JP4839413B1 - Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus - Google Patents

Abstract

An electrophotographic photosensitive member in which a charging stripe is unlikely to be generated even in an electrophotographic photosensitive member adopting a layer containing a metal oxide as a conductive layer, and a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member. I will provide a.
A conductive layer of an electrophotographic photosensitive member contains a binder material and titanium oxide particles coated with tin oxide doped with phosphorus or tungsten.
[Selection figure] None

Description

  The present invention relates to an electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  In recent years, research and development of electrophotographic photoreceptors (organic electrophotographic photoreceptors) using organic photoconductive materials have been actively conducted.

  An electrophotographic photoreceptor is basically composed of a support and a photosensitive layer formed on the support. However, the present situation is that the support and photosensitive layer are exposed in order to conceal defects on the surface of the support, protect against electrical breakdown of the photosensitive layer, improve chargeability, and improve the charge injection prevention property from the support to the photosensitive layer. Various layers are often provided between the layers.

Among the layers provided between the support and the photosensitive layer, a layer containing metal oxide particles is known as a layer provided for the purpose of concealing defects on the surface of the support. A layer containing a metal oxide generally has higher conductivity than a layer containing no metal oxide particles (for example, 5.0 × 10 ^{8 to} 1.0 × 10 ¹³ Ω · in volume resistivity). cm), even if the film thickness of the layer is increased, it is difficult to increase the residual potential during image formation, so that it is easy to hide defects on the surface of the support. By providing such a highly conductive layer (hereinafter referred to as “conductive layer”) between the support and the photosensitive layer to conceal defects on the surface of the support, the tolerance of defects on the surface of the support is allowed. Will grow. As a result, since the allowable use range of the support is greatly expanded, there is an advantage that the productivity of the electrophotographic photosensitive member can be improved.

  Patent Document 1 discloses a technique using tin oxide particles in which phosphorus is doped in a layer between a support and a photoconductive layer. Patent Document 2 discloses a technique using tin oxide particles doped with tungsten in a protective layer on a photosensitive layer. Patent Document 3 discloses a technique using titanium oxide particles coated with oxygen-deficient tin oxide on a conductive layer between a support and a photosensitive layer. Patent Documents 4 and 5 disclose a technique using barium sulfate particles coated with tin oxide in a layer between a support and a photosensitive layer. Reference 6 discloses a technique using titanium oxide particles coated with indium oxide doped with tin (indium oxide-tin oxide) between the support and the photosensitive layer. .

Japanese Patent Laid-Open No. 06-222600 JP 2003-316059 A JP 2007-047736 A Japanese Patent Laid-Open No. 06-208238 JP 07-295270 A JP 11-007145 A

  However, as a result of the study by the present inventors, when an electrophotographic photosensitive member employing the above-described metal oxide-containing layer as a conductive layer is subjected to image formation in a low-temperature and low-humidity environment, charged streaks appear in the output image. It turns out that it becomes easy to occur. The charging stripe is a direction perpendicular to the circumferential direction of the surface of the electrophotographic photosensitive member due to a decrease in uniformity of the surface potential of the electrophotographic photosensitive member (charging unevenness) when the surface of the electrophotographic photosensitive member is charged. This is a streak-like image defect and is likely to appear remarkably when a halftone image is output.

  An object of the present invention is to provide an electrophotographic photosensitive member in which a charging streak is unlikely to occur even in an electrophotographic photosensitive member adopting a layer containing a metal oxide as a conductive layer, and a process cartridge having the electrophotographic photosensitive member and It is to provide an electrophotographic apparatus.

The present invention relates to an electrophotographic photosensitive member having a support, a conductive layer formed on the support, and a photosensitive layer formed on the conductive layer.
Conductive layer, a binder material, and contains titanium oxide particles coated with tin oxide Li down is doped,
Dielectric loss tanδ at frequency 1.0 × ¹⁰ 3 Hz of the electrophotographic photosensitive member is an electrophotographic photosensitive member according to 5 × ^{10 -3} or more 2 × ^{10 -2} wherein der Rukoto below.

  Further, the present invention integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means, a transfer means, and a cleaning means, and is detachable from the main body of the electrophotographic apparatus. It is a process cartridge characterized by being.

  The present invention also provides an electrophotographic apparatus comprising the above-described electrophotographic photosensitive member, and a charging unit, an exposing unit, a developing unit, and a transfer unit.

  According to the present invention, an electrophotographic photosensitive member in which a charging streak is unlikely to occur even in an electrophotographic photosensitive member adopting a layer containing a metal oxide as a conductive layer, and a process cartridge having the electrophotographic photosensitive member and An electrophotographic apparatus can be provided.

1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention. It is a figure (top view) for demonstrating the measuring method of the volume resistivity of a conductive layer. It is a figure (sectional drawing) for demonstrating the measuring method of the volume resistivity of a conductive layer.

  The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a support, a conductive layer formed on the support, and a photosensitive layer formed on the conductive layer. The photosensitive layer may be a single layer type photosensitive layer containing a charge generation material and a charge transport material in a single layer, or a charge generation layer containing a charge generation material and a charge transport containing a charge transport material. It may be a laminated photosensitive layer in which layers are laminated. If necessary, an undercoat layer may be provided between the conductive layer and the photosensitive layer.

  As a support body, what has electroconductivity (conductive support body) is preferable, For example, the metal support bodies formed with metals, such as aluminum, aluminum alloy, stainless steel, can be used. In the case of using aluminum or an aluminum alloy, an aluminum tube manufactured by a manufacturing method including an extrusion process and a drawing process, or an aluminum pipe manufactured by a manufacturing method including an extrusion process and an ironing process can be used. Such an aluminum tube provides good dimensional accuracy and surface smoothness without cutting the surface, and is advantageous in terms of cost, but the surface of a non-cut aluminum tube has a crust-like convex defect. Therefore, it is particularly effective to provide a conductive layer.

In the present invention, for the purpose of concealing defects on the surface of the support, the support is made of a binding material and tin oxide (SnO ₂ ) doped with phosphorus (P) or tungsten (W). A conductive layer containing coated titanium oxide (TiO ₂ ) particles is provided. Hereinafter, the titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P) or tungsten (W) are also referred to as “phosphorus / tungsten-doped tin oxide-coated titanium oxide particles”.

The volume resistivity of the conductive layer is preferably 1.0 × 10 ¹³ Ω · cm or less, and more preferably 5.0 × 10 ¹² Ω · cm or less. If a layer having a volume resistivity that is too high is provided on the support as a layer for concealing defects on the surface of the support, the flow of electric charges tends to stagnate during image formation, and the residual potential tends to increase. Moreover, it is preferable that the volume resistivity of a conductive layer is low also from a viewpoint of suppressing generation | occurrence | production of a charging stripe. On the other hand, the volume resistivity of the conductive layer is preferably 1.0 × 10 ⁸ Ω · cm or more, and more preferably 5.0 × 10 ⁸ Ω · cm or more. If the volume resistivity of the conductive layer is too low, the amount of charge flowing in the conductive layer becomes too large, and when repeated image formation is performed in a high-temperature and high-humidity environment, the point due to charge injection from the support to the photosensitive layer is reduced. The fog is likely to occur in the output image.

  A method for measuring the volume resistivity of the conductive layer of the electrophotographic photosensitive member will be described with reference to FIGS.

  The volume resistivity of the conductive layer is measured under a normal temperature and normal humidity (23 ° C./50% RH) environment. A copper tape 203 (manufactured by Sumitomo 3M Co., Ltd., model number No. 1181) is attached to the surface of the conductive layer 202, and this is used as an electrode on the surface side of the conductive layer 202. The support 201 is an electrode on the back side of the conductive layer 202. A power source 206 for applying a voltage between the copper tape 203 and the support 201 and a current measuring device 207 for measuring a current flowing between the copper tape 203 and the support 201 are installed. Also, in order to apply a voltage to the copper tape 203, a copper wire 204 is placed on the copper tape 203, and the copper wire 204 is the same as the copper tape 203 from above the copper wire 204 so that the copper wire 204 does not protrude from the copper tape 203. The tape 205 is affixed, and the copper wire 204 is fixed to the copper tape 203. A voltage is applied to the copper tape 203 using a copper wire 204.

The background current value when no voltage is applied between the copper tape 203 and the support 201 is I ₀ [A], and the current value when a voltage of only a direct current component is 1 V is I [A]. When the film thickness d [cm] of the layer 202 and the area of the electrode (copper tape 203) on the surface side of the conductive layer 202 are S [cm ² ], the value expressed by the following formula (1) is the value of the conductive layer 202. The volume resistivity is ρ [Ω · cm].
ρ = 1 / (I−I ₀ ) × S / d [Ω · cm] (1)

In this measurement, since a minute amount of current of 1 × 10 ⁻⁶ A or less is measured, it is preferable to use a device capable of measuring a minute current as the current measuring device 207. Examples of such devices include a pA meter (trade name: 4140B) manufactured by Yokogawa Hewlett-Packard Company.

  Even if the volume resistivity of the conductive layer is measured in a state where only the conductive layer is formed on the support, each layer (such as the photosensitive layer) on the conductive layer is peeled off from the electrophotographic photosensitive member on the support. Even when the measurement is performed with only the conductive layer left, the same value is obtained.

In the present invention, as the metal oxide particles used in the conductive layer, core material particles (titanium oxide (TiO ₂ ) particles) and coating layers (tin oxide (SnO ₂ ) doped with phosphorus (P) or tungsten (W)) The composite particles having () are used in order to improve the dispersibility of the metal oxide particles in the conductive layer coating solution used for forming the conductive layer. As metal oxide particles, only tin oxide (SnO ₂ ) particles doped with phosphorus (P) or tungsten (W) (tin oxide (SnO ₂ ) doped with phosphorus (P) or tungsten (W)) only The particle size of the metal oxide particles in the coating liquid for the conductive layer is likely to increase, and convex surface defects occur on the surface of the conductive layer, and the coating liquid for the conductive layer is stable. May decrease.

The reason why titanium oxide (TiO ₂ ) particles are used as the core material particles is that the effect of suppressing the generation of charging stripes is high. Furthermore, the transparency as the metal oxide particles is low, and defects on the surface of the support are easily concealed. On the other hand, for example, when barium sulfate particles are used as the core material particles, it is difficult to suppress the generation of charging stripes. In addition, since the transparency as the metal oxide particles is high, a material for concealing defects on the surface of the support may be separately required.

In addition, the phosphor oxide / tungsten-doped tin oxide coated titanium oxide particles are used as the metal oxide particles, not the uncoated titanium oxide (TiO ₂ ) particles. The uncoated titanium oxide (TiO ₂ ) particles are used for image formation. This is because sometimes the flow of electric charge tends to stagnate and the residual potential tends to rise.

In addition, the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles have a higher effect of suppressing the generation of charged streaks than the titanium oxide (TiO ₂ ) particles coated with oxygen-deficient tin oxide (SnO ₂ ). . Furthermore, compared with titanium oxide (TiO ₂ ) particles coated with oxygen-deficient tin oxide (SnO ₂ ), the volume resistivity is increased in a low humidity environment and the volume resistivity is decreased in a high humidity environment. There is little, and environmental stability is excellent.

A method for producing titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P) or tungsten (W) is disclosed in JP-A Nos. 06-207118 and 2004. -349167 is also disclosed.

In order to keep the volume resistivity of the conductive layer in the above range, the powder resistivity (powder specific resistance) is 1.0 × 10 ⁰ Ω when preparing the coating liquid for the conductive layer used for forming the conductive layer. It is preferable to use phosphorus / tungsten-doped tin oxide-coated titanium oxide particles having a size of cm to 1.0 × 10 ⁶ Ω · cm. More preferable powder resistivity of the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is 1.0 × 10 ⁰ Ω · cm or more and 1.0 × 10 ⁵ Ω · cm or less, more preferably 1.0 × 10 10. ^{It is 0} Ω · cm or more and 1.0 × 10 ³ Ω · cm or less, and more preferably 1.0 × 10 ⁰ Ω · cm or more and 1.0 × 10 ² Ω · cm or less. When the powder resistivity of the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is too high, the volume resistivity of the conductive layer is adjusted to 1.0 × 10 ¹³ Ω · cm or less or 5.0 × 10 ¹² Ω · cm or less. It becomes difficult to do. On the other hand, when the powder resistivity of the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is too low, the charging ability of the produced electrophotographic photosensitive member tends to decrease.

The ratio (coverage) of tin oxide (SnO ₂ ) in the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is preferably 10 to 60% by mass, and more preferably 15 to 55% by mass. In order to control the coverage of the tin oxide (SnO _2), it is necessary to blend a tin raw material necessary to produce a tin oxide (SnO ₂₎ at phosphorus / tungsten-doped tin oxide coated titanium oxide particles produced. For example, the preparation needs to take into account tin oxide (SnO ₂ ) generated from tin chloride (SnCl ₄ ), which is a tin raw material. Note that coverage of tin oxide (SnO ₂₎ without taking into account the mass of the tin oxide phosphorus doped in the (SnO ₂₎ (P) or tungsten (W), oxide and tin oxide (SnO ₂₎ titanium The value is calculated from the mass of tin oxide (SnO ₂ ) relative to the total mass of (TiO ₂ ). When the coverage of tin oxide (SnO ₂ ) is too small, it becomes difficult to adjust the powder resistivity of the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles to 1.0 × 10 ⁶ Ω · cm or less. If the coverage is too large, the coating of titanium oxide (TiO ₂ ) particles with tin oxide (SnO ₂ ) tends to be non-uniform, and the cost tends to be high.

Moreover, tin oxide amount of phosphorus (P) or tungsten (W), which is doped (SnO ₂₎ (doping amount), tin oxide _(SnO 2) (mass containing no phosphorus (P) or tungsten (W)) It is preferable that it is 0.1-10 mass% with respect to. When the amount of phosphorus (P) or tungsten (W) doped in tin oxide (SnO ₂ ) is too small, the powder resistivity of the phosphorus / tungsten-doped tin oxide coated titanium oxide particles is 1.0 × 10 ⁶ Ω · It becomes difficult to adjust to below cm. When the amount of phosphorus (P) or tungsten (W) doped in tin oxide (SnO ₂ ) is too large, the crystallinity of tin oxide (SnO ₂ ) decreases, and the phosphorus / tungsten doped tin oxide coated titanium oxide particles It becomes difficult to adjust the powder resistivity to 1.0 × 10 ⁰ Ω · cm or more and 1.0 × 10 ⁶ Ω · cm or less. In general, by doping tin oxide (SnO ₂ ) with phosphorus (P) or tungsten (W), the powder resistivity of the particles can be reduced as compared with those not doped.

The powder resistivity of the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is measured under a normal temperature and normal humidity (23 ° C./50% RH) environment. In the present invention, a resistance measuring device (trade name: Loresta GP) manufactured by Mitsubishi Chemical Corporation was used as the measuring device. The phosphorus / tungsten-doped tin oxide-coated titanium oxide particles to be measured are solidified at a pressure of 500 kg / cm ² to obtain a pellet-shaped measurement sample. The applied voltage is 100V.

In order to further suppress the generation of charging stripes, the dielectric loss tan δ at a frequency of 1.0 × 10 ³ Hz of the electrophotographic photosensitive member is preferably 5 × 10 ⁻³ or more and 2 × 10 ⁻² or less. .

  The details of the relationship between the charging stripe and the dielectric loss tan δ of the electrophotographic photosensitive member are unknown, but the present inventors consider as follows.

  Hereinafter, the front side of the charging region (the region where the surface of the electrophotographic photosensitive member is charged by the charging means) with respect to the rotation direction of the electrophotographic photosensitive member is referred to as upstream charging region, and the opposite side is referred to as downstream charging region. First, after charge is applied to the surface of the electrophotographic photosensitive member upstream of the charging region, the amount of charge applied decreases downstream of the charging region, and as a result, the surface of the electrophotographic photosensitive member is sufficiently charged. There may be a case where a portion and a portion that is not sufficiently charged are mixed. In this case, a potential difference is generated on the surface of the electrophotographic photosensitive member, resulting in uneven development, and a streak-like image defect (shading unevenness) in the direction perpendicular to the circumferential direction of the surface of the electrophotographic photosensitive member occurs in the output image. Sometimes. This image defect is a charging stripe.

  One possible cause of this phenomenon is dielectric polarization. Dielectric polarization is a phenomenon in which a charge is biased in a dielectric placed in an electric field. One of the dielectric polarizations is the orientation polarization that occurs when the dipole moment in the molecules constituting the dielectric changes direction.

  The relationship between the orientation polarization and the surface potential of the electrophotographic photosensitive member will be described below with reference to how the electric field applied to the electrophotographic photosensitive member changes when the surface of the electrophotographic photosensitive member is charged.

  Charge is applied to the surface of the electrophotographic photosensitive member by applying the charge to the surface of the electrophotographic photosensitive member upstream of the charging region. Electric charges are placed on the surface of the electrophotographic photosensitive member, and an electric field (hereinafter referred to as “external electric field”) is generated by the charges. Due to this external electric field, the dipole moment inside the electrophotographic photosensitive member gradually polarizes (orientation polarization). The vector sum of the polarized dipole moments is an electric field (hereinafter referred to as “internal electric field”) generated inside the electrophotographic photosensitive member by the polarization. As time progresses, polarization proceeds and the internal electric field increases.

  Next, considering the electric field strength applied to the entire electrophotographic photosensitive member, when the charge amount on the surface of the electrophotographic photosensitive member is constant, the external electric field generated by the charge is constant. In contrast, the internal electric field increases as the orientation polarization progresses. Since the sum of the electric field strength applied to the entire electrophotographic photosensitive member may be the sum of the external electric field and the internal electric field, it is considered that the sum of the electric field strengths gradually decreases as the polarization progresses.

  Since the film thickness of each layer of the electrophotographic photosensitive member does not substantially change during the process of orientation polarization, the potential difference and the electric field are considered to be proportional to each other. This causes a reduction in the surface potential of the photographic photoreceptor.

In order to estimate the progress of this orientation polarization, the dielectric loss tan δ is used in the present invention. The dielectric loss is a heat loss of energy based on the progress of orientation polarization in an alternating electric field, and serves as an index of time dependency of orientation polarization. A large dielectric loss tan δ at a certain frequency means that the progression of orientational polarization at a time corresponding to that frequency is large. In order to reduce the surface potential of the electrophotographic photosensitive member due to the progress of orientation polarization, the charge is applied to the surface of the electrophotographic photosensitive member downstream from the start of the charging to the surface of the electrophotographic photosensitive member upstream of the charging region. It affects how much the polarization progresses in the time until (usually about 1.0 × 10 ⁻³ seconds). If the orientation polarization is not completed at this time, the orientation polarization proceeds before the charge is applied to the surface of the electrophotographic photosensitive member downstream of the charged region, so that the surface potential of the electrophotographic photosensitive member decreases. Conceivable.

  From the above, it is considered that by measuring the dielectric loss tan δ of the electrophotographic photosensitive member, it is possible to predict the generation and the degree of the charge streaks resulting from the decrease in the surface potential of the electrophotographic photosensitive member as the orientation polarization progresses. It is done.

Hereinafter, a method for measuring the dielectric loss tan δ of the electrophotographic photosensitive member will be described.
First, the electrophotographic photosensitive member is cut into small pieces (10 mm × 10 mm). When the electrophotographic photosensitive member is cylindrical, it is stretched by a vise so that the small pieces of the curved surface become flat. A sample for measurement is prepared by depositing gold (electrode) having a thickness of 600 nm on a flat piece. In the present invention, vapor deposition was performed using a sputtering apparatus (trade name: SC-707QUICK COATER) manufactured by SANYU DENSHI. The measurement sample is left for 24 hours in a normal temperature and normal humidity (23 ° C./50% RH) environment. Then, the dielectric loss tan δ of the electrophotographic photosensitive member is measured under the same environment under the conditions of a frequency of 1.0 × 10 ³ Hz and an applied voltage of 100 mV. In the present invention, the dielectric loss tan δ was measured using an impedance analyzer (trade name: frequency response analyzer 1260 type, dielectric constant interface 1296 type) manufactured by Solartron.

  In the measurement sample, each layer similar to that of the electrophotographic photosensitive member to be measured was formed on a support on which an aluminum sheet was wound, and then the aluminum sheet was cut into small pieces (10 mm × 10 mm), and the above-described samples were formed thereon. You may produce by vapor-depositing gold | metal | money (electrode). Even when the measurement sample prepared in this way is used, the same value as above is shown.

  There is a correlation between the volume resistivity of the conductive layer and the dielectric loss tan δ of the electrophotographic photosensitive member having the conductive layer, and the volume resistivity of the conductive layer is increased and the dielectric loss tan δ of the electrophotographic photosensitive member having the conductive layer is increased. Tend to be higher.

  When the volume resistivity of the conductive layer is the same, the dielectric loss tan δ of the electrophotographic photosensitive member having a conductive layer containing phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is a conductive layer containing conventional metal oxide particles. It tends to be lower than the dielectric loss tan δ of the electrophotographic photosensitive member having the above. Therefore, the use of phosphorus / tungsten-doped tin oxide-coated titanium oxide particles makes it easier to suppress the occurrence of charging stripes while suppressing the occurrence of spots and fog.

  The conductive layer may be formed by applying a conductive layer coating solution obtained by dispersing phosphorus / tungsten-doped tin oxide-coated titanium oxide particles together with a binder in a solvent, and drying and / or curing the coating solution. it can. Examples of the dispersion method include a method using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

  Examples of the binder material (binder resin) used for the conductive layer include phenol resin, polyurethane, polyamide, polyimide, polyamideimide, polyvinyl acetal, epoxy resin, acrylic resin, melamine resin, and polyester. These can be used alone or in combination of two or more. Among these, suppression of migration (melting) to other layers, adhesion to the support, dispersibility / dispersion stability of phosphorus / tungsten-doped tin oxide-coated titanium oxide particles, solvent resistance after layer formation, etc. From this point of view, a curable resin is preferable, and a thermosetting resin is more preferable. Of the thermosetting resins, thermosetting phenol resins and thermosetting polyurethanes are preferred. When a curable resin is used as the binder material for the conductive layer, the binder material contained in the conductive layer coating solution is a monomer and / or oligomer of the curable resin.

  Examples of the solvent used in the conductive layer coating solution include alcohols such as methanol, ethanol, isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, and the like. Ethers, esters such as methyl acetate and ethyl acetate, and aromatic hydrocarbons such as toluene and xylene.

In the present invention, the mass ratio (P / B) between the phosphor / tungsten-doped tin oxide-coated titanium oxide particles (P) and the binder material (B) in the conductive layer coating solution is 1.0 / 1.0 or more and 3 0.5 / 1.0 or less is preferable. If the amount of phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is too small compared to the binder material, the volume resistivity of the conductive layer is 1.0 × 10 ¹³ Ω · cm or less, or 5.0 × 10 ¹² Ω · cm. It becomes difficult to adjust to the following. On the other hand, when the amount of phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is too large compared to the binder material, the volume resistivity of the conductive layer is 1.0 × 10 ⁸ Ω · cm or more, or 5.0 × 10 ⁸ Ω.・ It becomes difficult to adjust to more than cm. In addition, if the amount of phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is too large compared to the binder material, it becomes difficult to bind the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles, and cracks are likely to occur in the conductive layer. Become.

  The film thickness of the conductive layer is preferably 10 μm or more and 40 μm or less, more preferably 15 μm or more and 35 μm or less from the viewpoint of concealing defects on the surface of the support.

  In the present invention, FISCHERSCOPE mms manufactured by Fisher Instruments Co., Ltd. was used as a film thickness measuring device for each layer of the electrophotographic photosensitive member including the conductive layer.

  The average particle diameter of the phosphor / tungsten-doped tin oxide-coated titanium oxide particles in the conductive layer coating solution is preferably from 0.10 μm to 0.60 μm, and preferably from 0.15 μm to 0.45 μm. More preferred. If the average particle size is too small, re-aggregation of the phosphor / tungsten-doped tin oxide-coated titanium oxide particles occurs after the preparation of the coating solution for the conductive layer, and the stability of the coating solution for the conductive layer is reduced. Cracks may occur. When the average particle size is too large, the surface of the conductive layer becomes rough, local charge injection to the photosensitive layer is likely to occur, and the spots on the white background of the output image may become conspicuous.

  The average particle diameter of the phosphor / tungsten-doped tin oxide-coated titanium oxide particles in the conductive layer coating solution can be measured by a liquid phase precipitation method as follows.

  First, the conductive layer coating solution is diluted with the solvent used for the preparation so that the transmittance is between 0.8 and 1.0. Next, a histogram of the average particle size (volume standard D50) and particle size distribution of phosphorus / tungsten-doped tin oxide-coated titanium oxide particles is prepared using an ultracentrifugal automatic particle size distribution measuring apparatus. In the present invention, an ultracentrifugal automatic particle size distribution measuring apparatus (trade name: CAPA700) manufactured by Horiba, Ltd. was used as an ultracentrifugal automatic particle size distribution measuring apparatus, and measurement was performed under the condition of a rotational speed of 3000 rpm.

In order to suppress interference of light reflected on the surface of the conductive layer and generation of interference fringes in the output image, the coating liquid for the conductive layer has a surface roughening for roughening the surface of the conductive layer. An imparting material may be included. As the surface roughening material, resin particles having an average particle diameter of 1 μm or more and 5 μm or less (preferably 3 μm or less) are preferable. Examples of the resin particles include curable resin particles such as curable rubber, polyurethane, epoxy resin, alkyd resin, phenol resin, polyester, silicone resin, and acrylic-melamine resin. Among these, silicone resin particles that are difficult to aggregate are preferable. Since the specific gravity of the resin particles (0.5-2) is smaller than the specific gravity (4-7) of the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles, the surface of the conductive layer is efficiently roughened when the conductive layer is formed. Can be However, the volume resistivity of the conductive layer tends to increase as the content of the surface roughening agent in the conductive layer increases. Therefore, in order to adjust the volume resistivity of the conductive layer to 1.0 × 10 ¹³ Ω · cm or less, the content of the surface roughening imparting agent in the conductive layer coating solution is determined by the amount of the bonding in the conductive layer coating solution. It is preferable that it is 1-80 mass% with respect to a dressing material, and it is more preferable that it is 1-40 mass%.

  The conductive layer coating solution may contain a leveling agent for enhancing the surface properties of the conductive layer. Moreover, you may make the coating liquid for conductive layers contain the pigment particle for improving the concealment property of a conductive layer.

  An undercoat layer (also referred to as a barrier layer or an intermediate layer) having an electrical barrier property may be provided between the conductive layer and the photosensitive layer in order to prevent charge injection from the conductive layer to the photosensitive layer. .

The undercoat layer can be formed by applying an undercoat layer coating solution containing a resin (binder resin) on the conductive layer and drying it.
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, and polyamides, polyimides and polyamides. Examples include imide, polyamic acid, melamine resin, epoxy resin, polyurethane, and polyglutamic acid ester. Among these, a thermoplastic resin is preferable in order to effectively develop the electrical barrier property of the undercoat layer. Of the thermoplastic resins, thermoplastic polyamide is preferable. As the polyamide, copolymer nylon or the like is preferable.
The thickness of the undercoat layer is preferably from 0.1 μm to 2 μm.

  Further, in order to prevent the flow of electric charges in the undercoat layer, the undercoat layer may contain an electron transport material.

A photosensitive layer is provided on the conductive layer (undercoat layer).
Examples of the charge generating material used in the photosensitive layer include azo pigments such as monoazo, disazo, and trisazo, phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, indigo pigments such as indigo and thioindigo, perylene acid anhydride, Perylene pigments such as perylene imide, polycyclic quinone pigments such as anthraquinone and pyrenequinone, squarylium dyes, pyrylium and thiapyrylium salts, triphenylmethane dyes, quinacridone pigments, azulenium salt pigments, cyanine dyes, Xanthene dyes, quinoneimine dyes, styryl dyes, and the like. Among these, metal phthalocyanines such as oxytitanium phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine are preferable.

  When the photosensitive layer is a laminated photosensitive layer, the charge generation layer is formed by applying a charge generation layer coating solution obtained by dispersing a charge generation material in a solvent together with a binder resin, and drying the coating solution. can do. Examples of the dispersion method include a method using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, a roll mill, and the like.

  Examples of the binder resin used for the charge generation layer include polycarbonate, polyester, polyarylate, butyral resin, polystyrene, polyvinyl acetal, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, phenol resin, silicone resin, polysulfone. Styrene-butadiene copolymer, alkyd resin, epoxy resin, urea resin, vinyl chloride-vinyl acetate copolymer, and the like. These may be used alone or in combination as a mixture or copolymer.

  The ratio of the charge generation material to the binder resin (charge generation material: binder resin) is preferably in the range of 10: 1 to 1:10 (mass ratio), and in the range of 5: 1 to 1: 1 (mass ratio). Is more preferable, and the range of 3: 1 to 1: 1 (mass ratio) is more preferable.

  Examples of the solvent used in the charge generation layer coating solution include alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogenated hydrocarbons, and aromatic compounds.

  The thickness of the charge generation layer is preferably 5 μm or less, and more preferably 0.1 μm or more and 2 μm or less.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary. In addition, in order to prevent the flow of charges from stagnation in the charge generation layer, the charge generation layer may contain an electron transport material (an electron accepting material such as an acceptor).

  Examples of the charge transport material used in the photosensitive layer include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triallylmethane compounds.

  When the photosensitive layer is a laminated type photosensitive layer, the charge transport layer is formed by applying a charge transport layer coating solution obtained by dissolving a charge transport material and a binder resin in a solvent, and drying it. can do.

  Examples of the binder resin used for the charge transport layer include acrylic resin, styrene resin, polyester, polycarbonate, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane, alkyd resin, and unsaturated resin. These can be used alone or in combination as a mixture or copolymer.

  The ratio of the charge transport material to the binder resin (charge transport material: binder resin) is preferably in the range of 2: 1 to 1: 2 (mass ratio).

  Examples of the solvent used in the charge transport layer coating solution include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, ethers such as dimethoxymethane and dimethoxyethane, and aromatics such as toluene and xylene. Examples include hydrocarbons and hydrocarbons substituted with halogen atoms such as chlorobenzene, chloroform and carbon tetrachloride.

  The thickness of the charge transport layer is preferably 3 μm or more and 40 μm or less, more preferably 5 μm or more and 30 μm or less from the viewpoint of charge uniformity and image reproducibility.

  In addition, an antioxidant, an ultraviolet absorber, and a plasticizer can be added to the charge transport layer as necessary.

  When the photosensitive layer is a single layer type photosensitive layer, the single layer type photosensitive layer is coated with a single layer type photosensitive layer coating solution containing a charge generating material, a charge transporting material, a binder resin and a solvent, It can be formed by drying it. As the charge generation material, the charge transport material, the binder resin, and the solvent, for example, the various types described above can be used.

A protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer.
The protective layer can be formed by applying a protective layer coating solution containing a resin (binder resin), and drying and / or curing it.
Examples of the binder resin used for the protective layer include phenol resin, acrylic resin, polystyrene, polyester, polycarbonate, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane, alkyd resin, siloxane resin, and unsaturated resin. It is done. These can be used alone or in combination as a mixture or copolymer.
The thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 8 μm or less.

  When applying the coating liquid for each of the above layers, for example, a dip coating method (dip coating method), a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, or a blade coating method should be used. Can do.

FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having an electrophotographic photosensitive member.
In FIG. 1, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member, which is driven to rotate about a shaft 2 in a direction indicated by an arrow at a predetermined peripheral speed.

  The peripheral surface of the electrophotographic photosensitive member 1 to be rotationally driven is uniformly charged to a predetermined positive or negative potential by a charging unit (primary charging unit, charging roller, etc.) 3, and then subjected to slit exposure, laser beam scanning exposure, or the like. The exposure light (image exposure light) 4 output from the exposure means (image exposure means, not shown) is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the peripheral surface of the electrophotographic photosensitive member 1. The voltage applied to the charging unit 3 may be only a DC voltage or a DC voltage on which an AC voltage is superimposed.

  The electrostatic latent image formed on the peripheral surface of the electrophotographic photosensitive member 1 is developed with toner of the developing means 5 to become a toner image. Next, the toner image formed on the peripheral surface of the electrophotographic photosensitive member 1 is transferred to a transfer material (such as paper) P by a transfer bias from a transfer unit (such as a transfer roller) 6. The transfer material P is fed from a transfer material supply means (not shown) between the electrophotographic photoreceptor 1 and the transfer means 6 (contact portion) in synchronization with the rotation of the electrophotographic photoreceptor 1.

  The transfer material P that has received the transfer of the toner image is separated from the peripheral surface of the electrophotographic photosensitive member 1 and is introduced into the fixing means 8 to receive the image fixing, and is printed out of the apparatus as an image formed product (print, copy). Be out.

  The peripheral surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is subjected to removal of residual toner by a cleaning means (cleaning blade or the like) 7. Further, after being subjected to charge removal processing by pre-exposure light 11 from a pre-exposure means (not shown), it is repeatedly used for image formation. When the charging unit is a contact charging unit, pre-exposure is not always necessary.

  Among the above-described components selected from the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, the transfer unit 6, and the cleaning unit 7, a plurality of components are housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from the electrophotographic apparatus main body. In FIG. 1, an electrophotographic photosensitive member 1, a charging unit 3, a developing unit 5 and a cleaning unit 7 are integrally supported to form a cartridge, and an electrophotographic apparatus is provided using a guide unit 10 such as a rail of the electrophotographic apparatus main body. The process cartridge 9 is detachable from the main body.

  A roller-shaped charging member (charging roller) is preferably used as the charging means of the process cartridge and the electrophotographic apparatus of the present invention. Examples of the configuration of the charging roller include a configuration composed of a conductive substrate and one or more coating layers formed on the conductive substrate. Moreover, electroconductivity is provided to at least one layer of the coating layer. More specifically, a preferable configuration includes a conductive substrate, a conductive elastic layer formed on the conductive substrate, and a surface layer formed on the conductive elastic layer.

  The ten-point average roughness (Rzjis) of the surface of the charging roller is preferably 5.0 μm or less. In the present invention, the 10-point average roughness (Rzjis) of the surface of the charging roller was measured using a surface roughness measuring instrument (trade name: SE-3400) manufactured by Kosaka Laboratory. More specifically, Rzjis at any six points on the surface of the charging roller is measured using this surface roughness measuring instrument, and the average value of the six points is used as the ten-point average roughness (Rzjis) of the surface of the charging roller. did.

  If the 10-point average roughness (Rzjis) of the surface of the charging roller is too large, the toner and its external additives are likely to adhere to the surface of the charging roller when image formation is repeated, resulting in dirt on the surface of the charging roller. The resulting image defect may occur. Further, by setting the ten-point average roughness (Rzjis) of the surface of the charging roller to 5.0 μm or less, it is possible to suppress a difference in discharge charge amount due to a difference in height of the surface of the charging roller. For this reason, it is possible to suppress the occurrence of image defects such as spots due to charging failure caused by the shape of the surface of the charging roller.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these. In the examples, “part” means “part by mass”. The titanium oxide (TiO ₂ ) particles (core material particles) in the phosphorus / tungsten-doped tin oxide-coated titanium oxide particles used in the examples all have a Bet value of 6.6 m ² / g. Examples 10-14 and 16, 19 and 20 are reference examples.

<Example of preparation of coating solution for conductive layer>
(Preparation example of coating liquid 1 for conductive layer)
Titanium oxide (TiO ₂ ) particles (powder resistivity: 40 Ω · cm, tin oxide (SnO ₂ )) coated with tin oxide (SnO ₂ ) doped with phosphorus (P) as metal oxide particles Covering ratio: 35% by mass, 204 parts of phosphorus (P) doped in tin oxide (SnO ₂ ) (doping amount: 3% by mass), phenol resin as binder resin (monomer / oligomer of phenol resin) ) (Product name: Priorofen J-325, manufactured by Dainippon Ink & Chemicals, Inc., resin solid content: 60% by mass) 148 parts, and 98 parts of 1-methoxy-2-propanol as a solvent, Place in a sand mill using 450 parts of 8 mm glass beads and perform dispersion treatment under the dispersion treatment conditions of rotation speed: 2000 rpm, dispersion treatment time: 4 hours, cooling water set temperature: 18 ° C. A dispersion was obtained.

  After removing the glass beads from the dispersion with a mesh, the dispersion was surface-roughened with silicone resin particles (trade name: Tospearl 120, manufactured by GE Toshiba Silicone Co., Ltd., average particle size: 2 μm) 13.8. Part, 0.014 parts of silicone oil as a leveling agent (trade name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.), 6 parts of methanol, and 6 parts of 1-methoxy-2-propanol were added and stirred. By doing this, the coating liquid 1 for conductive layers was prepared.

The average particle diameter of the titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P) in the conductive layer coating solution 1 was 0.35 μm.

(Preparation example of coating liquid 2-20 for conductive layer)
Table 1 shows the types of metal oxide particles (phosphorus / tungsten-doped tin oxide-coated titanium oxide particles) and the dispersion treatment conditions (dispersion treatment time and rotation speed) used in the preparation of the coating liquid for the conductive layer. Except for doing in this manner, conductive layer coating solutions 2 to 20 were prepared in the same manner as in the preparation example of the conductive layer coating solution 1. Table 1 shows the average particle diameters of the metal oxide particles (phosphorus / tungsten-doped tin oxide-coated titanium oxide particles) in the coating liquids 2 to 20 for the conductive layer. In Table 1, tin oxide is “SnO ₂ ” and titanium oxide is “TiO ₂ ”.

(Preparation example of coating liquid C1 for conductive layer)
The metal oxide particles used in the preparation of the coating liquid for the conductive layer were obtained from 204 parts of titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P). Phosphorus (Pn) -doped tin oxide (SnO ₂ ) particles (phosphorus-containing tin oxide fine particles) described in Example 1 of Kaihei 06-222600 (powder resistivity: 25 Ω · cm, tin oxide ( The amount of phosphorus (P) doped in SnO ₂ ) (doping amount: 1% by mass)) The coating for the conductive layer was performed in the same manner as in the preparation example of the coating liquid 1 for the conductive layer, except that it was changed to 204 parts. Liquid C1 was prepared. The average particle diameter of the metal oxide particles in the conductive layer coating liquid C1 was 0.48 μm.

(Preparation example of coating liquid C2 for conductive layer)
The metal oxide particles used in the preparation of the coating liquid for the conductive layer were obtained from 204 parts of titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P). Tin (Wn) -doped tin oxide (SnO ₂ ) particles described in Example 1 of Kaikai 2003-316059 (7.1 mol% of tungsten element (W) with respect to tin oxide (SnO ₂ )) Except for changing to 204 parts of doped tin oxide ultrafine particles), a conductive layer coating solution C2 was prepared in the same manner as in the preparation example of the conductive layer coating solution 1. The average particle diameter of the metal oxide particles in the conductive layer coating liquid C2 was 0.65 μm.

(Preparation example of coating liquid C3 for conductive layer)
The metal oxide particles used in the preparation of the coating liquid for the conductive layer were obtained from 204 parts of titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P). Titanium oxide (TiO ₂ ) particles (oxygen-deficient SnO ₂ -coated TiO ₂ particles) coated with oxygen-deficient tin oxide (SnO ₂ ) as described in the preparation of coating liquid A for conductive layers in Japanese Unexamined Patent Application Publication No. 2007-047736 ) (Powder resistivity: 100 Ω · cm, tin oxide (SnO ₂ ) coverage: 40 mass%) The conductive layer was prepared in the same manner as in the preparation example of the conductive layer coating solution 1 except that the content was changed to 204 parts. Coating solution C3 was prepared. The average particle diameter of the metal oxide particles in the conductive layer coating solution C3 was 0.36 μm.

(Preparation example of coating liquid C4 for conductive layer)
The metal oxide particles used in the preparation of the coating liquid for the conductive layer were obtained from 204 parts of titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P). Titanium oxide (TiO ₂ ) particles (antimony oxide-containing tin oxide coating layer) coated with tin oxide (SnO ₂ ) doped with antimony (Sb) described in Comparative Example 1 of Kaihei 11-007145 The conductive layer coating solution C4 was prepared in the same manner as in the preparation example of the conductive layer coating solution 1 except that the titanium oxide powder was changed to 204 parts (powder resistivity: 200 Ω · cm). The average particle size of the metal oxide particles in the conductive layer coating solution C4 was 0.36 μm.

(Preparation Example of Coating Liquid C5 for Conductive Layer)
The metal oxide particles used in the preparation of the coating liquid for the conductive layer were obtained from 204 parts of titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P). Barium sulfate (BaSO ₄ ) particles (containing a fluorine-containing tin oxide coating layer) coated with tin oxide (SnO ₂ ) doped with fluorine (F) described in Example 3 of Kaihei 07-295270 In 204 parts (barium sulfate fine particles) (powder resistivity: 40 Ω · cm, coverage: 50% by mass, amount of fluorine (F) doped in tin oxide (SnO ₂ ): 9% by mass) Except for the change, a conductive layer coating solution C5 was prepared in the same manner as in the preparation example of the conductive layer coating solution 1. The average particle diameter of the metal oxide particles in the conductive layer coating solution C5 was 0.47 μm.

(Preparation example of coating liquid C6 for conductive layer)
The metal oxide particles used in the preparation of the coating liquid for the conductive layer were obtained from 204 parts of titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P). Titanium oxide particles (oxygen-deficient SnO ₂ -coated TiO ₂ particles) coated with oxygen-deficient tin oxide (SnO ₂ ) (powder) described in the preparation of coating liquid A for conductive layers in Japanese Unexamined Patent Publication No. 2007-047736 Resistivity: 100 Ω · cm, tin oxide (SnO ₂ ) coverage: 40% by mass) Except for changing to 240 parts, the conductive layer coating solution C6 was prepared in the same manner as in the preparation example of the conductive layer coating solution 1. Was prepared. The average particle diameter of the metal oxide particles in the conductive layer coating liquid C6 was 0.36 μm.

(Preparation example of coating liquid C7 for conductive layer)
The metal oxide particles used in the preparation of the coating liquid for the conductive layer were obtained from 204 parts of titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P). Barium sulfate (BaSO ₄ ) particles coated with tin oxide (SnO ₂ ) doped with (P) (powder resistivity: 40 Ω · cm, coverage of tin oxide (SnO ₂ ): 35% by mass, The amount of phosphorus (P) doped in tin oxide (SnO ₂ ) (doping amount: 3% by mass) was changed to 204 parts, and the same operation as in the preparation example of the conductive layer coating solution 1 was performed. Layer coating solution C7 was prepared. The average particle diameter of the metal oxide particles in the conductive layer coating solution C7 was 0.40 μm.

<Example of production of electrophotographic photoreceptor>
(Example of production of electrophotographic photoreceptor 1)
An aluminum cylinder (JIS-A3003, aluminum alloy) having a length of 246 mm and a diameter of 24 mm manufactured by a manufacturing method including an extrusion process and a drawing process was used as a support.

In an environment of 23 ° C./60% RH, the conductive layer coating solution 1 is dip coated on the support and dried and thermally cured at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 30 μm. did. When the volume resistivity of the conductive layer was measured by the method described above, it was 2.1 × 10 ⁹ Ω · cm.

  Next, 4.5 parts of N-methoxymethylated nylon (trade name: Toresin EF-30T, manufactured by Teikoku Chemical Industry Co., Ltd.) and copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) An undercoat layer coating solution was prepared by dissolving 5 parts in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol. The undercoat layer coating solution was dip-coated on the conductive layer, and dried at 70 ° C. for 6 minutes to form an undercoat layer having a thickness of 0.85 μm.

  Next, the Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction are 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 °. A crystalline form of hydroxygallium phthalocyanine crystal (charge generating substance) having a strong peak, 10 parts, polyvinyl butyral (trade name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) and 250 parts of cyclohexanone having a diameter of 0.8 mm In a sand mill using glass beads, a dispersion treatment was performed under the condition of dispersion treatment time: 3 hours, and then 250 parts of ethyl acetate was added to prepare a charge generation layer coating solution. This coating solution for charge generation layer was dip-coated on the undercoat layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.12 μm.

ならびに、ポリカーボネート（商品名：Ｚ２００、三菱エンジニアリングプラスチックス（株）製）１０部を、ジメトキシメタン３０部／クロロベンゼン７０部の混合溶剤に溶解させることによって、電荷輸送層用塗布液を調製した。この電荷輸送層用塗布液を電荷発生層上に浸漬塗布し、これを３０分間１１０℃で乾燥させることによって、膜厚が１２μｍの電荷輸送層を形成した。
このようにして、電荷輸送層が表面層である電子写真感光体１を製造した。 Next, 4.8 parts of an amine compound (charge transport material) represented by the following formula (CT-1) and 3.2 parts of an amine compound (charge transport material) represented by the following formula (CT-2),

Also, 10 parts of polycarbonate (trade name: Z200, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was dissolved in a mixed solvent of 30 parts of dimethoxymethane / 70 parts of chlorobenzene to prepare a charge transport layer coating solution. The charge transport layer coating solution was dip coated on the charge generation layer and dried at 110 ° C. for 30 minutes to form a charge transport layer having a thickness of 12 μm.
Thus, an electrophotographic photoreceptor 1 having a charge transport layer as a surface layer was produced.

When the dielectric loss tan δ at a frequency of 1.0 × 10 ³ Hz of the electrophotographic photosensitive member 1 was measured by the above-described method, it was 7 × 10 ⁻³ .

(Production examples of electrophotographic photoreceptors 2 to 20 and C1 to C7)
The electrophotographic photosensitive member 1 except that the conductive layer coating solution used in the production of the electrophotographic photosensitive member was changed from the conductive layer coating solution 1 to the conductive layer coating solutions 2 to 20 and C1 to C7, respectively. Electrophotographic photoreceptors 2 to 20 and C1 to C7, in which the charge transport layer is a surface layer, were produced in the same manner as in the above production example. The dielectric loss tan δ at a frequency of 1.0 × 10 ³ Hz of the electrophotographic photoreceptors 2 to 20 and C1 to C7 was measured by the method described above in the same manner as the electrophotographic photoreceptor 1. Also, the volume resistivity of the electroconductive layers of electrophotographic photoreceptors 2 to 20 and C1 to C7 was measured in the same manner as the electroconductive layer of electrophotographic photoreceptor 1 as described above. The results are shown in Table 2.

(Example of production of electrophotographic photoreceptor 21)
The charge generation material used in forming the charge generation layer of the electrophotographic photosensitive member was 7.5 °, 9.9 °, 16.3 of Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction. From 10 parts of a crystalline form of hydroxygallium phthalocyanine having strong peaks at °, 18.6 °, 25.1 ° and 28.3 °, the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction is 9. Production example of electrophotographic photoreceptor 1 except that the crystal form of oxytitanium phthalocyanine crystal having strong peaks at 0 °, 14.2 °, 17.9 °, 23.9 ° and 27.1 ° was changed to 10 parts. In the same manner as in Example 1, an electrophotographic photoreceptor 21 having a charge transport layer as a surface layer was produced. The dielectric loss tan δ at a frequency of 1.0 × 10 ³ Hz of the electrophotographic photosensitive member 21 and the volume resistivity of the conductive layer thereof were measured by the method described above in the same manner as the electrophotographic photosensitive member 1. The results are shown in Table 2.

に変更した以外は、電子写真感光体１の製造例と同様の操作で、電子写真感光体２２を製造した。電子写真感光体２２の周波数１．０×１０^３Ｈｚにおける誘電損失ｔａｎδおよびその導電層の体積抵抗率を、電子写真感光体１と同様、前述の方法で測定した。その結果を表２に示す。 (Example of production of electrophotographic photosensitive member 22)
The amount of the amine compound represented by the above formula (CT-1) used in forming the charge transport layer of the electrophotographic photosensitive member was changed from 4.8 parts to 7 parts, and the above formula (CT-2) 3.2 parts of an amine compound represented by the formula 1 part of an amine compound represented by the following formula (CT-3)

An electrophotographic photosensitive member 22 was produced in the same manner as in the production example of the electrophotographic photosensitive member 1 except that the electrophotographic photosensitive member 1 was changed. The dielectric loss tan δ at a frequency of 1.0 × 10 ³ Hz of the electrophotographic photosensitive member 22 and the volume resistivity of the conductive layer thereof were measured by the method described above in the same manner as the electrophotographic photosensitive member 1. The results are shown in Table 2.

(Example of production of electrophotographic photoreceptor R1)
An electrophotographic photoreceptor R1 was produced in the same manner as in the production example of the electrophotographic photoreceptor 1 except that the conductive layer was not formed during the production of the electrophotographic photoreceptor. The dielectric loss tan δ at a frequency of 1.0 × 10 ³ Hz of the electrophotographic photosensitive member R1 was measured by the method described above in the same manner as the electrophotographic photosensitive member 1. The results are shown in Table 2.

(Examples 1-22, Reference Example 1 and Comparative Examples 1-7)
The electrophotographic photosensitive members 1 to 22, R1 and C1 to C7 are respectively mounted on a laser beam printer (trade name: HP Laserjet P1505) manufactured by Hewlett-Packard Co., and placed in a low temperature and low humidity (15 ° C./10% RH) environment. Then, a paper endurance test was performed and images were evaluated. In the paper passing durability test, a printing operation was performed in an intermittent mode in which character images with a printing rate of 2% were output one by one on letter paper, and 3000 images were output.

  Then, two samples for image evaluation (solid white image and halftone image of 1-dot Keima pattern) were output at the start of the paper passing durability test and after the output of 3000 images.

The evaluation of the image was performed with respect to charging stripes, spots (black spots), and fog. The charging streak is evaluated by a halftone image of a 1-dot Keima pattern, and the standard is as follows.
A: No charging streak at all.
B: Almost no charging streaks.
C: A slight charge streak is observed.
D: Charging streaks are observed.
E: Charging streaks are clearly understood.
The evaluation of fog and black spots was performed using a solid white image.
The results are shown in Table 3.

  In addition to the electrophotographic photosensitive members 1-22, R1, and C1-C7 subjected to the paper passing durability test, another electrophotographic photosensitive members 1-22, R1, and C1-C7 are prepared, A paper passing durability test similar to the above was performed at high humidity (30 ° C./80% RH), and evaluations other than charging streaks were performed.

1 Electrophotographic photosensitive member 2 Axis 3 Charging means (primary charging means)
4 exposure light (image exposure light)
5 Developing means 6 Transfer means (transfer roller, etc.)
7 Cleaning means (cleaning blade, etc.)
8 Fixing means 9 Process cartridge 10 Guide means 11 Pre-exposure light P Transfer material (paper, etc.)

Claims (4)

In an electrophotographic photosensitive member having a support, a conductive layer formed on the support, and a photosensitive layer formed on the conductive layer,
Conductive layer, a binder material, and contains titanium oxide particles coated with tin oxide Li down is doped,
Dielectric loss tanδ at frequency 1.0 × ¹⁰ 3 Hz of the electrophotographic photosensitive member, 5 × ^{10 -3} or more 2 × ^{10 -2} electrophotographic photoreceptor, characterized in der Rukoto below. The electrophotographic photosensitive member according to claim 1, wherein the conductive layer has a volume resistivity of 5.0 × 10 ⁸ Ω · cm to 1.0 × 10 ¹³ Ω · cm.   3. The electrophotographic photosensitive member according to claim 1 and at least one means selected from the group consisting of a charging means, a developing means, a transfer means and a cleaning means are integrally supported and detachable from the main body of the electrophotographic apparatus. Process cartridge characterized by being.   An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, and a charging unit, an exposure unit, a developing unit, and a transfer unit.

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