JP2011064905A - Image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus suppressing generation of color lines, which is an electrophotographic apparatus employing a contact charging system of applying a DC voltage. <P>SOLUTION: The image forming apparatus includes: an electrophotographic photoreceptor 31; a charging means 32 rotating while in contact with the surface of the photoreceptor and charging the surface of the photoreceptor by applying a DC voltage to the charging means; an electrostatic latent image-forming means 26; a developing means 33; and a transfer means 40. The photoreceptor has a photosensitive layer containing a binder resin and at least one selected from among butadiene-based charge transport material and an enamine-based charge transport material. Preferably, the photoreceptor satisfies a relationship of ΔVL≤ΔVh×1/4, wherein ΔVh represents a difference between the maximum and the minimum of the surface potential after charged, and ΔVL represents a difference between the maximum and the minimum of the surface potential after exposed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a process cartridge.

Electrophotographic image formation has the advantages of high speed and high print quality, and is therefore widely used in fields such as copying machines and laser beam printers.
In image forming apparatuses such as copying machines and laser beam printers, the Carlson method is generally used, and an electrostatic latent image formed on an electrophotographic photosensitive member by a charging and exposure device using a corona charger or a conductive roller. After developing in the developing step, the image is transferred to a recording medium such as recording paper in the transfer step, and then fixed to the recording medium such as recording paper in the fixing step with heat and pressure to form an image.

  As an electrophotographic photosensitive member (hereinafter, simply referred to as “photosensitive member” in some cases) used in an electrophotographic apparatus, it has advantages in terms of low cost, manufacturability and disposal compared to a photosensitive member using an inorganic photoconductive material. An electrophotographic photosensitive member using an organic photoconductive material has come to dominate. Among them, various proposals have been made for a function-separated type organic photoreceptor in which a charge generation layer that generates charges by exposure and a charge transport layer that transports charges are laminated.

For example, in Patent Document 1, the amount of wear (amount of wear) is suppressed by including a polycarbonate copolymer resin on the surface of the photoconductor, the variation in the dielectric film thickness of the photoconductor is reduced, and the change in the charging potential is reduced. It has been proposed to maintain image quality by suppressing image density reduction or fogging.
In Patent Document 2, by containing a polycarbonate copolymer resin on the surface of the photoconductor, the amount of abrasion (amount of wear) of the surface of the photoconductor is suppressed, and the dielectric film thickness unevenness caused by the surface wear unevenness is reduced. It has been proposed to reduce charging potential unevenness.

  On the other hand, as a charging means, a corona charging method has been generally used. In recent years, a contact charging method having advantages such as low ozone and low power has been put into practical use and has been actively used. In the contact charging method, the charging member is brought into contact with the surface of the photosensitive member, and a voltage is applied to the charging member to charge the surface of the photosensitive member. As a method of applying to the charging member, there are a direct current method in which only a direct current voltage is applied and an alternating current method in which an alternating current voltage is superimposed on the direct current voltage.

JP-A-8-146640 JP-A-7-92703

  In the contact charging type electrophotographic apparatus to which a DC voltage is applied, the present invention includes at least one of the charge transport materials represented by the general formula (1) and the general formula (2) described later. An object of the present invention is to provide an image forming apparatus in which the generation of color lines is suppressed as compared with the case where no photosensitive layer is provided.

（一般式（１）中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５、及びＲ^６はそれぞれ独立して水素原子、ハロゲン原子、炭素数１以上２０以下のアルキル基、炭素数１以上２０以下のアルコキシ基、又は、置換もしくは未置換の炭素数６以上３０以下のアリール基を表し、隣接する２つの置換基同士が炭化水素環構造を形成してもよい。ｎ及びｍはそれぞれ独立して０又は１を表す。）

（一般式（２）中、Ｒ^７、Ｒ^８、Ｒ^９、Ｒ^１０、Ｒ^１１、及びＲ^１２はそれぞれ独立して水素原子、ハロゲン原子、炭素数１以上２０以下のアルキル基、炭素数１以上２０以下のアルコキシ基、置換又未置換の炭素数６以上３０以下のアリール基を表し、隣接する２つの置換基同士が炭化水素環構造を形成してもよい。）
請求項２の発明は、前記電子写真感光体が、前記帯電手段により帯電された後の表面電位の最大値と最小値の差ΔＶｈと、前記静電潜像形成手段により露光された後の表面電位の最大値と最小値の差ΔＶＬが、下記式（３）の関係を満たす請求項１に記載の画像形成装置。
ΔＶＬ≦ΔＶｈ×１／４ （３）
請求項３の発明は、前記ΔＶｈが、２０Ｖ以下である請求項２に記載の画像形成装置。
請求項４の発明は、結着樹脂と、下記一般式（１）で表される構造を有する電荷輸送性材料及び下記一般式（２）で表される構造を有する電荷輸送性材料から選ばれる少なくとも一種と、を含む感光層を有する電子写真感光体と、前記電子写真感光体の表面に接触して回転し、直流電圧が印加されて該電子写真感光体の表面を帯電する帯電手段と、を備えたプロセスカートリッジ。

（一般式（１）中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５、及びＲ^６はそれぞれ独立して水素原子、ハロゲン原子、炭素数１以上２０以下のアルキル基、炭素数１以上２０以下のアルコキシ基、又は、置換もしくは未置換の炭素数６以上３０以下のアリール基を表し、隣接する２つの置換基同士が炭化水素環構造を形成してもよい。ｎ及びｍはそれぞれ独立して０又は１を表す。）

（一般式（２）中、Ｒ^７、Ｒ^８、Ｒ^９、Ｒ^１０、Ｒ^１１、及びＲ^１２はそれぞれ独立して水素原子、ハロゲン原子、炭素数１以上２０以下のアルキル基、炭素数１以上２０以下のアルコキシ基、置換又未置換の炭素数６以上３０以下のアリール基を表し、隣接する２つの置換基同士が炭化水素環構造を形成してもよい。） In order to achieve the above object, the following invention is provided.
The invention of claim 1 is selected from a binder resin, a charge transporting material having a structure represented by the following general formula (1), and a charge transporting material having a structure represented by the following general formula (2). An electrophotographic photosensitive member having a photosensitive layer containing at least one kind, and a charging unit that rotates in contact with the surface of the electrophotographic photosensitive member and charges the surface of the electrophotographic photosensitive member by applying a DC voltage; An electrostatic latent image forming means for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner. An image forming apparatus comprising: a developing unit that develops a toner image; and a transfer unit that transfers a toner image formed on the surface of the electrophotographic photosensitive member to a recording medium.

(In General Formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 carbon atom. It represents an alkoxy group having 20 or less or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure, where n and m are each Independently represents 0 or 1)

(In General Formula (2), R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 carbon atom. Represents an alkoxy group having 20 or less or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure.)
According to a second aspect of the present invention, the electrophotographic photosensitive member has a difference ΔVh between the maximum value and the minimum value of the surface potential after being charged by the charging unit, and the surface after being exposed by the electrostatic latent image forming unit. The image forming apparatus according to claim 1, wherein a difference ΔVL between the maximum value and the minimum value of the potential satisfies a relationship of the following formula (3).
ΔVL ≦ ΔVh × 1/4 (3)
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the ΔVh is 20 V or less.
The invention of claim 4 is selected from a binder resin, a charge transporting material having a structure represented by the following general formula (1), and a charge transporting material having a structure represented by the following general formula (2). An electrophotographic photosensitive member having a photosensitive layer containing at least one kind, and a charging unit that rotates in contact with the surface of the electrophotographic photosensitive member and charges the surface of the electrophotographic photosensitive member by applying a DC voltage; Process cartridge with

(In General Formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 carbon atom. It represents an alkoxy group having 20 or less or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure, where n and m are each Independently represents 0 or 1)

(In General Formula (2), R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 carbon atom. Represents an alkoxy group having 20 or less or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure.)

According to the first aspect of the present invention, in the contact charging type electrophotographic apparatus to which a DC voltage is applied, the electrophotographic photosensitive member is a charge transporting material represented by the following general formulas (1) and (2). As compared with the case where the photosensitive layer containing at least one of them is not provided, an image forming apparatus in which the generation of color lines is suppressed is provided.
According to the invention of claim 2, the difference ΔVh between the maximum value and the minimum value of the surface potential after charging and the difference ΔVL between the maximum value and the minimum value of the surface potential after exposure are ΔVL ≦ ΔVh × There is provided an image forming apparatus in which the generation of color lines is suppressed as compared with a case where ¼ is not satisfied.
According to the third aspect of the present invention, there is provided an image forming apparatus in which the generation of color lines is suppressed compared to the case where ΔVh exceeds 20V.
According to the fourth aspect of the present invention, in the contact charging type process cartridge for applying a DC voltage, the electrophotographic photosensitive member is formed of the charge transporting material represented by the following general formulas (1) and (2). A process cartridge is provided in which the generation of color lines is suppressed as compared with the case where no photosensitive layer containing at least one of them is provided.

1 is a schematic diagram illustrating an example of a configuration of an image forming apparatus according to an exemplary embodiment. It is a schematic sectional drawing which shows an example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of a structure of the image forming apparatus which concerns on this embodiment. It is the schematic which shows an example of a structure of the process cartridge which concerns on this embodiment.

  Hereinafter, embodiments will be described with reference to the accompanying drawings as appropriate. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and repeated description is omitted as appropriate.

When charging only by applying a DC voltage in the contact charging method, the charging potential of the charging roller is low, so the charging potential becomes non-uniform, and uneven charging occurs locally in the axial direction, especially in the contaminated part of the charging roller, The latent image potential after exposure is disturbed and fine color lines are generated.
Since the image forming apparatus according to the present embodiment has the following configuration, the generation of fine color lines as described above is suppressed.

  An image forming apparatus according to the present embodiment includes a binder resin, a charge transport material having a structure represented by the following general formula (1), and a charge transport material having a structure represented by the following general formula (2) An electrophotographic photosensitive member having a photosensitive layer containing at least one selected from the above, and charging that rotates in contact with the surface of the electrophotographic photosensitive member and charges the surface of the electrophotographic photosensitive member by applying a DC voltage And an electrostatic latent image forming means for exposing the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image formed on the surface of the electrophotographic photosensitive member includes toner. Developing means for developing with a developer to form a toner image; and transfer means for transferring the toner image formed on the surface of the electrophotographic photosensitive member to a recording medium.

In General Formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 or more carbon atoms. It represents an alkoxy group having 20 or less, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure. n and m each independently represents 0 or 1.

In General Formula (2), R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 or more carbon atoms. It represents an alkoxy group having 20 or less and a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure.

  FIG. 1 schematically shows an example of the configuration of an image forming apparatus according to the present embodiment. The image forming apparatus 100 includes a photosensitive drum 31 as an image carrier, a charger 32, a laser exposure device 26, a developing device 33, a cleaning device 36, a primary transfer roll 40, and a fixing device (not shown). . As the photoreceptor 31 rotates in the direction of arrow A, an electrostatic latent image is formed on the surface, and a toner image is further formed. In the charger 32, the charging roller rotates in contact with the surface of the photoconductor, and a DC voltage is applied to charge the surface of the photoconductor.

  The laser exposure device 26 exposes the surface of the charged photosensitive drum 31 to form an electrostatic latent image. The developing device 33 develops the electrostatic latent image formed on the surface of the photosensitive drum 31 with toner. The primary transfer roll 40 transfers the toner image formed on the photosensitive drum 31 onto a paper 500 that is a recording material (recording paper) at the primary transfer portion T1. The cleaning device includes a drum cleaner 36 to clean toner remaining on the surface of the photosensitive drum 31 after transfer. A fixing device (not shown) fixes the toner image transferred on the paper 500.

  At the time of printing, an image forming operation is executed under the control of a control unit (not shown). Specifically, image data input from a PC (personal computer) or an image reading device is subjected to image processing by an image processing unit and then supplied to the laser exposure device 26. Based on the image data, the laser exposure device 26 scans and exposes the surface of the photosensitive drum 31. Thereby, an electrostatic latent image is formed on the surface of the photosensitive drum 31. The electrostatic latent image formed on the surface of the photosensitive drum 31 is developed by the developing device 33, and a toner image is formed on the surface of the photosensitive drum 31. Here, the toner used in the developing unit 33 of the present embodiment has a negative polarity.

When the toner image formed on the photosensitive drum 31 is conveyed to the primary transfer portion T1, the paper 500 is supplied to the primary transfer portion T1. In the primary transfer portion T <b> 1, the toner images are collectively electrostatically transferred onto the paper 500 by the action of a transfer electric field formed between the primary transfer roll 40 and the photosensitive drum 31.
Thereafter, the sheet 500 on which the toner image is transferred is conveyed to a fixing device (not shown). The unfixed toner image on the paper 500 conveyed to the fixing device is fixed on the paper 500 by being subjected to fixing processing by heat and pressure by a fixing device (not shown). The paper 500 on which the fixed image is formed is conveyed to a paper discharge stacking unit (not shown) provided in the discharge unit of the image forming apparatus.

  On the surface of the photosensitive drum 31 after the transfer process in the primary transfer portion, the toner remaining on the surface of the photosensitive drum 31, the toner retransferred from the primary transfer roll 40, and the like are removed by the drum cleaner 36. The In the image forming apparatus of the present embodiment, such an image forming cycle is repeated.

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor 31 used in this embodiment has at least a photosensitive layer on a conductive support, and the photosensitive layer has a charge having a binder resin and a butadiene structure represented by the general formula (1). A transport material (hereinafter sometimes referred to as “butadiene-based charge transport material”) and a charge transport material having an enamine structure represented by the general formula (2) (hereinafter sometimes referred to as “enamine-based charge transport material”). And at least one selected from.

For example, an organic photoreceptor having a configuration in which at least a photosensitive layer is provided on a conductive support is used. The photosensitive layer may be a function separation type having a layer structure in which a charge generation layer and a charge transport layer are laminated in this order. Furthermore, a surface layer containing a resin having a crosslinked structure may be provided on the surface of the photosensitive layer. In addition to this, an intermediate layer may be provided between the photosensitive layer and the conductive support, or between the photosensitive layer and the surface protective layer, if necessary. Moreover, it is desirable that the resin having a crosslinked structure has charge transporting properties.
In the following description, the case where the electrophotographic photoreceptor 31 used in this embodiment is a function-separated organic photoreceptor will be mainly described. However, the layer configuration of the electrophotographic photoreceptor used in this embodiment is as follows. It is not limited to the following description.

  FIG. 2 schematically shows an example of the layer structure of the electrophotographic photosensitive member according to this embodiment. An electrophotographic photoreceptor 31 shown in FIG. 2 includes a function-separated type photosensitive layer 3 in which a charge generation layer 5 and a charge transport layer 6 are separately provided. The layer 4, the charge generation layer 5, and the charge transport layer 6 are stacked in this order.

-Conductive support-
As the conductive support 2, a metal drum such as aluminum, copper, iron, stainless steel, zinc, or nickel; aluminum, copper, gold, silver, platinum, palladium, titanium on a substrate such as a sheet, paper, plastic, glass, etc. , Nickel-chromium, stainless steel, copper-indium or the like deposited on metal; conductive metal compound such as indium oxide or tin oxide deposited on the substrate; metal foil laminated on the substrate; Carbon black, indium oxide, tin oxide-antimony oxide powder, metal powder, copper iodide and the like are dispersed in a binder resin and applied to the substrate to conduct a conductive treatment. In the present specification, “conductive” refers to a property having a volume resistivity of less than 10 ¹³ Ω · cm.

The shape of the conductive support 2 may be any of a drum shape, a sheet shape, and a plate shape. For example, when a metal pipe is used as the conductive support, the surface of the support of the metal pipe may be a raw pipe, but the surface of the support is roughened in advance by surface treatment. Also good. By this roughening, when a coherent light source such as a laser beam is used as the exposure light source, density unevenness in a grain shape due to interference light that can be generated inside the photoconductor is prevented. Examples of the surface treatment method include mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing and the like.
In particular, in terms of improving the adhesion of the photosensitive layer and improving the film formability, it is desirable to use, for example, an anodized aluminum surface as the conductive support.

-Undercoat layer-
The undercoat layer 4 is provided as necessary for the purpose of preventing light reflection on the surface of the support 2 and preventing inflow of unnecessary carriers from the support 2 to the photosensitive layer 3. Materials for the undercoat layer 4 include metal powders such as aluminum, copper, nickel, and silver, conductive metal oxides such as antimony oxide, indium oxide, tin oxide, and zinc oxide, carbon fiber, carbon black, and graphite. Examples thereof include a conductive material such as powder dispersed in a binder resin and coated on a support. Two or more kinds of conductive metal oxides may be used in combination. Further, the powder resistance may be controlled by performing a surface treatment with a coupling agent on the conductive metal oxide.

The binder resin contained in the undercoat layer 4 includes acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, and polyvinyl chloride resin. , Polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, and other known polymer resin compounds, and charge transport properties A charge transporting resin having a group or a conductive resin such as polyaniline is used.
The ratio of the conductive metal oxide and the binder resin in the undercoat layer 4 is not particularly limited and can be arbitrarily set.

  When the undercoat layer 4 is formed, a coating solution in which the above components are added to a solvent is used. Examples of such solvents include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol, acetone, cyclohexanone, and 2-butanone. Ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, methyl acetate, ethyl acetate, n acetate -Organic solvents, such as ester solvents, such as butyl. These solvents are used alone or in combination of two or more. When mixing, any solvent can be used as long as it can dissolve the binder resin as a mixed solvent.

  In addition, as a method for dispersing the conductive metal oxide in the coating liquid for forming the undercoat layer 4, a media dispersing machine such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, stirring, ultrasonic wave Medialess dispersers such as dispersers, roll mills, and high-pressure homogenizers are used. Further, examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration method in which the fine liquid is penetrated and dispersed in a high pressure state.

  As a method of applying the coating liquid for forming the undercoat layer 4 on the support 2, a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, a curtain coating method. Law. The thickness of the undercoat layer 4 is preferably 15 μm or more, and more preferably 20 μm or more and 50 μm or less. Resin particles may be added to the undercoat layer 4 in order to adjust the surface roughness. As the resin particles, silicone resin particles, cross-linked PMMA resin particles, and the like are used.

  Further, the surface of the undercoat layer 4 may be polished for adjusting the surface roughness. As a polishing method, buffing, sandblasting, wet honing, grinding, or the like is used.

-Intermediate layer-
An intermediate layer (not shown) may be further provided on the undercoat layer 4. As the binder resin used for the intermediate layer, acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl In addition to polymer resins such as acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium, titanium, aluminum, manganese, silicon atom, etc. An organometallic compound containing These compounds are used alone or as a mixture or polycondensate of a plurality of compounds.

  As the solvent used for forming the intermediate layer, known organic solvents, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatics such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol Alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or linear such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether Examples include ether solvents, ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate. These solvents are used alone or in combination of two or more. Any solvent can be used as long as it can dissolve the binder resin as a mixed solvent.

As a coating method for forming the intermediate layer, a usual method such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, or a curtain coating method is used.
The thickness when forming the intermediate layer is preferably in the range of 0.1 μm or more and 3 μm or less.

-Charge generation layer-
The charge generation layer 5 is formed by depositing a charge generation material by a vacuum deposition method or by applying a solution containing an organic solvent and a binder resin.
Examples of charge generation materials include amorphous selenium, crystalline selenium, selenium-tellurium alloy, selenium-arsenic alloy, and other selenium compounds; inorganic photoconductors such as selenium alloy, zinc oxide, and titanium oxide; Sensitized, various phthalocyanine compounds such as metal-free phthalocyanine, titanyl phthalocyanine, copper phthalocyanine, tin phthalocyanine, gallium phthalocyanine; Various organic pigments such as salts; or dyes are used.

In addition, these organic pigments generally have several types of crystals. In particular, phthalocyanine compounds have various crystal types including α type and β type. Any of these crystal forms may be used as long as it is a pigment capable of obtaining characteristics.
Of the charge generation materials described above, phthalocyanine compounds are desirable. In this case, when the photosensitive layer is irradiated with light, the phthalocyanine compound contained in the photosensitive layer absorbs photons and generates carriers. At this time, since the phthalocyanine compound has a high quantum efficiency, the absorbed photons are efficiently absorbed to generate carriers.

Examples of the binder resin used for the charge generation layer 5 include the following. That is, polycarbonate resin such as bisphenol A type or bisphenol Z type and copolymers thereof, polyarylate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer resin Vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole and the like.
These binder resins may be used alone or in combination of two or more. The mixing ratio of the charge generation material and the binder resin (charge generation material: binder resin) is preferably in the range of 10: 1 to 1:10 in terms of mass ratio.
In general, the thickness of the charge generation layer 5 is desirably in the range of 0.01 μm to 5 μm, and more desirably in the range of 0.05 μm to 2.0 μm.

The charge generation layer 5 may contain at least one electron accepting substance for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, and the like. Examples of the electron accepting material used in the charge generation layer 5 include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-di Examples thereof include nitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, and phthalic acid. Of these, fluorenone-based, quinone-based, and benzene derivatives having electron-withdrawing substituents such as Cl, CN, NO ₂ are particularly preferable.
As a method for dispersing the charge generating material in the resin, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a dyno mill, a sand mill, and a colloid mill are used.

  A known organic solvent as a solvent for the coating solution for forming the charge generation layer 5, for example, an aromatic hydrocarbon solvent such as toluene or chlorobenzene, methanol, ethanol, n-propanol, iso-propanol, n-butanol or the like. Aliphatic alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or straight chain such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether Examples include chain ether solvents, ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate.

-Charge transport layer-
The charge transport layer 6 includes at least one kind of charge transport selected from a binder resin, a butadiene charge transport material represented by the general formula (1), and an enamine charge transport material represented by the general formula (2). Contains sex materials. When the charge transport layer 6 contains at least one selected from the butadiene-based charge transport material and the enamine-based charge transport material, potential unevenness after exposure is particularly reduced.
The total content of the butadiene-based charge transporting material and the enamine-based charge transporting material in the charge transport layer is desirably 3% by mass or more and 40% by mass or less from the viewpoint of suppressing potential unevenness after exposure.

As described above, the composition has a high mobility and is hardly affected by the injection of positive charges in the immediately preceding image forming cycle, so that the difference ΔVh between the maximum value and the minimum value of the surface potential after charging, and the exposure The difference ΔVL between the maximum value and the minimum value of the surface potential after being satisfied satisfies the relationship of the following formula (3), the potential unevenness after exposure is more reliably reduced, and color lines are effectively generated over a long period of time. It is suppressed.
ΔVL ≦ ΔVh × 1/4 (3)
In particular, when ΔVL is 5 V or less, the generation of color lines is more effectively suppressed.

  In this embodiment, the surface potential of the photoconductor 31 is measured by measuring the surface potential of the photoconductor for one round in the circumferential direction every 10 mm in the axial direction using a surface potential meter Trek 334 (manufactured by Trek). And the value obtained from the difference between the minimum value.

  The charge transport layer 6 may include a charge transport material other than the butadiene-based charge transport material and the enamine-based charge transport material. Examples of such charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, and xanthone compounds. , Electron transport compounds such as benzophenone compounds, cyanovinyl compounds, ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds And hole transporting compounds such as compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto. These charge transport materials may be used alone or in combination of two or more.

  Examples of the binder resin used for the charge transport layer 6 include polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, and vinylidene chloride. -Acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N -Vinylcarbazole, polysilane, and polymer charge transport materials such as polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 may be used. More desirably, it is a polycarbonate-based resin, and a copolymer including a plurality of polycarbonate structures may be used. These binder resins may be used alone or in combination of two or more. The blending ratio (mass ratio) between the charge transport material and the binder resin is preferably 10: 1 to 1: 5.

  Further, a polymer charge transport material may be used in combination. As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 have a high charge transport property and are particularly desirable.

Generally, the thickness of the charge transport layer 6 is desirably 5 μm or more and 50 μm or less, and more desirably 9 μm or more and 28 μm or less.
As a coating method of the coating liquid for forming the charge transport layer, a usual method such as a blade coating method, a Mayer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, etc. Is used.
Solvents used when the charge transport layer 6 is provided include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenation such as methylene chloride, chloroform and ethylene chloride. Usual organic solvents such as aliphatic hydrocarbons, cyclic or linear ethers such as tetrahydrofuran and ethyl ether are used alone or in admixture of two or more.

  In addition, additives such as antioxidants, light stabilizers, and heat stabilizers are added to the photosensitive layer for the purpose of preventing deterioration of the photoreceptor due to ozone, oxidizing gas, or light and heat generated in the image forming apparatus. It may be added. For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and their derivatives, organic sulfur compounds, and organic phosphorus compounds. Examples of the light stabilizer include derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine.

In addition, at least one kind of electron-accepting substance is contained for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue during repeated use. Examples of the electron acceptor used for the photoreceptor used in this embodiment include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane. O-dinitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like. Among these, benzene derivatives having electron-withdrawing substituents such as fluorenone-based, quinone-based, Cl, CN, and NO ₂ are particularly desirable.

  Further, various particles may be added in order to improve the contamination resistance adhesion and lubricity on the surface of the photoreceptor. They may be used alone or in combination. Examples of the particles include fluorine-based particles such as ethylene tetrafluoride, ethylene trifluoride, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, and “The 8th Polymer Materials Forum Lecture Collection p89-90”. Examples thereof include particles made of a resin obtained by copolymerizing the fluororesin and a monomer having a hydroxyl group.

  For the same purpose, an oil such as silicone oil may be added. Examples of the silicone oil include silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, and phenylmethylsiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, fluorine-modified polysiloxane, Examples thereof include reactive silicone oils such as methacryl-modified polysiloxane, mercapto-modified polysiloxane, and phenol-modified polysiloxane.

<Charging means>
The charging means 32 used in the present embodiment is a charge using a contact charging method in which the surface of the electrophotographic photosensitive member 31 rotates in contact with the surface, and a DC voltage is applied to charge the surface of the electrophotographic photosensitive member. Vessel. In the contact charging type charger, various known forms such as a roller, a brush, and a film are used. In particular, a roller-shaped charging member is applied.
The roller-shaped charging member is preferably in contact with the photoreceptor at a pressure of 250 mgf or more and 600 mgf or less.

The roller-shaped charging member 32 is made of a material adjusted to an electric resistance (10 ³ Ω or more and 10 ⁸ Ω or less) effective as a charging member, and may be made of a single layer or a plurality of layers.
Materials constituting the charging member include urethane rubber, silicone rubber, fluorine rubber, chloroprene rubber, butadiene rubber, EPDM (ethylene-propylene-diene copolymer rubber), epichlorohydrin rubber and other synthetic rubber, polyolefin, polystyrene, vinyl chloride, etc. A material obtained by blending an appropriate amount of an optional conductivity imparting agent such as conductive carbon, metal oxide, or ionic conductive agent is used. These materials can easily develop an effective electric resistance as a charging member.
Furthermore, a resin such as nylon, polyester, polystyrene, polyurethane, silicone, etc. is made into a paint, and an appropriate amount of a conductivity imparting agent such as conductive carbon, metal oxide, ionic conductive agent, etc. is blended there, and the resulting paint is dip coated. The film is laminated by any method such as spray coating or roll coating.

<Electrostatic latent image forming means>
As the electrostatic latent image forming unit 26 according to the present embodiment, a known exposure unit is used. For example, as an exposure light source, a polygonal mirror is used to emit laser light emitted from a single light emitting laser element that forms a minute spot diameter or a surface emitting laser element in which a plurality of semiconductor lasers (light emitting points) are two-dimensionally arranged in a plane. There are those that refract and those in which a plurality of LED (Light Emitting Diode) elements are arranged in a straight line or a staggered pattern. The light source irradiates the photosensitive drum with light corresponding to the image data for writing from the image processing apparatus, thereby writing an image. The amount of light at the time of writing is desirably 0.5 mJ / m ² or more and 5.0 mJ / m ² or less on the surface of the photoreceptor.

<Developing means>
The developing unit 33 used in the present embodiment is not particularly limited as long as it is a publicly known one. For example, a two-component developing type developing unit that develops a developing brush made of a carrier and toner in contact with a photosensitive member, For example, a contact type one-component developing type developing unit that attaches toner onto a conductive rubber elastic body conveying roll (developing roll) and develops the toner on the photosensitive member is used.

In the case of the two-component development method, the rotation direction of the developing roll may be the same direction as the rotation direction of the photoconductor 31 (the direction of arrow A in FIG. 1) or the reverse direction. As a result, the recoverability of the residual toner on the photoreceptor 31 is improved. The electric field applied to the developing roll may be a direct current or an alternating current superimposed on the direct current.
In addition, in order to improve the toner recovery property and the discharge product scraping property, the magnetic brush formed on the surface of the developing roll is controlled by a layer regulating member so that the density of the magnetic brush facing the photoreceptor is always constant. It is desirable that the magnetic brush density is adjusted within an appropriate range by controlling the layers.
When the normal polarity of the toner is negative, the bias applied to the developing roll is preferably in the range of −50 V to −600 V, and more preferably in the range of −100 V to −350 V.

-Toner-
The toner used in the exemplary embodiment is not particularly limited as long as it is a known toner. Further, the toner contains a binder resin and a colorant, and may contain a release agent as necessary. Furthermore, external additives other than those described above may be added as necessary.
The toner may contain various components in order to control various characteristics. For example, when used as a magnetic toner, it may contain magnetic powder (for example, ferrite or magnetite), metal such as reduced iron, cobalt, nickel, manganese, an alloy, or a compound containing these metals. Further, if necessary, a charge control agent usually used such as a quaternary ammonium salt, a nigrosine compound or a triphenylmethane pigment may be appropriately selected and contained.
Furthermore, in addition to the abrasive | polishing agent which consists of inorganic particles, well-known external additives, such as a lubricant agent and a transfer aid, are externally added to the toner.
The method for producing the toner used in the present embodiment is not particularly limited. For example, a normal pulverization method, a wet melt spheronization method prepared in a dispersion medium, suspension polymerization, dispersion polymerization, A toner production method using a known polymerization method such as an emulsion polymerization aggregation method is used.

-Career-
When the developer used in this embodiment is a two-component developer composed of a toner and a carrier, the carrier to be used is not particularly limited, and a known carrier is used. For example, a carrier (non-coated carrier) consisting only of a core material such as a magnetic metal such as iron oxide, nickel or cobalt, or a magnetic oxide such as ferrite or magnetite, or a resin-coated carrier provided with a resin layer on the surface of these core materials Is used.
In the two-component developer using the carrier described above, the mixing ratio (mass ratio) of the toner and the carrier is in the range of toner: carrier = 1: 100 to 30: 100, and 3: 100 to 20: 100. A range of degree is more desirable.

<Transfer means>
As the transfer means 40 according to the present embodiment, those using a known transfer system are used. For example, a direct transfer method using a transfer corotron, a transfer roll, etc., an intermediate transfer method using an intermediate transfer member such as an intermediate transfer belt or an intermediate transfer drum, and a recording medium is electrostatically adsorbed and conveyed on the photoconductor And a transfer means using a transfer belt system for transferring the toner image.

<Cleaning means>
As the cleaning means 36 according to the present embodiment, a known cleaning method is used. For example, when a cleaning blade is used, the cleaning blade needs to be made of an elastic member at a portion in contact with the surface of the photoconductor, and the elastic member must have a 100% modulus of 6.5 MPa or more, and 7.0 MPa or more. More desirably, it is more desirably 9.0 MPa or more. When the 100% modulus of the elastic member is less than 6.5 MPa, the hardness is lowered and the dynamic deflection of the cleaning blade is increased, so that uneven wear of the photoreceptor is not suppressed. On the other hand, if the 100% modulus of the elastic member is too large, the followability of the cleaning blade to the photoreceptor may deteriorate and sufficient cleaning properties may not be obtained. Therefore, the 100% modulus of the elastic member is desirably 19.6 MPa or less, and more desirably 15.0 MPa or less.

Further, the elastic member preferably has an elongation at break of 250% or more, more preferably 300% or more, and further preferably 350% or more.
As the material constituting the cleaning blade, a known rubber elastic body is used, and other materials may be added as necessary. The rubber elastic body is not particularly limited, and rubber urethane rubber, silicone rubber, acrylic rubber, acrylonitrile rubber, butadiene rubber, styrene rubber, or a composite material thereof is used. Further, a plate shape is desirably used as the shape of the base material, and it is formed using centrifugal molding, extrusion molding, mold molding or the like.

  FIG. 3 schematically shows another example of the image forming apparatus according to the present embodiment. An image forming apparatus 200 shown in FIG. 3 is an intermediate transfer type image forming apparatus. In the housing 400, four photoconductors 401a to 401d (for example, the photoconductor 401a is yellow, the photoconductor 401b is magenta, and the photoconductor 401c is cyan, The photosensitive member 401d forms an image having a black color) and is arranged in parallel along the intermediate transfer belt 409.

Here, each of the photoconductors 401a to 401d mounted in the image forming apparatus 200 includes a charge transport layer, a binder resin, the butadiene-based charge transport material, and the photoconductor according to the present embodiment described above. It contains at least one selected from the enamine charge transport materials.
Further, the charging rolls 402a to 402d rotate in contact with the surfaces of the photoconductors 401a to 401d, respectively, and a DC voltage is applied to charge the surface of each photoconductor.

  Each of the photoreceptors 401a to 401d rotates in a predetermined direction (counterclockwise in the drawing), and along the rotation direction, the charging rolls 402a to 402d, the developing devices 404a to 404d, and the primary transfer roll 410a. 410d and cleaning blades 415a to 415d are arranged. Each of the developing devices 404a to 404d can supply toners of four colors, yellow, magenta, cyan, and black, contained in the toner cartridges 405a to 405d, and the primary transfer rolls 410a to 410d are respectively intermediate. The photoconductors 401a to 401d are in contact with each other via the transfer belt 409.

  Further, a laser light source 403 as an example of an exposure apparatus is disposed at a predetermined position in the housing 400, and laser light emitted from the laser light source 403 is irradiated on the surfaces of the photosensitive members 401a to 401d after charging. The Thus, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the photosensitive members 401a to 401d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 409 in an overlapping manner. The intermediate transfer belt 409 is supported with a tension determined by a drive roll 406, a counter roll 408, and a tension roll 407, and can rotate without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to come into contact with the counter roll 408 via the intermediate transfer belt 409. The intermediate transfer belt 409 that has passed through the region sandwiched between the opposing roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed facing the drive roll 406, and then the next image forming process. Repeatedly served.

  In addition, a recording medium container 411 is provided at a predetermined position in the housing 400, and the recording medium 500 such as paper in the recording medium container 411 is moved by the transfer roll 412 and the intermediate transfer belt 409 and the secondary transfer roll. The sheet is sequentially transferred to a region sandwiched by 413 and further to a region sandwiched by two fixing rolls 414 that are in contact with each other, and then discharged to the outside of the housing 400.

  In the above description, the case where the intermediate transfer belt 409 is used as the intermediate transfer member has been described. However, the intermediate transfer member may have a belt shape like the intermediate transfer belt 409 or a drum shape. Also good. In the case of a belt shape, conventionally known resins are used as the resin material used as the base material of the intermediate transfer member. For example, polyimide resin, polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene terephthalate (PAT), ethylenetetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend material, polyester Resin materials such as polyetheretherketone and polyamide, and resin materials containing these as main raw materials. Further, a resin material and an elastic material may be blended and used.

Next, an example of the process cartridge according to the present embodiment will be described.
The process cartridge according to the exemplary embodiment includes an electrophotographic photosensitive member having a photosensitive layer including a binder resin and at least one selected from the butadiene-based charge transporting material and the enamine-based charge transporting material, and the electrophotographic process. Charging means for rotating in contact with the surface of the photoreceptor and applying a DC voltage to charge the surface of the electrophotographic photoreceptor.

FIG. 4 schematically shows an example of the basic configuration of the process cartridge according to the present embodiment. This process cartridge 300 combines, together with the photoreceptor 307, a charging device 308, a developing device 311, a cleaning device 313, an opening 318 for exposure, and an opening 317 for static elimination exposure using a mounting rail 316. It is an integrated one.
The process cartridge 300 is detachable from an image forming apparatus main body including a transfer device 312, a fixing device 315, and other components not shown, and constitutes an image forming apparatus together with the image forming apparatus main body. To do.

  In this process cartridge 300 as well, the photoreceptor 307 includes at least one selected from the binder resin, the butadiene based charge transporting material, and the enamine based charge transporting material in the charge transporting layer. The charging device 308 rotates in contact with the surface of the photoconductor 307, and a DC voltage is applied to charge the surface of the photoconductor.

  The recording medium 500 used in the present embodiment is not particularly limited as long as it is a medium that transfers a toner image formed on a photoreceptor. For example, when transferring directly from a photoreceptor to a recording medium such as paper, paper or the like is the recording medium. When an intermediate transfer member is used, the intermediate transfer member is a recording medium.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

-Production of photoreceptor 1-
100 parts by mass of zinc oxide (average particle size: 70 nm, manufactured by Teica, specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts by mass of methanol, and KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent. 25 parts by mass was added and stirred for 2 hours. Thereafter, methanol was distilled off under reduced pressure, and baking was performed at 120 ° C. for 3 hours to obtain silane coupling agent surface-treated zinc oxide fine particles.

  60 parts by mass of the zinc oxide fine particles subjected to the surface treatment, 0.6 parts by mass of alizarin, 13.5 parts by mass of blocked isocyanate (Sumidule 3173, manufactured by Sumitomo Bayern Urethane Co., Ltd.) as a curing agent, and butyral resin (BM -1, made by Sekisui Chemical Co., Ltd.) 15 parts by mass, a solution of 38 parts by mass of methyl ethyl ketone dissolved in 85 parts by mass of methyl ethyl ketone and 25 parts by mass of methyl ethyl ketone were mixed, and 4 hours in a sand mill using glass beads having a diameter of 1 mm. Dispersion was performed to obtain a dispersion. To the obtained dispersion, 0.005 parts by mass of dioctyltin dilaurate and 4.0 parts by mass of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone) are added as a catalyst, and a coating liquid for forming an undercoat layer is added. Obtained. This coating solution was applied on an aluminum substrate having a diameter of 30 mm by a dip coating method, followed by drying and curing at 180 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 25 μm.

  Next, as a charge generation material, it has strong diffraction peaks at Bragg angles (2θ ± 0.2 °) with respect to CuKα characteristic X-rays of at least 7.4 °, 16.6 °, 25.5 ° and 28.3 °. Using a glass bead having a diameter of 1 mm, a mixture of 15 parts by mass of chlorogallium phthalocyanine crystal, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide) and 300 parts by mass of n-butyl alcohol was used. Then, it was dispersed in a sand mill for 4 hours to obtain a coating solution for forming a charge generation layer. This coating solution was dip-coated on the undercoat layer and dried to obtain a charge generation layer having a thickness of 0.2 μm.

  Next, 8 parts by mass of tetrafluoroethylene resin particles (average particle size: 0.2 μm) and 0.01 parts by mass of a fluorinated alkyl group-containing methacrylic copolymer (weight average molecular weight 30000), 4 parts by mass of tetrahydrofuran, toluene The mixture was kept at a liquid temperature of 20 ° C. together with 1 part by mass and stirred for 48 hours to obtain a tetrafluoroethylene resin particle suspension A.

Next, as a charge transport material, the following structural formula (1) (in the general formula (1), n = 1, m = 1, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are all H Compound), 4 parts by mass of tris [4- (4,4-diphenyl-1,3-butadienyl) phenyl] amine, and 6 parts of bisphenol Z-type polycarbonate resin (viscosity average molecular weight: 40000) as a binder resin Parts, 2,6-di-t-butyl-4-methylphenol 0.1 parts by mass as an antioxidant, 24 parts by mass of tetrahydrofuran and 11 parts by mass of toluene are mixed and dissolved, and mixed solution B is obtained. Obtained.

After the A liquid was added to the B liquid and stirred and mixed, the pressure was increased to 500 kgf / cm ² using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a through-type chamber having a fine flow path. 5 ppm of fluorine-modified silicone oil (trade name: FL-100 manufactured by Shin-Etsu Silicone Co., Ltd.) was added to the solution obtained by repeating the dispersion treatment six times, and the mixture was sufficiently stirred to obtain a coating solution for forming a charge transport layer. This coating solution was applied onto the charge generation layer and dried at 135 ° C. for 25 minutes to form a charge transport layer having a thickness of 20 μm, thereby obtaining the intended electrophotographic photosensitive member. The electrophotographic photoreceptor thus obtained was designated as photoreceptor 1.

-Production of photoreceptor 2-
Instead of the compound of the structural formula (1) used as the charge transport material in Example 1, an enamine derivative of the following structural formula (2) (in the general formula (2), R ⁹ is OCH ₃ , R ⁷ , R ⁸ , R ¹⁰ , R ¹¹ , and R ¹² are H) The photoconductor 2 was prepared in the same manner as the photoconductor 1 except that 4 parts by mass was used.

-Production of photoreceptor 3-
Instead of the compound of structural formula (1) used as the charge transport material in Example 1, 2 parts by mass of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine and N, N′-bis A photoconductor 3 was prepared in the same manner as the photoconductor 1 except that 2 parts by mass of (3,4-dimethylphenyl) biphenyl-4-amine was used.

<Evaluation>
The photoconductor 1 was incorporated in an image forming apparatus to be described later having the configuration shown in FIG. 1, and a negative DC voltage of −400 V was applied to the charging unit as Example 1.
Example 2 was the same as Example 1 except that Photoreceptor 2 was used as the photoreceptor.
For comparison, the same configuration as in Example 1 except that the photoconductor 3 was used as the photoconductor, and Comparative Example 1, and the charging means was applied with an orthogonal superimposed voltage of DC component -400 V and AC component 1.5 kVp-p. A comparative example 2 was constructed in the same manner as in Example 1 except that it was applied.

-Uneven charging potential-
The charging potential unevenness ΔVh is obtained by incorporating a working example and a comparative example in a modified machine of DocuCentre 505a (manufactured by Fuji Xerox Co., Ltd.), performing a charging step, and using a surface potential meter Trek 334 (manufactured by Trek Co.). Was obtained by measuring the surface potential of each in the circumferential direction for every 10 mm in the axial direction and measuring the difference (V) between the maximum value and the minimum value of the potential. The difference ΔVh between the maximum value and the minimum value of the surface potential after charging and the difference ΔVL between the maximum value and the minimum value of the surface potential after exposure were measured.
Table 1 shows the configurations, charging conditions, and surface potential unevenness ΔVh after charging in this example and the comparative example.

-Surface potential unevenness after exposure-
The charging potential unevenness ΔVL is obtained by incorporating the respective photoconductors and charging means of Examples and Comparative Examples into a modified machine of DocuCentre 505a (manufactured by Fuji Xerox Co., Ltd.), and performing a charging process and an exposure process (exposure light amount 3.5 mJ / m ² ). The surface potential of the photoconductor is measured for every 10 mm in the axial direction using a surface potential meter Trek 334 (manufactured by Trek), and the difference between the maximum value and the minimum value of the potential is measured. Obtained.

-Small color line-
The minute color line is obtained by incorporating an example and a comparative example into a modified DocuCentre 505a, and using a random character chart with an image density of 5% in a high-temperature and high-humidity environment of 28 ° C. and 85 RH%, A4 sheets of A4 After continuous printing, a 20% halftone image was output and evaluated by counting the number of fine color lines on the image.

○: Not generated Δ: 1 or more and 10 or less generated ×: 11 or more generated

-Photoreceptor wear amount-
The amount of wear was 80000 A4 continuous images using a random character chart with an image density of 5% in a high-temperature and high-humidity environment of 28 ° C. and 85RH% by incorporating an example and a comparative example into a modified DocuCentre 505a. After printing, the film thickness of the photoreceptor was evaluated by measuring with an eddy current film thickness measuring device (Fischer Instruments).

  Table 2 shows the evaluation results of the post-exposure potential unevenness ΔVL, the number of minute color lines generated, and the photoreceptor wear amount.

2 conductive support, 3 photosensitive layer, 4 undercoat layer, 5 charge generation layer, 6 charge transport layer, 26 laser exposure device (an example of electrostatic latent image forming means), 31 electrophotographic photoreceptor, 32 charging means, 33 Developing unit, 36 Cleaning unit, 40 Primary transfer roll (an example of transfer unit), 40 Transfer unit, 100, 200 Image forming apparatus, 300 Process cartridge

Claims (4)

A photosensitive resin comprising a binder resin and at least one selected from a charge transporting material having a structure represented by the following general formula (1) and a charge transporting material having a structure represented by the following general formula (2). An electrophotographic photoreceptor having a layer;
Charging means for rotating in contact with the surface of the electrophotographic photosensitive member and charging the surface of the electrophotographic photosensitive member by applying a DC voltage;
An electrostatic latent image forming means for exposing the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image;
Developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
Transfer means for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a recording medium;
An image forming apparatus.

(In General Formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 carbon atom. It represents an alkoxy group having 20 or less or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure, where n and m are each Independently represents 0 or 1)

(In General Formula (2), R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 carbon atom. Represents an alkoxy group having 20 or less or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure.) The difference ΔVh between the maximum value and the minimum value of the surface potential after the electrophotographic photosensitive member is charged by the charging unit, and the maximum value and the minimum value of the surface potential after the electrostatic latent image forming unit is exposed. The image forming apparatus according to claim 1, wherein the difference ΔVL satisfies the relationship of the following formula (3).
ΔVL ≦ ΔVh × 1/4 (3)   The image forming apparatus according to claim 2, wherein the ΔVh is 20 V or less. A photosensitive resin comprising a binder resin and at least one selected from a charge transporting material having a structure represented by the following general formula (1) and a charge transporting material having a structure represented by the following general formula (2). An electrophotographic photoreceptor having a layer;
Charging means for rotating in contact with the surface of the electrophotographic photosensitive member and charging the surface of the electrophotographic photosensitive member by applying a DC voltage;
Process cartridge with

(In General Formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 carbon atom. It represents an alkoxy group having 20 or less or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure, where n and m are each Independently represents 0 or 1)

(In General Formula (2), R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 carbon atom. Represents an alkoxy group having 20 or less or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and two adjacent substituents may form a hydrocarbon ring structure.)

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