JP6016838B2 - Electrophotographic roller member, process cartridge, and electrophotographic apparatus - Google Patents

Description

  The present invention relates to a roller member used for electrophotography, a process cartridge using the roller member, and an electrophotographic image forming apparatus (hereinafter referred to as “electrophotographic apparatus”).

  An electrophotographic apparatus adopting an electrophotographic system mainly includes an electrophotographic photosensitive member (hereinafter sometimes simply referred to as “photosensitive member”), a charging device, an exposure device, a developing device, a transfer device, and a fixing device. A roller member is preferably used for the charging device, the developing device, the transfer device, and the fixing device. In the charging device, the roller member is disposed in contact with or close to the surface of the photoconductor, and charges the surface of the photoconductor by applying a voltage (a voltage of only a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage).

  Patent Document 1 discloses a charging roller having a convex portion derived from conductive resin particles as a roller member (hereinafter referred to as a “charging roller”) that charges the photosensitive member by contacting the photosensitive member. ing.

  However, in the charging roller according to Patent Document 1, pressure is concentrated on the convex portions derived from the resin particles on the surface of the charging roller when contacting the photosensitive member, and the surface of the photosensitive member is not used in a long-term use. It was sometimes worn evenly.

  For such a problem, Patent Document 2 contains bowl-shaped resin particles having an opening in the conductive resin layer, and has a concave-convex shape derived from the openings and edge portions of the bowl-shaped resin particles on the surface. A roller member is disclosed. According to the roller member according to Patent Document 2, the contact pressure is relieved by elastic deformation when the edge portion of the bowl-shaped resin particles comes into contact with the photosensitive member, and the photosensitive member can be used even for a long period of use. It is described that non-uniform wear can be suppressed.

JP 2008-276026 A JP 2011-237470 A

  In the roller member according to Patent Document 2, the contact pressure on the photosensitive member is relieved by elastically deforming the edge portion of the opening of the bowl-shaped resin particles. For the above reasons, it is possible to suppress uneven wear on the surface of the photoreceptor even when used for a long period of time. On the other hand, there is a possibility that the roller member according to Japanese Patent Laid-Open No. 2004-260688 may be deteriorated in performance (hereinafter sometimes referred to as “driven rotation”) that rotates according to the rotation of the photosensitive member.

  In recent years, with the increase in the process speed of an electrophotographic apparatus, vibrations are likely to occur in the photoconductor when an electrophotographic image is formed. When an attempt is made to charge a photosensitive member by bringing a roller member having low driven rotation property into contact with the vibrating photosensitive member, the roller member cannot follow the rotation of the photosensitive member, and the roller member does not follow the surface of the photosensitive member. May occur (hereinafter also referred to as “stick slip”). 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 a roller member that can sufficiently suppress non-uniform 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 the present invention, there is provided a roller member for electrophotography having a conductive substrate and a conductive elastic layer as a surface layer,
The conductive elastic layer has a crown shape in which the outer diameter of the central portion in the longitudinal direction of the roller member is larger than the outer diameters of both end portions,
The conductive elastic layer includes a binder and bowl-shaped resin particles,
The surface of the roller member is
A recess derived from the opening of the bowl-shaped resin particles ;
It has a convex portion derived from the edge of the opening, and
The relationship between the elastic deformation restoration speed of the central portion and both ends of the roller member in the longitudinal direction of the conductive elastic layer is as follows:
On the surface of the conductive elastic layer , both end portions are larger than the central portion,
An electrophotographic roller member having a central portion larger than both end portions can be obtained at a position of a depth tμm from the surface of the conductive elastic layer (however, the depth tμm is equal to the depth tμm of the conductive elastic layer). The depth is from 30 μm to 100 μm from the surface) .

  In addition, according to the present invention, it is possible to obtain a process cartridge that has the above-described electrophotographic roller member and an electrophotographic photosensitive member and is configured to be detachable from the main body of the electrophotographic apparatus. Furthermore, according to the present invention, an electrophotographic apparatus having the above-described electrophotographic roller member and an electrophotographic photosensitive member can be obtained.

  The roller member according to the present invention can relieve the contact pressure from being concentrated on a part of the photosensitive member when the roller member is in contact with the photosensitive member. As a result, non-uniform wear of the photosensitive member due to the contact of the roller member can be suppressed even after long-term use. In addition, the roller member according to the present invention has improved follower rotation with respect to the photoreceptor. For this reason, stick-slip is less likely to occur, and it is possible to suppress the uneven charging of the photoreceptor and the occurrence of banding images due to the uneven charging.

It is explanatory drawing of the effect expression of the roller member which concerns on this invention. It is explanatory drawing of the effect expression of the roller member which concerns on this invention. It is sectional drawing of the roller member which concerns on this invention. It is a fragmentary sectional view of the surface vicinity of the roller member concerning the present invention. It is a fragmentary sectional view of the surface vicinity of the roller member concerning the present invention. It is explanatory drawing of the shape of the bowl-shaped resin particle of this invention. It is explanatory drawing of the electron beam irradiation apparatus used for manufacture of the roller member which concerns on this invention. It is explanatory drawing of the scanning electron beam irradiation source used for manufacture of the roller member which concerns on this invention. It is explanatory drawing of the area type | mold electron beam irradiation source used for manufacture of the roller member which concerns on this invention. 1 is a schematic cross-sectional view illustrating an example of an electrophotographic apparatus according to the present invention. It is a schematic sectional drawing showing an example of the process cartridge which concerns on this invention. It is an example of the load displacement curve in the roller member which concerns on this invention.

  The roller member for electrophotography according to the present invention (hereinafter sometimes simply referred to as “roller member”) has a conductive substrate and a conductive elastic layer. The conductive elastic layer has a crown shape whose outer diameter is larger at the center in the longitudinal direction of the roller member than at both ends.

  The conductive elastic layer contains a binder resin and bowl-shaped resin particles. The surface of the roller member has a concave portion derived from the opening of the bowl-shaped resin particles and a convex portion derived from the edge of the opening of the bowl-shaped resin particles (hereinafter sometimes simply referred to as “edge”). Have. In addition, the relationship of the restoring speed with respect to the elastic deformation of the central portion and both end portions of the roller member in the longitudinal direction is such that both end portions are larger than the central portion on the surface of the conductive elastic layer, and at a position of t μm from the surface of the conductive elastic layer. Is larger at the center than at both ends. In the present specification, the restoration speed with respect to the elastic deformation of the roller member may be simply referred to as “restoration speed”.

  The convex portion due to the edge is more easily elastically deformed at the time of contact with the photosensitive member than the convex portion formed by conductive resin particles as described in Patent Document 1. Therefore, the contact pressure is relieved. FIG. 1 (1a) is an enlarged schematic view of a close contact portion (hereinafter referred to as “nip portion”) between the roller member containing the bowl-shaped resin particles and the photoreceptor shown in FIG. At the nip portion, the edge is elastically deformed in the direction of arrow A by the contact pressure with the photosensitive member, so that the contact pressure with the photosensitive member is relieved. Due to the above-described effects, it is possible to suppress uneven wear of the photoreceptor even when used for a long time.

  On the other hand, when the contact pressure is relaxed, the contact area between the roller member and the photosensitive member is reduced, the driven rotational property is lowered, and charging unevenness may occur in the photosensitive member. Such uneven charging can be a cause of banding images. Such a problem becomes particularly noticeable when the process speed is increased and the vibration of the photosensitive member is increased.

  The roller member is placed in contact with the driven photosensitive member by applying a predetermined pressing force such as a spring to both ends of the shaft, and is driven to rotate following the photosensitive member. At this time, in the normal columnar shape, the pressurization of the central portion is weak due to the structure, and a gap may be generated between the photoconductor and the roller member. For the above reasons, a roller member having a crown shape in which the central portion of the roller member in the longitudinal direction has a larger outer diameter than both end portions is preferably used in order to make contact with the roller member in the longitudinal direction with uniform pressure. By adopting a crown shape in which the outer diameter of the central portion in the longitudinal direction of the roller member is larger than the outer diameters of both end portions, the contact width with the photoreceptor at the central portion (hereinafter referred to as “nip width”) is increased. For this reason, the followability of rotation with the photosensitive member at the center is improved. This driven rotation improves as the outer diameter difference between the center and both ends increases.

  However, if the difference between the outer diameters of the central portion and both end portions in the longitudinal direction of the roller member is large, the peripheral speed of the roller member is increased at both end portions as compared with the central portion when driven to rotate with the photoreceptor. As a result, “twist” is applied to the elastic layer of the roller member due to the difference in peripheral speed between the central portion and both end portions in the longitudinal direction. Such “twist” is absorbed by elastic deformation of the elastic layer while the amount is small, but “twist” is accumulated in the elastic layer, and when it exceeds a certain amount, The elastic layer attempts to return to its original shape to release the force, causing slip. That is, stick slip occurs at both end portions of the roller member. As a result, partial charging unevenness occurs on the photoreceptor, and a banding image is generated.

  In response to such a problem, according to the configuration of the roller member according to the present invention, both suppression of uneven wear of the photoconductor and suppression of banding images by improving the follower rotation of the roller member and the photoconductor are achieved. It becomes possible. This is considered to be due to the action described in 1) and 2) below.

  1) The restoring speed of the elastic deformation of the conductive elastic layer of the roller member according to the present invention increases from the center in the longitudinal direction toward both ends on the surface of the conductive elastic layer.

Resin particles of Bo ur shape, the nip portion as shown in FIG. 1 (1a), the edge portion 11 by the contact pressure between the photosensitive member 13, in a state of being elastically deformed in the direction of arrow A.

  FIG. 1 (1b) is a schematic sectional view of the nip portion. As shown in FIG. 1 (1b), the roller member 14 is brought into contact with the photosensitive member 13 by a predetermined pressing force (not shown) such as a spring. Then, as the photosensitive member rotates in the direction of arrow B, the roller member also rotates following the direction of arrow B. At this time, the contact pressure applied from the photosensitive member to the roller member becomes maximum at the center (position C) of the nip portion 15. For this reason, the elastic deformation of the edge also increases as shown in FIG. 1 (1c). As a result, the contact area between the edge 11 and the photosensitive member surface is the largest in the nip portion. Thereafter, as the resin particles move toward the end of the nip (position D), the contact pressure applied to the roller member and the bowl-shaped resin particles decreases, and when the resin particles exit the nip, Contact pressure is released. The state of the bowl-shaped resin particles at this time is shown in FIG. That is, the elastic deformation of the edge 11 is restored in the direction of the arrow E in FIG. 1 (1d), and the contact area between the edge and the photoconductor is reduced. The inventors of the present invention have found that the recovery speed of the elastic deformation of the edge 11 of the resin particle due to the reduction and release of the contact pressure applied to the bowl-shaped resin particle is determined by the conductive elastic layer 12 holding the resin particle. It was found that it depends on the recovery rate of elastic deformation of the surface region. That is, it has been found that the faster the recovery rate from the elastic deformation of the surface region of the conductive elastic layer 12, the faster the recovery rate from the elastic deformation of the edge portion of the bowl-shaped resin particles.

  Accordingly, the present inventors have attempted to increase the restoration speed of both end portions in the longitudinal direction of the roller member in the surface region of the conductive elastic layer 12 as compared with the restoration speed of the central portion in the longitudinal direction of the roller member. It was. Thereby, it is thought that the restoring speed immediately after passing the nip part of the edge of a bowl-shaped resin particle becomes large compared with the center part at both ends in the longitudinal direction. As a result, the contact state between the edge of the bowl-shaped resin particles and the photoconductor immediately after passing through the nip portion is as shown in FIG. 1 (1d) at both ends in the longitudinal direction of the roller member and as shown in FIG. ) As shown. By achieving such a state, the contact area between the convex portion derived from the edge and the photoconductor is reduced at both ends, so that the frictional force between the surface of the conductive elastic layer and the photoconductor is smaller than that in the central portion. descend. In this case, the “twist” force resulting from the difference in peripheral speed between the central portion and both ends is less likely to be accumulated at both ends in the longitudinal direction of the roller member of the conductive elastic layer of the roller member. As a result, it is considered that the occurrence of stick slip that causes charging unevenness can be suppressed.

  On the other hand, since the recovery speed of the elastic deformation of the edge of the bowl-shaped resin particles is slower at the center part in the longitudinal direction of the roller member than at both ends, the contact area between the convex part on the surface of the roller member and the photosensitive member Is reduced immediately after passing through the nip portion. Therefore, the driven rotation of the roller member with respect to the photoconductor is maintained well.

  2) The restoring speed of elastic deformation at a position of a predetermined depth tμm from the surface of the conductive elastic layer of the roller member according to the present invention increases as it goes from both ends in the longitudinal direction of the roller member toward the center.

  As described in 1) above, the elastic deformation restoration speed in the surface region of the conductive elastic layer mainly contributes to the contact state of the edge of the bowl-shaped resin particles on the surface of the roller member with the photoreceptor. On the other hand, it is considered that the restoring speed of elastic deformation at a position of a predetermined depth tμm from the surface contributes to the substantial nip width.

  As described above, when the roller member and the photosensitive member are driven to rotate, the contact pressure becomes maximum at the center (position C) of the nip portion 15 in FIG. Since the roller member is deformed by the contact pressure, the outer diameter of the roller member is minimized at the position C. After that, when rotating to the end of the nip portion (position D in FIG. 1 (1b)), the contact pressure decreases, so the outer diameter of the roller member is restored. 2 (2a), the outer diameter is restored in the direction of the arrow G in FIG. 2 (2b). When the restoration speed of the outer diameter of the roller member in this final end region is high, the state in which the surface of the roller member and the surface of the photoconductor are close to each other lasts longer than when the restoration speed is low. . This acts as if the nip width is increased.

  In the roller member according to the present invention, the elastic deformation restoration speed in the deep layer portion of the conductive elastic layer, that is, the portion having a depth of t μm from the surface, is compared with the both ends at the central portion in the longitudinal direction of the roller member. And it is getting bigger. As a result, the restoring speed of the outer diameter in the nip end end region of the conductive elastic layer is made faster than the center portion in the longitudinal direction of the roller member compared to both end portions. Therefore, the substantial nip width is larger at the center portion than at both end portions. As a result, the number of contact points where the edge contacts the photoconductor increases at the central portion in the longitudinal direction of the roller member and decreases at both ends. That is, the contact area between the convex portion derived from the edge and the photosensitive member is large at the central portion in the longitudinal direction of the roller member and is small at both end portions, so that the photosensitive member at the central portion in the longitudinal direction of the roller member having a crown shape The frictional force (grip property) is improved. As a result, the driven rotation of the roller member with respect to the photoreceptor can be improved.

  Here, the restoration rate of elastic deformation of the conductive elastic layer in the present invention will be described. The restoration rate of elastic deformation of the conductive elastic layer according to the present invention is determined by the following method. That is, a load is applied to the conductive elastic layer using a micro hardness tester based on an indentation test method based on ISO 14577 (metal material-indentation test and material parameters for hardness). A predetermined amount (D μm) of the indenter is submerged. Hereinafter, the predetermined amount may be referred to as “indentation depth”. Examples of the micro hardness tester include “Picodenter HM500” (trade name, manufactured by Fischer Instrument Co.).

  Thereafter, the load applied to the indenter is unloaded, and the restoring distance (μm) of the elastic layer is calculated based on the force that the indenter receives from the elastic layer during the unloading process. And the graph showing the relationship between the load (mN) applied to the indenter, the indentation depth (μm), and the restoring distance (μm) of the elastic layer at the time of unloading as shown in FIG. 12 is obtained.

Then, immediately after the start of unloading, specifically, when the recovery distance of the elastic layer is 0.1 μm after the start of unloading, the recovery speed v (μm / sec) is obtained by the following formula (1). .
Restoration speed v (μm / sec) = L (μm) /0.1 (sec) (1)
The reason for using the restoration distance L 0.1 seconds after the start of unloading for the restoration speed is as follows. That is, in the final end region of the nip portion, the restoration speed immediately after the surface area of the conductive elastic layer is released from the contact pressure regulates the restoration speed from the elastic deformation of the edge portion of the bowl-shaped resin particles. It is thought that. Similarly, in the final end region of the nip portion, it is considered that the restoration speed immediately after the deep layer region of the conductive elastic layer is released from the contact pressure regulates the substantial nip width. Therefore, in the present invention, the restoring speed of the conductive elastic layer is calculated by using the restoring distance 0.1 seconds after the start of unloading of the conductive elastic layer, so that the conductive elastic layer of the roller member is applied. It was assumed that the speed of restoration was just after the contact pressure was released.

  The surface region according to the present invention is a region from the surface of the conductive elastic layer opposite to the side facing the conductive substrate (the surface of the conductive elastic layer) to a depth of 10 μm. This is considered that the restoration from the elastic deformation of the edge described in 1) is substantially governed by the restoration speed of the conductive elastic layer in the region from the surface of the conductive elastic layer to a depth of 10 μm. By being done. For this reason, the indentation depth D μm of the microhardness tester is preferably 10 μm.

  Furthermore, in the present invention, a standard of the value of the depth t μm from the surface (surface of the conductive elastic layer) opposite to the side facing the substrate of the conductive elastic layer, which defines the deep layer region of the conductive elastic layer. Is preferably 30 μm or more and 100 μm or less. By setting the value of tμm within this range, the effect of substantially increasing the nip width at the central portion in the longitudinal direction of the roller member can be more reliably enjoyed. That is, within this depth range, it is preferable that the restoring speed of the conductive elastic layer is larger at the center than at both ends in the longitudinal direction of the roller member. Therefore, the indenter indentation depth D μm in the measurement of the restoration rate of the deep region of the conductive elastic layer according to the present invention is preferably 20 to 100 μm.

<Roller member>
Below, the roller member which concerns on this invention is demonstrated in detail. FIG. 3 is a schematic view of an example of a cross section of a roller member according to the present invention. The roller member in FIG. 3 (3 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. 3 (3b). The conductive elastic layer contains a binder, conductive fine particles, and bowl-shaped resin particles.

  The conductive substrate and the conductive elastic layer, or the layers sequentially stacked on the conductive substrate (for example, the conductive elastic layer 21 and the conductive elastic layer 22 shown in FIG. 3 (3b)) are bonded with an adhesive. May be. In this case, the adhesive is preferably conductive. A well-known adhesive can be used for the adhesive to make it conductive.

  Examples of the binder of the adhesive include thermosetting resins and thermoplastic resins, and known resins such as urethane, acrylic, polyester, polyether, and epoxy resins can be used.

  The conductive agent for imparting conductivity to the adhesive can be appropriately selected from conductive fine particles that can be used to make the elastic layer, which will be described later, and can be used alone or in combination of two or more.

The roller member according to the present invention is a crown whose center portion in the longitudinal direction is the thickest and becomes thinner toward both ends in the longitudinal direction from the viewpoint of improving the followability of rotation with the photosensitive member at the center portion in the longitudinal direction. Shape is preferred. A preferable range of the “crown amount” is 30 to 200 μm. However, the crown amount is the difference between the outer diameter D2 of the central portion in the longitudinal direction of the roller member and the average value of the outer diameters D1 and D3 at positions 90 mm away from the central portion in both end directions. This is the value calculated in 2).
Crown amount = D2- (D1 + D3) / 2 (2)

[Conductive substrate]
The conductive substrate used for the roller member of the present invention has conductivity and has a function of supporting a conductive elastic layer and the like provided thereon. Examples of the material include metals such as iron, copper, stainless steel, aluminum, and nickel, and alloys thereof.

[Conductive elastic layer]
FIG. 4 is a partial cross-sectional view in the vicinity of the surface of the conductive elastic layer of the roller member. Some of the bowl-shaped resin particles 41 contained in the conductive elastic layer are exposed on the surface of the roller member. The surface of the roller member has a recess 52 derived from the opening 51 of the bowl-shaped resin particles exposed on the surface, and a protrusion derived from the edge 53 of the opening of the bowl-shaped resin particles exposed on the surface. And have.

  5, the distance 54 between the apex of the convex portion 53 derived from the edge of the opening of the bowl-shaped resin particles and the bottom of the concave portion 52 defined by the shell of the bowl-shaped resin particles is 5 μm or more and 100 μm or less. In particular, the thickness is preferably 8 μm or more and 80 μm or less. Hereinafter, the distance may be referred to as “height difference”. By setting the distance 54 within the above range, the contact pressure can be more reliably relaxed. The ratio of the height difference 54 and the maximum diameter 55 of the bowl-shaped resin particles, that is, the value of [maximum diameter] / [height difference] of the resin particles is 0.8 or more and 3.0 or less. It is preferable. By setting it within this range, the contact pressure described above can be more reliably reduced.

  It is preferable that the surface state of the roller member, that is, the surface state of the conductive elastic layer is controlled as follows by forming the uneven shape. The ten-point average roughness (Rzjis) of the surface is preferably 5 μm or more and 65 μm or less, and particularly preferably 10 μm or more and 50 μm or less. The surface irregularity average interval (Sm) is preferably 30 μm or more and 200 μm or less, and particularly preferably 40 μm or more and 150 μm or less. By setting it within the above range, the contact pressure can be more reliably reduced. The method for measuring the surface ten-point average roughness (Rzjis) and the surface irregularity average interval (Sm) will be described in detail later.

  An example of bowl-shaped resin particles used in the present invention is shown in FIGS. 6 (6a) to 6 (6e). In the present invention, “bowl-shaped” particles refer to particles having an opening 61 and a shape having a rounded recess 62 defined by a shell. The opening may have a flat edge as shown in FIGS. 6 (6a) and 6 (6b), and the edges may be uneven as shown in FIGS. 6 (6c) to 6 (6e). You may have.

  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. The ratio of the maximum diameter 55 of the bowl-shaped resin particles to the minimum diameter 63 of the opening, that is, the value of [maximum diameter] / [minimum diameter of the opening] of the bowl-shaped resin particles is 1.1 or more. It is more preferable that it is 4.0 or less. By setting it within this range, the contact pressure described above can be more reliably reduced.

  The thickness of the shell of the bowl-shaped resin particles is preferably 0.1 μm to 3 μm, particularly preferably 0.2 μm to 2 μm. By setting the thickness of the shell within this range, the edge can be elastically denatured more flexibly, and as a result, the contact pressure can be relaxed more reliably. The maximum thickness of the shell is preferably 3 times or less of the minimum thickness, and more preferably 2 times or less.

[binder]
As the binder contained in the conductive elastic layer of the present invention, a known rubber or resin can be used. 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), acrylic rubber, epichlorohydrin rubber and fluorine rubber. 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.

[Conductive fine particles]
The conductive elastic layer contains known conductive fine particles in order to exhibit conductivity. Examples of the conductive fine particles include metal oxides, metal fine particles, and carbon black. Moreover, these electroconductive fine particles can be used individually 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 (hereinafter referred to as “preliminary coating layer”) in which conductive fine particles and hollow resin particles are dispersed in a binder is prepared on a conductive substrate. Then, by polishing the surface, a part of the hollow resin particles are removed to form a bowl shape, and a concave portion due to the opening of the bowl-shaped resin particle and a convex portion due to the edge of the opening of the bowl-shaped resin particle are formed. To do. Hereinafter, the shape including these concave portions and convex portions is referred to as “uneven shape by opening of bowl-shaped resin particles”. In this way, a conductive resin layer is formed, and then the surface is irradiated with an electron beam to control the elastic deformation recovery rate of the conductive elastic layer.

[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 particles containing a gas inside are dispersed together with a binder and conductive fine particles is formed on a conductive substrate. Examples of the method include drying, curing, and crosslinking. Examples of the material used for the hollow resin particles include the above-described known resins.

  As another method, a method of using a so-called thermally expandable microcapsule in which an encapsulated substance is contained inside the particles and the encapsulated substance expands 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 together with a binder and conductive fine particles 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 a thermally expandable microcapsule, 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, urethane resin, amide resin, methacrylonitrile resin, acrylic acid resin, acrylic ester resin, methacrylic ester resin. Among these, it is preferable to use a thermoplastic resin composed of at least one selected from acrylonitrile resin, vinylidene chloride resin, and methacrylonitrile resin having low gas permeability and high resilience. These thermoplastic resins can be used alone or in combination of two or more. 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 thermoplastic 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 point liquids such as propane, propylene, butene, normal butane, isobutane, normal pentane, and isopentane; high boiling point liquids such as normal hexane, isohexane, normal heptane, normal octane, isooctane, normal decane, and isodecane.

  The thermally expandable microcapsules can be produced by a known production method such as a suspension polymerization method, an interfacial polymerization method, an interfacial sedimentation 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); styrene monomer -Acrylamide, substituted acrylamide, methacrylamide, substituted methacrylamide, butadiene, epsilon caprolactam, polyether, isocyanate. These polymerizable monomers can be used alone or in combination of two or more.

  As a polymerization initiator, an initiator soluble in a polymerizable monomer is preferable, and a known peroxide initiator and 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. When using 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, polyepoxide fine particles, etc.), silica (colloidal silica, etc.), 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. Alternatively, the polymerization raw material may be suspended in a disperser or the like and then transferred to a pressure resistant container for suspension polymerization, or may be suspended in the 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. When solid-liquid separation or washing is performed, drying or pulverization may be performed thereafter at a temperature equal to or lower than the softening temperature of the resin constituting the thermally expanded microcapsules. 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.

[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. Further, the preliminary coating layer can be formed by placing the conductive resin composition in a mold in which a conductive substrate is disposed and curing the composition. 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.

  Thereafter, after drying, curing, cross-linking and the like, the surface of the preliminary coating layer is polished to remove a part of the hollow resin particles 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 particles, In many cases, convex portions derived from hollow resin particles are formed. In this case, a part of the convex portions of the hollow resin particles can be deleted to form a bowl shape, thereby forming an uneven shape by opening the bowl-shaped resin particles. In this case, it is more preferable to use tape polishing 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, silicon carbide, 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.), mirror film, wrapping film (trade name, Sankyo Rikagaku Co., Ltd.), Mipox (trade name, manufactured by 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 when the thickness of the preliminary coating layer is within 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, On the surface, there may be a case where the convex portions derived from the hollow resin particles are not formed. In such a case, it is possible to form a concavo-convex shape by opening the bowl-shaped resin particles by utilizing the difference in abrasiveness between the hollow-shaped resin particles and 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 preliminary coating layer in the above state is polished, the hollow resin particles can be formed into a bowl shape in which only a part of the hollow resin particles are removed without being polished in the same state as the preliminary coating layer. 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 using the difference in polishing properties between the hollow resin particles and the preliminary coating layer, rubber can be used as the binder used for the preliminary coating layer. preferable. 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. The resin used for the hollow resin particles is preferably a resin having a polar group from the viewpoint of low gas permeability and high resilience, and more preferably a resin having a unit represented by the following formula (1). . In particular, a resin having a unit represented by the formula (1) and a unit represented by the formula (5) is more preferable from the viewpoint that the abrasiveness can be easily controlled.

  In formula (1), A is at least one selected from the following formulas (2), (3) and (4). R1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

  In formula (5), R2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R3 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R2 and R3 may have the same structure or different structures.

[Polishing method]
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 conductive roller can be simultaneously polished and the polishing time can be shortened. In addition, it is preferable that the spark-out process (polishing process at an intrusion rate of 0 mm / min) that has been conventionally performed from the viewpoint of making the polished surface uniform be as short as possible or not be performed. 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 process, a break-in process may be provided on the polished surface, and it is preferable that the intrusion speed is 0.1 to 0.2 mm / min 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 unevenness | corrugation formation by the opening of a bowl-shaped resin particle can be more easily formed in the surface of a preliminary coating layer, and the electroconductive roller which has an electroconductive elastic layer can be produced. .

[Electron beam irradiation]
The surface of the conductive roller thus obtained is irradiated with an electron beam and cured by the method described in the following (1), (2) or (3). As a result, the roller member of the present invention can be obtained in which the elastic deformation restoring speeds at the center and both ends in the longitudinal direction have a specific relationship.

(1) A method of irradiating and scanning an electron beam in a fan shape toward both ends centering on the central portion in the longitudinal direction of the conductive roller,
(2) A method of irradiating an electron beam while increasing the acceleration voltage at the center in the longitudinal direction of the conductive roller and changing the acceleration voltage to be small at both ends,
(3) A method of irradiating electron beams with different acceleration voltages while masking a part of the conductive roller in the longitudinal direction.

  The elastic deformation recovery speed can be measured by a method of calculating the elastic deformation recovery speed from the load displacement curve obtained from the process of unloading after pushing the Vickers indenter to a predetermined depth by a picodenter described later. it can. The predetermined depth tμm is preferably 30 μm or more and 100 μm or less.

[Electron beam irradiation equipment]
Here, a schematic view of a general electron beam irradiation apparatus is shown in FIG. The electron beam irradiation device used in the present invention is a device that can irradiate the surface of the conductive roller with an electron beam while rotating the conductive roller. As shown in FIG. An irradiation chamber 72 and an irradiation port 73 are provided.

The electron beam generator 71 includes an acceleration tube 75 that accelerates an electron beam generated in an electron source (electron gun) 74 in a vacuum space (acceleration space). The inside of the electron beam generator is maintained at a vacuum of 10 ⁻³ to 10 ⁻⁶ Pa by a vacuum pump (not shown) or the like in order to prevent electrons from colliding with gas molecules and losing energy.

  When the filament 76 is heated by current from a power source (not shown), the filament 76 emits thermoelectrons, and these thermoelectrons are effectively taken out as an electron beam. The electron beam is accelerated in the acceleration space in the accelerating tube 75 by the acceleration voltage, then penetrates the irradiation port foil 77 and is irradiated to the conductive roller 78 conveyed in the irradiation chamber 72 below the irradiation port 73. The

  When the conductive roller 78 is irradiated with an electron beam as in this embodiment, the inside of the irradiation chamber 72 is a nitrogen atmosphere. Further, the conductive roller 78 is rotated by a roller rotating member 79 and moved from the left side to the right side in FIG. The surroundings of the electron beam generator 71 and the irradiation chamber 72 are shielded by lead (not shown) or stainless steel so that X-rays generated secondarily at the time of electron beam irradiation do not leak to the outside. .

  The irradiation port foil 77 is made of a metal foil, and separates the vacuum atmosphere in the electron beam generator and the nitrogen atmosphere in the irradiation chamber, and takes out the electron beam into the irradiation chamber through the irradiation port foil 77. Therefore, the irradiation port foil 77 provided at the boundary between the electron beam generating unit 71 and the irradiation chamber 72 has no pinhole, has a mechanical strength that can sufficiently maintain the vacuum atmosphere in the electron beam generating unit, and transmits the electron beam. It is desirable to be easy. Therefore, it is desirable that the irradiation port foil 77 has a small specific gravity and a thin metal, and an aluminum foil, a titanium foil, a beryllium foil, or a carbon film is usually used. For example, a thin film foil having a thickness of about 5 μm to 30 μm is used. The curing condition by the electron beam is determined by the acceleration voltage and dose of the electron beam. The acceleration voltage affects the curing treatment depth, and the acceleration voltage condition in the present invention is preferably in the range of 40 to 300 kV which is a low energy region. A treatment region having a sufficient thickness for obtaining the effects of the present invention can be obtained at 40 kV or more. A more preferable acceleration voltage is in the range of 70 to 150 kV.

The dose of electron beam in electron beam irradiation is defined by the following calculation formula (3).
D = (K · I) / V (3)
Here, D is a dose (kGy), K is an apparatus constant, I is an electron current (mA), and V is a processing speed (m / min). The device constant K is a constant that represents the efficiency of each device and is an index that represents the performance of the device. The apparatus constant K can be obtained by measuring the dose while changing the electron current and the processing speed under the condition of a constant acceleration voltage. Electron beam dose measurement is performed by attaching a dose measurement film to the surface of a conductive roller, irradiating the surface of the conductive roller with an electron beam, and measuring the dose of the dose measurement film with a film dosimeter. . The dosimetry film used is FWT-60, and the film dosimeter is FWT-92 type (both manufactured by FarWest Technology).

  The electron beam dose in the present invention is preferably in the range of 30 to 3000 kGy. If it is 30 kGy or more, a sufficient restoration speed for elastic deformation can be obtained to obtain the effects of the present invention. By setting it to 3000 kGy or less, the conductive elastic layer does not have an unnecessarily high hardness, and the driven rotation with the photoreceptor is improved.

[Scanning electron beam irradiation source]
Next, the scanning electron beam irradiation source that can be used in the present invention will be described in detail. As shown in FIG. 8, the scanning electron irradiation source includes an electron gun 81, an electron beam generator container 82, and an irradiation port 83. This scanning electron beam irradiation source is a device that scans and radiates an electron beam from the irradiation port 83 in a fan shape by deflecting the electron beam emitted from the electron gun 81 at a high speed in a predetermined direction.

The electron gun 81 has a filament 84 that emits an electron beam. An electromagnetic coil 86 is disposed around the electron beam passage hole 85 along the emission axis of the electron beam emitted from the filament 84. The arrangement center of the electromagnetic coil 86 coincides with the central axis of the electron beam passage hole 85. With this electromagnetic coil, the electron beam passing through the electron beam passage hole 85 is focused toward the irradiation port 83. In addition, a vacuum pump (not shown) is connected to the side of the container 82 of the electron beam generating unit. The inside of the electron beam generating unit prevents electrons from colliding with gas molecules and losing energy. The vacuum is maintained at ⁻³ to 10 ⁻⁶ Pa.

  The container 82 of the electron beam generator is provided with a deflection coil 87, and the electron beam that has passed through the electron beam passage hole 85 is deflected in a fan shape by the deflection coil 87. The deflection coil 87 operates based on a current value and frequency supplied from an AC power source (not shown), and as a result, the electron beam is deflected at a high speed from side to side as shown in FIG. The frequency of the deflected electron beam is preferably set to 100 Hz or more so that electron unevenness does not occur.

  The electron beam deflected in a fan shape by the deflection coil 87 passes through an irradiation window 88 provided in the irradiation port 83 and is irradiated onto the surface of the conductive roller 89 outside the scanning electron beam irradiation source. The electron beam irradiation window 88 is formed of, for example, a titanium foil or beryllium foil having a thickness of about several μm to 10 μm.

  By performing surface treatment of the conductive elastic layer using this scanning electron beam irradiation source, the recovery speed against elastic deformation at the surface and at a depth of t μm from the surface at the center and both ends in the longitudinal direction. It is possible to obtain a conductive elastic layer according to the present invention in which the above is reversed.

  Specifically, as shown in FIG. 8, the electron beam is radiated in a fan shape symmetrically toward the both ends of the conductive elastic layer of the conductive roller with the central portion in the longitudinal direction of the conductive roller as the center. . As a result, the electron beam irradiated to the central portion and both ends in the longitudinal direction of the conductive elastic layer has different incident angles to the conductive elastic layer even if the acceleration voltage is the same. The degree of penetration of the elastic elastic layer in the depth direction varies. As a result, the electron beam penetrates deeper in the center portion in the longitudinal direction of the conductive elastic layer than in the both end portions.

As a result, the roller member according to the present invention having the following characteristics 1) to 3) can be obtained.
1) The restoring speed of the conductive elastic layer with respect to elastic deformation is small in the depth direction from the surface of the conductive elastic layer.
2) Regarding the restoring speed of the central portion and both end portions in the longitudinal direction of the conductive elastic layer, the values of both end portions are larger than the values of the central portion on the surface of the conductive elastic layer.
3) With respect to the restoration speed, the value at the center is larger than the values at both ends at a position t μm deep from the surface of the conductive elastic layer.

  Further, by using this scanning electron beam irradiation window, the electron beam is formed in a fan shape while controlling the acceleration voltage so that the acceleration voltage is high at the central portion in the longitudinal direction of the conductive roller and low at both ends. The roller member according to the present invention can also be obtained by irradiation.

[Area-type electron beam irradiation source]
Next, the area type electron beam irradiation source that can be used in the present invention will be described in detail. As shown in FIG. 9, the area type electron beam irradiation source includes an electron gun 91, an electron beam generation unit container 92, and an irradiation port 93. This area-type electron beam irradiation source is an apparatus that accelerates an electron beam emitted from an electron gun 91 by an acceleration tube 94 in a vacuum space (acceleration space) and irradiates a predetermined area from an irradiation port 93 linearly. .

The electron gun 91 has a plurality of filaments 95 that emit an electron beam. The emitted electron beam is accelerated by the acceleration tube 94 in the vacuum space (acceleration space) and emitted toward the irradiation port 93 by the plurality of filaments 95. Further, a vacuum pump (not shown) is connected to the side of the container 92 of the electron beam generating unit, and the inside of the electron beam generating unit and the accelerating tube 94 detect that the electrons collide with gas molecules and lose energy. In order to prevent this, a vacuum of 10 ⁻³ to 10 ⁻⁶ Pa is maintained.

  The linear electron beams emitted from the plurality of filaments 95 pass through an irradiation window 96 provided at the irradiation port 93 and are irradiated onto the surface of the roller member 97 outside the area type electron beam irradiation source. The electron beam irradiation window 96 is formed of, for example, a titanium foil or beryllium foil having a thickness of about several μm to 10 μm.

  By using this area type electron beam irradiation source, it is possible to control the restoring rate of elastic deformation in the depth direction of the conductive elastic layer. Specifically, as shown in FIG. 9, masking 98 is performed on the surface of the conductive roller except for a predetermined width (for example, 10 mm each) at both ends in the longitudinal direction of the conductive roller, and electrons having a low acceleration voltage are obtained. Irradiate the line. Thereafter, the non-masking portion is sequentially moved by a predetermined width in the direction of the center portion to perform masking 98 on the surface of the conductive roller, and each time the non-masking portion is moved, the acceleration voltage is gradually increased and irradiation is repeated. Can be achieved.

  By this masking operation, an electron beam having a low acceleration voltage can be irradiated at both ends of the conductive roller, and an electron beam having a high acceleration voltage can be irradiated at the central portion of the conductive roller. As a result, it is possible to change the reach distance of the electron beam toward the depth direction of the conductive elastic layer at the center and both ends. Further, the masking 98 on the surface of the conductive roller prevents transmission of electron beams, and for example, a stainless steel sheet having a thickness of about 50 μm or more is used.

  In this way, it is possible to obtain the roller member according to the present invention having the above characteristics 1) to 3).

<Electrophotographic device>
An electrophotographic apparatus according to the present invention is an electrophotographic apparatus comprising the electrophotographic roller member and an electrophotographic photosensitive member.

  FIG. 10 shows a schematic configuration of an example of an electrophotographic apparatus. The electrophotographic apparatus includes an electrophotographic photosensitive member, a charging device for the electrophotographic photosensitive member, a latent image forming device that performs exposure, a developing device, a transfer device, a cleaning device for a transfer residual toner on the electrophotographic photosensitive member, and a fixing device. It is configured.

  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 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 toner electrostatically processed to the same polarity as the charged polarity of the electrophotographic photosensitive member is reversely developed to develop the electrostatic latent image to form a toner image. 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 includes a blade-type cleaning member 106 and a collection container 108, and after transfer, mechanically scrapes and collects transfer residual toner remaining on the electrophotographic photosensitive member 102. 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 fixing roller 105 is composed of a heated roll, fixes the transferred toner image on the transfer material, and discharges the toner image outside the apparatus.

  The roller member for electrophotography of the present invention can be used as the developing roller, the charging roller, the transfer roller, or the fixing roller.

<Process cartridge>
A process cartridge according to the present invention is a process cartridge having the above-described electrophotographic roller member and an electrophotographic photosensitive member, and configured to be detachable from a main body of the electrophotographic apparatus.

  FIG. 11 shows a schematic configuration of an example of the process cartridge. The 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 electrophotographic apparatus. The roller member for electrophotography of the present invention can be used as the above developing roller or charging roller.

  Hereinafter, the present invention will be described in more detail with reference to specific production examples and examples. The breakdown of production examples is as follows. Production Examples 1 to 13 are production examples of resin particles. Production Examples 14 to 18 are production examples of conductive rubber compositions 1 to 5 containing resin particles. The average particle size of the resin particles means the volume average particle size, and the measurement method will be described in detail below.

[Measurement of volume average particle diameter of resin particles]
The volume average particle size of the powder was measured using 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, and 10 mg to 25 mg of sodium sulfite was added to the measurement system as an antifoaming agent to execute the background function. Next, 3 to 4 drops of a surfactant was added to 50 ml of pure water, and further 1 mg to 25 mg of a measurement sample was 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. Measurement was performed by gradually adding a test sample solution into the measurement system of the measurement apparatus and adjusting the test sample concentration in the measurement system so that the PIDS on the screen of the apparatus was 45% or more and 55% or less. The volume average particle diameter was calculated from the obtained volume distribution.

<Production Example 1> [Preparation of Resin Particle 1]
An aqueous mixed solution of 4000 parts by mass of ion-exchanged water, 9 parts by mass of colloidal silica and 0.15 parts by mass of polyvinylpyrrolidone as a dispersion stabilizer was prepared. Subsequently, 50 parts by mass of acrylonitrile as a polymerizable monomer, 45 parts by mass of methacrylonitrile and 5 parts by mass of methyl methacrylate, 12.5 parts by mass of normal hexane as an inclusion substance, and 0.25 parts of dicumyl peroxide 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 200 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. The obtained resin particles were pulverized and classified by a sonic classifier to obtain resin particles 1 having an average particle diameter of 12 μm.

<Production Examples 2 to 13> [Preparation of resin particles 2 to 13]
Resin particles were produced in the same manner as in Production Example 1 except that at least one of the number of added colloidal silica, the type of polymerizable monomer, and the number of added parts was changed to the conditions shown in Table 1. Moreover, the resin particles 2-13 of the average particle diameter shown in Table 1 were obtained by classifying similarly, respectively.

<Production Example 14> [Preparation of conductive rubber composition 1]
Sealed mixer adjusted to 50 ° C. by adding other 4 components shown in the column of component (1) in Table 2 below to 100 parts by mass of acrylonitrile butadiene rubber (NBR) (trade name: N230SV, manufactured by JSR) And kneading for 15 minutes. Subsequently, 3 components shown in the column of the component (2) of Table 2 were added, and it knead | mixed for 10 minutes with the double roll machine cooled to the temperature of 25 degreeC, and the conductive rubber composition 1 was obtained.

<Production Example 15> [Preparation of Conductive Rubber Composition 2]
Sealed type adjusted to 80 ° C. by adding other 6 components shown in the column of component (1) in Table 3 below to 100 parts by mass of styrene butadiene rubber (SBR) (trade name: Toughden 2003, manufactured by Asahi Kasei Co., Ltd.) It knead | mixed for 15 minutes with the mixer. Subsequently, 4 components shown in the column of the component (2) of Table 3 were added, and it knead | mixed for 10 minutes with the double roll machine cooled to the temperature of 25 degreeC, and the conductive rubber composition 2 was obtained.

<Production Example 16> [Preparation of conductive rubber composition 3]
Conductive rubber in the same manner as in Production Example 14 except that the acrylonitrile butadiene rubber in Production Example 14 was changed to butadiene rubber (BR) (trade name: JSR BR01, manufactured by JSR Corporation) and carbon black was changed to 30 parts by mass. Composition 3 was obtained.

<Production Example 17> [Preparation of Conductive Rubber Composition 4]
With respect to 100 parts by mass of ethylene propylene diene copolymer (EPDM) (trade name: EP33, manufactured by JSR), other 4 components shown in the column of component (1) in Table 4 below were added to adjust to 80 ° C. It knead | mixed for 15 minutes with the airtight mixer. Subsequently, 4 components shown in the column of the component (2) of Table 4 were added, and it knead | mixed for 10 minutes with the double roll machine cooled to the temperature of 25 degreeC, and the conductive rubber composition 4 was obtained.

<Production Example 18> [Preparation of Conductive Rubber Composition 5]
Epichlorohydrin rubber (EO-EP-AGE ternary co-compound, EO / EP / AGE = 73 mol% / 23 mol% / 4 mol%) with respect to 100 parts by mass, other 7 components shown in the column of component (1) in Table 5 below And kneaded for 15 minutes in a closed mixer adjusted to 80 ° C. Subsequently, 4 components shown in the column of the component (2) of Table 5 were added, and it knead | mixed for 10 minutes with the double roll machine cooled to the temperature of 25 degreeC, and the conductive rubber composition 5 was obtained.

<Example 1>
As shown in FIG. 3 (3a), Example 1 relates to a roller member having a conductive elastic layer on a conductive substrate.

[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 a conductive substrate.

[2. Formation of conductive elastic layer]
Using an extrusion molding apparatus equipped with a crosshead, the conductive rubber composition 1 produced in Production Example 14 was coated in a cylindrical shape on the peripheral surface with the conductive base as the central axis. The thickness of the coated conductive rubber composition was adjusted to 1.75 mm.

  The roller after extrusion was heated in a hot air oven at 160 ° C. for 1 hour to vulcanize the conductive rubber composition, and then the end of the rubber layer was removed to a length of 224.2 mm. Further, secondary vulcanization was performed at 160 ° C. for 1 hour to produce a roller having a preliminary coating layer having a layer thickness of 3.5 mm. 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. The thickness of the conductive elastic layer was adjusted to 1.5 mm. The crown amount of this roller was 120 μm.

[3. Electron beam irradiation to the conductive elastic layer)
The roller member 1 was obtained by irradiating the conductive roller with an electron beam under the following conditions. The electron beam irradiation was performed with an electron beam irradiation apparatus (trade name: low energy electron beam irradiation source EB-ENGINE, manufactured by Hamamatsu Photonics). The oxygen concentration of the atmosphere is reduced to 500 ppm or less by nitrogen gas purge, and the roller member is rotated at 300 rpm with the conductive substrate of the roller member as a rotating shaft, and is conveyed at a processing speed of 10 mm / s in the direction perpendicular to the paper surface of FIG. Line irradiation was performed. As the electron beam irradiation conditions, the electron current was adjusted so that the acceleration voltage was 70 kV and the dose was 1000 kGy.

[4. Evaluation of roller members)
The roller member 1 thus obtained was evaluated in the following [4-1] to [4-6]. The evaluation results are shown in Table 11 and Table 13.

[4-1. Measurement of Ten-point Average Roughness Rzjis and Convex Average Distance Sm of Roller Member Surface
It measures according to the specification of JISB0601-1994 surface roughness, and measures using a surface roughness measuring device (brand name: SE-3500, Kosaka Laboratory Co., Ltd. make). Rzjis and Sm are measured at six locations on the surface of a randomly selected roller member, and are average values. The cut-off value is 0.8 mm, and the evaluation length is 8 mm.

[4-2. Measuring the shape of bowl-shaped resin particles]
An arbitrary point of the conductive elastic layer is cut out with a focused ion beam (trade name: FB-2000C, manufactured by Hitachi, Ltd.) every 20 nm over 500 μm, and a cross-sectional image thereof is taken. Then, by combining images obtained by photographing the same bowl-shaped resin particles, a three-dimensional image of the bowl-shaped resin particles is calculated. From the stereoscopic image, and it calculates the "maximum diameter" 55 as shown in FIG. 6, the "minimum diameter of the opening" 63 shown in FIG. Further, from the three-dimensional image, “difference between outer diameter and inner diameter” (that is, “shell thickness”) is calculated at any five points of the bowl-shaped resin particles. Such an operation is performed for 10 resin particles in the field of view. And the same measurement is performed about the longitudinal direction 10 places of a roller member, and the average value of the value calculated about the total 100 resin particles obtained is calculated.

[4-3. Measurement of roller member surface shape]
The surface of the roller member is observed with a laser microscope (trade name: LXM5 PASCAL: manufactured by Carl Zeiss) in a visual field of 0.5 mm in length and 0.5 mm in width. Two-dimensional image data is obtained by scanning the laser in the XY plane in the field of view, and further, the focal point is moved in the Z direction, and the above scanning is repeated to obtain three-dimensional image data. As a result, first, it is confirmed that the bowl-shaped resin particles have a concave portion derived from the opening and a convex portion derived from the edge of the opening. Further, a “height difference” 54 between the apex 53 of the convex portion and the bottom portion 52 of the concave portion is calculated. Such an operation is performed for two bowl-shaped resin particles in the field of view. And the same measurement is performed about 50 longitudinal directions of a roller member, and the average value of a total of 100 resin particles obtained is calculated.

[4-4. Measurement of restoring speed for elastic deformation of roller member]
Based on ISO14577, it was measured using Picodenter HM500 (trade name, manufactured by Fisher Instrument Co., Ltd.). As the indenter, a pyramid diamond indenter having a square base and an indenter (Vickers pyramid) having a facing angle of 136 ° sandwiching the apex was used. The measurement was performed at the central portion and both end portions in the longitudinal direction (positions of 90 mm from the central portion to both end directions).

  The measurement includes a step of pushing the indenter to a predetermined depth at a predetermined speed (hereinafter referred to as “push-in step”), and a step of unloading the load from a predetermined indentation depth position at a predetermined speed (hereinafter referred to as “unloading”). Process). From the thus obtained load displacement curve as shown in FIG. 12, the restoring speed with respect to elastic deformation was calculated. A method for calculating the restoration speed will be described later.

  The measurement was performed under the following two conditions, and when there was an area where no bowl-shaped resin particles were present, a non-resin particle part was selected. FIG. 12 is an example of a load displacement curve when t = 100 μm in <Condition 2>.

<Condition 1> Measurement of restoration speed on the surface (indentation process)
・ Maximum indentation depth = 10μm
Indentation time = 20 seconds Note that the maximum load _Fmax needs to be sufficiently large so that the indentation can be performed up to the maximum indentation depth. In this measurement, the maximum load _Fmax was set to 10 mN.
(Unloading process)
・ Minimum load = 0.005mN
-Unloading time = 1 second. Unloading was performed until the minimum load of the indenter was reached.
The restoring speed v with respect to elastic deformation was calculated by the following equation from the displacement of the indenter (= restoration distance L of the conductive elastic layer) at 0.1 seconds from the start of unloading in the unloading process.
Restoration speed v = L / 0.1
<Condition 2> Measurement of restoration speed at a predetermined depth tμm (indentation process)
・ Maximum indentation depth (predetermined depth t) = 20, 30, 50, 100 μm
Indentation time = 20 seconds The maximum load needs to be sufficiently large so that it can be indented to the maximum indentation depth. In this measurement, it was set to 300 mN.
(Unloading process)
・ Minimum load = 0.005mN
Unloading time = (maximum indentation depth) / 10 seconds Unloading was performed until the minimum load of the indenter was reached. The unloading time is determined by the maximum indentation depth of the indentation process. For example, when the maximum indentation depth t = 20 μm, the unloading time is 2 seconds. This is to make the unloading speeds of condition 1 and condition 2 the same. The restoration speed v for elastic deformation was calculated in the same manner as in Condition 1.

[4-5. Image Evaluation 1] Abrasion Evaluation Using a monochrome laser printer ("LaserJet P4515n" (trade name)) manufactured by Japan Hewlett-Packard Co., which is an electrophotographic apparatus having the configuration shown in FIG. 10, voltage is applied to the charging roller from the outside. Applied. The applied voltage was an alternating voltage, and the peak peak voltage (Vpp) was 1800 V, the frequency (f) was 2930 Hz, and the direct voltage (Vdc) was −600 V. The image resolution was output at 600 dpi. The process cartridge for the printer was used as the process cartridge. The attached charging roller was removed from the process cartridge, and the roller member 1 was set as the charging roller. The roller member 1 was brought into contact with the electrophotographic photosensitive member with a pressing force by a spring of 4.9 N at one end and a total of 9.8 N at both ends. The roller member 1 was set in the process cartridge, and the process cartridge was conditioned for 24 hours in a high temperature and high humidity environment having a temperature of 32.5 ° C. and a relative humidity of 80%.

  Then, the following image evaluation was performed. First, a two-sheet intermittent endurance test (endurance test in which the rotation of the printer is stopped for 3 seconds each time two sheets are output) that outputs a horizontal line image having a width of 2 dots and an interval of 176 dots in the direction perpendicular to the rotation direction of the electrophotographic photosensitive member. went. After outputting 20000 sheets, a halftone image (an image in which a horizontal line having a width of 1 dot and an interval of 2 dots was drawn in the direction perpendicular to the rotation direction of the electrophotographic photosensitive member) was output and evaluated. In the evaluation, a halftone image is visually observed, and whether or not a dot-like, horizontal streak-like or vertical streak-like defect due to uneven wear of the photoconductor is recognized in the image is determined according to the following criteria. did.

[4-6. Image Evaluation 2] Evaluation of Banding Occurrence Status After acclimatizing the process cartridge to a low-temperature and low-humidity environment with a temperature of 15 ° C. and a relative humidity of 10% for 24 hours, the same electrophotographic apparatus and voltage application as in the wear evaluation in Image Evaluation 1 Evaluation was performed according to conditions.

  After outputting 20000 sheets, 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) was output. Then, the obtained halftone image was visually observed, and it was determined according to the following criteria whether banding, which is horizontal streak-like density unevenness due to charging unevenness, was observed.

<Examples 2 to 10, 13 to 32, 34 to 40, 42 to 48, and 50 to 56>
At least one of the types of resin particles, the number of added parts, the type of conductive rubber composition, the cutting speed during polishing, the crown amount of the conductive elastic layer, the electron dose in electron beam irradiation, and the electron acceleration voltage in electron beam irradiation. The conditions were changed to those shown in Table 9. Other than that was carried out similarly to Example 1, and produced the roller members 2-10, 13-32, 34-40, 42-48, and 50-56.

<Example 11>
A roller member 11 was produced in the same manner as in Example 1 except that the electron beam irradiation was changed to the following method.

  In performing electron beam irradiation, a stainless steel sheet having a thickness of 100 μm is placed in the central portion of the conductive elastic layer of the conductive roller, the length of which is 224.2 mm, excluding the 15 mm wide portions at both ends. Then, the surface of the conductive elastic layer was coated. In this state, the surface of the conductive elastic layer is irradiated with an electron beam with an acceleration voltage of 80 kV using an area type electron beam irradiation source (trade name: EC150 / 45/40 mA, manufactured by Iwasaki Electric Co., Ltd.) The elastic layer was subjected to a surface treatment on each of 15 mm width portions at both ends.

  Next, a portion other than 15 to 30 mm from each longitudinal end of the conductive elastic layer is covered with a stainless steel sheet, and an acceleration voltage of 90 kV is applied to each 15 to 30 mm portion from both longitudinal ends of the conductive elastic layer. Irradiated with an electron beam.

  Next, a portion other than 30 to 45 mm from each longitudinal end of the conductive elastic layer is covered with a stainless steel sheet, and an acceleration voltage of 100 kV is applied to each 30 to 45 mm portion from both longitudinal ends of the conductive elastic layer. Irradiated with an electron beam.

  Next, the portions other than 45 to 60 mm from both ends in the longitudinal direction of the conductive elastic layer are covered with a stainless steel sheet, and an acceleration voltage of 110 kV is applied to each portion from 45 to 60 mm from both ends in the longitudinal direction of the conductive elastic layer. Irradiated with an electron beam.

  Next, a portion other than 60 to 75 mm from each longitudinal end of the conductive elastic layer is covered with a stainless steel sheet, and an acceleration voltage of 120 kV is applied to each 60 to 75 mm portion from both longitudinal ends of the conductive elastic layer. Irradiated with an electron beam.

  Next, the portions other than 75 to 90 mm from both ends in the longitudinal direction of the conductive elastic layer are covered with a stainless steel sheet, and an acceleration voltage of 130 kV is applied to each portion from 75 to 90 mm from both ends in the longitudinal direction of the conductive elastic layer. Irradiated with an electron beam.

  Next, portions other than 90 to 105 mm from both ends in the longitudinal direction of the conductive elastic layer are covered with a stainless steel sheet, and an acceleration voltage of 140 kV is applied to each portion from 90 to 105 mm from both ends in the longitudinal direction of the conductive elastic layer. Irradiated with an electron beam.

  Finally, except for each 7.1 mm width portion (total width 14.2 mm portion) from the center in the longitudinal direction of the conductive elastic layer to the both ends, this portion having a width of 14.2 mm is covered with a stainless steel sheet. Were irradiated with an electron beam having an acceleration voltage of 150 kV.

  The atmosphere at the time of irradiation was purged with nitrogen gas, the atmosphere oxygen concentration was 500 ppm or less, and the conductive roller was conveyed at a processing speed of 10 mm / sec in the direction perpendicular to the paper surface of FIG. 9 while rotating at 500 rpm. The electron current was adjusted so that the dose at each acceleration voltage was 1000 kGy.

<Example 12>
A roller member 12 was produced in the same manner as in Example 11 except that the resin particle 1 was changed to the resin particle 2.

<Examples 33, 41, 49 and 57>
Roller members 33, 41, 49, and 57 were produced in the same manner as in Example 1 except that the conductive rubber composition 1 was changed to the conductive rubber composition shown in Table 9, respectively.

  Table 9 shows roller member Nos. 1 to 57 according to Examples 1 to 57. 1 to 57, the conductive rubber composition No. 1 used in their production. Resin particle No. And the number of parts, polishing conditions, crown amount, and electron beam irradiation conditions are shown together. Tables 11 and 13 show the evaluation results of the roller members according to the respective examples.

<Comparative Example 1>
A roller member 58 was produced in the same manner as in Example 1 except that the electron beam irradiation was not performed.

<Comparative example 2>
A roller member 59 was produced in the same manner as in Example 1 except that the electron beam irradiation was changed to the following method. The electron beam irradiation was performed using an area type electron beam irradiation source (trade name: EC150 / 45/40 mA, manufactured by Iwasaki Electric Co., Ltd.). The oxygen concentration in the atmosphere was reduced to 500 ppm or less by purging with nitrogen gas, and the conductive roller was conveyed at 10 mm / sec while rotating at 500 rpm with the conductive substrate as the rotation axis. As the electron beam irradiation conditions, the electron current was adjusted so that the acceleration voltage was 80 kV and the dose was 1000 kGy.

<Comparative Example 3>
A roller member 60 was produced in the same manner as in Comparative Example 2, except that the electron acceleration voltage in electron beam irradiation was changed from 80 kV to 150 kV.

<Comparative example 4>
A roller member 61 is formed in the same manner as in Example 50 except that a conductive elastic layer is produced without adding resin particles and without irradiating with an electron beam, and then a conductive surface layer is formed by the following method. Was made.

[Method for forming conductive surface layer]
Methyl isobutyl ketone was added to caprolactone-modified acrylic polyol solution “Placcel DC2016” (trade name, manufactured by Daicel Chemical Industries, Ltd.) to adjust the solid content to 10% by mass. The other three components shown in Table 8 below were added to 1000 parts by mass of this solution (100 parts by mass of acrylic polyol solid content) to prepare a mixed solution.

  Next, 200 parts by mass of the above mixed solution was placed in a glass bottle with an internal volume of 450 mL together with 200 parts by mass of glass beads having an average particle diameter of 0.8 mm as a medium, and dispersed for 24 hours using a paint shaker disperser. Thereafter, polymethyl methacrylate resin particles (average particle size 20 μm) were added and dispersed again for 5 minutes, and the glass beads were removed to prepare a conductive resin coating solution.

  The conductive roller having the polished conductive elastic layer was immersed in the conductive resin coating solution with its longitudinal direction set to the vertical direction, and applied by dipping. As coating conditions, the dipping time is 9 seconds, and the pulling speed from the conductive resin coating liquid is 20 mm / sec for the initial speed and 2 mm / sec for the final speed. The speed was changed. The obtained coated product was air-dried at room temperature for 30 minutes, and then dried in a hot air circulating dryer at a temperature of 80 ° C. for 1 hour and further at a temperature of 160 ° C. for 1 hour. Thus, a roller member 61 having a surface layer formed on the outer peripheral surface of the conductive elastic layer was produced.

<Comparative Example 5>
A roller member 62 was produced in the same manner as in Example 1 except that no resin particles were added and 15 parts by mass of ADCA (azodicarbonamide) was added as a foaming agent.

  Table 10 shows the roller member Nos. According to Comparative Examples 1 to 5. About conductive rubber composition No. used for those about 58-62. Resin particle No. And the number of parts, polishing conditions, crown amount, and electron beam irradiation conditions are shown together. Tables 12 and 14 show the evaluation results of the roller members according to the comparative examples.

DESCRIPTION OF SYMBOLS 1 Conductive base | substrate 2 Conductive elastic layer 11 Bowl-shaped resin particle 12 Conductive elastic layer 13 Electrophotographic photoreceptor 14 Roller member 15 Nip part 41 Bowl-shaped resin particle 42 Conductive elastic layer 51 Opening of bowl-shaped resin particle Portion 52 Recessed portion derived from bowl-shaped resin particles 53 Edge 54 of bowl-shaped resin particle opening 55 Height difference 55 Maximum diameter of bowl-shaped resin particle 61 Opening portion 62 Recessed portion of opening 63 Minimum diameter of opening portion 71 Electron beam Generator 72 Irradiation chamber 73 Irradiation port 74 Electron source (electron gun)
75 Accelerating tube 76 Filament 77 Irradiation port foil 78 Roller member 81 Electron gun 82 Container 83 Irradiation port 84 Filament 85 Electron beam passage hole 86 Electromagnetic coil 87 Deflection coil 88 Irradiation window 89 Roller member 91 Electron gun 92 Container 93 Irradiation port 94 Acceleration tube 95 Filament 96 Irradiation window 97 Roller member 98 Masking 101 Charging roller 102 Electrophotographic photosensitive member 103 Developing roller 104 Transfer roller 105 Fixing roller 106 Cleaning member 107 Exposure light 108 Collection container 109 Power supply for charging

Claims (14)

A roller member for electrophotography having a conductive substrate and a conductive elastic layer as a surface layer,
The conductive elastic layer has a crown shape in which the outer diameter of the central portion in the longitudinal direction of the roller member is larger than the outer diameters of both end portions,
The conductive elastic layer includes a binder and bowl-shaped resin particles,
The surface of the roller member is
A recess derived from the opening of the bowl-shaped resin particles ;
It has a convex portion derived from the edge of the opening, and
The relationship between the elastic deformation restoration speed of the central portion and both ends of the roller member in the longitudinal direction of the conductive elastic layer is as follows:
On the surface of the conductive elastic layer , both end portions are larger than the central portion,
A roller member for electrophotography, wherein the central portion is larger than both end portions at a position t μm deep from the surface of the conductive elastic layer (however, the depth t μm is equal to the depth t μm of the conductive elastic layer). The depth is from 30 μm to 100 μm from the surface) .   The roller member according to claim 1, wherein a restoring speed of the elastic deformation decreases from a surface of the conductive elastic layer in a depth direction. The roller member according to claim 1, wherein the bowl-shaped resin particles are resin particles having an opening and a rounded recess defined by a shell . The distance (height difference) between the apex of the convex portion derived from the edge of the opening of the bowl-shaped resin particles and the bottom of the round concave portion defined by the shell of the bowl-shaped resin particles is 5 μm or more and 100 μm or less the roller member according to any one of claims 1 to 3 is. The distance (height difference) between the apex of the convex portion derived from the edge of the opening of the bowl-shaped resin particles and the bottom of the round concave portion defined by the shell of the bowl-shaped resin particles is from 8 μm to 80 μm The roller member according to claim 4 . The maximum diameter of the bowl-shaped resin particles, the apex of the convex portion derived from the edge of the opening of the bowl-shaped resin particles, and the bottom of the rounded concave portion defined by the shell of the bowl-shaped resin particles The roller member according to claim 4 or 5 , wherein a ratio [maximum diameter] / [height difference] of the distance (height difference) is 0.8 or more and 3.0 or less . The bowl maximum diameter of the resin particles of the shape, the roller member according to any one of claims 1 to 6 at 5μm least 150μm or less. The roller member according to claim 7, wherein a maximum diameter of the bowl-shaped resin particles is 8 μm or more and 120 μm or less. The bowl thickness of the shell of the resin particles of the shape, the roller member according to any one of claims 1-8 is 0.1μm or more 3μm or less. The roller member according to claim 9, wherein a thickness of the shell of the bowl-shaped resin particles is 0.2 μm or more and 2 μm or less. The roller ten-point average roughness of the surface of the member (Rzjis), the roller member according to any one of claims 1-10 is 5μm or more 65μm or less. The roller member according to any one of claims 1 to 11, wherein the uneven average interval (Sm) on the surface of the roller member is 30 µm or more and 200 µm or less . 13. A process cartridge comprising: the electrophotographic roller member according to claim 1; and an electrophotographic photosensitive member, wherein the process cartridge is configured to be detachable from a main body of the electrophotographic apparatus. . A roller member for electrophotography according to any one of claims 1 to 12 the electrophotographic apparatus, characterized by chromatic and electrophotographic photosensitive member.

Images