JP2014106362A - Electrophotographic photoreceptor, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having excellent sensitivity characteristics, and an image forming apparatus including the electrophotographic photoreceptor as an image carrier and having excellent sensitivity characteristics.SOLUTION: There is provided an electrophotographic photoreceptor having (1) a lamination-type photosensitive layer obtained by sequentially laminating a charge generating layer containing at least a charge generating material, and a charge transport layer containing at least a charge transport material and a binder resin, formed on a conductive substrate, or having (2) a single layer-type photosensitive layer containing at least a charge generating material, a charge transport material, and a binder resin, formed on a conductive substrate. The charge transport material used includes an imino quinone derivative having a specific structure as an electron transport material.

Description

  The present invention relates to an electrophotographic photoreceptor and an image forming apparatus.

  As an electrophotographic photoreceptor provided in an electrophotographic image forming apparatus, an inorganic photoreceptor having a photosensitive layer made of an inorganic material such as selenium or amorphous silicon, and mainly a binder resin, a charge generating material, a charge transporting material, etc. And an organic photoreceptor having a photosensitive layer made of any of the above organic materials. Among these photoreceptors, organic photoreceptors are widely used because they are easier to manufacture than inorganic photoreceptors, and the material of the photosensitive layer can be selected from a wide range of materials, and the degree of freedom in design is high. Yes.

  Electron transport materials and hole transport materials are used as charge transport materials for such organophotoreceptors, and the use of various naphthoquinone derivatives has been proposed for electron transport materials because of their excellent charge transport ability. ing. And as a specific example of a naphthoquinone derivative suitable as an electron transport material, the following compound is mentioned (for example, refer patent document 1, paragraph 0036).

Japanese Patent Laid-Open No. 09-151157

  However, the naphthoquinone derivative described in Patent Document 1 may have difficulty in obtaining good sensitivity characteristics depending on the combination with the binder resin constituting the photosensitive layer. For this reason, there is a need for an electron transport material that provides an electrophotographic photosensitive member that is more excellent in sensitivity characteristics than the naphthoquinone derivative disclosed in Patent Document 1.

  An object of the present invention is to provide an electrophotographic photoreceptor excellent in sensitivity characteristics. Another object of the present invention is to provide an image forming apparatus including the above-described electrophotographic photosensitive member as an image carrier.

  In the electrophotographic photoreceptor, the present inventors sequentially laminated 1) a charge generation layer containing at least a charge generation material, and a charge transport layer containing at least a charge transport material and a binder resin on a conductive substrate. A multilayer photosensitive layer or 2) a single-layer photosensitive layer containing at least a charge generation material, a charge transport material, and a binder resin, and a charge transport material containing an iminoquinone derivative having a specific structure as an electron transport material is used. As a result, the present inventors have found that the above problems can be solved, and have completed the present invention. More specifically, the present invention provides the following.

（一般式（１）中、Ｒ^１及びＲ^２は、それぞれ、水素原子、ハロゲン原子、ニトロ基、炭素数１以上１２以下のアルキル基、炭素数１以上１２以下のアルキル基で置換されていてもよい炭素数６以上１２以下のアリール基、炭素数６以上１２以下のアラルキル基、炭素数３以上１０以下のシクロアルキル基、及び炭素数１以上６以下のアルコキシ基からなる群より選択される基であり、
Ｒ^３及びＲ^４は、それぞれ、水素原子、炭素数１以上１２以下のアルキル基、炭素数１以上１２以下のアルキル基で置換されていてもよい炭素数６以上１２以下のアリール基、炭素数６以上１２以下のアラルキル基、炭素数３以上１０以下のシクロアルキル基、及び炭素数１以上６以下のアルコキシ基からなる群より選択される基である。） The first aspect of the present invention is:
An electrophotographic photoreceptor having a photosensitive layer formed on a conductive substrate,
The photosensitive layer is
1) a layered photosensitive layer in which a charge generation layer containing at least a charge generation material, a charge transport layer containing at least a charge transport material and a binder resin are sequentially laminated, or
2) A single-layer type photosensitive layer containing at least a charge generating material, a charge transporting material, and a binder resin,
The charge transport material relates to an electrophotographic photosensitive member containing an iminoquinone derivative represented by the following general formula (1) as an electron transport material.

(In General Formula (1), R ¹ and R ² are each substituted with a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. Or an aryl group having 6 to 12 carbon atoms, an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. Group,
R ³ and R ⁴ are each a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms that may be substituted with an alkyl group having 1 to 12 carbon atoms, It is a group selected from the group consisting of an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. )

The second aspect of the present invention is:
An image carrier;
A charging unit for charging the surface of the image carrier;
An exposure unit for exposing a surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier;
A developing unit for developing the electrostatic latent image as a toner image;
An image forming apparatus comprising: a transfer unit configured to transfer the toner image from the image carrier to a transfer target; wherein the image carrier is the electrophotographic photosensitive member according to the first aspect. About.

  According to the present invention, an electrophotographic photoreceptor excellent in sensitivity characteristics can be provided. Further, according to the present invention, it is possible to provide an image forming apparatus excellent in sensitivity characteristics provided with the above-described electrophotographic photosensitive member as an image carrier.

It is a figure which shows the structure of a laminated type photoreceptor. It is a figure which shows the structure of a single layer type photoreceptor. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention.

  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.

（一般式（１）中、Ｒ^１及びＲ^２は、それぞれ、水素原子、ハロゲン原子、ニトロ基、炭素数１以上１２以下のアルキル基、炭素数１以上１２以下のアルキル基で置換されていてもよい炭素数６以上１２以下のアリール基、炭素数６以上１２以下のアラルキル基、炭素数３以上１０以下のシクロアルキル基、及び炭素数１以上６以下のアルコキシ基からなる群より選択される基であり、
Ｒ^３及びＲ^４は、それぞれ、水素原子、炭素数１以上１２以下のアルキル基、炭素数１以上１２以下のアルキル基で置換されていてもよい炭素数６以上１２以下のアリール基、炭素数６以上１２以下のアラルキル基、炭素数３以上１０以下のシクロアルキル基、及び炭素数１以上６以下のアルコキシ基からなる群より選択される基である。） [First Embodiment]
The first embodiment of the present invention is an electrophotographic photosensitive member in which a photosensitive layer is formed on a conductive substrate, the photosensitive layer contains a charge transport material, and the charge transport material is an electron transport material. The present invention relates to an electrophotographic photoreceptor containing an iminoquinone derivative represented by (1).

(In General Formula (1), R ¹ and R ² are each substituted with a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. Or an aryl group having 6 to 12 carbon atoms, an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. Group,
R ³ and R ⁴ are each a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms that may be substituted with an alkyl group having 1 to 12 carbon atoms, It is a group selected from the group consisting of an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. )

Specifically, the first embodiment of the present invention is an electrophotographic photosensitive member in which a photosensitive layer is formed on a conductive substrate, and the photosensitive layer includes:
1) a layered photosensitive layer in which a charge generation layer containing at least a charge generation material, a charge transport layer containing at least a charge transport material and a binder resin are sequentially laminated, or
2) A single-layer type photosensitive layer containing at least a charge generating material, a charge transporting material, and a binder resin,
The present invention relates to an electrophotographic photoreceptor in which the charge transport material contains an iminoquinone derivative represented by the above formula (1) as an electron transport material. The structure of the electrophotographic photosensitive member according to the first embodiment of the present invention is not particularly limited, and may be a multilayer type electrophotographic photosensitive member or a single layer type electrophotographic photosensitive member.

  In the specification and claims of this application, a resin contained in the charge transport layer of the multilayer photoreceptor or the photosensitive layer of the single-layer laminate is referred to as a “binder resin”. In addition, when the charge generation layer of the multilayer photoreceptor includes a resin, the resin included in the charge generation layer is referred to as a “base resin”. Hereinafter, the electrophotographic photoreceptor according to the first embodiment of the present invention will be described in the order of a laminated electrophotographic photoreceptor and a single-layer electrophotographic photoreceptor.

≪Laminated electrophotographic photoreceptor≫
As shown in FIG. 1A, in the electrophotographic photoreceptor, the multilayer photoreceptor 10 is formed by forming a charge generation layer 12 containing a charge generation material on a conductive substrate 11 by means of vapor deposition or coating, Next, the charge transporting layer 13 can be formed by applying a coating liquid containing a charge transporting material and a specific binder resin on the charge generating layer 12 and then drying to form the charge transporting layer 13.

  The multilayer electrophotographic photosensitive member can be applied to both positive and negative charging systems by appropriately selecting the type of charge transport material.

  Further, as shown in FIG. 1B, it is also preferable to previously form the undercoat layer 14 on the conductive substrate 11 before forming the photosensitive layer. By providing the undercoat layer 14, the charge on the conductive substrate 11 side is prevented from being injected into the photosensitive layer, and the binding of the photosensitive layer onto the conductive substrate 11 is strengthened. This is because defects can be covered and smoothed.

  Hereinafter, with respect to the multilayer photoconductor, a conductive substrate, a photosensitive layer, and a method for producing the photosensitive layer will be described in order.

[Conductive substrate]
The conductive substrate is not particularly limited as long as it can be used as a conductive substrate of an electrophotographic photosensitive member. Specifically, for example, a material having at least a surface portion made of a conductive material can be used. Specifically, for example, it may be made of a conductive material, or may be a plastic material or the like whose surface is covered with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. Moreover, as a material which has electroconductivity, the material which has electroconductivity may be used by 1 type, and may be used as an alloy etc., for example, combining 2 or more types. Further, among the above, the conductive substrate is preferably made of aluminum or an aluminum alloy. By doing so, a photoconductor capable of forming a more suitable image can be provided. This is considered to be due to good charge transfer from the photosensitive layer to the conductive substrate.

  The shape of the conductive substrate can be appropriately selected according to the structure of the image forming apparatus to be used. For example, a sheet-like or drum-like substrate can be suitably used.

(Photosensitive layer)
The multilayer photoreceptor is composed of a charge generation layer containing at least a charge generation material and a charge transport layer containing at least a charge transport material and a binder resin, which are formed on a conductive substrate. May be included. Hereinafter, the binder resin, the charge transport material, the charge generation material, and the base resin will be described in order.

(Binder resin)
The binder resin used in the charge transporting layer is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from binder resins conventionally used in the charge transporting layer of the multilayer photoreceptor. Specific examples of suitable binder resins include bisphenol Z polycarbonate resin, bisphenol ZC polycarbonate resin, bisphenol C polycarbonate resin, bisphenol A polycarbonate resin, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer Polymer, styrene-maleic acid copolymer, acrylic copolymer, 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, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl acetal resin, polyvinyl chloride Lahr resins, polyether resins, silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, epoxy acrylate resins, and urethane - acrylate resins. Binder resin may be used individually by 1 type, and may use 2 or more types together.

(Charge transport material)
Generally as a charge transport material, a hole transport material and an electron transport material are mentioned. In the electrophotographic photosensitive member according to the first embodiment of the present invention, the charge transport layer contains an iminoquinone derivative represented by the following general formula (1) as an electron transport material.

（一般式（１）中、Ｒ^１及びＲ^２は、それぞれ、水素原子、ハロゲン原子、ニトロ基、炭素数１以上１２以下のアルキル基、炭素数１以上１２以下のアルキル基で置換されていてもよい炭素数６以上１２以下のアリール基、炭素数６以上１２以下のアラルキル基、炭素数３以上１０以下のシクロアルキル基、及び炭素数１以上６以下のアルコキシ基からなる群より選択される基であり、
Ｒ^３及びＲ^４は、それぞれ、水素原子、炭素数１以上１２以下のアルキル基、炭素数１以上１２以下のアルキル基で置換されていてもよい炭素数６以上１２以下のアリール基、炭素数６以上１２以下のアラルキル基、炭素数３以上１０以下のシクロアルキル基、及び炭素数１以上６以下のアルコキシ基である。）

(In General Formula (1), R ¹ and R ² are each substituted with a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. Or an aryl group having 6 to 12 carbon atoms, an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. Group,
R ³ and R ⁴ are each a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms that may be substituted with an alkyl group having 1 to 12 carbon atoms, An aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. )

When R ¹ and R ² are halogen atoms, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom is preferable.

When R ¹ and R ² are alkyl groups having 1 to 12 carbon atoms, the structure of the alkyl group may be linear, branched, or a combination thereof. Specific examples of the alkyl group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, and n-pentyl. Group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl, n-dodecyl group and the like. Among these groups, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group are preferable, and a methyl group and an ethyl group are more preferable. A methyl group is particularly preferred.

When R ¹ and R ² are an aryl group having 6 to 12 carbon atoms which may be substituted with an alkyl group having 1 to 12 carbon atoms, specific examples of the aryl group include a phenyl group, a naphthyl group, Biphenyl group, tolyl group, cumenyl group, xylyl group and the like can be mentioned. Of these groups, a phenyl group is preferred.

When R ¹ and R ² are an aralkyl group having 6 to 12 carbon atoms, specific examples of the aralkyl group include benzyl group, phenethyl group, α-naphthylmethyl group, β-naphthylmethyl group, α-naphthylethyl group. Group, and β-naphthylethyl group.

When R ¹ and R ² are a cycloalkyl group having 3 to 10 carbon atoms, specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Etc.

When R ¹ and R ² are an alkoxy group having 1 to 6 carbon atoms, specific examples of the alkoxy group include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, s- A butoxy group, a t-butoxy group, a pentyloxy group, an isopentyloxy group, a neopentyloxy group, a hexyloxy group, and the like can be given. In these, a methoxy group is preferable.

When R ³ and R ⁴ are alkyl groups having 1 to 12 carbon atoms, the same alkyl groups as R ¹ and R ² can be exemplified. As the alkyl group having 1 to 12 carbon atoms suitable as R ³ and R ⁴ , a methyl group and a tert-butyl group are preferable.

When R ³ and R ⁴ are an aryl group having 6 to 12 carbon atoms which may be substituted with an alkyl group having 1 to 12 carbon atoms, specific examples thereof are the same as those for R ¹ and R ² An aryl group can be mentioned.

When R ³ and R ⁴ are an aralkyl group having 6 to 12 carbon atoms, specific examples thereof include the same aralkyl groups as R ¹ and R ² .

When R ³ and R ⁴ are cycloalkyl groups having 3 to 10 carbon atoms, specific examples thereof include the same cycloalkyl groups as R ¹ and R ² .

When R ³ and R ⁴ are alkoxy groups having 1 to 6 carbon atoms, specific examples thereof include the same alkoxy groups as R ¹ and R ² .

  Among the iminoquinone derivatives represented by the general formula (1), specific examples of suitable compounds include the following ETM-1 to ETM-5.

<Method for producing iminoquinone derivative>
The production method of the iminoquinone derivative represented by the general formula (1) is not particularly limited. For example, ETM-1, which is the above-mentioned iminoquinone derivative, can be synthesized by the following method.

  As shown in the following reaction formula, first, 2-methyl-4-aminophenol represented by the formula (1-1) and 3,5-di-tert-butyl- represented by the formula (1-2) 4-Hydroxybenzaldehyde and para-toluenesulfonic acid are dissolved in toluene. The resulting toluene solution is heated to reflux while removing by-produced water to produce a compound represented by formula (1-3). After the reaction, toluene is distilled off to obtain a compound represented by the formula (1-3). The obtained compound represented by the formula (1-3) is dissolved in chloroform. Next, silver oxide is added to the chloroform solution, and the chloroform solution is stirred to carry out an oxidation reaction. After the oxidation reaction, silver oxide is filtered off from the chloroform solution. The filtrate obtained after filtration is purified by column chromatography to obtain ETM-1 which is an iminoquinone derivative.

  Since the photosensitive layer of the electrophotographic photosensitive member according to the first embodiment contains an iminoquinone derivative represented by the general formula (1) as an electron transport material among electron transport materials excellent in charge transport ability, sensitivity characteristics. An electrophotographic photoreceptor excellent in the above can be obtained.

  The charge transport layer contains various compounds conventionally used as charge transport materials in electrophotographic photoreceptors in addition to the iminoquinone derivative represented by the general formula (1) as long as the object of the present invention is not impaired. May be.

  Examples of the hole transport material that can be used together with the iminoquinone derivative represented by the general formula (1) include benzidine derivatives and 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole. Oxadiazole compounds, styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, organic polysilane compounds, pyrazolines such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline Compounds, hydrazone compounds, other triphenylamine compounds represented by the general formula (1), indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds Compound, pyrazole system Things, nitrogen-containing cyclic compounds such as triazole compounds, and condensed polycyclic compounds. These hole transport materials may be used alone or in combination of two or more.

  The charge transport material includes, in addition to the iminoquinone derivative represented by the general formula (1), an electron transport material conventionally used in a photosensitive layer of an electrophotographic photosensitive member as long as the object of the present invention is not impaired. May be. Specific examples of other electron transporting materials that can be used together with the iminoquinone derivative represented by the general formula (1) include naphthoquinone derivatives, diphenoquinone derivatives, anthraquinone derivatives, azoquinone derivatives, Quinone derivatives such as nitroantharaquinone derivatives and dinitroanthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3,4,5,7-tetranitro-9-fluorenone derivatives, dinitroanthracene derivatives, dinitroacridine derivatives, tetracyano Examples include ethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, succinic anhydride, maleic anhydride, and dibromomaleic anhydride.

  When the electron transport material contains other compounds of the iminoquinone derivative represented by the general formula (1) together with the iminoquinone derivative represented by the general formula (1), the general formula (1) with respect to the total mass of the electron transport material The mass ratio of the iminoquinone derivative represented is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

(Charge generation material)
The charge generation material is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from charge generation materials conventionally used in the photosensitive layer of an electrophotographic photoreceptor. Specifically, for example, X-type metal-free phthalocyanine (x-H ₂ Pc), Y-type oxotitanyl phthalocyanine (Y-TiOPc) represented by the following formula (I), perylene pigment, bisazo pigment, dithioketopyrrolopyrrole Inorganic photoconductive materials such as pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azulenium pigments, cyanine pigments, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon Powder, pyrylium salt, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, pyrazoline pigment, quinacridone pigment and the like.

  Further, the charge generation material may be used alone or in combination of two or more kinds so as to have an absorption wavelength in a desired region. Further, among the above-described charge generating materials, in particular, in a digital optical image forming apparatus such as a laser beam printer or a facsimile using a light source such as a semiconductor laser, a positively charged single layer having sensitivity in a wavelength region of 700 nm or more Since a type electrophotographic photoreceptor is required, for example, phthalocyanine pigments such as metal-free phthalocyanine and oxotitanyl phthalocyanine are preferably used. The crystal form of the phthalocyanine pigment is not particularly limited, and various types can be used. In addition, an image forming apparatus of an analog optical system such as an electrostatic copying machine using a white light source such as a halogen lamp needs a positively charged single layer type electrophotographic photosensitive member having sensitivity in the visible region. For example, perylene pigments and bisazo pigments are preferably used.

(Base resin)
When the charge generation layer is formed on a conductive substrate by applying a solution containing a charge generation material, a base resin is used together with the charge generation material. As the base resin used in the charge generation layer in the present invention, the same resin as the binder resin used in the charge transport layer can be used. However, since the laminated photoconductor is generally applied in the order of the charge generation layer and the charge transport layer, a base resin is selected so that the charge generation layer does not dissolve in the coating solvent when the charge transport layer is applied. The

[Method for creating photosensitive layer]
The photosensitive layer in the multilayer photoreceptor is formed by sequentially laminating a charge generation layer and a charge transport layer on a conductive substrate or an undercoat layer formed on the conductive substrate.

  The film thickness of the charge generation layer in the multilayer photoreceptor is preferably from 0.1 μm to 5 μm, and more preferably from 0.1 μm to 3 μm. The film thickness of the charge transport layer is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

  The content of the charge generation material in the charge generation layer is not particularly limited as long as the object of the present invention is not impaired. When the charge generation layer and the coating solution are applied, the amount of the charge generation material is preferably 10 parts by mass or more and 500 parts by mass or less, and 30 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the base resin. Is more preferable.

  The content of the charge transport material in the charge transport layer is not particularly limited as long as the object of the present invention is not impaired. The content of the charge transport material in the charge transport layer is preferably 65 parts by mass or less, more preferably 50 parts by mass or less, and particularly preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin. By setting the amount of the charge transporting material in such a range, it is easy to obtain a multilayer photoreceptor excellent in wear resistance.

  The charge transport layer includes a charge transport material containing an iminoquinone derivative represented by the general formula (1) as an electron transport material. The content of the iminoquinone derivative represented by the general formula (1) in the charge transport layer is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 30 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the binder resin. preferable. By setting the content of the iminoquinone derivative represented by the general formula (1) within such a range, it is easy to form a multilayer photoreceptor excellent in sensitivity characteristics.

  Examples of the method for forming the charge generation layer include vacuum deposition of a charge generation material, or application of a coating solution containing at least a charge generation material, a base resin, and a solvent. As a method for forming the charge generation layer, it is preferable to apply a coating solution containing at least a charge generation material, a base resin, and a solvent because an expensive vapor deposition apparatus is unnecessary and a film forming operation is easy. Moreover, as a formation method of a charge transport layer, application | coating of the coating liquid containing a charge transport material, binder resin, and a solvent is mentioned at least.

  As the solvent used for preparing the coating solution for forming the photosensitive layer, various organic solvents conventionally used for the coating solution for forming the photosensitive layer can be used. Specifically, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, dichloroethane and chloroform , Halogenated hydrocarbons such as carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, dioxane, dioxolane, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; Esters such as ethyl and methyl acetate; N, N-dimethylformaldehyde, N, N-dimethylformamide, dimethyl sulfoxide, etc. Aprotic polar organic solvents.

  Various conventionally known additives can be blended in the coating solution for the charge generation layer or the charge transport layer as long as the electrophotographic characteristics are not adversely affected. Suitable additives to be blended in the coating liquid include, for example, antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, Examples include thickeners, dispersion stabilizers, waxes, acceptors, donors and the like. In order to improve the dispersibility of the charge transporting material and the charge generating material and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent and the like may be used.

  The method for applying the coating solution for the charge generation layer or the charge transport layer is not particularly limited, and examples thereof include a method using a spin coater, applicator, spray coater, bar coater, dip coater, doctor blade and the like.

  The film formed by applying the coating solution by the above method is dried using a high-temperature dryer, a vacuum dryer, or the like to remove the solvent, thereby forming a charge generation layer and a charge transport layer. The drying temperature is preferably 40 ° C or higher and 150 ° C or lower. This is because, by drying the film in such a temperature range, the removal of the solvent proceeds rapidly, and the charge generation layer and the charge transport layer having a uniform thickness can be efficiently formed. When the drying temperature is too high, the components contained in the photosensitive layer may be thermally decomposed, which is not preferable.

  The undercoat layer can be formed by preparing a coating solution from a resin, inorganic fine particles such as zinc oxide and titanium oxide, and a solvent, applying the solution onto a conductive substrate, and then drying the coating solution.

≪Single layer type electrophotographic photoreceptor≫
The electrophotographic photosensitive member according to the first embodiment of the present invention can be used in both positive and negative charging methods, and since the photosensitive layer is a single layer, the production of the photosensitive member is easy, and the interface between the layers is It is also preferable to use a single-layer type photoreceptor because it has few optical properties and the like.

  As shown in FIG. 2A, in the electrophotographic photosensitive member, the single layer type photosensitive member 20 has a single photosensitive layer 21 provided on a conductive substrate 11. The photosensitive layer in the single-layer type photoreceptor is, for example, a coating liquid obtained by dissolving or dispersing a charge transport material, a charge generation material, a binder resin, and a leveling agent, if necessary, in an appropriate solvent. It can be formed by drying after coating on the conductive substrate 11.

  Further, as shown in FIG. 2B, it is also preferable to form a photosensitive layer 21 on the conductive substrate 11 via the undercoat layer 14.

  Hereinafter, regarding a single-layer type photoreceptor, a conductive substrate, a photosensitive layer, and a method for producing the photosensitive layer will be described in order.

[Conductive substrate]
In the present invention, as the conductive substrate used for the single-layer type photoreceptor, a substrate made of the same material as the conductive substrate used for the above-mentioned laminated type photoreceptor can be used. The shape of the conductive substrate can be appropriately selected according to the structure of the image forming apparatus to be used. For example, a substrate such as a sheet or a drum can be suitably used.

(Photosensitive layer)
Examples of the main material constituting the photosensitive layer in the single-layer type photoreceptor include a binder resin, a charge transport material, and a charge generation material. As the binder resin, a resin similar to the binder resin contained in the charge transport layer of the multilayer photoreceptor is used. The charge transporting material and the charge generating material are the same materials as those for the multilayer photoreceptor.

[Method for creating photosensitive layer]
The photosensitive layer of a single-layer type photoreceptor is prepared by preparing a coating solution from a charge transport material, a charge generation material, a binder resin, and a solvent, and is the same method as the method for forming the charge generation layer and the charge transport layer in the multilayer photoreceptor. Can be formed.

  The amount of the electron transport material used in the photosensitive layer of the single layer type photoreceptor is preferably 55 parts by mass or less, more preferably 5 parts by mass or more and 55 parts by mass or less, with respect to 100 parts by mass of the binder resin. Part by mass or less is particularly preferable. Further, the amount of the hole transport material used in the photosensitive layer is preferably 20 parts by mass or more and 150 parts by mass or less, and more preferably 40 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin. By setting the content of the iminoquinone derivative represented by the general formula (1) within such a range, it is easy to form a single layer type photoreceptor having excellent sensitivity characteristics. The amount of the charge transport material is the total amount of the hole transport material and the electron transport material in the charge transport layer.

  The amount of the charge generating material used in the photosensitive layer of the single layer type photoreceptor is preferably 0.01 parts by mass or more and 30 parts by mass or less, and 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferred is 0.4 to 10 parts by mass. When the amount of the charge generating material used is within such a range, a photoreceptor having excellent electrical characteristics can be produced without reducing the wear resistance of the photoreceptor.

  The thickness of the photosensitive layer of the single layer type photoreceptor is not particularly limited as long as it has a function suitable as a photosensitive layer. Specifically, the thickness of the photosensitive layer is preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm.

  As described above, the electrophotographic photoreceptor according to the first embodiment of the present invention has excellent sensitivity characteristics because the photosensitive layer contains the iminoquinone derivative represented by the general formula (1) as an electron transport material.

[Second Embodiment]
In the second embodiment of the present invention, an image carrier, a charging unit for charging the surface of the image carrier, and the surface of the charged image carrier are exposed to form an electrostatic latent image on the surface of the image carrier. An image bearing member includes an exposure unit for forming the toner image, a developing unit for developing the electrostatic latent image as a toner image, and a transfer unit for transferring the toner image from the image bearing member to the transfer target. The present invention relates to an image forming apparatus using an electrophotographic photosensitive member according to a first embodiment of the present invention.

  In the image forming apparatus according to the second embodiment of the present invention, other components of the image carrier such as the charging unit, the exposure unit, the developing unit, and the transfer unit are appropriately selected from those used in the conventional image forming apparatus. You can choose. An image forming apparatus according to the second embodiment of the present invention includes an electrophotographic photosensitive member according to the second embodiment of the present invention containing an iminoquinone derivative represented by the general formula (1) as an electron transport material. Therefore, it has excellent sensitivity characteristics.

  Hereinafter, as a representative example of the image forming apparatus according to the second embodiment of the present invention, an image carrier, a charging unit for charging the surface of the image carrier, and a surface of the charged image carrier are exposed. An exposure unit for forming an electrostatic latent image on the surface of the image carrier, a developing unit for developing the electrostatic latent image as a toner image, and a transfer unit for transferring the toner image from the image carrier to a transfer target. An image forming apparatus including a transfer unit and including a positively charged single-layer type electrophotographic photosensitive member as the electrophotographic photosensitive member according to the first embodiment of the present invention will be described as an image carrier.

  The image forming apparatus according to the second embodiment of the present invention can be applied to both a monochrome image forming apparatus and a tandem color image forming apparatus using a plurality of colors of toner as described later. A tandem color image forming apparatus will be described.

  An image forming apparatus provided with a positively charged single-layer type electrophotographic photosensitive member described below has a plurality of juxtaposed in a predetermined direction in order to form toner images with different colors of toner on each surface. A plurality of image carriers, and a plurality of developing rollers each provided with a developing roller disposed opposite to each image carrier, carrying and transporting toner on the surface, and supplying the conveyed toner to the surface of each image carrier And a positively charged single layer type electrophotographic photosensitive member is used as an image carrier as the electrophotographic photosensitive member according to the first embodiment of the present invention.

  FIG. 3 is a schematic view showing a configuration of a tandem type color image forming apparatus provided with a positively charged single layer type electrophotographic photosensitive member. Here, the color printer 1 will be described as an example of the image forming apparatus.

  As shown in FIG. 3, the color printer 1 has a box-shaped device body 1a. In the apparatus main body 1a, a toner image based on image data and the like is transferred to the paper P while feeding the paper P fed from the paper feeding unit 2 and the paper P fed from the paper feeding unit 2. An image forming unit 3 and a fixing unit 4 for performing a fixing process for fixing the unfixed toner image transferred onto the paper P by the image forming unit 3 to the paper P are provided. Further, on the upper surface of the apparatus main body 1a, a paper discharge unit 5 for discharging the paper P subjected to the fixing process by the fixing unit 4 is provided.

  The paper feed unit 2 includes a paper feed cassette 121, a pickup roller 122, paper feed rollers 123, 124 and 125, and a registration roller 126. The paper feed cassette 121 is provided so as to be detachable from the apparatus main body 1a, and stores the paper P of each size. The pickup roller 122 is provided at the upper left position of the paper feed cassette 121 shown in FIG. 3 and takes out the paper P stored in the paper feed cassette 121 one by one. The paper feed rollers 123, 124, and 125 send out the paper P picked up by the pickup roller 122 to the paper transport path. The registration roller 126 temporarily waits for the paper P sent to the paper transport path by the paper feed rollers 123, 124, 125, and then supplies the paper P to the image forming unit 3 at a predetermined timing.

  In addition, the paper feeding unit 2 further includes a manual feed tray (not shown) and a pickup roller 127 that are attached to the left side surface of the device main body 1a shown in FIG. The pickup roller 127 takes out the paper P placed on the manual feed tray. The paper P taken out by the pickup roller 127 is sent out to the paper transport path by the paper feed rollers 123 and 125, and is supplied to the image forming unit 3 by the registration roller 126 at a predetermined timing.

  The image forming unit 3 includes an image forming unit 7, an intermediate transfer belt 31 on which a toner image based on image data transmitted from a computer or the like to the surface (contact surface) of the image forming unit 7 is primarily transferred, A secondary transfer roller 32 is provided for secondary transfer of the toner image on the intermediate transfer belt 31 onto the paper P fed from the paper feed cassette 121.

  The image forming unit 7 includes a black unit 7K, a yellow unit 7Y, a cyan unit 7C, and a magenta unit 7M which are sequentially arranged from the upstream side (right side in FIG. 3) to the downstream side. ing. Each of the units 7K, 7Y, 7C and 7M has a positively charged single layer type electrophotographic photosensitive member 37 (hereinafter referred to as a photosensitive member 37) as an image carrier capable of rotating in the direction of an arrow (clockwise) at the center position. Has been placed. Around each photoconductor 37, there are a charging unit 39, an exposure unit 38, a developing unit 71, a cleaning unit (not shown), and a static elimination unit (not shown) in order from the upstream side in the rotation direction. Has been placed. As the photoconductor 37, a positively charged single layer type electrophotographic photoconductor is used as the electrophotographic photoconductor according to the second embodiment.

  The charging unit 39 uniformly charges the peripheral surface of the photoconductor 37 rotated in the direction of the arrow. The charging method of the charging unit 39 is not particularly limited, and may be a contact method or a non-contact method. A suitable example of the charging unit 39 includes a contact-type charging roller and charging brush that charges the peripheral surface (surface) of the photosensitive member 37 while the charging roller and charging brush are in contact with the photosensitive member 37. A charging part is mentioned, The charging part provided with the charging roller is used more preferably.

  The charging unit 39 including a contact-type charging roller charges the peripheral surface (surface) of the photoconductor 37 while the charging roller is in contact with the photoconductor 37. As such a charging roller, for example, a roller that rotates depending on the rotation of the photoconductor 37 while being in contact with the photoconductor 37 can be used. Moreover, as a charging roller, the roller etc. which the surface part was comprised with resin at least are mentioned, for example. More specifically, for example, a core metal that is rotatably supported, a resin layer formed on the metal core, and a voltage application unit that applies a voltage to the metal core may be used. The charging unit 39 including such a charging roller can charge the surface of the photoreceptor 37 that is in contact with the cored bar by applying a voltage to the cored bar by the voltage applying unit.

  The voltage applied to the charging roller by the voltage application unit is not particularly limited, but it is preferable that only the DC voltage is applied rather than the application of the superimposed voltage obtained by superimposing the AC voltage on the AC voltage or DC voltage. When only a DC voltage is applied to the charging roller, the amount of wear of the photosensitive layer tends to decrease, and a suitable image can be formed. The DC voltage applied to the multilayer electrophotographic photosensitive member by the charging roller is preferably from 100 V to 2000 V, more preferably from 1200 V to 1800 V, particularly preferably from 1400 V to 1600 V. A more suitable image can be formed when only the DC voltage is applied to the charging roller than when the AC voltage or the superimposed voltage obtained by superimposing the AC voltage on the DC voltage is applied to the charging roller.

  The resin constituting the resin layer of the charging roller is not particularly limited as long as the peripheral surface of the photoreceptor 37 can be charged satisfactorily. Specific examples of the resin used for the resin layer include a silicone resin, a urethane resin, and a silicone-modified resin. Further, the resin layer may contain an inorganic filler.

  The exposure unit 38 is a so-called laser scanning unit, and irradiates the peripheral surface of the photoreceptor 37 uniformly charged by the charging unit 39 with laser light based on image data input from a personal computer (PC) as a host device. Then, an electrostatic latent image based on the image data is formed on the photoreceptor 37. The developing unit 71 supplies toner to the circumferential surface of the photoreceptor 37 on which the electrostatic latent image is formed, thereby forming a toner image based on the image data. The toner image is primarily transferred to the intermediate transfer belt 31. The cleaning unit cleans the toner remaining on the peripheral surface of the photoreceptor 37 after the primary transfer of the toner image to the intermediate transfer belt 31 is completed. The neutralization unit neutralizes the peripheral surface of the photoreceptor 37 after the primary transfer is completed. The peripheral surface of the photoconductor 37 cleaned by the cleaning unit and the charge eliminating unit is directed to the charging unit 39 for a new charging process, and a new charging process is performed.

  The intermediate transfer belt 31 is an endless belt-like rotating body, and includes a driving roller 33, a driven roller 34, a backup roller 35, and 1 so that the surface (contact surface) side is in contact with the circumferential surface of each photoconductor 37. It is stretched over a plurality of rollers such as the next transfer roller 36. Further, the intermediate transfer belt 31 is configured to be rotated by a plurality of rollers while being pressed against the photoconductor 37 by a primary transfer roller 36 disposed to face each photoconductor 37. The driving roller 33 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 31. The driven roller 34, the backup roller 35, and the primary transfer roller 36 are rotatably provided and rotate following the rotation of the intermediate transfer belt 31 by the driving roller 33. These rollers 34, 35, and 36 are driven to rotate via the intermediate transfer belt 31 in accordance with the main rotation of the drive roller 33 and support the intermediate transfer belt 31.

  The primary transfer roller 36 applies a primary transfer bias (a polarity opposite to the toner charging polarity) to the intermediate transfer belt 31. By doing so, the toner image formed on each photoconductor 37 circulates in the direction of the arrow (counterclockwise) by driving the drive roller 33 between each photoconductor 37 and the primary transfer roller 36. The images are sequentially transferred (primary transfer) to the intermediate transfer belt 31 in an overcoated state. Thereafter, if desired, after neutralization is performed by a neutralization unit (not shown) for neutralizing the surface of each photoconductor 37 with neutralizing light, each photoconductor 37 is further rotated to move to the next process. .

  The secondary transfer roller 32 applies a secondary transfer bias having a polarity opposite to that of the toner image to the paper P. By doing so, the toner image primarily transferred onto the intermediate transfer belt 31 is transferred to the paper P between the secondary transfer roller 32 and the backup roller 35, and thereby, a color transfer image ( An unfixed toner image) is transferred.

  The fixing unit 4 performs a fixing process on the transfer image transferred to the paper P by the image forming unit 3. The fixing unit 4 is disposed opposite to the heating roller 41 heated by the energized heating element and the heating roller 41. Is provided with a pressure roller 42 that is pressed against the peripheral surface of the heating roller 41.

  The transferred image transferred to the paper P by the secondary transfer roller 32 in the image forming unit 3 is subjected to a fixing process by heating when the paper P passes between the heating roller 41 and the pressure roller 42. To be established. The paper P subjected to the fixing process is discharged to the paper discharge unit 5. Further, in the color printer 1 of the present embodiment, the transport roller 6 is disposed at an appropriate position between the fixing unit 4 and the paper discharge unit 5.

  The paper discharge unit 5 is formed by recessing the top of the device main body 1a of the color printer 1, and a paper discharge tray 51 for receiving the discharged paper P is formed at the bottom of the concave portion. .

  The color printer 1 forms an image on the paper P by the image forming operation as described above. In the tandem image forming apparatus as described above, the image bearing member includes the electrophotographic photosensitive member according to the first embodiment of the present invention, which is excellent in photosensitive characteristics, and thus forms a suitable image. An image forming apparatus capable of performing the above is obtained.

  In Examples and Comparative Examples, the following HTM-1 was used as a hole transport material (HTM). Moreover, the following ETM-1 to 6 were used as the electron transport material (ETM).

<Hole transport material>

<Electron transport material>

[Examples 1 to 10 and Comparative Examples 1 and 2]
<Evaluation of sensitivity of single layer type electrophotographic photoreceptor>
Using the hole transport material, electron transport material, and charge generation material shown in Table 1, a single layer type electrophotographic photosensitive member was prepared according to the following method, and the sensitivity of the single layer type electrophotographic photosensitive member was evaluated. .

(Preparation of coating solution)
80 parts by mass of a hole transport material (HTM-1), 50 parts by mass of an electron transport material of the type described in Table 1, and a charge generation material of the type described in Table 1 (X-type metal-free phthalocyanine (X-H ₂ PC) Or 5 parts by weight of Y-type titanyl phthalocyanine (Y-TiOPc), 100 parts by weight of binder resin (polycarbonate), and 800 parts by weight of solvent (tetrahydrofuran) are mixed into a ball mill and mixed and dispersed for 50 hours to form a single layer. A coating solution for a photoconductor was prepared.

(Creation of single layer type photoreceptor)
The obtained coating solution was applied on a conductive substrate (aluminum base tube) by a dip coating method, and then the coating film was dried with hot air at 100 ° C. for 30 minutes to obtain a single-layer electrophotographic film having a thickness of 30 μm. A photoconductor was prepared.

(Sensitivity measurement)
Using a drum sensitivity tester (Gentec), the wavelength extracted from the white light of the halogen lamp using a bandpass filter while the surface potential of the single-layer electrophotographic photosensitive member is charged to +700 V (V ₀ ). The surface of the photoconductor was irradiated with 780 nm monochromatic light (half-width 20 nm, light intensity 1.5 μJ / m ² ) for 1.5 seconds. The sensitivity of the photoconductor was measured with _VL being the residual potential on the surface of the photoconductor when 0.5 seconds had elapsed from the start of exposure. Table 1 shows the sensitivity (V _L ) of the photoconductors of Examples 1 to 10 and Comparative Examples 1 and 2.

According to Table 1, an electrophotographic photoreceptor using ETM-1 to ETM-5, which are iminoquinone derivatives represented by the general formula (1), as an electron transport material is ETM-6 which is a conventionally known electron transport material. It can be seen that the residual potential (V _L ) is lower and the sensitivity characteristics are better than those of the electrophotographic photoreceptor using.

DESCRIPTION OF SYMBOLS 10 Laminated-type photoreceptor 10 'Laminated-type photoreceptor which has an undercoat layer 11 Conductive substrate 12 Charge generation layer 13 Charge transport layer 14 Undercoat layer 20 Single-layer type photoreceptor 20' Single-layer-type photoreceptor which has an undercoat layer 21 Photosensitive layer

Claims (3)

An electrophotographic photoreceptor having a photosensitive layer formed on a conductive substrate,
The photosensitive layer is
1) a layered photosensitive layer in which a charge generation layer containing at least a charge generation material, a charge transport layer containing at least a charge transport material and a binder resin are sequentially laminated, or
2) A single-layer type photosensitive layer containing at least a charge generating material, a charge transporting material, and a binder resin,
An electrophotographic photoreceptor in which the charge transport material contains an iminoquinone derivative represented by the following general formula (1) as an electron transport material.

(In General Formula (1), R ¹ and R ² are each substituted with a hydrogen atom, a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. Or an aryl group having 6 to 12 carbon atoms, an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. Group,
R ³ and R ⁴ are each a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms that may be substituted with an alkyl group having 1 to 12 carbon atoms, It is a group selected from the group consisting of an aralkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. )   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is a single-layer type photosensitive layer. An image carrier;
A charging unit for charging the surface of the image carrier;
An exposure unit for exposing a surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier;
A developing unit for developing the electrostatic latent image as a toner image;
An image transfer member for transferring the toner image from the image carrier to a transfer target, wherein the image carrier is the electrophotographic photosensitive member according to claim 1. Forming equipment.

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