Method for producing regenerated elastic roller

Abstract

To provide a method for manufacturing a regenerated elastic roller which contributes to good image formation by efficiently removing contaminants sticking to the surface of an elastic roller which is used over a long period of time and to which a large amount of contaminants stick.SOLUTION: A method for producing a regenerated elastic roller, the method including a contaminant removal step of removing contaminants fixed to an outer surface of an elastic roller including a support having an electro-conductive outer surface and an electro-conductive layer on the outer surface of the support, wherein the electro-conductive layer includes a predetermined matrix containing first rubber and a plurality of predetermined domains dispersed in the matrix, and the elastic roller satisfies predetermined conditions (1), (2), and (3), the contaminant removing step includes a peeling step of pressing an adhesive tape against the outer surface of the elastic roller to which the contaminant adheres and then peeling off the adhesive tape, and the peeling step is performed in a state in which electric charges due to peeling electrification of the outer surface of the elastic roller are removed.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Electrophotographic image forming apparatuses use elastic rollers, such as charging rollers, transfer rollers, developing rollers, fixing rollers, and cleaning rollers. As images are produced, 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, requiring replacement as consumable parts. In recent years, in order to reduce environmental impact, there has been an increasing need to develop technologies for recovering used elastic rollers and cleaning and regenerating them by using various cleaning methods. Patent document 1 discloses a method for manufacturing a recycled elastic roller, which includes a step of pressing a pressure roller against an elastic roller that has filming on its surface due to adhesion of developer or the like to cause cracks in the filming, and a step of removing the filming using an adhesive roller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-203832 Summary of the Invention [Problem to be solved by the invention]

[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 also 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 charges occur between the adhesive roller and the recycled elastic roller, and the peeling charges remain unevenly on the surface of the elastic roller, causing 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. [Means for solving the problem]

[0006] The present disclosure provides: A method for producing a recycled elastic roller, 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, the conductive layer has a matrix containing a first rubber and a plurality of domains dispersed in the matrix; The volume resistivity of the matrix is ​​1.0×10 8 ~1.0×10 17 Ω cm, The domain includes a second rubber and conductive particles, 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; The peeling step is carried out in a state where the charge on the outer surface of the elastic roller due to peeling is removed. This invention relates to a method for manufacturing a recycled elastic roller. 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 ~1.0×10 7 When the impedance was measured by applying a voltage varying between 1.0 x 10 -1The absolute value of the impedance in Hz is 1.0 x 10 3 ~1.0×10 8 It is Omega. Condition (2) When the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, the conductive layer is sampled 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, and at three 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 with sides of 9 μm satisfy the following: When one sample is divided into 27 unit cubes each having a side length of 3 μm, and the volume Vd of the domain contained in each unit cube is calculated, Vd is 2.7 to 10.8 μm 3 The number of the unit cubes is at least 20. Condition (3) When 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 thickness direction of the conductive layer is μ (area %) and the standard deviation of the ratio is σ, The σ / μ is 0.00 to 0.40, and the μ is 20.0 to 40.0 area %. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0008] [Figure 1] Conceptual diagram of the phenomenon where peeling charge remains unevenly on the surface of an elastic roller [Figure 2] Schematic diagram of matrix domain structure [Figure 3] Schematic diagram showing an example of a cleaning device for removing contaminants using adhesive tape. [Figure 4] FIG. 1 is a schematic diagram showing an example of a configuration for removing charges due to peeling electrification; [Figure 5] Illustration of cross-section cutting direction [Figure 6] Illustration of envelope perimeter [Figure 7] 1 is a cross-sectional view of an elastic roller according to one embodiment of the present disclosure; DETAILED DESCRIPTION OF THE INVENTION

[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. Peel electrification is a phenomenon in which one object and the other object become charged when two objects in contact are peeled away. For example, in the regeneration method of Patent Document 1, the adhesive roller and the regenerated elastic roller are charged. Furthermore, as the contaminants peel off from the surface of the conductive layer, peel electrification also occurs on the surface of the conductive layer and the surface of the contaminants. At this time, the polarities of the charges generated on the surface of the conductive layer and the surface of the contaminants are opposite. As a result, after the contaminants are peeled off, the surface of the conductive layer The inventors believe that an electrostatic attraction occurs between the charges remaining on the surface and the charges on the contaminants, causing the contaminants to redeposit on the surface of the conductive layer.

[0011] Furthermore, the present inventors have recognized that in conventional elastic rollers, the conductive layer has non-uniform conductivity for the following reasons: It is believed that this non-uniformity causes charges due to peel electrification to remain non-uniformly on the surface of the elastic roller. In conventional elastic rollers, an electronic conductive agent is added to a resin or rubber to impart conductivity to the elastic layer, forming a conductive layer by linking the electronic conductive agent to form a conductive path. When focusing on a single electronic conductive agent in the conductive layer, there is variation in the distance between the single electronic conductive agent and the multiple electronic conductive agent particles surrounding it. As a result, it is thought 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 the removal of contaminants using an adhesive roller, and the movement of charges is restricted, it is believed that a large amount of charge due to peeling 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 charges remaining on the surface of the elastic roller and the charges on the contaminants.

[0012] Figure 1 is a conceptual diagram of the phenomenon in which charge due to peeling remains 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 charge 104 due to peeling remains on the surface 106 of the adhesive roller and on the surface of the contaminants 105. In addition, due to the unevenness of the conductive paths formed by the electronic conductive agent 102 on the surface 101 of the elastic roller, charge 103 due to peeling remains unevenly on the surface 101 of the elastic roller. On the other hand, the right side of Figure 1 shows a state in which an electrostatic attraction is generated between the charge 103 remaining on the surface 101 of the elastic roller and the charge 104 of the contaminant 105, causing the contaminant 105 to re-adhere 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, it is inevitable that the conductive paths will have variations. On the other hand, in the present disclosure, conductive particles as electronic conductive agents are contained within domains, the conductive particles are present in the domains at high density, and the amount of conductive particles contained in each domain is configured to have little variation. Furthermore, by using a matrix domain structure and setting the volume resistivity of the matrix within a predetermined range, it is possible to obtain uniform conductivity 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 state, a certain amount of domains is included in the conductive layer. As a result, the conductive form of the conductive layer becomes a state due to hopping conduction between the 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 this has resulted in a conductive layer in which charge due to peeling electrification does not remain unevenly and can be 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] <How to confirm the 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 the means for cutting out the thin piece include a razor, a microtome, and an FIB. The observation sample is subjected to a treatment (e.g., a dyeing treatment or a vapor deposition treatment) that makes it easy to distinguish between the first rubber phase and the second rubber phase, as necessary. The observation sample is then observed using a laser microscope, SEM, or TEM. More specific procedures will be described later.

[0017] The elastic roller satisfies the following conditions (1) to (3). <Condition (1)> A metal film was directly provided 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 was 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 ~1.0×10 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 ~1.0×10 8 It is Omega.

[0018] The frequency is 1.0×10 -1 The absolute value of the impedance in Hz being within the above range indicates that charge stagnation is unlikely to occur at low frequencies. When measuring impedance while applying a low-frequency voltage, it can be assumed that the impedance is based on the amount of charge movement when the charge can follow the voltage oscillation. That is, the frequency is 1.0×10 -1 The impedance in Hz can be used as an index of the ease with which charges move between the elastic roller and the measurement electrode. Furthermore, the AC voltage used to measure the impedance according to condition (1) has an amplitude of 1 V. This AC voltage for measurement is significantly lower than the voltage of several hundred volts to several thousand volts that is actually applied to an elastic roller in an electrophotographic image forming apparatus. Therefore, it is believed that measuring the impedance according to condition (1) allows for a higher-level evaluation of the likelihood of discharge 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. This may make it difficult to use the elastic roller as a charging roller. 8 If the resistance exceeds Ω, the volume resistivity of the conductive layer becomes high and charging failures tend to occur, making it difficult to use the elastic roller as a charging roller. The frequency is 1.0×10 -1The absolute value of the impedance in Hz is 1.0 x 10 3 ~5.0×10 7 Ω, preferably 1.0×10 3 ~1.0×10 6 It is more preferable that it is Ω.

[0020] <Method of 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 used as an electrode. The conductive support is then used as the 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 mechanism capable of gripping the elastic roller to the vacuum deposition device, in consideration of the ease of the process and the uniformity of the thin film. Therefore, for an elastic roller having a cylindrical cross section, it is preferable to use a vacuum deposition device further equipped with a rotation mechanism. For an elastic roller having a curved cross section such as a circular cross section, for example, a cylindrical elastic roller, it is difficult to connect the metal thin film 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 measurement device for measurement. This allows the measurement device to conveniently acquire an electrical signal from the conductive layer of the elastic roller, enabling impedance measurement. The metal sheet may be any metal sheet that has an electrical resistance equivalent to that of the metal part of the connection cable of the measurement device when measuring impedance; for example, aluminum foil or metal tape can be used.

[0024] The impedance measurement equipment is an impedance analyzer, a network analyzer, a spectrum analyzer, etc., and is 1.0 x 10 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 this is in the range of the electrical resistance of the elastic roller.

[0025] The impedance measurement conditions are as follows: An impedance measurement device was used, and the impedance was measured at 1.0 x 10 -1 The 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 is calculated. The amplitude of the AC voltage is 1V. 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 mentioned above, and providing electrodes for measurement.

[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 can be easily set 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 is likely to be less than 1.0 × 10 8 It is easy to exceed Ω.

[0028] <Method for measuring domain volume fraction> The volume fraction of the domains is determined by measuring the conductive layer in three dimensions using a FIB-SEM. FIB-SEM is a technique in which a sample is processed using a FIB (Focused Ion Beam) device and the exposed cross section is observed using a SEM (Scanning Electron Microscope). To examine the three-dimensional structure, a large number of photographs are taken by repeating the process of processing and observation, and then the SEM images are reconstructed in 3D using computer software to create a three-dimensional image of the sample structure.

[0029] A specific method for measuring the domain volume fraction is to obtain a three-dimensional image using a FIB-SEM (manufactured by FEI Inc.), and then calculate the volume fraction from that image. Sampling of the conductive layer was 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 was performed so that a surface perpendicular to the conductive support was obtained. A total of nine cubic samples with sides of 9 μm were obtained. The obtained sample is then subjected to three-dimensional measurement using FIB-SEM. In order to properly observe the domain structure, a pretreatment is carried out to obtain a good contrast between the domain and the matrix. A staining treatment is preferably used here. Specific examples include osmium tetroxide, ruthenium tetroxide, and phosphotungstic acid, and a staining agent that can distinguish the first rubber from the second rubber is selected.

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

[0031] <Condition (2)> When the longitudinal length of the conductive layer is L and the thickness of the conductive layer is T, a total of nine cubic samples with sides of 9 μm are sampled at three locations: the longitudinal center of the conductive layer, 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. At least eight of the nine samples satisfy the following: When one sample is divided into 27 unit cubes with a side length of 3 μm and the volume Vd of the domain contained in each unit cube is calculated, 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 with a volume ratio of 10 to 40%, which means that the domains are arranged three-dimensionally uniformly 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. 3 The number of unit cubes is preferably at least 25. There is no particular upper limit to the number of unit cubes, and examples thereof 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 by the ratio of the matrix to the domains that constitute the conductive layer, and the rotation speed and rotation time of the kneading device in the kneading step for forming the matrix domain structure.

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

[0034] <Condition (3)> In each domain in the 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 that there is 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. In order to reduce σ / μ, the amount of conductive particles contained in each domain can be increased, and the amount of conductive particles contained in each domain can be decreased to increase σ / μ. A specific method for measuring σ / μ will be described later.

[0036] As described above, μ is 20.0 to 40.0 area %. A μ of 20.0 area % or more 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 %, 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 the ability to remove peeling charge remaining on the elastic roller surface. μ is preferably 23.0 to 40.0 area %, more preferably 28.0 to 40.0 area %. 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 when 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. This makes it possible to make the distance between the conductive particles inside the shell uniform, while also suppressing the phenomenon of the conductive particles protruding from the shell. μ can be adjusted by changing the content of the conductive particles in the second rubber contained in the domain.

[0037] To obtain a domain in which 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 capacity (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 aggregate. This cluster-like high-order structure is called a structure, and its degree is determined by the DBP absorption (cm 3 It is quantified in units of 100g / 100g. Conductive carbon black with DBP absorption within the above range has an underdeveloped structure, resulting in less carbon black aggregation and good dispersibility in rubber. This allows for a larger loading amount in the domain, which in turn makes it easier to obtain domains with a more spherical shape. Furthermore, conductive carbon black with DBP absorption within the above range is effective because it is less likely to form aggregates.

[0039] Among the 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 compounded in the domain is not particularly limited. Specific examples include gas furnace black, oil furnace black, and the like. Examples of suitable black include ness black, thermal black, lamp black, acetylene black, and ketjen black, which will be described in more detail below.

[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 device 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, so an elastic roller with no contaminants adhered to its surface has the same configuration as a recycled elastic roller. Below, the configuration of an elastic roller will be explained using a recycled elastic roller as an example.

[0043] 7 is a cross-sectional view showing the configuration of a cross section perpendicular to the longitudinal direction, which is the axial direction, of elastic roller 70. 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 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 of three or more layers.

[0044] <Support> The material for the support 71 can be appropriately selected from materials known in the field of electrophotographic conductive members and materials usable as conductive members, and can be used. 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. The plating may be either electroplating or electroless plating. Electroless plating is preferred from the viewpoint of dimensional stability. Examples of electroless plating that can be 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 be in the shape of a solid column or a hollow column (cylindrical). 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 in order to mount it on an electrophotographic apparatus.

[0047] The conductive layer is preferably provided directly on the support so as to be 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 suitable resins include plastic resins, specifically known materials such as 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 with multiple 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 that forms the domain, and disperse the conductive particles in it. 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 this disclosure, a phase-separated structure containing three or more rubber components, having a core-shell domain structure 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, a domain may include a core containing a second rubber and an electronic conductive agent, and a shell made 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] <Matrix volume resistivity> The matrix containing the first rubber has a volume resistivity of 1.0×10 8 ~1.0×10 17 Ω·cm. Volume resistivity is 1.0×10 8 Below Ω·cm, the matrix begins to contribute to conductivity, preventing uniform conductivity through 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 ~1.0×10 17 Ω·cm is preferred, and 1.0×10 12 ~1.0×10 17 It is more preferable that the resistivity is Ω·cm. The volume resistivity of the matrix can be set within the above range, for example, by using a rubber material having a volume resistivity within 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 contacting the matrix in the slice with a microprobe of a scanning probe microscope (SPM) or atomic force microscope (AFM). 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 domains and measure the volume resistivity of the matrix alone. Therefore, thin sections with a thickness smaller than the interdomain distance measured in advance using a SEM or TEM are prepared. Therefore, a microtome is used as the 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, thereby obtaining 20 thin sample sections.

[0057] To measure volume resistivity, first ground one side of the obtained flake sample. Next, contact the matrix portion of the surface opposite the grounded surface of the flake with the microprobe of a scanning probe microscope (SPM) or atomic force microscope (AFM), apply a 50 V DC voltage for 5 seconds, measure the ground current value for 5 seconds, calculate the arithmetic mean value, and then divide the applied voltage by this calculated value to calculate the electrical resistance. Finally, the resistance value is converted to volume resistivity using the flake film thickness. At this time, the SPM or AFM can measure the flake film thickness at the same time as the resistance value.

[0058] <First Rubber> Specific examples of the first 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).

[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), even 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 ~1.0×10 4 Ω·cm is preferable, and 5.0 to 10 1~1.0×10 3 It is more preferable that the volume resistivity of the domain is in this range. When the volume resistivity of the domain is in this range, the charge transport path can be more effectively limited to a path that passes through multiple domains. It also makes it easier to increase the amount of charge that moves 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 volume resistivity of the domain is measured in the same manner as in the above-described method for measuring the volume resistivity of the matrix, except that the position where the microprobe is brought into contact is changed to the position of the domain.

[0062] <Second Rubber> Specific examples of the second rubber include 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 (N At least one selected from the group consisting of hydrogenated nitrile rubber (H-NBR), hydrogenated nitrile rubber (H-NBR), silicone rubber, and urethane rubber (U) is preferred.

[0063] The second rubber 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 more preferably contains at least one selected from the group consisting of isoprene rubber (IR), styrene butadiene rubber (SBR), and acrylonitrile butadiene rubber (NBR). 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] <The 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 can contain a known electronic conductive agent. The electronic conductive agent is preferably conductive particles. Examples of electronic 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 microparticles include PAN (polyacrylonitrile)-based carbon particles and pitch-based carbon particles.

[0069] By including such an electronic conductive agent or conductive particles, it becomes 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 required, a rubber compounding agent. Commonly used fillers, processing aids, crosslinking aids, crosslinking accelerators, crosslinking accelerator aids, crosslinking retarders, softeners, plasticizers, dispersants, and the like can be added.

[0070] <Arithmetic mean value of the equivalent circle diameter of the domain (domain size)> The arithmetic mean value μd of the equivalent circle diameters of the 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 domains. Hereinafter, the arithmetic mean value of the equivalent circle diameters of the domains is also referred to as the 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 in the following way.

[0071] <How to measure domain size> The domain size is measured as follows. First, 20 thin section samples are prepared using a method similar to that used to measure the volume resistivity of the matrix. Next, fracture surfaces can be formed using techniques such as freeze fracture, cross polishing, or focused ion beam (FIB). Considering the smoothness of the fracture surface and pretreatment for observation, the FIB method is preferred. Furthermore, to facilitate observation of the matrix domain structure, pretreatments such as staining and vapor deposition are performed to favorably obtain contrast between the matrix and the domains. Here, staining is preferably used. Specifically, osmium tetroxide, ruthenium tetroxide, or phosphotungstic acid can be used, and a staining agent that can distinguish between the first rubber and the second rubber is selected.

[0072] The thin section after 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 1000x to 100,000x magnification is preferred from the perspective of accurate quantification of 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) to obtain a monochrome image with 256 gradations. The image is then inverted to obtain a binary image so that the domains within the fracture surface appear white. A count function is then used to select domains within the binary image. The circle-equivalent diameter is calculated from the arithmetic mean value of the area values ​​of the selected domains within the binary image. Similar measurements are performed on 20 thin section samples, and the arithmetic mean value of the circle-equivalent diameter is calculated to obtain the domain size. The standard deviation σd of the arithmetic mean value of the circle-equivalent diameter of the domains is then calculated, and the σd / μd described below is calculated.

[0073] <Domain size control method> In the 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 where Vd is a predetermined value, there is likely to be little bias in the arrangement of the domains. Furthermore, the state in which the domains are uniform also includes, for example, a state in which there is little variation in the cross-sectional area of ​​the domains, which will be described later. By making the domains uniform, the remaining peel charge during the regeneration process can be made uniform, and the re-adhesion of contaminants can be easily suppressed.

[0074] The dispersed particle diameter (domain size) D when two incompatible polymers are melt-kneaded can be calculated using the Taylor formula, Wu's empirical formula, and Tokita's formula shown in the following formulas (1) to (4). has 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 Ceremony

number

[0075] As shown in the above formula, it is effective to control the domain size and inter-domain distance required for the formation of uniform domains by mainly controlling the following four factors (a) to (d). (a) Difference in interfacial tension σs between the domain and the matrix (b) Ratio of domain viscosity (ηd) to matrix viscosity (ηm) (ηm / ηd) (c) Shear rate during mixing (γ) and energy content during shear (EDK) (d) Volume fraction of the domain in the conductive layer

[0076] (a) Difference in interfacial tension σs between the domain and the matrix The interfacial tension tends to correlate with the difference in SP value between the domain and the matrix. Therefore, it can be controlled by selecting the materials for the first and second rubbers. 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 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 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 16.5 to 18.0.

[0077] (b) Ratio of domain viscosity (ηd) to matrix viscosity (ηm) (ηm / ηd) 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. Alternatively, a plasticizer such as paraffin oil may be added to the mixture to such an extent that the formation of the phase-separated structure is not hindered.The viscosity ratio can 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 in accordance with JIS K6300-1:2013. Alternatively, the catalog value for the raw rubber can be used instead.

[0078] (c) Shear rate during mixing (γ) and energy content during shear (EDK) The faster the shear rate and the greater the amount of energy during shearing, the smaller the domain size can be. The shear rate during mixing and the amount of energy 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 amount of energy 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 the domain in the conductive layer The volume fraction of domains in the conductive layer tends to correlate with the probability of collision and coalescence between the domains and the matrix. Specifically, increasing the volume fraction of domains in the conductive layer can increase the probability of collision and coalescence between the domains and the matrix.

[0080] <Uniformity of domain size> When 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), 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 divided by the matrix, making it easier to obtain a state in which the domains are not connected to each other. Furthermore, when σd / μd is in the above range, it indicates that the circle equivalent diameter of each domain is uniform. In other words, it indicates that the domain size is uniform. μd and σd can be adjusted by the method described above in the section on domain size control method, and μd and σd are measured by the method described above in the 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 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% by 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 transfer between domains.

[0083] When the arithmetic mean value of the perimeter of the domain is A and the arithmetic mean value of the envelope perimeter of the domain is B, it is preferable that A and B satisfy the following formula (5). 1.00≦A / B≦1.10 (5) (A: arithmetic mean value of domain perimeter, B: arithmetic mean value of domain envelope perimeter) 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 domain 61 observed in the observation area, as shown in Figure 6. A specific measurement method will be described later.

[0084] The minimum value for the ratio of the domain perimeter to the domain envelope perimeter is 1, and a ratio of 1 indicates that the domain has a cross-sectional shape with no recesses, such as a perfect circle or ellipse. If this ratio exceeds 1.10, the domain will have significant irregularities, which means that anisotropy of the electric field will occur. If A and B satisfy formula (5), this indicates that the domain has few irregularities on its periphery. As a result, the domain will have an outer shape that can significantly alleviate the concentration of electron exchange between domains.

[0085] In each domain included in the conductive layer, when the perimeter of the domain is a1 and the envelope perimeter of the domain is b1, the proportion of domains in which a1 and b1 satisfy the following formula (6) may be 35% by number or more, preferably 40% by number or more, and more preferably 60% by number or more. It is more preferable that the number of particles is 70% or more, even more preferable that the number of particles is 80% or more, and even more preferable that the number of particles is 90% or more. 1.00≦a1 / b1≦1.10 (6) The ratio of the number of domains in which a1 and b1 satisfy the following formula (6) being within the above range indicates that there are many domains whose external shapes are closer to spheres, which can significantly reduce the concentration of electron transfer between domains. The upper limit of the proportion of the number 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 the number ratio will be described later.

[0086] <Method for measuring each parameter related to domain shape> First, a slice is prepared in the same manner as in the measurement of the volume resistivity of the matrix described above. However, as described below, the slice is 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 will be explained below. 5A and 5B show the shape of the elastic roller 51 in three dimensions, specifically, along three axes, X, Y, and Z. 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 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 that 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 locations are selected: cross section 53b at the center of the conductive layer in the longitudinal direction, 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, measurements can be taken at a total of nine observation areas, with 15 μm square observation areas placed at three locations (0.3T, 0.6T, and 0.9T) in the thickness region of each slice from the outer surface to a depth of 0.1T or more and 0.9T or less.

[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, to facilitate observation of 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 1000x to 100,000x magnification 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 captured 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 the images are converted to 8-bit grayscale to obtain 256-level monochrome images. The images are then inverted to show the domains within the fracture surface in white, and binarized to obtain a binary image for analysis. Because 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, measurements can be made to analyze the following parameters:

[0093] <<Method for measuring the average value μ of the domain perimeter, envelope perimeter, and 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>> 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 domains, and the standard deviation σ of this ratio can be measured by quantifying the above-mentioned binary 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 domain envelope perimeter b1, the number ratio of domains whose a1 and b1 satisfy the above formula (6), and the ratio of the cross-sectional area of ​​the conductive particles to the domains. Then, the arithmetic mean value A of the domain perimeter j, the arithmetic mean value B of the domain envelope perimeter, the average value μ of the ratio of the conductive particles to the cross-sectional area of ​​the domains, and the standard deviation σ of this ratio are calculated. Additionally, the arithmetic mean values ​​A / B and σ / μ of the domain perimeter ratios are calculated.

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

[0095] <Roughening particles> The rubber composition forming the conductive layer may contain spherical particles having a particle diameter ranging from 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 a conductive layer is prepared. The unvulcanized rubber composition for forming a conductive layer can be formed, for example, through a method including the following steps (I) to (III). Step (I): A step of preparing an unvulcanized domain composition including an electronic conductive agent and a first rubber. Step (II): Kneading the unvulcanized domain composition and the second rubber to obtain an unvulcanized rubber composition. A process of preparing. Step (III): A step of kneading the unvulcanized rubber composition and compounding ingredients to prepare an unvulcanized rubber composition for forming a conductive layer. The mixing ratio by mass of the first rubber and 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 an 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 an unvulcanized rubber composition is extruded into a tube using an extruder and a core metal is inserted into the tube; (ii) A method in which an unvulcanized rubber composition is co-extruded into a cylindrical shape around a core bar using an extruder equipped with a crosshead to obtain a molded article having a desired outer diameter; (iii) A method in which an unvulcanized rubber composition is injected into a mold having a desired outer diameter using an injection molding machine to obtain a molded article. Among these, the above method (ii) is preferred because it allows for easy continuous production of elastic rollers, requires a small number of 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] <Contamination removal process> The method for manufacturing 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 cause cracks in the contaminants before carrying out this step.

[0103] 3 is a schematic diagram showing an example of a cleaning device that removes contaminants using adhesive tape. In FIG. 3, an elastic roller 10 is supported so as to be rotatable, and is brought into contact with the adhesive surface of an adhesive tape 31 while being pressed by a backup roller 32. Contaminants on the surface are removed. The adhesive tape 31 is supported by a guide roller 33 and is wound in the direction of the arrow 34 so that a fresh adhesive surface always comes into contact with the elastic roller 10. In the step of pressing the adhesive tape against the outer surface of the elastic roller and then peeling off the adhesive tape, the pressure of the adhesive tape when pressing the adhesive tape 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 is pulled and the force when it is pulled out at a speed of 0.5 cm / sec is measured, and this value is the linear pressure equivalent value converted into force 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. The plating may be either electroplating or electroless plating. Electroless plating is preferred from the viewpoint of dimensional stability. Examples of electroless plating that can be 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 stuck objects> 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 peeling. Examples of means for grounding the outer surface include a method of grounding the outer surface 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. 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, by connecting the support to an external power source, which makes it possible to forcibly remove the charge due to peeling. The peeling electrification potential is often several volts to several hundred volts. Therefore, the peeling step is preferably carried out when the potential of the outer surface of the support is greater than 0 V and equal to or less than +200 V, more preferably +100 to +200 V, and even more preferably +150 to +200 V. Furthermore, the peeling step is preferably carried out when the potential of the outer surface of the support is greater than -200 V and less than 0 V, more preferably -200 to -100 V, and even more preferably -200 to -150 V. The external power supply should be capable of outputting a DC voltage of -200 to +200V. As a result, the performance of removing charges due to peeling is dramatically improved, and re-adhesion of contaminants can be more reliably suppressed.

[0109] FIG. 4 is a schematic diagram showing an example of a configuration for removing charges due to peeling electrification. 4A shows one embodiment 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. 4B and 4C show an embodiment in which a potential is applied to the outer surface of the support. A 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. [Example]

[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 made using the materials shown below. <Conductive layer forming material> <Acrylonitrile butadiene rubber (NBR)> NBR (product name: Nipol DN401LL, acrylonitrile content: 18%, Mooney viscosity ML) (1+4) 100℃: 32, Zeon Corporation, abbreviation: DN401LL) <Styrene butadiene rubber (SBR)> SBR (product name: ESBR1507, styrene content: 23.5%, Mooney viscosity: ML (1+4) 100℃: 35, ENEOS Materials Co., Ltd., abbreviation: 1507)

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

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

[0114] <Vulcanization accelerator> Vulcanization accelerator (1) (trade name: Sancerer 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., abbreviated as TET) Vulcanization accelerator (3) (trade name: ACCEL CZ, N-cyclohexyl-2-benzothiazolyl sulfenamide, manufactured by Kawaguchi Chemical Industry Co., Ltd., abbreviation: Cz) <Filler> Filler (product name: Nanox #30, calcium carbonate, manufactured by Maruo Calcium Co., Ltd., abbreviated name: #30)

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

[0116] [1-2. Preparation of Unvulcanized Rubber Composition 1] The types and amounts of materials shown in Table 2 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. [Table 2]

[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. [Table 3]

[0118] [2. Forming 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 the free-cutting steel bar was electrolessly 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, excluding 11 mm at each end. In this example, the adhesive-coated round bar was used as a 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 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 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 with a conductive layer formed on the outer periphery of the conductive support. After that, 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 in the thickness direction of the conductive layer, including the surface of the elastic roller 1, 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 direction was set perpendicular to the longitudinal direction of the elastic roller, taking into account the direction in which electric charges are transported due to 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, which can distinguish the first rubber and the second rubber from each other. The stain was selected. In the cross-sectional image, when the domains were not connected to each other and were interrupted by the matrix, it was determined to be a matrix domain structure. The phase separation structure of the conductive layer of the elastic roller 1, which is made up of the first rubber and the second rubber, is a matrix-domain structure, and the carbon black, which is an electronic conductive agent, is present in the domains. was.

[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: LaserJetProM203dw manufactured by HP Corporation), and the electrophotographic process cartridge used was one specifically for this electrophotographic image forming apparatus.

[0124] The 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 mounted in the main body of the electrophotographic apparatus in the same environment. 60,000 sheets were then output continuously until the developer adhered to the surface of the elastic roller 1 and density unevenness and image streaks appeared on the image with a printing rate of 1%. Next, the charging roller with the developer-derived stains adhered thereto was taken out, and the surface of the charging roller was observed under an optical microscope, whereupon it was confirmed that a large amount of contaminants had adhered to the entire surface of the charging roller. By the above method, a used elastic roller 1 having developer-derived contaminants attached thereto was obtained.

[0125] <Contamination removal process> The used elastic roller 1 produced by the above procedure was attached to the device shown in Fig. 3. Then, the elastic roller 10 was rotated three times on an 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] <Observation of the surface after restoration> The surface of the recycled 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 adhering contaminants was counted. Observation was performed over a field of view of 1000 μm vertically and 1000 μm horizontally, and the number of adhering toner particles was counted. The observation fields were three points along the longitudinal direction of the recycled elastic roller 1 (25.5 mm, 115.5 mm, and 205 mm from the end of the conductive layer), plus four points circumferentially (every 90 degrees in phase) from the three longitudinal points, for a total of 12 fields. The arithmetic mean value of the number of contaminants in each field of view was calculated.

[0127] <Image evaluation after playback> When a 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 result in tiny white spots on 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: LaserJetProM203dw, manufactured by HP Corporation), and the electrophotographic process cartridge 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 mounted in the main body of an electrophotographic apparatus in the same environment. A halftone image was then printed on an A4-sized piece of paper, and the resulting image was observed visually and with a magnifying glass and evaluated according to the following criteria. "A": No irregularities are observed in the dots in the halftone image even when viewed with a magnifying glass. "B": When viewed through a magnifying glass, slight irregularities can be observed in the dots within the halftone image. "C": Slight white spots are visually observed. "D": White spots are visually observed over the entire area. The results are shown in Table 8.

[0129] <Examples 2 to 16> <Production of Elastic Rollers 2 to 12> Elastic rollers 2 to 12 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 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 produced in the same manner as in Example 1, except that elastic rollers 2 to 12 were used. The used elastic rollers used were those shown in Table 5, and the conditions for the contaminant removal process were set to those shown in Table 5. The used elastic rollers obtained were subjected to the contaminant removal process in the same manner as in Example 1, to obtain 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. [Table 4] [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 ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domains (area %), σ indicates the standard deviation of this ratio, μd indicates the arithmetic mean value (μm) of the equivalent circle diameters of the domains, σd indicates the standard deviation (μm) of this arithmetic mean value, A indicates the arithmetic mean value of the perimeters of the domains, B indicates the arithmetic mean value of the envelope perimeters of the domains, ρM indicates the volume resistivity of the matrix (Ω·cm), ρD indicates the volume resistivity of the domains (Ω·cm), and R indicates the volume fraction (volume %) of the domains in the matrix domain structure.

[0130] <Comparative Examples 1 to 7> Except for using the types and amounts of materials shown in Table 4, elastic rollers A to E were produced in the same manner as elastic roller 1. The physical properties of the obtained elastic rollers A to D were measured in the same manner as in Example 1. In addition, used elastic rollers A to D were 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 listed in Table 5 and the conditions for the contaminant removal process were those listed in Table 5, to obtain regenerated elastic rollers C1 to C6. Each of the obtained regenerated elastic rollers C1 to C6 was subjected to the evaluation described in Example 1. The results are shown in Table 7. [Table 6] [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 ratio of the cross-sectional area of ​​the conductive particles to the cross-sectional area of ​​the domains (area %), σ indicates the standard deviation of this ratio, μd indicates the arithmetic mean value (μm) of the equivalent circle diameters of the domains, σd indicates the standard deviation (μm) of this arithmetic mean value, A indicates the arithmetic mean value of the perimeters of the domains, B indicates the arithmetic mean value of the envelope perimeters of the domains, ρM indicates the volume resistivity of the matrix (Ω·cm), ρD indicates the volume resistivity of the domains (Ω·cm), and R indicates the volume fraction (volume %) of the domains in the matrix domain structure.

[0131] In Comparative Examples 1 and 2, the elastic rollers did not have a matrix domain structure, so non-uniform peeling electrification remained, resulting in a large amount of re-adhesion. In Comparative Example 3, the surface was not grounded during the contaminant removal process, and therefore peeling charge could not be removed, resulting in a large amount of re-adhesion. In Comparative Example 4, the impedance was low and abnormal discharge occurred, so that the durability evaluation could not be carried out, and in Comparative Example 5, charging was insufficient and that the durability evaluation could not be carried out. In Comparative Example 6, the cross-sectional area ratio of the conductive particles in each domain was small, and the filling amount of the conductive particles in the domain was low. As a result, the standard deviation of the ratio 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 its influence.

[0132] The present disclosure includes the following methods. (Method 1) A method for producing a recycled elastic roller, 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, the conductive layer has a matrix containing a first rubber and a plurality of domains dispersed in the matrix; The volume resistivity of the matrix is ​​1.0×10 8 ~1.0×10 17 Ω cm, The domain includes a second rubber and conductive particles, 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; A method for producing a recycled elastic roller, characterized in that the peeling step is carried out 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 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 ~1.0×10 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 ~1.0×10 8 Ω is: Condition (2) When the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, the conductive layer is sampled 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, and at three 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 with sides of 9 μm satisfy the following: When one sample is divided into 27 unit cubes each having a side length of 3 μm, and the volume Vd of the domain contained in each unit cube is calculated, Vd is 2.7 to 10.8 μm 3 There are at least 20 such unit cubes: Condition (3) When 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 thickness direction of the conductive layer is μ (area %) and the standard deviation of the ratio is σ, The σ / μ is 0.00 to 0.40, and the μ is 20.0 to 40.0 area % (Method 2). The method for producing a recycled elastic roller according to Method 1, wherein the peeling step is carried out with the outer surface of the support in contact with the ground. (Method 3) 3. The method for producing a recycled elastic roller according to method 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. (Method 4) The method for producing a recycled elastic roller according to any one of methods 1 to 3, wherein the peeling step is carried out in a state where the potential of the outer surface of the support is −200V or more and less than 0V. (Method 5) 5. The method for producing a recycled elastic roller according to any one of methods 1 to 4, wherein the σ / μ is 0.00 to 0.20. (Method 6) When 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), 6. The method for producing a recycled elastic roller according to any one of Methods 1 to 5, wherein μd is 0.20 to 2.00 μm, and σd / μd is 0.00 to 0.40. (Method 7) 7. The method for producing a recycled elastic roller according to any one of Methods 1 to 6, wherein the conductive particles are carbon black. (Method 8) The method for producing a recycled elastic roller according to any one of Methods 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). [Explanation of symbols]

[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 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, the conductive layer has a matrix containing a first rubber and a plurality of domains dispersed in the matrix; The volume resistivity of the matrix is ​​1.0×10 ８ ~1.0 x 10 １７ Ω cm, The domain includes a second rubber and conductive particles, 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; A method for producing a recycled elastic roller, characterized in that the peeling step is carried out 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 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 Ω is: Condition (2) When the length of the conductive layer in the longitudinal direction is L and the thickness of the conductive layer is T, the conductive layer is 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, and at depths of 0.3T, 0.6T, and 0.9T from the outer surface of the conductive layer toward the support, and the sample is a cube with a side length of 9 μm. At least eight of the nine samples satisfy the following: When one sample is divided into 27 unit cubes each having a side length of 3 μm, and the volume Vd of the domain contained in each unit cube is calculated, Vd is 2.7 to 10.8 μm ３ There are at least 20 such unit cubes: Condition (3) When 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 the ratio is σ, The σ / μ is 0.00 to 0.40, and the 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 , 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. 2. The method for producing a recycled elastic roller according to claim 1, 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. 2. The method for producing a recycled elastic roller according to claim 1, wherein the σ / μ is 0.00 to 0.

20.

6. When 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), 2. The method for producing a recycled elastic roller according to claim 1, wherein the μd is 0.20 to 2.00 μm, and σd / μd is 0.00 to 0.

40.

7. 2. The method for producing a recycled elastic roller according to claim 1, wherein the conductive particles are carbon black. Law.

8. The method for producing 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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