JP2006343487A - Electrophotographic photoreceptor and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor without causing density variation each time repeating a small number of copies. <P>SOLUTION: The electrophotographic photoreceptor is used in an electrophotographic apparatus which includes a charging means charging the electrophotographic photoreceptor by bringing a charging member into contact with it and which has a process speed equal to or more than 220 mm/second. In the electrophotographic photoreceptor including a conductive support, a charge generation layer containing a charge generation material provided on the conductive support, and a hole transport layer containing a hole transport material provided on the charge generation layer, an intermediate layer or the charge generation layer contains a proper electron conveying compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member and an electrophotographic apparatus used for a copying machine, a laser beam printer, and the like.

  Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used for electrophotographic photoreceptors. On the other hand, as an electrophotographic photosensitive member using an organic photoconductive substance, a photoconductive polymer represented by poly-N-vinylcarbazole and 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadi Those using a low molecular organic photoconductive substance such as azole, and those obtained by combining such organic photoconductive substance with various dyes and pigments are known.

  An electrophotographic photosensitive member using an organic conductive material has good film formability and can be produced by coating, and therefore has an advantage of providing an electrophotographic photosensitive member that is extremely high in productivity and inexpensive. Moreover, it has an advantage that the photosensitive wavelength range can be freely controlled by selecting a dye or a pigment to be used, and has been extensively studied so far. In particular, the development of a functionally-separated type photoreceptor in which a charge generation layer containing an organic conductive dye or pigment and a charge transport layer containing a photoconductive polymer or a low-molecular organic photoconductive material are laminated has been developed recently. The sensitivity and durability that have been regarded as disadvantages of the organic electrophotographic photoreceptors have been remarkably improved, and this has become the mainstream of organic electrophotographic photoreceptors.

  On the other hand, in recent copying machines and laser beam printers, in order to increase the speed and cost, the process speed has been increased and fine process conditions have not been controlled (saving of various sensors and control circuits). In addition, improvement in image quality and image stability represented by the POD market is also required. When conventional photoconductors are used in these electrophotographic apparatuses, there is a problem that the fluctuation of the bright portion potential is large. If the bright part potential is not stable, the image density is not stable, and there is a drawback that the density changes between the image at the initial stage of the photoconductor and the image at the end stage.

Various proposals have been made as a method for suppressing the fluctuation of the bright portion potential during the durability. (For example, refer to Patent Document 1.)
JP 2004-93809 (2nd page)

  However, even if these improved photoreceptors are used, in the severe environment such as a high-speed process and a low temperature and low humidity environment, the initial portion of the bright part potential fluctuation is remarkable, and the initial number of tens of sheets varies by several tens of volts. As a result, there has been a problem that a significant density change occurs in the initial dozens of copy images. Unlike fluctuations due to endurance, this is a serious drawback in that the density is changed each time a small number of copies are repeated, since it is almost recovered in a short time after image formation.

The present invention
An electrophotographic photosensitive member for use in an electrophotographic apparatus having a charging means for bringing a charging member into contact with the electrophotographic photosensitive member for charging and having a process speed of 220 mm / sec or more, comprising the conductive support and the conductive support In an electrophotographic photosensitive member having a charge generation layer containing a charge generation material provided on the body, and a hole transport layer containing a hole transport material provided on the charge generation layer,
The surface potential of the electrophotographic photosensitive member is set to −600 [V] by rotating the electrophotographic photosensitive member 5 times while charging the surface of the electrophotographic photosensitive member by the charging means set to the predetermined charging condition C1, Next, the surface potential of the electrophotographic photosensitive member is set to −150 [V] by irradiating the surface of the electrophotographic photosensitive member having a surface potential of −600 [V] with a predetermined amount of light E1. The surface potential of the electrophotographic photosensitive member after charging the surface of the electrophotographic photosensitive member having a value of −150 [V] by the charging means set in the charging condition C1 is VA [V],
The surface potential of the electrophotographic photosensitive member is set to −150 [V] by rotating the electrophotographic photosensitive member 5 times while charging the surface of the electrophotographic photosensitive member by a charging unit set to a predetermined charging condition C2. Next, the surface potential of the electrophotographic photosensitive member after the surface potential of the electrophotographic photosensitive member having a surface potential of −150 [V] is charged by the charging unit set under the same condition as the charging condition C1 is expressed as VB [ V],
When the film thickness of the hole transport layer is d [μm], the VA, VB and d are represented by the following formula (I)

を満足することを特徴とする電子写真感光体である。

Is an electrophotographic photosensitive member characterized by satisfying the above.

  The present invention also provides a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  The electrophotographic photosensitive member of the present invention is less affected by carrier traps even under harsh environments such as high-speed processes and low-temperature, low-humidity environments, and suppresses initial tens of light-area potential fluctuations. The remarkable density change which generate | occur | produces can be suppressed and the outstanding image can be formed continuously.

  The effect of the electrophotographic photosensitive member is naturally exhibited also in a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  Hereinafter, the present invention will be described in detail.

  The structure of the electrophotographic photosensitive member of the present invention will be described.

  As the conductive support used in the present invention, a metal or alloy such as aluminum, nickel, copper, gold, iron, etc., a metal such as aluminum, silver, gold or the like on an insulating support such as polyester, polycarbonate, polyimide, glass or the like Examples thereof include those in which a thin film of a conductive material such as indium oxide and tin oxide is formed, carbon and conductive fillers dispersed in a resin, and conductivity is imparted. These support surfaces were subjected to electrochemical treatment such as anodization to improve electrical characteristics or adhesion, and conductive support surfaces were treated with alkali phosphate, phosphoric acid or tannic acid. It is also possible to use a solution obtained by chemical treatment with a solution obtained by dissolving a metal salt compound or a fluorine compound metal salt in an acidic aqueous solution containing as a main component.

  Further, when the present photoreceptor is used in a printer using a single wavelength laser beam or the like, the surface of the conductive support needs to be appropriately roughened in order to suppress interference fringes. Specifically, a support having the surface of the support subjected to honing, blasting, cutting, electropolishing, or the like, or a support having a conductive film made of a conductive metal oxide and a binder resin on aluminum and an aluminum alloy is provided. It is necessary to use it.

  As the honing treatment, there are dry and wet treatment methods, and any of them may be used. The wet honing treatment is a method of suspending a powdery abrasive in a liquid such as water and spraying the surface of the substrate at a high speed to roughen the surface. The surface roughness is the spray pressure, speed, amount of abrasive, It can be controlled by the type, shape, size, hardness, specific gravity, suspension temperature and the like. Similarly, the dry honing process is a method in which an abrasive is sprayed onto the surface of a conductive substrate with air at a high speed to roughen the surface, and the surface roughness can be controlled in the same manner as the wet honing process. Examples of the abrasive used for the wet or dry honing treatment include particles of silicon carbide, alumina, iron, glass beads, and the like.

  In a method in which a conductive film made of a conductive metal oxide and a binder resin is applied to a support of aluminum or aluminum alloy to form a conductive support, a powder made of conductive fine particles is used as a filler in the conductive film. Containing. In this method, fine particles are dispersed in the film, so that the laser beam is diffusely reflected to prevent interference fringes and to conceal the scratches and protrusions of the support before coating. Titanium oxide, barium sulfate, or the like is used for the fine particles, and if necessary, a conductive coating layer is provided on the fine particles with tin oxide or the like to obtain a specific resistance suitable as a filler. The specific resistance of the conductive fine particle powder is preferably 0.1 to 1000 Ωcm, more preferably 1 to 1000 Ωcm. In the present invention, the powder specific resistance was measured using a resistance measuring apparatus Loresta AP (Lorest A Ap) manufactured by Mitsubishi Oil Corporation. The powder to be measured was hardened at a pressure of 49 MPa and attached to the measuring device as a coin-shaped sample. The average particle size of the fine particles is preferably 0.05 to 1.0 μm, more preferably 0.07 to 0.7 μm. In the present invention, the average particle diameter of the fine particles is a value measured by a centrifugal sedimentation method. The filler content is preferably from 1.0 to 90 mass%, more preferably from 5.0 to 80 mass%, based on the conductive film layer. The coating layer may contain fluorine or antimony as necessary.

  As the binder resin used for the conductive film of the present invention, for example, phenol resin, polyurethane, polyamide, polyimide, polyamideimide, polyamic acid, polyvinyl acetal, epoxy resin, acrylic resin, melamine resin or polyester is preferable. These resins may be used alone or in combination of two or more. These resins have good adhesion to the support, improve dispersibility of the filler used in the present invention, and have good solvent resistance after film formation. Among the above resins, phenol resin, polyurethane and polyamic acid are particularly preferable.

The conductive film can be formed, for example, by dip coating or solvent application using a Meyer bar or the like. The thickness of the conductive film is preferably 0.1 to 30 μm, more preferably 0.5 to 20 μm. The volume resistivity of the conductive film is preferably 10 ¹³ Ωcm or less, more preferably 10 ¹² Ωcm or less and 10 ⁵ Ωcm or more. In the present invention, the volume resistivity is obtained by applying a conductive film to be measured on an aluminum plate, further forming a gold thin film on the film, and calculating the current value flowing between both electrodes of the aluminum plate and the gold thin film as pA. It was determined by measuring with a meter. The conductive film may contain a filler made of powder such as zinc oxide or titanium oxide in addition to the powder made of barium sulfate fine particles having a coating layer. Furthermore, a leveling agent may be added to enhance the surface property.

  The shape of the conductive support is not particularly limited, and a plate shape, a drum shape, or a belt shape is used as necessary.

  Examples of the charge generating material used in the present invention include (1) azo pigments such as monoazo, disazo and trisazo, (2) phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, and (3) indigo materials such as indigo and thioindigo. Pigments, (4) perylene pigments such as perylene acid anhydride and perylene imide, (5) polycyclic quinone pigments such as anthraquinone and pyrenequinone, (6) squarylium dyes, (7) pyrylium salts, thiapyrylium salts, ( 8) Triphenylmethane dyes, (9) inorganic materials such as selenium, selenium tellurium, amorphous silicon, (10) quinacridone pigments, (11) azulenium salt pigments, (12) cyanine dyes, (13) xanthene dyes, (14) Quinoneimine dyes, (15) styryl dyes, (16) cadmium sulfide and ( 7) zinc oxide. In particular, metal phthalocyanine pigments are preferred, and among them, oxytitanium phthalocyanine crystals, chlorogallium phthalocyanine crystals, dichlorotin phthalocyanine crystals, and hydroxygallium phthalocyanine pigments are preferred, and hydroxygallium phthalocyanine pigments are particularly preferred. As an oxytitanium phthalocyanine pigment, it is strong in Bragg angles (2θ ± 0.2 °) of 9.0 °, 14.2 °, 23.9 ° and 27.1 ° in X-ray diffraction using CuKα as a radiation source. Oxytitanium phthalocyanine pigments with peaks, Bragg angles (2θ ± 0.2 °) of 9.5 °, 9.7 °, 11.7 °, 15.0 °, 23.5 °, 24.1 ° and 27 An oxytitanium phthalocyanine pigment having a strong peak at 3 ° is preferred. As a chlorogallium phthalocyanine crystal, in X-ray diffraction using CuKα as a radiation source, strong diffraction at Bragg angles (2θ ± 0.2 °) of 7.4 °, 16.6 °, 25.5 and 28.2 ° Chlorogallium phthalocyanine crystals having peaks, chlorogallium phthalocyanine crystals having strong diffraction peaks at Bragg angles (2θ ± 0.2 °) of 6.8 °, 17.3 °, 23.6 ° and 26.9 °, and Chlorogallium phthalocyanine crystals having strong diffraction peaks at Bragg angles (2θ ± 0.2 °) of 8.7 to 9.2 °, 17.6 °, 24.0 °, 27.4 ° and 28.8 ° preferable. As the dichlorotin phthalocyanine crystal, in X-ray diffraction using CuKα as a radiation source, Bragg angles (2θ ± 0.2 °) of 8.3 °, 12.2 °, 13.7 °, 15.9 °, 18 Dichlorotin phthalocyanine crystals with strong diffraction peaks at .9 ° and 28.2 °, strong at Bragg angles (2θ ± 0.2 °) of 8.5, 11.2 °, 14.5 ° and 27.2 ° Dichlorotin phthalocyanine crystal having a diffraction peak, Bragg angle (2θ ± 0.2 °) of 8.7 °, 9.9 °, 10.9 °, 13.1 °, 15.2 °, 16.3 °, Dichlorotin phthalocyanine crystals with strong diffraction peaks at 17.4 °, 21.9 ° and 25.5 °, and 9.2 °, 12.2 °, 13.4 with Bragg angles (2θ ± 0.2 °) Strong diffraction peaks at °, 14.6 °, 17.0 ° and 25.3 ° Chloro phthalocyanine crystal is preferable. As the hydroxygallium phthalocyanine crystal, in X-ray diffraction using CuKα as a radiation source, hydroxy having strong diffraction peaks at Bragg angles (2θ ± 0.2 °) of 7.3 °, 24.9 °, and 28.1 °. Gallium phthalocyanine crystals, Bragg angles (2θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 ° A hydroxygallium phthalocyanine crystal having a strong diffraction peak is preferred.

  Examples of the electron transporting compound added to the charge generation layer include fluorenone compounds such as trinitrofluorenone, imide compounds such as pyromellitic imide and naphthylimide, quinones such as benzoquinone, diphenoquinone, diiminoquinone, naphthoquinone, stilbenequinone, and anthraquinone. Compounds, fluorenylidene compounds such as fluorenylidene aniline, fluorenylidene malononitrile, carboxylic acid anhydride compounds such as phthalic anhydride, cyclic sulfone compounds such as thiopyran dioxide, oxadiazole compounds, triazoles Compounds, derivatives thereof, and the like can be mentioned, but are not limited thereto.

  In particular, a naphthalenecarboxylic acid diimide compound represented by the following general formula (1), a phenanthrene compound represented by the following general formula (2), a phenanthroline compound represented by the following general formula (3), or the following general formula ( The acenaphthoquinone compound represented by 4) is preferred.

（式中、Ｘ_１またはＸ_２はそれぞれ独立に水素原子、ハロゲン基、ニトロ基、置換基を有してもよいアルコキシ基または置換基を有してもよいアルキル基を示し、Ｒ_１及びＲ_２はそれぞれ独立にはエーテル基で中断されていてもよいアルキル基、エーテル基で中断されていてもよいアルケニル基、複素環基、アルキル基乃至アルケニル基乃至ニトロ基乃至ハロゲン基乃至ハロゲン置換アルキル基を有してもよいアリール基またはアルキル基乃至アルケニル基乃至ニトロ基乃至ハロゲン基乃至ハロゲン置換アルキル基を有してもよいアラルキル基を示す。）

(In the formula, X _{1 and} X ₂ each independently represent a hydrogen atom, a halogen group, a nitro group, an optionally substituted alkoxy group or an optionally substituted alkyl group, and R ₁ and R 2 ₂ are each independently an alkyl group which may be interrupted by an ether group, an alkenyl group which may be interrupted by an ether group, a heterocyclic group, an alkyl group, an alkenyl group, a nitro group, a halogen group or a halogen-substituted alkyl group. An aryl group which may have an alkyl group, an alkenyl group, a nitro group, a halogen group or a halogen-substituted alkyl group which may have an aralkyl group.

（式中、Ｚ_１、Ｚ_２はそれぞれ独立に酸素、Ｃ（ＣＮ）_２基、置換基を有しても良いＮフェニル基を示し、Ｘ_３、Ｘ_４はそれぞれ独立に水素原子、ハロゲン基、ニトロ基、置換基を有してもよいアルコキシ基または置換基を有してもよいアルキル基を示す。）

(In the formula, Z ₁ and Z ₂ each independently represent oxygen, C (CN) ₂ group, or N phenyl group which may have a substituent, and X ₃ and X ₄ each independently represent a hydrogen atom or a halogen group. , A nitro group, an alkoxy group which may have a substituent or an alkyl group which may have a substituent.

（式中、Ｚ_３、Ｚ_４はそれぞれ独立に酸素、Ｃ（ＣＮ）_２基、置換基を有しても良いＮフェニル基を示し、Ｘ_５、Ｘ_６はそれぞれ独立に水素原子、ハロゲン基、ニトロ基、置換基を有してもよいアルコキシ基または置換基を有してもよいアルキル基を示す。）

(In the formula, Z ₃ and Z ₄ each independently represent oxygen, C (CN) ₂ group, or optionally substituted N phenyl group, and X ₅ and X ₆ each independently represent a hydrogen atom or a halogen group. , A nitro group, an alkoxy group which may have a substituent or an alkyl group which may have a substituent.

（式中、Ｚ_５、Ｚ₆はそれぞれ独立に酸素、Ｃ（ＣＮ）_２基、置換基を有しても良いＮフェニル基を示し、Ｘ_７、Ｘ_８はそれぞれ独立に水素原子、ハロゲン基、ニトロ基、置換基を有してもよいアルコキシ基または置換基を有してもよいアルキル基を示す。）
次に上記一般式（１）〜（４）の化合物例を次の表１〜７に挙げるがこれらに限定されるわけではない。

(In the formula, Z ₅ and Z ₆ each independently represent oxygen, C (CN) ₂ group, or optionally substituted N-phenyl group; X ₇ and X ₈ each independently represent a hydrogen atom or a halogen group; , A nitro group, an alkoxy group which may have a substituent or an alkyl group which may have a substituent.
Next, although the compound examples of the said General formula (1)-(4) are given to the following Tables 1-7, it is not necessarily limited to these.

一般式（１）の化合物例

Examples of compounds of general formula (1)

一般式（１）の化合物例

Examples of compounds of general formula (1)

一般式（２）の化合物例

Example of compound of general formula (2)

一般式（２）の化合物例

Example of compound of general formula (2)

一般式（３）の化合物例

Example of compound of general formula (3)

一般式（４）の化合物例

Example of compound of general formula (4)

一般式（４）の化合物例
上記一般式（１）で表されるナフタレンカルボン酸ジイミド化合物がよく、溶媒への溶解性の観点から非対称系が更に好ましい。

Compound Example of General Formula (4) The naphthalenecarboxylic acid diimide compound represented by the above general formula (1) is preferable, and an asymmetric system is more preferable from the viewpoint of solubility in a solvent.

  The reduction potential of the electron-transporting compound or electron-accepting substance (with a saturated calomel electrode) is preferably 0.00 to −0.80 V, more preferably −0.25 to −0.65 V. The amount of the electron transporting compound or the electron accepting substance added is preferably 10 to 60% by mass, and more preferably 21 to 40% by mass with respect to the charge generation material. As binder resins, butyral resin, polyester resin, polycarbonate resin, polyarylate resin, polystyrene resin, polyvinyl methacrylate resin, polyvinyl acrylate resin, polyvinyl acetate resin, polyvinyl chloride resin, polyamide resin, polyurethane resin, silicone resin, alkyd Examples include, but are not limited to, resins, epoxy resins, cellulose resins, and melamine resins. In particular, a butyral resin is preferred. This mixed solution is applied onto the undercoat layer and dried to obtain a charge generation layer. The dispersed particle diameter of the charge generation material in the charge generation layer is preferably 0.5 μm or less, more preferably 0.3 μm or less. A range of 0.01 to 0.2 μm is more preferable. The thickness of the charge generation layer is preferably from 0.01 to 2 μm, more preferably from 0.05 to 0.3 μm.

  The charge transport layer is formed of a suitable charge transport material, for example, a heterocyclic compound such as poly-N-vinylcarbazole or polystyrylanthracene, or a polymer compound having a condensed polycyclic aromatic group, or a complex such as pyrazoline, imidazole, oxazole, triazole or carbazole. Suitable binder resins such as ring compounds, triarylalkane derivatives such as triphenylmethane, triarylamine derivatives such as triphenylamine, phenylenediamine derivatives, N-phenylcarbazole derivatives, stilbene derivatives, hydrazone derivatives, etc. A solution dispersed / dissolved in a solvent (which can be selected from the aforementioned resin for charge generation layer) can be applied by the above-mentioned known method and dried. In this case, the ratio of the charge transport material to the binder resin is such that the mass of the charge transport material is preferably 20 to 100, more preferably 30 to 100 when the total mass of both is 100. If the amount of the charge transport material is smaller than that, the charge transport ability is lowered, and problems such as a decrease in sensitivity and an increase in residual potential occur. In this case, the thickness of the charge transport layer is preferably adjusted in the range of 5 to 50 μm, more preferably 8 to 36 μm.

  Furthermore, a surface protective layer may be formed on the charge transport layer.

  The surface protective layer may be a single resin, or a charge transport material as described above or a conductive material such as conductive powder may be added for the purpose of reducing the residual potential. Examples of the conductive powder include metal powders such as aluminum, copper, nickel and silver, flaky metal powders and short metal fibers, conductive metal oxides such as antimony oxide, indium oxide and tin oxide, polypyrrole and polyaniline. And polymer conductive agents such as polymer electrolytes, carbon black, carbon fiber, graphite powder, organic and inorganic electrolytes, or conductive powders whose surfaces are coated with these conductive substances.

  The charging means of the present invention will be described.

  A charging member contacts the outer peripheral surface of the electrophotographic photosensitive member, and the electrophotographic photosensitive member is charged to a predetermined positive or negative voltage by the charging member. A positive or negative DC voltage is applied to the charging member. The DC voltage applied to the charging member is preferably 1000 to 2000V. A pulsating voltage may be applied to the charging member by superimposing an AC voltage in addition to the DC voltage. In this case, the DC voltage is preferably 400 to 1000 V, and the AC voltage to be superimposed needs to have a peak-to-peak potential difference that is at least twice the DC voltage. The frequency of the AC voltage is preferably 300 to 2500 Hz.

  The charging member may be rotated in the same direction as that of the photosensitive member or in the opposite direction, or may be slid on the outer peripheral surface of the photosensitive member without being rotated.

  An example of the electrophotographic process of the present invention will be described.

  FIG. 6 shows a schematic configuration example of an electrophotographic apparatus having a process cartridge having the electrophotographic photosensitive member of the present invention. In the figure, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotationally driven in the direction of an arrow at a predetermined peripheral speed. In the rotating process, the photoreceptor 1 is uniformly charged with a positive or negative predetermined potential on its peripheral surface by the contact charging unit 3, and then an image from an image exposure unit (not shown) such as slit exposure or laser beam scanning exposure. Exposure 4 is received. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photoreceptor 1. The formed electrostatic latent image is then developed with toner by the developing unit 5, and the developed toner developed image is rotated between the photosensitive member 1 and the transfer unit 6 from a sheet feeding unit (not shown). The image is sequentially transferred by the transfer means 6 to the transfer material P that is synchronously taken out and fed. The transfer material P that has received the image transfer is separated from the surface of the photosensitive member, introduced into the image fixing means 8, and subjected to image fixing, thereby being printed out as a copy (copy). After the image transfer, the photosensitive member 1 is subjected to removal of residual toner after cleaning by a cleaning unit 9 as necessary, and is subjected to static elimination processing by a neutralizing unit (not shown) such as pre-exposure as necessary, and then repeatedly used for image formation. Is done. In the present invention, a plurality of components such as the electrophotographic photosensitive member 1, the primary charging unit 3, the developing unit 5 and the cleaning unit 7 described above are integrally coupled as a process cartridge. The electrophotographic apparatus main body such as a copying machine or a laser beam printer may be detachable. For example, at least one of the primary charging unit 3, the developing unit 5, and the cleaning unit 7 is integrally supported together with the photoreceptor 1 to form a cartridge, and is attached to and detached from the apparatus main body using guide means such as a rail of the apparatus main body in FIG. A flexible process cartridge can be obtained. Further, when the electrophotographic apparatus is a copying machine or a printer, the image exposure 4 is a reflected light or transmitted light from a document, or a document is read by a sensor and converted into a signal, and a laser beam scanning performed according to this signal is performed. Light emitted by driving the LED array and driving the liquid crystal shutter array.

  As the developing means 5, jumping development, two-component contact development, one-component contact development, or the like is used.

  The electrophotographic photosensitive member of the present invention can be used not only in electrophotographic copying machines but also widely in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

  A determination method for determining whether or not the electrophotographic photosensitive member satisfies the above definition of the present invention (hereinafter also referred to as “determination method of the present invention”) will be described.

  The determination method of the present invention is performed in a normal temperature and normal humidity (23 ° C., 50% RH) environment.

  In FIG. 1, an example of schematic structure of the determination apparatus for enforcing the determination method of this invention is shown.

  In FIG. 1, 101 is an electrophotographic photosensitive member to be determined, 103 is a charging roller of a charging unit, 104 is an exposure apparatus including a xenon lamp, a monochromator, and an ND filter, and 104L is light (exposure light). 105 is an electrometer (potential probe) for measuring (reading) the surface potential of the electrophotographic photosensitive member. The electrophotographic photosensitive member 101 is rotationally driven in the arrow direction. FIG. 1 illustrates an electrophotographic photosensitive member having a diameter of 60 mm.

  In the determination method of the present invention, the rotation speed of the electrophotographic photosensitive member is set to a speed at which the moving speed of the surface of the electrophotographic photosensitive member becomes 30π [mm / s] (94.25 [mm / s]). .

  The charging position by the charging roller 103, the position where the light 104L is irradiated, that is, the exposure position and the potential measuring position by the electrometer 105 are 0.25 seconds between charging and light irradiation and between the light irradiation and the potential measurement. Is set to be 0.25 seconds.

In FIG. 1, since the electrophotographic photosensitive member 101 has a diameter of 60 mm,
{(30π × 0.25) / 60π} × 360 ° = 45 °
Accordingly, the angle formed between the charging position, the electrophotographic photosensitive member center, and the exposure position, and the angle formed between the exposure position, the electrophotographic photosensitive member center, and the potential measurement position are 45 ° as shown in FIG.

  FIG. 2 shows another example of a schematic configuration of a determination apparatus for carrying out the determination method of the present invention. Reference numeral 101 'denotes an electrophotographic photosensitive member to be determined, and other reference numerals are the same as those in FIG. FIG. 2 illustrates an electrophotographic photosensitive member having a diameter of 30 mm. Hereinafter, the determination method of the present invention will be described in more detail.

FIG. 3 is a diagram for explaining the “V _A ”, and FIG. 4 is a diagram for explaining the “V _B ”. In FIG. 3 to 4, C1 is charged in the charging condition _{C 1,} C2 are charged in the charging condition _{C 2,} E1 is light irradiation amount _{E 1,} D represents a potential measurement.

  In the determination method of the present invention, charging the electrophotographic photosensitive member 5 times while charging the surface of the electrophotographic photosensitive member (hereinafter also referred to as “five rotation charging”) This is to eliminate them even if they remain.

Hereinafter, the charging conditions C ₁ and C ₂ and the light amount E ₁ will be described. These charging conditions and light quantity are determined before determining whether or not the electrophotographic photosensitive member satisfies the above-mentioned regulations of the present invention.

・ Charging condition C ₁
The DC voltage value of the voltage applied to the charging roller is adjusted so that the surface potential of the electrophotographic photosensitive member becomes −600 [V] as a result of charging the surface of the electrophotographic photosensitive member to be judged five times. .

・ Light intensity E ₁
The amount of light is adjusted by the ND filter so that the surface potential (−600 [V]) of the electrophotographic photosensitive member to be determined that has been charged five times by the charging condition C ₁ is attenuated to −150 [V].

· Charging condition _{C 2}
The value of the DC voltage among the voltages applied to the charging roller is adjusted so that the surface potential of the electrophotographic photosensitive member becomes −150 [V] as a result of charging the surface of the electrophotographic photosensitive member to be judged five times. .

  Note that “charging” and “light irradiation” in the determination method of the present invention are performed on the entire surface of the maximum image area on the surface of the electrophotographic photosensitive member.

As described above, V _A and V _{B of the} electrophotographic photosensitive member are derived.

Further, among the electrophotographic photoreceptors satisfying the above-mentioned formula (I) of the present invention, V _X , V _AX and V _BX defined as described later, and the thickness d [μm] of the hole transport layer are defined. And an electrophotographic photoreceptor in which m in the following approximate formula (II) consisting of a constant m and a constant n is in the range of 1 × 10 ⁻⁴ to 2 × 10 ^{−3 in} the range of −200 ≦ VX ≦ −120. preferable.

・Ｖ_ＸおよびＶ_ＡＸ
帯電条件Ｃ_１に設定された帯電手段により電子写真感光体の表面を帯電しながら電子写真感光体を５回転させることによって電子写真感光体の表面電位を−６００［Ｖ］にし、次いで、表面電位が−６００［Ｖ］になった電子写真感光体の表面に光を照射することによって電子写真感光体の表面電位をＶ_Ｘ［Ｖ］にし、表面電位がＶ_Ｘ［Ｖ］になった電子写真感光体の表面を帯電条件Ｃ_１に設定された帯電手段により帯電した後の電子写真感光体の表面電位をＶ_ＡＸ［Ｖ］とする。

・ V _X and V _AX
The surface potential of the electrophotographic photosensitive member by 5 rotating the electrophotographic photosensitive member while charging the surface of the electrophotographic photosensitive member by a charging means which is set in charging condition C ₁ to -600 [V], then the surface potential The surface potential of the electrophotographic photosensitive member is set to V _X [V] by irradiating light on the surface of the electrophotographic photosensitive member having a value of −600 [V], and the electrophotographic photosensitive member is set to V _X [V]. Let V _AX [V] be the surface potential of the electrophotographic photosensitive member after the surface of the photosensitive member is charged by the charging means set to the charging condition C ₁ .

・ V _X and V _BX
The surface potential of the electrophotographic photosensitive member is set to V _X [V] by rotating the electrophotographic photosensitive member 5 times while charging the surface of the electrophotographic photosensitive member by the charging means set to the predetermined charging condition C _2X , The surface potential of the electrophotographic photosensitive member after charging the surface of the electrophotographic photosensitive member having the surface potential of V _X [V] by charging means set under the same condition as the charging condition C ₁ is _expressed as V _BX [V]. To do.

Incidentally, the same value is a _{"V X"} in _{"V X"} and the _{"V X} and _{V BX"} in the above _{"V X} and _{V AX".}

Hereinafter, the above charging condition _C2X will be described. This charging condition is also determined before determining whether or not the electrophotographic photosensitive member satisfies the above definition of the present invention.

・ Charging condition _C2X
The DC voltage value of the voltage applied to the charging roller is adjusted so that the surface potential of the electrophotographic photosensitive member is V _X [V] as a result of charging the surface of the electrophotographic photosensitive member to be judged five times. Other than the above, the charging conditions are the same as C ₁ and C ₂ .

The charging roller of this evaluation has a resistance of 5 per 1 cm in length in any environment of low temperature and low humidity (15 ° C., 10%), normal temperature and normal humidity (23 ° C., 50%), and high temperature and high humidity. The thing which is * 10 < ³ > -5 * 10 < ⁴ > (omega | ohm) is used. The resistance was measured by pressing a charging roller left in each environment for 24 hours against a metal drum connected to the ground with a total pressure of 15.69 N on both sides and a pressure of 7.8 N on one side. The drum was rotated at a speed of 100 mm / s (the charging roller was driven to rotate), a voltage of -500 V was applied to the core of the charging roller from a high voltage power source connected to the ground, and the measured resistance value and measurement It can be calculated from the nip width at the time and the thickness of the charging roller.

  The high voltage power supply of this evaluation sets AC Vpp to 1800 V and frequency 870 Hz.

  Image exposure uses a xenon lamp, a monochromator, and monochromatic light of 780 nm which is dispersed, and the setting of the light quantity is adjusted by an ND filter.

  As a result of intensive studies, we investigated the left side of the following formula (I) in an electrophotographic photosensitive member used for an electrophotographic apparatus having a charging means for charging by contacting a charging member.

装置によって大きく異なってしまうが、感光体中の電荷のトラップが原因で生じる影響を推測することが可能となり、式（Ｉ）を満足する感光体は、
特に、プロセススピードが速く、低温低湿下でも、初期数十枚の明部電位の変動が改善されることを見出した。

Although it varies greatly depending on the apparatus, it is possible to estimate the influence caused by charge trapping in the photoconductor, and the photoconductor satisfying the formula (I) is:
In particular, it has been found that the fluctuations in the initial portion of the bright part potential can be improved even when the process speed is high and the temperature and humidity are low.

The larger the image exposure amount, the smaller the absolute value of the surface potential after image exposure, that is, the larger the image exposure amount, the smaller the absolute value of V _X. In the part exposed to image exposure, when holes are injected into the CTL and electrons escape to the substrate, electrons remain in the CGL, in the substrate and at the CGL / substrate interface, and the barrier property against the injection of holes from the substrate in the next charging However, if m is 1 × 10 ⁻⁴ or more and 2 × 10 ⁻³ or less, the amount of electrons remaining in the CGL, the underlayer, and the CGL / underlayer interface is saturated by image exposure, and the image It is considered that the amount of remaining electrons does not increase much even if the exposure amount is increased. The reason why the bright part potential fluctuates is not clear, but it is presumed that there is some relationship between the fact that the amount of remaining electrons does not increase even if the image exposure amount is increased and the fluctuation of the bright part potential.

FIG. 5 shows an example of a graph showing the relationship between V _X and (| −600−V _AX | − | −600−V _BX |) / d.

May slope m fluctuations in 2 × 10 ^-3 larger than the initial dozens of light portion potential is seen, the slope m is 1 × 10 is less than ^-4 initial also initial dozens of after durability There was a case where the fluctuation of the bright part potential was observed.

  Hereinafter, the present invention will be described with reference to examples. In the examples, “parts” represents parts by mass.

Example 1
An aluminum cylinder having a diameter of 30 mm was subjected to a honing treatment and subjected to ultrasonic water cleaning to obtain a conductive support.

  Next, 5 parts of N-methoxymethylated 6 nylon was dissolved in 95 parts of methanol to prepare an undercoat layer coating material. This paint was applied on the conductive support by a dip coating method and dried at 100 ° C. for 20 minutes to form an undercoat layer having a thickness of 0.5 μm.

  Next, as a coating for the charge generation layer, 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° with a Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction and 10 parts of crystalline hydroxygallium phthalocyanine having a strong peak at 28.3 °, 0.1 part of the following structural formula (2) and 5 parts of polyvinyl butyral resin (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) Is added to 250 parts of cyclohexanone and dispersed in a sand mill using glass beads having a diameter of 1 mm for 4 hours. Then, 3 parts of the following structural formula (3) is added and dissolved as an electron transporting compound, and 250 parts of ethyl acetate is added thereto. Added and diluted. This was coated on the undercoat layer and then dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.16 μm.

次いで下記構造式（４）のスチリル化合物を１０部

Next, 10 parts of a styryl compound of the following structural formula (4)

及び下記構造式（５）の繰り返し単位を有するポリカーボネート樹脂１０部を

And 10 parts of a polycarbonate resin having a repeating unit of the following structural formula (5)

モノクロロベンゼン５０部及びジクロロメタン３０部の混合溶媒中に溶解し、電荷輸送層用塗布液を調製した。この塗布液を前記の電荷発生層上に浸漬コーティング法によって塗布し、１２０℃で１時間乾燥することによって、膜厚が３６μｍの電荷輸送層を形成した。

A charge transport layer coating solution was prepared by dissolving in a mixed solvent of 50 parts of monochlorobenzene and 30 parts of dichloromethane. This coating solution was applied onto the charge generation layer by dip coating and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 36 μm.

  The electrophotographic photoreceptor thus prepared was determined for (| A |-| B |) / d, m under normal temperature and normal humidity (23 ° C, 50%), and further under low temperature and low humidity (5 ° C, 20%). ) To evaluate the fluctuation of the light portion potential.

  The measurement of the bright part potential fluctuation under low temperature and low humidity will be described.

  Evaluation was made by changing the Canon digital copying machine GP405 (the photoconductor was rotated at an arbitrary speed so that only primary charging, image exposure and cleaning could be performed. The primary charging AC was set to a voltage of 2000 VP-P, and the frequency was 2000 Hz constant, process speed was changed to 180 mm / sec to 290 mm / sec, and the sensor was turned off so that it was not necessary to pass through the transfer paper. The fixing device is turned off so as not to warm up. The image exposure light amount can be adjusted to an arbitrary light amount), and the photoconductor of the present invention is attached to this, and the rotation speed of the photoconductor is low temperature and low humidity (5 ° C., 20%). Is set to an arbitrary process speed, and the primary charging DC is set so that the dark portion potential at that time is −600 V and the light portion potential is −150 V. Adjust the pressure and the image exposure amount, the A4 100 sheets continuously performs solid black copy, comparing the light portion potential and light portion potential of the 100th first sheet. These results are shown in Table 8.

(Example 2)
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the thickness of the charge transport layer was 30 μm. The results are shown in Table 8.

  (Example 3) An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 2 except that the electron transporting compound was added only to the intermediate layer. The results are shown in Table 8.

  Example 4 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 2 except that the electron transporting compound was added to both the charge generation layer and the intermediate layer. The results are shown in Table 8.

  Example 5 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 2 except that the compound (6) having the following structural formula was added as the electron transporting compound. The results are shown in Table 8.

（実施例６） 電子搬送性化合物として、下記構造式の化合物（７）を添加した以外は実施例２と同様に電子写真感光体を作製し評価した。結果を表８に示す。

Example 6 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 2 except that the compound (7) having the following structural formula was added as the electron transporting compound. The results are shown in Table 8.

（実施例７） 電子搬送性化合物として、下記構造式の化合物（８）を添加した以外は実施例２と同様に電子写真感光体を作製し評価した。結果を表８に示す。

Example 7 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 2 except that the compound (8) having the following structural formula was added as the electron transporting compound. The results are shown in Table 8.

（比較例１） 電荷輸送層の膜厚を２４μｍとした以外は実施例１と同様に電子写真感光体を作製し評価した。結果を表８に示す。

Comparative Example 1 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the thickness of the charge transport layer was 24 μm. The results are shown in Table 8.

  (Comparative Example 2) An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the resin of the charge transport layer used the following structural formula (9). The results are shown in Table 8.

（比較例３） 電荷発生層の膜厚を０．１０μｍとした以外は実施例１と同様に電子写真感光体を作製し評価した。結果を表８に示す。

Comparative Example 3 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the thickness of the charge generation layer was 0.10 μm. The results are shown in Table 8.

Comparative Example 4 An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the thickness of the charge generation layer was 0.26 μm. The results are shown in Table 8.
Table 8

  The present invention has the above-described effects, and the effects can be expected to be naturally exhibited in a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

It is a figure which shows an example of schematic structure of the determination apparatus for enforcing the determination method of this invention. It is a figure which shows another example of schematic structure of the determination apparatus for enforcing the determination method of this invention. It is a figure for demonstrating "VA". It is a figure for demonstrating "VB." It is a figure which shows an example of the graph which shows the relationship between VX and (| -600-VAX | --- 600-VBX |) / d. 1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention. It is an image pattern for evaluation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Primary charging means 4 Image exposure 5 Developing means 6 Transfer means 7 Cleaning means 8 Image fixing means 101 Electrophotographic photoreceptor 103 Charging roller 104 Exposure device 105 Electrometer

Claims (6)

An electrophotographic photosensitive member for use in an electrophotographic apparatus having a charging means for bringing a charging member into contact with the electrophotographic photosensitive member for charging and having a process speed of 220 mm / sec or more, comprising the conductive support and the conductive support In an electrophotographic photosensitive member having a charge generation layer containing a charge generation material provided on the body, and a hole transport layer containing a hole transport material provided on the charge generation layer,
The surface potential of the electrophotographic photosensitive member to -600 [V] by 5 rotating the electrophotographic photosensitive member while charging the surface of the electrophotographic photosensitive member by the set charging means to a predetermined charging condition C ₁ , then the surface potential of the electrophotographic photosensitive member to -150 [V] by the surface potential to irradiate a predetermined quantity of light E ₁ on the surface of the electrophotographic photosensitive member becomes -600 [V], The surface potential of the electrophotographic photosensitive member after the surface of the electrophotographic photosensitive member having a surface potential of −150 [V] is charged by the charging means set in the charging condition C ₁ is defined as V _A [V]. ,
The surface potential of the electrophotographic photosensitive member to -150 [V] by 5 rotating the electrophotographic photosensitive member while charging the surface of the electrophotographic photosensitive member by the set charging means to a predetermined charging condition C ₂ , then the surface potential of the electrophotographic photosensitive member after charged by the charging means the surface potential is set to the surface of the electrophotographic photosensitive member becomes -150 [V] to the charging condition C ₁ under the same conditions V _B [V]
When the film thickness of the hole transport layer is d [μm], the V _A , V _B and d are represented by the following formula (I)

An electrophotographic photoreceptor characterized by satisfying Wherein the surface potential of the electrophotographic photosensitive member by rotating 5 the electrophotographic photoreceptor while charging the surface of the electrophotographic photosensitive member by the charging condition set charging means C ₁ to -600 [V], then, the surface potential of the electrophotographic photosensitive member to V _{X [V]} by applying light to the surface of the electrophotographic photosensitive member surface potential becomes -600 [V], the surface potential V _{X [V} The surface potential of the electrophotographic photosensitive member after charging the surface of the electrophotographic photosensitive member with the charging condition C ₁ set to V _AX [V],
The surface potential of the electrophotographic photosensitive member is set to V _X [V] by rotating the electrophotographic photosensitive member five times while charging the surface of the electrophotographic photosensitive member by charging means set to a predetermined charging condition C _2X. Then, the surface potential of the electrophotographic photosensitive member after the surface of the electrophotographic photosensitive member having a surface potential of V _X [V] is charged by the charging means set under the same condition as the charging condition C ₁ is obtained. When V _BX [V],
In the range of −200 ≦ V _X ≦ −120, the following approximate formula (II) consisting of the above-mentioned V _X , V _AX , V _BX and the thickness d [μm] of the hole transport layer and the constant m and the constant n

The electrophotographic photosensitive member according to claim 1, wherein m is in the range of 1 × 10 ⁻⁴ to 2 × 10 ⁻³ .   The electrophotographic photosensitive member according to claim 1, wherein the charge generation layer and / or the intermediate layer contains an electron transporting compound. The electron transporting compound is represented by the following general formulas (1) to (4).

(In the formula, X _{1 and} X ₂ each independently represent a hydrogen atom, a halogen group, a nitro group, an optionally substituted alkoxy group or an optionally substituted alkyl group, and R ₁ and R 2 ₂ are each independently an alkyl group which may be interrupted by an ether group, an alkenyl group which may be interrupted by an ether group, a heterocyclic group, an alkyl group, an alkenyl group, a nitro group, a halogen group or a halogen-substituted alkyl group. An aryl group which may have an alkyl group, an alkenyl group, a nitro group, a halogen group or a halogen-substituted alkyl group which may have an aralkyl group.

(In the formula, Z ₁ and Z ₂ each independently represent oxygen, C (CN) ₂ group, or N phenyl group which may have a substituent, and X ₃ and X ₄ each independently represent a hydrogen atom or a halogen group. , A nitro group, an alkoxy group which may have a substituent or an alkyl group which may have a substituent.

(In the formula, Z ₃ and Z ₄ each independently represent oxygen, C (CN) ₂ group, or optionally substituted N phenyl group, and X ₅ and X ₆ each independently represent a hydrogen atom or a halogen group. , A nitro group, an alkoxy group which may have a substituent or an alkyl group which may have a substituent.

(In the formula, Z ₅ and Z ₆ each independently represent oxygen, C (CN) ₂ group, or optionally substituted N-phenyl group, and X ₇ and X ₈ each independently represent a hydrogen atom or a halogen group. , A nitro group, an alkoxy group which may have a substituent or an alkyl group which may have a substituent.
The electrophotographic photosensitive member according to claim 3, which is a compound represented by the formula:   A process cartridge having the electrophotographic photosensitive member according to claim 1.   An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1.

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