JP2016191780A - Positive charging single layer type electrophotographic photoreceptor, process cartridge, and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive charging single layer type electrophotographic photoreceptor capable of suppressing occurrence of a transfer memory.SOLUTION: A positive charging single layer type electrophotographic photoreceptor is used as an image carrier in an image formation device including a charging part which is brought into contact with the image carrier to apply a DC voltage. The positive charging single layer type electrophotographic photoreceptor includes a photosensitive layer including at least a charge producing agent, a positive hole transportation agent, an electron transportation agent, and a binder resin. The positive hole transportation agent contains at least one kind among triarylamine derivative or the like represented by a following formula (1).SELECTED DRAWING: None

Description

  The present invention relates to a positively charged single layer type electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

  The electrophotographic photosensitive member is used in an electrophotographic image forming apparatus. In general, an electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer can contain a charge generating agent, a charge transport agent (for example, a hole transport agent and an electron transport agent), and a resin (binder resin) for binding them. An electrophotographic photoreceptor having such a photosensitive layer is called an electrophotographic organic photoreceptor. The photosensitive layer contains a charge transport agent and a charge generator, and can have both functions of charge generation and charge transport in the same layer. Such an electrophotographic organic photoreceptor is referred to as a single layer type electrophotographic photoreceptor.

  For example, an amine stilbene derivative is known as a hole transporting agent usable for an electrophotographic organic photoreceptor (Patent Document 1).

JP 2006-008670 A

  However, even if the amine stilbene derivative described in Patent Document 1 is used, it is difficult to suppress the generation of the transfer memory.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a positively charged single layer type electrophotographic photosensitive member that suppresses generation of a transfer memory. Another object of the present invention is to provide a process cartridge or an image forming apparatus that suppresses the occurrence of image defects by including such a positively charged single layer type electrophotographic photosensitive member.

  The positively charged single layer type electrophotographic photosensitive member of the present invention is used as the image carrier in an image forming apparatus provided with a charging unit that contacts the image carrier and applies a DC voltage. The positively charged single layer type electrophotographic photoreceptor includes a photosensitive layer containing at least a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin. The hole transport agent includes one or more of a triarylamine derivative represented by the following general formula (1) and a triarylamine derivative represented by the following general formula (2).

In the general formula (1), R ₁ and R ₂ may each independently have a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a substituent. It is selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent. k and l each independently represent an integer of 0 or more and 4 or less. m represents an integer of 1 to 3.

In the general formula (2), R ₃ and R ₄ may each independently have a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a substituent. It is selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent. p and q each independently represent an integer of 0 or more and 4 or less. r and s each independently represent an integer of 1 or more and 3 or less.

  The process cartridge of the present invention includes the positively charged single layer type electrophotographic photosensitive member described above.

  The image forming apparatus of the present invention includes the image carrier, the charging unit, an exposure unit, a developing unit, and a transfer unit. The charging unit charges the surface of the image carrier. 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 target. The charging unit applies a DC voltage in contact with the image carrier. The charging polarity of the charging unit is positive. The image carrier is the positively charged single layer type electrophotographic photosensitive member described above.

  According to the positively charged single layer type electrophotographic photosensitive member of the present invention, it is possible to suppress the generation of a transfer memory. In addition, according to the process cartridge or the image forming apparatus of the present invention, it is possible to suppress the occurrence of image defects (for example, image ghost) caused by the transfer memory by including the positively charged single layer type electrophotographic photosensitive member. be able to.

(A), (b), and (c) are schematic sectional views showing the structure of the positively charged single layer type electrophotographic photosensitive member according to the first embodiment. 2 is a ¹ H-NMR chart of a triarylamine derivative represented by the formula (HT-1). 2 is a ¹ H-NMR chart of a triarylamine derivative represented by the formula (HT-2). 2 is a ¹ H-NMR chart of a triarylamine derivative represented by the formula (HT-3). 2 is a ¹ H-NMR chart of a triarylamine derivative represented by the formula (HT-4). 2 is a ¹ H-NMR chart of a triarylamine derivative represented by the formula (HT-5). 2 is a ¹ H-NMR chart of a triarylamine derivative represented by the formula (HT-6). 2 is a ¹ H-NMR chart of a triarylamine derivative represented by the formula (HT-7). It is the schematic which shows the structure of the one aspect | mode of the image forming apparatus which concerns on 2nd embodiment. It is the schematic which shows the structure of another aspect of the image forming apparatus which concerns on 2nd embodiment.

  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, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

[First embodiment: positively charged single-layer type electrophotographic photosensitive member]
The first embodiment relates to a positively charged single layer type electrophotographic photosensitive member (hereinafter sometimes referred to as “photosensitive member”). Hereinafter, the photoreceptor 1 of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the structure of the photoreceptor 1 according to this embodiment.

  The photoreceptor 1 includes a photosensitive layer 3 as shown in FIG. The photosensitive layer 3 contains at least a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The photosensitive layer 3 contains at least one of a triarylamine derivative represented by the general formula (1) and a triarylamine derivative represented by the general formula (2) as a hole transport agent. Hereinafter, the triarylamine derivatives represented by the general formulas (1) and (2) may be referred to as triarylamine derivatives (1) and (2), respectively.

  The photoreceptor 1 can suppress the generation of a transfer memory. The reason is presumed as follows.

For convenience, the transfer memory will be described first. In electrophotographic image formation, for example, an image forming process including the following steps 1) to 4) is performed.
1) a charging step for 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 as a toner image, and 4) a transferring step of transferring the formed toner image from the image carrier to the transfer target.

  However, in such an image forming process, since the image carrier is rotated and used, a transfer memory may be generated due to the transfer process. Specifically, it is as follows. In the charging process, the surface of the image carrier is uniformly charged to a constant positive potential. Subsequently, through an exposure process and a development process, in the transfer process, a transfer bias having a polarity opposite to that of charging (negative polarity) is applied to the image carrier via the transfer target. Specifically, the potential of the non-exposure area (non-image area) on the surface of the image carrier may be greatly lowered due to the influence of the applied reverse polarity transfer bias, and the lowered state may be maintained. Under the influence of this potential drop, the non-exposed area is hardly charged to a desired positive potential in the next charging step. On the other hand, even when a transfer bias is applied, the toner is attached to the exposed area, and therefore, it is difficult to apply the transfer bias directly to the surface of the photosensitive member, so that the potential of the exposed area (image area) is unlikely to decrease. . For this reason, the exposure area is easily charged to a desired positive potential in the charging process of the next circumference. As a result, the charged potential differs between the exposed area and the non-exposed area, and it may be difficult to uniformly charge the surface of the image carrier to a constant positive potential. As described above, a phenomenon in which the charging ability in the non-exposed area is lowered due to the influence of transfer in the image forming process (image forming process) on the front periphery of the photoreceptor is referred to as a transfer memory.

  However, as already described, the photoreceptor 1 of this embodiment includes one or more of a triarylamine derivative (1) and a triarylamine derivative (2) as a hole transport agent. Each of the triarylamine derivatives (1) and (2) has a double bond between two nitrogen atoms. The photosensitive layer 3 containing at least one of the triarylamine derivatives (1) and (2) having such a structure tends to have excellent electrical characteristics.

  Furthermore, the triarylamine derivatives (1) and (2) tend to have excellent solubility in a solvent and compatibility with a binder resin by having such a structure. For this reason, it is considered that the triarylamine derivatives (1) and (2), which are hole transport agents, can be uniformly dispersed in the photosensitive layer 3. The photosensitive layer 3 in which one or more of the triarylamine derivatives (1) and (2), which are hole transport agents, are uniformly dispersed has not only excellent hole transport ability but also electrons in the electron transport agent. There is a tendency that the electron transport ability is hardly inhibited and the electron transport ability is also excellent.

  As a result, even when a transfer bias having a reverse polarity is applied to the photoreceptor 1, the electrons in the photosensitive layer 3 move quickly and the electrons are unlikely to remain in the photosensitive layer 3. Therefore, it is considered that the photoreceptor 1 can suppress the generation of the transfer memory.

  Next, the photoreceptor 1 will be described. 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. Alternatively, for example, as shown in FIG. 1B, an intermediate layer 4 may be appropriately provided between the conductive substrate 2 and the photosensitive layer 3. Further, as shown in FIGS. 1A and 1B, the photosensitive layer 3 may be exposed as the outermost layer. Alternatively, as shown in FIG. 1C, a protective layer 5 may be appropriately provided on the photosensitive layer 3.

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

  Hereinafter, the conductive substrate 2 and the photosensitive layer 3 will be described. Furthermore, the manufacturing method of the intermediate | middle layer 4 and the photoreceptor 1 is demonstrated.

[1. Conductive substrate]
The conductive substrate 2 is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor 1. As the conductive substrate 2, a conductive substrate formed of a material having at least a surface portion having conductivity can be used. Examples of the conductive substrate 2 include a conductive substrate made of a conductive material; or a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). Among these materials having conductivity, aluminum or an aluminum alloy is preferable because charge transfer 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. For example, a sheet-like conductive substrate or a drum-shaped conductive substrate can be used. Further, the thickness of the conductive substrate 2 can be appropriately selected according to the shape of the conductive substrate 2.

[2. Photosensitive layer]
As already described above, the photosensitive layer 3 contains a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin in the same layer. Hereinafter, the charge generator, hole transport agent, electron transport agent, and binder resin contained in the photosensitive layer 3 will be described. Further, additives that may be included in the photosensitive layer 3 as necessary will be described.

[2-1. Charge generator]
The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. 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, cyanine pigments , Powders of inorganic photoconductive materials (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon), pyrylium salts, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples thereof include pyrazoline pigments and quinacridone pigments. Examples of the phthalocyanine pigment include metal-free phthalocyanine represented by the following formula (H ₂ Pc) or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the following formula (TiOPc), or phthalocyanine coordinated with a metal other than titanium oxide (for example, V-type hydroxygallium phthalocyanine). Metal-free phthalocyanine or metal phthalocyanine may be used after derivatization.

  The metal-free phthalocyanine may be a crystal. Examples of the metal-free phthalocyanine crystal include X-type metal-free phthalocyanine. The titanyl phthalocyanine may be a crystal. Examples of the titanyl phthalocyanine crystal include α-type titanyl phthalocyanine, β-type titanyl phthalocyanine, and Y-type titanyl phthalocyanine.

  Of these charge generators, phthalocyanine pigments are preferable, and X-type 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.

  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. Furthermore, for example, in a digital optical system image forming apparatus (for example, a laser beam printer or facsimile using a light source such as a semiconductor laser), it is preferable to use a photoconductor having sensitivity in a wavelength region of 700 nm or more. Therefore, for example, phthalocyanine pigments (for example, X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine) are preferably used. The crystal shape (for example, α-type, β-type, or Y-type) of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

  For a photoreceptor applied to an image forming apparatus using a short-wavelength laser light source (for example, a laser light source having a wavelength of about 350 nm to 550 nm), an santhrone pigment or a perylene pigment is suitable as a charge generator. Used for.

  The content of the charge generating agent is preferably 0.1 parts by weight or more and 50 parts by weight or less, and 0.5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the binder resin in the photosensitive layer 3. Is more preferable.

[2-2. Hole transport agent]
The photosensitive layer 3 contains one or more of triarylamine derivatives (1) and (2) as a hole transport agent.

In general formula (1), R ₁ and R ₂ are each independently a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or an optionally substituted carbon. It is selected from the group consisting of an alkoxy group having 1 to 6 atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent. k and l each independently represent an integer of 0 or more and 4 or less. m represents an integer of 1 to 3.

In general formula (2), R ₃ and R ₄ are each independently a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or an optionally substituted carbon. It is selected from the group consisting of an alkoxy group having 1 to 6 atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent. p and q each independently represent an integer of 0 or more and 4 or less. r and s each independently represent an integer of 1 or more and 3 or less.

In the general formulas (1) and (2), the halogen atom represented by R ₁ , R ₂ , R ₃ , and R ₄ is, for example, fluorine, chlorine, or bromine.

In general formulas (1) and (2), R ₁ , R ₂ , R ₃ , and R ₄ represent an alkyl group having 1 to 6 carbon atoms, which is a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. , S-butyl group, n-butyl group, t-butyl group, n-pentyl group, isopentyl group, neopentyl group, or hexyl group.

In the general formulas (1) and (2), an alkoxy group having 1 to 6 carbon atoms represented by R ₁ , R ₂ , R ₃ , and R ₄ is a methoxy group, an ethoxy group, an n-propoxy group, or an isopropoxy group. Group, n-butoxy group, s-butoxy group, t-butoxy group, n-pentyloxy group, isopentyloxy group, neopentyloxy group, or hexyloxy group.

In general formulas (1) and (2), the aryl group having 6 to 12 carbon atoms represented by R ₁ , R ₂ , R ₃ , and R ₄ is a phenyl group or a naphthyl group.

The alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, or the aryl group having 6 to 12 carbon atoms may have a substituent. When R ₁ , R ₂ , R ₃ , and R ₄ are an alkyl group having 1 to 6 carbon atoms having a substituent or an alkoxy group having 1 to 6 carbon atoms having a substituent, Is, for example, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. When R ₁ , R ₂ , R ₃ , and R ₄ are an aryl group having 6 to 12 carbon atoms having a substituent, examples of the substituent include an alkyl group having 1 to 6 carbon atoms, carbon Examples thereof include an alkoxy group having 1 to 6 atoms or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, or the aryl group having 6 to 12 carbon atoms as the substituent include, for example, general formulas (1) and (2 R ₁ , R ₂ , R ₃ , and R _{4 in the} formula (1) represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. The same group is mentioned.

In general formulas (1) and (2), the substitution positions of R ₁ , R ₂ , R ₃ , and R ₄ are not particularly limited. For example, R ₁ may be located at any of the ortho position (o position), meta position (m position), and para position (p position) with respect to the nitrogen atom to which the phenyl group having R ₁ is bonded. it can.

In the general formulas (1) and (2), when k, l, p, and q are each an integer of 2 or more, a plurality of R ₁ , a plurality of R ₂ , a plurality of R ₃ , And a plurality of R ₄ may be the same or different. Hereinafter, it demonstrates in detail, referring the following general formula (1-1) and (2-1). General formulas (1-1) and (2-1) correspond to general formulas (1) and (2), respectively.

In general formula (1-1), R _1a , R _1b , R _1c , R _1d , R _1e , R _2a , R _2b , R _2c , R _2d and R _2e are each independently a hydrogen atom, halogen An atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, and a carbon which may have a substituent It is selected from the group consisting of aryl groups having 6 to 12 atoms. However, k groups selected from R _1a , R _1b , R _1c , R _1d , and R _1e are not hydrogen atoms. Moreover, 1 group selected from R _{< 2a >} , R _{< 2b >} , R _{< 2c>} , R _<2d> , and R _<2e> is not a hydrogen atom. k and l each independently represent an integer of 0 or more and 4 or less. m represents an integer of 1 to 3.

In general formula (2-1), R _3a , R _3b , R _3c , R _3d , R _3e , R _4a , R _4b , R _4c , R _4d and R _4e are each independently a hydrogen atom, halogen An atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, and a carbon which may have a substituent It is selected from the group consisting of aryl groups having 6 to 12 atoms. However, p groups selected from R _3a , R _3b , R _3c , R _3d , and R _3e are not hydrogen atoms. Further, q groups selected from R _4a , R _4b , R _4c , R _4d and R _4e are not hydrogen atoms. p and q each independently represent an integer of 0 or more and 4 or less. r and s each independently represent an integer of 1 or more and 3 or less.

For example, in the general formula (1), when k is an integer of 2 or more, a plurality of R ₁ existing in the same aromatic ring may be the same or different, which means the following. R _1a , R _1b , R _1c , R _1d , and R _1e present in the aromatic ring (A) of the general formula (1-1) may be the same group or different groups. . However, the R _1a present in the aromatic ring (A), and R _1a present in the aromatic ring (B) are the same group. R _1b present in the aromatic ring _{(A), R 1c, R} 1d, and the R _1e, R _1b present in the aromatic ring _{(B), R 1c, R} 1d, and both R _1e, each is the same group .

In the general formula (1), when l is an integer of 2 or more, R _2a , R _2b , R _2c , R _2d and R _2e present in the aromatic ring (C) of the general formula (1-1); The relationship between R _2a , R _2b , R _2c , R _2d , and R _2e present in the aromatic ring (D) is as follows: R _1a , R _1b , present in the aromatic ring (A) of the general formula (1-1) R _1c, is similar to the relationship between R _1d, and R _1e, R _1a existing in the aromatic ring _{(B), R 1b, R} 1c, and R _1d, and R _1e.

In the general formula (2), when p is an integer of 2 or more, R _3a , R _3b , R _3c , R _3d and R _3e present in the aromatic ring (E) of the general formula (2-1); The relationship between R _3a , R _3b , R _3c , R _3d , and R _3e present in the aromatic ring (F) is as follows: R _1a , R _1b , present in the aromatic ring (A) of the general formula (1-1) R _1c, is similar to the relationship between R _1d, and R _1e, R _1a existing in the aromatic ring _{(B), R 1b, R} 1c, and R _1d, and R _1e.

In the general formula (2), when q is an integer of 2 or more, R _4a , R _4b , R _4c , R _4d and R _4e present in the aromatic ring (G) of the general formula (2-1); The relationship between R _4a , R _4b , R _4c , R _4d , and R _4e present in the aromatic ring (H) is as follows: R _1a , R _1b , present in the aromatic ring (A) of the general formula (1-1) R _1c, is similar to the relationship between R _1d, and R _1e, R _1a existing in the aromatic ring _{(B), R 1b, R} 1c, and R _1d, and R _1e.

  The case where k, l, p, and q are integers of 2 or more in the general formulas (1) and (2) has been described above. Next, general formulas (1) and (2) will be described.

From the viewpoint of suppressing the generation of transfer memory, in general formulas (1) and (2), R ₁ , R ₂ , R ₃ , and R ₄ are each independently an alkyl group having 1 to 6 carbon atoms. It is preferable that it is a methyl group or an ethyl group.

From the viewpoint of suppressing the generation of the transfer memory, in general formula (1), k is preferably 0 and 1 is preferably 1. When l is 1, R ₂ is preferably present in the para position with respect to the nitrogen atom to which the phenyl group having R ₂ is bonded.

  From the viewpoint of suppressing the occurrence of transfer memory, in general formula (2), p is preferably 0 or 1, and q is preferably 1 or 2.

When p is 1, R ₃ is preferably present in the para position with respect to the alkenyl group to which the phenyl group having R ₃ is bonded. When q is 1, R ₄ is preferably present in the para position with respect to the nitrogen atom to which the phenyl group having R ₄ is bonded. When q is 2, it is preferable that any two R ₄ existing in the same aromatic ring are present in the ortho position with respect to the nitrogen atom to which the phenyl group having R ₄ is bonded. Two R ₄ existing in the same aromatic ring may be the same or different.

Two R ₄ existing in the same aromatic ring may be the same or different means the following. In Formula (2-1), two groups out of R _4a , R _4b , R _4c , R _4d , and R _4e present in the aromatic ring (G) may have a halogen atom or a substituent. A good alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, and an aryl group having 6 to 12 carbon atoms which may have a substituent The same or different groups selected from the group consisting of Groups other than two of R _4a , R _4b , R _4c , R _4d and R _4e present in the aromatic ring (G) are hydrogen atoms. However, the R _4a present in the aromatic ring (G), and R _4a present in the aromatic ring (H) is the same group. R _4b present on the aromatic ring _{(G), R 4c, R} 4d, and the R _4e, R _4b present on the aromatic ring _{(H), R 4c, R} 4d, and both R _4e, each is the same group .

From the viewpoint of suppressing the generation of transfer memory, in general formula (2), r is preferably 1 or 2, and s is preferably 2 or 3. The number s of double bonds existing in the alkenyl group to which the phenyl group having R ₃ is bonded is the same as the number r of double bonds existing in the bond between two nitrogen atoms, or from the number r of double bonds Is larger, the electrical characteristics of the photosensitive layer 3 are further improved, and the generation of the transfer memory can be further suppressed.

  From the viewpoint of suppressing the generation of transfer memory, it is preferable to use the triarylamine derivative (2) among the triarylamine derivatives (1) and (2). When the photosensitive layer 3 contains one or more of the triarylamine derivatives (2), the generation of the transfer memory tends to be further suppressed.

  The photosensitive layer 3 can contain two or more of the triarylamine derivatives (1) and (2) as a hole transport agent. When two or more of the triarylamine derivatives (1) and (2) are included, one or more of the triarylamine derivatives (1) and one or more of the triarylamine derivatives (2) And may be used in combination. Alternatively, two or more of the triarylamine derivatives (1) may be used. Alternatively, two or more of the triarylamine derivatives (2) may be used.

  In addition to one or more of the triarylamine derivatives (1) and (2), another hole transporting agent other than the triarylamine derivatives (1) and (2) may be used in combination. Another hole transport agent can be appropriately selected from known hole transport agents.

  The total content of the hole transport 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 in the photosensitive layer 3. preferable.

  Specific examples of the triarylamine derivatives (1) and (2) include triarylamine derivatives represented by the formulas (HT-1) to (HT-9). Hereinafter, the triarylamine derivatives represented by the formulas (HT-1) to (HT-9) may be referred to as triarylamine derivatives (HT-1) to (HT-9), respectively.

Of the triarylamine derivatives (HT-1) to (HT-9), ¹ H-NMR charts of the triarylamine derivatives (HT-1) to (HT-7) are shown in FIGS.

  The triarylamine derivatives (1) and (2) can be produced, for example, by a production method including the following steps. In detail, the manufacturing method of a triarylamine derivative (1) includes the process of performing reaction represented by Reaction formula (R-1) and (R-2).

  Moreover, the manufacturing method of a triarylamine derivative (2) includes the process of performing reaction represented by Reaction formula (R-3) and (R-4).

In the reaction formulas (R-1) to (R-4), R ₁ , R ₂ , R ₃ and R ₄ are each independently a halogen atom or a carbon atom having 1 to 6 carbon atoms which may have a substituent. Selected from the group consisting of the following alkyl groups, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, and an aryl group having 6 to 12 carbon atoms which may have a substituent. . k, l, p and q each independently represent an integer of 0 or more and 4 or less. m, r, and s represent an integer of 1 to 3. X represents a halogen atom such as chlorine or fluorine.

  The reactions represented by the reaction formulas (R-1) to (R-4) are coupling reactions.

  In the reaction represented by the reaction formula (R-1), the compound represented by the general formula (3) (aniline derivative) and the compound represented by the general formula (4) (benzene derivative) are reacted, A compound represented by the general formula (5) (an intermediate of the triarylamine derivative (1). Hereinafter, it may be referred to as an “intermediate represented by the general formula (5)”) is obtained.

  Regarding the reaction ratio between the aniline derivative and the benzene derivative, the molar ratio of (aniline derivative) / (benzene derivative) is preferably 1/2 or more and 2/1 or less. When the reaction ratio of the benzene derivative is too small, the yield of the intermediate represented by the general formula (5) may be excessively lowered. On the other hand, if the reaction ratio of the benzene derivative is excessive, the excess benzene derivative may remain excessively unreacted.

  Regarding the reaction represented by the reaction formula (R-1), the reaction temperature is preferably 80 ° C. or higher and 140 ° C. or lower. The reaction time is preferably 2 hours or more and 10 hours or less.

  In the reaction represented by the reaction formula (R-1), it is preferable to use a palladium compound as a catalyst. By using a palladium compound as a catalyst, the activation energy is effectively reduced in the reaction represented by the reaction formula (R-1). As a result, the yield of the intermediate represented by the general formula (5) can be improved.

  Specific examples of the palladium compound include tetravalent palladium compounds, divalent palladium compounds, and other palladium compounds. Examples of the tetravalent palladium compounds include sodium hexachloropalladium (IV) tetrahydrate or potassium hexachloropalladium (IV) tetrahydrate. Examples of the divalent palladium compounds include palladium chloride (II), palladium bromide (II), palladium acetate (II), palladium acetyl acetate (II), dichlorobis (benzonitrile) palladium (II), dichlorobis (triphenyl). Phosphine) palladium (II), dichlorotetramine palladium (II), or dichloro (cycloocta-1,5-diene) palladium (II). Examples of other palladium compounds include tris (dibenzylideneacetone) dipalladium (0), tris (dibenzylideneacetone) dipalladium chloroform complex (0), and tetrakis (triphenylphosphine) palladium (0). Moreover, a palladium compound may be used individually by 1 type, and may be used in combination of 2 or more type.

  The addition amount of the palladium compound is preferably 0.0005 mol or more and 20 mol or less, and 0.001 mol or more and 1 mol or less with respect to 1 mol of the aniline derivative represented by the general formula (3). More preferred.

  In addition, the reaction represented by the reaction formula (R-1) is preferably performed in the presence of a base.

  By performing the reaction represented by the reaction formula (R-1) in the presence of a base, the hydrogen halide generated in the reaction system is quickly neutralized and the catalytic activity is improved. As a result, the yield of the intermediate represented by the general formula (5) can be improved.

  The base may be an inorganic base or an organic base. Examples of the organic base include, but are not limited to, alkali metal alkoxides (sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium tert-butoxide, sodium tert-butoxide, or potassium tert-butoxide. ) Is preferred, and sodium-tert-butoxide is more preferred. In addition, examples of the inorganic base include tripotassium phosphate and cesium fluoride.

  When 0.005 mol of the palladium compound is added to 1 mol of the aniline derivative represented by the general formula (3), the addition amount of the base is preferably 1 mol or more and 10 mol or less, and preferably 1 mol or more and 5 mol. The following is more preferable.

  The reaction represented by the reaction formula (R-1) can be carried out in a solvent. Examples of the solvent include xylene (o-, m-, or p-), toluene, tetrahydrofuran, or dimethylformamide.

Next, the reaction represented by the reaction formula (R-2) will be described.
In the reaction formula (R-2), the intermediate represented by the general formula (5) is reacted with the compound represented by the general formula (6) (stilbene derivative) to obtain a triarylamine derivative (1). Get.

  In the reaction represented by the reaction formula (R-2), the reaction ratio between the intermediate represented by the general formula (5) and the stilbene derivative represented by the general formula (6) is (intermediate) / (stilbene). The molar ratio of the derivative) is preferably from 1 / 2.5 to 1/1. If the reaction ratio of the stilbene derivative is too small, the yield of the triarylamine derivative (1) may be excessively lowered. On the other hand, if the reaction ratio of the stilbene derivative is excessive, unreacted stilbene derivative remains excessively after the reaction, and purification of the triarylamine derivative (1) may be difficult.

  Regarding the reaction represented by the reaction formula (R-2), the reaction temperature is preferably 80 ° C. or higher and 140 ° C. or lower. The reaction time is preferably 2 hours or more and 10 hours or less.

  The reaction represented by the reaction formula (R-2) can be carried out in the presence of a catalyst. Examples of the catalyst used include sodium alkoxide (sodium methoxide or sodium ethoxide), metal hydride (sodium hydride or potassium hydride), or metal salt (eg, n-butyllithium). These catalysts may be used individually by 1 type, and may be used in combination of 2 or more type. The addition amount of such a catalyst is preferably 1 mol or more and 2 mol or less with respect to 1 mol in total of the stilbene derivative represented by the general formula (6). If the addition amount of such a catalyst is too small, the reactivity between the intermediate represented by the general formula (5) and the stilbene derivative represented by the general formula (6) may be significantly lowered. On the other hand, if the reaction amount of such a catalyst is excessive, it may be difficult to control the reaction.

  In the reaction represented by the reaction formula (R-2), it is preferable to use a palladium compound as a catalyst. By using a palladium compound as a catalyst, the activation energy in the reaction represented by the reaction formula (R-2) is effectively reduced. As a result, the yield of the triarylamine derivative (1) can be improved.

  Specific examples of the palladium compound include tetravalent palladium compounds, divalent palladium compounds, and other palladium compounds. Examples of the tetravalent palladium compounds include sodium hexachloropalladium (IV) tetrahydrate or potassium hexachloropalladium (IV) tetrahydrate. Examples of the divalent palladium compounds include palladium chloride (II), palladium bromide (II), palladium acetate (II), palladium acetyl acetate (II), dichlorobis (benzonitrile) palladium (II), dichlorobis (triphenyl). Phosphine) palladium (II), dichlorotetramine palladium (II), or dichloro (cycloocta-1,5-diene) palladium (II). Examples of other palladium compounds include tris (dibenzylideneacetone) dipalladium (0), tris (dibenzylideneacetone) dipalladium chloroform complex (0), and tetrakis (triphenylphosphine) palladium (0). . Moreover, a palladium compound may be used individually by 1 type, and may be used in combination of 2 or more type.

  The addition amount of the palladium compound is preferably 0.0005 mol or more and 20 mol or less, and 0.001 mol or more and 1 mol or less with respect to 1 mol of the intermediate represented by the general formula (5). More preferred.

  In addition, the reaction represented by the reaction formula (R-2) is preferably performed in the presence of a base.

  By performing the reaction represented by the reaction formula (R-2) in the presence of a base, the hydrogen halide generated in the reaction system is quickly neutralized and the catalytic activity is improved. As a result, the yield of the triarylamine derivative (1) can be improved.

  The base may be an inorganic base or an organic base. Examples of the organic base include, but are not limited to, alkali metal alkoxides (sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium tert-butoxide, sodium tert-butoxide, or potassium tert-butoxide. ) Is preferred, and sodium-tert-butoxide is more preferred. In addition, examples of the inorganic base include tripotassium phosphate and cesium fluoride.

  When 0.005 mol of the palladium compound is added to 1 mol of the intermediate represented by the general formula (5), the addition amount of the base is preferably 1 mol or more and 10 mol or less, and preferably 1 mol or more and 5 mol. The following is more preferable.

  The reaction represented by the reaction formula (R-2) is performed, for example, in a solvent. Examples of the solvent include xylene (o-, m-, or p-), toluene, tetrahydrofuran, or dimethylformamide.

  Next, a method for producing the triarylamine derivative (2) will be described. The manufacturing method of a triarylamine derivative (2) includes the process of performing reaction represented by Reaction formula (R-3) and Reaction formula (R-4), for example.

  In the reaction represented by the reaction formula (R-3), the compound represented by the general formula (3) (aniline derivative) and the compound represented by the general formula (7) (benzene derivative) are reacted, A compound represented by the general formula (8) (an intermediate of the triarylamine derivative (2). Hereinafter, it may be referred to as an “intermediate represented by the general formula (8)”) is obtained.

  Regarding the reaction ratio between the aniline derivative and the benzene derivative, the molar ratio of (aniline derivative) / (benzene derivative) is preferably 1/2 or more and 2/1 or less. If the reaction ratio of the benzene derivative is too small, the yield of the intermediate represented by the general formula (8) may be excessively lowered. On the other hand, if the reaction ratio of the benzene derivative is excessive, the excess benzene derivative may remain excessively unreacted.

  Regarding the reaction represented by the reaction formula (R-3), the reaction temperature is preferably 80 ° C. or higher and 140 ° C. or lower. The reaction time is preferably 2 hours or more and 10 hours or less.

  In the reaction represented by the reaction formula (R-3), it is preferable to use a palladium compound as a catalyst. By using a palladium compound as a catalyst, the activation energy in the reaction represented by the reaction formula (R-3) is effectively reduced. As a result, the yield of the intermediate represented by the general formula (8) can be improved.

  Specific examples of the palladium compound include tetravalent palladium compounds, divalent palladium compounds, and other palladium compounds. Examples of the tetravalent palladium compounds include sodium hexachloropalladium (IV) tetrahydrate or potassium hexachloropalladium (IV) tetrahydrate. Examples of the divalent palladium compounds include palladium chloride (II), palladium bromide (II), palladium acetate (II), palladium acetyl acetate (II), dichlorobis (benzonitrile) palladium (II), dichlorobis (triphenyl). Phosphine) palladium (II), dichlorotetramine palladium (II), or dichloro (cycloocta-1,5-diene) palladium (II). Examples of other palladium compounds include tris (dibenzylideneacetone) dipalladium (0), tris (dibenzylideneacetone) dipalladium chloroform complex (0), and tetrakis (triphenylphosphine) palladium (0). Moreover, a palladium compound may be used individually by 1 type, and may be used in combination of 2 or more type.

  The addition amount of the palladium compound is preferably 0.0005 mol or more and 20 mol or less, and 0.001 mol or more and 1 mol or less with respect to 1 mol of the aniline derivative represented by the general formula (3). More preferred.

  In addition, the reaction represented by the reaction formula (R-3) is preferably performed in the presence of a base.

  By performing the reaction represented by the reaction formula (R-3) in the presence of a base, the hydrogen halide generated in the reaction system is quickly neutralized and the catalytic activity is improved. As a result, the yield of the intermediate represented by the general formula (8) can be improved.

  The base may be an inorganic base or an organic base. Examples of the organic base include, but are not limited to, alkali metal alkoxides (sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium tert-butoxide, sodium tert-butoxide, or potassium tert-butoxide. ) Is preferred, and sodium-tert-butoxide is more preferred. In addition, examples of the inorganic base include tripotassium phosphate and cesium fluoride.

  When 0.005 mol of the palladium compound is added to 1 mol of the stilbene derivative represented by the general formula (7), the addition amount of the base is preferably 1 mol or more and 10 mol or less, preferably 1 mol or more and 5 mol The following is more preferable.

  The reaction represented by the reaction formula (R-3) can be carried out in a solvent. Examples of the solvent include xylene (o-, m-, or p-), toluene, tetrahydrofuran, or dimethylformamide.

Next, the reaction represented by the reaction formula (R-4) will be described.
In the reaction formula (R-4), the intermediate represented by the general formula (8) is reacted with the stilbene derivative represented by the general formula (6) to obtain the triarylamine derivative (2).

  In the reaction represented by the reaction formula (R-4), the reaction ratio between the intermediate represented by the general formula (8) and the stilbene derivative represented by the general formula (6) is (intermediate) / (stilbene). The molar ratio of the derivative) is preferably from 1 / 2.5 to 1/1. If the reaction ratio of the stilbene derivative is too small, the yield of the triarylamine derivative (2) may be excessively lowered. On the other hand, if the reaction ratio of the stilbene derivative is excessive, unreacted stilbene derivative remains excessively after the reaction, and purification of the triarylamine derivative (2) may be difficult.

  Regarding the reaction represented by the reaction formula (R-4), the reaction temperature is preferably 80 ° C. or higher and 140 ° C. or lower. The reaction time is preferably 2 hours or more and 10 hours or less.

  The reaction represented by the reaction formula (R-4) can be carried out in the presence of a catalyst. Examples of the catalyst used include sodium alkoxide (sodium methoxide or sodium ethoxide), metal hydride (sodium hydride or potassium hydride), or metal salt (eg, n-butyllithium). These catalysts may be used individually by 1 type, and may be used in combination of 2 or more type. The addition amount of such a catalyst is preferably 1 mol or more and 2 mol or less with respect to 1 mol in total of the stilbene derivative represented by the general formula (6). If the amount of such a catalyst added is too small, the reactivity between the intermediate represented by the general formula (8) and the stilbene derivative represented by the general formula (6) may be significantly reduced. On the other hand, if the reaction amount of such a catalyst is excessive, it may be difficult to control the reaction.

  In the reaction represented by the reaction formula (R-4), it is preferable to use a palladium compound as a catalyst. By using a palladium compound as a catalyst, the activation energy in the reaction represented by the reaction formula (R-4) is effectively reduced. As a result, the yield of the triarylamine derivative (2) can be improved.

  Specific examples of the palladium compound include tetravalent palladium compounds, divalent palladium compounds, and other palladium compounds. Examples of the tetravalent palladium compounds include sodium hexachloropalladium (IV) tetrahydrate or potassium hexachloropalladium (IV) tetrahydrate. Examples of the divalent palladium compounds include palladium chloride (II), palladium bromide (II), palladium acetate (II), palladium acetyl acetate (II), dichlorobis (benzonitrile) palladium (II), dichlorobis (tri Phenylphosphine) palladium (II), dichlorotetraminepalladium (II), or dichloro (cycloocta-1,5-diene) palladium (II). Examples of other palladium compounds include tris (dibenzylideneacetone) dipalladium (0), tris (dibenzylideneacetone) dipalladium chloroform complex (0), and tetrakis (triphenylphosphine) palladium (0). . Moreover, a palladium compound may be used individually by 1 type, and may be used in combination of 2 or more type.

  The addition amount of the palladium compound is preferably 0.0005 mol or more and 20 mol or less, and 0.001 mol or more and 1 mol or less with respect to 1 mol of the intermediate represented by the general formula (8). More preferred.

  In addition, the reaction represented by the reaction formula (R-4) is preferably carried out in the presence of a base.

  By performing the reaction represented by the reaction formula (R-4) in the presence of a base, the hydrogen halide generated in the reaction system is quickly neutralized and the catalytic activity is improved. As a result, the yield of the triarylamine derivative (2) can be improved.

  The base may be an inorganic base or an organic base. Examples of the organic base include, but are not limited to, alkali metal alkoxides (sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium tert-butoxide, sodium tert-butoxide, or potassium tert-butoxide. ) Is preferred, and sodium-tert-butoxide is more preferred. In addition, examples of the inorganic base include tripotassium phosphate and cesium fluoride.

  When 0.005 mol of the palladium compound is added to 1 mol of the intermediate represented by the general formula (8), the addition amount of the base is preferably 1 mol or more and 10 mol or less, and preferably 1 mol or more and 5 mol. The following is more preferable.

  The reaction represented by the reaction formula (R-4) is performed, for example, in a solvent. Examples of the solvent include xylene (o-, m-, or p-), toluene, tetrahydrofuran, or dimethylformamide.

  In the production method of the triarylamine derivatives (1) and (2), the reaction represented by the reaction formulas (R-1) and (R-2), or the reaction formulas (R-3) and (R-4) In addition to the step of performing the reaction represented, an appropriate step may be included as necessary.

[2-3. Electron transport agent]
As already described, the photosensitive layer 3 contains an electron transport agent. When the photosensitive layer 3 contains an electron transfer agent, electrons are easily transported and the generation of transfer memory is suppressed.

  Examples of the electron transfer agent include quinone 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, dinitroanthracene, dinitroacridine, succinic anhydride, maleic anhydride, or dibromomaleic anhydride. Examples of the quinone compound include naphthoquinone compounds, diphenoquinone compounds, anthraquinone compounds, azoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds. These electron transfer agents may be used alone or in combination of two or more.

  Specific examples of the quinone compound include compounds represented by general formulas (ET-I) to (ET-III).

  Specific examples of the hydrazone compound include compounds represented by general formula (ET-IV).

In general formulas (ET-I) to (ET-IV), R _{11 to} R ₂₂ each independently represent a hydrogen atom, an alkyl group that may have a substituent, or an alkenyl that may have a substituent. Group, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent Represents. R ₂₃ may have a halogen atom, a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. A good aralkyl group, an aromatic hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent.

In R _{11 to} R ₂₃ in the general formulas (ET-I) to (ET-IV), examples of the alkyl group include alkyl groups having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, s-butyl, n-butyl, tert-butyl, n-pentyl, and isopentyl. Group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, or decyl group. Among the alkyl groups having 1 to 10 carbon atoms, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 5 carbon atoms is more preferable, a methyl group, a tert-butyl group, or A 1,1-dimethylpropyl group is particularly preferred. The alkyl group may be a linear alkyl group, a branched alkyl group, a cyclic alkyl group, or an alkyl group obtained by combining these. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In R _{11 to} R ₂₃ in the general formulas (ET-I) to (ET-IV), examples of the alkenyl group include alkenyl groups having 2 to 10 carbon atoms, and 2 to 6 carbon atoms. The alkenyl group is preferably an alkenyl group having 2 to 4 carbon atoms. The alkenyl group may be a linear alkenyl group, a branched alkenyl group, a cyclic alkenyl group, or an alkenyl group combining these. The alkenyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In R _{11 to} R ₂₃ in the general formulas (ET-I) to (ET-IV), examples of the alkoxy group include an alkoxy group having 1 to 10 carbon atoms, and 1 to 6 carbon atoms. Are more preferable, and an alkoxy group having 1 to 4 carbon atoms is more preferable. The alkoxy group may be a linear alkoxy group, a branched alkoxy group, a cyclic alkoxy group, or an alkoxy group that combines these. The alkoxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In R _{11 to} R ₂₃ in the general formulas (ET-I) to (ET-IV), examples of the aralkyl group include aralkyl groups having 7 to 15 carbon atoms, and 7 to 13 carbon atoms. And an aralkyl group having 7 to 12 carbon atoms is more preferable. The aralkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, and a fat having 2 to 4 carbon atoms. An acyl group, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group. The number of substituents is not particularly limited, but is preferably 5 or less, and more preferably 3 or less.

In R _{11 to} R ₂₃ in the general formulas (ET-I) to (ET-IV), the aromatic hydrocarbon group is formed by, for example, condensing a phenyl group, two or three benzene rings. Or a group formed by connecting two or three benzene rings by a single bond. The number of benzene rings contained in the aromatic hydrocarbon group is, for example, 1 or more and 3 or less, and preferably 1 or 2. Examples of the substituent that the aromatic hydrocarbon group may have include a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, and a cyano group. Group, an aliphatic acyl group having 2 to 4 carbon atoms, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group.

In R _{11 to} R ₂₃ in the general formulas (ET-I) to (ET-IV), the heterocyclic group includes, for example, one or more heteroatoms selected from the group consisting of N, S, and O A 5- or 6-membered monocyclic heterocyclic group; a heterocyclic group in which such monocyclic rings are condensed; or a heterocyclic ring in which such a monocyclic ring is condensed with a 5- or 6-membered hydrocarbon ring Groups. When the heterocyclic group is a condensed ring, the number of rings contained in the condensed ring is preferably 3 or less. Examples of the substituent that the heterocyclic group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, Examples thereof include an aliphatic acyl group having 2 to 4 carbon atoms, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group.

In R ₂₃ in the general formula (ET-IV), examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom is preferable.

  Among the compounds represented by the general formula (ET-I) to the general formula (ET-IV), from the viewpoint of suppressing the generation of the transfer memory, the photosensitive layer 3 has a general formula (ET- It is preferable that the compound represented by I) or general formula (ET-II) is contained.

  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 in the photosensitive layer 3.

[2-4. Binder resin]
Examples of the binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include polycarbonate resin, styrene resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic copolymer, 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, polyether resin, or polyester resin. Examples of the thermosetting resin include silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, and other crosslinkable thermosetting resins. As photocurable resin, an epoxy acrylate resin or a urethane-acrylate copolymer resin is mentioned, for example. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Among these resins, a polycarbonate resin is preferable because the photosensitive layer 3 having an excellent balance of workability, mechanical properties, optical properties, and / or wear resistance can be obtained. Examples of the polycarbonate resin include bisphenol Z-type polycarbonate resin, bisphenol B-type polycarbonate resin, bisphenol CZ-type polycarbonate resin, bisphenol C-type polycarbonate resin, and bisphenol A-type polycarbonate resin. More specifically, examples of the polycarbonate resin include a polycarbonate resin represented by the formula (Resin-I).

  The molecular weight of the binder resin is preferably 40000 or more, more preferably 40000 or more and 52500 or less in terms of viscosity average molecular weight. When the viscosity average molecular weight of the binder resin is 40000 or more, the abrasion resistance of the binder resin can be sufficiently increased, and the photosensitive layer 3 is hardly worn. Further, when the molecular weight of the binder resin is 52500 or less, the binder resin is easily dissolved in the solvent when the photosensitive layer 3 is formed, and the viscosity of the coating solution for the photosensitive layer does not become too high. As a result, the photosensitive layer 3 can be easily formed.

[2-5. Additive]
The photosensitive layer 3 may contain various additives as long as the electrophotographic characteristics of the photoreceptor 1 are not adversely affected. Examples of additives include deterioration inhibitors (eg, antioxidants, radical scavengers, singlet quenchers, or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, and dispersion stabilizers. Agents, waxes, acceptors, donors, surfactants, plasticizers, sensitizers, or leveling agents. 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]
In the photoreceptor 1, the intermediate layer 4 (particularly the undercoat layer) can be located between the conductive substrate 2 and the photosensitive layer 3. The intermediate layer 4 contains, for example, inorganic particles and a resin (interlayer resin) used for the intermediate layer 4. The presence of the intermediate layer 4 makes it possible to smooth the flow of current generated when the photosensitive member 1 is exposed while suppressing an increase in resistance while maintaining an insulating state capable of suppressing the occurrence of leakage.

  As the inorganic particles, for example, metal (for example, aluminum, iron, or copper), metal oxide (for example, titanium oxide, alumina, zirconium oxide, tin oxide, or zinc oxide) particles, or non-metal oxide (for example, , Silica) particles. These inorganic particles may be used individually by 1 type, and may use 2 or more types together.

  The resin for the intermediate layer is not particularly limited as long as it is a resin that can be used as the resin for forming the intermediate layer 4.

  The intermediate layer 4 may contain various additives as long as the electrophotographic characteristics of the photoreceptor 1 are not adversely affected. The additives are the same as those for the photosensitive layer 3.

[4. Production method]
Next, a method for manufacturing the photoreceptor 1 will be described with reference to FIG. The method for manufacturing the photoreceptor 1 can include a photosensitive layer forming step. In the photosensitive layer forming step, the photosensitive layer coating solution is applied onto the conductive substrate 2, and the solvent contained in the applied photosensitive layer coating solution is removed to form the photosensitive layer 3. The coating liquid for photosensitive layer can contain at least a charge generating agent, a triarylamine derivative (1), an electron transporting agent, a binder resin, and a solvent. The coating solution for the photosensitive layer can be prepared by dissolving or dispersing the charge generator, the triphenylamine hydrazine derivative represented by the general formula (1), the electron transport agent, and the binder resin in a solvent. Various additives may be added to the photosensitive layer coating solution as necessary.

  The solvent contained in the photosensitive layer coating solution is not particularly limited as long as each component contained in the photosensitive layer coating solution can be dissolved or dispersed. Examples of the solvent include alcohols (for example, methanol, ethanol, isopropanol, or butanol), aliphatic hydrocarbons (for example, n-hexane, octane, or cyclohexane), aromatic hydrocarbons (for example, benzene, toluene, Or xylene), halogenated hydrocarbons (eg, dichloromethane, dichloroethane, carbon tetrachloride, or chlorobenzene), ethers (eg, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, or diethylene glycol dimethyl ether), ketones (eg, acetone) , Methyl ethyl ketone, or cyclohexanone), esters (for example, ethyl acetate or methyl acetate), dimethylformaldehyde, N, N-dimethylformamide (D F), 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 photosensitive layer coating solution is prepared by mixing each component and dispersing in a solvent. For mixing 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 photosensitive layer coating solution 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 formed layer.

  The method for applying the photosensitive layer coating solution is not particularly limited as long as it is a method that can uniformly apply the photosensitive layer coating solution onto 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.

  The method for removing the solvent contained in the photosensitive layer coating solution is not particularly limited as long as it is a method capable of evaporating the solvent in the photosensitive layer coating solution. Examples of the method for removing the solvent include heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of performing 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.

  The method for manufacturing the photoreceptor 1 may further include a step of forming the intermediate layer 4 and / or 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 can be appropriately selected.

  The photoreceptor 1 is used as an image carrier in an image forming apparatus that includes a charging unit that applies a DC voltage in contact with the image carrier. The image forming apparatus will be described later.

  Heretofore, the photoreceptor 1 according to the first embodiment has been described with reference to FIG. According to the photoreceptor 1 according to the first embodiment, the generation of a transfer memory can be suppressed. According to the photosensitive member 1 according to the first embodiment, transfer memory is effectively generated even in an image forming apparatus including a charging unit that easily contacts with an image carrier and applies a DC voltage. Can be suppressed.

[Second Embodiment: Image Forming Apparatus]
The second embodiment relates to an image forming apparatus. Hereinafter, an aspect of the image forming apparatus 6 according to this embodiment will be described with reference to FIG. FIG. 6 is a schematic diagram illustrating a configuration of one aspect of the image forming apparatus 6 according to the present embodiment.

  Hereinafter, the case where the image forming apparatus 6 adopts the intermediate transfer method will be described as an example. The case where the image forming apparatus 6 employs the direct transfer method will be described later.

  The image forming apparatus 6 includes an image carrier 1 corresponding to a photosensitive member, a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit. The charging unit 27 charges the surface of the image carrier 1. The charging unit 27 is in contact with the image carrier 1 and applies a DC voltage. The charging polarity of the charging unit 27 is positive. The exposure unit 28 exposes the charged surface of the image carrier 1 to form an electrostatic latent image on the surface of the image carrier 1. The developing unit 29 develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the image carrier 1 to the transfer target. When the image forming apparatus 6 adopts the intermediate transfer method, the transfer unit corresponds to the primary transfer roller 33 and the secondary transfer roller 21. The transfer target corresponds to the intermediate transfer belt 20 and a recording medium (for example, paper P). As the image carrier 1, the photoreceptor 1 according to the first embodiment is provided.

  Since the image forming apparatus 6 includes the photoreceptor 1, it is possible to suppress the occurrence of image defects (for example, image ghost) caused by the transfer memory. The reason is presumed as follows.

  First, for convenience, an image defect caused by the transfer memory will be described. When a transfer memory is generated as described above, a region on the surface of the image carrier 1 where a desired potential cannot be obtained in the next charging step is a region where a desired potential can be obtained in the next charging step. In comparison, the potential tends to decrease. Specifically, the potential of the non-exposed area of the previous round on the surface of the image carrier 1 tends to be lower than that of the exposed area of the previous round. For this reason, since the potential of the non-exposed area in the previous round is likely to be lower than that in the exposed area of the previous round, it becomes easier to attract positively charged toner. As a result, an image reflecting the non-image portion (non-exposure area) of the previous round is easily formed. Such an image defect in which an image reflecting the non-image portion of the previous round is formed is an image defect caused by the transfer memory.

  As described above, the photoreceptor 1 according to the first embodiment can suppress the generation of the transfer memory. Since the image forming apparatus 6 includes the photoreceptor 1 according to the first embodiment as an image carrier, it is considered that image defects caused by the transfer memory can be suppressed.

  The image forming apparatus 6 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 6 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. The image forming apparatus 6 may be a tandem color image forming apparatus in order to form toner images of the respective colors using different color toners.

  Hereinafter, the image forming apparatus 6 will be described by taking a tandem color image forming apparatus as an example. The image forming apparatus 6 includes a plurality of photoreceptors 1 arranged in parallel in a predetermined direction and a plurality of developing units 29. Each of the plurality of developing units 29 is disposed to face the photoreceptor 1. Each of the plurality of developing units 29 includes a developing roller. The developing roller carries and conveys toner, and supplies the toner to the surface of the corresponding image carrier 1.

  As shown in FIG. 6, the image forming apparatus 6 further includes a box-shaped device housing 7. In the device housing 7, a paper feeding unit 8, an image forming unit 9, and a fixing unit 10 are provided. The paper feed unit 8 feeds the paper P. The image forming unit 9 transfers the toner image based on the image data to the paper P while conveying the paper P fed from the paper feeding unit 8. The fixing unit 10 fixes the unfixed toner image transferred on the paper P by the image forming unit 9 to the paper P. Further, a paper discharge unit 11 is provided on the upper surface of the device housing 7. The paper discharge unit 11 discharges the paper P fixed by the fixing unit 10.

  The paper supply unit 8 includes a paper supply cassette 12, a first pickup roller 13, paper supply rollers 14, 15 and 16, and a registration roller pair 17. The paper feed cassette 12 is provided so as to be detachable from the device housing 7. Various sizes of paper P are stored in the paper feed cassette 12. The first pickup roller 13 is provided at the upper left position of the paper feed cassette 12. The first pickup roller 13 takes out the sheets P stored in the sheet feeding cassette 12 one by one. The paper feed rollers 14, 15 and 16 convey the paper P taken out by the first pickup roller 13. The registration roller pair 17 temporarily supplies the paper P conveyed by the paper feed rollers 14, 15, and 16 to the image forming unit 9 at a predetermined timing.

  The paper feed unit 8 further includes a manual feed tray (not shown) and a second pickup roller 18. The manual feed tray is attached to the left side surface of the device housing 7. The second pickup roller 18 takes out the paper P placed on the manual feed tray. The paper P taken out by the second pickup roller 18 is conveyed by the paper feed rollers 14, 15 and 16, and is supplied to the image forming unit 9 by the registration roller pair 17 at a predetermined timing.

  The image forming unit 9 includes an image forming unit 19, an intermediate transfer belt 20, and a secondary transfer roller 21. A toner image is primarily transferred onto the intermediate transfer belt 20 by the image forming unit 19 on the surface of the intermediate transfer belt 20 (contact surface with the primary transfer roller 33). The toner image to be primarily transferred is formed based on image data transmitted from a host device such as a computer. The secondary transfer roller 21 secondarily transfers the toner image on the intermediate transfer belt 20 onto the paper P fed from the paper feed cassette 12.

  The image forming unit 19 includes a yellow toner supply unit 25 and a magenta toner supply from the upstream side (right side in FIG. 6) to the downstream side in the rotation direction of the intermediate transfer belt 20 with respect to the yellow toner supply unit 25 as a reference. A unit 24, a cyan toner supply unit 23, and a black toner supply unit 22 are sequentially arranged. In the units 22, 23, 24, and 25, the photoreceptor 1 is disposed at the center position of each unit. The photoreceptor 1 is disposed so as to be rotatable in the direction of an arrow (clockwise). The units 22, 23, 24, and 25 may be process cartridges described later that are detachable from the main body of the image forming apparatus 6.

  Around each image carrier 1, a charging unit 27, an exposure unit 28, and a developing unit 29 are sequentially arranged from the upstream side in the rotation direction of each image carrier 1 with respect to the charging unit 27.

  A static eliminator (not shown) and a cleaning device (not shown) may be provided on the upstream side of the charging unit 27 in the rotation direction of the image carrier 1. The static eliminator neutralizes the peripheral surface of the image carrier 1 after the primary transfer of the toner image to the intermediate transfer belt 20 is completed. The peripheral surface of the image carrier 1 cleaned and discharged by the cleaning device and the charge eliminator is sent to the charging unit 27 and newly charged. When the image forming apparatus 6 includes a cleaning device and / or a static eliminator, the charging unit 27, the exposure unit 28, the developing unit 29, and the primary transfer roller with reference to the charging unit 27 from the upstream side in the rotation direction of each image carrier 1. 33, the cleaning device, and the static eliminator are arranged in this order.

  As already described, the charging unit 27 charges the surface of the image carrier 1. Specifically, the charging unit 27 uniformly charges the peripheral surface of the image carrier 1 rotated in the arrow direction to positive polarity. The charging unit 27 is in contact with the image carrier 1 and applies a DC voltage. The charging unit 27 is also referred to as a so-called contact-type charging unit. Examples of such a charging unit 27 include a charging device, and more specifically, a charging roller or a charging brush. Of these, a charging roller is preferable.

  An example of such a charging roller is a charging roller that rotates depending on the rotation of the image carrier 1 while in contact with the image carrier 1. Moreover, as a charging roller, the charging roller by which the surface part was comprised with resin at least is mentioned, for example. Specifically, the charging roller includes, for example, a core metal that is rotatably supported, a resin layer formed on the core metal, and a voltage application unit that applies a voltage to the core metal. The charging unit 27 including such a charging roller can charge the surface of the photoreceptor 1 that is in contact with the resin through the resin layer when the voltage application unit applies a voltage to the cored bar.

  The resin constituting the resin layer of the charging roller is not particularly limited as long as the peripheral surface of the image carrier 1 can be charged satisfactorily. Specific examples of the resin constituting the resin layer include a silicone resin, a urethane resin, or a silicone-modified resin. The resin layer may contain an inorganic filler.

  It is considered that discharge of active gas (for example, ozone or nitrogen oxide) generated from the charging unit 27 can be suppressed by using the contact type charging unit 27 as described above. As a result, it is considered that the deterioration of the photosensitive layer 3 due to the active gas is suppressed and the design considering the office environment can be achieved.

  The charging unit 27 that applies only a DC voltage has the following advantages compared to a charging unit that applies an AC voltage or a charging unit that applies a superimposed voltage obtained by superimposing an AC voltage on a DC voltage. When the charging unit 27 applies only a DC voltage, the voltage value applied to the image carrier 1 is constant, so that the surface of the image carrier 1 is easily charged uniformly to a constant potential. Further, when the charging unit 27 applies only a DC voltage, the wear amount of the photosensitive layer 3 tends to decrease. As a result, a suitable image can be formed. The DC voltage applied to the photoreceptor 1 by the charging unit 27 is preferably 1000 V or more and 2000 V or less, more preferably 1200 V or more and 1800 V or less, and particularly preferably 1400 V or more and 1600 V or less.

  Examples of the exposure unit 28 include an exposure device, and more specifically, a laser scanning unit. The exposure unit 28 exposes the charged surface of the image carrier 1 to form an electrostatic latent image on the surface of the image carrier 1. Specifically, the exposure unit 28 irradiates the circumferential surface of the image carrier 1 uniformly charged by the charging unit 27 with laser light based on image data input from a host device such as a personal computer. Thereby, an electrostatic latent image based on the image data is formed on the peripheral surface of the image carrier 1.

  The developing unit 29 develops the electrostatic latent image as a toner image. Specifically, the developing unit 29 supplies toner to the peripheral surface of the image carrier 1 on which the electrostatic latent image is formed, and forms a toner image based on the image data. An example of the developing unit 29 is a developing device.

  The transfer unit (corresponding to the primary transfer roller 33 and the secondary transfer roller 21) transfers the toner image formed on the surface of the image carrier 1 to the transfer target (corresponding to the intermediate transfer belt 20 and the paper P). . The intermediate transfer belt 20 is an endless belt rotating body. The intermediate transfer belt 20 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of primary transfer rollers 33. The intermediate transfer belt 20 is disposed so that the peripheral surfaces of the plurality of image carriers 1 are in contact with the surface (contact surface) of the intermediate transfer belt 20.

  Further, the intermediate transfer belt 20 is pressed against the image carrier 1 by a primary transfer roller 33 disposed to face each image carrier 1. In the pressed state, the intermediate transfer belt 20 rotates endlessly in the arrow (counterclockwise) direction by the plurality of drive rollers 30. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 20 endlessly. The driven roller 31, the backup roller 32, and the plurality of primary transfer rollers 33 are rotatably provided. The driven roller 31, the backup roller 32, and the primary transfer roller 33 rotate following the endless rotation of the intermediate transfer belt 20 by the driving roller 30. The driven roller 31, the backup roller 32, and the primary transfer roller 33 are driven to rotate via the intermediate transfer belt 20 according to the main rotation of the driving roller 30 and support the intermediate transfer belt 20.

  The primary transfer roller 33 applies a primary transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the intermediate transfer belt 20. As a result, the toner image formed on each image carrier 1 is sequentially transferred (primary transfer) between each image carrier 1 and the primary transfer roller 33 to the circulating intermediate transfer belt 20. . Note that the charging polarity of the toner is positive.

  The secondary transfer roller 21 applies a secondary transfer bias (specifically, a bias having a polarity opposite to the toner charging polarity) to the paper P. As a result, the toner image primarily transferred onto the intermediate transfer belt 20 is transferred onto the paper P between the secondary transfer roller 21 and the backup roller 32. As a result, an unfixed toner image is transferred onto the paper P.

  The fixing unit 10 fixes the unfixed toner image transferred to the paper P by the image forming unit 9. The fixing unit 10 includes a heating roller 34 and a pressure roller 35. The heating roller 34 is heated by an energized heating element. The pressure roller 35 is disposed to face the heating roller 34, and the circumferential surface of the pressure roller 35 is pressed against the circumferential surface of the heating roller 34.

  The transfer image transferred to the paper P by the secondary transfer roller 21 in the image forming unit 9 is fixed to the paper P by a fixing process by heating when the paper P passes between the heating roller 34 and the pressure roller 35. The Then, the paper P subjected to the fixing process is discharged to the paper discharge unit 11. In addition, a plurality of transport rollers 36 are disposed at appropriate positions between the fixing unit 10 and the paper discharge unit 11.

  The paper discharge unit 11 is formed by recessing the top of the device housing 7. A paper discharge tray 37 that receives the discharged paper P is provided at the bottom of the recessed portion. The image forming apparatus 6 according to one aspect of the present embodiment has been described above with reference to FIG.

  Hereinafter, an image forming apparatus according to another aspect of this embodiment will be described with reference to FIG. FIG. 7 is a schematic diagram illustrating a configuration of another aspect of the image forming apparatus 6 according to the present embodiment. The image forming apparatus 6 shown in FIG. 7 employs a direct transfer method. In the image forming apparatus 6 illustrated in FIG. 7, the transfer unit corresponds to the transfer roller 41. The transfer target corresponds to a recording medium (for example, paper P). In FIG. 7, the same reference numerals are used for the elements corresponding to those in FIG.

  In the image forming apparatus 6 adopting the direct transfer method, the image carrier is likely to be affected by the transfer bias, so that a transfer memory is usually easily generated. However, as described above, the photoreceptor 1 according to the first embodiment tends to suppress the generation of the transfer memory. Therefore, since the image forming apparatus 6 shown in FIG. 7 includes the photoconductor 1 according to the first embodiment as the image carrier 1, even if the image forming apparatus 6 adopts the direct transfer method, the image forming apparatus 6 uses a transfer memory. It is considered that the occurrence of image defects caused is suppressed.

  As shown in FIG. 7, the transfer belt 40 is an endless belt-like rotating body. The transfer belt 40 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of transfer rollers 41. The transfer belt 40 is disposed so that the circumferential surface of each image carrier 1 is in contact with the surface (contact surface) of the transfer belt 40. The transfer belt 40 is pressed against the image carrier 1 by each transfer roller 41 disposed to face each image carrier 1. In the pressed state, the transfer belt 40 is rotated endlessly by the plurality of rollers 30, 31, 32, and 41. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the transfer belt 40 endlessly. The driven roller 31, the backup roller 32, and the transfer roller 41 are rotatably provided. With the endless rotation of the transfer belt 40 by the driving roller 30, the driven roller 31, the backup roller 32, and the plurality of transfer rollers 41 are driven to rotate. These rollers 31, 32 and 41 are driven to rotate and support the transfer belt 40. The paper P supplied from the registration roller pair 17 is sucked onto the transfer belt 40 by the suction roller 42. The sheet P adsorbed on the transfer belt 40 passes between each image carrier 1 and the corresponding transfer roller 41 as the transfer belt 40 rotates.

  The transfer roller 41 transfers the toner image from the image carrier 1 to the paper P. When transferring the toner image, the image carrier 1 is in contact with the paper P. Specifically, each transfer roller 41 applies a transfer bias (specifically, a bias having a polarity opposite to the toner charging polarity) to the paper P adsorbed on the transfer belt 40. As a result, the toner image formed on the image carrier 1 is transferred to the paper P between each image carrier 1 and the corresponding transfer roller 41. The transfer belt 40 circulates in the arrow (clockwise) direction by driving the driving roller 30. Accordingly, the paper P sucked on the transfer belt 40 sequentially passes between each image carrier 1 and the corresponding transfer roller 41. When passing, the toner images of the corresponding colors formed on each image carrier 1 are sequentially transferred onto the paper P in the overcoated state. Thereafter, each image carrier 1 further rotates and shifts to the next process. The image forming apparatus that employs the direct transfer method according to another aspect of the present embodiment has been described above with reference to FIG.

  As described with reference to FIGS. 6 and 7, the image forming apparatus 6 according to the second embodiment includes the photoreceptor 1 according to the first embodiment as an image carrier. The photoreceptor 1 can suppress the generation of a transfer memory. Therefore, by providing such a photoreceptor 1, the image forming apparatus 6 according to the second embodiment can suppress the occurrence of image defects. Furthermore, even when the image forming apparatus 6 according to the second embodiment includes the charging unit 27 that contacts the image carrier 1 and applies a DC voltage, it is effective to generate image defects caused by the transfer memory. Can be suppressed.

[Third embodiment: Process cartridge]
The third embodiment relates to a process cartridge. The process cartridge according to the present embodiment includes the photoconductor 1 according to the first embodiment as an image carrier. The photoreceptor 1 according to the first embodiment can suppress the generation of the transfer memory as described above. Therefore, it is considered that the process cartridge according to the present embodiment can suppress image defects caused by the transfer memory when provided in the image forming apparatus.

  The process cartridge can include, for example, the photoreceptor 1 according to the first embodiment unitized as an image carrier. The process cartridge may be designed to be detachable from the image forming apparatus 6 according to the second embodiment. For example, the process cartridge adopts a configuration in which at least one selected from the group consisting of a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit is unitized in addition to the image carrier. Can do. Here, the charging unit, the exposure unit, the development unit, the transfer unit, the cleaning unit, and the charge removal unit are the charging unit 27, the exposure unit 28, the development unit 29, the transfer unit, and the cleaning device described above in the second embodiment. , And the same configuration as the static eliminator.

  The process cartridge according to the third embodiment has been described above. The process cartridge according to the third embodiment can suppress the occurrence of image defects caused by the transfer memory. Further, since such a process cartridge is easy to handle, it can be easily and quickly replaced including the photosensitive member when the sensitivity characteristic of the photosensitive member is deteriorated.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the scope of the examples.

[1. Preparation of photoconductor]
Photoconductors (A-1) to (A-37) and (B-1) to (B-4) were prepared using a charge generator, a hole transport agent, an electron transport agent, and a binder resin.

[1-1. Preparation of charge generator]
For the production of the photoconductors (A-1) to (A-37) and (B-1) to (B-4), any one of the following charge generators was used. Specifically, it may be described as X-type metal-free phthalocyanine (hereinafter sometimes referred to as “charge generating agent (X—H ₂ Pc)”) or titanyl phthalocyanine (hereinafter referred to as “charge generating agent (TiOPc)”). Used).

[1-2. Preparation of hole transport agent]
For the production of the photoreceptors (A-1) to (A-37), the triarylamine derivatives (HT-1) to (HT-9) described above in the first embodiment were used as hole transporting agents. A method for synthesizing these triarylamine derivatives will be described later. Moreover, the hole transport agent represented by Formula (HT-A) was used for preparation of the photoreceptors (B-1) to (B-4).

[1-2-1. Preparation of Triarylamine Derivative (HT-1)]
Reactions represented by reaction formulas (R-5) to (R-10) were performed to synthesize a triarylamine derivative (HT-1).

  First, the reaction represented by the reaction formula (R-5) was performed. Specifically, 16.1 g (0.1 mol) of the benzene derivative represented by the formula (9) and 25 g (0.15 mol) of triethyl phosphite represented by the formula (10) were placed in a 200 mL flask. I put it in. This was stirred for 8 hours while heating at 180 ° C. Subsequently, after cooling to room temperature, excess triethyl phosphite was distilled off under reduced pressure to obtain 24.1 g (yield: 92%) of the phosphonate derivative (white liquid) represented by the formula (11).

  Then, the reaction represented by the reaction formula (R-6) was performed. Specifically, 13.0 g of the phosphonate derivative represented by the formula (11) was added to a 500 mL two-necked flask whose internal temperature was adjusted to 0 ° C. 0.05 mol) was added to perform argon gas replacement. To this, 100 mL of dried tetrahydrofuran (THF) and 9.3 g (0.05 mol) of a methanol solution of sodium methoxide (concentration: 28% by mass) were added and stirred at 0 ° C. for 30 minutes. To this reaction solution, a mixed solution in which 5.0 g (0.05 mol) of benzaldehyde represented by the formula (12) was dissolved in 300 mL of dry THF was added and stirred at room temperature for 12 hours.

  Thereafter, the reaction solution was poured into ion-exchanged water and extracted with toluene to obtain an organic phase (toluene phase). This organic phase was washed 5 times with ion exchange water. Subsequently, after drying an organic phase with anhydrous sodium sulfate, the solvent was distilled off to obtain a residue. Thereafter, the residue was purified by recrystallization with a solvent (a mixed solvent of 20 mL of toluene and 100 mL of methanol), and 9.3 g (yield: 92%) of a stilbene derivative (white crystals) represented by the formula (13) was obtained. Obtained.

  Subsequently, reaction represented by Reaction formula (R-7) was performed. Specifically, in a 200 mL flask, 16.1 g (0.075 mol) of dibromobutene represented by the formula (14) and 25 g (0.15 mol) of triethyl phosphite represented by the formula (10) And put it in. This was stirred for 8 hours while heating at 180 ° C. Subsequently, after cooling to room temperature, excess triethyl phosphite was distilled off under reduced pressure to obtain 22.5 g (yield: 91%) of the phosphonate derivative (colorless liquid) represented by the formula (15).

  Subsequently, reaction represented by Reaction formula (R-8) was performed. Specifically, 8.0 g (0.024 mol) of the phosphonate derivative represented by the formula (15) was introduced into a 500 mL two-necked flask whose internal temperature was adjusted to 0 ° C., and substituted with argon gas. To this, 100 mL of dried tetrahydrofuran (THF) and 9.3 g (0.05 mol) of a methanol solution of sodium methoxide (concentration: 28% by mass) were added and stirred at 0 ° C. for 30 minutes. To this reaction solution, a mixed solution prepared by dissolving 7.0 g (0.05 mol) of chlorobenzaldehyde represented by the formula (16) in 300 mL of dry THF was added and stirred at room temperature for 12 hours.

  Thereafter, the reaction solution was poured into ion-exchanged water and extracted with toluene to obtain an organic phase (toluene phase). This organic phase was washed 5 times with ion exchange water. Subsequently, after drying an organic phase with anhydrous sodium sulfate, the solvent was distilled off to obtain a residue. Thereafter, the residue was purified by recrystallization with a solvent (a mixed solvent of 20 mL of toluene and 100 mL of methanol), and 2.0 g (yield: 27%) of a stilbene derivative (white crystals) represented by the formula (17) was obtained. Obtained.

Subsequently, reaction represented by Reaction formula (R-9) was performed. Specifically, in a 2 L three-necked flask, 2.7 g (0.02 mol) of the aniline derivative represented by the formula (18) and 4.4 g (0.02 mol) of the stilbene derivative represented by the formula (19) Mol), 0.072 g (0.002049 mol) of tricyclohexylphosphine (Pcy3), 0.047 g (0.00005123 mol) of tris (dibenzylideneacetone) dipalladium (Pd ₂ (dba) ₃ ) and sodium-tert -2 g (0.021 mol) of butoxide (t-BuONa) was added. Furthermore, 100 mL of distilled o-xylene was added. Then, argon gas substitution was performed and it reacted for 5 hours, stirring at 120 degreeC.

  Next, the reaction liquid (solution containing the reaction product and o-xylene) was cooled to room temperature to obtain an organic phase. This organic phase was washed three times with ion exchange water. Further, the organic phase was dried and adsorbed using anhydrous sodium sulfate and activated clay. Thereafter, o-xylene was distilled off under reduced pressure to obtain a residue.

  The obtained residue was purified using silica gel column chromatography (developing solvent: mixed solvent of chloroform and hexane) to obtain 5.5 g of intermediate represented by formula (20) (yield: 86%). .

  Subsequently, reaction represented by Reaction formula (R-10) was performed. Specifically, in a three-necked flask, 3.0 g (0.01 mol) of the intermediate represented by the formula (20), 0.035 g (0.00009967 mol) of tricyclohexylphosphine, and tris (dibenzylideneacetone) di 0.046 g (0.00004983 mol) of palladium, 1.0 g (0.01 mol) of sodium-tert-butoxide (t-BuONa), and 1.5 g (0.05) of the stilbene derivative represented by the formula (17) Mol). Furthermore, 200 mL of distilled o-xylene was added. Then, argon gas substitution was performed and it reacted for 5 hours, stirring at 120 degreeC.

  Subsequently, the reaction liquid was cooled to room temperature to obtain an organic phase. The obtained organic phase was washed three times with ion-exchanged water, and further dried and adsorbed using anhydrous sodium sulfate and activated clay. Thereafter, o-xylene was distilled off under reduced pressure to obtain a residue.

  The obtained residue was purified using silica gel column chromatography (developing solvent: mixed solvent of chloroform and hexane) to obtain 3.2 g of a triarylamine derivative (HT-1) (yield: 75%).

The triarylamine derivative (HT-1) was measured by a proton nuclear magnetic resonance spectrometer ( ¹ H-NMR, 300 MHz). CDCl ₃ was used as the solvent. Tetramethylsilane (TMS) was used as an internal reference material. It was confirmed by a ¹ H-NMR chart that a triarylamine derivative (HT-1) was obtained. A ¹ H-NMR chart of the triarylamine derivative (HT-1) is shown in FIG.

[1-2-2. Synthesis of Triarylamine Derivative (HT-2)]
Reactions represented by reaction formulas (R-11) to (R-14) were performed to synthesize a triarylamine derivative (HT-2).

  First, in (R-11), 16.1 g (0.1 mol) of the benzene derivative represented by the formula (9) and 25 g of triethyl phosphite represented by the formula (10) were added to a 200 mL flask. 0.15 mol). This was stirred for 8 hours while heating at 180 ° C. Subsequently, after cooling to room temperature, excess triethyl phosphite was distilled off under reduced pressure to obtain 24.1 g (yield: 92%) of the phosphonate derivative (white liquid) represented by the formula (11).

  Next, instead of benzaldehyde represented by formula (12), cinnamaldehyde represented by formula (21) was used, and reaction represented by reaction formula (R-12) was substituted for reaction formula (R-6). went. As a result, a stilbene derivative represented by the formula (22) was obtained.

  Subsequently, the reaction represented by the reaction formulas (R-13) and (R-14) was performed. First, in the reaction formula (R-13), the same procedure as in the reaction formula (R-9) was performed except that the stilbene derivative represented by the formula (22) was used instead of the stilbene derivative represented by the formula (19). Thus, an intermediate represented by the formula (23) was obtained (yield: 83%). Thereafter, in the reaction represented by the reaction formula (R-14), the reaction formula (R) was used except that the stilbene derivative represented by the formula (17) was used instead of the stilbene derivative represented by the formula (17). In the same manner as in the reaction represented by -10), a triarylamine derivative (HT-2) was synthesized (yield: 75%).

A ¹ H-NMR chart (solvent: CDCl ₃ , internal reference material: TMS) of the triarylamine derivative (HT-2) is shown in FIG.

  In addition, in the synthesis | combination of a triarylamine derivative (HT-2) and the synthesis | combination of the below-mentioned formula (HT-3)-triarylamine derivative (HT-9), those molar scales are triarylamine derivatives (HT- The compounding amount of the material was adjusted so as to be equal to the molar scale in the synthesis of 1).

[1-2-3. Synthesis of Triarylamine Derivative (HT-3)]
Reactions represented by reaction formulas (R-15) and (R-16) were performed to synthesize a triarylamine derivative (HT-3).

Specifically, the benzene derivative represented by the formula (25) is used instead of the stilbene derivative represented by the formula (19), and the aniline derivative represented by the formula (18) is further substituted by the formula (24). The reaction represented by the reaction formula (R-15) was performed instead of the reaction formula (R-9). As a result, an intermediate represented by the formula (26) was obtained (yield: 85%). Next, the reaction represented by the reaction formula (R-16) was performed in the same manner as the reaction represented by the reaction formula (R-10) using the stilbene derivative represented by the formula (17). As a result, a triarylamine derivative (HT-3) was obtained (yield: 77%). A ¹ H-NMR chart (solvent: CDCl ₃ , internal reference substance: TMS) of the triarylamine derivative (HT-3) is shown in FIG.

[1-2-4. Synthesis of Triarylamine Derivative (HT-4)]
Reactions represented by reaction formulas (R-17) to (R-20) were performed to synthesize a triarylamine derivative (HT-4).

  First, the reaction represented by the formula (R-17) was performed in the same manner as the reaction represented by the reaction formula (R-5). Next, a cinnamaldehyde derivative represented by the formula (21) is used instead of the benzaldehyde represented by the formula (12), and a reaction represented by the reaction formula (R-18) is substituted for the reaction formula (R-12). Went. As a result, a stilbene derivative represented by the formula (27) was obtained (yield: 70%).

Next, the reaction represented by the reaction formula (R-19) was performed by the same method as the reaction represented by the reaction formula (R-9). As a result, an intermediate represented by the formula (20) was obtained (yield: 85%). Next, a stilbene derivative represented by the formula (27) is used instead of the stilbene derivative represented by the formula (17), and a reaction represented by the reaction formula (R-20) is substituted for the reaction formula (R-10). Went. As a result, a triarylamine derivative (HT-4) was synthesized (yield: 80%). FIG. 5 shows a ¹ H-NMR chart (solvent: CDCl ₃ , internal standard substance: TMS) of the triarylamine derivative (HT-4).

[1-2-5. Synthesis of Triarylamine Derivative (HT-5)]
The reaction represented by the reaction formulas (R-21) and (R-22) was performed to synthesize a triarylamine derivative (HT-5).

First, the reaction represented by the reaction formula (R-21) was performed by the same method as the reaction formula (R-13). As a result, an intermediate (23) represented by the formula (23) was obtained (yield: 80%). Next, a stilbene derivative represented by the formula (27) is used instead of the stilbene derivative represented by the formula (17), and a reaction represented by the reaction formula (R-22) is substituted for the reaction formula (R-14). Went. As a result, a triarylamine derivative (HT-5) was synthesized (yield: 80%). FIG. 6 shows a ¹ H-NMR chart (solvent: CDCl ₃ , internal standard substance: TMS) of the triarylamine derivative (HT-5).

[1-2-6. Synthesis of Triarylamine Derivative (HT-6)]
Reactions represented by reaction formulas (R-23) to (R-26) were performed to synthesize formula (HT-6).

  First, the reaction represented by the reaction formula (R-23) was performed in the same manner as the reaction represented by the reaction formula (R-5). As a result, a phosphonate derivative represented by the formula (11) was obtained. Next, the aldehyde derivative represented by the formula (16) is used instead of the aldehyde derivative represented by the formula (12), and the reaction represented by the reaction formula (R-24) is substituted for the reaction formula (R-6). Went. As a result, a stilbene derivative represented by the formula (28) was obtained (yield: 75%).

Next, the reaction represented by the formula (R-25) was performed in the same manner as the reaction represented by the reaction formula (R-9). As a result, an intermediate represented by the formula (20) was obtained (yield: 85%). Thereafter, a stilbene derivative represented by the formula (28) is used instead of the stilbene derivative represented by the formula (17), and a reaction represented by the reaction formula (R-26) is substituted for the reaction formula (R-10). Went. As a result, a triarylamine derivative (HT-6) was synthesized (yield: 85%). FIG. 7 shows a ¹ H-NMR chart (solvent: CDCl ₃ , internal standard substance: TMS) of the triarylamine derivative (HT-6).

[1-2-7. Synthesis of Triarylamine Derivative (HT-7)]
A reaction represented by reaction formulas (R-27) and (R-28) was performed to synthesize a triarylamine derivative (HT-7).

The reaction represented by the reaction formula (R-27) was performed in the same manner as the reaction represented by the reaction formula (R-13). As a result, an intermediate represented by the formula (23) was obtained (yield: 83%). Next, a stilbene derivative represented by the formula (28) is used instead of the stilbene derivative represented by the formula (17), and a reaction represented by the reaction formula (R-28) is substituted for the reaction formula (R-14). Went. As a result, a triarylamine derivative (HT-7) was synthesized (yield: 85%). A ¹ H-NMR chart (solvent: CDCl ₃ , internal reference material: TMS) of the triarylamine derivative (HT-7) is shown in FIG.

[1-2-8. Synthesis of Triarylamine Derivative (HT-8)]
Reactions represented by reaction formulas (R-29) to (R-32) were performed to synthesize a triarylamine derivative (HT-8).

  Using the benzene derivative represented by the formula (29) instead of the benzene derivative represented by the formula (9), the reaction represented by the reaction formula (R-29) is performed instead of the reaction formula (R-9). It was. As a result, a phosphonate derivative represented by the formula (30) was obtained.

  Next, a benzene derivative represented by the formula (21) is used instead of the benzaldehyde represented by the formula (12), and the reaction represented by the reaction formula (R-30) is substituted for the reaction formula (R-6). went. As a result, a stilbene derivative represented by the formula (31) was obtained.

  Next, a stilbene derivative represented by the formula (31) is used instead of the stilbene derivative represented by the formula (19), and a reaction represented by the reaction formula (R-31) instead of the reaction formula (R-9) Went. As a result, an intermediate represented by the formula (32) was obtained (yield: 75%). Next, a stilbene derivative represented by the formula (27) is used instead of the stilbene derivative represented by the formula (17), and the reaction represented by the reaction formula (32) is substituted for the reaction represented by the reaction formula (R-10). The reaction was performed. As a result, a triarylamine derivative (HT-8) was synthesized (yield: 73%).

[1-2-9. Synthesis of Triarylamine Derivative (HT-9)]
Reactions represented by reaction formulas (R-33) to (R-37) were performed to synthesize a triarylamine derivative (HT-9).

  First, the reaction represented by the reaction formula (R-33) was performed in the same manner as the reaction represented by the reaction formula (R-5). As a result, a phosphonate derivative represented by the formula (11) was obtained. Next, a benzene derivative represented by the formula (32) is used instead of the benzaldehyde represented by the formula (12), and the reaction represented by the reaction formula (R-34) is substituted for the reaction represented by the reaction formula (R-6). The indicated reaction was performed. As a result, a stilbene derivative represented by the formula (32) was obtained.

  Next, the aniline derivative represented by the formula (34) is used instead of the aniline derivative represented by the formula (18), and the stilbene derivative represented by the formula (19) is further substituted by the formula (33). Using the stilbene derivative, the reaction represented by the reaction formula (R-36) was performed instead of the reaction formula (R-9). As a result, an intermediate represented by the formula (35) was obtained (yield: 78%). Furthermore, instead of the intermediate represented by the formula (20), the intermediate represented by the formula (35) is used, and instead of the reaction represented by the reaction formula (R-10), the reaction formula (R-37) The reaction represented by As a result, a triarylamine derivative (HT-9) was synthesized (yield: 70%).

[1-3. Preparation of electron transport agent]
For the preparation of the photoreceptors (A-1) to (A-37) and (B-1) to (B-4), the general formulas (ET-I) to (ET-IV) described above in the first embodiment are used. Any one of the following electron transporting agents (ET-1) to (ET-4) was used. The electron transfer agent (ET-1) is a compound represented by the general formula (ET-I). Further, in general formula (ET-I), R ₁₁ represents a methyl group, R ₁₂ represents a tert-butyl group, R ₁₃ represents a methyl group, and R ₁₄ represents a tert-butyl group. The electron transport agent (ET-2) is a compound represented by the general formula (ET-II). Furthermore, in the general formula (ET-II), R ₁₅ represents a methyl group, R ₁₆ represents a tert-butyl group, R ₁₇ represents a methyl group, and R ₁₈ represents a tert-butyl group. The electron transfer agent (ET-3) is a compound represented by the general formula (ET-III). Further, in the general formula (ET-III), R ₁₉ and R ₂₀ each represent a 1,1-dimethylpropyl group. The electron transport agent (ET-4) is a compound represented by the general formula (ET-IV). Further, in the general formula (ET-IV), R ₂₁ represents a tert-butyl group, R ₂₂ represents a tert-butyl group, and R ₂₃ represents a chlorine atom located in the para position with respect to the nitrogen atom.

[1-4. Preparation of binder resin]
For the preparation of the photoreceptors (A-1) to (A-37) and (B-1) to (B-4), the binder resin is represented by the formula (Resin-1) described above in the first embodiment. Polycarbonate resin (hereinafter may be referred to as binder resin (Resin-1)). Specifically, “Panlite (registered trademark) TS-2050” (viscosity average molecular weight: 50000) manufactured by Teijin Limited was used as the binder resin (Resin-1).

[1-5. Production of photoconductor (A-1)]
In the container, 5 parts by mass of a charge generating agent (X—H ₂ Pc), 50 parts by mass of a triarylamine derivative (HT-1) as a hole transporting agent, and 35 parts by mass of an electron transporting agent (ET-1) And 100 parts by mass of a binder resin (Resin-1) and 800 parts by mass of tetrahydrofuran as a solvent were added. These were mixed and dispersed for 50 hours using a ball mill to prepare a photosensitive layer coating solution.

  Using a dip coating method, a coating solution for a photosensitive layer was applied on a conductive substrate to form a coating film on the conductive substrate. Then, it was made to dry for 40 minutes at 100 degreeC, and tetrahydrofuran was removed from the coating film. As a result, a photoreceptor (A-1) having a photosensitive layer with a thickness of 30 μm on a conductive substrate was obtained.

[1-6. Preparation of photoreceptors (A-2) to (A-37) and (B-1) to (B-4)]
Except for the following changes, the photosensitive members (A-2) to (A-37) and (B-1) to (B-4) were prepared in the same manner as the preparation of the photosensitive member (A-1). Prepared. Instead of the charge generating agent (X—H ₂ Pc), triarylamine derivative (HT-1), and electron transporting agent (ET-1) used for the preparation of the photoreceptor (A-1), respectively, The charge generating agent (CGM), hole transporting agent (HTM), and electron transporting agent (ETM) shown in Table 1 and Table 2 were used.

[2. Photoconductor performance evaluation]
The following evaluation was performed on any of the photoreceptors (A-1) to (A-37) and (B-1) to (B-4).

[2-1. Evaluation of transfer memory]
The photoreceptor was mounted on an image forming apparatus (“FS-C5250DN” manufactured by Kyocera Document Solutions Inc.). This image forming apparatus employs an intermediate transfer system. The image forming apparatus includes a contact-type charging roller that applies a DC voltage as a charging unit. As the charging unit, a charging roller that charges the surface of the photosensitive member by bringing a charging sleeve into contact with the photosensitive member was used. The charging sleeve is composed of a charging rubber in which conductive carbon is dispersed in epichlorohydrin resin. The surface of the photoreceptor was charged to +600 V using this charging roller. Subsequently, the surface of the photoreceptor was exposed.

Subsequently, the surface potential of the unexposed portion of the photosensitive member in the case of not applying a transfer bias to the photoconductor (V _OFF), the surface potential (V _ON of the non-exposed portion of the photoreceptor in the case of applying a transfer bias to the photoconductor ) And were measured in order. Note that a transfer bias of −2 KV was applied to the photoreceptor. The measurement environment was a temperature of 23 ° C. and a humidity of 50% RH.

The difference in surface potential (V _ON -V _OFF ) was calculated from the measured surface potential of the photoreceptor. The difference in the calculated surface potential was taken as the transfer memory potential. Tables 1 and 2 show the transfer memory potential. Note that the larger the absolute value of the difference in surface potential, the more transfer memory is generated.

  Next, the charging unit provided in the image forming apparatus was changed from a contact-type charging roller that applies a DC voltage to a contact-type charging roller that applies an AC voltage. Then, using the photoconductor (A-1), an attempt was made to obtain the transfer memory potential by the same method as the evaluation of the transfer memory. However, the surface potential of the photoconductor was greatly reduced, and the surface potential of the photoconductor was not stable. Therefore, it was impossible to evaluate the transfer memory when an AC voltage was applied.

[2-2. Image evaluation]
The photoreceptor was mounted on an image forming apparatus (“FS-C5250DN” manufactured by Kyocera Document Solutions Inc.). This image forming apparatus employs an intermediate transfer system. The image forming apparatus includes a contact-type charging roller that applies a DC voltage as a charging unit. The charging roller charges the surface of the photosensitive member by bringing the charging sleeve into contact with the photosensitive member. The charging sleeve is composed of a charging rubber in which conductive carbon is dispersed in epichlorohydrin resin. In order to stabilize the operation of the photoreceptor in the image forming apparatus, an alphabet image was printed for 1 hour. Subsequently, one image A was printed. Image A is an image composed of a donut-shaped white pattern. A donut-shaped white pattern is composed of a set of two concentric circles. The image density of the image portion of image A (the region other than the donut-shaped white portion) was 100%. Image A corresponds to an image formed on the first round of the photoreceptor. Subsequently, one half-tone image B (image density 12.5%) was printed on one sheet, and used as an image ghost evaluation sample. Image B corresponds to an image formed on the second round of the photoreceptor.

The obtained sample for evaluation was visually observed to confirm the presence or absence of an image ghost derived from the image A. The presence or absence of image ghost was evaluated based on the following criteria. The results of image evaluation are shown in Tables 1 and 2.
A (good): An image ghost derived from the image A was not observed.
○ (Normal): Image ghost derived from Image A was slightly observed.
X (defect): An image ghost derived from the image A was clearly observed.

  In Table 2, “HT-1 / HT-2 (1: 1)” means a triarylamine derivative (HT-1) and (HT-2) as a hole transporting agent in a mass ratio of 1: 1 (each 25 (Mass part) indicating that the photosensitive member (A-38) contained the toner.

  As shown in Table 1 and Table 2, the photoreceptors (A-1) to (A-37) contained triarylamine derivatives (HT-1) to (HT-9). Therefore, in the photoconductors (A-1) to (A-37), the absolute value of the transfer memory potential is small, and the generation of the transfer memory is suppressed. On the other hand, the photoreceptors (B-1) to (B-4) did not contain any of the triarylamine derivatives represented by the general formulas (1) and (2). For this reason, the absolute value of the transfer memory potential is large and transfer memory is generated.

  All the evaluations of images formed by the image forming apparatus including the photoconductors (A-1) to (A-37) were good or normal. All the evaluations of the images formed by the image forming apparatus including the photoconductors (B-1) to (B-4) were poor. For this reason, the image forming apparatus including the photoconductors (A-1) to (A-37) suppresses the occurrence of image ghost as compared with the image forming apparatus including the photoconductors (B-1) to (B-4). Was shown to do.

  From the above, it has been shown that the photoconductor according to the present invention suppresses the generation of transfer memory, and the image forming apparatus including such a photoconductor suppresses the occurrence of image defects (for example, image ghost).

  The photoreceptor according to the present invention can be suitably used as an electrophotographic photoreceptor.

1 Positively charged single layer type electrophotographic photosensitive member (image carrier)
2 Conductive substrate 3 Photosensitive layer 4 Intermediate layer 5 Protective layer 6 Image forming apparatus 7 Device housing 8 Paper feed unit 9 Image forming unit 10 Fixing unit 11 Paper discharge unit 12 Paper feed cassette 13 First pickup roller 14 Paper feed roller 15 Paper roller 16 Paper feed roller 17 Registration roller pair 18 Second pickup roller 19 Image forming unit 20 Intermediate transfer belt 21 Secondary transfer roller 22 Black toner supply unit 23 Cyan toner supply unit 24 Magenta toner supply unit 25 Yellow toner supply Unit 27 charging unit 28 exposure unit 29 developing unit 30 driving roller 31 driven roller 32 backup roller 33 primary transfer roller 34 heating roller 35 pressure roller 36 transport roller 37 discharge tray 40 transfer belt 41 transfer roller 42 suction roller A sheet

Claims (10)

In an image forming apparatus including a charging unit that applies a DC voltage in contact with an image carrier, a positively charged single layer type electrophotographic photosensitive member used as the image carrier,
A photosensitive layer containing at least a charge generator, a hole transport agent, an electron transport agent, and a binder resin,
The positive hole transport agent includes at least one of a triarylamine derivative represented by the following general formula (1) and a triarylamine derivative represented by the following general formula (2). Type electrophotographic photoreceptor.

In the general formula (1), R ₁ and R ₂ may each independently have a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a substituent. Selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent, and k and l are each independently 0 to 4 M represents an integer of 1 or more and 3 or less.

In the general formula (2), R ₃ and R ₄ may each independently have a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a substituent. Selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent, and p and q are each independently 0 or more and 4 or less. R and s each independently represent an integer of 1 or more and 3 or less. In the general formula (1), R ₁ and R ₂ are each independently an alkyl group having 1 to 6 carbon atoms,
2. The positively charged single layer type electrophotographic photosensitive member according to claim 1, wherein in the general formula (2), R ₃ and R ₄ are each independently an alkyl group having 1 to 6 carbon atoms. In the general formula (1), k is 0, l is 1, R ₂ is present in the para position with respect to the nitrogen atom to which the phenyl group having R ₂ is bonded,
In the general formula (2), p is 0 or 1, q is 1 or 2,
when p is 1, R ₃ is in the para position relative to the alkenyl group to which the phenyl group having R ₃ is attached;
when q is 1, R ₄ is present in the para position relative to the nitrogen atom to which the phenyl group having R ₄ is attached;
When q is 2, any two R ₄ groups present on the same aromatic ring are present in the ortho position relative to the nitrogen atom to which the phenyl group having R ₄ is bonded, and the two R ₄ groups are the same. However, the positively charged single layer type electrophotographic photosensitive member according to claim 1, which may be different. The hole transport agent is at least one of triarylamine derivatives represented by the general formula (2),
The positively charged single layer type electrophotographic photosensitive member according to any one of claims 1 to 3, wherein, in the general formula (2), r is 1 or 2, and s is 2 or 3.   The hole transport agent includes two or more of a triarylamine derivative represented by the general formula (1) and a triarylamine derivative represented by the general formula (2). 4. The positively charged single layer type electrophotographic photosensitive member according to any one of 3 above. The said electron transport agent is a compound represented by the following general formula (ET-I), or a compound represented by the following general formula (ET-II), It is any one of Claims 1-5. Positively charged single layer type electrophotographic photoreceptor.

In the general formulas (ET-I) and (ET-II), R _{11 to} R ₁₈ may each independently have a hydrogen atom, an alkyl group that may have a substituent, or a substituent. An alkenyl group, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a heterocyclic ring which may have a substituent Represents a group. In the general formulas (ET-I) and (ET-II), R _{11 to} R ₁₈ are each independently an alkyl group having 1 to 10 carbon atoms. Layer type electrophotographic photoreceptor.   A process cartridge comprising the positively charged single layer type electrophotographic photosensitive member according to any one of claims 1 to 7. The image carrier;
The charging unit for charging 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;
An image forming apparatus comprising: a transfer unit that transfers the toner image from the image carrier to a transfer target;
The charging unit applies a DC voltage in contact with the image carrier,
The charging polarity of the charging part is positive.
The image forming apparatus according to claim 1, wherein the image carrier is the positively charged single layer type electrophotographic photosensitive member according to claim 1. The transfer object is a recording medium,
The image forming apparatus according to claim 9, wherein the image carrier is in contact with the recording medium when the transfer unit transfers the toner image from the image carrier to the recording medium.

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