JP6760240B2 - Electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Description

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

The electrophotographic photosensitive member is used as an image carrier in an electrophotographic image forming apparatus (for example, a printer or a multifunction device). The electrophotographic photosensitive member includes a photosensitive layer. As the electrophotographic photosensitive member, for example, a single-layer electrophotographic photosensitive member or a laminated electrophotographic photosensitive member is used. The single-layer electrophotographic photosensitive member includes a photosensitive layer having a function of generating charges and a function of transporting charges. In the laminated electrophotographic photosensitive member, the photosensitive layer includes a charge generation layer having a charge generation function and a charge transport layer having a charge transport function.

Patent Document 1 describes a polyarylate resin having a repeating unit represented by the chemical formula (E-1). Further, an electrophotographic photosensitive member containing the above polyarylate resin is described.

Japanese Unexamined Patent Publication No. 10-288845

However, the electrophotographic photosensitive member described in Patent Document 1 cannot sufficiently suppress the generation of transfer memory.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photosensitive member that suppresses the generation of a transfer memory. Another object of the present invention is to provide a process cartridge and an image forming apparatus that suppress the occurrence of image defects.

The electrophotographic photosensitive member of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single-layer photosensitive layer. The photosensitive layer contains a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The electron transporting agent contains a compound represented by the general formula (ET). The binder resin contains a polyarylate resin. The polyarylate resin is represented by the general formula (1).

In the general formula (ET), at least one of R ¹ , R ² , and R ³ is a carbon having an alkyl group having 4 or more and 10 or less carbon atoms or an aryl group having 6 or more and 14 or less carbon atoms. Represents an alkyl group having 2 or more and 5 or less atoms. The rest of R ¹ , R ² , and R ³ are alkyl groups with 1 to 6 carbon atoms, aryl groups with 6 to 14 carbon atoms, or cycloalkyl groups with 3 to 10 carbon atoms. Represent. At least two of R ¹ , R ² , and R ³ may combine with each other to form a ring. At least one of R ⁴ , R ⁵ , and R ⁶ has an alkyl group having 4 to 10 carbon atoms or an alkyl group having 6 to 14 carbon atoms and having 2 to 5 carbon atoms. Represents a group. The rest of R ⁴ , R ⁵ , and R ⁶ contain alkyl groups with 1 to 6 carbon atoms, aryl groups with 6 to 14 carbon atoms, or cycloalkyl groups with 3 to 10 carbon atoms. Represent. At least two of R ⁴ , R ⁵ , and R ⁶ may combine with each other to form a ring.

In the general formula (1), r and s represent integers of 0 or more and 49 or less. t and u represent integers of 1 or more and 50 or less. r + s + t + u = 100. r + t = s + u. r and t may be the same as or different from each other. s and u may be the same or different from each other. kr represents 2 or 3. kt represents 2 or 3. X and Y are independently represented by the chemical formula (2A), chemical formula (2B), chemical formula (2C), chemical formula (2D), chemical formula (2E), chemical formula (2F), or chemical formula (2G). Represents the basis of.

The process cartridge of the present invention comprises the above-mentioned electrophotographic photosensitive member.

The image forming apparatus of the present invention includes an image carrier, a charged portion, an exposed portion, a developing portion, and a transfer portion. The image carrier is the above-mentioned electrophotographic photosensitive member. The charged portion positively charges the surface of the image carrier. The exposed portion exposes the surface of the charged 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 the transfer body while the surface of the image carrier is in contact with the transfer body.

The electrophotographic photosensitive member of the present invention can suppress the generation of transfer memory. Further, the process cartridge and the image forming apparatus of the present invention can suppress the occurrence of image defects.

(A), (b) and (c) are schematic cross-sectional views showing the structure of the electrophotographic photosensitive member according to the first embodiment of the present invention, respectively. It is a figure which shows an example of the image forming apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the image which image ghost occurred. It is ¹ H-NMR spectrum of the polyarylate resin represented by the chemical formula (R-2). It is ¹ H-NMR spectrum of the polyarylate resin represented by the chemical formula (R-4). It is a ¹ H-NMR spectrum of a quinone derivative represented by the chemical formula (ET-1). It is ¹ H-NMR spectrum of the quinone derivative represented by the chemical formula (ET-6). It is a figure which shows the image for evaluation.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention. In addition, although the description may be omitted as appropriate for the parts where the description is duplicated, the gist of the invention is not limited. In addition, in this specification, a compound and a derivative thereof may be generically referred to by adding "system" after the compound name. When the polymer name is represented by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative.

Hereinafter, an alkyl group having 1 or more and 6 or less carbon atoms, an alkyl group having 1 or more and 4 or less carbon atoms, an alkyl group having 1 or more and 3 or less carbon atoms, an alkyl group having 2 or more and 5 or less carbon atoms, and 4 carbon atoms. Alkyl groups with 10 or more carbon atoms, alkyl groups with 4 or more and 6 or less carbon atoms, alkoxy groups with 1 or more and 4 or less carbon atoms, aryl groups with 6 or more and 14 or less carbon atoms, cycloalkyl with 3 or more carbon atoms and 10 or less carbon atoms The group and the cycloalkylidene group having 5 or more and 7 or less carbon atoms have the following meanings, respectively.

Alkyl groups having 1 to 6 carbon atoms are linear or branched and unsubstituted. Examples of the alkyl group having 1 or more and 6 or less carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an s-butyl group, a t-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. , Or a hexyl group.

Alkyl groups having 1 to 4 carbon atoms are linear or branched and unsubstituted. Examples of the alkyl group having 1 or more and 4 or less carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an s-butyl group, and a t-butyl group.

Alkyl groups having 1 to 3 carbon atoms are linear or branched and unsubstituted. Examples of the alkyl group having 1 or more and 3 or less carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

Alkyl groups having 2 or more and 5 or less carbon atoms are linear or branched chain and unsubstituted. Examples of the alkyl group having 2 or more and 5 or less carbon atoms include an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, a t-butyl group, a pentyl group, an isopentyl group, or a neopentyl group. Can be mentioned.

Alkyl groups having 4 or more and 10 or less carbon atoms are linear or branched chain and unsubstituted. Examples of the alkyl group having 4 or more and 10 or less carbon atoms include n-butyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group and nonyl. A group or a decyl group can be mentioned.

Alkyl groups having 4 or more and 6 or less carbon atoms are linear or branched chain and unsubstituted. Examples of the alkyl group having 4 or more and 6 or less carbon atoms include an n-butyl group, an s-butyl group, a t-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and a hexyl group.

Alkoxy groups having 1 or more and 4 or less carbon atoms are linear or branched and unsubstituted. Examples of the alkoxy group having 1 or more and 4 or less carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an s-butoxy group, and a t-butoxy group.

Aryl groups having 6 to 14 carbon atoms are unsubstituted. Examples of the aryl group having 6 to 14 carbon atoms include an unsubstituted aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms and an unsubstituted aromatic condensed bicycle having 6 to 14 carbon atoms. It is a hydrocarbon group or an unsubstituted aromatic condensed tricyclic hydrocarbon group having 6 to 14 carbon atoms. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

Cycloalkyl groups having 3 or more and 10 or less carbon atoms are unsubstituted. Examples of the cycloalkyl group having 3 or more and 10 or less carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group.

Cycloalkylidene groups having 5 or more and 7 or less carbon atoms are unsubstituted. Examples of the cycloalkylidene group having 5 or more and 7 or less carbon atoms include a cyclopentylidene group, a cyclohexylidene group, and a cycloheptilidene group.

<First embodiment: electrophotographic photosensitive member>
The structure of the electrophotographic photosensitive member (hereinafter, may be referred to as a photosensitive member) according to the first embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing the structure of the photoconductor 1 according to the first embodiment. As shown in FIG. 1A, the photoconductor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a single-layer type photosensitive layer (single-layer photosensitive layer) 3c. As shown in FIG. 1A, the photosensitive layer 3 may be arranged directly on the conductive substrate 2. Further, as shown in FIG. 1B, the photoconductor 1 includes, for example, a conductive substrate 2, an intermediate layer 4 (undercoat layer), and a photosensitive layer 3. As shown in FIG. 1B, the photosensitive layer 3 may be indirectly arranged on the conductive substrate 2. As shown in FIG. 1B, the intermediate layer 4 may be provided between the conductive substrate 2 and the single-layer photosensitive layer 3c. As shown in FIG. 1 (c), the photoconductor 1 may include a protective layer 5 as the outermost surface layer.

The photosensitive layer 3 contains a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The electron transporting agent includes a quinone derivative represented by the general formula (ET) (hereinafter, may be referred to as a quinone derivative (ET)). The binder resin includes a polyarylate resin represented by the general formula (1) (hereinafter, may be referred to as a polyarylate resin (1)). The photoconductor 1 according to the first embodiment suppresses the generation of transfer memory. The reason is presumed as follows.

For convenience, first, the transfer memory will be described. In electrophotographic image formation, for example, a direct transfer type image formation process including the following steps 1) to 4) is carried out.
1) A charging process in which the surface of an image carrier (corresponding to a photoconductor) is positively charged.
2) An exposure step of exposing the surface of a charged image carrier to form an electrostatic latent image on the surface of the image carrier.
3) a developing step of developing an electrostatic latent image as a toner image, and 4) a transfer step of transferring the formed toner image from an image carrier to a recording medium.

In such an image forming process, since the image carrier is rotated and used, a transfer memory due to the transfer step may be generated. Specifically, it is as follows. In the charging step, the surface of the image carrier is uniformly charged to a constant positive electrode potential. Subsequently, through the exposure step and the developing step, in the transfer step, a transfer bias having a polarity opposite to that of charging (negative electrode property) is applied to the image carrier via the recording medium. Specifically, due to the influence of the applied reverse polarity transfer bias, the potential of the non-exposed region (non-image region) on the surface of the image carrier may be significantly reduced, and the reduced state may be maintained. Under the influence of this potential decrease, the non-exposed region has a desired positive electrode potential in the charging step of the next circumference based on the circumference on which the photoconductor forms an image (hereinafter, may be referred to as a reference circumference). It becomes difficult to be charged. On the other hand, even when the transfer bias is applied, the potential of the exposed region (image region) is lowered because the transfer bias is difficult to be directly applied to the surface of the image carrier because the toner adheres to the exposed region. It's hard to do. Therefore, the exposed region is likely to be charged to a desired positive electrode potential in the charging step following the reference circumference. As a result, the charging potential differs between the exposed region and the non-exposed region, and it may be difficult to uniformly charge the surface of the image carrier to a constant positive electrode potential. As described above, the chargeability in the non-exposed region may decrease due to the influence of the potential decrease due to the transfer bias in the image forming process (image formation process) of the reference circumference of the image carrier. The phenomenon in which such a potential difference occurs in the charging potential is called a transfer memory.

Quinone derivatives (ETs) have a π-conjugated system with a relatively large spatial spread. Therefore, the quinone derivative (ET) as an electron transporting agent has excellent carrier (electron) acceptability, and the movement distance of the carrier (electron) in the molecule of the quinone derivative (ET) tends to increase. That is, the intramolecular movement distance of carriers (electrons) tends to increase. Further, the plurality of electron transporting agents (ETs) in the photosensitive layer 3 tend to have π-conjugated systems overlapping each other, and the moving distance of carriers (electrons) between the molecules of the plurality of quinone derivatives (ETs) tends to decrease. .. That is, the intermolecular movement distance of carriers (electrons) tends to decrease. Therefore, the quinone derivative (ET) is considered to improve the acceptability (injectability) and transportability of the carrier (electron) of the photoconductor 1.

The polyarylate resin (1) has a repeating unit derived from a dicarboxylic acid and a repeating unit derived from a diol as represented by the general formula (1). The repeating unit derived from a dicarboxylic acid has a divalent group represented by the chemical formulas (2A) to (2G), and the repeating unit derived from a diol has a cycloalkylidene group. Since the polyarylate resin (1) having such a structure has excellent compatibility with the quinone derivative (ET), the quinone derivative (ET) can be easily dispersed uniformly in the photosensitive layer 3. From the above, it is considered that the photoconductor 1 according to the first embodiment can suppress the generation of the transfer memory.

Hereinafter, the elements of the photoconductor 1 (conductive substrate 2, photosensitive layer 3, and intermediate layer 4) according to the first embodiment will be described. Further, a method for manufacturing the photoconductor 1 will also be described.

[1. Conductive substrate]
The conductive substrate 2 is not particularly limited as long as it can be used as the conductive substrate of the photoconductor 1. As the conductive substrate 2, a conductive substrate made of a material having at least a conductive surface (hereinafter, may be referred to as a conductive material) can be used. An example of the conductive substrate 2 is a conductive substrate made of a conductive material. Another example of a conductive substrate is a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, or indium. Among these conductive materials, one type may be used alone, or two or more types may be used in combination. Examples of the combination of the two or more are alloys (specifically, aluminum alloys, stainless steel, brass, etc.). Among these conductive materials, aluminum or an aluminum alloy is preferable because the transfer of charge 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. Examples of the shape of the conductive substrate 2 include a sheet shape and a drum shape. Further, the thickness of the conductive substrate 2 can be appropriately selected according to the shape of the conductive substrate 2.

[2. Photosensitive layer]
The photosensitive layer 3 contains a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The photosensitive layer 3 may contain an additive. The thickness of the photosensitive layer 3 is not particularly limited as long as the function as the photosensitive layer can be sufficiently exhibited. Specifically, the thickness of the photosensitive layer 3 may be 5 μm or more and 100 μm or less, and preferably 10 μm or more and 50 μm or less.

Hereinafter, charge generators, hole transport agents, electron transport agents, binder resins, and additives will be described.

[2-1. Charge generator]
The charge generator is not particularly limited as long as it is a charge generator for the photoconductor 1. Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaline pigments, trisazo pigments, indigo pigments, azulenium pigments, and cyanine. Pigments, selenium, selenium-tellu, selenium-arsenic, cadmium sulfide, powders of inorganic photoconductive materials such as amorphous silicon, pyrylium salts, anthanthrone pigments, triphenylmethane pigments, slen pigments, toluidine pigments, pyrazoline Examples thereof include based pigments and quinacridone based pigments. Examples of the phthalocyanine pigment include a phthalocyanine pigment or a phthalocyanine derivative pigment. Examples of the phthalocyanine pigment include a metal-free phthalocyanine pigment (more specifically, an X-type metal-free phthalocyanine pigment (x-H ₂ Pc) and the like). Examples of the pigment of the phthalocyanine derivative include a metal phthalocyanine pigment (more specifically, a titanyl phthalocyanine pigment, a V-type hydroxygallium phthalocyanine pigment, and the like). The crystal shape of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes are used. Examples of the crystal shape of the phthalocyanine pigment include α-type, β-type, and Y-type. One type of charge generator may be used alone, or two or more types may be used in combination. Among these charge generators, phthalocyanine pigments are preferable, and X-type metal-free phthalocyanine pigments (x-H ₂ Pc) or Y-type titanyl phthalocyanine pigments (Y-TiOPc) are more preferable. From the viewpoint of further improving the sensitivity characteristics of the photoconductor 1, the charge generator is more preferably a Y-type titanyl phthalocyanine pigment. From the viewpoint of further suppressing the generation of transfer memory, the charge generator is more preferably an X-type metal-free phthalocyanine pigment.

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

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

A charge generator having an absorption wavelength in a desired region may be used alone, or two or more kinds of charge generators may be used in combination. Further, for example, in a digital optical image forming apparatus, it is preferable to use a photoconductor having sensitivity in a wavelength region of 700 nm or more. Examples of the digital optical image forming apparatus include a laser beam printer or a facsimile using a light source such as a semiconductor laser. Therefore, for example, a phthalocyanine pigment is preferable, and an X-type metal-free phthalocyanine pigment or a Y-type titanyl phthalocyanine pigment is more preferable.

Ansanthron pigments or perylene pigments are preferably used as the charge generator for the photoconductor applied to the image forming apparatus using the short wavelength laser light source. Examples of the wavelength of the short wavelength laser include wavelengths of 350 nm or more and 550 nm or less.

The charge generators are, for example, phthalocyanine pigments represented by the chemical formulas (CGM-1) to (CGM-4) (hereinafter, charge generators (CGM-1) to (CGM-4), respectively. There is).

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

[2-2. Hole transporter]
Examples of the hole transporting agent include amine derivatives (more specifically, triarylamine derivatives, etc.); diamine derivatives (more specifically, N, N, N', N'-tetraphenylphenylenediamine derivatives, etc.). N, N, N', N'-tetraphenylnaphthylene diamine derivatives, or N, N, N', N'-tetraphenylphenanthrylene diamine derivatives, etc.); Oxaziazole compounds (more specifically, 2,5-Di (4-methylaminophenyl) -1,3,4-oxadiazole, etc.); Styryl compounds (more specifically, 9- (4-diethylaminostyryl) anthracene, etc.); Carbazole compounds (More specifically, polyvinylcarbazole, etc.); Organic polysilane compounds; Pyrazoline compounds (more specifically, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, etc.); Hydrazone compounds; Indol compounds Examples thereof include oxazole compounds; isooxazole compounds; thiazole compounds; thiadiazol compounds; imidazole compounds; pyrazole compounds; triazole compounds. Among these hole transporting agents, a triarylamine derivative is preferable, a triphenylamine derivative is more preferable, and a triphenylamine derivative represented by the general formula (HT) (hereinafter referred to as a triphenylamine derivative (HT)) will be described. May be more preferred). That is, the charge transport agent preferably contains a triphenylamine derivative (HT).

In the general formula (HT), R ¹¹ , R ¹² , and R ¹³ each independently represent an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. k, p, and q each independently represent an integer of 0 or more and 5 or less. m1 and m2 each independently represent an integer of 1 or more and 3 or less. When k represents an integer of 2 or more, the plurality of R ^11s may be the same or different from each other. When p represents an integer of 2 or more, the plurality of R ^12s may be the same or different from each other. When q represents an integer of 2 or more, the plurality of R ^13s may be the same or different from each other.

In the photoconductor 1 according to the first embodiment, when the photosensitive layer 3 contains a triphenylamine derivative (HT), the generation of transfer memory can be further suppressed. The reason is presumed as follows. A triphenylamine derivative (HT) has a phenylalcapolyenyl group (more specifically, a phenylethenyl group, a phenylbutadienyl group or a phenylbutadienyl group) in two of the three benzene rings in the central triphenylamine structure. It has a phenylhexatrienyl group). Since the π-conjugated system of the triphenylamine derivative (HT) has a relatively large spatial spread, the movement distance of carriers (holes) in the molecule of the triphenylamine derivative (HT) tends to be large. That is, the intramolecular movement distance of carriers (holes) tends to increase. Further, since the π-conjugated systems of the plurality of triphenylamine derivatives (HT) in the photosensitive layer 3 tend to overlap each other, the moving distance of carriers (holes) between the molecules of the plurality of triphenylamine derivatives (HT) is reduced. Tend to do. That is, the intermolecular movement distance of carriers (holes) tends to decrease. On the other hand, since the triphenylamine derivative (HT) has one nitrogen atom in the molecule, the charge bias in the molecule tends to be smaller than that of a compound having two nitrogen atoms in the molecule (for example, a diamine compound). is there. Therefore, the triphenylamine derivative (HT) is considered to improve the acceptability (injectability) and transportability of the carrier (hole) of the photoconductor 1.

Further, since the triphenylamine derivative (HT) has excellent compatibility with the polyarylate resin (1), the triphenylamine derivative (HT) is likely to be uniformly dispersed in the photosensitive layer 3. From the above, it is considered that the photoconductor 1 according to the first embodiment can further suppress the generation of transfer memory when the photosensitive layer 3 contains a triphenylamine derivative (HT).

In the general formula (HT), the alkyl group having 1 to 4 carbon atoms represented by R ¹¹ preferably represents a methyl group, an ethyl group, or an n-butyl group. The alkoxy group represented by R ¹¹ having 1 or more and 4 or less carbon atoms preferably represents an ethoxy group or an n-butoxy group. The substitution position of the substituent represented by R ¹¹ is any of the ortho-position (o-position), meta-position (m-position), or para-position (p-position) of the benzene ring with respect to the bond with the nitrogen atom. Also, it is preferably in the ortho position or the para position.

In the general formula (HT), R ¹¹ represents a group selected from the group consisting of an alkoxy group having 1 or more and 4 or less carbon atoms and an alkyl group having 1 or more and 4 or less carbon atoms, and k represents 1 or 2. , if k is 2, two R ¹ may be the same or different from each other, p and q represent 0, m1 and m2 preferably represents 2 or 3.

From the viewpoint of further suppressing the generation of transfer memory and improving the sensitivity characteristics of the photoconductor 1, in the general formula (HT), R ¹¹ represents an alkyl group having 1 or more carbon atoms and 4 or less carbon atoms, and k is 2. It is preferable to represent it.

From the viewpoint of further suppressing the generation of the transfer memory and improving the sensitivity characteristics of the photoconductor, m1 and m2 preferably represent 3 in the general formula (HT).

Examples of the triphenylamine derivative (HT) include chemical formula (HT-1), chemical formula (HT-2), chemical formula (HT-3), chemical formula (HT-4), chemical formula (HT-5), and chemical formula (HT). -6), or a triphenylamine derivative represented by the chemical formula (HT-7) (hereinafter, triphenylamine derivative (HT-1), triphenylamine derivative (HT-2), triphenylamine derivative (HT-, respectively). 3), triphenylamine derivative (HT-4), triphenylamine derivative (HT-5), triphenylamine derivative (HT-6), and triphenylamine derivative (HT-7) may be described). Can be mentioned.

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

[2-3. Electronic transport agent]
The electron transport agent contains a quinone derivative (ET). The quinone derivative (ET) is represented by the general formula (ET).

In the general formula (ET), at least one of R ¹ , R ² , and R ³ is an alkyl group having 4 or more and 10 or less carbon atoms, or a carbon atom having an aryl group having 6 or more and 14 or less carbon atoms. Represents an alkyl group of number 2 or more and 5 or less. The rest of R ¹ , R ² , and R ³ are alkyl groups with 1 to 6 carbon atoms, aryl groups with 6 to 14 carbon atoms, or cycloalkyl groups with 3 to 10 carbon atoms. Represent. At least two of R ¹ , R ² , and R ³ may combine with each other to form a ring. At least one of R ⁴ , R ⁵ , and R ⁶ has an alkyl group having 4 to 10 carbon atoms or an alkyl group having 6 to 14 carbon atoms and having 2 to 5 carbon atoms. Represents a group. The rest of R ⁴ , R ⁵ , and R ⁶ contain alkyl groups with 1 to 6 carbon atoms, aryl groups with 6 to 14 carbon atoms, or cycloalkyl groups with 3 to 10 carbon atoms. Represent. At least two of R ⁴ , R ⁵ , and R ⁶ may combine with each other to form a ring.

In the general formula (ET), the alkyl groups represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ having 4 or more and 10 or less carbon atoms are alkyl groups having 4 or more and 6 or less carbon atoms. Is preferable, and an n-butyl group, an n-hexyl group, or an isohexyl group is more preferable. At least two of R ¹ , R ² , and R ³ may combine with each other to form a ring. At least two of R ⁴ , R ⁵ , and R ⁶ may combine with each other to form a ring. Examples of such a ring include a cycloalkylidene group or a cyclic hydrocarbon group having 5 or more and 7 or less carbon atoms. Examples of the cycloalkylidene group having 5 or more and 7 or less carbon atoms include a cyclohexylidene group. Examples of the cyclic hydrocarbon group include an adamantyl group.

In the general formula (ET), an alkyl group having 2 or more and 5 or less carbon atoms having an aryl group having 6 or more and 14 or less carbon atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ An alkyl group having a phenyl group and having 2 or more carbon atoms and 5 or less carbon atoms is preferable, and a phenylethyl group is more preferable.

In the general formula (ET), the alkyl group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ having 1 or more and 6 or less carbon atoms includes an alkyl having 1 or more and 3 or less carbon atoms. A group is preferable, and a methyl group is more preferable.

In the general formula (ET), a phenyl group is preferable as the aryl group having 6 to 14 carbon atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ .

In the general formula (ET), at least one of R ¹ , R ² , and R ³ is an alkyl group having 4 or more and 6 or less carbon atoms, or an alkyl group having 2 or more and 5 or less carbon atoms having a phenyl group. , And the rest of R ¹ , R ² , and R ³ preferably represent an alkyl group having 1 or more and 3 or less carbon atoms. At least two of R ¹ , R ² , and R ³ may combine with each other to form a ring. At least one of R ⁴ , R ⁵ , and R ⁶ represents an alkyl group having 4 to 6 carbon atoms or an alkyl group having a phenyl group and having 2 to 5 carbon atoms, and R ⁴ , R. The rest of ⁵ and R ⁶ preferably represent an alkyl group having 1 or more and 3 or less carbon atoms. At least two of R ⁴ , R ⁵ , and R ⁶ may combine with each other to form a ring.

Specific examples of the quinone derivative (ET) shall be described as quinone derivatives represented by the chemical formulas (ET-1) to (ET-7) (hereinafter, quinone derivatives (ET-1) to (ET-7), respectively. There is).

From the viewpoint of further suppressing the generation of transfer memory, of the quinone derivatives (ET-1) to (ET-7), the quinone derivatives (ET-1) to (ET-5) or (ET-7) are preferable, and quinone is preferable. Derivatives (ET-4), (ET-5) or (ET-7) are more preferred.

Of the quinone derivatives (ET-1) to (ET-7), the quinone derivative (ET-1) or (ET-4) is preferable from the viewpoint of improving the sensitivity characteristics of the photoconductor 1.

(Manufacturing method of quinone derivative (ET))
The quinone derivative (ET) is, for example, a reaction represented by the reaction formulas (R-1), (R-2), and (R-3) (hereinafter, reactions (R-1), (R-2), and (R-2), respectively. It may be described as (R-3)) or by a method similar thereto. The method for producing a quinone derivative (ET) includes, for example, a reaction (R-1), a reaction (R-2), and a reaction (R-3).

In reaction (R-1), R ^1, R ^2, and R ³ are the same meanings as R ^1, R ^2, and R ³ in the general formula (1).

In the reaction (R-1), 1 equivalent of the compound (1-naphthol) represented by the chemical formula (A) and the compound (alcohol derivative) represented by the general formula (B) (hereinafter referred to as the alcohol derivative (B)) are described. (May be) 1 equivalent is reacted in the presence of concentrated sulfuric acid in a solvent and may be described as an intermediate compound represented by the general formula (C) (hereinafter, naphthol derivative (C)). ) Obtain 1 equivalent. In the reaction (R-1), it is preferable to add 1 mol or more and 2.5 mol or less of the alcohol derivative (B) to 1 mol of 1-naphthol. When 1 mol or more of the alcohol derivative (B) is added to 1 mol of 1-naphthol, the yield of the naphthol derivative (C) can be easily improved. On the other hand, when 2.5 mol or less of the alcohol derivative (B) is added to 1 mol of 1-naphthol, the unreacted alcohol derivative (B) is unlikely to remain after the reaction (R-1), and the quinone derivative (ET). ) Is easy to purify. The reaction temperature of the reaction (R-1) is preferably room temperature (for example, 25 ° C.). The reaction time of the reaction (R-1) is preferably 1 hour or more and 10 hours or less. The reaction (R-1) can be carried out in a solvent. Examples of the solvent include an aqueous organic acid solution (for example, acetic acid).

More specifically, in the reaction (R-1), 1-naphthol is reacted with the alcohol derivative (B). After the reaction, ion-exchanged water is added to the reaction solution and extracted into an organic layer. Examples of the organic solvent contained in the organic layer include chloroform and ethyl acetate. Add to the organic layer with an aqueous alkaline solution to wash and neutralize the organic layer. Examples of the alkali include alkali metal hydroxides (more specifically, sodium hydroxide or potassium hydroxide, etc.) or alkaline earth metal hydroxides (more specifically, calcium hydroxide, etc.). Can be mentioned.

In reaction (R-2), R ^4, R ^5, and R ⁶ is R ^4, R ⁵ each in formula (1), and the R ⁶ synonymous.

In the reaction (R-2), it is described as 1 equivalent of the compound (1-naphthol) represented by the chemical formula (A) and the compound (alcohol derivative) represented by the general formula (D) (hereinafter, alcohol derivative (D)). (May be) 1 equivalent is reacted in the presence of concentrated sulfuric acid in a solvent and may be described as an intermediate compound represented by the general formula (E) (hereinafter referred to as a naphthol derivative (E)). ) Obtain 1 equivalent. The reaction (R-2) is the same as the reaction (R-1) except that the alcohol derivative (B) is changed to the alcohol derivative (D).

In the reaction (R-3), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are R ¹ , R ² , R ³ , R ⁴ , and R ^{5 in the} general formula (1), respectively. , And R ⁶ are synonymous.

In the reaction (R-3), 1 equivalent of the naphthol derivative (C) and 1 equivalent of the naphthol derivative (E) are reacted in the presence of an oxidizing agent to obtain 1 equivalent of the quinone derivative (ET). In the reaction (R-3), it is preferable to add 1 mol of an oxidizing agent to 1 mol of the naphthol derivative (C) and 1 mol of the naphthol derivative (E). Examples of the oxidizing agent include chloranil, potassium permanganate, and silver oxide. The reaction temperature of the reaction (R-3) is preferably room temperature (for example, 25 ° C.). The reaction time of the reaction (R-3) is preferably 1 hour or more and 10 hours or less. Examples of the solvent include chloroform and dichloromethane.

The production of the quinone derivative (ET) may include other steps as needed. Other steps include, for example, a purification step. Examples of the purification method in the purification step include known methods (more specifically, filtration, chromatography, crystallization, etc.).

The photosensitive layer 3 may contain yet another electron transporting agent in addition to the quinone derivative (ET). Examples of other electron transporting agents include quinone compounds (quinone compounds other than quinone derivatives (ET)), diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3, 4,5,7-Tetranitro-9-fluorenone compound, dinitroanthracene compound, dinitroacridine compound, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroaclysine, succinic anhydride, maleine anhydride Examples thereof include an acid or dibromomaleic anhydride. Examples of the quinone compound include a diphenoquinone compound, an azoquinone compound, an anthraquinone compound, a naphthoquinone compound, a nitroanthraquinone compound, and a dinitroanthraquinone compound. One of these electron transporting agents may be used alone, or two or more thereof may be used in combination.

The content of the electron transporting agent in the photosensitive layer 3 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.

The content of the quinone derivative (ET) in the electron transporting agent is preferably 80% by mass or more, more preferably 90% by mass or more, and 100% by mass, based on the total mass of the electron transporting agent. It is particularly preferable to have.

[2-4. Binder resin]
The binder resin contains a polyarylate resin (1). The polyarylate resin (1) is represented by the general formula (1).

In the general formula (1), r and s represent integers of 0 or more and 49 or less. t and u represent integers of 1 or more and 50 or less. r + s + t + u = 100. r + t = s + u. r and t may be the same as or different from each other. s and u may be the same or different from each other. kr represents 2 or 3. kt represents 2 or 3. X and Y are independently represented by the chemical formula (2A), chemical formula (2B), chemical formula (2C), chemical formula (2D), chemical formula (2E), chemical formula (2F), or chemical formula (2G). Represents the basis of.

In the general formula (1), X and Y are independently represented by the chemical formula (2A), the chemical formula (2C), the chemical formula (2D), the chemical formula (2E), the chemical formula (2F), or the chemical formula (2G). It represents a divalent group, and X and Y are different from each other, and kr and kt preferably represent 3.

From the viewpoint of further suppressing the generation of transfer memory, in the general formula (1), s represents an integer of 1 or more, and one of X and Y represents a divalent group represented by the chemical formula (2C). , X and Y preferably represent a divalent group represented by the chemical formula (2F) or (2G).

The polyarylate resin (1) is a repeating unit represented by the general formula (1-5) with a mole fraction r / (r + t), and is represented by the general formula (1-6) with a mole fraction s / (s + u). Repetitive unit, mole fraction t / (r + t) represented by the general formula (1-7), and mole fraction u / (s + u) represented by the general formula (1-8). Has. Hereinafter, these repeating units may be described as repeating units (1-5), (1-6), (1-7) and (1-8), respectively.

Kr, X, kt, and Y in the repeating units (1-5) to (1-8) are synonymous with kr, X, kt, and Y in the general formula (1), respectively.

The polyarylate resin (1) may have a repeating unit other than the repeating units (1-5) to (1-8). The ratio (molar fraction) of the total amount of substances of the repeating units (1-5) to (1-8) to the total amount of substances of the repeating units in the polyarylate resin (1) is preferably 0.80 or more. 0.90 or more is more preferable, and 1.00 is even more preferable.

The arrangement of the repeating units (1-5) to (1-8) in the polyarylate resin (1) is particularly limited as long as the repeating units derived from the aromatic diol and the repeating units derived from the aromatic dicarboxylic acid are adjacent to each other. Not done. For example, the repeating unit (1-5) is adjacent to the repeating unit (1-6) or the repeating unit (1-8) and is coupled to each other. Similarly, the repeating unit (1-7) is adjacent to the repeating unit (1-6) or the repeating unit (1-8) and is coupled to each other. The polyarylate resin (1) may have a repeating unit other than the repeating units (1-5) to (1-8).

In the general formula (1), r and s represent integers of 0 or more and 49 or less, and t and u represent integers of 1 or more and 50 or less. r + s + t + u = 100. r + t = s + u. s / (s + u) is preferably 0.30 or more and 0.70 or less. s / (s + u) is the ratio of the amount of substance of the repeating unit (1-6) to the total amount of substance of the repeating unit (1-6) and the amount of substance of the repeating unit (1-8) in the polyarylate resin (1). Represents (mole fraction).

The viscosity average molecular weight of the polyarylate resin (1) is preferably 40,000 or more, and preferably 40,000 or more and 52,500 or less. When the viscosity average molecular weight of the polyarylate resin (1) is 40,000 or more, the abrasion resistance of the photoconductor 1 can be enhanced, and the photosensitive layer 3 is less likely to be worn. On the other hand, when the viscosity average molecular weight of the polyarylate resin (1) is 52,500 or less, the polyarylate resin (1) is easily dissolved in the solvent when the photosensitive layer 3 is formed, and the photosensitive layer 3 is easily formed. Tends to be.

Examples of the polyarylate resin (1) are described as polyarylate resins represented by the chemical formulas (R-1) to (R-11) (hereinafter, polyarylate resins (R-1) to (R-11), respectively). There are times when).

From the viewpoint of improving the sensitivity characteristics of the photoconductor 1, the polyarylate resins (R-1) to (R-4) are preferable among the polyarylate resins (R-1) to (R-7), and (R-1) is preferable. ) Or (R-2) is more preferable.

Of the polyarylate resins (R-1) to (R-7), the polyarylate resin (R-4) or (R-7) is preferable from the viewpoint of further suppressing the generation of transfer memory.

(Manufacturing method of polyarylate resin (1))
The method for producing the binder resin (1) is not particularly limited as long as the polyarylate resin (1) can be produced. Examples of these production methods include a method of polycondensing an aromatic diol and an aromatic dicarboxylic acid for forming a repeating unit of the polyarylate resin (1). The method for synthesizing the polyarylate resin (1) is not particularly limited, and a known synthesis method (more specifically, solution polymerization, melt polymerization, interfacial polymerization, etc.) can be adopted. Hereinafter, an example of the method for producing the polyarylate resin (1) will be described.

The polyarylate resin (1) is produced, for example, according to or according to a reaction represented by the reaction formula (R-11) (hereinafter, may be referred to as a reaction (R-11)). The method for producing a polyarylate resin includes, for example, a reaction (R-11).

In the reaction (R-11), kr in the general formula (1-11), kt in the general formula (1-12), X in the general formula (1-9), and in the general formula (1-10). Y is synonymous with kr, kt, X, and Y in the general formula (1), respectively.

In the reaction (R-11), the aromatic dicarboxylic acid represented by the general formula (1-9) and the aromatic dicarboxylic acid represented by the general formula (1-10) (hereinafter, each aromatic dicarboxylic acid (1-). 9) and (1-10)), aromatic diols represented by the general formula (1-11), and aromatic diols represented by the general formula (1-12) (hereinafter, respectively). Aromatic diols (1-11) and (sometimes referred to as (1-12)) are reacted to obtain a polyarylate resin (1).

Examples of the aromatic dicarboxylic acids (1-9) and (1-10) include 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxybiphenyl, terephthalic acid, isophthalic acid, or 2,6-naphthalene. Dicarboxylic acid is mentioned. In the reaction (R-1), other aromatic dicarboxylic acids may be used in addition to the aromatic dicarboxylic acids (1-9) and (1-10). In the reaction (R-1), an aromatic dicarboxylic acid derivative can be used instead of the aromatic dicarboxylic acid. Examples of the aromatic dicarboxylic acid derivative include halogenated alkanoyls or acid anhydrides of aromatic dicarboxylic acids (1-9) and (1-10).

Examples of the aromatic diols (1-11) and (1-12) include 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane or 1,1-bis (4-hydroxy-3-methyl). Phenyl) cyclopentane can be mentioned. In the reaction (R-1), other aromatic diols may be used in addition to the aromatic diols (1-11) and (1-12). Examples of other aromatic diols include bisphenol A, bisphenol S, bisphenol E, and bisphenol F. In the reaction (R-1), an aromatic diol derivative can be used instead of the aromatic diol. Examples of the aromatic diol derivative include diacetate.

The total amount of substance of the aromatic diols (1-11) and (1-12) is 0.9 mol or more with respect to 1 mol of the total amount of substance of the aromatic dicarboxylic acids (1-9) and (1-10). It is preferably 1 mol or less. This is because the polyarylate resin (1) can be easily purified and the yield of the polyarylate resin (1) is improved within the above range.

The reaction (R-11) may proceed in the presence of alkali and catalyst. Examples of the catalyst include tertiary ammonium (more specifically, trialkylamine and the like) or quaternary ammonium salt (more specifically, benzyltrimethylammonium bromide and the like). Examples of the alkali include alkali metal hydroxides (more specifically, sodium hydroxide or potassium hydroxide, etc.) and alkaline earth metal hydroxides (more specifically, calcium hydroxide, etc.). Can be mentioned. The reaction (R-11) may proceed in a solvent and in an atmosphere of an inert gas. Examples of the solvent include water and chloroform. Examples of the inert gas include argon. The reaction time of the reaction (R-11) is preferably 2 hours or more and 5 hours or less. The reaction temperature is preferably 5 ° C. or higher and 25 ° C. or lower.

The production of the polyarylate resin (1) may include other steps, if necessary. Other steps include, for example, a purification step. Examples of the purification method include known methods (more specifically, filtration, chromatography, crystallization, etc.).

As the binder resin, only the polyarylate resin (1) may be used alone, or a resin other than the polyarylate resin (1) (other resins) may be contained within a range that does not impair the effects of the present invention. Good. Examples of other resins include thermoplastic resins (more specifically, polyarylate resins other than polyarylate resin (1), polycarbonate resins, styrene resins, styrene-butadiene copolymers, and styrene-acrylonitrile copolymers. , 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, polyester resin, alkyd resin, polyamide resin, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, polyester resin, etc.), thermosetting resin (more specific) Specifically, silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, or other crosslinkable thermosetting resin, or photocurable resin (more specifically, epoxy-acrylic acid-based resin). , Or urethane-acrylic acid-based copolymer, etc.). These may be used alone or in combination of two or more.

The content ratio of the binder resin is 40% by mass or more with respect to the total mass of all the constituent elements (for example, charge generator, hole transporting agent, electron transporting agent and binder resin) contained in the photosensitive layer 3. Preferably, 80% by mass or more is more preferable.

[2-5. Additive]
At least one of the photosensitive layer 3 and the intermediate layer 4 may contain various additives as long as the electrophotographic characteristics are not adversely affected. Examples of the additive include an antioxidant (more specifically, an antioxidant, a radical scavenger, a quencher, an ultraviolet absorber, etc.), a softener, a surface modifier, a thickener, a thickener, and the like. Dispersion stabilizers, waxes, donors, surfactants, or leveling agents can be mentioned.

[3. Middle layer]
The photoconductor 1 according to the first embodiment may have an intermediate layer 4 (for example, an undercoat layer). The intermediate layer 4 contains, for example, inorganic particles and a resin (resin for the intermediate layer). By interposing the intermediate layer 4, it is possible to suppress an increase in electrical resistance by smoothing the flow of current generated when the photoconductor 1 is exposed while maintaining an insulating state that can suppress the occurrence of current leakage. it can.

Examples of the inorganic particles include particles of a metal (more specifically, aluminum, iron, copper, etc.), metal oxides (more specifically, titanium oxide, alumina, zirconium oxide, tin oxide, or zinc oxide). Etc.), or non-metal oxide (more specifically, silica, etc.) particles. One type of these inorganic particles may be used alone, or two or more types may be used in combination.

[4. Photoreceptor manufacturing method]
A method for manufacturing the photoconductor 1 will be described. The method for producing the photoconductor 1 includes, for example, a step of forming a photosensitive layer.

In the photosensitive layer forming step, a coating liquid for forming the photosensitive layer 3 (hereinafter, may be referred to as a coating liquid for a photosensitive layer) is prepared. The coating liquid for the photosensitive layer is applied onto the conductive substrate 2 to form a coating film. Next, at least a part of the solvent contained in the coating film is removed by drying the coating film by an appropriate method to form the photosensitive layer 3. The coating liquid for the photosensitive layer contains, for example, a charge generator, a hole transport agent, an electron transport agent, a binder resin, and a solvent. Such a coating liquid for a photosensitive layer is prepared by dissolving or dispersing a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin in a solvent. Various additives may be added to the coating liquid for the photosensitive layer, if necessary.

The details of the photosensitive layer forming step will be described below. The solvent contained in the coating liquid for the photosensitive layer is not particularly limited as long as each component contained in the coating liquid for the photosensitive layer can be dissolved or dispersed and the solvent can be easily removed from the coating film when the coating film is dried. Specifically, as the solvent, alcohol (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbon (more specifically, n-hexane, octane, cyclohexane, etc.), Aromatic hydrocarbons (more specifically, benzene, toluene, or xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, or chlorobenzene, etc.), ethers (more specifically, chlorobenzene, etc.) Is dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc.), ketone (more specifically, acetone, methyl ethyl ketone, or cyclohexanone, etc.), ester (more specifically, ethyl acetate, methyl acetate, etc.) ), Dimethylformaldehyde, dimethylformamide, or dimethylsulfoxide. These solvents may be used alone or in combination of two or more. Of these solvents, it is preferable to use a non-halogen solvent.

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

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

The method for applying the coating liquid for the photosensitive layer is not particularly limited as long as the coating liquid for the photosensitive layer can be uniformly applied. 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 at least a part of the solvent contained in the coating film is not particularly limited as long as it can remove at least a part of the solvent in the coating film (more specifically, evaporation or the like). Examples of the removing method include heating, depressurization, or a combination of heating and depressurization. More specifically, a method of heat treatment (hot air drying) using a high temperature dryer or a vacuum dryer can be mentioned. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower, and a time of 3 minutes or longer and 120 minutes or lower.

The method for producing the photoconductor 1 may further include a step of forming the intermediate layer 4 if necessary. A known method can be appropriately selected for the step of forming the intermediate layer 4.

<Second Embodiment: Image forming apparatus>
Hereinafter, one aspect of the image forming apparatus according to the second embodiment will be described with reference to FIG. FIG. 2 is a diagram showing an example of the image forming apparatus 100 according to the second embodiment. FIG. 2 shows an image forming apparatus 100 of a direct transfer method.

The image forming apparatus 100 according to the second embodiment includes an image forming unit 40. The image forming unit 40 includes an image carrier 30, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. The image carrier 30 is a photoconductor according to the first embodiment. The charging unit 42 positively charges the surface of the image carrier 30. The exposure unit 44 exposes the surface of the charged image carrier 30 to form an electrostatic latent image on the surface of the image carrier 30. The developing unit 46 develops the electrostatic latent image as a toner image. The transfer unit 48 transfers the toner image from the image carrier 30 to the recording medium P while the surface of the image carrier 30 and the recording medium P which is the transfer body are in contact with each other. The outline of the image forming apparatus 100 according to the second embodiment has been described above.

The image forming apparatus 100 according to the second embodiment can suppress image defects (for example, image defects caused by the generation of transfer memory). The reason is presumed as follows. The image forming apparatus 100 according to the second embodiment includes the photoconductor according to the first embodiment as the image carrier 30. The photoconductor according to the first embodiment can suppress the generation of transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image defects caused by the generation of the transfer memory.

Image defects caused by the transfer memory will be described. When a transfer memory is generated in the image forming process, a region where a desired potential cannot be obtained in the charging step of the next circumference on the surface of the image carrier 30 with reference to the circumference (reference circumference) of the photoconductor in image forming. The potential tends to be lower than that in the region where a desired potential is obtained in the charging step of the next circumference of the reference circumference. Specifically, the non-exposed region of the reference circumference on the surface of the image carrier 30 tends to have a lower potential during the next round of charging than the exposed region of the reference circumference. Therefore, in the non-exposed region of the reference circumference, the potential during charging tends to decrease as compared with the exposed region of the reference circumference, so that the positively charged toner is easily attracted during development. As a result, an image reflecting the non-image portion (non-exposure region) of the reference circumference is likely to be formed in the image-drawing step after the next circumference. An image defect in which an image reflecting a non-image portion of a reference circumference is formed is an image defect (hereinafter, may be referred to as an image ghost) caused by a transfer memory.

An image in which an image defect has occurred will be described with reference to FIG. FIG. 3 is a diagram showing an image 60 in which an image ghost has occurred. Image 60 includes region 62 and region 64. The region 62 is a region corresponding to one circumference of the image carrier 30, and the region 64 is also a region corresponding to one circumference of the image carrier 30. The region 62 is composed of an image 66 and an image 65. The image 66 is composed of a square solid image (image density 100%). The image 65 is composed of a square white blank image (image density 0%). The region 64 is composed of an image 68 and an image 69. Image 68 is a square halftone image. Image 69 is a square white halftone image in region 64. Image 69 has a higher image density than image 68. The image 69 reflects the image 65 in the non-exposed region of the region 62, and is an image defect (image ghost) darker than the design image density. The image in the region 64 is composed of a full-face halftone image having a uniform image density on the design image.

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

The image forming apparatus 100 includes an image forming unit 40, a transfer belt 50, and a fixing portion 52. The image forming unit 40 is provided for each color. In FIG. 2, since the image forming apparatus 100 includes four image forming units 40a, 40b, 40c and 40d, an image can be formed in four colors.

The image forming apparatus 100 can adopt a direct transfer method. Usually, in an image forming apparatus that employs a direct transfer method, the toner image is transferred to the recording medium while the surface of the image carrier is in contact with the recording medium. Therefore, the image carrier is more affected by the transfer bias than the image carrier mounted on the image forming apparatus that employs the intermediate transfer method. Therefore, it is usually difficult for an image forming apparatus that employs a direct transfer method to suppress the occurrence of image defects due to the generation of a transfer memory. However, the image forming apparatus 100 according to the second embodiment includes the photoconductor according to the first embodiment. Then, the photoconductor according to the first embodiment can suppress the generation of the transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image defects caused by the generation of the transfer memory even if the direct transfer method is adopted.

The image carrier 30 is provided at the center of the image forming unit 40. The image carrier 30 is rotatably provided in the arrow direction (counterclockwise). A charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48 are provided around the image carrier 30 in order from the upstream side in the rotation direction of the image carrier 30 with reference to the charging unit 42. The image forming unit 40 may be further provided with one or both of a cleaning unit (not shown) and a static elimination unit (not shown).

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

The charging unit 42 charges the surface of the image carrier 30 while contacting the surface of the image carrier 30. The charging unit 42 is a so-called contact type charging unit and is a charging roller. Examples of the charging part of the other contact type include a charging brush. Further, the charged portion may be a non-contact type charged portion. Examples of the non-contact type charging unit include a corotron charging unit or a scorotron charging unit.

The contact-type charged portion is less likely to charge the surface of the photoconductor than the non-contact-type charged portion. For example, it is usually difficult to suppress image defects caused by the generation of transfer memory in an image forming apparatus including a charging roller. The image forming apparatus 100 according to the second embodiment includes a photoconductor according to the first embodiment. The photoconductor according to the first embodiment suppresses the generation of transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image defects caused by the generation of the transfer memory even when the contact type charging unit is provided.

The voltage applied by the charging unit 42 may be any of a DC voltage, an AC voltage, and a superposed voltage, and is preferably a DC voltage. The superimposed voltage is a voltage obtained by superimposing an AC voltage on a DC voltage. When the voltage applied to the image carrier 30 by the charging unit 42 is a DC voltage, the amount of wear of the outermost surface layer (for example, a single-layer photosensitive layer) of the photosensitive layer is reduced as compared with the case where the voltage is an AC voltage or a superposed voltage. Can be made to.

When the charging unit 42 applies an AC voltage, the surface potential of the surface of the image carrier 30 tends to be made uniform, but in the image forming apparatus 100 provided with the contact charging type charging unit 42, only the DC voltage is used. Can be charged uniformly even if By applying only a DC voltage to the charging roller, a suitable image can be formed, and the amount of wear of the photosensitive layer can be reduced.

The exposure unit 44 exposes the surface of the charged image carrier 30. As a result, an electrostatic latent image is formed on the surface of the image carrier 30. The electrostatic latent image is formed based on the image data input to the image forming apparatus 100.

The developing unit 46 supplies toner to the surface of the image carrier 30 and develops the electrostatic latent image as a toner image. The developing unit 46 can develop the electrostatic latent image as a toner image while contacting the surface of the image carrier 30.

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

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

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

When the image forming apparatus according to the second embodiment adopts the intermediate transfer method, the primary transfer unit (more specifically, the primary transfer roller) as the transfer unit is the intermediate transfer body (more specifically, the primary transfer roller) from the image carrier to the transfer body. More specifically, the toner image is transferred to an intermediate transfer roller, an intermediate transfer belt, or the like). Specifically, the primary transfer unit applies a primary transfer bias (more specifically, a bias opposite to the charging polarity of the toner) to the intermediate transfer body. As a result, the toner image carried on the image carrier is transferred (primary transfer) to the intermediate transfer body.

The secondary transfer unit as the transfer unit transfers the toner image from the intermediate transfer body to the recording medium. Specifically, the secondary transfer unit (more specifically, the secondary transfer roller) applies a secondary transfer bias (more specifically, a bias opposite to the charging polarity of the toner) to the recording medium. As a result, the toner image primaryly transferred to the intermediate transfer body is transferred to a recording medium (secondary transfer).

The fixing portion fixes the toner image on the recording medium by the fixing treatment by heating and / or pressurization. As a result, an image is formed.

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

The process cartridge contains a unitized part. The unitized portion is the image carrier 30. The unitized portion is the image carrier 30. The unitized portion may include, in addition to the image carrier 30, at least one selected from the group consisting of a charged portion 42, an exposed portion 44, a developing portion 46, and a transfer portion 48. The process cartridge corresponds to, for example, each of the image forming units 40a to 40d. The process cartridge may further include one or both of a cleaning device (not shown) and a static eliminator (not shown). The process cartridge is designed to be detachably attached to the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics of the image carrier 30 deteriorates, the process cartridge including the image carrier 30 can be easily and quickly replaced.

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

[Material of photoconductor]
(Hole transport agent)
The triphenylamine derivatives (HT-1) to (HT-7) described in the first embodiment were prepared. In addition, a hole transport agent (HT-8) or (HT-9) was prepared. The hole transport agent (HT-8) or (HT-9) is represented by the chemical formula (HT-8) or (HT-9), respectively.

(Charge generator)
The charge generators (CGM-1) to (CGM-2) described in the first embodiment were prepared. The charge generator (CGM-1) was an X-type metal-free phthalocyanine represented by the chemical formula (CGM-1).

The charge generator (CGM-2) was a Y-type titanyl phthalocyanine pigment (Y-type titanyl phthalocyanine crystal) represented by the chemical formula (CGM-2). The crystal structure was Y-shaped.

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

(Binder resin)
[Polyarylate resin (R-1) to (R-11)]
The polyarylate resins (R-1) to (R-11) described in the first embodiment were prepared.

[Synthesis of polyarylate resin (R-2)]
A three-necked flask was used as the reaction vessel. This reaction vessel is a 1 L capacity three-necked flask equipped with a thermometer, a three-way cock, and a dropping funnel of 200 mL. 12.24 g (41.28 mmol) of 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 0.062 g (0.413 mmol) of t-butylphenol, and 3.92 g of sodium hydroxide in a reaction vessel. (98 mmol) and 0.120 g (0.384 mmol) of benzyltributylammonium chloride were added. Then, the inside of the reaction vessel was replaced with argon. Then, 300 mL of water was further added to the reaction vessel. The internal temperature of the reaction vessel was raised to 50 ° C. The internal temperature of the reaction vessel was maintained at 50 ° C., and the contents in the reaction vessel were stirred for 1 hour. Then, the internal temperature of the reaction vessel was cooled to 10 ° C. As a result, an alkaline aqueous solution was obtained.

On the other hand, 4.10 g (16.2 mmol) of 2,6-naphthalenedicarboxylic acid dichloride and 4.52 g (16.2 mmol) of biphenyl-4,4'-dicarboxylic acid dichloride were dissolved in 150 mL of chloroform. As a result, a chloroform solution was obtained.

Then, the chloroform solution was slowly added dropwise from the dropping funnel to the alkaline aqueous solution over 110 minutes to initiate the polymerization reaction. The internal temperature in the reaction vessel was adjusted to 15 ± 5 ° C., and the contents of the reaction vessel were stirred for 4 hours to proceed with the polymerization reaction.

Then, the upper layer (aqueous layer) in the contents of the reaction vessel was removed using a decant to obtain an organic layer. Next, 400 mL of ion-exchanged water was put into a three-necked flask having a capacity of 1 L, and then the obtained organic layer was put into it. Further, 400 mL of chloroform and 2 mL of acetic acid were put into a three-necked flask. The contents of the three-necked flask were stirred at room temperature (25 ° C.) for 30 minutes. Then, the upper layer (aqueous layer) in the contents of the three-necked flask was removed using a decant to obtain an organic layer. The organic layer obtained with 1 L of water was washed 5 times with a separating funnel. As a result, an organic layer washed with water was obtained.

Next, the organic layer washed with water was filtered to obtain a filtrate. 1 L of methanol was put into a beaker having a capacity of 3 L. The obtained filtrate was slowly added dropwise to a beaker to obtain a precipitate. The precipitate was filtered off by filtration. The obtained precipitate was vacuum dried at a temperature of 70 ° C. for 12 hours. As a result, a polyarylate resin (R-2) was obtained. The yield of the polyarylate resin (R-2) was 12.2 g, and the yield was 77 mol%.

[Synthesis of polyarylate resins (R-1) and (R-3) to (R-11)]
Change 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane to aromatic diol which is the starting material of polyarylate resin ((R-1) and (R-3) to (R-11)). , 2,6-naphthalenedicarboxylic acid dichloride and biphenyl-4,4'-dicarboxylic acid dichloride to polyarylate resin (R-1) and halogenated alkanoyl which is a starting material of (R-3) to (R-11). Polyarylate resins (R-1) and (R-3) to (R-11) were produced in the same manner as the polyarylate resin (R-2) except for the modification. When a plurality of different types of aromatic carboxylic acid derivatives (halogenated alkanoyl) are used, a plurality of aromatic carboxylic acid derivatives (halogenated alkanoyl) are used at a content ratio corresponding to a mole fraction s / (s + u). Using. When a plurality of different types of aromatic diols were used, a plurality of aromatic diols were used at a content ratio corresponding to a molar fraction r / (r + t).

Next, ¹ H-NMR spectra of the produced polyarylate resins (R-1) to (R-11) were measured using a proton nuclear magnetic resonance spectrometer (manufactured by JASCO Corporation, 300 MHz). CDCl ₃ was used as the solvent. Tetramethylsilane (TMS) was used as the internal standard sample. Among these, polyarylate resins (R-2) and (R-4) are given as typical examples.

4 and 5 show ¹ H-NMR spectra of polyarylate resins (R-2) and (R-4), respectively. In FIGS. 4 and 5, the horizontal axis represents the chemical shift (unit: ppm), and the vertical axis represents the signal strength (unit: arbitrary unit). ¹ It was confirmed by ¹ H-NMR spectrum that polyarylate resins (R-2) and (R-4) were obtained. Similarly, the other polyarylate resins (R-1), (R-3), and (R-5) to (R-11) are also polyarylate resins (R-1) according to ^{1 1} H-NMR spectrum. , (R-3), and (R-5) to (R-11) were confirmed to be obtained.

[Binder resin (RA) to (RF)]
Binder resins (RA) to (RF) were prepared. The binder resins (RA) to (RF) are represented by the chemical formulas (RA) to (RF), respectively.

(Electronic transport agent)
The quinone derivatives (ET-1) to (ET-7) described in the first embodiment were prepared as electron transport agents. In addition, electron transport agents (ET-8), (ET-9) and (ET-10) were prepared. The electron transporting agents (ET-8) to (ET-10) are represented by the chemical formulas (ET-8) to (ET-10), respectively.

[1-1-1. Production of quinone derivative (ET-1)]
The quinone derivative (ET-1) is according to the reactions represented by the reaction formulas (r-1) and the reaction formula (r-3) (hereinafter, may be referred to as reactions (r-1) and (r-3), respectively). ) Was manufactured.

In the reaction (r-1), the naphthol derivative (1A) (1-naphthol) was reacted with the alcohol derivative (1B) to obtain an intermediate product, the naphthol derivative (1C). Specifically, 1.44 g (0.010 mol) of the naphthol derivative (1A), 1.64 g (0.010 mol) of the alcohol derivative (1B), and 0.98 g (0.010 mol) of concentrated acetic acid are placed in a flask. The mixture was charged to prepare an acetic acid solution. 0.98 g (0.010 mol) of concentrated sulfuric acid was added dropwise to the contents of the flask, and the mixture was stirred at room temperature for 8 hours. Ion-exchanged water and chloroform were added to the contents of the flask to obtain an organic layer. The organic layer was washed with aqueous sodium hydroxide solution and neutralized. Subsequently, anhydrous sodium sulfate was added to the organic layer, and the organic layer was dried. The dried organic layer was distilled off under reduced pressure to obtain a crude product containing a naphthol derivative (1C).

In the reaction (r-3), the naphthol derivative (1C) was oxidized to obtain a quinone derivative (ET-1). Specifically, a crude product containing a naphthol derivative (1C) and 100 mL of chloroform were placed in a flask to prepare a chloroform solution. 2.46 g (0.010 mol) of chloranil was added to the contents of the flask, and the mixture was stirred at room temperature for 8 hours. Subsequently, the contents of the flask were filtered to obtain a filtrate. The solvent of the obtained filtrate was distilled off to obtain a residue. Chloroform was used as the developing solvent, and the residue obtained by silica gel column chromatography was purified. As a result, a quinone derivative (ET-1) was obtained. The yield of the quinone derivative (ET-1) was 1.73 g, and the yield of the quinone derivative (ET-1) from the naphthol derivative (1A) was 60 mol%.

[1-1-2. Production of quinone derivatives (ET-2) to (ET-7)]
The quinone derivatives (ET-2) to (ET-7) were produced in the same manner as in the production of the quinone derivative (ET-1) except that the following points were changed. In the production of the quinone derivatives (ET-2) to (ET-7), each raw material was added in the same number of moles as the number of moles of the corresponding raw materials in the production of the quinone derivative (ET-1).

Table 1 shows the naphthol derivative (A), the alcohol derivative (B), and the naphthol derivative (C) in the reaction (r-1). In Table 1, type 1A in the naphthol derivative (A) column indicates a naphthol derivative (1A). Types 1B to 7B in the alcohol derivative (B) column indicate alcohol derivatives (1B) to (7B), respectively. 1C to 7C in the naphthol derivative (C) column indicate naphthol derivatives (1C) to (7C), respectively.

The alcohol derivative (1B) used in the reaction (r-1) was changed to any of the alcohol derivatives (2B) to (7B). As a result, in the reaction (r-1), crude products containing the naphthol derivatives (2C) to (7C) instead of the naphthol derivative (1C) were obtained.

Table 1 shows the naphthol derivative (C) and the quinone derivative (ET) in the reaction (r-3). In Table 1, the types ET-1 to ET-7 in the quinone derivative (ET) column indicate quinone derivatives (ET-1) to (ET-7), respectively. The crude product containing the naphthol derivative (1C) used in the reaction (r-3) was changed to a crude product containing any of the naphthol derivatives (2C) to (7C). As a result, in the reaction (r-3), quinone derivatives (ET-2) to (ET-7) were obtained instead of the quinone derivative (ET-1), respectively.

Table 1 shows the yield and yield of the quinone derivative (ET). In Table 1, the alcohol derivatives (2B) to (7B) are represented by the following chemical formulas (2B) to (7B), respectively. The naphthol derivatives (2C) to (7C) are represented by the following chemical formulas (2C) to (7C), respectively.

Next, ¹ H-NMR spectra of the produced quinone derivatives (ET-1) to (ET-7) were measured using a proton nuclear magnetic resonance spectrometer (manufactured by Nippon Spectroscopy Co., Ltd., 300 MHz). CDCl ₃ was used as the solvent. Tetramethylsilane (TMS) was used as the internal standard sample. Among these, quinone derivatives (ET-1) and (ET-6) are given as typical examples. 6 and 7 show ^{1 1} H-NMR spectra of quinone derivatives (ET-1) and (ET-6), respectively. In FIGS. 6 and 7, the vertical axis represents the signal strength (unit: arbitrary unit), and the horizontal axis represents the chemical shift (unit: ppm).

The chemical shift values of the quinone derivatives (ET-1) and (ET-6) are shown below.
Quinone derivative (ET-1): ^{1 1} H-NMR (300 MHz, CDCl ₃ ) δ = 8.32-8.35 (m, 2H), 8.02 (s, 2H), 7.84-7.88 ( m, 2H), 7.60-7.67 (m, 4H), 7.03-7.18 (m, 10H), 2.39-2.45 (m, 4H), 2.22-2. 29 (m, 4H), 1.38 (s, 12H).
Quinone derivative (ET-6): ^{1 1} H-NMR (300 MHz, CDCl ₃ ) δ = 8.31-8.35 (m, 2H), 7.97 (s, 2H), 7.83-7.87 ( m, 2H), 7.62-7.73 (m, 4H), 7.03-7.25 (m, 10H), 2.48-2.60 (m, 4H), 2.17-2. 37 (m, 4H), 1.86-1.98 (m, 2H), 1.56-1.63 (m, 2H), 1.19-1.33 (m, 22H), 0.81 ( t, 6H).

¹ It was confirmed that the quinone derivatives (ET-1) and (ET-6) were obtained from the ¹ H-NMR spectrum and the chemical shift value. Similarly for the other quinone derivatives (ET-2) to (ET-5) and (ET-7), the quinone derivatives (ET-2) to (ET-5) are obtained according to the ¹ H-NMR spectrum and the chemical shift value, respectively. ) And (2-7) were confirmed.

[Manufacturing of photoconductor (A-1)]
Hereinafter, the production of the photoconductor (A-1) according to Example 1 will be described.

5 parts by mass of charge generator (CGM-1), 50 parts by mass of triphenylamine derivative (HT-5) as hole transport agent, 35 parts by mass of quinone derivative (ET-1) as electron transport agent, as binder resin 100 parts by mass of the polyarylate resin (R-4) and 800 parts by mass of tetrahydrofuran as a solvent were put into the container. The contents of the container are mixed for 50 hours using a ball mill, and the solvent is mixed with the material (charge generator, triphenylamine derivative (HT-5), quinone derivative (ET-1), and polyarylate resin (R-4). )) Was dispersed. As a result, a coating liquid for the photosensitive layer was obtained. A coating liquid for a photosensitive layer was applied onto an aluminum drum-shaped support (diameter 30 mm, total length 238.5 mm) as a conductive substrate by a dip coating method to form a coating film. The coating film was hot air dried at 100 ° C. for 40 minutes. As a result, a single-layer photosensitive layer (thickness 30 μm) was formed on the conductive substrate. As a result, a photoconductor (A-1) was obtained.

[Photoreceptors (A-2) to (A-26) and Photoreceptors (B-1) to (B-13)]
A photoconductor was produced using the same method as that of the photoconductor (A-1) except for the items shown below. Instead of the charge generator (CGM-1), the charge generators listed in Table 2 or Table 3 were used. The electron transporting agent shown in Table 2 or Table 3 was used instead of the quinone derivative (ET-1). The hole transporting agent shown in Table 2 or Table 3 was used instead of the triphenylamine derivative (HT-5). The binder resin shown in Table 2 or Table 3 was used instead of the polyarylate resin (R-4). In this way, the photoconductors (A-2) to (A-26) and the photoconductors (B-1) to (B-11) were obtained.

[Performance evaluation of photoconductor]
(Evaluation of sensitivity characteristics and transfer memory)
Sensitivity characteristics and transfer memory were evaluated for each of the photoconductors (A-1) to (A-26) and (B-1) to (B-13).

The photoconductor was attached to an image forming apparatus (“FS-C5250DN” manufactured by Kyocera Document Solutions Co., Ltd.). This image forming apparatus includes a contact-type charging roller that applies a DC voltage as a charging unit. In addition, this image forming apparatus employs an intermediate transfer method in which a toner image is directly posted on an intermediate transfer belt. The chargeable sleeve was provided on the surface of the chargeable roller and was formed of a chargeable rubber mainly composed of epichlorohydrin resin. The charging voltage of the charged portion was adjusted, and the charging potential (blank paper potential Vs) of the photoconductor corresponding to the position of the developing portion at the time of non-exposure was set to +570V ± 10V. "Kyocera Document Solutions brand paper VM-A4" (A4 size) sold by Kyocera Document Solutions Co., Ltd. was used as the recording medium. The measurement environment was a temperature of 23 ° C. and a relative humidity of 50% RH.

Then, using a bandpass filter, monochromatic light was extracted from the white light of the halogen lamp. The surface potential of the photoconductor corresponding to the developed position when exposed to the extracted monochromatic light with a laser beam having a wavelength of 780 nm, a half width of 20 nm, and a light energy of 1.16 μJ / cm ² was measured. The measured surface potential of the exposed area was defined as the post-exposure potential _VL (unit: V). The measured surface potential of the unexposed area was defined as the blank paper potential V ₃ (unit: V). The post-exposure potential V _L and the blank paper potential V ₃ were measured with the transfer bias turned off. Next, a transfer bias of -2 kV was applied, and the surface potential of the non-exposed region (blank paper portion) was measured with the transfer bias turned on. The surface potential of the obtained non-exposed region (blank paper portion) was defined as the blank paper portion potential V ₄ . From the obtained V ₃ and V ₄ , the transfer memory potential ΔVtc (unit: V) was obtained using the mathematical formula “transfer memory potential ΔVtc = V _4- V ₃ ”.

The obtained post-exposure potential _VL and the transfer memory potential ΔVtc are shown in Tables 2 and 3. The smaller the value of the potential _VL after exposure, the better the sensitivity characteristics of the photoconductor. The smaller the absolute value of the transfer memory potential ΔVtc, the more the generation of the transfer memory is suppressed.

(Evaluation of image defects)
Image defects were evaluated for each of the photoconductors (A-1) to (A-26) and (B-1) to (B-13).

The photoconductor was attached to an image forming apparatus (“FS-C5250DN” manufactured by Kyocera Document Solutions Co., Ltd.). This image forming apparatus includes a contact-type charging roller that applies a DC voltage as a charging unit. In addition, this image forming apparatus employs an intermediate transfer method in which a toner image is directly posted on an intermediate transfer belt. The chargeable sleeve was provided on the surface of the chargeable roller and was formed of a chargeable rubber mainly composed of epichlorohydrin resin. The charging voltage of the charged portion was adjusted, and the charging potential (blank paper potential Vs) of the photoconductor corresponding to the position of the developing portion at the time of non-exposure was set to +570V ± 10V. Laser light was used as the exposure light. This laser light was light obtained by extracting monochromatic light from the white light of a halogen lamp using a bandpass filter, and had a wavelength of 780 nm, a half width of 20 nm, and a light energy of 1.16 μJ / cm ² . "Kyocera Document Solutions brand paper VM-A4" (A4 size) sold by Kyocera Document Solutions Co., Ltd. was used as the recording medium. The measurement environment was a temperature of 23 ° C. and a relative humidity of 50% RH.

First, a printing test was performed. The printing test was a test in which a printing pattern (image density 40%) was continuously printed on a recording medium for one hour. Next, an evaluation image was created. The evaluation image will be described with reference to FIG. FIG. 8 is a diagram showing an evaluation image 70. The evaluation image 70 includes a region 72 and a region 74. The region 72 is a region corresponding to one round of the image carrier. The region 72 is composed of an image 76 and an image 75. The image 76 is composed of a square solid image (image density 100%). The image 75 is composed of a square white blank image (image density 0%). The region 74 is a region corresponding to one round of the image carrier. Region 74 is composed of image 78. Image 78 is composed of a full-face halftone image (image density 40%). First, the image 76 and the image 75 of the region 72 were formed, and then the image 78 of the region 74 was formed. Image 76 is an image corresponding to one round of the photoconductor, and image 78 is an image corresponding to one round of the next round with reference to the round forming the image 76.

The evaluation image was visually observed to confirm the presence or absence of an image corresponding to the image 76 in the region 74. Here, the visual observation is an observation with the naked eye (visual observation) or an observation via a loupe (magnification 10 times, manufactured by TRUSCO, TL-SL10K) (loupe observation). We confirmed the presence or absence of image defects (image ghosts) caused by the transfer memory. The presence or absence of image ghost was evaluated based on the following criteria. The obtained evaluation results are shown in Tables 2 and 3. Evaluations A to C were accepted.

(Evaluation criteria for image ghost)
Rating A (very good): Image ghosts corresponding to image 76 are observed in region 74.
Rating B (good): Image ghosts corresponding to image 76 are slightly observed in region 74.
Evaluation C (normal): An image ghost corresponding to the image 76 is observed in the region 74, but the level is not a problem in practical use.
Evaluation D (bad): The image ghost corresponding to the image 76 is clearly observed in the region 74, which is a practically problematic level. The contrast between the image ghost observed in the image evaluation sample and the non-image portion in which the image ghost was not observed is low.

Table 2 shows the configurations and evaluation results of the photoconductors (A-1) to (A-26), and Table 3 shows the configurations and evaluation results of the photoconductors (B-1) to (B-13). CG-1 to CG-2 in the column "CGM" indicate charge generators (CGM-1) to (CGM-2), respectively. In Tables 2 and 3, HT-1 to HT-7 and HT-8 to HT-9 in the column "HTM" are triphenylamine derivatives (HT-1) to (HT-7) and hole transport agents, respectively. (HT-8) to (HT-9) are shown. ET-1 to ET-10 in the column "ETM" indicate quinone derivatives (ET-1) to (ET-7) and electron transport agents (ET-8) to (ET-10), respectively. In Tables 2 and 3, R-1 to R-11 and RA to RF in the column "Resin" are polyarylate resins (R-1) to (R-11) and binder resins (R-, respectively). A) to (RF) are shown.

As shown in Table 2, in the photoconductors (A-1) to (A-26), the photosensitive layer was a single-layer type photosensitive layer. The photosensitive layer contained a charge generator, a hole transport agent, an electron transport agent, and a binder resin. The electron transporting agent was any one of quinone derivatives (ET-1) to (ET-7). The quinone derivatives (ET-1) to (ET-7) were compounds included in the quinone derivatives represented by the general formula (ET). The binder resin was any of polyarylate resins (R-1) to (R-11). The polyarylate resins (R-1) to (R-11) were all polyarylate resins included in the polyarylate resin represented by the general formula (1). As shown in Table 2, in the photoconductors (A-1) to (A-26), the transfer memory potential is −37 V or more and -14 V or less, and the image evaluation results are A (very good) and B (good). ) Or C (normal).

As shown in Table 3, in the photoconductors (B-1) to (B-11), the photosensitive layer was a single-layer type photosensitive layer. The photosensitive layer contained a charge generator, a hole transport agent, an electron transport agent, and a binder resin. Specifically, in the photoconductors (B-1) to (B-3) and (B-12) to (B-13), the photosensitive layer is an electron transporting agent (ET-8) to (ET-10). It contained any one of the above. The electron transporting agents (ET-8) to (ET-10) were not compounds included in the quinone derivative represented by the general formula (ET). In the photoconductors (B-4) to (B-11), the photosensitive layer contained any one of the binder resins (RA) to (RF). None of the binder resins (RA) to (RF) was a binder resin included in the polyarylate resin represented by the general formula (1). As shown in Table 3, in the photoconductors (B-1) to (B-13), the transfer memory potential was −61 V or more and −49 V or less, and the evaluation result of the image was D (bad).

As is clear from Tables 2 and 3, the photoconductors (photoreceptors (A-1) to (A-26)) according to the first embodiment are the photoconductors (B-1) to (B-13). In comparison, the absolute value of the transfer memory potential was small. The evaluation result of the image was excellent. Therefore, it is clear that the photoconductor according to the present invention suppresses the generation of transfer memory. Further, the image forming apparatus according to the second embodiment (an image forming apparatus equipped with any one of the photoconductors (A-1) to (A-26)) includes the photoconductors (B-1) to (B-). Compared with the image forming apparatus equipped with any one of 13), the evaluation result of the image was excellent. Therefore, it is clear that the image forming apparatus according to the present invention suppresses the occurrence of image defects.

As shown in Table 2, in the photoconductors (A-1) and (A-22), the photosensitive layers contained polyarylate resins (R-4) and (R-7) as binder resins, respectively. The polyarylate resin (R-4) represents an integer in which s is 1 or more, one of X and Y represents a divalent group represented by the chemical formula (2C), and the other of X and Y represents. Was a polyarylate resin representing a divalent group represented by the chemical formula (2F). The polyarylate resin (R-7) represents an integer in which s is 1 or more, one of X and Y represents a divalent group represented by the chemical formula (2C), and the other of X and Y represents. Was a polyarylate resin representing a divalent group represented by the chemical formula (2G). As shown in Table 2, in the photoconductors (A-1) and (A-22), the transfer memory potentials were -20V and -21V, respectively, and the image evaluation result was A (very good).

As shown in Table 2, in the photoconductors (A-17) to (A-21), the photosensitive layers are polyarylate resins (R-1) to (R-3) and (R-5) as binder resins, respectively. And (R-6), any one of them was contained. The polyarylate resins (R-1) to (R-3), (R-5) and (R-6) all represent integers in which s is 1 or more, and one of X and Y has a chemical formula (R). The other of X and Y represented a divalent group represented by 2C) was not a polyarylate resin representing a divalent group represented by the chemical formula (2F) or (2G). As shown in Table 2, in the photoconductors (A-17) to (A-21), the transfer memory potential is −32 V or more and -22 V or less, and the evaluation result of the image is B (good) or C (normal). there were.

As is clear from Table 2, the photoconductors (A-1) and (A-22) had smaller absolute transfer memory potentials than the photoconductors (A-17) to (A-21). In the photoconductor, when the photosensitive layer contains a polyarylate resin represented by the general formula (1) as a binder resin, the polyarylate resin represents an integer in which s is 1 or more in the general formula (1), and X and One of Y represents a divalent group represented by the chemical formula (2C), and the other of X and Y represents a divalent group represented by the chemical formula (2F) or (2G). It is clear that the photosensitive layer suppresses the generation of transfer memory as compared with the photoconductor containing other polyarylate resin.

As shown in Table 2, in the photoconductors (A-1) and (A-8) to (A-13), the photosensitive layer is a triphenylamine derivative (HT-1) to (HT-) as a hole transport agent. It contained any one of 7). The triphenylamine derivatives (HT-1) to (HT-7) were compounds included in the triphenylamine derivatives represented by the general formula (HT). As shown in Table 2, in the photoconductors (A-1) and (A-8) to (A-13), the transfer memory potential is -22V or more and -16V or less, and the evaluation result of the image is A (very much). It was good) or B (good).

As shown in Table 2, in the photoconductors (A-14) and (A-15), the photosensitive layers contained hole transport agents (HT-8) and (HT-9), respectively. The hole transporting agents (HT-8) and (HT-9) were not compounds included in the triphenylamine derivative represented by the general formula (HT). As shown in Table 2, in the photoconductors (A-14) and (A-15), the transfer memory potentials were −35 V and −37 V, and the image evaluation result was C (normal).

As is clear from Table 2, the photoconductors (A-1) and (A-8) to (A-13) have an absolute transfer memory potential as compared with the photoconductors (A-14) and (A-15). The value was small. A photoconductor in which the photosensitive layer contains a triphenylamine derivative represented by the general formula (HT) suppresses the generation of transfer memory as compared with a photoconductor not containing the triphenylamine derivative represented by the general formula (HT). It is clear to do. Further, the image forming apparatus equipped with any one of the photoconductors (A-1) and (A-8) to (A-13) is any one of the photoconductors (A-14) and (A-15). The evaluation result of the image was superior to that of the image forming apparatus equipped with one type.

As shown in Table 2, in the photoconductors (A-12) and (A-13), the photosensitive layer contained triphenylamine derivatives (HT-6) and (HT-7) as hole transport agents, respectively. .. The triphenylamine derivatives (HT-6) and (HT-7) are hole transport agents in which R ¹¹ represents an alkyl group having 1 to 4 carbon atoms and k represents 2 in the general formula (HT). Yes, it was a hole transport agent in which m1 and m2 represent 3. As shown in Table 2, in the photoconductors (A-12) and (A-13), the post-exposure potentials were + 114V and + 113V, respectively.

As shown in Table 2, in the photoconductors (A-8) to (A-11) and (A-1), the photosensitive layers are triphenylamine derivatives (HT-1) to (HT) as hole transport agents, respectively. -5) was included. In all of the triphenylamine derivatives (HT-1) to (HT-5), in the general formula (HT), R ¹¹ represents an alkyl group having 1 to 4 carbon atoms, and k represents a hole transport representing 2. It was neither an agent nor a hole transport agent in which m1 and m2 represent 3. As shown in Table 2, in the photoconductors (A-8) to (A-11) and (A-1), the post-exposure potential was + 117V or more and + 126V or less.

As is clear from Table 2, the photoconductors (A-12) and (A-13) have smaller post-exposure potentials than the photoconductors (A-1) and (A-8) to (A-11). It was. In the photoconductor, when the photosensitive layer contains a triphenylamine derivative represented by the general formula (HT) as a hole transport agent, the triphenylamine derivative has a carbon atom number of 1 in R ¹¹ in the general formula (HT). When m1 and m2 represent 3, the photosensitive layer is a triphenylamine represented by another general formula (HT), which represents an alkyl group of 4 or more or k represents 2. It is clear that the sensitivity characteristics are superior to those of the photoconductor containing the derivative.

The electrophotographic photosensitive member according to the present invention can be used in an image forming apparatus such as a multifunction device.

1 Electrophotographic photosensitive member 2 Conductive substrate 3 Photosensitive layer 3c Single layer photosensitive layer

Claims (17)

An electrophotographic photosensitive member including a conductive substrate and a photosensitive layer.
The photosensitive layer is a single-layer photosensitive layer, and is
The photosensitive layer contains a charge generator, a hole transport agent, an electron transport agent, and a binder resin.
The electron transporting agent contains a compound represented by the general formula (ET) and contains.
The binder resin contains a polyarylate resin and contains.
The polyarylate resin is an electrophotographic photosensitive member represented by the general formula (1).

In the general formula (ET),
At least one of R ¹ , R ² , and R ³ has an alkyl group having 4 to 10 carbon atoms or an alkyl group having 6 to 14 carbon atoms and having 2 to 5 carbon atoms. Represents the group
The rest of R ¹ , R ² , and R ³ are alkyl groups with 1 to 6 carbon atoms, aryl groups with 6 to 14 carbon atoms, or cycloalkyl groups with 3 to 10 carbon atoms. Represent,
At least two of R ¹ , R ² , and R ³ may combine with each other to form a ring.
At least one of R ⁴ , R ⁵ , and R ⁶ has an alkyl group having 4 to 10 carbon atoms or an alkyl group having 6 to 14 carbon atoms and having 2 to 5 carbon atoms. Represents a group
The rest of R ⁴ , R ⁵ , and R ⁶ contain alkyl groups with 1 to 6 carbon atoms, aryl groups with 6 to 14 carbon atoms, or cycloalkyl groups with 3 to 10 carbon atoms. Represent,
At least two of R ⁴ , R ⁵ , and R ⁶ may combine with each other to form a ring.

In the general formula (1),
r and s represent integers of 0 or more and 49 or less.
t and u represent integers of 1 or more and 50 or less.
r + s + t + u = 100,
r + t = s + u,
r and t may be the same or different from each other
s and u may be the same or different from each other
kr represents 2 or 3
kt represents 2 or 3 and represents
X and Y are independently represented by chemical formula (2A), chemical formula (2B), chemical formula (2C), chemical formula (2D), chemical formula (2E), chemical formula (2F), or chemical formula (2G). Represents the basis of.

In the general formula (ET),
At least one of R ¹ , R ² , and R ³ represents an alkyl group having 4 to 6 carbon atoms or an alkyl group having a phenyl group and having 2 to 5 carbon atoms.
The rest of R ¹ , R ² , and R ³ represent alkyl or phenyl groups with 1 to 3 carbon atoms.
At least two of R ¹ , R ² , and R ³ may combine with each other to form a ring.
At least one of R ⁴ , R ⁵ , and R ⁶ represents an alkyl group having 4 to 6 carbon atoms or an alkyl group having a phenyl group and having 2 to 5 carbon atoms.
The rest of R ⁴ , R ⁵ , and R ⁶ represent alkyl or phenyl groups with 1 to 3 carbon atoms.
The electrophotographic photosensitive member according to claim 1, wherein at least two of R ⁴ , R ⁵ , and R ⁶ may be bonded to each other to form a ring. The electron transporting agent has a chemical formula (ET-1), a chemical formula (ET-2), a chemical formula (ET-3), a chemical formula (ET-4), a chemical formula (ET-5), a chemical formula (ET-6), or a chemical formula. The electrophotographic photosensitive member according to claim 1 or 2, represented by (ET-7).

In the general formula (1),
X and Y are independently represented by the chemical formula (2A), the chemical formula (2C), the chemical formula (2D), the chemical formula (2E), the chemical formula (2F), or the chemical formula (2G). Represents a divalent group
X and Y are different from each other
The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein kr and kt represent 3. The polyarylate resin has a chemical formula (R-1), a chemical formula (R-2), a chemical formula (R-3), a chemical formula (R-4), a chemical formula (R-5), a chemical formula (R-6), and a chemical formula (R-6). R-7), according to any one of claims 1 to 4, represented by the chemical formula (R-8), the chemical formula (R-9), the chemical formula (R-10), or the chemical formula (R-11). Electrophotographic photosensitive member.

In the general formula (1),
The electrophotographic photosensitive member according to any one of claims 1 to 5, wherein s / (s + u) is 0.30 or more and 0.70 or less. In the general formula (1),
s represents an integer greater than or equal to 1
One of X and Y represents the divalent group represented by the chemical formula (2C), and the other of X and Y represents the divalent group represented by the chemical formula (2F) or (2G). The electrophotographic photosensitive member according to any one of claims 1 to 5, which represents a valence group. The hole transport agent contains a triphenylamine derivative and contains.
The electrophotographic photosensitive member according to any one of claims 1 to 7, wherein the triphenylamine derivative is represented by the general formula (HT).

In the general formula (HT),
R ¹¹ , R ¹² , and R ¹³ independently represent an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.
k, p, and q each independently represent an integer of 0 or more and 5 or less.
m1 and m2 each independently represent an integer of 1 or more and 3 or less.
When k represents an integer greater than or equal to 2, multiple R ^11s may be the same or different from each other.
When p represents an integer greater than or equal to 2, multiple R ^12s may be the same or different from each other.
When q represents an integer of 2 or more, the plurality of R ^13s may be the same or different from each other. In the general formula (HT),
R ¹¹ represents a group selected from the group consisting of an alkoxy group having 1 or more and 4 or less carbon atoms and an alkyl group having 1 or more and 4 or less carbon atoms.
k represents 1 or 2
If k represents 2, the two R ^11s may be the same or different from each other.
p and q represent 0 and
The electrophotographic photosensitive member according to claim 8, wherein m1 and m2 represent 2 or 3. The triphenylamine derivative has a chemical formula (HT-1), a chemical formula (HT-2), a chemical formula (HT-3), a chemical formula (HT-4), a chemical formula (HT-5), a chemical formula (HT-6), or The electrophotographic photosensitive member according to claim 8 or 9, which is represented by the chemical formula (HT-7).

In the general formula (HT),
R ¹¹ represents an alkyl group having 1 or more carbon atoms and 4 or less carbon atoms.
The electrophotographic photosensitive member according to any one of claims 8 to 10, wherein k represents 2. In the general formula (HT),
The electrophotographic photosensitive member according to any one of claims 8 to 11, wherein m1 and m2 represent 3. The electrophotographic photosensitive member according to any one of claims 1 to 12, wherein the charge generator is an X-type metal-free phthalocyanine pigment or a Y-type titanyl phthalocyanine pigment. A process cartridge comprising the electrophotographic photosensitive member according to any one of claims 1 to 13. Image carrier and
A charged portion that positively charges the surface of the image carrier,
An exposed portion 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 that develops the electrostatic latent image as a toner image,
An image forming apparatus including a transfer unit that transfers the toner image from the image carrier to the transfer body.
The image carrier is the electrophotographic photosensitive member according to any one of claims 1 to 13.
The transfer unit is an image forming apparatus that transfers the toner image to the transfer body while the surface of the image carrier and the transfer body are in contact with each other. The image forming apparatus according to claim 15, wherein the charging portion charges the surface of the image carrier while contacting the surface of the image carrier. The image forming apparatus according to claim 15 or 16, wherein the transfer body is a recording medium.

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