JP6597658B2 - Electrophotographic photosensitive member, image forming apparatus, and process cartridge - Google Patents

Description

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

  The electrophotographic photosensitive member is used as an image carrier in an electrophotographic image forming apparatus (for example, a printer and a multifunction machine). The electrophotographic photoreceptor includes a photosensitive layer. As the electrophotographic photosensitive member, for example, a multilayer type electrophotographic photosensitive member and a single layer type electrophotographic photosensitive member are used. The multilayer electrophotographic photosensitive member includes a photosensitive layer including a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The single-layer type electrophotographic photosensitive member includes a photosensitive layer having a charge generation function and a charge transport function.

  Patent Document 1 describes a hole transport agent having a structure having a triphenylamine skeleton (hereinafter sometimes referred to as a triphenylamine structure). An electrophotographic photoreceptor containing a hole transporting agent having a triphenylamine structure is also described.

JP 2012-27139 A

  However, as a result of studies by the present inventors, the electrophotographic photoreceptor using the hole transport agent having a triphenylamine structure disclosed in Patent Document 1 improves filming resistance while suppressing generation of transfer memory. Proved difficult.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photoreceptor capable of suppressing the generation of a transfer memory and improving the filming resistance. Another object of the present invention is to provide an image forming apparatus and a process cartridge that suppress the occurrence of image defects.

  The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single layer and includes a charge generator, a hole transport agent, an electron transport agent, a binder resin, and filler particles. The said hole transport agent contains the compound represented by following General formula (1). The filler particles include silica particles, resin particles, or a combination thereof. The average primary particle size of the filler particles is 5 nm or more and 10.0 μm or less.

In the general formula (1), R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a carbon which may have a substituent. An alkoxy group having 1 to 6 atoms, an aryl group having 6 to 14 carbon atoms which may have a substituent, an aryloxy group having 6 to 14 carbon atoms which may have a substituent, halogen Represents an atom or a hydrogen atom. R ² and R ³ may combine with each other to form a ring structure. n represents 1 or 2.

  The image forming apparatus of the present invention includes an image carrier, a charging unit, an exposure unit, a developing unit, and a transfer unit. The image carrier is the above-described electrophotographic photosensitive member. The charging unit charges the surface of the image carrier. The charging polarity of the charging unit is positive. The exposure unit exposes the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier. The developing unit develops the electrostatic latent image as a toner image using a developer. The transfer unit transfers the toner image from the image carrier to a transfer target.

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

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

It is a fragmentary sectional view showing an example of the structure of the electrophotographic photosensitive member according to the first embodiment of the present invention. It is a fragmentary sectional view showing an example of the structure of the electrophotographic photosensitive member according to the first embodiment of the present invention. It is a fragmentary sectional view showing an example of the structure of the electrophotographic photosensitive member according to the first embodiment of the present invention. It is a figure which shows an example of the image forming apparatus which concerns on 2nd embodiment of this invention. It is a figure which shows the image in which the image ghost generate | occur | produced. It is a figure which shows the design image of the image for evaluation.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited. Moreover, in this specification, a compound and its derivative may be named generically by attaching "system" after a compound name. When the name of a polymer is expressed by adding “system” after the compound name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

  Hereinafter, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, and 6 carbon atoms The aryloxy group having 14 or less and the halogen atom have the following meanings.

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

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

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

  An aryl group having 6 to 14 carbon atoms is unsubstituted. Examples of the aryl group having 6 to 14 carbon atoms include, for example, an unsubstituted aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms, and an unsubstituted aromatic condensed bicycle having 6 to 14 carbon atoms. Examples thereof include a hydrocarbon group and an unsubstituted aromatic condensed tricyclic hydrocarbon group having 6 to 14 carbon atoms. More specific 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.

  An aryloxy group having 6 to 14 carbon atoms is unsubstituted. The aryloxy group having 6 to 14 carbon atoms is a group in which an oxygen atom is bonded to the terminal of the bond side of the aryl group having 6 to 14 carbon atoms. Examples of the aryloxy group having 6 to 14 carbon atoms include a phenoxy group, a naphthyloxy group, an anthryloxy group, and a phenanthryloxy group.

  As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example.

  In the following, “may have a substituent” means that part or all of the hydrogen atoms of the functional group may be substituted with a substituent.

<First embodiment: electrophotographic photoreceptor>
The structure of the electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor) according to the first embodiment of the present invention will be described. 1, 2, and 3 are partial cross-sectional views illustrating the structure of a photoreceptor 1 that is an example of the first embodiment. As shown in FIG. 1, the photoreceptor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a single photosensitive layer. As shown in FIG. 1, the photosensitive layer 3 may be provided directly on the conductive substrate 2. As shown in FIG. 2, the photoreceptor 1 may include, for example, a conductive substrate 2, an intermediate layer 4 (for example, an undercoat layer), and a photosensitive layer 3. In the example shown in FIG. 2, the photosensitive layer 3 is indirectly provided on the conductive substrate 2 via the intermediate layer 4. Further, as shown in FIG. 3, the photoreceptor 1 may include a protective layer 5 as an outermost surface layer.

  The photosensitive layer 3 contains a charge generating agent, a hole transport agent, an electron transport agent, a binder resin, and filler particles. The hole transport agent contains a compound represented by the following general formula (1) (hereinafter sometimes referred to as compound (1)). The filler particles include silica particles, resin particles, or a combination thereof. The average primary particle size of the filler particles is 5 nm or more and 10.0 μm or less.

In general formula (1), R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 6 carbon atoms which may have a substituent, and a carbon atom which may have a substituent. An alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms which may have a substituent, an aryloxy group having 6 to 14 carbon atoms which may have a substituent, a halogen atom Or a hydrogen atom. R ² and R ³ may combine with each other to form a ring structure. n represents 1 or 2.

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

  The compound (1) contained in the photoreceptor 1 has a π-conjugated system having a relatively large spatial spread because n in the general formula (1) representing the number of double bonds is 1 or 2. Therefore, the compound (1) tends to increase the acceptability of carriers (holes). In addition, since the compound (1) has a relatively large π-conjugated system, the π-conjugated systems of the plurality of compounds (1) are likely to overlap each other, and the carrier (hole) travel distance between the molecules of the plurality of compounds (1). Is relatively small. Therefore, the compound (1) tends to have high carrier (hole) transportability. Furthermore, the compound (1) has lower symmetry than the hole transport agent having a triphenylamine structure. Therefore, the compound (1) is easily dissolved in the solvent used when forming the photosensitive layer 3 and is not easily crystallized even in the binder resin. Thereby, since the compound (1) is relatively uniformly dispersed in the photosensitive layer 3, it is considered that the carrier (hole) transport efficiency is improved. That is, according to the photoreceptor 1, the acceptability and transportability of the carrier (hole) of the compound (1) contained in the photosensitive layer 3 are relatively high, and the compound (1) is relatively contained in the photosensitive layer 3. It is considered that carriers (holes) can be efficiently transported because they are uniformly dispersed.

  In addition, the photosensitive layer 3 of the photoreceptor 1 includes specific filler particles. The filler particles form irregularities on the surface of the photoreceptor 1. As a result, the contact area between a member (more specifically, a cleaning blade or the like) included in the image forming apparatus and the photosensitive member 1 is reduced. As a result, the generation of charges due to frictional charging in the photosensitive layer 3 tends to be suppressed.

  Thus, the photoreceptor 1 tends to efficiently transport carriers (holes) by including the compound (1). In addition, the inclusion of specific filler particles tends to suppress the generation of charges due to frictional charging. Therefore, it is considered that the photoreceptor 1 can reduce the residual charge in the photosensitive layer 3 and can suppress the generation of the transfer memory.

  Further, the photoreceptor 1 can improve the filming resistance. The reason is presumed as follows.

  As described above, the specific filler particles contained in the photosensitive layer 3 of the photoreceptor 1 form irregularities on the surface of the photoreceptor 1. As a result, the contact area between the photosensitive member 1 and a component that causes filming (more specifically, a toner component, paper dust, and the like) is reduced. Thereby, it is considered that the photoreceptor 1 can suppress the adhesion of components that cause filming and can improve the filming resistance.

  Hereinafter, the elements of the photoreceptor 1 (conductive base 2, photosensitive layer 3, and intermediate layer 4) will be described. Further, a method for manufacturing the photoreceptor 1 will 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 photoreceptor 1. As the conductive substrate 2, a conductive substrate formed of a material having at least a surface portion having conductivity can be used. Examples of the conductive substrate 2 include a conductive substrate made of a conductive material (conductive material) and a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, and indium. These conductive materials may be used alone or in combination of two or more. Examples of combinations of two or more include alloys (more specifically, aluminum alloys, stainless steel, brass, etc.). Among these conductive materials, aluminum and aluminum alloys are preferable because charge transfer from the photosensitive layer 3 to the conductive substrate 2 is good.

  The shape of the conductive substrate 2 can be appropriately selected according to the structure of the image forming apparatus to be used. 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 generating agent, a hole transport agent, an electron transport agent, a binder resin, and filler particles. The photosensitive layer 3 may further 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 expressed. Specifically, the thickness of the photosensitive layer 3 may be 5 μm or more and 100 μm or less, and is preferably 10 μm or more and 50 μm or less.

  Hereinafter, the charge generator, the hole transport agent, the electron transport agent, the binder resin, the filler particles, and the additive which is an optional component will be described.

(Charge generator)
The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azurenium pigments, cyanine Pigments, powders of inorganic photoconductive materials (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide and amorphous silicon), pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples thereof include pyrazoline pigments and quinacridone pigments. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the phthalocyanine pigment include metal-free phthalocyanine and metal phthalocyanine represented by the following chemical formula (C-1). Examples of the metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine and chlorogallium phthalocyanine represented by the following chemical formula (C-2). The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape of the phthalocyanine pigment (for example, α type, β type, X type, Y type, V type and II type) is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

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

  In addition, when the photoreceptor 1 is applied to a digital optical image forming apparatus (for example, a laser beam printer and a facsimile using a light source such as a semiconductor laser), a charge generating agent having sensitivity in a wavelength region of 700 nm or more. Is preferably used. In this case, the charge generating agent is preferably a phthalocyanine-based pigment, more preferably a metal-free phthalocyanine and titanyl phthalocyanine, since it has a high quantum yield in a wavelength region of 700 nm or more.

  Further, when the photoreceptor 1 is applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of 350 nm or more and 550 nm or less), for example, an ansanthrone pigment and a perylene system as a charge generator. A pigment is preferably used.

  From the viewpoint of further suppressing the generation of transfer memory by using in combination with the compound (1) and filler particles contained in the photosensitive layer 3, as the charge generating agent, X-type metal-free phthalocyanine, α-type titanyl phthalocyanine, and Y-type are used. Titanyl phthalocyanine is preferred.

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

(Hole transport agent)
The hole transport agent contains a compound (1) represented by the following general formula (1).

In general formula (1), R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 6 carbon atoms which may have a substituent, and a carbon atom which may have a substituent. An alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms which may have a substituent, an aryloxy group having 6 to 14 carbon atoms which may have a substituent, a halogen atom Or a hydrogen atom. R ² and R ³ may combine with each other to form a ring structure. n represents 1 or 2.

In general formula (1), the alkyl group having 1 to 6 carbon atoms represented by R ¹ , R ² and R ³ may have a substituent. Examples of such a substituent include an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, and a halogen atom. .

In general formula (1), the alkoxy group having 1 to 6 carbon atoms represented by R ¹ , R ² and R ³ may have a substituent. Examples of such a substituent include an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, and a halogen atom. .

In general formula (1), the aryl group having 6 to 14 carbon atoms represented by R ¹ , R ² and R ³ may have a substituent. Examples of such a substituent include an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, and 6 to 14 carbon atoms. An aryloxy group, and a halogen atom.

In general formula (1), the aryloxy group having 6 to 14 carbon atoms represented by R ¹ , R ² and R ³ may have a substituent. Examples of such a substituent include an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, and 6 to 14 carbon atoms. An aryloxy group, and a halogen atom.

In general formula (1), R ¹ preferably represents an aryl group having 6 to 14 carbon atoms, which may have a substituent, from the viewpoint of further suppressing the generation of transfer memory. It is more preferably a phenyl group which may have an alkyl group having 1 or more and 3 or less carbon atoms, more preferably a phenyl group which may have a methyl group. More preferably.

In addition, when R ¹ in the general formula (1) represents a phenyl group having a substituent, R ¹ is preferably a group represented by the following general formula (2) from the viewpoint of further suppressing generation of a transfer memory. .

In general formula (2), R ⁴ represents an alkyl group having 1 to 3 carbon atoms. a represents an integer of 0 or more and 5 or less. When a represents an integer of 2 or more and 5 or less, the plurality of R ⁴ may be the same as or different from each other. R ⁵ represents an aryl group having 6 to 14 carbon atoms or a hydrogen atom. s represents an integer of 0 or more and 3 or less. When s represents 2 or 3, several R < ⁵ > may mutually be same or different. * Is a site | part couple | bonded with the nitrogen atom in General formula (1).

In general formula (2), R ⁴ preferably represents a methyl group from the viewpoint of further suppressing generation of a transfer memory. From the same viewpoint, in the general formula (2), a preferably represents 0 or 1, and more preferably represents 0. From the same viewpoint, in the general formula (2), s preferably represents 1 or 2, and more preferably represents 2. From the same viewpoint, in general formula (2), R ⁵ preferably represents a phenyl group or a hydrogen atom.

Examples of R ¹ represented by the general formula (2) include groups represented by the following general formulas (2-1), (2-2), and (2-3). Among these, R ¹ is preferably a group represented by the general formula (2-1) from the viewpoint of further suppressing generation of a transfer memory. In the following general formulas (2-1), (2-2), and (2-3), R ⁴ , R ⁵ , a, s, and * are R ⁴ in the general formula (2), respectively. , R ⁵ , a, s and *.

In general formula (1), R ² and R ³ are each preferably independently an aryl group or a hydrogen atom having 6 to 14 carbon atoms, from the viewpoint of further suppressing the generation of transfer memory, and a phenyl group Or it represents more preferably a hydrogen atom. In particular, further suppressing the occurrence of a transfer memory, one of R ² and R ³ represents a phenyl group, the other R ² and R ³ preferably represents a phenyl group or a hydrogen atom.

Further, R ² and R ³ in the general formula (1) may be bonded to each other to form a ring structure. Also in this case, the generation of the transfer memory can be further suppressed. Such a ring structure may be a monocyclic structure or a polycyclic structure, and may be an alicyclic structure or an aromatic ring structure. The ring structure is preferably a polycyclic structure from the viewpoint of further suppressing the generation of transcription memory, more preferably a polycyclic structure having 8 to 20 carbon atoms constituting the ring, an indene ring, a fluorene ring, and a benzoic ring. A fluorene ring is more preferable, and a fluorene ring is particularly preferable.

  In general formula (1), n preferably represents 2 from the viewpoint of further suppressing the generation of the transfer memory.

  Examples of the compound (1) include compounds represented by the following chemical formulas (HT1) to (HT9) (hereinafter may be referred to as compounds (HT1) to (HT9), respectively).

  Of these compounds, the compound (HT4) and the compound (HT9) are preferable, and the compound (HT9) is more preferable from the viewpoint of further suppressing the generation of the transfer memory.

  The content of the compound (1) as the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less, and 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. More preferred.

  The photosensitive layer 3 may further contain another hole transport agent in addition to the compound (1). As another hole transport agent, for example, a nitrogen-containing cyclic compound other than the compound (1) and a condensed polycyclic compound can be used. Examples of nitrogen-containing cyclic compounds and condensed polycyclic compounds include diamine compounds (more specifically, N, N, N ′, N′-tetraphenylphenylenediamine derivatives, N, N, N ′, N ′. -Tetraphenylnaphthylenediamine derivative, N, N, N ', N'-tetraphenylphenanthrylenediamine derivative, etc.), oxadiazole compounds (more specifically, 2,5-di (4-methylamino) Phenyl) -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.), hydrides ZON compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds and triazole compounds. The content of the compound (1) with respect to the total mass of the hole transport agent is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

(Synthesis Method of Compound (1))
Compound (1) is, for example, according to or according to the reactions represented by the following reaction formulas (R1) and (R2) (hereinafter sometimes referred to as reactions (R1) and (R2), respectively). Synthesized by the method. Hereinafter, the synthesis method of the compound (1) in which n represents 1 in the general formula (1) will be described as an example.

In the reaction (R1), the general formula (A1) and R ² and R ³ in the general formula (B1) are respectively synonymous with R ² and R ³ in the general formula (1).

  In the reaction (R1), 1 mol equivalent of the compound represented by the general formula (A1) (hereinafter referred to as the compound (A1)) and 1 mol equivalent of triethyl phosphite are reacted to give 1 mol. An equivalent amount of the compound represented by the general formula (B1) (hereinafter referred to as the compound (B1)) is obtained. In the reaction (R1), it is preferable to add 1 mol to 2.5 mol of triethyl phosphite with respect to 1 mol of the compound (A1). The reaction temperature for the reaction (R1) is preferably 160 ° C. or higher and 200 ° C. or lower. The reaction time for reaction (R1) is preferably 2 hours or longer and 10 hours or shorter.

In the reaction (R2), R ¹ in the general formula (C1) has the same meaning as R ¹ in the general formula (1). Moreover, R < ¹ >, R < ² > and R < ³ > in General formula (1-1) are synonymous with R < ¹ >, R < ² > and R < ³ > in General formula (1), respectively.

  In the reaction (R2), 1 mol equivalent of the compound (B1) and 1 mol equivalent of the compound represented by the general formula (C1) (hereinafter referred to as the compound (C1)) are reacted to give 1 mol. Equivalent compound (1) represented by general formula (1-1) is obtained. It is preferable to add 1 mol or more and 5 mol or less of compound (B1) with respect to 1 mol of compound (C1). The reaction temperature for reaction (R2) is preferably from −5 ° C. to 50 ° C. The reaction time for reaction (R2) is preferably 10 minutes or longer and 24 hours or shorter. The reaction (R2) may be performed in an atmosphere of an inert gas (for example, argon gas).

  Reaction (R2) may be performed in the presence of a base. Examples of the base include sodium alkoxide (specifically, sodium methoxide, sodium ethoxide, etc.), metal hydride (specifically, sodium hydride, potassium hydride, etc.) and metal salt (specifically, , N-butyllithium, etc.). As the base, sodium methoxide is preferred. These bases may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the base added is preferably 1 mol or more and 3 mol or less with respect to 1 mol of the compound (C1).

  Reaction (R2) may be carried out in a solvent. Examples of the solvent include ethers (specifically, tetrahydrofuran, diethyl ether, dioxane, etc.), halogenated hydrocarbons (specifically, methylene chloride, chloroform, dichloroethane, etc.) and aromatic hydrocarbons (specifically, Are benzene, toluene and the like. As the solvent, tetrahydrofuran is preferred.

  By purifying the reaction product obtained in the reaction (R2) as necessary, the target compound (1) can be isolated. As a purification method, a known method is appropriately employed, and examples thereof include crystallization and silica gel chromatography. Examples of the solvent used for purification include chloroform, hexane, and a mixed solvent of chloroform and hexane.

When synthesizing compound (1) in which n is 2 in general formula (1), compound (A1) in reaction (R1) is changed to the compound represented by general formula (A2) shown below. What is necessary is just to perform reaction similar to the above-mentioned. Incidentally, in the general formula (A2), R ² and R ³ are the same meanings as R ² and R ³ in the general formula (1).

Moreover, when synthesizing the compound (1) in which R ¹ in the general formula (1) is represented by the general formula (2), a reaction represented by the following reaction formula (R3) (hereinafter referred to as reaction (R3)) ) And may be synthesized by a method according to this. Hereinafter, a synthesis method of the compound (1) in which n in the general formula (1) represents 1 and s in the general formula (2) represents 1 will be described as an example.

In the reaction (R3), R ^4, R ⁵ and a in the general formula (B3) and the general formula (1-2) are respectively the same as R ^4, R ⁵ and a in the general formula (2). Also, R ² and R ³ in the general formula (1-2) are the same meanings as R ² and R ³ in the general formula (1).

  In the reaction (R3), 1 molar equivalent of the compound (B1), 1 molar equivalent of the compound represented by the general formula (B3) (hereinafter referred to as the compound (B3)), and 1 molar equivalent of the general formula A compound represented by (C2) (hereinafter referred to as compound (C2)) is reacted to obtain 1 mole equivalent of compound (1) represented by general formula (1-2). It is preferable to add 1 mol or more and 5 mol or less of compound (B1) with respect to 1 mol of compound (C2). It is preferable to add 1 mol or more and 5 mol or less of compound (B3) with respect to 1 mol of compound (C2). About other conditions, it is the same as that of reaction (R2) mentioned above.

In the reaction (R3), the compound (B3) is a reaction similar to the reaction (R1) by changing the compound (A1) of the reaction (R1) to a compound represented by the following general formula (A3), for example. Is obtained. Incidentally, in the general formula (A3), R ^4, R ⁵ and a are respectively the same as the R ^4, R ⁵ and a in the general formula (2).

  In addition, when synthesizing the compound (1) in which s in the general formula (2) represents an integer other than 1, a compound in which the number of double bonds is changed according to the number of s instead of the compound (B3). And a reaction similar to the reaction (R3) may be performed.

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

  Among these electron transport agents, from the viewpoint of efficiently transporting electrons, the following general formula (ET1), general formula (ET2), general formula (ET3), general formula (ET4), and general formula (ET5) The compound represented by these is preferable. Hereinafter, these electron transport agents may be referred to as an electron transport agent (ET1), an electron transport agent (ET2), an electron transport agent (ET3), an electron transport agent (ET4), and an electron transport agent (ET5), respectively. is there.

In General Formula (ET1), R ¹¹ and R ¹² each independently represents an alkyl group having 1 to 6 carbon atoms. In General Formula (ET2), R ¹³ and R ¹⁴ each independently represents an aryl group having 6 to 14 carbon atoms, which may have an alkyl group having 1 to 3 carbon atoms. In the general formula (ET3), R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ each independently represents an alkyl group having 1 to 6 carbon atoms. In General Formula (ET4), R ¹⁹ and R ²⁰ each independently represents an alkyl group having 1 to 6 carbon atoms. R ²¹ represents an aryl group having 6 to 14 carbon atoms which may have a halogen atom. In the general formula (ET5), R ²² represents an aralkyl group having 7 to 17 carbon atoms. An aralkyl group having 7 to 17 carbon atoms is a group in which one of hydrogen atoms of an alkyl group having 1 to 3 carbon atoms is substituted with an aryl group having 6 to 14 carbon atoms.

  Of the electron transfer agents (ET1) to (ET5), the electron transfer agents (ET1), (ET3) and (ET5) are preferable from the viewpoint of further suppressing the generation of the transfer memory.

In general formula (ET1), R ¹¹ and R ¹² preferably represent a branched alkyl group having 1 to 6 carbon atoms, and more preferably a 2-methyl-2-butyl group. Examples of the electron transfer agent (ET1) include an electron transfer agent represented by the following chemical formula (ET1-1) (hereinafter sometimes referred to as an electron transfer agent (ET1-1)).

In General Formula (ET2), R ¹³ and R ¹⁴ preferably represent a phenyl group having a plurality of alkyl groups having 1 to 3 carbon atoms, more preferably a 2-ethyl-6-methylphenyl group. preferable. Examples of the electron transfer agent (ET2) include an electron transfer agent represented by the following chemical formula (ET2-1) (hereinafter sometimes referred to as an electron transfer agent (ET2-1)).

In the general formula ^{(ET3), R 15, R} 16, R 17 and R ¹⁸ are each independently preferably represents a methyl group or t- butyl group. Examples of the electron transfer agent (ET3) include an electron transfer agent represented by the following chemical formula (ET3-1) (hereinafter sometimes referred to as an electron transfer agent (ET3-1)).

In General Formula (ET4), R ¹⁹ and R ²⁰ preferably represent a branched alkyl group having 1 to 6 carbon atoms, and more preferably a t-butyl group. R ²¹ preferably represents a phenyl group having a halogen atom, more preferably a chlorophenyl group, and still more preferably a p-chlorophenyl group. Examples of the electron transfer agent (ET4) include an electron transfer agent represented by the following chemical formula (ET4-1) (hereinafter sometimes referred to as an electron transfer agent (ET4-1)).

In general formula (ET5), R ²² preferably represents a phenylalkyl group, more preferably a benzyl group. Examples of the electron transfer agent (ET5) include an electron transfer agent represented by the following chemical formula (ET5-1) (hereinafter sometimes referred to as an electron transfer agent (ET5-1)).

  The content of the electron transport agent is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 80 parts by mass or less, and more preferably 30 parts by mass or more with respect to 100 parts by mass of the binder resin. The amount is particularly preferably 60 parts by mass or less.

(Binder resin)
Examples of the binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include polycarbonate resin, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic acid polymer, styrene-acrylic acid copolymer, Polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polysulfone resin, diallyl phthalate Examples include resins, ketone resins, polyvinyl butyral resins, polyester resins, and polyether resins. As a thermosetting resin, a silicone resin, an epoxy resin, a phenol resin, a urea resin, and a melamine resin are mentioned, for example. Examples of the photo-curable resin include epoxy acrylate (epoxy compound acrylic acid adduct) and urethane-acrylate (urethane compound acrylic acid adduct). These binder resins may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these resins, the polycarbonate resin is preferable because the photosensitive layer 3 having an excellent balance of workability, mechanical properties, optical properties, and abrasion resistance can be obtained. Examples of the polycarbonate resin include bisphenol Z type polycarbonate resin, bisphenol ZC type polycarbonate resin, bisphenol C type polycarbonate resin and bisphenol A type polycarbonate resin represented by the following chemical formula.

  The viscosity average molecular weight of the binder resin is preferably 30,000 or more, and more preferably 35,000 or more and 55,000 or less. When the viscosity average molecular weight of the binder resin is 35,000 or more, it is easy to improve the abrasion resistance of the photosensitive layer 3. When the viscosity average molecular weight of the binder resin is 55,000 or less, the binder resin is easily dissolved in the solvent when the photosensitive layer 3 is formed, and the viscosity of the coating solution for the photosensitive layer does not become too high. As a result, the photosensitive layer 3 can be easily formed.

(Filler particles)
The filler particles include silica particles, resin particles, or a combination thereof. The photosensitive layer 3 can contain one kind or two or more kinds of filler particles. Further, the photosensitive layer 3 may include only one of silica particles and resin particles as filler particles.

  The silica particles are preferably treated with a surface treatment agent. By treating the silica particles with the surface treatment agent, at least a part of the hydroxyl groups on the surface of the silica particles is silylated. Thereby, there exists a tendency for the hydroxyl group of the surface of a silica particle to decrease. As a result, it is possible to suppress a decrease in electrical characteristics of the photoreceptor 1 due to moisture (humidity). Examples of the surface treatment agent for silica particles include hexamethyldisilazane, N-methyl-hexamethyldisilazane, N-ethyl-hexamethyldisilazane, hexamethyl-N-propyldisilazane, dimethyldichlorosilane, and polydimethylsiloxane. Can be mentioned. The photosensitive layer 3 can contain one kind or two or more kinds of silica particles.

  Examples of the resin constituting the resin particles include a silicone resin, a polyphenylene sulfide resin (hereinafter sometimes referred to as a PPS resin), and a resin containing a fluorine atom (hereinafter sometimes referred to as a fluororesin). Is mentioned. Examples of the fluororesin include polytetrafluoroethylene resin (hereinafter sometimes referred to as PTFE resin), polychlorotrifluoroethylene resin, polyvinylidene fluoride resin, and polyvinyl fluoride resin. The resin particles may contain one kind of these resins alone, or may contain two or more kinds. Moreover, the photosensitive layer 3 can contain 1 type, or 2 or more types of resin particle.

  The filler particles are preferably resin particles from the viewpoint of further improving the filming resistance. When resin particles are used as the filler particles, the resin constituting the resin particles is preferably a silicone resin and a fluororesin from the viewpoint of further suppressing the generation of a transfer memory while further improving filming resistance, and more preferably a fluororesin. Preferably, PTFE resin is more preferable.

  In order to uniformly charge the surface of the photosensitive layer 3, it is preferable to use filler particles having no conductivity.

  The content of the filler particles is preferably 0.5 parts by mass or more and 30.0 parts by mass or less, preferably 10.0 parts by mass or more and 15.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin. More preferably. When the content of the filler particles is 0.5 parts by mass or more with respect to 100.0 parts by mass of the binder resin, the filming resistance can be further improved. When the content of the filler particles is 30.0 parts by mass or less with respect to the binder resin of 100.0 parts by mass, the occurrence of solid foreign matters in the photosensitive layer 3 can be suppressed, so that the appearance defect of the photoreceptor 1 is suppressed. it can.

  The average primary particle size of the filler particles is 5 nm or more and 10.0 μm or less. From the viewpoint of further improving the filming resistance, the average primary particle size of the filler particles is preferably 10 nm or more, and more preferably 100 nm or more. From the viewpoint of further suppressing the generation of the transfer memory, the average primary particle size of the filler particles is preferably 5.0 μm or less.

The average primary particle size of the filler particles is measured by the following method, for example. A plurality of filler particles (powder) are used as a measurement sample. The N ₂ adsorption isotherm at −196 ° C. of the measurement sample is measured. The obtained N ₂ adsorption isotherm is evaluated according to the method of Brunauer, Emmett and Teller, and further according to the t curve method by De Boer. Thereby, the specific surface area of the measurement sample is calculated. From the specific surface area of the obtained measurement sample, the particle size of the measurement sample is calculated according to the formula “d = 6 / ρS”. In the formula, d represents the particle size of the measurement sample, ρ represents the density of the measurement sample, and S represents the specific surface area of the measurement sample. Let the calculated particle diameter of the measurement sample be the average primary particle diameter of the filler particles. In addition, as another method for measuring the average primary particle size of the filler particles, a method by image measurement is also exemplified. Specifically, an image of a considerable number of filler particles is taken using a transmission electron microscope, and the primary particle size of each filler particle in the image is measured. The average primary particle size of the filler particles is calculated by dividing the sum of the measured primary particle sizes by the number of the measured filler particles.

(Additive)
The photosensitive layer 3 may contain various additives as required. Examples of additives include deterioration inhibitors (for example, antioxidants, radical scavengers, singlet quenchers and ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersion stabilizers. , Waxes, acceptors, donors, surfactants, plasticizers, sensitizers and leveling agents. Antioxidants include, for example, hindered phenols (eg, di (tert-butyl) p-cresol), hindered amines, paraphenylenediamine, arylalkanes, hydroquinones, spirochromans, spirodanone or derivatives thereof, organic sulfur compounds, and An organic phosphorus compound is mentioned.

[3. Middle layer]
As described above, the photoreceptor 1 may have the intermediate layer 4 (for example, the undercoat layer). The intermediate layer 4 contains, for example, inorganic particles and a resin (interlayer resin) used for the intermediate layer. When the intermediate layer 4 is interposed, an increase in electrical resistance can be suppressed by smoothing the flow of current generated when the photosensitive member 1 is exposed while maintaining an insulating state capable of suppressing the occurrence of leakage.

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

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

[4. Photoconductor manufacturing method]
A method for manufacturing the photoreceptor 1 will be described. The method for manufacturing the photoreceptor 1 includes, for example, a photosensitive layer forming step. In the photosensitive layer forming step, a photosensitive layer coating solution for forming the photosensitive layer 3 is prepared. Next, a photosensitive layer coating solution is applied onto the conductive substrate 2. Next, the photosensitive layer 3 is formed by removing at least a part of the solvent contained in the applied coating solution for the photosensitive layer by drying by an appropriate method. The photosensitive layer coating solution contains, for example, a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, filler particles, and a solvent. Such a photosensitive layer coating solution is prepared by dissolving or dispersing a charge generating agent, a hole transport agent, an electron transport agent, a binder resin, and filler particles in a solvent. Various additives may be added to the photosensitive layer coating solution as necessary.

  Hereinafter, details of the photosensitive layer forming step will be described. The solvent contained in the photosensitive layer coating solution is not particularly limited as long as each component contained in the photosensitive layer coating solution can be dissolved or dispersed. Examples of the solvent include alcohol (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbon (more specifically, n-hexane, octane, cyclohexane, etc.), aromatic hydrocarbon ( More specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, etc.), ethers (more specifically, dimethyl ether, diethyl ether, Tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc.), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), esters (more specifically, ethyl acetate, methyl acetate, etc.), dimethylformaldehyde, Methyl formamide, and dimethylsulfoxide. These solvents may be used alone or in combination of two or more. Of these solvents, non-halogen solvents are preferably used.

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

  In order to improve the dispersibility of each component or the surface smoothness of the formed photosensitive layer 3, the photosensitive layer coating solution may contain, for example, a surfactant or a leveling agent.

  The method for applying the photosensitive layer coating solution is not particularly limited as long as it can uniformly apply the photosensitive layer coating solution. 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 photosensitive layer coating solution is not particularly limited as long as it is a method capable of evaporating at least a part of the solvent in the photosensitive layer coating solution. Examples of the removal method include heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of heat treatment (hot air drying) using a high-temperature dryer, a vacuum dryer, or the like can be given. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower and a time of 3 minutes or longer and 120 minutes or shorter.

  In addition, the manufacturing method of the photoreceptor 1 may further include a step of forming the intermediate layer 4 as necessary. A known method can be appropriately selected for the step of forming the intermediate layer 4.

  The photoreceptor of this embodiment described above can be suitably used in various image forming apparatuses because it can suppress the generation of a transfer memory and can improve the filming resistance.

<Second Embodiment: Image Forming Apparatus>
Hereinafter, an aspect of the image forming apparatus according to the second embodiment will be described using a tandem color image forming apparatus as an example. FIG. 4 is a diagram illustrating an example of an image forming apparatus according to the second embodiment. The image forming apparatus 100 according to the second embodiment includes an image carrier 30, a charging unit 42, an exposure unit 44, a developing unit 46, and a transfer unit 48. The image carrier 30 is a photoconductor according to the first embodiment. The charging unit 42 charges the surface of the image carrier 30. The charging polarity of the charging unit 42 is positive. The exposure unit 44 exposes the charged surface of the image carrier 30 to form an electrostatic latent image on the surface of the image carrier 30. The developing unit 46 develops the electrostatic latent image as a toner image using a developer. The transfer unit 48 transfers the toner image from the image carrier 30 to the recording medium P that is a transfer target. 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 caused by filming and generation of a 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 has excellent filming resistance and can suppress the generation of a transfer memory. Therefore, the image forming apparatus 100 according to the second embodiment can suppress image defects caused by the occurrence of filming and transfer memory. Hereinafter, an image defect caused by the generation of the transfer memory will be described.

  When a transfer memory is generated in the image forming process, the non-exposure area around the reference circumference (any one round when images are continuously formed) on the surface of the image carrier 30 is the exposure area around the reference circumference. Compared to the above, there is a tendency that the potential decreases at the time of charging the next round of the reference circumference. For this reason, the non-exposed area of the next round of the reference circumference becomes easier to attract the positively charged toner in the developing process than in the normal state. As a result, an image reflecting a non-image portion (non-exposure area) of the reference circumference is easily formed in the next round of the reference circumference. An image defect in which an image reflecting the non-image portion of the reference circumference is formed in the next round is an image defect caused by the transfer memory (hereinafter sometimes referred to as an image ghost).

  The image ghost will be described with reference to FIG. FIG. 5 is a diagram illustrating an image 60 in which an image ghost has occurred. The image 60 includes a region 62 and a region 64. The region 62 is a region corresponding to one rotation of the image carrier (one rotation of the reference circle), and the region 64 is also a region corresponding to one rotation of the image carrier (one rotation of the reference circle). Region 62 includes an image 66. The image 66 is composed of a square solid image. Region 64 includes image 68 and image 69. The image 68 is a square halftone image. The image 69 is a halftone image of an area excluding the image 68 in the area 64. Note that the design image of the region 64 is a full face halftone image. As shown in FIG. 5, the image 69 has a higher image density than the image 68. The image 69 is an image defect (image ghost) that reflects the non-exposed area of the area 62 and becomes darker than the design image density.

  Hereinafter, each unit of the image forming apparatus 100 will be described in detail with reference to FIG.

  The image forming apparatus 100 employs a direct transfer method. That is, in the image forming apparatus 100, the transfer unit 48 transfers the toner image to the recording medium P while bringing the surface of the image carrier 30 into contact with the recording medium P. Usually, in an image forming apparatus that employs a direct transfer system, an image carrier is easily affected by a transfer bias, and thus a transfer memory is likely to occur. In general, in an image forming apparatus that employs a direct transfer method, since the image carrier is in contact with the recording medium, minute components are likely to adhere to the surface of the image carrier, and filming is likely to occur. However, the image forming apparatus 100 according to the second embodiment includes the photoconductor according to the first embodiment as the image carrier 30. The photoconductor according to the first embodiment has excellent filming resistance and can suppress the generation of a transfer memory. Accordingly, when the photoconductor according to the first embodiment is provided as the image carrier 30, even if the image forming apparatus 100 adopts the direct transfer method, the occurrence of image defects due to filming and transfer memory is suppressed. .

  The image forming apparatus 100 includes image forming units 40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing unit 54. Hereinafter, when it is not necessary to distinguish, each of the image forming units 40a, 40b, 40c, and 40d is referred to as an image forming unit 40.

  The image forming unit 40 includes an image carrier 30, a charging unit 42, an exposure unit 44, a developing unit 46, a transfer unit 48, and a cleaning unit 52 that cleans the surface of the image carrier 30. The cleaning unit 52 is a cleaning blade. Normally, in an image forming apparatus provided with a cleaning blade, the image carrier is easily frictionally charged by the contact between the image carrier and the cleaning blade. Therefore, an image forming apparatus provided with a cleaning blade is liable to generate a transfer memory when charges generated by frictional charging remain in the image carrier. However, the image forming apparatus 100 according to the second embodiment includes the photoconductor according to the first embodiment as the image carrier 30. The photoconductor according to the first embodiment can suppress the generation of a transfer memory. Therefore, when the photoconductor according to the first embodiment is provided as the image carrier 30, the occurrence of image defects due to the transfer memory is suppressed even in the image forming apparatus 100 including the cleaning blade.

  The image carrier 30 is provided at the center position of the image forming unit 40 so as to be rotatable in the arrow direction (counterclockwise). Around the image carrier 30, a charging unit 42, an exposure unit 44, a developing unit 46, a transfer unit 48, and a cleaning unit 52 are provided in order from the upstream side in the rotation direction of the image carrier 30 with respect to the charging unit 42. It is done. Note that the image forming unit 40 may further include a charge removal unit (not shown).

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

  The charging unit 42 is a charging roller. The charging roller charges the surface of the image carrier 30 while being in contact with the surface of the image carrier 30. Usually, in an image forming apparatus provided with a charging roller, image defects due to filming and transfer memory are likely to occur. However, the image forming apparatus 100 according to the second embodiment includes the photoconductor according to the first embodiment as the image carrier 30. The photoconductor according to the first embodiment has excellent filming resistance and can suppress the generation of a transfer memory. Therefore, even in the image forming apparatus 100 including the charging roller as the charging unit 42, image defects due to filming and transfer memory are suppressed. In addition, as a charging part of another contact charging system, for example, a charging brush can be cited. The charging unit may be a non-contact type. Examples of the non-contact charging unit include a corotron charging unit and a scorotron charging unit.

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

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

  The developing unit 46 develops the electrostatic latent image as a toner image using a developer. The developer may be a one-component developer or a two-component developer. The developer may include a polymerized toner. Usually, when the developer contains polymerized toner, the polymerized toner remaining on the surface of the image carrier after image formation is difficult to be removed by a cleaning unit (for example, a cleaning blade). In such a case, a minute component adheres to the surface of the image carrier and filming is likely to occur. However, the image forming apparatus 100 according to the second embodiment includes the photoconductor according to the first embodiment as the image carrier 30. The photoconductor according to the first embodiment is excellent in filming resistance. For this reason, the image forming apparatus 100 according to the second embodiment can suppress the occurrence of filming even when the developer includes polymerized toner.

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

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

  The fixing unit 54 heats and / or pressurizes the unfixed toner image transferred to the recording medium P by the transfer unit 48. The fixing unit 54 is, for example, a heating roller and / or a pressure roller. The toner image is fixed on the recording medium P by heating and / or pressurizing the toner image. As a result, an image is formed on the recording medium P.

  The example of the image forming apparatus according to the second embodiment has been described above, but the image forming apparatus according to the second embodiment is not limited to the image forming apparatus 100 described above. For example, the image forming apparatus according to the second embodiment may be a monochrome image forming apparatus. In this case, the image forming apparatus may include only one image forming unit, for example. The image forming apparatus 100 described above is a tandem image forming apparatus. However, the image forming apparatus according to the second embodiment is not limited to this, and may be, for example, a rotary image forming apparatus. The image forming apparatus according to the second embodiment may employ an intermediate transfer method. When the image forming apparatus according to the second embodiment employs an intermediate transfer method, the transfer target corresponds to an intermediate transfer belt.

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

  The process cartridge includes a unitized portion. The unitized portion includes the image carrier 30. The unitized portion may include at least one selected from the group consisting of a charging unit 42, an exposure unit 44, a developing unit 46, a transfer unit 48, and a cleaning unit 52 in addition to the image carrier 30. The process cartridge corresponds to each of the image forming units 40a to 40d, for example. The process cartridge may further include a static eliminator (not shown). The process cartridge is designed to be detachable from the image forming apparatus 100, for example. The process cartridge in this case is easy to handle, and when the sensitivity characteristics of the image carrier 30 are deteriorated, the process cartridge including the image carrier 30 can be easily and quickly replaced.

  The process cartridge according to the third embodiment has been described above. Since the process cartridge according to the third embodiment includes the photoconductor according to the first embodiment as an image carrier, the occurrence of image defects due to filming and transfer memory can be suppressed.

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

<Materials used in Examples and Comparative Examples>
As materials for producing the photosensitive layer, the following charge generator, hole transport agent, electron transport agent, and filler particles were prepared.

[Charge generator]
X-type metal-free phthalocyanine (hereinafter sometimes referred to as charge generation agent (CG1)), α-type titanyl phthalocyanine (hereinafter sometimes referred to as charge generation agent (CG2)), and Y-type titanyl phthalocyanine (Hereinafter, it may be described as a charge generating agent (CG3)).

[Hole transport agent]
As the hole transport agent, the compounds (HT1) to (HT9) described in the first embodiment were prepared. Furthermore, a compound (HTM10) and a compound (HTM11) were also prepared. The compounds (HTM10) and (HTM11) are hole transport agents represented by the following chemical formulas (HTM10) and (HTM11), respectively.

(Synthesis of compounds (HT1) to (HT9))
Compounds (HT1) to (HT9) were each synthesized by the following method. In the following, reactions represented by reaction formulas (R10) to (R16) may be referred to as reactions (R10) to (R16), respectively. The compounds represented by the chemical formulas (A1-1) to (A1-6), (B1-1) to (B1-6), and (C1-1) to (C1-3) are each represented by compound (A1-1). ) To (A1-6), (B1-1) to (B1-6), and (C1-1) to (C1-3). In the following, the yield (%) is based on the number of moles.

  First, as raw materials for synthesizing compounds (HT1) to (HT9), compounds (B1-1) to (B1-6) were synthesized according to the following reactions (R10) to (R15), respectively.

  In reaction (R10), compound (B1-1) was obtained by reacting compound (A1-1) with triethyl phosphite. Specifically, 15.2 g (0.1 mol) of the compound (A1-1) and 50 g (0.3 mol) of triethyl phosphite were charged into a 200-mL flask. The flask contents were stirred at 180 ° C. for 8 hours and then cooled to room temperature. Subsequently, unreacted triethyl phosphite contained in the flask contents was distilled off under reduced pressure. This obtained the compound (B1-1) which is a white liquid. The yield of compound (B1-1) was 22.9 g, and the yield of compound (B1-1) from compound (A1-1) was 90%.

  In the reaction (R11), the same reaction as the reaction (R10) is performed except that 22.9 g of the compound (A1-2) is used instead of 15.2 g of the compound (A1-1) in the reaction (R10). Compound (B1-2) was obtained. The yield of compound (B1-2) was 28.1 g, and the yield of compound (B1-2) from compound (A1-2) was 85%.

  In reaction (R12), reaction is the same as in reaction (R10) except that 22.7 g of compound (A1-3) was used instead of 15.2 g of compound (A1-1) in reaction (R10). Compound (B1-3) was obtained. The yield of compound (B1-3) was 30.5 g, and the yield of compound (B1-3) from compound (A1-3) was 93%.

  In reaction (R13), reaction is performed in the same manner as in reaction (R10) except that 20.3 g of compound (A1-4) was used instead of 15.2 g of compound (A1-1) in reaction (R10). Compound (B1-4) was obtained. The yield of compound (B1-4) was 27.7 g, and the yield of compound (B1-4) from compound (A1-4) was 88%.

  In reaction (R14), the same reaction as in reaction (R10) was performed except that 17.9 g of compound (A1-5) was used instead of 15.2 g of compound (A1-1) in reaction (R10). Compound (B1-5) was obtained. The yield of compound (B1-5) was 21.8 g, and the yield of compound (B1-5) from compound (A1-5) was 78%.

  In reaction (R15), reaction is the same as reaction (R10) except that 25.5 g of compound (A1-6) was used instead of 15.2 g of compound (A1-1) in reaction (R10). Compound (B1-6) was obtained. The yield of compound (B1-6) was 26.3 g, and the yield of compound (B1-6) from compound (A1-6) was 74%.

  Next, compound (HT1) was synthesized according to the following reaction (R16).

  In the reaction (R16), a compound (B1-1) (25.4 g, 0.1 mol) as a phosphonate derivative was added to a two-necked flask having a volume of 500 mL at 0 ° C. The inside of the flask was replaced with argon gas. Thereafter, dry tetrahydrofuran (100 mL) and 28% by mass sodium methoxide (18.6 g, 0.1 mol) were added to the flask and stirred for 30 minutes to prepare a first tetrahydrofuran solution.

  Dry tetrahydrofuran (300 mL) and compound (C1-1) (23.7 g, 0.1 mol) which is an aldehyde derivative were added to another container, and these were stirred to prepare a second tetrahydrofuran solution. The obtained second tetrahydrofuran solution was added to the first tetrahydrofuran solution, and the mixture was stirred at room temperature (25 ° C.) for 12 hours to obtain a mixture.

  The obtained mixture was poured into ion-exchanged water and extracted with toluene to obtain an organic layer. The organic layer was washed 5 times with ion exchange water and dried over anhydrous sodium sulfate, and then the solvent was distilled off. The resulting residue was purified by silica gel chromatography using chloroform / hexane (volume ratio V / V = 1/1) as a developing solvent to obtain a white crystalline compound (HT1). The yield of compound (HT1) was 21.9 g, and the yield was 65%.

  Next, the compound (B1-1) and the addition amount in the reaction (R16) are changed to the phosphonate derivative and the addition amount shown in Table 1, respectively, and the compound (C1-1) and the addition amount are shown in Table 1, respectively. Compounds (HT2) to (HT9) were synthesized in the same manner as described above except that the amount was changed to the addition amount. Table 1 shows the yield and yield of the obtained compounds (HT2) to (HT9). In Table 1, B1-1 to B1-6 in the column “Types of phosphonate derivatives” represent compounds (B1-1) to (B1-6), respectively. C1-1 to C1-3 in the column “Type of aldehyde derivative” indicate compounds (C1-1) to (C1-3), respectively. HT2 to HT9 in the column “type of target compound” indicate compounds (HT2) to (HT9), respectively. Compounds (C1-2) and (C1-3) which are aldehyde derivatives are compounds represented by the following chemical formulas (C1-2) and (C1-3), respectively.

Next, ¹ H-NMR spectra of the synthesized compounds (HT1) to (HT9) 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 an internal standard sample. Of these, the compound (HT4) is given as a representative example. The chemical shift value of the compound (HT4) is shown below.

  Compound (HT4): δ = 7.23-7.39 (m, 15H), 7.06-7.18 (m, 2H), 6.98 (s, 5H), 6.77-6.95 ( m, 4H), 3.53 (t, 2H), 2.81 (t, 2H), 2.00 (quin, 2H).

  From the chemical shift value, it was confirmed that the compound (HT4) was obtained. In the same manner, the compounds (HT1) to (HT3) and (HT5) to (HT9) were confirmed to have compounds (HT1) to (HT3) and (HT5) to (HT9) by chemical shift values. did.

[Electron transport agent]
The electron transport agents (ET1-1), (ET3-1), and (ET5-1) described in the second embodiment were prepared.

[Filler particles]
Filler particles (F1) to (F12) shown in Table 2 were prepared. Table 2 shows the types, materials, average primary particle sizes, varieties, and manufacturers of the filler particles (F1) to (F12). Note that “AEROSIL”, “Trepearl”, and “Lublon” in the column “variety” in Table 2 are registered trademarks.

<Manufacture of photoconductor>
Photoconductors (A-1) to (A-25) and (B-1) to (B-5) were produced by the method described below.

[Production of Photosensitive Member (A-1)]
Charge generating agent (CG1) (3.0 parts by mass), compound (HT1) (60.0 parts by mass) as a hole transporting agent, electron transporting agent (ET1-1) (40.0 parts by mass), , Filler particles (F3) (5.0 parts by mass), bisphenol Z-type polycarbonate resin (“PCZ500” manufactured by Mitsubishi Gas Chemical Co., Ltd., viscosity average molecular weight 50,000) (100.0 parts by mass) as a binder resin, Then, tetrahydrofuran (800.0 parts by mass) as a solvent was charged into the container. Using a rod-shaped ultrasonic disperser, the material in the container and the solvent were mixed for 2 minutes to disperse the material in the solvent. Further, using a ball mill, the material and the solvent were mixed for 50 hours to disperse the material in the solvent. This obtained the coating liquid for photosensitive layers. This photosensitive layer coating solution was applied on an aluminum drum-like support as a conductive substrate by a dip coating method. The applied coating solution for photosensitive layer was dried with hot air at 100 ° C. for 40 minutes. As a result, a photosensitive layer (film thickness: 25 μm) was formed on the conductive substrate to obtain a photoreceptor (A-1) which is a single-layer photoreceptor.

[Production of photoconductors (A-2) to (A-25) and (B-1) to (B-5)]
Photoconductors (A-2) to (A-25) and (B-1) to (B-5) were prepared in the same manner as in the production of photoconductor (A-1) except that the following points were changed. Manufactured.

(change point)
The charge generator (CG1) used for the production of the photoreceptor (A-1) was changed to the charge generator shown in Table 3. The compound (HT1) as the hole transport agent used for the production of the photoreceptor (A-1) was changed to the hole transport agent shown in Table 3. The electron transport agent (ET1-1) used for the production of the photoreceptor (A-1) was changed to the electron transport agent shown in Table 3. The filler particles (F3) and their contents (5.0 parts by mass) used for the production of the photoreceptor (A-1) were changed to the filler particles and their contents shown in Table 3. In Table 3, HT1 to HT9, HTM10, and HTM11 in the column “Hole Transfer Agent” indicate compounds (HT1) to (HT9), (HTM10), and (HTM11), respectively. In Table 3, F1 to F12 in the column “Type of filler particles” indicate filler particles (F1) to (F12), respectively.

<Evaluation of photoreceptor>
[Evaluation 1 (Evaluation on transfer memory)]
As Evaluation 1, each of the photoreceptors (A-1) to (A-25) and (B-1) to (B-5) was evaluated for image defects caused by the transfer memory using the image forming apparatus. did. As the image forming apparatus, a modified machine of “FS-5350DN” manufactured by Kyocera Document Solutions Co., Ltd. was used. This image forming apparatus employs a direct transfer system. In addition, this image forming apparatus includes a contact-type charging roller and a cleaning blade. As the developer, a one-component developer containing a polymerization toner (prototype manufactured by Kyocera Document Solutions Co., Ltd.) was used. As a recording medium, “Kyocera Document Solutions Brand Paper VM-A4” (A4 size) sold by Kyocera Document Solutions Inc. was used.

  First, each photoconductor was mounted on an image forming apparatus, the charging voltage of the charging unit was adjusted, and the charging potential of the photoconductor corresponding to the developing unit position during non-exposure was set to + 570V ± 10V. Next, a printing pattern (image density of 4%) was printed on 1000 recording media at an interval of 15 seconds under an environment of a temperature of 10 ° C. and a humidity of 20% RH, and a printing test was performed. Immediately after this printing test, one evaluation image was printed.

  The design image of the evaluation image will be described with reference to FIG. FIG. 6 is a diagram showing a design image 70 of an evaluation image. The design image 70 includes a region 72 and a region 74. The region 72 is a region corresponding to one rotation of the image carrier (photosensitive member). Region 72 includes an image 76. The image 76 is composed of a square solid image (image density 100%). The region 74 is a region corresponding to one rotation of the image carrier. Region 74 includes an image 78. The image 78 is composed of an entire halftone image (image density 40%). The image 76 is an image corresponding to one turn of the image carrier, and the image 78 is an image corresponding to one turn of the next turn on the basis of the turn forming the image 76.

  The printed evaluation image was visually observed, and in the region 74, it was confirmed whether or not an image defect (image ghost) corresponding to the non-image portion of the region 72 occurred. The presence or absence of image ghost was evaluated based on the following criteria. The obtained results (Evaluation 1) are shown in Table 4.

(Evaluation criteria for evaluation 1)
Evaluation A: No image ghost was observed.
Evaluation B: A slight image ghost was observed.
Evaluation C: Although an image ghost was observed, it was a level with no practical problem.
Evaluation D: Image ghost was clearly observed, and was a practically problematic level.

[Evaluation 2 (Evaluation on filming resistance)]
As Evaluation 2, each of the photoreceptors (A-1) to (A-25) and (B-1) to (B-5) was evaluated for image defects caused by filming using an image forming apparatus. did. The same image forming apparatus, developer, and recording medium as in Evaluation 1 were used.

  First, each photoconductor was mounted on an image forming apparatus, the charging voltage of the charging unit was adjusted, and the charging potential of the photoconductor corresponding to the developing unit position during non-exposure was set to + 570V ± 10V. Subsequently, a printing pattern (image density: 1%) was printed at an interval of 15 seconds on 5000 recording media in an environment of a temperature of 30 ° C. and a humidity of 80% RH, and a printing test was performed. One hour after the end of the printing test, one halftone image (image density 25%) was printed and used as an evaluation image. The image for evaluation was visually observed to confirm the presence or absence of image defects (streaks and dash marks) due to filming. A streak is a line parallel to the printing direction. A dash mark is a point or a short line arranged parallel to the printing direction. The presence or absence of image defects was evaluated based on the following criteria. The obtained results (Evaluation 2) are shown in Table 4.

(Evaluation criteria for evaluation 2)
Evaluation A: Muscle and dash marks were not observed.
Evaluation B: Slight streaks and dash marks were observed.
Evaluation C: Although streaks and dash marks were partially observed, they were at a level of no practical problem.
Evaluation D: Streaks and dash marks were clearly observed as a whole, and there were practically problematic levels.

[Comprehensive evaluation]
From the results of Evaluation 1 and Evaluation 2, the photoreceptors were comprehensively evaluated based on the following criteria. A photoreceptor having an overall evaluation of A, B or C was evaluated as good. In addition, a photoreceptor with a comprehensive evaluation of D was evaluated as defective.

(Evaluation criteria for comprehensive evaluation)
Evaluation A: One of Evaluation 1 and Evaluation 2 was Evaluation A, and the other of Evaluation 1 and Evaluation 2 was Evaluation A or B.
Evaluation B: Both Evaluation 1 and Evaluation 2 were Evaluation B.
Evaluation C: One of Evaluation 1 and Evaluation 2 was Evaluation C, and the other of Evaluation 1 and Evaluation 2 was Evaluation A, B, or C.
Evaluation D: At least one of Evaluation 1 and Evaluation 2 was Evaluation D.

  As shown in Table 3, in the photoreceptors (A-1) to (A-25), the photosensitive layer contains any of the compounds (HT1) to (HT9) included in the general formula (1). It was. In the photoreceptors (A-1) to (A-25), the photosensitive layer is any one of filler particles (F1) to (F10) that are silica particles or resin particles having an average primary particle size of 5 nm to 10.0 μm. Contained.

  As shown in Table 4, in the photoreceptors (A-1) to (A-25), the overall evaluation result of the transfer memory and the filming resistance was either A (good) or C (good). .

  As shown in Table 3, in the photoreceptors (B-1) and (B-2), the photosensitive layer contained one of the compounds (HTM10) and (HTM11) not included in the general formula (1). . In the photoreceptor (B-3), the photosensitive layer did not contain filler particles. In the photoreceptors (B-4) and (B-5), the photosensitive layer contained any one of filler particles (F11) and (F12) that did not correspond to either silica particles or resin particles.

  As shown in Table 4, in the photoreceptors (B-1) to (B-5), the overall evaluation results of the transfer memory and the filming resistance were all D (defect).

  As is clear from the above results, the photoconductors (A-1) to (A-25) suppress the occurrence of transfer memory and are resistant to the photoconductors (B-1) to (B-5). Excellent filming properties.

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

1 electrophotographic photoreceptor 2 conductive substrate 3 photosensitive layer

Claims (16)

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer,
The photosensitive layer is a single layer and includes a charge generator, a hole transport agent, an electron transport agent, a binder resin and filler particles,
The hole transport agent includes a compound represented by the following general formula (1),
The filler particles include silica particles, resin particles or a combination thereof,
The electrophotographic photosensitive member, wherein the filler particles have an average primary particle size of 5 nm to 10.0 μm.

(In the general formula (1),
R ¹ , R ² and R ³ are each independently an alkyl group having 1 to 6 carbon atoms which may have a substituent, or an alkoxy having 1 to 6 carbon atoms which may have a substituent. A group, an aryl group having 6 to 14 carbon atoms that may have a substituent, an aryloxy group having 6 to 14 carbon atoms that may have a substituent, a halogen atom, or a hydrogen atom;
R ² and R ³ may combine with each other to form a ring structure;
n represents 1 or 2. )   2. The electrophotographic photosensitive member according to claim 1, wherein the content of the filler particles is 0.5 part by mass or more and 30.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin. The filler particles include the resin particles,
The electrophotographic photosensitive member according to claim 1, wherein the resin particles contain fluorine atoms.   The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the charge generating agent includes X-type metal-free phthalocyanine, α-type titanyl phthalocyanine, Y-type titanyl phthalocyanine, or a combination thereof. In the general formula (1), R ¹ represents an aryl group having up to 14 which may having 6 or more carbon atoms have a substituent, an electrophotographic photosensitive member according to any one of claims 1 to 4 . The electrophotographic photosensitive member according to claim 5, wherein in the general formula (1), R ¹ represents a phenyl group which may have an alkyl group having 1 to 3 carbon atoms. The electrophotographic photoreceptor according to claim 5, wherein R ¹ in the general formula (1) is a group represented by the following general formula (2).

(In the general formula (2),
R ⁴ represents an alkyl group having 1 to 3 carbon atoms,
a represents an integer of 0 to 5,
when a represents an integer of 2 or more and 5 or less, the plurality of R ⁴ may be the same or different from each other;
R ⁵ represents an aryl group having 6 to 14 carbon atoms or a hydrogen atom,
s represents an integer of 0 to 3,
when s represents 2 or 3, the plurality of R ⁵ may be the same as or different from each other;
* Is a site | part couple | bonded with the nitrogen atom in the said General formula (1). ) In the general formula (1), R ² and R ³ each independently represents an aryl group or a hydrogen atom having 6 to 14 carbon atoms, electrophotography according to any one of claims 1 to 7 Photoconductor. The electrophotographic photosensitive member according to any one of claims 1 to 7, wherein, in the general formula (1), R ² and R ³ are bonded to each other to form a ring structure. The hole transport agent has the following chemical formula (HT1), chemical formula (HT2), chemical formula (HT3), chemical formula (HT4), chemical formula (HT5), chemical formula (HT6), chemical formula (HT7), chemical formula (HT8), or chemical formula (HT8). The electrophotographic photosensitive member according to claim 5, comprising a compound represented by HT9).

An image carrier;
A charging unit that charges the surface of the image carrier;
An exposure unit that exposes the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier;
A developing unit that develops the electrostatic latent image as a toner image using a developer;
An image forming apparatus comprising: a transfer unit that transfers the toner image from the image carrier to a transfer target;
The image carrier is the electrophotographic photosensitive member according to any one of claims 1 to 10,
The image forming apparatus, wherein a charging polarity of the charging unit is positive. The transfer object is a recording medium,
The image forming apparatus according to claim 11, wherein the transfer unit transfers the toner image to the recording medium while bringing the surface of the image carrier into contact with the recording medium.   The image forming apparatus according to claim 11, wherein the charging unit charges the surface of the image carrier while being in contact with the surface of the image carrier.   The image forming apparatus according to claim 11, wherein the developer includes a polymerized toner. A cleaning unit for cleaning the surface of the image carrier;
The image forming apparatus according to claim 11, wherein the cleaning unit is a cleaning blade.   A process cartridge comprising the electrophotographic photosensitive member according to claim 1.

Images