochrome image forming apparatus, image forming apparatus 100 includes image forming unit 40a, and image forming units 40b to 40d are omitted.

The image forming apparatus 100 may employ a direct transfer method. In general, in an image forming apparatus employing a direct transfer method, a toner image is transferred onto a recording medium when a surface of an image bearing member is brought into contact with the recording medium. Therefore, the image carrier is greatly affected by the transfer bias compared to the image carrier mounted in the image forming apparatus adopting the intermediate transfer method. Therefore, it is difficult to suppress the occurrence of image failure due to the occurrence of transfer memory. However, the image forming apparatus 100 according to the second embodiment includes the photoreceptor according to the first embodiment. The photoreceptor according to the first embodiment can suppress the occurrence of transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image failure due to occurrence of transfer memory, although the direct transfer method is adopted.

In the image forming unit 40, the image carrier 30 is disposed at the center thereof. The image carrier 30 is provided to be rotatable in the arrow direction (counterclockwise direction). Around the image carrier 30, a charging section 42, an exposure section 44, a developing section 46, and a transfer section 48 are provided in this order from the upstream side in the rotation direction of the image carrier 30 with reference to the charging section 42. The image forming unit 40 may further include one or both of a cleaning unit (not shown) and a discharging unit (not shown).

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

The charging section 42 charges the surface of the image carrier 30 while making contact with the surface of the image carrier 30. The charging section 42 is a contact type charging section, i.e., a charging roller. The charging portion of the other contact type is, for example, a charging brush. The charging unit may be a non-contact type charging unit. Examples of the non-contact type charging section include: corona charging part or grid corona charging part.

The contact type charging section is less likely to charge the surface of the photoreceptor than the non-contact type charging section. For example, in an image forming apparatus including a charging roller, it is generally difficult to suppress image failure caused by occurrence of transfer memory. The image forming apparatus 100 according to the second embodiment includes the photoreceptor according to the first embodiment. The photoreceptor according to the first embodiment suppresses the occurrence of transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image failure due to occurrence of transfer memory even when the image forming apparatus includes a contact-type charging unit.

The voltage applied by the charging section 42 is a dc voltage. In the case where the voltage applied to the image carrier by the charging section is a direct-current voltage, the amount of abrasion of the outermost surface layer (for example, the monolayer type photosensitive layer) of the photosensitive layer can be reduced as compared with the case of an alternating-current voltage or a superimposed voltage.

In the image forming apparatus including the contact charging type charging unit, although the surface potential on the surface of the image carrier may be made uniform by applying the ac voltage to the charging unit, the charging unit may be uniformly charged by applying only the dc voltage. By applying only a dc voltage to the charging roller, a good image can be formed and the amount of abrasion of the photosensitive layer can be reduced.

The exposure section 44 exposes the surface of the charged image carrier 30. Thereby, 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 section 46 supplies toner to the surface of the image carrier 30, thereby developing the electrostatic latent image into a toner image. The developing section 46 can develop the electrostatic latent image into a toner image while contacting the surface of the image carrier 30.

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

After the toner image is developed by the developing section 46, the transfer section 48 transfers the toner image from the surface of the image carrier 30 onto the recording medium P. The transfer section 48 is, for example, a transfer roller. When the toner image is transferred from the image carrier 30 onto the recording medium P, the surface of the image carrier 30 is kept in contact with the recording medium P.

After the transfer portion 48 transfers the toner image onto the recording medium P, the fixing portion 52 heats and/or pressurizes the unfixed toner image. The fixing section 52 is, for example, a heating roller and/or a pressure roller. The toner image is fixed to 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: processing box

A process cartridge according to a third embodiment includes the photoreceptor according to the first embodiment. Next, a process cartridge according to a third embodiment will be described with reference to fig. 2.

The process cartridge contains unitized portions. The unitized portion is like carrier 30. The unitized portion may include at least one selected from the group consisting of the charging section 42, the exposure section 44, the developing section 46, and the transfer section 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 one or both of a cleaning device (not shown) and a static eliminator (not shown). The process cartridge is designed to be freely attachable and detachable with respect to 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 replaced easily and quickly.

[ examples ] A method for producing a compound

The present invention will be described in more detail with reference to examples. The present invention is not to be limited in any way by the scope of the examples.

[ Material of photoreceptor ]

(hole transport agent)

The triphenylamine derivatives (HT-1) to (HT-7) described in the first embodiment were prepared. A hole-transporting agent represented by the formula (HT-8) or (HT-9) (hereinafter, sometimes referred to as hole-transporting agent (HT-8) or (HT-9)) is prepared.

[ CHEM 17 ]

(Electron transport agent)

The electron-transporting agents (ET1-1) to (ET5-1) described in the first embodiment were prepared.

(Charge generating agent)

The charge generating agents (CGM-1) to (CGM-2) described in the first embodiment were prepared. The charge generating agent (CGM-1) is X-type metal-free phthalocyanine represented by the chemical formula (CGM-1).

The charge generating agent (CGM-2) is a Y-type oxytitanium phthalocyanine pigment (Y-type oxytitanium phthalocyanine crystal) represented by the chemical formula (CGM-2). The crystal structure is Y-type.

The Y-type oxytitanium phthalocyanine crystal has peaks at bragg angles 2 θ ± 0.2 ° of 9.2 °, 14.5 °, 18.1 °, 24.1 °, and 27.2 ° in a CuK α characteristic X-ray diffraction spectrum chart, and the main peak is 27.2 °. The CuK α characteristic X-ray diffraction spectrum was measured by the measurement device and the measurement conditions described in the first embodiment.

(Binder resin)

Polyarylate resins (Resin-1) to (Resin-11)

The polyarylate resins (Resin-1) to (Resin-11) described in the first embodiment were produced.

[ preparation of polyarylate Resin (Resin-5) ]

A three-necked flask was used as a reaction vessel. The reaction vessel was a 1L three-necked flask equipped with a thermometer, a three-way valve and a 200mL dropping funnel. In a reaction vessel, 31.25g (82.56 mmol) of 9, 9-bis (3-methyl-4-hydroxyphenyl) fluorene, 0.124g (0.826 mmol) of t-butylphenol, 7.84g (196 mmol) of sodium hydroxide and 0.240g (0.768 mmol) of benzyltributylammonium chloride were placed. Then, the inside of the reaction vessel was replaced with argon. Then, 600mL of water was added to the reaction vessel. The contents of the reaction vessel were stirred for 1 hour at an internal temperature of the reaction vessel of 20 ℃. Then, the contents of the reaction vessel were cooled, and the internal temperature of the reaction vessel was lowered to 10 ℃. Thus, an alkaline aqueous solution was prepared.

A chloroform solution was prepared by dissolving 9.84g (38.9 mmol) of 2, 6-naphthalenedicarboxylic acid dichloride and 11.47g (38.9 mmol) of 4, 4' -chloroformylphenyl ether in 300g of chloroform (to which pentene was added).

Then, the internal temperature of the reaction vessel of the alkaline aqueous solution was maintained at 10 ℃, and the contents of the reaction vessel were stirred. The chloroform solution was added to the basic aqueous solution to start the polymerization reaction. The contents of the reaction vessel were continuously stirred and the internal temperature of the reaction vessel was maintained at 13. + -. 3 ℃ to allow the polymerization reaction to proceed for 3 hours. Then, the upper layer (aqueous layer) was removed using a decanter to obtain an organic layer.

A2L Erlenmeyer flask was used as a reaction vessel. In the reaction vessel, 500mL of ion-exchanged water was added, followed by addition of the organic layer. Then, 300g of chloroform and 6mL of acetic acid were added to the reaction vessel. The contents of the reaction vessel were stirred at room temperature (25 ℃) for 30 minutes. Then, the upper layer (aqueous layer) was removed using a decanter to obtain an organic layer. Then, 500mL of ion-exchanged water was used, and the organic layer was washed 8 times with a separatory funnel.

The organic layer after washing was taken out by a liquid separation operation. The organic layer was filtered to obtain a filtrate. A beaker with a capacity of 3L was charged with 1.5L of methanol. The organic layer was slowly added dropwise with stirring of methanol to obtain a precipitate. The precipitate was filtered off by filtration. The resulting precipitate was dried under vacuum at a temperature of 70 ℃ for 12 hours. As a result, a polyarylate Resin (Resin-5) was obtained. The yield of the polyarylate Resin (Resin-5) was 39.7g, and the yield was 88.1%.

[ production of polyarylate resins (Resin-1) to (Resin-4) ]

Polyarylate resins (Resin-1) to (Resin-4) were produced in the same manner as in the case of the polyarylate Resin (Resin-5) except that 9, 9-bis (3-methyl-4-hydroxyphenyl) fluorene was changed to an aromatic diol as a raw material for the polyarylate resins (Resin-1) to (Resin-4) and 2, 6-naphthalenedicarboxylic acid dichloride (2, 6-Naphthalene dicarboxylic acid dichloride) and 4, 4' -chloroformylphenyl ether were changed to a haloalkanoyl as a raw material for the polyarylate resins (Resin-1) to (Resin-4). In the production of polyarylate resins (Resin-1) to (Resin-4), the amount of the material of the raw material is the same as that in the production of the polyarylate Resin. The amount of the raw material substance refers to the total amount of the aromatic dicarboxylic acid and the amount of the aromatic diol substance.

[ production of polyarylate resins (Resin-6) to (Resin-7) ]

Polyarylate resins (Resin-6) to (Resin-7) were produced in the same manner as in the case of polyarylate Resin (Resin-5) except that 9, 9-bis (3-methyl-4-hydroxyphenyl) fluorene was changed to an aromatic diol as a raw material of polyarylate Resin ((Resin-6) to (Resin-7)) and 2, 6-naphthalenedicarboxylic acid dichloride (2, 6-Naphthalene dicarboxylic acid dichloride) and 4, 4' -chloroformylphenyl ether were changed to a haloalkanoyl as a raw material of polyarylate Resin ((Resin-6) to (Resin-7)). In the production of polyarylate resins (Resin-6) to (Resin-7), the amount of the material of the raw material is the same as that in the production of the polyarylate Resin. The amount of the raw material substance refers to the total amount of the aromatic dicarboxylic acid and the amount of the aromatic diol substance.

[ production of polyarylate resins (Resin-8) to (Resin-11) ]

In the production of polyarylate resins (Resin-8) to (Resin-11), polyarylate resins (Resin-8) to (Resin-11) were produced in the same manner as in the case of the polyarylate Resin (Resin-5) except that the amounts of the raw materials (aromatic dicarboxylic acid and aromatic diol) were changed to the amounts corresponding to the mole fractions in the chemical formulas (Resin-8) to (Resin-11).

Next, the polyarylate resins (Resin-1) to (Resin-11) were prepared by using a proton nuclear magnetic resonance spectrometer (300 MHz, manufactured by Nippon spectral Co., Ltd.)¹H-NMR spectrum was measured. Using CDCl₃As a solvent. Tetramethylsilane (TMS) was used as an internal standard. Among them, polyarylate Resin (Resin-5) is exemplified as a representative example. The chemical shift value of the polyarylate Resin (Resin-5) is shown below.

Polyarylate Resin (Resin-5):¹H-NMR(300MHz,CDCl₃)δ＝8.81(s，1H)，8.26(d，1H)，8.20(d，2H)，8.09(d，1H)，7.74-7.80(m，2H)，7.28-7.48(m，7H)，6.99-7.18(m，7H)，2.11-2.18(m，6H).

the polyarylate Resin (Resin-5) was confirmed to be obtained from the chemical shift value. The same applies to the other polyarylate resins (Resin-1) to (Resin-4) and (Resin-6) to (Resin-11), and it was confirmed that polyarylate resins (Resin-1) to (Resin-4) and (Resin-6) to (Resin-11) were obtained from the chemical shift values, respectively.

[ Binder resins (Resin-A) to (Resin-E) ]

Binder resins (Resin-A) to (Resin-E) were prepared. The binder resins (Resin-A) to (Resin-E) are represented by chemical formulas (Resin-A) to (Resin-E), respectively.

[ CHEM 18 ]

[ production of photoreceptor (A-1) ]

The production of the photoreceptor (a-1) according to example 1 will be described below.

5 parts by mass of a charge generating agent (CGM-1), 50 parts by mass of a triphenylamine derivative (HT1-1) as a hole transporting agent, 35 parts by mass of an electron transporting agent (ET1-1), 100 parts by mass of a polyarylate resin (R-1) as a binder resin, and 750 parts by mass of tetrahydrofuran as a solvent were placed in a vessel. The contents of the vessel were mixed using a ball mill for 50 hours to disperse the material in the solvent. Thus, a coating liquid for photosensitive layer was obtained. A photosensitive layer coating solution was applied to an aluminum drum-shaped support (diameter 30mm, total length 238.5mm) as a conductive substrate by a dip coating method. The coating liquid for the photosensitive layer applied was dried with hot air at 100 ℃ for 40 minutes. Thus, a monolayer type photosensitive layer (film thickness: 35 μm) was formed on the conductive substrate. As a result, photoreceptor (A-1) was obtained.

[ photoreceptors (A-2) to (A-22) and photoreceptors (B-1) to (B-7) ]

The photoreceptor was produced by the same method as the photoreceptor (A-1) except for the following points. The charge generating agent (CGM-1) described in Table 1 was used in place of the charge generating agent. The electron transport agent described in table 1 was used in place of the electron transport agent (ET 1-1). The hole-transporting agent described in Table 1 was used in place of the triphenylamine derivative (HT 1-1). The binder resin described in Table 1 was used in place of the polyarylate resin (R-1). Thus, photoreceptors (A-2) to (A-22) and photoreceptors (B-1) to (B-7) were obtained.

[ evaluation of photoreceptor Properties ]

(evaluation of sensitivity characteristics and transfer memory)

The photoreceptors (A-1) to (A-22) and (B-1) to (B-7) were evaluated for sensitivity characteristics and transfer memory.

The photoreceptor was mounted in an image forming apparatus ("FS-C5250 DN" manufactured by Kyowa office information systems Co., Ltd.). In this image forming apparatus, a contact type charging roller to which a dc voltage is applied serves as a charging section. In addition, this image forming apparatus employs an intermediate transfer system that directly transfers a toner image onto an intermediate transfer belt. The surface of the charging roller is provided with a charging sleeve which is formed by charging rubber mainly made of epichlorohydrin resin. The charging voltage of the charging portion was adjusted, and the charging potential (blank portion potential Vs) of the photoreceptor corresponding to the position of the developing portion at the time of non-exposure was set to + 570V. "Beijing porcelain office information system brand paper VM-A4" (size A4) sold by Beijing porcelain office information system corporation was used as a recording medium. The measurement environment was a temperature of 23 ℃ and a relative humidity of 50% RH.

Then, monochromatic light is extracted from the white light of the halogen lamp using a band-pass filter. The monochromatic light extracted has a wavelength of 780nm, a half-width of 20nm and a light energy of 0.5 muJ/cm²The laser beam of (1) is exposed to the monochromatic light, and the charged potential of the photoreceptor corresponding to the development position is measured. The measured surface potential of the exposure area is recorded as a light sensitivity potential V_L(unit: V). The measured surface potential of the unexposed area is recorded as a blank potential V₃(unit: V). In addition, light sensitivity potential V_LAnd a blank potential V₃Is measured in a state where the transfer bias is turned off. Then, a transfer bias of-2 kV was applied, and the surface potential of the non-exposed region (blank region) was measured in a state where the transfer bias was turned on. The surface potential of the obtained non-exposed region (blank region) was recorded as a blank region potential V₄. Using the formula "transfer memory potential Δ Vtc ═ V₄-V₃", based on the resulting V₃And V₄Thus, the transfer memory potential Δ Vtc (unit: V) is obtained.

The resultant light sensitivity potential V_LAnd the transfer memory potential Δ Vtc are shown in table 1. In addition, light sensitivity potential V_LThe smaller the value of (b) is, the more excellent the sensitivity characteristics of the photoreceptor are. The smaller the absolute value of the transfer memory potential Δ Vtc is, the better the occurrence of the transfer memory is suppressed.

(evaluation of image failure)

The image failure was evaluated for each of the photoreceptors (A-1) to (A-22) and (B-1) to (B-7).

The photoreceptor was mounted in an image forming apparatus ("FS-C5250 DN" manufactured by Kyowa office information systems Co., Ltd.). In this image forming apparatus, a contact type charging roller to which a dc voltage is applied serves as a charging section. In addition, this image forming apparatus employs an intermediate transfer system that directly transfers a toner image onto an intermediate transfer belt. The surface of the charging roller is provided with a charging sleeve which is formed by charging rubber mainly made of epichlorohydrin resin. The charging voltage of the charging portion was adjusted, and the charging potential (blank portion potential Vs) of the photoreceptor corresponding to the position of the developing portion at the time of non-exposure was set to + 570V. Laser light is used as light for exposure. The laser light is monochromatic light (wavelength 780nm, half-width 20nm and light energy 0.5. mu.J/cm) extracted from white light of a halogen lamp by using a band-pass filter²). "Beijing porcelain office information system brand paper VM-A4" (size A4) sold by Beijing porcelain office information system corporation was used as a recording medium. The measurement environment was a temperature of 23 ℃ and a relative humidity of 50% RH.

First, in order to stabilize the operation of the photoreceptor of the evaluation apparatus, a printing experiment was performed. The printing experiment was an experiment in which a pattern (image density 40%) was printed on a recording medium for 1 hour continuously. Then, an image for evaluation was created. The evaluation image will be described with reference to fig. 4. Fig. 4 shows an evaluation image 70. The evaluation image 70 includes an area 72 and an area 74. The region 72 corresponds to 1 turn of the image carrier. Region 72 contains image 76. The image 76 is composed of a square solid image (image density 100%). The region 74 corresponds to 1 turn of the image carrier. Region 74 contains image 78. Image 78 is composed of a full-scale halftone image (image density 12.5%). Image 76 of region 72 is formed first and image 78 of region 74 is formed thereafter. The image 76 corresponds to 1 turn of the photoreceptor, and the image 78 corresponds to the next 1 turn based on 1 turn of the image 76.

The evaluation image was visually observed, and the presence or absence of an image corresponding to the image 76 was confirmed in the area 74. The visual observation is observation with the naked eye (visual observation) or observation with a magnifying glass (magnification 10 times, TL-SL10K, manufactured by TRUSCO). The presence or absence of image failure (image sticking) due to transfer memory is checked. The presence or absence of image sticking was evaluated based on the following criteria. The evaluation results are shown in Table 1. Further, A to C were evaluated as passed.

(evaluation criteria of image sticking)

Evaluation a (very good): no image sticking corresponding to the image 76 was confirmed by both of the visual observation and the magnifying glass observation.

Evaluation B (good): no image sticking corresponding to the image 76 was confirmed by visual observation, and was slightly confirmed by observation with a magnifying glass.

Evaluation C (normal): an image afterimage corresponding to the image 76 was slightly observed by visual observation.

Evaluation D (poor): an image afterimage corresponding to the image 76 was clearly confirmed by visual observation.

Table 1 shows the structures and evaluation results of the photoreceptors (A-1) to (A-22) and the photoreceptors (B-1) to (B-7). In Table 1, the molecular weight of the polyarylate resin is the viscosity average molecular weight. In Table 1, HT-1 to HT-7 and HT-8 to HT-9 in the column "type of hole transport agent" represent triphenylamine derivatives (HT-1) to (HT-7) and hole transport agents (HT-8) to (HT-9), respectively. The ET1-1 to ET5-1 in the column "type of electron-transporting agent" respectively represent electron-transporting agents (ET1-1) to ET 5-1). In Table 1, R-1 to R-11 and R-A to R-E in the column "type of binder Resin" represent polyarylate resins (Resin-1) to (Resin-11) and binder resins (Resin-A) to (Resin-E), respectively. CGM-1 to CGM-2 in the column "kind of charge generating agent" represent charge generating agents (CGM-1 to CGM-2), respectively.

[ TABLE 1 ]

As shown in Table 1, the photosensitive layer of the photoreceptors (A-1) to (A-22) was a single-layer type photosensitive layer. The photosensitive layer contains a charge generator, a hole transporting agent, an electron transporting agent, and a binder resin. The hole-transporting agent is one of triphenylamine derivatives (HT-1) to (HT-7). The triphenylamine derivatives (HT-1) to (HT-7) are represented by the general formula (HT). The binder resin is one of polyarylate resins (R-1) to (R-11). The polyarylate resins (R-1) to (R-11) are all represented by the general formula (1). As shown in Table 1, the transfer memory potential Δ Vtc of the photoreceptors (A-1) to (A-22) was at least-20V and at most-9V, and the evaluation results of the images were A (excellent) or B (excellent).

As shown in Table 1, in the photoreceptors (B-1) to (B-7), the photosensitive layer was a single-layer type photosensitive layer. The photosensitive layer contains a charge generator, a hole transporting agent, an electron transporting agent, and a binder resin. Specifically, in the photoreceptors (B-1) to (B-2), the photosensitive layer contains a hole-transporting agent (HT-8) or (HT-9). The hole transport agents (HT-8) and (HT-9) are not triphenylamine derivatives represented by the general formula (HT). In the photoreceptors (B-3) to (B-7), the photosensitive layer contains one of the binder resins (Resin-A) to (Resin-E). None of the binder resins (Resin-A) to (Resin-E) is a polyarylate Resin represented by the general formula (1). As shown in Table 1, the transfer memory potential Δ Vtc was not less than-66V and not more than-40V in the photoreceptors (B-1) to (B-7), and the evaluation result of the image was D (poor).

As is clear from table 1, the photoreceptors (a-1) to (a-22)) according to the first embodiment have a smaller absolute value of transfer memory potential and have better image evaluation results than the photoreceptors (B-1) to (B-7). Therefore, the photoreceptor according to the present invention can obviously suppress the occurrence of transfer memory. The image forming apparatus according to the second embodiment (image forming apparatus having any of the photoreceptors (a-1) to (a-22)) has better image evaluation results than the image forming apparatus having any of the photoreceptors (B-1) to (B-7). Therefore, it is obvious that the image forming apparatus according to the present invention can suppress the occurrence of image failure.

Claims

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer,

the photosensitive layer is a monolayer type photosensitive layer,

the photosensitive layer contains a charge generator, a hole transporting agent, an electron transporting agent and a binder resin,

the hole-transporting agent contains a triphenylamine derivative,

characterized in that the triphenylamine derivative is represented by the general formula (HT),

the binder resin comprises a polyarylate resin,

the polyarylate resin is represented by the general formula (1),

[ CHEM 1 ]

In the general formula (1) described above,

Q¹、Q²、Q³and Q⁴Each independently represents a hydrogen atom or a methyl group,

r and s represent integers of 0 to 49 inclusive,

t and u represent integers of 1 to 50 inclusive,

r+s+t+u＝100，

r+t＝s+u，

r and t may be the same or different from each other,

s and u may be the same or different from each other,

x is a divalent group represented by formula (2A), formula (2B), formula (2C), formula (2D), formula (2E) or formula (2F),

y is a divalent group represented by formula (4A), formula (4B), formula (4C), formula (4D) or formula (4E),

x and Y are different from each other,

[ CHEM 2 ]

[ CHEM 3 ]

In the general formula (HT) in which,

R¹、R²and R³Independently of each other, represents a group selected from the group consisting of C1-C4 alkyl groups and C1-C4 alkoxy groups,

k. p and q are each independently an integer of 0 to 5 inclusive,

m1 and m2 each independently represents an integer of 1 to 3,

in the case where k represents an integer of 2 or more, a plurality of R¹May be the same as or different from each other,

in the case where p represents an integer of 2 or more, a number of R²May be the same as or different from each other,

in the case where q represents an integer of 2 or more, a plurality of R³May be the same or different from each other.

2. The electrophotographic photoreceptor according to claim 1,

the polyarylate Resin is represented by a chemical formula (Resin-1), a chemical formula (Resin-2), a chemical formula (Resin-3), a chemical formula (Resin-4), a chemical formula (Resin-5), a chemical formula (Resin-6), a chemical formula (Resin-7), a chemical formula (Resin-8), a chemical formula (Resin-9), a chemical formula (Resin-10) or a chemical formula (Resin-11),

[ CHEM 4 ]

[ CHEM 5 ]

[ CHEM 6 ]

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein in the general formula (1),

in the case where s represents 0, the first,

y is the divalent group represented by the general formula (4A), the general formula (4B) or the general formula (4C),

in the case where s represents an integer of 1 or more,

x is the divalent group represented by the general formula (2A), the general formula (2B) or the general formula (2C),

y is the divalent group represented by the general formula (4A), the general formula (4B) or the general formula (4C).

4. The electrophotographic photoreceptor according to claim 1 or 2,

in the general formula (HT) in which,

R¹represents the group selected from the group consisting of the C1-C4 alkoxy group and the C1-C4 alkyl group,

k represents a number of 1 or 2,

in the case where k represents 2, 2R¹May be the same as or different from each other,

p and q represent 0 and are each a group,

m1 and m2 represent 2 or 3.

5. The electrophotographic photoreceptor according to claim 1 or 2,

the hole transport agent is represented by formula (HT-1), formula (HT-2), formula (HT-3), formula (HT-4), formula (HT-5), formula (HT-6) or formula (HT-7),

[ CHEM 7 ]

6. The electrophotographic photoreceptor according to claim 1 or 2,

the electron transport agent is represented by a general formula (ET1), a general formula (ET2), a general formula (ET3), a general formula (ET4) or a general formula (ET5),

[ CHEM 8 ]

In the general formula (ET1),

R¹¹and R¹²Represents a C1-C6 alkyl group,

in the general formula (ET2),

R¹³、R¹⁴、R¹⁵and R¹⁶Represents a C1-C6 alkyl group,

in the general formula (ET3),

R¹⁷and R¹⁸Independently of one another, represents a C6-C14 aryl radical, the C6-C14 aryl radical may have 1 or several C1-C3 alkyl substituents,

in the general formula (ET4),

R¹⁹and R²⁰Represents a C1-C6 alkyl group,

R²¹represents a C6-C14 aryl group, the C6-C14 aryl group may have 1 or several halogen atoms,

in the general formula (ET5),

R²²、R²³、R²⁴and R²⁵Represents a C1-C6 alkyl group.

7. The electrophotographic photoreceptor according to claim 6,

the electron transport agent is represented by a chemical formula (ET1-1), a chemical formula (ET2-1), a chemical formula (ET3-1), a chemical formula (ET4-1) or a chemical formula (ET5-1),

[ CHEM 9 ]

8. The electrophotographic photoreceptor according to claim 1 or 2,

the charge generating agent is an X-type metal-free phthalocyanine pigment or a Y-type oxytitanium phthalocyanine pigment.

9. A kind of processing box is disclosed, which comprises a box body,

the electrophotographic photoreceptor according to claim 1 or 2.

10. An image forming apparatus includes:

an image bearing body;

a charging unit for charging a surface of the image carrier;

an exposure section that exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier;

a developing section that develops the electrostatic latent image into a toner image; and

a transfer section for transferring the toner image from the image bearing member to a transfer body,

it is characterized in that the preparation method is characterized in that,

the image bearing member is the electrophotographic photoreceptor according to claim 1 or 2,

the charging polarity of the charging section is a positive polarity,

the charging section charges the surface of the image carrier by applying a DC voltage while contacting the surface of the image carrier,

the transfer body is a recording medium,

the transfer section transfers the toner image to the transfer body when the surface of the image bearing member comes into contact with the transfer body.