JP2005037931A - Electrostatic chargeable material, process cartridge, and electrophotographic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging member that can output superior defectless images (with horizontal stripes especially suppressed), even in an electrophotographic system which can use two or more process speeds. <P>SOLUTION: The charging member has one or more layers for covering layer on a support body. When denoting the ten-point average surface roughness of the surface of this material as Rz [μm], the height of the projections on the surface of this material as H [μm], and its area as Sa [μm<SP>2</SP>], and further making Sb [μm<SP>2</SP>] represent the area surrounded by the projections other than the above projections and other projections higher than H [μm] but not including the projections which exceed 0.5H [μm] in the charging member having one or more cover layers on the base, Rz, H, Sa and Sb satisfy a specific relation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

An image forming apparatus employing an electrophotographic system, that is, an electrophotographic apparatus, generally includes an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit.
Further, as this charging means, a voltage (a voltage of only DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage) is applied to a charging member that is in contact with or close to the surface of the electrophotographic photosensitive member. Many systems that charge the surface of the photoreceptor are used.
As a voltage to be applied to the charging member, when a voltage obtained by superimposing an AC voltage on a DC voltage is used, an AC power source is required, leading to an increase in size and cost of the electrophotographic apparatus, an increase in power consumption, From the above viewpoint, the voltage applied to the charging member may be only a DC voltage because the durability of the charging member and the electrophotographic photosensitive member may decrease due to the large amount of ozone generated by the use of alternating current. preferable.

In recent years, there has been a demand for higher image quality for electrophotographic devices. However, when a conventional charging member is used, depending on certain conditions (applied voltage, image output environment, output image pattern, etc.) May cause white or black streaks or spots, density unevenness due to foreign matter adhering to the surface of the charging member or uneven adhesion of foreign matter, or streaks or spots due to the shape of the surface of the charging member. It may occur. These problems were particularly likely to occur when the voltage applied to the charging member was a DC voltage only.
In recent years, there has been a demand for further enhancement of durability in electrophotographic apparatuses, and it is a matter of course that further enhancement of durability is required for charging members mounted thereon.

For example, in JP-A-07-199593 (Patent Document 1) and JP-A-2000-214657 (Patent Document 2), the charging uniformity and durability are improved by controlling the shape of the surface of the charging member. Alternatively, a technique for achieving reduction of image defects is disclosed.
Japanese Patent Laid-Open No. 07-199593 JP 2000-214657 A

Currently, further added value is required for an electrophotographic apparatus on the premise of high image quality / high durability. As an example of the added value, there is a correspondence with media (transfer material such as paper). “Media correspondence” refers to forming good images on various transfer materials.
For example, when a presentation or the like is performed, a transparent PET film (OHT) is often used as a transfer material, and an image is often formed thereon. In addition, there are increasing opportunities to output electronic images taken with digital cameras, etc., with printers, and to copy photos with photocopiers. However, when outputting photographic images, surface treatment was performed as a transfer material. Special paper such as paper and high gloss paper is often used.
In addition, a special paper that is thick and small like a postcard is frequently used.
OHT and special paper are often different in thickness, size, and material compared to plain paper, and in order to form a good image on these, compared to the case of using plain paper as a transfer material. Often, the process speed (PS) is slowed down.

  In order to cope with various types of transfer materials that differ in thickness and size, and in order to be able to form an appropriate image according to the transfer material, one electrophotographic apparatus can be used for a plurality of types. It is preferable that the process speed can be set. Specifically, for example, the process speed of 1/2 speed, 1/3 speed, and 1/4 speed can be set with reference to the standard speed. More specifically, for example, when plain paper is used as the transfer material, the process speed is 94 mm / s (standard speed), and when OHT is used as the transfer material, the process speed is 31 mm / s (1 / 3rd speed) is used by switching.

However, as a result of studies by the present inventors, it has been found that such a difference in process speed has a great influence on the charging uniformity, and consequently the uniformity of the output image (image uniformity).
In order to obtain a uniform charged state of the electrophotographic photosensitive member, the amount of charge per unit area of the surface of the electrophotographic photosensitive member needs to be constant. At this time, if the process speed is high, the amount of charge supplied to the surface of the electrophotographic photosensitive member per unit time must be large, and if the process speed is slow, the amount of charge supplied may be small. That is, if the process speed of the electrophotographic apparatus to be applied is determined, the charging member may be developed accordingly.

However, when the applied electrophotographic apparatus is an electrophotographic apparatus in which a plurality of process speeds can be set, even if high charging uniformity and, in turn, high image uniformity can be achieved at a certain process speed, the process speed can be further increased. However, when switching to a low speed, the discharge of the charging member becomes an overdischarged state, a partial overcharged state occurs on the surface of the electrophotographic photosensitive member, and white horizontal stripes may occur on the output image, In addition, when the process speed is switched to a higher speed, the charging member discharges in an insufficiently discharged state, resulting in a partial insufficiently charged state on the surface of the electrophotographic photosensitive member, resulting in black horizontal streaks on the output image. May occur.
This problem is particularly likely to occur when image output is performed in a low humidity environment. This problem is particularly likely to occur when the voltage applied to the charging member is a DC voltage only (when an AC voltage that has a smoothing effect is not used as the voltage applied to the charging member).

In the case of an electrophotographic apparatus capable of setting a plurality of types of process speeds, static / dynamic contact state between the electrophotographic photosensitive member and the charging member, torque, rubbing state, voltage application state to the charging member Therefore, various stresses are easily applied to the charging member as compared with the electrophotographic apparatus in which the process speed is set to a single value. For this reason, the surface of the charging member is more easily worn, deterioration of the charging member is promoted, and it is difficult to maintain high image quality.
This problem is particularly likely to occur when image output is performed in a low humidity environment or when the voltage applied to the charging member is a DC voltage only.
Further, it has been found that these problems also occur with the charging members disclosed in Japanese Patent Application Laid-Open Nos. 07-199593 and 2000-214657.

By the way, high image quality can be achieved to some extent by improving charging uniformity. However, as described in Japanese Patent Application Laid-Open No. 2000-214657, black spots, white spots, and the like appearing on the output image can be achieved. It is clear that some image defects are caused by charging members. This is due to the convex portions and concave portions on the surface of the charging member.
Japanese Patent Application Laid-Open No. 2000-214657 discloses a charging member characterized in that there is no protrusion of 5 μm or more on the surface of the charging member, but this charging member prevents black spots and white spots on the output image. Although it is possible, charging uniformity corresponding to a plurality of kinds of process speeds cannot be achieved.
It was also clarified that when the voltage applied to the charging member is a DC voltage only, image defects due to defects on the surface of the charging member become very conspicuous as well as charging uniformity. .

  The object of the present invention is to output a good image free from image defects (especially the occurrence of horizontal stripes) even if the applied electrophotographic apparatus is an electrophotographic apparatus capable of setting a plurality of process speeds. Another object is to provide a charging member that can be used, and to provide a process cartridge and an electrophotographic apparatus having such a charging member.

を満たし、
該帯電部材の表面の、Ｒｚとの関係が式（２）および（３）

を満たすＨ［μｍ］を高さとする凸部分の面積Ｓａ［μｍ^２］が式（４）

を満たし、
該帯電部材の表面の、Ｒｚとの関係が式（２）および（３）を満たすＨ［μｍ］を高さとする凸部分と該凸部分の高さ以上の高さの他の凸部分とに囲まれ、かつ、該凸部分の高さの０．５倍を超える高さの凸部分を内側に含まない領域の面積Ｓｂ［μｍ^２］が式（５）

を満たすことを特徴とする帯電部材である。 In the charging member having one or more coating layers on the support,
When the 10-point average surface roughness of the surface of the charging member is Rz [μm], Rz is the formula (1)

The filling,
The relationship between the surface of the charging member and Rz is expressed by the equations (2) and (3).

The area Sa [μm ² ] of the convex portion having a height of H [μm] satisfying the equation (4)

The filling,
On the surface of the charging member, a convex portion whose height is H [μm] whose relation to Rz satisfies the expressions (2) and (3), and other convex portions whose height is higher than the height of the convex portion. The area Sb [μm ² ] of a region that is enclosed and does not include a convex portion having a height that exceeds 0.5 times the height of the convex portion is expressed by the equation (5).

The charging member is characterized by satisfying the above.

In the charging member having one or more coating layers on a support, the coating layer serving as a surface layer of the charging member contains polymer compound particles, and When the average particle size of the polymer compound particles is A [μm], 2 ≦ A ≦ 50, and the particle size distribution range of the polymer compound particles exceeds 0 [μm] and is 7 A [μm] or less. A charging member characterized by the above.
The present invention also provides a process cartridge and an electrophotographic apparatus having the charging member.

  According to the present invention, even when the applied electrophotographic apparatus is an electrophotographic apparatus in which a plurality of process speeds can be set, a good image free from image defects (particularly the occurrence of horizontal stripes is suppressed) is output. The charging member can be provided, and a process cartridge and an electrophotographic apparatus having such a charging member can be provided.

式（６）中のＤはＤ＝Σｄｉ／εｉ＝ｄｃ／εｃ＋ｄｐ／εｐであり、ｄｃは帯電部材の支持体上に形成された層（１層または２層以上）の厚さの合計（合計膜厚）［ｍ］であり、ｄｐは電子写真感光体の支持体上に形成された層（１層または２層以上）の厚さの合計（合計膜厚）［ｍ］であり、εｃは帯電部材の支持体上に形成された層の比誘電率であり、εｐは電子写真感光体の支持体上に形成された層の比誘電率であり、Ｇは点Ｘと点Ｙとの間の距離（ギャップ）［ｍ］であり、Ｖｘｙは点Ｘと点Ｙとの間での電位差［Ｖ］であり、Ｖｐａは式（７）および図１に示すパッシェンの法則から導き出される放電開始電圧［Ｖ］である。

That the charging member charges the surface of the electrophotographic photosensitive member means that a discharge from the charging member to the surface of the electrophotographic photosensitive member occurs and the charge moves. When a point X on the surface of the charging member and a point where a line extending the radius of the charging member passing through the point X intersects the surface of the electrophotographic photosensitive member is a point Y, between the point X and the point Y When the electric potential difference Vxy exceeds the Paschen discharge limit voltage (discharge start voltage) Vpa, discharge occurs, and the charge ΔQ moves to the surface of the electrophotographic photosensitive member and the reverse charge −ΔQ moves to the surface of the charging member. The sum of ΔQ is the charge Q accumulated on the surface of the electrophotographic photosensitive member, and the potential V of the surface of the electrophotographic photosensitive member is V = Q / C (C is formed on the support of the electrophotographic photosensitive member. It can be calculated from the relationship of the capacitance of the layer. Here, the charge (discharge charge density) ΔQ can be calculated from the equation (6).

D in the formula (6) is D = Σdi / εi = dc / εc + dp / εp, and dc is the total thickness (one layer or two layers or more) formed on the support of the charging member (total) Film thickness) [m], dp is the total (total film thickness) [m] of the layers (one layer or two or more layers) formed on the support of the electrophotographic photosensitive member, and εc is The relative permittivity of the layer formed on the support of the charging member, εp is the relative permittivity of the layer formed on the support of the electrophotographic photosensitive member, and G is between the point X and the point Y Distance (gap) [m], Vxy is the potential difference [V] between point X and point Y, and Vpa is the discharge start voltage derived from equation (7) and Paschen's law shown in FIG. [V].

According to the equation (6), the charge ΔQ moved by the discharge depends on G, that is, the gap between the charging member and the electrophotographic photosensitive member. When the surface of the charging member is smooth (when the distance to the surface of the electrophotographic photosensitive member is uniform), in the direction orthogonal to the moving direction of the surface of the charging member (hereinafter also simply referred to as “orthogonal direction”), Theoretically, ΔQ (and −ΔQ) is uniformly moved between the charging member and the electrophotographic photosensitive member by discharge.
However, in reality, it is very difficult to make the film thickness of the coating layer and the state of the various materials constituting the coating layer uniform, so it is very difficult to make the surface of the charging member uniform. In practice, ΔQ (and −ΔQ) cannot be moved completely uniformly by discharge. That is, a portion that may affect the discharge always exists on the surface of the charging member.
The fact that the above-described charging uniformity depends on the process speed means that the state of the discharge by the charging member depends on the process speed, and therefore, there is a possibility of affecting the discharge on the surface of the charging member. Which part of the parts actually causes a discharge failure (overdischarge or insufficient discharge) is determined by the process speed of the electrophotographic apparatus to which the charging member is applied.
If the electrophotographic apparatus to which the charging member is applied is an electrophotographic apparatus in which the process speed is set to a single value, the charging member is designed and optimized according to the process speed. It is possible to suppress image defects caused by defects and / or discharge defects.

  However, when the electrophotographic apparatus to which the charging member is applied is an electrophotographic apparatus in which a plurality of types of process speeds can be set, the charging member is designed according to a certain type of process speed to Discharge failure when image formation is performed at a process speed other than the one process speed even though the discharge failure and / or image defect caused by the discharge failure can be suppressed when image formation is performed at a different process speed. And / or it is difficult to suppress image defects due to defective discharge. In particular, it becomes extremely difficult when a plurality of types of process speeds exceed the range of 10% ({(high speed PS−low speed PS) / low speed PS} × 100).

When a part of the surface of the charging member is a portion that causes overdischarge (overdischarge portion), a phenomenon in which electric charge flows out from the overdischarge portion to a portion that is adjacent to the overdischarge portion in a direction orthogonal to the portion where originally no overdischarge occurs. Therefore, the overdischarge portion expands in the orthogonal direction. On the other hand, when a part of the surface of the charging member is a portion where discharge is insufficient (discharge shortage portion), the charge flows out from the portion where the discharge shortage does not occur normally adjacent to the discharge shortage portion. As a phenomenon occurs, the insufficient discharge portion expands in the orthogonal direction. In addition, the larger the range of the portion where the overdischarge or the insufficient discharge is adjacent to the overdischarge portion or the insufficient discharge portion, and the higher the smoothness of the surface of the charging member, the higher the surface of the overdischarge portion or the insufficient discharge portion. Expansion will progress. If the enlargement of the overdischarge portion or the insufficient discharge portion becomes large, white and black horizontal stripes (orthogonal stripes) appear conspicuously in the output image.
In other words, if the surface of the charging member is roughened to some extent, the enlargement of the overdischarged portion or the insufficiently discharged portion is suppressed, thereby suppressing the occurrence of horizontal streaks in the output image (the horizontal streaks cannot be visually recognized on the output image). To a certain extent).

  On the other hand, it is not the case that the surface of the charging member is simply roughened. Roughening the surface of the charging member means that the charge ΔQ that moves due to the discharge differs depending on the location where the discharge occurs, but in order to achieve charging uniformity, the sum of ΔQ, that is, electrons This is because the charge Q accumulated on the surface of the photographic photoreceptor must be uniform (so uniform that an image defect cannot be visually recognized). For example, if the surface of the charging member is excessively roughened and there are very large convex portions or concave portions on the surface of the charging member, white or black spots caused by the convex portions or concave portions appear in the output image. Appears prominently.

を満たし、該帯電部材の表面の、Ｒｚとの関係が式（２）および（３）

を満たすＨ［μｍ］を高さとする凸部分の面積Ｓａ［μｍ^２］が式（４）

を満たし、該帯電部材の表面の、Ｒｚとの関係が式（２）および（３）を満たすＨ［μｍ］を高さとする凸部分と該凸部分の高さ以上の高さの他の凸部分とに囲まれ、かつ、該凸部分の高さの０．５倍を超える高さの凸部分を内側に含まない領域の面積Ｓｂ［μｍ^２］が式（５）

を満たす帯電部材
とすることで、または、
＜ＩＩ＞ 支持体上に被覆層を１層以上有する帯電部材であって、該被覆層のうち、該帯電部材の表面層となる被覆層が、高分子化合物粒子を含有し、かつ、該高分子化合物粒子の平均粒径をＡ［μｍ］としたとき２≦Ａ≦５０であり、該高分子化合物粒子の粒径分布範囲が０［μｍ］を超えて７Ａ［μｍ］以下である帯電部材
とすることで解決できることがわかった。 式（２）、（３）および（５）中のＨは、図２に示すように、凸部分の周囲の最下点を基準とした高さＨである（つまりＨ’ではない）。
式（４）中のＳａは、図３に示すように、凸部分の底面を完全に覆う最小の円３１の面積Ｓａである。
式（５）中のＳｂは、図４に示すように、凸部分の頂点および該凸部分の高さ以上の高さの他の凸部分の頂点のすべてを通る円４１の面積Ｓｂである。図４中、４２は凸部分であり、４３および４４は他の凸部分であり、４５は該凸部分の高さの０．５倍以下の高さの凸部分（の１つ）である。 As a result of intensive studies, the present inventors have found that the above problem is that the charging member has <I> one or more coating layers on the support, and the surface roughness of the charging member is 10 points average. When Rz [μm], Rz is the formula (1)

And the relationship between the surface of the charging member and Rz is expressed by formulas (2) and (3)

The area Sa [μm ² ] of the convex portion having a height of H [μm] satisfying the equation

And a convex portion having a height of H [μm] whose relation to Rz satisfies the formulas (2) and (3) on the surface of the charging member and other convex portions having a height equal to or higher than the height of the convex portion. The area Sb [μm ² ] of a region that is surrounded by the portion and does not include a convex portion having a height exceeding 0.5 times the height of the convex portion inside is expressed by the equation (5).

Or a charging member that satisfies
<II> A charging member having one or more coating layers on a support, wherein the coating layer serving as a surface layer of the charging member contains polymer compound particles, and When the average particle size of the molecular compound particles is A [μm], 2 ≦ A ≦ 50, and the particle size distribution range of the polymer compound particles exceeds 0 [μm] and is 7 A [μm] or less. It was found that this can be solved. H in the equations (2), (3), and (5) is a height H based on the lowest point around the convex portion (that is, not H ′), as shown in FIG.
Sa in the formula (4) is the area Sa of the smallest circle 31 that completely covers the bottom surface of the convex portion, as shown in FIG.
As shown in FIG. 4, Sb in the formula (5) is an area Sb of a circle 41 passing through all of the vertices of the convex portion and the vertices of the other convex portion having a height equal to or higher than the height of the convex portion. In FIG. 4, 42 is a convex portion, 43 and 44 are other convex portions, and 45 is a convex portion having a height not more than 0.5 times the height of the convex portion.

In the present invention, the 10-point average surface roughness Rz [μm] of the surface of the charging member is preferably 2 μm or more, more preferably 4 μm or more, and even more preferably 6 μm or more. If Rz is too small, it will be difficult to satisfy charging uniformity. On the other hand, the 10-point average surface roughness Rz [μm] of the surface of the charging member is preferably 50 μm or less. If Rz is too large, the toner (toner particles and external additives) adheres to the charging member due to long-term use, and it becomes easy to cause dirt or unevenness of the dirt, and the initial charge uniformity can be maintained for a long time. It becomes difficult.
The charging member described in Japanese Patent Application Laid-Open No. 2000-214657 has a prescribed size of protrusions on the surface (protrusions caused by particles in the atmosphere when the charging member is manufactured (particle size distribution range is unknown)). Although it is a charging member, the invention described in the publication is intended to smooth the surface of the charging member. Therefore, in the charging member described in the publication, a plurality of process speeds can be set. It is difficult to satisfy charging uniformity corresponding to the electrophotographic apparatus.
In addition, the surface control of the charging member in the invention described in Japanese Patent Application Laid-Open No. 07-199593 is control by surface polishing of the rubber member and shrinkage of the urethane paint, and the particles are contained in the coating layer that becomes the surface layer of the charging member. It is not control by things. Further, it is considered that the surface property of the charging member of the present invention cannot be achieved only by the expression control described in JP-A-07-199593. Therefore, it is difficult for the charging member described in Japanese Patent Application Laid-Open No. 07-199593 to satisfy charging uniformity corresponding to an electrophotographic apparatus capable of setting a plurality of types of process speeds.

The charging member of the present invention is a charging member having one or more coating layers on a support.
Conventionally known layers can be employed as the coating layer, such as resins, rubbers (natural rubber (which may be vulcanized) or synthetic rubbers), thermoplastic elastomers, and the like. And a layer using an elastomer such as a binder as a binding material.
Examples of the resin include fluorine resin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene / butylene-olefin copolymer (SEBC), and olefin-ethylene / butylene-olefin copolymer (CEBC). Is mentioned.
Synthetic rubbers include ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer rubber (SBR), silicone rubber, urethane rubber, isoprene rubber (IR), butyl rubber (BR), acrylonitrile-butadiene copolymer rubber. (NBR), chloroprene rubber (CR) and the like.
As thermoplastic elastomers, polyolefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, fluororubber-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, ethylene Examples thereof include a vinyl acetate thermoplastic elastomer, a polyvinyl chloride thermoplastic elastomer, and a chlorinated polyethylene thermoplastic elastomer.
These may be used alone or in combination of two or more as a mixture or copolymer.

In the charging member of the present invention, two or more coating layers can be provided on the support.
As a support for the charging member, it is only necessary to have conductivity (conductive support). For example, a metallic (alloy) support such as iron, copper, stainless steel, aluminum, or nickel is used. it can. In addition, for the purpose of imparting scratch resistance to these surfaces, plating treatment or the like may be performed as long as the conductivity is not impaired.
When using the charging member in contact with the electrophotographic photosensitive member, the power supply to the electrophotographic photosensitive member is improved, and the uniform adhesion between the electrophotographic photosensitive member and the charging member is improved. In addition, a coating layer having conductivity and elasticity (hereinafter, also referred to as “elastic coating layer”) is provided between the coating layer (hereinafter also referred to as “surface coating layer”) serving as the surface layer of the charging member and the support. It is preferable to provide it.

Examples of the layer structure of the charging member are shown in FIGS.
The charging member shown in FIG. 5 is a roller-shaped charging member, and is a one-layered charging member having a support a and a surface coating layer c formed on the support a.
The charging member shown in FIG. 6 is a roller-shaped charging member, and includes a support body a, an elastic coating layer b formed on the support body a, and a surface coating layer c formed on the elastic coating layer b. A charging member having a layer structure.
The charging member shown in FIG. 7 is a roller-shaped charging member, and a resistance layer (one type of coating layer) d is provided between the elastic coating layer b and the surface coating layer c of the charging member shown in FIG. A charging member having a layer structure.
The charging member shown in FIG. 8 is a roller-shaped charging member, and a second resistance layer (one type of coating layer) e is provided between the resistance layer d and the surface coating layer c of the charging member shown in FIG. In addition, the charging member has a four-layer structure.

The shape of the charging member of the present invention is preferably a roller shape. However, as exemplified in FIGS. 9 to 12, various shapes such as a sheet shape, a belt shape, a film shape, and a plate shape can be adopted. In addition, each of the above-described layer configurations can be adopted. Hereinafter, the roller-shaped charging member is also referred to as a “charging roller”.
A roller-shaped charging member, that is, a charging roller, has a shape in which the central portion in the longitudinal direction is the thickest and becomes thinner toward both ends in the longitudinal direction from the viewpoint of improving the uniform adhesion between the charging roller and the electrophotographic photosensitive member. It is preferable to form a so-called crown shape. In general, the charging roller is brought into contact with the electrophotographic photosensitive member by applying a predetermined pressing force to both end portions of the support, and the pressing force is small in the central portion in the longitudinal direction, and becomes closer to both end portions in the longitudinal direction. Therefore, the density unevenness may occur between the image corresponding to the central portion and the images corresponding to both end portions. The crown shape is formed to prevent this.
When the charging member is used in contact with the electrophotographic photosensitive member or other member, the surface coating layer has a high releasability so as not to contaminate the electrophotographic photosensitive member or other member. It is preferable to use a material. From this viewpoint, it is preferable to use a resin as the binding material for the surface coating layer.

  As a method for controlling the surface state of the charging member so as to satisfy the formulas (1) to (5), a method in which particles or fibers (natural fibers, chemical fibers, glass fibers, etc.) are contained in the surface coating layer, or polishing The surface of the surface coating layer (= charged) by pressing tape or paper with particles or abrasive particles adhered to the surface of the surface coating layer, or by hitting the abrasive particles against the surface of the surface coating layer (sandblasting method) And a method of polishing the surface of the member. Among these, from the viewpoint of ease of surface control of the charging member and work efficiency, a method of incorporating particles and fibers into the surface coating layer, particularly a method of incorporating particles into the surface coating layer is preferable. For example, a method of polishing the surface of the charging member after incorporating particles or fibers into the surface coating layer may be employed.

The particles contained in the surface coating layer are roughly classified into conductive particles and insulating particles. In the present invention, “conductive particle” means a particle having a volume resistivity of 1 × 10 ¹⁰ Ω · cm or less, and “insulating particle” means a volume resistivity of 1 × 10 ¹⁰ Ω · cm. Means more particles. In the surface coating layer, either one of conductive particles or insulating particles may be used, or both may be used in combination.
Examples of the conductive particles include particles of carbon black, tin oxide, titanium oxide, zinc oxide, barium sulfate, copper, aluminum, nickel, and the like.

Insulating particles include polymer compound particles such as polyamide resin, silicone resin, fluorine resin, (meth) acrylic resin, styrene resin, phenol resin, polyester resin, melamine resin, urethane resin, olefin resin, epoxy resin, And resin particles such as copolymers, modified products and derivatives thereof, ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer rubber (SBR), silicone rubber, urethane rubber, isoprene rubber (IR ), Butyl rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR), polyolefin thermoplastic elastomer, urethane thermoplastic elastomer, polystyrene thermoplastic elastomer, fluorine rubber thermal Plastic error Thermoplastic elastomer particles such as tomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, ethylene vinyl acetate-based thermoplastic elastomers, polyvinyl chloride-based thermoplastic elastomers, and chlorinated polyethylene-based thermoplastic elastomers Can be mentioned.
Other insulating particles include silica, alumina, titanium oxide (titanium dioxide, titanium monoxide, etc.), metal oxide particles such as zinc oxide, magnesium oxide, zirconium oxide, barium sulfate, barium titanate, disulfide. Molybdenum, calcium carbonate, magnesium carbonate, dolomite, talc, kaolin clay, mica, aluminum hydroxide, magnesium hydroxide, zeolite, wollastonite, diatomaceous earth, glass beads, bentonite, montmorillonite, asbestos, hollow glass sphere, graphite, Examples thereof include particles of rice husk, organometallic compounds, and organometallic salts. Also, iron oxides such as ferrite, magnetite, and hematite, activated carbon, and the like can be used. Examples of the ferrite include ferrite described in “Electronic Material Series Ferrite” (Maruzen Co., Ltd., issued on October 10, 1997, 5th printing), and specifically, MnFe ₂ O ₄ , FeFe ₂ O ₄ , ZnFe ₂ O ₄ , MgFe ₂ O ₄ , γ-Fe ₂ O _{4 and the} like can be exemplified. Examples of the activated carbon include activated carbon described in “New Edition Activated Carbon-Fundamentals and Applications” (Kodansha Co., Ltd., issued October 20, 1992, 2nd edition). Examples thereof include activated carbon, coconut shell activated carbon, and coal activated carbon.

These particles may be used alone or in combination of two or more, and may be subjected to surface treatment, modification, introduction of functional groups or molecular chains, coating, and the like. From the viewpoint of controlling the dispersibility of the particles, the particles are preferably subjected to a surface treatment. Examples of the surface treatment include coupling treatment and fatty acid treatment. Examples of the coupling treatment include treatment using a silane coupling agent or titanate coupling agent, and examples of the fatty acid treatment include treatment using an acid such as stearic acid.
The volume resistivity of the surface coating layer is preferably 10 ¹⁶ Ω · cm or less in a 23 ° C./50% RH environment, and is preferably larger than the volume resistivity of the elastic coating layer described later. When the volume resistivity of the surface coating layer is too large, the charging ability as a charging member is lowered, and it becomes difficult to satisfy charging uniformity. On the other hand, if the volume resistivity of the surface coating layer is smaller than the volume resistivity of the elastic coating layer, which will be described later, it is difficult to prevent leakage due to pinholes or scratches on the surface of the electrophotographic photosensitive member being charged. Become. Thus, in order to adjust the volume resistivity of a surface coating layer, it is preferable to make a surface coating layer contain 1 type, or 2 or more types of electroconductive particle.

  On the other hand, from the viewpoint of ease of controlling the dispersibility of the particles and, in turn, ease of surface control of the charging member, the surface coating layer preferably contains polymer compound particles (at least particles composed of a polymer compound). In particular, when a resin suitable as a binding material is used for the surface coating layer, it is preferable to contain resin particles (at least particles made of resin). Among the resin particles, resin particles having the same type of structure as the resin used as the binder material are preferable.

  When the particles (preferably polymer compound particles, more preferably resin particles) are contained in the surface coating layer of the charging member to solve the above problem, the average particle size A [ μm] is preferably 2 ≦ A, more preferably 3 ≦ A, even more preferably 5 ≦ A, still more preferably 9 ≦ A, More preferably, 10 ≦ A. If the average particle size of the particles included in the surface coating layer is too small, the surface of the charging member becomes too smooth, and charging uniformity corresponding to multiple process speeds (initial charging uniformity and charging uniformity over a long period of time) Maintenance of sex) is difficult to achieve. On the other hand, the average particle diameter A [μm] of the particles to be contained in the surface coating layer is preferably A ≦ 50, and more preferably A ≦ 20. If the average particle size of the particles to be included in the surface coating layer is too large, a convex portion that is too large is formed on the surface of the charging member, and charging uniformity corresponding to multiple types of process speeds (initial charging uniformity and long-term Maintenance of the charging uniformity over the entire area) is difficult to achieve. Further, the sharper the particle size distribution of the particles to be contained in the surface coating layer of the charging member is more preferable. Specifically, the particle size distribution range is more than 0 and 7 A or less when the average particle size is A [μm]. It is preferable that it is the range of these. In other words, the particle size of the particles to be contained in the surface coating layer of the charging member is preferably in the range of more than 0 [μm] and not more than 7 A [μm]. Particles having a size exceeding 7 A [μm] form a convex portion that is too large on the surface of the charging member, and charging uniformity corresponding to a plurality of types of process speeds (initial charging uniformity and charging uniformity over a long period of time). Maintenance of sex) is difficult to achieve.

Further, the surface coating layer may contain a release agent in order to improve the releasability of the surface of the charging member. By including a release agent in the surface coating layer, dirt adhesion on the surface of the charging member can be reduced, so that the durability of the charging member is improved and between the charging member and the electrophotographic photosensitive member. Therefore, the occurrence of irregular movement such as stick-slip can be reduced, and as a result, irregular wear on the surface of the charging member and occurrence of abnormal noise can be improved. . In addition, when the mold release agent contained in a surface coating layer is a liquid, it acts also as a leveling agent when forming a surface coating layer.
Many release agents use low surface energy and slidability, and their properties are liquid or solid. Examples of the solid and slidable material (solid lubricant) include, for example, the substances described in the Solid Lubrication Handbook (Publisher; Koshobo Co., Ltd., published on March 15, 1982), specifically Metal oxides such as graphite, graphite fluoride, molybdenum disulfide, tungsten disulfide, boron nitride, and lead monoxide can be used.
In addition, a compound containing silicon or fluorine in the molecule is used in an oily state or a solid state (a release resin or powder, or a part of the polymer having a release property introduced therein). Furthermore, waxes and higher fatty acids (including salts, esters and other derivatives thereof) can also be mentioned.

As described above, the elastic coating layer is a coating layer having conductivity and elasticity.
In order to give elasticity to the elastic coating layer, it is preferable to use an elastomer such as rubber or a thermoplastic elastomer as a binding material. Among them, a viewpoint of securing a sufficient nip between the charging member and the electrophotographic photosensitive member. Therefore, it is more preferable to use rubber, particularly synthetic rubber. Moreover, you may use the foam which carried out the foam molding of the elastomer as a binding material of an elastic coating layer.
The elasticity and hardness of the elastic coating layer can be adjusted by the degree of addition of additives (softening oil, plasticizer, etc.) and the degree of foaming.
The elastic coating layer using elastomer may be used as the surface layer of the charging member, that is, the surface coating layer. However, when an additive such as softening oil or plasticizer is used for this elastic coating layer, it is added to the surface of the charging member. From the viewpoint of preventing the agent from bleeding out, the elastic coating layer is preferably not a surface layer of the charging member.

The volume resistivity of the elastic coating layer is preferably 10 ⁵ to 10 ⁸ Ω · cm in a 23 ° C./50% RH environment. When the volume resistivity of the elastic coating layer is too large, the charging ability of the charging member is lowered, it becomes difficult to satisfy charging uniformity, and an image defect such as charging member periodic longitudinal unevenness may occur. On the other hand, if the volume resistivity of the elastic coating layer is too small, image defects such as black spots may occur. If the volume resistivity of the elastic coating layer is too small, a potential difference hardly occurs in the elastic coating layer even if a voltage is applied to the charging member. Then, this potential difference occurs in the gap between the charging member and the electrophotographic photosensitive member and / or in the surface coating layer when a separate surface coating layer is provided. That is, the potential difference Vxy in the equation (6) is increased. That is, when the surface of the charging member has the same shape, the smaller the volume resistivity of the elastic coating layer, the more the sum of ΔQ, that is, the difference in the charge Q accumulated on the surface of the electrophotographic photosensitive member becomes significant. Image defects such as black spots will occur.
Moreover, it is preferable that resistance of what formed only the elastic coating layer on the support body is 10 < ⁵ > -10 < ⁸ > (omega | ohm) in 23 degreeC / 50% RH environment. If the resistance is too large, it is difficult to satisfy charging uniformity, and an image defect such as uneven charging member longitudinal length may occur. If the resistance is too small, image defects such as black spots may occur.
The conductivity (volume resistivity) of the elastic coating layer can be adjusted by appropriately adding a conductive agent such as carbon black, a conductive metal oxide, an alkali metal salt, or an ammonium salt to the above binder material. .

Further, when the charging member is a charging roller having a crown shape, the crown shape is preferably obtained by polishing the surface of the elastic coating layer.
Examples of the method for polishing the surface of the elastic coating layer include a method in which abrasive particles, a tape or paper to which the abrasive particles are bonded, or a grindstone is pressed against the surface of the elastic coating layer. Among these, the method of pressing the grindstone against the surface of the elastic coating layer and polishing the surface of the elastic coating layer is preferable. An example of a method for polishing the surface of the roller-shaped elastic coating layer is a polishing method called a traverse method. This traversing method is a method of polishing the surface of the elastic coating layer by moving a short grindstone along the surface of the roller-shaped elastic coating layer. As another polishing method, there is also a polishing method called a wide polishing method. This wide polishing method is a method in which a wide whetstone, that is, a whetstone having a width approximately equal to the length in the longitudinal direction of a roller-shaped elastic coating layer, is pressed against the surface of the elastic coating layer once. In this method, the surface of the elastic coating layer can be polished in a short time. Since the surface of the elastic coating layer can be polished at once by this wide polishing method, the surface roughness of the elastic coating layer can be easily set to a desired value by controlling the shape of the grindstone. . Therefore, from the viewpoint of work efficiency, a polishing method called a wide polishing method is preferable.

When an additive is used for the elastic coating layer, one or two or more resistance layers (1 of the coating layer) are provided between the elastic coating layer and the surface coating layer from the viewpoint of enhancing the prevention of the additive bleed-out. Seeds) may be provided. The volume resistivity of the resistance layer is preferably larger than the volume resistivity of the elastic coating layer, and preferably smaller than the volume resistivity of the surface coating layer. When the volume resistivity of the resistance layer is smaller than the volume resistivity of the elastic coating layer or larger than the volume resistivity of the surface coating layer, it becomes difficult to satisfy charging uniformity. Thus, in order to adjust the volume resistivity of a resistance layer, you may make a resistance layer contain 1 type, or 2 or more types of electroconductive particle.
In addition to the various materials described above, the surface coating layer, the elastic coating layer, and the resistance layer can appropriately contain materials having various functions. Examples of such materials include anti-aging agents such as 2-mercaptobenzimidazole and lubricants such as stearic acid and zinc stearate.
Moreover, you may surface-treat to each surface of said surface coating layer, an elastic coating layer, and a resistance layer. Examples of the surface treatment include a surface processing treatment using UV or electron beam, and a surface modification treatment for attaching and / or impregnating a compound or the like on the surface.

The surface coating layer, the elastic coating layer, and the resistance layer may be formed by, for example, adhering or coating a sheet-shaped or tube-shaped layer formed in advance to a predetermined film thickness, or electrostatic spraying. The coating may be performed by a coating method such as coating or dipping. Moreover, after forming a layer roughly by extrusion molding, the method of adjusting the shape of a layer by grinding | polishing etc. may be used, and the method of hardening and shaping | molding material to a predetermined shape within a type | mold may be used.
When the layer is formed by a coating method, the solvent used in the coating solution may be any solvent that can dissolve the binder material, for example, alcohols such as methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, Ketones such as cyclohexanone, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane and ethylene glycol monomethyl ether, and methyl acetate Esters such as ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, ethylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene, benzene, toluene, xylene, ligroin, chlorobenzene, di Chlorobenzene and aromatic compounds such as.

  Further, the film thickness of the surface coating layer, the elastic coating layer, and the resistance layer may be in a range that does not impair the expression of the function of each layer. The thickness of the elastic coating layer is preferably 0.5 mm or more, and the thickness of the resistance layer is preferably 1-1000 μm. If the thickness of the surface coating layer is too thin, unevenness in the thickness of the layer may appear remarkably, and the unevenness of the elastic coating layer may appear on the surface of the charging member as it is. If so, it becomes difficult to satisfy the charging uniformity, and the toner (toner particles and external additives) easily adheres to the surface of the charging member. If the surface coating layer is too thick, the elasticity of the elastic coating layer may not be sufficiently exerted, and the uniform adhesion between the electrophotographic photosensitive member and the charging member may be poor. If the thickness of the elastic coating layer is too thin, the elasticity is not sufficient, and the uniform adhesion between the electrophotographic photosensitive member and the charging member may be poor.

(Measurement method of physical properties)
In the present invention, the volume resistivity of the surface coating layer, the elastic coating layer, and the resistance layer is measured using a resistance measuring device Hiresta-UP manufactured by Mitsubishi Chemical Corporation in a 23 ° C./50% RH environment. The sample was measured by applying a voltage of 250 V for 30 seconds. Regarding the measurement of the volume resistivity of the elastic coating layer, a 2 mm thick film was formed using the material for the elastic coating layer, and this was used as a sample to be measured. Regarding the measurement of the volume resistivity of the surface coating layer, a coating solution containing a material for the surface coating layer was coated on an aluminum sheet, and this was used as a measurement target sample. For the measurement of the volume resistivity of the resistance layer, a coating solution containing a material for the resistance layer was coated on an aluminum sheet, and this was used as a measurement target sample.
In addition, the resistance of the support having only the elastic coating layer formed thereon is measured as shown in FIG. 13 by using a 30 mm diameter SUS cylindrical electrode 131, a fixed resistor 132, a recorder (recorder) 133, a power source 134, and the like. It was carried out by a measuring device composed of Both ends of 135 having an elastic coating layer formed on the support are pressed against the cylindrical electrode 131 with a load of 1 kg as a whole, and both the 135 and the cylindrical electrode 131 having only the elastic coating layer formed thereon are pressed. The measurement was performed while being driven to rotate. In the environment of 23 ° C./50% RH, the value of the current flowing through the circuit when 200 V is applied to the circuit from the power source 134 is measured, and only the elastic coating layer is formed on the support from the average value 135 The resistance was calculated.
In the present invention, the thickness of the surface coating layer, the elastic coating layer, and the resistance layer is determined by cutting the charging member with a cutter knife or the like, and observing the cross section of the layer with an optical microscope or an electron microscope. It was determined by actual measurement.
The 10-point average surface roughness (Rz) in the present invention is the 10-point average surface roughness in the standard of JISB0601 surface roughness. The measurement was performed using a surface roughness measuring device SE-3400 manufactured by Kosaka Laboratory. Specifically, the 10-point average surface roughness at 6 random points of the charging member to be measured was measured by this measuring device, and the average value of the 6 points was defined as the 10-point average surface roughness (Rz). Further, the average surface roughness (Sm) was also measured in the same manner as the 10-point average surface roughness (Rz).
Moreover, the measurement of said H, Sa, and Sb was performed using the ultra deep shape measurement microscope VK-8500 made from KEYENCE. Specifically, the charging member was placed on a stage, a convex portion on the surface of the charging member was selected, and measurement was performed in the “color ultra-deep” measurement mode. After measurement, the profile and measurement screen can be displayed to calculate the height and area. The calculation method is as described above.

The charging member whose surface state is controlled so as to satisfy the expressions (1) to (5) of the present invention will be summarized below.
20 convex portions randomly selected from the surface used for image formation on the surface of the charging member (H [μm] whose relationship with Rz satisfies the expressions (2) and (3) is the height. H, Sa, and Sb are calculated for the convex portion, and the calculated H, Sa, and Sb and the 10-point average surface roughness Rz of the surface of the charging member do not deviate from the formulas (1) to (5). In this case, the charging member is the charging member of the present invention.
If there is a convex shape that does not satisfy the formula (3) in the region that is used for image formation, it is too small and is not considered as the convex portion for calculating the area (Sa) in the formula (4). Further, it is not adopted as the “vertex” for calculating the area (Sb) in the equation (5).
The charging member whose surface state is controlled so as to satisfy the formulas (1) to (5) of the present invention has a convex shape that is so large that the formula (2) is not satisfied in the region used for image formation (convex There is no part).
When one of the convex portions whose height is H [μm] whose relation to Rz satisfies the expressions (2) and (3) is used as a reference, the height other than the height of the reference convex portion If there is no convex part or there is only one, or even if there are two or more, the height of the convex part based on the reference is inside the area surrounded by the vertices of the convex part and the reference convex part. When a convex part having a height exceeding 0.5 times exists, the area (Sb) is not calculated.

In the present invention, the particle size of the particles was measured using a laser diffraction particle size distribution analyzer SALD-7000 manufactured by Shimadzu Corporation. First, a solution in which a small amount of 0.2% by mass of a surfactant was added to distilled water was prepared. The surfactant is not particularly limited, and any surfactant can be used. This solution was put in a glass bottle, a small amount of particles to be measured were added, and dispersed by applying ultrasonic waves for 5 minutes. This solution was put into a measurement cell, and the particle size was measured. The measurable particle size range is 0.015 to 500 μm. The volume average particle diameter measured by the above apparatus was used as the average particle diameter of the particles. Further, in the present invention, the volume resistivity of the insulating particles is measured using a resistance measuring device “Hiresta-UP” manufactured by Mitsubishi Chemical Corporation in a 23 ° C./50% RH environment. Measurement was carried out by applying a voltage that matches the resistance of the sample (because a suitable applied voltage differs depending on the resistance region to be measured). In addition, the volume resistivity of the conductive particles is measured by applying a voltage of 10 V to the measurement target sample using a resistance measuring device Loresta-GP manufactured by Mitsubishi Chemical Corporation in a 23 ° C./50% RH environment. It was measured.
The amount of the sample to be measured is preferably adjusted as appropriate in consideration of the density of the particles whose volume resistivity is to be measured. For example, when measuring tin oxide particles, 1.5 g is used, and carbon black is used. Was measured, 0.5 g was used, and a sample subjected to compression by applying a pressure of 10.1 MPa (102 kgf / cm ² ) was used as a measurement target sample.

FIG. 14 shows an example of a schematic configuration of an electrophotographic apparatus including an electrophotographic photosensitive member and a process cartridge having the charging member of the present invention.
In FIG. 14, reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is driven to rotate at a predetermined peripheral speed in the direction of the arrow about the shaft 2.
The surface of the electrophotographic photosensitive member 1 that is rotationally driven is uniformly charged to a predetermined positive or negative potential by a charging member (roller-shaped charging member: charging roller in FIG. 14), and then subjected to slit exposure or laser beam. Exposure light (image exposure light) 4L output from exposure means (not shown) such as scanning exposure is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the surface of the electrophotographic photosensitive member 1.
The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in the developer of the developing means 5 to become a toner image. Next, the toner image formed and supported on the surface of the electrophotographic photoreceptor 1 is transferred from a transfer material supply means (not shown) to the electrophotographic photoreceptor 1 and the transfer means by a transfer bias from a transfer means (transfer roller or the like) 6. 6 (contact portion) is sequentially transferred onto a transfer material (paper or the like) P taken out and fed in synchronization with the rotation of the electrophotographic photosensitive member 1.
The transfer material P that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member 1 and introduced into the fixing means 8 to receive the image fixing, and is printed out as an image formed product (print, copy). Is done.
After the toner image is transferred, the surface of the electrophotographic photoreceptor 1 is cleaned by a cleaning means (cleaning blade or the like) 7 to remove the developer (toner) remaining after transfer, and then used repeatedly for image formation. . In addition, after the surface of the electrophotographic photosensitive member 1 is cleaned by the cleaning unit 7, the surface of the electrophotographic photosensitive member 1 may be neutralized by pre-exposure light before charging by the charging member 3.

Among the above-described components such as the electrophotographic photosensitive member 1, the charging member 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 an electrophotographic apparatus main body such as a copying machine or a laser beam printer. In FIG. 14, the electrophotographic photosensitive member 1, the charging member 3, the developing unit 5 and the cleaning unit 7 are integrally supported to form a cartridge, and the main body of the electrophotographic apparatus using a guide unit 10 such as a rail of the main body of the electrophotographic apparatus. The process cartridge 9 is detachable.
The electrophotographic photosensitive member 1 includes, for example, an electrophotographic photosensitive member having a cylindrical support (conductive support) and a photosensitive layer containing an inorganic photosensitive material and / or an organic photosensitive material formed on the support. The body can be adopted. In addition, the electrophotographic photosensitive member 1 may further include a charge injection layer for charging the surface of the electrophotographic photosensitive member to a predetermined polarity and potential.
Examples of the developing method employed by the developing unit 3 include a jumping developing method, a contact developing method, and a magnetic brush method. In the case of an electrophotographic apparatus that outputs a color image (full color image), the contact development method is particularly preferable for the purpose of improving toner scattering properties.

  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”.

および、カーボンブラック（表面未処理品、平均粒径：０．２μｍ、体積抵抗率：０．１Ω・ｃｍ）５部を、５０℃に調節した密閉型ミキサーにて１０分間混練して、原料コンパウンドを調製した。
この原料コンパウンドに、上記エピクロルヒドリンゴム三元共重合体に対して１質量％の硫黄（加硫剤）、１質量％のジベンゾチアジルスルフィド（ＤＭ）（加硫促進剤）および０．５質量％のテトラメチルチウラムモノスルフィド（ＴＳ）を添加し、２０℃に冷却した二本ロール機にて１０分間混練して、弾性被覆層用コンパウンドを得た。
支持体上に、この弾性被覆層用コンパウンドを押し出し成型機にて押し出し、外径が１５ｍｍのローラー形状になるように成型し、次いで、加熱蒸気加硫した後、外径が１０ｍｍのローラー形状になるように表面の研磨加工を行って、支持体上に弾性被覆層を形成した。この研磨加工は、幅広研磨方式を採用した。 上述した方法により、弾性被覆層の体積抵抗率および「支持体上に弾性被覆層のみを形成したもの」（以下、「弾性被覆層形成部材」という）の抵抗を測定したところ、弾性被覆層の体積抵抗率は１．２×１０^６Ω・ｃｍ、弾性被覆層形成部材の抵抗は３．２×１０^５Ωであった。 (Example 1)
A stainless steel cylinder having a diameter of 6 mm and a length of 232 mm was used as a support (conductive support).
Next, 100 parts of epichlorohydrin rubber terpolymer (epichlorohydrin: ethylene oxide: allyl glycidyl ether = 40 mol%: 56 mol%: 4 mol%), 30 parts of light calcium carbonate, 5 parts of an aliphatic polyester plasticizer, zinc stearate 1 part, 0.5 part of 2-mercaptobenzimidazole (MB) (anti-aging agent), 5 parts of zinc oxide, 2 parts of a quaternary ammonium salt represented by the following formula,

And 5 parts of carbon black (surface untreated product, average particle size: 0.2 μm, volume resistivity: 0.1 Ω · cm) is kneaded for 10 minutes in a closed mixer adjusted to 50 ° C., and the raw material compound Was prepared.
To this raw material compound, 1% by mass of sulfur (vulcanizing agent), 1% by mass of dibenzothiazyl sulfide (DM) (vulcanization accelerator) and 0.5% by mass with respect to the above epichlorohydrin rubber terpolymer. Of tetramethylthiuram monosulfide (TS) was added and kneaded for 10 minutes in a two-roll machine cooled to 20 ° C. to obtain a compound for an elastic coating layer.
This elastic coating layer compound is extruded on a support by an extrusion molding machine, molded so as to have a roller shape with an outer diameter of 15 mm, then heated and steam vulcanized, and then formed into a roller shape with an outer diameter of 10 mm. The surface was polished so that an elastic coating layer was formed on the support. This polishing process employs a wide polishing method. By measuring the volume resistivity of the elastic coating layer and the resistance of “only the elastic coating layer formed on the support” (hereinafter referred to as “elastic coating layer forming member”) by the above-described method, The volume resistivity was 1.2 × 10 ⁶ Ω · cm, and the resistance of the elastic coating layer forming member was 3.2 × 10 ⁵ Ω.

Next, 100 parts of caprolactone-modified acrylic polyol solution, 250 parts of methyl isobutyl ketone, conductive tin oxide particles (treated with trifluoropropyltrimethoxysilane, average particle size: 0.05 μm, volume resistivity: 10 ³ Ω · cm, 130 parts of conductive particles, 3 parts of hydrophobic silica (treated with dimethylpolysiloxane, average particle size: 0.02 μm, volume resistivity: 10 ¹⁶ Ω · cm), 0.08 parts of modified dimethyl silicone oil, and crosslinking Polymethylmethacrylate (PMMA) particles (average particle size: 9.85 μm, maximum particle size: 52.5 μm, volume resistivity: 10 ¹⁶ Ω · cm, insulating polymer compound particles (resin particles)) 80 parts were put into a glass bottle to prepare a mixed solution.
The mixed solution was filled with glass beads having an average particle diameter of 0.8 mm as a dispersion medium so that the filling rate was 80%, and dispersed for 18 hours using a paint shaker disperser to obtain a dispersion solution.
To this dispersion solution, a mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) each butanone oxime block body 1: 1 was added so that “NCO / OH = 1.0”. A coating solution was prepared.

This surface coating layer coating solution is dipped on the elastic coating layer twice, air-dried at room temperature for 30 minutes or more, then dried in a hot air circulating dryer set at 80 ° C. for 1 hour, and further set at 160 ° C. The surface coating layer was formed on the elastic coating layer by drying with a hot air circulating dryer for 1 hour. The dipping coating was performed as follows.
That is, after the first dipping coating was performed, air-dried at room temperature for 10 to 30 minutes, the coated body was inverted, and the second dipping coating was performed in the same manner as the first dipping coating. The pulling speed was 6 mm / s for the first and second time.
Thus, a charging roller having an elastic coating layer and a surface coating layer in this order on the support was produced.
When the volume resistivity of the surface coating layer was measured by the method described above, the volume resistivity of the surface coating layer was 10 ¹⁰ Ω · cm. Further, the 10-point average surface roughness (Rz) of the surface of the charging member was measured by the method described above, and it was 10.2 μm.
The above measurement results are shown in Table 1. Moreover, H, Sa, and Sb were calculated about the convex part of 20 points | pieces selected at random by the method mentioned above. The measurement results are shown in Table 2.

・ Evaluation 1. Evaluation of initial output image The prepared charging member is mounted on an electrophotographic apparatus having a configuration shown in FIG. 15 (a voltage of only a direct current voltage is applied to the charging member), and the 23 ° C./50% RH environment (hereinafter, “NN environment” )), 30 ° C./80% RH environment (hereinafter referred to as “HH environment”) and 15 ° C./10% RH environment (hereinafter referred to as “LL environment”). The output image was evaluated. The voltage applied to the charging roller was adjusted for each environment so that the surface potential (dark portion potential) VD of the electrophotographic photosensitive member charged by the charging roller was −400 V in each environment. The process speed was set to 94 mm / s and 30 mm / s.

The electrophotographic apparatus having the configuration shown in FIG. 15 will be described below.
Reference numeral 151 denotes a cylindrical electrophotographic photosensitive member. The electrophotographic photoreceptor 151 is rotationally driven in a direction indicated by an arrow at a predetermined process speed (can be set to 94 mm / s and 30 mm / s).
Reference numeral 153 denotes a charging roller. S1 is a power source for applying only a DC voltage to the charging roller. The charging roller 153 is brought into contact (contact) with the electrophotographic photosensitive member 151 with a predetermined pressing force, and is driven to rotate in the forward direction with respect to the rotation of the electrophotographic photosensitive member 151. The charging roller 153 is charged (contact charged) to the surface of the electrophotographic photosensitive member 151 at −400 V by applying a voltage of only DC voltage −1000 V from the power source S1.
Reference numeral 154 denotes a laser beam scanner as exposure means. The surface of the electrophotographic photosensitive member 151 charged to −400 V (dark portion potential) by the charging roller 153 is irradiated with exposure (image exposure) light 154L corresponding to target image information by the laser beam scanner 154, so that the electron The potential of −400 V on the surface of the photographic photoreceptor is selectively attenuated to −150 V (bright part potential), and an electrostatic latent image is formed on the surface of the electrophotographic photoreceptor 151.

  Reference numeral 155 denotes a developing device (developing means). The developing device 155 includes a toner carrier 155a that is disposed in an opening of a developing container that accommodates toner (developer) and carries the toner, a stirring member 155b that stirs the contained toner, and a toner carrier. And a toner regulating member 155c that regulates the amount of toner 155a (toner layer thickness). The developing device 155 selectively attaches toner (negative toner) charged to −350 V (development bias) to the bright portion potential portion of the electrostatic latent image formed on the surface of the electrophotographic photoreceptor 151, The electrostatic latent image is visualized as a toner image. The toner carrier 155a is in contact with the electrophotographic photosensitive member, or in contact with the electrophotographic photosensitive member via the toner to be carried. That is, the contact development method is adopted. Therefore, the toner carrier 155a is a developing roller provided with an elastic coating layer (made of rubber) imparted with conductivity on a conductive support from the viewpoint of ensuring contact stability (of course, the elastic coating layer includes A foam may be used as the elastic material, or a layer may be separately provided on the elastic coating layer, or surface treatment (surface treatment using UV or electron beam, or adhesion and / or impregnation of a compound or the like on the surface) Etc.) may be applied).

  Reference numeral 156 denotes a transfer roller as transfer means. The transfer roller 156 is a transfer roller formed by coating a conductive support with an elastic resin layer adjusted to a medium resistance. The transfer roller 156 is brought into contact with the electrophotographic photosensitive member 151 with a predetermined pressing force to form a transfer nip portion, and is approximately equal to the rotational peripheral speed of the electrophotographic photosensitive member 151 in the forward direction with the rotation of the electrophotographic photosensitive member 151. Rotates at the same peripheral speed. Further, a transfer voltage having a polarity opposite to the charging characteristics of the toner is applied from the power source S2. A transfer material P is fed to a transfer nip portion from a paper feeding mechanism (not shown) at a predetermined timing, and the back surface of the transfer material P is opposite to the charging polarity of the toner by a transfer roller 156 to which a transfer voltage is applied. By being charged to the polarity, the toner image on the surface of the electrophotographic photosensitive member 151 is electrostatically transferred to the surface of the transfer material P (the surface facing the electrophotographic photosensitive member 151) at the transfer nip portion.

The transfer material P that has received the transfer of the toner image at the transfer nip is separated from the surface of the electrophotographic photosensitive member 151 and introduced into a fixing device (not shown), and the toner image is fixed and output as an image formed product. (In the case of the double-sided image forming mode or the multiple image forming mode, this image-formed product is introduced into a recirculation conveyance mechanism (not shown) and reintroduced into the transfer nip portion)
The transfer residual toner on the surface of the electrophotographic photoreceptor 151 is collected by a cleaning blade (not shown). Thereafter, the surface of the electrophotographic photosensitive member 151 is again charged by the charging roller 153, and image formation is repeatedly performed.
Table 3 shows the evaluation results of the initial output image. In Table 3, Rank 1 is very good, Rank 2 is good, Rank 3 has a slight streak or spot-like image defect in the halftone image, and Rank 4 shows a noticeable streak or spot-like image defect. Is a level. Of the image output at a process speed of 94 mm / s and the image output at a process speed of 30 mm / s, the evaluation rank of the one with the worse image level was set as the evaluation rank of the example (and comparative example).

2. Evaluation of output image during endurance test Further, after evaluation of the initial output image, an image output endurance test was continuously performed for 10,000 images under each environment. During the durability test, the process speed was set to 94 mm / s, and during the durability test, the output images of the 5000th sheet and the 10,000th sheet were evaluated. The evaluation of this output image was performed in the same manner as the evaluation of the initial output image.
Table 4 shows the evaluation results of the output images after endurance (5000th and 10000th images). In Table 3, Rank 1 is the same as the initial output image, Rank 2 is almost unchanged from the initial output image (with slight density unevenness), and Rank 3 is a halftone image that is a faint color caused by uneven charging member contamination. The density level and the dot image are generated, and rank 4 is an image level that the density unevenness and the dot due to the stain unevenness of the charging member are generated in the halftone image. Of the image output at a process speed of 94 mm / s and the image output at a process speed of 30 mm / s, the evaluation rank of the one with the worse image level was set as the evaluation rank of the example (and comparative example).

(Example 2)
A charging member was produced in the same manner as in Example 1 except that the amount of the crosslinked polymethyl methacrylate (PMMA) particles contained in the surface coating layer was changed from 80 parts to 50 parts in Example 1. However, the average particle diameter of the crosslinked polymethylmethacrylate (PMMA) particles and the maximum particle diameter of the particles contained in the surface coating layer are as shown in Table 1.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.

(Example 3)
In Example 1, a charged member was produced in the same manner as in Example 1 except that the crosslinked polymethyl methacrylate (PMMA) particles contained in the surface coating layer were changed to polystyrene particles and the amount used was 50 parts. Table 1 shows the average particle diameter of the polystyrene particles and the maximum particle diameter of the polystyrene particles contained in the surface coating layer.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.

(Example 4)
A charging member was produced in the same manner as in Example 3, and the surface was further polished to obtain the charging member of this example. As a polishing method, a paper to which aluminum oxide particles (abrasive particles) having an average particle size of 5.2 μm are adhered is pressed against a surface to be polished (a charging member produced in the same manner as in Example 3). The method of polishing was taken.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.

(Example 5)
In Example 2, a charging member was produced in the same manner as in Example 2 except that the elastic coating layer was formed as follows.
That is, 100 parts of acrylonitrile-butadiene copolymer rubber (NBR), 5 parts of carbon black (non-surface-treated product, average particle diameter: 0.2 μm, volume resistivity: 0.1 Ω · cm), the charging member of Example 1 10 parts in a closed mixer adjusted to 50 ° C. with 2 parts of the same quaternary ammonium salt used for the elastic coating layer, 30 parts of calcium carbonate, 5 parts of zinc oxide, and 2 parts of aliphatic polyester (plasticizer). The mixture was kneaded for 20 minutes and further kneaded for 20 minutes with a closed mixer cooled and adjusted to 20 ° C. to prepare a raw material compound.
To this raw material compound, 1% by mass of sulfur and 3% by mass of Noxeller TS (manufactured by Ouchi Shinsei Chemical Co., Ltd.) are added to the NBR and kneaded for 10 minutes in a two-roll mill cooled to 50 ° C. Thus, an elastic coating layer compound was obtained.
This elastic coating layer compound is extruded on a support with an extrusion molding machine, molded to have a roller shape with an outer diameter of 15 mm, and then heat vulcanized and molded into a roller shape with an outer diameter of 10 mm. The surface was polished so that an elastic coating layer was formed on the support. This polishing process employs a wide polishing method.
When the volume resistivity of the elastic coating layer and the resistance of the elastic coating layer forming member were measured by the method described above, the volume resistivity of the elastic coating layer was 2.3 × 10 ⁶ Ω · cm, and the resistance of the elastic coating layer forming member was Was 7.8 × 10 ⁵ Ω. About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.

(Example 6)
In Example 2, the amount of quaternary ammonium salt contained in the elastic coating layer was changed from 2 parts to 5 parts, and the amount of carbon black used was changed from 5 parts to 10 parts. Thus, a charging member was produced.
When the volume resistivity of the elastic coating layer and the resistance of the elastic coating layer forming member were measured by the method described above, the volume resistivity of the elastic coating layer was 1.25 × 10 ⁵ Ω · cm, and the resistance of the elastic coating layer forming member was Was 1.02 × 10 ⁵ Ω.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.

(Example 7)
In Example 2, the amount of quaternary ammonium salt contained in the elastic coating layer was changed from 2 parts to 0.1 part, and the amount of carbon black used was changed from 5 parts to 1 part. In the same manner, a charging member was produced.
When the volume resistivity of the elastic coating layer and the resistance of the elastic coating layer forming member were measured by the above-described method, the volume resistivity of the elastic coating layer was 6.5 × 10 ⁷ Ω · cm, and the resistance of the elastic coating layer forming member was Was 5.6 × 10 ⁷ Ω.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.

(Example 8)
A charging member was produced in the same manner as in Example 7.
Using the produced charging member, the initial and endurance output images were evaluated in the same manner as in Example 1 except that 30 mm / s on the low speed side of the two process speeds was changed to 47 mm / s. The evaluation results are shown in Tables 3 and 4.

Example 9
A charging member was produced in the same manner as in Example 7.
Using the produced charging member, the initial and endurance output images were evaluated in the same manner as in Example 1 except that 30 mm / s on the low speed side of the two process speeds was changed to 15 mm / s. The evaluation results are shown in Tables 3 and 4.

(Comparative Example 1)
In Example 5, the charging member was the same as Example 5 except that the amount of the crosslinked polymethyl methacrylate (PMMA) particles contained in the surface coating layer was changed from 50 parts to 0 parts (that is, not used). Was made.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz is shown in Table 1. In the charging member of this example, there was no H to be calculated for Sa and Sb.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.
In this example, streaks occur in the output image. There was no convex portion on the surface of the charging member that would cause a spot in the output image.

(Comparative Example 2)
The charging member in the same manner as in Example 5 except that the average particle size of the crosslinked polymethyl methacrylate (PMMA) particles and the maximum particle size of the particles contained in the surface coating layer in Example 5 were as shown in Table 1. Was made.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.
In this example, noticeable spots occurred in the output image. In addition, during the durability test, an image defect caused by unevenness of the surface of the charging member occurred.

(Comparative Example 3)
The charging member in the same manner as in Example 5 except that the average particle size of the crosslinked polymethyl methacrylate (PMMA) particles and the maximum particle size of the particles contained in the surface coating layer in Example 5 were as shown in Table 1. Was made.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.
In this example, a spot occurs in the output image. In addition, during the durability test, an image defect caused by unevenness of the surface of the charging member occurred.

(Comparative Example 4)
The charging member in the same manner as in Example 5 except that the average particle size of the crosslinked polymethyl methacrylate (PMMA) particles and the maximum particle size of the particles contained in the surface coating layer in Example 5 were as shown in Table 1. Was made.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.
In this example, a spot occurs in the output image. In addition, during the durability test, an image defect caused by unevenness of the surface of the charging member occurred.

(Comparative Example 5)
The charging member in the same manner as in Example 5 except that the average particle size of the crosslinked polymethyl methacrylate (PMMA) particles and the maximum particle size of the particles contained in the surface coating layer in Example 5 were as shown in Table 1. Was made.
About the produced charging member, the volume resistivity of the elastic coating layer, the resistance of the elastic coating layer forming member, the volume resistivity of the surface coating layer, and the surface of the charging member measured in the same manner as the charging member produced in Example 1. Rz, H, Sa and Sb are shown in Tables 1 and 2.
Further, using the produced charging member, the output images after the initial stage and after the durability were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4.
In this example, a spot occurs in the output image. In addition, during the durability test, an image defect caused by unevenness of the surface of the charging member occurred.

  16 is a graph of the formula (2), FIG. 17 is a graph of the formula (3), FIG. 18 is a graph of the formula (4), and FIG. 19 is a graph of the formula (5).

It is a graph explaining Paschen's law. It is a figure for demonstrating the height H of a convex part. It is a figure for demonstrating the area Sa of a convex part. Area Sb of a region surrounded by the convex portion and other convex portions having a height not less than H [μm] (height of the convex portion) and not including the convex portion having a height exceeding 0.5 H [μm] It is a figure for demonstrating. It is a figure which shows the example of a layer structure of a charging member. It is a figure which shows the example of a layer structure of a charging member. It is a figure which shows the example of a layer structure of a charging member. It is a figure which shows the example of a layer structure of a charging member. It is a figure which shows the example of a layer structure of a charging member. It is a figure which shows the example of a layer structure of a charging member. It is a figure which shows the example of a layer structure of a charging member. It is a figure which shows the example of a layer structure of a charging member. It is a figure which shows the structure of the apparatus for measuring the resistance of an elastic coating layer forming member. 1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including an electrophotographic photosensitive member and a process cartridge having a charging member of the present invention. It is a figure which shows schematic structure of the electrophotographic apparatus used for the Example and the comparative example. It is a graph of Formula (2). It is a graph of Formula (3). It is a graph of Formula (4). It is a graph of Formula (5).

Explanation of symbols

H The height Sa of the convex portion of the surface of the charging member Sa The area 31 of the convex portion The smallest circle Sb that completely covers the bottom surface of the convex portion The height that is surrounded by the convex portion and other convex portions and exceeds 0.5H [μm] The area 41 of the region not including the convex portion 41 Circle 42 passing through all the vertices of the convex portion and the vertices of the other convex portion Convex portion 43 Other convex portion 44 Other convex portion 45 Convex part (one of)
a support b elastic coating layer c surface coating layer d resistance layer e resistance layer 131 cylindrical electrode 132 fixed resistor 133 recorder (recorder)
134 Power supply 135 An elastic coating layer only formed on a support 1 Electrophotographic photosensitive member 2 Shaft 3 Charging member (charging roller)
4L exposure light (image exposure light)
5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 10 Guide means P Transfer material 151 Electrophotographic photosensitive member 153 Charging roller 154 Laser beam scanner 154L Exposure light 155 Developing device 155a Toner carrier 155b Stirring member 155c Toner regulating member 156 Transfer roller S1 Power supply S2 Power supply

Claims (23)

In the charging member having one or more coating layers on the support,
When the 10-point average surface roughness of the surface of the charging member is Rz [μm], Rz is the formula (1)

The filling,
The relationship between the surface of the charging member and Rz is expressed by the equations (2) and (3).

The area Sa [μm ² ] of the convex portion having a height of H [μm] satisfying the equation (4)

The filling,
On the surface of the charging member, a convex portion whose height is H [μm] whose relation to Rz satisfies the expressions (2) and (3), and other convex portions whose height is higher than the height of the convex portion. The area Sb [μm ² ] of a region that is enclosed and does not include a convex portion having a height that exceeds 0.5 times the height of the convex portion is expressed by the equation (5).

A charging member characterized by satisfying:   The charging member according to claim 1, wherein a coating layer serving as a surface layer of the charging member among the coating layers of the charging member contains polymer compound particles.   The charging member according to claim 2, wherein the polymer compound is a resin.   The average particle diameter of the polymer compound particles is A [μm], and the particle size distribution range of the polymer compound particles is more than 0 [μm] and not more than 7 A [μm]. Charging member.   5. The charging member according to claim 2, wherein 2 ≦ A ≦ 50 when the average particle diameter of the polymer compound particles is A [μm].   The charging member according to claim 5, wherein 3 ≦ A, where A [μm] is an average particle diameter of the polymer compound particles.   The charging member according to claim 6, wherein 5 ≦ A, where A [μm] is an average particle diameter of the polymer compound particles.   The charging member according to claim 7, wherein 9 ≦ A, where A [μm] is an average particle diameter of the polymer compound particles.   The charging member according to claim 8, wherein 10 ≦ A, where A [μm] is an average particle diameter of the polymer compound particles.   The charging member according to claim 1, wherein the charging member has two or more coating layers. 11. The volume resistivity at 23 ° C./50% RH of the layer immediately below the coating layer that becomes the surface layer of the charging member among the coating layers of the charging member is 10 ⁵ to 10 ⁸ Ω · cm. The charging member according to 1.   In the charging member having one or more coating layers on the support, the coating layer serving as the surface layer of the charging member among the coating layers contains polymer compound particles, and the average of the polymer compound particles Charging member, wherein 2 ≦ A ≦ 50 when the particle size is A [μm], and the particle size distribution range of the polymer compound particles is more than 0 [μm] and not more than 7 A [μm] .   The charging member according to claim 12, wherein the polymer compound is a resin.   14. The charging member according to claim 12, wherein 3 ≦ A when the average particle diameter of the polymer compound particles is A [μm].   The charging member according to claim 14, wherein 5 ≦ A, where A [μm] is an average particle diameter of the polymer compound particles.   The charging member according to claim 15, wherein 9 ≦ A when the average particle diameter of the polymer compound particles is A [μm].   The charging member according to claim 16, wherein 10 ≦ A, where A [μm] is an average particle diameter of the polymer compound particles.   The charging member according to claim 12, wherein the charging member has two or more coating layers. 19. The volume resistivity at 23 ° C./50% RH of the layer immediately below the coating layer that becomes the surface layer of the charging member among the coating layers of the charging member is 10 ⁵ to 10 ⁸ Ω · cm. The charging member according to 1.   A process cartridge that integrally supports at least an electrophotographic photosensitive member and a charging member, and is detachable from an electrophotographic apparatus main body, wherein the charging member is the charging member according to any one of claims 1 to 19. To process cartridge.   An electrophotographic apparatus having an electrophotographic photosensitive member, a charging means, an exposure means, a developing means, and a transfer means, wherein the charging means has the charging member according to any one of claims 1 to 19. .   The electrophotographic apparatus according to claim 21, further comprising a voltage applying unit configured to apply only a DC voltage to the charging member. 23. The electrophotographic apparatus according to claim 21, further comprising process speed control means capable of driving the electrophotographic photosensitive member at two or more process speeds.

Images