Regenerated elastic roller manufacturing method

Abstract

Provided is a regenerated elastic roller manufacturing method including a contaminant removal step for removing contaminants adhered to an outer surface of an elastic roller having a support body having a conductive outer surface and an elastic layer on the outer surface of the support body, the method being characterized in that: the elastic layer has a matrix and a domain dispersed in the matrix; the matrix includes a first rubber; the domain includes a second rubber and an electronic conductive agent; the impedance of the elastic roller is 1.00×103 to 1.00×108 Ω; and the contaminant removal step includes a step for rubbing the outer surface of the elastic roller to which the contaminants are adhered.

Description

Manufacturing method for recycled elastic roller

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

[0002] Electrophotographic image forming apparatuses use electrophotographic rollers, such as charging rollers, transfer rollers, developing rollers, fixing rollers, and cleaning rollers. As images are produced, contaminants such as developer, external additives, and paper dust adhere to and gradually accumulate on the surfaces of these electrophotographic rollers. As a result, the performance of the electrophotographic rollers deteriorates, and they may be replaced as consumable parts. In recent years, in order to reduce environmental impact, there has been a growing need for the development of technologies for recovering used electrophotographic rollers and cleaning and recycling the roller surfaces using various cleaning means. One such recycling method involves using a rubbing member such as a brush or roller to remove contaminants through friction. Patent Document 1 discloses a method for manufacturing a recycled elastic roller for an office automation (OA) roller, a type of electrophotographic roller, which is contaminated by the adhesion of developer, paper dust, and the like, by striking the surface of the OA roller with the bristles of a rotating brush to remove the contaminants, and then vacuuming the removed contaminants to remove the contaminants from the OA roller surface.

[0003] Japanese Patent Application Laid-Open No. 2007-218983

[0004] However, in the recycling method disclosed in Patent Document 1, the frictional force generated during rubbing causes the movement of materials such as electronically conductive materials (e.g., conductive particles) contained on the surface of the OA roller. As a result, the electrical properties required for the OA roller, such as uniform charging and discharging, change, which can make it difficult to form high-quality images. Therefore, the present inventors have recognized that, in the case of an electrophotographic roller having an elastic layer containing an electronically conductive material, it is necessary to develop a method that can efficiently remove contaminants adhered to the outer surface of the elastic roller using a rubbing member while simultaneously suppressing changes in the electrical properties of the elastic roller due to rubbing.

[0005] The object of the present disclosure is to provide a method for manufacturing a recycled elastic roller that uses a rubbing member to remove contaminants, and that suppresses changes in the electrical properties of the elastic roller surface due to frictional forces, thereby contributing to good image formation.

[0006] According to one aspect of the present disclosure, there is provided a method for producing a recycled elastic roller, the method comprising a contaminant removal step of removing contaminants adhered to the outer surface of an elastic roller having a support having a conductive outer surface and an elastic layer on the outer surface of the support, wherein the elastic layer has a matrix and domains dispersed in the matrix, the matrix containing a first rubber, and the domains containing a second rubber and an electronic conductive agent, and an electrode is provided on the outer surface of the elastic roller, and an impedance of 1.00×10 when an AC voltage of 1 V amplitude and 10 Hz frequency is applied between the outer surface of the support and the electrode in an environment of a temperature of 23° C. and a relative humidity of 50% is ３ ~1.00 x 10 ８ Ω, and the contaminant removing step includes a step of rubbing the outer surface of the elastic roller to which the contaminants are adhered.

[0007] According to one aspect of the present disclosure, a method for manufacturing a recycled elastic roller that contributes to good image formation can be provided by removing contaminants from a used elastic roller while suppressing changes in electrical properties due to the recycling process.

[0008] Figures 1A and 1B are schematic diagrams of an elastic roller. Figures 2A and 2B are examples of cross-sectional views perpendicular to the longitudinal direction of the elastic layer of an elastic roller. Figure 3 is a three-dimensional diagram of a sample cut out from the elastic layer. Figures 4A and 4B are explanatory diagrams of a contamination removal device. Figure 5 is a cross-sectional view of a process cartridge. Figure 6 is a cross-sectional view of an electrophotographic image forming apparatus. Figure 7 is a schematic diagram of a state in which measurement electrodes are formed on an elastic roller. Figure 8 is a schematic diagram of an impedance measurement system. Figure 9 is a schematic diagram of an electrical resistance measurement device for a conductive member.

[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] After extensive investigation, the present inventors have found that in a method for manufacturing a recycled elastic roller, which includes a contaminant removal step for removing contaminants adhering to the outer surface of an elastic roller having a support with a conductive outer surface and an elastic layer on the outer surface of the support, satisfying the following requirements can achieve both uniform removal of contaminants and suppression of changes in the distance between the electronic conductive agents, thereby suppressing roughness (microscopic density unevenness) caused by uneven discharge due to changes in the electrical properties of the elastic roller surface.

[0011] <Requirements> The elastic layer has a matrix and domains dispersed in the matrix, the matrix contains a first rubber, and the domains contain a second rubber and an electronic conductive agent, and an electrode is provided on the outer surface of the elastic roller. When an AC voltage with an amplitude of 1 V and a frequency of 10 Hz is applied between the outer surface of the support and the electrode in an environment of a temperature of 23°C and a relative humidity of 50%, the impedance is 1.00 x 10 ３ ~1.00 x 10 ８ It is Ω.

[0012] This requirement is explained in detail below. This requirement relates to the morphology and electrical properties of the rubber constituting the elastic layer. Elastic rollers used in electrophotographic devices typically require the rubber to contain an electronic conductive agent in order to achieve uniform discharge with respect to contacting objects such as a photosensitive drum, intermediate transfer body, or print medium. For example, if conductive particles are used as the electronic conductive agent and are contained in the rubber, the rubber elasticity decreases, resulting in poor recovery from deformation. As a result, the frictional force from the rubbing member changes the distance between the conductive materials, which can lead to uneven discharge and result in image defects such as roughness.

[0013] On the other hand, particularly with increasing printing speeds, a large amount of charge transfer per unit time is required, so a relatively large amount of electronic conductive agent may be contained in the rubber. In this case, rubber elasticity is likely to decrease, and it may be difficult to achieve deformation recovery. As a result, the distance between the electronic conductive agents is likely to change due to frictional forces from rubbing members such as photoconductors, development blades, and toner supply rollers, especially during long-term use, making it difficult to ensure a sufficient discharge amount. In other words, there is a trade-off between suppressing changes in electrical properties and ensuring a discharge amount, and it may be difficult to achieve both.

[0014] In view of the above-mentioned problems, the inventors have conducted studies and found that the above-mentioned trade-off relationship can be resolved by forming an island-in-a-sea type phase-separated structure (matrix domain structure) in the elastic layer, which is composed of a domain and a matrix, and by incorporating an electronic conductive agent into the domain.

[0015] In the elastic roller configuration of the present disclosure, multiple domains containing an electronic conductive agent are primarily responsible for electrical conductivity, and charge is transferred via tunneling current at the interface between the matrix and the domains. In this case, it is preferable that the domains contain a large amount of electronic conductive agent, while the matrix contains a small amount of electronic conductive agent. In this configuration, the matrix surrounds the conductive domains, making it difficult for the frictional force of rubbing to directly affect the electronic conductive agent. In this matrix-domain structure, the inter-domain distance is hardly changed by the frictional force during rubbing, and therefore electrical properties are unlikely to change.

[0016] Furthermore, in a sea-island structure, it is believed that the matrix connecting the rubber particles together primarily relieves mechanical strain in response to frictional forces generated between the contacting members. Furthermore, since the domains contain an electronic conductive agent, the domains are relatively hard compared to the matrix and are less likely to deform. Therefore, the above structure exhibits excellent rubber elasticity and deformation recovery in the matrix, while at the same time making the domains, which are the origins of discharge, less likely to deform under external forces. As a result, the distance between the electronic conductive agents is less likely to change, effectively suppressing uneven discharge.

[0017] Furthermore, with the above-mentioned configuration, the content of the electronic conductive agent in the entire conductive member required for uniform discharge can be significantly reduced compared to conventional conductive members made of a single rubber. As a result, the elastic roller easily exhibits rubber elasticity and exhibits excellent deformation recovery, thereby suppressing changes in the distance between the electronic conductive agents. As a result, even after recycling, roughness due to uneven discharge can be suppressed.

[0018] Next, an electrode was provided on the outer surface of the elastic roller, and an AC voltage of 1 V amplitude and 10 Hz frequency was applied between the outer surface of the support and the electrode in an environment of a temperature of 23° C. and a relative humidity of 50%. When this voltage was applied, the impedance was 1.00×10 ３ ~1.00 x 10 ８ The effect when the impedance is 1.00×10 Ω will be described. The impedance indicates the degree of conductivity of the elastic layer. ３ By setting the impedance to 1.00×10 Ω or more, an excessive increase in the discharge current amount can be suppressed, and as a result, it is possible to prevent the occurrence of uneven discharge due to over-discharge. ８ By keeping the impedance within the above range, uneven discharge due to insufficient charging can be suppressed. Therefore, by keeping the impedance within the above range, roughness due to uneven discharge caused by insufficient charging and over-discharge can be suppressed even after regeneration processing. Hereinafter, embodiments for carrying out the present disclosure will be described in detail with reference to the drawings, but the present disclosure is not limited thereto.

[0019] <Recycled Elastic Roller> The recycled elastic roller can be used as an elastic roller for an electrophotographic device used in an electrophotographic image forming apparatus. Specifically, the recycled elastic roller can be used as a developing roller, charging roller, transfer roller, fixing roller, cleaning roller, etc. An example of a recycled elastic roller is shown in FIG. 1. Note that the recycled elastic roller is an elastic roller from which contaminants, such as those from developers and external additives, have adhered to its surface during image formation or the like have been removed. Therefore, the elastic roller itself, i.e., an elastic roller without contaminants adhered to its surface, has the same configuration as a recycled elastic roller. Below, the configuration of the elastic roller itself will be described using the recycled elastic roller as an example.

[0020] 1A is a bird's-eye view of a recycled elastic roller, and FIG. 1B is a view of the recycled elastic roller viewed from the longitudinal direction. In this disclosure, unless otherwise specified, the "longitudinal direction" refers to the direction of the rotation axis of the elastic roller. In FIGS. 1A and 1B, a recycled elastic roller 11 has an elastic layer 13 formed around a cylindrical conductive mandrel 12 serving as a support. However, the shape of the support is not particularly limited.

[0021] 2A and 2B show examples of cross sections perpendicular to the longitudinal direction of the elastic layer of the recycled elastic roller. In FIG. 2A, the elastic layer 13 has a sea-island phase-separated structure consisting of a matrix 3a that forms a sea region and domains 3b that form island regions. Furthermore, in the domains 3b, electronic conductive agent 3c is unevenly distributed in the domains 3b. Furthermore, FIG. 2B shows a cross section when two types of domains exist. The elastic layer has a sea-island phase-separated structure consisting of a matrix 3a that forms a sea region and first and second domains 3b and 3d that form island regions.

[0022] <Method for Confirming Matrix Domain Structure> The matrix domain structure is confirmed as follows. Specifically, a thin section is prepared from a cross section in the thickness direction of the elastic layer, including the surface of the elastic roller 11, and detailed observation is performed. Examples of means for thinning include a sharp razor, a microtome, and a focused ion beam (FIB). Furthermore, to facilitate observation of the matrix domain structure, pretreatment such as a staining treatment or a vapor deposition treatment may be performed to favorably obtain contrast between the conductive phase and the insulating phase. The thin section after forming the fracture surface and pretreatment can be observed using a laser microscope, a scanning electron microscope (SEM), or a transmission electron microscope (TEM). In the matrix domain structure according to the present disclosure, the matrix is ​​defined as a connected region in the image, such as 3a in FIGS. 2A and 2B , and the domain is defined as multiple regions surrounded by the matrix, such as 3b.

[0023] <Support> The support has a conductive outer surface. A support having a conductive outer surface is also called a "conductive support." Materials constituting the conductive support can be appropriately selected from those known in the field of conductive members for electrophotography and materials usable as conductive members. Examples include metals or alloys such as aluminum, stainless steel, conductive synthetic resins, iron, steel, and copper alloys.

[0024] Furthermore, these may be subjected to an oxidation treatment or a plating treatment with chromium, nickel, or the like. As the type of plating, either electroplating or electroless plating can be used. Electroless plating is preferred from the viewpoint of dimensional stability. Examples of the electroless plating used here include nickel plating, copper plating, gold plating, and various other alloy platings. Of these, electroless nickel plating is preferred.

[0025] 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 0.1 to 30 μm. The conductive support 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 for installation in an electrophotographic apparatus.

[0026] <Elastic Layer> The elastic layer 13 is provided on the outer surface of the support in order to impart the desired elasticity to the recycled elastic roller 11 in a device using the recycled elastic roller. Specifically, the elastic layer 13 may be either a solid body or a foam body. The elastic layer 13 may also be a single layer or multiple layers. For example, in a developing roller or a charging roller, which is constantly in pressure contact with the photosensitive drum and the toner, an elastic layer having low hardness and low compressive strain is provided to reduce mutual damage between these components.

[0027] From the viewpoint of supplying electric charges, it is preferable that the elastic layer is provided directly on the support in a manner that the elastic layer is in contact with the support. Another preferable embodiment is that the elastic layer is provided on the outer surface of the support via an intermediate layer made of a conductive resin layer such as a primer layer. It is more preferable that the primer layer is a thin film.

[0028] As the primer, a known material can be selected and used depending on the rubber material for forming the elastic layer and the material of the support. Examples of the primer material include thermosetting resins and thermoplastic resins, and specific examples of known materials that can be used include phenolic resins, urethane resins, acrylic resins, polyester resins, polyether resins, and epoxy resins. Among these, phenolic resins are preferred, and for example, Metalock U-20 (manufactured by Toyo Kagaku Kenkyusho Co., Ltd.) can be used.

[0029] The elastic layer has a matrix containing a first rubber and domains dispersed in the matrix, the matrix containing the first rubber, and the domains containing a second rubber and an electronic conductive agent. The matrix containing the first rubber is not particularly limited as long as it can form a phase-separated structure with the second rubber, but it is more preferable that the matrix exhibits non-conductivity. Here, non-conductivity means that the volume resistivity is 1.0 × 10 ８ The volume resistivity of the matrix is ​​1.0 × 10 ８ A resistivity of Ω cm or more means that the matrix contains almost no electronic conductive agent, and this effectively suppresses changes in the distance between the matrix and the electronic conductive agent between the domains due to friction during the regeneration process.

[0030] The volume resistivity of the matrix is ​​1.0 × 10 ８ To achieve a resistivity of Ω cm or more, for example, the affinity between the rubber used in the elastic layer and the electronic conductive agent may be adjusted. Specifically, a suitable combination of the first rubber, the second rubber, and the electronic conductive agent, which will be described later, may be selected. The volume resistivity of the matrix is ​​1.0×10 ９ ~1.0 x 10 １６ Ω cm is more preferable, and 1.0×10 １０ ~1.0 x 10 １５ The volume resistivity of the matrix can be adjusted by the composition of the first rubber used as the matrix and the amount of the electronic conductive agent contained in the matrix.

[0031] <Volume Resistivity Measurement Method> The volume resistivity of the matrix or domain can be measured using a microprobe by cutting the elastic layer of the recycled elastic roller into a thin section. Examples of methods for cutting include a sharp razor, a microtome, and an FIB. When preparing the thin section, it is necessary to eliminate the influence of the domain (or matrix) and measure the volume resistivity of only the matrix (or domain) at the measurement point. Therefore, it is necessary to prepare a thin section with a thickness smaller than the interdomain distance (or domain size) previously measured using an SEM or TEM. Therefore, a method capable of preparing a very thin sample, such as a microtome, is preferred as a cutting method.

[0032] To measure the volume resistivity, first, one side of the flake is grounded, and then the locations of the matrix and domains in the flake are identified using a means capable of measuring the structure or hardness distribution of the matrix and domains, such as an SPM or AFM. Next, a probe is brought into contact with the matrix (or domain), and the ground current is measured when a DC voltage of 50 V is applied, and the electrical resistance is calculated. In this case, a means capable of measuring the shape of the flake, such as an SPM or AFM, is preferred because it can measure the film thickness of the flake and therefore the volume resistivity. To measure the volume resistivity, the elastic layer is divided into four regions circumferentially and five regions longitudinally, and one flake sample is cut out from each region. After obtaining each measurement value, the volume resistivity of a total of 20 samples is calculated as the arithmetic average.

[0033] <First Rubber> The matrix contains a first rubber. The first rubber is not particularly limited as long as it can form a phase-separated structure with the second rubber described below. 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).

[0034] Particularly preferred is at least one rubber selected from isoprene rubber (IR), acrylonitrile rubber (NBR), ethylene propylene rubber (EPDM) and styrene butadiene rubber (SBR).

[0035] It is also possible to compound reinforcing carbon black as a reinforcing agent into the matrix to the extent that it does not affect the deformation recovery of the first rubber. Examples of the reinforcing carbon black used here include FEF, GPF, SRF, and MT carbon, which have low conductivity and a small surface area. Furthermore, if necessary, fillers, processing aids, vulcanization accelerators, vulcanization retarders, antioxidants, softeners, dispersants, colorants, and the like, which are commonly used as rubber compounding agents, may be added to the first rubber forming the matrix to the extent that it does not impair the deformation recovery.

[0036] The glass transition temperature Tg1 of the first rubber is preferably lower than −15° C. This is because, when the glass transition temperature Tg1 is lower than −15° C., the roller hardness can be kept low and the hardness of the elastic roller changes little under usage environments such as high-temperature, high-humidity environments and low-temperature, low-humidity environments. This is because elastic rollers used in electrophotographic image forming apparatuses are usually used in contact with other members, and therefore it is necessary to maintain an appropriate nip width.

[0037] <Second Rubber> The domain contains a second rubber and an electronic conductive agent. The second rubber is a rubber different from the first rubber, and is not particularly limited as long as it can form a phase-separated structure with the first rubber. The rubbers listed as the first rubber can be suitably used. Particularly preferred are those containing at least one structure selected from IR, NBR, EPDM, and SBR.

[0038] The glass transition temperature Tg2 of the second rubber is preferably lower than −15° C. This is because, when the glass transition temperature Tg2 is lower than −15° C., the roller hardness can be kept low and the hardness of the elastic roller changes little under usage environments such as high-temperature, high-humidity environments and low-temperature, low-humidity environments. This is because elastic rollers used in electrophotographic image forming apparatuses are usually used in contact with other members, and therefore it is necessary to maintain an appropriate nip width.

[0039] The first rubber and the second rubber are preferably, for example, the following combinations: The first rubber is styrene butadiene rubber (SBR) and the second rubber is acrylonitrile butadiene rubber (NBR). 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 acrylonitrile butadiene rubber (NBR) and the second rubber is butadiene rubber (BR).

[0040] The mass ratio of the second rubber to the first rubber in the elastic layer (second rubber:first rubber) is preferably 5:90 to 40:60, and more preferably 15:75 to 30:70.

[0041] When a third rubber is used, preferred examples of the third rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), ethylene-propylene rubber (EPM), ethylene propylene diene rubber (EPDM), and silicone rubber. The third rubber preferably contains SBR. 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.

[0042] <Electronic Conductive Agent> Examples of the electronic conductive agent to be incorporated into the domains include oxides such as carbon black, graphite, titanium oxide, and tin oxide; metals such as Cu and Ag; and particles coated with an oxide or metal to make them conductive. If necessary, two or more of these electronic conductive agents may be appropriately combined and used. The electronic conductive agent is preferably a conductive particle. Among the above-mentioned electronic conductive agents, an electronic conductive agent containing conductive carbon black is preferred for reasons such as preventing a significant decrease in rubber elasticity, high conductivity, high affinity with rubber, and easy control of the distance between the electronic conductive agents. The type of carbon black to be incorporated into the domains is not particularly limited. Specific examples include gas furnace black, oil furnace black, thermal black, lamp black, acetylene black, black furnace black, and ketjen black. Examples of furnace black include SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, I-ISAF-HS, HAF-HS, HAF, HAF-LS, T-HS, T-NS, MAF, FEF, GPF, SRF-HS-HM, SRF-LM, ECF, and FEF-HS. Examples of thermal black include FT and MT. Examples of carbon-based fine particles include PAN (polyacrylonitrile)-based carbon particles and pitch-based carbon particles.

[0043] Furthermore, when observing a cross section of the elastic layer in the thickness direction, the ratio of the total cross-sectional area of ​​the electronic conductive agent contained in the domains to the total cross-sectional area of ​​the domains is defined as μ, and this μ is preferably 15.0 area% or more and 50.0 area% or less, and particularly preferably 20.0 area% or more and 40.0 area% or less. μ can be adjusted by the amount of electronic conductive agent blended in the domains.

[0044] A μ value within the above range means that a larger amount of electronic conductive agent is blended compared to typical electrophotographic conductive materials. The conductivity of the electronic conductive agent is formed by tunneling currents flowing between conductive materials. The variation in the amount of this tunneling current correlates with the distribution of the distance between the electronic conductive agents. Therefore, the higher the amount of electronic conductive agent added and the area occupancy rate in the domain, the more uniform the distribution of the distance between the electronic conductive agents becomes, and the more the variation can be suppressed. Therefore, by having the μ value within the above range, uniform discharge can be facilitated.

[0045] When μ is 15.0 area % or more, the amount of the electronic conductive agent is large, and the electrical connection of the electronic conductive agent within the domain is stabilized by percolation. As a result, even if differences in the movement of the electronic conductive agent occur due to the friction of the regeneration treatment, they are not likely to be significantly manifested as differences in the discharge amount, and roughness due to uneven discharge is not likely to become apparent. On the other hand, when μ is 50.0 area % or less, the electronic conductive agent is likely to exist in a stable state within the domain, and the electronic conductive agent is unlikely to migrate to the matrix, so the effects of the present disclosure are likely to be fully realized.

[0046] Furthermore, the content of the electronic conductive agent in the domains is preferably 20 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the second rubber. It is particularly preferably 50 parts by mass or more and 150 parts by mass or less. By including 20 parts by mass or more, a sufficient amount of electronic conductive agent is contained in the domains, making them less susceptible to deformation due to external forces and suppressing changes in the distance between the electronic conductive agents. Furthermore, by including 200 parts by mass or less, excessive reduction in rubber elasticity of the domains is suppressed, and sufficient follow-up ability to deformation of the domains and matrix is ​​achieved. Therefore, even if a strong external force is applied during the recycling process, aggregation of the domains can be suppressed. Furthermore, since the electronic conductive agent can be present in a stable state within the domains, migration of the electronic conductive agent to the matrix is ​​suppressed, making it easier to achieve the effects of the present disclosure.

[0047] In order to suppress changes in electrical properties due to friction, it is preferable that the amount of the electronic conductive agent contained in the matrix is ​​small. The content of the electronic conductive agent in the matrix is ​​preferably 5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the first rubber.

[0048] When the electronic conductive agent contains conductive carbon black, the conductive carbon black to be blended into the domain is particularly preferably one having a neutral surface with a pH of 6.0 or more at 20° C. The DBP oil absorption of the conductive carbon black to be blended into the domain is preferably 85 cm ３ / 100g or more, 160cm ３ It is particularly preferable that the DBP absorption of carbon black is a value measured in accordance with JIS K 6217. The pH is 6.0 or more and the DBP oil absorption is 85 cm or less. ３ / 100g or more, 160cm ３ By using conductive carbon black with a r / 100g or less, it is possible to maintain the resistance value within an appropriate range even if the conductive carbon black has a domain structure. Furthermore, since it can exhibit excellent affinity with diene polymers such as IR, SBR, and NBR, the interaction between the polymer and the conductive carbon black can suppress the aggregation of domains when subjected to friction during the recycling process. As a result, by suppressing changes in the distance between the carbon blacks, i.e., uneven discharge, it is possible to easily suppress roughness.

[0049] <Impedance> The recycled elastic roller has an electrode on the roller surface, and when an AC voltage of 1 V amplitude and 10 Hz frequency is applied between the outer surface of the support and the electrode in an environment of a temperature of 23° C. and a relative humidity of 50%, the impedance is 1.00×10 ３ ~1.00 x 10 ８ The impedance of the regenerated elastic roller is a value specified at a frequency of 10 Hz. When the regenerated elastic roller is mounted as a charging roller for electrophotography and combined with a photosensitive drum, the discharge frequency is generally several Hz to 1.0 × 10 ６Hz range. Within this range, the low-frequency region is the region that correlates with discharge unevenness. The amount of charge transfer at low frequencies is an index of the ease of charge transfer between the charging member and the measurement electrode, and can also be used as an index of the amount of charge that can be transferred by discharge from the surface of the charging member to the photosensitive drum.

[0050] Therefore, it can be assumed that measurements made while applying a low-frequency voltage simulate the amount of charge movement in a state where the charge movement can follow the voltage oscillation. ３ ~1.00 x 10 ８ The impedance of Ω indicates the characteristic that charge stagnation is unlikely to occur. Charge stagnation directly affects the amount of discharge to the photosensitive drum, so when charge stagnation occurs, discharge unevenness is likely to occur. In particular, by performing a regeneration process, resistance unevenness caused by remaining contaminants and discharge unevenness due to changes between electronic conductive agents caused by friction are likely to occur, but by having the impedance in the above range, discharge unevenness can be suppressed. Specifically, when the impedance at the above frequency of 10 Hz is 1.00×10 ３ Ω or more, the discharge current amount becomes excessive, and as a result, it is possible to prevent the occurrence of potential unevenness due to abnormal discharge. ８ By keeping the resistance Ω or less, it is possible to suppress insufficient charging due to insufficient total amount of discharged charge.

[0051] The impedance is preferably 1.00 x 10 ４ ~1.00 x 10 ７ Ω, more preferably 1.00×10 ５ ~5.00 x 10 ６ The impedance can be controlled by selecting the rubber that forms the elastic layer, the compounding ratio, and the amount of electronic conductive agent contained.

[0052] <Method for Measuring Impedance> Impedance can be measured by the following method. When measuring impedance, in order to eliminate the influence of contact resistance between the conductive member and the measurement electrode, a low-resistance thin film is deposited on the surface of the conductive member, and the thin film is used as an electrode, while the conductive support is used as a ground electrode to measure the impedance at two terminals. Examples of methods for forming the thin film include metal deposition, sputtering, application of a metal paste, and application of a metal tape.

[0053] Among these, a method of forming a metal thin film such as platinum or palladium as an electrode by vapor deposition is preferred from the viewpoint of reducing contact resistance with the conductive member. When forming a metal thin film on the surface of a conductive member, considering the simplicity and uniformity of the thin film, it is preferable to use a vacuum deposition apparatus equipped with a mechanism for gripping a charging member, and for conductive members with a cylindrical cross section, it is preferable to use a vacuum deposition apparatus equipped with an additional rotation mechanism. For conductive members with a curved cross section such as a circular cross section, it is difficult to connect the above-mentioned metal thin film as a measurement electrode to an impedance measurement device, so it is preferable to use the following method.

[0054] Specifically, a thin metal film electrode with a width of approximately 10 mm to 20 mm is formed in the longitudinal direction of the conductive member, and then a metal sheet is tightly wrapped around the conductive member, and the metal sheet is 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 conductive member, enabling impedance measurement. The metal sheet may be any metal sheet that has an electrical resistance value equivalent to that of the metal part of the connection cable of the measurement device when measuring impedance, and examples of such metal sheets include aluminum foil and metal tape. The impedance measurement device can be an impedance analyzer, network analyzer, spectrum analyzer, or the like, and can measure impedance up to 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 impedance using an impedance analyzer, since it is in the range of electrical resistance of the conductive member.

[0055] The conditions for measuring impedance are as follows. An impedance measuring device is used to measure impedance at a frequency of 10 Hz. Measurements are performed in an environment of 23°C temperature and 50% RH. The amplitude of the AC voltage is 1 V. Regarding the measurement voltage, measurements may be performed while applying a DC voltage, taking into account the shared voltage applied to the elastic roller in the electrophotographic device. Specifically, measurements are performed while applying a DC voltage of 10 V or less superimposed on an oscillating voltage, which is suitable for quantifying the characteristics of charge transport and accumulation.

[0056] <Domain Volume Fraction> The domain volume fraction in the elastic layer is preferably 15.0% or more and 40.0% or less. By setting the domain volume fraction to 15.0% or more and 40.0% or less, the above-mentioned impedance range can be easily achieved. Furthermore, by setting the domain volume fraction to 15.0% or more, the distribution of interdomain distances becomes uniform, which can suppress variation and facilitate uniform discharge. Furthermore, the domains have excellent mechanical properties, which can sufficiently suppress damage during the recycling process. Furthermore, excessive addition of electronic conductive agent to the domains can be suppressed. As a result, excessive reduction in the rubber elasticity of the domains is suppressed, and sufficient compliance with deformation of the domains and matrix can be achieved, so that aggregation between domains can be suppressed even when friction is applied during the recycling process.

[0057] On the other hand, by setting the domain volume fraction to 40.0% or less, it is possible to suppress the aggregation of domains when subjected to friction during the recycling process, while at the same time achieving a structure in which the matrix is ​​relatively more abundant than the domain. As a result, the matrix has excellent rubber elasticity and can exhibit deformation recovery, making it easier to suppress changes in discharge characteristics. The domain volume fraction can be controlled by selecting the first rubber and the second rubber and their compounding ratios.

[0058] <Method for Measuring Domain Volume Fraction> The domain volume can be determined by measuring the elastic layer in three dimensions using an FIB-SEM. FIB-SEM is a technique in which a sample is processed using a focused ion beam (FIB) device and the exposed cross section is observed using a scanning electron microscope (SEM). To investigate the three-dimensional structure, a large number of photographs are obtained by repeating successive processing and observation, and then the SEM images are subjected to 3D reconstruction processing using computer software to construct a three-dimensional image of the sample structure.

[0059] A specific method for measuring the domain volume involves using an FIB-SEM (manufactured by FEI Corporation) to obtain a three-dimensional image of the unit cube 31 shown in Figure 3, and then confirming the above-mentioned configuration from that image. Specifically, the procedure is as follows: When the longitudinal length of the elastic layer is L, one sample is taken from each of three locations located at distances of (1 / 4)L, (2 / 4)L, and (3 / 4)L from one end of the longitudinal direction. Furthermore, one sample is similarly taken from each location at a distance of 120° and 240° from each location in the circumferential direction of the roller, cutting out a total of nine samples.

[0060] Thereafter, three-dimensional measurement is performed by cutting out the sample at 60 nm intervals and acquiring images using an FIB-SEM, and images of cube shapes with sides of 9 μm at 60 nm intervals are measured.

[0061] In order to properly observe the domain structure, it is also preferable to perform pretreatment that provides a good contrast between the domain and the matrix. Staining treatment is preferably used here. The resulting image is then used with 3D visualization and analysis software Avizo (manufactured by F.E.I.) to calculate the domain volumes of 27 unit cubes with sides of 3 μm contained in one 9 μm cubic sample. Because 9 μm cubic samples are collected from nine locations, the domain volume fraction is calculated from the arithmetic average of a total of 243 measurements.

[0062] The distance between adjacent wall surfaces of the domains can also be measured in the same manner using the 3D visualization and analysis software Avizo. After obtaining the above measured values, the distance is calculated by taking the arithmetic mean of the measured values.

[0063] <Domain Size> The average domain size is preferably in the range of 0.1 μm to 4.0 μm. More preferably, it is in the range of 0.2 μm to 2.0 μm. When the domain size is 0.1 μm or more, migration of the electronic conductive agent from the domain to the matrix can be suppressed, and a decrease in the rubber elasticity of the matrix can be suppressed. Furthermore, a change in conductivity due to aggregation of domains can be suppressed.

[0064] As a result, even when subjected to friction during the regeneration process, the distance between the electronic conductive agents is less likely to increase, making it easier to achieve the effects of the present disclosure. On the other hand, by keeping the thickness at 4.0 μm or less, the charge transport effect due to tunneling current is achieved, particularly in high-speed processes, and charging defects can be suppressed. Furthermore, changes in the discharge amount due to aggregation between domains can be suppressed.

[0065] <Method for Measuring Domain Size> The average domain size may be measured as follows. First, a thin section is prepared using the same method as in the above-mentioned method for measuring volume resistivity. Next, a fracture surface is formed by means of a freeze fracture method, a cross polisher method, a focused ion beam method (FIB), or the like. Considering the smoothness of the fracture surface and pretreatment for observation, the FIB method is preferred. Furthermore, in order to favorably observe the matrix domain structure, pretreatment such as a staining treatment or a vapor deposition treatment may be performed to favorably obtain contrast between the conductive phase and the insulating phase.

[0066] The formed and pretreated thin section of the fracture surface can be observed using a laser microscope, a scanning electron microscope (SEM), or a transmission electron microscope (TEM). Among these, observation with an SEM at 1000x to 100000x magnification is preferred from the viewpoint of accurate quantification of the area of ​​the conductive phase.

[0067] The domain size can be obtained by quantifying the image captured above. The fracture surface image obtained by SEM observation is converted to an 8-bit grayscale image using image processing software such as ImageProPlus to obtain a monochrome image with 256 gradations. The image is then inverted to black and white, and binarized, so that the domains in the fracture surface appear white. The diameter of the equivalent circle is then calculated from the area value of each domain group in the image, and the arithmetic average value is calculated.

[0068] The domain size can be measured by dividing the conductive member into four regions in the circumferential direction and five regions in the longitudinal direction, cutting out one thin sample from each center of each region, and performing the above measurement on the sample, and then calculating the domain size from the arithmetic average of the measurement values ​​at a total of 20 points.

[0069] <Interdomain distance> The average distance between domains in the elastic layer is preferably 0.2 μm or more and 4.0 μm or less. By making the interdomain distance 0.2 μm or more, it is possible to easily suppress the aggregation of domains. On the other hand, by making it 4.0 μm or less, an excellent effect of suppressing mechanical distortion due to frictional force is exhibited, and it is easy to suppress changes in the interdomain distance. Note that when two or more types of domains are present, the interdomain distance is defined as the distance between the domains with the highest volume fraction. The interdomain distance is preferably 0.5 to 2.0 μm, more preferably 1.0 to 1.5 μm.

[0070] <Method for Measuring Interdomain Distance> The interdomain distance can be measured by quantifying an image obtained by direct observation of the fracture surface, similar to the method for measuring domain size. After binarizing the fracture surface in the same manner as the method for measuring domain size, the distance between the wall surfaces of the domain group in the image is calculated using image processing software. The wall surface distance in this case is the shortest distance between the two closest domains among the domain group in the image. The domain size is measured by dividing the elastic roller into four regions in the circumferential direction and five regions in the longitudinal direction, cutting out one thin sample from each center of each region, and performing the above measurement. The domain size is calculated from the arithmetic average of the measured values ​​at a total of 20 points.

[0071] <Method for controlling domain size and interdomain distance> In the matrix domain structure of the elastic layer, it is preferable that the domains are formed uniformly. Here, "uniform" is defined as (1) the size of each domain is approximately equal, and (2) there is no bias in the arrangement of the domains in the matrix. Formation of uniform domains can suppress aggregation of domains when subjected to friction during the regeneration process.

[0072] The following Taylor's formula, Wu's empirical formula, and Tokita's formula have been proposed to calculate the dispersed particle diameter (domain size) D when two immiscible polymers are melt-kneaded: Taylor's formula D = [C σ / ηm γ] f(ηm / ηd)

[0073] ・Wu's empirical formula γ・D・ηm / σ=4(ηd / ηm)0.84・ηd / ηm>1 γ・D・ηm / σ=4(ηd / ηm)−0.84・ηd / ηm<1

[0074] ・Tokita's formula D=f((1 / η)×(1 / γ)×(ηd / ηm)×P×φ×σ×(1 / EDK)×(1 / τ)×χ12)

[0075] D: domain size, C: constant, σ: interfacial tension, ηm: viscosity of matrix, ηd: viscosity of domain, γ: shear rate, η: viscosity of mixed system, P: probability of collision and coalescence, φ: domain phase volume, EDK: domain phase cleavage energy, χ12: interaction parameter between two polymers

[0076] As shown in the above formula, the domain size and interdomain distance required for the formation of uniform domains can be controlled mainly by the following four points: (1) Interfacial tension difference between the domain and the matrix (2) Viscosity ratio between the domain and the matrix (3) Shear rate during mixing / amount of energy during shear (4) Volume fraction of the domain in the elastic layer

[0077] (1) The interfacial tension correlates with the difference in SP value between the domain and the matrix, and can be controlled by selecting the materials for rubbers A and B. Specifically, the interfacial tension can be reduced by reducing the difference in SP value.

[0078] (2) The viscosity ratio of the domain raw rubber to the matrix raw rubber can be adjusted by selecting the Mooney viscosity of the rubber raw material and by blending the type and amount of filler. It can also be adjusted by adding a plasticizer such as paraffin oil to an extent that does not interfere with the formation of a phase-separated structure. Furthermore, 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 of the raw rubber may be used instead.

[0079] (3) The shear rate during mixing / the amount of energy during shearing 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 shearing can be increased by increasing the rotation speed and kneading time during rubber kneading and the feed rate during extrusion molding.

[0080] (4) The volume fraction of domains in the elastic layer correlates with the probability of collision and coalescence between the domains and the matrix. Specifically, increasing the volume fraction of domains in the elastic layer can increase the probability of collision and coalescence between the domains and the matrix.

[0081] Specifically, the domain size can be reduced by the following methods: - Reducing the interfacial tension between the domain polymer and the matrix polymer - Reducing the difference in viscosity between the domain polymer and the matrix polymer - Increasing the shear rate during kneading

[0082] In addition to the method for reducing the domain size, the distance between domains can be reduced by the following methods: Increasing the energy during shearing Increasing the volume ratio of the domain phase Decreasing the probability of collision and coalescence

[0083] <Volume Resistivity of Domain> The domain transports charges by utilizing tunnel currents formed between domains. Therefore, it is preferable that the volume resistivity of the domain is low. Specifically, it is preferable that the volume resistivity of the domain is 1.0×10 １ ~1.0 x 10 ４It is preferable that the resistivity of the domain is 1.0×10 Ω·cm. Furthermore, from the viewpoint of exhibiting charge mobility that can be used in high-speed processes and reducing the volume resistivity, electronic conductivity is more preferable than ionic conductivity. １ By making the resistivity of the domain Ωcm or more, the content of the electronic conductive agent in the domain can be suppressed. As a result, excessive reduction in rubber elasticity of the domain can be suppressed, and sufficient followability to deformation of the domain and matrix can be exhibited, so that even if friction is applied during the recycling process, aggregation of the domains can be suppressed. Furthermore, since the electronic conductive agent can be present in a stable state within the domain, migration of the electronic conductive agent to the matrix can be suppressed, making it easier to exhibit the effects of the present disclosure. Furthermore, when the volume resistivity of the domain is 1.0 × 10 ４ By setting the electrical resistance to Ω cm or less, a sufficient amount of discharge charge can be ensured, especially in high-speed processes, making it easier to control the suppression of minute density unevenness. Furthermore, by setting the electrical resistance within the above range, even when an electronic conductive agent is used, ohmic behavior is achieved, reducing voltage dependency and making it easier to achieve uniform discharge. As a result, the effects of the present disclosure are easily realized.

[0084] The volume resistivity of the domain is 1.0×10 ２ ~5.0 x 10 ３ Ω cm is more preferable, and 3.0×10 ２ ~4.0 x 10 ３ Ω cm is more preferable. The volume resistivity of the domain can be adjusted by the composition of the second rubber used as the domain and the amount of the electronic conductive agent contained in the domain. When two or more types of domains are present, it is sufficient that the volume resistivity of the domain with the highest volume fraction is within the above range.

[0085] <Method for manufacturing elastic roller> An example of a method for manufacturing an elastic roller according to one aspect of the present disclosure is shown below. In this example, the manufacturing method includes the following steps (A) to (C), but is not particularly limited as long as the configuration of the present disclosure can be achieved.

[0086] (A) a step of preparing a carbon masterbatch (CMB) for domain formation, which contains carbon black and rubber; (B) a step of preparing a rubber composition that will serve as a matrix; and (C) a step of kneading the carbon masterbatch and the rubber composition to prepare a rubber composition having a matrix domain structure.

[0087] It is preferable to unevenly distribute an electronic conductive agent such as conductive carbon black in the domains of the elastic layer. To achieve this, it is effective to prepare a master batch in which the electronic conductive agent is added only to the domains in advance, as in step (A), and then blend the obtained master batch with a rubber composition that will become the matrix to prepare a semiconductive rubber composition. That is, a rubber composition in which the electronic conductive agent is unevenly distributed in the domains can be produced by compounding the electronic conductive agent with the second rubber that is the raw material for the domains to prepare a CMB, and then blending the obtained CMB with a rubber composition that will become the matrix.

[0088] Examples of the method for kneading the CMB that will form the domains and the unvulcanized rubber composition that will form the matrix in step (C) to form an unvulcanized rubber composition having a matrix domain structure include the following methods: - The CMB that will form the domains and the unvulcanized rubber composition that will form the matrix are mixed using an internal mixer such as a Banbury mixer or a pressure kneader. Then, an open mixer such as an open roll mill is used to knead and integrate the CMB that will form the domains, the unvulcanized rubber composition that will form the matrix, and raw materials such as a vulcanizing agent and a vulcanization accelerator. - A method in which the CMB that will form the domains is mixed using an internal mixer such as a Banbury mixer or a pressure kneader, and then the CMB that will form the domains and the raw materials for the unvulcanized rubber composition that will form the matrix are mixed in an internal mixer. Then, an open mixer such as an open roll mill is used to knead and integrate raw materials such as a vulcanizing agent and a vulcanization accelerator.

[0089] The elastic layer is formed on the mandrel by a known method such as extrusion molding, injection molding, or compression molding of a rubber composition having a matrix domain structure. The elastic layer is adhered to the mandrel via an adhesive, if necessary, and then the elastic layer formed on the mandrel is vulcanized. The sea-island structure of the elastic layer can also be controlled by the mixing time of the internal mixer and an open mixer such as an open roll mixer, the clearance between the rolls of the mixer, and the molding speed of extrusion molding, injection molding, compression molding, or the like.

[0090] <Elastic Roller Shape> In order to more uniformly distribute the width of the nip extending in the longitudinal direction relative to the photosensitive drum, the elastic roller preferably has a so-called crowned shape, in which the outer diameter is greatest at the longitudinal center and tapers toward both longitudinal ends. The crown amount is preferably such that the difference between the outer diameter at the longitudinal center and the average outer diameter at two points 90 mm away from the center is 30 μm or more and 160 μm or less. By setting the crown amount within this range, the contact state between the elastic roller and the photosensitive drum can be more stable. As a result, external force is more easily applied uniformly across the entire contact area between the elastic roller and the photosensitive drum, which facilitates suppression of roughness due to uneven discharge.

[0091] <Method for Regenerating Elastic Roller> A method for producing a recycled elastic roller according to one embodiment of the present disclosure includes a contaminant removal step for removing contaminants adhering to the outer surface of the elastic roller. An example of an apparatus for removing contaminants adhering to the outer surface of the elastic roller is described with reference to FIG. 4. FIG. 4 is a schematic diagram showing an example of the contaminant removal apparatus, showing the state in which the elastic roller is set. Examples of contaminants include adhering materials originating from the developer.

[0092] 4A, removal device 501 is composed of cleaning member 502 and dust collection means 503 for collecting dust. Dust collection means 503 is composed of vacuum chamber 504, vacuum pump 505, and pump drive motor 506. Furthermore, elastic roller 507 having contaminants adhering to its outer surface is disposed within removal device 501. Within removal device 501, cleaning member 502 is in contact with the surface of elastic roller 507 so as to be able to make contact and perform frictional movement. Cleaning member 502 is composed of a support portion and a cleaning portion 508.

[0093] The contact pressure of the cleaning member 502 on the surface of the elastic roller 507 can be appropriately selected depending on the surface material of the elastic roller 507, the material of the cleaning portion 508, and the material of the contaminants. It is preferable to select a contact pressure that breaks down the contaminants on the surface of the elastic roller 507 without scratching the surface of the elastic roller 507. The dust collecting means is also configured to collect and remove the contaminants on the surface of the elastic roller 507. Specifically, the pressure applied to the elastic roller 507 by pressing the cleaning member 502 is preferably a drawing pressure of 10 N / m or more and 500 N / m or less, and more preferably 50 N / m or more and 300 N / m or less. A drawing pressure of 10 N / m or more applied to the elastic roller 507 makes it easier to break down contaminants on the surface of the elastic roller 507, while a drawing pressure of 500 N / m or less can easily prevent damage to the elastic roller 507 during pressing.

[0094] The drawing pressure can be measured by the following method. 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 pressing member 23 and the elastic roller 1. Next, the SUS plate for drawing is pulled at a speed of 0.5 cm / sec, and the force is measured and converted into a linear pressure equivalent value per meter of SUS plate width. The force during drawing is measured using a digital force gauge (product name: DS2, manufactured by Imada Co., Ltd.). The elastic roller 507 has a mandrel (support) and one elastic layer on the mandrel, and the mandrel is connected to a rotating means (not shown) for rotation. If the removal device 501 processes multiple elastic rollers 507, a mechanism for easily attaching and detaching the elastic rollers 507 may be provided.

[0095] Next, the operation of the removal device will be described. First, within the removal device 501, an elastic roller 507 is installed in a predetermined position, and a cleaning member 502 is abutted against the surface of the elastic roller 507 with a predetermined pressure. Then, a cleaning portion 508 of the cleaning member 502 is brought into dry contact with the surface of the elastic roller 507, thereby causing frictional motion. During this frictional motion of the cleaning portion 508, the frictional force of the cleaning portion breaks down contaminants on the surface of the elastic roller, liberating them from the surface of the elastic roller. The liberated contaminants are removed by sucking them up with a vacuum pump 505 and collecting them in a vacuum chamber 504. The rotation speed of the elastic roller 507 is not particularly limited. If one rotation does not sufficiently remove the contaminants, multiple rotations are repeated, and the specified removal process is performed until the contaminants are completely removed. The rotation speed at which the elastic roller 507 is rotated can be determined taking into account the processing time and the efficiency of contaminant removal. Specifically, a rotation speed of 30 rpm or more and 500 rpm or less is preferred. After the above operations have been performed and a sufficient predetermined processing time has elapsed, the rotation of the elastic roller 507 is stopped, and the elastic roller 507 from which the contaminants have been removed is removed.

[0096] Furthermore, when the elastic roller 507 is brought into contact with and rubbed against the cleaning portion 508 of the cleaning member 502, it is preferable to do so in a dry state. Here, "dry state" refers to a state in which no liquid is present at the portion where the cleaning portion 508 comes into contact with the elastic roller. By performing the process in a dry state, swelling of the elastic roller 507 due to liquids such as solvents and cleaning fluids can be suppressed, and the surface shape can be easily maintained.

[0097] Although the regeneration method using a brush shape has been described as an example, the shape of the cleaning member 502 is not particularly limited as long as it is a rubbing member that can uniformly scrape off contaminants. For example, roller-shaped cleaning members using foam rollers, blade-shaped cleaning members, and sheet-shaped cleaning members can also be suitably used. Figure 4B shows a diagram of a removal device using a blade-shaped cleaning member 509 as the cleaning member. By removing contaminants adhered to the outer surface of the elastic roller using the method described above, a regenerated elastic roller according to one embodiment of the present disclosure can be manufactured.

[0098] <Cleaning Member> The cleaning member 502 has a fibrous cleaning portion 508 that contacts and rubs against the elastic roller, and a support portion that supports the cleaning portion. The shape of the cleaning member 502 is not particularly limited, but brush, roller, or sheet shapes are preferred, with brush or roller shapes being particularly preferred for uniformly scraping away contaminants. In other words, the contaminant removal step in the method for manufacturing a recycled elastic roller is preferably a step of rubbing the outer surface of the elastic roller with a brush or roller. The cleaning portion 508 breaks down contaminants adhering to the surface of the elastic roller 507 through shear force between the elastic roller and the cleaning member. To effectively exert this function, it is preferable that the material of at least the cleaning portion 508 of the cleaning member has a Mohs hardness higher than that of the contaminant.

[0099] Here, when the contaminants are derived from the developer, the Mohs hardness of the solidified material derived from the developer used in the electrophotographic process is generally 1.0 degrees or more and less than 2.0 degrees. Therefore, more specifically, the Mohs hardness of the cleaning portion 508 is preferably 2.0 degrees or more and 6.0 degrees or less. If the Mohs hardness of the cleaning portion 508 is 2.0 degrees or more, the solidified material derived from the developer on the surface of the elastic roller 507 can be sufficiently destroyed. On the other hand, if the Mohs hardness of the cleaning portion 508 is 6.0 degrees or less, damage to the surface of the elastic roller can be suppressed.

[0100] Preferred materials with a Mohs hardness of 2.0 to 6.0 degrees include nylon resin, polypropylene resin, polyester resin, urethane resin, polyamide resin, aramid resin, acrylic resin, and fluororesin. Conductive resins obtained by incorporating a conductive agent such as carbon black into the above resins are also suitable. Resin materials containing an abrasive of inorganic fine particles such as silica, alumina, or silicon oxide can also be used. Particularly preferred are conductive resins obtained by incorporating carbon black into acrylic resin, nylon resin, polypropylene resin, or polyester resin, and nylon resin containing alumina or silicon carbide as an abrasive. In particular, the brush or roller preferably contains at least one material selected from the group consisting of conductive fibers, abrasive-containing fibers, and urethane-containing resins or rubbers.

[0101] The use of a conductive resin has the effect of attenuating the charge of the scraped dirt, effectively suppressing electrostatic re-adhesion to a matrix with high volume resistivity. Furthermore, the use of a resin material containing inorganic fine particle abrasives can promote the destruction of developer-derived deposits. In particular, when a large amount of electronic conductive agent is present in the domains of the elastic layer, even if a resin containing inorganic fine particle abrasives is used, it is preferable because it can suppress changes in the inter-domain distance and the inter-electro-conductive agent distance due to friction due to its excellent mechanical properties.

[0102] When the cleaning portion 508 is brush-shaped, it is preferably made of a bundle of fibrous material, and the thickness and length of the fibers should be selected appropriately so that they can sufficiently rub against the elastic roller without damaging the surface of the elastic roller. The thickness of the fibers is preferably 0.1 mm or more and 1 mm or less. Furthermore, one method of contacting the cleaning member 502 with the elastic roller 507 is to fix the cleaning member 502 and contact the tip of the cleaning portion with the surface of the elastic roller 507. Alternatively, it is preferable to contact the cleaning member 502 with the tip of the cleaning portion 508 facing in the opposite direction to the rotational direction of the elastic roller 507, as this will tension the cleaning portion and increase the effect of destroying contaminants.

[0103] <Process Cartridge> Figure 5 is a schematic cross-sectional view of an example of an electrophotographic process cartridge equipped with an elastic roller as a charging roller. This process cartridge integrates a developing device and a charging device and is configured to be detachably attached to the main body of an electrophotographic device. The developing device integrates at least a developing roller 93 and a developer container 96, and may optionally include a developer supply roller 94, developer 99, a developing blade 98, and an agitating blade 910. The charging device integrates at least a photosensitive drum 91, a cleaning blade 95, and a charging roller 92, and may also include a waste developer container 97. Voltages are applied to the charging roller 92, developing roller 93, developer supply roller 94, and developing blade 98, respectively.

[0104] <Electrophotographic Device> FIG. 6 is a schematic diagram of an example of an electrophotographic device using an elastic roller as a charging roller. This electrophotographic device is a color electrophotographic device with four detachable process cartridges. Each process cartridge contains a developer of one of the following colors: black, magenta, yellow, and cyan. A photosensitive drum 101 rotates in the direction of the arrow and is uniformly charged by a charging roller 102 to which a voltage is applied from a charging bias power supply. An electrostatic latent image is formed on the surface of the photosensitive drum 101 by exposure light 1011. Meanwhile, developer 109 contained in a developer container 106 is supplied to a developer supply roller 104 by an agitating blade 1010 and transported onto a developing roller 103. A developing blade 108, which is disposed in contact with the developing roller 103, uniformly coats the surface of the developing roller 103 with the developer 109, and imparts an electric charge to the developer 109 through frictional charging. The electrostatic latent image is developed by the application of developer 109 conveyed by a developing roller 103 arranged in contact with the photosensitive drum 101, and is visualized as a developer image. The visualized developer image on the photosensitive drum is transferred to an intermediate transfer belt 1015 supported and driven by a tension roller 1013 and an intermediate transfer belt drive roller 1014 by a primary transfer roller 1012 to which a voltage is applied by a primary transfer bias power supply. The developer images of each color are sequentially superimposed to form a color image on the intermediate transfer belt.

[0105] A transfer material 1019 is fed into the device by a paper feed roller and transported between an intermediate transfer belt 1015 and a secondary transfer roller 1016. A voltage is applied to the secondary transfer roller 1016 from a secondary transfer bias power supply, and the secondary transfer roller 1016 transfers the color image on the intermediate transfer belt 1015 onto the transfer material 1019. The transfer material 1019 onto which the color image has been transferred is fixed by a fixer 1018 and is then discarded outside the device, completing the printing operation. Meanwhile, any developer remaining on the photosensitive drum without being transferred is scraped off by a cleaning blade 105 and stored in a waste developer container 107, and the cleaned photosensitive drum 101 repeats the above-mentioned process. Any developer remaining on the primary transfer belt without being transferred is also scraped off by a cleaning device 1017.

[0106] The present disclosure will be described in detail below based on examples, but the present disclosure is not limited thereto. An elastic roller was produced using the materials shown below. <Elastic Layer Forming Materials> <Acrylonitrile Butadiene Rubber NBR> NBR (trade name: NBR N215SL, acrylonitrile content: 48%, Mooney viscosity ML （１＋４） 100°C: 45, manufactured by ENEOS Material Corporation, abbreviation: N215SL) <Styrene butadiene rubber SBR> SBR (trade name: Asaprene 303, styrene content: 45.0%, Mooney viscosity ML （１＋４） 100°C: 45, manufactured by Asahi Kasei Corporation, abbreviation: A303) <Isoprene rubber IR> Isoprene rubber (trade name: Nipol 2200L, Mooney viscosity ML （１＋４） 100°C: 70, manufactured by Zeon Corporation, abbreviation: 2200L) <Butadiene rubber BR> Butadiene rubber (trade name: UBEPOL BR130B, Mooney viscosity ML （１＋４） 100°C: 29, manufactured by Ube Industries, abbreviated name: BR130B)

[0107] <Electron conductive agent> Carbon black (1) (trade name: Toka Black #5500, manufactured by Tokai Carbon Co., Ltd., abbreviation: #5500) Carbon black (2) (trade name: General-purpose color MA45L, manufactured by Mitsubishi Chemical Corporation, abbreviation: MA45L) Carbon black (3) (trade name: Carbon ECP, manufactured by Lion Specialty Chemicals Co., Ltd., abbreviation: ECP)

[0108] <Vulcanizing agent> Vulcanizing agent (trade name: SULFAX200S, sulfur content 99.5%, manufactured by Tsurumi Chemical Industry Co., Ltd., abbreviated as sulfur)

[0109] <Vulcanization accelerators> Vulcanization accelerator (1) (trade name: Suncerer TBZTD, tetrabenzyl thiuram disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., abbreviation: TBzTD) Vulcanization accelerator (2) (trade name: Noccela TET-G, tetraethyl thiuram disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., abbreviation: TET) Vulcanization accelerator (3) (trade name: ACCEL CZ, N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Kawaguchi Chemical Industry Co., Ltd., abbreviation: Cz)

[0110] <Filler> Filler (1) (trade name: Nanox #30, calcium carbonate, manufactured by Maruo Calcium Co., Ltd., abbreviation: #30)

[0111] <Example 1> [Production of Elastic Roller 1] [1-1. Preparation of Unvulcanized Domain Rubber Composition (1)] The types and amounts of materials shown in Table 1 were mixed in a pressure kneader to obtain an unvulcanized domain rubber composition (1). The mixing conditions were a filling rate of 70 vol%, a blade rotation speed of 30 rpm, and 18 minutes.

[0112]

[0113] [1-2. Preparation of Unvulcanized Rubber Composition (1)] Unvulcanized rubber composition (1) was obtained by mixing the materials of the types and amounts shown in Table 2 in a pressure kneader. The mixing conditions were a filling rate of 70 vol%, a blade rotation speed of 30 rpm, and 18 minutes.

[0114]

[0115] [1-3. Preparation of Unvulcanized Rubber Composition (1) for Forming Elastic Layer] The types and amounts of materials shown in Table 3 were mixed using an open roll to prepare an unvulcanized rubber composition (1) for forming an elastic 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.

[0116]

[0117] 2. Formation of Elastic Layer A round bar with a total length of 252 mm and an outer diameter of 6 mm was prepared, the surface of which was made of free-cutting steel and electroless nickel-plated. Next, using a roll coater, an adhesive, Metalock U-20 (trade name, manufactured by Toyo Kagaku Kenkyusho Co., Ltd.), was applied to the entire circumference of the round bar over a range of 230 mm, excluding 11 mm at each end. In this example, the adhesive-coated round bar was used as a conductive support.

[0118] Next, a die with an inner diameter of 12.5 mm was attached to the tip of a crosshead extruder having a mechanism for feeding a conductive support and a mechanism for discharging an unvulcanized rubber roller, and the temperatures of the extruder and crosshead were adjusted to 80° C., and the conveying speed of the conductive mandrel was adjusted to 60 mm / sec. Under these conditions, unvulcanized rubber composition (1) for forming an elastic layer was fed from the extruder, and the outer periphery of the conductive support was coated with unvulcanized rubber composition (1) for forming an elastic layer in the crosshead, thereby obtaining an unvulcanized rubber roller (1).

[0119] 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) for forming the elastic layer, thereby obtaining a roller with an elastic layer formed on the outer periphery of the conductive support. Thereafter, 10 mm of each end of the elastic layer was cut off, making the longitudinal length of the elastic layer portion 231 mm.

[0120] Next, the surface of the elastic layer was polished with a rotary grindstone. As a result, a roller with a crown of 80 μm, with a diameter of 8.42 mm at positions 90 mm from the center to both ends and a central diameter of 8.5 mm, was obtained. Furthermore, a low-pressure mercury lamp (manufactured by Toshiba Lighting & Technology Corporation) was used as a light source of ultraviolet light, and ultraviolet light with a wavelength of 254 nm was irradiated at an integrated light intensity of 9000 mJ / cm. ２ The surface of the elastic layer was irradiated with light so that the current was equal to or greater than 5000 μA, thereby obtaining an elastic roller (1). Subsequently, the current value of this elastic roller (1) was measured under the conditions described below, and this was taken as the initial current value. The initial current value of this elastic roller (1) was 5000 μA.

[0121] <Preparation of Elastic Rollers (2) to (5)> Elastic rollers (2) to (5) were prepared in the same manner as elastic roller (1), except that the types and amounts of materials shown in Table 4 were used.

[0122]

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

[0124] An electrophotographic process cartridge incorporating the charging roller was left in an environment of 15°C temperature and 10% humidity for 24 hours, and then installed in the main body of an electrophotographic apparatus in the same environment. 60,000 sheets were continuously output until the developer adhered to the surface of the elastic roller (1), causing uneven density and streaks in images with a print rate of 1%. The charging roller with the adhered developer was then removed, and the developer present on the surface was removed with an air blower. Observation of the surface of the charging roller under a microscope confirmed that a large amount of developer-derived contaminants had adhered to the entire surface of the charging roller.

[0125] Using the above method, a used elastic roller (1) having developer-derived contaminants attached thereto was obtained. The current value of this elastic roller was measured under the conditions described below and was taken as the post-use current value. The current value of this used elastic roller (1) was 204 μA. Here, the ratio of the post-use current value to the initial current value was calculated as the post-use current value rate. The post-use current value rate in this case was 4.08%.

[0126] <Removal of Adhered Contaminants to Create a Recycled Elastic Roller> Contaminants adhering to a used elastic roller (1) were removed using the removal device shown in Figure 4A. The used elastic roller (1) was mounted in the removal device and rotated at 500 rpm in the direction of arrow 5a. These removal processes were performed at room temperature (23°C), with the contact friction process lasting 40 seconds. The cleaning portion 508 of the cleaning member 502 was a plate brush made of nylon resin fibers (0.2 mm diameter, 20 mm length, Mohs hardness 3.0; product name: Tynex Nylon 612, manufactured by DuPont Co.) implanted on an aluminum base. The cleaning member 502 was brought into uniform contact with the surface of the elastic roller 507 at a linear pressure of 2 kg per meter to generate friction. After the above steps, the rotation of the elastic roller was stopped, the treated elastic roller was removed, and contaminants derived from the destroyed developer on the surface were removed using air blowing, yielding a recycled elastic roller (1).

[0127] 3. Elastic Roller Property Evaluation [3-1. Confirmation of Matrix Domain Structure] To confirm whether a matrix domain structure was formed, the following confirmation was performed. Ultrathin slices with a thickness of 1 μm were cut from a cross section in the thickness direction of the elastic layer, including the surface of the elastic roller, 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 perpendicular to the longitudinal direction of the conductive member, taking into account the direction in which charge is transported for conductivity. The prepared slices were stained using a staining agent and photographed at 10,000x magnification using a scanning electron microscope (SEM) (trade name: S-4800, manufactured by Hitachi High-Technologies Corporation), to obtain backscattered electron images of the cross section.

[0128] Examples of the staining agent include osmium tetroxide, ruthenium tetroxide, or phosphotungstic acid. A staining agent capable of distinguishing the first, second, and third rubbers was appropriately selected. The elastic layer of the elastic roller (longitudinal length: 230 mm) was divided into five equal sections in the longitudinal direction, and each section was further divided into four equal sections in the circumferential direction to create a total of 20 sections. The above confirmation was performed at a total of 20 locations in the central region of each section. Note that, as shown in Figures 2A and 2B, a connected region in the image was defined as a matrix, and multiple regions surrounded by a matrix, as shown in Figure 3b, were defined as domains. When both matrix regions and domain regions were confirmed in the image, it was determined that the sample had a matrix-domain structure.

[0129] When the matrix domain structure was confirmed at all 20 observation points, it was marked as "OK," and when it was not confirmed at any of the observation points, it was marked as "NG" in Table 5. The evaluation results for each example and comparative example are shown in Table 5.

[0130] [3-2. Impedance Measurement] As a pretreatment, platinum was vapor-deposited onto the outer surface of a rotating elastic roller to prepare a measurement electrode. Masking tape was used to prepare a 1.5 cm wide, uniform electrode in the circumferential direction. By forming this electrode, the contribution of the contact area between the measurement electrode and the conductive member due to the surface roughness of the charging roller can be minimized. Next, an aluminum sheet was tightly wrapped around the electrode, and the aluminum sheet was connected to the measurement electrode of an impedance measuring device (product names: Solartron 1260 and Solartron 1296; manufactured by Solartron Corporation).

[0131] FIG. 7 shows a cross-sectional view of an elastic roller with a measurement electrode formed thereon. In FIG. 7, 121 denotes a conductive support, 122 denotes an elastic layer with a matrix domain structure, 123 denotes a platinum vapor-deposited layer, and 124 denotes an aluminum sheet. FIG. 8 shows a schematic diagram of a charging roller with a measurement electrode formed thereon. 131 denotes a conductive support, 132 denotes an elastic layer with a matrix domain structure, 133 denotes a platinum vapor-deposited layer, and 134 denotes an aluminum sheet. As shown in FIG. 8, the elastic layer with a matrix domain structure was sandwiched between the conductive support 131 and the measurement electrode. The aluminum sheet was then connected to the measurement electrode of an impedance measuring device (Solatron 1260 and Solartron 1296, manufactured by Solartron). Impedance measurements were performed using the conductive support and aluminum sheet as the two electrodes for measurement. Impedance measurements were performed at a temperature of 23°C, a relative humidity of 50%, an AC voltage of 1 Vpp, and a frequency of 10 Hz.

[0132] [3-3. Current Measurement Method] Figure 9 shows a schematic diagram of the electrical resistance measurement device used to measure the current values ​​of the elastic roller, used elastic roller, and regenerated elastic roller. The roller to be measured had both ends of the mandrel 12 pressed against a 40 mm diameter SUS cylindrical electrode 61 by a pressing means (not shown), and rotated in response to the rotation of the SUS cylindrical electrode 61. In this state, a DC voltage was applied to the core of the roller to be measured using a power source, and the voltage across the reference resistor connected in series to the SUS cylindrical electrode 61 was measured to measure the current flowing through the roller. Measurements were performed with a reference resistor of 1 kΩ, a rotation speed of the SUS cylindrical electrode of 30 rpm, and a DC voltage of 200 V applied in an environment with a temperature of 20°C and a humidity of 50% RH. Measurements were performed using a multimeter connected to the reference resistor at a sampling frequency of 100 Hz. The current value at this time was measured for one revolution of the roller using an ammeter, and the average value was calculated and used as the current value of the elastic roller. The volume resistivity ρ was calculated using the measured current value I, internal resistance R, applied voltage V, nip area S between the SUS cylindrical electrode and the elastic roller, and total layer thickness t of the elastic roller using the following formula. The evaluation results for the examples are shown in Tables 5 and 6. ρ=(V / I-R)×S / t

[0133] [3-4. Measurement of the ratio of the sum of the cross-sectional areas of the electronic conductive agent contained in the domains to the sum of the cross-sectional areas of the domains] The backscattered electron image of the cross section obtained by the above-mentioned SEM observation was converted to 8-bit grayscale using image processing software (product name: ImageProPlus, manufactured by Media Cybernetics) to obtain a monochrome image with 256 gradations. Next, the image was inverted and binarized so that the domains in the cross section appeared white, and the domains were extracted, and the sum of the cross-sectional areas of the domains was calculated. Next, the secondary electron image obtained simultaneously with the backscattered electron image acquisition was converted to 8-bit grayscale to obtain a monochrome image with 256 gradations. Next, the image was inverted and binarized so that the electronic conductive agent in the cross section appeared white. At this time, the total area of ​​the electronic conductive agent present in the areas corresponding to the domains separated by binarization of the backscattered electron image was calculated. The ratio of the total cross-sectional area of ​​the electronic conductive agent contained in the domains to the total cross-sectional area of ​​the domains was calculated based on the total cross-sectional area of ​​the domains calculated above and the total cross-sectional area of ​​the electronic conductive agent present in the locations corresponding to the domain portions.

[0134] [3-5. Measurement of Domain Volume Fraction in Elastic Layer] The domain volume fraction was determined by three-dimensional measurement of the elastic layer using 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 investigate the three-dimensional structure, a large number of photographs are obtained by repeating continuous processing and observation, and then the SEM images are subjected to 3D reconstruction processing using computer software to construct a three-dimensional image of the sample structure.

[0135] To specifically measure the domain volume fraction, a cubic sample with a side length of 9 μm was cut from a cross section of the elastic layer, including the surface of the elastic roller, in the thickness direction using a microtome (trade name: Leica EM FCS, manufactured by Leica Microsystems) at a cutting temperature of -100°C. A three-dimensional image of the cut sample, represented by the unit cube 31 in Figure 3, was obtained using an FIB-SEM (manufactured by FEI, Inc.) (described in detail above), and the above-mentioned structure was confirmed from the image. The elastic layer was sampled from nine locations. When the longitudinal length of the elastic layer to be measured is L, one sample was taken from each of three locations located at distances of (1 / 4)L, (2 / 4)L, and (3 / 4)L from one end of the longitudinal direction. Furthermore, one sample was similarly taken from each of the sampled locations at positions 120° and 240° away from each location in the circumferential direction of the roller, for a total of nine samples. Thereafter, three-dimensional measurement was performed by cutting out the sample at intervals of 60 nm using an FIB-SEM and acquiring images, and images of a cube shape with a side length of 9 μm were measured.

[0136] In order to properly observe the domain structure, the same pretreatment as described in 3-1 above was performed. The resulting images were then analyzed using 3D visualization and analysis software Avizo (manufactured by F.E.I.) to calculate the domain volumes of 27 unit cubes with sides of 3 μm contained in one 9 μm cubic sample. Because 9 μm cubic samples were collected from nine locations, the domain volume fraction was calculated from the arithmetic average of a total of 243 measurements. The calculation results for each of the elastic rollers (1) to (5) are shown in Table 5.

[0137] [3-6. Measurement method for volume resistivity of matrix] The volume resistivity of the matrix was measured in contact mode using a scanning probe microscope (SPM) (product name: Q-Scope 250, manufactured by Quesant Instrument Corporation) as follows: The measurement environment was a temperature of 23°C and a relative humidity of 50%.

[0138] First, a slice approximately 2 μm thick was cut from the elastic layer of the elastic roller using a microtome (trade name: Leica EMFCS, manufactured by Leica Microsystems) at a cutting temperature of −100°C. Next, the slice was placed on a metal plate so that one side of the slice corresponding to the cross section of the elastic layer was in contact with the surface of the metal plate. The cantilever of the SPM was then brought into contact with the portion of the slice opposite the side in contact with the surface of the metal plate, corresponding to the matrix. A DC voltage of 50 V was then applied to the cantilever, and the current value was measured. The surface shape of the slice was also observed with the SPM, and the thickness of the measurement point was calculated from the obtained height profile. Furthermore, the area of ​​the recess at the contact point of the cantilever was calculated from the surface shape observation results. The volume resistivity was calculated from the thickness and the area of ​​the recess, and this was taken as the volume resistivity of the matrix. The results are shown in Table 5.

[0139] [3-7. Measurement of domain volume resistivity] The volume resistivity of the domain was measured in the same manner as in the measurement of the volume resistivity of the matrix, except that a voltage of 1 V was applied to the cantilever at a location corresponding to the domain and the current value was measured. The measurement results are shown in Table 5.

[0140] [3-8. Domain Size Measurement Method] The domain size was obtained by image processing of an observation image obtained by observation with a scanning electron microscope (SEM). The measurement sample was a cross-sectional slice obtained in the measurement of the volume resistivity of the matrix. The sample was set on a metal sample stage so that the cross section could be observed, and a surface image was obtained by photographing the sample using a scanning electron microscope (SEM) (product name: S-4800, manufactured by Hitachi High-Technologies Corporation) under the following conditions: acceleration voltage: 5 kV, magnification: 1,000 times, and secondary electron image. Next, the surface image was subjected to image processing (binarization) using image processing software Image-pro plus (product name, manufactured by Media Cybernetics) so that the matrix was white and the domains were black. The circle-equivalent diameters of any 50 domains in the observation image were measured using a counting function, and the arithmetic average value was calculated. The elastic layer was divided into 5 equal parts in the longitudinal direction and 4 equal parts in the circumferential direction, and the arithmetic mean value of the measurement results for the 20 regions was taken as the domain size. The measurement results are shown in Table 5.

[0141] [3-9. Method for Measuring Interdomain Distance] The interdomain distance was obtained by image processing of images obtained with a scanning electron microscope (SEM). Specifically, the interdomain distance was calculated in the same manner as in the above-mentioned domain size measurement method, except that measurements were taken at a magnification of 5,000 times and the image processing method used a function to count the distance between the wall surfaces of the domains. This was divided into 5 equal parts in the longitudinal direction of the elastic layer and 4 equal parts in the circumferential direction, and the arithmetic mean value of the above measurement results in these 20 regions was taken as the interdomain distance. The evaluation results are shown in Table 5.

[0142]

[0143] Evaluation of Regenerated Elastic Roller Characteristics <Current Recovery Rate> The current value of the regenerated elastic roller (1) was measured under an environment of 23°C and 55% RH, and was used as the post-removal current value. The current value of this regenerated elastic roller (1) was 4,324 μA. The ratio of the post-removal current value to the initial current value was calculated as the current recovery rate. The current recovery rate at this time was 86.5%. Contaminants derived from the developer generally have a higher resistance than elastic rollers, and the resistance of the elastic roller increases with the amount of adhesion. Furthermore, strong shear during the recycling process can change the distance between the electronic conductors on the surface of the elastic layer, resulting in increased resistance. Therefore, the current recovery rate can be used as an indicator of the degree of removal of developer-derived contaminants and the change in the distance between the electronic conductors on the surface of the elastic layer.

[0144] <Slight Density Unevenness (Roughness)> If contaminants derived from the developer are not sufficiently removed, further accumulation of contaminants on the surface of the elastic roller during reuse can cause minute density unevenness (hereinafter referred to as roughness) in the image. Therefore, a recycled elastic roller was used, and the occurrence of roughness after reuse was evaluated. The recycled elastic roller (1) was replaced with the developing roller of a new electrophotographic process cartridge and then loaded into the main body of an electrophotographic image forming apparatus. Then, in an environment of 23°C and 55% RH, 30,000 images with a print rate of 1% were output. Then, halftone images were printed in the same environment. Roughness was evaluated according to the following criteria: "A": No roughness was visually observed. "B": Slight roughness was observed. "C": Roughness was observed, but no problems were encountered in use. "D": Roughness was clearly observed. The results are also shown in Table 6.

[0145] [Examples 2 to 5] Various evaluations were carried out in the same manner as in Example 1, except that the elastic rollers (2) to (5) were used as charging members instead of the elastic roller (1) and the contamination formation and regeneration treatment were carried out. The results are shown in Table 6.

[0146] [Example 6] In the contaminant formation and recycling process, an elastic roller (2) was used as the charging member, and the cleaning rubbing member (2) was changed to a roller-shaped cleaning member (2) (material: nylon, Mohs hardness 2.5; product name: SK Tight Type Tight Channel Roller Brush, manufactured by Showa Kogyo Co., Ltd.), but evaluation of various properties and image evaluation were carried out in the same manner as in Example 1. The results are shown in Table 6.

[0147] Example 7 Evaluation of various properties and image quality were performed in the same manner as in Example 1, except that in the contaminant formation and regeneration processes, an elastic roller (2) was used as the charging member, and a cleaning rubbing member (3) in the form of a urethane sponge roller was used. The cleaning rubbing member (3) was manufactured by the following method. A polyether polyol (product name: CARADOL 56-16, manufactured by SHELL) with an average molecular weight of 3,000, obtained by addition polymerization of propylene oxide with glycerin, was used. 100 g of this polyether polyol was mixed with 4.0 g of water as a foaming agent, 0.1 g of triethylenediamine as a catalyst, 0.23 g of stannous octoate (stannous octoate), and 30 g of melamine powder (manufactured by Mitsui Chemicals, Inc., average particle size 1 to 10 μm) and stirred for 5 minutes in a mixer. Then, 51.3 g of tolylene diisocyanate (product name: TDI-80, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added and stirred for 7 seconds to obtain a mixed solution. Next, foam molding was performed in a sponge roller mold (made of SUS304) at 50°C for 20 minutes to form a 5mm thick polyurethane foam layer integrally around a core metal (diameter 6mm, made of SUS304), producing a sponge roller. The Mohs hardness of this urethane sponge was 2.0. The results are shown in Table 6.

[0148] [Example 8] In the contaminant formation and recycling treatment, the elastic roller (2) was used as the charging member, and the cleaning rubbing member (4) was changed (material: fluorine fiber, diameter 0.1 mm, fiber length: processed to 20 mm by cutting treatment, Mohs hardness 4.0, manufactured by Showa Kogyo Co., Ltd.), but evaluation of various properties and image evaluation were carried out in the same manner as in Example 1. The results are shown in Table 6.

[0149] [Example 9] In the contaminant formation and recycling treatment, the elastic roller (2) was used as the charging member, and the cleaning rubbing member (5) (material: nylon conductive fiber, diameter 0.2 mm, fiber length: processed to 20 mm by cutting treatment, Mohs hardness 3.5, manufactured by Showa Kogyo Co., Ltd.) was used instead, and evaluation of various properties and image evaluation were carried out in the same manner as in Example 1. The results are shown in Table 6.

[0150] [Example 10] In the contaminant formation and regeneration treatment, the elastic roller (2) was used as the charging member, and the cleaning rubbing member (6) was changed to (material: abrasive grain-containing nylon fiber, abrasive grain material: SiC, diameter 0.2 mm, fiber length: processed to 20 mm by cutting treatment, Mohs hardness 5.0, manufactured by Showa Kogyo Co., Ltd.), and the evaluation of various properties and image evaluation were carried out in the same manner as in Example 1. The results are shown in Table 6.

[0151] Example 11: In the contamination formation and recycling process, the elastic roller (2) was used as the charging member, and the sheet-type cleaning rubbing member (7) was used. Evaluation of various properties and image evaluation were performed in the same manner as in Example 1. The manufacturing method of the cleaning rubbing member (7) is as follows. A 2 mm thick PET sheet (manufactured by Takiron C.I. Co., Ltd.) was cut into a shape of 230 mm wide x 20 mm long, and a commercially available adhesive was evenly applied to the leading edge 10 mm in the longitudinal direction. A cut-out nylon brush portion used in the cleaning rubbing member (2) was then evenly attached to obtain the cleaning rubbing member (7). The contact pressure between the cleaning rubbing member (7) and the elastic roller was 5.0 N, and the recycling process was performed by abutting them as shown in Figure 4B. The results are shown in Table 6.

[0152] Example 12 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (5), and the evaluation of various properties and image quality were carried out in the same manner as in Example 1. The results are shown in Table 6.

[0153] Example 13 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (6), and the evaluation of various properties and image quality were carried out in the same manner as in Example 1. The results are shown in Table 6.

[0154] Example 14 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (2), and the evaluation of various properties and image quality were carried out in the same manner as in Example 3. The results are shown in Table 6.

[0155] Example 15 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (5), and the evaluation of various properties and image quality were carried out in the same manner as in Example 3. The results are shown in Table 6.

[0156] Example 16 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (6), and the evaluation of various properties and image quality were carried out in the same manner as in Example 3. The results are shown in Table 6.

[0157] Example 17 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (2), and the evaluation of various properties and image quality were carried out in the same manner as in Example 4. The results are shown in Table 6.

[0158] Example 18 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (5), and the evaluation of various properties and image quality were carried out in the same manner as in Example 4. The results are shown in Table 6.

[0159] Example 19 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (6), and the evaluation of various properties and image quality were carried out in the same manner as in Example 4. The results are shown in Table 6.

[0160] Example 20 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (5), and the evaluation of various properties and image quality were carried out in the same manner as in Example 5. The results are shown in Table 6.

[0161] Example 21 In the recycling process, the cleaning rubbing member (1) was replaced with the cleaning rubbing member (6), and the evaluation of various properties and image quality were carried out in the same manner as in Example 5. The results are shown in Table 6.

[0162]

[0163] <Comparative Example 1> The elastic roller (6) in Comparative Example 1 was produced under the same conditions as the elastic roller (1), except that the unvulcanized domain rubber composition was not used when producing the elastic roller (1), and the unvulcanized rubber composition (1) for forming the elastic layer was changed to the unvulcanized rubber composition (6) for forming the elastic layer shown in Tables 7 and 8. The initial current value of this elastic roller (6) was 4000 μA. The evaluation results of the physical properties are shown in Table 10.

[0164]

[0165]

[0166] <Preparation of Elastic Rollers (7) and (8)> Elastic rollers (7) and (8) in Comparative Examples 2 and 3 were prepared in the same manner as elastic roller (1), except that the types and amounts of materials shown in Table 9 were used. The physical properties of elastic rollers (7) and (8) are shown in Table 10. In elastic roller (8) of Comparative Example 3, the electronic conductive agent was uniformly present in both the matrix and the domains, making it impossible to measure the volume resistivity of the domains and the matrix alone, and to evaluate the cross-sectional area ratio of the electronic conductive agent.

[0167]

[0168]

[0169] Comparative Example 1: Evaluation was performed in the same manner as in Example 6, except that elastic roller (2) was replaced with elastic roller (6). The evaluation results are shown in Table 11. In Comparative Example 1, since no matrix domain structure was formed, it is presumed that the distance between the electronic conductive agents changed due to friction during the regeneration process. As a result, the current recovery rate was low at 57.2%, and significant roughness, ranked "D," was confirmed.

[0170] Comparative Example 2 Evaluation was carried out in the same manner as in Example 6, except that the elastic roller (2) was changed to the elastic roller (7). The evaluation results are shown in Table 11. In Comparative Example 2, the formation of a matrix domain structure was confirmed, but the impedance when an AC voltage with an amplitude of 1 V and a frequency of 10 Hz was applied was 1.00 × 10 ８Because the resistance was higher than Ω, insufficient charging occurred due to a lack of total discharge charge. Furthermore, because the content of electronic conductive agent in the domain was low, it was not possible to exhibit excellent mechanical properties, and it is presumed that the distance between conductive particles changed due to friction during the regeneration process. As a result, the current recovery rate was low at 61.2%, and significant roughness, ranked "D," was confirmed.

[0171] Comparative Example 3 Evaluation was performed in the same manner as in Example 6, except that the elastic roller (2) was changed to the elastic roller (7). The evaluation results are shown in Table 11. In Comparative Example 3, the formation of a matrix domain structure was confirmed, but since the electronic conductive agent was uniformly present in the matrix and the domain, the enclosing effect of the matrix could not be achieved, and it is presumed that the distance between the electronic conductive agents changed due to friction during the regeneration process. In addition, the impedance when an AC voltage with an amplitude of 1 V and a frequency of 10 Hz was applied was 1.00 × 10 3 Since the resistance was lower than Ω, the discharge current amount became excessive, resulting in a low current recovery rate of 59.4%, and significant roughness of rank "D" was confirmed.

[0172]

[0173] In Table 11, "roller damage" was rated as "present" when visually discernible scratches were found on the elastic roller after the recycling process. Furthermore, "vertical streaks" in the image evaluation were rated as "C" when streaks caused by roller damage were found in the image during the roughness evaluation, and as "D" when significant streaks were found. In all Examples 1 to 21, neither roller damage nor vertical streaks were found.

[0174] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. Therefore, the following claims are appended to clarify the scope of the present disclosure. This application claims priority based on Japanese Patent Application No. 2024-103316, filed June 26, 2024, the entire contents of which are incorporated herein by reference.

[0175] 11: Recycled elastic roller 12: Conductive mandrel 13: Elastic layer 3a: Matrix 3b: Domain 3c: Electronically conductive agent 3b: Second domain 31: Unit cube 501: Removal device 502: Cleaning member 503: Dust collection means 504: Vacuum chamber 505: Vacuum pump 506: Pump drive motor 507: Elastic roller 508: Cleaning portion 509: Blade-shaped cleaning member 91: Photosensitive drum 92: Charging roller 93: Developing roller 94: Developer supply roller 95: Cleaning blade 96: Developer container 97: Waste developer container 98: Developing blade 99: Developer 910: Agitating blade 101: Photosensitive drum 102: Charging roller 103: Developing roller 104: Developer supply roller 105: Cleaning blade 106: Developer container 107: Waste developer container 108: Development blade 109: Developer 1010: Stirring blade 1011: Exposure light 1012: Primary transfer roller 1013: Tension roller 1014: Intermediate transfer belt drive roller 1015: Intermediate transfer belt 1016: Secondary transfer roller 1017: Cleaning device 1018: Fixing unit 1019: Transfer material 121: Conductive mandrel 122: Elastic layer 123: Platinum vapor deposition layer 124: Aluminum sheet 131: Conductive mandrel 132: Elastic layer 133: Platinum vapor deposition layer 134: Aluminum sheet 61: SUS cylindrical electrode 62: High voltage power supply 63: Internal resistance

Claims

1. A method for producing a recycled elastic roller, comprising a contaminant removal step of removing contaminants adhering to the outer surface of an elastic roller having a support with a conductive outer surface and an elastic layer on the outer surface of the support, wherein the elastic layer has a matrix and domains dispersed in the matrix, the matrix containing a first rubber, and the domains containing a second rubber and an electronic conductive agent, and wherein an electrode is provided on the outer surface of the elastic roller, and an impedance of 1.00 x 10 when an AC voltage of 1 V amplitude and 10 Hz frequency is applied between the outer surface of the support and the electrode in an environment of a temperature of 23°C and a relative humidity of 50% is ３ ~1.00 x 10 ８ Ω, and the contaminant removing step includes a step of rubbing the outer surface of the elastic roller to which the contaminants are adhered.

2. A method for manufacturing a recycled elastic roller as described in claim 1, wherein, upon cross-sectional observation of the elastic layer in the thickness direction, the ratio of the total cross-sectional area of ​​the electronic conductive agent contained in the domains to the total cross-sectional area of ​​the domains is 20.0 to 40.0 area %.

3. The method for producing a recycled elastic roller according to claim 1 or 2, wherein the content of the electronic conductive agent in the domain is 20 to 200 parts by mass per 100 parts by mass of the second rubber.

4. A method for manufacturing a recycled elastic roller according to any one of claims 1 to 3, wherein the contaminant removal step is a step of rubbing the outer surface of the elastic roller with a brush or roller.

5. The method for manufacturing a recycled elastic roller according to claim 4, wherein the brush or roller contains at least one material selected from the group consisting of conductive fiber, abrasive-containing fiber, and urethane-containing resin or rubber.

6. A method for manufacturing a recycled elastic roller according to any one of claims 1 to 5, wherein the first rubber and the second rubber are any of the following combinations: the first rubber is styrene butadiene rubber (SBR) and the second rubber is acrylonitrile butadiene rubber (NBR); 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 acrylonitrile butadiene rubber (NBR) and the second rubber is butadiene rubber (BR).

7. A method for producing a recycled elastic roller according to any one of claims 1 to 6, wherein the content of the electronic conductive agent in the matrix is ​​1 part by mass or less per 100 parts by mass of the first rubber.

8. The method for producing a recycled elastic roller according to any one of claims 1 to 7, wherein the electronic conductive agent contains carbon black.

Images