Method for manufacturing regenerated elastic roller

Abstract

Provided is a method for manufacturing a regenerated elastic roller, the method comprising a contaminant removal step for removing contaminants affixed to the outer surface of an elastic roller that has a support having an electroconductive outer surface and an elastic layer on the outer surface of the support, wherein the method for manufacturing a regenerated elastic roller is characterized in that the outer surface of the elastic layer contains at least a first rubber and a second rubber, the glass transition temperature Tg1 (°C) of the first rubber and the glass transition temperature Tg2 (°C) of the second rubber satisfy the relationship Tg1 > Tg2 or Tg2 > Tg1, and the contaminant removal step includes a step A for removing the contaminants in a state in which Ts satisfies the relationship Tg2 < Ts < Tg1 or Tg1 < Ts < Tg2, where Ts is the temperature (°C) of the outer surface of the elastic roller to which the contaminants have become affixed.

Description

Manufacturing method for recycled elastic roller

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

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

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

[0004] According to the method for manufacturing a recycled elastic roller disclosed in the examples of Patent Document 1, filming (adhered matter) can be effectively removed from a multi-layer elastic roller having a surface layer on an elastic layer. However, the present inventors have recognized that a method for more efficiently removing adhering matter is needed for an elastic roller having an elastic layer on its outer surface.

[0005] The present disclosure provides a method for producing a recycled elastic roller that efficiently removes contaminants adhered to the surface of an elastic roller having an elastic layer on its outer surface, thereby contributing to good image formation.

[0006] The present disclosure provides a method for manufacturing 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 with a conductive outer surface and an elastic layer on the outer surface of the support; wherein the outer surface of the elastic layer comprises at least a first rubber and a second rubber; when the glass transition temperature of the first rubber is Tg1 (°C) and the glass transition temperature of the second rubber is Tg2 (°C), Tg1 and Tg2 satisfy Tg1 > Tg2 or Tg2 > Tg1; and the contaminant removal step comprises: when the temperature of the outer surface of the elastic roller to which the contaminants adhere is Ts (°C), Ts satisfies Tg2 < Ts < Tg1 or Tg1 < Ts < Tg2.

[0007] According to the present disclosure, it is possible to efficiently remove contaminants adhered to the surface even in elastic rollers having an elastic layer on their outer surface, and a method for manufacturing a recycled elastic roller is provided that contributes to good image formation.

[0008] Fig. 1 is a cross-sectional view of an elastic roller according to one embodiment of the present disclosure. Fig. 2 is a schematic diagram showing an example of a cleaning device that removes contaminants using a rubbing member. Fig. 3 is a schematic diagram showing an example of a cleaning device that removes contaminants by spraying a fluid. Fig. 4 is a schematic diagram showing an example of a cleaning device that removes contaminants by spraying abrasive grains. Fig. 5 is a schematic diagram showing an example of a cleaning device that removes contaminants using an adhesive tape.

[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] The present inventors have conducted extensive research into 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. Here, the outer surface of the elastic layer includes at least a first rubber and a second rubber. As a result of their research, they discovered that the elastic roller can be efficiently recycled by performing a contaminant removal step while controlling the temperature of the outer surface of the elastic roller to a temperature between the glass transition temperatures of the first rubber and the second rubber. Hereinafter, the temperature of the outer surface of the elastic roller may be referred to as Ts (°C), the glass transition temperature of the first rubber as Tg1 (°C), and the glass transition temperature of the second rubber as Tg2 (°C).

[0011] The inventors speculate that the reason for this is as follows. Specifically, by controlling the temperature of the outer surface of the elastic roller between the glass transition temperatures of the first rubber and the second rubber, the rubber with a higher glass transition temperature that constitutes the outer surface becomes glassy, ​​and the rubber with a lower glass transition temperature becomes rubbery. In other words, the surface of the elastic roller is in a state where hard glassy portions and soft rubbery portions are mixed. In this state, when an external force is applied to remove contaminants, the glassy portions deform less and the rubbery portions deform more. This difference in deformation causes fine cracks to form uniformly in the contaminants on the surface of the elastic roller, and creates gaps between the roller surface and the contaminant portions. This is thought to reduce the contact area between the roller surface and the contaminants, significantly reducing the adhesion force.

[0012] Furthermore, the glass transition temperature of rubber is generally low. Therefore, when the temperature of the outer surface of the elastic roller is controlled between the glass transition temperature of the first rubber and the glass transition temperature of the second rubber, not only does the adhesiveness of the rubber portion in the glassy state decrease, but the adhesiveness specific to rubber also decreases in the rubber portion in the rubbery state. As a result, the adhesive force per unit area acting between the roller surface and contaminants also decreases. It is believed that these two effects enable the efficient removal of contaminants using the manufacturing method of the reclaimed elastic roller disclosed herein.

[0013] The outer surface of the elastic layer of the recycled elastic roller includes at least a first rubber and a second rubber. When the glass transition temperature of the first rubber is Tg1 (°C) and the glass transition temperature of the second rubber is Tg2 (°C), Tg1 and Tg2 satisfy the relationship Tg1 > Tg2 or Tg2 > Tg1. Preferably, Tg1 and Tg2 satisfy the relationship Tg1 > Tg2. If Tg1 and Tg2 are equal, the outer surface of the elastic roller cannot be made into a state in which a hard glassy state portion and a soft rubbery state portion are mixed, and the effects of the present disclosure cannot be obtained.

[0014] Both Tg1 and Tg2 are preferably less than −15° C., and more preferably not more than −30° C. If Tg1 and Tg2 are within the above ranges, when the temperature Ts of the outer surface of the elastic roller is controlled between Tg1 and Tg2, the adhesiveness characteristic of rubber is reduced even in the rubbery state portion, making it easier to remove contaminants more uniformly.

[0015] The absolute value of the difference between Tg1 and Tg2 is preferably 10°C or more, and more preferably 14°C or more. When the absolute value of the difference is within the above range, the setting range of the temperature Ts of the outer surface of the elastic roller, which is a temperature between Tg1 and Tg2, becomes wider. As a result, in the contaminant removal process, it is easier to set the temperature of the outer surface of the elastic roller to a temperature that increases the difference in deformation between the glassy state portion and the rubbery state portion when an external force is applied. This makes it easier to remove contaminants. The upper limit of the absolute value of the difference between Tg1 and Tg2 is not particularly limited, but may be, for example, 10 to 100°C, or 14 to 90°C. The method for adjusting Tg1 and Tg2 will be described later. Tg1 and Tg2 are measured using a temperature-variable SPM. The specific method will be described in detail.

[0016] <Elastic Roller> The elastic roller and recycled elastic roller can be used as an elastic roller for an electrophotographic image forming apparatus, specifically as a developing roller, a charging roller, a transfer roller, a fixing roller, a cleaning roller, etc.

[0017] An example of a recycled elastic roller is shown in Figure 1. Note that a recycled elastic roller is an elastic roller that has had developer, external additives, and other contaminants adhered to its surface due to image formation or the like removed, and therefore an elastic roller without any contaminants adhered to its surface has the same configuration as a recycled elastic roller. Below, the configuration of an elastic roller will be described using a recycled elastic roller as an example.

[0018] 1 is a cross-sectional view showing the configuration of a cross section perpendicular to the longitudinal direction, which is the axial direction, of an elastic roller 10. The elastic roller 10 has a cylindrical support 11 having a conductive outer surface, and an elastic layer 12 provided on the outer peripheral surface of the support 11, i.e., on the outer surface of the support. However, the shape of the support in the elastic roller is not particularly limited.

[0019] <Support> The material constituting the support 11 can be appropriately selected from materials known in the field of electrophotographic conductive members and materials usable as conductive members. Examples include metals or alloys such as aluminum, stainless steel, conductive synthetic resins, iron, steel, and copper alloys.

[0020] Furthermore, these may be subjected to an oxidation treatment or a plating treatment with chromium, nickel, or the like. As the type of plating, either electroplating or electroless plating can be used. Electroless plating is preferred from the viewpoint of dimensional stability. Examples of the electroless plating used here include nickel plating, copper plating, gold plating, and various other alloy platings. Of these, electroless nickel plating is preferred. The plating thickness is preferably 0.05 μm or more, and considering the balance between work efficiency and rust prevention ability, the plating thickness is preferably 0.10 μm or more and 30.00 μm or less.

[0021] The cylindrical support 11 may have a solid cylindrical shape or a hollow cylindrical shape. The outer diameter of the support is preferably 3 mm or more and 10 mm or less. The length of the support in the longitudinal direction is not particularly limited, but is preferably, for example, 200 mm or more and 300 mm or less. Furthermore, if necessary, the support may be partially processed for installation in an electrophotographic apparatus.

[0022] The elastic layer is preferably provided directly on the support so as to be in contact with the support. Another preferred embodiment is to provide the elastic layer on the outer surface of the support via an intermediate layer made of a conductive resin layer such as a primer layer. The primer layer is more preferably a thin film.

[0023] 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.

[0024] <Elastic Layer> The elastic roller has an elastic layer on the outer surface of the support. The outer surface of the elastic layer preferably corresponds to the outer surface of the elastic roller. The elastic layer preferably contains at least a first rubber and a second rubber. The elastic layer preferably has a matrix and a plurality of domains dispersed in the matrix. The matrix and domains form a phase-separated structure. That is, the elastic layer preferably has a matrix-domain structure having a plurality of domains dispersed in the matrix.

[0025] For example, the rubber that forms the matrix is ​​the component with the highest compounding ratio in the unvulcanized rubber composition used to form the elastic layer, and it provides the required mechanical strength, such as abrasion resistance and low settling. In other words, it is resistant to scratches and deformation even during the contamination removal process, resulting in a higher quality recycled elastic roller.

[0026] It is preferable to use a rubber that has good dispersibility of the electronic conductive agent as the rubber that forms the domain, and to disperse the electronic conductive agent. That is, it is preferable that the domain contains an electronic conductive agent. This is because uniform dispersion of the electronic conductive agent in the rubber can impart excellent electrical properties. If the domain contains an electronic conductive agent, the uniform dispersion of the electronic conductive agent suppresses aggregation of the electronic conductive agent contained in the rubber in the elastic layer due to external stresses such as stress received in the contaminant removal process and friction, and therefore, a decrease in conductivity can be suppressed.

[0027] The matrix and domains preferably satisfy the following requirement (1) or (2). Requirement (1) The matrix contains a first rubber, and the domains contain a second rubber. Requirement (2) The matrix contains a second rubber, and the domains contain the first rubber. By satisfying the above requirements, a matrix-domain structure can be easily formed by utilizing phase separation that occurs when the first rubber and the second rubber are mixed. Furthermore, it is more preferable that the matrix and domains satisfy the above requirement (1).

[0028] The elastic layer may contain a rubber other than the first rubber and the second rubber as long as the effects of the present disclosure are not impaired. In this case, the top two rubbers in terms of content, in no particular order, are designated as the first rubber and the second rubber. For example, the elastic layer may contain a third rubber other than the first rubber and the second rubber. Furthermore, the outer surface of the elastic layer may contain a third rubber other than the first rubber and the second rubber.

[0029] In the present disclosure, a phase-separated structure containing three or more rubber components, having a core-shell domain configuration in a matrix, and in which the matrix and domains are formed from a first rubber and a second rubber, respectively, is also referred to as a matrix-domain structure. For example, the domain may include a core containing the second rubber and an electronic conductive agent, and a shell of a third rubber. When the third rubber is used as the shell, for example, the third rubber may be selected to have an SP value between the SP values ​​of the first rubber and the second rubber.

[0030] <Method for Confirming Phase Separation Structure> The phase separation structure can be confirmed, for example, by the following method. That is, a thin piece of the elastic layer is cut out from the elastic layer to prepare an observation sample. Examples of means for cutting out the thin piece include a razor, a microtome, and an FIB. If necessary, the observation sample is subjected to a treatment (e.g., a staining treatment or a vapor deposition treatment) that makes it easy to distinguish between the first rubber phase and the second rubber phase. Then, the observation sample is observed using a laser microscope, SEM, or TEM. A more specific procedure will be described later.

[0031] <First Rubber> A specific example of the first rubber is preferably at least one selected from the group consisting of natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), butyl rubber (IIR), ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), silicone rubber, and urethane rubber (U).

[0032] The first rubber is more preferably at least one selected from the group consisting of isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), and ethylene propylene diene rubber (EPDM), still more preferably at least one selected from the group consisting of isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), and acrylonitrile butadiene rubber (NBR), and particularly preferably at least one selected from the group consisting of styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR).

[0033] The glass transition temperature Tg1 of the first rubber is preferably less than -15°C, and more preferably -30°C or less. This is because, within the above range, 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 typically used in contact with other members, and therefore an appropriate nip width must be maintained. The lower limit of Tg1 is not particularly limited, but examples include temperatures of -120°C or higher and lower than -15°C, and temperatures of -110°C or higher and -30°C or lower. The glass transition temperature Tg1 of the first rubber can be adjusted by changing the type of first rubber.

[0034] <Second Rubber> Specific examples of the second rubber include at least one selected from the group consisting of natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), butyl rubber (IIR), ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), silicone rubber, and urethane rubber (U).

[0035] The second rubber more preferably contains at least one selected from the group consisting of isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), and ethylene propylene diene rubber (EPDM), even more preferably contains at least one selected from the group consisting of isoprene rubber (IR), styrene butadiene rubber (SBR), and acrylonitrile butadiene rubber (NBR), and particularly preferably contains at least one selected from the group consisting of styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR). Also, the second rubber is preferably different from the first rubber.

[0036] The glass transition temperature Tg2 of the second rubber is preferably less than -15°C, and more preferably -30°C or less. This is because, within the above range, 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 typically used in contact with other members, and therefore an appropriate nip width must be maintained. The lower limit of Tg2 is not particularly limited, but examples include temperatures of -120°C or higher and lower than -15°C, and temperatures of -110°C or higher and -30°C or lower. The glass transition temperature Tg2 of the second rubber can be adjusted by changing the type of second rubber.

[0037] The first rubber and the second rubber are preferably, for example, any of the following combinations: The first rubber is acrylonitrile butadiene rubber (NBR) and the second rubber is styrene butadiene rubber (SBR). The first rubber is styrene butadiene rubber (SBR) and the second rubber is acrylonitrile butadiene rubber (NBR). The first rubber is butadiene rubber (BR) and the second rubber is acrylonitrile butadiene rubber (NBR). The first rubber is acrylonitrile butadiene rubber (NBR) and the second rubber is isoprene rubber (IR).

[0038] The mass ratio of the first rubber to the second rubber in the elastic layer (first rubber:second rubber) is preferably 10:90 to 40:60, and more preferably 20:80 to 40:60.

[0039] 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.

[0040] <Electron Conductive Agent> The elastic layer may contain a known electron conductive agent. The electron conductive agent is preferably conductive particles. Examples of the electron conductive agent include: fine particles and fibers of metals such as aluminum, palladium, iron, copper, and silver; metal oxides such as titanium oxide, tin oxide, and zinc oxide; composite materials in which the surfaces of the above-mentioned metal fine particles, fibers, and metal oxides are surface-treated by electrolysis, spray coating, or mixing and shaking; carbon black and carbon-based fine particles. The electron conductive agent preferably contains carbon black.

[0041] Examples of carbon black include black furnace black, thermal black, acetylene black, and ketjen black. Examples of furnace black include SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, I-ISAF-HS, HAF-HS, HAF, HAF-LS, T-HS, T-NS, MAF, FEF, GPF, SRF-HS-HM, SRF-LM, ECF, and FEF-HS. Examples of thermal black include FT and MT. Examples of carbon-based fine particles include PAN (polyacrylonitrile)-based carbon particles and pitch-based carbon particles.

[0042] By incorporating such an electronic conductive agent, the elastic layer can be ４ ~1 x 10 １０ When an elastic roller having an elastic layer with a volume resistivity in this range is used as a charging roller, a uniform charge can be imparted to the surface of the photosensitive member. In other words, the elastic layer is preferably a conductive layer. The volume resistivity of the elastic layer in the elastic roller is more preferably 1×10 ４ ~1 x 10 ９ It is Ω·cm.

[0043] Furthermore, it is preferable that the domain contains an electronic conductive agent. This is because the domain containing an electronic conductive agent can impart excellent electrical properties. Furthermore, when the domain contains an electronic conductive agent, the uniform dispersion of the electronic conductive agent suppresses aggregation of the electronic conductive agent due to external stresses such as stress received in the contaminant removal process and friction. This makes it easier to suppress a decrease in conductivity.

[0044] Furthermore, the rubber composition for forming the elastic layer may contain, as needed, fillers, processing aids, crosslinking aids, crosslinking accelerators, crosslinking accelerator aids, crosslinking retarders, softeners, plasticizers, dispersants, and the like, which are commonly used as compounding agents for rubber.

[0045] <Roughening Particles> The rubber composition forming the elastic layer may contain spherical particles having a particle diameter in the range of 1 μm to 90 μm. Examples of the spherical particles include at least one selected from the following: phenolic resin particles, silicone resin particles, polyacrylonitrile resin particles, polystyrene resin particles, polyurethane resin particles, nylon resin particles, polyethylene resin particles, polypropylene resin particles, acrylic resin particles, silica particles, and alumina particles. By using such a rubber composition, convex portions derived from the spherical particles can be formed on the outer surface of the elastic layer.

[0046] Examples of methods for mixing these raw materials include a mixing method using a closed type mixer such as a Banbury mixer or a pressure kneader, and a mixing method using an open type mixer such as an open roll.

[0047] The elastic layer can be formed, for example, as follows: An unvulcanized rubber composition for forming the elastic layer is prepared. The unvulcanized rubber composition for forming the elastic layer can be formed, for example, via a method including the following steps (I) to (III). Step (I): A step of preparing an unvulcanized domain composition containing an electronic conductive agent and a first rubber. Step (II): A step of kneading the unvulcanized domain composition and a second rubber to prepare an unvulcanized rubber composition. Step (III): A step of kneading the unvulcanized rubber composition and compounding ingredients to prepare an unvulcanized rubber composition for forming the elastic layer. The mass-based mixing ratio of the first rubber to the second rubber (first rubber:second rubber) in the unvulcanized rubber composition for forming the elastic layer is preferably 10:90 to 40:60. When a third rubber is used, it is preferable to further include the third rubber in step (II).

[0048] Next, a layer of unvulcanized rubber composition for forming an elastic layer is formed on the conductive support. Examples of methods for forming such a rubber composition layer include the following methods (i) to (iii): (i) a method in which the unvulcanized rubber composition is extruded into a tube using an extruder and a core is inserted into the tube; (ii) a method in which the unvulcanized rubber composition is co-extruded into a cylindrical shape around a core using an extruder equipped with a crosshead to obtain a molded product with a desired outer diameter; (iii) a method in which the unvulcanized rubber composition is injected into a mold with a desired outer diameter using an injection molding machine to obtain a molded product. Among these, method (ii) is preferred because it allows for easy continuous production of elastic rollers, requires fewer steps, and is suitable for low-cost production.

[0049] Next, the layer of unvulcanized composition is vulcanized. Vulcanization is carried out by heating, and examples of heating devices include hot air oven heating using a gear oven, heat vulcanization using far infrared rays, and steam heating using a vulcanization can. Among these, hot air oven heating and far infrared heating are preferred because they allow continuous production. The surface of the vulcanized rubber layer, i.e., the elastic layer, can also be ground if necessary.

[0050] Methods for grinding the roller surface include, for example, a traverse grinding method in which a grinding stone or roller is moved in the thrust direction of the roller to grind. Another method is a plunge-cut grinding method in which a grinding stone wider than the roller length is cut into the roller without reciprocating while the roller is rotated around the center of the core shaft. The plunge-cut cylindrical grinding method has the advantage that the entire width of the elastic roller can be ground at once, and is more preferable than the traverse cylindrical grinding method because it can shorten the processing time.

[0051] The surface of the elastic roller may be modified to the extent that it does not affect the glass transition temperature of the rubber forming the elastic layer. Surface modification methods include ultraviolet irradiation, electron beam irradiation, plasma treatment, and corona discharge treatment. These surface treatments may also be combined.

[0052] <Step of Adjusting the Temperature Ts of the Outer Surface of the Elastic Roller Between Tg1 and Tg2> The method for manufacturing a recycled elastic roller preferably includes a step of controlling the temperature Ts of the outer surface of the elastic roller to which contaminants have adhered between Tg1 and Tg2. The step of controlling the temperature Ts of the outer surface of the elastic roller to which contaminants have adhered between Tg1 and Tg2 is not particularly limited. For example, the elastic roller may be contacted with a cooling medium whose temperature is equal to or lower than the glass transition temperature of the rubber contained in the outer surface of the elastic layer. Other examples include placing the elastic roller in an ultra-low temperature freezer capable of cooling down to -80°C and removing it when the temperature Ts of the outer surface of the elastic roller reaches a temperature between Tg1 and Tg2, or contacting the outer surface of the elastic roller with a low-boiling point liquid such as liquid nitrogen, a low-temperature sublimable solid such as dry ice, a cooling plate, a cooling roller, or the like to adjust the temperature Ts of the outer surface of the elastic roller to a temperature between Tg1 and Tg2. Hereinafter, a temperature between Tg1 and Tg2 may be referred to as the desired temperature. The temperature of the outer surface of the elastic roller after this step is preferably −3 to −1° C. lower than the temperature of the outer surface of the elastic roller when the contamination removal step is carried out.

[0053] More specific methods for controlling Ts to a desired temperature include the following: A method of vaporizing liquid nitrogen (boiling point: -196°C) and spraying the generated low-temperature nitrogen gas onto the surface of the elastic roller to set Ts to the desired temperature; A method of immersing the elastic roller in liquid nitrogen to set Ts to the desired temperature; A method of bringing dry ice (sublimation point: -79°C) into contact with the elastic roller to set Ts to the desired temperature; A method of bringing a cooling plate, cooling roller, or the like cooled to about -80°C into contact with the outer surface of the elastic roller to set Ts to the desired temperature. A method using an ultra-low temperature freezer is preferred, as it is easy to control the set temperature.

[0054] <Contaminant Removal Step> The method for manufacturing a recycled elastic roller includes a contaminant removal step of removing contaminants adhering to the outer surface of the elastic roller. The contaminant removal step includes a step A of removing the contaminants when Ts (°C) is the temperature of the outer surface of the elastic roller to which the contaminants are adhering satisfies Tg2<Ts<Tg1 or Tg1<Ts<Tg2. Here, the state where Ts satisfies Tg2<Ts<Tg1 or Tg1<Ts<Tg2 indicates that Ts is between Tg1 and Tg2. As described above, including this step A makes it possible to efficiently remove contaminants adhering to the surface of an elastic roller having an elastic layer on its outer surface.

[0055] Step A is not particularly limited as long as it can remove the contaminants, but examples include a step of applying an external force to the outer surface of the elastic roller to deform the outer surface and remove the contaminants. Deforming the outer surface in this manner makes it easier to generate fine cracks in the contaminants, making them easier to remove. In addition, the outer surface of the elastic roller is the outer surface of the elastic layer. Therefore, even when the outer surface is deformed by applying an external force in step A, the elastic layer's elasticity ensures that the shape of the elastic roller remains the same as before the outer surface was deformed (i.e., the shape before step A). ​​The external force is not particularly limited as long as it can remove the contaminants, and examples include pressure and electromagnetic force, with pressure being preferred.

[0056] The means for applying pressure is not particularly limited, but examples include rubbing, spraying a fluid, spraying abrasive particles, and pressing a member. Step A preferably includes at least one step selected from the group consisting of a step of rubbing the outer surface of the elastic roller to which contaminants have adhered, a step of spraying a fluid against the outer surface of the elastic roller to which contaminants have adhered, a step of spraying abrasive particles against the outer surface of the elastic roller to which contaminants have adhered, and a step of pressing an adhesive tape against the outer surface of the elastic roller to which contaminants have adhered and then peeling off the adhesive tape. These steps are preferred because they effectively apply an external force to the outer surface, making it easy to deform the outer surface of the elastic roller. The environment in which step A is performed may be room temperature or a temperature near Tg1 and Tg2, as long as the effects of the present disclosure can be obtained. More preferably, the contaminants are removed in an environment with a temperature between Tg1 and Tg2, which facilitates maintaining the outer surface temperature Ts of the elastic roller until step A is completed.

[0057] <Step of Rubbing the Outer Surface of the Elastic Roller> In the step of rubbing the outer surface of the elastic roller to which contaminants have adhered, the contaminants are removed by rubbing the outer surface of the elastic roller. A known cleaning device that uses a rubbing member to remove adhered contaminants can be used in this step. Examples of the rubbing member include a brush, a film, and a foam. Among these, a brush-shaped rubbing member is preferred from the viewpoint of minimizing damage to the elastic roller surface. Furthermore, the material of the rubbing member is not particularly limited, but resins such as polyester resin and polyamide resin are preferred from the viewpoint of minimizing damage to the elastic roller surface. In the step of rubbing the outer surface of the elastic roller, the strength of the rubbing against the outer surface of the elastic roller is not particularly limited, but the linear pressure against the outer surface of the elastic roller may be, for example, 1 to 4 kg / m, and preferably 1 to 3 kg / m.

[0058] FIG. 2 is a schematic diagram showing an example of a cleaning device that removes contaminants using a rubbing member. In FIG. 2, a brush 21, which serves as a rubbing member, is pressed against an elastic roller 10, which is supported so as to rotate in the direction of the arrow by a rotary motor (not shown). The elastic roller 10 is then rotated while the brush 21 is in contact with the elastic roller 10, causing the brush 21 to rub against the outer surface of the elastic roller 10. This removes contaminants from the outer surface of the elastic roller 10. Furthermore, a recovery device 22 is provided within the cleaning device. Therefore, the contaminants removed from the outer surface of the elastic roller 10 are recovered by the recovery device 22. The recovery method is not particularly limited, but examples include a method of electrostatically recovering contaminants by applying an electric charge to the contaminants, or a method of recovering contaminants by suction, etc. The time for the process of rubbing the outer surface of the elastic roller is not particularly limited, but may be, for example, 5 to 60 seconds.

[0059] The method for manufacturing a recycled elastic roller preferably includes, after the step of rubbing the outer surface of the elastic roller, a step of blowing compressed air onto the outer surface of the elastic roller to remove contaminants from the outer surface of the elastic roller. By including this step, even if contaminants remain on the outer surface of the elastic roller after the step of rubbing the outer surface of the elastic roller, the remaining contaminants can be removed. The step of blowing compressed air onto the outer surface of the elastic roller to remove contaminants from the outer surface of the elastic roller may be performed in an environment with a temperature between Tg1 and Tg2, but the temperature is not particularly limited.

[0060] <Step of spraying a fluid onto the outer surface of the elastic roller> In the step of spraying a fluid onto the outer surface of the elastic roller to which contaminants have adhered, the contaminants are removed by spraying the fluid onto the outer surface of the elastic roller. A cleaning device that removes contaminants by spraying a fluid such as a gas or liquid can be used for this step. Examples of gases include inert gases such as nitrogen and rare gases, air, and mixtures thereof. Among these, air is preferred from the viewpoint of cost.

[0061] Examples of the liquid include water and organic solvents such as methanol and ethanol. Among these, water is preferred from the viewpoint of low environmental impact. The liquid preferably contains water as a main component. The term "main component" refers to a content of 50% by mass or more. When the liquid contains water, the liquid may contain a water-soluble organic solvent such as methanol, ethanol, or ethylene glycol in order to lower the freezing point. The temperature of the fluid is preferably between Tg1 and Tg2 to minimize changes in the outer surface temperature Ts of the elastic roller. When a liquid is used as the fluid, the method for manufacturing a recycled elastic roller preferably includes, after the step of spraying the fluid, a step of removing the liquid adhering to the outer surface of the elastic roller by blowing compressed air onto the outer surface of the elastic roller.

[0062] FIG. 3 is a schematic diagram showing an example of a cleaning device that sprays a fluid onto the outer surface of an elastic roller to remove contaminants. In FIG. 3, air pressurized by a compressor (not shown) is sprayed from a spray nozzle 31. Meanwhile, the elastic roller 10 is supported by a rotatable support base 32 so as to rotate in the direction of arrow 33. The accelerated air collides with the surface of the rotating elastic roller 10, removing contaminants, for example, derived from the developer, that have adhered to the surface of the elastic roller 10. Furthermore, the spray nozzle 31 moves back and forth from side to side in the direction of arrow 34, spraying the fluid over the entire outer surface of the elastic roller 10. In the process of spraying the fluid onto the outer surface of the elastic roller, the pressure of the fluid against the outer surface of the elastic roller is not particularly limited, but is preferably 1.0 to 10.0 kg / cm. ２ and 2.5 to 7.5 kg / cm ２ The time for the step of spraying the fluid onto the outer surface of the elastic roller is not particularly limited, but may be, for example, 5 to 60 seconds.

[0063] <Step of blasting abrasive grains onto the outer surface of the elastic roller> In the step of blasting abrasive grains onto the outer surface of the elastic roller to which contaminants have adhered, the contaminants are removed by blasting the abrasive grains onto the outer surface of the elastic roller. A blasting device, for example, can be used for this step. Examples of blasting devices include air blasting and centrifugal blasting. Among these, the air blasting method, which can spray abrasive grains from a thin nozzle, is preferred. Examples of air blasting methods include direct pressure and suction methods.

[0064] The following abrasive grains can be used: Inorganic materials include zirconia, glass beads, alumina, titania, sand, baking soda, and dry ice; and organic materials include beads made from synthetic resins such as polyethylene resin, polypropylene resin, polyamide resin, fluororesin, acrylic resin, polyacetal resin, melamine, benzoguanamine, and silicone resin. Of these, dry ice is preferred.

[0065] Fig. 4 is a schematic diagram showing an example of a cleaning device that sprays abrasive grains onto the outer surface of an elastic roller to remove contaminants. In Fig. 4, powder in a pressure tank 42 is sprayed from a spray nozzle 43 by applying pressure using a compressor 41. Meanwhile, the elastic roller 10 is supported so as to rotate in the direction of arrow 44 by a rotary motor (not shown). The accelerated powder collides with the surface of the rotating elastic roller 10, removing contaminants, for example, derived from the developer, that have adhered to the surface of the elastic roller 10. Furthermore, the spray nozzle 43 moves back and forth up and down in the direction of arrow 45, spraying abrasive grains over the entire outer surface of the elastic roller 10. The spray pressure of the abrasive grains in the process of spraying the abrasive grains onto the outer surface of the elastic roller is not particularly limited, but is preferably 1 x 10 ５ ~5 x 10 ５ Pa, and 1×10 ５ ~4 x 10 ５ It is preferable that the pressure be within a range of 5 to 60 Pa. The time required for the step of blasting the abrasive grains onto the outer surface of the elastic roller is not particularly limited, but may be, for example, 5 to 60 seconds.

[0066] The method for manufacturing a recycled elastic roller preferably includes, after the step of blasting abrasive grains onto the outer surface of the elastic roller, a step of blowing compressed air onto the outer surface of the elastic roller to remove contaminants adhered to the outer surface of the elastic roller. By including this step, even if contaminants remain on the outer surface of the elastic roller after the step of blasting abrasive grains onto the outer surface of the elastic roller, the remaining contaminants can be removed.

[0067] <Step of pressing adhesive tape onto the outer surface of an elastic roller and then peeling off the adhesive tape> In the step of pressing adhesive tape onto the outer surface of an elastic roller to which contaminants have adhered and then peeling off the adhesive tape, the contaminants are removed by pressing and peeling off the adhesive tape. A known cleaning device that presses adhesive tape onto the outer surface of an elastic roller and then peels off the adhesive tape to remove the contaminants can be used for this step. Before pressing the adhesive tape, the outer surface of the elastic roller may be brought into contact with a flat plate such as a glass plate or a roller to cause cracks in the contaminants before this step is performed.

[0068] FIG. 5 is a schematic diagram showing an example of a cleaning device that removes contaminants using adhesive tape. In FIG. 5 , the adhesive surface of adhesive tape 51 is brought into contact with elastic roller 10, which is supported for rotation, while being pressed by backup roller 52, thereby removing contaminants from the surface of elastic roller 10. Adhesive tape 51 is supported by guide roller 53 and wound in the direction of arrow 54, ensuring that a fresh adhesive surface always comes into contact with the outer surface of elastic roller 10. After pressing the adhesive tape against the outer surface of the elastic roller, the pressure of backup roller 52 when pressing the adhesive tape during the tape peeling process may be 200 to 1000 N / m, preferably 200 to 700 N / mPa, in terms of drawing pressure. The drawing pressure is determined by sandwiching a 30 μm-thick SUS plate between two 30 μm-thick SUS plates and inserting it into the contact area between the backup roller and the elastic roller. Next, the SUS plate for drawing was pulled, and the force when it was pulled out at a speed of 0.5 cm / sec was measured, and this was converted into a value equivalent to the linear pressure per meter of width of the SUS plate.

[0069] The present disclosure will be described below based on examples, but the present disclosure is not limited to these examples.

[0070] An elastic roller was produced using the following materials: <Elastic Layer Forming Materials> <Acrylonitrile Butadiene Rubber NBR> NBR (1) (trade name: NBR N230SV, acrylonitrile content: 35%, Mooney viscosity ML （１＋４） 100°C: 32, manufactured by ENEOS Material Corporation, abbreviation: N230SV) NBR (2) (trade name: NBR N215SL, acrylonitrile content: 48%, Mooney viscosity ML （１＋４） 100°C: 45, manufactured by ENEOS Material Corporation, abbreviation: N215SL) NBR (3) (trade name: Nipol DN401LL, acrylonitrile content: 18%, Mooney viscosity ML （１＋４） 100°C: 32, manufactured by Zeon Corporation, abbreviation: DN401LL)

[0071] <Styrene butadiene rubber SBR> SBR (product name: ESBR1507, styrene content: 23.5%, Mooney viscosity ML （１＋４） 100°C: 35, manufactured by ENEOS Materials Corporation, abbreviation: 1507) <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)

[0072] <Electron conductive agent> Carbon black (product name: Toka Black #7270SB, DBP absorption: 62 cm ３ / 100g, manufactured by Tokai Carbon Co., Ltd., abbreviation: #7270) <Vulcanizing agent> Vulcanizing agent (trade name: SULFAX PMC, sulfur content 97.5%, manufactured by Tsurumi Chemical Industry Co., Ltd., abbreviation: sulfur)

[0073] <Vulcanization accelerators> Vulcanization accelerator (1) (trade name: Suncerar TBZTD, tetrabenzyl thiuram disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., abbreviation: TBzTD) Vulcanization accelerator (2) (trade name: Noccela TET, tetraethyl thiuram disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., abbreviation: TET) Vulcanization accelerator (3) (trade name: ACCEL CZ, N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Kawaguchi Chemical Industry Co., Ltd., abbreviation: Cz) <Filler> Filler (trade name: Nanox #30, calcium carbonate, manufactured by Maruo Calcium Co., Ltd., abbreviation: #30)

[0074] <Example 1> <Production of Elastic Roller 1> [1-1. Preparation of Unvulcanized Domain Composition 1] The materials of the types and amounts shown in Table 1 were mixed in a pressure kneader to obtain an unvulcanized domain composition 1. The mixing conditions were a filling rate of 70 vol%, a blade rotation speed of 30 rpm, and 18 minutes.

[0075] [1-2. Preparation of Unvulcanized Rubber Composition 1] The materials shown in Table 2 in their types and amounts were mixed in a pressure kneader to obtain Unvulcanized Rubber Composition 1. The mixing conditions were a filling rate of 70 vol%, a blade rotation speed of 30 rpm, and 18 minutes.

[0076] [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 rubber composition 1 for forming the 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.

[0077] [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 the free-cutting steel bar was electrolessly nickel-plated. Next, using a roll coater, an adhesive, Metalock U-20 (trade name, manufactured by Toyo Kagaku Kenkyusho Co., Ltd.), was applied to the entire circumference of the round bar, excluding 11 mm at each end. In this example, the adhesive-coated round bar was used as a conductive support.

[0078] Next, a die with an inner diameter of 10.4 mm was attached to the tip of a crosshead extruder having a mechanism for feeding the conductive support and a mechanism for discharging the unvulcanized rubber roller, and the temperatures of the extruder and the crosshead were adjusted to 80° C., and the conveying speed of the conductive support was adjusted to 60 mm / sec. Under these conditions, unvulcanized rubber composition 1 for forming 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.

[0079] Next, the unvulcanized rubber roller 1 was placed in a hot air vulcanizing furnace at 170°C and heated for 60 minutes to vulcanize the unvulcanized rubber composition 1, thereby obtaining a roller having an elastic layer formed on the outer periphery of the conductive support. Thereafter, both ends of the elastic layer were cut off to make the longitudinal length of the elastic layer portion 231 mm.

[0080] Next, the surface of the elastic layer was polished with a grindstone. As a result, an elastic roller 1 was obtained, with a diameter of 9.62 mm at positions 90 mm from the center to both ends, a central diameter of 9.7 mm, and a crown amount of 80 μm. Next, the current value of this elastic roller 1 was measured under the conditions described below, and this was taken as the initial current value.

[0081] <Current Measurement Method> A 500 g load was applied to each exposed support portion at both ends of the elastic roller, and the outer surface of the elastic roller was abutted against a 40 mm diameter SUS cylindrical electrode 41. The cylindrical electrode was rotated in this state, causing the recycled elastic roller to rotate along with it. Once the rotation stabilized, a voltage was applied to the support from a DC power source, and a voltage of 200 V was applied between the support and the cylindrical electrode. The environment during this operation was 20°C and 50% RH (relative humidity). The current value at this time was measured using an ammeter for one revolution of the elastic roller, and the average value was calculated to determine the current value of the recycled 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 thickness t of the elastic layer of the elastic roller, using the following formula: ρ = (V / I-R) x S / t

[0082] <Measurement of the Glass Transition Temperature Tg1 of the First Rubber and the Glass Transition Temperature Tg2 of the Second Rubber> First, the elastic roller was cross-sectioned with a razor. Then, a 1 μm thick thin section was cut out using a microtome (trade name: Leica EM FCS, manufactured by Leica Microsystems) at a cutting temperature of -100°C. One side of the thin section (hereinafter also referred to as the "ground surface") was grounded on a silicone wafer. Then, on the side of the thin section opposite the ground surface (hereinafter also referred to as the "measurement surface"), which corresponds to the matrix and does not contain two or more types of rubber between the measurement surface and the ground surface, a phase image was measured in 2 μm square using the tapping mode of a scanning probe microscope (SPM) (trade name: E-Sweep, manufactured by Hitachi High-Tech Science).

[0083] Furthermore, to calculate Tg, observations were made while changing the temperature in the SPM measurement chamber from -70°C to +30°C in 2°C increments. Then, a phase histogram was calculated at each temperature, and the phase peak position was calculated. The relative phase value represents the difference in the flexibility of each rubber. When the phase difference between rubbers is large, the phase histogram has a phase peak originating from each rubber. Furthermore, when the temperature in the SPM measurement chamber is changed, the phase peak originating from each rubber shifts to a lower angle near Tg. In other words, the temperature at which each peak shifts represents the Tg of each rubber.

[0084] Furthermore, even if there is no significant change in phase between the glassy and rubbery states of each rubber, a significant difference in phase may occur between the glassy and rubbery states. In such cases, Tg is measured using the following procedure. When an SPM phase image is acquired and two or more types of rubber are included in the phase image, the peaks overlap when the chamber is at a low temperature. On the other hand, as the chamber temperature is increased, the histogram peak splits into two. This is because the rubber splits into glassy and rubbery states. Furthermore, by further increasing the chamber temperature, the peaks overlap again. In the above case, the temperature at which the peaks split into two represents the Tg of the rubber on the lower side, and the temperature at which the peaks overlap again represents the Tg of the rubber on the higher side. The glass transition temperature Tg1 of the first rubber in the elastic layer of the elastic roller 1 was −36°C, and the glass transition temperature Tg2 of the second rubber was −52°C.

[0085] <Confirmation of the Phase Separation Structure Between the Matrix and Domains and the Electronic Conductive Agent in the Elastic Layer> The phase separation structure between the matrix and domains and the electronic conductive agent in the elastic layer were confirmed as follows. Specifically, ultrathin sections 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 1, using a microtome (trade name: Leica EM FCS, manufactured by Leica Microsystems) at a cutting temperature of −100°C. When cutting the sections, the cross-sectional direction was perpendicular to the longitudinal direction of the elastic roller, taking into account the direction in which electric charges are transported for electrical conductivity. The prepared sections were stained using a staining agent and photographed at 10,000x magnification using a scanning electron microscope (SEM) (trade name: S-4800, manufactured by Hitachi High-Technologies Corporation) to obtain cross-sectional images. Examples of staining agents include osmium tetroxide, ruthenium tetroxide, and phosphotungstic acid. Staining agents that can distinguish the first rubber and the second rubber were selected. When multiple domains were dispersed in the matrix in the cross-sectional image and the domains were not connected to each other but existed independently, it was determined that the structure was a matrix domain structure.

[0086] Next, a section prepared separately using the same method as above was placed on a metal plate in an environment with a temperature of 23°C and a relative humidity of 50%. Using a scanning probe microscope (SPM) (product name: E-sweep, manufactured by Hitachi High-Tech Science Corporation) and an SI-DF3-R SPM cantilever, the section was observed to identify the domains in a phase image and obtain a height image of the domains. Next, a current image of the domains was obtained by applying 0.5 V in SIS-AFM mode. The height image and current image of the domains were then superimposed, and if current was flowing in the convex portions, it was determined that the domains contained an electronic conductive agent. The phase-separated structure consisting of the first rubber and the second rubber in the elastic layer of the elastic roller 1 was a matrix-domain structure, and the electronic conductive agent, carbon black, was present in the domains.

[0087] <Method for forming developer-derived contaminants> The elastic roller 1 obtained above was incorporated into an electrophotographic process cartridge as a charging roller, and an image was output using an electrophotographic image forming apparatus. The electrophotographic image forming apparatus used was an electrophotographic laser printer (product name: LaserJet Pro M203dw, manufactured by HP Corporation), and the electrophotographic process cartridge used was one specifically for this electrophotographic image forming apparatus.

[0088] An electrophotographic process cartridge incorporating the charging roller was left in an environment at a temperature of 15°C and a relative humidity of 10% for 24 hours, and then installed in an electrophotographic apparatus main body in the same environment. Then, 60,000 sheets were continuously output until the developer adhered to the surface of the elastic roller 1, causing uneven density and streaks in images with a print rate of 1%. Next, the charging roller with the developer-derived contaminants adhered thereto was removed, and the surface of the charging roller was observed under an optical microscope. It was confirmed that a large amount of developer-derived contaminants had adhered to the entire surface of the charging roller. Using the above method, a used elastic roller 1 with developer-derived contaminants adhered thereto was obtained.

[0089] <Step of setting the temperature Ts of the outer surface of the elastic roller between Tg1 and Tg2> The used elastic roller 1 to which developer-derived contaminants had adhered by the above procedure was placed in a freezer (product name: SF-53U, manufactured by Nippon Freezer Co., Ltd.) set to -42°C and left there for 24 hours. Thereafter, the temperature Ts of the outer surface of the used elastic roller 1 was measured in the same environment and found to be -42°C. The temperature setting of the freezer in this step was set to a temperature between Tg1 and Tg2 of each elastic roller.

[0090] <Contaminant Removal Step> After the step of bringing the temperature Ts of the outer surface of the elastic roller to a temperature between Tg1 and Tg2, one of the following steps (i) to (iv) was carried out as a contaminant removal step.

[0091] (i) Step of Rubbing the Outer Surface of the Elastic Roller: The used elastic roller 1, whose outer surface temperature Ts had been adjusted to -42°C using the above procedure, was mounted in the device shown in Figure 2. The elastic roller was then rotated at 200 rpm, and its outer surface was rubbed with a cleaning brush. This step was initiated after confirming that the outer surface temperature Ts of the elastic roller had reached -40°C using a non-contact thermometer in a 0°C environment. The rubbing time was 15 seconds. The brush 21 used was a plate brush made of polyamide resin fibers (0.2 mm diameter, 20 mm length; product name: Tynex Nylon 612, manufactured by DuPont Co.) implanted on an aluminum base. The brush 21 was brought into uniform contact with the surface of the elastic roller at a linear pressure of 2 kg / m and rubbed. As a result, developer-derived contaminants were removed from the surface of the elastic roller. The elastic roller 1 was then removed from the device, and small amounts of contaminants present on the surface of the elastic roller were completely removed using air blowing in a 0°C environment, yielding a reclaimed elastic roller 1. The current value of this regenerated elastic roller 1 was measured under the above-mentioned conditions and was taken as the post-regeneration current value.

[0092] (ii) Step of spraying fluid onto the outer surface of the elastic roller The used elastic roller 1, whose outer surface temperature Ts had been reduced to -42°C by the above procedure, was attached to the device shown in Figure 3. The spray nozzle 31 was installed 2 cm from the surface of the elastic roller so as to face the center of rotation of the elastic roller 10. The roller was rotated at 60 rpm, and air was sprayed while the spray nozzle 31 was moved back and forth in the longitudinal axis direction of the roller at a speed of 1.3 cm / s. This step was started after it was confirmed that the temperature Ts of the outer surface of the elastic roller had reached -40°C using a non-contact thermometer in a 0°C environment. At this time, a pressure of 5.0 kg / cm was applied to the outer surface of the elastic roller. ２ The air pressure was adjusted so that a pressure of 1000 kJ / cm was applied, and the spraying time was set to 20 seconds. Next, the elastic roller 1 was removed from the device to obtain a regenerated elastic roller 1. The current value of this regenerated elastic roller 1 was measured under the above-mentioned conditions and was defined as the post-regeneration current value.

[0093] (iii) Step of spraying abrasive grains onto the outer surface of the elastic roller The used elastic roller 1, whose outer surface temperature Ts had been reduced to -42°C by the above procedure, was attached to the device shown in Figure 4. The spray nozzle 43 was installed 5 cm from the surface of the elastic roller so as to face the center of rotation of the elastic roller 1. The roller was rotated at 60 rpm, and dry ice with a particle diameter of 0.1 mm was sprayed while the spray nozzle 43 was moved back and forth in the longitudinal axis direction of the roller at a speed of 1.0 cm / s. This step was started after it was confirmed that the temperature Ts of the outer surface of the elastic roller had reached -40°C using a non-contact thermometer in a room temperature environment (23°C). The spray pressure was 2 x 10 ５ The pressure was set to 100 Pa, and the spraying time was 25 seconds. As a result of the spraying, contaminants derived from the developer were removed from the surface of the elastic roller. Next, the elastic roller 1 was removed from the device, and small amounts of contaminants present on the surface of the elastic roller were completely removed by air blowing in an environment of 0°C, thereby obtaining a regenerated elastic roller 1. The current value of this regenerated elastic roller 1 was measured under the above-mentioned conditions and was taken as the post-regeneration current value.

[0094] (iv) Step of pressing adhesive tape onto the outer surface of the elastic roller and then peeling off the adhesive tape. The used elastic roller 1, whose outer surface temperature Ts had been adjusted to -42°C using the above procedure, was attached to the device shown in Figure 5. The elastic roller 10 was then rotated three times on adhesive tape 51 (product name: Kraft Tape No. 500, manufactured by Sekisui Chemical Co., Ltd.). This step was started after confirming that the outer surface temperature Ts of the elastic roller had reached -40°C using a non-contact thermometer in a 0°C environment. The pressing force between the backup roller 52 and the elastic roller 1 was set to a drawing pressure of 500 N / m. The elastic roller 1 was then removed from the device, and a regenerated elastic roller 1 was obtained. The current value of this regenerated elastic roller 1 was measured under the conditions described above and used as the post-regeneration current value.

[0095] <Evaluation of characteristics of recycled elastic roller> <Evaluation of surface damage after recycling> The surface of the recycled elastic roller 1 was visually observed to evaluate surface damage. The degree of surface damage was evaluated according to the following criteria. "A": No minor scratches or dents were observed visually. "B": 1 to 5 minor scratches or dents were observed visually. "C": 6 to 10 minor scratches or dents were observed visually. "D": 11 or more significant scratches or dents were observed visually. The results are shown in Table 8.

[0096] <Current Recovery Rate> The ratio of the current value after reclamation to the initial current value was calculated as the current recovery rate. Contaminants derived from the developer generally have a higher resistance than the elastic roller, and the resistance of the elastic roller increases with the amount of adhesion. Furthermore, repeated stress during the reclamation process can change the distance between the electronic conductive agents dispersed in the elastic layer, resulting in increased resistance. Therefore, the current recovery rate can be used as an indicator of the degree of removal of contaminants derived from the developer and the change in the distance between the electronic conductive agents on the surface of the elastic layer. The current recovery rate was evaluated according to the following criteria: "A": Current recovery rate is 90% or more. "B": Current recovery rate is 80% or more but less than 90%. "C": Current recovery rate is 60% or more but less than 80%. "D": Current recovery rate is 40% or more but less than 60%. The results are shown in Table 8.

[0097] <Charge Stability Evaluation> When a recycled elastic roller is used as a charging roller, if the removal of developer-derived contaminants is insufficient, further developer-derived contaminants will accumulate on the surface of the elastic roller during reuse, causing minute white spots in the image. The recycled elastic roller 1 obtained above was incorporated into an electrophotographic process cartridge as a charging roller, and images were output using an electrophotographic image forming apparatus. The electrophotographic image forming apparatus used was an electrophotographic laser printer (product name: LaserJet Pro M203dw, manufactured by HP Corporation), and the electrophotographic process cartridge used was one specifically designed for this electrophotographic image forming apparatus.

[0098] An electrophotographic process cartridge incorporating the charging roller was left in an environment at a temperature of 15°C and a relative humidity of 10% for 24 hours, and then installed in an electrophotographic apparatus in the same environment. Next, 24,000 images were printed on A4-size paper, each with a 4-point "E" printed at a coverage rate of 1%. The electrophotographic image output was performed in an intermittent mode, in which the rotation of the electrophotographic photoreceptor was stopped for 7 seconds after each print. Image output in the intermittent mode involves more friction between the charging roller and the electrophotographic photoreceptor than when electrophotographic images are output continuously, and therefore is considered to be a more severe evaluation condition for the charging roller. Next, a halftone image was output, and the resulting image was observed visually and with a magnifying glass and evaluated according to the following criteria: "A": No white dots were observed even with a magnifying glass. "B": No white dots were observed visually. "C": Slight white dots were observed visually. "D": White spots were visually observed over the entire area. The results are shown in Table 8.

[0099] Examples 2 to 3 Preparation of Elastic Rollers 2 to 3 Elastic rollers 2 to 3 were prepared in the same manner as elastic roller 1, except that the types and amounts of materials shown in Table 4 were used. The physical properties of the obtained elastic rollers 2 to 3 were measured in the same manner as elastic roller 1. Used elastic rollers 2 to 3 were prepared in the same manner as in Example 1, except that elastic rollers 2 to 3 were used. The obtained used elastic rollers 2 to 3 were subjected to the contaminant removal process in the same manner as used elastic roller 1, except that the outer surface temperatures Ts shown in Table 8 were set to obtain regenerated elastic rollers 2 to 3. The obtained regenerated elastic rollers 2 to 3 were each subjected to the evaluation described in Example 1. The results are shown in Table 8.

[0100] <Example 4> <Preparation of Elastic Roller 4> [1-2. Preparation of Unvulcanized Rubber Composition 4] Unvulcanized rubber composition 4 was prepared in the same manner as elastic roller 1, except that the types and amounts of each material were changed as shown in Table 5.

[0101] [1-3. Preparation of Rubber Composition 4 for Forming Elastic Layer] Unvulcanized rubber composition 4 for forming elastic layer was prepared in the same manner as elastic roller 1, except that the types and amounts of each material were changed as shown in Table 6.

[0102] [2. Forming of Elastic Layer] Elastic roller 4 was prepared by molding in the same manner as elastic roller 1, except that unvulcanized rubber composition 4 was used for forming the elastic layer. Used elastic roller 4 was prepared in the same manner as in Example 1, except that elastic roller 4 was used. The obtained used elastic roller 4 was subjected to the contaminant removal process in the same manner as used elastic roller 1, except that the outer surface temperature Ts shown in Table 8 was set to obtain regenerated elastic roller 4. The obtained regenerated elastic roller 4 was subjected to the evaluation described in Example 1. The results are shown in Table 8.

[0103] Examples 5 to 8 Preparation of Elastic Rollers 5 to 8 Elastic rollers 5 to 8 were prepared in the same manner as elastic roller 1, except that the types and amounts of materials shown in Table 7 were used.

[0104] Used elastic rollers 5 to 8 were produced in the same manner as in Example 1, except that elastic rollers 5 to 8 were used. The obtained used elastic rollers 5 to 8 were subjected to the contaminant removal process in the same manner as used elastic roller 1, except that the outer surface temperatures Ts shown in Table 8 were set to obtain regenerated elastic rollers 5 to 8. The obtained regenerated elastic rollers 5 to 8 were each subjected to the evaluation described in Example 1. The results are shown in Table 8.

[0105] Comparative Example 1 Unvulcanized rubber composition 9 was prepared in the same manner as unvulcanized rubber composition 1, except that the types and amounts of each material were changed as shown in Table 9.

[0106] Unvulcanized rubber composition 9 for forming elastic layer was prepared in the same manner as rubber composition 1 for molding elastic layer, except that the types and amounts of each material were changed as shown in Table 10.

[0107] [2. Forming of Elastic Layer] Elastic roller 9 was prepared by molding in the same manner as elastic roller 1, except that unvulcanized rubber composition 9 for forming the elastic layer was used. Used elastic roller 9 was prepared in the same manner as in Example 1, except that elastic roller 9 was used. The obtained used elastic roller 9 was subjected to the contaminant removal process in the same manner as used elastic roller 1, except that the outer surface temperature Ts shown in Table 11 was set to obtain regenerated elastic roller 9. The obtained regenerated elastic roller 9 was subjected to the evaluation described in Example 1. The results are shown in Table 11.

[0108] Comparative Examples 2 and 3: Used elastic rollers were produced in the same manner as in Example 1, except that the elastic rollers shown in Table 11 were used. The resulting used elastic rollers were subjected to the same contaminant removal process as used elastic roller 1, except that the outer surface temperature Ts shown in Table 11 was set to a temperature of -100°C, to obtain regenerated elastic rollers. Regarding Ts in Comparative Example 3, used elastic roller 8 was immersed in liquid nitrogen to set Ts to -100°C, and the removal process was also carried out in a thermostatic chamber at -40°C to suppress a rise in Ts temperature. The resulting regenerated elastic rollers were subjected to the evaluations described in Example 1. The results are shown in Table 11.

[0109] 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. 2024-103379, filed June 26, 2024, the entire contents of which are incorporated herein by reference.

[0110] 10: Elastic roller, 11: Support, 12: Elastic layer, 21: Brush, 22: Recovery device, 31: Spray nozzle, 32: Support stand, 41: Compressor, 42: Pressure tank, 43: Spray nozzle, 51: Adhesive tape, 52: Backup roller, 53: Guide roller

Claims

1. A method for manufacturing a recycled elastic roller, comprising a contamination removal step of removing contamination adhered 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 outer surface of the elastic layer comprises at least a first rubber and a second rubber, and when the glass transition temperature of the first rubber is Tg1 (°C) and the glass transition temperature of the second rubber is Tg2 (°C), Tg1 and Tg2 satisfy Tg1 > Tg2 or Tg2 > Tg1, and the contamination removal step comprises a step A of removing the contamination in a state where Ts (°C) is the temperature of the outer surface of the elastic roller to which the contamination has adhered, Ts satisfies Tg2 < Ts < Tg1 or Tg1 < Ts < Tg2.

2. The method for producing a recycled elastic roller according to claim 1, wherein step A is a step of applying an external force to the outer surface of the elastic roller to deform the outer surface and remove the contaminants.

3. The method for producing a recycled elastic roller according to claim 1 or 2, wherein both Tg1 and Tg2 are lower than -15°C.

4. The method for manufacturing a recycled elastic roller according to any one of claims 1 to 3, wherein the absolute value of the difference between Tg1 and Tg2 is 10°C or more.

5. A method for manufacturing a recycled elastic roller according to any one of claims 1 to 4, wherein step A includes at least one step selected from the group consisting of: a step of rubbing the outer surface of the elastic roller to which the contaminants are adhered; a step of spraying a fluid onto the outer surface of the elastic roller to which the contaminants are adhered; a step of spraying abrasive grains onto the outer surface of the elastic roller to which the contaminants are adhered; and a step of pressing an adhesive tape onto the outer surface of the elastic roller to which the contaminants are adhered, and then peeling off the adhesive tape.

6. A method for manufacturing a recycled elastic roller according to any one of claims 1 to 5, wherein the elastic layer has a matrix and a plurality of domains dispersed in the matrix, and the matrix and the domains satisfy the following requirement (1) or (2): Requirement (1) The matrix contains the first rubber, and the domains contain the second rubber; Requirement (2) The matrix contains the second rubber, and the domains contain the first rubber.

7. The method for producing a regenerated elastic roller according to claim 6, wherein the domains include an electronic conductive agent.

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

9. The method for producing a recycled elastic roller according to any one of claims 1 to 8, wherein the outer surface of the elastic layer further comprises a third rubber.

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