JP2008107618A - Method for manufacturing coating liquid for electrophotographic photoreceptor, and electrophotographic photoreceptor using the method, and electrophotographic device and process cartridge for electrophotographic device using the photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a coating liquid for an electrophotographic photoreceptor, the liquid showing high productivity and preferable liquid stability, and to provide an electrophotographic device and a process cartridge for an electrophotographic device using an electrophotographic photoreceptor that shows preferable sensitivity and potential stability and gives an image of high quality having no image defect. <P>SOLUTION: The method for manufacturing a coating liquid for an electrophotographic photoreceptor prepared by dispersing an azo pigment in at least a solvent is characterized in that: the coating liquid is dispersed by a ball mill; and the number of revolutions (R/rpm) of the ball mill is calculated by formula (1):R=V*60/(D*π), wherein V is in a range of 0.7≤V≤1.2, R represents the number of revolutions, and D represents the diameter (m) of a pot of the ball mill. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an electrophotographic photoreceptor coating liquid, an electrophotographic photoreceptor using the same, an electrophotographic apparatus using the same, and a process cartridge for an electrophotographic apparatus. More particularly, the present invention relates to a method for producing an electrophotographic photosensitive member coating solution having high productivity and excellent liquid stability, and has a high image defect-free height produced using such a production method. The present invention relates to an electrophotographic photosensitive member that gives an image of high image quality, an electrophotographic apparatus using the electrophotographic photosensitive member, and a process cartridge for an electrophotographic apparatus.

Conventionally, inorganic materials such as Se, CdS, and ZnO have been used as photoconductive materials for electrophotographic photoreceptors. However, in recent years, organic light has been used because of problems such as photosensitivity, thermal stability, and toxicity. Development of electrophotographic photoreceptors using conductive materials has been actively conducted, and electrophotographic photoreceptors having a photosensitive layer containing a charge generation material and a charge transport material have already been put into practical use. .
In general, a photosensitive layer of an electrophotographic photoreceptor using an organic photoconductive material is composed of at least a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. At least the charge generating material is dispersed in an appropriate solvent using a ball mill, attritor, sand mill, ultrasonic wave, etc. to create a coating liquid, which is formed by applying it on a conductive support or intermediate layer and drying it. Is done.

When an azo pigment is used as a charge generation material, the azo pigment itself has a high cohesiveness and a high hardness as a solid material. Therefore, it is necessary to apply dry pulverization in advance or to increase the dispersion time. Often created. However, either means is not preferable in the manufacturing process of the coating liquid because it takes time and labor due to an increase in steps and man-hours.
In addition, azo pigments are considered to express the function of charge generation by taking a state of agglomeration of a single molecule, so the storage stability after preparation of the coating liquid is small, and charge generation occurs over time. As the properties change, the liquid properties of the coating liquid change and aggregates are formed, or the viscosity rises, the coating film quality of the coated electrophotographic photoreceptor deteriorates and the worst In some cases, it had to be discarded.
Various proposals have been made for the dispersion method for the above problems, but the present situation is that a satisfactory coating property required for the photoreceptor coating solution has not been obtained.

As a dispersion method, for example, dry pulverization is performed first, followed by wet pulverization (Patent Document 1: Japanese Patent Laid-Open No. 1-176433, Patent Document 2: Japanese Patent Laid-Open No. 1-176434, and Patent Document 3: Japanese Patent Laid-Open No. Hei 9 (1998)). 8-41368) and a method of dispersing while performing ultrasonic irradiation (Patent Document 4: Japanese Patent Laid-Open No. 2001-265027) is disclosed.
However, in this method, a good coating liquid can be obtained as the initial dispersion state, but the stability over time is poor, and the viscosity of the coating liquid over time, the occurrence of aggregates on the coated photoconductor, etc. Occurs.

The ball mill does not require premixing of pigment, resin and solvent, has less solvent loss due to evaporation, has a simple mechanism, does not require management and monitoring, and has low labor costs. Often used in the production of coating fluids.
Non-patent document 1 also describes optimum conditions for general ball mill dispersion. The media volume is optimally half the volume of the mill.
However, under the above conditions, there is a problem that the time required for dispersion is long and productivity is poor.

Further, a method using a medium using crystalline glass or alumina as a dispersion medium (Patent Document 5: Japanese Patent Laid-Open No. 4-223272, Patent Document 6: Japanese Patent Laid-Open No. 8-123045) is also disclosed.
However, in this method, the media wear powder is mixed with the coating liquid, and the electrophotographic photosensitive member produced by this method has a problem that an image defect occurs and a low-quality image is formed.

Further, there is a method in which an organic pigment is dispersed in a solvent together with balls or beads having two or more different diameters (Patent Document 7: Japanese Patent No. 3346416, Patent Document 8: Japanese Patent Laid-Open No. 2001-265027). It is disclosed.
However, in this method, since finely divided media are used and various types of media are used, there arises a problem that handling at the manufacturing site becomes difficult.

Also disclosed is a method using a medium having a density (D: g / cm ² ) and a diameter (R: mm) represented by the following formula (a) (Patent Document 9: JP 2002-341564 A). Yes.

しかし、後に説明するように、メディアはＰＳＺボールがよく、ＰＳＺボールはＤ＝６であるため、当該方法ではメディアの直径は１０ｍｍ以上がよいということになる。したがって、当該方法では生産性、液安定性の点で不十分である。

However, as will be described later, the medium is preferably a PSZ ball, and the PSZ ball has D = 6. Therefore, in this method, the diameter of the medium should be 10 mm or more. Therefore, this method is insufficient in terms of productivity and liquid stability.

Also disclosed is a method (Patent Document 10: Japanese Patent Application Laid-Open No. 2002-107974) using a dispersion medium having a mass of 1.5 times or more of the dispersion solution.
However, as will be described later, the media is preferably PSZ balls, and when PSZ balls are used in this method, the amount of media is too small, the dispersion efficiency is poor, and the productivity is poor.

A method of pulverizing an azo pigment with a ball mill using 1,4-dioxane as a processing solvent is also disclosed (Patent Document 11: JP-A-7-152188). However, dioxane cannot be carried out because of its toxicity.

Japanese Patent Laid-Open No. 1-176433 Japanese Patent Laid-Open No. 1-176434 JP-A-8-41368 JP 2001-265027 A JP-A-4-223272 JP-A-8-123045 Japanese Patent No. 3346416 JP 2001-265027 A JP 2002-341564 A JP 2002-107974 A JP-A-7-152188 Paint flow and pigment dispersion by TEMPLE.C.PATTON Kyoritsu Publishing Co., Ltd.

  Accordingly, in view of the above prior art, the present invention is to provide a method for producing a coating solution for an electrophotographic photosensitive member having high productivity and good liquid stability, and speeding up the electrophotographic apparatus. The present invention provides a method for producing a coating solution for an electrophotographic photosensitive member that provides an electrophotographic photosensitive member that contributes to the electrophotographic photosensitive member, and provides an electrophotographic photosensitive member having good sensitivity and potential stability. It is to provide a method for producing a working liquid, to provide an electrophotographic photosensitive member that gives a high-quality image without image defects produced using the electrophotographic photosensitive member coating liquid of the present invention, and It is an object to provide an electrophotographic apparatus using an electrophotographic photosensitive member that uses an electrophotographic photosensitive member coating solution of the present invention to give a high-quality image free from image defects, and the electrophotographic photosensitive member of the present invention. No image defects produced using coating liquid It is to provide an electrophotographic apparatus for a process cartridge using an electrophotographic photosensitive member which gives images of quality.

  The above-described problem is (1) in the method for producing a coating solution for an electrophotographic photosensitive member obtained by dispersing an azo pigment in at least a solvent, wherein the coating solution is dispersed by a ball mill, and the rotational speed of the ball mill is Is the rotation speed (R / rpm) calculated by the following formula (1), and V in the formula (1) is in the range of 0.7 ≦ V ≦ 1.2. Production method;

R：回転数（ｒｐｍ）
D：ボールミルのポットの直径（ｍ）」、
（２）「使用されるメディアの径が２ｍｍ以上５ｍｍ以下であることを特徴とする前記第（１）項に記載の電子写真感光体の製造方法」、
（３）「使用されるメディアの量がボールミル容積の２５％以上３５％以下であることを特徴とする前記第（１）項または第（２）項に記載の電子写真感光体の製造方法」、
（４）「ボールミルのポットの直径が０．０２ｍ以上０．１５ｍ以下であることを特徴とする前記第（１）項乃至第（３）項の何れかに記載の電子写真感光体の製造方法」、
（５）「前記メディアがＰＳＺボールであることを特徴とする前記第（１）項乃至第（４）項のいずれかに記載の電子写真感光体の製造方法」、
（６）「前記アゾ顔料が下記一般式（I）：

R: Number of revolutions (rpm)
D: Ball mill pot diameter (m) ",
(2) “The method for producing an electrophotographic photosensitive member according to (1) above, wherein a diameter of a medium to be used is 2 mm or more and 5 mm or less”,
(3) “The method for producing an electrophotographic photosensitive member according to (1) or (2) above, wherein the amount of media used is 25% or more and 35% or less of the ball mill volume” ,
(4) The method for producing an electrophotographic photosensitive member according to any one of (1) to (3) above, wherein the diameter of the ball mill pot is 0.02 m or more and 0.15 m or less. "
(5) "The method for producing an electrophotographic photosensitive member according to any one of (1) to (4) above, wherein the medium is a PSZ ball";
(6) “The azo pigment is represented by the following general formula (I):

（式中、Ａは、炭素原子でアゾ基の窒素原子に結合している２価の残基を示し；Ｃｐ1及びＣｐ2は互いに構造の異なるカプラー残基を示す。）で表わされる非対称ジスアゾ顔料であることを特徴とする前記第（１）項乃至第（５）項の何れかに記載の電子写真感光体の製造方法」、
（７）「前記一般（I）で表される非対称アゾ顔料が下記一般式（II）で表わされる化合物であることを特徴とする前記第（６）項に記載の電子写真感光体の製造方法；

(Wherein A represents a divalent residue bonded to the nitrogen atom of the azo group by a carbon atom; Cp1 and Cp2 represent coupler residues having different structures from each other), and an asymmetric disazo pigment represented by The method for producing an electrophotographic photosensitive member according to any one of (1) to (5), wherein:
(7) The process for producing an electrophotographic photosensitive member as described in (6) above, wherein the asymmetric azo pigment represented by the general formula (I) is a compound represented by the following general formula (II): ;

（式中、Ｃｐ1及びＣｐ3は互いに構造の異なるカプラー残基を示す。）」、
（８）「前記塗工液の分散媒にケトン系溶媒を含有することを特徴とする前記第（６）項または第（７）項に記載の電子写真感光体の製造方法」により達成される。
また、上記課題は、本発明の（９）「前記第（１）項乃至第（８）項の何れかに記載の電子写真感光体の製造方法により得られたことを特徴とする電子写真感光体」により達成される。
また、上記課題は、本発明の（１０）「少なくとも帯電手段、画像露光手段、現像手段、転写手段、除電手段及び電子写真感光体を具備してなる電子写真装置であって、該電子写真感光体が、前記第（９）項に記載の電子写真感光体であることを特徴とする電子写真装置」により達成される。
また、上記課題は、本発明の（１１）「少なくとも電子写真感光体を具備してなる電子写真装置用プロセスカートリッジであって、該電子写真感光体が、前記第（９）項に記載の電子写真感光体であることを特徴とする電子写真装置用プロセスカートリッジ」により達成される。

(Wherein Cp1 and Cp3 represent coupler residues having different structures from each other) "
(8) “A method for producing an electrophotographic photosensitive member according to (6) or (7) above, wherein the dispersion medium of the coating liquid contains a ketone solvent”. .
Further, the above object is obtained by an electrophotographic photosensitive member manufacturing method according to any one of (9) and “(1) to (8)” of the present invention. Achieved by "body".
Another object of the present invention is to provide an electrophotographic apparatus comprising (10) “at least a charging unit, an image exposing unit, a developing unit, a transferring unit, a neutralizing unit, and an electrophotographic photosensitive member. This is achieved by an electrophotographic apparatus characterized in that the body is the electrophotographic photosensitive member according to item (9).
Further, the above-mentioned problem is (11) “a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is an electron according to (9) above”. This is achieved by a “process cartridge for an electrophotographic apparatus, which is a photographic photosensitive member”.

As is clear from the following detailed and specific description, according to the above (1) of the present invention, since the rotation speed of the ball mill is within a predetermined range, it is possible to provide a coating liquid having excellent productivity and liquid stability,
According to the above (2), since the media diameter is in a predetermined range, it is possible to provide a coating liquid having excellent productivity and liquid stability.
According to the above (3), since the amount of media is within a predetermined range, it is possible to provide a coating liquid with excellent productivity and liquid stability.
According to the above (4), since the pot diameter is in a predetermined range, it is possible to provide a coating liquid having excellent productivity and liquid stability.
According to the above (5), since the material of the medium is PSZ, it is possible to provide a coating liquid with excellent productivity and liquid stability, and an electrophotographic photosensitive member produced using the coating liquid does not cause image defects. ,
According to the above (6), since an asymmetric bisazo pigment is used, it contributes to speeding up of the electrophotographic apparatus,
According to the above (7), since the central skeleton of the asymmetric bisazo pigment is represented by the general formula (II), the electrophotographic photoreceptor produced using the coating solution exhibits stable electrical characteristics,
According to the above (8), since a ketone solvent is used as the dispersion solvent, it is possible to provide a coating liquid with excellent productivity and liquid stability.
According to the above (9), since the coating liquid produced by the production method of the present invention is used, it is possible to provide an electrophotographic photosensitive member that gives a high-quality image without image defects,
According to the above (10), since the electrophotographic photosensitive member of the present invention is used, it is possible to provide an electrophotographic apparatus that gives a high-quality image without image defects,
According to the above (11), since the electrophotographic photosensitive member of the present invention is used, there can be provided an extremely excellent effect that a process cartridge for an electrophotographic apparatus that gives a high-quality image without image defects can be provided. It is.

The present invention is described in detail below.
FIG. 7 shows one configuration example of the ball mill dispersing apparatus. A ball mill dispersing device is composed of a cylindrical pot and a medium in it. A mill base of azo pigment, resin, solvent, etc. is placed in this pot, and the medium is moved by rotating the pot. The pigment is dispersed.
The number of rotations of the ball mill is preferably the number of rotations (R / rpm) calculated by the following formula (1).

R：回転数（ｒｐｍ）
D：ボールミル直径（ｍ）
０．７≦V≦１．２、なおVは０．７以上１．２以下が好ましい。さらに好ましくは０．８以上１．２以下で、さらに好ましくは０．９以上１．２以下である。
ボールミル分散装置では、顔料分散を行っているメディアやポット壁面に運動エネルギーを与えているのは、ポットの回転であり、ポットの回転数が分散効率に大きな影響を及ぼす。
回転数Rは大きいほど液安定性は向上し、分散時間も短くなる。Vが１．２より大きくなるとメディアが遠心力のためボールミルの内壁に沿ってポットにつれまわって回転してしまい分散効率が落ちる。

R: Number of revolutions (rpm)
D: Ball mill diameter (m)
0.7 ≦ V ≦ 1.2, and V is preferably 0.7 or more and 1.2 or less. More preferably, it is 0.8 or more and 1.2 or less, More preferably, it is 0.9 or more and 1.2 or less.
In the ball mill dispersing apparatus, it is the rotation of the pot that imparts kinetic energy to the media in which the pigment is dispersed and the wall surface of the pot, and the rotational speed of the pot has a great influence on the dispersion efficiency.
The larger the rotation speed R, the better the liquid stability and the shorter the dispersion time. When V is greater than 1.2, the media rotates due to centrifugal force along the inner wall of the ball mill, and the dispersion efficiency decreases.

Various commonly used shapes such as a spherical shape, a cylindrical shape, and a rugby ball shape can be applied as the shape of the media. Among them, the spherical shape is preferable because it is uniformly worn.
When a spherical medium is used, the media diameter is preferably 2 mm or more and 5 mm or less. Furthermore, 3 mm or more and 5 mm or less are preferable, and 3 mm or more and 4 mm or less are more preferable.
The smaller the media diameter, the better the liquid stability. However, if the media diameter is too small, the weight per ball becomes small and the dispersion force becomes weak, so the productivity is lowered.

The amount of media is preferably 25% or more and 35% or less with respect to the pot volume. More preferably, they are 26% or more and 34% or less, More preferably, they are 28% or more and 32% or less.
The amount of media here is an amount that does not include a gap between the media, and the ratio of the ball to the pot volume is obtained by the following equation.

メディアの量は多すぎても少なすぎても生産効率が落ち、上記範囲が生産性が一番良くなる。

If the amount of media is too much or too little, the production efficiency will drop, and the above range will give the best productivity.

Regarding the size of the pot, the inner diameter is preferably 0.02 m or more and 0.15 m or less. More preferably, it is 0.05 m or more and 0.15 m or less, More preferably, 0.09 m or more and 0.15 m or less is preferable.
The smaller the pot diameter, the better the liquid stability, but the productivity decreases. Therefore, the above range is preferable.

As the material of the media, PSZ is preferable.
Commonly used media materials include glass, alumina, and titania. However, these materials have the disadvantage that the media itself is worn and remains as an impurity in the coating liquid, resulting in image defects.
The amount of mill base in the pot is preferably 25% or more and 50% or less with respect to the volume of the pot.
Productivity decreases when the amount of mill base is less than 25% of the pot volume. Moreover, it becomes easy to receive the influence of the temperature rise by friction of media. On the other hand, even if it becomes 50% or more, the dispersion efficiency decreases.
The solid content of the coating liquid during dispersion is preferably 1% or more and 30% or less.
When the solid content is too high, the viscosity of the liquid is too high to be sufficiently dispersed, and when it is too low, it takes time until the liquid is sufficiently dispersed.

As the solvent used at the time of preparing the coating liquid, a ketone solvent is preferable.
In the case of alcohol solvents such as methanol, ethanol, and isopropanol, the pigment is not dispersed, and in the case of ester solvents such as ethyl cellosolve, ethyl acetate, and methyl acetate, the stability of the coating solution is not maintained, resulting in sensitivity fluctuations. Halogen solvents such as dichloromethane, dichloroethane, and monochlorobenzene have a problem with safety as a solvent.
The reason why the ketone solvent is excellent as a coating solution solvent is that the dispersibility of the asymmetric disazo pigment used in the present invention, the stability and storage stability of the coating solution are excellent, and further, vertical stripe unevenness and concentration unevenness during the production of a photoreceptor. This is because the occurrence of this is suppressed.
Specific examples of the ketone solvent include isophorone, cyclohexanone, methylcyclohexanone, acetophenone, acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, diisobutyl ketone and the like. Can be mentioned.
As the coating method of the coating solution, methods such as dip coating, spray coating, bead coating, nozzle coating, spinner coating, ring coating, and the like can be used.

  The electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor obtained by sequentially laminating at least a charge generation layer and a charge transport layer on a conductive support, and the charge generation layer is formed by the method of the present invention. It is formed using the produced electrophotographic photosensitive member coating liquid. Furthermore, the electrophotographic apparatus and the process cartridge for an electrophotographic apparatus according to the present invention include at least the electrophotographic photosensitive member according to the present invention.

  Hereinafter, the present invention will be described based on the configuration of the electrophotographic photosensitive member. FIG. 1 is a cross-sectional view showing a structural example of the electrophotographic photosensitive member of the present invention, in which a photosensitive layer (15) formed by applying a coating solution containing at least an azo pigment on a conductive support (11). The structure which laminated | stacked is taken. FIG. 2 is a cross-sectional view showing another structural example of the electrophotographic photosensitive member of the present invention, which is formed by applying a charge generation layer coating solution containing at least an azo pigment on the conductive support (11). The charge generation layer (17) and the charge transport layer (19) are stacked. FIG. 3 is a sectional view showing another structural example of the present invention, in which an intermediate layer (13) is provided between the conductive support (11) and the charge generation layer (17). FIG. 4 is a cross-sectional view showing still another structural example of the present invention, in which a protective layer (21) is provided on the charge transport layer (19).

1 to 4, as the conductive support (11), a substance exhibiting conductivity having a volume resistance of 10 ¹⁰ Ω · cm or less, such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, etc. A metal or metal oxide such as tin oxide or indium oxide coated with a film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate of aluminum, aluminum alloy, nickel, stainless steel or the like After forming a tube by a method such as extrusion or drawing, a tube that has been surface-treated by cutting, superfinishing, polishing, or the like can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can be used as the conductive support (11). In addition, as the conductive support (11) of the present invention, a conductive support dispersed on a suitable binder resin on the support can be used. Examples of the conductive powder include carbon-based materials such as carbon black and acetylene black, metal powders such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, or conductive titanium oxide, conductive tin oxide, and ITO. And metal oxide powders. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Thermoplastic, thermosetting resin or photo-curing resin such as melamine resin, urethane resin, phenol resin, alkyd resin and the like can be mentioned. Such a conductive layer can be provided by dispersing and applying these conductive powder and binder resin in a suitable solvent, for example, tetrahydrofuran, dichloromethane, 2-butanone, toluene or the like. Further, as the conductive support (11) of the present invention, the above conductive material is applied to a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. A material in which a conductive layer is provided by a heat-shrinkable tube containing a conductive powder can also be used favorably.

  As the charge generating substance, azo pigments such as monoazo pigments, bisazo pigments, asymmetric disazo pigments, trisazo pigments, tetraazo pigments, and the like can be used. Specifically, an azo pigment having a carbazole skeleton (described in JP-A-53-95033), an azo pigment having a triphenylamine skeleton (described in JP-A-53-132547), and a stilstilbene skeleton. Azo pigments (described in JP-A No. 53-138229), azo pigments having a dibenzothiophene skeleton (described in JP-A No. 54-21728), azo pigments having a fluorenone skeleton (JP-A No. 54-22834) ), An azo pigment having an oxadiazole skeleton (described in JP-A No. 54-12742), an azo pigment having a bis-stilbene skeleton (described in JP-A No. 54-17733), a distyryl oxadiazole An azo pigment having a skeleton (described in JP-A-54-2129), an azo face having a distyrylcarbazole skeleton (Described in JP-A-54-17734) and the like.

Among these azo pigments, it is preferable from the viewpoint of increasing the speed of the electrophotographic apparatus to use a highly sensitive asymmetric disazo pigment represented by the general formula (I). For these asymmetric disazo pigments, the corresponding diazonium salt compound and the coupler corresponding to Cp1 or Cp2 are reacted sequentially in two stages, or the diazonium salt compound obtained by the coupling reaction with the first Cp1 or Cp2 is isolated. Thereafter, it can be obtained by reacting the remaining coupler.
Examples of these asymmetric disazo pigments A are exemplified below, but the present invention is naturally not limited to the following examples.

  Examples of the couplers Cp1 and Cp2 of these asymmetric disazo pigments are illustrated below, but the present invention is not limited to the following examples.

  In the general formula (II), preferred examples of the couplers Cp1 and Cp2 include coupler residues represented by the following general formulas (IV) to (IX).

  In the general formulas (IV) and (V), X is a carbon atom such as a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, dibenzothiophene ring, etc., which may be substituted with a benzene ring. Represents a residue necessary for forming a hydrogen ring or a heterocyclic group. In the general formula (VIII), Y represents a divalent aromatic hydrocarbon group which may have a substituent or a divalent heterocyclic group containing a nitrogen atom in the ring. In the general formulas (IV) and (V), R1, R2, R3 and R4 each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group or a heterocyclic group which may have a substituent, R2 or R3 and R4 may be bonded together to form a cyclic amino group containing a nitrogen atom in the ring. In the general formula (VI), R5 represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group, an aralkyl group or a heterocyclic group. In the general formulas (VII) and (VIII), R6 and R7 each represents an optionally substituted alkyl group, aryl group, aralkyl group or heterocyclic group. In the general formulas (VI) and (VII), Ar1 and Ar2 each represents an aryl group or a heterocyclic group which may have a substituent. In the general formula (IV), p represents 0 or 1.

  Examples of the alkyl group in the above expression include groups such as methyl, ethyl and propyl, aralkyl groups such as benzyl and phenethyl, aryl groups such as phenyl, naphthyl and anthryl, heterocyclic groups such as pyridyl, Examples include thienyl, thiazolyl, carbazolyl, benzimidazolyl, benzothiazolyl and the like, and cyclic amino groups containing a nitrogen atom in the ring include pyrrole, pyrroline, pyrrolidine, pyrrolidone, indole, indolyl, carbazole, imidazole, pyrazole, pyrazoline, oxazine, Examples include phenoxazine. Substituents include alkyl groups such as methyl, ethyl, propyl and butyl, alkoxy groups such as methoxy, ethoxy and propoxy, halogen atoms such as fluorine, chlorine and bromine, and dialkylamino such as dimethylamino and diethylamino. Group, phenylcarbamoyl group, nitro group, cyano group, halomethyl group such as trifluoromethyl, and the like.

  Among these asymmetric disazo pigments, the compound represented by the general formula (II) having a fluorenone central skeleton represented by A-20 is particularly preferable from the viewpoint of sensitivity and potential stability. Specific examples of the asymmetric disazo pigment represented by the general formula (II) are shown in Table 3 below, but the present invention is not limited thereto.

  Since these asymmetric azo pigments are asymmetric, it is considered that the charge distribution is biased compared to the symmetric azo pigments, and the interaction between molecules is stronger. Accordingly, it is considered that the storage stability is poor when the coating liquid is used, but a coating liquid having a high storage stability can be produced by dispersing by the method of the present invention.

The charge generation layer (17) is dispersed using a ball mill disperser to prepare a coating solution, and the obtained coating solution is applied onto the conductive support (11) or the intermediate layer (13) and dried. Can be formed.
Examples of the binder resin used for the charge generation layer (17) include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl formal, polyvinyl ketone, polystyrene, poly-vinyl carbazole, polyacrylamide, and polyvinyl butyral. , Polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone and the like. The amount of the binder resin is 10 to 500 parts by weight, preferably 25 to 300 parts by weight, based on 100 parts by weight of the charge generating material. The film thickness of the charge generation layer is 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer (19) can be formed by dissolving or dispersing the charge transport material and the binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, etc. can also be added as needed. Charge transport materials include electron transport materials and hole transport materials. Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.
Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, other poly Known materials such as a merized hole transport material can be used.
Examples of the binder resin used for the charge transport layer include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. Coalescence, polyvinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Examples include melamine resins, urethane resins, phenol resins, alkyd resins, and thermoplastic or thermosetting resins such as various polycarbonate copolymers described in JP-A-5-158250 and JP-A-6-51544. It is.
The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 50 μm.
As the solvent used for the charge transport layer, tetrahydrofuran, dioxane, dioxolane, toluene, xylene, monochlorobenzene, dichloroethane, dichloromethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.
Furthermore, a leveling agent or an antioxidant may be added to the charge transport layer (19). As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount used is 100 parts by weight of the binder resin. 0 to 1 part by weight is suitable. Antioxidants such as hindered phenol compounds, sulfur compounds, phosphorus compounds, hindered amine compounds, pyridine derivatives, piperidine derivatives and morpholine derivatives can be used as the antioxidant.

In the electrophotographic photoreceptor of the present invention, an intermediate layer (13) can be provided between the conductive support (11) and the photosensitive layer (15). The intermediate layer (13) is generally composed mainly of a resin, but these resins are resins having a high solvent resistance with respect to a general organic solvent in consideration of applying a photosensitive layer thereon with a solvent. It is desirable to be. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. In addition, a fine powder pigment of metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide or the like is added to the intermediate layer (13) in order to prevent moire and reduce residual potential. May be.
Further, as the intermediate layer (13) of the present invention, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, a titanyl chelate compound, a zirconium chelate compound, a titanyl alkoxide compound, and an organic titanyl compound can also be used. In addition, in the intermediate layer (13) of the present invention, Al ₂ O ₃ is provided by anodic oxidation, organic substances such as polyparaxylylene, SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO _2, etc. Those provided with an inorganic material by a vacuum thin film forming method can also be used favorably. These intermediate layers (13) can be formed using an appropriate solvent, dispersion, and coating method as in the photosensitive layer described above. The film thickness of the intermediate layer (13) is suitably from 0 to 10 μm.

The protective layer (21) is provided for the purpose of improving the durability of the photoreceptor. Materials used for the protective layer (21) include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl. Sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, poly Examples of the resin include vinyl chloride, polyvinylidene chloride, and epoxy resin.
In addition to the protective layer (21), a fluorine resin such as polytetrafluoroethylene, a silicone resin, or an inorganic material such as titanium oxide, tin oxide, or potassium titanate may be added for the purpose of improving wear resistance. it can. Moreover, well-known materials, such as a-C and a-SiC formed with the vacuum thin film preparation method, can also be used as a protective layer (21). As a method for forming the protective layer (21), a normal coating method can be used. In addition, 0.1-10 micrometers is suitable for the thickness of a protective layer (21).

Next, the electrophotographic apparatus and the electrophotographic apparatus process cartridge used in the present invention will be described. FIG. 5 is a schematic diagram for explaining the electrophotographic apparatus according to the present invention, and is not limited to the form shown in the figure. Modifications described below also belong to the category of the present invention. Is. In FIG. 5, the electrophotographic photosensitive member (1) is provided with a photosensitive layer formed on a conductive support using the dispersion prepared by the method described above. The electrophotographic photosensitive member (1) has a drum shape, but may be a sheet shape or an endless belt shape. The charging charger (3), pre-transfer charger (7), transfer charger (10), separation charger (11), and pre-cleaning charger (13) include corotron, scorotron, solid state charger, and charging. Known means such as a roller is used. As the transfer means, the above charger can be generally used.
Further, light sources such as the image exposure unit (5) and the charge removal lamp (2) include fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LD), electroluminescence (EL). ) And other luminescent materials can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range. In addition to the steps shown in FIG. 5, such a light source or the like irradiates the electrophotographic photosensitive member with light by providing a transfer step using light irradiation, a static elimination step, a cleaning step, or a pre-exposure step. .
The toner developed on the electrophotographic photosensitive member (1) by the developing unit (6) is transferred to the transfer paper (9), but not all is transferred and remains on the photosensitive member (1). Toner is also produced. Such toner is removed from the photoreceptor by the fur brush (14) and the blade (15). The cleaning may be performed only with a blade or a cleaning brush, and known cleaning brushes such as a fur brush and a mag fur brush are used as the cleaning brush. However, when the developing unit has a cleaning function, cleaning parts such as the fur brush (14) and the blade (15) are not necessary.
When the electrophotographic photosensitive member according to the present invention is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with toner of negative (positive) polarity (electrodetection fine particles), a positive image can be obtained. On the other hand, a negative image can be obtained by developing with positive (negative) polarity toner. A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.

The electrophotographic apparatus illustrated as described above exemplifies an embodiment of the present invention, and of course, other embodiments are possible.
On the other hand, in the light irradiation process, image exposure, pre-cleaning exposure, and static elimination exposure are illustrated, but other pre-exposure exposure, pre-exposure of image exposure, and other known light irradiation processes are provided to light the photosensitive member Irradiation can also be performed.

  Image forming means and processes as shown in the above description of the electrophotographic apparatus may be incorporated in the copying apparatus, facsimile, and printer in the form of a process cartridge. A process cartridge is a single device (part) that contains a photosensitive member and includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. There are many process cartridge shapes and the like, but a general example is that used in Imagio MF200 (manufactured by Ricoh Co., Ltd.) as shown in FIG.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
[Comparative Example 1]
2 parts by weight of polyamide resin (CM-8000: manufactured by Toray Industries, Inc.) was dissolved in a mixed solvent of 20 parts by weight of n-butanol and 80 parts by weight of methanol to prepare an intermediate layer coating solution. This was applied onto an aluminum drum having a diameter of 30 mm and a length of 340 mm, and dried at 130 ° C. for 20 minutes to provide an intermediate layer having a thickness of 0.5 μm.
Next, a glass ball mill having an inner diameter of 0.2 m was prepared by mixing a mixture of 60 parts by weight of the disazo pigment represented by the following structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone. , 6 mm PSZ balls with a ball mill capacity of 20%, and dispersed for 4 days at 57 rpm (V = 0.6). After dispersion, 4512 parts by weight of cyclohexanone is added and dispersed for 3 hours to generate charges. A layer coating solution was prepared. This coating solution was applied onto the intermediate layer by a dip coating method and dried to provide a charge generation layer having a thickness of 0.25 μm.

  Next, 7 parts by weight of a charge transport material represented by the following structural formula (B), 10 parts by weight of polycarbonate (Z type: viscosity average molecular weight 50,000), silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) 0.002 A part by weight was dissolved in 83 parts by weight of tetrahydrofuran to prepare a charge transport layer coating solution. This was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 25 μm, whereby the electrophotographic photosensitive member of Example 1 was obtained.

[Comparative Example 2]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ6 mm Of PSZ balls of 20% in the ball mill capacity and dispersed for 4 days at a rotation speed of 124 rpm (V = 1.3). After the dispersion, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours to apply the coating for the charge generation layer. A liquid was prepared.

[Example 1]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ6 mm Of PSZ balls of 20% in the ball mill capacity and dispersed for 4 days at a rotation speed of 67 rpm (V = 0.7). After the dispersion, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours. A liquid was prepared.

[Example 2]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ6 mm Of PSZ balls of 20% in the ball mill capacity and dispersed at 115 rpm (V = 1.2) for 4 days. After dispersion, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours to apply the coating for the charge generation layer. A liquid was prepared.

[Example 3]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ5 mm Of PSZ balls of 20% in the ball mill capacity and dispersed for 4 days at a rotation speed of 67 rpm (V = 0.7). After the dispersion, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours. A liquid was prepared.

[Example 4]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ1 mm Of PSZ balls of 20% in the ball mill capacity and dispersed for 4 days at a rotation speed of 67 rpm (V = 0.7). After the dispersion, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours. A liquid was prepared.

[Example 5]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ5 mm PSZ balls of 30% of the ball mill's internal volume were added and dispersed for 4 days at a rotation speed of 67 rpm (V = 0.7). After the dispersion was completed, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours to apply the coating for the charge generation layer. A liquid was prepared.

[Example 6]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ5 mm Of PSZ balls of 40% in the ball mill capacity and dispersed for 4 days at a rotation speed of 67 rpm (V = 0.7). After the dispersion, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours to apply the coating for the charge generation layer. A liquid was prepared.

[Example 7]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.15 m, and φ5 mm 30% of the ball mill internal capacity was added and dispersed at a rotational speed of 89 rpm (V = 0.7) for 4 days. After the dispersion was completed, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours to apply the coating for the charge generation layer. A liquid was prepared.

[Example 8]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.01 m, and φ5 mm 30% of the ball mill's internal capacity was added and dispersed at a rotational speed of 1338 rpm (V = 0.7) for 4 days. After dispersion was completed, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours. A liquid was prepared.

[Example 9]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ5 mm 30% of the volume of the ball mill was added and dispersed at a rotational speed of 1338 rpm (V = 0.7) for 4 days. After dispersion was completed, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours. A liquid was prepared.

[Example 10]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (C), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ5 mm PSZ balls of 30% of the ball mill's internal volume were added and dispersed for 4 days at a rotation speed of 67 rpm (V = 0.7). After the dispersion was completed, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours to apply the coating for the charge generation layer. A liquid was prepared.

[Example 11]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (D), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of methyl ethyl ketone was placed in a glass ball mill having an inner diameter of 0.2 m, and φ5 mm PSZ balls of 30% of the ball mill's internal volume were added and dispersed for 4 days at a rotation speed of 67 rpm (V = 0.7). After the dispersion was completed, 4512 parts by weight of cyclohexanone was added and dispersed for 3 hours to apply the coating for the charge generation layer. A liquid was prepared.

[Example 12]
The same as Comparative Example 1 except that the production of the charge generation layer coating solution of Comparative Example 1 was changed as follows.
A mixture of 60 parts by weight of the disazo pigment represented by the structural formula (A), 12 parts by weight of polyvinyl butyral (ESREC BM-1: manufactured by Sekisui Chemical) and 216 parts by weight of ethyl acetate was placed in a glass ball mill having an inner diameter of 0.2 m. Add PS5 balls of 5mm in diameter to 30% of the ball mill capacity and disperse for 4 days at a rotation speed of 67rpm (V = 0.7). After dispersion, add 4512 parts by weight of cyclohexanone and disperse for 3 hours. A working solution was prepared.

The following evaluation was performed about the coating liquid for charge generation layers and the electrophotographic photosensitive member produced in Comparative Examples 1 and 2 and Examples 1 to 12 described above.
The charge generation layer coating solution was evaluated for the average particle size (median diameter) and viscosity change immediately after production.
The average particle diameter (median diameter) was measured with a Horiba ultracentrifugal particle size distribution analyzer CAPA-700 (manufactured by Horiba, Ltd.).
The viscosity was measured with an E-type viscometer (model: ELD manufactured by Tokyo Keiki Co., Ltd.) under the conditions of 20 ° C. and 100 rotations. In addition, what was preserve | saved at normal temperature immediately after preparation and for one month was measured, and the viscosity change was evaluated.
As the coating film evaluation, the charge generation layer coated with the coating solution for charge generation layer after storage for 1 month was visually evaluated for the presence or absence of foreign matters which are pigment aggregates of φ0.5 mm or more.
The results are shown in Table 5, where 10 or more foreign matters are indicated as x, 1 to 10 as Δ, and 0 as ○.
△ and ○ are acceptable.
For the electrophotographic photosensitive member, an electrophotographic photosensitive member prepared using the coating solution for charge generation layer after storage for 1 month was used, and image evaluation was performed using Spirio 1510 (manufactured by Ricoh Co., Ltd.). Images after running 200000 sheets were evaluated in 5 stages. Rank 5 indicates no abnormality, and rank 1 is the lowest image quality.
Rank 3 or higher is acceptable.
In addition, for those in which the coating film evaluation was ◯ and the image evaluation was not rank 5, dispersion was continued for 10 days as a limit, and the dispersion time during which the coating film evaluation was ◯ and image evaluation was rank 5 was also evaluated.

FIG. 2 is a cross-sectional view illustrating a configuration example of an electrophotographic photoreceptor according to the present invention. It is sectional drawing which shows another structural example of the electrophotographic photoreceptor which concerns on this invention. It is sectional drawing which shows another structural example which concerns on this invention. It is sectional drawing which shows another structural example which concerns on this invention. It is the schematic for demonstrating the electrophotographic apparatus which concerns on this invention. It is the schematic which shows one specific example of the process cartridge which concerns on this invention. It is the figure which showed the structural example of the ball mill dispersion | distribution apparatus.

Explanation of symbols

(FIGS. 1 to 4)
11 Conductive support
13 Middle layer
15 Photosensitive layer
17 Charge generation layer
19 Charge transport layer
21 Protective layer
(Fig. 5)
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charger charger 4 Eraser 5 Image exposure part 6 Developing unit 7 Charger before transfer 8 Registration roller 9 Transfer body 10 Transfer charger 11 Separation charger 12 Separation claw 13 Charger before cleaning 14 Fur brush 15 Cleaning blade (FIG. 6) )
101 Photosensitive drum
102 Charging device
103 exposure
104 Developing device
105 Transcript
106 Transfer device
107 Cleaning blade
108 Static elimination lamp
109 Fixing device
(105: transfer body, 106: transfer device, 108: static elimination lamp, 109: fixing device are not included in the cartridge portion.)

Claims (11)

In a method for producing a coating solution for an electrophotographic photoreceptor in which an azo pigment is dispersed at least in a solvent, the coating solution is dispersed by a ball mill, and the rotation speed of the ball mill is calculated by the following formula (1). A method for producing an electrophotographic photosensitive member, wherein V is a number (R / rpm) and V in formula (1) is in a range of 0.7 ≦ V ≦ 1.2.

R: Number of revolutions (rpm)
D: Ball mill pot diameter (m) The method for producing an electrophotographic photosensitive member according to claim 1, wherein the diameter of the medium used is 2 mm or more and 5 mm or less. 3. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the amount of media used is 25% or more and 35% or less of the ball mill volume. 4. The method for producing an electrophotographic photosensitive member according to claim 1, wherein a diameter of the pot of the ball mill is 0.02 m or more and 0.15 m or less. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the medium is a PSZ ball. The azo pigment is represented by the following general formula (I):

(Wherein A represents a divalent residue bonded to the nitrogen atom of the azo group by a carbon atom; Cp1 and Cp2 represent coupler residues having different structures from each other), and an asymmetric disazo pigment represented by The method for producing an electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is provided. The method for producing an electrophotographic photoreceptor according to claim 6, wherein the asymmetric azo pigment represented by the general formula (I) is a compound represented by the following general formula (II).

(In the formula, Cp1 and Cp3 represent coupler residues having different structures from each other.) The method for producing an electrophotographic photosensitive member according to claim 6, wherein the dispersion medium of the coating solution contains a ketone solvent. An electrophotographic photosensitive member obtained by the method for producing an electrophotographic photosensitive member according to claim 1. 10. An electrophotographic apparatus comprising at least a charging unit, an image exposing unit, a developing unit, a transferring unit, a charge eliminating unit, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 9. An electrophotographic apparatus, characterized in that A process cartridge for an electrophotographic apparatus, comprising at least an electrophotographic photoreceptor, wherein the electrophotographic photoreceptor is the electrophotographic photoreceptor according to claim 9. .

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