Developing roller, process cartridge and electrophotographic image forming apparatus

Abstract

To provide a developing roller which has a high process speed and can suppress toner transport defects even when used under various environments for a long period of time with reduced driving torque. A developing roller includes a substrate having a conductive outer surface and a conductive layer on the outer surface of the substrate, wherein the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region, the first region and the second region being disposed adjacent to each other, the first region being disposed on the outer surface of the conductive layer, and the impedance of the outer surface of the developing roller is 1.0×10 6 Ω or more, and the potential of the outer surface of the developing roller satisfies a predetermined relationship.

Description

[Technical Field]

[0001] The present disclosure relates to a developing roller, a process cartridge, and an electrophotographic image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art With the recent increase in environmental awareness, electrophotographic image forming apparatuses (electrophotographic apparatuses) are being required to not only improve device performance such as increasing process speed, but also to conserve energy and resources. Increasing the process speed of an electrophotographic device tends to increase the drive torque required to drive the device, resulting in increased energy consumption. Therefore, in order to save energy while increasing the process speed, it is necessary to significantly reduce the drive torque of the electrophotographic device. Furthermore, in order to conserve resources, there is a demand for electrophotographic members that can be used for a long period of time by simply replenishing toner, rather than replacing the entire device along with the process cartridge as in the past.

[0003] The developing device accounts for a large proportion of the driving torque of an electrophotographic device, and the torque generated between the toner supply roller and the developing roller accounts for the majority of that torque. Therefore, reducing the driving torque between the toner supply roller and the developing roller can significantly contribute to increasing process speed and energy conservation. To reduce the driving torque, for example, reducing the contact area of ​​the toner supply roller with the developing roller or reducing the difference in peripheral speed between the developing roller and the toner supply roller can be considered. However, reducing the contact area of ​​the toner supply roller or reducing the difference in peripheral speed as described above can result in an insufficient amount of toner being supplied from the toner supply roller to the developing roller, which can make it impossible for the developing roller to transport toner.

[0004] To address the issues associated with reducing the drive torque, a developing roller whose outer surface is composed of an insulating portion and a conductive portion has been investigated. When this developing roller is used in an electrophotographic device, the insulating portion of the surface becomes charged due to frictional charging between the developing roller and toner, and due to injection charging, which injects charge due to a potential difference between the developing roller and other contacting members, primarily the developing blade. When the insulating portion becomes charged, a small electric field is formed due to the potential difference between the charged insulating portion and the highly conductive, uncharged conductive portion. This small electric field generates a gradient force around the developing roller, which is a force acting toward the outer surface of the developing roller. This gradient force attracts toner around the developing roller toward the developing roller, allowing the developing roller to transport a sufficient amount of toner even when the drive torque between the toner supply roller and the developing roller is reduced.

[0005] In addition, if the insulating portion is charged by injection charging, it is less susceptible to factors other than the developing roller, such as the state of the toner, compared to frictional charging, making it possible to ensure a stable toner transport force. Patent document 1 discloses a developing roller that can suppress density unevenness caused by uneven toner transport force, even when an image is output in a state where the torque generated by the developing roller and toner supply roller is reduced after the roller has been left in a high-temperature, high-humidity environment. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-020958 Summary of the Invention [Problem to be solved by the invention]

[0007] However, according to the inventors' investigations, the developing roller of Patent Document 1 may experience a decrease in toner transport power if used for a long period of time without being replaced in a high-temperature, high-humidity area with the driving torque reduced. When the developing roller is used without replacement, it will be used for several times longer than when it is replaced as a unit with the process cartridge. When used for such a long period in a high-temperature, high-humidity environment, the entire developing roller absorbs moisture, causing the insulating portion to have low resistance. In this state, when an attempt is made to charge the insulating portion, particularly by injection charging, the insulating portion is not sufficiently charged, which can result in poor toner transport (reduced image density and white areas in the image).

[0008] The present disclosure provides a developing roller that has a high process speed and exhibits sufficient toner transport force and can suppress toner transport defects even when used over a long period of time under various environments with reduced drive torque. Another aspect of the present disclosure provides a process cartridge including the developing roller. Still another aspect of the present disclosure provides an electrophotographic image forming apparatus including the process cartridge. [Means for solving the problem]

[0009] The present disclosure provides: a substrate having an electrically conductive outer surface; a conductive layer on the outer surface of the substrate, the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region; the first region and the second region are disposed adjacent to each other; the first region is disposed on an outer surface of the conductive layer; A metal film was provided directly on the outer surface of the developing roller, and a DC voltage of 50 V was applied between the outer surface of the substrate and the metal film in an environment of a temperature of 23°C and a relative humidity of 50%, while an AC voltage of 50 V amplitude and a frequency of 1.0 × 10 -1 ~1.0×10 5 When applied while changing between Hz, the frequency is 1.0 × 10 0 ~1.0×10 1 Impedance at Hz is 1.0×10 6 is greater than or equal to Ω, In an environment of 23°C temperature and 50% relative humidity, a corona discharger having a grid portion with a width of 3.0 mm was placed so that the distance between the grid portion and the outer surface of the developing roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the developing roller, a voltage of 8 kV was applied to the grid portion, and the corona discharger was moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec to charge the outer surface of the developing roller, and the potential of the outer surface was measured t seconds after the grid portion had passed. The potential at t=0.06 [seconds] is V INI [V], The change in potential in the range of 30.00≦t≦100.00 was fitted to the following equation (X′) by the least squares method, and V 0,1 When [V] and τ1 [seconds] are calculated, when t = 0.06 [seconds] is substituted into the formula (X'), the value of the potential V1(t) is V1 [V], INI -V1 is less than 20.0V. V1(t)=V 0,1 exp(-t / τ1) (X')

[0010] The present disclosure also relates to a process cartridge configured to be detachably mountable to the main body of an electrophotographic image forming apparatus, the process cartridge including a developing unit, the developing unit having the developing roller of the present disclosure. Furthermore, the present disclosure relates to an electrophotographic image forming apparatus having a developing means, the developing means having the developing roller of the present disclosure. [Effects of the Invention]

[0011] According to the present disclosure, the process speed is high, and further, the driving torque can be reduced for a long period of time. It is therefore possible to provide a developing roller, a process cartridge, and an electrophotographic image forming apparatus that are capable of suppressing toner transport defects even when used under various environments over a long period of time. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1A is a schematic cross-sectional view showing an example of a developing roller, and FIG. 1B is a schematic view of the outer surface of an example of the developing roller. [Figure 2] FIG. 10 is a schematic cross-sectional view showing another example of the developing roller. [Figure 3] FIG. 2 is a schematic diagram of a process cartridge. [Figure 4] FIG. 1 is a schematic diagram of an electrophotographic image forming apparatus. [Figure 5] FIG. 10 is a schematic diagram showing a state in which a measurement electrode is formed on a developing roller. [Figure 6] FIG. 2 is a cross-sectional view of a developing roller and a measurement electrode. [Figure 7] FIG. 1 is a schematic diagram of an impedance measurement system. [Figure 8] FIG. 1 is a schematic diagram showing an example of an apparatus for measuring the surface potential of a developing roller. [Figure 9] FIG. 10 is a schematic diagram of a circuit for measuring leakage current flowing from the toner to the developing roller. [Figure 10] FIG. 1 is a schematic diagram of an electrophotographic image forming apparatus for image evaluation. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. 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.

[0014] The inventors have inferred the reason why, when the developing roller according to Patent Document 1 is used for a long period of time in a high-temperature, high-humidity environment, the insulating part is not sufficiently charged, resulting in insufficient toner transport force and reduced image density, as follows. When a process cartridge equipped with a developing roller is left in a high-temperature, high-humidity environment without being operated, a difference in humidity occurs between the outside and inside of the process cartridge, which are separated by the developing roller. This causes unevenness in the amount of moisture absorbed by the outer surface of the developing roller located outside the process cartridge and the outer surface of the developing roller located inside, which in turn causes unevenness in the charge retention and electrical resistance of the insulating part. As a result, unevenness occurs in the gradient force, i.e., the toner transport force, leading to uneven image density.

[0015] According to the developing roller disclosed in Patent Document 1, by incorporating a low-hygroscopic resin near the surface of the conductive elastic layer, moisture diffusion into the conductive elastic layer is reduced, reducing the amount of moisture adhering to the insulating portion on the outer surface of the conductive elastic layer, thereby suppressing density unevenness. However, when the developing roller is used for a long period of time in a high-temperature, high-humidity environment without being replaced, moisture gradually diffuses into the interior of the process cartridge, causing the humidity inside the process cartridge to rise to the same level as the humidity outside. Furthermore, moisture diffuses throughout the entire developing roller, eventually absorbing moisture until the entire developing roller is saturated. Even if a low-hygroscopic resin is incorporated near the surface, if the entire developing roller absorbs moisture until it is saturated, the electrical resistance of the insulating portion on the entire outer surface of the developing roller, both inside and outside the process cartridge, decreases. This results in insufficient charging of the insulating portion, resulting in insufficient toner transport force and poor toner transport (reduced image density and white areas in the image).

[0016] The inventors have found that the reason why the insulating portion that has absorbed moisture is difficult to be charged by injection charging is that while the injection of charge into the insulating portion occurs due to the potential difference between the developing roller and other contact members, In other words, if the leakage of charge from the insulating portion to the conductive portion can be suppressed, the insulating portion can be sufficiently charged even if it absorbs moisture.

[0017] Specifically, we attempted to suppress charge leakage from the insulating portion by increasing the resistance of the conductive portion. For example, we evaluated image density after leaving a developing roller with a highly resistive conductive portion formed using polyurethane and an insulating portion formed thereon for a long period of time in a high-temperature, high-humidity environment. We found that this suppressed toner transport defects. However, we found that a new problem occurred when this developing roller was used in a low-temperature, low-humidity environment: toner transport defects. This is thought to be because the high resistance of the conductive portion prevented the charge injected into the conductive portion from being quickly removed by the potential difference between the developing roller and other contacting members. When the charge on the conductive portion could no longer be removed, not only the insulating portion but also the conductive portion became charged, reducing the potential difference between the conductive portion and the insulating portion, preventing sufficient gradient force from being exerted, resulting in toner transport defects.

[0018] Therefore, the inventors have investigated how to simultaneously suppress charge leakage from the insulating portion to the conductive portion and remove charge from the conductive portion by adjusting the amount and type of conductive filler contained in the polyurethane that forms the conductive portion. However, they found that simply adjusting the amount and type of conductive filler results in a trade-off between the two, making it difficult to simultaneously suppress toner transport defects when used for a long period of time in a high-temperature, high-humidity environment and in a low-temperature, low-humidity environment. That is, the inventors recognized that in order to achieve a high level of resolution between the conflicting goals of suppressing charge leakage from the insulating part to the conductive part in a high-temperature, high-humidity environment and removing charge from the conductive part in a low-temperature, low-humidity environment, it was necessary to develop a new conductive part. Based on this recognition, the inventors conducted further research.

[0019] As a result, we have come to realize that satisfying the following two requirements for a developing roller having a substrate with a conductive outer surface and a conductive layer on the outer surface of the substrate, wherein the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region, the first region and the second region being arranged adjacent to each other, and the first region being arranged on the outer surface of the conductive layer, is effective in solving the two problems described above.

[0020] Requirement (1) A metal film was provided directly on the outer surface of the developing roller, and a DC voltage of 50 V was applied between the outer surface of the substrate and the metal film in an environment of a temperature of 23°C and a relative humidity of 50%, while an AC voltage of 50 V amplitude and a frequency of 1.0 × 10 -1 ~1.0×10 5 When applied while changing between Hz, the frequency is 1.0 × 10 0 ~1.0×10 1 Impedance at Hz is 1.0×10 6 It is greater than or equal to Ω.

[0021] Requirement (2) In an environment of 23°C temperature and 50% relative humidity, a corona discharger having a grid portion with a width of 3.0 mm was placed so that the distance between the grid portion and the outer surface of the developing roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the developing roller, a voltage of 8 kV was applied to the grid portion, and the corona discharger was moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec to charge the outer surface of the developing roller, and the potential of the outer surface was measured t seconds after the grid portion had passed. The potential at t=0.06 [seconds] is V INI [V], The change in potential in the range of 30.00≦t≦100.00 was fitted to the following equation (X′) by the least squares method, and V 0,1 When [V] and τ1 [seconds] are calculated, the formula (X When t = 0.06 [seconds] is substituted into ('), the value of the potential V1(t) is V1 [V], INI-V1 is less than 20.0V. V1(t)=V 0,1 exp(-t / τ1) (X')

[0022] The above requirements (1) and (2) are explained in detail below. <Technical significance of requirement (1)> Requirement (1) specifies the value of the impedance of the developing roller. This impedance is a physical property value that indicates the charge leakage from the first region, i.e., the insulating portion, that constitutes the outer surface of the developing roller to the second region, i.e., the conductive portion. The inventors measured the current value (leakage current value) that flows through the developing roller when a blade bias is applied to the developing blade according to the circuit diagram shown in Figure 9. As a result, it was found that this current value exhibits a higher correlation with the impedance value of the developing roller than the electrical resistance value of the developing roller. Furthermore, it was found that when the outer surface of the developing roller is composed of an insulating portion (first region) and a conductive portion (second region), the above impedance value exhibits the characteristics of the conductive portion, which has higher conductivity. In other words, this shows that when it comes to charge leakage, it is necessary to consider not only the resistance component of the developing roller (conductive part), but also the influence of the capacitance component.This is thought to be because, when the electrical characteristics of the developing roller are represented pseudo-analogously as an RC parallel circuit, the transient state until a sufficient amount of charge is stored in the capacitance component and the steady state dominated by the resistance component has a large influence on charge leakage.

[0023] The voltage application conditions for measuring impedance were a DC voltage of 50 V superimposed on an AC voltage of 50 V. In other words, a sine wave with minimum and maximum applied voltages of 0 V and 100 V (Vpp100 V) was applied. This value of Vpp100 V is the assumed maximum value of the shared voltage applied to the developing roller when a voltage is applied so that a voltage difference of 300 V is applied between the developing roller and developing blade in an electrophotographic image forming apparatus.

[0024] Impedance exhibits bias dependency, meaning that impedance decreases as the bias increases, but it is known that the degree of this decrease varies depending on the developing roller. In conventional impedance measurements of developing rollers, an AC voltage of 1 V is generally used as the voltage application condition, but this AC voltage of 1 V is clearly smaller than the voltage (generally several hundred volts) applied between the developing roller and developing blade in an actual electrophotographic image forming apparatus. Therefore, it is often not possible to simulate the behavior of the developing roller in an electrophotographic image forming apparatus, and it is often inappropriate as an impedance measurement condition. Therefore, in this disclosure, voltage application conditions that mimic the high blade bias applied to an actual electrophotographic image forming apparatus are adopted. Also, a sine wave with a minimum applied voltage of 0 V mimics a square wave that is generally used in applying a blade bias to an actual electrophotographic image forming apparatus.

[0025] In this disclosure, the frequency 1.0×10 0 ~1.0×10 1 The impedance is specified at a frequency of 1.0 x 10 0 ~1.0×10 1 The low frequency range of 1.0 x 10 Hz is the region where the transient state is completed and the steady state dominated by the resistance component is reached. In other words, the influence of both the capacitance component and the resistance component is reflected, and this region is suitable for understanding the charge leakage from the insulating part to the conductive part. 0 ~1.0×10 1 Impedance at Hz is 1.0×10 6 When the resistance is Ω or more, the charge leakage from the conductive layer is low, and charge leakage from the insulating portion to the conductive layer under a high blade bias is suppressed, thereby making it possible to suppress poor toner transport.

[0026] The frequency is 1.0 x 10 0 ~1.0×10 1 The impedance at Hz is preferably 1.4 x 10 6 The higher the impedance value, the better. There is no particular upper limit, but for example, 5.0 × 10 7Examples include Ω and below. Also, the frequency is 1.0×10 0 ~1.0×10 1 The impedance at Hz is preferably 1.4 x 10 6 Ω or more, more preferably 2.0×10 6 Ω or more, particularly preferably 3.0 × 10 6 Ω or more, more preferably 5.0×10 6 The preferred range of the impedance is 1.0×10 6 Ω or more 5.0×10 7 Ω or less, preferably 1.4×10 6 Ω or more 5.0×10 7 Ω or less, more preferably 2.0×10 6 Ω or more 5.0×10 7 Ω or less, particularly preferably 3.0 × 10 6 Ω or more 5.0×10 7 Ω or less, more preferably 5.0 × 10 6 Ω or more 5.0×10 7 It is less than Ω.

[0027] <Technical significance of requirement (2)> Requirement (2) specifies the surface potential of the outer surface of the developing roller. This surface potential corresponds to the surface potential of the conductive portion, which is the second region. The surface potential of the conductive portion indicates the ease with which the charge in the conductive portion remains. The higher this surface potential, the more difficult it is to remove the charge injected into the conductive portion, which reduces the potential difference between the conductive portion and the insulating portion, making it more likely that insufficient toner transport will occur.

[0028] In this disclosure, when a voltage of 8 kV is applied to the grid portion and the corona discharger is moved relative to the developing roller in the axial direction at a speed of 400 mm / s, the decay behavior of the potential on the outer surface of the developing roller after the grid portion of the corona discharger has passed, i.e., the relaxation curve, is confirmed. The relaxation curve of the surface potential of a developing roller whose outer surface is composed of conductive and insulating parts is a curve that combines a relaxation curve corresponding to the conductive parts, which decay quickly, and a relaxation curve corresponding to the insulating parts, which decay slowly. The relaxation curve is generally expressed by the following formula (X): V=V0exp(-t / τ) (X) In formula (X), V0 represents the surface potential [V] at t=0, t represents the elapsed time [seconds], and τ represents the time constant [seconds]. In addition, the surface potential of the developing roller in the range of 30.00≦t≦100.00 is considered to be less affected by the relaxation curve corresponding to the conductive part with fast decay. Therefore, the change in the surface potential of the developing roller in the range of 30.00≦t≦100.00 is fitted to the following formula (X'), and V 0,1 When the values ​​of [V] and τ1 [seconds] are found, V1(t) is a relaxation curve corresponding to the region where charge decay is slow on the outer surface of the developing roller, that is, the insulating portion. V1(t)=V 0,1 exp(-t / τ1) (X') In formula (X'), V 0,1 indicates the surface potential [V] of the insulating part at t=0, and τ1 indicates the time constant [seconds] of the insulating part. Therefore, when t=0.06 is substituted into the potential V1(t), the value V1 represents the surface potential of the insulating part 0.06 seconds after the grid part of the corona discharger has passed.

[0029] On the other hand, V INI is the measured value of the surface potential of the outer surface of the developing roller, including the conductive and insulating parts, 0.06 seconds after the grid part of the corona discharger has passed. In other words, the surface potential of the conductive part 0.06 seconds after the grid part of the corona discharger has passed is V INI -V1. If the surface potential of the conductive portion is less than 20.0 V, the charge injected into the conductive portion when passing through a contact member such as a developing blade or a photosensitive drum can be quickly removed. Therefore, even if the conductive portion repeatedly passes through a developing blade or a photosensitive drum due to the rotation of the developing roller, charge does not accumulate on the conductive portion and the potential difference between the conductive portion and the insulating portion does not decrease, thereby suppressing poor toner transport.

[0030] The time 0.06 seconds after the grid part of the corona discharger passes simulates the time it takes for the conductive part of the developing roller to reach the contact position with other contact members such as the photosensitive drum after the development blade has passed in a model with a high process speed. This prevents charge from accumulating on the conductive part even when frictional charging or injection charging occurs not only with the development blade but also with the photosensitive drum in an electrophotographic image forming apparatus with a high process speed, thereby suppressing toner transport defects. This can be done. The surface potential of the conductive part (V INI −V1) is preferably 15.0 V or less, and more preferably 10.0 V or less. The lower the surface potential of the conductive portion, the better, and there is no particular lower limit. The surface potential of the conductive portion is, for example, preferably 0.0V or more and less than 20.0V, particularly preferably 0.0V or more and 15.0V or less, and further preferably 0.0V or more and 10.0V or less.

[0031] By satisfying the above requirements (1) and (2), the developing roller can achieve a high level of both the conflicting objectives of suppressing charge leakage from the insulating portion to the conductive portion in a high-temperature, high-humidity environment and removing charge from the conductive portion in a low-temperature, low-humidity environment. As a result, toner transport problems can be suppressed even when the developing roller is used for a long period of time in various environments with reduced drive torque. There are no particular limitations on the means for satisfying the above requirements (1) and (2). Specific examples include using the following conductive layer materials, conductive filler materials, and additives, as described below.

[0032] The present disclosure will be described in detail below. <Developing roller> The developing roller has a substrate having a conductive outer surface and a conductive layer on the outer surface of the substrate. The outer surface of the developing roller is further composed of at least a first region (insulating portion) and a second region (conductive portion) having a higher conductivity than the first region, the first region and the second region being disposed adjacent to each other, and the first region being disposed on the outer surface of the conductive layer.

[0033] FIG. 1A shows an example of a schematic cross-sectional view of a developing roller, and FIG. 1B shows an example of a schematic outer surface view. The developing roller 10 shown in FIG. 1A has a conductive layer 12 laminated on the outer surface of a cylindrical or hollow cylindrical substrate 11. The outer surface of the developing roller is further composed of a first region 1 and a second region 2 having higher conductivity than the first region, and the second region 2 is composed of the outer surface of the conductive layer 12. The first region 1 is composed of the outer surface of an insulator arranged on the outer surface of the conductive layer 12 so that the outer surface of the conductive layer is exposed. The first region may be formed by arranging an insulator on the outer surface of the conductive layer 12, or by exposing an insulator contained in the conductive layer 12.

[0034] The layer configuration of the developing roller is not limited to the configuration shown in Fig. 1A. Another configuration of the developing roller is a developing roller having an elastic layer 13 between a substrate 11 and a conductive layer 12 provided on the outer peripheral surface thereof, as shown in Fig. 2.

[0035] [Base] The substrate is electrically conductive and functions as a support member for the developing roller and, in some cases, as an electrode. Specific examples of the substrate include a solid columnar shape and a hollow cylindrical shape.

[0036] The material for the substrate can be appropriately selected from those known in the field of electroconductive members for electrophotography and materials usable for such developing rollers, and examples thereof include metals or alloys such as aluminum and stainless steel, carbon steel alloys, conductive synthetic resins, iron, and copper alloys.

[0037] Furthermore, the material constituting the substrate may be subjected to an oxidation treatment or a plating treatment with chromium, nickel, etc. Either electroplating or electroless plating can be used as the type of plating. Electroless plating is preferred from the viewpoint of dimensional stability. Examples of the types of electroless plating used here include nickel plating, copper plating, gold plating, and various other alloy plating. The plating thickness is preferably 0.05 μm or more, and is suitable for work efficiency and rust prevention ability. Considering the balance, the plating thickness is preferably 0.1 to 30 μm.

[0038] A primer may be applied to the surface of the substrate to improve adhesion between the substrate and the conductive layer or elastic layer. A known primer can be selected and used depending on the rubber material for forming the conductive layer and the material of the support. Examples of primer materials include thermosetting resins and thermoplastic resins, and specific examples of materials that can be used include phenolic resins, polyurethanes, acrylic resins, polyester resins, polyether resins, and epoxy resins.

[0039] [Conductive layer and second region (conductive portion)] The developer roller has a conductive layer on the outer surface of a substrate, and the outer surface of the developer roller is configured with at least a first region and a second region having a higher conductivity than the first region. That is, the conductive layer is provided on the outer surface of the substrate, and the second region (conductive portion) that constitutes the outer surface of the developing roller is constituted by the outer surface of the conductive layer. The conductive layer may contain a binder resin.

[0040] (binder resin) As the binder resin for the conductive layer, polyurethane is preferably used, and polyurethane having a polycarbonate structure is more preferably used, in order to suppress charge leakage from the insulating portion to the conductive layer. That is, the conductive layer preferably contains polyurethane, and polyurethane having a polycarbonate structure is more preferably used. The polycarbonate structure provides high surface strength and good electrical resistance, making it easier to maintain the properties of the developing roller throughout its durability.

[0041] Furthermore, in order to suppress charge leakage from the insulating portion to the conductive layer while maintaining sufficient flexibility of the conductive layer to reduce the load on the toner and sufficient abrasion resistance of the conductive layer, it is more preferable to use a polyurethane having the structure described below as the binder resin of the conductive layer.

[0042] The conductive layer contains polyurethane, and the polyurethane preferably satisfies at least two of the following (A), (B), and (C). It may also satisfy all of the following (A), (B), and (C). (A) The polyurethane has a structure represented by the following structural formula (1) in its molecule; (B) The polyurethane has, in its molecule, either one or both of a structure represented by the following structural formula (2) and a structure represented by the following structural formula (3): (C) The polyurethane has a structure represented by the following structural formula (4) in the molecule.

[0043] That is, it is preferable that the polyurethane satisfies at least one of the following requirements. -Having at least a structure represented by structural formula (1) and a structure represented by structural formula (2) ·Having at least a structure represented by structural formula (1) and a structure represented by structural formula (3) ·Having at least a structure represented by structural formula (1) and a structure represented by structural formula (4) ·Having at least a structure represented by structural formula (2) and a structure represented by structural formula (4) ·Having at least a structure represented by structural formula (3) and a structure represented by structural formula (4) [ka]

[0044] In structural formula (1), R11, R12, and R13 represent divalent hydrocarbon groups having 3 to 9 carbon atoms. However, R11 and R12 are different from each other, and R13 is the same as at least one selected from the group consisting of R11 and R12. m and n represent the average number of moles added, and each independently represents a number of 1.0 or more (preferably 1.0 to 20.0, more preferably 2.0 to 12.0). In structural formula (2), o and p are the average number of moles added, and each independently represents a number of 1.0 or more (preferably 1.0 to 15.0, more preferably 4.0 to 10.0). In structural formula (3), R31 and R32 each independently represent a divalent hydrocarbon group having 3 to 8 carbon atoms. q and r each independently represent the average number of moles added and are 1.0 or greater (preferably 1.0 to 20.0, more preferably 2.0 to 14.0). In structural formula (4), R41 represents a divalent hydrocarbon group having 6 to 9 carbon atoms (preferably 5 to 8). s represents the average number of moles added and is a number of 1.0 or more (preferably 1.0 to 22.0, more preferably 4.0 to 18.0).

[0045] The structure shown in structural formula (1) is a copolymer polycarbonate polyol in which crystallinity is suppressed by linking two carbonate groups with two different hydrocarbon groups, and the polyol is reacted with isocyanate. Because the crystallinity is suppressed, the cohesive energy in the soft segments is small, which gives the conductive layer flexibility and high volume resistivity. By using the structure of structural formula (1) in combination with the structures (2) to (4) described above in the conductive layer, the adhesiveness of the conductive layer can be reduced, which prevents toner, powder, etc. from adhering to the surface of the conductive layer, prevents an increase in the electrical resistance of the surface of the conductive layer due to contamination, and makes it easier to quickly remove the charge injected into the conductive portion.

[0046] In structural formula (1), R11 and R12 are each independently a divalent hydrocarbon group having 3 to 9 carbon atoms. R11 and R12 are different from each other, and R13 is the same as at least one selected from the group consisting of R11 and R12. If the number of carbon atoms in R11 and R12 is 3 or more, the amount of carbonate groups, which are polar functional groups with strong cohesive energy, in the polyurethane is not too large, making the conductive layer flexible and highly conductive. This makes it easier to maintain the resistance value. Furthermore, when the carbon numbers of R11 and R12 are 9 or less, the amount of carbonate groups in the polyurethane is not too small, and the strength of the polymer can be maintained. Furthermore, when R11 and R12 have different structures, the crystallinity of the polymer can be suppressed and flexibility can be imparted to the conductive layer. m and n each independently represent a number of 1.0 or more. The hydrocarbon groups represented by R11, R12, and R13 may have a branched structure or a cyclic structure.

[0047] The structures shown in structural formulas (2) and (3) are obtained by reacting a copolymer polyol, which is a copolymer of a polycarbonate structure and a polyester structure, with an isocyanate. By copolymerizing a polycarbonate structure and a polyester structure, the crystallinity of the polymer is suppressed, and by introducing an ester group, which has a stronger cohesive energy than a carbonate group, the soft segment is appropriately reinforced, thereby imparting abrasion resistance to the conductive layer.

[0048] When a conductive layer is formed using a polymer in which the structure represented by structural formula (2) and / or structural formula (3) is combined with the structure represented by formula (1) or (4), the conductive layer can be given sufficient volume resistivity while having a polar ester group, making it easier to suppress charge leakage from the insulating part to the conductive layer.

[0049] In structural formula (2), o and p each independently represent a number of 1.0 or more. In structural formula (3), R31 and R32 each independently represent a divalent hydrocarbon group having 3 to 8 carbon atoms, and q and r each independently represent a number greater than or equal to 1.0. When R31 and R32 each have 3 or more carbon atoms, the amount of carbonate and ester groups in the polyurethane, which are polar functional groups with strong cohesive energy, is not too large, allowing the conductive layer to maintain flexibility. When R31 and R32 each have 8 or less carbon atoms, the amount of carbonate and ester groups in the polyurethane is not too small, allowing the conductive layer to be imparted with abrasion resistance.

[0050] The structure shown in structural formula (4) is a structure obtained by reacting a highly crystalline polycarbonate polyol, in which two carbonate groups are bonded by a single hydrocarbon group, with an isocyanate. This structure is highly crystalline and easily arranged in the soft segment, which can impart abrasion resistance and high volume resistivity to the conductive layer. By forming a conductive layer using a polymer in which the structure represented by structural formula (4) is combined with the structures of formulas (1) to (3) above, the hardness of the conductive layer does not become too high and can be easily controlled appropriately.

[0051] In structural formula (4), R41 represents a divalent hydrocarbon group having 6 to 9 carbon atoms, and s represents a number of 1.0 or more. When R41 has 6 or more carbon atoms, crystallinity is easily exhibited, and the conductive layer can be imparted with abrasion resistance and high volume resistivity. When R41 has 9 or less carbon atoms, excessive crystallinity can be suppressed, and therefore, by further containing at least one of the structures represented by structural formulas (1), (2), and (3) in the polymer, an increase in the hardness of the conductive layer can be suppressed.

[0052] The conductive layer preferably contains a polymer having a urethane bond, i.e., polyurethane, as a binder resin, and the polymer preferably satisfies at least two selected from the group consisting of (A), (B), and (C), thereby making the conductive layer flexible and less susceptible to wear.

[0053] The structure of the polymer contained in the conductive layer of the developing roller can be confirmed by, for example, pyrolysis GC / MS, FT-IR, or NMR analysis.

[0054] Polyurethane can be produced using (A) a polyol compound and (B) a polyisocyanate compound. Polyurethane is usually synthesized by the following methods (1) and (2). (1) One-shot method in which the polyol component and the polyisocyanate component are mixed and reacted (2) A method of reacting an isocyanate-terminated prepolymer obtained by reacting a part of a polyol with an isocyanate with a chain extender such as a low molecular weight diol or low molecular weight triol.

[0055] In the present disclosure, polyurethane may be synthesized by any of the above methods, but a method of subjecting a hydroxyl-terminated prepolymer obtained by reacting a raw material polyol with an isocyanate to a thermal curing reaction with an isocyanate-terminated prepolymer obtained by reacting a raw material polyol with an isocyanate is more preferred. The polyurethane is preferably a reaction product of a mixture containing a hydroxyl-terminated prepolymer and an isocyanate-terminated prepolymer. The mixture can be used as a coating liquid for forming a conductive layer. The polyurethane is more preferably a reaction product of a mixture containing a hydroxyl-terminated prepolymer, an isocyanate-terminated prepolymer, a conductive filler, and an additive.

[0056] When the polyurethane contains a large number of hydroxyl groups, isocyanate groups, or urea bonds, allophanate bonds, isocyanurate bonds, etc., the amount of polar functional groups present in the polyurethane increases, which may increase the water absorption of the polymer and reduce the volume resistivity of the conductive layer. On the other hand, by thermally curing the hydroxyl-terminated prepolymer and the isocyanate-terminated prepolymer, a polyurethane with less unreacted polyol and polar functional groups can be obtained without using an excessive amount of isocyanate. This is therefore preferable from the viewpoint of further suppressing charge leakage from the insulating portion to the conductive layer.

[0057] (A) Polyol compound The polyol compound may be any polyol known for or usable in the synthesis of urethane resins. Examples of polyol compounds include polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols such as polybutadiene polyols and polyisoprene polyols, so-called polymer polyols obtained by polymerizing ethylenically unsaturated monomers in polyols, and polyester-polycarbonate copolymer polyols. Among these, the polyol compound is preferably at least one selected from the group consisting of polycarbonate polyols and polyester polycarbonate copolymer polyols.

[0058] Examples of polycarbonate polyols include polynonamethylene carbonate diol, poly(2-methyl-octamethylene) carbonate diol, polyhexamethylene carbonate diol, polypentamethylene carbonate diol, poly(3-methylpentamethylene) carbonate diol, polytetramethylene carbonate diol, polytrimethylene carbonate diol, poly(1,4-cyclohexanedimethylene carbonate) diol, poly(2-ethyl-2-butyl-trimethylene) carbonate diol, and random / block copolymers thereof.

[0059] Examples of polyester polycarbonate copolymer polyols include the following: copolymers obtained by polycondensing the above-mentioned polycarbonate polyols with lactones such as ε-caprolactone, and copolymers of polyesters obtained by polycondensing diols such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentanediol, and neopentyl glycol with dicarboxylic acids such as adipic acid and sebacic acid.

[0060] (B) Polyisocyanate compound The polyisocyanate may be selected from commonly used known ones, such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, hydrogenated MDI, polymeric MDI, xylylene diisocyanate (XDI), and hexamethylene diisocyanate. (HDI), isophorone diisocyanate (IPDI), etc. Among these, aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, and polymeric MDI are more preferably used. Other polyisocyanates can also be used as long as they do not affect the impedance value and surface potential.

[0061] The ratio of the number of isocyanate groups to the number of hydroxyl groups (hereinafter also referred to as "NCO / OH ratio") is preferably 1.0 to 2.0. If this NCO / OH ratio is 1.0 to 2.0, the crosslinking reaction proceeds, and the bleeding of unreacted components and low-molecular-weight polyurethane, known as "bleeding," is suppressed. The NCO / OH ratio is more preferably 1.0 to 1.6. If this NCO / OH ratio is 1.0 to 1.6, bleeding is suppressed and the hardness of the polymer can be reduced.

[0062] The content of polyurethane in the conductive layer is not particularly limited, but is preferably 50 to 95% by mass, more preferably 60 to 80% by mass, and even more preferably 65 to 75% by mass.

[0063] (Conductive filler) The conductive layer preferably contains a conductive filler to obtain conductivity. It is more preferable to use an electronic conductive agent as the conductive filler in the conductive layer. The electronic conductive agent is preferably a conductive particle that exhibits electronic conductivity and has a surface functional group that can interact with a functional group present in the additive described below. Examples of electronic conductive agents that exhibit these properties include at least one selected from the group consisting of carbon black such as furnace black, thermal black, acetylene black, and ketjen black; metal oxide-based conductive particles such as titanium oxide whose surfaces have been treated with acidic functional groups; and metal-based conductive particles such as aluminum and iron whose surfaces have been treated with acidic functional groups. Among these, at least one selected from the group consisting of carbon blacks with highly stable surface functional groups is preferably used. The conductive filler preferably contains carbon black. Furthermore, in order to obtain the desired impedance value and surface potential, carbon black having a number-average diameter of primary particles of 30 nm or less, which allows for higher dispersion in the conductive layer, a DBP absorption of 90 ml / 100 g or less, and a pH of 4.0 or less is particularly preferably used.

[0064] When the number-average diameter of the primary particles of carbon black is 30 nm or less, the aggregates (primary agglomerates), which are the smallest dispersible units of carbon black, become small, and the structure (the size of the particle connections) also becomes small, making it difficult to form conductive paths. As a result, a sufficiently high impedance is easily obtained. The primary particle diameter of carbon black can be calculated using a transmission electron microscope (TEM). The lower the number-average diameter, the better, and there is no particular lower limit. For example, the number-average diameter of the primary particles of carbon black is preferably 5 to 30 nm, and more preferably 20 to 28 nm.

[0065] When the DBP absorption of carbon black is 90 ml / 100 g or less, the carbon black structure becomes small, making it difficult to form conductive paths, and therefore, it is easy to obtain a sufficiently high impedance. The lower the DBP absorption, the better, and there is no particular lower limit. For example, the DBP absorption of carbon black is preferably 30 to 90 ml / 100 g, and more preferably 40 to 60 ml / 100 g.

[0066] When the pH of carbon black is 4.0 or less, the repulsion of the surface functional groups of the carbon black provides dispersion stability, making it difficult for the carbon black to aggregate, and therefore, it is easy to obtain a sufficiently high impedance. The lower the pH of carbon black, the more preferable it is, and there is no particular lower limit. For example, the pH of carbon black is 2.0 to 4.0, 2.2 to 4.0, or 2.3 to 4.0. 2.8 is more preferable.

[0067] However, even if the number-average diameter of the primary particles of carbon black, DBP absorption, and pH are within the above ranges, when polycarbonate urethane is used as the binder resin, the carbon black may not be sufficiently dispersed, making it impossible to obtain the desired impedance.The reason why carbon black, which has the desired raw material properties, cannot be dispersed when polycarbonate urethane is used as the binder resin is not clearly understood, but it is speculated as follows.

[0068] The hydroxyl groups, which are surface functional groups of carbon black, tend to interact with the terminal hydroxyl groups of polycarbonate diol. On the other hand, the structure of the carbonate bond and hydrocarbon group bonded between the two hydroxyl groups of polycarbonate diol is hydrophobic due to the presence of the hydrocarbon group, making it less likely to interact with carbon black. Since the structure is more stable when hydrophobic and hydrophilic materials are close together, hydrophilic carbon black will be found in the vicinity of hydrophilic carbon black. As a result, carbon black tends to aggregate and become difficult to disperse.

[0069] In order to sufficiently disperse carbon black having the number average diameter of primary particles, DBP absorption amount, and pH within the above-mentioned ranges when using polycarbonate urethane as a binder resin, it is more preferable to add the additives described below.

[0070] The carbon black content is preferably added so as to achieve a desired volume resistivity, and is preferably 30 parts by mass or less, more preferably 10 to 30 parts by mass, and even more preferably 15 to 25 parts by mass, per 100 parts by mass of polyurethane forming the conductive layer. When the amount is 30 parts by mass or less, the distance between the carbon black particles in the coating liquid is maintained at an appropriate level, reducing the probability of collisions due to Brownian motion of the carbon black and making the carbon black less likely to aggregate. This makes the carbon black more easily dispersible and improves dispersion stability. As a result, the carbon black is well dispersed in the conductive layer formed from the coating liquid.

[0071] To achieve the above-mentioned specific impedance and surface potential, it is preferable to control the dispersion of the carbon black. As for the particle size of the dispersed carbon black, the arithmetic mean value Rc of the equivalent circle diameter of the carbon black in the conductive layer is preferably 60.0 nm or less. Furthermore, when the standard deviation of the equivalent circle diameter is σc [nm], it is more preferable that σc / Rc is 0.000 to 0.650. Furthermore, as for the distance between the carbon black particles, it is more preferable that the arithmetic mean value d of the distance between the wall surfaces of the carbon black particles in the conductive layer is 80.0 to 150.0 nm, and σd / d is 0.000 to 0.600, where σd [nm] is the standard deviation of the distance between the wall surfaces.

[0072] The reason why high impedance and low surface potential are more easily achieved when the equivalent circle diameter and wall-to-wall distance are within the above-mentioned ranges is presumed to be as follows. When the dispersed particle size is large, there are areas where the distance between the walls is close, making it easier for conductive paths to form, resulting in lower impedance and surface potential. On the other hand, when the dispersed particle size is small, the distance between the walls becomes more uniform, making it harder for conductive paths to form and increasing resistance, resulting in higher impedance. Regarding surface potential, localized charge accumulation is less likely to occur, making it possible to lower the surface potential. It is possible to use a plurality of types of carbon black in combination as long as the impedance value and the surface potential are not affected.

[0073] The arithmetic mean value Rc of the equivalent circle diameter is more preferably 40.0 to 60.0 nm, It is more preferably 5.0 to 55.0 nm. σc / Rc is more preferably 0.500 to 0.650, and even more preferably 0.550 to 0.650. The arithmetic mean value Rc and standard deviation σc of the equivalent circle diameter can be changed, for example, by the dispersion state in a mill when preparing the coating liquid for forming the conductive layer. Weaker dispersion tends to increase Rc and σc, while stronger dispersion tends to decrease Rc and σc. Normally, Rc converges, so once a certain dispersion state is exceeded, σc can be reduced while Rc remains almost constant, and σc / Rc can be reduced.

[0074] The arithmetic mean value d of the distance between the wall surfaces is more preferably 90.0 to 120.0 nm, and even more preferably 95.0 to 115.0 nm. σd / d is more preferably 0.500 to 0.600, and even more preferably 0.540 to 0.590. The arithmetic mean value d and standard deviation σd of the wall-to-wall distance can be changed, for example, by the dispersion state in a mill or the like when preparing the conductive layer-forming coating liquid. Weaker dispersion tends to make d smaller and σd larger, while stronger dispersion tends to make d larger and σd smaller. Therefore, weaker dispersion tends to make σd / d larger, and stronger dispersion tends to make σd / d smaller.

[0075] (additives) One preferred embodiment is to use an additive to further improve the dispersibility of carbon black in a binder resin using polycarbonate urethane. Here, for example, at least one compound selected from the group consisting of a compound having a structure represented by the following structural formula (5), a compound having a structure represented by the following structural formula (6), and a compound having a structure represented by the following structural formula (7) can be suitably used as the additive. That is, the conductive layer preferably contains at least one compound selected from the group consisting of a compound represented by the following structural formula (5), a compound represented by the following structural formula (6), and a compound represented by the following structural formula (7). One method for incorporating the additive into the conductive layer is to incorporate a dispersant into the conductive layer-forming coating liquid. In a conductive layer formed using a conductive layer-forming coating liquid containing at least one compound selected from the group consisting of compounds having a structure represented by structural formula (5) and compounds having a structure represented by structural formula (6), the compound may be incorporated at the end of the polyurethane polymer chain. Even in such cases, the effect of improving the dispersibility of carbon black can be expected, but it is preferable that the compound be present in the conductive layer independently of the polyurethane.

[0076] Among the compounds having the structures represented by structural formulas (5) to (7), the compound having the structure represented by structural formula (5) is more preferably used because it has particularly excellent dispersibility of carbon black and affinity with polycarbonate urethane. [ka]

[0077] In structural formula (5), R51 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms (preferably 3 to 12). t and u represent the average number of moles added, and each independently represents a number of 1.0 or more (preferably 5.0 to 30.0, more preferably 10.0 to 25.0). In structural formula (6), R61 represents a monovalent hydrocarbon group having 1 to 8 carbon atoms (preferably 1 to 4). v and w represent the average number of moles added, and each independently represents a number of 1.0 or more (preferably 1.0 to 30.0, more preferably 5.0 to 30.0). In structural formula (7), R71 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms. x represents the average number of moles added and is a number of 1.0 or more (preferably 1.0 to 30.0, more preferably 4.0 to 15.0).

[0078] Structural formula (5) is polyoxyethylene polyoxypropylene alkyl ether, a polyether monool with a block-type addition polymerization structure of ethylene oxide and propylene oxide. The terminal hydroxyl groups of this polyether monool interact with the surface functional groups of the conductive filler carbon black through hydrogen bonding, acting as a dispersant for the carbon black. In addition, the structure is compatible with polycarbonate urethane, enhancing its effectiveness as a dispersant for carbon black.

[0079] Ethylene oxide is introduced into the structure to ensure uniform distribution of the additive in the polycarbonate urethane. This is thought to be because the ethylene group in ethylene oxide is compatible with the hydrophobic hydrocarbon group in the polycarbonate urethane. Propylene oxide is introduced into the structure to improve the dispersibility of the conductive filler dispersed in the conductive layer. This is thought to be because the side-chain methyl group of propylene oxide interacts with the conductive filler, improving the dispersibility of the conductive filler.

[0080] R51, a monovalent hydrocarbon group having 1 to 12 carbon atoms, is introduced into the structure to allow the additive to be distributed uniformly throughout the polycarbonate urethane. Being a monovalent hydrocarbon group improves compatibility with the hydrophobic hydrocarbon groups in the polycarbonate urethane, allowing the additive to be distributed uniformly throughout the polycarbonate urethane. Having 12 or fewer carbon atoms reduces steric hindrance with the polycarbonate urethane, making it easier for the additive to be distributed uniformly. Furthermore, since the compound of formula (5) has a mono-ol structure, it is less reactive than a diol and is less likely to be incorporated into the urethane reaction caused by the reaction of isocyanate with a polyol, which makes it less likely to lead to a decrease in the resistance of the polyurethane due to the introduction of an ether structure into the polycarbonate urethane.

[0081] The polyoxyethylene polyoxypropylene alkyl ether can be a commercially available product or can be obtained by synthesis. The synthesis of polyoxyethylene polyoxypropylene alkyl ether can be carried out by carrying out the following step (A) followed by step (B). Note that step (B) may also be carried out on a commercially available product whose structure has already been completed up to step (A).

[0082] Step (A): Reaction of alcohol with ethylene oxide Step (B): Reaction of the product obtained in step (A) with propylene oxide In step (A), the reaction can be carried out by adding ethylene oxide to an alcohol in the presence of a catalyst at 50 to 200°C, more preferably 100 to 160°C. Since ethylene oxide has a boiling point of 10.7°C and is in a gaseous state at this temperature, the reaction is preferably carried out in a pressurized environment in a sealed container. The pressure is preferably 0.1 MPa to 1.0 MPa. The reaction time is not particularly limited, but is preferably about 1 to 3 hours in order to reduce the amount of unreacted ethylene oxide.

[0083] The catalyst may be an acid catalyst or an alkali catalyst, but an alkali catalyst is preferred to facilitate purification after the reaction. Examples of alkali catalysts include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide, ammonium hydroxide, and tertiary amines. In view of the ease and efficiency of the reaction, sodium hydroxide and potassium hydroxide are particularly preferred. Examples of acid catalysts include Bronsted acids such as sulfuric acid and phosphoric acid, and Lewis acids such as stannic chloride and boron trifluoride.

[0084] The amount of catalyst used is preferably 0.1 to 5 mol % per 1 mol of alcohol in the case of sodium hydroxide or potassium hydroxide. Since ethylene oxide reacts with water to produce ethylene glycol, it is important to prevent water from entering the reaction system as much as possible, and a dehydration treatment may be carried out before the reaction in step (A) as necessary.

[0085] Step (B) can be carried out under the same conditions as step (A). Propylene oxide has a boiling point of 34.2°C and is in a gaseous state at reaction temperatures of 50 to 200°C, so the reaction is preferably carried out in a pressurized environment in a sealed container. The catalyst used in step (A) may be used as is, or a new catalyst may be added. When a new catalyst is added, the catalyst used in step (A) is preferred.

[0086] Structural formula (6) is a polyetheramine (monoamine) with a block-type addition polymerization structure of ethylene oxide and propylene oxide. The amino groups at the terminals of this polyetheramine interact with the surface functional groups of the conductive filler carbon black through hydrogen bonding, acting as a dispersant for the carbon black. Furthermore, to enhance its effectiveness as a dispersant, R61, a monovalent hydrocarbon group with 1 to 8 carbon atoms, is introduced, resulting in a structure that is easily compatible with the hydrophobic functional groups of polycarbonate urethane, resulting in a structure that is also highly compatible with polycarbonate urethane.

[0087] The polyether monoamine can be a commercially available product or can be obtained by synthesis. The synthesis of the polyether monoamine can be carried out by carrying out the following step (C) followed by step (D).

[0088] Step (C): Oxidation reaction of the compound of structural formula (5), which is a secondary alcohol Step (D): Reductive amination of the product obtained in step (C) Step (C) is a reaction to produce a ketone by oxidation of a secondary alcohol. The synthesis of a ketone by oxidation of a secondary alcohol is carried out using heavy metal salts such as chromic acid and manganese dioxide and their There are two types of oxidation reactions: oxidation reactions using derivatives and oxidation reactions using non-heavy metal salts using dimethyl sulfoxide (DMSO) or hypohalous acids such as hypochlorous acid.

[0089] Although either method can be used for synthesis, oxidation reactions using hypohalous acids such as dimethyl sulfoxide (DMSO) or hypochlorous acid are preferred due to the environmental impact of heavy metals. Furthermore, dimethyl sulfoxide (DMSO) can undergo explosive reactions at room temperature depending on the electrophilic activating reagent used, requiring temperatures as low as -60°C, making the method using hypohalous acids more preferable. Examples of hypohalous acids include hypochlorites such as sodium hypochlorite and calcium hypochlorite (bleaching powder). Ketones can be obtained by reacting these hypochlorites with secondary alcohols in acetic acid.

[0090] When using dimethyl sulfoxide (DMSO), an electrophilic activating reagent is required. The electrophilic activating reagent increases the electrophilicity of the sulfur in DMSO, allowing it to undergo nucleophilic attack by the alcohol's hydroxyl group. This nucleophilic attack generates a dimethylalkoxysulfonium salt, which decomposes to yield a ketone and dimethyl sulfide. Examples of electrophilic activating reagents include dicyclohexylcarbodiimide (DCC), acetic anhydride, phosphorus pentoxide, sulfur trisulfide-pyridine complex, trifluoroacetic anhydride, oxalyl chloride, and halogens.

[0091] Step (D) is a reductive amination reaction that converts a ketone to an amine. The reaction is divided into two steps. First, a carbonyl group reacts with an amine to generate an iminium cation. Next, a hydride reducing agent nucleophilically attacks the iminium cation to generate an amine. A borohydride reagent is preferably used as the reducing agent. Examples of borohydride reagents include sodium cyanoborohydride, sodium triacetoxyborohydride, and 2-picoline borane. Among these, sodium triacetoxyborohydride and 2-picoline borane are preferred due to their low toxicity. In the reductive amination reaction using a borohydride reagent, if the reagent has a bulky structure, steric hindrance makes it difficult to generate an iminium cation. Therefore, R61 in structural formula (6) is preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms.

[0092] Structural formula (7) is polyoxyethylene alkyl ether acetic acid. The terminal carboxylic acid in structural formula (7) interacts with the surface functional groups of the conductive filler carbon black through hydrogen bonding, acting as a dispersant for the carbon black. In addition, to enhance its effectiveness as a dispersant, R71, a monovalent hydrocarbon group with 1 to 12 carbon atoms, is introduced, resulting in a structure that is easily compatible with the hydrophobic functional groups of polycarbonate urethane, resulting in a structure that is also compatible with polycarbonate urethane.

[0093] Polyoxyethylene alkyl ether acetic acid can be obtained by synthesis or commercially available products. Polyoxyethylene alkyl ether acetic acid can be synthesized by carrying out the following step (E) followed by step (F). Note that step (F) may also be carried out on a commercially available product whose structure has been completed up to step (E). Step (E): Reaction of alcohol with ethylene oxide Step (F): Oxidation reaction of the primary alcohol, which is the product of step (E) Step (E) is the same as step (A) and can be prepared by the same method as step (A).

[0094] Step (F) is a step in which a primary alcohol is oxidized to produce a carboxylic acid. In the oxidation of a primary alcohol, an aldehyde is produced, and then a carboxylic acid is produced by further oxidation. Therefore, it is necessary to select a reaction method and conditions that do not stop at the aldehyde. Methods for obtaining a carboxylic acid by oxidation of a primary alcohol include oxidation with an oxidizing agent and oxidation with a catalyst. Catalytic dehydrogenation is one example. Oxidizing agents include permanganate, chromic acid, ruthenium tetroxide, and hypochlorite. Dehydrogenation catalysts include palladium, platinum, iridium, rhodium, and manganese.

[0095] The compounds represented by structural formulas (5) to (7) function as dispersants for carbon black and have high affinity with polycarbonate urethane. Surfactants are typically used to improve the dispersibility and dispersion stability of carbon black. However, the compounds represented by structural formulas (5) to (7) have a low number of functional groups that interact with the surface functional groups of carbon black, resulting in weak surfactant properties and making them uncommonly used. Coupling agents and nonionic surfactants are commonly used as dispersants for carbon black.

[0096] Silane coupling agents, titanate coupling agents, and aluminum coupling agents are used as coupling agents, while polyester and polyether-based nonionic surfactants are used. However, adding these dispersants to polycarbonate urethane to a level that sufficiently enhances the dispersibility of carbon black (50 to 100% by mass relative to the carbon black) inhibits the conductivity of the carbon black and binder resin. Conversely, adding them in an amount that does not inhibit the conductivity of the carbon black and binder resin (10 to 40% by mass relative to the carbon black) does not result in sufficient dispersibility of the carbon black.

[0097] The amount of the compounds represented by structural formulas (5) to (7) added is preferably 3.0 to 7.0 mass % based on the solid content in the conductive layer-forming coating liquid, more preferably 3.0 to 5.0 mass %, and the total content is preferably 18.9 to 46.0 mass parts per 100 mass parts of carbon black in the conductive layer-forming coating liquid. By keeping the content of the additive in the conductive layer-forming coating liquid within the above range, the dispersibility of carbon black in polyurethane is further improved, and the desired impedance value and surface potential can be more easily achieved.

[0098] The presence of the additive in the conductive layer can be confirmed and quantitatively evaluated by the following method. The conductive layer of the developing roller is cut out, and the cut piece is subjected to, for example,1 H-NMR, 13 Analysis is performed using CNMR, XPS, and FT-IR. This allows the carbonate structure of the binder resin, and the ether structure, amine structure, and carboxylic acid structure of the additives to be detected in the conductive layer, and the ratio can be calculated from the peak ratios, etc. Alternatively, sections can be extracted by immersing them overnight in an organic solvent such as 2-butanone (methyl ethyl ketone; MEK), and the extract and the extracted sections can be analyzed. 1 H-NMR, 13 Analysis using C-NMR, XPS, and FT-IR is performed, which allows us to calculate the proportion of additives that have been incorporated into the resin during the polymerization reaction and those that have not.

[0099] The conductive layer may have a structure in which at least one of the compounds having the structures represented by structural formulas (5) and (6) is bonded to polyurethane (a structure resulting from a reaction during polyurethane polymerization). Examples of the structure resulting from a reaction during polyurethane polymerization include the following: In the case of the structure represented by structural formula (5), in polyurethane, the compound having the structure represented by structural formula (5) is a urethane structure. In the case of the structure represented by structural formula (6), in polyurethane, the compound having the structure represented by structural formula (6) is a urea-modified structure.

[0100] (roughening particles) The conductive layer may contain roughening particles. The roughening particles may be, for example, spherical particles. The particle diameter of the roughening particles is preferably in the range of, for example, 1 μm to 150 μm, and more preferably in the range of 5 μm to 150 μm. It is more preferable that the particle size is in the range of 30 μm. For example, at least one spherical particle selected from the following particles can be used. Urethane resin particles, acrylic resin particles, phenolic resin particles, silicone resin particles, polyacrylonitrile resin particles, polystyrene resin particles, polyurethane resin particles, nylon resin particles, polyethylene resin particles, polypropylene resin particles, preferably urethane resin particles. The content of the roughening particles in the conductive layer is preferably 1 to 50 mass %, more preferably 5 to 30 mass %.

[0101] (Conductive layer manufacturing method) The method for forming the conductive layer is not particularly limited, but examples include spraying, dip coating, and roll coating. For example, a conductive layer can be formed by applying a conductive layer-forming coating liquid to the substrate or an elastic layer formed on the outer surface of the substrate using a known method, and then heating and drying the applied coating liquid. The conditions for heating and drying are not particularly limited, and examples include methods in which the conductive layer is dried at temperatures of 120 to 200°C. The thickness of the conductive layer is also not particularly limited, and is preferably 1 to 50 μm, and more preferably 5 to 20 μm.

[0102] (Time constant of the surface potential of the conductive part) It is preferable that the time constant of the surface potential of the conductive portion is 6.0 seconds or less, since the charge injected into the conductive portion can be easily and quickly removed. Specifically, in an environment of a temperature of 23°C and a relative humidity of 50%, a corona discharger having a grid portion with a width of 3.0 mm was placed so that the distance between the grid portion and the outer surface of the developing roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the developing roller, a voltage of 8 kV was applied to the grid portion, and the corona discharger was moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec to charge the outer surface of the developing roller, and when the potential of the outer surface was measured t seconds after the grid portion had passed, The change in potential in the range of 0.06≦t≦100.00 was fitted to the following equation (Y) by the least squares method, and V 0,2 When [V] and τ2 [seconds] are calculated, τ2 is preferably 6.0 seconds or less. τ2 is more preferably 5.0 seconds or less, and even more preferably 4.0 seconds or less. There is no particular lower limit, and τ2 may be in the range of, for example, 0.1 to 6.0 seconds, 0.1 to 5.0 seconds, or 0.1 to 4.0 seconds. V(t)=V1(t)+V2(t) (Y) (In formula (Y), V2(t)=V 0,2 exp(-t / τ2) (Z))

[0103] As mentioned above, V1(t) represents the relaxation curve corresponding to the insulating portion. The change in potential in the range of 0.06≦t≦100.00 also includes the influence of the relaxation curve corresponding to the conductive portion, which decays quickly. Therefore, V2(t) in the above formula (Y) obtained by fitting the change in potential in the range of 0.06≦t≦100.00 represents the relaxation curve corresponding to the conductive portion. Therefore, V 0,2 is the surface potential of the conductive part at t = 0, and τ2 is the time constant of the surface potential of the conductive part. V 0,2 The detailed measurement conditions for τ and τ2 will be described later. The time constant of the surface potential of the conductive portion can be controlled by changing the blending ratio of the binder resin and conductive filler within a range that satisfies the impedance value and surface potential of the conductive layer.

[0104] [First area (insulation)] The first region (insulating portion) is disposed on the outer surface of the conductive layer. The first region is, for example, configured by the outer surface of an insulator exposed on the outer surface of the conductive layer. The first region may, for example, be scattered on the conductive layer, or may be connected to the conductive layer (second region) so that the conductive layer (second region) is exposed.

[0105] When a square observation area with sides of 300 μm is placed on the outer surface of the developing roller so that the axial direction of the developing roller and one side of the observation area are parallel, the ratio of the total area of ​​the first area to the area of ​​the square observation area is preferably 10 to 60 area%, more preferably 15 to 50 area%, and even more preferably 20 to 40 area%, from the viewpoint of imparting an appropriate gradient force to the developing roller. The proportion of the total area of ​​the first region can be controlled by the wettability of the constituent material solution of the first region, the viscosity of the solution, the drying speed, the surface roughness of the conductive layer, the solid content of the solution, and the like.

[0106] The height of each insulating portion from the contact portion with the conductive layer is preferably 0.1 to 10.0 μm. By making this height 0.1 μm or more, the first region can easily attract toner when it is charged. By making this height 10.0 μm or less, the toner can easily be charged between the first region and the contact member. The ratio of the total area and the height of the first region can be measured using, for example, a laser microscope (product name: VK-X100, manufactured by Keyence Corporation). Specific details will be described later.

[0107] (Surface potential of insulating part) It is preferable that the time constant (τ1) of the surface potential of the insulating part is 60.0 seconds or more, because the charge injected into the insulating part is difficult to remove and the insulating part is quickly charged. By quickly charging the insulating part, the potential difference with the conductive part becomes clear from the start of printing, making it easier to demonstrate toner transport power. τ1 is more preferably 100.0 seconds or more, and even more preferably 1000.0 seconds or more. There is no particular upper limit to τ1, but the range of τ1 may be 60.0 to 5000.0 seconds, 100.0 to 4500.0 seconds, or 1000.0 to 4000.0 seconds. As described above, the time constant of the surface potential of the insulating portion can be obtained by measuring the change in the surface potential of the developing roller and fitting the change in the potential over a period of 30.00≦t≦100.00 seconds to the following equation (X′) using the least squares method. V1(t)=V 0,1 exp(-t / τ1) (X') Detailed measurement conditions will be described later.

[0108] In addition, in an environment of 23°C temperature and 50% relative humidity, a corona discharger having a 3.0 mm wide grid portion was placed so that the distance between the grid portion and the outer surface of the developing roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the developing roller, a voltage of 8 kV was applied to the grid portion, and the corona discharger was moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec to charge the outer surface of the developing roller, and the potential of the outer surface was measured t seconds after the grid portion had passed. The change in potential at 30.00≦t≦100.00 was fitted to the above equation (X') by the least squares method, and V 0,1 When calculating [V] and τ1 [seconds], if the value of the potential V1(t) when t = 0.06 [seconds] is substituted into formula (X') is V1 [V], it is preferable that V1 is 5.0 V or more. By having a surface potential of 5.0 V or higher immediately after being charged by a corona discharger, the gradient force required to transport the toner is easily exerted when a charge is injected into the insulating portion. V1 is more preferably 6.0 V or higher, and even more preferably 10.0 V or higher. There is no particular upper limit for V1, but V1 may be in the range of 5.0 to 35.0 V, 6.0 to 33.0 V, or 10.0 to 20.0 V. To achieve the above τ1 and V1, the volume resistivity of the insulating part must be 1.0×10 13 Ω cm or more 1.0×10 18 It is preferable that the resistance is Ω·cm or less, and 1.0×10 14 Ω cm or more, 1.0×10 17 It is more preferable that the resistivity is Ω·cm or less. The volume resistivity of the insulating portion can be adjusted by using, for example, the following materials and adjusting the amount thereof.

[0109] (Materials that make up the insulating part) Various electrically insulating materials can be used as the material for the insulating portion. Furthermore, it is preferable that the material be relatively resistant to cracking when the developing member is deformed by contact with another member. Specific examples include inorganic materials such as metal oxides such as silicon dioxide and aluminum oxide, and diamond. Other examples include resins such as polyethylene, polystyrene, polycarbonate, polyacrylic, polytetrafluoroethylene, phenolic resin, urea resin, silicone resin, and polyimide resin. Resins such as polystyrene, polycarbonate, polyacrylic, polytetrafluoroethylene, silicone resin, and polyimide resin, as well as copolymers of these resins, are particularly preferred because they have high electrical resistance, are resistant to cracking even with slight deformation, and are resistant to friction. Among these, polycarbonate is preferred. Therefore, it is preferable that the first region contains at least one type of polycarbonate.

[0110] Among these, it is preferable that the insulating portion contains a polycarbonate having the following specific structure, because this makes it easier to inject charge into the toner and tends to improve fog even immediately after printing a high-density image. That is, it is preferable that at least one polycarbonate has a structure represented by the following structural formula (8). [ka] In structural formula (8), R81 to R88 are each independently a hydrogen atom, an alkyl group having 1 to 9 carbon atoms (preferably 1 to 4, more preferably 1 to 3), or an aryl group having 6 to 10 carbon atoms (preferably 6 to 8, more preferably 6). R89 and R90 each independently represent a hydrogen atom, an alkyl group having 1 to 9 carbon atoms (preferably 1 to 4, more preferably 1 to 3), or an aryl group having 6 to 10 carbon atoms (preferably 6 to 8, more preferably 6), or R89 and R90 are a group of atoms necessary for R89 ​​and R90 to be linked together to form an alicyclic structure having 6 to 12 carbon atoms.

[0111] However, the structural formula (8) satisfies at least one condition selected from the group consisting of the following conditions 1 and 2: ·Condition 1 At least one (preferably 1 to 4, more preferably 1 to 3, and even more preferably 2) selected from the group consisting of R81 to R88 is an alkyl group having 1 to 9 carbon atoms (preferably 1 to 4, more preferably 1 to 3), or an aryl group having 6 to 10 carbon atoms (preferably 6 to 8, more preferably 6). The remainder of R1 to R8 are preferably hydrogen atoms. ·Condition 2 At least one selected from the group consisting of R89 and R90 is a linear or branched alkyl group having 2 or more carbon atoms (preferably 2 to 10, more preferably 3 to 6), or an aryl group having 6 to 10 carbon atoms (preferably 6 to 8, more preferably 6). It is preferable that one of R89 and R90 satisfies the above, and the other is an alkyl group having 1 to 3 carbon atoms (preferably 1).

[0112] When the driving torque between the toner supply roller and the developing roller is reduced, Because friction with the developing roller decreases, the amount of charge on the toner there tends to decrease. The impact is minor when the toner on the developing roller is repeatedly rubbed with the rotation of the developing roller. On the other hand, when a high-density image is printed, most of the toner on the developing roller is consumed by the photosensitive drum, and most of the toner on the developing roller becomes newly supplied toner that has not been subjected to much friction. Therefore, the toner on the developing roller immediately after printing a high-density image tends to be insufficiently charged, which can lead to increased fogging.

[0113] The polycarbonate structure of structural formula (8) has steric hindrance in the aromatic ring of the main chain, resulting in lower molecular orientation and higher molecular mobility compared to conventional polycarbonates. By providing steric hindrance around the aromatic ring, the polycarbonate has higher molecular mobility due to steric hindrance around the aromatic ring compared to conventional polycarbonates. When exposed to an external electric field, micro-molecular orientation occurs in some areas, increasing the dielectric constant. That is, when passing through a development blade nip to which a development blade bias is applied, the dielectric constant of the insulating portion increases. Therefore, the toner sandwiched between the development blade and the insulating portion is more likely to receive and transfer charge due to the electric field. The conductive layer of the present disclosure suppresses charge leakage from the insulating portion to the conductive layer, resulting in easier charge injection not only into the insulating portion but also into the toner. As a result, the toner is more likely to be charged quickly when passing through the development blade, thereby further reducing fogging immediately after printing a high-density image. In addition, since the polycarbonate has low molecular orientation, its dielectric constant is low when it is not exposed to an external electric field, and the potential rises when it is charged, making it easy to obtain toner transport power, making it suitable as a material for the insulating part.

[0114] More preferred polycarbonates are described below. Examples of polycarbonates include those in which, in the structural formula (8), at least one of R81 and R83 is an alkyl group having 1 to 9 carbon atoms or an aryl group having 6 to 10 carbon atoms, and at least one of R86 and R88 is an alkyl group having 1 to 9 carbon atoms or an aryl group having 6 to 10 carbon atoms, and those in which, in the structural formula (8), at least one selected from the group consisting of R89 and R90 is a linear or branched alkyl group having 2 or more carbon atoms, or an aryl group having 6 to 10 carbon atoms. Specifically, it is preferable that the polycarbonate contains at least one selected from the group consisting of the following structural formulas (9) to (11): [ka]

[0115] By including at least one selected from the group consisting of the structural formulas (9) to (11) in the polycarbonate, micro-molecular orientation tends to be enhanced when exposed to an external electric field. Furthermore, it is more preferable that at least one polycarbonate has a structure represented by the structural formula (9).

[0116] It is preferable that at least one polycarbonate has at least one structure selected from the group consisting of the structure represented by the above structural formula (10) and the structure represented by the above structural formula (11). By having this structure, the adhesive force of the aromatic rings can be further relaxed, and the micro-molecular orientation can be improved.

[0117] The following describes methods for synthesizing the polycarbonate. For example, the following two methods can be mentioned. The first is a method in which a bisphenol compound is directly reacted with phosgene (phosgene method). The second is a method in which a bisphenol compound is transesterified with a bisaryl carbonate such as diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, or dinaphthyl carbonate (transesterification method).

[0118] In the phosgene method, a bisphenol compound is usually reacted with phosgene in the presence of an acid binder and a solvent. Examples of the acid binder used here include pyridine and alkali metal hydroxides such as potassium hydroxide and sodium hydroxide. Examples of solvents include methylene chloride and chloroform. Furthermore, a catalyst or molecular weight modifier may be added to promote the condensation polymerization reaction. Examples of catalysts include tertiary amines such as triethylamine, or quaternary ammonium salts. Examples of molecular weight modifiers include monofunctional compounds such as phenol, p-cumylphenol, t-butylphenol, and long-chain alkyl-substituted phenols.

[0119] In addition, when synthesizing polycarbonate, antioxidants such as sodium sulfite and hydrosulfite, and branching agents such as phloroglucin and isatin bisphenol may be used. The reaction temperature when synthesizing polycarbonate is preferably 0 to 150°C, more preferably 5 to 40°C. The reaction time varies depending on the reaction temperature, but is generally preferably 0.5 minutes to 10 hours, more preferably 1 minute to 2 hours. During the reaction, it is preferable to maintain the pH of the reaction system at 10 or higher. The chemical structure of the resin can be identified by NMR analysis.

[0120] The weight-average molecular weight (Mw) of the polycarbonate is preferably 1,000 or more and 500,000 or less. Generally, the smaller the weight-average molecular weight of the polycarbonate, the more likely it is that the insulating portions will gather together when forming the insulating portion on the conductive layer, resulting in a relatively tall, bowl-shaped configuration. Furthermore, the larger the weight-average molecular weight of the polycarbonate, the more likely it is that the insulating portion will spread over the conductive layer, resulting in a low, branched configuration. Therefore, by setting the weight-average molecular weight of the polycarbonate within the above range, it is easier to form an insulating portion that covers part of the conductive layer, which is preferable. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC).

[0121] (Method of forming the first region) The method for forming the first region that becomes the insulating portion is not particularly limited, and the following methods can be used, for example. Examples include a method in which an insulating portion-forming coating liquid, prepared by diluting an insulating material in a solvent, is applied to the conductive layer in an island pattern using screen printing, a jet dispenser, or the like, and then the solvent is dried and solidified. Another example includes a method in which the insulating portion-forming coating liquid is uniformly applied to the conductive layer by dipping or the like, and then repelled to expose the conductive layer by controlling the wettability, and then the solvent is dried and solidified. Another example includes a method in which an insulating portion-forming coating liquid containing the insulating material raw material is applied to the conductive layer in an island pattern using screen printing, a jet dispenser, or the like, and then the insulating material raw material is cured by heating or ultraviolet irradiation, as necessary. Another example includes a method in which an insulating portion-forming coating liquid containing the insulating material raw material is uniformly applied to the conductive layer by dipping or the like, and then repelled to expose the conductive layer by controlling the wettability, and then the insulating material raw material is cured by heating or ultraviolet irradiation, as necessary. As a method for controlling the wettability, for example, a method of adding a surface conditioner to the conductive layer can be used.

[0122] [Elastic layer] The developing roller may have an elastic layer on the outer surface of the substrate. The developing roller has the elastic layer between the substrate and the conductive layer, for example. The elastic layer is not particularly limited, and any known elastic layer for developing rollers may be used. For example, a cured product of an addition-curing liquid silicone rubber mixture may be used.

[0123] <Process cartridge and electrophotographic image forming apparatus> The developing roller of the present disclosure can be suitably used as a developing roller in a process cartridge. Fig. 3 is a schematic cross-sectional view of an example of a process cartridge according to one embodiment of the present disclosure. The process cartridge 22 is configured to be detachably mountable to the main body of an electrophotographic image forming apparatus. The process cartridge 22 includes a developing roller 14 and a developing blade 15. The developing device 18, photosensitive member 19, charging roller 20, and cleaning blade 21 are integrated into one unit. That is, the process cartridge is equipped with a developing means, and the developing means has a developing roller 14. The developing device 18 is further filled with toner 16. The toner 16 is supplied to the surface of the developing roller 14 by a toner supply roller 17, and a layer of toner 16 of a predetermined thickness is formed on the surface of the developing roller 14 by a developing blade 15.

[0124] The developing roller 14 is in contact with the photosensitive member 19 and is driven to rotate at a predetermined peripheral speed ratio relative to the photosensitive member 19. A predetermined bias is applied to the developing roller 14, and the electrostatic latent image on the photosensitive member 19 is developed with the toner 16 to be visualized.

[0125] The toner supply roller 17 contacts the developing roller 14, penetrates a predetermined amount, and rotates in the same direction as or opposite to the rotation direction of the developing roller 14. A predetermined bias may be applied to the toner supply roller 17. By reducing the difference in relative speed between the toner supply roller 17 and the developing roller 14 or by reducing the penetration amount of the toner supply roller 17 into the developing roller 14, the drive torque can be significantly reduced.

[0126] One end of the developing blade 15 is fixed to the developing device 18, and the other free end is arranged in contact with the developing roller 14 in the counter direction to the rotational direction. By arranging the developing blade 15 in contact with the developing roller 14, the amount of toner on the developing roller 14 is regulated, making the layer thinner and forming a toner layer of uniform thickness. In addition, a predetermined bias is applied to the developing blade 15, which imparts an electric charge to the toner 16 and the insulating portion on the outer surface of the developing roller 14.

[0127] FIG. 4 is a schematic cross-sectional view showing an example of an electrophotographic image forming apparatus equipped with a contact-type developing device using one-component toner. The developing device 18 includes toner 16 as a single-component toner, a developing roller 14, a toner supply roller 17 that supplies toner to the developing roller 14, and a developing blade 15 that regulates the thickness of the toner layer on the developing roller 14. That is, the electrophotographic image forming apparatus is equipped with a developing means, and the developing means has the developing roller 14. The developing roller 14 is located in an opening extending in the longitudinal direction within the developing device 18, and is installed in contact with the photoconductor 19. Note that the photoconductor 19, charging roller 20, and cleaning blade 21 may be provided in the main body of the electrophotographic image forming apparatus. The developing device 18 is equipped with toner of each color: black, cyan, magenta, and yellow, enabling color printing.

[0128] The printing operation of an electrophotographic image forming apparatus will now be described. Photoconductor 19 rotates in the direction of the arrow and is uniformly charged by charging roller 20, which charges photoconductor 19. Next, an electrostatic latent image is formed on the surface of photoconductor 19 by laser light 23, which serves as exposure means. The electrostatic latent image is visualized as a toner image (developed) by developing device 18, which applies toner 16 from developing roller 14, which is placed in contact with photoconductor 19. Development is what is known as reversal development, in which a toner image is formed in the exposed area.

[0129] The toner image formed on the photosensitive member 19 is transferred onto an intermediate transfer member 25 in the form of an endless belt by a transfer roller 24 which is a transfer member. Paper 26, which is a recording medium, is fed into the device by paper feed roller 27 and secondary transfer roller 28, and is transported together with intermediate transfer body 25 bearing a toner image to the nip between secondary transfer roller 28 and driven roller 29, where the toner image is transferred to paper 26. Intermediate transfer body 25 is operated by driven roller 29, drive roller 30, and tension roller 31. Toner remaining on intermediate transfer body 25 is cleaned by cleaning device 32.

[0130] The developing roller 14, the developing blade 15, the transfer roller 24 and the secondary transfer roller 28 are provided with a Voltage is applied from bias power supply 33. Paper 26 onto which the toner image has been transferred is fixed by fixing device 34 and then ejected outside the device, completing the printing operation. Meanwhile, residual toner remaining on photoreceptor 19 without being transferred is scraped off by cleaning blade 21, which is a cleaning member for cleaning the surface of the photoreceptor. The cleaned photoreceptor 19 then repeats the above printing operation.

[0131] <Impedance> In impedance measurements, the response of the developing roller is examined when AC and DC voltages are applied while changing the frequency. An AC voltage is applied, and measurements are taken of two responses: one with no phase shift relative to the applied AC voltage, and one with a phase shift of π / 2. The impedance of the response with no phase shift is plotted on a complex plane as Z' (real part), and the impedance of the response with a phase shift is plotted as Z" (imaginary part), and the distance from the origin to the plot is calculated as the impedance value. When the electrical characteristics of the developing roller are expressed pseudo-wise using an RC parallel circuit, the real part without phase shift represents the resistance component, and the imaginary part with phase shift represents the capacitance component. Note that the meaning of the measurement conditions and measured values ​​was explained above in <Technical significance of requirement (1)>, so it will not be explained here.

[0132] The impedance measurement method, measurement device, and measurement conditions are described below. (Method of measuring impedance) The impedance of the developing roller can be measured by the following methods (1) and (2). (1) A method in which a thin film electrode is placed on the surface of the developing roller and measurement is performed using two terminals: the electrode and the substrate. (2) A method in which the developing roller is pressed against a metal drum with a constant load and measured at two terminals, one on the metal drum and the other on the base.

[0133] Although impedance can be measured by either method, method (2) is affected by the nip width and contact area between the developing roller and the metal drum, so it is necessary to measure using a developing roller with the same hardness. Therefore, in this disclosure, measurement is performed using method (1). Measurement method (1) will be described below, but more specific conditions will be described later. When measuring impedance, in order to eliminate the influence of contact resistance between the developing roller and the measurement electrode, it is preferable to deposit a low-resistance thin film on the surface of the developing roller, use the thin film as an electrode, and measure the impedance using two terminals, with the conductive substrate as a ground electrode.

[0134] Examples of methods for forming the thin film include metal deposition, sputtering, applying a metal paste, and attaching a metal tape. Among these, from the viewpoint of reducing contact resistance with the developing roller, a method of forming a metal thin film such as platinum or palladium as an electrode by deposition is preferred. In the present disclosure, vacuum platinum deposition is used.

[0135] When forming a metal thin film on the surface of a developing roller, in consideration of the ease of the process and the uniformity of the thin film, it is preferable to use a vacuum deposition apparatus that is provided with a mechanism that can grip the developing roller, and that is further provided with a rotation mechanism for a developing roller that has a cylindrical cross section.

[0136] It is preferable to form a thin metal film electrode about 10 mm wide in the longitudinal direction of the developing roller, and then connect a metal sheet wrapped tightly around the thin metal film electrode in a direction crossing the longitudinal direction to the measuring electrode protruding from the measuring device to perform the measurement. In the case of a cylindrical developing roller, it is preferable to use a metal sheet wrapped tightly around the circumferential direction of the developing roller. This makes it possible to perform impedance measurement without being affected by fluctuations in the size of the outer edge (outer diameter in the case of a cylindrical developing roller) in the cross section perpendicular to the longitudinal direction of the developing roller, or by the surface shape. The metal sheet may be aluminum foil, metal tape, or the like.

[0137] (Impedance measurement conditions) The impedance measurement equipment is an impedance analyzer, a network analyzer, a spectrum analyzer, etc., and is 1.0 x 10 -1 ~1.0×10 5 Any device capable of measuring impedance in a frequency range up to 100 Hz will suffice. Among these, it is preferable to measure the impedance using an impedance analyzer in the electrical resistance range of the developing roller. The impedance measurement conditions are as follows: An impedance measurement device was used, and the impedance was measured at 1.0 x 10 -1 ~1.0×10 5 The impedance is measured in the Hz frequency range. The measurement environment is a temperature of 23°C and a relative humidity of 50%. The impedance is measured at the center of the developing roller in the longitudinal direction. The voltage application condition is a DC voltage of 50V superimposed on an AC voltage of 50V.

[0138] More specifically, it is as follows. First, as a pretreatment, a measurement electrode is created by vacuum-evaporating platinum onto the developing roller while it is rotating. A vacuum evaporation device with a mechanism for gripping the base of the roller (the object to be coated) and rotating it circumferentially is used for evaporation. The roller rotation speed, evaporation distance, and evaporation time are controlled to achieve a film thickness of 100 nm or more. A 1.5 cm wide electrode is then created using masking tape. By forming this electrode with a film thickness of 100 nm or more, the contribution of the contact area between the measuring electrode and the developing roller, which is caused by the surface roughness of the developing roller, can be minimized.

[0139] Next, an aluminum sheet is wrapped tightly around the electrode, and the aluminum sheet is connected to the measurement electrodes of an impedance measuring device (product names: Solartron 1260 and Solartron 1296, manufactured by Solartron) and a high-voltage system (product names: 6792 and HVA-500, manufactured by Toyo Corporation).

[0140] Figure 5 shows a schematic diagram of the state in which the measurement electrodes are formed on the developing roller. In Figure 5, 51 is a conductive substrate, 52 is a conductive layer, 53 is a platinum vapor deposition layer, and 54 is an aluminum sheet. In this figure, the elastic layer is not shown, but it exists between the substrate 51 and the conductive layer 52.

[0141] Figure 6 shows a cross-sectional view of the developing roller with the measurement electrode formed on it. 61 is the conductive substrate, 62 is the elastic layer, 63 is the conductive layer, 64 is the insulating part, 65 is the platinum vapor deposition layer, and 66 is the aluminum sheet. As shown in Figure 6, it is important to sandwich the conductive layer between the conductive substrate and the measurement electrode.

[0142] The aluminum sheet was then connected to the measurement electrodes of an impedance measurement device (Solatron 1260 and Solartron 1296, manufactured by Solartron) and a high-voltage system (product names: 6792 and HVA-500, manufactured by Toyo Corporation). Figure 7 shows a schematic diagram of this measurement system. Impedance measurements were performed using the conductive substrate and the aluminum sheet as the two electrodes for measurement.

[0143] The impedance was measured at a temperature of 23°C and a relative humidity of 50%, with a DC voltage of 50V and an AC voltage of 50V applied, and a frequency of 1.0 x 10 -1 ~1.0×10 5 The absolute value of the impedance is obtained in Hz, and the frequency is 1.0 x 10 0 ~1.0×10 1 Check the minimum impedance value in Hz. The impedance measurement point is the center of the developing roller in the longitudinal direction.

[0144] <Surface potential measurement> A corona with a grid section of 3.0 mm in width was used under an environment of 23°C and 50% relative humidity. The discharger is positioned so that the distance between the grid section and the outer surface of the developing roller is 1.0 mm, and the width direction of the grid section coincides with the axial direction of the developing roller. A voltage of 8 kV is applied to the grid section, and the corona discharger is moved relatively along the axial direction of the developing roller at a speed of 400 mm / s to charge the outer surface of the developing roller. The corona discharger is stopped at a measurement position on the developing roller, and the change in the surface potential of the developing roller is measured at 0.01 second intervals from 0.06 seconds to 100.00 seconds after passing the grid section.

[0145] When the time from passing through the grid is t (seconds), the surface potential at t = 0.06 is V INI Furthermore, the measurement results for 30.00≦t≦100.00 are fitted to the following formula (X') by the least squares method, and V 0,1 , and τ1 are calculated. V1(t)=V 0,1 exp(-t / τ1) (X') Furthermore, from V1, which is the value when t = 0.06 [seconds] is substituted into the above formula, V INI Calculate -V1.

[0146] In addition, the measurement results for 0.06≦t≦100.00 were fitted to the following equation (Y) using the least squares method, and V 0,2 Calculate [V] and τ2. V(t)=V1(t)+V2(t) (Y) In formula (Y), V2(t)=V 0,2 exp(-t / τ2) (Z) The above measurement is carried out at 9 points in total, 3 points in the longitudinal direction and 3 points in the circumferential direction of the developing roller, and the arithmetic mean value is taken as the V of the developing roller. INI Let V1, τ1, and τ2 be -V1, τ1, and τ2.

[0147] The surface potential of the developing roller can be measured, for example, using the device shown in Figure 8. Both ends of substrate 82 of developing roller 81 are held by chucks 83, and a measurement unit 86, which includes a corona discharger 84 and a surface electrometer 85 arranged in parallel with a 25 mm gap between them, is positioned facing the surface of developing roller 81 at a distance of 1.0 mm. With developing roller 81 stationary, a voltage of 8 kV is applied to the grid portion of corona discharger 84, and measurement unit 86 is moved in the axial direction of developing roller 81 at a speed of 400 mm / sec. The change in the surface potential of the developing roller from 0.06 seconds to 100.00 seconds after passing through corona discharger 84 is measured using surface electrometer 85 at 0.01 second intervals. The meaning of the measurement conditions and measurement values ​​has been explained in the above section <Technical significance of requirement (2)>, so it will not be covered here.

[0148] More specifically, it is as follows. The surface potential of the developing roller is measured using a charge measurement device (product name: DRA-2000L, manufactured by QEA). Specifically, in an environment of 23°C temperature and 50% relative humidity, a corona discharger with a grid is placed so that the distance between the grid and the outer surface of the developing roller is 1.0 mm and the width direction of the grid coincides with the axial direction of the developing roller. The grid of the corona discharger of the above device is 3.0 mm wide. Next, a voltage of 8 kV is applied to the corona charger, and the corona charger is moved relatively along the axial direction of the developing roller at a speed of 400 mm / s to charge the surface of the conductive member. The surface potential of the developing roller is measured at 0.01 second intervals from 0.06 seconds to 100.00 seconds after passing the grid section.

[0149] <Calculation of various physical properties such as the circle equivalent diameter and wall distance of carbon black dispersed in the conductive layer> The dispersed particle size and wall-to-wall distance of the carbon black dispersed in the conductive layer are measured by the following method. First, a section (0.5 to 1.0 mm thick) is cut out using a razor so that a cross section perpendicular to the longitudinal direction of the developing roller can be observed. If the substrate and conductive layer are tightly adhered to each other and cutting out with a razor is difficult, the substrate can be cut out with a hacksaw or similar tool, and then the cross section can be processed using a FIB (Focused Ion Beam) device.

[0150] Next, platinum is vapor-deposited on the slice, and the conductive layer is photographed at 15,000 times magnification using a scanning electron microscope (SEM) (trade name: JSM-7800F, manufactured by JEOL Ltd.) to obtain a cross-sectional image. Furthermore, in order to quantify the cross-sectional images obtained by SEM observation, the cross-sectional images were processed using image processing software (trade name: Luzex AP, manufactured by Nireco Corporation) to obtain 8-bit resolution. The cross-sectional image is then grayscaled to obtain a monochrome image with 256 gradations. Next, the image is inverted so that the carbon black in the cross-sectional image appears white, and a binarization threshold is set for the brightness distribution of the image based on the algorithm of Otsu's discriminant analysis method, resulting in a binarized image in which the carbon black appears white and the binder resin appears black.

[0151] Then, using image processing software (trade name: Luzex AP, manufactured by Nireco Corporation) on the obtained binarized image, the equivalent circle diameter and the distance between adjacent wall surfaces of the whitened carbon black portions are calculated. The image region for calculating the equivalent circle diameter and the distance between adjacent wall surfaces is set to an area 0.075 μm inside in actual image dimensions (if there is a text section describing the SEM measurement conditions, etc., then 0.075 μm inside from where the actual image begins) to eliminate uncertainty in the calculated values ​​for the carbon black that is divided at the top, bottom, left, and right edges of the image, and the equivalent circle diameter and the distance between adjacent wall surfaces are calculated for all carbon black within the specified image region. The arithmetic mean and standard deviation are then calculated for the distribution of the obtained circle equivalent diameter and the distance between adjacent wall surfaces. Although there is no particular problem with using just one image for image analysis, at least three images should be used to eliminate the influence of differences in the longitudinal direction of the carbon black dispersed in the conductive layer of the developing roller.

[0152] The number-average diameter of the primary particles of the carbon black dispersed in the resin is measured using a transmission electron microscope (TEM). First, a thin sectioned sample is prepared. A known method can be used for thinning. For example, the sample can be thinned using an ion beam or a diamond knife. In this disclosure, a 40 nm thick thin sectioned sample for observation is prepared using an ultramicrotome (product name: ULTRACUT-S, manufactured by Leica Microsystems). Then, a TEM image is obtained using a transmission electron microscope (product name: H-7100FA, manufactured by Hitachi High-Technologies Corporation) under measurement conditions of TE mode and an accelerating voltage of 100 kV. Then, using image analysis software (trade name: WinROOF, manufactured by Mitani Shoji Co., Ltd.) for the obtained TEM image, the circle-equivalent diameters of 50 primary particles of carbon black in the TEM image are measured, and the number-average value of the 50 particles is taken as the number-average diameter of the primary particles.

[0153] <Confirmation of the first and second areas> The outer surface of the developing roller was observed using a laser microscope (product name: VK-X100, manufactured by Keyence Corporation) with a 20x objective lens attached. Island-shaped repelled first regions and second regions where the conductive layer was exposed on the surface could be confirmed on the roller surface.

[0154] <Percentage of the total area of ​​the first area> An objective lens with a magnification of 20x was installed on a laser microscope (product name: VK-X100, manufactured by Keyence Corporation). Images of the surface of the developing roller were taken at nine areas: two locations 10 mm inward from both ends in the longitudinal direction, one location in the center, and three locations in the circumferential direction (at 120° intervals). Next, the tilt of the obtained observation image is corrected in quadric surface correction mode, assuming that the axial direction of the developing roller and the observation image are now parallel. At the center of the corrected image, the total area occupied by the first region within a square area with sides of 300 μm is measured. The total area occupied by this first region is divided by the square area with sides of 300 μm, and the resulting value is used as the percentage of the total area of ​​the first region. The arithmetic mean of the total area percentages obtained for the nine regions is calculated, and this is used as the percentage of the total area of ​​the first region of the developing roller.

[0155] <Resistance measurement of the first region> A sample including the first region is cut out from the developing roller, and a thin sample having a planar size of 50 μm square and a thickness t of 100 nm is prepared using a microtome. Next, this thin sample is placed on a metal flat plate, and a pressing surface area S of 100 μm is pressed from above. 2 The thin sample is pressed against the metal terminal. In this state, a voltage of 1 V is applied between the metal terminal and the metal plate using an electrometer 6517B (trade name, manufactured by KEITHLEY) to measure the resistance R. From this resistance R, the volume resistivity pv (Ω·cm) is calculated using the following formula. pv=R×S / t

[0156] (Measurement of DBP absorption amount of carbon black) The DBP absorption of carbon black is measured for carbon black powder in accordance with Japanese Industrial Standards (JIS) K6217-4.

[0157] (Measurement of pH of carbon black) The pH of carbon black is measured on carbon black powder according to ASTM D1512. [Example]

[0158] The present disclosure will be described in more detail below with reference to examples, but these examples are not intended to limit the present disclosure in any way.

[0159] <Example of developing roller manufacturing> In this embodiment, a developing roller is described in which a conductive layer is laminated on an elastic roller having an elastic layer on the outer surface of a base body, and an insulating portion is further arranged, but the developing roller is not limited to this configuration.

[0160] [1. Preparation and manufacturing of raw materials for forming conductive layer] <1-1. Preparation of raw polyol and manufacturing example> A synthesis example for obtaining a polyurethane resin layer will be shown below.

[0161] [Measurement of number average molecular weight of raw material polyol] The apparatus and conditions used for measuring the number average molecular weight (Mn) in this production example are as follows. Measuring device: HLC-8120GPC (Tosoh Corporation) Column: TSKgel Super HZMM (Tosoh Corporation) x 2 Solvent: tetrahydrofuran (THF) (20 mmol / l triethylamine added) Temperature: 40℃ THF flow rate: 0.6 ml / min The measurement sample was a 0.1% by mass THF solution. Furthermore, the measurement was carried out using an RI (refractive index) detector as the detector. A calibration curve was created using TSK standard polystyrenes A-1000, A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40, F-80, and F-128 manufactured by Tosoh Corporation as standard samples. Based on this calibration curve, the number average molecular weight was calculated from the retention time of the obtained measurement sample.

[0162] [Preparing raw polyol] Commercially available products were used as the five raw material polyols A-1 to A-5 shown in Table 1. Raw material polyols A-6 and A-7 were synthesized by the following method. [Table 1]

[0163] [Synthesis of raw material polyol A-6] Under a nitrogen atmosphere, 100.0 g of 1,3-propanediol, 49.4 g of adipic acid, and 69.5 g of ethylene carbonate were mixed and heated, and the temperature was raised to 200°C while the ethylene glycol and water produced in the reaction system were distilled off. After the ethylene glycol and water were distilled off, 15 ppm of titanium tetraisopropoxide was added, and the polycondensation reaction was further carried out under a reduced pressure of 266.7 Pa. The reaction solution was cooled to room temperature to obtain raw material polyol A-6. The number average molecular weight of the resulting raw material polyol A-6 was 2030.

[0164] [Synthesis of raw material polyol A-7] Raw material polyol A-7 was produced in the same manner as raw material polyol A-6, except that the starting materials shown in Table 2 below were used. The number average molecular weight of raw material polyol A-7 was 2,040. [Table 2]

[0165] <1-2. Preparation of raw material isocyanates B-1 to B-3> The raw material isocyanates shown in Table 3 below were prepared. [Table 3]

[0166] <1-3. Production Examples of Hydroxyl-Terminated Urethane Prepolymers C-1 to C-3> [Synthesis of hydroxyl-terminated urethane prepolymer C-1] Under a nitrogen atmosphere, the materials listed in Table 4 below were reacted by heating and stirring at a temperature of 90°C for 3 hours. 2-Butanone (MEK) was then added to the resulting reaction product to prepare a solution with a solid content of 50 parts by mass, producing hydroxyl-terminated urethane prepolymer C-1. [Table 4]

[0167] [Synthesis of Hydroxyl-Terminated Urethane Prepolymers C-2 to C-5] Hydroxyl-terminated urethane prepolymers C-2 to C-5 were prepared using the starting materials listed in Table 5 below in the same manner as in the synthesis of hydroxyl-terminated urethane prepolymer C-1. The chemical structures of these hydroxyl group-terminated urethane prepolymers C-1 to C-5 are as follows: 1 H-NMR and 13 The molecular weights of the compounds were determined using C-NMR. In Table 5, m, n, q, r, and s in the structural formulae (1), (3), and (4) represent the average number of moles added. [Table 5]

[0168] For the hydroxyl group-terminated urethane prepolymers C-1 to C-2 containing the structure represented by structural formula (1) in the molecule, R13 in structural formula (1) was the same as R12. In the tables, when "x, y = A", such as when m and n = 6.9, this indicates that the average number of moles of x and y added is A. The same applies to the following tables. Parts indicate parts by mass.

[0169] <1-4. Production Examples of Isocyanate-Terminated Prepolymers D-1 to D-3> [Synthesis of isocyanate-terminated prepolymer D-1] The materials listed in Table 6 below were reacted under a nitrogen atmosphere by heating and stirring at 90°C for 3 hours. 2-Butanone (MEK) was then added to the resulting reaction product to prepare a solution with a solid content of 50 parts by mass, producing isocyanate-terminated prepolymer D-1. [Table 6]

[0170] [Synthesis of isocyanate-terminated prepolymers D-2 to D-3] Isocyanate group-terminated prepolymers D-2 and D-3 were prepared using the types and amounts of starting materials shown in Table 7 below in the same manner as in the synthesis of isocyanate group-terminated prepolymer D-1. The chemical structures of these isocyanate group-terminated prepolymers D-1 to D-3 are as follows: 1 H-NMR and 13 The molecular weight was determined using C-NMR. In Table 7, m, n, o, p, and s in structural formulas (1), (2), and (4) represent the average number of moles added. Parts represent parts by mass. [Table 7]

[0171] For the isocyanate group-terminated prepolymer D-2 containing the structure represented by structural formula (1) in the molecule, R13 in structural formula (1) was the same as at least one selected from the group consisting of R11 and R12.

[0172] [2. Preparation and manufacturing of conductive layer additive] <2-1. Preparation and Production Examples of Polyoxyethylene Polyoxypropylene Alkyl Ethers E-1 and E-2> [Preparation of polyoxyethylene polyoxypropylene alkyl ether] Additives E-1 and E-2 shown in Table 8 below, which are polyoxyethylene polyoxypropylene alkyl ethers, were commercially available products.

[0173] <2-2. Preparation of polyoxyethylene alkyl ether acetic acid, manufacturing example> [Preparation of polyoxyethylene alkyl ether acetic acid] E-3, which is a polyoxyethylene alkyl ether acetic acid as an additive, was synthesized as shown in Table 8 below.

[0174] [Synthesis of Polyoxyethylene Alkyl Ether Acetic Acid E-3] 55.0 g of polyoxyethylene methyl ether (trade name: BRAWNON MP-550, manufactured by Aoki Oil & Fat Chemicals Co., Ltd.; average number of moles of ethylene oxide added relative to alcohol: 12) was mixed with 510 ml of 1 mol / L aqueous sodium hydroxide solution, and 71.1 g of potassium permanganate was added and stirred at room temperature for 6 hours. Then, 760 ml of 2-propanol was added and stirred for 1 hour to quench the excess potassium permanganate. The by-product manganese oxide was filtered. The aqueous layer was extracted with dichloromethane and purified to obtain polyoxyethylene methyl ether acetic acid E-3. The structure of R71 and the value of x for E-3 are shown in Table 8.

[0175] <2-3. Preparation of polyetheramine, manufacturing example> [Preparation of polyetheramine] Additive E-4, which is a polyetheramine shown in Table 8 below, was a commercially available product. [Table 8]

[0176] [3. Example of manufacturing a coating solution for forming a conductive layer] <3-1. Preparation of conductive layer forming coating solution F-1> The materials for conductive layer-forming coating solution F-1, the types and amounts of which are listed in Table 9 below, were added to a reaction vessel and stirred. Next, 2-butanone (MEK) was added so that the total solids ratio was 30% by mass, and the mixture was mixed using a sand mill. Next, 2-butanone (MEK) was added to adjust the viscosity of the solution to within the range of 6 to 10 mPa·s, thereby producing conductive layer-forming coating solution F-1. [Table 9]

[0177] <3-2. Preparation of conductive layer forming coating solutions F-2 to F-13> Conductive layer-forming coating solutions F-2 to F-13 were prepared in the following manner. First, the hydroxyl-terminated urethane prepolymer, isocyanate-terminated prepolymer, additives, surface conditioner, carbon black, and roughening particles listed in Table 10 below were mixed in the same manner as in the preparation of conductive layer-forming coating solution F-1. 2-Butanone (MEK) was then added to adjust the viscosity of the solution to within the range of 6 to 10 mPa·s, producing conductive layer-forming coating solutions F-2 to F-13. [Table 10]

[0178] [4. Conductive Layer Roller Manufacturing Example] <4-1. Preparation of the substrate> As a substrate, a 6 mm diameter core bar made of stainless steel (SUS304) was prepared by applying a primer (product name: DY35-051, manufactured by Dow Toray Industries, Inc.) to the circumferential surface and baking it.

[0179] <4-2. Preparation of Elastic Layer> The substrate was placed in a mold, and an addition-type silicone rubber composition containing the materials shown in Table 11 was poured into the mold. It was poured into a cavity formed in a mold. [Table 11]

[0180] Next, the mold was heated to vulcanize and harden the silicone rubber at a temperature of 150°C for 15 minutes, and after demolding, it was further heated at a temperature of 180°C for 1 hour to complete the hardening reaction, resulting in an elastic roller with an elastic layer with a diameter of 11.5 mm on the outer periphery of the base body.

[0181] <4-3. Manufacturing example of conductive layer roller G-1> The elastic roller was oriented with its longitudinal direction in the vertical direction, and its upper end was gripped and immersed (dipped) in the conductive layer-forming coating solution F-1 to coat the surface of the elastic roller with the coating solution. The resulting coating was air-dried at room temperature for 30 minutes, and then dried and cured for 1 hour in a hot air circulating dryer set at 160°C. In this way, a conductive layer roller G-1 was obtained, in which a conductive layer with a thickness of 12 μm was formed on the elastic layer.

[0182] <4-4. Manufacturing Examples of Conductive Layer Rollers G-2 to G-13> Conductive layer rollers G-2 to G-13 were produced in the same manner as in the manufacturing example of conductive layer roller G-1, except that the conductive layer forming coating liquid F-1 was changed to F-2 to F-13 shown in Table 12 below. [Table 12]

[0183] [5. Preparation and manufacturing of insulating material] <5-1. Manufacturing Examples of Insulating Part Forming Materials I-1 to I-5> [Preparing raw material monomers] The four raw material monomers H-1 to H-4 shown in Table 13 below were commercially available products. [Table 13]

[0184] [Synthesis of insulating material I-1] 42.5 g of 2,2-bis(4-hydroxyphenyl)propane (Tokyo Chemical Industry Co., Ltd., product code B0494), 37.5 g of 2,2-bis(3-methyl-4-hydroxyphenyl)propane (Tokyo Chemical Industry Co., Ltd., product code B1567), and 0.1 g of hydrosulfite were dissolved in 1100 ml of a 5% by mass aqueous sodium hydroxide solution. 500 ml of methylene chloride was added to the solution, and while stirring and maintaining the temperature at 15°C, 60 g of phosgene was then blown in over 60 minutes.

[0185] After the phosgene injection was completed, 1.3 g of pt-butylphenol (hereinafter abbreviated as "PTBP": manufactured by Tokyo Chemical Industry Co., Ltd., product code B0383) was added as a molecular weight modifier and stirred to emulsify the reaction solution. After emulsification, 0.4 ml of triethylamine was added, and the mixture was stirred at 23°C for 1 hour to allow polymerization.

[0186] After the polymerization was completed, the reaction solution was separated into an aqueous phase and an organic phase. The organic phase was neutralized with phosphoric acid and repeatedly washed with water until the conductivity of the washing liquid (aqueous phase) reached 10 μS / cm or less. The resulting polymer solution was added dropwise to warm water maintained at 45°C, and the solvent was evaporated to obtain a white powdery precipitate. The resulting precipitate was filtered and dried at 110°C for 24 hours to obtain an insulating part-forming material I-1.

[0187] [Measurement of weight average molecular weight of insulating part forming material I-1] The apparatus and conditions used to measure the weight average molecular weight (Mw) of the insulating portion forming material in this production example are as follows. First, the sample is dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. The resulting solution is then filtered through a solvent-resistant membrane filter "Myshoridisc" (manufactured by Tosoh Corporation) with a pore size of 0.5 μm to obtain a sample solution. The sample solution is prepared so that the concentration is 0.5% by mass. This sample solution is measured under the following conditions. Apparatus: HLC-8320GPC (detector: RI) (manufactured by Tosoh Corporation) Column: Shodex LF-404, 2 columns of LF-404 (Showa Denko) Eluent: tetrahydrofuran (THF) Flow rate: 0.4ml / min Oven temperature: 40.0℃ Sample injection volume: 0.10 ml The molecular weight of the sample was calculated using a molecular weight calibration curve prepared using standard polystyrene resins (for example, trade name "EasiVial PS-H Polystyrene", manufactured by Agilent Technologies). The molecular weight of the insulating portion forming material I-1 was measured and found to be Mw=56,000.

[0188] [Synthesis of insulating material I-2 to I-5] Insulating portion forming materials I-2 to I-5 were prepared in the same manner as in the synthesis of insulating portion forming material I-1, except that the starting materials listed in Table 14-1 below were used. The chemical structures and molar ratios of these insulating portion forming materials I-1 to I-5 are as follows: 1 H-NMR and 13 Identification was performed using C-NMR. [Table 14-1]

[0189] <5-2. Preparation of insulating material I-6, manufacturing example> The acrylate monomers used were commercially available products shown in Table 14-2 below. [Table 14-2]

[0190] [6. Example of manufacturing coating liquid for forming insulating parts] <6-1. Preparation of coating solution J-1 for forming insulating parts> 100 parts by mass of the insulating portion forming material I-1 was weighed out, MEK was added to the material to give a concentration of 2.0 mass %, and the material was thoroughly dissolved to prepare insulating portion forming coating liquid J-1.

[0191] <6-2. Preparation of coating solutions J-2 to J-7 for forming insulating parts> In preparing the coating liquid J-1 for forming an insulating portion, coating liquids J-2 to J-7 for forming an insulating portion were prepared in the same manner as the coating liquid J-1 for forming an insulating portion, except that the materials and concentrations for forming the insulating portion were changed to those shown in Table 15 below.

[0192] <6-3. Preparation of coating solution J-8 for forming insulating parts> 100 parts by mass of the insulating part forming material I-6 was weighed out, and then 5.0 parts by mass of a photopolymerization initiator (product name: Omnirad184, manufactured by IGM Resins) was weighed out, and MEK was added to a concentration of 2.0% by mass, and the mixture was thoroughly dissolved to prepare insulating part forming coating liquid J-8. [Table 15]

[0193] [7. Manufacturing Examples of Developing Rollers and Comparative Developing Rollers] <7-1. Manufacturing example of developing roller K-1> The conductive layer roller G-1 was oriented with its longitudinal direction vertical, its upper end was gripped, and immersed (dipped) in the insulating portion-forming coating liquid J-1 to coat the surface of the conductive layer roller G-1 with the coating liquid. The resulting coating was air-dried at room temperature for 30 minutes and then dried for 1 hour in a hot air circulating dryer set at 90°C. In this way, a developing roller K-1 was obtained, with an insulating portion formed on the conductive layer. The physical properties of the developing roller K-1 are shown in Tables 16-1 and 16-2.

[0194] <7-2. Manufacturing Examples of Developing Rollers K-2 to K-19> Developing rollers K-2 to K-19 were obtained in the same manner as in the manufacturing example of developing roller K-1, except that the conductive layer roller and the insulating portion-forming coating liquid were changed to those shown in Table 16-1 below. The physical properties of developing rollers K-2 to K-19 are shown in Tables 16-1 and 16-2.

[0195] <7-3. Manufacturing example of developing roller K-20> The conductive layer roller G-1 was oriented with its longitudinal direction in the vertical direction, and its upper end was gripped and immersed (dipped) in the insulating portion-forming coating liquid J-8 to coat the surface of the conductive layer roller G-1 with the coating liquid. The resulting coating was air-dried at room temperature for 30 minutes, and then dried for 1 hour in a hot air circulating dryer set at 90°C to obtain a conductive layer roller G-1 to which a mixture of the insulating portion-forming material and the photopolymerization initiator was adhered. Thereafter, the outer surface of the conductive layer roller G-1 was exposed to an integrated light intensity of 2000 mJ / cm 2 2The insulating portion-forming material was cured by irradiating it with ultraviolet light so that the insulating portion was cured. In this way, developing roller K-20 was obtained, with an insulating portion formed on the conductive layer. Note that a high-pressure mercury lamp (product name: handy type UV curing device, manufactured by Mario Network Co., Ltd.) was used as the ultraviolet irradiating device. The physical properties of developing roller K-20 are shown in Tables 16-1 and 16-2. [Table 16-1] In the table, for example, 9.1E+06 is 9.1 x 10 6 The same applies to the other tables below. The minimum impedance is a frequency of 1.0 x 10 0 Hz~1.0×10 1 Indicates the minimum impedance value in Hz. [Table 16-2]

[0196] <7-10. Manufacturing example of comparative developing roller L-1> The types and amounts of materials listed in Table 17 below were added to a reaction vessel and stirred. Next, 2-butanone (MEK) was added so that the total solids ratio was 30% by mass, and the mixture was mixed using a sand mill. Next, 2-butanone (MEK) was added to adjust the viscosity of the liquid to within the range of 6 to 10 mPa·s, producing conductive layer-forming coating liquid F-14. Conductive layer roller G-14 was produced in the same manner as conductive layer roller G-1, except that conductive layer-forming coating liquid F-1 was replaced with conductive layer-forming coating liquid F-14. [Table 17]

[0197] Next, the conductive layer roller G-1 was changed to G-14, and the same process was carried out as for the developing roller K-20. Thus, comparative developing roller L-1 was obtained. The physical properties of comparative developing roller L-1 are shown in Tables 22-1 and 22-2.

[0198] <7-11. Manufacturing example of comparative developing roller L-2> The materials shown in Table 18 below were weighed, and MEK was added to give a concentration of 5.0 mass %. The materials were thoroughly dissolved to prepare impregnation coating solution M-1. [Table 18]

[0199] Next, the comparative developing roller L-1 was oriented with its longitudinal direction vertical, its upper end was gripped, and it was immersed (dipped) in the impregnation coating liquid M-1 to impregnate the surface of the conductive layer of the comparative developing roller L-1 with the vinyl monomer and polymerization initiator. The resulting coating was air-dried at room temperature for 30 minutes, and then dried and cured for 2 hours in a hot air circulating dryer set at 120°C to obtain the comparative developing roller L-2. The physical properties of the comparative developing roller L-2 are shown in Tables 22-1 and 22-2. The second region (conductive portion) of the comparative developing roller L-2 was analyzed using a microscope IR (product name: fully automatic microscope FT-IR system: LUMOS, manufactured by Bruker Optics), and it was confirmed that the conductive portion was impregnated with a resin derived from the above vinyl monomer.

[0200] <7-12. Manufacturing examples of comparative developing rollers L-3 and L-4> Conductive layer-forming coating solutions F-15 and F-16 were prepared in the same manner as for conductive layer-forming coating solution F-1, except that the carbon black used in conductive layer-forming coating solution F-1 was changed to the materials listed in Table 19 below. Conductive layer rollers G-15 and G-16 and comparative developing rollers L-3 and L-4 were obtained in the same manner as for developing roller K-20, except that conductive layer-forming coating solution F-1 was changed to F-15 and F-16, respectively. The physical properties of comparative developing rollers L-3 and L-4 are shown in Tables 22-1 and 22-2. [Table 19]

[0201] <7-13. Manufacturing examples of comparative developing rollers L-5 to L-7> Conductive layer-forming coating solutions F-17 to F-19 were prepared in the same manner as for conductive layer-forming coating solution F-1, except that the additives used in conductive layer-forming coating solution F-1 were changed to the materials and parts by mass shown in Table 20 below. Conductive layer rollers G-17 to G-19 and comparative developing rollers L-5 to L-7 were obtained in the same manner as developing roller K-20 except for the above. The physical properties of comparative developing rollers L-5 to L-7 are shown in Tables 22-1 and 22-2. [Table 20]

[0202] <7-14. Manufacturing example of comparative developing roller L-8> Conductive layer-forming coating solution F-20 was prepared in the same manner as conductive layer-forming coating solution F-1, except that the additive used in conductive layer-forming coating solution F-1 was changed to E-5 listed in Table 21 below. Conductive layer roller G-20 and comparative developing roller L-8 were obtained in the same manner as developing roller K-20, except that conductive layer-forming coating solution F-1 was changed to F-20. The physical properties of comparative developing roller L-8 are shown in Tables 22-1 and 22-2.

[0203] <7-15. Manufacturing example of comparative developing roller L-9> [Synthesis of Additive E-6] Additive E-6, a polyetheramine, was prepared by synthesizing polyoxyethylene polyoxypropylene decyl ether, converting it to a ketone by oxidation of a secondary alcohol, and then subjecting it to reductive amination.

[0204] (Synthesis of polyoxyethylene polyoxypropylene decyl ether) 205.8 g of 1-decanol (Tokyo Chemical Industry Co., Ltd.) and 3.0 g of potassium hydroxide were placed in an autoclave equipped with a stirrer, temperature controller, and automatic feeder, and dehydration was carried out at 110°C and 1.2 kPa for 30 minutes. After completion of dehydration, the atmosphere was purged with nitrogen, and the temperature was raised to 150°C, after which 858.0 g of ethylene oxide (15 mol relative to alcohol) was added. The reaction was carried out at 150°C for 1 hour, yielding an ethylene oxide adduct with an average added mole number of 15 mol.

[0205] The resulting ethylene oxide adduct was cooled to 130°C, and then 1132.6 g of propylene oxide (relative to the alcohol: 15 mol) was added. After the addition was completed, the reaction was carried out at 130°C for 5 hours to obtain a polyoxyethylene polyoxypropylene decyl ether adduct, which was a block polymer having an average added mole number of 15 mol of ethylene oxide and 15 mol of propylene oxide.

[0206] The obtained polyoxyethylene polyoxypropylene octyldecyl adduct was cooled to 80°C and the unreacted ethylene oxide and propylene oxide were removed at 2.5 kPa for 30 minutes. Next, 6.0 g of 90% lactic acid was added to the autoclave and stirred at 80°C for 30 minutes, followed by extraction to obtain polyoxyethylene polyoxypropylene decyl ether.

[0207] [Synthesis of polyetheramine E-6] A three-necked flask was equipped with a stirrer and charged with 1688 g of polyoxyethylene polyoxypropylene decyl ether and 460 ml of acetic acid. 600 ml of a 2 mol / l aqueous solution of sodium hypochlorite was added dropwise over one hour. The reaction vessel was placed in an ice bath and cooled to a temperature within the range of 15 to 25°C. After the addition was complete, stirring was continued for one hour. Dichloromethane was added to the resulting solution, and the aqueous layer was extracted. After post-treatment and purification using a column, a compound in which the secondary alcohol was ketonized was obtained.

[0208] The mixture was cooled to 0°C in an ice bath, and 41.4 g of the resulting compound, which was ketone from a secondary alcohol, was added to 250 ml of a methanol-acetic acid mixed solution (volume ratio 10:1), followed by 2.7 g of 2-picoline borane. The ice bath was removed, and the mixture was stirred overnight at room temperature in an open system. After concentration, the mixture was cooled to 0°C, and 360 ml of 35% aqueous hydrochloric acid was added, followed by stirring at room temperature for 2 hours. Aqueous sodium hydroxide was added to make the mixture basic, and the aqueous layer was extracted with dichloromethane, post-treated, and purified using a column to obtain polyetheramine E-6. The structure of R61 of E-6 and the values ​​of v and w are shown in Table 21.

[0209] Conductive layer-forming coating solution F-21 was prepared in the same manner as conductive layer-forming coating solution F-1, except that the additive used in conductive layer-forming coating solution F-1 was changed to E-6 listed in Table 21 below. Conductive layer roller G-21 and comparative developing roller L-9 were obtained in the same manner as developing roller K-20, except that conductive layer-forming coating solution F-1 was changed to F-21. The physical properties of comparative developing roller L-9 are shown in Tables 22-1 and 22-2.

[0210] <7-16. Manufacturing example of comparative developing roller L-10> [Synthesis of Additive E-7] 315.2 g of 1-hexadecanol (Tokyo Chemical Industry Co., Ltd.) and 3.0 g of potassium hydroxide were placed in an autoclave equipped with a stirrer, temperature controller, and automatic feeder, and dehydration was carried out at 110°C and 1.2 kPa for 30 minutes. After completion of dehydration, the atmosphere was purged with nitrogen, and the temperature was raised to 150°C, after which 858.0 g of ethylene oxide (15 mol relative to alcohol) was added. The reaction was carried out at 150°C for 1 hour, yielding an ethylene oxide adduct with an average added mole number of 15 mol.

[0211] 90.2 g of the resulting ethylene oxide adduct was mixed with 510 ml of 1 mol / L aqueous sodium hydroxide, and 71.1 g of potassium permanganate was added and stirred at room temperature for 6 hours. Then, 760 ml of 2-propanol was added and stirred for 1 hour to quench the excess potassium permanganate. The by-product manganese oxide was then filtered. The aqueous layer was extracted with dichloromethane and purified to obtain polyoxyethylene methyl ether acetic acid E-7. The structure of R71 and the value of x for E-7 are shown in Table 21.

[0212] Conductive layer-forming coating solution F-22 was prepared in the same manner as conductive layer-forming coating solution F-1, except that the additive used in conductive layer-forming coating solution F-1 was changed to E-7 listed in Table 21 below. Conductive layer roller G-22 and comparative developing roller L-10 were obtained in the same manner as developing roller K-20, except that conductive layer-forming coating solution F-1 was changed to F-22. The physical properties of comparative developing roller L-10 are shown in Tables 22-1 and 22-2. [Table 21] [Table 22-1] Regarding the impedance measurement of the comparative developing rollers L-1 to L-10, the minimum impedance value was 1.0 x 10 0 Hz~1.0×10 1 Indicates the minimum impedance value in Hz. [Table 22-2]

[0213] 8. Working Example <8-1. Example 1> The evaluation methods and evaluation criteria of the present disclosure will be described below. The electrophotographic image forming apparatus used was a modified version of a commercially available laser printer, the LBP-7600C (manufactured by Canon Inc.). The configuration of the modified apparatus is shown in Figure 10. Modifications included connecting to power supplies 14C and 15C as well as an external high-voltage power supply 20C, allowing any potential difference to be set between the developing blade and developing roller, and setting the output rate per unit time to 50 sheets / minute for A4 size paper in order to evaluate a high-speed process.

[0214] The process cartridge used was a commercially available toner cartridge 318 (cyan) (manufactured by Canon Inc.), and the developing roller was replaced with the developing roller K-1 of the present disclosure. Furthermore, to reduce the drive torque, the gear of the toner supply roller was removed from the process cartridge. By removing the gear, the toner supply roller rotates in a driven manner relative to the developing roller, reducing the drive torque, but also reducing the amount of toner supplied to the developing roller and the toner chargeability after printing a high-density image. The yellow, magenta and black cartridges were inserted into each of the yellow, magenta and black stations, with the product toner removed and the remaining toner amount detection mechanism disabled, and the evaluation was carried out.

[0215] <Evaluation of toner transport performance after long-term storage in a high-temperature, high-humidity environment> The process cartridge equipped with the developing roller K-1 was left standing for 30 days in an environment with a temperature of 40°C and a relative humidity of 95%. This was the condition in which the difference in humidity between the outside and inside of the process cartridge was sufficiently eliminated, and the entire developing roller absorbed moisture uniformly. Next, the process cartridge was removed from the above environment and immediately moved to an environment of 30°C temperature and 80% relative humidity, and left to stand for another 24 hours. At the same time, the modified laser printer and the evaluation paper (GFC81 (Canon) A4: 81.4 g / m 2 ) was left standing in the same environment for 24 hours.

[0216] The process cartridge was then loaded into a modified laser printer, the potential difference between the developing blade and the developing roller was set to -300 V, and one all-black image was printed. The density of the all-black image was measured using a spectrodensitometer (trade name: X-Rite504, S.D.G.). The image density difference was calculated by dividing the arithmetic mean value of the image densities at five points within 20.0 mm from the trailing edge in the image transport direction by the arithmetic mean value of the image densities at five points within 20.0 mm from the leading edge in the image transport direction. In order to reduce the drive torque of the process cartridge, the gear of the toner supply roller has been removed, which causes charge to leak from the insulating part of the developing roller to the conductive part, resulting in insufficient toner transport force and a decrease in image density towards the rear edge of the image. Note that 20.0 mm in the image transport direction is the width within one revolution of the developing roller. The obtained results were evaluated based on the following evaluation criteria. The evaluation results are shown in Table 23 below. Rank A: Image density difference is less than 0.10 Rank B: Image density difference is 0.10 or more and less than 0.20 Rank C: Image density difference is 0.20 or more and less than 0.30 Rank D: Image density difference is 0.30 or more

[0217] <Evaluation of fog immediately after printing a high-density image under high-temperature and high-humidity conditions> After the evaluation of the toner transport property under the high temperature and high humidity environment, one image was output under the same environment in which the area 150.0 mm from the leading edge in the image transport direction was all black and the rest was all white. Using a reflection densitometer (product name: TC-6DS / A, manufactured by Tokyo Denshoku Technology Center Co., Ltd.), the reflection density R1 of the evaluation paper before image formation and the reflection density R2 of the all-white area within 20.0 mm in the image transport direction from the rear edge of the all-black area (i.e., 150.0 mm to 170.0 mm from the leading edge in the image transport direction) were measured, and the increase in reflection density (R2 - R1) was taken as the fog value. The reflection density R1 of the evaluation paper before image formation was the arithmetic mean of measurements taken at five points across the entire evaluation paper, and the reflection density R2 of the all-white area was the maximum value of measurements taken at five points across the same area. The smaller the fog value, the better. The obtained results were evaluated based on the following evaluation criteria. The evaluation results are shown in Table 23 below. Rank A: Fog value less than 1.0% Rank B: Fog value is 1.0% or more and less than 2.0% Rank C: Fog value is 2.0% or more and less than 3.0% Rank D: Fog value is 3.0% or more

[0218] <Evaluation of toner transportability after continuous paper feed under low temperature and low humidity environment> As with the above process cartridge, the gear of the toner supply roller was removed, and a process cartridge with the developing roller K-1 attached was prepared. Next, the process cartridge, the modified laser printer, and the evaluation paper (GFC81 (Canon) A4: 81.4 g / m 2 ) was left to stand for 24 hours in an environment of 15°C and 10% relative humidity. The process cartridge was then loaded into a modified laser printer, the potential difference between the developing blade and the developing roller was set to -300 V, and 1,000 images with a printing rate of 2% and one all-black image were printed in succession in this order.

[0219] The density of the obtained all-black image was measured using a spectrodensitometer (product name: X-Rite504, manufactured by S.D.G. Co., Ltd.). The image density difference was calculated by dividing the arithmetic mean value of the image densities at five points within 20.0 mm from the leading edge of the image in the conveying direction by the arithmetic mean value of the image densities at five points within 20.0 mm from the trailing edge of the image in the conveying direction. When the toner supply roller gear is removed and the drive torque of the process cartridge is reduced, the toner transport force of the developing roller becomes insufficient, and the image density decreases toward the trailing edge of the image.Since the toner supply roller gear is removed in order to reduce the drive torque of the process cartridge, when the conductive part of the developing roller is charged up due to continuous paper feed and the potential difference with the insulating part decreases, the toner transport force becomes insufficient, and the image density decreases toward the trailing edge of the image. The results obtained were evaluated based on the following evaluation criteria, and the evaluation results are shown in Table 23 below. Rank A: Image density difference is less than 0.10 Rank B: Image density difference is 0.10 or more and less than 0.20 Rank C: Image density difference is 0.20 or more and less than 0.30 Rank D: Image density difference is 0.30 or more

[0220] <8-2. Examples 2 to 20 and Comparative Examples 1 to 10> Except for using developing rollers K-2 to K-20 and comparative developing rollers L1 to L10, evaluation was carried out in the same manner as in Example 1. The evaluation results are shown in Table 23 below. [Table 23]

[0221] From the above results, by using the developing roller of the present disclosure, the process speed is fast, and further Even when the toner conveyance device is used in various environments for a long period of time with the driving torque reduced, it is possible to prevent toner conveyance failure.

[0222] The present disclosure includes the following configurations. (Configuration 1) a substrate having an electrically conductive outer surface; a conductive layer on the outer surface of the substrate, the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region; the first region and the second region are disposed adjacent to each other; the first region is disposed on an outer surface of the conductive layer; A metal film was provided directly on the outer surface of the developing roller, and a DC voltage of 50 V was applied between the outer surface of the substrate and the metal film in an environment of a temperature of 23°C and a relative humidity of 50%, while an AC voltage of 50 V amplitude and a frequency of 1.0 × 10 -1 ~1.0×10 5 When applied while changing between Hz, the frequency is 1.0 × 10 0 ~1.0×10 1 Impedance at Hz is 1.0×10 6 is greater than or equal to Ω, In an environment of 23°C temperature and 50% relative humidity, a corona discharger having a grid portion with a width of 3.0 mm was placed so that the distance between the grid portion and the outer surface of the developing roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the developing roller, a voltage of 8 kV was applied to the grid portion, and the corona discharger was moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec to charge the outer surface of the developing roller, and the potential of the outer surface was measured t seconds after the grid portion had passed. The potential at t=0.06 [seconds] is V INI [V], The change in potential in the range of 30.00≦t≦100.00 was fitted to the following equation (X′) by the least squares method, and V 0,1 When [V] and τ1 [seconds] are calculated, when t = 0.06 [seconds] is substituted into the formula (X'), the value of the potential V1(t) is V1 [V], INI - a developing roller characterized in that V1 is less than 20.0 V; V1(t)=V 0,1 exp(-t / τ1) (X'). (Configuration 2) 2. The developing roller according to claim 1, wherein τ1 is 60.0 seconds or longer. (Configuration 3) 3. The developing roller according to claim 1, wherein V1 is 5.0 V or more. (Configuration 4) In an environment of a temperature of 23°C and a relative humidity of 50%, a corona discharger having a grid portion with a width of 3.0 mm was arranged so that the distance between the grid portion and the outer surface of the developing roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the developing roller, a voltage of 8 kV was applied to the grid portion, and the corona discharger was moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec to charge the outer surface of the developing roller, and the potential of the outer surface was measured t seconds after the grid portion had passed. The change in potential in the range of 0.06≦t≦100.00 was fitted to the following equation (Y) by the least squares method, and V 0,2 When [V] and τ2 [seconds] are calculated, The developing roller according to any one of configurations 1 to 3, wherein τ2 is 6.0 seconds or less: V(t)=V1(t)+V2(t) (Y). (In formula (Y), V2(t)=V 0,2 exp(-t / τ2) (Z)) (Configuration 5) The above V INI 5. The developing roller according to any one of configurations 1 to 4, wherein −V1 is 10.0 V or less. (Configuration 6) When a square observation area with a side of 300 μm is placed on the outer surface of the developing roller so that the axial direction of the developing roller and one side of the observation area are parallel, the surface of the square observation area 6. The developing roller according to any one of configurations 1 to 5, wherein the ratio of the total area of ​​the first region to the total area is 10 to 60 area %. (Configuration 7) 7. The developing roller according to any one of configurations 1 to 6, wherein the conductive layer contains polyurethane. (Configuration 8) 8. The developing roller according to any one of configurations 1 to 7, wherein the conductive layer contains polyurethane having a polycarbonate structure. (Configuration 9) The developing roller according to Configuration 8, wherein the polyurethane satisfies at least two of the following (A), (B), and (C): (A) The polyurethane has a structure represented by the following structural formula (1) in its molecule: (B) The polyurethane has, in its molecule, either one or both of a structure represented by the following structural formula (2) and a structure represented by the following structural formula (3): (C) The polyurethane has a structure represented by the following structural formula (4) in the molecule. TIFF2026042383000032.tif102170 [In structural formula (1), R11, R12, and R13 represent divalent hydrocarbon groups having 3 to 9 carbon atoms. However, R11 and R12 are different from each other, and R13 is the same as at least one selected from the group consisting of R11 and R12. m and n represent the average number of moles added, and each independently represents a number of 1.0 or more. In the structural formula (2), o and p are the average number of moles added, and each independently represents a number of 1.0 or more. In structural formula (3), R31 and R32 each independently represent a divalent hydrocarbon group having 3 to 8 carbon atoms, and q and r each independently represent the average number of moles added and are each a number of 1.0 or greater. In structural formula (4), R41 represents a divalent hydrocarbon group having 6 to 9 carbon atoms, and s represents the average number of moles added and is a number of 1.0 or more. (Configuration 10) The developing roller according to any one of Configurations 1 to 9, wherein the conductive layer contains carbon black. (Configuration 11) The developing roller according to any one of configurations 1 to 10, wherein the conductive layer contains at least one selected from the group consisting of a compound represented by the following structural formula (5), a compound represented by the following structural formula (6), and a compound represented by the following structural formula (7): TIFF2026042383000033.tif77170 [In structural formula (5), R51 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms. t and u represent the average number of moles added, and each independently represents a number of 1.0 or more.] In structural formula (6), R61 represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, v and w represent the average number of moles added, and each independently represents a number of 1.0 or more. In structural formula (7), R71 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, and x represents the average number of moles added and is a number of 1.0 or more. (Configuration 12) the arithmetic mean value Rc of the equivalent circle diameter of the carbon black in the conductive layer is 60.0 nm or less, 11. The developing roller according to claim 10, wherein σc / Rc is 0.000 to 0.650, where σc is the standard deviation of the equivalent circle diameter of the carbon black. (Configuration 13) the arithmetic mean value d of the distance between wall surfaces of the carbon black in the conductive layer is 80.0 to 150.0 nm; 13. The developing roller according to claim 10 or 12, wherein σd / d is 0.000 to 0.600, where σd is the standard deviation of the distance between the wall surfaces. (Configuration 14) 14. The developing roller according to any one of Configurations 10, 12, and 13, wherein the number average particle diameter of the primary particles of the carbon black in the conductive layer is 30 nm or less. (Configuration 15) the DBP absorption of the carbon black in the conductive layer is 90 ml / 100 g or less; 15. The developing roller according to any one of configurations 10 and 12 to 14, wherein the carbon black has a pH of 4.0 or less. (Configuration 16) the first region comprises at least one polycarbonate; The developing roller according to any one of Configurations 1 to 15, wherein the at least one polycarbonate has a structure represented by the following structural formula (8): [In the structural formula (8), R81 to R88 each independently represent a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R89 and R90 each independently represent a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms, or R89 and R90 are an atomic group necessary for R89 ​​and R90 to bond with each other to form an alicyclic structure having 6 to 12 carbon atoms, However, the structural formula (8) satisfies at least one of the following conditions 1 and 2: Satisfy the following conditions: ·Condition 1 At least one selected from the group consisting of R81 to R88 is the alkyl group having 1 to 9 carbon atoms or the aryl group having 6 to 10 carbon atoms. ·Condition 2 At least one selected from the group consisting of R89 and R90 is a linear or branched alkyl group having 2 or more carbon atoms, or an aryl group having 6 to 10 carbon atoms. TIFF2026042383000034.tif45170 (configuration 17) 17. The developing roller according to claim 16, wherein the at least one polycarbonate has a structure represented by the following structural formula (9): TIFF2026042383000035.tif146170 (configuration 18) The at least one polycarbonate has at least one structure selected from the group consisting of a structure represented by the following structural formula (10) and a structure represented by the following structural formula (11): 18. The developing roller according to configuration 16 or 17. TIFF2026042383000036.tif146170(Configuration 19) 19. A process cartridge configured to be detachably attached to the main body of an electrophotographic image forming apparatus, the process cartridge comprising a developing means, the developing means having the developing roller according to any one of configurations 1 to 18. (Configuration 20) 19. An electrophotographic image forming apparatus comprising a developing means, wherein the developing means has the developing roller according to any one of Configurations 1 to 18.

Claims

1. a substrate having an electrically conductive outer surface; a conductive layer on the outer surface of the substrate, the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region; the first region and the second region are disposed adjacent to each other; the first region is disposed on an outer surface of the conductive layer; A metal film was provided directly on the outer surface of the developing roller, and a DC voltage of 50 V was applied between the outer surface of the substrate and the metal film in an environment of a temperature of 23° C. and a relative humidity of 50%, while an AC voltage of 50 V amplitude and a frequency of 1.0×10 －１ ~1.0 x 10 ５ When applied while changing between 1.0 x 10 Hz, ０ ~1.0 x 10 １ Impedance at Hz is 1.0 x 10 ６ is greater than or equal to Ω, In an environment of a temperature of 23°C and a relative humidity of 50%, a corona discharger having a grid portion with a width of 3.0 mm was arranged so that the distance between the grid portion and the outer surface of the developing roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the developing roller, a voltage of 8 kV was applied to the grid portion, and the corona discharger was moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec to charge the outer surface of the developing roller, and the potential of the outer surface was measured t seconds after the grid portion had passed. The potential at t = 0.06 [seconds] is V ＩＮＩ [V], The change in potential in the range of 30.00≦t≦100.00 was fitted to the following equation (X′) by the least squares method, and V ０，１ [V] and τ １ When t = 0.06 [seconds] is calculated, the potential V when t = 0.06 [seconds] is substituted into the formula (X') １ (t) value V １ When [V] is set, V ＩＮＩ -V １ a developing roller having a voltage of less than 20.0 V: V １ (t)=V ０，１ exp(-t / τ １ ) (X’)。

2. The τ １ 2. The developing roller according to claim 1, wherein the time is 60.0 seconds or more.

3. The V １ 2. The developing roller according to claim 1, wherein the voltage Vcc is 5.0 V or more.

4. In an environment of a temperature of 23°C and a relative humidity of 50%, a corona discharger having a grid portion with a width of 3.0 mm was arranged so that the distance between the grid portion and the outer surface of the developing roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the developing roller, a voltage of 8 kV was applied to the grid portion, and the corona discharger was moved relatively along the axial direction of the developing roller at a speed of 400 mm / sec to charge the outer surface of the developing roller, and the potential of the outer surface was measured t seconds after the grid portion had passed. The change in potential in the range of 0.06≦t≦100.00 was fitted to the following equation (Y) by the least squares method, and V ０，２ [V] and τ ２ When calculating [seconds], The τ ２ 2. The developing roller of claim 1, wherein the time required for development is 6.0 seconds or less. V(t)=V １ (t)+V ２ (t) (Y)。 (In formula (Y), V ２ (t) = V ０，２ exp(−t / τ ２ ) (Z))

5. The V ＩＮＩ -V １ 2. The developing roller according to claim 1, wherein the voltage Vcc is 10.0 V or less.

6. 2. The developing roller according to claim 1, wherein, when a square observation area with sides of 300 μm is placed on the outer surface of the developing roller such that one side of the observation area is parallel to the axial direction of the developing roller, the ratio of the total area of ​​the first area to the area of ​​the square observation area is 10 to 60 area %.

7. The developer roller of claim 1 , wherein the conductive layer comprises polyurethane.

8. 10. The developer roller of claim 1, wherein said conductive layer comprises a polyurethane having a polycarbonate structure.

9. 9. The developing roller according to claim 8, wherein the polyurethane satisfies at least two of the following (A), (B), and (C): (A) The polyurethane has a structure represented by the following structural formula (1) in the molecule: (B) The polyurethane has, in its molecule, either one or both of a structure represented by the following structural formula (2) and a structure represented by the following structural formula (3): (C) The polyurethane has a structure represented by the following structural formula (4) in the molecule. In structural formula (1), R11, R12, and R13 represent divalent hydrocarbon groups having 3 to 9 carbon atoms. However, R11 and R12 are different from each other, and R13 is the same as at least one selected from the group consisting of R11 and R12. m and n represent the average number of moles added, and each independently represents a number of 1.0 or more. In the structural formula (2), o and p are the average number of moles added, and each independently represents a number of 1.0 or more. In structural formula (3), R31 and R32 each independently represent a divalent hydrocarbon group having 3 to 8 carbon atoms. q and r each independently represent the average number of moles added and are each a number of 1.0 or greater. In structural formula (4), R41 represents a divalent hydrocarbon group having 6 to 9 carbon atoms, and s represents the average number of moles added and is a number of 1.0 or more.

10. The developer roller of claim 1 wherein the conductive layer comprises carbon black.

11. 8. The developing roller according to claim 7, wherein the conductive layer comprises at least one selected from the group consisting of a compound represented by the following structural formula (5), a compound represented by the following structural formula (6), and a compound represented by the following structural formula (7): In structural formula (5), R51 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms. t and u represent the average number of moles added, and each independently represents a number of 1.0 or more. In structural formula (6), R61 represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, v and w represent the average number of moles added, and each independently represents a number of 1.0 or more. In structural formula (7), R71 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, and x represents the average number of moles added and is a number of 1.0 or more.

12. the arithmetic mean value Rc of the equivalent circle diameter of the carbon black in the conductive layer is 60.0 nm or less, 11. The developing roller according to claim 10, wherein σc / Rc is 0.000 to 0.650, where σc is the standard deviation of the equivalent circle diameter of the carbon black.

13. an arithmetic mean value d of the distance between wall surfaces of the carbon black in the conductive layer is 80.0 to 150.0 nm; 11. The developing roller according to claim 10, wherein σd / d is 0.000 to 0.600, where σd is the standard deviation of the distance between the wall surfaces.

14. 11. The developing roller according to claim 10, wherein the number average particle diameter of the primary particles of said carbon black in said conductive layer is 30 nm or less.

15. the DBP absorption of the carbon black in the conductive layer is 90 ml / 100 g or less; 11. The developing roller according to claim 10, wherein the carbon black has a pH of 4.0 or less.

16. the first region comprises at least one polycarbonate; 2. The developing roller of claim 1, wherein the at least one polycarbonate has a structure represented by the following structural formula (8): [In structural formula (8), R81 to R88 each independently represent a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R89 and R90 each independently represent a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms, or R89 and R90 represent an atomic group necessary for R89 ​​and R90 to be bonded to each other to form an alicyclic structure having 6 to 12 carbon atoms, However, the structural formula (8) satisfies at least one condition selected from the group consisting of the following conditions 1 and 2: ・Condition 1 At least one selected from the group consisting of R81 to R88 is the alkyl group having 1 to 9 carbon atoms or the aryl group having 6 to 10 carbon atoms. ・Condition 2 At least one selected from the group consisting of R89 and R90 is a linear or branched alkyl group having 2 or more carbon atoms, or an aryl group having 6 to 10 carbon atoms.

17. 17. The developer roller of claim 16, wherein the at least one polycarbonate has a structure represented by the following structural formula (9):

18. 17. The developing roller according to claim 16, wherein the at least one polycarbonate has at least one structure selected from the group consisting of a structure represented by the following structural formula (10) and a structure represented by the following structural formula (11):

19. A process cartridge configured to be detachably mountable to a main body of an electrophotographic image forming apparatus, the process cartridge comprising a developing means, the developing means having the developing roller according to any one of claims 1 to 18.

20. 19. An electrophotographic image forming apparatus comprising a developing means, wherein the developing means has the developing roller according to any one of claims 1 to 18.

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