Conductive member, process cartridge, and electrophotographic image forming apparatus

Abstract

To provide a conductive member that, even when applied to a high-speed electrophotographic image formation process, can perform high-quality image formation and can be used for an electrifying member, a developing member, or a transfer member.SOLUTION: A conductive member for electrophotography has a conductive support, a conductive layer on the support, and a surface layer on the conductive layer. The impedance on an outer surface of the conductive member is 1.0×103 to 1.0×108 Ω. An electronic conductive agent is dispersed in the surface layer. The conductive layer has a matrix that includes a first rubber cross-linked material, and domains that include a second rubber cross-linked material and conductive particles. Of the domains observed in respective predetermined observation areas, 80 number% or more of them satisfy the requirements (1) and (2). (1) The ratio of the cross section of the conductive particle to the domain is 20% or more, and (2) the ratio of the peripheral length A of the domain to the envelope peripheral length B of the domain, A / B is 1.00 to 1.10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a conductive member, a process cartridge, and an electrophotographic image forming apparatus used in an electrophotographic system. [Background technology]

[0002] In electrophotographic image forming apparatuses (hereinafter also referred to as "electrophotographic apparatuses"), conductive members are used as charging members, transfer members, and developing members. Known conductive members include a conductive support and a conductive layer provided on the support. The conductive member transports electric charge from the conductive support to its surface and provides electric charge to a contacting object by discharge or frictional charging. The charging member is a member that generates a discharge between itself and the electrophotographic photosensitive member, thereby charging the surface of the electrophotographic photosensitive member. The developing member is a member that controls the charge of the developer coated on its surface by frictional charging, provides a uniform charge distribution, and then uniformly transfers the developer to the surface of the electrophotographic photosensitive member according to the applied electric field. The transfer member is a member that transfers the developer from the electrophotographic photosensitive member to a print medium or an intermediate transfer member, and at the same time generates a discharge to stabilize the developer after transfer. These conductive members are required to achieve uniform charging of the objects in contact therewith, such as electrophotographic photosensitive members, intermediate transfer members, and printing media. Patent Document 1 discloses a charging member for achieving uniform charging, which has an elastic layer in which an electronically conductive polymer particle phase is dispersed in an ionically conductive semiconductive polymer continuous phase. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-3651 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the inventors' investigations, the charging member disclosed in Patent Document 1 was found to have excellent uniform charging performance for a charged body. However, they recognized that there is still room for improvement in the recent trend toward higher speeds in image formation processes. Specifically, they attempted to form images over a long period of time using a high-speed system in which the charging member disclosed in Patent Document 1 was brought into contact with an electrophotographic photosensitive member and rotated at a higher speed than usual. As a result, for example, even with a high print count in which the accumulation (staining) of toner and external additives on the charging member was not a problem in the past, the accumulation of stains became noticeable, and white spots due to excessive discharge sometimes appeared on the images in the affected areas.

[0005] One aspect of the present disclosure is to provide a conductive member that can be used as a charging member, a developing member, or a transfer member, which enables high-quality image formation over a long period of time even when applied to a high-speed electrophotographic image formation process. Another aspect of the present disclosure is directed to providing a process cartridge that contributes to the formation of high-quality electrophotographic images. Yet another aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus that can form high-quality electrophotographic images. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a conductive member for electrophotography, comprising: a support having a conductive outer surface; a conductive layer provided on the outer surface of the support; and a surface layer provided on the outer surface of the conductive layer, A platinum electrode was provided directly on the outer surface of the conductive member, and an AC voltage with an amplitude of 1 V and a frequency of 1.0 Hz was applied between the outer surface of the support and the platinum electrode in an environment of a temperature of 23°C and a relative humidity of 50%. The impedance was 1.0 x 10 3 ~1.0×10 8 Ω, The surface layer is A binder resin, and a material dispersed in the binder resin Electronic Conductive Agent Includes , the surface of the surface layer has protrusions resulting from exposed portions of the electronic conductive agent, The universal hardness at a depth of 1 μm from the surface of the surface layer is 1.0 N / mm 2 More than 7.0N / mm2 is as follows: the electronic conductive agent is a first conductive carbon black; the conductive layer has a matrix containing a cross-linked product of a first rubber and a domain containing a cross-linked product of a second rubber and conductive particles, The present invention provides a conductive member for electrophotography in which, when the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, 15 μm square observation regions are placed at any three locations in a thickness region from the outer surface of the conductive layer to a depth of 0.1T to 0.9T on a cross section of the conductive layer in the thickness direction, the observation regions being at the longitudinal center of the conductive layer and at three locations spaced at L / 4 from both ends of the conductive layer toward the center, and 80% by number or more of the domains observed in each of the nine observation regions satisfy the following requirement (1) and requirement (2): (1) The ratio of the cross-sectional area of ​​the conductive particles contained in the domain to the cross-sectional area of ​​the domain is 20% or more; (2) When the perimeter of a domain is A and the envelope perimeter of the domain is B, the ratio A / B is 1.00 or more and 1.10 or less. According to another aspect of the present disclosure, there is provided a conductive member for electrophotography, comprising: a support having a conductive outer surface; a conductive layer provided on the outer surface of the support; and a surface layer provided on the outer surface of the conductive layer, A platinum electrode was provided directly on the outer surface of the conductive member, and an AC voltage with an amplitude of 1 V and a frequency of 1.0 Hz was applied between the outer surface of the support and the platinum electrode in an environment of a temperature of 23°C and a relative humidity of 50%. The impedance was 1.0 x 10 3 ~1.0×10 8 Ω, The surface layer has an electronic conductive agent dispersed therein, The volume resistivity of the surface layer is 1.0×10 10 Ω cm or more 1.0×10 16 Ω·cm or less, the conductive layer has a matrix containing a cross-linked product of a first rubber and a domain containing a cross-linked product of a second rubber and conductive particles, The present invention provides a conductive member for electrophotography in which, when the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, 15 μm square observation regions are placed at any three locations in a thickness region from the outer surface of the conductive layer to a depth of 0.1T to 0.9T on a cross section of the conductive layer in the thickness direction, the observation regions being at the longitudinal center of the conductive layer and at three locations spaced at L / 4 from both ends of the conductive layer toward the center, and 80% by number or more of the domains observed in each of the nine observation regions satisfy the following requirement (1) and requirement (2): (1) The ratio of the cross-sectional area of ​​the conductive particles contained in the domain to the cross-sectional area of ​​the domain is 20% or more; (2) When the perimeter of a domain is A and the envelope perimeter of the domain is B, the ratio A / B is 1.00 or more and 1.10 or less.

[0007] According to another aspect of the present disclosure, there is provided a process cartridge configured to be detachably mountable to a main body of an electrophotographic image forming apparatus, comprising: Conductivity A process cartridge having the member is provided. Furthermore, according to another aspect of the present disclosure, Conductive materialsAn electrophotographic imaging apparatus is provided comprising: [Effects of the Invention]

[0008] According to one aspect of the present disclosure, there is provided an electrophotographic conductive member capable of maintaining high image quality for a long period of time even in a high-speed process. Also, according to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus and a process cartridge used therein capable of stably outputting high-quality electrophotographic images. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view of a conductive member according to an embodiment of the present disclosure, taken in a direction perpendicular to the longitudinal direction. [Figure 2] FIG. 2 is a cross-sectional view of a conductive member according to an embodiment of the present disclosure, taken in a direction perpendicular to the longitudinal direction of a conductive layer. [Figure 3A] FIG. 1 is a schematic diagram of an impedance measurement system for a conductive layer according to the present embodiment. [Figure 3B] FIG. 1 is a schematic diagram of an impedance measurement system for a conductive layer according to the present embodiment. [Figure 4] FIG. 1 is a conceptual diagram illustrating the maximum Feret diameter of a domain according to the present embodiment. [Figure 5] FIG. 2 is a conceptual diagram illustrating the envelope perimeter of a domain according to the present embodiment. [Figure 6A] FIG. 2 is a conceptual diagram of a section for measuring the domain shape according to the present embodiment. [Figure 6B] FIG. 2 is a conceptual diagram of a section for measuring the domain shape according to the present embodiment. [Figure 7] FIG. 2 is a cross-sectional view of a process cartridge according to an embodiment of the present disclosure. [Figure 8] 1 is a cross-sectional view of an electrophotographic image forming apparatus according to an embodiment of the present disclosure. [Figure 9] FIG. 4 is a conceptual diagram illustrating the size of the convex portions of the surface layer. DETAILED DESCRIPTION OF THE INVENTION

[0010] The expressions "XX or more and YY or less" or "XX to YY" that represent a numerical range mean a numerical range including the endpoints, that is, the lower limit and the upper limit, unless otherwise specified. When numerical ranges are stated in stages, the upper and lower limits of each numerical range can be combined in any way.

[0011] The inventors investigated why, when the process speed of the charging member according to Patent Document 1 is increased, the accumulation of contaminants such as toner and external additives on the member becomes significant at a high print count, which previously did not pose a problem on the image, resulting in white spots on the electrophotographic image. Generally, a DC voltage is applied to a charging member (charge roller), which generates a potential difference between the DC voltage applied to the charge roller and the surface potential of a photoconductor. Meanwhile, contaminants such as insulating toner and external additives are partially charged positively or negatively due to friction and other factors within an electrophotographic image forming apparatus. Therefore, since a potential difference occurs between the surface potentials of the charge roller and the photoconductor, either positively (+) or negatively (-) charged contaminants electrostatically adhere to the charge roller due to the potential difference. For example, in the case of a charge roller in which a conductive member is disposed in contact with a photoconductor in an electrophotographic apparatus and charges the photoconductor, positively charged contaminants actively electrostatically adhere to the charge roller due to the potential difference between the charge roller and the photoconductor drum. When toner adheres to the charging roller, depending on whether the bias applied to the charging roller is negative or positive, the toner gradually acquires a charge of the same polarity as the applied bias from its outer surface. When sufficient charge accumulates on the dirt, an electrostatic force acts in the electric field formed from the surface of the charging roller toward the photosensitive drum, exceeding the adhesive force between the surface of the charging roller and the dirt, causing a "discharge" phenomenon in which the dirt peels off from the surface and moves toward the photosensitive drum. In other words, if sufficient charge accumulates on most of the dirt and the discharge phenomenon occurs efficiently, the accumulation of dirt can be prevented. Regarding the transport process of negatively or positively charged particles from the support to the surface of the charging roller, where they ultimately reach the contaminants, we focused on the role of the polymer particle phase made of an electronically conductive rubber material within the charging member described in Patent Document 1. According to the inventors' observations, the shapes of all polymer particle phases were significantly different from spherical, and there were many areas where the phase boundaries were concave or convex. Between such polymer particle phases, electron transfer concentrated at the convex portions of the polymer particle phase. When areas of concentrated electron transfer occurred, other areas also developed where electron transfer was insufficient. This resulted in uneven charge transfer during the transport process. Particularly in high-speed processes, the amount of toner and other contaminants coming into contact per unit time increased, shortening the time between the attachment of a contaminant and the next attachment of another contaminant, which is the most important factor in imparting charge to the contaminants. This resulted in a more pronounced decrease in the amount of charge supplied to the contaminants. From the above, it was speculated that the occurrence of white spots on images due to the accumulation of dirt when the process speed is increased is caused by the occurrence of uneven density of electron transfer between polymer particle phases, which causes areas on the charging roller surface where the ejection phenomenon is insufficient, accelerating the accumulation of dirt in those areas, resulting in the occurrence of white spots on electrophotographic images.

[0012] Therefore, the present inventors have recognized that eliminating the concentration points of electron transfer between polymer particle phases and ensuring uniform charge supply to dirt on the surface will promote the ejection effect and suppress the accumulation of dirt, and will be effective in improving the occurrence of white spots on images. Based on this recognition and after further investigation, the present inventors have discovered a conductive member for electrophotography having a support having a conductive outer surface, a conductive layer provided on the outer surface of the support, and a surface layer provided on the outer surface of the conductive layer, It has been discovered that a conductive member that satisfies the following requirements (A), (B), (C), and (D) can suppress the occurrence of white spots due to accumulated dirt over a long period of time even in high-speed processes.

[0013] ·Requirements (A) A platinum electrode was provided directly on the outer surface of the conductive member, and an AC voltage with an amplitude of 1 V and a frequency of 1.0 Hz was applied between the outer surface of the support and the platinum electrode in an environment of a temperature of 23°C and a relative humidity of 50%. The impedance was 1.0 x 10 3 ~1.0×10 8 Being Omega.

[0014] ·Requirements (B) The conductive layer has a matrix containing a cross-linked product of a first rubber, and a domain containing a cross-linked product of a second rubber and conductive particles.

[0015] ·Requirements (C) The length of the conductive layer in the longitudinal direction is L, and the thickness of the conductive layer is T. For each cross section of the conductive layer in the thickness direction, at the center of the conductive layer in the longitudinal direction and at three locations at L / 4 from both ends of the conductive layer toward the center, observation regions measuring 15 μm square are placed at any three locations in a thickness region from the outer surface of the conductive layer to a depth of 0.1T to 0.9T. Of the domains observed in each of the nine observation regions, 80% or more by number satisfy the following requirements (1) and (2). (1) The ratio of the cross-sectional area of ​​the conductive particles contained in the domain to the cross-sectional area of ​​the domain is 20% or more; (2) When the perimeter of a domain is A and the envelope perimeter of the domain is B, the ratio A / B is 1.00 or more and 1.10 or less.

[0016] ·Requirements (D) The surface layer has an electronic conductive agent dispersed therein.

[0017] <Requirements (A)> Requirement (A) represents the degree of conductivity of the conductive member. A conductive member exhibiting such an impedance value can suppress an excessive increase in the amount of discharge current, thereby preventing the occurrence of potential unevenness due to abnormal discharge. It can also suppress the occurrence of a deficiency in the total amount of discharge charge and a deficiency in the amount of injected charge supplied to the dirt.

[0018] The impedance required for requirement (A) can be measured by the following method. First, when measuring impedance, in order to eliminate the influence of contact resistance between the conductive member and the measurement electrode, a thin film of platinum is formed on the outer surface of the conductive member, and the thin film is used as an electrode, with the conductive support as the ground electrode, and the impedance is measured using two terminals. The thin film can be formed by metal vapor deposition, sputtering, applying a metal paste, attaching with a metal tape, etc. Among these, the vapor deposition method is preferred from the viewpoint of reducing the contact resistance with the conductive member. When forming a platinum thin film on the surface of a conductive member, it is preferable to provide a vacuum deposition apparatus with a mechanism for gripping the conductive member, taking into consideration the ease of the process and the uniformity of the thin film. Furthermore, for conductive members with a cylindrical cross section, it is preferable to use a vacuum deposition apparatus further equipped with a rotation mechanism. For conductive members with a cylindrical cross section, it is preferable to form a platinum thin-film electrode approximately 10 mm wide in the longitudinal direction (the axial direction of the cylindrical shape) and perform measurements by tightly wrapping a metal sheet around the platinum thin-film electrode and connecting it to the measurement electrode extending from the measurement device. This allows impedance measurements to be performed without being affected by variations in the outer diameter or surface shape of the conductive member. Aluminum foil, metal tape, etc. can be used as the metal sheet. Examples of devices for measuring impedance include an impedance analyzer, a network analyzer, and a spectrum analyzer. Among these, an impedance analyzer is preferably used because of the electrical resistance range of the charging member. 3A and 3B show schematic diagrams of a state in which a measurement electrode is formed on a conductive member. In FIGS. 3A and 3B, 31 denotes a support, 32 denotes a conductive layer and a surface layer, 33 denotes a platinum vapor-deposited layer that serves as a measurement electrode, and 34 denotes an aluminum sheet. FIG. 3A shows a perspective view, and FIG. 3B shows a cross-sectional view. As shown in the figures, it is important to sandwich the conductive layer and surface layer 32 between the support 31 and the measurement electrode 33.

[0019] Then, the aluminum sheet 34 is connected to the measuring electrode 33 and the support 31 in an impedance measuring device (for example, product name "Solatron 1260", 96W type dielectric impedance measuring system manufactured by Solartron, not shown), and impedance measurement is performed. The impedance is measured in an environment of a temperature of 23°C and a relative humidity of 50%, with an oscillating voltage (amplitude) of 1 Vpp and a frequency of 1.0 Hz, and the absolute value of the impedance is obtained. The conductive member is divided into five equal regions in the longitudinal direction, and the above measurement is carried out five times in total, once in each region at random, and the average value is taken as the impedance of the conductive member.

[0020] <Requirements (B)> The configuration of the matrix containing the cross-linked product of the first rubber of the conductive layer and the domain containing the cross-linked product of the second rubber and conductive particles will be described in detail later in the <Conductive Layer> section.

[0021] <Requirements (C)> In requirement (C), requirement (1) specifies the amount of conductive particles contained in each domain of the conductive layer, and requirement (2) specifies that the domain shape is close to a perfect sphere and that the outer periphery of the domain has few convex or concave portions (hereinafter referred to as the outer periphery of the domain having few or no concave portions). Regarding requirement (1), the inventors have found that, when focusing on a single domain, the amount of conductive particles contained in the domain affects the domain shape. That is, as the amount of conductive particles in a single domain increases, the shape of the domain becomes more spherical. The more domains that are close to spheres, the fewer the points at which electrons are exchanged between domains. The inventors then focused on the ratio of the cross-sectional area of ​​one domain to the total cross-sectional area of ​​the conductive particles observed in the cross-section. According to the inventors' investigations, although the reason for this is unclear, domains with this ratio of 20% or more can have an outer shape that can significantly alleviate the concentration of electron transfer between domains. Specifically, they can have a shape closer to a sphere. Requirement (2) defines the degree of unevenness on the outer periphery of a domain that could become a concentration point for electron transfer. That is, when the periphery of a domain is A and the envelope periphery of the domain is B, a domain with an A / B ratio of 1.00 has no unevenness on its periphery. Furthermore, according to the inventors' investigations, it was recognized that domains with an A / B ratio of 1.00 or greater and 1.10 or less have substantially no unevenness that could become a concentration point for electron transfer between domains. The envelope periphery is the periphery (dashed line 52) obtained by connecting the convex portions of domains 51 observed within the observation area, ignoring the peripheries of concave portions, as shown in FIG. 5 . Requirement (C) stipulates that, of the domains in the conductive layer, domains that satisfy the above requirements (1) and (2) account for the majority, ie, 80% or more by number. In requirement (C), the reason why the domain observation target is within a range of depths of 0.1T to 0.9T from the outer surface of the conductive layer in the cross section in the thickness direction of the conductive layer is as follows: That is, the movement of electrons in the conductive layer from the support side toward the outer surface side of the conductive layer is considered to be mainly controlled by the domains present within that range.

[0022] <Requirements (D)> A surface layer that satisfies requirement (D) enables the charge supplied uniformly from the conductive layer that satisfies requirement (C) to be reliably transferred to the dirt regardless of the contact form of the dirt. For example, if there is no surface layer that satisfies requirement (D), the contact area between the toner and the conductive layer is small, and the contact area is the matrix part of the conductive layer, the charge may not be sufficiently transferred to the dirt. The presence of a surface layer with an electronic conductive agent dispersed therein enables the charge to be transferred more uniformly. Among conductive agents, an electronic conductive agent is required due to its fast response.

[0023] As one embodiment of the electroconductive member for electrophotography according to the present disclosure, a conductive member having a roller shape (hereinafter also referred to as a "conductive roller") will be described with reference to the drawings. 1 is a cross-sectional view perpendicular to the longitudinal direction of a conductive roller 11. The conductive roller 11 has a columnar or hollow cylindrical support 12, a conductive layer 13 formed on the outer peripheral surface of the support, and a surface layer 14. 2 shows a cross-sectional view of the conductive roller excluding the support, taken in a direction perpendicular to the longitudinal direction of the conductive roller. The conductive layer 23 has a structure including a matrix 23a and domains 23b (hereinafter also referred to as a "matrix-domain structure"). The domains 23b contain conductive particles 23c. A surface layer 24 containing an electronic conductive agent (not shown) is formed on the outer surface of the conductive layer 23. The domains, matrix, and surface layer in the conductive layer in FIGS. 1 and 2 are shown only as outlines for ease of understanding, and their sizes, ratios, etc. are not specified.

[0024] <Support> The material constituting the support can be appropriately selected from materials known in the field of electroconductive materials for electrophotography and materials usable as conductive materials, such as aluminum, stainless steel, conductive synthetic resins, iron, copper alloys, and other metals or alloys. Furthermore, these may be subjected to oxidation treatment or plating treatment with chromium, nickel, etc. As the type of plating, either electroplating or electroless plating can be used. From the viewpoint of dimensional stability, electroless plating is preferred. Examples of the types of electroless plating used here include nickel plating, copper plating, gold plating, and various other alloy platings. The plating thickness is preferably 0.05 μm or more, and considering the balance between work efficiency and anti-corrosion ability, the plating thickness is preferably 0.10 μm to 30.00 μm. The shape of the support can be a columnar or hollow cylindrical shape. The columnar shape of the support may be a solid columnar or a hollow columnar (cylindrical). The outer diameter of the support is preferably in the range of 3 mm to 10 mm. Furthermore, if necessary, partial processing is performed for installation in an electrophotographic device. If a medium-resistance layer or an insulating layer is present between the support and the conductive layer, it may be impossible to quickly supply charge after the charge is consumed by discharge. Therefore, it is preferable to provide the conductive layer directly on the support, or to provide the conductive layer on the outer periphery of the support via only an intermediate layer made of a thin conductive resin layer such as a primer. As the primer, a known material can be selected and used depending on the rubber material for forming the conductive layer, the material of the support, etc. Examples of the primer material include thermosetting resins and thermoplastic resins, and specifically, known materials such as phenolic resins, urethane resins, acrylic resins, polyester resins, polyether resins, and epoxy resins can be used.

[0025] <Conductive layer> The conductive layer has a matrix and a plurality of domains dispersed in the matrix, the matrix containing a first rubber and the domains containing a second rubber and an electronic conductive agent. <Matrix> The matrix contains a crosslinked product of the first rubber. The volume resistivity ρm of the matrix is ​​1.0×10 8 Ωcm or more 1.0×10 17 The volume resistivity of the matrix is ​​preferably 1.0×10 8 By setting the volume resistivity ρm to 1.0×10 Ωcm or more, it is possible to prevent the matrix from disturbing the exchange of charges between conductive domains. 17 By setting the matrix volume resistivity ρm to 1.0×10 Ωcm or less, discharge from the conductive member to the member to be charged can be smoothly performed when a charging bias is applied between the support and the member to be charged. 10 Ωcm or more 1.0×10 17 Ωcm or less, and even 1.0×10 12 Ωcm exceeded 1.0×10 17 Ωcm or less is preferable.

[0026] The volume resistivity ρm of the matrix can be measured, for example, by cutting a thin slice of a predetermined thickness (e.g., 1 μm) containing a matrix domain structure from the conductive layer and contacting the matrix in the thin slice with a microprobe of a scanning probe microscope (SPM) or an atomic force microscope (AFM). For example, as shown in FIG. 6A, when the longitudinal direction of the conductive member is the X axis, the thickness direction of the conductive layer is the Z axis, and the circumferential direction is the Y axis, the slice is cut out so as to include at least a portion of cross section 62a parallel to the XZ plane. Alternatively, as shown in FIG. 6B, the slice is cut out so as to include at least a portion of a YZ plane (e.g., 63a, 63b, 63c) perpendicular to the axial direction of the conductive member. For example, a sharp razor, a microtome, or a focused ion beam (FIB) method may be used.

[0027] To measure volume resistivity, one side of a thin piece cut from the conductive layer is grounded. Next, the microprobe (tip of a cantilever) of a scanning probe microscope (SPM) or atomic force microscope (AFM) is contacted with the matrix portion of the surface opposite the grounded surface of the thin piece, and a DC voltage of 50 V is applied for 5 seconds. The ground current value is measured for 5 seconds, and the arithmetic mean is calculated from the measured value. The applied voltage is then divided by this calculated value to calculate the electrical resistance. Finally, the resistance value is converted to volume resistivity using the thickness of the thin piece. At this time, the SPM or AFM can measure the thickness of the thin piece at the same time as the resistance value. The volume resistivity value of the matrix in a cylindrical charging member is determined, for example, by dividing the conductive layer into four regions in the circumferential direction and five regions in the longitudinal direction, cutting out one thin sample from each region, obtaining the above-mentioned measurements, and then calculating the arithmetic average value of the volume resistivities of a total of 20 samples.

[0028] <First Rubber> The first rubber is the component with the largest compounding ratio in the rubber composition for forming the conductive layer, and the cross-linked product of the first rubber determines the mechanical strength of the conductive layer. Therefore, the first rubber used is one that, after cross-linking, provides the conductive layer with the strength required for a conductive member for electrophotography. Preferred examples of the first rubber are listed below. Natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), ethylene-propylene rubber (EPM), ethylene-propylene-diene terpolymer rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (H-NBR), and silicone rubber.

[0029] If necessary, the first rubber forming the matrix may contain fillers, processing aids, vulcanization aids, vulcanization accelerators, vulcanization acceleration aids, vulcanization retarders, antioxidants, softeners, dispersants, colorants, and the like, which are generally used as compounding agents for rubber.

[0030] <domain> The domain contains a crosslinked product of the second rubber and conductive particles. Here, conductive means that the volume resistivity is 1.0×10 8 It is defined as less than Ωcm.

[0031] <Second Rubber> Specific examples of the second rubber include at least one selected from the group consisting of natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), butyl rubber (IIR), ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), chlorprene rubber (CR), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), silicone rubber, and urethane rubber (U).

[0032] <Conductive particles> Conductive particles include conductive carbon black (also called "second conductive carbon black") Examples of the conductive particles include carbon materials such as graphite, conductive oxides such as titanium oxide and tin oxide, metals such as Cu and Ag, and particles of electronic conductive agents such as particles coated with a conductive oxide or metal to make them conductive. Two or more types of these conductive particles may be used in appropriate amounts. As defined in requirement (C)(1), the conductive particles are preferably contained so that the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain is at least 20%. By densely packing the conductive particles into the domain in this manner, the external shape of the domain can be made closer to a sphere, and the irregularities can be reduced as defined in requirement (C)(2). There is no particular upper limit to the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain, but it is preferably 30% or less.

[0033] In order to obtain a domain in which conductive particles are densely packed as defined in requirement (C)(1), it is preferable to use conductive carbon black as the conductive particles. Specific examples of conductive carbon black are listed below. Gas furnace black, oil furnace black, thermal black, lamp black, acetylene black, ketjen black. Among them, DBP absorption was 40 cm 3 / 100g or more 80cm 3 Carbon black having a DBP absorption capacity (cm) of 100 g or less can be particularly preferably used. 3 / 100g) is the volume of dibutyl phthalate (DBP) that can be adsorbed by 100g of carbon black, and is measured in accordance with Japan Industrial Standards (JIS) K 6217-4:2017 (Carbon black for rubber - Fundamental properties - Part 4: Determination of oil absorption (including compressed samples)). Generally, carbon black has a cluster-like high-order structure in which primary particles with an average particle size of 10nm to 50nm are aggregated. This cluster-like high-order structure is called structure, and its degree is expressed as DBP absorption (cm 3 It is quantified in units of 100g / 100g. Generally, carbon black with a developed structure has a high reinforcing effect on rubber, which makes it difficult to incorporate the carbon black into rubber and increases the shear torque during kneading, making it difficult to increase the amount of carbon black loaded into the domains. On the other hand, conductive carbon black with DBP absorption within the above range has an underdeveloped structure, resulting in less carbon black aggregation and good dispersibility in rubber, which allows for a larger loading amount in the domains, making it easier to obtain domains with an external shape closer to a sphere. Furthermore, carbon black with a developed structure tends to aggregate easily, and the aggregates tend to form large, uneven masses. If such aggregates are contained in a domain, it is difficult to obtain the domain required by requirement (C)(2). This may even affect the shape, forming an uneven structure. On the other hand, conductive carbon black with a DBP absorption amount within the above range is effective in obtaining the domain required by requirement (C)(2) because it is difficult to form aggregates. The content of the electronic conductive agent such as conductive carbon black is preferably 20 parts by mass or more and 150 parts by mass or less, more preferably 50 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the second rubber contained in the domain.

[0034] The volume resistivity of the domain is 1.0×10 4 It is preferable to keep it below 1.0×10 Ωcm. 4 This is because, if the resistivity is Ωcm or less, the domain volume fraction that forms a stable matrix-domain structure can be made conductive. The volume resistivity of the domain can be measured in the same manner as in the above-mentioned method for measuring the volume resistivity of the matrix, except that the measurement location is changed to a location corresponding to the domain and the applied voltage when measuring the current value is changed to 1 V.

[0035] To obtain a conductive member as defined in requirement (A), it is more preferable that the domains according to this embodiment have 20 to 300 domains within a specific observation area. In the present disclosure, when the thickness of the conductive layer is T, a 15 μm square observation area is placed at any position within a thickness region from the outer surface of the conductive layer to a depth of 0.1T to 0.9T in a cross section of the conductive layer in the thickness direction. The number of domains contained within the observation area is preferably 20 or more. This ensures sufficient conductivity as a conductive member and enables sufficient charge supply even in higher-speed electrophotographic image formation processes. Furthermore, the number of domains within the observation area is preferably 300 or less. This allows for sufficient distance between the domains, preventing aggregation of the domains even with long-term use. As a result, uniform discharge can be achieved over a long period of time.

[0036] In the domains according to this embodiment, the average of the maximum Feret diameter Df (see FIG. 4, hereinafter simply referred to as "domain diameter") of the domains 41 that satisfy the requirements (C)(1) and (C)(2) is preferably within the range of 0.1 to 5.0 μm. Within this range, the size is the same as or smaller than that of the developer, enabling fine discharge and facilitating uniform discharge.

[0037] <Method of manufacturing conductive layer> The conductive layer of the conductive member according to this embodiment can be formed, for example, by a method including the following steps (i) to (iv).

[0038] Step (i): preparing a domain-forming rubber composition (hereinafter also referred to as "CMB") containing carbon black and a second rubber; Step (ii): preparing a matrix-forming rubber composition (hereinafter also referred to as "MRC") containing a first rubber; Step (iii): A step of kneading the CMB and the MRC to prepare a rubber composition having a matrix-domain structure. Step (iv): A step of forming a layer of the rubber composition prepared in step (iii) on a support directly or via another layer, and curing the layer of the rubber composition to form the conductive layer according to this embodiment.

[0039] To obtain a domain that satisfies requirement (C), the conductive particles used to prepare CMB must have a DBP absorption of 40 cm 3 / 100g or more 170cm 3 / 100g or less, preferably, the DBP absorption amount is 40cm 3 / 100g or more 80cm 3 It is effective to prepare a CMB by adding a large amount of carbon black having a carbon black content of 100g or less to the second rubber and kneading them. In this case, the amount of carbon black to be compounded with respect to the second rubber in the CMB is preferably, for example, 40 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the second rubber. In particular, it is 50 parts by mass or more and 100 parts by mass or less. The content of the conductive particles in the domain is preferably such that Dc, which is the arithmetic mean of the distance between the conductive particles in the domain, is 110 nm or more and 130 nm or less. When the Dc of the conductive particles in a domain is between 110 nm and 130 nm, electrons can be transferred between almost all conductive particles within the domain via the tunnel effect. This means that uneven distribution of conductive paths within the domain can be suppressed, thereby suppressing electric field concentration within the domain. As a result, in addition to the domain shape, electric field concentration within the domain can also be suppressed. Furthermore, the amount of carbon gel in rubber containing dispersed carbon black particles, which exhibits properties similar to cross-linked rubber, increases, making it easier to maintain the shape and keep the domains spherical during molding. As a result, electric field concentration is suppressed. Furthermore, it is more preferable that the conductive particles have a Dc of 110 nm or more and 130 nm or less, and that the coefficient of variation σm / Dc of the interparticle distances of the conductive particles is 0.0 or more and 0.3 or less, where σm is the standard deviation of the distribution of the distances between the conductive particles. The coefficient of variation is a value that indicates the variation in the distances between the conductive particles, and is 0.0 when the distances between the conductive particles are all the same. When this coefficient of variation σm / Dc is between 0.0 and 0.3, the interparticle distance of the carbon black particles varies little, meaning that the carbon black particles are uniformly dispersed. As a result, the irregularities in the domains caused by agglomerates (secondary particles) of the carbon black particles can be suppressed. As a result, electric field concentration can be suppressed.

[0040] The Dc of the conductive particles in a domain and the ratio of the conductive particle cross section to the domain cross section area can be measured as follows: First, a thin section of the conductive layer is prepared. To facilitate observation of the matrix-domain structure, pretreatment such as dyeing or vapor deposition may be performed to favorably obtain contrast between the conductive and insulating phases. The formed and pretreated thin section of the fracture surface can be observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Among these, observation using an SEM at 1,000 to 100,000 magnifications is preferred for the accuracy of quantifying the area of ​​the domains that are the conductive phase. The obtained observation image is binarized and analyzed using an image analyzer or the like to obtain the arithmetic mean distance Dc and the above ratio.

[0041] Furthermore, in order to further reduce the electric field concentration between domains, it is preferable to make the external shape of the domains closer to a sphere. To achieve this, it is preferable to make the domain diameter smaller within the above-mentioned range. One method for this is to control the domain diameter of the CMB to be smaller in the process of preparing a rubber composition in which MRC and CMB are mixed together to cause phase separation between the MRC and CMB and form CMB domains in an MRC matrix. By reducing the domain diameter of the CMB, the total specific surface area of ​​the CMB increases, and the interface with the matrix increases. Therefore, tension acts on the interface of the CMB domains to reduce the tension. As a result, the external shape of the CMB domains becomes closer to a sphere. Here, the factors that determine the domain diameter D in the matrix-domain structure formed when two immiscible polymers are melt-kneaded are known to be Taylor's formula (formula (4)), Wu's empirical formula (formulas (5) and (6)), and Tokita's formula (formula (7)) (Sumitomo Chemical Technical Journal 2003-II, 42).

[0042] Taylor's formula D=[C·σ / ηm·γ]·f(ηm / ηd) (4)

[0043] Wu's Empirical Formula γ·D·ηm / σ=4(ηd / ηm) 0.84 ηd / ηm>1 (5) γ·D·ηm / σ=4(ηd / ηm) -0.84 ηd / ηm<1 (6)

[0044]

number

[0045] In equations (4) to (7), D is the CMB domain diameter (maximum Feret diameter Df), C is a constant, σ is the interfacial tension, ηm is the viscosity of the matrix, and ηd is the viscosity of the domain. In equation (7), γ is the shear rate, η is the viscosity of the mixture, P is the probability of collision and coalescence, φ is the domain phase volume, and EDK is the domain phase cleavage energy.

[0046] From the above formulas (4) to (7), it is clear that controlling the physical properties of the CMB and MRC and the kneading conditions in step (iii) is effective for reducing the CMB domain diameter D. Specifically, it is effective to control the following four factors (a) to (d): (a) Difference in interfacial tension σ between the CMB and the MRC; (b) The ratio (ηm / ηd) of the viscosity of the CMB (ηd) and the viscosity of the MRC (ηm); (c) Shear rate (γ) and energy content (EDK) during kneading of CMB and MRC in step (iii); (d) Volume fraction of CMB in the mixture of CMB and MRC in step (iii).

[0047] (a) Interfacial tension difference between the CMB and the MRC Generally, when two immiscible rubbers are mixed, phase separation occurs. This occurs because the interactions between identical polymers are stronger than those between different polymers, leading to aggregation of identical polymers, reducing free energy and stabilizing the mixture. Because the interface of a phase-separated structure comes into contact with different polymers, the free energy is higher than in the interior, which is stabilized by interactions between identical molecules. As a result, interfacial tension is generated, which reduces the contact area with the different polymers to reduce the interfacial free energy. When this interfacial tension is low, the different polymers tend to mix more uniformly in order to increase entropy. A uniform mixture is called a solution, and the SP value, which is an indicator of solubility, tends to correlate with interfacial tension. In other words, the difference in interfacial tension between CMB and MRC is thought to correlate with the difference in SP value between CMB and MRC. Therefore, it is possible to control the interfacial tension by changing the combination of MRC and CMB, particularly the combination of the first rubber and the second rubber. The absolute value of the difference in solubility parameter (SP value) between the first rubber in MRC and the second rubber in CMB is 0.4 (J / cm 3 ) 0.5 More than 4.0(J / cm 3 ) 0.5 Below 0.4 (J / cm3 ) 0.5 It is preferable to select a rubber such that the following is satisfied: 3.0 (J / cm 3 ) 0.5 or less. Within this range, a stable phase separation structure can be formed, and the domain diameter D of the CMB can be reduced.

[0048] <Method for Measuring SP Value> The SP values of the first rubber and the second rubber contained in each of the MRC and the CMB can be accurately calculated by creating a calibration curve using materials with known SP values. This known SP value can also be the catalog value of the material manufacturer. For example, for NBR and SBR, the SP value is almost determined by the content ratio of acrylonitrile or styrene regardless of the molecular weight. Therefore, analyze the content ratio of acrylonitrile or styrene for the rubbers constituting the matrix and the domain using analytical methods such as pyrolysis gas chromatography (Py-GC) and solid NMR. Then, the SP value can be calculated based on the content ratio from the calibration curve obtained from materials with known SP values. Also, for isoprene rubber, the SP value is determined by the isomer structure such as 1,2-polyisoprene, 1,3-polyisoprene, 3,4-polyisoprene, cis-1,4-polyisoprene, and trans-1,4-polyisoprene. Therefore, similar to SBR and NBR, analyze the isomer content ratio using Py-GC and solid NMR, etc., and calculate the SP value from materials with known SP values. The SP value of the material with known SP value is obtained by the Hansen sphere method.

[0049] (b) Viscosity Ratio between CMB and MRC The closer the viscosity ratio (ηd / ηm) between CMB and MRC is to 1, the smaller the maximum Feret diameter of the domains. The viscosity ratio between CMB and MRC can be adjusted by selecting the Mooney viscosity of the CMB and MRC, and by the type and amount of filler used. It can also be adjusted by adding a plasticizer such as paraffin oil to the extent that it does not interfere with the formation of a phase-separated structure. The viscosity ratio can also be adjusted by adjusting the temperature during kneading. The viscosity of CMB and MRC can be obtained by measuring the Mooney viscosity ML(1+4) at the rubber temperature during kneading, based on JIS K6300-1:2013.

[0050] (c) Shear rate and energy content during mixing of MRC and CMB The faster the shear rate during kneading of MRC and CMB, and the greater the amount of energy during shearing, the smaller the maximum Feret diameter Df of the domains can be. The shear rate can be increased by increasing the inner diameter of the mixing element, such as the blade or screw, reducing the gap between the end face of the mixing element and the inner wall of the mixing machine, or by increasing the rotation speed. The energy during shearing can also be increased by increasing the rotation speed of the mixing element or by increasing the viscosity of the first rubber in the CMB and the second rubber in the MRC.

[0051] (d) Domain volume fraction (volume fraction of CMB in the mixture of CMB and MRC) The volume fraction of CMB in a mixture of CMB and MRC correlates with the probability of collision and coalescence of CMB with MRC. Specifically, reducing the volume fraction of CMB in a mixture of CMB and MRC reduces the probability of collision and coalescence of CMB and MRC. In other words, the domain size can be reduced by reducing the volume fraction of the domain in the conductive layer within the range that achieves the required conductivity.

[0052] <How to confirm the matrix-domain (MD) structure> The matrix-domain structure according to this embodiment can be confirmed, for example, by the following method. That is, a thin piece of the conductive layer is cut out from the conductive layer to prepare an observation sample. Examples of means for cutting out the thin piece include a razor, a microtome, and an FIB. The observation sample is subjected to a treatment (for example, a staining treatment or a vapor deposition treatment) that makes it easier to distinguish between the matrix and the domains, as necessary, and then observed using a laser microscope, SEM, or TEM.

[0053] <Methods for measuring domain perimeter, envelope perimeter, maximum and average Feret diameter, and number and average number of domains> The domain perimeter, envelope perimeter, maximum Feret diameter, and domain number according to this embodiment can be measured, for example, as follows. First, slices are prepared using a method similar to that used to measure the volume resistivity of the matrix. Then, thin sections with fractured surfaces can be prepared using techniques such as freeze-fracture, cross-polishing, or focused ion beam (FIB). Considering the smoothness of the fractured surface and pretreatment for observation, the FIB method is preferred. Furthermore, to facilitate observation of the matrix-domain structure, pretreatments such as staining and vapor deposition may be used to favorably enhance the contrast between the conductive and insulating phases. The fracture surface can be formed and the pretreated thin section can be observed using SEM or TEM. Among these, observation using SEM at 1,000x to 100,000x magnification is preferred from the viewpoint of accuracy in quantifying the domain perimeter, envelope perimeter, and maximum Feret diameter. The domain perimeter, envelope perimeter, maximum Feret diameter, and domain number can be measured by quantifying the captured image as described above. The fracture surface image obtained by SEM observation is converted to an 8-bit grayscale image using image processing software such as Image-Pro Plus (manufactured by Planetron Corporation) to obtain a monochrome image with 256 gradations. The image is then binarized by inverting the black and white of the image so that the domains in the fracture surface appear white. The perimeter, envelope perimeter, maximum Feret diameter, and domain number can then be calculated for each of the domain groups in the image. For the above measurement, when the length of the conductive layer of the conductive member in the longitudinal direction is L, slices are cut out from three locations: the center of the conductive layer in the longitudinal direction, and two locations at L / 4 from both ends of the conductive layer toward the center. The direction in which the slices are cut out is the direction of a cross section perpendicular to the longitudinal direction of the conductive layer.

[0054] The reason for evaluating the domain shape in a cross section perpendicular to the longitudinal direction of the conductive layer as described above is as follows: Figures 6A and 6B show the shape of the conductive member 61 in three dimensions along three axes, specifically the X, Y, and Z axes. In Figures 6A and 6B, the X axis is parallel to the longitudinal direction (axial direction) of the conductive member, and the Y and Z axes are perpendicular to the axial direction of the conductive member.

[0055] FIG. 6A shows an image of a conductive member cut out at a cross section 62a parallel to an XZ plane 62. The XZ plane can rotate 360° around the axis of the conductive member. Considering that the conductive member rotates in contact with the photosensitive drum and discharges when passing through a gap between the photosensitive drum, the cross section 62a parallel to the XZ plane 62 represents a surface on which discharge occurs simultaneously at a certain timing. Therefore, the surface potential of the photosensitive drum is formed by the passage of a surface equivalent to a certain amount of the cross section 62a. Because locally large discharges due to electric field concentration within the conductive member cause localized increases on the photosensitive drum surface, resulting in fogging, an evaluation is required that correlates with the photosensitive drum surface potential, which is formed by the passage of a collection of cross sections 62a rather than a single cross section 62a of a certain amount. Therefore, rather than analyzing a cross section where discharges occur simultaneously at a certain moment, such as cross section 62a, an evaluation is required of cross sections (63a-63c) parallel to a YZ plane 63 perpendicular to the axial direction of the conductive member, which allows evaluation of the domain shape including a certain amount of cross sections 62a. When the longitudinal length of the conductive layer is L, cross sections 63a-63c are selected at three locations: cross section 63b at the longitudinal center of the conductive layer, and two cross sections (63a and 63c) located at L / 4 from both ends of the conductive layer toward the center. Furthermore, with regard to the observation positions of each of the cross sections 63a to 63c, 15 μm square observation regions are placed at any three locations in the thickness region from the outer surface of each section to a depth of 0.1 T to 0.9 T, where T is the thickness of the conductive layer, and measurements are taken at a total of nine locations. The average value of each value represents the average value of the nine observation regions.

[0056] <Surface layer> The surface layer contains an electronic conductive agent. When the surface layer is formed in a state where the electronic conductive agent is dispersed in the binder resin, the dispersion is sufficiently promoted, which is also preferable in terms of the physical durability of the surface layer. The surface layer may contain roughening particles, a surface release agent, etc., as necessary.

[0057] <Electron conductive agent> The surface layer contains conductive carbon black as an electronic conductive agent. (also called "first conductive carbon black")Examples of conductive particles include metal oxide-based conductive particles such as titanium oxide, tin oxide, and zinc oxide, and metal-based conductive particles such as aluminum, iron, copper, and silver. These conductive particles can be used alone or in combination of two or more. Furthermore, composite particles in which silica particles are coated with conductive particles can also be used as conductive particles. Carbon black is preferred as the conductive particle used in the surface layer. Carbon black has a low specific gravity and high conductivity, so adding a small amount to the binder resin can ensure sufficient conductivity for the surface layer. In the present disclosure, it is preferable to maintain the hardness of the surface layer at a low level, and therefore carbon black suitable for addition in small amounts is preferred.

[0058] <Binder resin> Known binder resins can be used. Examples include various synthetic resins, natural rubber and its vulcanized form, synthetic rubber, and other rubbers. Examples of binder resins that can be used include fluororesins, polyamide resins, acrylic resins, polyurethane resins, silicone resins, butyral resins, styrene-ethylene-butylene-olefin copolymers, and olefin-ethylene-butylene-olefin copolymers. The binder resins of the present disclosure preferably do not contain ether bonds, such as polyethylene oxide and polypropylene oxide. While ether-based urethane resins can reduce the universal hardness, they are unsuitable for the binder resins of the present disclosure due to their reduced volume resistivity. The binder resins can be used alone or in combination of two or more. Among these binder resins, resins containing a polycarbonate structure are particularly preferred to achieve both flexibility by reducing the universal hardness of the surface layer and high resistance of the surface layer. The polycarbonate structure has low polarity, allowing the binder resin itself to maintain a high volume resistivity. Specifically, polycarbonate-based polyurethane obtained by copolymerizing polycarbonate polyol and polyisocyanate is preferred.

[0059] Examples of polycarbonate polyols include polynonamethylene carbonate diol, poly(2-methyl-octamethylene) carbonate diol, polyhexamethylene carbonate diol, polypentamethylene carbonate diol, poly(3-methylpentamethylene) carbonate diol, polytetramethylene carbonate diol, polytrimethylene carbonate diol, poly(1,4-cyclohexanedimethylene carbonate) diol, poly(2-ethyl-2-butyl-trimethylene) carbonate diol, and random / block copolymers thereof.

[0060] The polyisocyanate may be selected from commonly used known isocyanates, such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, hydrogenated MDI, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc. Among these, aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and polymeric diphenylmethane polyisocyanate are more preferably used.

[0061] <Universal hardness of the surface layer> In order to suppress the generation of contaminants, it is effective to prevent cracking or deformation of the toner. For this purpose, it is preferable that the surface layer is flexible. The hardness of the conductive member of the present disclosure is estimated to be 1.0 N / mm at a "universal hardness (at t=1 μm)" at a depth of 1 μm from the surface of the surface layer. 2 More than 7.0N / mm 2 Since the size of the external additives and toner is on the order of submicrons to several microns, it is preferable to control the hardness in the immediate vicinity of the outer surface, which is the surface of the surface layer that comes into contact with the external additives and toner. Specifically, the universal hardness of the surface when the indenter is pressed 1 μm from the outer surface of the surface layer should be 1.0 N / mm 2By setting the universal hardness to 7.0 N / mm or more, it is possible to suppress the occurrence of image density unevenness due to deformation of the charging roller, which occurs when the charging roller and the electrophotographic photosensitive member are in contact with each other in a stationary state for a long period of time. 2 By making the universal hardness equal to or less than 5.0 N / mm, deformation and cracking of the toner can be suppressed, and the absolute amount of irregular toner and finely powdered toner remaining on the photosensitive member can be more reliably suppressed. 2 By doing as follows, the surface layer conforms to and deforms in response to the contaminants, increasing the number of contact points between the convex portions made of conductive particles exposed on the surface of the surface layer and the contaminants, thereby improving the efficiency of electron injection from the convex portions to the contaminants.

[0062] The universal hardness of the surface of the surface layer of the charging roller is measured, for example, using a universal hardness tester (product name: Fischerscope HM2000XYp, manufactured by Fischer Instruments). Universal hardness is a physical property value determined by pressing an indenter into a measurement object while applying a load, and is expressed as "(test load) / (surface area of ​​indenter under test load) (N / mm 2 The universal hardness is calculated as follows: An indenter such as a square pyramid is pressed into the object to be measured while applying a predetermined, relatively small test load, and the surface area in contact with the indenter is calculated from the indentation depth at the time when the indenter reaches a predetermined depth, and the universal hardness is calculated using the above formula.

[0063] <Convex portions of the surface layer derived from the electronic conductive agent> To inject charge into the contaminants, it is preferable for the surface layer to have protrusions originating from the exposed portions of the electronic conductive agent (conductive particles). The size of the protrusions originating from the exposed portions of the conductive particles is preferably 5.0 nm or more and 100.0 nm or less. By making the size 5.0 nm or more, the protrusions can function as starting points for more efficiently injecting charge into the contaminants. Furthermore, by making the size 100.0 nm or less, excessive charge injection into the photoreceptor can be suppressed. The size of the protrusions refers to the average particle diameter 303 (number-average particle diameter) of the conductive particles 301 exposed from the binder resin 302, as shown in Figure 9. The protrusion size is measured using an SEM to capture an image of an arbitrary 2 μm square area, and then the particle diameters of 20 particles randomly selected from the image are measured to determine the arithmetic average particle diameter. In addition, in order to inject charges into the contaminants by utilizing the convex portions derived from the conductive fine particles, it is effective to control the number of convex portions. The number of convex portions derived from the exposed portions of the conductive fine particles is set to an area of ​​2.0 μm in length and 2.0 μm in width (4.0 μm 2 It is preferable that the number of convex portions is 50 or more and 500 or less in the area (region). By making the number 50 or more, the number of convex portions as starting points for injecting charge into the contaminants can be secured. Furthermore, by making the number 500 or less, the injection of charge into the photoreceptor can be suppressed. The number of convex portions can be calculated by taking an image of any 2 μm square region using a scanning electron microscope (SEM) and calculating the number of conductive points from the binarized image.

[0064] Next, a method for exposing conductive particles on the surface of the surface layer will be described. When a surface layer is formed on a conductive layer of a conductive member by a dip coating method, a skin layer is inevitably formed on the outermost surface of the surface layer. Therefore, in order to expose the conductive particles on the surface of the surface layer and create convex portions on the surface of the surface layer through the exposed portions, it is effective to remove the outermost skin layer. For example, ultraviolet treatment, polishing, electrolytic polishing, chemical polishing, ion milling, etc. can be performed to remove the surface skin layer formed by the binder resin and expose the conductive particles on the surface of the surface layer. In the present disclosure, because the hardness of the surface layer is low, ultraviolet treatment can also be performed to sufficiently remove the skin layer and expose the conductive particles on the surface of the surface layer. UV treatment is preferred because it can expose the conductive particles on the surface of the surface layer while minimizing damage to the surface layer compared to polishing methods, etc. The exposed state of the conductive fine particles can be confirmed using an electron force microscope (AFM). A height image is acquired using the tapping mode of the AFM. In this case, the portions originating from the exposed portions of the conductive fine particles are confirmed as convex portions. When a height image is acquired with a skin layer present after dip coating, the convex portions are not confirmed. Furthermore, a phase image is acquired using the tapping mode of the AFM. In this case, there is little phase shift of the conductive fine particles, and due to the difference in hardness between the binder resin and the conductive fine particles, an image with a very large difference in contrast between light and dark is obtained. When a phase image is acquired with a skin layer present after dip coating, there is very little phase difference, resulting in an image with low contrast difference.

[0065] <Roughening particles> The surface layer may contain roughening particles to the extent that the effects of the present disclosure are not impaired. Examples of roughening particles include: organic insulating particles such as acrylic resin, polycarbonate resin, styrene resin, urethane resin, fluororesin, and silicone resin; and inorganic insulating particles such as titanium oxide, silica, alumina, magnesium oxide, strontium titanate, barium titanate, barium sulfate, calcium carbonate, mica, zeolite, and bentonite. In the present disclosure, flexible organic insulating particles are preferably used as roughening particles because they increase the chance of contact with external additives, toner, and other contaminants by deforming the surface layer. These particles may be used alone or in combination of two or more. The number-average particle diameter of the roughening particles is not particularly limited, but is approximately 3 μm or more and 30 μm or less.

[0066] <Ionic conductive agent> The surface layer may contain an ionic conductive agent to the extent that the effects of the present disclosure are not impaired. To transport the charge supplied to the adhering dirt from the conductive layer, the surface layer must contain an electronic conductive agent with good responsiveness. However, an ionic conductive agent with relatively low (slow) responsiveness may also be added as an auxiliary agent. This allows the amount of charge that can be supplied to the dirt on the surface at a given moment to be the sum of the charge instantly transported from the conductive layer by the electronic conductive agent and the charge that left the conductive layer a short time ago and was transported later by the ionic conductive agent. Therefore, when the electronic conductive agent is primarily responsible for charge transport, the possibility of insufficient charge supply is further reduced. The ionic conductive agent is not particularly limited as long as it exhibits ionic conductivity, and examples include the following: Inorganic ionic substances such as lithium perchlorate, sodium perchlorate, and calcium perchlorate; quaternary ammonium salts such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, and tetrabutylammonium perchlorate; inorganic salts of organic acids such as lithium trifluoromethanesulfonate and potassium perfluorobutanesulfonate. These may be used alone or in combination of two or more. Among ionic conductive agents, those with functional groups that readily form bonds with the materials that make up the surface layer are preferred because they are immobilized within the surface layer, making it easier to maintain their properties over the long term. For example, if the surface layer contains urethane bonds, an ionic conductive agent with an OH group is preferred. Even more preferred is an imidazolium structure within the ionic conductive agent's structure. Charge is easily delocalized on the imidazolium ring, making it less likely to cause uneven charge distribution within the structure, which can lead to uniform charge transfer within the surface layer and more uniform charge delivery to contaminants. Because the ionic conductive agent plays a supporting role to the electronic conductive agent, its amount is less than that of the electronic conductive agent that makes up the surface layer, preferably 0.01 to 5.0 parts by weight per 100 parts by weight of the binder resin. It is even more preferred to use an ionic conductive agent with an imidazolium structure within the structure.

[0067] <Other Additives> Other additives may be added to the surface layer as needed, provided that the effects of the present disclosure are not impaired. Examples of additives that may be added include chain extenders, crosslinkers, pigments, silicone additives, and catalysts such as amines and tin complexes. Addition of a silicone additive to the surface layer is particularly preferred because it increases the resistance of the surface layer, provides slipperiness to the surface layer, inhibits charge injection into the photoreceptor, and improves the abrasion resistance of the surface layer.

[0068] <Surface layer thickness> The surface layer preferably has a thickness of 0.1 μm or more and 100 μm or less, and more preferably 1 μm or more and 50 μm or less. The thickness of the surface layer can be measured by cutting out a cross section of the roller with a sharp blade and observing it with an optical microscope or an electron microscope.

[0069] <Volume resistivity of surface layer> The volume resistivity of the surface layer of the charging roller is 1.0 x 10 10 Ω cm or more, 1.0×10 16Ω·cm or less is preferable. When used as a charging roller, it is preferable to set the volume resistivity of the surface layer to a high value. It has been confirmed that when the volume resistivity of the surface layer is low, it is difficult for contaminants to return to the photoreceptor, and the amount of contaminants that accumulate on the charging roller increases. The inventors believe that this suggests that when negatively charged contaminants come into direct contact with the surface layer, especially with binder resin where conductive particles are not exposed on the surface, the negative charge of the contaminants moves to the surface layer side of the charging roller, causing the negative charge of the contaminants to decay. In order to suppress the decay of the negative charge of the contaminants, it is preferable that the surface layer has a high resistance, and for this purpose, the volume resistivity of the surface layer should be set to 1.0 × 10 10 It is necessary to set the resistivity to Ω·cm or more. It has also been confirmed that when the volume resistivity of the surface layer is low, charge is injected from the charging roller into the photosensitive member. This phenomenon becomes more pronounced when the hardness of the surface layer is low, and when there is a difference in peripheral speed between the charging roller and the photosensitive member. During actual image output, the injected charge amount is added to the charge amount due to discharge, so if the injected charge amount is large, it becomes difficult to maintain a stable surface potential of the photosensitive member. The target injected charge amount for maintaining output with stable image density is 50 V or less, and to achieve this, the volume resistivity of the surface layer must be set to 1.0 x 10 12 It is preferable to set it to Ω·cm or more. In addition, if the volume resistivity of the surface layer is high, the discharge of the charging roller becomes unstable. Therefore, the volume resistivity of the surface layer should be set to 1.0 × 10 16The charge injected from the charging roller to the photoreceptor should be less than Ω·cm. The charge injected from the charging roller to the photoreceptor can be estimated, for example, as follows: Under a high-temperature, high-humidity environment (temperature 30°C, relative humidity 80%) where the charge injected increases, a voltage (e.g., DC-500V) is applied to the charging roller under conditions where the charging roller does not discharge. The volume resistivity of the surface layer can be measured using an atomic force microscope (AFM) in conductivity mode. A sheet is cut out from the surface layer of the charging roller using a manipulator, and one side of the surface layer is metallized. A DC power supply is connected to the metallized surface, and voltage is applied. The free end of a cantilever is brought into contact with the other side of the surface layer, and a current image is obtained through the AFM. The current value at 100 randomly selected points on the surface is measured, and the volume resistivity can be calculated from the average current value at the 10 lowest current values ​​measured, the average film thickness, and the cantilever contact area.

[0070] <Method of manufacturing the surface layer> The method for forming the surface layer is not particularly limited, but examples include spraying with a paint in which a solvent is added to the raw material, immersion (dip coating method), and roll coating. The dip coating method is a simple method for forming the surface layer and has excellent production stability. Furthermore, if necessary, additional treatment such as heating may be performed after coating.

[0071] <Use as a developing material> The electroconductive member for electrophotography is also effective when used as a developing member. In a high-speed process, when the conductive member disclosed in Patent Document 1 is used as a developing member, charge transfer from the support to the surface of the conductive member becomes uneven, resulting in variations in the amount of charge imparted to the toner. This makes it difficult to achieve uniform development, and for example, can result in fogged images in which toner with low charge appears in the image. This disclosure makes it possible to maintain a development process with very little variation in the amount of charge on the toner over a long period of time.

[0072] When used as a developing material, the surface layer has a volume resistivity of 1.0 x 10 under an environment of 23°C temperature and 50% relative humidity. 4 ~1.0×10 15 It is characterized by a resistivity of Ωcm. The surface layer has the function of imparting frictional charge to the toner, protecting the surface of the developing member, and suppressing wear and damage to the surface of the developing member. The volume resistivity of the surface layer can be adjusted by adding an electronic conductive agent or an ionic conductive agent to the resin component that serves as the binder. The binder resin functions as a carrier for the electronic conductive agent, ionic conductive agent, filler, and additives.

[0073] As the binder resin component, known resins can be used, and although there are no particular limitations, examples thereof include the following, and one or a combination of two or more of these can be used. Specific examples include polyurethane resins, polyester resins, polyether resins, acrylic resins, epoxy resins, amino resins such as melamine, amide resins, imide resins, amide-imide resins, phenol resins, vinyl resins, silicone resins, fluorine resins, polyalkyleneimine resins, and polycarbonate resins.

[0074] Polyurethane resins are particularly preferred from the viewpoints of film strength and toner charging properties, and among these, thermosetting polyether polyurethane resins, polyester polyurethane resins, and polycarbonate resins are preferably used because they also have flexibility. These thermosetting polyurethane resins are obtained by reacting known polyether polyols, polyester polyols, or polycarbonate polyols with an isocyanate compound.

[0075] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of polyester polyols include the following: Polyester polyols obtained by a condensation reaction between a diol component such as ethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,4-pentanediol, or neopentyl glycol, or a triol component such as trimethylolpropane, and a dicarboxylic acid such as succinic acid, adipic acid, phthalic anhydride, terephthalic acid, or hexahydroxyphthalic acid. Examples of polycarbonate polyols include the following: Polycarbonate polyols obtained by the condensation reaction of a diol component such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 3-methyl-1,5-pentanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene glycol with a dialkyl carbonate such as phosgene or dimethyl carbonate, or a cyclic carbonate such as ethylene carbonate.

[0076] If necessary, these polyol components may be chain-extended in advance with an isocyanate such as 2,4-tolylene diisocyanate (TDI), 1,4-diphenylmethane diisocyanate (MDI), or isophorone diisocyanate (IPDI) to form a prepolymer. The isocyanate compound to be reacted with these polyol components is not particularly limited, and examples thereof include aliphatic polyisocyanates such as ethylene diisocyanate and 1,6-hexamethylene diisocyanate (HDI), alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), cyclohexane 1,3-diisocyanate and cyclohexane 1,4-diisocyanate, aromatic isocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), polymeric diphenylmethane diisocyanate, xylylene diisocyanate and naphthalene diisocyanate, as well as copolymers, isocyanurates, TMP adducts, biurets and block products thereof. Among these, aromatic isocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and polymeric diphenylmethane diisocyanate are more preferably used. The mixing ratio of the isocyanate compound to be reacted with the polyol component is preferably in the range of 1.0 to 2.0, where the ratio of isocyanate groups to hydroxyl groups is 1.0, since this can prevent unreacted components from remaining. When a urethane resin is used as the binder resin for the surface layer, the urethane group concentration is preferably 1.5% or more and 6.5% or less. When a conductive member (developing member) in an electrophotographic image forming apparatus is subjected to a long-term durability test in alternating high-temperature, high-humidity and low-temperature, low-humidity environments, damage to the conductive member surface may occur, resulting in image degradation. The inventors have confirmed through their investigations that the breakdown near the surface of the conductive member occurs when the conductive member is alternately placed in a high-temperature, high-humidity environment and a low-temperature, low-humidity environment, and that the surface layer repeatedly expands and contracts, causing minute cracks near the interface between the surface layer and the conductive layer. It is presumed that these minute cracks are the cause of the breakdown near the surface of the conductive member during long-term durability tests.

[0077] When the urethane group concentration is 1.5% or higher, the interaction between the urethane groups results in high film strength in the surface layer, which is preferable from the perspective of durability. Furthermore, when the urethane group concentration is 6.5% or lower, there are fewer excess urethane groups that act as affinity sites for water molecules. Therefore, even when used alternately in high-temperature, high-humidity and low-temperature, low-humidity environments, damage due to expansion / contraction is unlikely to occur, and high durability is achieved even when used in harsh environments.

[0078] It is particularly preferable that the surface layer contains a urethane resin having a structure of any one of structural formulas (1) to (3), since this provides higher durability even when used in a harsh environment.

[0079] [ka] In structural formulas (1) to (3), R 1 ~R 3 each independently represents a linear or branched divalent hydrocarbon group having 4 to 8 carbon atoms.

[0080] The structures of structural formulas (1) to (3) specifically represent ether structures, ester structures, and carbonate structures with a large number of carbon atoms, respectively. Resins containing these structures have a large number of carbon atoms, so they contain fewer ether bonds, ester bonds, and carbonate bonds per unit weight. This reduces the affinity of the resin with water molecules, allowing the moisture content to be kept low even in high-temperature, high-humidity environments. In particular, it is preferable to react the structural formulas (1) to (3) as polyols with an isocyanate compound to obtain the desired urethane resin. As a result, even when used alternately in high-temperature, high-humidity environments and low-temperature, low-humidity environments, the material is less likely to be damaged by thermal expansion / contraction, ensuring high durability even when used in harsh environments.

[0081] Examples of polyols having the structure of structural formula (1) include polytetramethylene glycol, polyhexamethylene glycol, polyoctamethylene glycol, and ring-opening copolymer polyols of tetrahydrofuran and 3-methyltetrahydrofuran.

[0082] Examples of polyols having the structure of structural formula (2) include polyester polyols obtained by a condensation reaction between a diol component such as 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 3-methyl-1,4-pentanediol, or neopentyl glycol, or a triol component such as trimethylolpropane, and a dicarboxylic acid such as adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid.

[0083] Examples of polyols having the structure of structural formula (3) include polycarbonate polyols obtained by a condensation reaction between a diol component such as 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 3-methyl-1,4-pentanediol, or neopentyl glycol and a dialkyl carbonate such as phosgene or dimethyl carbonate.

[0084] In addition to the heat curing reaction using an isocyanate compound, a compound having a vinyl group or an acroyl group introduced at the end instead of the polyol can also be cured with ultraviolet light or an electron beam. In a curing system using ultraviolet light or an electron beam, the curing reaction can be completed in a shorter time than in a curing system using an isocyanate.

[0085] As described above, the surface layer contains an electronic conductive agent. Among these, carbon black is preferred because it is relatively easy to obtain and provides good conductivity. When carbon black is used as the electronic conductive agent, it is preferable to mix 2 to 50 parts by mass of carbon black with 100 parts by mass of binder resin.

[0086] As the conductive agent, an ionic conductive agent may be used in combination with the electronic conductive agent. Examples of ionic conductive agents that can be used include quaternary ammonium salts, imidazolium salts, pyridinium salts, sulfonium salts, and phosphonium salts. Examples of anions of ionic conductive agents include perchlorate anions, fluoroalkylsulfonylimide anions, fluorosulfonylimide anions, trifluoromethanesulfonate anions, tetrafluoroborate anions, hexafluorophosphate anions, dicyanamide anions, thiocyanate anions, and dicyanosulfonylimide anions. At least one of these can be used.

[0087] The surface layer may contain a non-conductive filler such as silica, quartz powder, titanium oxide, zinc oxide, or calcium carbonate, as needed. When the surface layer is formed by coating with a paint, the non-conductive filler can be added to act as a film-forming aid. The content of the non-conductive filler is preferably 10% by mass or more and 30% by mass or less, based on 100 parts by mass of the resin components that form the surface layer, i.e., the combined components of the binder resin and the resin having the structure represented by structural formula (1).

[0088] The conductive member may have an appropriate surface roughness as needed. When the conductive member is a developing roller or a developing sleeve, the surface roughness is preferably in the ten-point mean roughness (Rz) range of 2.0 to 10.0 μm, and particularly preferably in the range of 2.0 to 4.5 μm. When the conductive member is a developing blade, the surface roughness is preferably in the ten-point mean roughness (Rz) range of 0.0 to 6.0 μm, and particularly preferably in the range of 0.0 to 1.5 μm. When the surface roughness is within this range, both uniform contact with the toner and an appropriate amount of toner transport are achieved, making it easier to uniformly supply charge to the toner. Methods for providing surface roughness to the conductive member include adding fine particles to the surface layer, polishing, mold transfer, and laser treatment. When fine particles are added to control the roughness, the fine particles preferably have a volume average particle size of 3 to 20 μm. Furthermore, the amount of particles added to the surface layer is preferably 1 to 50 parts by mass per 100 parts by mass of the resin solid content of the surface layer. As the fine particles for controlling the roughness, fine particles of polyurethane resin, polyester resin, polyether resin, polyamide resin, acrylic resin, and phenol resin can be used.

[0089] When the conductive member is in the form of a roller, the conductive layer may be formed by the same method as that for producing a charging roller. When the conductive member is in the shape of a blade, the molding method includes molding, injection molding, extrusion molding, and centrifugal molding.

[0090] The method for forming the surface layer is not particularly limited, and examples thereof include spraying, dipping, and roll coating with a paint. The dip coating method in which a paint is allowed to overflow from the upper end of a dipping tank, as described in JP-A-57-5047, is a simple method for forming a surface layer and has excellent production stability.

[0091] <Process cartridge> FIG. 7 is a schematic cross-sectional view of an electrophotographic process cartridge 100 including a conductive member according to an embodiment of the present disclosure as a charging roller. This process cartridge integrates a developing device and a charging device and is configured to be detachably attached to the main body of an electrophotographic image forming apparatus. The developing device integrates at least a developing roller 103, a toner container 106, and toner 109, and may optionally include a toner supply roller 104, a developing blade 108, and an agitating blade 110. The charging device integrates at least a photosensitive drum 101 and a charging roller 102, and may optionally include a cleaning blade 105 and a waste toner container 107. Voltages are applied to the charging roller 102, the developing roller 103, the toner supply roller 104, and the developing blade 108. The conductive member according to an embodiment of the present disclosure can also be used as a developing roller, a developing blade, or a toner supply roller.

[0092] <Electrophotographic image forming apparatus> FIG. 8 is a schematic diagram of an electrophotographic image forming apparatus 200 using a conductive member according to an embodiment of the present disclosure as a charging roller. This apparatus is a color electrophotographic apparatus in which the process cartridge 100 is detachably mounted. Each process cartridge uses toner of one of the colors: black, magenta, yellow, and cyan. The photosensitive drum 201 rotates in the direction of the arrow and is uniformly charged by a charging roller 202 to which a voltage is applied from a charging bias power supply. An electrostatic latent image is formed on the surface of the photosensitive drum 201 by exposure light 211. Meanwhile, toner 209 stored in a toner container 206 is supplied to a toner supply roller 204 by an agitating blade 210 and transported onto a developing roller 203. The developing blade 208, which is in contact with the developing roller 203, uniformly coats the surface of the developing roller 203 with toner 209, and imparts an electric charge to the toner 209 through frictional charging. The electrostatic latent image is developed by the toner 209 transported by the developing roller 203, which is in contact with the photosensitive drum 101, and is visualized as a toner image. The visualized toner image on the photosensitive drum is transferred by a primary transfer roller 212, to which a voltage is applied by a primary transfer bias power supply, onto an intermediate transfer belt 215, which is supported and driven by a tension roller 213 and an intermediate transfer belt drive roller 214. The toner images of each color are sequentially superimposed to form a color image on the intermediate transfer belt. A transfer material 219 is fed into the device by a paper feed roller and transported between an intermediate transfer belt 215 and a secondary transfer roller 216. A voltage is applied to the secondary transfer roller 216 from a secondary transfer bias power supply, and the secondary transfer roller 216 transfers the color image on the intermediate transfer belt 215 onto the transfer material 219. The transfer material 219 onto which the color image has been transferred is fixed by a fixing device 218, and is then discarded outside the device, completing the printing operation. Meanwhile, the toner remaining on the photosensitive drum without being transferred is scraped off by a cleaning blade 205 and stored in a waste toner container 207, and the above-mentioned process is repeated for the cleaned photosensitive drum 201. In addition, the toner remaining on the primary transfer belt without being transferred is also scraped off by a cleaning device 217. Although a color electrophotographic device is shown as an example, in a monochrome electrophotographic device (not shown), the process cartridge uses only black toner. A monochrome image is formed directly on the transfer material by the process cartridge and primary transfer roller (no secondary transfer roller) without using an intermediate transfer belt. The image is then fixed by a fixing device, and the printing operation is completed when the paper is ejected from the device. [Example]

[0093] The raw materials used in the production of electrophotographic conductive members according to Examples and Comparative Examples are shown below.

[0094] <nbr> NBR (1) (product name: JSR NBR N230SV, acrylonitrile content: 35%, Mooney viscosity ML (1+4) 100°C: 32, SP value: 20.0 (J / cm 3 ) 0.5 , manufactured by JSR, abbreviation: N230SV) NBR (2) (product name: JSR NBR N215SL, acrylonitrile content: 48%, Mooney viscosity ML (1+4) 100°C: 45, SP value: 21.7 (J / cm 3 ) 0.5 , manufactured by JSR Corporation, abbreviated name: N215SL) NBR (3) (trade name: Nipol DN401LL, acrylonitrile content: 18.0%, Mooney viscosity ML (1+4) 100°C: 32, SP value: 17.4 (J / cm 3 ) 0.5 , manufactured by Zeon Corporation, abbreviated name: DN401LL)

[0095] <Isoprene rubber IR> Isoprene rubber (trade name: Nipol 2200L, Mooney viscosity ML (1+4) at 100°C: 70, SP value: 16.5 (J / cm 3 ) 0.5 , manufactured by Zeon Corporation, abbreviated name: IR2200L)

[0096] <Butadiene rubber BR> Butadiene rubber (1) (trade name: UBEPOL BR130B, Mooney viscosity ML (1+4) 100°C: 29, SP value: 16.8 (J / cm 3 ) 0.5 , manufactured by Ube Industries, abbreviated name: BR130B) Butadiene rubber (2) (trade name: UBEPOL BR150B, Mooney viscosity ML (1+4) 100°C: 40, SP value: 16.8 (J / cm 3 ) 0.5 , manufactured by Ube Industries, abbreviated name: BR150B)

[0097] <sbr> SBR (1) (product name: Asaprene 303, styrene content: 46%, Mooney viscosity ML (1+4) 100°C: 45, SP value: 17.4 (J / cm 3 ) 0.5 , manufactured by Asahi Kasei Corporation, abbreviation: A303) SBR (2) (trade name: Tufden 2003, styrene content: 25%, Mooney viscosity ML (1+4) 100°C: 33, SP value: 17.0 (J / cm 3 ) 0.5 , manufactured by Asahi Kasei Corporation, abbreviation: T2003) SBR (3) (trade name: Tufden 2100R, styrene content: 25%, Mooney viscosity ML (1+4) 100°C: 78, SP value: 17.0 (J / cm 3 ) 0.5 , manufactured by Asahi Kasei Corporation, abbreviated name: T2100R) SBR (4) (product name: Tufden 2000R, styrene content: 25%, Mooney viscosity ML (1+4) 100°C: 45SP value: 17.0 (J / cm 3 ) 0.5 , manufactured by Asahi Kasei Corporation, abbreviated name: T2000R) SBR (5) (trade name: Tufuden 1000, styrene content: 18%, Mooney viscosity ML (1+4) 100°C: 45, SP value: 16.8 (J / cm 3 ) 0.5 , manufactured by Asahi Kasei Corporation, abbreviated name: T1000)

[0098] <Chloroprene rubber (CR)> Chloroprene rubber (product name: SKYPRENE B31, Mooney viscosity ML (1+4) at 100°C: 40, SP value: 17.4 (J / cm 3 ) 0.5 , manufactured by Tosoh Corporation, abbreviation: CR B31)

[0099] <epdm> EPDM (product name: Esprene 505A, Mooney viscosity ML (1+4) 100°C: 47, SP value: 16.0 (J / cm 3 ) 0.5 , manufactured by Sumitomo Chemical Co., Ltd., abbreviation: E505A)

[0100] <Conductive particles> Carbon black (1) (product name: Toka Black #5500, DBP absorption capacity: 155 cm 3 / 100g, manufactured by Tokai Carbon Co., Ltd., abbreviation: #5500) Carbon black (2) (product name: Toka Black #7360SB, DBP absorption capacity: 87 cm 3 / 100g, manufactured by Tokai Carbon Co., Ltd., abbreviation: #7360) Carbon black (3) (product name: Toka Black #7270SB, DBP absorption capacity: 62 cm 3 / 100g, manufactured by Tokai Carbon Co., Ltd., abbreviation: #7270) Carbon black (4) (product name: Raven 1170, DBP absorption capacity: 55 cm 3 / 100g, manufactured by Columbia Chemical Co., abbreviation: R1170) Carbon black (5) (product name: MA100, DBP absorption capacity: 95 cm 3 / 100g, manufactured by Mitsubishi Chemical Corporation, abbreviated name: MA100)

[0101] <Vulcanizing agent> Vulcanizing agent (1) (product name: SULFAX PMC, sulfur content 97.5%, manufactured by Tsurumi Chemical Industry Co., Ltd., abbreviated name: sulfur)

[0102] <Vulcanization accelerator> Vulcanization accelerator (1) (trade name: Suncerer TBZTD, tetrabenzyl thiuram disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., abbreviation: TBZTD) Vulcanization accelerator (2) (trade name: Noccela TBT, tetrabutylthiuram disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., abbreviation: TBT) Vulcanization accelerator (3) (trade name: Noccela EP-60, vulcanization accelerator mixture, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., abbreviation: EP-60) Vulcanization accelerator (4) (trade name: SANTOCURE-TBSI, Nt-butyl-2-benzothiazole sulfenimide, manufactured by FLEXSYS, abbreviation: TBSI) Vulcanization accelerator (5) (trade name: Sancerer 22-C, 2-imidazoline-2-thiol or 2-imidazolinethione, manufactured by Sanshin Chemical Industry Co., Ltd., abbreviated as Sancerer 22) Vulcanization accelerator (6) (trade name: Noccela TRA, dipentamethylene thiuram tetrasulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., abbreviation: TRA)

[0103] <Filler> Filler (1) (trade name: Nanox #30, calcium carbonate, manufactured by Maruo Calcium Co., Ltd., abbreviation: #30)

[0104] Conductive members according to examples and comparative examples will be described below, but the technical scope of the present disclosure is not limited to the configurations embodied in the examples.

[0105] <Production of Conductive Roller 1> [1-1. Preparation of domain-forming rubber composition (CMB)] A domain-forming rubber composition (CMB) was obtained by mixing the materials in the types and amounts shown in Table 1 in a pressure kneader. The mixing conditions were a filling rate of 70 vol%, a blade rotation speed of 30 rpm, and 18 minutes.

[0106] [Table 1]

[0107] [1-2. Preparation of matrix-forming rubber composition (MRC)] A matrix-forming rubber composition (MRC) was obtained by mixing the materials in the types and amounts shown in Table 2 in a pressure kneader. The mixing conditions were a filling rate of 70 vol%, a blade rotation speed of 30 rpm, and 18 minutes.

[0108] [Table 2]

[0109] [1-3. Preparation of Rubber Composition 1 for Forming Conductive Layer] The types and amounts of materials shown in Table 3 were mixed using an open roll to prepare a rubber composition for molding a conductive member. The mixer used was an open roll with a roll diameter of 12 inches. The mixing conditions were a front roll rotation speed of 10 rpm, a rear roll rotation speed of 8 rpm, a roll gap of 2 mm, and a total of 20 left and right turns, followed by 10 thin passes with a roll gap of 1.0 mm.

[0110] [Table 3]

[0111] [1-4. Formation of conductive layer] A round bar with a total length of 252 mm and an outer diameter of 6 mm was prepared. The surface of the free-cutting steel bar was electrolessly nickel-plated. Next, an adhesive (product name: Metalock U-20, manufactured by Toyo Kagaku Kenkyusho) was applied using a roll coater over the entire circumference of the round bar, excluding 11 mm at each end, over a range of 230 mm, to prepare a support. Next, a die with an inner diameter of 10.5 mm was attached to the tip of a crosshead extruder having a support feeding mechanism and an unvulcanized rubber roller discharge mechanism, and the temperatures of the extruder and crosshead were adjusted to 100°C, and the conveying speed of the conductive support was adjusted to 60 mm / sec. Under these conditions, the rubber composition 1 for forming a conductive layer prepared in [1-3] was fed from the extruder, and the outer periphery of the support was coated with the rubber composition 1 for forming a conductive layer in the crosshead, thereby obtaining an unvulcanized rubber roller. Next, the unvulcanized rubber roller was placed in a hot air vulcanizing furnace and heated at 170°C for 60 minutes to vulcanize the layer of unvulcanized rubber composition, resulting in a roller with a conductive resin layer formed on the outer periphery of the support. After that, 10 mm of each end of the conductive resin layer was cut off, leaving a longitudinal length of 232 mm for the conductive resin layer portion. Finally, the surface of the conductive resin layer was polished with a grindstone, thereby producing a conductive roller 1 having a conductive layer 1 with a diameter of 9.65 mm at positions 90 mm from the center to both ends and a central diameter of 9.7 mm.

[0112] <Production of Conductive Rollers 2 to 28> [2-1. Preparation of domain-forming rubber composition] [2-2. Preparation of rubber composition for matrix formation] The domain-forming rubber composition and matrix-forming rubber composition for forming each of the conductive layers 2 to 28 of the conductive rollers 2 to 28 were prepared in the same manner as in [1-1] and [1-2] above, except that the materials shown in Tables 4-1 and 4-2 were used. [2-3. Preparation of Rubber Compositions 2 to 28 for Forming Conductive Layer] Rubber compositions 2 to 28 for forming a conductive layer were prepared in the same manner as rubber composition 1 for forming a conductive layer, except that the CMB shown in Table 4-1, the MRC shown in Table 4-2, and other materials were blended as shown in Table 4-3. [2-4. Preparation of conductive rollers 2 to 28] Conductive rollers 2 to 28 were produced in the same manner as in "1-4" above, except that conductive layer-forming rubber compositions 2 to 28 were used.

[0113] [Table 4-1]

[0114] [Table 4-2]

[0115] [Table 4-3]

[0116] In Tables 4-1 to 4-3, DBP represents the amount of DBP absorbed, and the unit is (cm 3 / 100g). The Mooney viscosity values ​​in the table for raw rubber are the catalog values ​​of each company. The value for CMB for domains is Mooney viscosity ML (1+4) based on JIS K6300-1:2013, measured at the rubber temperature when all the materials that make up the CMB for domains are being mixed. The unit of SP value is (J / cm 3 ) 0.5 is.

[0117] Regarding Mooney viscosity, the values ​​for raw rubber are the catalog values ​​of each company. The MRC value is Mooney viscosity ML (1+4) based on JIS K6300-1:2013, and is measured at the rubber temperature when all the materials that make up the MRC are being mixed. The unit of SP value is (J / cm 3 ) 0.5 and the SP value difference is the absolute value of the difference between the second rubber in the CMB and the first rubber in the MRC.

[0118] <3. Preparation of coating liquid for surface layer> [3-1. Preparation of Coating Solution 1 for Surface Layer] A surface layer coating solution 1 for forming the surface layer 1 was prepared as follows. Under a nitrogen atmosphere, 27 parts by mass of polymeric MDI (trade name: Millionate MR200, manufactured by Nippon Polyurethane Industry Co., Ltd.) was slowly added dropwise to 100 parts by mass of polyester polyol (trade name: P3010, manufactured by Kuraray Co., Ltd.) in a reaction vessel while maintaining the temperature inside the reaction vessel at 65°C. After the addition was completed, the mixture was allowed to react at 65°C for 2 hours. The resulting reaction mixture was cooled to room temperature to obtain an isocyanate-terminated prepolymer P-1 having an isocyanate group content of 4.3%. 54.9 parts by mass of isocyanate-terminated prepolymer P-1 was dissolved in methyl ethyl ketone (MEK) with 41.52 parts by mass of polyester polyol (trade name: P2010, manufactured by Kuraray Co., Ltd.) and 30 parts by mass of carbon black (trade name: MA230, manufactured by Mitsubishi Chemical Corporation, number-average particle diameter: 30 nm) to obtain a solids content of 27% by mass. Mixed solution 1 was prepared as described above. 270 g of mixed solution 1 and 200 g of glass beads with an average particle size of 0.8 mm were placed in a 450 mL glass bottle and dispersed for 12 hours using a paint shaker disperser. After dispersion, 15 parts by mass of urethane particles with an average particle size of 7.0 μm (trade name: Dimic Beads UCN-5070D, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) were added. The mixture was then further dispersed for 15 minutes, and the glass beads were removed to obtain surface layer coating solution 1.

[0119] [3-2. Preparation of Surface Layer Coating Solutions 2 to 16, C1 and C2] Surface layer coating solutions 2 to 16, C1 and C2 were prepared in the same manner as surface layer coating solution 1, except that the materials shown in Table 5 were used in the blending ratios shown in Table 5. Surface layer coating solutions 12 and 13 further contained an ionic conductive agent in addition to the electronic conductive agent. Surface layer coating solutions 14 and 16 will be described in detail in Examples 41 and 45. In the table, "phr" represents the amount blended relative to 100 parts by mass of the rubber component.

[0120] [Table 5]

[0121] The abbreviations for polyols, isocyanates, roughening particles, silicone additives, and ionic conductive agents in Table 5 are as follows: A-1: Polyester polyol (product name: P2010, manufactured by Kuraray Co., Ltd.) A-2: Polycarbonate (product name: T5652, manufactured by Asahi Kasei Chemicals Corporation) A-3: Acrylic polyol (trade name: DC2016, manufactured by Daicel Chemical Industries, Ltd.) B-1: Polyester polyol / polymeric MDI (product name: P3010, manufactured by Kuraray Co., Ltd. / product name: Millionate MR200, manufactured by Nippon Polyurethane Industry Co., Ltd.) B-2: Polycarbonate polyol / polymeric MDI (product name: T5652, manufactured by Asahi Kasei Chemicals; product name: Millionate MR200, manufactured by Nippon Polyurethane Industry Co., Ltd.) B-3: Isocyanate A / Isocyanate B = 4:3 (Trade name: Bestanate B1370, manufactured by Degussa Corporation / Trade name: Duranate TPA-880E, manufactured by Asahi Kasei Chemicals Corporation) C-1: Urethane particles (product name: Dimic Beads UCN-5070D, average particle size 7.0 μm, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) CB: Conductive carbon black (product name: MA230, manufactured by Mitsubishi Chemical Corporation, number average particle diameter 30 nm) Tin oxide: Sb-doped SnO2 (product name: SN-100P, manufactured by Ishihara Sangyo Kaisha, Ltd., particle size 10 to 30 nm (primary particle size)) D-1: Modified dimethyl silicone oil (product name: SH-28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) E-1: Quaternary ammonium salt (product name: Adeka Cizer LV70, manufactured by ADEKA Corporation) E-2: Synthetic product (described in Example 41 below)

[0122] Example 1 The conductive roller 1 was oriented with its longitudinal direction in the vertical direction, and its upper end was gripped and immersed (dipped) in the surface layer coating liquid 1 and then pulled up. The immersion time for the dip coating was 9 seconds, and the roller pull-up speed was adjusted so that the initial speed was 20 mm / sec and the final speed was 2 mm / sec, with the speed varying linearly with time between 20 mm / sec and 2 mm / sec. After coating, the roller was air-dried for 30 minutes at 23°C. Next, the roller was dried in a hot air circulation dryer at 80°C for 1 hour and then at 160°C for 1 hour, forming a dried film of the surface layer coating liquid 1 on the conductive layer.

[0123] Furthermore, the cumulative amount of ultraviolet light with a wavelength of 254 nm is 9000 mJ / cm 2 The surface of the dry film was irradiated with ultraviolet light so that the outermost skin layer of the dry film was removed, and a surface layer was formed in which the conductive particles (conductive carbon black) in the dry film were exposed to the outer surface. A low-pressure mercury lamp (manufactured by Toshiba Lighting & Technology Corporation) was used as the ultraviolet light source. In this way, an electrophotographic roller 1 according to Example 1 was produced.

[0124] <4. Characterization> The obtained electrophotographic roller 1 was subjected to the following evaluations. <4-1. Evaluation of electrophotographic roller characteristics> <Method for measuring impedance of conductive materials> The impedance of the electrophotographic roller was measured by the following method. First, as a pretreatment, platinum was vapor-deposited onto the outer surface of the electrophotographic roller while the roller was rotating to create a measurement electrode. Masking tape was used to create a 1.5 cm wide, uniform electrode in the circumferential direction. By forming this electrode, the contribution of the contact area between the measurement electrode and the conductive member, due to the surface roughness of the conductive member, can be minimized. Next, an aluminum sheet was tightly wrapped around the electrode to form the measurement sample shown in Figures 3A and 3B. An impedance measuring device (product name: Solartron 126096W, manufactured by Toyo Corporation) was then connected from the aluminum sheet to the measurement electrode and to the support body. Impedance was measured at a temperature of 23°C, a relative humidity of 50%, an oscillating voltage of 1 Vpp, and a frequency of 1.0 Hz to obtain the absolute value of impedance. The conductive member (longitudinal length: 230 mm) was divided into five equal regions in the longitudinal direction, and measurement electrodes were formed at five points in each region (one at a time), and the above measurement was performed. The average value was taken as the impedance of the conductive member.

[0125] <4-2 Evaluation of surface layer characteristics> <Measurement of surface layer thickness> The thickness of the surface layer was measured by observing the cross section of the surface layer at nine locations (three in the axial direction and three in the circumferential direction) using an optical microscope or an electron microscope, and the average value was taken as the "thickness" of the surface layer. The evaluation results are shown in Table 6.

[0126] <Measurement of universal hardness of surface layer> The universal hardness at a depth of 1 μm from the surface of the surface layer was measured using a universal hardness tester. An ultra-microhardness tester (product name: FISCHERSCOPE HM-2000, manufactured by Helmut Fischer GmbH) was used for the measurement. The specific measurement conditions are shown below. Measurement indenter: Vickers indenter (face angle 136, Young's modulus 1140, Poisson's ratio 0.07, indenter material: diamond) Measurement environment: Temperature 23°C, relative humidity 50% Maximum test load: 1.0 mN Loading conditions: The load was applied in proportion to time, at a rate that reached the maximum test load in 30 seconds. In this evaluation, the universal hardness was calculated using the load F when the indenter was pressed 1 μm deep from the surface of the surface layer and the contact area A between the indenter and the surface layer at that time, according to the following formula (1): Calculation formula (1) Universal hardness (N / mm 2 )=F / A

[0127] <Measurement of volume resistivity (Ω·cm) of the surface layer> The volume resistivity of the surface layer was measured using an atomic force microscope (AFM) (product name: Q-scope250, Quesant) in conductivity mode. First, the surface layer of the developing roller was cut into a sheet 2 mm wide and 2 mm long using a manipulator, and platinum was vapor-deposited on one side of the surface layer. Next, a DC power supply (product name: 6614C, Agilent) was connected to the platinum-deposited surface and 10 V was applied. The free end of a cantilever was contacted with the other side of the surface layer, and a current image was obtained through the AFM body. This measurement was performed at 100 randomly selected locations across the entire surface layer, and the "volume resistivity" was calculated from the average current value of the top 10 lowest current values ​​and the average film thickness of the surface layer. The measurement conditions are as follows: Measurement mode: contact Cantilever: CSC17 Measurement range: 10nm x 10nm Scan rate: 4Hz Applied voltage: 10V

[0128] <Measurement of protrusions resulting from exposed areas of the electronic conductive agent on the surface of the surface layer> The method for measuring the number of protrusions resulting from exposed portions of the electronic conductive agent particles on the surface of the surface layer is as follows. First, a sample including the surface layer and the elastic layer was cut out from the charging roller. Platinum was vapor-deposited on the surface of the sample corresponding to the outer surface of the surface layer. Next, observation areas measuring 2.0 μm in length and 2.0 μm in width were placed at five random locations on the platinum-deposited surface of the sample. Each observation area was observed at 40,000x magnification using a scanning electron microscope (SEM) (product name: S-4800, manufactured by Hitachi High-Technologies Corporation), and five SEM images were obtained. Each of the SEM images was converted to an 8-bit grayscale using image processing software (product name: ImageProPlus, manufactured by Media Cybernetics) to obtain a monochrome image with 256 gradations. Next, the image was inverted so that protrusions resulting from exposed portions of the electronic conductive agent in the monochrome image appeared white. A binarization threshold was set for the brightness distribution of the image based on the algorithm of Otsu's discriminant analysis method, and a binarized image was obtained. The number of convex portions was calculated from the obtained binarized image, and the average value of the numbers of convex portions calculated from the five SEM images was taken as the number of convex portions caused by the exposed portions of the electronic conductive agent of the conductive member.

[0129] <Analysis of urethane resin in the surface layer> The analysis of the urethane resin in the surface layer (urethane group concentration, partial structure) was performed using FT-IR and 1 H-NMR was used.

[0130] <4-3 Characterization of the conductive layer> <(1) Confirmation of matrix-domain structure> The presence of a matrix-domain structure in the conductive layer was confirmed by the following method. A slice (500 μm thick) was cut using a razor so that a cross section perpendicular to the longitudinal direction of the conductive layer could be observed. Platinum was then vapor-deposited on the surface of the slice corresponding to the cross section of the conductive layer. The platinum-deposited surface of the slice was observed at 1000x magnification using a scanning electron microscope (SEM) (product name: S-4800, manufactured by Hitachi High-Technologies Corporation) to obtain an SEM image. When a structure in which multiple domains were dispersed in a matrix and the matrix was interconnected was confirmed in the SEM image, the matrix-domain structure was judged to be "present."

[0131] <(2) Measurement of the maximum Feret diameter, perimeter, and envelope perimeter of the domain> The maximum Feret diameter, perimeter, envelope perimeter, and number of domains were measured as follows: First, when the longitudinal length is L, samples (thickness 1 μm) including a cross section of the conductive layer in the entire thickness direction as shown in FIG. 6B were cut out from an electrophotographic roller using a microtome (trade name: Leica EM FCS, manufactured by Leica Microsystems) at three locations: the center of the conductive layer in the longitudinal direction, and L / 4 from both ends of the conductive layer toward the center. For each of the three samples obtained, platinum was vapor-deposited on a surface corresponding to a cross section of the conductive layer in the full thickness direction. The platinum-deposited surface was then photographed at 5000x magnification using a scanning electron microscope (product name: S-4800, manufactured by Hitachi High-Technologies Corporation) to obtain SEM images. Each of the obtained SEM images was converted to 8-bit grayscale using image processing software (product name: ImageProPlus, manufactured by Media Cybernetics) to obtain a 256-level monochrome image. The image was then inverted to white so that domains within the monochrome image became white. A binarization threshold was set for the image brightness distribution based on the Otsu discriminant analysis algorithm, and a binarized image was obtained. For the obtained binarized image, square observation areas measuring 15 μm on a side were placed at three arbitrary locations within a thickness range of 0.1T to 0.9T from the outer surface of the conductive layer (the surface opposite the surface facing the support), where T is the thickness of the conductive layer. Then, for 50 domains arbitrarily selected from the domains present in the observation region, the maximum Feret's diameter, perimeter, and envelope perimeter were calculated using the counting function of the image processing software.

[0132] The A / B value was calculated using the perimeter and envelope perimeter calculated for each domain observed in each observation area.The percentage of domains that satisfied requirement (2) was then calculated.

[0133] <(3) Measurement of matrix volume resistivity> The volume resistivity of the matrix was measured using a scanning probe microscope (SPM) (product name: Q-Scope 250, manufactured by Quesant Instrument Corporation) in contact mode as follows: The measurement environment was a temperature of 23°C and a relative humidity of 50%. First, a sample was cut out from the conductive layer in the same manner as in (2) above. Next, the sample was placed on the surface of a metal plate, with one side of the sample corresponding to the cross section of the elastic layer in contact with the surface of the metal plate. Then, the cantilever of an SPM was brought into contact with the portion of the sample opposite the side in contact with the metal plate, corresponding to the matrix. A voltage of 50 V was then applied to the cantilever, and the current value was measured. The surface shape of the measurement piece was also measured with the SPM, and the thickness of the measurement point was calculated from the obtained height profile. The volume resistivity of the measurement point was calculated from the thickness and current value of the measurement point. The measurements were carried out at three arbitrary points in the matrix portion of the sample in a region corresponding to a thickness region of 0.1T to 0.9T depth from the outer surface of the conductive layer (the surface opposite to the surface facing the support), where T is the thickness of the conductive layer. The arithmetic mean value of the volume resistivity calculated from the measurement results at a total of nine points obtained from each sample was taken as the volume resistivity of the matrix of the conductive member to be measured.

[0134] The measurement positions were three arbitrary positions in the matrix portion of each slice in a thickness region from the outer surface to a depth of 0.1T to 0.9T, where T is the thickness of the conductive layer, for a total of nine positions. The average value was taken as the volume resistivity of the matrix.

[0135] <(4) Measurement method for DBP absorption of carbon black> The DBP absorption amount of carbon black was measured in accordance with Japanese Industrial Standards (JIS) K 6217. Note that the value listed in the catalogue of the carbon black can also be used.

[0136] <(5) Methods for measuring the ratio of the cross-sectional area of ​​the conductive particles contained in a domain to the cross-sectional area of ​​the domain, the arithmetic mean distance Dc between conductive carbon black particles in a domain, the standard deviation σm, and the coefficient of variation σm / Dc> The ratio of the cross-sectional area of ​​the conductive particles contained in a domain to the cross-sectional area of ​​the domain, the arithmetic mean distance Dc between conductive carbon black particles, the standard deviation σm, and the coefficient of variation σm / Dc were measured as follows. First, a portion of the platinum-deposited surface of the sample prepared in (2) above, corresponding to the square observation area with sides of 15 μm in the binarized image used in the evaluation in (2) above, was photographed at 20,000x magnification using a scanning electron microscope (SEM) (product name: S-4800, manufactured by Hitachi High-Technologies Corporation) to obtain a new SEM image. The SEM image was converted to 8-bit grayscale using an image analyzer (product name: LUZEX-AP, manufactured by Nireco Corporation) to obtain a monochrome image with 256 gradations. Next, the image was inverted to make the domains in the monochrome image white, and a binarization threshold was set for the brightness distribution of the image based on the algorithm of Otsu's discriminant analysis method to obtain a binarized image. Next, from the binarized image, the inter-wall distance Ci of the carbon black within each domain observed in (2) above was calculated. The arithmetic mean inter-wall distance C of the carbon black within each domain was then calculated. Furthermore, the cross-sectional area of ​​the domain and the cross-sectional area of ​​the carbon black in the domain were calculated, and from these results, the ratio (number %) of the number of domains satisfying requirement (1) and the ratio (number %) of the number of domains satisfying requirements (1) and (2) to the total number of observed domains were calculated. Furthermore, the standard deviation σm was calculated from the distance between the conductive carbon black walls in the obtained domain and its arithmetic mean C. The standard deviation σm was then divided by the arithmetic mean C to calculate the coefficient of variation σm / C. For domains satisfying requirements (1) and (2), the arithmetic mean wall-to-wall distance C of the carbon black, the coefficient of variation σm / C, and the arithmetic mean value of the ratio of the cross-sectional area of ​​the carbon black to the cross-sectional area of ​​the domain were calculated. Furthermore, for domains satisfying requirements (1) and (2), the arithmetic mean value of A / B and the arithmetic mean value of the maximum Feret diameter were calculated. The results are shown in Table 6-2.

[0137] <SP value of rubber that makes up the matrix and domain> The SP value can be measured using a conventional swelling method. The rubbers that make up the matrix and domains are each separated using a manipulator or similar tool and immersed in solvents with different SP values, and the degree of swelling is measured from the change in weight of the rubber. The Hansen solubility parameter (HSP) can be calculated by analyzing the swelling value for each solvent. Accurate calculations are also possible by creating a calibration curve using materials with known SP values. This known SP value can also be the catalog value from the material manufacturer. The SP difference, obtained using the SP values ​​of the rubbers that make up the matrix and domains, is calculated and converted into an absolute value.

[0138] <5. Evaluation as a charging member> The characteristics of the electrophotographic roller 1 were evaluated when it was used as a charging member. <Toner charge amount evaluation> When the electrophotographic roller 1 was used as a charging roller, the negative charge supplying ability to contaminant components (contaminant components such as transfer residual toner and external additives) was evaluated as follows. A laser printer (product name: HP LaserJet Pro M203dw, manufactured by HP) was prepared as the electrophotographic image forming apparatus. The motor of this laser printer was modified so that the process speed was 1.2 times faster than normal. Furthermore, an external power source was connected to apply voltage to the charging roller, and the printer was modified so that voltage was not applied directly to the charging roller from the main body. Furthermore, the process cartridge for the laser printer was modified by removing the cleaning blade for the charging roller, the developing container that contacts the photosensitive drum, and the transfer roller. The laser printer and process cartridge were left in a low-temperature, low-humidity environment (temperature 15°C, relative humidity 10%) for 48 hours. The process cartridge was then loaded into the laser printer. The following evaluations were then performed in the low-temperature, low-humidity environment. In a low-temperature, low-humidity environment, charge injection from the electrophotographic member to the toner is unlikely to occur. By performing the following evaluations in such an environment, the ability of the electrophotographic member to inject charge into the toner can be more accurately evaluated. First, the main body was stopped midway through the image forming process of outputting one solid black image under normal image output conditions, and a state was formed in which the entire circumference of the photosensitive drum was covered with a toner layer. Next, the process cartridge in which the entire circumference of the photosensitive drum was covered with a toner layer was removed from the main body. The charging roller of this process cartridge was removed, and the electrophotographic roller 1 was installed as the charging roller. This process cartridge was installed in the main body. An image forming process was then carried out in which a voltage at which the electrophotographic roller 1 would not discharge, specifically -500V, was applied to the electrophotographic roller 1 from an external power source to output one solid white image, and during this process the potential of the toner on the surface of the toner layer on the photosensitive drum was measured before and after passing through the nip portion between the electrophotographic roller 1 and the photosensitive drum. The potential was measured using a surface potentiometer probe (product name: MODEL555P-1, manufactured by Trek Japan) placed 2 mm away from the surface of the photosensitive drum. The difference between the potential of the surface of the toner layer before passing through the nip and the potential of the surface of the toner layer after passing through the nip was measured as the amount of charge (V) injected by the conductive member.

[0139] <Stain evaluation> The following evaluation was carried out to evaluate the amount of dirt attached to the electrophotographic roller 1. A laser printer and a process cartridge were prepared, which were modified in the same manner as in the above-mentioned <Toner Charge Amount Evaluation>. The evaluation environment was also the same as in the above-mentioned <Toner Charge Amount Evaluation>. First, 500 sheets of an image were printed, depicting horizontal lines 2 dots wide and spaced 100 dots apart in the direction perpendicular to the rotational direction of the photosensitive drum. The charging roller was then removed from the process cartridge and the resulting staining was evaluated using a tape staining test. The tape staining test was performed as follows: A polyester adhesive tape (product name: No. 31B, manufactured by Nitto Denko Corporation) was attached to the surface of the charging roller, and the tape was then peeled off along with the toner adhering to the surface of the charging roller and attached to a blank sheet of paper. This test was performed over the entire image printing area of ​​the charging roller. After this test, the reflection density of the adhesive tape was measured over the entire image printing area using a Photovolt reflection densitometer (product name: TC-6DS / A, manufactured by Tokyo Denshoku Co., Ltd.) to determine the maximum value. Next, the reflection density of a new piece of polyester adhesive tape attached to the same blank sheet of paper was measured to determine the minimum value. The increase in reflection density was used as the color density value. The smaller the color density value, the less staining there was on the charging roller, indicating a better result. Therefore, this value was used as an indicator of the degree of staining on the charging roller.

[0140] <Evaluation of charging stability> Using the same main body and cartridge configuration as in the <Stain Evaluation Test> above, 20,000 images were printed on A4-size paper in a low-temperature, low-humidity environment (temperature 15°C, relative humidity 10%), with the letter "E" printed at a 4-point size at a print rate of 1%. The output of electrophotographic images was performed in a so-called intermittent mode, in which the rotation of the electrophotographic photosensitive member was stopped for 7 seconds after each output of an electrophotographic image. Image output in the intermittent mode involves more friction between the charging roller and the electrophotographic photosensitive member than when electrophotographic images are output continuously, and therefore can be said to be a more severe evaluation condition for the charging roller. Next, a halftone image was output, and the resulting image was observed visually and with a magnifying glass, and evaluated according to the following criteria. Rank A: There are no white spots even when viewed with a magnifying glass. Rank B: No white spots are visible to the naked eye. Rank C: Slight white spots are visible to the naked eye. Rank D: White spots are visible throughout the entire area.

[0141] <Examples 2 to 28> Conductive rollers 2 to 28 were produced in the same manner as for conductive roller 1, except that the rubber compositions for forming conductive layers shown in Table 4-3 were used. Electrophotographic rollers 2 to 28 having surface layers formed from surface layer coating liquid 1 were produced in the same manner as in Example 1, except that conductive rollers 2 to 28 were used. Each of the obtained electrophotographic rollers 2 to 28 was subjected to the evaluations described in Example 1.

[0142] <Examples 29 to 40, 42> Electrophotographic rollers 29 to 40 and 42 were produced in the same manner as in Example 1, except that surface layer coating solutions 2 to 13 and 15 were used. The obtained electrophotographic rollers 29 to 40 and 42 were subjected to the evaluations described in Example 1.

[0143] <Example 41> [Preparation of Surface Layer Coating Solution 14] The ionic conductive agent E-2 used in preparing the coating solution 14 was obtained as follows. A stirring bar and 50 ml of tetrahydrofuran (THF, manufactured by Kanto Chemical Co., Ltd.) were placed in a recovery flask equipped with a Dimroth trap, and 12.5 g (0.52 mol) of sodium hydride (manufactured by Kanto Chemical Co., Ltd.) was dispersed therein. The recovery flask was cooled in an ice bath. A solution of 8.8 g (0.13 mol) of the nucleophile imidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 50 ml of THF was slowly added dropwise, after which the ice bath was removed and the mixture was stirred at room temperature for 2 hours. After adding 41.3 g (0.33 mol) of 2-bromoethanol (Tokyo Chemical Industry Co., Ltd.) as an electrophile at room temperature, the mixture was heated to reflux for 7 hours at 70° C. After the reaction, the reaction solution was filtered, the insoluble matter was washed away with THF, and the solvent of the obtained filtrate was distilled off under reduced pressure. The mixture was dissolved again in dichloromethane and filtered. The filtrate was recovered and the solvent was removed by evaporation under reduced pressure. The resulting concentrate was washed with diethyl ether and dried under reduced pressure to obtain 28 g of an ion conductive agent precursor. Subsequently, to exchange the anion of the resulting ion conductive agent with the target anion, the entire amount of the resulting ion conductive agent precursor was dissolved in 100 ml of methanol at room temperature. While stirring the solution, 57.4 g of ion-exchange salt lithium bis(trifluoromethanesulfonyl)imide (Kanto Chemical Co., Ltd.) dissolved in 50 ml of pure water was added and stirred at room temperature for 24 hours. After the reaction, the methanol was removed by evaporation under reduced pressure. After separation with dichloromethane and water, the organic layer was recovered and washed twice with water. The solvent was removed by evaporation under reduced pressure. After drying, ion conductive agent E-2 was obtained as a white powder. This ion conductive agent had an imidazolium ring and an OH group. This ionic conductive agent E-2 was used together with other materials in the amounts shown in Table 5 to prepare a surface layer coating solution 14 in the same manner as the surface layer coating solution 1. [Preparation of Electrophotographic Roller 41] An electrophotographic roller 41 was produced in the same manner as in Example 1, except that the surface layer coating liquid 14 was used. The obtained electrophotographic roller 41 was subjected to the evaluations described in Example 1.

[0144] <Example 43> The cumulative amount of ultraviolet light irradiated onto the dried coating film of the surface layer coating solution 1 was 450 mJ / cm 2 Except for the above, an electrophotographic roller 43 was produced in the same manner as in Example 1. The obtained electrophotographic roller 43 was subjected to the evaluations described in Example 1.

[0145] <Example 44> An electrophotographic roller 44 was produced in the same manner as in Example 1, except that ultraviolet light was not irradiated onto the dried coating film of the surface layer coating liquid 1. The obtained electrophotographic roller 44 was subjected to the evaluations described in Example 1.

[0146] Example 45 [Preparation of Surface Layer Coating Solution 16] Polystyrene (Sigma-Aldrich, weight-average molecular weight: 350,000) was dissolved in MEK to a concentration of 12% by mass, and 23 parts by mass of carbon black (trade name: MA230, Mitsubishi Chemical Corporation, number-average particle size: 30 nm) was added thereto. Surface layer coating solution 16 was prepared in the same manner as for surface layer coating solution 1 from the dispersion step onwards. [Preparation of Electrophotographic Roller 45] An electrophotographic roller 45 was produced in the same manner as in Example 1, except that the surface layer coating liquid 16 was used. The obtained electrophotographic roller 45 was subjected to the evaluations described in Example 1.

[0147] The evaluation results of electrophotographic rollers 1 to 45 according to Examples 1 to 45 are shown in Tables 6-1 to 6-3. The absolute values ​​of the difference in SP value between the rubber constituting the matrix and the rubber constituting the domain are shown in Table 5. Furthermore, in Table 6-1, when the surface layer formed from each coating liquid contains a urethane resin, the urethane group concentration and, when the urethane resin contains at least one of the structures represented by the above-mentioned structural formulas (1) to (3), the number of the structural formula are also shown.

[0148] [Table 6-1]

[0149] [Table 6-2]

[0150] In Table 6-2, the "average value of A / B," "average value of maximum Feret's diameter of the domain," "average value of the distance between the walls of the CB Dc," "coefficient of variation σm / Dc," and "ratio of the cross-sectional area of ​​the CB to the cross-sectional area of ​​the domain" are calculated from the values ​​of the domain that satisfy both requirement (1) and requirement (2).

[0151] [Table 6-3]

[0152] <Comparative Examples 1 to 7> [6-1. Preparation of Domain-Forming Rubber Compositions (CMB) C1 to C7] A domain-forming rubber composition was prepared to form each of the conductive layers C1 to C7 of the conductive rollers C1 to C7 according to Comparative Examples 1 to 7. Specifically, the rubber composition was prepared in the same manner as in [1-1] above, except that the materials listed in Table 7-1 were used in the amounts listed in Table 7-1.

[0153] [6-2. Preparation of Matrix-forming Rubber Compositions (MRC) C3 to C7] A rubber composition for forming a matrix was prepared to form each of the conductive layers C3 to C7 of the conductive rollers C3 to C7 according to Comparative Examples 3 to 7. Specifically, the rubber composition was prepared in the same manner as in [1-2] above, except that the materials listed in Table 7-2 were used in the amounts listed in Table 7-2.

[0154] [Table 7-1]

[0155] [Table 7-2]

[0156] [6-3. Preparation of Rubber Compositions C1 to C7 for Forming Conductive Layer] Rubber compositions C1 to C7 for conductive layers for forming conductive layers C1 to C7 were prepared in the same manner as conductive rubber composition 1, except that the CMB shown in Table 7-1, the MRC shown in Table 7-2, and other materials were compounded in the amounts shown in Table 7-3.

[0157] [Table 7-3]

[0158] The raw materials in Tables 7-1 to 7-3 above are as follows. CG102: Epichlorohydrin rubber (EO-EP-AGE ternary compound) (trade name: Epichromer CG102, SP value: 18.5 (J / cm 3 ) 0.5 , manufactured by Osaka Soda Co., Ltd.) · ON301: Epichlorohydrin rubber (EO-EP-AGE ternary compound) (trade name: Epion 301, SP value: 18.5 (J / cm 3 ) 0.5 , manufactured by Osaka Soda Co., Ltd.) EC300JD: Ketjenblack (product name: Ketjenblack EC300JD, manufactured by Ketjenblack International Co., Ltd.) LV: Quaternary ammonium salt (product name: Adeka Cizer LV70, manufactured by ADEKA Corporation) P202: Aliphatic polyester plasticizer (product name: Polycizer P-202, manufactured by DIC Corporation) AQ: Silica (product name: Nipsil AQ, manufactured by Tosoh Corporation) MB: 2-mercaptobenzimidazole (trade name: Nocrac MB, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) TS: Tetramethylthiuram monosulfide (trade name: Noccela TS, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) DM: Di-2-benzothiazolyl disulfide (DM) (trade name: Noccela DM-P (DM), manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) PW380: Paraffin oil (product name: PW-380, manufactured by Idemitsu Kosan Co., Ltd.) 25-B-40: 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne (trade name: Perhexa 25B-40, manufactured by NOF Corporation) TAIC-M60: Triallyl isocyanurate (trade name: TAIC-M60, manufactured by Nippon Kasei Co., Ltd.)

[0159] [6-4. Preparation of Electrophotographic Rollers C1 to C7] Conductive rollers C1 to C7 were produced in the same manner as in Example 1, except that rubbers C1 to C7 for forming conductive layers were used. Electrophotographic rollers C1 to C7 were produced by forming a surface layer from surface layer coating liquid 1 in the same manner as in Example 1, except that the obtained conductive rollers C1 to C7 were used. The obtained electrophotographic rollers C1 to C7 were subjected to the evaluations described in Example 1. The evaluation results are shown in Table 8. Note that, for Comparative Examples 1 and 2, as a result of determining the presence or absence of an MD structure in the conductive layer, no matrix-domain structure was found to exist, and therefore no other evaluations were made on the conductive layer. In addition, in Comparative Example 5, the conductive layer did not have a matrix-domain structure, and the conductive phase and insulating phase formed a co-continuous structure, so similarly no other evaluations were made on the conductive layer.

[0160] <Comparative Example 8> [7-1. Preparation of rubber particles for domain formation] The conductive layer-forming rubber composition C2 according to Comparative Example 2 was heated alone to be vulcanized, and then freeze-pulverized to prepare rubber particles.

[0161] [7-2. Preparation of rubber composition for matrix formation] A matrix-forming rubber composition (MRC) C8 was prepared in the same manner as in [1-2] above, except that the materials shown in Table 7-4 were used in the amounts shown in Table 7-4.

[0162] [Table 7-4]

[0163] [7-3. Preparation of Rubber Composition C8 for Forming Conductive Layer] A rubber composition C8 for forming a conductive layer was prepared in the same manner as the rubber composition 1 for forming a conductive layer, except that the rubber particles prepared in [7-1] above, the MRC prepared in [7-2] above, and other materials were used in the amounts shown in Table 7-5.

[0164] [Table 7-5]

[0165] [7-4. Preparation of Electrophotographic Roller C8] Except for using the rubber composition C8 for forming a conductive layer, a conductive roller C8 was produced in the same manner as in Example 1. Except for using the obtained conductive roller C8, a roller C8 for electrophotography was produced in the same manner as in Example 1. The obtained roller C8 for electrophotography was subjected to the evaluations described in Example 1.

[0166] <Comparative Example 9> Surface layer coating liquid C1 was prepared in the same manner as surface layer coating liquid 1, except that carbon black was not used in surface layer coating liquid 1. Electrophotographic roller C9 was prepared in the same manner as in Example 1, except that coating liquid C1 was used. The obtained electrophotographic roller C9 was subjected to the evaluation described in Example 1.

[0167] <Comparative Example 10> Surface layer Coating Liquid C2 was prepared in the same manner as for surface layer Coating Liquid 1, except that 7 parts by mass of LV: quaternary ammonium salt (trade name: Adeka Cizer LV70, manufactured by ADEKA Corporation) was used as the ionic conductive agent instead of carbon black in surface layer Coating Liquid 1. Electrophotographic roller C10 was produced in the same manner as in Example 1, except that surface layer Coating Liquid C2 was used. The obtained electrophotographic roller C10 was subjected to the evaluations described in Example 1. The evaluation results of Comparative Examples 1 to 10 are shown in Tables 8-1 to 8-3.

[0168] [Table 8-1]

[0169] [Table 8-2]

[0170] [Table 8-3]

[0171] In Comparative Example 1, because an ion-conductive conductive layer was used, it took time for charge transport from the support to the surface layer in a high-speed process, resulting in insufficient charge supply to the toner. As a result, dirt accumulation occurred due to insufficient dirt ejection, resulting in white spots on the image.

[0172] In Comparative Example 2, the conductive layer did not have a matrix-domain structure and was composed only of domain material, resulting in a configuration in which electric field concentration occurred in the conductive layer and excess charge easily flowed through the conductive path. Many areas where charge was difficult to flow were also created, resulting in a configuration in which charge was insufficiently supplied to the dirt in those areas. This resulted in dirt accumulation and the occurrence of white spots.

[0173] In Comparative Example 3, although the matrix-domain structure was used, the domains satisfying requirements (1) and (2) accounted for 80% or less by number. This is thought to be due to the small amount of carbon black added to the domains, which prevented the formation of a sufficient amount of carbon gel, resulting in an uneven domain shape. As a result, electric field concentration occurs in the conductive layer, making it easy for excess charge to flow through the conductive paths. Excessive charge transfer occurs due to the concentration of electric fields caused by the domain shape. Many areas where charge is difficult to flow occur, resulting in an insufficient charge supply to the dirt in those areas. This causes dirt to accumulate, resulting in the appearance of white spots.

[0174] Comparative Example 4 has a matrix-domain structure, but the domains are insulating because no conductive agent is added, while the matrix is ​​conductive and a continuous layer because conductive particles are added. In other words, because the conductive member has a single conductive path, electric field concentration occurs in the conductive layer, making it easy for excess charge to flow in the conductive path. Many areas where charge does not flow well occur, resulting in insufficient charge supply to dirt in those areas. Dirt accumulates, causing white spots.

[0175] In Comparative Example 5, the conductive phase and insulating phase are not a matrix-domain structure but a co-continuous structure. In other words, since the conductive member has a single conductive path, electric field concentration occurs in the conductive layer, and excess charge tends to flow in the conductive path. Many areas where charge does not flow easily occur, resulting in an insufficient charge supply to the dirt. This resulted in dirt accumulation and the occurrence of white spots.

[0176] In Comparative Example 6, although the matrix-domain structure was used, the domains satisfying requirements (1) and (2) accounted for 80% or less by number. The reason for this is thought to be that the amount of carbon black added to the domains was small, and the amount of carbon gel was insufficient to form, resulting in the domains not being circular, and the unevenness and aspect ratio becoming large. As a result, electric field concentration occurred in the conductive layer, making it easy for excess charge to flow through the conductive path. Many areas where charge flow was difficult also occurred, resulting in insufficient charge supply to dirt in these areas. Dirt accumulated, resulting in the appearance of white spots.

[0177] In Comparative Example 7, although the matrix-domain structure was used, the number of domains satisfying requirements (1) and (2) was 0%. As a result, electric field concentration occurred in the conductive layer, making it easy for excess charge to flow through the conductive path. Many areas where charge was difficult to flow were also created, resulting in an insufficient charge supply to the dirt in those areas. This resulted in dirt accumulation and the occurrence of white spots.

[0178] In Comparative Example 8, although the matrix-domain structure was used, the number of domains satisfying requirements (1) and (2) was 0%. The reason for this is that large, anisotropic conductive rubber particles formed by freeze-pulverization were dispersed. As a result, electric field concentration occurred in the conductive layer, making it easy for excess charge to flow in the conductive path. Many areas where charge flow was difficult also occurred, resulting in an insufficient charge supply to dirt in these areas. This resulted in dirt accumulation and the appearance of white spots.

[0179] In Comparative Example 9, the use of a non-conductive surface layer resulted in insufficient charge supply to the toner, which resulted in the accumulation of dirt due to insufficient dirt ejection, resulting in the occurrence of white spots on the image.

[0180] In Comparative Example 10, since an ion-conductive surface layer is used, it takes time for charge transport from the support to the surface layer in a high-speed process, resulting in insufficient charge supply to the toner. As a result, dirt accumulation occurs due to insufficient dirt ejection, resulting in white spots on the image.

[0181] <Example 46> [Production of conductive roller 29] Conductive roller 29 was produced in the same manner as conductive roller 1, except that in the polishing process of the conductive resin layer in the manufacture of conductive roller 1, it was polished to a crown shape with a diameter of 12.0 mm at positions 90 mm from the center to both ends and a central diameter of 12.2 mm.

[0182] [Preparation of surface layer coating liquid 17] The following materials were mixed and stirred: Polyether polyol (product name: PEG-1000, manufactured by Sanyo Chemical Industries, Ltd.): 52.0 parts by mass Isocyanate (product name: Millionate MR-400, manufactured by Tosoh Corporation): 48.0 parts by mass Carbon black (product name: MA-100, manufactured by Mitsubishi Chemical Corporation): 15.0 parts by mass Urethane resin particles (product name: Art Pearl C-400T, manufactured by Negami Chemical Industries): 20.0 parts by weight

[0183] Next, methyl ethyl ketone was added so that the total solid content ratio was 30% by mass, and then the mixture was mixed in a sand mill. Next, the viscosity was further adjusted to 10 to 12 cps with methyl ethyl ketone to prepare surface layer coating solution 17.

[0184] [Preparation of Electrophotographic Roller 46] An electrophotographic roller 46 was produced in the same manner as in Example 1, except that the conductive roller 29 and the surface layer coating liquid 17 were used, the drying conditions in the hot air drying oven were a temperature of 150°C for 1 hour, and UV irradiation was not performed. [evaluation] The obtained electrophotographic roller 46 was subjected to the evaluations <4-1> and <4-2> described in Example 1 and the following evaluations <7-1> to <7-4>. Note that evaluation <4-3> was not performed because the configuration of the conductive layer was the same as that of the electrophotographic roller 1 according to Example 1.

[0185] <7-1. Evaluation of physical properties as a developing roller> The electrophotographic roller 46 was evaluated for its characteristics as a developing roller as follows.

[0186] <Image (Fog) Evaluation> A magenta toner cartridge for a laser printer (product name: HP Color Laserjet Enterprise CP4515dn, manufactured by HP) equipped with the electrophotographic roller 46 as a developing roller was loaded into the laser printer. In order to evaluate a high-speed process, the laser printer was modified so that the number of sheets output per unit time was 50 sheets per minute using A4 size paper, which was greater than the number of sheets output in the original. The laser printer was left in a high temperature and humidity environment with a temperature of 32°C and a relative humidity of 85% for 6 hours. Next, an image of the letter "E" (hereinafter referred to as "E letter image") printed in 4-point size with a coverage rate of 1% of the area of ​​an A4-sized sheet of paper was continuously output onto a predetermined number of sheets of copy paper. After that, a solid white image was printed on a new copy paper, and the printer was stopped while the solid white image was being printed. At this time, the toner adhering to the photoreceptor was removed with tape (product name: CT18, manufactured by Nichiban Co., Ltd.), and the reflectance was measured with a reflection densitometer (product name: TC-6DS / A, manufactured by Tokyo Denshoku Co., Ltd.). The amount of decrease in reflectance (%) based on the reflectance of the tape was measured and used as the fogging value. Based on these fogging values, evaluation was performed according to the following criteria. Rank A: The fogging value is less than 1.5%. Rank B: The fog value is 1.5% or more and less than 3.0%. Rank C: The fog value is 3.0% or more and less than 5.0%. Rank D: The fogging value is 5.0% or more.

[0187] <Toner charge amount> To evaluate the charging ability of the developing roller to the toner, the amount of charge was measured. During the image evaluation, the toner carried on the narrowest part of the developing roller between the toner regulating blade and the photosensitive drum was collected by suction using a metal cylindrical tube and a cylindrical filter. The amount of charge stored in the capacitor and the mass of the toner sucked through the metal cylindrical tube were measured. The charge amount was measured using a measuring instrument manufactured by ADC Corporation (product name: 8252). From these values, the charge amount per unit mass (μC / g) was calculated. When a negatively charged toner is used, the sign of the charge amount per unit mass is negative, and the larger the absolute value, the higher the charge-imparting ability of the developing roller. The value obtained by measurement was taken as the toner charge amount.

[0188] <Toner charge distribution> To evaluate the spread of the charge amount of the toner, the charge amount distribution was measured. The charge distribution was measured using a powder measurement charge / particle size distribution estimation device (product name: E-spart Analyzer Model EST-III, manufactured by Hosokawa Micron Corporation). Except for this, the charge distribution was measured in the same manner as for measuring the charge of the toner. The number of particles measured was approximately 3,000. The standard deviation was calculated from the obtained charge distribution, and the obtained value was used as the initial charge distribution of the toner.

[0189] <High temperature / high humidity / low temperature / low humidity cycle test> A test (hereinafter referred to as the "environmental cycle test") in which the toner cartridge was alternately evaluated in a high-temperature, high-humidity environment and a low-temperature, low-humidity environment was conducted as follows. First, a magenta toner cartridge with each developing roller installed, similar to that used in the image (fog) evaluation, was loaded into the laser printer and placed in a high-temperature, high-humidity environment (hereinafter referred to as "H / H") at a temperature of 32°C and a relative humidity of 85%, after which it was left for 30 minutes. Next, in this environment, an image (hereinafter referred to as the "E character image") in which a 4-point letter "E" was printed with a coverage of 1% of the area of ​​an A4-sized sheet of paper was continuously printed on 500 sheets of copy paper. Next, the toner cartridge and laser printer were placed in a low-temperature, low-humidity environment (hereinafter referred to as "L / L") at a temperature of 15°C and a relative humidity of 10% RH, after which it was left for 30 minutes. Next, in this environment, an image of the letter "E" (4-point size) printed so that its coverage rate was 1% of the area of ​​an A4-sized sheet of paper (hereinafter referred to as the "E letter image") was continuously printed onto 500 sheets of copy paper. This H / H and L / L image output constituted one cycle, and a total of five cycles were repeated.

[0190] Next, the above-mentioned evaluations relating to <Image (Fogging) Evaluation>, <Toner Charge Amount>, and <Toner Charge Amount Distribution> were carried out in the same manner. Furthermore, the electrophotographic roller was taken out of the toner cartridge, and the state of destruction in the vicinity of the surface layer of the electrophotographic roller was visually observed and evaluated according to the following criteria. Rank A: No damage was observed over the entire developing roller. Rank B: Minor damage was observed only at the end of the developing roller (within a range of 1.5 cm from the end of the elastic layer in the longitudinal direction). Rank C: Minor damage is observed in areas other than the end of the developing roller. Rank D: Damage is observed anywhere on the developing roller, causing problems with the image.

[0191] <Examples 47 to 50> [Preparation of Surface Layer Coating Solutions 18 to 21] Surface layer coating solutions 18 to 21 were prepared in the same manner as surface layer coating solution 17, except that the binder resin raw material and conductive agent were changed as shown in Table 9-1.

[0192] [Table 9-1]

[0193] *The materials listed in Table 9-1 are as follows: PEG-1000: Polyethylene glycol manufactured by Sanyo Chemical Industries, Ltd. Sannix PP-1000: Polypropylene glycol manufactured by Sanyo Chemical Industries, Ltd. Sannix PP-4000: Polypropylene glycol manufactured by Sanyo Chemical Industries, Ltd. PTMG-2000: Polytetramethylene glycol manufactured by Hodogaya Chemical Co., Ltd. PTG-L3500: Polyethylene glycol manufactured by Hodogaya Chemical Co., Ltd. Nipporan 4002: Tosoh Corporation, ethylene adipate polyester polyol Nipporan 4010: Tosoh Corporation, butylene adipate polyester polyol ETERNACOLL PH-300: 1,6-HD / 1,5-PD polycarbonate diol manufactured by Ube Industries, Ltd. Acrydic A817: Acrylic polyol manufactured by DIC MR-400: Tosoh Corporation (product name Millionate MR-400) polymeric MDI Coronate 2233: TDI polyisocyanate manufactured by Tosoh Corporation Coronate L: TDI polyisocyanate manufactured by Tosoh Corporation Yuban 20SB: Melamine resin manufactured by Mitsui Chemicals MA-100: Carbon black manufactured by Mitsubishi Chemical Corporation Printex25: Carbon black manufactured by Orion Engineered Carbons CIL-312: Ionic liquid manufactured by Nippon Carlit Co., Ltd.

[0194] [Preparation of Electrophotographic Rollers 47 to 50] Electrophotographic rollers 47 to 50 were produced in the same manner as in Example 46, except that surface layer coating solutions 17 to 22 were used. The obtained electrophotographic rollers 47 to 50 were subjected to the evaluations described in Example 46.

[0195] <Example 51> [Preparation of Surface Layer Coating Solution 22] The following materials were mixed and stirred: Acrylic polyol (product name: Acrydic A817, manufactured by DIC Corporation): 75.0 parts by mass Melamine resin (product name: U-Ban 20SB, manufactured by Mitsui Chemicals): 25.0 parts by mass Carbon black (product name: Printex 25, manufactured by Orion Engineered Carbons): 10.0 parts by mass Lithium salt compound (product name: F-Top EF-N115, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.): 2.0 parts by mass Urethane resin particles (product name: Art Pearl C-400T, manufactured by Negami Chemical Industries): 20.0 parts by weight

[0196] Next, methyl ethyl ketone was added so that the total solid content ratio was 30% by mass, and then the mixture was mixed in a sand mill. Next, the viscosity was further adjusted to 10 to 12 cps with methyl ethyl ketone to prepare a surface layer coating solution 22.

[0197] [Preparation of Electrophotographic Roller 51] An electrophotographic roller 51 having a surface layer with a thickness of 15 μm on the outer periphery of a conductive layer was produced in the same manner as in Example 46, except that the surface layer coating solution 22 was used and the drying conditions in a hot air drying oven were a temperature of 140° C. and heating for 30 minutes. The obtained electrophotographic roller 51 was subjected to the evaluation described in Example 46. The evaluation results of Examples 46 to 51 are shown in Tables 9-2 and 9-3.

[0198] [Table 9-2]

[0199] [Table 9-3] [Explanation of symbols]

[0200] 1 Conductive material 2 Support 3 Conductive layer 4 Surface layer< / epdm> < / sbr> < / nbr>

Claims

1. A support having an electrically conductive outer surface; a conductive layer provided on the outer surface of the support; a surface layer provided on the outer surface of the conductive layer; An electroconductive member for electrophotography, comprising: a platinum electrode is provided directly on the outer surface of the conductive member, and an AC voltage having an amplitude of 1 V and a frequency of 1.0 Hz is applied between the outer surface of the support and the platinum electrode in an environment of a temperature of 23°C and a relative humidity of 50%, the impedance is 1.0×10 3 to 1.0×10 8 Ω; the surface layer contains a binder resin and an electronic conductive agent dispersed in the binder resin, the surface of the surface layer has protrusions resulting from exposed portions of the electronic conductive agent, The universal hardness at a depth of 1 μm from the surface of the surface layer is 1.0 N / mm ２ 7.0N / mm or more ２ is as follows: the electronic conductive agent is a first conductive carbon black; The conductive layer is a matrix containing a crosslinked product of a first rubber; a domain including a crosslinked product of the second rubber and conductive particles; and A conductive member for electrophotography, characterized in that, when a length in the longitudinal direction of the conductive layer is L and a thickness of the conductive layer is T, 15 μm square observation regions are placed at any three locations in a thickness region from the outer surface of the conductive layer to a depth of 0.1T to 0.9T on each of a cross section of the conductive layer in the thickness direction at three locations: the center in the longitudinal direction of the conductive layer and three locations at L / 4 from both ends of the conductive layer toward the center, and 80% by number or more of domains observed in each of all nine observation regions satisfy the following requirement (1) and the following requirement (2): (1) The ratio of the cross-sectional area of ​​the conductive particles contained in the domain to the cross-sectional area of ​​the domain is 20% or more; (2) When the perimeter of a domain is A and the envelope perimeter of the domain is B, A / B is 1.00 or more and 1.10 or less.

2. The volume resistivity of the surface layer is 1.0×10 １０ Ω・cm or more 1.0×10 １６ The conductive member according to claim 1 , having a resistivity of Ω·cm or less.

3. a support having an electrically conductive outer surface; a conductive layer provided on the outer surface of the support; a surface layer provided on the outer surface of the conductive layer; An electroconductive member for electrophotography, comprising: A platinum electrode was provided directly on the outer surface of the conductive member, and an AC voltage with an amplitude of 1 V and a frequency of 1.0 Hz was applied between the outer surface of the support and the platinum electrode in an environment of a temperature of 23° C. and a relative humidity of 50%, and the impedance was 1.0×10 ３ ~1.0 x 10 ８ Ω, The surface layer has an electronic conductive agent dispersed therein, The volume resistivity of the surface layer is 1.0×10 １０ Ω・cm or more 1.0×10 １６ Ω cm or less, The conductive layer is a matrix containing a crosslinked product of a first rubber; a domain including a crosslinked product of the second rubber and conductive particles; and When the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, 15 μm square observation regions are placed at any three locations in a thickness region from the outer surface of the conductive layer to a depth of 0.1T to 0.9T on each of a cross section of the conductive layer in the thickness direction, that is, at the center of the conductive layer in the longitudinal direction and at three locations spaced at L / 4 from both ends of the conductive layer toward the center, and 80% or more by number of domains observed in each of all nine observation regions satisfy the following requirement (1) and the following requirement (2): A conductive member for electrophotography characterized by: (1) The ratio of the cross-sectional area of ​​the conductive particles contained in the domain to the cross-sectional area of ​​the domain is 20% or more; (2) When the perimeter of a domain is A and the envelope perimeter of the domain is B, A / B is 1.00 or more and 1.10 or less.

4. The conductive layer is a second rubber composition containing conductive particles and a second rubber; A first rubber; The conductive member according to any one of claims 1 to 3, which is formed by curing a layer of a rubber composition comprising:

5. The volume resistivity ρm of the matrix is ​​1.0×10 ８ Ω・cm or more, 1.0×10 １７ The conductive member according to any one of claims 1 to 4, having a resistivity of Ω·cm or less.

6. The average of the maximum Feret diameter Df of the domains contained in each of the domains satisfying the requirements (1) and (2) is in the range of 0.1 to 5.0 μm. The conductive member according to any one of claims 1 to 5.

7. The conductive member according to any one of claims 1 to 6, wherein an average number of the domains present in the observation region is 20 to 300.

8. 8. The conductive member according to claim 1, wherein the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain is 30% or less.

9. The conductive member according to any one of claims 1 to 8, wherein the conductive particles are a second conductive carbon black.

10. The DBP absorption of the second conductive carbon black is 40 cm ３ / 100g or more 80cm ３ The conductive member according to claim 9, wherein the weight ratio is 1 / 100 g or less.

11. The arithmetic mean distance Dc between the second conductive carbon black particles contained in each of the domains satisfying the requirements (1) and (2) is 110 nm or more and 130 nm or less; and When the standard deviation of the distribution of the distances between the second conductive carbon black particles is σm, the σm / Dc of the distances between the second conductive carbon black particles is 0.0 or more and 0.3 or less. The conductive member according to claim 9 or 10.

12. The first rubber is at least one rubber selected from the group consisting of natural rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene terpolymer rubber, chloroprene rubber, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile rubber-butadiene rubber, and silicone rubber. The conductive member according to any one of claims 1 to 11.

13. The difference in absolute value between the solubility parameter of the first rubber and the solubility parameter of the second rubber is 0.4 (J / cm ３ ) ０．５ 4.0 (J / cm ３ ) ０．５ The conductive member according to any one of claims 1 to 12, wherein:

14. 14. The conductive member according to claim 13, wherein the second rubber is at least one rubber selected from the group consisting of natural rubber, butadiene rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, butyl rubber, ethylene propylene rubber, ethylene propylene diene rubber, chloroprene rubber, nitrile rubber, hydrogenated nitrile rubber, silicone rubber, and urethane rubber.

15. the first rubber is a styrene-butadiene rubber; the second rubber is an acrylonitrile-butadiene rubber; The conductive member according to claim 14.

16. the first rubber is an acrylonitrile-butadiene rubber; The second rubber is a styrene-butadiene rubber. The conductive member according to claim 14.

17. The volume resistivity ρm of the matrix is ​​1.0×10 １０ Ω・cm or more 1.0×10 １７ The conductive member according to any one of claims 1 to 16, having a resistivity of Ω·cm or less.

18. The volume resistivity ρm of the matrix is ​​1.0×10 １２ Ω・cm excess 1.0×10 １７ The conductive member according to any one of claims 1 to 17, having a resistivity of Ω·cm or less.

19. 3. The conductive member according to claim 1, wherein when a region of 2.0 μm in length and 2.0 μm in width on the surface of the surface layer is observed using a scanning electron microscope, the number of the protrusions is 50 or more and 500 or less.

20. The conductive member according to claim 1 , wherein the binder resin comprises a urethane resin.

21. The conductive member according to claim 20 , wherein the urethane group concentration of the urethane resin is 1.5% or more and 6.5% or less.

22. 22. The conductive member according to claim 20 or 21, wherein the urethane resin has at least one structure selected from the group consisting of a structure represented by the following structural formula (1), a structure represented by the following structural formula (2), and a structure represented by the following structural formula (3): 【Chemical 1】 (In structural formulas (1) to (3), R １ ~R ３ each independently represents a linear or branched divalent hydrocarbon group having 4 to 8 carbon atoms.

23. The conductive member according to any one of claims 1, 2, and 19 to 22, wherein the binder resin has a polycarbonate structure.

24. The conductive member according to any one of claims 1 to 23, wherein the surface layer contains roughening particles having a number average particle diameter of 3 µm or more and 30 µm or less.

25. The conductive member according to any one of claims 1 to 24, wherein the surface layer contains an ionic conductive agent.

26. A process cartridge for electrophotography that is configured to be detachably mountable to a main body of an electrophotographic image forming apparatus, characterized in that it comprises the conductive member according to any one of claims 1 to 25.

27. An electrophotographic image forming apparatus comprising the conductive member according to any one of claims 1 to 25.

Images