Regenerated elastic roller manufacturing method

Abstract

Provided is a regenerated elastic roller manufacturing method which contributes to excellent image formation by efficiently removing contaminants adhered to the surface of an elastic roller even when the roller has been used for a long period of time and has a large amount of contaminants adhered thereto. The regenerated elastic roller manufacturing method includes a contaminant removal step for removing contaminants adhered to the outer surface of an elastic roller which has a support body having a conductive outer surface, and a conductive layer on the outer surface of the support body. The regenerated elastic roller manufacturing method is characterized in that: the conductive layer has a prescribed matrix including a first rubber and a plurality of prescribed domains dispersed in the matrix; the elastic roller satisfies prescribed conditions (1), (2), and (3); the contaminant removal step includes a peeling step for peeling off an adhesive tape after pressing the adhesive tape against the outer surface of the elastic roller to which the contaminants are adhered; and the peeling step is performed in a state in which an electrical charge due to separation electrification on the outer surface of the elastic roller is removed.

Description

Manufacturing method for recycled elastic roller

[0001] The present disclosure relates to a method for manufacturing a reclaimed elastic roller.

[0002] Electrophotographic image forming apparatuses use elastic rollers such as charging rollers, transfer rollers, developing rollers, fixing rollers, and cleaning rollers. During image output, contaminants such as developer, external additives derived from the developer, and paper dust adhere to and gradually accumulate on the surfaces of these elastic rollers. As a result, the performance of the elastic rollers may deteriorate, and they may be replaced as consumable parts. In recent years, from the perspective of reducing environmental impact, there has been an increasing need for the development of technologies for recovering used elastic rollers and cleaning and recycling the roller surfaces using various cleaning means. Patent Document 1 discloses a method for manufacturing a recycled elastic roller for an elastic roller that has developed a film on its surface due to adhesion of developer or the like, the method comprising the steps of pressing a pressure roller against the elastic roller to create cracks in the film, and removing the film using an adhesive roller.

[0003] Japanese Patent Application Laid-Open No. 2008-203832

[0004] The present inventors have found that as the lifespan of electrophotographic devices has been extended, the amount of contaminants adhering to the surface of the elastic roller has been increasing, and that improvements to the conventional elastic regenerated roller and cleaning method are necessary. The present inventors have recognized that the regeneration method disclosed in Patent Document 1 has the following problems. Specifically, in the process of removing filming using an adhesive roller, peeling charge occurs between the adhesive roller and the regenerated elastic roller, and the peeling charge remains unevenly on the surface of the elastic roller, which can cause some of the contaminants peeled off by the adhesive roller to adhere again to the elastic roller due to electrostatic attraction.

[0005] The present disclosure provides a method for producing a recycled elastic roller that efficiently removes contaminants adhering to the surface of an elastic roller that has been used for a long period of time and has a large amount of contaminants adhering to the surface, thereby contributing to good image formation.

[0006] The present disclosure provides a method for producing a recycled elastic roller, the method comprising a contaminant removal step of removing contaminants adhered to the outer surface of an elastic roller having a support having a conductive outer surface and a conductive layer on the outer surface of the support, wherein the conductive layer has a matrix containing a first rubber and a plurality of domains dispersed in the matrix, and the volume resistivity of the matrix is ​​1.0×10 ８ ~1.0 x 10 １７ The present invention relates to a method for manufacturing a recycled elastic roller, the method comprising: providing a metal film directly on the outer surface of the elastic roller; applying an AC voltage with an amplitude of 1 V and a frequency of 1.0 × 10 Hz between the outer surface of the support and the metal film in an environment of a temperature of 23°C and a humidity of 50% RH; and applying an AC voltage with an amplitude of 1 V and a frequency of 1.0 × 10 Hz between the outer surface of the support and the metal film in an environment of a temperature of 23°C and a humidity of 50% RH. －２ ~1.0 x 10 ７ When the impedance was measured by applying a voltage varying between 1.0 x 10 －１ The absolute value of the impedance in Hz is 1.0 x 10 ３ ~1.0 x 10 ８ Condition (2) When the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, at least eight of nine cubic samples each 9 μm on a side are sampled at three locations: the center of the conductive layer in the longitudinal direction, and three locations spaced at L / 4 from both ends of the conductive layer toward the center, at depths of 0.3T, 0.6T, and 0.9T from the outer surface of the conductive layer toward the support, and at least eight of the nine cubic samples each 9 μm on a side satisfy the following: When one sample is divided into 27 unit cubes each 3 μm on a side, and the volume Vd of the domain contained in each of the unit cubes is determined, Vd is 2.7 to 10.8 μm ３The number of unit cubes in which μ is the average value of the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain in the cross section of the conductive layer in the thickness direction is μ (area %), and the standard deviation of this ratio is σ, where σ / μ is 0.00 to 0.40 and μ is 20.0 to 40.0 area %.

[0007] According to the present disclosure, a method for manufacturing a recycled elastic roller is provided that effectively removes contaminants adhering to the surface of an elastic roller that has been used for a long period of time and has a large amount of contaminants adhering to the surface, thereby contributing to good image formation.

[0008] Fig. 1 is a conceptual diagram of the phenomenon in which peeling charge remains unevenly on the surface of an elastic roller. Fig. 2 is a conceptual diagram of a matrix domain structure. Fig. 3 is a schematic diagram showing an example of a cleaning device that removes contaminants using adhesive tape. Figs. 4A, 4B, and 4C are schematic diagrams showing an example of a configuration for removing charge due to peeling charge. Figs. 5A and 5B are explanatory diagrams of the cross-sectional cutting direction. Fig. 6 is an explanatory diagram of the envelope perimeter. Fig. 7 is a cross-sectional view of an elastic roller according to one embodiment of the present disclosure.

[0009] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Note that when XX is a group, multiple XXs may be selected, and the same applies to YY and ZZ.

[0010] As described above, the present inventors recognized that the recycling method of Patent Document 1 generates peeling electrification, resulting in the above-mentioned problem. Peeling electrification refers to the phenomenon in which one object and the other object become charged when two contacting objects are peeled away from each other. For example, in the recycling method of Patent Document 1, the adhesive roller and the recycled elastic roller become charged. Furthermore, as contaminants are peeled away from the surface of the conductive layer, peeling electrification also occurs on the surface of the conductive layer and the surface of the contaminant. At this time, the polarities of the charges generated on the surface of the conductive layer and the surface of the contaminant are opposite. As a result, the present inventors believe that after the contaminant is peeled away, an electrostatic attraction occurs between the charge remaining on the surface of the conductive layer and the charge on the contaminant, causing the contaminant to reattach to the surface of the conductive layer.

[0011] The inventors also recognized that the conductive layer of conventional elastic rollers has non-uniform conductivity for the following reasons. It is believed that this non-uniformity causes charge due to peeling electrification to remain unevenly on the surface of the elastic roller. Conventional elastic rollers impart conductivity to the elastic layer by adding an electronic conductive agent to the resin or rubber, which then connects the electronic conductive agent to form a conductive path. Focusing on a single electronic conductive agent in the conductive layer, there is variation in the distance between the single electronic conductive agent and multiple surrounding electronic conductive agent particles. As a result, it is believed that non-uniformity in the conductivity generated by the countless conductive paths existing from the conductive support to the surface of the conductive layer is unavoidable. In particular, when the conductive support is not grounded during contaminant removal with an adhesive roller, it is believed that a large amount of charge due to peeling electrification remains in areas with particularly low conductivity among the uneven distribution of conductive paths. As a result, electrostatic attraction is likely to occur between the charge remaining on the surface of the elastic roller and the charge on the contaminant.

[0012] Figure 1 is a conceptual diagram of the phenomenon in which charges due to peeling remain unevenly on the surface of an elastic roller. The left side of Figure 1 shows the state after contaminants 105 have been removed from the surface 101 of the elastic roller. Contaminants 105 are attached to the surface 106 of the adhesive roller, and charges 104 due to peeling remain on the surface 106 of the adhesive roller and the surface of the contaminants 105. Furthermore, due to the unevenness of the conductive paths formed by the electronic conductive agent 102 on the surface 101 of the elastic roller, charges 103 due to peeling remain unevenly on the surface 101 of the elastic roller. Meanwhile, the right side of Figure 1 shows the state in which electrostatic attraction occurs between the charges 103 remaining on the surface 101 of the elastic roller and the charges 104 of the contaminants 105, causing the contaminants 105 to reattach to the surface 101 of the elastic roller.

[0013] Based on the above considerations, the inventors came up with a configuration that achieves both uniform conductivity of the elastic roller by using a conductive layer having a matrix domain structure in which conductive particles are contained in the domains as an electronic conductive agent, and that allows the peeling step of the contamination removal process to be performed in a state in which peeling electrification of the outer surface of the elastic roller is suppressed.

[0014] As described above, when conductive paths are formed by connections between electronic conductive agents, variations in the conductive paths are inevitable. In contrast, in the present disclosure, conductive particles serving as electronic conductive agents are contained within domains, the conductive particles are densely present within the domains, and the amount of conductive particles contained in each domain is minimally varied. Furthermore, by using a matrix domain structure and setting the volume resistivity of the matrix within a predetermined range, uniform conductivity can be achieved that is not dependent on variations in the distance between conductive particles. Furthermore, by forming the matrix domain structure in a stable domain dispersion state, the distance between the domains becomes uniform. To achieve this stable domain dispersion, a certain amount of domains is contained in the conductive layer. As a result, the conductive form of the conductive layer is a state due to hopping conduction between domains. In other words, the state depends not on the distance between the electronic conductive agents but on the distance between the domains. The inventors believe that, as a result, a conductive layer has been obtained in which charge due to peeling electrification does not remain unevenly and is quickly removed.

[0015] 2 is a conceptual diagram of the matrix domain structure. The conductive layer 2 has a matrix 2a and a plurality of domains 2b dispersed in the matrix 2a. The domains 2b contain conductive particles 2c.

[0016] <Method for Confirming Phase Separation Structure> The phase separation structure 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. If necessary, the observation sample is subjected to a treatment (e.g., a staining treatment or a vapor deposition treatment) that makes it easy to distinguish between the first rubber phase and the second rubber phase. The observation sample is then observed using a laser microscope, SEM, or TEM. A more specific procedure will be described later.

[0017] The elastic roller satisfies the following conditions (1) to (3): <Condition (1)> A metal film is provided directly on the outer surface of the elastic roller, and an AC voltage with an amplitude of 1 V and a frequency of 1.0 × 10 is applied between the outer surface of the support and the metal film in an environment of a temperature of 23°C and a humidity of 50% RH. －２ ~1.0 x 10 ７ When the impedance was measured by applying a voltage varying between 1.0 x 10 －１ The absolute value of the impedance in Hz is 1.0 x 10 ３ ~1.0 x 10 ８ It is Ω.

[0018] The frequency is 1.0 x 10 －１ The absolute value of the impedance in Hz being in the above range indicates that charge stagnation is unlikely to occur on the low frequency side. When measuring the impedance while applying a low frequency voltage, it can be assumed that the impedance is simulated based on the amount of charge movement in a state where the movement of the charge can follow the voltage oscillation. In other words, when the frequency is 1.0 × 10 －１The impedance in Hz can be used as an index of the ease of charge transfer between the elastic roller and the measurement electrode. The AC voltage used to measure the impedance under condition (1) has an amplitude of 1 V. This AC voltage for measurement is significantly lower than the voltages actually applied to elastic rollers in electrophotographic image forming apparatuses, which are several hundred to several thousand volts. Therefore, it is believed that measuring the impedance under condition (1) allows for a higher-level evaluation of the ease with which discharge occurs from the surface of the elastic roller.

[0019] Impedance is 1.0 x 10 ３ If the impedance is less than 1.0×10 Ω, the volume resistivity of the conductive layer is low and abnormal discharge is likely to occur. Therefore, it may be difficult to use the elastic roller as a charging roller. ８ If the frequency exceeds 1.0×10 Ω, the volume resistance of the conductive layer becomes high and charging failures tend to occur. Therefore, it becomes difficult to use the elastic roller as a charging roller. －１ The absolute value of the impedance in Hz is 1.0 x 10 ３ ~5.0 x 10 ７ Ω, and preferably 1.0×10 ３ ~1.0 x 10 ６ It is more preferable that it is Ω.

[0020] <Method for Measuring Impedance> Impedance can be measured by the following method. When measuring impedance, it is necessary to eliminate the influence of contact resistance between the elastic roller and the measurement electrode. To do this, a low-resistance thin film is deposited on the surface of the elastic roller, and this thin film is used as an electrode. Then, the conductive support is used as a ground electrode, and the impedance is measured using two terminals.

[0021] Examples of the method for forming the thin film include metal deposition, sputtering, application of a metal paste, application of a metal tape, etc. Among these, from the viewpoint of reducing the contact resistance with the elastic roller, a method for forming a metal thin film such as platinum or palladium as an electrode by deposition is preferred.

[0022] When forming a metal thin film on the surface of an elastic roller, it is preferable to provide a vacuum deposition apparatus with a mechanism for gripping the elastic roller, considering the ease of the process and the uniformity of the thin film. For elastic rollers with a cylindrical cross section, it is preferable to use a vacuum deposition apparatus that also includes a rotation mechanism. For elastic rollers with a curved cross section, such as a cylindrical elastic roller, it is difficult to connect the metal thin film serving as the measurement electrode to the impedance measurement device, so it is preferable to use the following method.

[0023] Specifically, a thin metal film electrode approximately 10 mm to 20 mm wide is formed in the longitudinal direction of the elastic roller, and then a metal sheet is tightly wrapped around the elastic roller. The metal sheet is then connected to a measurement electrode extending from a measuring device for measurement. This allows the measuring device to conveniently acquire an electrical signal from the conductive layer of the elastic roller, enabling impedance measurement. Any metal sheet can be used as the metal sheet, as long as it has an electrical resistance equivalent to that of the metal part of the connecting cable of the measuring device when measuring impedance. For example, aluminum foil, metal tape, etc. can be used.

[0024] The impedance measuring device is an impedance analyzer, a network analyzer, a spectrum analyzer, etc. ７ Any device capable of measuring impedance in a frequency range up to 100 Hz may be used. Among these, it is preferable to measure the impedance using an impedance analyzer, since it is in the range of the electrical resistance of the elastic roller.

[0025] The conditions for measuring impedance are as follows: An impedance measuring device was used, and a value of 1.0 x 10 －１The impedance is measured at a frequency of 100 Hz. The measurement is performed in an environment with a temperature of 23°C and a humidity of 50% RH. The measurement points are the center of the conductive layer in the longitudinal direction, and three points at a distance of L / 4 from both ends of the conductive layer toward the center, where L is the longitudinal length of the conductive layer. The arithmetic mean of the measurements at these three points can be calculated. The amplitude of the AC voltage is 1 V. Regarding the measurement voltage, measurements may be performed while applying a DC voltage, taking into account the shared voltage applied to the elastic roller in the electrophotographic device. Specifically, measurements while applying a DC voltage of 10 V or less superimposed on an AC voltage are suitable for quantifying the characteristics of charge transport and accumulation. Furthermore, measurements may be performed by forming a 1.5 cm wide metal film by a method such as vacuum deposition at the three measurement points, and providing measurement electrodes.

[0026] To set the absolute value of the impedance within the above range, for example, the volume fraction of the domains filled with conductive particles in the matrix domain structure can be adjusted. As the volume fraction increases, the impedance tends to decrease. Conversely, as the volume fraction decreases, the impedance tends to increase.

[0027] The volume fraction of the domain in the matrix domain structure is preferably 10 to 40% by volume, more preferably 15 to 40% by volume, and even more preferably 20 to 40% by volume. Within this range, the absolute value of the impedance is easily kept within the above range. For example, if the volume fraction exceeds 40% by volume, the frequency will be 1.0 × 10 －１ The absolute value of the impedance in Hz is 1.0 x 10 ３ Furthermore, if the volume fraction is less than 10% by volume, the absolute value of the impedance tends to be less than 1.0×10 ８ It is easy to exceed Ω.

[0028] <Method for Measuring Domain Volume Fraction> The domain volume fraction is determined by measuring the conductive layer in three dimensions using an FIB-SEM. FIB-SEM is a technique in which a sample is processed using a focused ion beam (FIB) device and the exposed cross section is observed using a scanning electron microscope (SEM). To investigate the three-dimensional structure, a large number of photographs are obtained by repeating successive processing and observations, and then the SEM images are subjected to 3D reconstruction processing using computer software to construct a three-dimensional image of the sample structure.

[0029] A specific method for measuring the domain volume fraction involves obtaining a three-dimensional stereoscopic image using a FIB-SEM (manufactured by FEI Corporation) and calculating the volume fraction from the image. Sampling of the conductive layer is performed at three locations: the center of the conductive layer in the longitudinal direction, and three locations at L / 4 from both ends of the conductive layer toward the center, at depths of 0.3T, 0.6T, and 0.9T from the outer surface of the conductive layer toward the support, where L is the longitudinal length of the conductive layer and T is the thickness of the conductive layer. Sampling is performed so that a surface perpendicular to the conductive support is exposed. A total of nine cubic samples with sides of 9 μm are obtained. Three-dimensional measurements are then performed on the obtained samples using the FIB-SEM. To facilitate observation of the domain structure, a pretreatment is performed to obtain favorable contrast between the domain and the matrix. A staining treatment is preferably used here. Specifically, osmium tetroxide, ruthenium tetroxide, tungstophosphoric acid, or the like can be mentioned, and a dye that can distinguish the first rubber from the second rubber is selected.

[0030] The obtained image is then analyzed using 3D visualization and analysis software Avizo (registered trademark, manufactured by F.E.I. Co., Ltd.) to divide one 9 μm-side cubic sample into 27 unit cubes, each with a side length of 3 μm. The volume Vd of the domain contained in each unit cube is then calculated. The volume Vd and the volume of the sample are then used to calculate the volume fraction of the domains in each sample. The same calculation is performed for the 27 samples, and the arithmetic mean value of the resulting volume fractions is taken as the volume fraction of the domains.

[0031] <Condition (2)> When the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, at least eight of nine cubic samples each 9 μm on a side are sampled at three locations: the center of the conductive layer in the longitudinal direction, and three locations spaced at L / 4 from both ends of the conductive layer toward the center, at depths of 0.3T, 0.6T, and 0.9T from the outer surface of the conductive layer toward the support, and at least eight of the nine samples satisfy the following: When one sample is divided into 27 unit cubes each 3 μm on a side, and the volume Vd of the domain contained in each unit cube is determined, Vd is 2.7 to 10.8 μm ３ There are at least 20 unit cubes where

[0032] The above conditions mean that when 27 unit cubes with a side length of 3 μm are produced, 20 or more (74% or more) of the cubes have domain portions of 10 to 40% by volume. In other words, this means that the domains are arranged three-dimensionally evenly and densely in the conductive layer. Vd is 2.7 to 10.8 μm ３ As the number of unit cubes increases, the domains are more evenly and densely arranged in the conductive layer in three dimensions. ３ The number of unit cubes is preferably 25 or more. There is no particular upper limit to the number of unit cubes, and examples include 20 to 27, and 25 to 27. The number of unit cubes can be adjusted by the volume fraction and dispersion state of the domains. Specifically, the number can be adjusted by the ratio of the matrix and domains that constitute the conductive layer, and the rotation speed and rotation time of the kneading device in the kneading step to form the matrix-domain structure.

[0033] <Measuring method for condition (2)> Vd is 2.7 to 10.8 μm ３ The number of unit cubes having a volume fraction of the domain is measured by calculating the volume Vd of the domain contained in each unit cube using the above-mentioned method for measuring the volume fraction of the domain. ３ This is done by counting the number of unit cubes.

[0034] <Condition (3)> In each domain in a cross section of the conductive layer in the thickness direction, when the average value of the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain is μ (area %) and the standard deviation of this ratio is σ, σ / μ is 0.00 to 0.40 and μ is 20.0 to 40.0 area %.

[0035] σ / μ represents the coefficient of variation of the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain, and a σ / μ of 0.00 to 0.40 indicates little variation in the amount of conductive particles contained in each domain. As a result, when σ / μ is in the above range, the domains have uniform electrical resistance. σ / μ is preferably 0.00 to 0.25, and more preferably 0.00 to 0.20. When σ / μ is in this range, the domains have even more uniform electrical resistance. To reduce σ / μ, one method is to increase the amount of conductive particles contained in each domain. Furthermore, σ / μ can be increased by decreasing the amount of conductive particles contained in each domain. Specific methods for measuring σ / μ are described below.

[0036] As described above, μ is 20.0 to 40.0 area percent. A μ of 20.0 area percent or greater indicates that the conductive particles are densely packed within the domain. This reduces variation in the distance between conductive particles within the domain. As a result, the conductivity of the domain is stable. Furthermore, if μ exceeds 40.0 area percent, the amount of conductive particles within the domain becomes too large, making the conductive particles more likely to protrude from the domain. Protruding conductive particles from the domain connect the domains, creating conductive paths through the connected domains. This reduces the uniformity of the conductive paths and reduces the ability to remove peeling charge remaining on the elastic roller surface. μ is preferably 23.0 to 40.0 area percent, more preferably 28.0 to 40.0 area percent. A μ within this range indicates that the conductive particles are densely packed within the domain. As a result, the external shape of the domain can be made closer to a sphere, resulting in minimal irregularities. Furthermore, even in a configuration in which the domain has a core-shell structure and conductive particles are filled into the shell, the amount of conductive particles is preferably within the above range. The distance between the conductive particles inside the shell can be made uniform, while the phenomenon of the conductive particles protruding from the shell can be suppressed. μ can be adjusted by changing the content of the conductive particles relative to the second rubber contained in the domain.

[0037] In order to obtain a domain in which the conductive particles are densely packed as described above, the conductive particles should have a DBP absorption of 40 to 80 cm ３ Carbon black having a DBP absorption (cm ３ / 100g) is the volume of dibutyl phthalate (DBP) that can be adsorbed by 100g of carbon black, and is measured in accordance with Japanese Industrial Standards (JIS) K6217-4:2017 (Carbon black for rubber - Fundamental properties - Part 4: Determination of oil absorption (including compressed samples)).

[0038] Generally, carbon black has a cluster-like high-order structure in which primary particles with an average particle size of 10 nm to 50 nm are aggregated. This cluster-like high-order structure is called a structure, and its degree is expressed by the DBP absorption (cm３ The DBP absorption is quantified in units of 1 / 100g. Conductive carbon black with a DBP absorption within the above range has an underdeveloped structure, resulting in less carbon black aggregation and good dispersibility in rubber. This allows for a larger loading amount in the domain, which in turn makes it easier to obtain domains with an outer shape closer to a sphere. Furthermore, conductive carbon black with a DBP absorption within the above range is effective because it is less likely to form aggregates.

[0039] Among conductive particles, conductive particles containing conductive carbon black as a main component are preferred for reasons such as high conductivity, high affinity with rubber, and ease of controlling the distance between conductive particles. The type of conductive carbon black to be blended into the domain is not particularly limited. Specific examples include gas furnace black, oil furnace black, thermal black, lamp black, acetylene black, and ketjen black. More specific details will be described later.

[0040] Hereinafter, details of the elastic roller for carrying out the present disclosure will be described in detail with reference to the drawings, but the present disclosure is not limited thereto.

[0041] <Elastic Roller> The elastic roller and the recycled elastic roller can be used as an elastic roller for an electrophotographic apparatus used in an electrophotographic image forming apparatus, and specifically, the elastic roller can be used as a developing roller, a charging roller, a transfer roller, a fixing roller, a cleaning roller, etc.

[0042] An example of a recycled elastic roller is shown in Figure 7. Note that a recycled elastic roller is an elastic roller that has had developer, external additives, and other contaminants adhered to its surface due to image formation or the like removed, and therefore an elastic roller without any contaminants adhered to its surface has the same configuration as a recycled elastic roller. Below, the configuration of an elastic roller will be described using a recycled elastic roller as an example.

[0043] 7 is a cross-sectional view showing the cross-sectional configuration of the elastic roller 70 taken perpendicular to the longitudinal direction, which is the axial direction. The elastic roller 70 has a cylindrical support 71 having a conductive outer surface, and a conductive layer 72 provided on the outer peripheral surface of the support 71, i.e., on the outer surface of the support. However, the shape of the support in the elastic roller is not particularly limited. The conductive layer 72 may be a single-layer structure, a two-layer structure having a conductive resin layer on the outer surface, or a multi-layer structure having three or more layers.

[0044] <Support> The material constituting the support 71 can be appropriately selected from materials known in the field of electrophotographic conductive members and materials usable as conductive members. Examples include metals or alloys such as aluminum, stainless steel, conductive synthetic resins, iron, and copper alloys.

[0045] Furthermore, these may be subjected to an oxidation treatment or a plating treatment with chromium, nickel, or the like. As the type of plating, either electroplating or electroless plating can be used. Electroless plating is preferred from the viewpoint of dimensional stability. Examples of the electroless plating used here include nickel plating, copper plating, gold plating, and various other alloy platings. Of these, electroless nickel plating is preferred. The plating thickness is preferably 0.05 μm or more, and considering the balance between work efficiency and rust prevention ability, the plating thickness is preferably 0.10 μm or more and 30.00 μm or less.

[0046] The cylindrical support 71 may have a solid cylindrical shape or a hollow cylindrical shape. The outer diameter of the support is preferably 3 mm or more and 10 mm or less. The length of the support in the longitudinal direction is not particularly limited, but is preferably, for example, 200 mm or more and 300 mm or less. Furthermore, if necessary, the support may be partially processed for installation in an electrophotographic apparatus.

[0047] The conductive layer is preferably provided directly on the support in a manner that it is in contact with the support. Another preferred embodiment is to provide the conductive layer on the outer surface of the support via an intermediate layer made of a conductive resin layer such as a primer layer. The primer layer is more preferably a thin film.

[0048] As the primer, a known material can be selected and used depending on the rubber material for forming the conductive layer and the material of the support. Examples of the primer material include thermosetting resins and thermoplastic resins, and specific examples of known materials that can be used include phenolic resins, urethane resins, acrylic resins, polyester resins, polyether resins, and epoxy resins. Among these, phenolic resins are preferred, and for example, Metalock U-20 (manufactured by Toyo Kagaku Kenkyusho Co., Ltd.) can be used.

[0049] <Conductive Layer> The elastic roller has a conductive layer on the outer surface of the support. The conductive layer may be a conductive elastic layer. The outer surface of the conductive layer preferably corresponds to the outer surface of the elastic roller. The conductive layer has a matrix containing a first rubber and domains containing a second rubber and conductive particles. The matrix and domains form a phase-separated structure. That is, the conductive layer has a matrix-domain structure having a plurality of domains dispersed in the matrix.

[0050] For example, the first rubber that forms the matrix is ​​the component with the highest blending ratio in the rubber composition for forming the conductive layer, and is present between domains, preventing the existence of uneven conductive paths that directly connect the domains.

[0051] It is preferable to use a rubber with good dispersibility of conductive particles for the second rubber forming the domain, and to disperse the conductive particles therein. This is because uniform dispersion of the conductive particles in the rubber can impart excellent electrical properties. When the domain contains conductive particles and the elastic roller satisfies the above-mentioned condition (3), uniform conductivity can be obtained that is not dependent on variations in the distance between the conductive particles.

[0052] The conductive layer may contain a rubber other than the first rubber and the second rubber as long as the effects of the present disclosure are not impaired. In this case, the top two rubbers in terms of content, in no particular order, are designated as the first rubber and the second rubber. For example, the conductive layer may contain a third rubber other than the first rubber and the second rubber.

[0053] In the present disclosure, a phase-separated structure containing three or more rubber components, having a core-shell domain configuration in a matrix, and in which the matrix and domains are formed from a first rubber and a second rubber, respectively, is also referred to as a matrix-domain structure. For example, the domain may include a core containing a second rubber and an electronic conductive agent, and a shell of a third rubber. When the third rubber is used as the shell, for example, the third rubber may be selected to have an SP value closer to that of the first rubber than that of the second rubber.

[0054] <Volume Resistivity of Matrix> The matrix containing the first rubber has a volume resistivity of 1.0×10 ８ ~1.0 x 10 １７ Ω cm. The volume resistivity is 1.0 × 10 ８ If the volume resistivity is less than Ω·cm, the matrix begins to contribute to the conductivity, preventing uniform conductivity due to the domains filled with conductive particles. １７ If the resistivity exceeds Ω·cm, the volume resistivity of the conductive layer becomes high, making it difficult to obtain sufficient discharge for image formation. １０ ~1.0 x 10 １７ Preferably, the resistance is Ω cm, and 1.0×10 １２ ~1.0 x 10 １７ It is more preferable that the volume resistivity of the matrix is ​​in the above range by using, for example, a rubber material having a volume resistivity in the above range.

[0055] <Method for measuring volume resistivity of matrix> The volume resistivity of the matrix can be measured by cutting the elastic roller into a thin slice and bringing a microprobe of a scanning probe microscope (SPM) or an atomic force microscope (AFM) into contact with the matrix in the thin slice. Specific measurement methods are shown below.

[0056] Examples of means for thinning include a sharp razor, a microtome, and an FIB. In this disclosure, a microtome is used. When preparing the thin sections, it is necessary to eliminate the influence of the domains and measure the volume resistivity of only the matrix. Therefore, a thin section with a thickness smaller than the interdomain distance measured in advance using a SEM or TEM is prepared. Therefore, a microtome is used as a means for thinning. The elastic roller is divided into four regions in the circumferential direction and five regions in the longitudinal direction, and a sample is taken from the center of each region. Then, 20 thin section samples are obtained.

[0057] To measure the volume resistivity, first, one side of the obtained flake sample is grounded. Next, a microprobe 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 flake, and a DC voltage of 50 V is applied for 5 seconds. The ground current value measured for 5 seconds is used to calculate the arithmetic mean value, and the applied voltage is divided by this calculated value to calculate the electrical resistance value. Finally, the resistance value is converted to volume resistivity using the film thickness of the flake. At this time, the SPM or AFM can measure the film thickness of the flake simultaneously with the resistance value.

[0058] <First Rubber> A specific example of the first rubber is preferably 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), chloroprene rubber (CR), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), silicone rubber, and urethane rubber (U).

[0059] The first rubber is more preferably at least one selected from the group consisting of isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), and ethylene propylene diene rubber (EPDM), still more preferably at least one selected from the group consisting of isoprene rubber (IR), styrene butadiene rubber (SBR), and acrylonitrile butadiene rubber (NBR), and particularly preferably at least one selected from the group consisting of styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR).

[0060] <Volume Resistivity of Domain> The volume resistivity of the domain is not particularly limited, but is preferably 1.0×10 １ ~1.0 x 10 ４ Preferably, the resistance is 5.0 to 10 Ω·cm. １ ~1.0 x 10 ３ It is more preferable that the volume resistivity of the domain is within this range. When the volume resistivity of the domain is within this range, the charge transport path can be more effectively limited to a path passing through multiple domains. In addition, it becomes easier to increase the amount of charge moving within the domain. The volume resistivity of the domain can be adjusted by changing the volume resistivity of the second rubber contained in the domain or by changing the type and amount of conductive particles contained in the domain.

[0061] <Method for Measuring Volume Resistivity of Domain> The method for measuring the volume resistivity of the domain is the same as the method for measuring the volume resistivity of the matrix described above, except that the position where the microprobe comes into contact is changed to the position of the domain.

[0062] <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), chloroprene rubber (CR), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), silicone rubber, and urethane rubber (U).

[0063] The second rubber more preferably contains at least one selected from the group consisting of isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), and ethylene propylene diene rubber (EPDM), and further preferably contains at least one selected from the group consisting of isoprene rubber (IR), styrene butadiene rubber (SBR), and acrylonitrile butadiene rubber (NBR). Furthermore, the second rubber is preferably different from the first rubber.

[0064] The first rubber and the second rubber are preferably, for example, any of the following combinations: The first rubber is acrylonitrile butadiene rubber (NBR) and the second rubber is styrene butadiene rubber (SBR). The first rubber is acrylonitrile butadiene rubber (NBR) and the second rubber is isoprene rubber (IR). The first rubber is styrene butadiene rubber (SBR) and the second rubber is acrylonitrile butadiene rubber (NBR).

[0065] The mass ratio of the second rubber to the first rubber in the conductive layer (second rubber:first rubber) is preferably 10:90 to 40:60, and more preferably 20:80 to 40:60.

[0066] <Third Rubber> The third rubber is not particularly limited as long as it can form a matrix domain structure, and the rubber materials described in the first rubber section or the second rubber section can be used. The third rubber preferably contains BR. The content of the third rubber is, for example, 1 to 25 parts by mass or 5 to 20 parts by mass per 100 parts by mass of the first rubber.

[0067] <Electron Conductive Agent> The conductive layer may contain a known electron conductive agent. The electron conductive agent is preferably conductive particles. Examples of electron conductive agents include: fine particles and fibers of metals such as aluminum, palladium, iron, copper, and silver; metal oxides such as titanium oxide, tin oxide, and zinc oxide; composite materials in which the surfaces of the above-mentioned metal fine particles, fibers, and metal oxides are surface-treated by electrolysis, spray coating, or mixing and shaking; carbon black and carbon-based fine particles. The conductive particles are preferably carbon black.

[0068] Examples of carbon black include black furnace black, thermal black, acetylene black, and ketjen black. Examples of furnace black include SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, I-ISAF-HS, HAF-HS, HAF, HAF-LS, T-HS, T-NS, MAF, FEF, GPF, SRF-HS-HM, SRF-LM, ECF, and FEF-HS. Examples of thermal black include FT and MT. Examples of carbon-based fine particles include PAN (polyacrylonitrile)-based carbon particles and pitch-based carbon particles.

[0069] The inclusion of such an electronic conductive agent or conductive particles makes it easier to set the impedance of the elastic roller within the above range. Furthermore, the rubber composition for forming the conductive layer may contain, as needed, fillers, processing aids, crosslinking aids, crosslinking accelerators, crosslinking accelerator aids, crosslinking retarders, softeners, plasticizers, dispersants, and the like, which are commonly used as compounding agents for rubber.

[0070] <Arithmetic mean value of equivalent circle diameters of domains (domain size)> The arithmetic mean value μd of the equivalent circle diameters of domains is preferably 0.20 to 4.00 μm. More preferably, it is 0.20 to 2.00 μm. μd represents the size of the domain. Hereinafter, the arithmetic mean value of the equivalent circle diameters of domains is also referred to as domain size. By setting the domain size to 0.20 μm or more, the uniformity of the domain size tends to be stabilized, and the anti-static effect tends to be exhibited. On the other hand, by setting the domain size to 4.00 μm or less, the migration of conductive particles from the domains to the matrix tends to be suppressed. Furthermore, it tends to suppress the decrease in conductivity uniformity due to aggregation between domains. The domain size is measured by the following method.

[0071] <Method for Measuring Domain Size> The domain size is measured as follows. First, 20 thin section samples are prepared using the same method as in the measurement of the volume resistivity of the matrix described above. Next, fracture surfaces can be formed by means of freeze fracture, cross polishing, focused ion beam (FIB), or the like. Considering the smoothness of the fracture surface and pretreatment for observation, the FIB method is preferred. Furthermore, in order to properly observe the matrix domain structure, pretreatment is performed, such as dyeing or vapor deposition, to obtain a favorable contrast between the matrix and the domains. Here, dyeing is preferably used. Specifically, osmium tetroxide, ruthenium tetroxide, tungstophosphoric acid, or the like can be used, and a dye that can distinguish the first rubber from the second rubber is selected.

[0072] The thin section after the fracture surface formation and pretreatment is observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Among these, observation using an SEM at 1,000x to 100,000x magnification is preferred due to the accuracy of quantifying the area of ​​the conductive phase. The domain size is obtained by quantifying the captured image obtained by the above observation. The fracture surface image obtained by SEM observation is converted to 8-bit grayscale using image processing such as ImageProPlus (product name, manufactured by MediaCybernetics), resulting in a monochrome image with 256 gradations. Next, the image is inverted to white so that the domains within the fracture surface appear white, resulting in a binarized image. Next, a count function is used to select domains within the binarized image. The circle-equivalent diameter is calculated from the arithmetic mean value of the area values ​​of the domains selected within the binarized image. The same measurement was performed on 20 flake samples, and the arithmetic mean value of the equivalent circle diameters was calculated to obtain the domain size. The standard deviation σd of the arithmetic mean value of the equivalent circle diameters of the domains was also calculated, and the σd / μd ratio described below was calculated.

[0073] <Domain Size Control Method> In a matrix domain structure, it is preferable that the domains are uniform. An example of a state in which the domains are uniform is a state in which there is little bias in the arrangement of the domains in the matrix. For example, when there are a large number of unit cubes in which Vd is a predetermined value, there is likely to be little bias in the arrangement of the domains. Another example of a state in which the domains are uniform is a state in which there is little variation in the cross-sectional area of ​​the domains. The state in which there is little variation in the cross-sectional area of ​​the domains will be described later. Having uniform domains makes it possible to uniformize the remaining peel charge during the regeneration process, making it easier to suppress the re-adhesion of contaminants.

[0074] Regarding the dispersed particle diameter (domain size) D when two immiscible polymers are melt-kneaded, the Taylor formula, Wu's empirical formula, and Tokita's formula shown in the following formulas (1) to (4) have been proposed. Taylor's formula: D = (C σs / ηm γ) (ηd + ηm) / (19 / 4ηd + ηm) (1) Wu's empirical formula: γ D ηm / σs = 4 (ηd / ηm) 0.84 ηd / ηm > 1 (2) γ D ηm / σs = 4 (ηd / ηm) - 0.84 ηd / ηm < 1 (3) Tokita's formula In the formulas (1) to (4), D: domain size, C: constant, σs: interfacial tension, ηm: viscosity of the matrix, ηd: viscosity of the domain, γ: shear rate, η: viscosity of the mixed system, P: probability of collision and coalescence, φ: domain phase volume, and EDK: domain phase cleavage energy.

[0075] As shown in the above formula, it is effective to control the domain size and interdomain distance required for the formation of uniform domains by controlling the following four factors (a) to (d): (a) the difference in interfacial tension σs between the domain and the matrix (b) the ratio (ηm / ηd) of the viscosity of the domain (ηd) to the viscosity of the matrix (ηm) (c) the shear rate (γ) during mixing and the amount of energy during shear (EDK) (d) the volume fraction of the domain in the conductive layer

[0076] (a) Difference in interfacial tension σs between domain and matrix Interfacial tension tends to correlate with the difference in SP value between the domain and matrix. Therefore, it can be controlled by selecting the materials of the first rubber and the second rubber. Specifically, it is possible to reduce the interfacial tension by reducing the difference in SP value. The absolute value of the difference between the SP value of the first rubber and the SP value of the second rubber is not particularly limited, but is preferably 0.0 to 1.0, more preferably 0.1 to 0.6, and even more preferably 0.1 to 0.5. The SP value of the first rubber is not particularly limited, but may be 16.0 to 19.0, or may be 16.5 to 18.0. The SP value of the second rubber is not particularly limited, but may be 15.5 to 19.0, or may be 16.0 to 18.0. The SP value of the third rubber is not particularly limited, but may be 16.0 to 19.0, or may be 16.5 to 18.0.

[0077] (b) Ratio (ηm / ηd) of viscosity of domain (ηd) to viscosity of matrix (ηm) The closer ηm / ηd is to 1, the smaller the domain size can be. The viscosity ratio of the second rubber, which is the domain raw material, to the second rubber, which is the matrix raw material, can be adjusted by selecting the Mooney viscosity of the rubber raw material and by blending the type and amount of filler. It can also be adjusted by adding a plasticizer such as paraffin oil to an extent that does not interfere with the formation of a phase separation structure. The viscosity ratio can also be adjusted by adjusting the temperature during kneading. The viscosity of the domain and matrix can be obtained by measuring the Mooney viscosity ML(1+4) at the rubber temperature during kneading according to JIS K6300-1:2013. It may also be substituted with the catalog value of the raw rubber.

[0078] (c) Shear rate (γ) during mixing and energy amount during shear (EDK) The faster the shear rate and the greater the energy amount during shear, the smaller the domain size can be. The shear rate during mixing and the energy amount during shear can be controlled by the rotation speed during rubber kneading and the feed rate during extrusion molding. Specifically, the shear rate during mixing / the energy amount during shear can be increased by increasing the rotation speed and kneading time during rubber kneading and the feed rate during extrusion molding.

[0079] (d) Volume Fraction of Domains in the Conductive Layer The volume fraction of domains in the conductive layer tends to correlate with the probability of collision and coalescence between domains and the matrix. Specifically, increasing the volume fraction of domains in the conductive layer can increase the probability of collision and coalescence between domains and the matrix.

[0080] <Domain Size Uniformity> When the arithmetic mean value of the circle-equivalent diameters of the domains is μd (μm) and the standard deviation of the arithmetic mean value is σd (μm), it is preferable that μd is 0.20 to 2.00 μm and σd / μd is 0.00 to 0.40. When μd is in the above range, the domains are suitably separated by the matrix, making it easier to achieve a state in which the domains are not connected to each other. Furthermore, σd / μd being in the above range indicates that the circle-equivalent diameters of the domains are uniform. In other words, it indicates that the domain size is uniform. μd and σd can be adjusted by the method described in the above-mentioned section on domain size control method. Furthermore, μd and σd are measured by the method described in the above-mentioned section on domain size measurement method.

[0081] <Domain Shape> The present inventors have found that the amount of conductive particles contained in a domain affects the external shape of the domain, i.e., as the loading amount of conductive particles in a domain increases, the external shape of the domain becomes closer to a sphere.

[0082] According to the inventors' investigations, although the reason for this is unclear, domains in which the average value μ of the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain in the thickness direction of the conductive layer is 20 area % or more can have a shape closer to a sphere, which is preferable because it allows for an outer shape that can significantly alleviate the concentration of electron exchange between domains.

[0083] When the arithmetic mean value of the domain perimeters is A and the arithmetic mean value of the domain envelope perimeters is B, A and B preferably satisfy the following formula (5): 1.00≦A / B≦1.10 (5) (A: arithmetic mean value of the domain perimeters, B: arithmetic mean value of the domain envelope perimeters) A / B represents the arithmetic mean value of the ratio of the domain perimeter to the domain envelope perimeter. Here, the envelope perimeter is the perimeter when connecting the convex portions of the domains 61 observed in the observation area, as shown in FIG. 6 . A specific measurement method will be described later.

[0084] The ratio of the domain perimeter to the domain envelope perimeter has a minimum value of 1, and a state of 1 indicates that the domain has a cross-sectional shape with no recesses, such as a perfect circle or ellipse. If these ratios exceed 1.10, the domain will have large irregularities, i.e., anisotropy of the electric field will occur. If A and B satisfy formula (5), this indicates that there are few irregularities on the periphery of the domain. As a result, the outer shape can significantly alleviate the concentration of electron exchange between domains.

[0085] When the perimeter of each domain contained in the conductive layer is a1 and the envelope perimeter of the domain is b1, the number ratio of domains whose a1 and b1 satisfy the following formula (6) may be 35% by number or more, preferably 40% by number or more, more preferably 60% by number or more, even more preferably 70% by number or more, particularly preferably 80% by number or more, and especially preferably 90% by number or more. 1.00≦a1 / b1≦1.10 (6) When the number ratio of domains whose a1 and b1 satisfy the following formula (6) is in the above range, it indicates that there are many domains whose outer shape is closer to a sphere. As a result, the concentration of electron exchange between domains can be significantly alleviated. The upper limit of the number proportion of domains in which a1 and b1 satisfy the following formula (6) is not particularly limited, and may be, for example, 40 to 100% by number, 60 to 100% by number, 70 to 100% by number, 80 to 100% by number, 90 to 100% by number, or 90 to 98% by number. The method for measuring this number proportion will be described later.

[0086] <Method of Measuring Each Parameter Related to Domain Shape> First, slices are prepared using the same method as in the measurement of the volume resistivity of the matrix described above. However, as described below, slices are prepared along a cross section perpendicular to the longitudinal direction of the elastic roller, and the domain shape at the fracture surface of the slice is evaluated. The reason for this is explained below. Figures 5A and 5B show diagrams illustrating the shape of the elastic roller 51 in three dimensions along three axes, specifically the X, Y, and Z axes. In Figures 5A and 5B, the X axis is parallel to the longitudinal direction (axial direction) of the elastic roller, and the Y and Z axes are perpendicular to the axial direction of the elastic roller. The thickness direction of the conductive layer is defined as the Z axis.

[0087] 5A shows an image of the elastic roller cut out at a cross section 52a parallel to an XZ plane 52. The XZ plane can rotate 360° around the axis of the elastic roller. Considering the state in which the elastic roller is in contact with the photosensitive drum and rotates, repeatedly coming into contact with the photosensitive drum, the cross section 52a parallel to the XZ plane 52 shows the surface that simultaneously comes into contact with the photosensitive drum at a certain timing.

[0088] Therefore, to evaluate the domain shape, which correlates with the electric field concentration in the elastic roller, it is necessary to evaluate a cross section parallel to a YZ plane 53 perpendicular to the axial direction of the elastic roller, which allows evaluation of the domain shape including a certain amount of cross section 52a. For this evaluation, when the length in the longitudinal direction of the conductive layer is L, a total of three cross sections are selected: a cross section 53b at the center in the longitudinal direction of the conductive layer, and two cross sections (53a and 53c) at L / 4 from both ends of the conductive layer toward the center (FIG. 5B).

[0089] Furthermore, with regard to the observation positions of the cross sections 53a to 53c, when the thickness of the conductive layer is T, 15 μm square observation areas are placed at three locations (0.3T, 0.6T, and 0.9T) in the thickness region from the outer surface of each slice to a depth of 0.1T or more and 0.9T or less, and measurements can be taken at a total of nine observation areas.

[0090] The fracture surface can be formed by freeze fracturing, cross polishing, focused ion beam (FIB), or other methods. Considering the smoothness of the fracture surface and pretreatment for observation, the FIB method is preferred. Furthermore, in order to favorably observe the matrix domain structure, pretreatments such as staining and vapor deposition may be performed to favorably obtain contrast between the conductive and insulating phases.

[0091] The matrix domain structure can be observed on the fractured surface and pretreated sections using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Among these, observation with an SEM at 1,000 to 100,000 magnifications is preferred for accurate quantification of the domain area.

[0092] The domain perimeter and envelope perimeter, as well as the average value μ of the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain, and the standard deviation σ of this ratio can be measured by quantifying the photographed images obtained above. For the fracture surface images obtained by SEM observation, image processing such as ImageProPlus (manufactured by MediaCybernetics) is used to extract 15 μm square analysis regions from each of the nine images obtained at each observation position, and 8-bit grayscale conversion is performed to obtain a monochrome image with 256 gradations. Next, the image is inverted to black and white so that the domains within the fracture surface appear white, and then binarized to obtain a binary image for analysis. The first rubber, the second rubber, and the conductive particles exhibit significant differences in the amount of reflected electrons when observed with an electron scanning electron microscope, making it possible to measure the following parameters for analysis:

[0093] <<Method for Measuring Domain Perimeter, Envelope Perimeter, and the Average Value μ of the Ratio of the Cross-Sectional Area of ​​Conductive Particles to the Cross-Sectional Area of ​​the Domains, and the Standard Deviation σ of the Ratio>> The domain perimeter, envelope perimeter, and the average value μ of the ratio of the cross-sectional area of ​​conductive particles to the cross-sectional area of ​​the domains, and the standard deviation σ of the ratio, can be measured by quantifying the binarized image. The counting function of the image processing software ImageProPlus (manufactured by MediaCybernetics) is used to calculate the perimeter a1 of each domain in the image, the envelope perimeter b1 of the domains, the number ratio of domains whose a1 and b1 satisfy the above formula (6), and the ratio of the cross-sectional area of ​​conductive particles to the cross-sectional area of ​​the domains. The arithmetic mean A of the domain perimeter j, the arithmetic mean B of the domain envelope perimeter, the average value μ of the ratio of conductive particles to the cross-sectional area of ​​the domains, and the standard deviation σ of the ratio are then calculated. In addition, the arithmetic mean values ​​A / B and σ / μ of the perimeter ratios of the domains are calculated.

[0094] In the case of a cylindrical elastic roller, where the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, cross sections in the thickness direction of the conductive layer as shown in Fig. 5B are obtained at three locations: the center of the conductive layer in the longitudinal direction, and at L / 4 from both ends of the conductive layer toward the center. For each of the obtained cross sections, the above measurements are made in three 15 µm square regions (0.3T, 0.6T, and 0.9T) in a thickness region from the outer surface of the conductive layer to a depth of 0.1T to 0.9T toward the support, and the thickness is calculated from the arithmetic average of the measured values ​​from a total of nine regions.

[0095] <Roughening Particles> The rubber composition forming the conductive layer may contain spherical particles having a particle diameter in the range of 1 μm to 90 μm. Examples of the spherical particles include at least one selected from the following: phenolic resin particles, silicone resin particles, polyacrylonitrile resin particles, polystyrene resin particles, polyurethane resin particles, nylon resin particles, polyethylene resin particles, polypropylene resin particles, acrylic resin particles, silica particles, and alumina particles. By using such a rubber composition, convex portions derived from the spherical particles can be formed on the outer surface of the conductive layer.

[0096] Examples of methods for mixing these raw materials include a mixing method using a closed type mixer such as a Banbury mixer or a pressure kneader, and a mixing method using an open type mixer such as an open roll.

[0097] The conductive layer can be formed, for example, as follows: An unvulcanized rubber composition for forming the conductive layer is prepared. The unvulcanized rubber composition for forming the conductive layer can be formed, for example, via a method including the following steps (I) to (III). Step (I): A step of preparing an unvulcanized domain composition containing an electronic conductive agent and a first rubber. Step (II): A step of kneading the unvulcanized domain composition and a second rubber to prepare an unvulcanized rubber composition. Step (III): A step of kneading the unvulcanized rubber composition and compounding ingredients to prepare an unvulcanized rubber composition for forming the conductive layer. The mass-based mixing ratio of the first rubber to the second rubber (first rubber:second rubber) in the unvulcanized rubber composition for forming the conductive layer is preferably 10:90 to 15:85. When a third rubber is used, it is preferable to further include the third rubber in step (II).

[0098] Next, a layer of unvulcanized rubber composition for forming a conductive layer is formed on the conductive support. Examples of methods for forming such a rubber composition layer include the following methods (i) to (iii): (i) a method in which the unvulcanized rubber composition is extruded into a tube using an extruder and a core is inserted into the tube; (ii) a method in which the unvulcanized rubber composition is co-extruded into a cylindrical shape around a core using an extruder equipped with a crosshead to obtain a molded product with a desired outer diameter; (iii) a method in which the unvulcanized rubber composition is injected into a mold with a desired outer diameter using an injection molding machine to obtain a molded product. Among these, method (ii) is preferred because it allows for easy continuous production of elastic rollers, requires fewer steps, and is suitable for low-cost production.

[0099] Next, the unvulcanized composition layer is vulcanized. Vulcanization is carried out by heating, and examples of heating devices include hot air oven heating using a gear oven, heat vulcanization using far infrared rays, and steam heating using a vulcanization can. Among these, hot air oven heating and far infrared heating are preferred because they allow continuous production. The surface of the vulcanized rubber layer, i.e., the conductive layer, can also be ground if necessary.

[0100] Methods for grinding the roller surface include, for example, a traverse grinding method in which a grinding stone or roller is moved in the thrust direction of the roller to grind. Another method is a plunge-cut grinding method in which a grinding stone wider than the roller length is cut into the roller without reciprocating while the roller is rotated around the center of the core shaft. The plunge-cut cylindrical grinding method has the advantage that the entire width of the elastic roller can be ground at once, and is more preferable than the traverse cylindrical grinding method because it can shorten the processing time.

[0101] The surface of the elastic roller may be modified to the extent that it does not affect the glass transition temperature of the rubber forming the conductive layer. Surface modification methods include ultraviolet irradiation, electron beam irradiation, plasma treatment, and corona discharge treatment. These surface treatments may also be combined.

[0102] <Contaminant Removal Step> The method for producing a recycled elastic roller includes a peeling step in which an adhesive tape is pressed against the outer surface of the elastic roller to which contaminants have adhered, and then the adhesive tape is peeled off. In the peeling step, the contaminants are removed by pressing and peeling the adhesive tape. The device used in this step can be a known cleaning device that presses an adhesive tape against the outer surface of the elastic roller and then peels off the adhesive tape to remove the contaminants. For example, the device preferably has a mechanism for gripping the support. Before pressing the adhesive tape, the outer surface of the elastic roller may be brought into contact with a flat plate such as a glass plate or a roller to pre-crack the contaminants, and then this step may be performed.

[0103] FIG. 3 is a schematic diagram showing an example of a cleaning device that removes contaminants using adhesive tape. In FIG. 3 , a rotatably supported elastic roller 10 is pressed by a backup roller 32 while the adhesive surface of an adhesive tape 31 is brought into contact with the elastic roller 10, thereby removing contaminants from the surface of the elastic roller 10. The adhesive tape 31 is supported by a guide roller 33 and wound in the direction of arrow 34, ensuring that a fresh adhesive surface always comes into contact with the elastic roller 10. After pressing the adhesive tape against the outer surface of the elastic roller, the pressure of the adhesive tape when pressing the adhesive tape during the peeling process may be 200 to 1000 N / m, preferably 200 to 700 N / mPa, and more preferably 200 to 400 N / mPa. The drawing pressure is the pressure measured as follows: A 30 μm thick SUS plate for drawing is sandwiched between two 30 μm thick SUS plates and inserted into the contact area between the backup roller and the elastic roller. Next, the SUS plate for drawing was pulled, and the force when it was pulled out at a speed of 0.5 cm / sec was measured, and this was converted into a value equivalent to the linear pressure per meter of width of the SUS plate.

[0104] The peeling step is carried out in a state where the charge on the outer surface of the elastic roller due to peeling electrification is removed. This makes it possible to prevent the peeled contaminants from adhering to the elastic roller again due to electrostatic attraction, and makes it possible to efficiently remove the contaminants. There are no particular limitations on the method for achieving this state, but examples include a method of carrying out the peeling step in the following state.

[0105] The mechanism for gripping the support is preferably made of at least one material selected from the group consisting of metal and conductive resin. This makes it easier to connect the support, which has a conductive outer surface of the elastic roller, to ground or an external power source. Examples include metals or alloys such as aluminum, stainless steel, conductive synthetic resin, iron, and copper alloy. The material of the mechanism for gripping the support is preferably the same as the material constituting the support.

[0106] Furthermore, these may be subjected to an oxidation treatment or a plating treatment with chromium, nickel, or the like. As the type of plating, either electroplating or electroless plating can be used. Electroless plating is preferred from the viewpoint of dimensional stability. Examples of the electroless plating used here include nickel plating, copper plating, gold plating, and various other alloy platings. Of these, electroless nickel plating is preferred. The plating thickness is preferably 0.05 μm or more, and considering the balance between work efficiency and rust prevention ability, the plating thickness is preferably 0.10 μm or more and 30.00 μm or less.

[0107] <Grounding when removing adhered material> The peeling step is preferably carried out with the outer surface of the support grounded. This removes the charge on the outer surface of the elastic roller due to peel electrification. Examples of means for grounding the outer surface include a method of grounding the elastic roller by contacting a conductive cable with the gripping portion of the support of the elastic roller, and a method of installing the elastic roller by contacting a conductive cable with the support of the elastic roller. The material constituting the conductive cable may be at least one selected from the group consisting of metals and conductive resins described in the section on the mechanism for gripping the support.

[0108] It is more preferable to carry out the peeling step while applying a potential to the outer surface of the support. For example, a method of connecting the support to an external power source can be used. This method allows for forcible removal of the charge due to peeling. The potential of the peeling charge is often several volts to several hundred volts. Therefore, the peeling step is preferably carried out while the potential of the outer surface of the support is greater than 0 V and less than +200 V, more preferably at +100 to +200 V, and even more preferably at +150 to +200 V. Furthermore, the peeling step is preferably carried out while the potential of the outer surface of the support is greater than -200 V and less than 0 V, more preferably at -200 to -100 V, and even more preferably at -200 to -150 V. The external power source may be a power source capable of outputting a DC voltage of -200 to +200 V. As a result, the ability to remove the charge due to peeling charge is dramatically improved, and re-adhesion of contaminants can be more reliably suppressed.

[0109] Figure 4 is a schematic diagram showing an example of a configuration for removing charge due to peeling electrification. Figure 4A shows one mode in which the outer surface of the support is grounded. A conductive cable 41 is in contact with a gripping portion 42 that grips an elastic roller 40. This grounds the outer surface of the support. Figures 4B and 4C show one mode in which a potential is applied to the outer surface of the support. The conductive cable 41 is in contact with a gripping portion 42 that grips an elastic roller 40. The conductive cable 41 is also connected to an external power source 43. This results in a state in which a potential is applied to the surface of the support.

[0110] The present disclosure will be described below based on examples, but the present disclosure is not limited to these examples.

[0111] The elastic roller was produced using the following materials: <Conductive Layer Forming Materials> <Acrylonitrile Butadiene Rubber NBR> NBR (trade name: Nipol DN401LL, acrylonitrile content: 18%, Mooney viscosity ML （１＋４） 100°C: 32, manufactured by Zeon Corporation, abbreviation: DN401LL) <Styrene butadiene rubber SBR> SBR (trade name: ESBR1507, styrene content: 23.5%, Mooney viscosity ML （１＋４） 100°C: 35, ENEOS Materials Corporation, abbreviation: 1507)

[0112] <Isoprene rubber IR> Isoprene rubber (trade name: Nipol 2200L, Mooney viscosity ML （１＋４） 100°C: 70, manufactured by Zeon Corporation, abbreviation: 2200L) <Butadiene rubber BR> Butadiene rubber (trade name: UBEPOL BR130B, Mooney viscosity ML （１＋４） 100°C: 29, manufactured by Ube Industries, abbreviated name: BR130B)

[0113] <Electronic conductive agent> Carbon black (1) (product name: Toka Black #7270SB, DBP absorption: 62 cm ３ / 100g, manufactured by Tokai Carbon Co., Ltd., abbreviation: #7270) Carbon black (2) (trade name: Toka Black #7360, DBP absorption capacity: 87 cm ３ / 100g, manufactured by Tokai Carbon Co., Ltd., abbreviation: #7360) Carbon black (3) (trade name: Toka Black #5500, DBP absorption capacity: 155 cm ３ / 100g, manufactured by Tokai Carbon Co., Ltd., abbreviation: #5500) Carbon black (4) (trade name: Ketjen Black, DBP absorption capacity: 350 cm ３ / 100g, manufactured by Lion Specialty Chemicals, abbreviated name: EC100J) <Vulcanizing agent> Vulcanizing agent (trade name: SULFAX PMC, sulfur content 97.5%, manufactured by Tsurumi Chemical Industry Co., Ltd., abbreviated name: sulfur)

[0114] <Vulcanization accelerators> Vulcanization accelerator (1) (trade name: Suncerar TBZTD, tetrabenzyl thiuram disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., abbreviation: TBzTD) Vulcanization accelerator (2) (trade name: Noccela TET, tetraethyl thiuram disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., abbreviation: TET) Vulcanization accelerator (3) (trade name: ACCEL CZ, N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Kawaguchi Chemical Industry Co., Ltd., abbreviation: Cz) <Filler> Filler (trade name: Nanox #30, calcium carbonate, manufactured by Maruo Calcium Co., Ltd., abbreviation: #30)

[0115] <Example 1> <Production of Elastic Roller 1> [1-1. Preparation of Unvulcanized Domain Composition 1] The materials of the types and amounts shown in Table 1 were mixed in a pressure kneader to obtain an unvulcanized domain composition 1. The mixing conditions were a filling rate of 70 vol%, a blade rotation speed of 30 rpm, and 18 minutes.

[0116] [1-2. Preparation of Unvulcanized Rubber Composition 1] The materials shown in Table 2 in their types and amounts were mixed in a pressure kneader to obtain Unvulcanized Rubber Composition 1. The mixing conditions were a filling rate of 70 vol%, a blade rotation speed of 30 rpm, and 18 minutes.

[0117] [1-3. Preparation of Unvulcanized 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 unvulcanized rubber composition 1 for forming a conductive layer. An open roll with a roll diameter of 12 inches was used as the mixer. 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.

[0118] [2. Formation of the Conductive Layer] A round bar with a total length of 252 mm and an outer diameter of 6 mm was prepared, the surface of which was made of free-cutting steel and electroless nickel-plated. Next, using a roll coater, an adhesive, Metalock U-20 (trade name, manufactured by Toyo Kagaku Kenkyusho Co., Ltd.), was applied to the entire circumference of the round bar over a range of 230 mm, excluding 11 mm at each end. In this example, the adhesive-coated round bar was used as the conductive support.

[0119] Next, a die with an inner diameter of 10.4 mm was attached to the tip of a crosshead extruder having a mechanism for feeding the conductive support and a mechanism for discharging the unvulcanized rubber roller, and the temperatures of the extruder and the crosshead were adjusted to 80° C., and the conveying speed of the conductive support was adjusted to 60 mm / sec. Under these conditions, unvulcanized rubber composition 1 for forming a conductive layer was fed from the extruder, and the outer periphery of the conductive support was coated with unvulcanized rubber composition 1 for forming a conductive layer in the crosshead, thereby obtaining an unvulcanized rubber roller 1.

[0120] Next, the unvulcanized rubber roller 1 was placed in a hot-air vulcanizing furnace at 170°C and heated for 60 minutes to vulcanize the unvulcanized rubber composition 1, thereby obtaining a roller having a conductive layer formed on the outer periphery of the conductive support. Thereafter, both ends of the conductive layer were cut off to make the longitudinal length of the conductive layer portion 231 mm.

[0121] Next, the surface of the conductive layer was polished with a grindstone to obtain an elastic roller 1 having a diameter of 9.62 mm at positions 90 mm from the center to both ends, a central diameter of 9.7 mm, and a crown amount of 80 μm.

[0122] <Confirmation of the Phase Separation Structure of the Matrix Containing the First Rubber and the Domain Containing the Second Rubber and the Electronic Conductive Agent in the Conductive Layer> The matrix domain structure in the conductive layer was confirmed as follows. Specifically, ultrathin slices with a thickness of 1 μm were cut from a cross section of the conductive layer, including the surface of the elastic roller 1, in the thickness direction using a microtome (trade name: Leica EM FCS, manufactured by Leica Microsystems) at a cutting temperature of -100°C. When cutting the slices, the cross section was oriented perpendicular to the longitudinal direction of the elastic roller, taking into account the direction of charge transport for conductivity. The prepared slices were stained using a staining agent and photographed at 10,000x magnification using a scanning electron microscope (SEM) (trade name: S-4800, manufactured by Hitachi High-Technologies Corporation) to obtain cross-sectional images. Examples of staining agents include osmium tetroxide, ruthenium tetroxide, and phosphotungstic acid. Staining agents that can distinguish the first rubber and the second rubber were selected. In the cross-sectional image, when the domains were not connected to each other and were separated by the matrix, it was determined that the structure had a matrix domain structure. The phase-separated structure consisting of the first rubber and the second rubber in the conductive layer of the elastic roller 1 was a matrix-domain structure, and the carbon black, which is an electronic conductive agent, was present in the domains.

[0123] <Method for forming developer-derived contaminants> The elastic roller 1 obtained above was incorporated into an electrophotographic process cartridge as a charging roller, and an image was output using an electrophotographic image forming apparatus. The electrophotographic image forming apparatus used was an electrophotographic laser printer (product name: LaserJet Pro M203dw, manufactured by HP Corporation), and the electrophotographic process cartridge used was one specifically for this electrophotographic image forming apparatus.

[0124] An electrophotographic process cartridge incorporating the charging roller was left in an environment at a temperature of 15°C and a relative humidity of 10% for 24 hours, and then installed in an electrophotographic apparatus main body in the same environment. Then, 60,000 sheets were continuously output until the developer adhered to the surface of the elastic roller 1, causing uneven density and streaks in images with a print rate of 1%. Next, the charging roller with the developer-derived contaminants adhered thereto was removed, and the surface of the charging roller was observed under an optical microscope, confirming that a large amount of contaminants had adhered to the entire surface of the charging roller. Using the above method, a used elastic roller 1 with developer-derived contaminants adhered thereto was obtained.

[0125] <Contaminant Removal Process> The used elastic roller 1 produced by the above procedure was attached to the device shown in Figure 3. Then, the elastic roller 10 was rotated three times on adhesive tape 31 (product name: Kraft Tape No. 500, manufactured by Sekisui Chemical Co., Ltd.). The pressing force between the backup roller 32 and the elastic roller 10 was set to a drawing pressure of 200 N / m. Next, the elastic roller 10 was removed from the device, and a recycled elastic roller 1 was obtained.

[0126] <Surface Observation After Regeneration> The surface of the regenerated elastic roller 1 was photographed using a laser microscope (product name: Color 3D Laser Microscope VK-8700, manufactured by Keyence Corporation), and the number of contaminants adhering to the surface was counted. Observation was performed over a field of view measuring 1000 μm vertically and 1000 μm horizontally, and the number of adhering toner particles was counted. The fields of view for observation were three points in the longitudinal direction of the regenerated elastic roller 1 (positions 25.5 mm, 115.5 mm, and 205 mm from the end of the conductive layer), and four additional points in the circumferential direction (every 90 degrees in phase) from the three longitudinal points, for a total of 12 points. The arithmetic mean value of the number of contaminants in each field of view was calculated.

[0127] <Image Evaluation After Recycle> When the recycled elastic roller is used as a charging roller, if the removal of contaminants is insufficient, further accumulation of contaminants on the surface of the elastic roller during reuse will cause minute white spots in the image. The recycled elastic roller 1 obtained above was incorporated into an electrophotographic process cartridge as a charging roller, and images were output using an electrophotographic image forming apparatus. The electrophotographic image forming apparatus used was an electrophotographic laser printer (product name: LaserJet Pro M203dw, manufactured by HP Corporation), and the electrophotographic process cartridge used was one specifically designed for this electrophotographic image forming apparatus.

[0128] An electrophotographic process cartridge incorporating a charging roller was left in an environment at a temperature of 15°C and a relative humidity of 10% for 24 hours, and then installed in an electrophotographic apparatus main body in the same environment. A halftone image was then printed on A4-sized paper, and the resulting image was observed visually and with a magnifying glass and evaluated according to the following criteria: "A": No disturbance in the dots in the halftone image was observed even with a magnifying glass. "B": Slight disturbance in the dots in the halftone image was observed with a magnifying glass. "C": Slight white spots were observed visually. "D": White spots were observed visually throughout the entire area. The results are shown in Table 8.

[0129] Examples 2 to 16 Preparation of Elastic Rollers 2 to 12 Elastic rollers 2 to 12 were prepared in the same manner as elastic roller 1, except that the types and amounts of materials shown in Table 4 were used. The physical properties of the obtained elastic rollers 2 to 12 were measured in the same manner as in Example 1. In addition, used elastic rollers 2 to 12 were prepared in the same manner as in Example 1, except that elastic rollers 2 to 12 were used. The used elastic rollers obtained were subjected to the contaminant removal process in the same manner as in Example 1, except that the used elastic rollers used were those shown in Table 5 and the conditions for the contaminant removal process were set as shown in Table 5, thereby obtaining regenerated elastic rollers 2 to 16. Each of the obtained regenerated elastic rollers 2 to 16 was subjected to the evaluation described in Example 1. The results are shown in Table 5. In the table, "matrix domain structure" indicates the presence or absence of a matrix domain structure, "impedance (Ω)" indicates the absolute value of the impedance according to condition (1), "number of unit cubes" indicates the number of unit cubes according to condition (2), μ indicates the average value (area %) of the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain, σ indicates the standard deviation of this ratio, μd indicates the arithmetic mean value (μm) of the equivalent circle diameter of the domain, σd indicates the standard deviation (μm) of this arithmetic mean value, A indicates the arithmetic mean value of the perimeter of the domain, B indicates the arithmetic mean value of the envelope perimeter of the domain, ρM indicates the volume resistivity (Ω cm) of the matrix, ρD indicates the volume resistivity (Ω cm) of the domain, and R indicates the volume fraction (volume %) of the domain in the matrix domain structure.

[0130] Comparative Examples 1 to 7 Elastic rollers A to E were produced in the same manner as elastic roller 1, except that the types and amounts of materials shown in Table 4 were used. The physical properties of the resulting elastic rollers A to D were measured in the same manner as in Example 1. Used elastic rollers A to D were also produced in the same manner as in Example 1, except that elastic rollers A to D were used. The used elastic rollers obtained were subjected to the contaminant removal process in the same manner as in Example 1, except that the used elastic rollers used were those shown in Table 5 and the conditions for the contaminant removal process were set as shown in Table 5, thereby obtaining regenerated elastic rollers C1 to C6. Each of the resulting regenerated elastic rollers C1 to C6 was subjected to the evaluation described in Example 1. The results are shown in Table 7. In the table, "matrix domain structure" indicates the presence or absence of a matrix domain structure, "impedance (Ω)" indicates the absolute value of the impedance according to condition (1), "number of unit cubes" indicates the number of unit cubes according to condition (2), μ indicates the average value (area %) of the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain, σ indicates the standard deviation of this ratio, μd indicates the arithmetic mean value (μm) of the equivalent circle diameter of the domain, σd indicates the standard deviation (μm) of this arithmetic mean value, A indicates the arithmetic mean value of the perimeter of the domain, B indicates the arithmetic mean value of the envelope perimeter of the domain, ρM indicates the volume resistivity (Ω cm) of the matrix, ρD indicates the volume resistivity (Ω cm) of the domain, and R indicates the volume fraction (volume %) of the domain in the matrix domain structure.

[0131] In Comparative Examples 1 and 2, the elastic roller did not have a matrix domain structure, so non-uniform peeling charge remained. As a result, there was a lot of re-adhesion. In Comparative Example 3, the peeling charge could not be removed because the roller was not grounded during the contaminant removal process, resulting in a lot of re-adhesion. In Comparative Example 4, the impedance was low, abnormal discharge occurred, and the roller could not be used for durability evaluation. In Comparative Example 5, charging was poor, so the roller could not be used for durability evaluation. In Comparative Example 6, the proportion of the cross-sectional area of ​​conductive particles contained in each domain was small, and the filling amount of conductive particles in the domain was low. As a result, the standard deviation of this proportion increased, and the uniformity of the domain shape was poor. As a result, peeling charge remained, and it was difficult to suppress re-adhesion due to this influence.

[0132] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. Therefore, the following claims are appended to clarify the scope of the present disclosure. This application claims priority based on Japanese Patent Application No. 2024-103380, filed June 26, 2024, the entire contents of which are incorporated herein by reference.

[0133] 10: Elastic roller, 31: Adhesive tape, 32: Backup roller, 33: Guide roller, 70: Elastic roller, 71: Support, 72: Conductive layer

Claims

1. A method for producing a recycled elastic roller, comprising a contaminant removal step of removing contaminants adhering to the outer surface of an elastic roller having a support having a conductive outer surface and a conductive layer on the outer surface of the support, wherein the conductive layer has a matrix containing a first rubber and a plurality of domains dispersed in the matrix, and the volume resistivity of the matrix is ​​1.0 x 10 ８ ~1.0 x 10 １７ a conductive domain including a second rubber and conductive particles, and the elastic roller satisfies the following conditions (1), (2), and (3): the contaminant removal step includes a peeling step of pressing an adhesive tape against the outer surface of the elastic roller to which the contaminants are attached, and then peeling off the adhesive tape, and the peeling step is performed in a state in which the charge on the outer surface of the elastic roller due to peeling electrification is removed: Condition (1) A metal film is provided directly on the outer surface of the elastic roller, and an AC voltage with an amplitude of 1 V is applied between the outer surface of the support and the metal film in an environment of a temperature of 23°C and a humidity of 50% RH, with a frequency of 1.0 x 10 －２ ~1.0 x 10 ７ When the impedance was measured by applying a voltage varying between 1.0 x 10 －１ The absolute value of the impedance in Hz is 1.0 x 10 ３ ~1.0 x 10 ８ Condition (2) When the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, at least eight of nine cubic samples each 9 μm on a side are sampled at three locations: the center of the conductive layer in the longitudinal direction, and three locations at a distance of L / 4 from both ends of the conductive layer toward the center, at depths of 0.3T, 0.6T, and 0.9T from the outer surface of the conductive layer toward the support, and at least eight of the nine cubic samples each 9 μm on a side satisfy the following: When one sample is divided into 27 unit cubes each 3 μm on a side, and the volume Vd of the domain contained in each unit cube is determined, Vd is 2.7 to 10.8 μm ３ The number of unit cubes in which μ is the average value of the ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domain in the cross section of the conductive layer in the thickness direction is μ (area %), and the standard deviation of this ratio is σ, where μ / μ is 0.00 to 0.40 and μ is 20.0 to 40.0 area %.

2. The method for producing a recycled elastic roller according to claim 1, wherein the peeling step is carried out with the outer surface of the support in contact with the ground.

3. The method for producing a recycled elastic roller according to claim 1 or 2, wherein the peeling step is carried out in a state where the potential of the outer surface of the support is greater than 0 V and equal to or less than +200 V.

4. The method for producing a recycled elastic roller according to claim 1 or 2, wherein the peeling step is carried out in a state where the potential of the outer surface of the support is −200 V or more and less than 0 V.

5. The method for producing a recycled elastic roller according to any one of claims 1 to 4, wherein the σ / μ is 0.00 to 0.

20.

6. A method for manufacturing a recycled elastic roller according to any one of claims 1 to 5, wherein the arithmetic mean value of the equivalent circle diameters of the domains is μd (μm) and the standard deviation of the arithmetic mean value is σd (μm), μd is 0.20 to 2.00 μm and σd / μd is 0.00 to 0.

40.

7. The method for producing a recycled elastic roller according to any one of claims 1 to 6, wherein the conductive particles are carbon black.

8. A method for manufacturing a recycled elastic roller according to any one of claims 1 to 7, wherein the first rubber and the second rubber are any of the following combinations: the first rubber is acrylonitrile butadiene rubber (NBR) and the second rubber is styrene butadiene rubber (SBR); the first rubber is acrylonitrile butadiene rubber (NBR) and the second rubber is isoprene rubber (IR); the first rubber is styrene butadiene rubber (SBR) and the second rubber is acrylonitrile butadiene rubber (NBR).

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