JP2018045095A - Electrophotographic member, method for manufacturing the same, process cartridge, and electrophotographic image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic member that reduces ununiform wear of a photoreceptor even in a high-speed electrophotographic device, and reduces the occurrence of a dot-like image and a horizontal streak image caused by abnormal discharge.SOLUTION: An electrophotographic member comprises a conductive substrate and a conductive elastic layer as a surface layer; exposed on a surface of the conductive elastic layer is an edge part of an opening of a bowl-shape resin particle obtained through opening of a hollow-shape resin particle; a concave part defined by the edge part and an inner wall of the resin particle and a convex part derived from the edge part are present. The convex part includes a first convex part area bent in the inside direction of the concave part, and a second convex part area. Various straight lines and angles defined by the tip of the first convex part area, the tip of the second convex part area, and the concave part satisfy a predetermined relational expression.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrophotographic member that can be used as a charging member or the like for applying a voltage to charge the surface of an electrophotographic photosensitive member, which is an object to be charged, to a predetermined potential, a process cartridge using the same, and an electrophotography The present invention relates to an image forming apparatus (hereinafter also referred to as “electrophotographic apparatus”).

  An electrophotographic apparatus employing an electrophotographic system mainly includes an electrophotographic photosensitive member (hereinafter also simply referred to as “photosensitive member”), a charging device, an exposure device, a developing device, a transfer device, and a fixing device. As the charging device, there is a contact charging device that charges the surface of the photoconductor by applying a DC voltage or a voltage obtained by superimposing an AC voltage on the DC voltage to a charging member that is in contact with or close to the surface of the photoconductor. Many have been adopted.

  Patent Document 1 includes a bowl-shaped resin particle having an opening in a conductive resin layer as a roller member (hereinafter also referred to as a “charging roller”) that is charged by being brought into contact with a photosensitive member, and a bowl is formed on the surface. A roller member having a concavo-convex shape derived from an opening portion and an edge portion of a resin particle having a shape is disclosed. According to the roller member according to Patent Document 1, the contact pressure is relieved by elastic deformation when the edge portion of the bowl-shaped resin particles abuts on the photoreceptor, and the photoreceptor can be used even for a long period of use. It is described that uneven wear can be suppressed.

JP 2011-237470 A

  On the other hand, in recent years, with the increase in the process speed of an electrophotographic apparatus, it is becoming easier for the photosensitive member to vibrate when an electrophotographic image is formed. When an attempt is made to charge the photosensitive member using the roller member described in Patent Document 1 on the vibrating photosensitive member, the roller member cannot follow the rotation of the photosensitive member, and the roller member is not on the surface of the photosensitive member. It was confirmed that the phenomenon of slipping (hereinafter also referred to as “stick slip”) may occur. The occurrence of stick-slip causes uneven charging on the photoreceptor and causes horizontal stripe-like density unevenness on the electrophotographic image. Hereinafter, horizontal stripe-like density unevenness generated in an electrophotographic image may be referred to as “banding”. In addition, an electrophotographic image in which horizontal stripe-like density unevenness occurs may be referred to as a “banding image”.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic member that can sufficiently suppress uneven wear of a photoreceptor and generation of a banding image even when used for a long period of time. Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus that contribute to the formation of high-quality electrophotographic images.

According to one aspect of the present invention, a roll-shaped electrophotographic member having a conductive substrate and a conductive elastic layer as a surface layer on the conductive substrate, the conductive elastic layer comprising a binder And bowl-shaped resin particles having hollow resin particles opened, and the edge of the opening of the bowl-shaped resin particles is exposed on the surface of the conductive elastic layer. The resin particle has a concave portion defined by the edge portion of the opening and the inner wall of the resin particle, and a convex portion derived from the edge portion of the opening, and the center O of the rotation axis of the electrophotographic member. The first direction is a direction along the first straight line a that forms the shortest distance from the resin particle to the inner wall of the resin particle in the recess, and is orthogonal to the first direction and in the longitudinal direction of the electrophotographic member When the direction orthogonal to the second direction is the second direction, the convex portion is from the center O of the rotation axis. The highest point C that is farthest away in the first direction, and when the highest point is orthographically projected in the first direction, the projected point P ′ of the highest point protrudes so as to be located in the recess. A first convex region, and a second convex region constituted by an edge portion AA ′ of an opening in the second direction from a tip E protruding the first convex region. The second direction from the tangent a ″ in the first direction of the pseudo circle having a diameter at two points that define the maximum inner diameter of the concave portion to the tip E of the first convex region. L ₁ a _distance, and the inner wall surface of the resin particles in the recess, through the intersection P between the first straight line a, a second straight line b extending in the second direction, highest-point L ₂ , the distance to the third straight line b ″ extending in the second direction through C, the highest point C ′ in the first direction of the tip E of the first convex region, and the second Connecting the outermost edge A of the convex region of The electrophotographic member is characterized by having at least one bowl-shaped resin particle satisfying the following mathematical formula (1), where θ is an angle formed by the straight line c of 4 and the second direction.
Equation _{(1) D = L 1 /} L 2 -tanθ> 0.

  According to another aspect of the present invention, a process for producing a conductive roller by forming a coating layer of a composition in which hollow resin particles are dispersed in a binder on the outer periphery of a conductive substrate, the coating By polishing the surface of the layer, a part of the shell of the hollow resin particle is removed to form a bowl shape having an opening, and the edge of the opening of the bowl-shaped resin particle and the resin are formed on the surface of the coating layer A step of forming a concave portion defined by the inner wall of the particle and a convex portion derived from the edge portion of the opening, and the conductive roller has a rotation axis parallel to the rotation axis of the conductive substrate. There is provided a method for producing the electrophotographic member, comprising a press-contact rotation heating step of heating while pressing a cylindrical press-contact member and rotating both members.

  According to another aspect of the present invention, a process for producing a conductive roller by forming a coating layer of a composition in which hollow resin particles are dispersed in a binder on the outer periphery of a conductive substrate, the coating By polishing the surface of the layer, a part of the shell of the hollow resin particle is removed to form a bowl shape having an opening, and the edge of the opening of the bowl-shaped resin particle and the resin are formed on the surface of the coating layer A step of forming a concave portion defined by the inner wall of the particle and a convex portion derived from an edge portion of the opening, a step of heat-treating the conductive roller in an oxygen-containing atmosphere, and a tape polishing method. There is provided a method for producing the electrophotographic member, comprising the step of performing surface finish grinding of the coating layer.

  According to another aspect of the present invention, there is provided a process cartridge having the above-described electrophotographic member and an electrophotographic photosensitive member and configured to be detachable from the main body of the electrophotographic image forming apparatus. Furthermore, according to another aspect of the present invention, there is provided an electrophotographic image forming apparatus having the above-described electrophotographic member and an electrophotographic photosensitive member.

  According to the present invention, even in an electrophotographic image forming apparatus that has been increased in speed, there is provided an electrophotographic member that can suppress uneven wear of a photoreceptor and can provide a high-quality electrophotographic image. The present invention also provides a process cartridge and an electrophotographic image forming apparatus that contribute to stable formation of high-quality electrophotographic images.

It is a fragmentary sectional view of the surface vicinity of the member for electrophotography concerning the present invention. It is explanatory drawing which shows the structure of the surface vicinity of the conventional electrophotographic member and the electrophotographic member which concerns on this invention. It is a schematic sectional drawing of the nip part of the conventional electrophotographic member and the electrophotographic member which concerns on this invention. It is explanatory drawing which shows the dynamic state in the member for electrophotography which concerns on this invention. It is a schematic sectional drawing which shows an example of the member for electrophotography which concerns on this invention. It is a fragmentary sectional view of the surface vicinity of the member for electrophotography concerning the present invention. It is explanatory drawing of the shape of the bowl-shaped resin particle used for this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure of the pressure welding vulcanizer which has the cylindrical pressure welding member for implementing this invention, and the cylindrical pressure welding member with a curvature change in an edge part, (8a) is a front view, (8b) is a side view FIG. It is explanatory drawing which shows an example of the surface finish grinding for implementing this invention. 1 is a schematic cross-sectional view illustrating an example of an electrophotographic image forming apparatus according to the present invention. It is a schematic sectional drawing showing an example of the process cartridge which concerns on this invention.

An electrophotographic member according to the present invention is a roll-shaped electrophotographic member having a conductive substrate and a conductive elastic layer as a surface layer on the conductive substrate, the conductive elastic layer comprising: A binder and bowl-shaped resin particles opened with hollow resin particles, and the edge of the opening of the bowl-shaped resin particles is exposed on the surface of the conductive elastic layer. The resin particle has a concave portion defined by the edge portion of the opening and the inner wall of the resin particle, and a convex portion derived from the edge portion of the opening, and the center O of the rotation axis of the electrophotographic member. The first direction is a direction along the first straight line a that forms the shortest distance from the resin particle to the inner wall of the resin particle in the recess, and is orthogonal to the first direction and in the longitudinal direction of the electrophotographic member When the direction orthogonal to the second direction is the second direction, the convex portion is the center O of the rotation axis. The highest point C farthest away in the first direction, and when the highest point is orthographically projected in the first direction, the projected point P ′ of the highest point is positioned in the recess. A projecting first projecting region, and a second projecting region composed of an edge AA ′ of an opening in the second direction from the projecting tip E of the first projecting region; And the second tangent a ″ in the first direction of the pseudo circle having a diameter at two points defining the maximum inner diameter of the concave portion to the tip E of the first convex region. The distance in the direction is L ₁ , the second straight line b extending in the second direction passing through the intersection P between the inner wall surface of the resin particle in the recess and the first straight line a, and the highest The distance from the point C to the third straight line b ″ extending in the second direction is L ₂ , the highest point C ′ in the first direction of the tip E of the first convex region and the first line B ″. Connecting the outermost edge A of the two convex regions An electrophotographic member having at least one bowl-shaped resin particle satisfying the following formula (1), where θ is an angle formed by a fourth straight line c and the second direction.
Equation _{(1) D = L 1 /} L 2 -tanθ> 0.

  The electrophotographic member according to the present invention has a conductive substrate and a conductive elastic layer. The conductive elastic layer contains a binder and bowl-shaped resin particles. The edge of the opening of the bowl-shaped resin particle is exposed on the surface of the electrophotographic member, and the bowl-shaped resin particle is defined by the edge of the opening and the inner wall of the resin particle. It has a recessed part and the convex part derived from the edge part of this opening. The direction along the first straight line a that forms the shortest distance from the center O of the rotation axis of the electrophotographic member to the inner wall of the resin particle in the recess is defined as the first direction, and the first direction When the direction perpendicular to the longitudinal direction of the electrophotographic member is defined as the second direction, the convex portion has the highest point C farthest from the center O of the rotation axis in the first direction. When the highest point is orthographically projected in the first direction, the first convex region protruding so that the projection point P ′ of the highest point is located in the concave portion, and the first convexity And a second convex region constituted by an edge portion AA ′ of the opening in the second direction from the tip E of the partial region.

  Hereinafter, the surface formed by the first direction and the second direction is referred to as “xy cross section”, and the bowl-shaped resin particles are also simply referred to as “bowl”.

  FIG. 1 is a partial cross-sectional view orthogonal to the longitudinal direction in the vicinity of the surface of the electrophotographic member according to the present invention, and shows an example of the shape of the bowl-shaped resin particles in the xy cross section. FIG. 2 (2 a) is an enlarged schematic view of a close contact portion (hereinafter referred to as “nip portion”) between a roller member containing bowl-shaped resin particles and a photoreceptor according to Patent Document 1. In the nip portion, the edge portion (convex portion) of the opening of the bowl-shaped resin particles is elastically deformed by the contact pressure with the photoreceptor, so that the contact pressure on the photoreceptor is relieved. Due to the above-described effects, it is possible to suppress uneven wear of the photoconductor even during long-term use.

  On the other hand, FIG. 2 (2 b) is an enlarged schematic view of a close contact portion between the electrophotographic member containing the bowl-shaped resin particles according to the present invention and the photosensitive member. Compared with the edge part (convex part) of the bowl-shaped resin particle described in Patent Document 1, the convex part derived from the edge part of the opening of the bowl-shaped resin particle on the surface of the electrophotographic member according to the present invention. The first convex region which is a portion is bent inward of the concave portion of the bowl and is in contact with the photosensitive member.

  As a result of intensive studies by the inventors, by achieving the contact state shown in FIG. 2 (2b), the stability of driven rotation between the electrophotographic member and the photosensitive member is improved, and slip is suppressed. As a result, it was found that the banding image is suppressed. The mechanism is presumed as follows.

  FIG. 3 (3a) is a schematic sectional view of the nip portion. As shown in FIG. 3 (3 a), the electrophotographic member 32 is brought into contact with the photoreceptor 31 by a predetermined pressing force (not shown) such as a spring to form a nip portion 33. Then, as the photosensitive member rotates in the direction of arrow E, the electrophotographic member also rotates following the direction of arrow A. Here, first, the present inventors have confirmed in detail the behavior of the edge portion of the bowl-shaped resin particles when a banding image is generated. That is, in FIG. 3 (3a), the state of the edge portion of the resin particle at the start end (position B) of the nip portion, the center of the nip portion (position C), and the end end (position D) of the nip portion is observed. did.

  3 (3b, 3c, 3d) is a diagram showing the state of the edge portions (convex portions) of the bowl-shaped resin particles at the positions B, C, D of the roller member according to Patent Document 1, respectively. At the positions B and C, the edge part (convex part) is bent inward of the concave part of the bowl, whereas at the position D, the edge part (convex part) is bent outward of the bowl. I was able to confirm. That is, in the roller member described in Patent Document 1, the direction of elastic deformation of the edge portion (convex portion) transitions from the inner side of the concave portion of the bowl to the outer side of the bowl between positions C to D (hereinafter, It was also known as “transition of elastic deformation direction”. Then, the present inventors have confirmed that slip occurs between the roller member and the photosensitive member during the transition of the elastic deformation direction between the positions C to D, and a banding image is generated.

  On the other hand, FIG. 3 (3b ′, 3c ′, 3d ′) shows edge portions of bowl-shaped resin particles at the positions B, C, D of the roller-shaped electrophotographic member according to one embodiment of the present invention. It is a figure which shows the state of (convex part). The elastic deformation direction of the edge part (convex part) of the resin particle according to one embodiment of the present invention is uniformly inward of the concave part of the bowl at each of B, C, and D positions. That is, the transition in the elastic deformation direction is suppressed. Thereby, it is guessed that the said slip can be suppressed and a banding image can be suppressed.

  As a result of further earnest studies by the present inventors, the surface state of the electrophotographic member necessary for suppressing the transition in the elastic deformation direction has been found. Compared to the conventional bowl shape, the edge part (convex part) has a bowl shape in which the edge part is bent inward of the concave part of the bowl, so that the gentle convex shape derived from the edge part stabilizes the contact with the photoconductor, and the banding. Found to suppress the image. In order to stably contact the electrophotographic member with the photosensitive member, a mathematical expression that defines the bending angle, the length of the edge portion, and the depth of the concave portion with respect to the inner direction of the concave portion of the bowl. It has been found that it is necessary to satisfy (1).

The parameters representing the surface state of the electrophotographic member according to the present invention will be described with reference to FIG. Based on the first direction, the second direction, the first straight line a, the first convex region, the second convex region, and the concave, the following (1) to (1) to Each straight line, each point, each distance, and corner of (7) can be defined.
(1) Draw a pseudo circle whose diameter is two points that define the maximum inner diameter of the recess, and draw a tangent line a ″ in the first direction.
(2) The distance in the second direction from the tangent line a ″ to the tip E of the first convex region is L ₁ .
(3) A second straight line b extending in the second direction passing through the intersection point P between the inner wall surface of the resin particle in the recess and the first straight line a is drawn.
(4) Draw a third straight line b ″ that passes through the highest point C and extends in the second direction.
(5) from the second straight line b, and the distance to the third straight line b "and _{L 2.}
(6) A fourth straight line c connecting the highest point C ′ in the first direction of the tip E of the first convex region and the outermost end A of the second convex region is drawn.
(7) An angle formed by the fourth straight line c and the second direction is θ.

The electrophotographic member according to the present invention is characterized in that the L ₁ , L ₂ , and θ have at least one bowl-shaped resin particle that satisfies the following formula (1).
Equation _{(1) D = L 1 /} L 2 -tanθ> 0.

  In FIG. 1, the highest point C in the first direction of the first convex region and the highest point C ′ in the first direction of the tip E of the first convex region coincide with each other. These two points may or may not match.

  In the case of bowl-shaped resin particles satisfying the above formula (1), the transition of the elastic deformation direction of the edge portion can be suppressed. The reason will be described below.

FIG. 4 is a view corresponding to FIG. 1 and showing a surface shape of an electrophotographic member according to an embodiment of the present invention. As a result of studies by the present inventors, it has been found that the transition in the elastic deformation direction can be suppressed when various parameters derived from FIG. This will be described in detail below. In FIG. 4, F represents the contact pressure, and the straight line a ″, the straight line b, the distance L ₁ , the distance L ₂ , and the angle θ are the same as those already described with reference to FIG. Let the point G be the intersection of the straight lines b. Let M _{1 be} the rotational moment in the clockwise direction at the tip of the first convex region derived from the edge portion with the point G as a fulcrum, and M _{2 be} the rotational moment in the counterclockwise direction. The rotational moment due to the contact pressure F can be expressed by the following mathematical formulas (2) and (3).
Formula (2) M ₁ = FL ₂ sin θ
Equation _{(3) M 2 = FL 1} cosθ.

Among the contact pressure F of the photosensitive member and the electrophotographic member, the moment M ₁ of the clockwise direction represents the components to bend the first projection region from the edge portion outwardly of the bowl, counterclockwise The direction moment M ₂ represents a component that bends the first convex region derived from the edge portion inward of the concave portion of the bowl. That is, in order for the direction of elastic deformation of the first convex region to be always inward of the concave portion of the bowl, it is necessary to satisfy the following formula (4).
Equation _{(4) M 2> M 1} .

By substituting the formulas (2) and (3) into the formula (4) and arranging the formulas, the following formula (1) can be obtained.
Equation _{(1) D = L 1 /} L 2 -tanθ> 0.

  The mathematical formula (1) indicates that the D value is always a positive value. That is, the first convex region derived from the edge portion satisfying the above mathematical formula (1) has a concave portion of the bowl rather than a component that bends the first convex region toward the outside of the bowl at the nip portion with the photosensitive member. The component that is bent in the inner direction is always large, and the first convex region is elastically deformed in the inner direction of the concave portion of the bowl. Therefore, by satisfying the above formula (1), “transition in the elastic deformation direction” can be suppressed, and as a result, generation of banding images can be suppressed. Considering the measurement error of each parameter, the D value is preferably 0.01 or more.

  The electrophotographic member of the present invention has at least one bowl-shaped resin particle satisfying the formula (1) on the surface thereof. In order to further suppress the generation of banding images, each of the electrophotographic members is divided into five equal areas of 5 in the longitudinal direction, and each of the six locations in the circumferential direction (phase 0 °, 60 °, When the surface layer of the region of 0.5 mm in the longitudinal direction and 0.5 mm in the circumferential direction is defined as the “measurement range” at each of the 30 locations in total of 120 °, 180 °, 240 °, and 300 °, the above formula (1) It is preferable that the “measurement range” in which at least one bowl-shaped resin particle satisfying (1) exists is 15 or more.

Moreover, it is more preferable that the average value D _{(Ave) of} D values calculated in the “measurement range” at the 30 locations is 0.02 or more. Moreover, it is more preferable that all of the D values calculated in the 30 measurement ranges are greater than 0, and more preferably 0.01 or more.

  In the electrophotographic member of the present invention, the size of each component is not particularly limited, but the outer diameter of the electrophotographic member is preferably 7 mm or more and 12 mm or less, and the thickness of the conductive elastic layer is preferably 1 mm or more and 7 mm or less, The inner diameter d of the bowl-shaped resin particles is preferably 1 μm or more and 150 μm or less, and the thickness of the shell of the resin particles is preferably 0.1 μm or more and 3 μm or less.

It is preferable that the bowl-shaped resin particles extracted in the xy section satisfy Formula (1), and L ₁ , L ₂ , and θ are within the following ranges. L ₁ represents a length in which the tip E of the first convex region derived from the edge portion enters the inside of the concave portion of the bowl in the xy cross section, and the electrophotographic member is the first convex region. Contact the photoconductor. As the value of L ₁ is large, the electrophotographic member is in contact stably with the photosensitive member, the elastic deformation of the inward direction of the recess of the bowl of the first convex region becomes dominant. That is, L ₁ is preferably from 0.1 d to 0.9 d, and more preferably from 0.2 d to 0.6 d, where d is the inner diameter of the resin particles. If L ₁ is 0.1 d or more, the first convex region is easily bent, and if it is 0.9 d or less, θ can be decreased, and the first convex region is stably inward of the concave portion of the bowl. It becomes easy to bend.

L ₂ denotes a distance from a point P located at the lowest point of the recess in the xy cross section to the highest point C of the first projection region from the edge portion (height). As the value of L ₂ is large, the moment M ₁ that bends the first convex region outward of the bowl is large. On the other hand, as the value of L ₂ is large, the first convex region is also large space that can be bent inwardly of the recess of the bowl. From the above, considering the relationship between L ₁ and θ described later, L ₂ is preferably 0.1 d or more and 0.9 d or less, and more preferably 0.2 d or more and 0.6 d or less. If L ₂ is 0.1 d or more, the first convex region is easily bent, and if it is 0.9 d or less, θ can be reduced, and the first convex region is stably inward of the concave portion of the bowl. It becomes easy to bend.

θ represents the angle formed by the fourth direction c connecting the highest point C of the first convex region and the outermost end A of the second convex region in the xy section and the second direction. Yes. The larger θ is, the larger the moment M ₂ that bends the first convex region derived from the edge portion inward of the concave portion of the bowl is, and the elastic deformation in the inner direction of the concave portion of the bowl in the first convex region. Becomes dominant. That is, θ is preferably 1 ° to 40 °, and more preferably 5 ° to 30 °. If θ is 1 ° or more, the first convex region is easily bent, and if it is 40 ° or less, the first convex region is easily bent in the inner direction of the concave portion of the bowl.

<Electrophotographic materials>
FIG. 5 is a schematic sectional view showing an example of the electrophotographic member according to the present invention. The electrophotographic member of FIG. 5 (5 a) has a conductive substrate 1 and a conductive elastic layer 2. The conductive elastic layer may have a two-layer structure of conductive elastic layers 21 and 22, as shown in FIG. 5 (5b). The conductive elastic layer contains a binder and bowl-shaped resin particles.

  The conductive substrate 1 and the conductive elastic layer 2 or the layers sequentially stacked on the conductive substrate 1 (for example, the conductive elastic layer 21 and the conductive elastic layer 22 shown in FIG. 5 (5b)) are made of an adhesive. You may adhere through. In this case, the adhesive is preferably conductive. A well-known thing can be used for a conductive adhesive. Examples of the base material resin for the adhesive include thermosetting resins and thermoplastic resins, and known resins such as urethane, acrylic, polyester, polyether, and epoxy resins can be used. As a conductive agent for imparting conductivity to the adhesive, it can be appropriately selected from conductive fine particles described in detail later, and one kind can be used alone, or two or more kinds can be used in combination.

[Conductive substrate]
The conductive substrate used in the electrophotographic member of the present case has conductivity and has a function of supporting a conductive elastic layer provided thereon. Examples of the material include metals such as iron, copper, aluminum and nickel and alloys thereof (stainless steel, etc.).

[Conductive elastic layer]
FIG. 6 is a partial sectional view of the vicinity of the surface of the conductive elastic layer constituting the surface layer of the electrophotographic member according to the present invention. The conductive elastic layer includes a binder 42 and bowl-shaped resin particles 41 in which hollow resin particles are opened. The edge of the opening of the bowl-shaped resin particles is exposed on the surface of the conductive elastic layer. Yes. The bowl-shaped resin particles have an opening 51, a concave portion 52 defined by an edge portion of the opening and an inner wall of the resin particle, and a convex portion 53 derived from the edge portion of the opening.

[Bowl-shaped resin particles]
An example of bowl-shaped resin particles is shown in FIGS. 7 (a) to (7d). In the present invention, the “bowl shape” means a shape having an opening and a rounded concave portion inside the opening. The “opening” needs to have a convex part protruding from the edge of the bowl as shown in FIGS. 7B to 7D. However, the conductive elastic layer may contain bowl-shaped resin particles such as shown in (7a) of FIG.

  The thickness of the shell around the opening of the bowl-shaped resin particles (the difference between the outer diameter and the inner diameter of the edge) is preferably 0.1 μm to 3 μm, and particularly preferably 0.2 μm to 2 μm. In addition, the “maximum thickness” of the shell is preferably 3 times or less of the “minimum thickness”, more preferably 2 times or less.

  The “maximum diameter” of the bowl-shaped resin particles means the maximum length in a circular projection image provided by the bowl-shaped resin particles. When the bowl-shaped resin particles give a plurality of circular projection images, the maximum value among the maximum lengths of the projection images is set as the “maximum diameter” of the bowl-shaped resin particles. The standard of the maximum diameter 55 of the bowl-shaped resin particles is 5 μm or more and 150 μm or less, and particularly 8 μm or more and 120 μm or less.

  In the present invention, the degree of suppression of the transition in the elastic deformation direction is affected by the first convex region derived from the edge of the opening of the bowl-shaped resin particles, so the mechanical strength of the bowl-shaped resin particles Such materials are important. In the present invention, examples of the resin forming the bowl-shaped resin particles include the following resins. Acrylonitrile resin, vinyl chloride resin, vinylidene chloride resin, methacrylic acid resin, styrene resin, butadiene resin, urethane resin, amide resin, methacrylonitrile resin, acrylic acid resin, acrylic ester resin, methacrylic ester resin. Among them, in particular, it is possible to use at least one thermoplastic resin selected from acrylonitrile resin, vinylidene chloride resin, and methacrylonitrile resin exhibiting high impact resilience in forming the bowl shape shown in FIG. preferable.

[binder]
A known rubber or resin can be used as the binder contained in the conductive elastic layer. Examples of rubber include natural rubber, a vulcanized product thereof, and synthetic rubber. The following are mentioned as a synthetic rubber. Ethylene propylene rubber, styrene butadiene rubber (SBR), silicone rubber, urethane rubber, isopropylene rubber (IR), butyl rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butadiene rubber (BR), acrylic rubber, epichlorohydrin rubber And fluororubber.

  As the resin, for example, a resin such as a thermosetting resin or a thermoplastic resin can be used. Among these, fluorine resin, polyamide resin, acrylic resin, polyurethane resin, acrylic urethane resin, silicone resin, and butyral resin are more preferable. These may be used alone or in combination of two or more. Moreover, the monomer which is the raw material of these binders may be copolymerized to form a copolymer. For the reasons described later, styrene butadiene rubber (SBR), butyl rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butadiene rubber (BR) having a double bond in the molecule and high heat resistance. It is more preferable to use

Further, in order to control the conductivity of the binder in the conductive elastic layer and the conductivity of the recess derived from the bowl-shaped resin particles, it is preferable to contain silicone oil in the conductive elastic layer. As the structure of the silicone oil, linear dimethylpolysiloxane is preferable. Moreover, as content of a silicone oil, 0.2 mass part or more and 2.0 mass parts or less with respect to 100 mass parts of binders, Especially 0.4 mass part or more and 1.0 mass part or less are preferable. Thereby, the conductivity of the electrophotographic member can be better controlled. Moreover, as mentioned later, the viscosity of the silicone oil is preferably 20 mm ² / s or more and 200 mm ² / s or less, and more preferably 30 mm ² / s or more and 100 mm ² / s or less.

[Conductive fine particles]
As a measure of the volume resistivity of the conductive elastic layer, it is preferably 1 × 10 ² Ωcm or more and 1 × 10 ¹⁶ Ωcm or less in an environment of a temperature of 23 ° C. and a relative humidity of 50%. By setting it within this range, it becomes easier to appropriately charge the photoconductor by discharge. Therefore, you may contain well-known electroconductive fine particles in an electroconductive elastic layer. Examples of the conductive fine particles include fine particles of metal oxide, metal, carbon black, and graphite. Moreover, these electroconductive fine particles can be used individually by 1 type or in combination of 2 or more types. As a standard of the content of the conductive fine particles in the conductive elastic layer, it is 2 to 200 parts by mass, particularly 5 to 100 parts by mass with respect to 100 parts by mass of the binder.

[Method of forming conductive elastic layer]
A method for forming the conductive elastic layer is exemplified below. First, a coating layer of a composition in which hollow resin particles are dispersed in a binder is formed on a conductive substrate. Thereafter, by polishing the surface of the coating layer, a part of the shell of the hollow resin particles is removed to form a bowl shape having an opening, and the edge portion of the opening of the bowl-shaped resin particle and the inner wall of the resin particle And a convex part derived from the edge part of the opening of the bowl-shaped resin particles (hereinafter referred to as a "concave shape due to the opening of the bowl-shaped resin particles") Called). Next, the conductivity of the material present on the surface of the coating layer is adjusted by applying conductive fine particles to the recesses, or by heat treatment of the coating layer in an oxygen-containing atmosphere.

  Hereinafter, each process of the formation method of an electroconductive elastic layer is demonstrated in detail. The coating layer before the polishing step is referred to as “preliminary coating layer”. In addition, the “shell of hollow resin particles” in the raw material of the electrophotographic member is the “bowl-shaped resin particle shell” in the electrophotographic member in which the bowl-shaped resin particles having openings are formed by polishing. It is called “Bowl”.

[Dispersion of resin particles in pre-coating layer]
First, a method for dispersing hollow resin particles in the preliminary coating layer will be described. As one method, a coating film of a conductive resin composition in which hollow resin particles containing a gas are dispersed in a binder is formed on a substrate, and the coating film is dried, cured, or A method for performing crosslinking and the like can be exemplified. In addition, conductive particles can be contained in the conductive resin composition. As a material used for the hollow resin particles, a resin having a polar group is preferable from the viewpoint of low gas permeability and high resilience, and a resin having a unit represented by the following chemical formula (5) is more preferable. . In particular, it is more preferable to have both the unit represented by the chemical formula (5) and the unit represented by the chemical formula (9) from the viewpoint of easily controlling the polishing properties.

化学式（５）中、Ａは、下記化学式（６）、（７）及び（８）から選択される少なくとも１種である。Ｒ１は、水素原子もしくは炭素数１から４のアルキル基である。

In the chemical formula (5), A is at least one selected from the following chemical formulas (6), (7) and (8). R1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

化学式（９）中、Ｒ２は、水素原子もしくは炭素数１から４のアルキル基であり、Ｒ３は、水素原子もしくは炭素数１から１０のアルキル基である。

In the chemical formula (9), R2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R3 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

  As another method, a method of using a thermally expandable microcapsule that includes an encapsulated substance inside the particle and expands the encapsulated substance by applying heat to form hollow resin particles can be exemplified. In this method, a conductive resin composition in which thermally expandable microcapsules are dispersed in a binder is prepared, and this composition is coated on a conductive substrate, followed by drying, curing, or crosslinking. In the case of this method, the encapsulated substance can be expanded by heat at the time of drying, curing, or crosslinking of the binder used for the preliminary coating layer to form hollow resin particles. At that time, the particle size can be controlled by controlling the temperature condition.

  When using thermally expandable microcapsules, it is necessary to use a thermoplastic resin as a binder. The following are mentioned as a thermoplastic resin. Acrylonitrile resin, vinyl chloride resin, vinylidene chloride resin, methacrylic acid resin, styrene resin, butadiene resin, urethane resin, amide resin, methacrylonitrile resin, acrylic acid resin, acrylic ester resin, methacrylic ester resin. Among them, in particular, it is possible to use at least one thermoplastic resin selected from acrylonitrile resin, vinylidene chloride resin, and methacrylonitrile resin exhibiting high impact resilience in forming the bowl shape shown in FIG. preferable. These thermoplastic resins can be used individually by 1 type or in combination of 2 or more types. Furthermore, the monomer used as the raw material of these thermoplastic resins is copolymerized, and it is good also as a copolymer.

  The substance to be encapsulated in the thermally expandable microcapsule is preferably a substance that expands as a gas at a temperature lower than the softening point of the thermoplastic resin, and examples thereof include the following. Low boiling liquids such as propane, propylene, butene, normal butane, isobutane, normal pentane and isopentane, and high boiling liquids such as normal hexane, isohexane, normal heptane, normal octane, isooctane, normal decane and isodecane.

  The heat-expandable microcapsules can be produced by a known production method such as a suspension polymerization method, an interfacial polymerization method, an interfacial precipitation method, or a submerged drying method. For example, in the suspension polymerization method, a polymerizable monomer, a substance to be encapsulated in the thermally expandable microcapsule, and a polymerization initiator are mixed, and this mixture is mixed in an aqueous medium containing a surfactant and a dispersion stabilizer. Examples of the method include suspension polymerization after being dispersed in the solution. A compound having a reactive group that reacts with the functional group of the polymerizable monomer, or an organic filler can also be added.

  The following can be illustrated as a polymerizable monomer. Acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, vinylidene chloride, vinyl acetate; acrylic acid ester (methyl acrylate, ethyl Acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, isobornyl acrylate, cyclohexyl acrylate, benzyl acrylate); methacrylic acid ester (methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate) , Isobornyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate); styrenic mono Mer, acrylamide, substituted acrylamide, methacrylamide, substituted methacrylamide, butadiene, ε-caprolactam, polyether, isocyanate. These polymerizable monomers can be used alone or in combination of two or more.

  Although it does not specifically limit as a polymerization initiator, The initiator soluble in a polymerizable monomer is preferable, and a well-known peroxide initiator and an azo initiator can be used. Of these, azo initiators are preferred. Examples of azo initiators are listed below. 2,2'-azobisisobutyronitrile, 1,1'-azobiscyclohexane 1-carbonitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile. Of these, 2,2'-azobisisobutyronitrile is preferable. As for the usage-amount of a polymerization initiator, 0.01-5 mass parts is preferable with respect to 100 mass parts of polymerizable monomers.

  As the surfactant, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, and a polymer type dispersant can be used. As for the usage-amount of surfactant, 0.01-10 mass parts is preferable with respect to 100 mass parts of polymerizable monomers. Examples of the dispersion stabilizer include the following. Organic fine particles (polystyrene fine particles, polymethyl methacrylate fine particles, polyacrylic acid fine particles and polyepoxide fine particles), silica (colloidal silica), calcium carbonate, calcium phosphate, aluminum hydroxide, barium carbonate, magnesium hydroxide and the like. As for the usage-amount of a dispersion stabilizer, 0.01-20 mass parts is preferable with respect to 100 mass parts of polymerizable monomers.

  The suspension polymerization is preferably performed in a sealed state using a pressure vessel. Moreover, after suspending a polymeric raw material with a disperser etc., it may transfer to a pressure-resistant container and may carry out suspension polymerization, and may be suspended in a pressure-resistant container. The polymerization temperature is preferably 50 ° C to 120 ° C. The polymerization may be performed at atmospheric pressure, but may be performed under pressure (at a pressure obtained by adding 0.1 to 1 MPa to atmospheric pressure) so as not to vaporize the substance to be included in the thermal expansion microcapsule. preferable. After completion of the polymerization, solid-liquid separation and washing may be performed by centrifugation or filtration. In the case of solid-liquid separation or washing, thereafter, drying or pulverization may be performed below the softening temperature of the resin constituting the thermally expanded microcapsule. Drying and pulverization can be performed by a known method, and an air dryer, a normal air dryer, and a Nauta mixer can be used. Further, drying and pulverization can be simultaneously performed by a pulverization dryer. Surfactants and dispersion stabilizers can be removed by repeated washing and filtration after production.

[Other components constituting the conductive elastic layer]
In addition to the above, the conductive elastic layer may contain insulating particles and additives such as softening oil and plasticizer in order to adjust the hardness. The plasticizer is preferably a polymer type, and the weight average molecular weight is preferably 2000 or more, more preferably 4000 or more. Furthermore, resin materials other than anti-aging agents, fillers, processing aids, tackifiers, anti-tack agents, dispersants, and roughened particles may be included as materials that impart various functions. The following are mentioned as a resin particle. Polymethyl methacrylate particles, polyethylene particles, silicone rubber particles, polyurethane particles, polystyrene particles, amino resin particles, or phenol resin particles.

[Method for forming preliminary coating layer]
Then, the formation method of a preliminary coating layer is demonstrated. As a method for forming the preliminary coating layer, a layer of the conductive resin composition is formed on the conductive substrate by a coating method such as electrostatic spray coating, dipping coating or roll coating, and this layer is dried, heated, crosslinked, etc. The method of hardening | curing is mentioned. Moreover, the method of adhere | attaching or coat | covering the sheet | seat shape or tube-shaped layer which formed and hardened | cured the conductive resin composition into the predetermined film thickness with respect to a conductive base | substrate is mentioned. Furthermore, there is a method in which the conductive resin composition is placed in a mold in which a conductive substrate is placed and cured to form a preliminary coating layer. In particular, when the binder is rubber, the conductive substrate and the unvulcanized rubber composition can be integrally extruded by using an extruder equipped with a cross head. A crosshead is an extrusion die that is used at the tip of a cylinder of an extruder, which is used to form a coating layer for electric wires and wires. Then, after passing through drying, curing, cross-linking, etc., the surface of the preliminary coating layer is polished, and a part of the shell of the hollow resin particles is removed to obtain a bowl shape. As a polishing method, a cylindrical polishing method or a tape polishing method can be used. Examples of the cylindrical polishing machine include a traverse type NC cylindrical polishing machine and a plunge cut type NC cylindrical polishing machine.

(A) When the thickness of the preliminary coating layer is 5 times or less the average particle size of the hollow resin particles When the thickness of the preliminary coating layer is 5 times or less the average particle size of the hollow resin particles, In many cases, convex portions derived from hollow resin particles are formed on the surface. In this case, a part of the convex portion derived from the hollow resin particles can be polished until the hollow inner wall of the resin particles is exposed to form a bowl shape, and an uneven shape can be formed by opening the bowl-shaped resin particles. . In this case, it is more preferable to use a tape polishing method in which the pressure applied to the preliminary coating layer during polishing is relatively small. As an example, the preferable ranges as the polishing conditions for the preliminary coating layer when using the tape polishing method are shown below.

  The abrasive tape is obtained by dispersing abrasive grains in a resin and applying it to a sheet-like substrate. Examples of the abrasive grains include aluminum oxide, chromium oxide, iron oxide, diamond, cerium oxide, corundum, silicon nitride, silicon carbide, molybdenum carbide, tungsten carbide, titanium carbide, and silicon oxide. The average particle size of the abrasive grains is preferably 0.01 μm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less. The average particle size of the abrasive grains is the median diameter D50 measured by centrifugal sedimentation. The preferable range of the count of the polishing tape having the above-mentioned preferable range of abrasive grains is 500 or more and 20000 or less, and more preferably 1000 or more and 10,000 or less.

  Specific examples of the polishing tape are listed below. “MAXIMA LAP, MAXIMA T type” (trade name, Reflight Co., Ltd.), “RAPICA” (trade name, manufactured by KOVAX), “Microfinishing film”, “wrapping film” (trade name, Sumitomo 3M Co., Ltd. (new company name) : 3M Japan)), mirror film, wrapping film (trade name, manufactured by Sankyo Rikagaku Co., Ltd.), Mipox (trade name, manufactured by Mipox (former company name: Nippon Micro Coating Co., Ltd.)).

  The feed rate of the polishing tape is preferably 10 mm / min or more and 500 mm / min or less, more preferably 50 mm / min or more and 300 mm / min or less. The pressure applied to the preliminary coating layer of the polishing tape is preferably 0.01 MPa or more and 0.4 MPa or less, and more preferably 0.1 MPa or more and 0.3 MPa or less. In order to control the pressing pressure, a backup roller may be brought into contact with the preliminary coating layer via a polishing tape. Moreover, in order to obtain a desired shape, you may perform a grinding | polishing process over multiple times. The number of rotations is preferably set to 10 rpm or more and 1000 rpm or less, and more preferably set to 50 rpm or more and 800 rpm or less. By setting it as said conditions, the uneven | corrugated shape by opening of a bowl-shaped resin particle can be more easily formed in the surface of a preliminary coating layer. Even if the thickness of the preliminary coating layer is out of the above range, it is possible to form an uneven shape by opening the bowl-shaped resin particles by the method (b) described below.

(B) When the thickness of the preliminary coating layer is more than 5 times the average particle size of the hollow resin particles When the thickness of the preliminary coating layer exceeds 5 times the average particle size of the hollow resin particles, In some cases, convex portions derived from hollow resin particles are not formed on the surface. In such a case, it is possible to form a concavo-convex shape due to the opening of the bowl-shaped resin particles by utilizing the difference in abrasiveness between the hollow resin particles and the material of the preliminary coating layer. The hollow resin particles have a high resilience because they contain a gas inside. On the other hand, as the binder for the preliminary coating layer, a rubber or resin having relatively low impact resilience and small elongation is selected. Thereby, the preliminary coating layer can be easily polished, and the hollow resin particles can be hardly polished. When the pre-coating layer in the above state is polished, the hollow resin particles are not polished in the same state as the pre-coating layer, and may have a bowl shape in which a part of the shell of the hollow resin particles is removed. it can. Thereby, the uneven | corrugated shape by the opening of a bowl-shaped resin particle can be formed in the surface of a preliminary | backup coating layer. Since this method is a method of forming a concavo-convex shape by utilizing the difference in abrasiveness between the hollow resin particles and the material of the preliminary coating layer, the material (binder) used for the preliminary coating layer is rubber. Is preferred. Among these, it is particularly preferable to use acrylonitrile butadiene rubber, styrene butadiene rubber, or butadiene rubber from the viewpoint of low resilience and small elongation.

  As a polishing method, a cylindrical polishing method or a tape polishing method can be used. However, since it is necessary to remarkably bring out a difference in the polishing properties of materials, conditions for polishing faster are preferable. From this viewpoint, it is more preferable to use a cylindrical polishing method. Among the cylindrical polishing methods, it is more preferable to use the plunge cut method from the viewpoint that the longitudinal direction of the preliminary coating layer can be simultaneously polished and the polishing time can be shortened. Further, in order to form the protruding first convex region, a spark-out process (polishing process at an intrusion rate of 0 mm / min) conventionally performed from the viewpoint of making the polished surface uniform is as short as possible. Or preferably not. As an example, the rotational speed of the plunge cut type cylindrical grinding wheel is preferably 1000 to 4000 rpm, particularly 2000 to 4000 rpm. The penetration rate into the preliminary coating layer is more preferably 5 to 30 mm / min, particularly 10 to 30 mm / min. At the end of the intrusion step, a break-in step may be provided on the polished surface, and it is preferable that the intrusion speed is 0.1 or more and 0.2 mm / min or less within 2 seconds. The spark-out process (polishing process at an intrusion rate of 0 mm / min) is preferably 3 seconds or less. The number of rotations is preferably set to 50 rpm or more and 500 rpm or less, and more preferably set to 200 rpm or more. By setting it as the said conditions, the uneven | corrugated formation by opening of a bowl-shaped resin particle can be more easily formed in the surface of a preliminary coating layer. In the following description, the polished pre-coating layer is simply referred to as “coating layer”.

[Surface finishing method]
The electrophotographic member according to the present invention suppresses “transition in the elastic deformation direction” by having bowl-shaped resin particles satisfying the mathematical formula (1) on the surface thereof. And in order to satisfy | fill said Numerical formula (1), it is preferable to perform the surface finishing shown below moderately. This surface finishing is preferably performed as a subsequent process of the above-described polishing process. As the surface finishing means, the following two can be exemplified.
[Method 1] A pressure-rotation heating process in which heating is performed while applying pressure by a pressure-contact member and rotating the pressure-contact member.
[Method 2] A step of performing surface finish grinding after heat-treating the surface of the coating layer in an oxygen-containing atmosphere (such as an air atmosphere).

  First, [Method 1] will be described with reference to FIG. FIG. 8 shows a pressure vulcanization apparatus having a cylindrical pressure contact member used in the pressure contact rotation heating process. FIG. 8 (8a) is a top view and FIG. 8 (8b) is a side view. The cylindrical pressure contact member 62 rotated by the motor 67 and the central axis of the electrophotographic member 61 are held in parallel, and the axis of the cored bar exposed portions at both ends of the electrophotographic member 61 is not shifted by the holding member 66. To be held. The cylindrical pressure contact member 62 is set together with another pressure contact member 63 so as to be pressed by springs 64 from both sides of the electrophotographic member, and by rotating the cylindrical pressure contact member 62, the electrophotography is performed. The member and the cylindrical pressure contact member 63 are rotated by being driven. Thereby, the 1st convex part area | region originating in an edge part can be bent in the inner side direction of the recessed part of a bowl. In order to fix in the above-mentioned state, it is preferable that the heating temperature of the pressure contact member is set to 140 ° C. or higher and 240 ° C. or lower where rubber vulcanization is easy to proceed, and press vulcanization is performed for 1 to 120 minutes. In FIG. 8, reference numeral 65 denotes a slider.

  Next, [Method 2] will be described. First, a preferable heat treatment method will be described in detail below. In the heat treatment under an oxygen-containing atmosphere, the degree of cross-linking of the resin of the bowl-shaped resin particles increases due to the progress of oxidative cross-linking. The more the oxidative crosslinking proceeds, the harder the resin. In order to satisfy the formula (1), it is preferable to cure the resin appropriately, and the degree of oxidative crosslinking can be adjusted by the heat treatment temperature and the oxygen concentration of the crosslinked portion. Regarding the heating temperature, the higher the temperature, the higher the degree of crosslinking. As for the oxygen concentration, the higher the oxygen concentration in the cross-linking part, the more the oxidative cross-linking can proceed. Therefore, it is possible to control the hardness of the resin by controlling the heating temperature and the oxygen concentration in the resin. At this time, as a technique for controlling the oxygen concentration in the resin, it is useful to adjust the oxygen permeability of the bowl-shaped resin particles in the bowl.

  Therefore, as the material for forming the bowl of bowl-shaped resin particles, acrylonitrile resin, vinylidene chloride resin, methacrylonitrile resin, methyl methacrylate resin, and copolymers of these resins, which have low oxygen gas permeability, are used. In particular, it is more preferable to use acrylonitrile resin or vinylidene chloride resin. Thereby, the hardness of the resin described above can be more easily performed.

  On the other hand, the degree of oxidative crosslinking can be controlled by changing the temperature of the heat treatment, and this method is a useful technique for controlling the hardness of the resin. However, the progress of oxidative crosslinking by heating is accelerated as the temperature increases, but at the same time, embrittlement of the resin proceeds. When embrittlement of the resin occurs, the edge portion may be removed during surface finish grinding, and the mathematical formula (1) may not be satisfied. Therefore, the heating temperature is preferably controlled to 180 ° C. or higher and 210 ° C. or lower, and more preferably 190 ° C. or higher and 200 ° C. or lower. The heat treatment time is preferably 10 to 200 minutes.

  In addition, about the method of heat processing, although well-known means, such as a hot-air continuous furnace, oven, a near infrared heating method, a far infrared heating method, can be used, it coat | covers in oxygen-containing atmosphere (in the presence of oxygen). The technique is not particularly limited as long as the surface of the layer can be heat-treated.

  The resin as the binder is preferably a resin that promotes the effect of oxidative crosslinking when heated in an oxygen-containing atmosphere. Specifically, styrene butadiene rubber (SBR), butyl rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butadiene rubber (BR) having a double bond in the molecule and high heat resistance are used. It is preferable to do. The conductive elastic layer is preferably formed by thermally cross-linking a layer of a conductive heat-crosslinkable rubber composition containing a crosslinked rubber as a binder and containing conductive fine particles in the presence of oxygen.

[Surface finish grinding]
In order to perform the above [Method 2], a preferable surface finish grinding technique will be described in detail below. As an example of surface finish grinding, preferred ranges for polishing conditions for the preliminary coating layer when using the tape polishing method shown in FIG. 9 are shown below.

  The polishing tape 91 is obtained by dispersing abrasive grains in a resin and applying it to a sheet-like substrate. Examples of the abrasive grains include aluminum oxide, chromium oxide, iron oxide, diamond, cerium oxide, corundum, silicon nitride, silicon carbide, molybdenum carbide, tungsten carbide, titanium carbide, and silicon oxide. The average particle size of the abrasive grains is preferably 0.01 μm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less. The average particle size of the abrasive grains is the median diameter D50 measured by centrifugal sedimentation. The preferable range of the count of the polishing tape having the above-mentioned preferable range of abrasive grains is 500 or more and 20000 or less, and more preferably 1000 or more and 10,000 or less.

  Specific examples of the polishing tape are listed below. “MAXIMA LAP, MAXIMA T type” (trade name, Reflight Co., Ltd.), “RAPICA” (trade name, manufactured by KOVAX), “Microfinishing film”, “wrapping film” (trade name, Sumitomo 3M Co., Ltd. (new company name) : 3M Japan)), mirror film, wrapping film (trade name, manufactured by Sankyo Rikagaku Co., Ltd.), Mipox (trade name, manufactured by Mipox (former company name: Nippon Micro Coating Co., Ltd.)).

  The pressure applied to the preliminary coating layer of the polishing tape 91 is preferably 0.01 MPa or more and 0.4 MPa or less, and more preferably 0.1 MPa or more and 0.3 MPa or less. In order to control the pressing pressure, a backup roller 93 may be brought into contact with the preliminary coating layer via the polishing tape 91, and a tape guide 92 may be used to prevent the polishing tape 91 from loosening. . Moreover, in order to obtain a desired shape, you may perform a grinding | polishing process over multiple times. The rotational speed of the conductive roller 94 is preferably set to 500 rpm or more and 6000 rpm or less, and more preferably set to 1000 rpm or more and 4000 rpm or less. By setting it as said conditions, the 1st convex part area | region which protruded from the edge part hardened | cured by the said heat processing can be bent in the inner direction of the recessed part of a bowl, and the uneven | corrugated shape which satisfy | fills Numerical formula (1) can be formed.

  As for the surface finish grinding method, known means such as a buffing method and a cylindrical grinding method can be used. However, these methods are particularly suitable if they can form a surface shape satisfying the formula (1). It is not limited to.

The method for forming the conductive elastic layer has been described above. Examples of the method for producing the electrophotographic member according to the present invention include the following [1] to [3].
[1] Step 1 in which a coating layer of a composition in which hollow resin particles are dispersed in a binder is formed on a conductive substrate to produce a conductive roller, the surface of the coating layer is polished by polishing A bowl shape having an opening by removing a part of the shell of the resin particle having a shape, and a concave portion defined by an edge portion of the opening of the bowl-shaped resin particle and an inner wall of the resin particle on the surface of the coating layer; Step 2 of forming a convex portion derived from the edge portion of the opening, and a cylindrical pressure contact member having a rotation axis parallel to the rotation axis of the conductive substrate are pressed against the conductive roller to rotate both A method for producing an electrophotographic member, comprising: a press-contact rotary heating step 3 in which heating is performed.
[2] In the above method, instead of step 3, step 3 ′ in which the conductive roller is heat-treated in an oxygen-containing atmosphere, and step 4 in which the surface finish grinding of the coating layer is performed by a tape polishing method. The manufacturing method of the member for electrophotography which has.
[3] A step of forming a coating layer of a thermally crosslinkable rubber composition containing conductive fine particles, thermally crosslinkable rubber, and hollow resin particles on the substrate, and polishing the surface of the coating layer, A part of the shell of the hollow resin particle is deleted to form a bowl-shaped resin particle having an opening, and the bowl-shaped resin particle is held with the edge of the opening exposed on the surface. A step of forming a layer, and a heat-crosslinkable rubber in the coating layer is heat-crosslinked in the presence of oxygen to form a recess defined by the edge of the opening and the inner wall of the resin particle; A method for producing an electrophotographic member, comprising: a step of obtaining an electrophotographic member having a convex portion derived from an edge portion on a surface and a part of the surface being formed of a conductive elastic layer.

<Electrophotographic device>
The electrophotographic image forming apparatus according to the present invention has an electrophotographic member and an electrophotographic photosensitive member. The electrophotographic member according to the present invention can be used in this electrophotographic image forming apparatus.

  FIG. 10 shows a schematic configuration of an example of an electrophotographic image forming apparatus according to the present invention. The electrophotographic apparatus includes an electrophotographic photosensitive member, a charging device that charges the electrophotographic photosensitive member, a latent image forming device that performs exposure, a developing device that develops a toner image, a transfer device that transfers to a transfer material, and an electrophotographic photosensitive member. And a fixing device for fixing the toner image. The roller-shaped electrophotographic member according to the present invention can be used as a charging roller provided in the charging device of the electrophotographic image forming apparatus.

  The electrophotographic photosensitive member 102 is a rotary drum type having a photosensitive layer on a conductive substrate. The electrophotographic photosensitive member is driven to rotate at a predetermined peripheral speed (process speed) in the direction of the arrow. The charging device includes a contact-type charging roller 101 that is placed in contact with the electrophotographic photosensitive member 102 by contacting the electrophotographic photosensitive member 102 with a predetermined pressing force. The charging roller 101 is driven rotation that rotates in accordance with the rotation of the electrophotographic photosensitive member 102, and charges the electrophotographic photosensitive member 102 to a predetermined potential by applying a predetermined DC voltage from the charging power source 109. As a latent image forming apparatus (not shown) for forming an electrostatic latent image on the electrophotographic photosensitive member 102, an exposure apparatus such as a laser beam scanner is used. An electrostatic latent image is formed by irradiating the uniformly charged electrophotographic photosensitive member 102 with exposure light 107 corresponding to image information.

  The developing device includes a developing sleeve or a developing roller 103 disposed close to or in contact with the electrophotographic photosensitive member 102. The developing device forms a toner image by developing the electrostatic latent image by reversal development of toner electrostatically processed to the same polarity as the charging polarity of the electrophotographic photosensitive member. The transfer device has a contact-type transfer roller 104. The toner image is transferred from the electrophotographic photosensitive member to a transfer material such as plain paper. The transfer material is conveyed by a paper feeding system having a conveying member.

  The cleaning device has a blade-type cleaning member 106 and a collection container 108, and after the developed toner image is transferred to a transfer material, the transfer residual toner remaining on the electrophotographic photosensitive member 102 is mechanically scraped off. to recover. Here, it is possible to omit the cleaning device by adopting a development simultaneous cleaning system in which the transfer device collects the transfer residual toner. The toner image transferred to the transfer material is fixed to the transfer material by passing between a fixing belt 105 heated by a heating device (not shown) and a roller disposed opposite to the fixing belt. .

<Process cartridge>
The process cartridge according to the present invention includes an electrophotographic member and an electrophotographic photosensitive member, and is configured to be detachable from the main body of the electrophotographic image forming apparatus. FIG. 11 shows a schematic configuration of an example of a process cartridge according to the present invention. This process cartridge is configured such that the electrophotographic photosensitive member 102, the charging roller 101, the developing roller 103, the cleaning member 106, and the like are integrated and detachable from the main body of the electrophotographic image forming apparatus. The electrophotographic member according to the present invention can be used as a charging roller provided in the process cartridge.

  Hereinafter, the present invention will be described in more detail with reference to specific production examples and examples. Prior to Examples, Production Examples A1 to A10 (Production of Resin Particles No. 1 to No. 10), Measurement Methods for Volume Average Particle Diameter of Resin Particles, Production Examples B1 to B12 (Conductive Rubber Composition Nos. 1 to 1) Production of No. 12 will be described. In addition, all the parts and% of the following Examples and Comparative Examples are based on mass unless otherwise specified.

<Production Example A1: Resin particle No. Production of 1>
An aqueous mixed solution comprising 4000 parts by mass of ion-exchanged water, 9 parts by mass of colloidal silica as a dispersion stabilizer and 0.15 parts by mass of polyvinylpyrrolidone was prepared. Next, 50 parts by mass of acrylonitrile, 45 parts by mass of methacrylonitrile and 5 parts by mass of methyl acrylate as a polymerizable monomer, 12.5 parts by mass of normal hexane as an inclusion substance, and dicumyl peroxide 0 as a polymerization initiator An oily mixture consisting of .75 parts by mass was prepared. This oily mixture was added to the aqueous mixture, and 0.4 parts by mass of sodium hydroxide was further added to prepare a dispersion.

  The obtained dispersion was stirred and mixed for 3 minutes using a homogenizer, charged into a nitrogen-substituted polymerization reaction vessel, and reacted at 60 ° C. for 20 hours with stirring at 400 rpm to prepare a reaction product. About the obtained reaction product, after repeating filtration and water washing, the resin particle was produced by drying at 80 degreeC for 5 hours. By crushing and classifying the resin particles with a sonic classifier, resin particles No. 1 was obtained.

<Production Example A2: Resin particle No. Production of 2>
In Production Example A1, the resin particle No. was changed in the same manner except that the classification conditions were changed. 2 was obtained.

<Production Examples A3 and A5-A8: Resin particle No. 3 and no. 5-No. Production of 8>
Prepare and classify resin particles by the same method as in Production Example A1, except that the amount of colloidal silica used, the type and amount of polymerizable monomer, and one or more of the number of stirring revolutions during polymerization are changed. Resin particle No. 3 and no. 5-No. 8 was obtained.

<Production Example A4: Resin particle No. Production of 4>
In Production Example A3, the resin particle No. was changed in the same manner except that the classification conditions were changed. 4 was obtained.

<Production Example A9: Resin particle No. Production of 9>
In Production Example A7, the resin particle No. was changed in the same manner except that the classification conditions were changed. 9 was obtained.

<Production Example A10: Resin particle No. Production of 10>
In Production Example A8, the resin particle No. was changed in the same manner except that the classification conditions were changed. 10 was obtained.

<Measurement of volume average particle diameter of resin particles>
Resin particle No. 1-No. The volume average particle size of 10 was measured by a laser diffraction type particle size distribution meter (trade name: Coulter LS-230 type particle size distribution meter, manufactured by Coulter). For the measurement, an aqueous module was used, and pure water was used as a measurement solvent. The measurement system of the particle size distribution meter was washed with pure water for about 5 minutes, 10 to 25 mg of sodium sulfite was added to the measurement system as an antifoaming agent, and the background function was executed. Next, 3 to 4 drops of a surfactant was added to 50 ml of pure water, and 1 mg to 25 mg of a measurement sample (resin particles) was further added. The aqueous solution in which the sample was suspended was subjected to dispersion treatment for 1 to 3 minutes with an ultrasonic disperser to prepare a test sample solution. Gradually add the test sample solution into the measurement system of the measurement device, and adjust the test sample concentration in the measurement system so that the polarization scattering intensity difference (PIDS) on the screen of the device is 45% or more and 55% or less. And measured. The volume average particle diameter Dv was calculated from the obtained volume distribution. Resin particle No. 1-No. Table 1 shows the formulation of the ten materials, the stirring conditions during polymerization, and the volume average particle diameter.

＜製造例Ｂ１：導電性ゴム組成物Ｎｏ．１の製造＞
アクリロニトリルブタジエンゴム（ＮＢＲ）（商品名：Ｎ２３０ＳＶ，ＪＳＲ社製）１００質量部に対し、表２の成分（１）の欄に示す他の材料を加えて、５０℃に調節した密閉型ミキサーにて１５分間混練した。これに、表２の成分（２）の欄に示す材料を添加した。次いで、温度２５℃に冷却した二本ロール機にて１０分間混練し、導電性ゴム組成物Ｎｏ．１を得た。

<Production Example B1: Conductive rubber composition No. Production of 1>
In a closed mixer adjusted to 50 ° C. by adding other materials shown in the column of component (1) in Table 2 to 100 parts by mass of acrylonitrile butadiene rubber (NBR) (trade name: N230SV, manufactured by JSR) Kneaded for 15 minutes. To this, the material shown in the column of component (2) in Table 2 was added. Subsequently, it knead | mixes for 10 minutes with the two roll machine cooled to the temperature of 25 degreeC, and conductive rubber composition No.1. 1 was obtained.

＜製造例Ｂ２：導電性ゴム組成物Ｎｏ．２の製造＞
アクリロニトリルブタジエンゴム（ＮＢＲ）（商品名：Ｎ２３０ＳＶ，ＪＳＲ社製）１００質量部に対し、表３の成分（１）の欄に示す他の材料を加えて、５０℃に調節した密閉型ミキサーにて１５分間混練した。これに、表３の成分（２）の欄に示す材料を添加した。次いで、温度２５℃に冷却した二本ロール機にて１０分間混練し、導電性ゴム組成物Ｎｏ．２を得た。

<Production Example B2: Conductive rubber composition No. Production of 2>
In a closed mixer adjusted to 50 ° C. by adding other materials shown in the column of component (1) in Table 3 to 100 parts by mass of acrylonitrile butadiene rubber (NBR) (trade name: N230SV, manufactured by JSR) Kneaded for 15 minutes. The material shown in the column of the component (2) of Table 3 was added to this. Subsequently, it knead | mixes for 10 minutes with the two roll machine cooled to the temperature of 25 degreeC, and conductive rubber composition No.1. 2 was obtained.

＜製造例Ｂ３〜Ｂ８：導電性ゴム組成物Ｎｏ．３〜Ｎｏ．８の製造＞
シリコーンオイルのオイル種、樹脂粒子（樹脂粒子Ｎｏ．３〜Ｎｏ．８）を表５に示す条件とした以外は、製造例Ｂ１と同様にして導電性ゴム組成物Ｎｏ．３〜Ｎｏ．８を得た。なお、使用したシリコーンオイルの詳細を表４に示す。

<Production Examples B3 to B8: Conductive rubber composition No. 3-No. Production of 8>
The conductive rubber composition No. 1 was prepared in the same manner as in Production Example B1 except that the oil type of the silicone oil and the resin particles (resin particles No. 3 to No. 8) were changed to the conditions shown in Table 5. 3-No. 8 was obtained. Details of the used silicone oil are shown in Table 4.

＜製造例Ｂ９〜Ｂ１２：導電性ゴム組成物Ｎｏ．９〜Ｎｏ．１２の製造＞
製造例Ｂ５において、アクリロニトリルブタジエンゴムをブタジエンゴム（ＢＲ）（商品名：ＪＳＲ ＢＲ０１、ＪＳＲ社製）に変更し、樹脂粒子、カーボンブラックを表５に示す条件とした以外は、製造例Ｂ２と同様にして導電性ゴム組成物Ｎｏ．９〜Ｎｏ．１２を得た。

<Production Examples B9 to B12: Conductive rubber composition No. 9-No. Production of 12>
In Production Example B5, except that acrylonitrile butadiene rubber was changed to butadiene rubber (BR) (trade name: JSR BR01, manufactured by JSR Corporation), and the resin particles and carbon black were changed to the conditions shown in Table 5, the same as Production Example B2. Conductive rubber composition No. 9-No. 12 was obtained.

  The conductive rubber composition No. 1-No. The 12 formulations are shown in Table 5.

＜実施例１＞
１．導電性基体
直径６ｍｍ、長さ２５２．５ｍｍのステンレス鋼製の基体に、カーボンブラックを１０質量％含有させた熱硬化性樹脂を塗布し、乾燥したものを導電性基体として使用した。

<Example 1>
1. Conductive substrate A thermosetting resin containing 10% by mass of carbon black was applied to a stainless steel substrate having a diameter of 6 mm and a length of 252.5 mm, and the dried one was used as the conductive substrate.

2. Formation of Conductive Elastic Layer Using an extrusion molding apparatus equipped with a crosshead, the conductive rubber composition No. 1 produced in Production Example B1 in a cylindrical shape on the peripheral surface with the conductive substrate as the central axis. 1 was coated. The thickness of the conductive rubber composition was adjusted to 1.75 mm.

  The extruded roller was vulcanized at 160 ° C. for 1 hour in a hot air oven, and then the end of the rubber layer was removed to make the length 224.2 mm, and a roller having a preliminary coating layer was produced. The outer peripheral surface of the obtained roller was polished using a plunge cut type cylindrical polishing machine. Vitrified grindstones were used as the abrasive grains, the abrasive grains were green silicon carbide (GC), and the grain size was 100 mesh. The rotational speed of the roller was 350 rpm, and the rotational speed of the grinding wheel was 2050 rpm. Polishing was performed by setting the cutting speed to 20 mm / min and setting the spark-out time (time at the cutting 0 mm) to 0 seconds to produce a conductive roller having a conductive elastic layer (coating layer). The thickness of the conductive elastic layer was adjusted to 1.5 mm. The crown amount of this roller (the average value of the difference between the outer diameter at the center and the outer diameter at positions 90 mm away from the center toward both ends) was 120 μm.

  After polishing, the edge was cured by post-heating treatment at 180 ° C. for 1 hour in an air atmosphere using a hot air oven. Using the surface finish grinding apparatus shown in FIG. 9, the conductive roller rotating at 1000 rpm was subjected to surface finish grinding with lapping film WA abrasive grain # 2000 (trade name, manufactured by Sankyo Rikagaku Co., Ltd.). 1 was obtained. This electrophotographic member has on its surface a convex portion derived from the edge of the opening of the bowl-shaped resin particles, and a concave defined by the edge of the opening of the bowl-shaped resin particles and the inner wall of the resin particles. It had a conductive elastic layer.

  Table 8 shows the results of physical property measurement and image evaluation of the electrophotographic member performed by the following method.

3. 3. Evaluation of electrophotographic member 3-1. Measurement of shape of bowl-shaped resin particles (hereinafter also referred to as “bowl”) Measurement is performed by the following method. The measurement location is about the center part in the longitudinal direction of the electrophotographic member, the position 30 mm away from the center part in the direction of both ends, and the 5 parts in the longitudinal direction at positions 75 mm away from the center part in the direction of both ends. In addition, a total of 30 locations including 6 locations (phase 0 °, 60 °, 120 °, 180 °, 240 °, and 300 °) in the circumferential direction of the electrophotographic member. Using a laser microscope (trade name: LXM5 PASCAL: manufactured by Carl Zeiss), a range of 0.5 mm in the longitudinal direction and 0.5 mm in the circumferential direction (hereinafter referred to as “measurement range”) centering on each of these measurement points. Observe. By scanning the laser in the XY plane within the field of view to obtain two-dimensional image data of the surface, moving the focal point in the Z direction (the direction of the central axis of the electrophotographic member), and repeating the above scan Three-dimensional image data is obtained. As a result, first, the bowl-shaped resin particles exposed on the surface of the electrophotographic member have a recess defined by the edge of the opening and the inner wall of the resin particle, and a protrusion derived from the edge of the opening. Make sure you have In this measurement range, a bowl having a protruding first convex region having the highest point C farthest from the center point O of the rotation axis of the electrophotographic member is selected. A focused ion beam processing observation apparatus (trade name: FB-2000C, manufactured by Hitachi, Ltd.) is used for the selected bowl with respect to a cross section orthogonal to the rotation axis of the electrophotographic member passing through the highest point C of the first convex region. Use to cut out and take a cross-sectional image. From the cross-sectional image, L ₁ , L ₂ and θ shown in FIG. 1 are measured. Next, the D value in the mathematical formula (1) is calculated.

Bowls selected in each measurement range of the 30 measurement ranges are respectively bowl No. 1, ~ No. Table 6 shows the measured values of L ₁ , L ₂ and θ and the calculated value of D corresponding to each bowl as 30. This electrophotographic member No. 1 has bowl-shaped resin particles that satisfy the formula (1) in all 30 measurement ranges.

The average value of 30 L ₁ values obtained in 30 measurement ranges is defined as L _{1 (Ave),} and the average value of D values is calculated from the calculated D values of D> 0 for 30 D values. And D _(Ave) is shown in Table 8. Table 8 shows the ratio of the number of measurement ranges that satisfy D> 0, the number of measurement ranges that satisfy D ≦ 0, and the number of measurement ranges that satisfy D> 0 in 30 measurement ranges.

  Further, the “maximum diameter” was measured from the cross-sectional image as shown in FIG. The average value of the “maximum diameter” measured for a total of 30 bowl-shaped resin particles obtained was calculated as the average diameter. Table 7 shows the calculated average diameter values.

3-2. Image Evaluation A monochrome laser printer (“LBP6700” (trade name)) manufactured by Canon Inc., which is an electrophotographic apparatus having the configuration shown in FIG. 11, was modified to a process speed of 370 mm / sec. The attached charging roller is removed from the process cartridge for the printer, and instead of the electrophotographic member No. 1 was set as a charging roller. The charging roller was brought into contact with the electrophotographic photosensitive member with a pressing force of 4.9 N at one end and a total of 9.8 N at both ends. Further, a voltage was applied to the charging roller from the outside. The applied voltage was an AC voltage with a peak-peak voltage (Vpp) of 1800 V, a frequency (f) of 1350 Hz, and a DC voltage (Vdc) of -600 V. The resolution of the image was 600 dpi.

  The process cartridge was conditioned for 24 hours in a low-temperature and low-humidity environment having a temperature of 15 ° C. and a relative humidity of 10%, and then image evaluation was performed. Specifically, a halftone image (an image in which a horizontal line having a width of 1 dot and an interval of 2 dots is drawn in the direction perpendicular to the rotation direction of the electrophotographic photosensitive member) is output, and the obtained image is visually observed to form a dot shape. The presence or absence of image defects and the presence or absence of horizontal streak-like image defects due to banding were determined according to the following criteria.

[Evaluation of point-like images]
Rank 1: No spot-like image defect is observed.
Rank 2: A spot-like image defect is slightly observed.
Rank 3: It is recognized that a spot-like image defect occurs in a partial area corresponding to the rotation pitch of the charging roller.
Rank 4: Spot-like image defects are recognized over a wide area and are conspicuous.

[Evaluation of horizontal stripe image]
Rank 1: No horizontal streak-like image defect is observed.
Rank 2: A slight horizontal stripe-like image defect is recognized.
Rank 3: It is recognized that a horizontal streak-like image defect occurs in a part of the area corresponding to the rotation pitch of the charging roller.
Rank 4: Horizontal streak-like image defects are recognized over a wide area and are conspicuous.

<Examples 2 to 18>
In Example 1, except that the type of resin particles, the number of workpiece rotations during surface finish grinding, and the abrasive grain size of the wrapping film were changed to the conditions shown in Table 7, the electrophotographic member No. 2-No. 18 was produced. Table 8 shows the results of physical property measurement and image evaluation of each electrophotographic member. In the electrophotographic members of Examples 2 to 10, bowl-shaped resin particles satisfying Equation (1) are present in all 30 measurement ranges.

<Example 19>
By conducting the steps up to polishing in the same manner as in Example 1, a polished conductive roller was produced. Next, both sides of the conductive roller 61 are pressed by the pressing member 63 (end pressing member) pressed against the end simultaneously with the pressing vulcanization by the cylindrical pressing member 62 using the pressing vulcanizing apparatus schematically shown in FIG. The pressure welding was performed. As the pressure contact member 63, a concave portion having an arc shape of R = 1.5 mm was used. The temperature of the cylindrical pressure contact member was 160 ° C., the temperature of the pressure contact member 63 pressed against the end portion was 180 ° C., and pressure vulcanization was performed for 20 minutes. At that time, the springs 64 were adjusted so as to obtain a load of 1 kg on one side at both ends of the pressure vulcanizing apparatus. Further, after that, secondary vulcanization was performed for 30 minutes in a hot stove preheated to 180 ° C., and an electrophotographic member No. 1 having an R-face at the end was used. 19 was obtained. Table 8 shows the results of physical property measurement and image evaluation of this electrophotographic member. The cylindrical pressure contact member 62 has a so-called reverse crown shape (the outer diameter of the central portion in the longitudinal direction is smaller than the outer diameter of the end portion), and corresponds to the portion corresponding to the end portion of the roller rubber portion and the center. The outer diameter difference of 0.1 mm is provided.

＜比較例１〜４＞
導電性ゴム組成物を表９に示す材料に変更したこと以外は、実施例１と同様にして、研磨した導電性ローラを作製した。各導電性ローラの表面に対して、引用文献１に記載の条件と同様の以下に示す条件で、電子線照射により処理を行って、電子写真用部材Ｎｏ．２１〜Ｎｏ．２４を得た。電子線の照射には、最大加速電圧１５０ｋＶ、最大電子電流４０ｍＡの電子線照射装置（岩崎電気株式会社製）を用い、照射時には窒素ガスパージを行った。処理条件は加速電圧：１２５ｋＶ、電子電流：３５ｍＡ、処理速度：１．２７ｍ／ｍｉｎ、酸素濃度：１００ｐｐｍであった。電子写真用部材Ｎｏ．２１〜Ｎｏ．２４の物性測定及び画像評価の結果を表１０に示す。

<Comparative Examples 1-4>
A polished conductive roller was produced in the same manner as in Example 1 except that the conductive rubber composition was changed to the material shown in Table 9. The surface of each conductive roller was treated by electron beam irradiation under the following conditions similar to those described in Cited Document 1 to obtain an electrophotographic member No. 21-No. 24 was obtained. For the electron beam irradiation, an electron beam irradiation apparatus (manufactured by Iwasaki Electric Co., Ltd.) having a maximum acceleration voltage of 150 kV and a maximum electron current of 40 mA was used, and nitrogen gas purge was performed during irradiation. The treatment conditions were acceleration voltage: 125 kV, electron current: 35 mA, treatment speed: 1.27 m / min, and oxygen concentration: 100 ppm. Electrophotographic member No. 21-No. Table 10 shows the results of 24 physical property measurements and image evaluation.

実施例１〜１９では、電子写真用部材の表面形状が数式（１）を満たしているため、ポチ状画像及びバンディングによる横スジ状画像について、ともに良好な結果が得られた。一方、比較例１〜４では、電子写真用部材の表面形状が数式（１）を満たしていないため、バンディングによる横スジ状画像が発生した。

In Examples 1 to 19, since the surface shape of the electrophotographic member satisfies the mathematical formula (1), good results were obtained for both the potty image and the horizontal streak image by banding. On the other hand, in Comparative Examples 1 to 4, since the surface shape of the electrophotographic member did not satisfy Expression (1), a horizontal streak image was generated due to banding.

1: Conductive substrate 2: Conductive elastic layer 21: Conductive elastic layer 22: Conductive elastic layer 32: Electrophotographic member 41: Bowl-shaped resin particles 42: Conductive elastic layer 51: Bowl-shaped resin particles Opening 52: Concave portion of bowl-shaped resin particle 53: Convex portion of bowl-shaped resin particle 61: Electrophotographic member 62: Cylindrical pressure contact member 94: Electrophotographic member 101: Charging roller 102: Electrophotographic photosensitive member

Claims (15)

A roll-shaped electrophotographic member having a conductive substrate and a conductive elastic layer as a surface layer on the conductive substrate,
The conductive elastic layer includes a binder and bowl-shaped resin particles in which hollow resin particles are opened,
On the surface of the conductive elastic layer, the edge of the opening of the bowl-shaped resin particles is exposed,
The bowl-shaped resin particle has a concave portion defined by the edge portion of the opening and the inner wall of the resin particle, and a convex portion derived from the edge portion of the opening,
The direction along the first straight line a that forms the shortest distance from the center O of the rotation axis of the electrophotographic member to the inner wall of the resin particle in the recess is defined as the first direction, and is orthogonal to the first direction. And when the direction perpendicular to the longitudinal direction of the electrophotographic member is the second direction,
The convex portion has a highest point C farthest from the center O of the rotation axis in the first direction, and when the highest point is orthographically projected in the first direction, the projection point of the highest point The first convex region protruding so that P ′ is located in the concave portion, and the edge portion AA ′ of the opening in the second direction from the protruding tip E of the first convex region A second convex region composed of: and
The distance in the second direction from the tangent line a ″ in the first direction of the pseudo circle whose diameter is two points that define the maximum inner diameter of the concave portion to the tip E of the first convex region is represented by L _1. ,
A second straight line b extending in the second direction passes through the intersection point P between the inner wall surface of the resin particle in the recess and the first straight line a, and passes through the highest point C to the second straight line b. L ₂ , the distance to the third straight line b ″ extending in the direction of
A fourth straight line c connecting the highest point C ′ in the first direction of the tip E of the first convex region and the outermost end A of the second convex region and the second direction are When the angle formed is θ,
An electrophotographic member having at least one bowl-shaped resin particle satisfying the following formula (1):
Equation _{(1) D = L 1 /} L 2 -tanθ> 0.   One in each of the five regions obtained by dividing the longitudinal direction of the electrophotographic member into five equal parts, and six in the circumferential direction in each part (phase 0 °, 60 °, 120 °, 180 °, 240 °, and 300 ° ), The bowl-shaped resin particles satisfying the mathematical formula (1) when the surface layer of the region in the longitudinal direction of 0.5 mm and the circumferential direction of 0.5 mm is defined as “measurement range” The electrophotographic member according to claim 1, wherein one “measurement range” is 15 or more. The member for electrophotography according to claim 2, wherein an average value D _{(Ave) of the} D values calculated in the measurement range of the 30 locations is 0.02 or more.   The electrophotographic member according to claim 2, wherein the D values calculated in the 30 measurement ranges are all greater than zero.   The electrophotographic member according to claim 2, wherein all of the D values measured in the 30 measurement ranges are 0.01 or more. The member for electrophotography according to claim 1, wherein the value of L ₁ is 0.1 d or more and 0.9 d or less, where d is the inner diameter of the resin particles. The member for electrophotography according to claim 1, wherein the value of L ₂ is 0.1 d or more and 0.9 d or less, where d is the inner diameter of the resin particles.   The member for electrophotography according to claim 1, wherein the value of θ is 1 ° or more and 40 ° or less. It is a manufacturing method of the member for electrophotography according to any one of claims 1 to 8,
Forming a coating layer of a composition in which hollow resin particles are dispersed in a binder on the outer periphery of a conductive substrate to produce a conductive roller;
By polishing the surface of the coating layer, a part of the shell of the hollow resin particle is removed to form a bowl shape having an opening, and the edge of the opening of the bowl-shaped resin particle is formed on the surface of the coating layer. Forming a recess defined by the inner wall of the resin particle and a protrusion derived from the edge of the opening, and
A pressure-rotation heating process in which heating is performed while rotating a cylindrical pressure-contact member having a rotation axis parallel to the rotation axis of the conductive substrate against the conductive roller;
A method for producing an electrophotographic member, comprising:   The method for producing an electrophotographic member according to claim 9, wherein in the press-rotating and heating step, a pair of cylindrical press-contact members are pressed against both sides of the conductive roller.   The manufacturing method of the member for electrophotography of Claim 9 or 10 which performs the said press-contact rotation heating process at the temperature of 140 to 240 degreeC for 1 to 120 minutes. It is a manufacturing method of the member for electrophotography according to any one of claims 1 to 8,
Forming a coating layer of a composition in which hollow resin particles are dispersed in a binder on the outer periphery of a conductive substrate to produce a conductive roller;
By polishing the surface of the coating layer, a part of the shell of the hollow resin particle is removed to form a bowl shape having an opening, and the edge of the opening of the bowl-shaped resin particle is formed on the surface of the coating layer. Forming a recess defined by the inner wall of the resin particles and a protrusion derived from the edge of the opening,
A step of heat-treating the conductive roller in an oxygen-containing atmosphere, and a step of performing surface finish grinding of the coating layer by a tape polishing method;
A method for producing an electrophotographic member, comprising:   The method for producing an electrophotographic member according to claim 12, wherein the heat treatment is performed at a temperature of 180 ° C. or higher and 210 ° C. or lower for 10 to 200 minutes.   9. A process cartridge comprising the electrophotographic member according to claim 1 and an electrophotographic photosensitive member, wherein the process cartridge is detachable from a main body of the electrophotographic image forming apparatus. An electrophotographic image forming apparatus comprising the electrophotographic member according to claim 1 and an electrophotographic photosensitive member.

Images