Electrophotographic member, electrophotographic process cartridge and electrophotographic image forming apparatus

Abstract

To provide an electrophotographic member that can prevent an adverse effect accompanying toner contamination even after printing of a large number of prints, and is hardly scratched.SOLUTION: An electrophotographic member has a conductive substrate, an elastic layer, and a surface layer. The surface layer contains fine particles and a binder resin, and has a film thickness of less than 1.0 μm. The fine particles have an average diameter of 0.1 μm to 0.9 μm. The volume occupancy of the fine particles relative to 100 volume% of the binder resin in the surface layer is 60 to 99 volume%. The fine particles have a modulus of elasticity E1 of 1000 MPa or more. The binder resin has a modulus of elasticity E2 of 2 to 200 MPa. The surface layer has an MD-1 hardness H1 of 50 to 100°. The difference between the H1 and an MD-1 hardness H2 of the elastic layer (H1-H2) is 5° or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrophotographic member incorporated in an apparatus employing an electrophotographic system, and also to an electrophotographic process cartridge and an electrophotographic image forming apparatus using the electrophotographic member. [Background technology]

[0002] As an image forming method for an electrophotographic image forming apparatus (also called an electrophotographic apparatus) such as a copying machine, a facsimile machine, or a printer, a developing method using a magnetic one-component or non-magnetic one-component toner is known. Specifically, an image is formed by the following steps. 1) A charging step in which an electrophotographic photosensitive member, which is a rotatable electrostatic latent image carrier, is charged by a charging means such as a charging roller. 2) A process in which the surface of a charged photoreceptor is exposed to laser light to form an electrostatic latent image. 3) A development process in which the toner in the toner container is applied to the developing member by the toner supply member, and the applied toner is regulated by the toner regulating member to form a toner layer, and an electrostatic latent image is developed with the toner at the contact point between the photosensitive member and the developing member. 4) A fixing process in which the toner image on the photosensitive member is transferred to the recording paper in the transfer section, either via an intermediate transfer belt or without, and then fixed to the recording paper using heat and pressure in a fixing device. 5) After transfer to the recording paper, a cleaning process is performed in which residual toner on the photosensitive drum is removed with a cleaning blade.

[0003] Specifically, the electrophotographic members used in the above-mentioned developing step are, for example, as follows: (a) A toner supply roller that is present in a toner container, supplies toner to the developing member, and scrapes off the toner after development on the developing member. (b) A toner regulating blade that forms a toner layer on the developing member to keep the amount of toner on the developing member constant. (c) A developing roller as a developing member that closes the opening of a toner container that stores toner and exposes a portion of the container to the outside, and is positioned so that this exposed portion faces the photosensitive member and develops the toner on the photosensitive member. Of these electrophotographic members, the roller members rotate, and toner is supplied, regulated, and developed by rubbing between the rollers and between the blade and the roller.

[0004] In recent years, from the perspective of environmental considerations, the development of toners that can be fixed at lower temperatures has been accelerated in order to reduce the energy required in the fixing process. Meanwhile, in the developing process, friction occurs between components to ensure uniform toner transport, which places stress on the toner. When developing latent images with toner that can be fixed at low temperatures, further reduction in stress on the toner is required. In addition, various technologies are being investigated to prevent damage to the electrophotographic components themselves by toner.

[0005] Patent Document 1 discloses a developing roller for an electrophotographic device, which has a surface layer on the surface of an elastic base layer having elasticity, the surface layer being made of a resin composition containing a fluorine-containing olefin resin, an acrylic resin, and inorganic fine particles. In a tensile test according to JIS K7113, this resin composition exhibits an elongation of 100% or more for a No. 2 test piece, has no yield point, and exhibits a stress of 25 MPa or less at 100% elongation. It also describes that the surface layer has excellent toner transport properties, flexibility, and conformability, and is resistant to scratches even with long-term use. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-301872 Summary of the Invention [Problem to be solved by the invention]

[0007] At least one aspect of the present disclosure is directed to providing an electrophotographic member that can be used as a developing member that reduces stress on toner, can prevent image defects caused by toner fusion, and has excellent durability. At least one aspect of the present disclosure is directed to providing an electrophotographic process cartridge that contributes to the stable formation of high-quality electrophotographic images. Furthermore, at least one aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images. [Means for solving the problem]

[0008] According to at least one aspect of the present disclosure, a conductive substrate; an elastic layer on the substrate; a surface layer on the elastic layer; and 1. An electrophotographic member having: the electrophotographic member is a developing roller; the surface layer contains fine particles and a binder resin; The thickness of the surface layer is , 0.2μm or more and 0.9μm or less and The average particle size of the fine particles is 、 0.1 μm End 0.9 μm below and the average particle diameter of the fine particles is in the range of −0.7 μm to +0.1 μm relative to the film thickness of the surface layer, the volume occupancy rate of the fine particles relative to 100% by volume of the binder resin in the surface layer is 60% by volume or more and 99% by volume or less; When the elastic modulus of the fine particles is E1 and the elastic modulus of the binder resin is E2, which are calculated by measuring a force curve using an SPM in a cross section of the surface layer in the thickness direction, E1 and E2 can be expressed by the following formulas (1) and (2 ): E1≧1000MPa (1) 200MPa ≥ E2 ≥ 2MPa (2) The relationship shown in a type C indenter is brought into contact with the surface of the surface layer of the electrophotographic member opposite to the surface facing the elastic layer, and the MD-1 hardness measured at an indentation depth of 2 mm is defined as H1; The surface layer is peeled off from the electrophotographic member to expose the surface of the elastic layer, and a type C indenter is brought into contact with the exposed surface of the elastic layer. When the MD-1 hardness measured at an indentation depth of 2 mm is defined as H2, H1 and H2 are represented by the following formulas (3) and (4 ): 100°≧H1≧50° (3) H1-H2≧5° (4) An electrophotographic member is provided that satisfies the relationship .

[0009] According to at least one aspect of the present disclosure, there is provided an electrophotographic process cartridge configured to be detachably mountable to a main body of an electrophotographic image forming apparatus, comprising: the electrophotographic process cartridge has a developing roller for developing an electrostatic latent image with toner to form a toner image; The developing roller the electrophotographic member That is, An electrophotographic process cartridge is provided.

[0010] Further, according to at least one aspect of the present disclosure, an image carrier for carrying an electrostatic latent image; a charging device for primarily charging the image carrier; an exposure device for forming an electrostatic latent image on the image carrier that has been primarily charged; a developing step for developing the electrostatic latent image with toner to form a toner image; Laura and, a transfer device for transferring the toner image to a transfer member; 、 In an electrophotographic image forming apparatus having The development Laura but 、 The electrophotographic member 、 An electrophotographic imaging apparatus is provided. [Effects of the Invention]

[0011] According to one aspect of the present disclosure, it is possible to obtain an electrophotographic member that is capable of suppressing adverse effects associated with toner contamination and is resistant to scratches even when a large number of sheets are printed. Also, according to another aspect of the present disclosure, it is possible to obtain an electrophotographic process cartridge and an electrophotographic image forming apparatus that have the electrophotographic member. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a cross section of a developing roller according to one aspect of the present disclosure. [Figure 2] 1 is a schematic diagram illustrating an electrophotographic process cartridge according to one embodiment of the present disclosure. [Figure 3] 1 is a schematic diagram illustrating an electrophotographic image forming apparatus according to one aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] In order to stably form high-quality electrophotographic images using toner with a lower fixing temperature, it is believed that it is effective to further reduce the stress that the developing member imparts to the toner in the developing process, and also to prevent the toner from fusing to a toner regulating member that contacts the developing member. Here, the present inventors mounted the electrophotographic member described in Patent Document 1 as a developing roller in an electrophotographic process cartridge (hereinafter also referred to as CRG), and continuously output electrophotographic images in a high-temperature, high-humidity environment using toner with a low fixing temperature. As a result, as the number of output sheets increased, streak-like defects occurred in the electrophotographic images. Then, when the CRG on which the electrophotographic images with the defects were formed was disassembled and examined, it was confirmed that toner had fused onto a toner regulating member that had been in contact with the developing roller.

[0014] The present inventors speculate that the cause of the above-mentioned defects occurring when the number of output sheets increased in an experiment using a CRG equipped with the electrophotographic member described in Patent Document 1 as a developing roller is as follows. That is, in an electrophotographic device equipped with the developing member according to Patent Document 1, it is believed that the problem is caused by the formation of electrophotographic images over a long period of time, which causes deteriorated toner to fuse to the toner regulating member (hereinafter simply referred to as the regulating member), resulting in an uneven state of the toner layer formed on the surface of the developing member.

[0015] Therefore, the present inventors have conducted extensive research to obtain a developing member capable of maintaining a uniform toner layer on the developing member even after long-term use, and have found that an electrophotographic member having the following configuration contributes to achieving the above-mentioned object. That is, the electrophotographic member according to the first aspect of the present disclosure comprises: a conductive substrate; an elastic layer on the substrate; a surface layer on the elastic layer; and 1. An electrophotographic member having: the surface layer contains fine particles and a binder resin; The thickness of the surface layer is less than 1.0 μm, The average particle size of the microparticles is 0.1 μm to 0.9 μm, The volume occupancy rate of the fine particles relative to 100% by volume of the binder resin in the surface layer is 60% by volume or more and 99% by volume or less. A force curve is measured by tracing the cross section of the surface layer in the thickness direction with the probe of a scanning probe microscope (SPM). Here, the elastic modulus calculated by Hertz theory is defined as E1 for the fine particles and E2 for the binder resin. E1 and E2 satisfy the relationship shown in the following formulas (1) and (2): E1 ≥ 1000 MPa (1), 200MPa ≥ E2 ≥ 2MPa (2). A type C indenter is brought into contact with the surface of the surface layer of the electrophotographic member opposite the surface facing the elastic layer, and the MD-1 hardness measured at an indentation depth of 2 mm is defined as H1. The surface layer is peeled from the electrophotographic member to expose the surface of the elastic layer, and a type C indenter is brought into contact with the exposed surface of the elastic layer, and the MD-1 hardness measured at an indentation depth of 2 mm is defined as H2. At this time, the relationships shown in the following formulas (3) and (4) are satisfied: 100° ≥ H1 ≥ 50° (3), H1-H2≥5° (4).

[0016] <Effective mechanism> The present inventors speculate as follows why an electrophotographic member having the above-described configuration can stably form a good electrophotographic image. Note that the mechanism of action of the electrophotographic member according to one embodiment of the present disclosure described below is merely one possible conjecture, and the present disclosure is not limited to this. Furthermore, in the following description, a developing member having a roller shape (hereinafter also referred to as a "developing roller") will be used as an example of the electrophotographic member, but the electrophotographic member according to the present disclosure is not limited to a developing roller.

[0017] The developing roller according to this embodiment has a higher surface hardness than a developing roller having only an elastic layer due to the presence of the surface layer on the elastic layer.

[0018] The microparticles in the surface layer have an elastic modulus (E1) of 1000 MPa or more, making them hard compared to other components in the developing roller. The microparticles are contained in a binder resin having an elastic modulus (E2) of 2 MPa to 200 MPa, and account for 60% to 99% by volume of the binder resin (100% by volume). The thickness of the surface layer is less than 1.0 μm.

[0019] The developing roller according to this embodiment has a relatively hard surface layer disposed on a relatively soft elastic layer with a thin thickness. That is, although the surface layer contains hard microparticles, it is thin. Therefore, it is believed that the physical properties of the elastic layer have a dominant influence on the stress on the toner, rather than the physical properties of the surface layer. Furthermore, the presence of the soft elastic layer makes it difficult for excessive stress to be applied to the toner. In other words, the toner is less likely to deteriorate even with long-term electrophotographic image formation. As a result, it is believed that the toner is less likely to fuse to the regulating member. Even with a developing roller that reduces stress on toner, repeated rubbing by the regulating member can cause stress to accumulate in the toner when used to form electrophotographic images over a long period of time. However, the developing roller according to this embodiment has an outer surface that is made of a high-hardness surface layer, which reduces the tackiness of the developing roller surface. As a result, toner-derived stains are less likely to accumulate on the surface of the developing roller. Furthermore, even if toner does melt and adhere to the regulating member, the high-hardness fine particles contained in the surface layer of the developing roller according to this embodiment effectively scrape the toner off, preventing stains from accumulating on the regulating member. These factors are believed to enable a toner layer of uniform thickness to be stably formed on the developing roller.

[0020] <Preferable composition and physical properties of the surface layer> The thickness of the surface layer is less than 1.0 μm, preferably 0.8 μm or less, and more preferably 0.5 μm or less. A thickness of less than 1.0 μm is believed to reduce stress on the toner and better prevent toner filming on the surface of the developing roller. While there is no particular lower limit to the thickness of the surface layer, it is preferable that the developing roller have a thickness that allows the fine particles to be more reliably retained. Specifically, for example, 0.1 μm or more is preferred, and 0.2 μm or more is more preferred. The thickness of the surface layer is preferably in the range of 0.1 μm or more to less than 1.0 μm, particularly 0.1 μm or more to 0.8 μm or less, and even more preferably 0.1 μm or more to 0.5 μm or less. The thickness of the surface layer is measured by measuring the thickness of the binder resin in the portion of the surface layer that does not contain fine particles using an optical microscope or electron microscope on a cross section of the surface layer in the thickness direction. Measurements are made at a total of nine locations: three in the circumferential direction of the developing roller and three in the axial direction perpendicular to the circumferential direction. The average value of the film thickness at each measurement point is taken as the film thickness of the surface layer. The surface of the developing roller has protrusions resulting from the fine particles. Even if the fine particles are not exposed from the surface layer but are embedded in the surface layer, when the surface of the developing roller is pressed, the difference in elastic modulus between the fine particles and the binder resin causes a difference in the degree of depression between the areas with and without the fine particles in the surface layer. It is believed that these surface characteristics of the developing roller make it possible to effectively scrape off the fused toner even if it adheres to the regulating member.

[0021] The average particle size of the microparticles contained in the surface layer is 0.1 μm to 0.9 μm, preferably 0.1 μm to 0.5 μm. If the average particle size of the microparticles is larger than 0.9 μm, stress on the toner between the regulating member and the microparticles increases, which may result in significant filming. On the other hand, if the average particle size of the microparticles is smaller than 0.1 μm, there is a concern that toner that has adhered or fused to the regulating member in the latter half of the durability test may not be properly scraped off. In this case, the dirt on the regulating member may grow and form circumferential streaks as a coating on the developing roller, which may manifest as image defects.

[0022] The average particle size of the fine particles is preferably about the same as the film thickness of the surface layer. Shii The average particle size of the microparticles refers to the number-average particle size. There are no particular limitations on the method for measuring the number-average particle size. For example, when measuring microparticles as raw materials for use in a coating material for forming a surface layer, the particle size can be measured using a particle size distribution analyzer. Specifically, a precision particle size distribution analyzer using the pore electrical resistance method (product name: Coulter Counter Multisizer 3) and dedicated software (product name: Beckman Coulter Multisizer 3 Version 3.51, manufactured by Beckman Coulter, Inc.) are used. An aperture diameter of 100 μm is used, and measurements are performed using 25,000 effective measurement channels. The measurement data are analyzed and calculated. The electrolytic solution used for the measurement can be, for example, an electrolytic solution prepared by dissolving special-grade sodium chloride in ion-exchange water to adjust the sodium chloride concentration to 1% by mass. Such an electrolytic solution is available, for example, as "ISOTON II" (product name, manufactured by Beckman Coulter, Inc.). Prior to measurement and analysis using the above-mentioned device and software, it is preferable to set the software as follows: In the "Change Standard Measurement Method (SOM) screen" of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using standard particles (10.0 μm, manufactured by Beckman Coulter). Press the threshold / noise level measurement button to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte solution to "ISOTON II," and check the option to flush the aperture tube after measurement. In the "Pulse to particle size conversion setting screen" of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bins, and the particle size range is set to 2 μm or more and 60 μm or less.

[0023] The specific measurement method is as follows. (1) Pour approximately 200 mL of the electrolyte solution into a 250 mL round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture tube flush" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube. (2) Approximately 30 mL of the electrolytic solution is placed in a 100 mL flat-bottom glass beaker, and approximately 0.3 mL of a diluted solution of Contaminon N (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) diluted three times by weight with ion-exchanged water is added. (3) A predetermined amount of ion-exchanged water and approximately 2 mL of Contaminon N (trade name) are added to the water tank of an ultrasonic disperser (trade name: Ultrasonic Dispersion System Tetora150, manufactured by Nikkaki Bios Co., Ltd.) that has two oscillators with an oscillation frequency of 50 kHz built in with a phase shift of 180 degrees and an electrical output of 120 W. (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized. (5) While ultrasonic waves are irradiated to the electrolyte solution in the beaker in (4), approximately 10 mg of toner (particles) is added little by little to the electrolyte solution and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C. (6) Using a pipette, add the electrolytic solution (5) containing dispersed toner particles to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to approximately 5%. Then, measure the number of particles measured until it reaches 50,000. (7) The measurement data is analyzed using the dedicated software provided with the device to calculate the number-average particle size. When the dedicated software is set to Graph / Number %, the "Average diameter" on the "Analysis / Number statistics (arithmetic mean)" screen is the number-average particle size.

[0024] When measuring the average particle size of the fine particles from the surface layer, the measurement can be carried out, for example, by the following method. When the electrophotographic member is a developing roller, a sample can be cut out as follows. The developing roller is cooled to -150°C, and a cryomicrotome (product name: UC-6, manufactured by Leica Microsystems) is used to prepare a sample that passes through the tops of the convex parts on the developing roller surface and reveals a cross section of the surface layer in the thickness direction. The average particle size (number-average particle size) of the resin particles present in the surface layer is measured by the following method. First, the circle-equivalent diameter Ds of each particle is calculated from the cross-sectional area of ​​the particle observed on the surface of the sample where the cross-section of the surface layer in the thickness direction is shown. Then, assuming that each particle is a sphere and the cross-section is a cross-section obtained by randomly cutting the sphere, the particle size D of the particle is calculated from the circle-equivalent diameter Ds using the following formula (1).

[0025]

number

[0026] The above measurements are performed on 100 microparticles exposed on the cross section of the sample. The samples are taken from a total of nine locations: three equally spaced locations along the axis of the developing roller and three equally spaced locations around the circumference, and the above calculations are performed on each of the nine samples obtained. The D values ​​of each microparticle obtained in this way are arithmetically averaged to calculate the average particle size (number-average particle size) of the microparticles.

[0027] The volume occupancy of the fine particles relative to 100% by volume of the binder resin contained in the surface layer is 60% by volume or more and 99% by volume or less. It is preferably 70% by volume or more and 95% by volume or less. When the volume occupancy is within the above range, embrittlement of the surface layer caused by an excessively high content of fine particles relative to the binder resin in the surface layer can be effectively prevented, and scraping and scratching of the surface layer can be effectively prevented. Furthermore, even if toner adheres or fuses to the above-mentioned regulating member, it can be effectively scraped off. The following method can be used to measure the volume occupancy of the fine particles relative to the binder resin in the surface layer. The volume fraction of the fine particles in the surface layer is the same as the area fraction obtained from the cross-sectional area. Therefore, the ratio of the total area of ​​the fine particles observed in the cross-section to the area of ​​the cross-section in the thickness direction of the surface layer of the sample used to measure the number average particle diameter is calculated. This measurement is performed on the nine samples, and the arithmetic average value is taken as the volume fraction of the fine particles.

[0028] The elastic modulus (E1) of the fine particles contained in the surface layer is 1000 MPa or more, as calculated by Hertz theory using a force curve measured with an SPM in a cross section of the surface layer in the thickness direction. Preferably, it is 1500 MPa or more. By having an elastic modulus of 1000 MPa or more, toner clumps fixed or fused to the toner regulating member can be more reliably scraped off.

[0029] Furthermore, the elastic modulus (E2) of the binder resin contained in the surface layer, calculated by the above-mentioned method, is 2 MPa or more and 200 MPa or less. E2 is particularly preferably 25 MPa or more and 200 MPa or less. The surface layer according to the present disclosure, despite its thin film thickness of less than 1.0 μm, contains fine particles having an E1 of 1000 MPa or more at a high content of 60 to 99 volume % relative to the binder resin in the surface layer. Generally, a resin layer containing a high content of particles with a high elastic modulus tends to become more brittle as its film thickness decreases. However, in the resin layer according to the present disclosure, the elastic modulus E2 of the binder resin is in the range of 2 MPa to 200 MPa, which is thought to prevent the surface layer from becoming brittle despite the large amount of fine particles with a high elastic modulus being filled. To obtain the elastic modulus E1 of the microparticles and the elastic modulus E2 of the binder resin in the cross section of the surface layer in the thickness direction, first, a force curve is measured using an SPM. The force curve measurement mode is contact mode, with a force distance of 500 nm and a trigger point of 0.01 V. The cantilever used is a dynamic mode silicon cantilever, such as the "OMCL-AC-160TS" (trade name, manufactured by Olympus Corporation, spring constant = 47.08 N / m), and the scanning frequency is 1 Hz.

[0030] The MD-1 hardness (H1) of the electrophotographic member of the present disclosure, measured by contacting a type C indenter with the surface of the surface layer opposite the surface facing the elastic layer and measuring the indentation depth at a depth of 2 mm, is 50° or more and 100° or less. It is preferably 70° or more and 95° or less. If this hardness is higher than 100°, stress on the toner increases, raising concerns about the occurrence of filming. On the other hand, if this hardness is lower than 50°, the contact area between the toner and the developing roller increases, raising concerns about toner sticking (initial sticking), especially after long-term storage in a high-temperature, high-humidity environment.

[0031] For the electrophotographic member of the present disclosure, the surface layer is peeled off to expose the surface of the elastic layer, and a Type C indenter is brought into contact with the exposed surface of the elastic layer. The MD-1 hardness measured at an indentation depth of 2 mm is defined as H2. In this case, the difference between the MD-1 hardnesses H1 and H2 (H1 - H2) is 5° or more. If this value is lower than 5°, tackiness is not sufficiently suppressed, which promotes the accumulation of toner stains, raising concerns about the occurrence of filming.

[0032] The 10% modulus of the binder resin used in the electrophotographic member of the present disclosure is preferably 2 MPa or more and 20 MPa or less. The 10% modulus refers to the tensile stress at 10% elongation. Particularly during toner-out, when the frequency of toner replacement on the developing roller decreases, toner fusion to the regulating member can become significant. In this case, the toner fusion portion on the regulating member has a certain size, so it bites into the surface of the developing roller. If the binder resin of the developing roller has the flexibility described above, no significant scratches or peeling will occur. On the other hand, if the 10% modulus of the binder resin is greater than 20 MPa, the binder resin will lack flexibility, raising concerns about scratches and peeling. On the other hand, if the 10% modulus of the binder resin is less than 2 MPa, the resin's molecular mobility will be high, raising concerns about toner contamination on the developing roller surface and filming.

[0033] <Configuration of the developing roller> A schematic diagram of a cross section of a developing roller according to one embodiment of the present disclosure in a direction perpendicular to the axial direction is shown in FIG. 1, but the shape of the developing roller is not limited to this. 1(a), the developing roller 1 comprises a columnar or hollow cylindrical substrate 2 and a surface layer 4, and further comprises an elastic layer 3 between the substrate 2 and the surface layer 4. That is, this developing roller has a substrate, an elastic layer on the substrate, and a surface layer on the elastic layer. As another configuration of the developing roller 1, as shown in Fig. 1(b), it may have a three-layer structure in which an intermediate layer 5 is disposed between the elastic layer 3 and the surface layer 4, or a structure in which multiple intermediate layers 5 are disposed. As the intermediate layer, a known intermediate layer for a developing roller can be used.

[0034] <Surface layer> [Fine particles] The microparticles satisfy the following requirements (I) and (II): (I) Average particle size: 0.1μm~0.9μm, (II) In a cross section of the surface layer in the thickness direction, a force curve is measured using a probe with an SPM device, and when the elastic modulus of the fine particles is defined as E1 as the elastic modulus calculated by Hertz theory, the relationship shown in the following formula (1) is satisfied: E1 ≥ 1000 MPa (1).

[0035] The fine particles can be used without any particular limitation as long as they satisfy the above (I) and (II). Specifically, fine particles of polyurethane resin, polyester resin, polyether resin, polyamide resin, acrylic resin, polycarbonate resin, phenolic resin, etc. can be used as the organic filler. Furthermore, it is preferable that these are crosslinked resin particles in order to satisfy the above formula (1). Alternatively, insulating or conductive inorganic fillers may be used. Examples of insulating inorganic fillers include fine quartz powder, silica particles, diatomaceous earth, zinc oxide, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, aluminum sulfate, calcium sulfate, barium sulfate, and glass fiber. The surfaces of these inorganic fillers may be hydrophobized by treating them with an organosilicon compound, such as polydiorganosiloxane. Examples of conductive inorganic fillers include: carbon-based materials such as carbon black and graphite; metals or alloys such as aluminum, silver, gold, tin-lead alloys, and copper-nickel alloys; metal oxides such as zinc oxide, titanium oxide, aluminum oxide, tin oxide, antimony oxide, indium oxide, and silver oxide; and materials in which various insulating fillers are plated with conductive metals such as copper, nickel, and silver.

[0036] [Binder resin] The binder resin satisfies the following requirement (i): Requirement (i): In a cross section of the surface layer in the thickness direction, a force curve is measured using a probe with an SPM device, and when the elastic modulus of the binder resin is defined as E2 as the elastic modulus calculated by Hertz theory, the relationship shown in the following formula (2) is satisfied: 200MPa ≥ E2 ≥ 2MPa (2).

[0037] The binder resin can be any resin that satisfies the above elasticity characteristics without any particular limitation. Specific examples include polyurethane resin, acrylic resin, polyolefin resin, epoxy resin, polyester resin, silicone resin, etc. These may be used alone or in combination of two or more. Among these, polyurethane resins are suitable for satisfying the above formula (2) because they have appropriate flexibility. Note that even for resins other than polyurethane resins, it is possible to adjust the elastic modulus to fall within the above range by means of adjusting the molecular weight between crosslinks, etc.

[0038] The 10% modulus value of the binder resin is preferably in the range of 2 MPa or more and 20 MPa or less. When the 10% modulus value is within this range, the binder resin exhibits moderate extensibility and can easily follow the deformation of the elastic layer. On the other hand, when the 10% modulus value is 20 MPa or less, the binder resin can follow the deformation of the elastic layer and can suppress tearing and cracking. Furthermore, when the 10% modulus value is 2 MPa or more, the tackiness is suppressed, causing surface contamination and preventing filming.

[0039] [Measurement of elastic modulus E1 and elastic modulus E2] To measure the elastic modulus E1 of the microparticles in the surface layer and the elastic modulus E2 of the binder resin, a sample is prepared from the surface layer, exposing a cross section spanning the entire thickness of the surface layer. The size of the sample is not particularly limited, but it can be, for example, a cube with a side length of 100 μm. Force curves are then measured by contacting the probe of a scanning probe microscope (SPM) with the exposed microparticles and binder resin on the surface of the sample where the cross section across the entire thickness of the surface layer is exposed. The elastic moduli E1 and E2 are calculated from the obtained force curve based on Hertz theory. An example of an SPM that can be used is the "MFP-3D-Origin" (trade name, manufactured by Oxford Instruments). When using this device, the elastic moduli E1 and E2 are automatically output from the measured force curve. Here, the method for preparing a sample from the surface layer is not particularly limited, but examples include a method using a sharp razor or a microtome, and a method using a focused ion beam (FIB). The sample acquisition position is not particularly limited, but can be, for example, the center in the direction (longitudinal direction) perpendicular to the circumferential direction of the developing roller. Furthermore, the position for measuring the force curve by SPM on the surface (observation surface) corresponding to the cross section in the thickness direction of the surface layer of the acquired sample is also not particularly limited, and measurement can be performed on the part of the fine particles and the part of the binder resin exposed on the observation surface. However, from the viewpoint of performing more stable measurements, it is preferable to measure the part of the fine particles and the part of the binder resin exposed in the central region when the observation surface is divided into three equal parts in the thickness direction in the observation surface, in the region T / 3 to 2T / 3 in the depth direction from the outer surface side of the surface layer. Furthermore, the elastic modulus E1 in this disclosure is a value obtained by measuring force curves using an SPM at any 10 points on the part of the particle exposed on the observation surface, calculating the elastic modulus from the force curves, and then taking the arithmetic average of the 8 points excluding the highest and lowest values ​​of the calculated elastic modulus. Similarly, the elastic modulus E2 in the present disclosure is a value obtained by measuring force curves using an SPM at any 10 points on the binder resin portion exposed to the observation surface, calculating the elastic modulus from the force curves, and then calculating the arithmetic average of the calculated elastic modulus values ​​at 8 points excluding the highest and lowest values. The force curve was measured using the SPM in contact mode, with a force distance of 500 nm and a trigger point of 0.01 V. The cantilever used was a dynamic mode silicon cantilever, such as the "OMCL-AC-160TS" (product name, manufactured by Olympus Corporation, spring constant = 47.08 N / m). The scanning frequency was 1 Hz.

[0040] [MD-1 hardness measurement] The electrophotographic member to be measured is left for 24 hours in an environment with a temperature of 23°C and a relative humidity of 53%. Next, using a micro rubber hardness tester (product name: MD-1capa, manufactured by Kobunshi Keiki Co., Ltd.) and a Type C indenter (diameter 1.00 mm), measurements are taken at 12 points at 90° intervals in the circumferential direction, 20 mm inward from the center and both ends of the surface layer of the electrophotographic member, by indenting each point by 2 mm. The average of these measurements is taken as the MD-1 hardness, H1, of the surface layer. Next, the surface layer is carefully removed from the electrophotographic member, and the MD-1 hardness, H2, of the exposed elastic layer is measured using the above-mentioned method. The method for removing the surface layer is not particularly limited, but for example, a razor or a microtome can be used.

[0041] [Other ingredients] In addition to the above, the surface layer may contain one or more additives selected from the group consisting of modified silicone compounds and modified fluorine compounds, as long as the functions of the surface layer are not impaired. Also, the surface layer may contain components such as crosslinking agents, plasticizers, fillers, extenders, vulcanizing agents, vulcanization aids, crosslinking aids, antioxidants, antiaging agents, processing aids, and leveling agents.

[0042] <Method of manufacturing the surface layer> The method for forming the surface layer according to the present embodiment is not particularly limited, but a coating molding method using a liquid paint is preferred. For example, the surface layer can be formed by dispersing and mixing the materials for the surface layer in a solvent to form a paint, applying the paint to an elastic roller having an elastic layer formed on a conductive substrate, and drying and solidifying the paint or by heating the paint to form the surface layer. When a crosslinked urethane resin is used as the binder resin, a polar solvent is preferred from the viewpoint of compatibility with the raw materials, polyol and isocyanate compounds. Examples of polar solvents include alcohols such as methanol, ethanol, and n-propanol, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and esters such as methyl acetate and ethyl acetate. Among these polar solvents, one or a mixture of two or more solvents that are compatible with other materials can be used. The solid content of the paint can be freely adjusted by the amount of solvent mixed, but is preferably adjusted to 20% by mass or more and 40% by mass or less from the viewpoint of uniformly dispersing the fine particles. For dispersion and mixing, known dispersion devices using beads, such as a sand mill, paint shaker, dyno mill, or pearl mill, can be used. The coating method can be any of dip coating, ring coating, spray coating, and roll coating. The drying and solidifying or heat curing is not particularly limited as long as the crosslinking of the urethane resin proceeds, but a temperature of 50°C or higher is preferred, and a temperature of 70°C or higher is more preferred.

[0043] <Base> The substrate functions as an electrode and a support member for the developing member, and is made of a conductive material such as a metal or alloy such as aluminum, a copper alloy, or stainless steel; iron plated with chromium or nickel; or a conductive synthetic resin. The substrate may be solid or hollow.

[0044] <Elastic layer> The elastic layer may be made of any material known for use in elastic layers or any material that can be used for elastic layers. The elastic layer is preferably made of a molded rubber material.

[0045] Examples of rubber materials include ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), fluororubber, silicone rubber, epichlorohydrin rubber, NBR hydride, urethane rubber, etc. These can be used alone or in combination of two or more. Among these, silicone rubber is particularly preferred because it is less likely to cause compression set in the elastic layer even when in contact with other members over a long period of time. Examples of silicone rubber include a cured product of addition-curing silicone rubber. More specifically, a cured product of addition-curing dimethyl silicone rubber is particularly preferred.

[0046] Various additives such as a conductivity imparting agent, a non-conductive filler, a crosslinking agent, and a catalyst are appropriately blended into the elastic layer. Examples of conductivity imparting agents that can be used include carbon black; conductive metals such as aluminum and copper; and fine particles of conductive metal oxides such as zinc oxide, tin oxide, and titanium oxide. At least one of these can be used. Of these, carbon black is particularly preferred because it is relatively easy to obtain and provides good conductivity. When carbon black is used as the conductivity imparting agent, it is preferably blended in an amount of 2 to 50 parts by mass per 100 parts by mass of the rubber material in the material for forming the elastic layer. Examples of non-conductive fillers include silica, quartz powder, titanium oxide, zinc oxide, and calcium carbonate, and at least one of these may be used. Examples of the crosslinking agent include di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and dicumyl peroxide, and at least one of these can be used.

[0047] <Developing device> The developing member according to each aspect of the present disclosure can be applied to a developing device that uses a magnetic one-component developer or a non-magnetic one-component developer.Furthermore, the developing member according to each aspect of the present disclosure can be applied to a developing device that does not contact an electrophotographic photosensitive member, a developing device in which the developing member contacts an electrophotographic photosensitive member, and a developing device that uses a two-component developer.

[0048] <Electrophotographic process cartridge> 2 is a schematic diagram showing an electrophotographic process cartridge according to one embodiment of the present disclosure. The electrophotographic process cartridge has an image carrier (photoconductor) 21 such as a photosensitive drum, a charging device equipped with a charging member (charging roller) 22, and a developing device equipped with a developing member 24 (developing roller). The developing device also incorporates a supply roller 25, which is a toner supply member that contacts the developing member 24, and a regulating blade 26, which is a toner regulating member. Furthermore, a cleaning member (cleaning blade) 30 that removes residual toner from the image carrier 21 is disposed upstream of the charging member 22.

[0049] <Electrophotographic image forming apparatus> Fig. 3 is a schematic diagram of an electrophotographic image forming apparatus to which the electrophotographic process cartridge of Fig. 2 is attached. The electrophotographic process cartridge is supported by a housing (not shown) and is configured to be detachably attachable to the main body of the electrophotographic image forming apparatus. The image carrier 21 is uniformly charged (primary charging) by a charging member 22 connected to a bias power supply (not shown). At this time, the charged potential of the image carrier 21 is between -800V and -400V. Next, exposure light 23 for writing an electrostatic latent image is irradiated onto the image carrier 21 from an exposure device (not shown), and an electrostatic latent image is formed on the surface. Either LED light or laser light can be used as the exposure light 23. The surface potential of the exposed portion of the image carrier 21 is, for example, between -200V and -100V. Next, negatively charged toner is applied to the electrostatic latent image by the developing member 24, forming a toner image on the image carrier 21 and converting the electrostatic latent image into a visible image (development). At this time, a voltage of, for example, −500 V or more and −300 V or less is applied to the developing member 24 by a bias power supply (not shown). The developing member 24 contacts the image carrier 21 with a nip width of, for example, 0.5 mm or more and 3 mm or less. In the electrophotographic process cartridge of this embodiment, a supply roller 25 is rotatably contacted with the developing roller 24 on the upstream side of the contact portion between the developing roller 24 and a regulating blade 26, which is a toner regulating member, in the rotational direction of the developing roller 24. The toner image developed on the image carrier 21 is primarily transferred to an intermediate transfer belt 27, which is a transfer means. A primary transfer member 28 is in contact with the rear surface of the intermediate transfer belt 27, and a voltage of +100 V or more and +1500 V or less is applied to the primary transfer member 28 to primarily transfer the negative polarity toner image from the image carrier 21 to the intermediate transfer belt 27. The primary transfer member 28 may be in the shape of a roller as shown in the figure, or in another shape such as a blade.

[0050] Furthermore, the example of the electrophotographic image forming apparatus in Figure 3 is a full-color image forming apparatus, in which the above-mentioned charging, exposure, development, and primary transfer processes are performed for each of the colors yellow, cyan, magenta, and black. Therefore, in the electrophotographic image forming apparatus shown in Figure 3, a total of four electrophotographic process cartridges, one for each color toner, are detachably mounted in the main body of the electrophotographic image forming apparatus. The above-mentioned charging, exposure, development, and primary transfer processes are performed sequentially with a predetermined time difference, and a state in which four color toner images are superimposed on the intermediate transfer belt 27 to represent a full-color image is created. As intermediate transfer belt 27 rotates, the toner image on intermediate transfer belt 27 is transported to a position facing secondary transfer member 29. Recording paper is transported between intermediate transfer belt 27 and secondary transfer member 29 along recording paper transport route 32 at a predetermined timing, and the toner image on intermediate transfer belt 27 is transferred to the recording paper by applying a secondary transfer bias to secondary transfer member 29. At this time, the bias voltage applied to secondary transfer member 29 is +1000 V or more and +4000 V or less. Secondary transfer member 29 is also included in the transfer means. The recording paper onto which the toner image has been transferred by the secondary transfer member 29 is transported to a fixing device 31 via a recording paper transport route 32. After the toner image on the recording paper is melted and fixed on the recording paper in the fixing device 31, the recording paper is discharged outside the electrophotographic image forming apparatus, thereby completing the printing operation. In addition, toner remaining on the image carrier 21 without being transferred from the image carrier 21 to the intermediate transfer belt 27 is scraped off by a cleaning member 30 for cleaning the surface of the image carrier 21, and the surface of the image carrier 21 is cleaned. Although the above description has been given of a configuration in which the transfer means has an intermediate transfer belt, the present invention is not limited to this, and the transfer means may be a direct transfer type in which the image is transferred directly from the image carrier to the recording paper. [Example]

[0051] Hereinafter, the present disclosure will be specifically explained with reference to Production Examples and Examples, but the present disclosure is not limited thereto.

[0052] <Fine particles> [Fine particles No.1] Crosslinked acrylic particles having an average particle size of 0.4 μm were synthesized using the same production method as in Example 1 of JP-A No. 2002-003511. That is, 100 parts by weight of methyl methacrylate, 0.04 parts by weight of ethylene glycol dimethacrylate, and 900 parts by weight of ion-exchanged water were placed in a 1-liter four-neck flask equipped with a thermometer and a nitrogen inlet tube, mixed, and then heated to 80°C while stirring under a nitrogen stream. Next, 0.2 parts by weight of potassium persulfate was dissolved in 5 parts by weight of ion-exchanged water, and 5.2 parts by weight of this ion-exchanged water was added to the reaction solution in the four-neck flask. The reaction solution was maintained at a temperature of 80°C and reacted for 5.00 hours to obtain a dispersion of crosslinked acrylic particles. The number-average particle size (or volume-average particle size) of the obtained crosslinked acrylic particles was 0.40 μm. Here, the number-average particle size was measured by the method described above. The crosslinked acrylic particles thus obtained were designated as Fine Particles No. 1.

[0053] [Fine particles No.2] "MX-80H3wT" (product name, material: cross-linked acrylic, average particle size: 0.8 μm, manufactured by Soken Chemical & Engineering Co., Ltd.) was prepared as fine particles No. 2. [Fine particles No.3] Crosslinked acrylic particles having an average particle size of 0.9 μm were synthesized in the same manner as in the preparation of microparticles 1, except that the polymerization time was changed to 11.25 hours. The obtained crosslinked acrylic particles were designated as microparticles No. 3. [Fine particles No.4] Crosslinked acrylic particles having an average particle size of 0.1 μm were synthesized in the same manner as in the preparation of fine particles 1, except that the polymerization time was changed to 1.25 hours. The obtained crosslinked acrylic particles were designated as fine particles No. 4. [Fine particles No.5] "Eposter S6" (trade name, material: melamine, average particle size: 0.4 μm, manufactured by Soken Chemical & Engineering Co., Ltd.) was prepared as fine particles No. 5. [Fine particles No.6] Crosslinked acrylic particles having an average particle size of 0.8 μm were synthesized in the same manner as in the case of Microparticles 1, except that the polymerization time was changed to 10.00 hours. The obtained crosslinked acrylic particles were designated as Microparticles No. 6. [Fine particles No.7] Crosslinked acrylic particles having an average particle size of 0.2 μm were synthesized in the same manner as in the preparation of fine particles 1, except that the polymerization time was changed to 2.50 hours. The obtained crosslinked acrylic particles were designated as fine particles No. 7. [Fine particles No.8] Crosslinked acrylic particles having an average particle size of 0.7 μm were synthesized in the same manner as in the case of Microparticles 1, except that the polymerization time was changed to 8.75 hours. The obtained crosslinked acrylic particles were designated as Microparticles No. 8. [Fine particles No.9] "Seahoster KE-S S50" (trade name, material: silica, average particle size: 0.5 μm, manufactured by Nippon Shokubai Co., Ltd.) was prepared as fine particles No. 9. [Fine particles No.10] "PT-301" (trade name, material: titanium oxide, average particle size: 0.3 μm, manufactured by Ishihara Sangyo Kaisha) was prepared as fine particles No. 10. [Fine particles No.11] Crosslinked acrylic particles having an average particle size of 1.0 μm were synthesized in the same manner as in the preparation of fine particles 1, except that the polymerization time was changed to 12.50 hours. The obtained crosslinked acrylic particles were designated as fine particles No. 11. [Fine particles No.12] "MP-1000" (trade name, material: non-crosslinked acrylic resin, average particle size: 0.4 μm, manufactured by Soken Chemical & Engineering Co., Ltd.) was prepared as fine particles No. 12. [Fine particles No.13] Crosslinked acrylic particles having an average particle size of 0.04 μm were synthesized in the same manner as in the preparation of fine particles 1, except that the polymerization time was changed to 0.50 hours. The obtained crosslinked acrylic particles were designated as fine particles No. 13.

[0054] The materials and number-average particle diameters (μm) of the fine particles Nos. 1 to 13 are shown in Table 1. The number-average particle diameters of the fine particles Nos. 1 to 13 were calculated according to the calculation method described above.

[0055] [Table 1]

[0056] <Synthesis of resin raw materials> [Synthesis of isocyanate-terminated prepolymer 1] Under a nitrogen atmosphere, 74.1 parts by mass of pure MDI (trade name: Millionate MT, manufactured by Tosoh Corporation) was gradually added dropwise to 100.0 parts by mass of polytetramethylene glycol-based polyol (trade name: PTMG2000, manufactured by Hodogaya Chemical Co., Ltd.) in a reaction vessel while maintaining the temperature inside the reaction vessel at 65°C. After the dropwise addition was completed, the mixture was reacted for 2 hours at a temperature of 65° C. The resulting reaction mixture was cooled to room temperature to obtain an isocyanate group-terminated prepolymer 1 having an isocyanate group content of 5.1% by mass.

[0057] [Synthesis of isocyanate-terminated prepolymer 2] Under a nitrogen atmosphere, 100.0 parts by mass of polyester / polycarbonate polyol (trade name: Nipporan 982, manufactured by Tosoh Corporation) was slowly added dropwise to 74.1 parts by mass of the pure MDI in a reaction vessel while maintaining the temperature inside the reaction vessel at 65°C. After the dropwise addition was completed, the mixture was reacted for 2 hours at a temperature of 65° C. The resulting reaction mixture was cooled to room temperature to obtain an isocyanate group-terminated prepolymer 2 having an isocyanate group content of 4.9 mass %.

[0058] <Production of Elastic Roller> A conductive substrate was prepared by coating a SUS304 core metal with an outer diameter of 6 mm and a length of 264 mm with a primer (product name: DY35-051, manufactured by Dow-Toray Industries, Inc.) and heating it for 20 minutes at a temperature of 150° C. This conductive substrate 2 was placed concentrically in a cylindrical mold with an inner diameter of 11.5 mm.

[0059] [Elastic Roller No. 1 to 5] An addition-curable liquid silicone rubber composition was prepared for the elastic layer by mixing the following materials in the proportions shown in Table 2 using a kneading and stirring device (product name: Trimix TX-15, manufactured by Inoue Seisakusho). The resulting addition-curable liquid silicone rubber composition was poured into the cavity of a mold heated to 115°C. After pouring, it was heated at 120°C for 10 minutes and cooled to room temperature, after which the substrate with a cured silicone rubber layer formed around its periphery was removed from the mold. In this way, elastic rollers Nos. 1 to 5 were obtained, each having a conductive substrate 2 and a 2.75 mm-thick elastic layer 3 containing cured silicone formed around the outer periphery.

[0060] [Table 2]

[0061] [Elastic Roller No. 6] To 100 parts by mass of styrene-butadiene rubber (SBR) (trade name: Tufden 2003, manufactured by Asahi Kasei Corporation), the materials shown in component (1) in Table 3 below were added in the proportions shown in Table 3, and the mixture was kneaded for 15 minutes in an internal mixer adjusted to a temperature of 80°C. Next, the materials shown in component (2) in Table 3 below were added in the proportions shown in Table 3. Next, the mixture was kneaded for 10 minutes in a two-roll mill cooled to a temperature of 25°C, to obtain conductive rubber composition No. 1.

[0062] [Table 3]

[0063] A conductive vulcanizing adhesive (product name: Metalock U-20, manufactured by Toyo Kagaku Kenkyusho) was applied to the peripheral surface of a stainless steel (SUS304) cylinder with an outer diameter of 6 mm and a length of 270 mm, and then baked to produce a conductive substrate. Using an extrusion molding device equipped with a crosshead, the substrate was formed into a cylindrical shape with the conductive rubber composition No. 1 around its central axis. The thickness of the layer of conductive rubber composition No. 1 was 2.75 mm. The substrate with the conductive rubber composition No. 1 layer was placed in a hot air oven and heated at 160°C for 1 hour to vulcanize the conductive rubber composition No. 1 layer and form a rubber layer. Both ends of the rubber layer were then removed to reduce its length to 235 mm. The outer peripheral surface of the rubber layer was then polished with a plunge-cut grinding machine to give the rubber layer a crowned shape. The outer diameter of the crowned rubber layer was measured longitudinally at 1 mm intervals using a laser length measuring device (product name: Controller LS-7000, Sensor Head LS-7030R, manufactured by Keyence Corporation). The difference between the average outer diameter at a position 10 mm from the longitudinal end toward the center of the rubber layer and the average outer diameter at the longitudinal center was defined as the crown amount. As a result, the outer diameter at a position 10 mm from the longitudinal end toward the center was 10.018 mm, and the outer diameter at the center was 10.068 mm. Therefore, the crown amount was 50 μm. The substrate with the crown-shaped rubber layer was then placed in a hot air oven and post-heated at 195°C for 1 hour in an air atmosphere to obtain elastic roller No. 6.

[0064] <Formation of surface layer> [Paint Intermediates No. 1-9] Coating intermediates Nos. 1 to 9 were prepared as raw materials for the coating material for forming the surface layer. Specifically, the following materials were mixed by stirring in the proportions shown in Table 4. Next, methyl ethyl ketone (manufactured by Kishida Chemical Co., Ltd.) was added so that the solid concentration was 30% by mass, and after mixing, the mixture was uniformly dispersed using a sand mill. Polyol PTMG650: Polytetramethylene glycol (molecular weight 650, manufactured by Hodogaya Chemical Co., Ltd.) PTMG1000: Polytetramethylene glycol (molecular weight 1000, manufactured by Hodogaya Chemical Co., Ltd.) PTMG2000: Polytetramethylene glycol (molecular weight 2000, manufactured by Hodogaya Chemical Co., Ltd.) PTMG3500: Polytetramethylene glycol (molecular weight 3500, manufactured by Hodogaya Chemical Co., Ltd.) NP-400: Newpol NP-400 (product name, manufactured by Sanyo Chemical Industries Co., Ltd.) Isocyanate compounds MR-400: Millionate MR-400 (product name, manufactured by Tosoh Corporation) NCO1: The above isocyanate group-terminated prepolymer 1 NCO2: The above isocyanate group-terminated prepolymer 2 ●Carbon black SB X15: SUNBLACK X15 (product name, manufactured by Asahi Carbon Co., Ltd.) Additives TSF: TSF4445 (product name, polyether-modified silicone oil, manufactured by Momentive Performance Materials Japan)

[0065] [Table 4]

[0066] [Paint Intermediate No. 10] The materials shown in Table 5 below were mixed and stirred. Next, methyl ethyl ketone (Kishida Chemical Co., Ltd.) was added so that the solids concentration was 30% by mass, and after mixing, the mixture was uniformly dispersed in a sand mill to obtain paint intermediate No. 10.

[0067] [Table 5]

[0068] [Paint Intermediate No. 11] The materials shown in Table 6 below were mixed and stirred. Next, methyl ethyl ketone (Kishida Chemical Co., Ltd.) was added so that the solids concentration was 30% by mass, and after mixing, the mixture was uniformly dispersed in a sand mill to obtain paint intermediate No. 11.

[0069] [Table 6]

[0070] [Preparation of paint for forming surface layer] To the obtained coating material intermediates Nos. 1 to 11, the listed parts of fine particles Nos. 1 to 13 were added in the combinations shown in Table 7 below, and the mixture was stirred and dispersed using a ball mill. The number of parts of fine particles listed in Table 7 is the amount relative to 100 parts by mass of binder resin in the coating material intermediate. The amount of binder resin refers to the total parts by mass of polyol and isocyanate. Next, methyl ethyl ketone (manufactured by Kishida Chemical Co., Ltd.) was added and the solid content was adjusted to the amount shown in Table 7, thereby obtaining coating materials for forming surface layers Nos. 1 to 35.

[0071] [Table 7]

[0072] [Developing Roller No. 1] The surface layer-forming coating material No. 1 was roll-coated onto the elastic roller No. 1 so that the dry thickness of the coating film was 0.4 μm. The coating film was then heated at 130° C. for 60 minutes to dry and harden the coating film, thereby forming a surface layer on the elastic layer, thereby producing developing roller No. 1. [Developing roller No. 2 to 50] Surface layer-forming coating materials were prepared in the same manner as above, except that the materials shown in Table 7 were used as the surface layer materials. Each coating material was then applied to each elastic roller as shown in Table 8, followed by drying and heating in the same manner as above, to produce developing rollers Nos. 2 to 50.

[0073] [Table 8]

[0074] <Evaluation of physical properties of developing materials> The resulting developing roller was subjected to the following measurements and physical property evaluations, and the results are shown in Table 9 (Table 9-1). [Film thickness measurement] The thickness of the surface layer was measured by observing the cross section of the surface layer at nine locations (three axial locations and three circumferential locations) using an optical microscope or an electron microscope, and the average value was taken as the "thickness" of the surface layer.

[0075] [Measurement of Elastic Modulus E1 of Fine Particles in Surface Layer and Elastic Modulus E2 of Binder Resin] The elastic modulus E1 of the fine particles and the elastic modulus E2 of the binder resin were determined by the above-mentioned method for measuring the SPM elastic modulus.

[0076] [Measurement of elastic modulus E1 and E2] The elastic modulus E1 of the microparticles in the surface layer and the elastic modulus E2 of the binder resin were measured by preparing a sample in which a cross section spanning the entire thickness of the surface layer was exposed from the surface layer. The sample was a cube with a side length of 100 μm. Force curves were measured by contacting the probe of a scanning probe microscope (SPM) with the exposed microparticles and binder resin on the surface where the cross section across the entire thickness of the surface layer was exposed. The elastic moduli E1 and E2 were calculated from the force curves based on Hertz theory. The SPM used was the "MFP-3D-Origin" (trade name, manufactured by Oxford Instruments). This device automatically measures the force curve and outputs the elastic moduli E1 and E2 from the measured force curve. Here, to prepare samples from the surface layer, a freezing cutting system (product name: EM FC6, manufactured by Leica Microsystems) and an ultramicrotome (product name: EM UC6, manufactured by Leica Microsystems) were used to prepare cubic samples with sides of 100 μm from the surface layer. The samples were taken from the center of the longitudinal direction of the surface layer. The surface (observation surface) of the obtained sample, corresponding to the cross section of the surface layer in the full thickness direction, was measured in the region T / 3 to 2T / 3 in the depth direction from the outer surface side of the surface layer, i.e., the portion of the fine particles and the portion of the binder resin exposed in the central region when the observation surface was divided into three equal parts in the thickness direction. In this measurement, force curves were measured using an SPM at 10 random locations on the part of the particle exposed on the observation surface, and the elastic modulus was calculated from the force curves. The elastic modulus E1 was determined as the arithmetic mean of the 8 calculated elastic moduli excluding the highest and lowest values. In this measurement, force curves were measured using an SPM at 10 random locations on the binder resin portion exposed to the observation surface, and the elastic modulus was calculated from the force curves. The arithmetic mean of the 8 calculated elastic moduli excluding the highest and lowest values ​​was determined as the elastic modulus E2. The force curve was measured using the SPM in contact mode, with a force distance of 500 nm and a trigger point of 0.01 V. The cantilever used was a dynamic mode silicon cantilever, such as the "OMCL-AC-160TS" (trade name, manufactured by Olympus Corporation, spring constant = 47.08 N / m). The scanning frequency was 1 Hz.

[0077] [Measurement of the volume ratio of fine particles to binder resin in the surface layer] The volume occupancy of the fine particles relative to the binder resin in the surface layer was calculated according to the above-mentioned calculation method.

[0078] [MD-1 hardness measurement] The electrophotographic roller to be measured was left for 24 hours in an environment with a temperature of 23°C and a relative humidity of 53%. Next, using a micro rubber hardness tester (product name: MD-1capa, manufactured by Kobunshi Keiki Co., Ltd.) and a Type C indenter (diameter 1.00 mm), the MD-1 hardness was measured at each position by pressing 2 mm into 12 points at 90° intervals around the circumference at positions 20 mm inward from the center and both ends of the surface layer of the electrophotographic roller. The average value of the MD-1 hardness values ​​at each position was taken as the MD-1 hardness H1 of the surface layer in this measurement. Next, the surface layer was removed from the electrophotographic roller to be measured using an ultramicrotome (product name: EM UC6, manufactured by Leica Microsystems) to expose the surface of the elastic layer. Then, the MD-1 hardness H2 of the elastic layer was obtained in the same manner as above, except that the contact point of the indenter of the micro rubber hardness meter was set to the surface of the exposed elastic layer. Then, the difference (H1-H2) between the hardness H1 of the surface layer and the hardness H2 of the elastic layer was calculated.

[0079] [Measurement of tensile elasticity] Using test pieces prepared from surface layer-forming paints Nos. 1 to 35, the tensile modulus was measured under the following conditions: n=5, and measurements were performed using a universal tensile tester (trade name: Tensilon RTC-1250A, manufactured by Orientec Co., Ltd.) in a temperature of 20°C and a humidity of 60% RH, and the average value was taken as the tensile modulus.

[0080] <Image evaluation> The following image evaluations were carried out, and the results are shown in Table 9 (Table 9-2). [Preparation for image evaluation] A cyan process cartridge (product name: HP 656X High Yield Cyan Original LaserJet Toner Cartridge, manufactured by HP) for a color laser printer (product name: HP Color LaserJet Enterprise M652dn, manufactured by HP) was prepared, and to evaluate initial adhesion, developing rollers No. 1 to 50 with their surfaces coated with toner were each stored in individual cartridges (CRGs). Next, these CRGs were left for 30 days in a high-temperature, high-humidity environment at a temperature of 30°C and a relative humidity of 95%.

[0081] [Evaluation 1: Initial adhesion evaluation] The CRG containing the developing rollers Nos. 1 to 50 was stored in the color laser printer at a temperature of 30°C and a relative humidity of 95%. Subsequently, 50 solid white images were output without pre-rotation, and if image defects due to abnormal images occurred from the first sheet, the number of sheets required until the defects disappeared was recorded. If no abnormal images were observed, the number was recorded as 0.

[0082] [Evaluation 2: Blade fusion evaluation] The CRG was removed from the main body, and the developing roller and regulating blade were removed. The surface of the regulating blade was then observed with a laser microscope (product name: VK-8700, manufactured by Keyence Corporation) using a 20x objective lens, and the size of the toner fused particles was measured. If no fused particles were found, the size was recorded as 0.

[0083] [Rating 3: Surface scratches] The surface of the developing roller removed from the CRG was blown with air to remove the toner coated on the surface. The surface condition of the roller was then observed with a laser microscope (product name: VK-8700, manufactured by Keyence Corporation) using a 20x objective lens, and the size of scratches was measured. Note that if there were no surface scratches, it was recorded as 0.

[0084] [Rating 4: Filming rating] The surface of the developing roller was observed with a laser microscope (product name: VK-8700, manufactured by Keyence Corporation) using a 20x objective lens, and the area ratio of filming was calculated. Note that if no filming was found, it was recorded as 0.

[0085] [Table 9-1]

[0086] [Table 9-2]

[0087] [Discussion of evaluation results] In Examples 1 to 39, since all conditions were within the ranges described in this disclosure, there were no problems with initial adhesion, image density, blade adhesion, surface scratches, or filming, and it was confirmed that these developing rollers were able to exhibit good image performance. In particular, in Examples 1 to 7, 15, and 19, the evaluation results show that the surface layer is thin, with a thickness of 0.5 μm or less, and almost no blade fusion is observed. This is presumably because the blade fusion material is well scraped off by the developing roller. It was also confirmed that the smaller the 10% modulus of the binder resin, the less likely the surface to be scratched. On the other hand, significant filming was observed in Comparative Examples 1, 2, 6, and 8. This is presumably because the film thickness of the surface layer, the average particle size of the microparticles, the elastic modulus of the binder resin, and the hardness of the surface layer were outside the ranges of the present disclosure, resulting in significant stress on the toner. In Comparative Example 3, noticeable surface scratches were observed, which is presumed to be due to the large volume occupancy of the fine particles, which made the surface layer brittle. In Comparative Examples 4, 5, 10, and 11, the image density was low and significant blade fusion was observed. This is thought to be because the volume fraction of the fine particles was smaller than specified in the present disclosure, the MD-1 hardness difference between the surface layer and the elastic layer was smaller than specified, the average particle size of the fine particles was smaller than specified, or the elastic modulus of the fine particles was smaller than specified, so the toner components fused to the blade could not be scraped off effectively. Initial sticking was noticeable in Comparative Examples 7 and 9. This is presumably due to the influence of high molecular mobility on the outermost surface and a large nip at the time of contact, which were caused by the elastic modulus of the binder resin being smaller than the specified value and the MD-1 of the surface layer being lower than the specified value.

[0088] The present disclosure includes the following configurations. [Configuration 1] a conductive substrate; an elastic layer on the substrate; a surface layer on the elastic layer; and 1. An electrophotographic member having: the surface layer contains fine particles and a binder resin; The thickness of the surface layer is less than 1.0 μm, The average particle size of the microparticles is 0.1 μm to 0.9 μm, the volume occupancy rate of the fine particles relative to 100% by volume of the binder resin in the surface layer is 60% by volume or more and 99% by volume or less; When the elastic modulus of the fine particles and the elastic modulus of the binder resin, which are calculated by measuring a force curve using an SPM in a cross section of the surface layer in the thickness direction, are defined as E1 and E2, respectively, E1 and E2 satisfy the relationship shown in the following formulas (1) and (2): E1 ≥ 1000 MPa (1), 200MPa ≥ E2 ≥ 2MPa (2), a type C indenter is brought into contact with the surface of the surface layer of the electrophotographic member opposite to the surface facing the elastic layer, and the MD-1 hardness measured at an indentation depth of 2 mm is defined as H1; The surface layer is peeled off from the electrophotographic member to expose the surface of the elastic layer, and a type C indenter is brought into contact with the exposed surface of the elastic layer. When the MD-1 hardness measured at an indentation depth of 2 mm is defined as H2, H1 and H2 satisfy the relationships shown in the following formulas (3) and (4): 100° ≥ H1 ≥ 50° (3), H1-H2≥5° (4). [Configuration 2] 2. The electrophotographic member according to Configuration 1, wherein the 10% modulus of the binder resin is 2 MPa or more and 20 MPa or less. [Configuration 3] 3. The electrophotographic member according to configuration 1 or 2, wherein the surface layer has a thickness of 0.5 μm or less. [Configuration 4] An electrophotographic process cartridge configured to be detachably attached to the main body of an electrophotographic image forming apparatus, characterized in that the electrophotographic process cartridge comprises the electrophotographic member according to any one of configurations 1 to 3. [Configuration 5] An electrophotographic image forming apparatus comprising an image carrier for carrying an electrostatic latent image, a charging device for primarily charging the image carrier, an exposure device for forming an electrostatic latent image on the primarily charged image carrier, a developing member for developing the electrostatic latent image with toner to form a toner image, and a transfer device for transferring the toner image to a transfer member, wherein the developing member is the electrophotographic member according to any one of the configurations 1 to 3.

[0089] 1: Developing roller 2: Base 3: Elastic layer 4: Surface layer 21: Image carrier (photosensitive member) 22: Charging member (charging roller) 23: Exposure light 24: Developing member (developing roller) 25: Toner supply member (supply roller) 26: Toner regulation member (regulation blade)

Claims

1. a conductive substrate; an elastic layer on the substrate; a surface layer on the elastic layer; and 1. An electrophotographic member having: the electrophotographic member is a developing roller; the surface layer contains fine particles and a binder resin; the thickness of the surface layer is 0.2 μm or more and 0.9 μm or less; The average particle size of the fine particles is 0.1 μm or more and 0.9 μm or less, the average particle diameter of the fine particles is in the range of −0.7 μm to +0.1 μm relative to the film thickness of the surface layer; a volume occupancy rate of the fine particles relative to 100% by volume of the binder resin in the surface layer is 60% by volume or more and 99% by volume or less; When the elastic modulus of the fine particles is defined as E1 and the elastic modulus of the binder resin is defined as E2, the elastic modulus is calculated by measuring a force curve using an SPM in a cross section of the surface layer in the thickness direction, E1 and E2 are represented by the following formulas (1) and (2): E1≧1000 MPa (1) 200 MPa ≧ E2 ≧ 2 MPa (2) The relationship shown in a type C indenter is brought into contact with the surface of the surface layer of the electrophotographic member opposite to the surface facing the elastic layer, and the MD-1 hardness measured at an indentation depth of 2 mm is defined as H1; The surface layer is peeled off from the electrophotographic member to expose the surface of the elastic layer, and a type C indenter is brought into contact with the exposed surface of the elastic layer. When the MD-1 hardness measured at an indentation depth of 2 mm is defined as H2, H1 and H2 are represented by the following formulas (3) and (4): 100°≧H1≧50° (3) H1-H2≧5° (4) The relationship shown in Electrophotographic member characterized by:

2. 2. The electrophotographic member according to claim 1, wherein the 10% modulus of the binder resin is 2 MPa or more and 20 MPa or less.

3. 2. The electrophotographic member according to claim 1, wherein the surface layer has a thickness of 0.5 [mu]m or less.

4. An electrophotographic process cartridge configured to be detachably mounted in a main body of an electrophotographic image forming apparatus, the electrophotographic process cartridge has a developing roller for developing an electrostatic latent image with toner to form a toner image; The developing roller is the electrophotographic member according to any one of claims 1 to 3. Electrophotographic process cartridge.

5. an image carrier for carrying an electrostatic latent image; a charging device for primarily charging the image carrier; an exposure device for forming an electrostatic latent image on the image carrier that has been primarily charged; a developing roller for developing the electrostatic latent image with toner to form a toner image; a transfer device for transferring the toner image to a transfer member; In an electrophotographic image forming apparatus having The developing roller is the electrophotographic member according to any one of claims 1 to 3. Electrophotographic image forming apparatus characterized in that:

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