DESCRIPTION

Title of Invention

ELECTROPHOTOGRAPHIC PHOTOSENSITIVE MEMBER, PROCESS CARTRIDGE, AND ELECTROPHOTOGRAPHIC

APPARATUS

Technical Field

[0001] he present invention relates to an electrophotographic photosensitive member, a process cartridge and

electrophotographic apparatus having an

electrophotographic photosensitive member.

Background Art

[ 0002 ] Recently, research and development of

electrophotographic photosensitive members (organic electrophotographic photosensitive members) using an organic photoconductive material have been performed actively .

[0003] The electrophotographic photosensitive member basically includes a support and a photosensitive layer formed on the support. Actually, however, in order to cover defects of the surface of the support, protect the photosensitive layer from electrical damage, improve charging properties, and improve charge injection prohibiting properties from the support to the

photosensitive layer, a variety of layers is often provided between the support and the photosensitive layer .

[0004] Among the layers provided between the support and the photosensitive layer, as a layer provided to cover defects of the surface of the support, a layer

containing metal oxide particles is known. The layer containing a metal oxide particle usually has a higher conductivity than that of the layer containing no metal oxide particle (for example, volume resistivity of 1.0 χ 10 ⁸ to 5.0 x 10 ¹² Ω-cm). Thus, even if the film thickness of the layer is increased, residual potential is hardly increased at the time of forming an image, and dark potential and bright potential hardly

fluctuate. For this reason, the defects of the surface of the support are easily covered. Such a highly conductive layer (hereinafter, referred to as a

"conductive layer (electrically conductive layer)") is provided between the support and the photosensitive layer to cover the defects of the surface of the support. Thereby, the tolerable range of the defects of the surface of the support is wider. As a result, the tolerable range of the support to be used is significantly wider, leading to an advantage in that productivity of the electrophotographic photosensitive member can be improved.

[0005] Patent Literature 1 discloses a technique for

containing a titanium oxide particle coated with tin oxide doped with phosphorus, tungsten, or fluorine in a conductive layer provided between a support and a photosensitive layer.

[0006] Patent Literature 2 discloses a technique for

containing a titanium oxide particle coated with tin oxide doped with phosphorus or tungsten in a conductive layer provided between a support and a photosensitive layer .

Citation List

Patent Literature

[0007] PTL 1: Japanese Patent Application Laid-Open No. 2012- 018370

PTL 2: Japanese Patent Application Laid-Open No. 2012- 018371

Summary of Invention

Technical Problem

[ 0008 ] Unfortunately, examination by the present inventors revealed that if a high voltage is applied to an electrophotographic photosensitive member using such a layer containing a titanium oxide particle coated with tin oxide doped with phosphorus, tungsten, niobium, tantalum, or fluorine as a conductive layer under a low temperature and low humidity environment, a leak easily occurs in the electrophotographic photosensitive member. The leak is a phenomenon such that a portion of the electrophotographic photosensitive member locally breaks down, and an excessive current flows through the portion. If the leak occurs, the electrophotographic photosensitive member cannot be sufficiently charged, leading to image defects such as black dots, horizontal white stripes and horizontal black stripes formed on an image. The horizontal white stripes are white stripes that appear on an output image in the direction

corresponding to the direction intersecting

perpendicular to the rotational direction

(circumferential direction) of the electrophotographic photosensitive member. The horizontal black stripes are black stripes that appear on an output image in the direction corresponding to a direction intersecting perpendicular to the rotational direction

(circumferential direction) of the electrophotographic photosensitive member.

[0009] The present invention is directed to providing an

electrophotographic photosensitive member in which a leak hardly occurs even if a layer containing a

titanium oxide particle coated with tin oxide doped with phosphorus, tungsten, niobium, tantalum, or

fluorine as a metal oxide particle is used as a

conductive layer in the electrophotographic

photosensitive member, and a process cartridge and electrophotographic apparatus having the

electrophotographic photosensitive member.

Solution to Problem

[ 0010 ] According to one aspect of the present invention, there is provided an electrophotographic photosensitive member including a support, a conductive layer formed on the support, and a photosensitive layer formed on the conductive layer, wherein the conductive layer includes a binder material, a first metal oxide

particle, and a second metal oxide particle, the first metal oxide particle is a titanium oxide particle coated with tin oxide doped with phosphorus, tungsten, niobium, tantalum, or fluorine, the second metal oxide particle is an uncoated titanium oxide particle, a content of the first metal oxide particle in the conductive layer is not less than 20% by volume and not more than 50% by volume based on a total volume of the conductive layer, and a content of the second metal oxide particle in the conductive layer is not less than 1.0% by volume and not more than 15% by volume based on the total volume of the conductive layer, and not less than 5.0% by volume and not more than 30% by volume based on the content of the first metal oxide particle in the conductive layer.

] According to another aspect of the present invention, there is provided a process cartridge that integrally supports the electrophotographic photosensitive member and at least one selected from the group consisting of a charging unit, a developing unit, a transfer unit, and a cleaning unit, and is detachably mountable on a main body of an electrophotographic apparatus.

]According to further aspect of the present invention, there is provided an electrophotographic apparatus including the electrophotographic photosensitive member a charging unit, an exposing unit, a developing unit, and a transfer unit.

Advantageous Effects of Invention

] he present invention can provide an

electrophotographic photosensitive member in which a leak hardly occurs even if the layer containing a titanium oxide particle coated with tin oxide doped with phosphorus, tungsten, niobium, tantalum, or fluorine as the metal oxide particle is used as the conductive layer in the electrophotographic

photosensitive member, and provide the process

cartridge and electrophotographic apparatus having the electrophotographic photosensitive member.

[ 0014 ] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. Brief Description of Drawings

[0015] Fig. 1 is a drawing illustrating an example of a

schematic configuration of an electrophotographic apparatus including a process cartridge having an electrophotographic photosensitive member.

Fig. 2 is a drawing illustrating an example of a probe pressure resistance test apparatus.

Fig. 3 is a drawing (top view) for describing a method for measuring a volume resistivity of a conductive layer .

Fig. 4 is a drawing (sectional view) for describing a method for measuring a volume resistivity of a

conductive layer.

Fig. 5 is a drawing for describing an image of a one dot KEIMA pattern.

Description of Embodiments

[0016] An electrophotographic photosensitive member according to the present invention is an electrophotographic photosensitive member including a support, a conductive layer formed on the support, and a photosensitive layer formed on the conductive layer.

[0017] he photosensitive layer may be a single photosensitive layer in which a charge-generating substance and a charge transport substance are contained in a single layer, or a laminated photosensitive layer in which a charge-generating layer containing a charge-generating substance and a charge transport layer containing a charge transport substance are laminated. Moreover, when necessary, the electrophotographic photosensitive member according to the present invention can be provided with an undercoat layer between the conductive layer formed on the support and the photosensitive layer .

[0018]As the support, those having conductivity (conductive support) can be used, and metallic supports formed with a metal such as aluminum, an aluminum alloy, and stainless steel can be used. In a case where aluminum or an aluminum alloy is used, an aluminum tube produced by a production method including extrusion and drawing or an aluminum tube produced by a production method including extrusion and ironing can be used. Such an aluminum tube has high precision of the size and surface smoothness without machining the surface, and has an advantage from the viewpoint of cost.

Unfortunately, the aluminum tube not machined often has defects like ragged projections on the surface thereof. Then, the defects like ragged projections on the surface of the aluminum tube not machined are easily covered by providing the conductive layer.

[0019] In the present invention, the conductive layer is

provided on the support to cover the defects on the surface of the support.

[0020] he conductive layer can have a volume resistivity of not less than 1.0 ^χ 10 ⁸ Ω-cm and not more than 5.0 ^χ 10 ¹² Ω-cm. At a volume resistivity of the conductive layer of not more than 5.0 ^χ 10 ¹² Ω-cm, a flow of charges hardly stagnates during image formation. As a result, the residual potential hardly increases, and the dark potential and the bright potential hardly fluctuate. At a volume resistivity of a conductive layer of not less than 1.0 ^χ 10 ⁸ Ω-cm, charges are difficult to excessively flow in the conductive layer during charging the electrophotographic photosensitive member, and the leak hardly occurs. [0021] Using Fig. 3 and Fig. 4, a method for measuring the volume resistivity of the conductive layer in the electrophotographic photosensitive member will be described. Fig. 3 is a top view for describing a method for measuring a volume resistivity of a

conductive layer, and Fig. 4 is a sectional view for describing a method for measuring a volume resistivity of a conductive layer.

[0022] he volume resistivity of the conductive layer is

measured under an environment of normal temperature and normal humidity (23°C/50%RH) . A copper tape 203 (made by Sumitomo 3M Limited, No. 1181) is applied to the surface of the conductive layer 202, and the copper tape is used as an electrode on the side of the surface of the conductive layer 202. The support 201 is used as an electrode on a rear surface side of the

conductive layer 202. Between the copper tape 203 and the support 201, a power supply 206 for applying voltage, and a current measurement apparatus 207 for measuring the current that flows between the copper tape 203 and the support 201 are provided. In order to apply voltage to the copper tape 203, a copper wire 204 is placed on the copper tape 203, and a copper tape 205 similar to the copper tape 203 is applied onto the copper wire 204 such that the copper wire 204 is not out of the copper tape 203, to fix the copper wire 204 to the copper tape 203. The voltage is applied to the copper tape 203 using the copper wire 204.

[0023] The value represented by the following relation (1) is the volume resistivity p [Ω-cm] of the conductive layer 202 wherein I ₀ [A] is a background current value when no voltage is applied between the copper tape 203 and the support 201, I [A] is a current value when -1 V of the voltage having only a DC voltage (DC component) is applied, the film thickness of the conductive layer 202 is d [cm] , and the area of the electrode (copper tape 203) on the surface side of the conductive layer 202 is S [cm ² ] :

p = 1/(1 - Io) x S/d [Ω-cm] ... (1)

[0024] In this measurement, a slight amount of the current of not more than 1 ^χ 10 ^~6 A in an absolute value is

measured. Accordingly, the measurement is preferably performed using a current measurement apparatus 207 that can measure such a slight amount of the current. Examples of such an apparatus include a pA meter (trade name: 4140B) made by Yokogawa Hewlett-Packard Ltd.

[0025] he volume resistivity of the conductive layer

indicates the same value when the volume resistivity is measured in the state where only the conductive layer is formed on the support and in the state where the respective layers (such as the photosensitive layer) on the conductive layer are removed from the

electrophotographic photosensitive member and only the conductive layer is left on the support.

[0026] he conductive layer in the electrophotographic

photosensitive member of the present invention contains a binder material, a first metal oxide particle, and a second metal oxide particle.

[0027] In the present invention, as the first metal oxide

particle, a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with phosphorus (P) , a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with tungsten (W) , a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with niobium (Nb) , a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with tantalum (Ta) , or a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with fluorine (F) is used. Hereinafter, these are also referred to as a "titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide" generally.

[0028 ] Further, in the present invention, an uncoated titanium oxide particle is used as the second metal oxide particle. Here, the uncoated titanium oxide particle means a titanium oxide particle not coated with an inorganic material such as tin oxide and aluminum oxide and not coated (surface treated) with an organic material such as a silane coupling agent. This is also abbreviated to and referred to as an "uncoated titanium oxide particle".

[0029] The titanium oxide particle coated with P/W/Nb/Ta/F- doped tin oxide used as the first metal oxide particle is contained in the conductive layer. The content is not less than 20% by volume and not more than 50% by volume based on the total volume of the conductive layer .

[0030] The uncoated titanium oxide particle used as the second metal oxide particle is contained in the conductive layer. The content is not less than 1.0% by volume and not more than 15% by volume based on the total volume of the conductive layer, and not less than 5.0% by volume and not more than 30% by volume (preferably not less than 5.0% by volume and not more than 20% by volume) based on the content of the first metal oxide particle (titanium oxide particle coated with

P/W/Nb/Ta/F-doped tin oxide) in the conductive layer.

[0031] If the content of the first metal oxide particle

(titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) in the conductive layer is less than 20% by volume based on the total volume of the conductive layer, the distance between the first metal oxide particles (titanium oxide particles coated with

P/W/Nb/Ta/F-doped tin oxide) are likely to be longer. As the distance between the first metal oxide particles (titanium oxide particles coated with P/W/Nb/Ta/F-doped tin oxide) are longer, the volume resistivity of the conductive layer is higher. Then, a flow of charges is likely to stagnate during image formation to increase the residual potential and fluctuate the dark potential and the bright potential.

[0032] If the content of the first metal oxide particle

(titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) in the conductive layer is more than 50% by volume based on the total volume of the conductive layer, the first metal oxide particles (titanium oxide particles coated with P/W/Nb/Ta/F-doped tin oxide) are likely to contact each other. The portion of the conductive layer in which the first metal oxide

particles (titanium oxide particles coated with

P/W/Nb/Ta/F-doped tin oxide) contact each other has a low volume resistivity locally, and easily causes the leak to occur in the electrophotographic photosensitive member .

[0033]A method of producing a titanium oxide particle coated with tin oxide (Sn0 ₂ ) doped with phosphorus (P) or the like is disclosed also in Japanese Patent Application Laid-Open No. H06-207118 and Japanese Patent

Application Laid-Open No. 2004-349167.

[0034] It is thought that the uncoated titanium oxide particle as the second metal oxide particle plays a role for the titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide as the first metal oxide particle in

suppressing occurrence of the leak when a high voltage is applied to the electrophotographic photosensitive member under a low temperature and low humidity

environment .

[0035] It is thought that charges flowing in the conductive layer usually flow mainly on the surface of the

titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide having a lower powder resistivity than that of the uncoated titanium oxide particle. However, when a high voltage is applied to the electrophotographic photosensitive member and excessive charges are going to flow in the conductive layer, the excessive charges cannot be completely flown only by the surface of the titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide. As a result, the leak easily occurs in the electrophotographic photosensitive member.

[0036] Meanwhile, it is thought that by using the titanium

oxide particle coated with P/W/Nb/Ta/F-doped tin oxide and the uncoated titanium oxide particle having a higher powder resistivity than that of the titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide in combination for the conductive layer, charges flow on the surface of the uncoated titanium oxide particle in addition to the surface of the titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide only when excessive charges are going to flow in the

conductive layer. The titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide and the uncoated titanium oxide particle both are metal oxide particles containing titanium oxide as a metal oxide. For this reason, it is thought that when excessive charges are going to flow in the conductive layer, the charges are easy to uniformly flow on the surface of the titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide and the surface of the uncoated titanium oxide particle and uniformly flow in the conductive layer, and as a result occurrence of the leak is suppressed.

[0037] If the content of the second metal oxide particle

(uncoated titanium oxide particle) in the conductive layer is less than 1.0% by volume based on the total volume of the conductive layer, the effect to be obtained by containing the second metal oxide particle (uncoated titanium oxide particle) in the conductive layer is small.

[0038] If the content of the second metal oxide particle

(uncoated titanium oxide particle) in the conductive layer is more than 20% by volume based on the total volume of the conductive layer, the volume resistivity of the conductive layer is likely to be higher. Then, a flow of charges is likely to stagnate during image formation to increase the residual potential and fluctuate the dark potential and the bright potential.

[0039] If the content of the second metal oxide particle

(uncoated titanium oxide particle) in the conductive layer is less than 5.0% by volume based on the content of the titanium oxide particle coated with P/W/Nb/Ta/F- doped tin oxide, the effect to be obtained by

containing the second metal oxide particle (uncoated titanium oxide particle) in the conductive layer is small .

[0040] If the content of the second metal oxide particle

(uncoated titanium oxide particle) in the conductive layer is more than 30% by volume based on the content of the titanium oxide particle coated with P/W/Nb/Ta/F- doped tin oxide, the volume resistivity of the

conductive layer is likely to be higher. Then, a flow of charges is likely to stagnate during image formation to increase the residual potential and fluctuate the dark potential and the bright potential.

[0041] The form of the titanium oxide (Ti0 ₂ ) particle as the core material particle in the titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide and the form of the uncoated titanium oxide particle in use can be granular, spherical, needle-like, fibrous, cylindrical, rod-like, spindle-like, plate-like, and other forms. Among these, spherical forms are preferable because image defects such as black spots are decreased.

[0042] The titanium oxide (Ti0 ₂ ) particle as the core material particle in the titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide may have any crystal form of rutile, anatase, and brookite forms, for example. The titanium oxide (Ti0 ₂ ) particle may be amorphous. The same is true of the uncoated titanium oxide

particle .

[0043] The method of producing a particle may be any production method such as a sulfuric acid method and a hydrochloric acid method, for example.

[0044] he first metal oxide particle (titanium oxide particle coated with P/ /Nb/Ta/F-doped tin oxide) in the

conductive layer has the average primary particle diameter (Di) of preferably not less than 0.10 μπ\ and not more than 0.45 μπι, and more preferably not less than 0.15 μιη and not more than 0.40 μπι.

[0045] If the first metal oxide particle (titanium oxide

particle coated with P/W/Nb/Ta/F-doped tin oxide) has the average primary particle diameter of not less than 0.10 μπι, the first metal oxide particle (titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) hardly aggregates again after the coating liquid for a conductive layer is prepared. If the first metal oxide particle (titanium oxide particle coated with

P/W/Nb/Ta/F-doped tin oxide) aggregates again, the stability of the coating liquid for a conductive layer easily reduces, or the surface of the conductive layer to be formed easily cracks.

[0046] If the first metal oxide particle (titanium oxide

particle coated with P/W/Nb/Ta/F-doped tin oxide) has the average primary particle diameter of not more than 0.45 μπι, the surface of the conductive layer hardly roughens. If the surface of the conductive layer roughens, charges are likely to be locally injected into the photosensitive layer, causing remarkable black dots (black spots) in the white solid portion in the output image .

[0047] The ratio (Di/D ₂ ) of the average primary particle

diameter (Di) of the first metal oxide particle

(titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) to the average primary particle diameter (D ₂ ) of the second metal oxide particle (uncoated titanium oxide particle) in the conductive layer can be not less than 0.7 and not more than 1.3. [0048]At a ratio (Di/D ₂ ) of not less than 0.7, the average primary particle diameter of the second metal oxide particle (uncoated titanium oxide particle) is not excessively larger than the average primary particle diameter of the first metal oxide particle (titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) . Thereby, the dark potential and the bright potential hardly fluctuate.

[0049] At a ratio (Di/D ₂ ) of not more than 1.3, the average

primary particle diameter of the second metal oxide particle (uncoated titanium oxide particle) is not excessively smaller than the average primary particle diameter of the first metal oxide particle (titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) . Thereby, the leak hardly occurs.

[0050] In the present invention, the content of the first

metal oxide particle and second metal oxide particle in the conductive layer and the average primary particle diameter thereof are measured based on a three- dimensional structure analysis obtained from the

element mapping using an FIB-SEM and FIB-SEM slice & view .

[0051]A method of measuring the powder resistivity of the

titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide is as follows .

[0052] The powder resistivity of the first metal oxide

particle (titanium oxide particle coated with

P/W/Nb/Ta/F-doped tin oxide) and that of the second metal oxide particle (uncoated titanium oxide particle) are measured under a normal temperature and normal humidity (23°C/50% RH) environment. In the present invention, a resistivity meter (trade name: Loresta GP) made by Mitsubishi Chemical Corporation was used as a measurement apparatus. The first metal oxide particle (titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) and second metal oxide particle (uncoated titanium oxide particle) to be measured both are solidified at a pressure of 500 kg/cm ² and formed into a pellet-like measurement sample. The voltage to be applied is 100 V.

[0053] The conductive layer can be formed as follows: a

coating liquid for a conductive layer containing a solvent, a binder material, the first metal oxide particle (titanium oxide particle coated with

P/W/Nb/Ta/F-doped tin oxide) , and the second metal oxide particle (uncoated titanium oxide particle) is applied onto the support, and the obtained coating film is dried and/or cured.

[0054] The coating liquid for a conductive layer can be

prepared by dispersing the first metal oxide particle (titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) and the second metal oxide particle

(uncoated titanium oxide particle) in a solvent

together with the binder material. Examples of a

dispersion method include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed dispersing machine.

[0055] Examples of a binder material used for preparation of the coating liquid for a conductive layer include resins such as phenol resins, polyurethanes, polyamides, polyimides, polyamidimides , polyvinyl acetals, epoxy resins, acrylic resins, melamine resins, and polyesters. One of these or two or more thereof can be used. Among these resins, curable resins are preferable and

thermosetting resins are more preferable from the viewpoint of suppressing migration (transfer) to other layer, adhesive properties to the support, the

dispersibility and dispersion stability of the first metal oxide particle (titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide) and the second metal oxide particle (uncoated titanium oxide particle) , and resistance against a solvent after formation of the layer. Among the thermosetting resins, thermosetting phenol resins and thermosetting polyurethanes are preferable. In a case where a curable resin is used for the binder material for the conductive layer, the binder material contained in the coating liquid for a conductive layer is a monomer and/or oligomer of the curable resin.

[0056] Examples of a solvent used for the coating liquid for a conductive layer include alcohols such as methanol, ethanol, and isopropanol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; and aromatic hydrocarbons such as toluene and xylene.

[0057] From the viewpoint of covering the defects of the

surface of the support, the film thickness of the conductive layer is preferably not less than 10 μπι and not more than 40 μπι, and more preferably not less than 15 μπι and not more than 35 μπι.

[0058] In the present invention, FISCHERSCOPE MMS made by

Helmut Fischer GmbH was used as an apparatus for measuring the film thickness of each layer in the electrophotographic photosensitive member including a conductive layer.

[0059] In order to suppress interference fringes produced on the output image by interference of the light reflected on the surface of the conductive layer, the coating liquid for a conductive layer may contain a surface roughening material for roughening the surface of the conductive layer. As the surface roughening material, resin particles having the average particle diameter of not less than 1 μπι and not more than 5 μπι are

preferable. Examples of the resin particles include particles of curable resins such as curable rubbers, polyurethanes, epoxy resins, alkyd resins, phenol resins, polyesters, silicone resins, and acrylic- melamine resins. Among these, particles of silicone resins difficult to aggregate are preferable. The specific gravity of the resin particle (0.5 to 2) is smaller than that of the titanium oxide particle coated with P/W/Nb/Ta/F-doped tin oxide (4 to 7) . For this reason, the surface of the conductive layer is

efficiently roughened at the time of forming the

conductive layer. The content of the surface

roughening material in the coating liquid for a

conductive layer is preferably 1 to 80% by mass based on the binder material in the coating liquid for a conductive layer.

[0060] In the present invention, the densities [g/cm ³ ] of the first metal oxide particle, the second metal oxide particle, the binder material (the density of the cured product is measured when the binder material is liquid) , the silicone particle, and the like were determined using a dry type automatic densimeter as follows.

[0061]A dry type automatic densimeter made by SHIMADZU

Corporation (trade name: Accupyc 1330) was used. As a pre-treatment of the particle to be measured, a

container having a volume of 10 cm ³ was purged with helium gas at a temperature of 23 °C and the highest pressure of 19.5 psig 10 times. Subsequently, the pressure, 0.0050 psig/min, was defined as the index of the pressure equilibrium determination value indicating whether the container inner pressure reached

equilibrium. It was considered that the deflection of the pressure inside of the sample chamber of the value or less indicated the equilibrium state, and the

measurement was started. Thus, the density [g/cm ³ ] was automatically measured.

[0062] The density of the first metal oxide particle can be

adjusted according to the amount of tin oxide to be coated, the kind of elements used for doping, the amount of the element to be doped with, and the like.

[0063] he density of the second metal oxide particle

(uncoated titanium oxide) can also be adjusted

according to the crystal form and the mixing ratio.

[0064] The coating liquid for a conductive layer may also

contain a leveling agent for increasing surface

properties of the conductive layer.

[0065] In order to prevent charge injection from the

conductive layer to the photosensitive layer, the electrophotographic photosensitive member according to the present invention can be provided with an undercoat layer (barrier layer) having electrical barrier

properties between the conductive layer and the

photosensitive layer.

[0066] The undercoat layer can be formed by applying a coating solution for an undercoat layer containing a resin (binder resin) onto the conductive layer, and drying the obtained coating film.

[0067] Examples of the resin (binder resin) used for the

undercoat layer include water soluble resins such as polyvinyl alcohol, polyvinyl methyl ether, polyacrylic acids, methyl cellulose, ethyl cellulose, polyglutamic acid, casein, and starch, polyamides, polyimides, polyamidimides, polyamic acids, melamine resins, epoxy resins, polyurethanes, and polyglutamic acid esters. Among these, in order to produce electrical barrier properties of the undercoat layer effectively,

thermoplastic resins are preferable. Among the

thermoplastic resins, thermoplastic polyamides are preferable. As polyamides, copolymerized nylons are preferable .

[0068] he film thickness of the undercoat layer is preferably not less than 0.1 μπι and not more than 2 μπι.

[0069] In order to prevent a flow of charges from stagnating in the undercoat layer, the undercoat layer may contain an electron transport substance (electron-receptive substance such as an acceptor) .

[0070] Examples of the electron transport substance include electron-withdrawing substances such as 2,4,7- trinitrofluorenone, 2,4,5, 7-tetranitrofluorenone , chloranil, and tetracyanoquinodimethane, and

polymerized products of these electron-withdrawing substances .

[0071] On the conductive layer (undercoat layer), the

photosensitive layer is provided.

[0072] Examples of the charge-generating substance used for the photosensitive layer include azo pigments such as monoazos, disazos, and trisazos; phthalocyanine

pigments such as metal phthalocyanine and non-metallic phthalocyanine; indigo pigments such as indigo and thioindigo; perylene pigments such as perylene acid anhydrides and perylene acid imides; polycyclic quinone pigments such as anthraquinone and pyrenequinone ;

squarylium dyes; pyrylium salts and thiapyrylium salts; triphenylmethane dyes; quinacridone pigments; azulenium salt pigments; cyanine dyes; xanthene dyes;

quinoneimine dyes; and styryl dyes. Among these, metal phthalocyanines such as oxytitanium phthalocyanine, hydroxy gallium phthalocyanine, and chlorogallium phthalocyanine are preferable.

[0073] In a case where the photosensitive layer is a laminated photosensitive layer, a coating solution for a charge- generating layer prepared by dispersing a charge- generating substance and a binder resin in a solvent can be applied and the obtained coating film is dried to form a charge-generating layer. Examples of the dispersion method include methods using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, or a roll mill.

[0074 ] Examples of the binder resin used for the charge- generating layer include polycarbonates, polyesters, polyarylates, butyral resins, polystyrenes, polyvinyl acetals, diallyl phthalate resins, acrylic resins, methacrylic resins, vinyl acetate resins, phenol resins, silicone resins, polysulfones , styrene-butadiene

copolymers, alkyd resins, epoxy resins, urea resins, and vinyl chloride-vinyl acetate copolymers . One of these can be used alone, or two or more thereof can be used as a mixture or a copolymer.

[0075] he proportion of the charge-generating substance to

the binder resin (charge-generating substance : binder resin) is preferably in the range of 10:1 to 1:10 (mass ratio), and more preferably in the range of 5:1 to 1:1 (mass ratio) .

[ 0076] Examples of the solvent used for the coating solution for a charge-generating layer include alcohols,

sulfoxides, ketones, ethers, esters, aliphatic

halogenated hydrocarbons, and aromatic compounds.

[0077] The film thickness of the charge-generating layer is

preferably not more than 5 μκι, and more preferably not less than 0.1 μπι and not more than 2 μπι.

[0078] To the charge-generating layer, a variety of additives such as a sensitizer, an antioxidant, an ultraviolet absorbing agent, and a plasticizer can be added when necessary. In order to prevent a flow of charges from stagnating in the charge-generating layer, the charge- generating layer may contain an electron transport substance (an electron-receptive substance such as an acceptor) .

[0079] Examples of the electron transport substance include

electron-withdrawing substances such as 2,4,7- trinitrofluorenone, 2,4,5, 7-tetranitrofluorenone, chloranil, and tetracyanoquinodimethane, and

polymerized products of these electron-withdrawing substances .

[0080] Examples of the charge transport substance used for the photosensitive layer include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triallylmethane compounds.

[0081] In a case where the photosensitive layer is a laminated photosensitive layer, a coating solution for a charge transport layer prepared by dissolving the charge transport substance and a binder resin in a solvent can be applied and the obtained coating film is dried to form a charge transport layer.

[ 0082 ] Examples of the binder resin used for the charge

transport layer include acrylic resins, styrene resins, polyesters, polycarbonates, polyarylates , polysulfones , polyphenylene oxides, epoxy resins, polyurethanes , alkyd resins, and unsaturated resins. One of these can be used alone, or two or more thereof can be used as a mixture or a copolymer.

[0083] he proportion of the charge transport substance to the binder resin (charge transport substance : binder resin) is preferably in the range of 2:1 to 1:2 (mass ratio).

[0084] Examples of the solvent used for the coating solution for a charge transport layer include ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate; ethers such as

dimethoxymethane and dimethoxyethane; aromatic

hydrocarbons such as toluene and xylene; and

hydrocarbons substituted by a halogen atom such as chlorobenzene, chloroform, and carbon tetrachloride.

[0085] From the viewpoint of charging uniformity and

reproductivity of an image, the film thickness of the charge transport layer is preferably not less than 3 μπι and not more than 40 μπι, and more preferably not less than 4 pm and not more than 30 μπι.

[0086] To the charge transport layer, an antioxidant, an

ultraviolet absorbing agent, and a plasticizer can be added when necessary.

[0087] In a case where the photosensitive layer is a single photosensitive layer, a coating solution for a single photosensitive layer containing a charge-generating substance, a charge transport substance, a binder resin, and a solvent can be applied and the obtained coating film is dried to form a single photosensitive layer.

As the charge-generating substance, the charge

transport substance, the binder resin, and the solvent, a variety of the materials described above can be used, for example.

[0088] On the photosensitive layer, a protective layer may be provided to protect the photosensitive layer.

[0089]A coating solution for a protective layer containing a resin (binder resin) can be applied and the obtained coating film is dried and/or cured to form a protective layer .

[0090] The film thickness of the protective layer is

preferably not less than 0.5 μπι and not more than 10 μπι, and more preferably not less than 1 μπι and not more than 8 μπι.

[0091] In application of the coating solutions for the

respective layers above, application methods such as a dip coating method (an immersion coating method) , a spray coating method, a spin coating method, a roll coating method, a Meyer bar coating method, and a blade coating method can be used.

[0092] Fig. 1 illustrates an example of a schematic

configuration of an electrophotographic apparatus including a process cartridge having an

electrophotographic photosensitive member.

[0093] In Fig. 1, a drum type (cylindrical)

electrophotographic photosensitive member 1 is rotated and driven around a shaft 2 in the arrow direction at a predetermined circumferential speed.

[0094] he surface (circumferential surface) of the

electrophotographic photosensitive member 1 rotated and driven is uniformly charged at a predetermined positive or negative potential by a charging unit (a primary charging unit, a charging roller, or the like) 3. Next, the circumferential surface of the electrophotographic photosensitive member 1 receives exposure light (image exposure light) 4 output from an exposing unit such as slit exposure or laser beam scanning exposure (not illustrated) . Thus, an electrostatic latent image corresponding to a target image is sequentially formed on the circumferential surface of the

electrophotographic photosensitive member 1. The voltage applied to the charging unit 3 may be only DC voltage, or DC voltage on which AC voltage is

superimposed.

[0095] The electrostatic latent image formed on the

circumferential surface of the electrophotographic photosensitive member 1 is developed by a toner of a developing unit 5 to form a toner image. Next, the toner image formed on the circumferential surface of the electrophotographic photosensitive member 1 is transferred onto a transfer material (such as paper) P by a transfer bias from a transferring unit (such as a transfer roller) 6. The transfer material P is fed from a transfer material feeding unit (not illustrated) between the electrophotographic photosensitive member 1 and the transferring unit 6 (contact region) in

synchronization with rotation of the

electrophotographic photosensitive member 1.

[0096] The transfer material P having the toner image

transferred is separated from the circumferential surface of the electrophotographic photosensitive member 1, and introduced to a fixing unit 8 to fix the image. Thereby, an image forming product (print, copy) is printed out of the apparatus.

[0097] From the circumferential surface of the

electrophotographic photosensitive member 1 after transfer of the toner image, the remaining toner of transfer is removed by a cleaning unit (such as a cleaning blade) 7. Further, the circumferential surface of the electrophotographic photosensitive member 1 is discharged by pre-exposure light 11 from a pre-exposing unit (not illustrated) , and is repeatedly used for image formation. In a case where the charging unit is a contact charging unit such as a charging roller, the pre-exposure is not always necessary.

[0098] he electrophotographic photosensitive member 1 and at least one component selected from the charging unit 3, the developing unit 5, the transferring unit 6, and the cleaning unit 7 may be accommodated in a container and integrally supported as a process cartridge, and the process cartridge may be detachably attached to the main body of the electrophotographic apparatus. In Fig. 1, the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, and the

cleaning unit 7 are integrally supported to form a process cartridge 9, which is detachably attached to the main body of the electrophotographic apparatus using a guide unit 10 such as a rail in the main body of the electrophotographic apparatus. The

electrophotographic apparatus may include the

electrophotographic photosensitive member 1, the

charging unit 3, the exposing unit, the developing unit 5, and the transferring unit 6.

Example

[0099] Hereinafter, using specific Examples, the present

invention will be described more in detail. However, the present invention will not be limited to these. In Examples and Comparative Examples, "parts" mean "parts by mass". In each of the particles in Examples and Comparative Examples, the particle diameter

distribution had one peak.

[ 0100 ] <Preparation Example of Coating Liquid for a conductive layer>

(Preparation Example of Coating Liquid for a conductive layer 1)

120 Parts of the titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with phosphorus (P) as the first metal oxide particle (powder resistivity: 5.0 ^χ 10 ² Ω-cm, average primary particle diameter: 0.20 μπι, powder resistivity of the core material particle

(rutile titanium oxide (Ti0 ₂ ) particle): 5.0 ^χ 10 ⁷ Ω-cm, average primary particle diameter of the core material particle (titanium oxide (Ti0 ₂ ) particle): 0.18 μπι, density: 5.1 g/cm ² ) , 7 parts of the uncoated titanium oxide (Ti0 ₂ ) particle as the second metal oxide

particle (rutile titanium oxide, powder resistivity: 5.0 x 10 ⁷ Ω-cm, average primary particle diameter: 0.20 μπι, density: 4.2 g/cm ² ), 168 parts of a phenol resin as the binder material (monomer/oligomer of the phenol resin) (trade name: Plyophen J-325, made by DIC

Corporation, resin solid content: 60%, density after curing: 1.3 g/cm ² ), and 98 parts of l-methoxy-2- propanol as a solvent were placed in a sand mill using 420 parts of glass beads having a diameter of 0.8 mm, and subjected to a dispersion treatment under the conditions of the number of rotation: 1500 rpm and the dispersion treatment time: 4 hours to obtain a

dispersion liquid.

[0101] he glass beads were removed from the dispersion liquid with a mesh.

[0102] 13.8 parts of a silicone resin particle as a surface roughening material (trade name: Tospearl 120, made by Momentive Performance Materials Inc., average particle diameter: 2 μπι, density: 1.3 g/cm ² ), 0.014 parts of a silicone oil as a leveling agent (trade name: SH28PA, made by Dow Corning Toray Co., Ltd.), 6 parts of methanol, and 6 parts of l-methoxy-2-propanol were added to the dispersion liquid from which the glass beads were removed, and stirred to prepare a coating liquid for a conductive layer 1. ] (Preparation Examples of coating liquids for conductive layer 2 to 78, CI to C47, and C54 to C71)

Coating liquids for a conductive layer 2 to 78, CI to C47, and C54 to C71 were prepared by the same operation as that in Preparation Example of the coating liquid for a conductive layer 1 except that the kinds, average primary particle diameters, and amounts (parts) of the first metal oxide particle and the second metal oxide particle used in preparation of the coating liquid for a conductive layer were changed as shown in Tables 1 to 7. Further, in preparation of the coating liquids for a conductive layer 18, 60, and 78, the conditions of the dispersion treatment were changed to the number of rotation: 2500 rpm and dispersion treatment time: 30 hours .

104]Table 1

Binder

Second metal oxide

material particle (Uncoated

First metal oxide particle

titanium oxide (B)

(phenol particle)

resin)

Coating

Amount solution for

[parts] conductive Average Average

(resin solid layer Powder primary primary

Amount Amount content is

Kind resistivity particle particle

[parts] [parts] 60% by [Ω-cm] diameter diameter

mass of [μιη] [μπι] amount below)

1 5.0xl0 ² 0.20 120 0.20 5 168

2 5.0xl0 ² 0.20 120 0.20 20 168

3 5.0xl0 ² 0.20 120 0.20 30 168

4 5.0xl0 ² 0.20 250 0.20 11 168

5 Titanium 5.0xl0 ² 0.20 250 0.20 18 168

6 oxide 5.0xl0 ² 0.20 450 0.20 37 168

7 particle 5.0xl0 ² 0.20 460 0.20 19 168

8 coated with 5.0xl0 ² 0.20 250 0.20 29 168 tin oxide

9 5.0xl0 ² 0.20 250 0.20 53 168 doped with

10 5.0xl0 ² 0.20 500 0.20 85 168 phosphorus

11 5.0xl0 ² 0.20 550 0.20 135 168

12 5.0xl0 ² 0.45 250 0.20 11 168

13 Density: 5.0xl0 ² 0.45 250 0.40 11 168

14 5.1 g/cm ² 5.0xl0 ² 0.15 250 0.15 11 168

15 5.0x l0 ² 0.15 250 0.10 11 168

16 2.0xl0 ² 0.20 250 0.20 18 168

17 1.5x l0 ³ 0.20 250 0.20 18 168

18 5.0x l0 ² 0.20 130 0.20 6 168

]Table 2

Table 3

„ _n Table 4

Binder

Second metal oxide

material particle (Uncoated

First metal oxide particle

titanium oxide (B)

(phenol particle)

resin)

Coating

Amount solution

[parts] for

Average Average (resin conductive

Powder primary primaiy solid layer Amount Amount

Kind resistivity particle particle content is

[parts] [parts]

[Ω-cm] diameter diameter 60% by

[ πι] [μιη] mass of amount below)

61 5.0x l0 ² 0.20 120 0.20 5 168

62 5.0xl0 ² 0.20 120 0.20 20 168

63 5.0x l0 ² 0.20 120 0.20 30 168

64 Titanium 5.0xl0 ² 0.20 250 0.20 11 168

65 oxide 5.0x l0 ² 0.20 250 0.20 18 168

66 particle 5.0xl0 ² 0.20 450 0.20 37 168

67 coated 5.0x l0 ² 0.20 460 0.20 19 168

68 with tin 5.0xl0 ² 0.20 250 0.20 29 168 oxide

69 5.0xl0 ² 0.20 250 0.20 53 168 doped

70 5.0xl0 ² 0.20 500 0.20 85 168 with

71 tantalum 5.0xl0 ² 0.20 500 0.20 120 168

72 5.0xl0 ² 0.45 250 0.20 11 168

73 5.0xl0 ² 0.45 250 0.40 11 168

74 Density: 5.0xl0 ² 0.15 250 0.15 11 168

75 5.2 g/cm ² 5.0xl0 ² 0.15 250 0.10 1 1 168

76 2.0xl0 ² 0.20 250 0.20 18 168

77 1.5x l0 ³ 0.20 250 0.20 18 168

78 5.0xl0 ² 0.20 130 0.20 6 168

„„ Table 5

„ Table 6

„„

[0110]Table 7

[0111] he "titanium oxide particle coated with tin oxide doped with antimony" and "titanium oxide particle coated with oxygen-defective tin oxide" in the coating liquids for a conductive layer C28 to C47 are not the first metal oxide particle according to the present invention. For comparison with the present invention, however, these particles are used as the first metal oxide particle for convenience. The same is true below.

[0112] (Preparation Example of coating liquid for conductive layer C48)

A coating liquid for a conductive layer was prepared by the same operation as the operation to prepare a

coating liquid for a conductive layer L-4 which is described in Patent Literature 1. This coating liquid was used as a coating liquid for a conductive layer C48.

[0113] Namely, 54.8 parts of a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with phosphorus (P) (average primary particle diameter: 0.15 μπι, powder resistivity: 2.0 ^χ 10 ² Ω-cm, coating percentage with tin oxide (Sn0 ₂ ) : 15% by mass, amount of phosphorus (P) used to dope tin oxide (Sn0 ₂ ) (amount of dope) :7% by mass) , 36.5 parts of a phenol resin as a binding resin (trade name: Plyophen J-325, made by DIC Corporation, resin solid content: 60% by mass), and 50 parts of methoxypropanol as a solvent ( l-methoxy-2-propanol ) were placed in a sand mill using glass beads having a diameter of 0.5 mm, and subjected to a dispersion treatment under the dispersion treatment conditions of the number of rotation of the disk: 2500 rpm and the dispersion treatment time: 3.5 hours to obtain a

dispersion liquid.

[0114] 3.9 Parts of a silicone resin particle as a surface

roughening material (trade name: Tospearl 120, made by Momentive Performance Materials Japan LLC, average particle diameter: 2 μηι) , and 0.001 parts of a silicone oil as a leveling agent (trade name: SH28PA, made by Dow Corning Toray Co., Ltd.) were added to this

dispersion liquid, and stirred to prepare the coating liquid for a conductive layer C48.

[0115] (Preparation Example of coating liquid for conductive layer C49) A coating liquid for a conductive layer was prepared by the same operation as the operation to prepare the coating liquid for a conductive layer L-14 which is described in Patent Literature 1. This coating liquid was used as a coating liquid for a conductive layer C49.

[0116] amely, 37.5 parts of a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with tungsten (W) (average primary particle diameter: 0.15 μπι, powder resistivity: 2.5 ^χ 10 ² Ω-cm, coating percentage with tin oxide (Sn0 ₂ ) : 15% by mass, amount of tungsten (W) used to dope tin oxide (Sn0 ₂ ) (amount of dope) : 7% by mass), 36.5 parts of a phenol resin as a binding resin (trade name: Plyophen J-325, made by DIC Corporation, resin solid content: 60% by mass), and 50 parts of methoxypropanol as a solvent (l-methoxy-2-propanol) were placed in a sand mill using glass beads having a diameter of 0.5 mm, and subjected to a dispersion treatment under the dispersion treatment conditions of the number of rotation of the disk: 2500 rpm and

dispersion treatment time: 3.5 hours to obtain a

dispersion liquid.

[0117] 3.9 Parts of a silicone resin particle as a surface

roughening material (trade name: Tospearl 120, made by Momentive Performance Materials Japan LLC, average particle diameter: 2 μπι) , and 0.001 parts of a silicone oil as a leveling agent (trade name: SH28PA, made by Dow Corning Toray Co., Ltd.) were added to the

dispersion liquid, and stirred to prepare the coating liquid for a conductive layer C49.

[0118] (Preparation Example of coating liquid for conductive layer C50)

A coating liquid for a conductive layer was prepared by the same operation as the operation to prepare the coating liquid for a conductive layer L-30 which is described in Patent Literature 1. This coating liquid was used as a coating liquid for a conductive layer C50. [0119] Namely, 60 parts of a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (SnC>2) doped with fluorine (F) (average primary particle diameter: 0.075 μπι, powder resistivity: 3.0 ^χ 10 ² Ω-cm, coating percentage with tin oxide (Sn02) : 15% by mass, amount of fluorine (F) used to dope tin oxide (Sn0 ₂ ) (amount of dope) : 7% by mass), 36.5 parts of a phenol resin as a biding resin (trade name: Plyophen J-325, made by DIC Corporation, resin solid content: 60% by mass), and 50 parts of methoxypropanol as a solvent (l-methoxy-2-propanol) were placed in a sand mill using glass beads having a diameter of 0.5 mm, and subjected to a dispersion treatment under the dispersion treatment conditions of the number of rotation of the disk: 2500 rpm and the dispersion treatment time: 3.5 hours to obtain a

dispersion liquid.

[0120] 3. Parts of a silicone resin particle as a surface

roughening material (trade name: Tospearl 120, made by Momentive Performance Materials Japan LLC, average particle diameter: 2 μπι) , and 0.001 parts of a silicone oil as a leveling agent (trade name: SH28PA, made by Dow Corning Toray Co., Ltd.) were added to the

dispersion liquid, and stirred to prepare a coating liquid for a conductive layer C50.

[0121] (Preparation Example of coating liquid for a conductive layer C51)

A coating liquid for a conductive layer was prepared by the same operation as the operation to prepare the coating liquid for a conductive layer 1 which is

described in Patent Literature 2. This coating liquid was used as a coating liquid for a conductive layer C51.

[ 0122 ] amely, 204 parts of a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with phosphorus (P) (powder resistivity: 4.0 ^χ 10 ¹ Ω-cm, coating percentage with tin oxide (Sn0 ₂ ) : 35% by mass, amount of

phosphorus (P) used to dope tin oxide (Sn0 ₂ ) (amount of dope) : 3% by mass) , 148 parts of a phenol resin as a biding resin (monomer/oligomer of the phenol resin) (trade name: Plyophen J-325, made by DIC Corporation, resin solid content: 60% by mass), and 98 parts of 1- methoxy-2-propanol as a solvent were placed in a sand mill using 450 parts of glass beads having a diameter of 0.8 mm, and subjected to a dispersion treatment under the dispersion treatment conditions of the number of rotation: 2000 rpm, dispersion treatment time: 4 hours, and setting temperature of the cooling water:

18 °C to obtain a dispersion liquid.

[0123]After the glass beads were removed from the dispersion liquid with a mesh, 13.8 parts of a silicone resin particle as a surface roughening material (trade name: Tospearl 120, made by Momentive Performance Materials Japan LLC, average particle diameter: 2 μπι) , 0.014 parts of a silicone oil as a leveling agent (trade name: SH28PA, made by Dow Corning Toray Co., Ltd.), 6 parts of methanol, and 6 parts of l-methoxy-2-propanol were added to the dispersion liquid, and stirred to prepare a coating liquid for a conductive layer C51.

[ 0124 ] Preparation Example of coating liquid for conductive

layer C52)

A coating liquid for a conductive layer was prepared by the same operation as the operation to prepare the coating liquid for a conductive layer 10 which is described in Patent Literature 2. This coating liquid was used as a coating liquid for a conductive layer C52.

[ 0125 ] amely, 204 parts of a titanium oxide (Ti0 ₂ ) particle coated with tin oxide (Sn0 ₂ ) doped with tungsten ( ) (powder resistivity: 2.5 ^χ 10 ¹ Ω-cm, coating percentage with tin oxide (Sn0 ₂ ) : 33% by mass, amount of tungsten (W) used to dope tin oxide (Sn0 ₂ ) (amount of dope) : 3% by mass) , 148 parts of a phenol resin as a biding resin (monomer/oligomer of the phenol resin) (trade name:

Plyophen J-325, made by DIC Corporation, resin solid content: 60% by mass), and 98 parts of l-methoxy-2- propanol as a solvent were placed in a sand mill using 450 parts of glass beads having a diameter of 0.8 mm, and subjected to a dispersion treatment under the dispersion treatment conditions of the number of rotation: 2000 rpm, dispersion treatment time: 4 hours, and setting temperature of cooling water: 18 °C to obtain a dispersion liquid.

[0126]After the glass beads were removed from the dispersion liquid with a mesh, 13.8 parts of a silicone resin particle as a surface roughening material (trade name: Tospearl 120, made by Momentive Performance Materials Japan LLC, average particle diameter: 2 μπι) , 0.014 parts of a silicone oil as a leveling agent (trade name: SH28PA, made by Dow Corning Toray Co., Ltd.), 6 parts of methanol, and 6 parts of l-methoxy-2-propanol were added to the dispersion liquid, and stirred to prepare a coating liquid for a conductive layer C52.

[0127] (Preparation Example of coating liquid for conductive layer C53)

A coating liquid for a conductive layer was prepared by the same operation as the operation to prepare the coating liquid for a conductive layer which is

described in Example 2 in Japanese Patent Application Laid-Open No. 2008-026482. This coating liquid was used as a coating liquid for a conductive layer C53.

[0128] Namely, 8.08 parts of a titanium oxide (Ti0 ₂ ) particle coated with oxygen-defective tin oxide (SnC^) (powder resistivity: 9.7 ^χ 10 ² Ω-cm, coating percentage with tin oxide (SnC>2) : 31% by mass), 2.02 parts of a

titanium oxide (Ti0 ₂ ) particle not subjected to a conductive treatment (average primary particle

diameter: 0.60 μπι) , 1.80 parts of a phenol resin as a biding resin (trade name: J-325, made by DIC

Corporation, resin solid content 60%), and 10.32 parts of methoxypropanol as a solvent (l-methoxy-2-propanol) were placed in a sand mill using glass beads having a diameter of 1 mm, and subjected to a dispersion

treatment under the dispersion treatment condition of the dispersion treatment time: 3 hours to obtain a dispersion liquid.

[0129] 0.5 Parts of as silicone resin particle as a surface roughening material (trade name: Tospearl 120, made by Momentive Performance Materials Japan LLC, average particle diameter: 2 μπι) , and 0.001 parts of a silicone oil as a leveling agent (trade name: SH28PA, made by Dow Corning Toray Co., Ltd.) were added to the

dispersion liquid, and stirred to prepare a coating liquid for a conductive layer C53.

[0130] <Production Examples of Electrophotographic

Photosensitive Member>

(Production Example of Electrophotographic

Photosensitive Member 1)

A support was an aluminum cylinder having a length of 257 mm and a diameter of 24 mm and produced by a production method including extrusion and drawing (JIS- A3003, aluminum alloy) .

[0131] Under an environment of normal temperature and normal humidity (23°C/50%RH) , the coating liquid for a

conductive layer 1 was applied onto the support by dip coating, and the obtained coating film is dried and thermally cured for 30 minutes at 140°C to form a conductive layer having a film thickness of 30 μπι.

[0132] he volume resistivity of the conductive layer was

measured by the method described above, and it was 1.8 x 10 ¹² Ω-cm.

[0133] ext, 4.5 parts of N-methoxymethylated nylon (trade name: TORESIN EF-30T, made by Nagase ChemteX

Corporation) and 1.5 parts of a copolymerized nylon resin (trade name: AMILAN CM8000, made by Toray

Industries, Inc.) were dissolved in a mixed solvent of 65 parts of methanol/30 parts of n-butanol to prepare a coating solution for an undercoat layer. The coating solution for an undercoat layer was applied onto the conductive layer by dip coating, and the obtained coating film is dried for 6 minutes at 70 °C to form an undercoat layer having a film thickness of 0.85 μπι.

[0134]Next, 10 parts of crystalline hydroxy gallium

phthalocyanine crystals (charge-generating substance) having strong peaks at Bragg angles (2Θ ± 0.2°) of 7.5°, 9.9°, 16.3°, 18.6°, 25.1°, and 28.3° in CuK properties X ray diffraction, 5 parts of polyvinyl butyral (trade name: S-LECBX-1, made by Sekisui Chemical Co., Ltd.), and 250 parts of cyclohexanone were placed in a sand mill using glass beads having a diameter of 0.8 mm.

The solution was dispersed under a condition:

dispersing time, 3 hours. Next, 250 parts of ethyl acetate was added to the solution to prepare a coating solution for a charge-generating layer. The coating solution for a charge-generating layer was applied onto the undercoat layer by dip coating, and the obtained coating film is dried for 10 minutes at 100 °C to form a charge-generating layer having a film thickness of 0.15 μπι.

[0135] Next, 6.0 parts of an amine compound represented by the following formula (CT-1) (charge transport substance) ,

[0136] 2.0 parts of an amine compound represented by the

following formula (CT-2) (charge transport substance), 10 parts of bisphenol Z type polycarbonate (trade name: Z400, made by Mitsubishi Engineering-Plastics

Corporation), and 0.36 parts of siloxane modified polycarbonate having the repeating structure unit represented by the following formula (B-l) ((B-l):(B-2) = 95:5 (molar ratio)), the repeating structure unit represented by the following formula (B-2), and the terminal structure represented by the following formula

were dissolved in a mixed solvent of 60 parts of o- xylene/40 parts of dimethoxymethane/2.7 parts of methyl benzoate to prepare a coating solution for a charge transport layer. The coating solution for a charge transport layer was applied onto a charge-generating layer by dipping, and the obtained coating film was dried for 30 minutes at 125 °C. Thereby, a charge transport layer having a film thickness of 10.0 μπι was formed .

[0138] hus, an electrophotographic photosensitive member 1 in which the charge transport layer was the surface layer was produced.

[0139] (Production Examples of electrophotographic

photosensitive members 2 to 78 and CI to C71)

Electrophotographic photosensitive members 2 to 78 and CI to C71 in which the charge transport layer was the surface layer were produced by the same operation as that in Production Example of the electrophotographic photosensitive member 1 except that the coating liquid for a conductive layer used in production of the electrophotographic photosensitive member was changed from the coating liquid for a conductive layer 1 to each of the coating liquids for a conductive layer 2 to 78 and CI to C71. The volume resistivity of the conductive layer was measured in the same manner as in the case of the electrophotographic photosensitive member 1. The results are shown in Tables 8 to 14.

[0140] In the electrophotographic photosensitive members 1 to 78 and CI to C71, two electrophotographic

photosensitive members were produced: one for the conductive layer analysis and the other for the sheet feeding durability test.

[0141] (Production Examples of electrophotographic

photosensitive members 101 to 178 and ClOl to C171) As the electrophotographic photosensitive member for the probe pressure resistance test, electrophotographic photosensitive members 101 to 178 and ClOl to C171 in which the charge transport layer was the surface layer were produced by the same operation as that in

Production Examples of electrophotographic

photosensitive members 1 to 78 and CI to C71 except that the film thickness of the charge transport layer was 5.0 μπι. [0142] (Examples 1 to 78 and Comparative Examples 1 to 71) <Analysis of conductive layer in electrophotographic photosensitive member>

Five pieces of a 5 mm square were cut from each of the electrophotographic photosensitive members 1 to 78 and CI to C71 for the conductive layer analysis.

Subsequently, the charge transport layers and charge- generating layers on the respective pieces were removed with chlorobenzene, methyl ethyl ketone, and methanol to expose the conductive layer. Thus, five sample pieces for observation were prepared for each of the electrophotographic photosensitive members.

[0143] First, for each of the electrophotographic

photosensitive members, using one sample piece and a focused ion beam processing observation apparatus

(trade name: FB-2000A, made by Hitachi High-Tech

Manufacturing & Service Corporation) , the conductive layer was sliced into a thickness: 150 nm according to an FIB-μ sampling method. Using a field emission electron microscope (HRTEM) (trade name: JEM-2100F, made by JEOL, Ltd. ) and an energy dispersive X-ray spectrometer (EDX) (trade name: JED-2300T, made by JEOL, Ltd.), the conductive layer was subjected to the

composition analysis. The measurement conditions of the EDX are an accelerating voltage: 200 kV and a beam diameter: 1.0 nm.

[0144]As a result, it was found that the conductive layers in the electrophotographic photosensitive members 1 to 18, CI to C9, C48 and C51 contained the titanium oxide particle coated with tin oxide doped with phosphorus . It was also found that the conductive layers in the electrophotographic photosensitive members 19 to 30, CIO to C18, C49 and C52 contained the titanium oxide particle coated with tin oxide doped with tungsten. It was also found that the conductive layers in the

electrophotographic photosensitive members 31 to 42, C19 to C27 and C50 contained the titanium oxide particle coated with tin oxide doped with fluorine. It was also found that the conductive layers in the

electrophotographic photosensitive members C28 to C37 contained the titanium oxide particle coated with tin oxide doped with antimony. It was also found that the conductive layers in the electrophotographic

photosensitive members C38 to C47 and C53 contained the titanium oxide particle coated with tin oxide. It was also found that the electrophotographic photosensitive members 43 to 60 and C54 to 62 contained the titanium oxide particle coated with tin oxide doped with niobium. It was also found that the electrophotographic

photosensitive members 61 to 78 and C63 to 71 contained the titanium oxide particle coated with tin oxide doped with niobium. It was also found that the conductive layers in all of the electrophotographic photosensitive members except the electrophotographic photosensitive members C3, C12, C21, C56, C65 and C48 to C53 contained the uncoated titanium oxide particle.

[0145] Next,, for each of the electrophotographic

photosensitive members, using the remaining four sample pieces, the conductive layer was formed into a three- dimensional image of 2 μπι 2 μπι ^χ 2 μπι by the FIB-SEM Slice & View.

[0146] From the difference in contrast in the FIB-SEM Slice & View, tin oxide and titanium oxide doped with

phosphorus can be identified, and the volume of the titanium oxide particle coated with P-doped tin oxide, the volume of the P-doped tin oxide particle, and the ratio thereof in the conductive layer can be determined. When the kind of elements used to dope tin oxide is other than phosphorus, for example, tungsten, fluorine, niobium, and tantalum, the volumes and the ratio

thereof in the conductive layer can be determined in the same manner. [0147] he conditions of the Slice & View in the present invention were as follows .

processing of the sample for analysis: FIB method processing and observation apparatus: made by Sll/Zeiss, NVision 40

slice interval: 10 nm

observation condition:

accelerating voltage: 1.0 kV

inclination of the sample: 54°

WD: 5 mm

detector: BSE detector

aperture: 60 μπι, high current

ABC: ON

resolution of the image: 1.25 nm/pixel

[0148] he analysis is performed on the area measuring 2 ym ^χ

2 μιη. The information for every cross section is integrated to determine the volumes Vx and V2 per 2 μπι ^χ 2 μιη ^χ 2 μπι (V _T = 8 μιη ³ ) . The measurement environment is the temperature: 23 °C and the pressure: 1 ^χ 10 ^~4 Pa.

[0149] For the processing and observation apparatus, Strata

400S made by FEI Company (inclination of the sample:

52°) can also be used.

[0150] The information for every cross section was obtained by analyzing the images of the areas of identified tin oxide doped with phosphorus and titanium oxide. The image was analyzed using the following image processing software .

image processing software: made by Media Cybernetics, Inc., Image-Pro Plus

[0151] Based on the obtained information, for the four sample pieces, the volume of the first metal oxide particle

(Vi [μπι ³ ] ) and the volume of the second metal oxide particle (uncoated titanium oxide particle) (V ₂ [μπι ³ ] ) in the volume of 2 μπι ^χ 2 μπι ^χ 2 μπι (unit volume: 8 μπι ³ ) were obtained. Then, (Vi [μπι ³ ] /8 [μπι ³ ] ) 100, (V ₂ [μπι ³ ]/8 [μπι ³ ] ) ^χ 100, and (V ₂ [μπι ³ ] /V [μπι ³ ] ) ^χ 100 were calculated. The average value of the values of (Vi

[μπι ³ ] / 8 [μιη ³ ] ) ^χ 100 in the four sample pieces was defined as the content [% by volume] of the first metal oxide particle in the conductive layer based on the total volume of the conductive layer. The average value of the values of (V ₂ [μπι ³ ] / 8 [μπι ³ ] ) ^χ 100 in the four sample pieces was defined as the content [% by volume] of the second metal oxide particle in the conductive layer based on the total volume of the conductive layer. The average value of the values of (V ₂ [μπι ³ ] /Vi [μπι ³ ] ) ^χ 100 in the four sample pieces was defined as the content [% by volume] of the second metal oxide particle in the conductive layer based on the content of the first metal oxide particle in the conductive layer.

[ 0152 ] In the four sample pieces, the average primary particle diameter of the first metal oxide particle and the average primary particle diameter of the second metal oxide particle (uncoated titanium oxide particle) were determined as described above. The average value of the average primary particle diameters of the first metal oxide particle in the four sample pieces was defined as the average primary particle diameter ( Di ) of the first metal oxide particle in the conductive layer. The average value of the average primary particle diameters of the second metal oxide particle in the four sample pieces was defined as the average primary particle diameter (D ₂ ) of the second metal oxide particle in the conductive layer.

[ 0153 ] The results are shown in Tables 8 to 14 . [0154]Table 8

Content [%

by volume]

Content [%

Content [% of the

by volume]

by volume] second Average

of the Average

of the first metal primary

second primary

metal oxide particle

metal particle

oxide particle in diameter

oxide diameter Volume particle in the (D ₂ ) of the

Coating Electrophoto particle in (Di) of the resistivity the conductive second

solution for graphic the first metal of the

Example conductive layer metal Di/D ₂

conductive photosensitiv conductive oxide conductive layer based on oxide

layer e member layer particle in layer based on the content particle in

based on the [Ω-cm] the total of the first the

the total conductive

volume of metal conductive

volume of layer

the oxide layer

the

conductive particle in [μΓη]

[μηπ]

conductive

layer the

layer

conductive

layer

1 1 1 21 1.1 5.1 0.20 0.20 1.0 1.8x1012

2 2 2 20 4.1 20 0.20 0.20 1.0 2.0x10 ¹²

3 3 3 20 5.9 30 0.20 0.20 1.0 2.5x1012

4 4 4 35 1.8 5.1 0.20 0.20 1.0 5.0x1010

5 5 5 35 3.0 8.7 0.20 0.20 1.0 5.0x1010

6 6 6 48 4.8 10 0.20 0.20 1.0 4.5x108

7 7 7 49 2.5 5.0 0.20 0.20 1.0 4.5x10 ⁸

8 8 8 34 4.9 14 0.20 0.20 1.0 1.0x1011

9 9 9 33 8.4 26 0.20 0.20 1.0 5.8x1011

10 10 10 47 9.8 21 0.20 0.20 1.0 5.0x108

11 11 11 46 14.1 30 0.20 0.20 1.0 7.0x108

12 12 12 35 1.8 5.1 0.45 0.20 2.3 5.0x1010

13 13 13 35 1.8 5.1 0.45 0.40 1.1 5.0x1010

14 14 14 35 1.8 5.1 0.15 0.15 1.0 5.0x1010

15 15 15 35 1.8 5.1 0.15 0.10 1.5 5.0x1010

16 16 16 35 3.0 8.6 0.20 0.20 1.0 3.2x109

17 17 17 35 3.0 8.6 0.20 0.20 1.0 2.2x1011

18 18 18 20 3.5 17 0.20 0.18 1.0 2.0x1011 [0155]Table 9

Content [%

by volume]

Content [%

Content [% of the

by volume]

by volume] second Average

of the Average

of the first metal primary

second primary

metal oxide particle

metal particle

oxide particle in diameter

oxide diameter Volume particle in the (D ₂ ) of the

Coating Electrophoto particle in (Di) of the resistivity the conductive second

solution for graphic the first metal of the

Example conductive layer metal Di/D ₂

conductive photosensitiv conductive oxide conductive layer based on oxide

layer e member layer particle in layer based on the content particle in

based on the [Ω-cm] the total of the first the

the total conductive

volume of metal conductive

volume of layer

the oxide layer

the

conductive particle in [μηι]

[μτη]

conductive

layer the

layer

conductive

layer

19 19 19 20 1.5 7.5 0.20 0.20 1.0 1.8x10 ¹²

20 20 20 35 1.8 5.1 0.20 0.20 1.0 5.0x101°

21 21 21 34 2.9 8.6 0.20 0.20 1.0 5.0x1010

22 22 22 50 5.0 10 0.20 0.20 1.0 4.7x108

23 23 23 34 5.0 15 0.20 0.20 1.0 1.8x10 ¹¹

24 24 24 32 8.0 25 0.20 0.20 1.0 5.6x10"

25 25 25 47 9.4 20 0.20 0.20 1.0 5.0x10 ^s

26 26 26 45 13 30 0.20 0.20 1.0 7.0x108

27 27 27 35 3.0 8.6 0.45 0.20 2.3 5.0x10 ¹⁰

28 28 28 35 3.0 8.6 0.45 0.40 1.1 5.0x101"

29 29 29 35 3.0 8.6 0.15 0.15 1.0 5.0x10 ¹⁰

30 30 30 35 3.0 8.6 0.15 0.10 1.5 5.0x10 ¹ o

31 31 31 20 1.5 7.5 0.20 0.20 1.0 2.0x10 ¹²

32 32 32 35 1.8 5.1 0.20 0.20 1.0 5.5x10 ¹⁰

33 33 33 34 2.9 8.6 0.20 0.20 1.0 5.5x1010

34 34 34 50 5.0 10 0.20 0.20 1.0 5.3x10 ⁸

35 35 35 34 4.8 14 0.20 0.20 · 1.0 2.2x1011

36 36 36 32 8.3 26 0.20 0.20 1.0 6.5x1011

37 37 37 48 9.7 20 0.20 0.20 1.0 5.5x108

38 38 38 46 13.7 30 0.20 0.20 1.0 7.8x10 ^s

39 39 39 34 3.1 8.9 0.45 0.20 2.3 5.5x101°

40 40 40 34 3.1 8.9 0.45 0.40 1.1 5.5x1010

41 41 41 34 3.1 8.9 0.15 0.15 1.0 5.5x101°

42 42 42 34 3.1 8.9 0.15 0.10 1.5 5.5x1010 . ^

[0156]Table 10

Content [%

by volume]

Content [%

Content [% of the

by volume]

by volume] second Average

of the Average

of the first metal primary

second primary

metal oxide particle

metal particle

oxide particle in diameter

oxide diameter Volume particle in the (D ₂ ) of the

Coating Electrophoto particle in (DO of the resistivity the conductive second

solution for graphic the first metal of the

Example conductive layer metal Di/D ₂

conductive photosensitiv conductive oxide conductive layer based on oxide

layer e member layer particle in layer based on the content particle in

based on the [Ω-cm] the total of the first the

the total conductive

volume of metal conductive

volume of layer

the oxide layer

the

conductive particle in

conductive [μΓη]

layer the

layer

conductive

layer

43 43 43 21 1.1 5.1 0.20 0.20 1.0 1.8x1012

44 44 44 20 4.1 20 0.20 0.20 1.0 2.0x1012

45 45 45 20 5.9 30 0.20 0.20 1.0 2.5x1012

46 46 46 35 1.8 5.1 0.20 0.20 1.0 5.0x10 ¹⁰

47 47 47 35 3.0 8.7 0.20 0.20 1.0 5.0x101"

48 48 48 48 4.8 10 0.20 0.20 1.0 4.5x10 ⁸

49 49 49 49 2.5 5.0 0.20 0.20 1.0 4.5x10 ⁸

50 50 50 34 4.9 14 0.20 0.20 1.0 1.0x1011

51 51 51 33 8.4 26 0.20 0.20 1.0 5.8x1011

52 52 52 47 9.8 21 0.20 0.20 1.0 5.0x108

53 53 53 46 13 29 0.20 0.20 1.0 7.0x108

54 5 54 35 1.8 5.1 0.45 0.20 2.3 5.0x1010

55 55 55 35 1.8 5.1 0.45 0.40 1.1 5.0x1010

56 56 56 35 1.8 5.1 0.15 0.15 1.0 5.0x1010

57 57 57 35 1.8 5.1 0.15 0.10 1.5 5.0x101"

58 58 58 35 3.0 8.6 0.20 0.20 1.0 3.2x109

59 59 59 35 3.0 8.6 0.20 0.20 1.0 2.2x1011

60 60 60 20 3.5 17 0.20 0.20 1.0 2.0x1011

_.„

[0157]Table 11

Content [%

by volume]

Content [%

Content [% of the

by volume]

by volume] second Average

of the Average

of the first metal primary

second primary

metal oxide particle

metal particle

oxide particle in diameter

oxide diameter Volume particle in the (D ₂ ) of the

Coating Electrophoto particle in (Di) of the resistivity the conductive second

solution for graphic the first metal of the

Example conductive layer metal Di/D ₂

conductive photosensitiv conductive oxide conductive layer based on oxide

layer e member layer particle in layer based on the content particle in

based on the [Ω-cm] the total of the first the

the total conductive

volume of metal conductive

volume of layer

the oxide layer

the

conductive particle in [μηη]

conductive [μηι]

layer the

layer

conductive

layer

61 61 61 21 1.1 5.2 0.20 0.20 1.0 1.8x1012

62 62 62 20 4.1 21 0.20 0.20 1.0 2.0x10 ¹²

63 63 63 20 5.9 30 0.20 0.20 1.0 2.5x1012

64 64 64 35 1.8 5.1 0.20 0.20 1.0 5.0x10 ¹⁰

65 65 65 34 3.0 8.9 0.20 0.20 1.0 5.0x1010

66 66 66 48 4.8 10 0.20 0.20 1.0 4.5x10 ^s

67 67 67 49 2.4 5.0 0.20 0.20 1.0 4.5x108

68 68 68 34 4.8 14 0.20 0.20 1.0 1.0x1011

69 69 69 32 8.3 26 0.20 0.20 1.0 5.8x1011

70 70 70 47 10 21 0.20 0.20 1.0 5.0x10 ⁸

71 71 71 45 13 30 0.20 0.20 1.0 7.0x10»

72 72 72 35 1.8 5.1 0.45 0.20 2.3 5.0x1010

73 73 73 35 1.8 5.1 0.45 0.40 1.1 5.0x1010

74 74 74 35 1.8 5.1 0.15 0.15 1.0 5.0x101»

75 75 75 35 1.8 5.1 0.15 0.10 1.5 5.0x1010

76 76 76 34 2.9 8.6 0.20 0.20 1.0 3.2x109

77 77 77 34 2.9 8.6 0.20 0.20 1.0 2.2x10»

78 78 78 20 3.5 17 0.20 0.20 1.0 2.0x10»

[0158]Table 12

Content [%

by volume]

Content [%

Content [% of the

by volume]

by volume] second Average

of the Average

of the first metal primary

second primary

metal oxide particle

metal particle

oxide particle in diameter

oxide diameter Volume particle in the (D ₂ ) of the

Coating Electrophoto particle in (Di) of the resistivity the conductive second

solution for graphic the first metal of the

Example conductive layer metal Di/D ₂

conductive photosensitiv conductive oxide conductive layer based on oxide

layer e member layer particle in layer based on the content particle in

based on the [Ω-cm] the total of the first the

the total conductive

volume of metal conductive

volume of layer

the oxide layer

the

conductive particle in [μηη]

conductive [μΓη]

layer the

layer

conductive

layer

1 C1 C1 15 1.5 10 0.20 0.20 1.0 5.0x10^2

2 C2 C2 54 4.9 9.1 0.20 0.20 1.0 2.2x108

3 C3 C3 35 - - 0.20 - - 5.0x101°

4 C4 C4 35 0.5 1.4 0.20 0.20 1.0 5.0x10 ¹⁰

5 C5 C5 50 0.5 1.0 0.20 0.20 1.0 4.5x10 ⁸

6 C6 C6 32 20 62 0.20 0.20 1.0 6.7x1010

7 C7 C7 40 20 50 0.20 0.20 1.0 5.8x10 ⁸

8 C8 C8 34 1.5 4.3 0.20 0.20 1.0 5.0x1010

9 C9 C9 31 11 34 0.20 0.20 1.0 6.0x1010

10 C10 C10 15 1.5 10 0.20 0.20 1.0 5.0x1012

11 C11 C11 54 5.0 9.3 0.20 0.20 1.0 2.2x108

12 C12 C12 35 - - 0.20 - - 5.0x1010

13 C13 C13 35 0.5 1.4 0.20 0.20 1.0 5.0x1010

14 C14 C14 50 0.5 1.0 0.20 0.20 1.0 4.5x108

15 C15 C15 32 20 64 0.20 0.20 1.0 6.7x1010

16 C16 C16 40 20 50 0.20 0.20 1.0 5.8x108

17 C17 C17 35 1.0 2.9 0.20 0.20 1.0 5.0x1010

18 C18 C18 31 11 34 0.20 0.20 1.0 6.0x1010

19 C19 C19 15 1.5 10 0.20 0.20 1.0 6.0x1012

20 C20 C20 55 5.0 9.1 0.20 0.20 1.0 2.5x108

21 C21 C21 35 - - 0.20 - - 5.5x1010

22 C22 C22 35 0.5 1.4 0.20 0.20 1.0 5.5x101°

23 C23 C23 50 0.5 1.0 0.20 0.20 1.0 4.8x108

24 C24 C24 31 22 71 0.20 0.20 1.0 7.3x101°

25 C25 C25 40 20 50 0.20 0.20 1.0 6.2x108

26 C26 C26 35 1.0 2.9 0.20 0.20 1.0 5.5x101°

27 C27 C27 31 11 34 0.20 0.20 1.0 6.5x1010 „

[0159]Table 13

Content [%

by volume]

Content [%

Content [% of the

by volume]

by volume] second Average

of the Average

of the first metal primary

second primary

metal oxide particle

metal particle

oxide particle in diameter

oxide diameter Volume particle in the (D ₂ ) of the

Coating Electrophoto particle in (Di) of the resistivity the conductive second

solution for graphic the first metal of the

Example conductive layer metal Di/D ₂

conductive photosensitiv conductive oxide conductive layer based on oxide

layer e member layer particle in layer based on the content particle in

based on the [Ω-cm] the total of the first the

the total conductive

volume of metal conductive

volume of layer

the oxide layer

the

conductive particle in [μΓη]

conductive [μΓη]

layer the

layer

conductive

layer

28 C28 C28 20 1.5 7.5 0.20 0.20 1.0 1.8x1012

29 C29 C29 34 1.8 5.1 0.20 0.20 1.0 5.0x101"

30 C30 C30 34 2.9 8.6 0.20 0.20 1.0 5.0x10 o

^' 31 C31 C31 48 4.8 10 0.20 0.20 1.0 4.5x10 ⁸

32 C32 C32 35 5.0 14 0.20 0.20 1.0 1.0x1011

33 C33 C33 33 8.6 26 0.20 0.20 1.0 5.8x1011

34 C34 C34 47 9.8 21 0.20 0.20 1.0 5.0x10 ⁸

35 C35 C35 46 13 29 0.20 0.20 1.0 7.0x108

36 C36 C36 35 3.0 8.6 0.45 0.40 1.1 5.0x1010

37 C37 C37 35 3.0 8.6 0.15 0.15 1.0 5.0x10 ¹ o

38 C38 C38 20 1.5 7.5 0.20 0.20 1.0 1.8x1012

39 C39 C39 34 1.8 5.1 0.20 0.20 1.0 5.0x1010

40 C40 C40 34 2.9 8.6 0.20 0.20 1.0 5.0x101»

41 C41 C41 48 4.8 10 0.20 0.20 1.0 4.5x10 ⁸

42 C42 C42 35 5.0 14 0.20 0.20 1.0 1.0x1011

43 C43 C43 33 8.6 26 0.20 0.20 1.0 5.8x1011

44 C44 C44 48 9.5 20 0.20 0.20 1.0 5.0x10 ⁸

45 C45 C45 46 13 29 0.20 0.20 1.0 7.0x10 ⁸

46 C46 C46 35 3.0 8.6 0.45 0.40 1.1 5.0x101»

47 C47 C47 35 3.0 8.6 0.15 0.15 1.0 5.0x101°

48 C48 C48 35 - - 0.15 - - 3.5x1010

49 C49 C49 29 - - 0.15 - - 2.0x1013

50 C50 C50 37 - - 0.08 - - 3.5x101°

51 C51 C51 32 - - 0.35 - - 2.1 x109

52 C52 C52 32 - - 0.38 - - 4.0x109

53 C53 C53 34 - - 0.16 - - 1.2x10 ⁹ „

[0160]Table 14

[0161] (Sheet feeding durability test of electrophotographic photosensitive member)

The electrophotographic photosensitive members 1 to 78 and CI to C71 for the sheet feeding durability test each were mounted on a laser beam printer made by Canon Inc. (trade name: LBP7200C) , and a sheet feeding durability test was performed under a low temperature and low humidity (15°C/10% RH) environment to evaluate an image. In the sheet feeding durability test, a text image having a coverage rate of 2% was printed on a letter size sheet one by one in an intermittent mode, and 3000 sheets of the image were output.

[0162] Then, a sheet of a sample for image evaluation

(halftone image of a one dot KEIMA pattern) was output every time when the sheet feeding durability test was started, after 1500 sheets of the image were output, and after 3000 sheets of the image were output.

[0163] The image was evaluated on the following criterion.

A: no image defects caused by occurrence of the leak are found in the image .

B: tiny black dots caused by occurrence of the leak are slightly found in the image.

C: large black dots caused by occurrence of the leak are clearly found in the image.

D: large black dots and short horizontal black stripes caused by occurrence of the leak are found in the image. E: long horizontal black stripes caused by occurrence of the leak are found in the image.

[0164] The charge potential (dark potential) and the potential during exposure (bright potential) were measured after the sample for image evaluation was output at the time of starting the sheet feeding durability test and after outputting 3000 sheets of the image. The measurement of the potential was performed using one white solid image and one black solid image. The dark potential at the initial stage (when the sheet feeding durability test was started) was Vd, and the bright potential at the initial stage (when the sheet feeding durability test was started) was VI. The dark potential after 3000 sheets of the image were output was Vd' , and the bright potential after 3000 sheets of the image were output was VI'. The difference between the dark

potential Vd' after 3000 sheets of the image were output and the dark potential Vd at the initial stage, i.e., the amount of the dark potential to be changed AVd (= |Vd' I - I Vd I ) was determined. Moreover, the difference between the bright potential VI' after 3000 sheets of the image were output and the bright

potential VI at the initial stage, i.e., the amount of the bright potential to be changed AVI (= | VI ' | - |V1|) was determined.

[0165] he result is shown in Tables 15 to 21.

[0166]Table 15

Amount of

Leakage potential to be changed [V]

Electrophotographic When

When When

Example photosensitive sheet

1500 3000

member feeding

sheets of sheets of AVd AVI durability

image are image are

test is

output output

started

1 1 A A A +10 +10

2 2 A A A +10 +25

3 3 A A A +8 +30

4 4 A A A +8 +15

5 5 A A A +10 +15

6 6 A A A +5 +15

7 7 A A A +5 +15

8 8 A A A +10 +20

9 9 A A A +12 +30

10 10 A A A +12 +20

11 11 A A A +10 +30

12 12 A B B +10 +15

13 13 A A A +10 +15

14 14 A A A +10 +15

15 15 A B B +10 +15

16 16 A A A +8 +15

17 17 A A A +8 +30

18 18 A A A +10 +15 _r able 16

Amount of

Leakage potential to be changed [V]

Electrophotographic When

When When

Example photosensitive sheet

1500 3000

member feeding

sheets of sheets of AVd AVI durability

image are image are

test is

output output

started

19 19 A A A +12 +30

20 20 A A A +10 +15

21 21 A A A +12 +15

22 22 A A A +10 +15

23 23 A A A +10 +20

24 24 A A A +12 +30

25 25 A A A +12 +15

26 26 A A A +10 +30

27 27 A B B +12 +15

28 28 A A A +13 +15

29 29 A A A +15 +18

30 30 A B B +14 +15

31 31 A A A +12 +35

32 32 A A A +10 +20

33 33 A A A +12 +15

34 34 A A A +10 +15

35 35 A A A +10 +20

36 36 A A A +15 +35

37 37 A A A +12 +15

38 38 A A A +10 +38

39 39 A B B +12 +15

40 40 A A A +13 +15

41 41 A A A +12 +15

42 42 A B B +14 +15

_r ^ able 17

Amount of

Leakage potential to be changed [V]

Electrophotographic When

When When

Example photosensitive sheet

1500 3000

member feeding

sheets of sheets of AVd AVI durability

image are image are

test is

output output

started

43 43 A A A +10 +10

44 44 A A A +10 +25

45 45 A A A +8 +30

46 46 A A A +8 +15

47 47 A A A +10 +15

48 48 A A A +5 +15

49 49 A A A +5 +15

50 50 A A A +10 +20

51 51 A A A +12 +30

52 52 A A A +12 +20

53 53 A A A +10 +30

54 54 A B 8 +10 +15

55 55 A A A +10 +15

56 56 A A A +10 +15

57 57 A B B +10 +15

58 58 A A A +8 +15

59 59 A A A +8 +30

60 60 A A A +10 +15

_n able 18

Amount of

Leakage potential to be changed [V]

Electrophotographic When

When When

Example photosensitive sheet

1500 3000

member feeding

sheets of sheets of AVd AVI durability

image are image are

test is

output output

started

61 61 A A A +12 +15

62 62 A A A +12 +25

63 63 A A A +8 +30

64 64 A A A +10 +15

65 65 A A A +10 +15

66 66 A A A +8 +20

67 67 A A A +8 +20

68 68 A A A +10 +24

69 69 A A A +15 +30

70 70 A A A +15 +25

71 71 A A A +10 +30

72 72 A B B +8 +15

73 73 A A A +8 +15

^• 74 74 A A A +10 +15

75 75 A B B +10 +15

76 76 A A A +10 +15

77 77 A A A +10 +30

78 78 A A A +12 +15

_n able 19

Amount of

Leakage potential to be changed [V]

Electrophotographic When When When

Comparative

photosensitive sheet 1500 3000 Example

member feeding sheets of sheets of

AVd durability image AVI image

test is are are

started output output

1 CI A A A +30 +80

2 C2 C D D +8 +25

3 C3 B B C +12 +30

4 C4 B B C +12 +30

5 C5 B C C +12 +25

6 C6 A A A +28 +100

7 C7 A A A +15 +80

8 C8 B B C +12 +30

9 C9 A A B +14 +60

10 CIO A A A +30 +85

11 Cl l C D E +8 +22

12 C12 B B C +12 +30

13 C13 B B C +12 +30

14 C14 B B C +12 +25

15 C15 A A A +28 +100

16 C16 A A A +15 +80

17 C17 B C C +12 +30

18 C18 A A B +14 +60

19 C19 A A A +30 +100

20 C20 C D E +10 +20

21 C21 B B C +12 +35

22 C22 B B C +12 +40

23 C23 B B C +12 +40

24 C24 A A A +25 +100

25 C25 A A A +15 +70

26 C26 B C C +12 +35

27 C27 A A B +14 +60

,.„ able 20

Amount of

Leakage potential to be changed [V]

Electrophotographic When When

Comparative When

photosensitive sheet 1500

Example 3000

member feeding sheets of

sheets of AVd AVI durability image

image are

test is are

output

started output

28 C28 B B C +12 +35

29 C29 B B C +12 +35

30 C30 B B C +12 +30

31 C31 B C C +8 +25

32 C32 B B C +15 +35

33 C33 B B C +20 +40

34 C34 B B C +12 +30

35 ^■ C35 B B C +12 +30

36 C36 B B C +12 +30

37 C37 B B C +12 +30

38 C38 A B C +12 +35

39 C39 A B C +12 +35

40 C40 A B C +12 +30

41 C41 A B C +8 +25

42 C42 A B C +15 +40

43 C43 A B C +20 +60

44 C44 A B C +12 +30

45 C45 A B C +12 +30

46 C46 A B C +12 +30

47 C47 A B C +12 +30

48 C48 A B B +10 +15

49 C49 A B B +10 +25

50 C50 A B C +15 +30

51 C51 A B B +10 +20

52 C52 A B B +10 +20

53 C53 B C C +20 +50

[0172]Table 21

[0173] (Probe pressure resistance test of electrophotographic photosensitive member)

The electrophotographic photosensitive members for the probe pressure resistance test 101 to 178 and ClOl to C171 were subjected to a probe pressure resistance test as follows.

[0174]A probe pressure resistance test apparatus is

illustrated in Fig. 2. The probe pressure resistance test was performed under a normal temperature and normal humidity (23°C/50% RH) environment.

[0175] Both ends of an electrophotographic photosensitive

member 1401 were placed on fixing bases 1402, and fixed such that the electrophotographic photosensitive member did not move. The tip of a probe electrode 1403 was brought into contact with the surface of the

electrophotographic photosensitive member 1401. To the probe electrode 1403, a power supply 1404 for applying voltage and an ammeter 1405 for measuring current were connected. A portion 1406 of the electrophotographic photosensitive member 1401 contacting the support was connected to a ground. The voltage applied for 2 seconds by the probe electrode 1403 was increased from 0 V in increments of 10 V. The probe pressure

resistance value was defined as the voltage when the leak occurred inside of the electrophotographic photosensitive member 1401 contacted by the tip of the probe electrode 1403 and the value indicated by the ammeter 1405 started to be 10 times or more larger. This measurement was performed on five points of the surface of the electrophotographic photosensitive member 1401, and the average value was defined as the probe pressure resistance value of the

electrophotographic photosensitive member 1401 to be measured .

The results are shown in Tables 22 to 24.

able 22

able 23

[0179]Table 24

[0180] hile the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0181] his application claims the benefit of Japanese Patent Application Nos. 2012-189530, filed August 30, 2012, and 2013-077620, filed April 3, 2013, which are hereby incorporated by reference herein in their entirety. Reference Signs List

[0182] 1 Electrophotographic photosensitive member

2 Shaft

3 Charging unit (primary charging unit)

4 Exposure light (image exposure light)

5 Developing unit

6 Transfer unit (such as transfer roller)

7 Cleaning unit (such as cleaning blade)

8 Fixing unit

9 Process cartridge

10 Guide unit

11 Pre-exposure light

P Transfer material (such as paper)