Developing device, process cartridge and electrophotographic image forming apparatus

Abstract

A developing device that has good injection charging characteristics regardless of the environment and maintains stable charging even after long-term use. [Solution] A developing device having a developer and a developer carrier that carries the developer, wherein the developer is a toner having toner particles and an external additive, the external additive includes fine particles A and fine particles B, the fine particles A being at least one fine particle selected from the group consisting of silica fine particles and silicone fine particles, and the fine particles B being a specific conductive fine particle, the developer carrier is a developing roller having a base having a conductive outer surface and a resin layer on the outer surface of the base, and the maximum values ​​of the impedance and potential of the outer surface of the developing roller are within specific ranges.

Description

[Technical Field]

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

[0002] In recent years, image forming apparatuses such as copiers and printers are required to have high image quality, high speed, and high stability, while at the same time, they are also required to be compact and easy to maintain. In these respects, a one-component development method is preferably used.

[0003] Various types of developing devices using one-component development have been proposed. An example is as follows: In a developing device, toner, which is a one-component developer, is contained in a developing container. The toner is carried on a developing roller that is rotatably fixed to the developing container, and a toner layer of uniform thickness is formed by a toner regulating member. The developing roller carrying the toner layer is brought close to or into contact with a photosensitive member, and a developing bias voltage, for example, is applied to the developing roller, thereby generating a potential difference between the electrostatic image on the photosensitive member and the developing roller. This causes the toner to move to the electrostatic image, thereby developing it.

[0004] To obtain good image quality, uniform toner development is necessary, and toner on the developing roller must be uniformly charged to the appropriate amount. The toner is typically charged by frictional charging, which occurs when the toner comes into contact with a toner regulating member or the developing roller. However, frictional charging can result in uneven rubbing between the toner and the contacting member, resulting in overcharged and undercharged toner. This is because the charge generated by frictional charging occurs only at the point where the toner comes into contact with the contacting member.

[0005] In addition, triboelectric charging is greatly affected by the rolling of toner. Toner that has been used for a long time is prone to deforming due to stress in the developing device. Deformed toner is more difficult to roll than toner that has not deformed. As a result, there are cases where the toner does not obtain a sufficient amount of charge after long-term use.

[0006] To solve these problems in the friction charging process, an injection charging process is being investigated. The injection charging process is a process in which the toner is charged by injecting electric charge due to the potential difference between the toner and the charging member. In this case, not only the portion in contact with the charging member but also the entire toner can be uniformly charged by discharge through a minute gap in the vicinity of the contact portion with the charging member.

[0007] In addition, the injection charging process allows the amount of charge to be controlled arbitrarily by changing the potential difference, making it easy to meet the charge amount required by the system. Furthermore, injection charging is not easily affected by humidity, making it possible to suppress changes in the amount of charge due to the environment.

[0008] Patent Document 1 proposes a toner configuration that adjusts the volume resistance and capacitance of the toner by fixing medium-resistivity metal oxide particles to the toner surface, thereby enabling contact charging and charge injection charging to be performed simultaneously. Patent Document 2 gives an example of a toner with a large amount of titania added externally as a toner that can be used in the injection charging process. Patent Document 3 proposes a developing device that adjusts the volume resistance of the toner and the volume resistance and capacitance of the toner carrier, enabling charge injection charging to be performed simultaneously. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-058874 [Patent Document 2] Patent Publication No. 2021-021791 [Patent Document 3] Japanese Patent Publication No. 2022-080159 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in Patent Document 1, the conductivity of the raw materials is low, so it is necessary to add a large amount of material to obtain sufficient injection properties. According to the inventors' studies, such toner forms a conductive path at the toner interface, causing the injected charge to leak from the developing roller or the like via the interface. In other words, although it has the ability to inject a certain amount of charge, it has a poor ability to retain the charge, resulting in a toner with low injection charge properties. As a result, sufficient charge properties cannot be obtained, and problems such as fogging and toner scattering are likely to occur.

[0011] In addition, in a system that uses an injection charging process, the characteristics of the developing roller that is combined with the toner are also important. The developing roller that is combined with the toner in Patent Document 1 is coated with an elastic rubber layer, and has an electrical resistance of 10 3 ~10 10 It is stated that the electrical resistance is set to Ω, but no details are given.

[0012] 10 5 When a developing roller with a relatively low resistance of Ω or less is used, the toner charge obtained by contact charging or charge injection leaks through the developing roller, easily causing problems such as fogging and toner scattering. In order to maintain the charge of the toner on the developing roller, it is necessary to increase the resistance of the developing roller, but in this case, charge buildup on the surface of the developing roller becomes significant, easily causing problems such as fogging and poor regulation.

[0013] Patent Document 2 also discloses that high charge injection properties can be obtained by incorporating a large amount of a medium-resistivity external additive such as titania into the toner surface. However, as in Patent Document 1, it is difficult to achieve both charge injection properties and charge retention properties due to the formation of a conductive path, and sufficient charging properties cannot be obtained, making it more likely to cause problems such as fogging and toner scattering.

[0014] In Patent Document 3, the difference in the time constant between the toner and the toner carrier is designed to be a desired value, thereby causing a phenomenon in which charge accumulates at this interface (interfacial polarization phenomenon), and allowing charge to be held at the interface between the toner and the toner carrier. However, because the toner's charge injection ability is insufficient, the toner does not obtain a sufficient amount of charge due to the influence of deformed toner accumulated inside the developing device in the latter half of long-term use, and problems such as fogging and toner scattering are likely to occur.

[0015] As described above, Patent Documents 1 and 2 attempt to improve the charge injection charging property of the toner, but both of them are insufficient in charge injection property and charge retention property, and there is still room for improvement. Also, Patent Document 3 focuses on the time constant difference from the viewpoint of the combination of the toner and the developing roller, and improves the charge retention property, but there is still room for further study regarding the charge injection of the toner. The present disclosure provides a developing device, a process cartridge, and an electrophotographic image forming apparatus that have good injection charging characteristics regardless of the environment and are stable in charging even when used for a long period of time. [Means for solving the problem]

[0016] The present disclosure provides a developing device having a developer and a developer carrier that carries the developer, the developer is a toner having toner particles and an external additive; The external additive contains fine particles A and fine particles B, the fine particles A are at least one fine particle selected from the group consisting of silica fine particles and silicone fine particles, The fine particles B are made of antimony-tin-based oxide-titanium-based oxide, antimony-titanium-based at least one fine particle selected from the group consisting of oxides, antimony-tin oxides, indium-tin oxides, indium-titanium oxides, niobium-tin oxides, niobium-titanium oxides, and zinc oxide; the developer carrier is a developing roller having a substrate with a conductive outer surface and a resin layer on the outer surface of the substrate, 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%. 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 1.00 x 10 6 is greater than or equal to Ω, and The developing device is configured such that, in an environment of a temperature of 23°C and a relative humidity of 50%, a corona discharger having a 3.0 mm wide grid portion is positioned so that the distance between the grid portion and the outer surface of the developing roller is 1.0 mm and the direction of the width of the grid portion coincides with the axial direction of the developing roller, a voltage of 8 kV is applied to the grid portion, and the corona discharger is 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 maximum value of the potential of the outer surface measured 0.06 seconds after the grid portion has passed is less than 20.0 V.

[0017] The present disclosure also provides a process cartridge configured to be detachably attached to a main body of an electrophotographic image forming apparatus, The present invention relates to a process cartridge having the above-mentioned developing device. The present disclosure also relates to an electrophotographic image forming apparatus equipped with the above-described developing device. [Effects of the Invention]

[0018] According to the present disclosure, it is possible to provide a developing device, a process cartridge, and an electrophotographic image forming apparatus that have good injection charging characteristics regardless of the environment and are stable in charging even when used for a long period of time. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of a 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. [Figure 11] An example of a Faraday cage [Figure 12] An example of a work function measurement curve DETAILED DESCRIPTION OF THE INVENTION

[0020] In the present disclosure, the expressions "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, for example, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means 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. is.

[0021] As mentioned above, a large amount of medium-resistivity external additive is required to achieve high charge injection. The reason for this is thought to be that the conductivity of the material in the charge injection area is low, so a small amount does not result in a sufficient amount of charge injection. Therefore, a large amount of medium-resistivity external additive is required to increase the amount of charge injection. As a result, the conductivity of the interface formed between toner particles (hereinafter referred to as the toner interface) increases. When the conductivity of the toner interface increases, charge leakage from the toner is promoted. As a result, the charge obtained by injection cannot be retained on the toner, and leaks out, resulting in charge loss.

[0022] Therefore, the present inventors have considered that the injection charging property of the toner can be improved by separating the charge injection property from the charge retention property. Specifically, we attempted to prevent charge leakage from the toner by combining a toner with high charge injection properties and reduced charge leakage with a developing roller with high resistance, while injecting charge into the toner. In particular, charge leakage from the toner can be classified into two phenomena: one related to the toner due to the conductivity of the toner surface, and the other related to the developing roller, where the toner charge leaks from the contact point due to contact between the rolling toner and the developing roller.

[0023] Therefore, we investigated the combination of a developing roller with a surface layer formed using polyurethane as a high-resistance developing roller with toner that has charge injection properties and suppresses charge leakage. As a result, we confirmed that good injection charging properties could be obtained by using fine particles with higher conductivity than the commonly used medium-resistivity external additives for toner. However, we also found that another problem arose. The electrical resistance of the developing roller surface layer was too high, which caused a new problem: excessively charged toner adhered to the surface of the developing roller. As a result, we found that injection charging properties could not be maintained throughout long-term use.

[0024] Therefore, the present inventors have investigated the possibility of removing excess charge from overcharged toner by incorporating a conductive filler into the surface layer of a developing roller. For example, they have investigated incorporating a conductive filler into the surface layer, but have recognized a new problem: it is difficult to disperse the conductive filler sufficiently to remove excess charge. If the conductive filler is not sufficiently dispersible, a conductive path may be formed by the conductive filler in the surface layer, resulting in charge leakage, or conversely, the conductive filler may not be effective enough in removing excess charge.

[0025] In other words, the surface layer of the developing roller must be able to achieve a high level of resolution for the conflicting goals of preventing charge leakage from the toner and removing excess charge from overcharged toner. To this end, the inventors recognized that it was necessary to develop a new surface layer that could remove excess charge while maintaining high electrical resistance of the surface layer. Based on this recognition, the inventors conducted further research.

[0026] As a result, the inventors discovered that a developing roller having a substrate with a conductive outer surface and a resin layer on the outer surface of the substrate can obtain a developing system with stable charging when combined with a toner having charge injection properties by satisfying the following two requirements:

[0027] 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 The frequency is changed between 1.0×10 Hz. 0 ~1.0×10 1 Impedance at Hz is 1.00×10 6 It is greater than or equal to Ω.

[0028] Requirement (2) In an environment of 23°C temperature and 50% relative humidity, a corona charger with a 3.0 mm wide grid was placed so that the distance between the grid and the outer surface of the developing roller was 1.0 mm and the width direction of the grid coincided with the axial direction of the developing roller. A voltage of 8 kV was applied to the grid, and the corona charger 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 0.06 seconds after passing the grid. The maximum value of the potential at this time was less than 20.0 V.

[0029] 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 that indicates the charge leakage from the toner to the developing roller. 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 FIG. 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. This shows that when it comes to charge leakage, it is necessary to consider not only the resistance component of the developing roller but also the effect 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 accumulates in the capacitance component and the steady state dominated by the resistance component has a large effect on charge leakage.

[0030] 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.

[0031] 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.

[0032] 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 toner to the developing roller. 0 ~1.0×10 1 Impedance at Hz is 1.00×10 6 If the resistance is Ω or more, the charge leakage is low, and under a high blade bias, charge leakage from the toner to the developing roller is suppressed, and a decrease in the charge amount of the toner can be prevented.

[0033] The frequency is 1.0 x 10 0 ~1.0×10 1 The impedance in Hz is preferably is 1.40 x 10 6The higher the impedance value, the better. There is no particular upper limit, but for example, 5.00×10 7 Examples include Ω and below. Also, the frequency is 1.0×10 0 ~1.0×10 1 The minimum impedance in Hz is preferably 1.40 x 10 6 Ω or more, more preferably 2.00×10 6 Ω or more, particularly preferably 3.00×10 6 Ω or more, more preferably 5.00×10 6 The preferred range of the impedance is 1.00×10 6 Ω or more 5.00×10 7 Ω or less, preferably 1.40×10 6 Ω or more 5.00×10 7 Ω or less, more preferably 2.00×10 6 Ω or more 5.00×10 7 Ω or less, particularly preferably 3.00 × 10 6 Ω or more 5.00×10 7 Ω or less, more preferably 5.00×10 6 Ω or more 5.00×10 7 It is less than Ω.

[0034] <Technical significance of requirement (2)> Requirement (2) specifies the surface potential of the developing roller. The surface potential of the developing roller indicates the residual charge on the surface of the developing roller, and is a physical property that indicates the degree of excessive charge (charge-up) of the toner. If the surface potential is high, the charge of the excessively charged toner cannot be properly controlled, which may result in a decrease in image density or the occurrence of fogging. There are two possible causes of a decrease in image density. The first is that excessively charged toner adheres electrically to the surface of the developing roller, making it impossible to charge the next toner transported to the same location. The second is that after the toner is removed from the surface of the developing roller, residual charge remains on the surface of the developing roller, making it impossible to charge the next toner transported to the same location.

[0035] In this disclosure, a voltage of 8 kV is applied to the grid portion, and a corona discharger is moved relative to the developing roller axially at a speed of 400 mm / s. The potential of the outer surface of the developing roller is measured 0.06 seconds after the grid portion of the corona discharger passes. If the maximum value of the outer surface potential is less than 20.0 V, the occurrence of image defects due to excessive toner charging can be suppressed even in electrophotographic image forming devices with high process speeds, where the time it takes for toner charged by the developing blade to be transported to the photoconductor is shorter. Note that the measurement 0.06 seconds after the grid portion of the corona discharger passes simulates a model with a high process speed.

[0036] The maximum value of the potential of the outer surface is preferably 15.0 V or less, and more preferably 10.0 V or less. The lower the maximum value of the potential of the outer surface, the better, and there is no particular lower limit. A preferred range for the maximum potential of the outer surface is, for example, 0 V or more and less than 20.0 V, particularly 0 V or more and 15.0 V or less, and further preferably 0 V or more and 10.0 V or less.

[0037] By satisfying the above requirements (1) and (2), the developing roller can both suppress charge leakage from the toner and prevent excessive charging on the surface of the developing roller. As a result, the charge injected into the toner is properly retained on the toner, enabling efficient charge injection into the toner. From the above, it is possible to obtain a development system with stable charging that can be applied even in high-speed development processes.

[0038] There are no particular limitations on the means for satisfying the above requirements (1) and (2). Specific examples of the means for improving the dispersibility of the conductive filler include, as will be described later, the following resin layer materials, conductive filler materials, and additives.

[0039] The present disclosure will be described in detail below. <Developer> The developer according to the present disclosure is a toner containing toner particles and an external additive. The composition contains particles A and particles B, and the particles A are at least one particle selected from the group consisting of silica particles and silicone particles. Furthermore, the fine particles B are at least one fine particle selected from the group consisting of antimony-tin-based oxide-titanium-based oxide, antimony-titanium-based oxide, antimony-tin-based oxide, indium-tin-based oxide, indium-titanium-based oxide, niobium-tin-based oxide, niobium-titanium-based oxide, and zinc oxide. Alternatively, the fine particles B are at least one fine particle selected from the group consisting of antimony-tin-based oxide, antimony-titanium-based oxide, antimony-tin-based oxide, indium-titanium-based oxide, niobium-tin-based oxide, niobium-titanium-based oxide, and zinc oxide. Alternatively, the fine particles B are at least one fine particle selected from the group consisting of antimony-tin-based oxide, antimony-tin-based oxide, antimony-tin-based oxide, indium-titanium-based oxide, niobium-tin-based oxide, niobium- -5 ~1.0×10 2 S / m.

[0040] Particle B corresponds to the charge injection part. The particles listed as particle B are a material with higher conductivity than the medium-resistivity titania generally used for toner applications, so a larger amount of charge is injected with the same potential difference compared to medium-resistivity titania, demonstrating high charge injection properties. Furthermore, particle B has a conductivity of 1.0 x 10 as determined by impedance measurement. -5 ~1.0×10 2 Similarly, a high charge injection property is also indicated by a value of S / m.

[0041] That is, for example, the microparticles B may be at least one microparticle selected from the group consisting of antimony-tin-based oxide-titanium-based oxide, antimony-titanium-based oxide, antimony-tin-based oxide, indium-tin-based oxide, indium-titanium-based oxide, niobium-tin-based oxide, niobium-titanium-based oxide, zinc oxide, indium oxide, barium titanate, and strontium titanate.

[0042] The conductivity of particle B is 1.0×10 -5 When the conductivity of the fine particles is 1.0×10 S / m or more, the fine particles have a high charge injection property, and sufficient injection chargeability can be obtained. 2 When the conductivity is less than 1.1×10 S / m, the particles are unlikely to discharge, and sufficient charge injection performance can be obtained. -5 ~1.0×10 0 S / m is preferred. Detailed measurement and calculation methods for measuring the impedance of fine particles B are described in the section on powder impedance measurement methods.

[0043] As mentioned above, particle B is the charge injection site. The presence of highly insulating particles such as silica or silicone particles as shown in particle A at this site causes charge transfer at the contact interface between particle B and particle A, further improving charge injection properties and reducing charge leakage by suppressing the formation of conductive paths at the toner interface by particle B. In particular, it is preferable that the work function of particle A is larger than that of particle B, as this makes it easier for charge to transfer to particle A at the contact interface between particle A and particle B.

[0044] Among the fine particles A that satisfy these conditions, the fine particles A are preferably silica fine particles, more preferably sol-gel silica fine particles. The fine particles B are preferably antimony-tin oxide-titanium oxide, more preferably titanium oxide fine particles doped with antimony and tin. The conductivity of the fine particles A is, for example, 1.0×10 -13 ~1.0×10 -16 S / m, 9.0 x 10 -13 ~9.0×10 -15 S / m is preferred. The preferred state of existence of the fine particles A and the fine particles B is shown below.

[0045] The cross section of the toner observed with a transmission electron microscope is analyzed by energy dispersive X-ray spectroscopy to obtain an EDS mapping image of the constituent elements of the cross section of the toner. In the region outside the contour of the toner particle in the EDS mapping image, a normal to the contour of the toner particle at the contact point between the fine particles having a signal derived from silicon and the toner particle is determined.The number-average length of the fine particles having a signal derived from silicon in the normal direction is preferably 0.02 to 0.20 μm, more preferably 0.04 to 0.10 μm.The above range is preferred from the viewpoint of intermittently providing insulating portions on the toner surface. The fine particles having a signal derived from silicon are considered to correspond to the fine particles A. In other words, the number average value can correspond to the number average particle size of the primary particles of the fine particles A. The number average particle size of the secondary particles is preferably 0.02 to 0.20 μm, more preferably 0.04 to 0.10 μm.

[0046] Furthermore, in the region outside the contour of the toner particle in the EDS mapping image, a normal to the contour of the toner particle at the contact point between the toner particle and the fine particles having a signal derived from the constituent elements of the fine particles B is determined. The number average length of the fine particles having a signal derived from the constituent elements of the fine particles B in the normal direction is preferably 0.01 to 0.05 μm, and more preferably 0.01 to 0.03 μm. The above range is preferred from the viewpoint of providing intermittent injection sites on the toner surface. The fine particles having signals derived from the constituent elements of fine particles B are considered to correspond to fine particles B. In other words, the number average value can correspond to the number average particle size of the primary particles of fine particles B. The number average particle size of the primary particles of fine particles B is preferably 0.01 to 0.05 μm, and more preferably 0.01 to 0.03 μm.

[0047] Regarding the sizes of fine particles A and fine particles B, in order to suppress contact between fine particles B, which are the injection part, and components involved in charge leakage during toner rolling, it is preferable that the number-average particle size of fine particles A is larger than that of fine particles B. In other words, it is preferable that the number-average particle size of the lengths of fine particles having signals derived from silicon is larger than the number-average particle size of the lengths of fine particles having signals derived from the constituent elements of fine particles B. The value of (number average length of fine particles having signals derived from silicon) - (number average length of fine particles having signals derived from the constituent elements of fine particles B) is preferably 0 to 0.30 μm, more preferably 0.01 to 0.25 μm.

[0048] With regard to the state of coverage of the toner surface with the fine particles A, from the viewpoint of suppressing deterioration of the toner due to durability, the coverage rate of the fine particles A on the toner surface is preferably 30 to 70 area %, more preferably 40 to 60 area %. That is, the toner surface observed with a reflection electron microscope is analyzed by energy dispersive X-ray spectroscopy to obtain an EDS mapping image of the constituent elements of the toner surface. In the EDS mapping image, the coverage of the toner surface with fine particles having signals derived from silicon atoms is, for example, 28 to 70 area %, preferably 30 to 70 area %, and more preferably 40 to 60 area %.

[0049] The coverage of the toner surface with fine particles A can be controlled by controlling the amount of fine particles A added, the number-average diameter of fine particles A, and the crushability and diffusibility of the powder in the device used to fix fine particles A. The content of fine particles A is preferably 0.5 to 10.0 parts by mass, and 0.8 to 9.0 parts by mass, per 100 parts by mass of toner particles.

[0050] The coverage of the toner surface with the fine particles B is preferably 5 to 30% by area, more preferably 10 to 30% by area, from the viewpoint of suppressing an increase in the conductivity of the toner interface while maintaining charge injection properties. That is, in the EDS mapping image of the constituent elements on the toner surface, the coverage of the fine particles having signals derived from the constituent elements of fine particle B on the toner surface is, for example, 2 to 38 area %, preferably 5 to 30 area %, and more preferably 10 to 30 area %.

[0051] The coverage of the toner surface with fine particles B can be controlled by controlling the amount of fine particles B added, the number-average diameter of fine particles B, the timing of adding fine particles B when fixing fine particles A and B, and the crushability and diffusibility of the powder within the device. The content of fine particles B is preferably 0.3 to 5.0 parts by mass, or 0.5 to 4.0 parts by mass, per 100 parts by mass of toner particles.

[0052] Furthermore, it is preferable that the difference between the work function Wa of the fine particles A and the work function Wb of the fine particles B is greater than 0, since charge transfer occurs at the contact interface between adjacent fine particles A and B, thereby further improving the amount of charge injected by charge injection. That is, when the work function of the fine particles A is Wa and the work function of the fine particles B is Wb, it is preferable that Wa-Wb>0 is satisfied. Wa-Wb is preferably 0 to 1.0, and more preferably 0.2 to 0.8. The work function of the fine particles can be controlled by the composition of the fine particles or by surface treatment of the fine particles.

[0053] Regarding Wb, it is preferable that Wb>4.0 from the viewpoint of charge injection properties. In particular, when the injection source, such as a development blade, is made of a metal member, it is preferable that Wb>4.0 be satisfied from the viewpoint of charge injection properties. The work function Wa of the fine particles A is preferably 5.0 to 6.0, or 5.2 to 5.6. The work function Wb of the fine particles B is preferably 4.3 to 5.2, or 4.4 to 5.1.

[0054] Each component constituting the toner and the method for producing the toner will be described in more detail below. <Binder resin> The toner particles may have a binder resin. Examples of binder resins include polyester resins, vinyl resins, and other binder resins such as the following resins or polymers: styrene acrylic resins, polyester resins, epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and mixed or composite resins thereof.

[0055] The binder resin is preferably a polyester resin, a styrene-acrylic resin, or a hybrid resin thereof, and more preferably a styrene-acrylic resin, because it is inexpensive, easily available, and has excellent low-temperature fixing properties.

[0056] The polyester resin can be obtained by selecting and combining suitable compounds from polycarboxylic acids, polyols, hydroxycarboxylic acids, etc., and synthesizing them using a conventionally known method such as transesterification or polycondensation.

[0057] Polycarboxylic acids are compounds containing two or more carboxy groups in one molecule, and among these, dicarboxylic acids are compounds containing two carboxy groups in one molecule and are preferably used.

[0058] Examples of dicarboxylic acids include oxalic acid, succinic acid, glutaric acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-carboxylic acid, hexahydroterephthalic acid, malonic acid, pimelic acid, suberic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediacetic acid, o-phenylenediacetic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, and cyclohexanedicarboxylic acid.

[0059] Examples of polycarboxylic acids other than dicarboxylic acids include trimellitic acid, trimesic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, pyrenetetracarboxylic acid, itaconic acid, glutaconic acid, n-dodecylsuccinic acid, n-dodecenylsuccinic acid, isododecylsuccinic acid, isododecenylsuccinic acid, n-octylsuccinic acid, and n-octenylsuccinic acid. Alternatively, two or more of them may be used in combination.

[0060] Polyols are compounds containing two or more hydroxyl groups in one molecule, and among these, diols are compounds containing two hydroxyl groups in one molecule and are preferably used.

[0061] Specifically, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,14-eicosanedecanediol, diethylene glycol, Examples of the alkylene oxide include triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-butenediol, neopentyl glycol, 1,4-cyclohexanediol, polytetramethylene glycol, hydrogenated bisphenol A, bisphenol A, bisphenol F, bisphenol S, and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts of the above bisphenols.

[0062] Among these, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are preferred, and alkylene oxide adducts of bisphenols and their combined use with alkylene glycols having 2 to 12 carbon atoms are particularly preferred.

[0063] Examples of trivalent or higher polyols include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, sorbitol, trisphenol PA, phenol novolac, cresol novolac, and alkylene oxide adducts of the above trivalent or higher polyphenols. These may be used alone or in combination of two or more. The polyester resin may also be a polyester resin containing a urea group. It is preferable that the carboxyl groups of the polyester resin, such as terminal groups, are not capped.

[0064] Examples of the styrene-acrylic resin include homopolymers made of the following polymerizable monomers, copolymers obtained by combining two or more of these, and mixtures thereof.

[0065] Styrenic monomers such as styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene and p-phenylstyrene; Methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, dimethyl phosphate ethyl (meth)acrylate, diethyl phosphate ethyl (meth)acrylate, dibutyl phosphate ethyl (meth)acrylate, and 2-benzoyl (Meth)acrylic monomers such as oxyethyl (meth)acrylate, (meth)acrylonitrile, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid, and maleic acid; Vinyl ether monomers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketone monomers such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; Polyolefins such as ethylene, propylene, and butadiene.

[0066] The styrene-acrylic resin may contain a polyfunctional polymerizable monomer, if necessary. Examples of the polyfunctional polymerizable monomer include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2'-bis(4-((meth)acryloxydiethoxy)phenyl)propane, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.

[0067] In order to control the degree of polymerization, it is also possible to further add a known chain transfer agent and polymerization inhibitor.

[0068] Examples of the polymerization initiator for obtaining the styrene-acrylic resin include organic peroxide-based initiators and azo-based polymerization initiators. Examples of organic peroxide initiators include benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, bis(4-t-butylcyclohexyl)peroxydicarbonate, 1,1-bis(t-butylperoxy)cyclododecane, t-butylperoxymaleic acid, bis(t-butylperoxy)isophthalate, methyl ethyl ketone peroxide, tert-butylperoxy-2-ethylhexanoate, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and tert-butylperoxypivalate.

[0069] Examples of the azo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobismethylbutyronitrile, and 2,2'-azobis-(methyl isobutyrate).

[0070] Furthermore, a redox initiator, which is a combination of an oxidizing substance and a reducing substance, can also be used as the polymerization initiator. The oxidizing substances include inorganic peroxides such as hydrogen peroxide, persulfates (sodium, potassium and ammonium salts) and oxidizing metal salts such as tetravalent cerium salts.

[0071] Reducing substances include reducing metal salts (divalent iron salts, monovalent copper salts, and trivalent chromium salts), ammonia, lower amines (amines with 1 to 6 carbon atoms, such as methylamine and ethylamine), amino compounds such as hydroxylamine, reducing sulfur compounds such as sodium thiosulfate, sodium hydrosulfite, sodium hydrogensulfite, sodium sulfite, and sodium formaldehyde sulfoxylate, lower alcohols (with 1 to 6 carbon atoms), ascorbic acid or its salts, and lower aldehydes (with 1 to 6 carbon atoms). It can be obtained.

[0072] The polymerization initiator is selected based on its 10-hour half-life temperature and is used alone or in combination. The amount of polymerization initiator added varies depending on the desired degree of polymerization, but is generally 0.5 to 20.0 parts by mass per 100.0 parts by mass of polymerizable monomer.

[0073] The toner particles may contain a crystalline polyester, such as a condensation polymer of an aliphatic diol and an aliphatic dicarboxylic acid.

[0074] The crystalline polyester is preferably a condensation polymer of an aliphatic diol having from 2 to 12 carbon atoms and an aliphatic dicarboxylic acid having from 2 to 12 carbon atoms. Examples of the aliphatic diol having from 2 to 12 carbon atoms include the following compounds: 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

[0075] The crystalline polyester may also contain aliphatic diols having double bonds, such as 2-butene-1,4-diol, 3-hexene-1,6-diol, and 4-octene-1,8-diol.

[0076] Examples of aliphatic dicarboxylic acids having from 2 to 12 carbon atoms include the following compounds: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, lower alkyl esters and acid anhydrides of these aliphatic dicarboxylic acids.

[0077] Among these, sebacic acid, adipic acid, 1,10-decanedicarboxylic acid, and lower alkyl esters and acid anhydrides thereof are preferred. These may be used alone or in combination of two or more.

[0078] Aromatic dicarboxylic acids can also be used for the crystalline polyester. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. Among these, terephthalic acid is preferred because it is easily available and can easily form a polymer with a low melting point.

[0079] The crystalline polyester may also contain a dicarboxylic acid having a double bond, which can be used to crosslink the entire resin by utilizing the double bond, and is therefore suitable for suppressing hot offset during fixing. Examples of such dicarboxylic acids include fumaric acid, maleic acid, 3-hexenedioic acid, and 3-octenedioic acid. Also included are lower alkyl esters and acid anhydrides of these. Among these, fumaric acid and maleic acid are more preferred.

[0080] The method for producing the crystalline polyester is not particularly limited, and the crystalline polyester can be produced by a general polyester polymerization method in which a dicarboxylic acid component and a diol component are reacted. For example, the crystalline polyester can be produced by a direct polycondensation method or an ester exchange method, which are selected depending on the type of monomer.

[0081] The content of the crystalline polyester is preferably 1.0 parts by mass or more and 30.0 parts by mass or less, and more preferably 3.0 parts by mass or more and 25.0 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0082] The peak temperature of the maximum endothermic peak of the crystalline polyester measured using a differential scanning calorimeter (DSC) is preferably 50.0°C or higher and 100.0°C or lower, and from the viewpoint of low-temperature fixability, more preferably 60.0°C or higher and 90.0°C or lower.

[0083] The molecular weight of the binder resin is preferably a peak molecular weight Mp of 5,000 or more and 100,000 or less, more preferably 10,000 or more and 40,000 or less. The glass transition temperature Tg of the binder resin is preferably 40° C. or more and 70° C. or less, more preferably 40° C. or more and 60° C. or less. The content of the binder resin is preferably 50% by mass or more with respect to the total amount of resin components in the toner particles.

[0084] <Crosslinking agent> In order to control the molecular weight of the binder resin constituting the toner particles, a crosslinking agent may be added during polymerization of the polymerizable monomer. For example, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, divinylbenzene, bis(4-acryloxypolyethoxyphenyl)propane, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol #200, #400, and #600 diacrylates, dipropylene glycol diacrylate, polypropylene glycol diacrylate, polyester diacrylate (MANDA Nippon Kayaku), and those in which the above acrylates have been replaced with methacrylates.

[0085] The amount of the crosslinking agent added is preferably 0.001 parts by mass or more and 15,000 parts by mass or less relative to 100 parts by mass of the polymerizable monomer.

[0086] <Release agent> The toner may contain a known wax as a release agent. Specific examples include petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum and their derivatives, montan wax and its derivatives, hydrocarbon waxes produced by the Fischer-Tropsch process and their derivatives, polyolefin waxes such as polyethylene and polypropylene and their derivatives, and natural waxes such as carnauba wax and candelilla wax and their derivatives. Derivatives also include oxides, block copolymers with vinyl monomers, and graft-modified products.

[0087] Other examples include alcohols such as higher aliphatic alcohols, fatty acids such as stearic acid and palmitic acid or their acid amides, esters, and ketones, hydrogenated castor oil and its derivatives, vegetable waxes, and animal waxes.These may be used alone or in combination.

[0088] Among these, polyolefin, hydrocarbon wax produced by the Fischer-Tropsch method, or petroleum wax is preferred because it tends to improve the developing property and transfer property. Note that these waxes may contain an antioxidant within a range that does not affect the properties of the toner. It may be done.

[0089] In addition, from the viewpoint of phase separation property relative to the binder resin or crystallization temperature, preferred examples include higher fatty acid esters such as behenyl behenate and dibehenyl sebacate.

[0090] The content of the release agent is preferably 1.0 part by mass or more and 30.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0091] The melting point of the release agent is preferably 30° C. or higher and 120° C. or lower, and more preferably 60° C. or higher and 100° C. or lower. By using a release agent with a melting point of 30° C. or higher and 120° C. or lower, the release effect is efficiently exerted and a wider fixing area is ensured.

[0092] <Plasticizer> From the viewpoint of improving the sharp melting property of the toner, the toner may contain a plasticizer. The plasticizer is not particularly limited, and known plasticizers used in toners such as those described below can be used.

[0093] Esters of monohydric alcohols and fatty carboxylic acids, such as behenyl behenate, stearyl stearate, and palmityl palmitate, or esters of monohydric carboxylic acids and fatty alcohols; esters of dihydric alcohols and fatty carboxylic acids, such as ethylene glycol distearate, dibehenyl sebacate, and hexanediol dibehenate, or esters of dihydric carboxylic acids and fatty alcohols; esters of trihydric alcohols and fatty carboxylic acids, such as glycerin tribehenate, or esters of trihydric carboxylic acids and fatty alcohols; pentaerythritol tetrastearate esters of tetrahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate, or esters of tetrahydric carboxylic acids and aliphatic alcohols; esters of hexahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate, or esters of hexahydric carboxylic acids and aliphatic alcohols; esters of polyhydric alcohols and aliphatic carboxylic acids, such as polyglycerol behenate, or esters of polyhydric carboxylic acids and aliphatic alcohols; and natural ester waxes, such as carnauba wax and rice wax. These may be used alone or in combination.

[0094] <Coloring agent> The toner particles may contain a colorant. Known pigments and dyes can be used as the colorant. Pigments are preferred as the colorant because they have excellent weather resistance. Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds. Specific examples include: CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62 and 66.

[0095] Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specific examples include CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254, and CI Pigment Violet 19.

[0096] Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specific examples include the following: CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191 and 194.

[0097] Examples of black colorants include those toned to black using the above yellow, magenta, and cyan colorants, as well as carbon black. These colorants can be used alone or in mixture, or further in the state of a solid solution. The colorant is preferably used in an amount of 1.0 part by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0098] <Charge control agents and charge control resins> The toner particles may contain a charge control agent or a charge control resin. Known charge control agents can be used, and charge control agents that have a high triboelectric charging speed and can stably maintain a constant triboelectric charge amount are particularly preferred. Furthermore, when the toner particles are produced by a suspension polymerization method, charge control agents that have low polymerization inhibition properties and are substantially free of solubilized substances in aqueous media are particularly preferred.

[0099] Examples of substances that control the toner to be negatively charged include monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic and dicarboxylic acid-based metal compounds, aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid-based compounds, metal-containing naphthoic acid-based compounds, boron compounds, quaternary ammonium salts, calixarene, and charge control resins.

[0100] Examples of the charge control resin include polymers or copolymers having sulfonic acid groups, sulfonate salt groups, or sulfonate ester groups. As the polymer having sulfonic acid groups, sulfonate salt groups, or sulfonate ester groups, a polymer containing 2% by mass or more, more preferably 5% by mass or more, of a sulfonate group-containing acrylamide monomer or a sulfonate group-containing methacrylamide monomer in copolymerization ratio is preferred.

[0101] The charge control resin preferably has a glass transition temperature (Tg) of 35°C or higher and 90°C or lower, a peak molecular weight (Mp) of 10,000 or higher and 30,000 or lower, and a weight average molecular weight (Mw) of 25,000 or higher and 50,000 or lower. When used, it can impart desirable triboelectric charging properties without affecting the thermal properties required of the toner particles. Furthermore, when the charge control resin contains sulfonic acid groups, the dispersibility of the charge control resin itself and the dispersibility of colorants, etc., in the polymerizable monomer composition is improved, thereby further improving coloring power, transparency, and triboelectric charging properties.

[0102] These charge control agents or charge control resins may be added singly or in combination of two or more kinds. The amount of the charge control agent or charge control resin added is preferably 0.01 to 20.0 parts by mass, more preferably 0.5 to 10.0 parts by mass, relative to 100.0 parts by mass of the binder resin.

[0103] <External additives> The toner may contain external additives other than the above-described fine particles A and fine particles B. For example, in order to improve the fluidity, chargeability, cleaning properties, etc., a fluidizing agent, a charging aid, a cleaning aid, etc. may be added to the toner particles to obtain the toner.

[0104] Examples of external additives include inorganic oxide fine particles such as silica fine particles and alumina fine particles, positively charged particles such as hydrotalcite and melamine resin, and inorganic stearic acid compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles. These may be used alone or in combination of two or more.

[0105] <Method of manufacturing toner particles> The toner particles preferably have core particles containing a binder resin and a shell on the surface of the core particles. The method for producing the toner particles is not particularly limited, and known means can be used, such as a kneading and pulverization method or a wet production method. Examples of wet production methods include a suspension polymerization method, a dissolution suspension method, an emulsion polymerization aggregation method, and an emulsion aggregation method. From the viewpoints of achieving uniform particle size, shape controllability, and ease of obtaining toner particles with a core-shell structure, a wet production method is preferred, and among these, a suspension polymerization method and an emulsion aggregation method are preferred. As an example, the suspension polymerization method will be described below.

[0106] <Suspension polymerization method> In the suspension polymerization method, first, a polymerizable monomer for producing a binder resin, a colorant, and other additives as needed are uniformly dissolved or dispersed using a disperser such as a ball mill or an ultrasonic disperser to prepare a polymerizable monomer composition (polymerizable monomer composition preparation step). At this time, a multifunctional monomer, a chain transfer agent, a wax as a mold release agent, a charge control agent, a plasticizer, and the like can be appropriately added as needed.

[0107] Next, the polymerizable monomer composition is poured into a previously prepared aqueous medium, and droplets of the polymerizable monomer composition are formed into the desired toner particle size using a stirrer or disperser with high shear force (granulation process).

[0108] It is preferable that the aqueous medium used in the granulation process contains a dispersion stabilizer in order to control the particle size of the toner particles, sharpen the particle size distribution, and prevent the coalescence of toner particles during the manufacturing process. Dispersion stabilizers are generally broadly classified into polymers that exhibit repulsive forces due to steric hindrance and poorly water-soluble inorganic compounds that stabilize dispersion by electrostatic repulsive forces. Fine particles of poorly water-soluble inorganic compounds are preferably used because they dissolve in acid or alkali and can be easily removed by washing with acid or alkali after polymerization.

[0109] As the dispersion stabilizer of the poorly water-soluble inorganic compound, one containing any of magnesium, calcium, barium, zinc, aluminum, and phosphorus is preferably used. More preferably, one containing any of magnesium, calcium, aluminum, and phosphorus is desired. Specific examples include the following.

[0110] Magnesium phosphate, tricalcium phosphate, aluminum phosphate, zinc phosphate, magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, hydroxyapatide.

[0111] The dispersion stabilizer may be used in combination with an organic compound such as polyvinyl alcohol, gelatin, methyl cellulose, methylhydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, or starch. These dispersion stabilizers are preferably used in an amount of 0.01 to 2.00 parts by mass per 100 parts by mass of the polymerizable monomer.

[0112] Furthermore, to make these dispersion stabilizers finer, a surfactant may be used in an amount of 0.001 to 0.1 parts by mass per 100 parts by mass of the polymerizable monomer. Specifically, commercially available nonionic, anionic, and cationic surfactants can be used. For example, sodium dodecyl sulfate Among these, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, and calcium oleate are preferably used.

[0113] After the granulation step, or while the granulation step is being carried out, the temperature is preferably set to 50°C or higher and 90°C or lower to polymerize the polymerizable monomers contained in the polymerizable monomer composition, thereby obtaining a toner particle dispersion (polymerization step).

[0114] In the polymerization step, it is preferable to perform stirring so as to achieve a uniform temperature distribution in the vessel. When adding a polymerization initiator, it can be added at any timing and for any required time. The temperature may be raised in the latter half of the polymerization reaction in order to obtain a desired molecular weight distribution. Furthermore, in order to remove unreacted polymerizable monomers, by-products, etc. from the system, a portion of the aqueous medium may be distilled off in the latter half of the reaction or after completion of the reaction. The distillation operation may be performed under normal pressure or reduced pressure.

[0115] In the suspension polymerization method, an oil-soluble initiator is generally used as the polymerization initiator, and a water-soluble initiator may be used in combination with the oil-soluble initiator, if necessary. These polymerization initiators can be used alone or in combination, and a chain transfer agent, a polymerization inhibitor, etc. can also be added to control the degree of polymerization of the polymerizable monomer.

[0116] From the viewpoint of obtaining high-definition, high-resolution images, the volume-based median diameter of the toner particles is preferably 3.0 μm or more and 10.0 μm or less. The volume-based median diameter and number-average particle diameter of the toner can be measured by the pore electrical resistance method. For example, they can be measured using a Coulter Counter Multisizer 3 (manufactured by Beckman Coulter, Inc.). The toner particle dispersion thus obtained is sent to a filtration process for solid-liquid separation of the toner particles and the aqueous medium.

[0117] Solid-liquid separation to obtain toner particles from the resulting toner particle dispersion can be performed by a general filtration method, and then, in order to remove any foreign matter that has not been completely removed from the toner particle surface, further washing is preferably performed by reslurrying or washing with washing water. After sufficient washing, solid-liquid separation is again performed to obtain a toner cake. Thereafter, the toner cake is dried by a known drying means, and if necessary, particle groups having particle sizes other than the specified particle size are separated by classification to obtain toner particles. The particle groups having particle sizes other than the specified particle size separated at this time may be reused to improve the final yield.

[0118] <Toner manufacturing method> The toner contains at least fine particles A and fine particles B as external additives. The toner can be obtained by externally adding the fine particles A and the fine particles B to the toner particles.

[0119] The mixer for externally adding the external additive to the toner particles is not particularly limited, and any known mixer, whether dry or wet, can be used. Examples include FM Mixer (manufactured by Nippon Coke & Engineering Co., Ltd.), Super Mixer (manufactured by Kawata Corporation), Nobilta (manufactured by Hosokawa Micron Corporation), and Hybridizer (manufactured by Nara Kikai Co., Ltd.). To control the coating state of the external additive, the toner can be prepared by adjusting the rotation speed, processing time, and water temperature and amount in the jacket of the external addition device.

[0120] In addition, examples of sieving devices used to sift out coarse particles after external addition include Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonaseave, Gyrosifter (Tokuju Kogyo Co., Ltd.); Vibrasonic System (manufactured by Dalton Co., Ltd.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Turbo Screener (manufactured by Turbo Kogyo Co., Ltd.); and Microsifter (manufactured by Makino Sangyo Co., Ltd.).

[0121] <Developing roller> The developer carrier is a developing roller having a substrate with a conductive outer surface and a resin layer on the outer surface of the substrate.

[0122] An example of a developing roller is shown in Fig. 1. The developing roller 10 shown in Fig. 1 has a resin layer 12 laminated on the outer peripheral surface of a columnar or hollow cylindrical substrate 11. The layer configuration of the developing roller is not limited to the form shown in Fig. 1. As another form of the developing roller, as shown in Fig. 2, an elastic layer 13 may be provided between a base 11 and a resin layer 12 provided on the outer peripheral surface thereof.

[0123] [Base] The substrate has a conductive outer surface and functions as a support member for the developing roller and, in some cases, as an electrode. Specific examples of the substrate preferably have a solid columnar or hollow cylindrical shape.

[0124] 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.

[0125] Furthermore, the material constituting the substrate may be subjected to an oxidation treatment or a plating treatment with chromium, nickel, or the like. 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 electroless plating that can be used here include nickel plating, copper plating, gold plating, and various other alloy platings. The plating thickness is preferably 0.05 μm or more, and considering the balance between work efficiency and rust prevention ability, the plating thickness is preferably 0.1 to 30 μm.

[0126] A primer may be applied to the surface of the substrate to improve adhesion between the substrate and the resin 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.

[0127] [Resin layer] The developing roller has a resin layer on the outer surface of the substrate. For example, the resin layer is present on the outer surface of the developing roller. The resin layer may contain a binder resin. As the binder resin of the resin layer in the developing roller, polyurethane is preferably used, and polyurethane having a polycarbonate structure is more preferably used, in order to suppress charge leakage from the toner to the developing roller. That is, the resin 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.

[0128] Furthermore, in order to suppress charge leakage from the toner to the developing roller while maintaining a light load on the toner and sufficient abrasion resistance of the resin layer, it is more preferable to use a polyurethane having the structure described below as the binder resin of the resin layer.

[0129] The resin layer contains polyurethane, and the polyurethane preferably satisfies at least two of the following (A), (B), and (C): You may fill all of them. (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.

[0130] 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) Among these, from the viewpoint of better fogging suppression and image density stability, it is more preferable that the polyurethane has at least the structure represented by structural formula (1) and the structure represented by structural formula (4) in the molecule.

[0131] [ka]

[0132] 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).

[0133] 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 resin 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 resin layer, the adhesiveness of the resin layer can be reduced, which prevents toner, powder, etc. from adhering to the surface of the resin layer, suppresses an increase in the electrical resistance of the surface of the resin layer due to contamination, and facilitates uniform charging of the toner.

[0134] 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 R11 and R12 each have 3 or more carbon atoms, the amount of carbonate groups, which are polar functional groups with strong cohesive energy, in the polyurethane will not be too large, making it easier to maintain the resin layer flexible and with a high electrical resistance. 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 resin 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.

[0135] 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 resin layer.

[0136] When a resin 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 resin layer can be endowed with sufficient volume resistivity while having a polar ester group, making it easier to suppress charge leakage from the toner to the developing roller.

[0137] 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 groups and ester groups in the polyurethane, which are polar functional groups with strong cohesive energy, is not too large, thereby maintaining flexibility of the resin layer. When R31 and R32 each have 8 or less carbon atoms, the amount of carbonate groups and ester groups in the polyurethane is not too small, thereby providing abrasion resistance to the resin layer.

[0138] The structure shown in structural formula (4) is a structure in which two carbonate groups are bonded with a single hydrocarbon group. This structure is formed by reacting a highly crystalline polycarbonate polyol with an isocyanate. This structure is highly crystalline and easily oriented in the soft segment, imparting abrasion resistance and high volume resistivity to the resin layer. By forming a resin layer using a polymer that combines the structure represented by structural formula (4) with the structures of formulas (1) to (3) above, the hardness of the resin layer does not become too high and can be easily controlled appropriately.

[0139] 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 resin 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 resin layer can be suppressed.

[0140] The resin 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) above, which makes the resin layer flexible and less susceptible to wear.

[0141] The structure of the polymer contained in the resin layer of the developing roller can be confirmed by, for example, pyrolysis GC / MS, FT-IR, or NMR analysis.

[0142] 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.

[0143] 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 resin 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.

[0144] 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 can increase the water absorption of the polymer and reduce the volume resistivity of the resin 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 toner to the developing roller.

[0145] (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 the following: polycarbonate polyol, polyether polyol, polyester polyol, polyolefin polyol such as polybutadiene polyol and polyisoprene polyol, and polyols obtained by polymerizing ethylenically unsaturated monomers in polyols. So-called polymer polyols, polyester polycarbonate copolymer polyols, etc. Among these, the polyol compound is preferably at least one selected from the group consisting of polycarbonate polyols and polyester polycarbonate copolymer polyols.

[0146] 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.

[0147] 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.

[0148] (B) Polyisocyanate compound The polyisocyanate may be selected from commonly used and known polyisocyanates, such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, hydrogenated MDI, polymeric MDI, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). Among these, aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, and polymeric MDI are more preferably used. Other polyisocyanates may also be used as long as they do not affect the impedance value and surface potential.

[0149] 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.

[0150] The content of polyurethane in the resin 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.

[0151] (Conductive filler) The resin 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 resin 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 resin layer, a DBP absorption of 90 ml / 100 g or less, and a pH of 4.0 or less is particularly preferably used.

[0152] 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.

[0153] 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.

[0154] 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 the carbon black less likely to aggregate, and thus making it easier 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 preferably 2.0 to 4.0, and more preferably 2.2 to 2.8.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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, relative to 100 parts by mass of polyurethane forming the resin layer. When the amount is 30 parts by mass or less, the distance between the carbon black particles in the coating liquid is kept appropriate, the probability of collision due to Brownian motion of the carbon black particles is reduced, and the carbon black particles do not aggregate. Therefore, the carbon black becomes more easily dispersed and the dispersion stability is improved. As a result, the carbon black is well dispersed in the resin layer formed by coating the coating liquid.

[0159] 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 resin 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 resin 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.

[0160] 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. In terms of 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.

[0161] The arithmetic mean value Rc of the equivalent circle diameter is more preferably 40.0 to 60.0 nm, and even more preferably 45.0 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 resin 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.

[0162] 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 resin 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.

[0163] (additives) One of the preferred embodiments is to use an additive to further improve the dispersibility of carbon black in a binder resin using polycarbonate urethane. Here, as the additive, 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. One method for incorporating the additive into the surface layer is to incorporate a dispersant into the coating liquid for forming the surface layer. Incidentally, the additive containing at least one compound selected from the group consisting of a compound having a structure represented by the structural formula (5) and a compound having a structure represented by the structural formula (6) can be used. In a surface layer formed using a coating liquid for forming a surface layer containing the compound, the compound may be incorporated at the end of the polyurethane polymer chain. Even in such a case, the effect of improving the dispersibility of carbon black can be expected, but it is preferable that the compound is present in the surface layer independently of the polyurethane.

[0164] 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.

[0165] [ka]

[0166] 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 or more (preferably 5 to 30, more preferably 10 to 25). 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 or more (preferably 1 to 30, more preferably 5 to 30). 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 or more (preferably 1 to 30, more preferably 4 to 15).

[0167] 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.

[0168] 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 resin 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.

[0169] 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.

[0170] 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).

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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. In addition, 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, and the dispersant disperses the polycarbonate urethane. The structure is also compatible with

[0176] 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).

[0177] 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 the oxidation of a secondary alcohol to produce a ketone. The synthesis of ketones by oxidation of a secondary alcohol can be carried out using heavy metal salts such as chromic acid or manganese dioxide or their derivatives, or by non-heavy metal salt oxidation using dimethyl sulfoxide (DMSO) or hypohalous acids such as hypochlorous acid.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] Polyoxyethylene alkyl ether acetic acid can be a commercially available product or can be obtained by synthesis. Polyoxyethylene alkyl ether acetic acid can be synthesized by carrying out the following step (E) followed by step (F). Note that the synthesis of polyoxyethylene alkyl ether acetic acid can be carried out by carrying out the following step (E) followed by step (F). Step (F) may be carried out on a commercially available product having such a structure. 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).

[0183] Step (F) is the oxidation of a primary alcohol to produce a carboxylic acid. Because the oxidation of a primary alcohol produces an aldehyde, followed by further oxidation to produce a carboxylic acid, 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 catalytic dehydrogenation using a catalyst. Oxidizing agents include permanganate, chromic acid, ruthenium tetroxide, and hypochlorite. Dehydrogenation catalysts include palladium, platinum, iridium, rhodium, and manganese.

[0184] 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.

[0185] 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.

[0186] 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 coating material for forming a surface layer, more preferably 3.0 to 5.0 mass %, and the total content is preferably 18.9 to 46.0 mass parts relative to 100 mass parts of carbon black in the coating material for forming a surface layer. By ensuring that the content of the additive in the coating material for forming the surface layer is within the above range, the dispersibility of the carbon black in the polyurethane is further improved, and the desired impedance value and surface potential can be more easily achieved.

[0187] The presence of additives in the resin layer can be confirmed and quantitatively evaluated by the following method. The resin 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 resin 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 allows us to calculate the proportion of additives that were incorporated into the resin during the polymerization reaction and those that were not.

[0188] The resin layer is made of at least one of compounds having a structure represented by structural formula (5) or (6). may have a structure in which the compound 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.

[0189] [Roughening particles] The resin layer may contain roughening particles. The roughening particles may be, for example, spherical particles. The particle diameter of the roughening particles is, for example, preferably in the range of 1 μm to 150 μm, and more preferably in the range of 5 μm to 30 μm. For example, at least one spherical particle selected from the following particles may 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 resin layer is preferably 1 to 20% by mass, more preferably 5 to 15% by mass.

[0190] 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 resin layer, for example. The elastic layer is not particularly limited, and any known elastic layer for developing rollers may be used. For example, the elastic layer may be a cured product of an addition-curing liquid silicone rubber mixture.

[0191] (Manufacturing method) The method for forming the resin layer is not particularly limited, but examples include spraying with a paint, dip coating, and roll coating. For example, a resin layer can be formed by applying a resin 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 heating and drying conditions are not particularly limited, and examples include a method of drying at 120 to 200°C. The thickness of the resin layer is also not particularly limited, and is preferably 1 to 50 μm, and more preferably 5 to 20 μm.

[0192] <Process cartridge and electrophotographic image forming apparatus> The developing roller according to the present disclosure can be suitably used as a developing roller in a process cartridge. The process cartridge includes the developing device according to the present disclosure. 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 integrates a developing device 18 including a developing roller 14 and a developing blade 15, a photosensitive member 19, a charging roller 20, and a cleaning blade 21. 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 the developing blade 15.

[0193] 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.

[0194] The toner supply roller 17 comes into contact with 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 is applied to the toner supply roller 17.

[0195] 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, imparting an electric charge to the toner 16.

[0196] The developing device has a developing roller 14 and toner 16. The developing device also has a developing blade 15, which is a developer layer thickness regulating member that contacts the developing roller 14, which is a developer carrier, and regulates the layer thickness of the toner 16, which is the developer carried on the developer carrier, and a contact point electrically connected to the developing blade 15. When the developing device is mounted in the main body of an electrophotographic image forming apparatus, the contact point electrically connects to a main body contact point of the main body of the electrophotographic image forming apparatus, making it possible to apply a predetermined voltage to the developing blade 15. The volume resistivity of the developing blade 15 is 1.0×10 6 It is preferable that the resistivity is Ω·cm or less. This allows the developing blade 15 to form a layer of toner 16 of uniform thickness on the developing roller 14, while at the same time enabling charge injection from the developing blade 15 into the toner, making it easier to uniformly control the amount of charge on the toner.

[0197] An electrophotographic image forming apparatus is provided with a developing device. Figure 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. 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.

[0198] 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.

[0199] 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.

[0200] A voltage is applied to the developing roller 14, developing blade 15, transfer roller 24, and secondary transfer roller 28 from a bias power supply 33. The paper 26 onto which the toner image has been transferred is fixed by a fixing device 34 and then ejected outside the device, completing the printing operation. Meanwhile, residual toner remaining on the photoreceptor 19 without being transferred is scraped off by a cleaning blade 21, which is a cleaning member for cleaning the surface of the photoreceptor. The cleaned photoreceptor 19 repeats the above printing operation.

[0201] The methods for measuring the physical properties of each material, toner, and developing roller will be described below. <Method for measuring impedance of fine particles, toner, and other powders and calculating conductivity> The capacitance and conductivity of air and powder are measured by impedance measurement using the parallel plate capacitor method. The equipment used is a toner measurement jig consisting of a four-terminal sample holder SH2-Z (manufactured by Toyo Corporation) and a torque wrench adapter SH-TRQ-AD (optional), and a material testing system ModuLab XM MTS (manufactured by Solartron Corporation). In addition, a noise-cutting transformer NCT-I3 1.4kVA (manufactured by Denken Seiki Kenkyusho Co., Ltd.) is used to suppress commercial power supply noise, and a shielding box is used to suppress electromagnetic wave noise.

[0202] The measurement jig uses a four-terminal sample holder and the optional torque wrench adapter SH-TRQ-AD, and uses the upper electrode (Φ25mm solid electrode) SH-H25AU and the lower electrode for liquids / powder (center electrode Φ10mm; guard electrode Φ26mm) SH-2610AU as parallel plate electrodes, and is configured to be able to measure resistances of 0.1Ω to 1TΩ for electrical signals of up to 500Vp-p and DC to 1MHz.

[0203] In addition, to adjust the pressure on the sample, a torque wrench adapter SH-TRQ-AD (manufactured by Toyo Corporation) was attached to the micrometer used to measure the film thickness between the upper and lower electrodes on the four-terminal sample holder. The torque driver used for pressure control is a torque driver RTD15CN (manufactured by Tohnichi Manufacturing Co., Ltd.) with a 6.35 mm square bit, configured to be able to control the tightening torque to 6.5 cN m if the powder to be measured is toner. If the powder to be measured is fine particles A or B, a torque driver RTD30CN (manufactured by Tohnichi Manufacturing Co., Ltd.) with a 6.35 mm square bit, configured to be able to control the tightening torque to 20.0 cN m.

[0204] The electrical AC characteristics are measured by impedance measurement using a material testing system ModuLab XM MTS (manufactured by Solartron). The ModuLab XM MTS consists of the control module XM MAT 1MHz, the high-voltage module XM MHV100, the femtocurrent module XM MFA, and the frequency response analysis module XM MRA 1MHz, and the control software is the company's own XM-studio MTS Ver.3.4.

[0205] When the powder is toner, the measurement conditions are Normal Mode, which only performs measurement, with an AC level of 7 Vrms, a DC bias of 0 V, and a sweep frequency of 1 MHz to 0.01 Hz (12 points / decade or 6 points / decade). Furthermore, in consideration of noise suppression and shortening of measurement time, the following settings are added for each sweep frequency. Sweep frequency 1MHz~10Hz Measurement integration time 64 cycles Sweep frequency 10Hz to 1Hz Measurement integration time 24 cycles Sweep frequency 1Hz to 0.01Hz Measurement integration time 1 cycle Under the above measurement conditions, the impedance characteristics, which are the electrical AC characteristics of the toner, are measured.

[0206] When the powders are fine particles A and B, the measurement conditions are Normal Mode, which only performs measurement, with an AC level of 0.5 Vrms, a DC bias of 0 V, and a sweep frequency of 1 MHz to 0.01 Hz (12 points / decade or 6 points / decade). Furthermore, in consideration of noise suppression and shortening of measurement time, the following settings are added for each sweep frequency. Sweep frequency 1MHz~10Hz Measurement integration time 64 cycles Sweep frequency 10Hz to 1Hz Measurement integration time 24 cycles Sweep frequency 1Hz to 0.01Hz Measurement integration time 1 cycle Under the above measurement conditions, the impedance characteristics, which are the electrical AC characteristics of the particles A and B, are measured.

[0207] By performing measurements under the above conditions, a powder measurement jig based on the parallel plate capacitor method is used, and the impedance characteristics of the air and sample at the film thickness d according to the pressure torque and a measurement electrode S of 10 mm in diameter can be obtained.

[0208] From the obtained impedance characteristics of the air and sample, data correction processing for the measurement system is performed to obtain highly reliable capacitance C and conductance (conductivity) G. From the obtained capacitance C, conductance (conductivity) G, and the geometric shape of the toner measurement jig (parallel plate electrode size S and sample film thickness), the electrical properties of relative permittivity and conductivity are calculated.

[0209] When using the SH2-Z four-terminal sample holder for the first time, two verifications must be carried out to find the optimal measurement conditions, since there are individual differences in the SH2-Z four-terminal sample holders used in powder measurement jigs.

[0210] The first verification is the film thickness dependency characteristics of the four-terminal sample holder. The dependency on air thickness (distance between the upper and lower electrodes) is measured, the error between the theoretical value of capacitance and the measured value is confirmed, and the optimal range or film thickness at which the measurement error is minimized is identified.

[0211] The second verification is the measurement of mechanical error. When measuring toner samples, a torque-controlled load is applied to maintain a constant volume density. In contrast, when measuring air, no load is applied. At this time, film thickness errors occur due to the influence of dimensions such as mechanical processing accuracy. Therefore, the offset value when the tightening torque control value (6.5 cN m in this jig) is loaded and unloaded is confirmed, and this is used as the offset correction value.

[0212] The specific sample preparation and measurement procedures are as follows. (1) Pile powder on the center electrode of the lower electrode and shape it into a trapezoidal shape with a height of 5 mm. (2) The lower electrode with the powder piled on it is attached to the four-terminal sample holder SH2-Z, and the upper electrode is lowered. (3) At this time, the upper electrode is lowered to the top end of the powder while keeping it constant so as not to rotate unintentionally. (4) While rotating the upper electrode left and right, smoothing treatment is performed to make the powder smooth. (5) Using a micrometer, adjust the film thickness to a predetermined value while maintaining the rotation direction of the upper electrode in a uniform, constant direction. (6) Apply pressure using a torque driver that is suited to the powder. (7) Measure the sample film thickness using a micrometer. (8) Impedance measurement is carried out under the above conditions. (9) After the measurement is completed, raise the upper electrode and remove the lower electrode. At this time, remove the lower electrode carefully so that toner does not get into the contact terminal for the lower electrode of the four-terminal sample holder, and protect it with masking tape. (10) Clean the upper and lower electrodes. (11) Remove the masking tape and attach the lower electrode. (12) The sample film thickness d obtained in step (7) is adjusted to the air thickness t, taking into account offset correction in the no-load state, and the rotation direction of the upper electrode is kept constant. (13) Conduct air impedance measurements. (14) If the measurement data (dielectric tangent; tanδ) of the air measured in step (13) is 0.002 or more in the frequency range of 100 Hz to 0.01 Hz, the cleaning is insufficient, so the work is to be started again from the cleaning step (10). The measurement is carried out at 25°C.

[0213] The specific data processing procedure is as follows. (15) From the measured impedance characteristics of air, the error of the phase characteristics relative to the theoretical value is calculated, and phase correction data for the material testing system ModuLab XM MTS (manufactured by Solartron) is obtained. (16) The phase correction data calculated in step (15) is applied to the impedance characteristics of the air measured in step (13) to obtain the phase-corrected impedance characteristics of the air. (17) The capacitance Ca is calculated from the admittance Ya=Ga+jωCa of the phase-corrected impedance characteristic of air, and the error from the theoretical value is calculated to obtain correction data α for the film thickness error. (18) The phase correction process obtained in step (15) is applied to the impedance characteristics of the powder sample measured in step (8). (19) By calculating the complex admittance Ym = Gm + jωCm of the characteristics that have been subjected to the phase correction processing in step (18) using the capacitance Ca of the air obtained in step (17) and its correction data α, highly reliable relative permittivity and conductivity of the powder sample can be obtained. The electrical conductivity of the fine particles A, the fine particles B, and the toner in this disclosure is a value of electrical conductivity at a frequency of 0.01 Hz.

[0214] <Method for measuring particle diameters of fine particles A and B present on the toner surface> The cross section of the toner is observed using a transmission electron microscope (TEM) using the following method. First, the toner is thoroughly dispersed in a room-temperature curing epoxy resin, and then cured for two days in an atmosphere at 40°C. A 100 nm-thick flake sample is cut from the resulting cured product using a microtome equipped with a diamond blade. This sample is magnified 100,000 times in a TEM (product name: electron microscope Tecnai TF20XT, manufactured by FEI) to observe the cross section of the toner. In this case, a toner cross section having a major axis diameter 0.9 to 1.1 times the number-average particle size (D1) measured for the toner is selected.

[0215] Next, the constituent elements of the cross-section of the obtained toner are collected and analyzed using an energy dispersive X-ray spectroscopy (EDX) analyzer to create an EDX mapping image. Spectra are collected and analyzed using an NSS (Thermo Fischer Scientific). The collection conditions are an acceleration voltage of 200 kV, a probe size of 1.0 nm or 1.5 nm selected appropriately so that the dead time is 15 to 30, a mapping resolution of 256 x 256, and 500 frames. EDS mapping images are obtained for 50 toner cross-sections.

[0216] In the EDX mapping image, fine particles having a signal derived from silicon, which is an external additive, and fine particles having a signal derived from the constituent elements of fine particles B are confirmed on the contours of the toner particles. In the region outside the contour of the toner particle, the length of the fine particle having the signal derived from silicon is measured in the normal direction to the contour of the toner particle at the point of contact between the fine particle having the signal derived from silicon and the toner particle. In addition, in the region outside the contour of the toner particle, the length of the microparticle having a signal derived from the constituent elements of microparticle B is measured in the normal direction to the contour of the toner particle at the point of contact between the microparticle having a signal derived from the constituent elements of microparticle B and the toner particle. The length of each of the 50 particles is measured using the above method, and the arithmetic mean value of the 50 particles is obtained. The contact point between the toner particle and the particle for determining the normal line is specified as follows: The distance from the particle interface in the normal direction was measured, and the point where the maximum length was reached was taken as the contact point.

[0217] <Method for measuring the coverage of particles A and B on the toner surface> The coverage of the toner surface with the fine particles A and B is calculated as follows. Using a scanning electron microscope (SEM, model JSM-7800F manufactured by JEOL Ltd.), the toner surface was observed at a magnification of 50,000 times to identify the external additive particles. Then, elements on the toner surface were mapped using EDX (energy dispersive X-ray spectroscopy). From the obtained SEM element mapping image, the coverage (area %) of particles on the toner surface that had signals derived from silicon was calculated (coverage of particle A). Furthermore, the coverage (area %) of particles on the toner surface that had signals derived from the constituent elements of particle B was calculated (coverage of particle B).

[0218] <Method for measuring the work function of fine particles> The work function of the fine particles is measured by the following measurement method. The work function is expressed numerically as the energy (eV) required to extract an electron from the substance. The work function is measured using a surface analyzer (AC-2 manufactured by Riken Keiki Co., Ltd.). A deuterium lamp is used in the above-mentioned device, and measurements are made under the following conditions. Irradiation light intensity: 800nW Spectrometer: Monochromatic light Spot size: 4mm x 4mm Energy scan range: 3.6 to 6.2 eV Anode voltage: 2910V Measurement time: 30 [sec / 1 point] The photoelectrons emitted from the sample surface are detected and processed using work function calculation software built into the surface analyzer. The work function is measured with a repeatability (standard deviation) of 0.02 eV. When measuring powder, a powder measurement cell is used. In the surface analysis, when the excitation energy of monochromatic light is scanned from low to high in 0.05 eV intervals, photon emission begins at a certain energy value [eV], and this energy threshold is taken as the work function [eV].

[0219] An example of a work function measurement curve obtained under the above conditions is shown in Figure 12. In Figure 12, the horizontal axis represents excitation energy [eV], and the vertical axis represents the 0.5th power of the number of emitted photoelectrons (normalized photon yield) Y. Generally, when the excitation energy value exceeds a certain threshold, the emission of photoelectrons, i.e., the normalized photon yield, increases rapidly, and the work function measurement curve rises sharply. The point at which this rise occurs is defined as the photoelectric work function value [Wf]. This photoelectric work function value [Wf] is taken to be the work function of the sample.

[0220] <Method for measuring glass transition temperature (Tg)> The glass transition temperature (Tg) of the binder resin, toner, etc. is measured using a differential scanning calorimeter "Q1000" (manufactured by TA Instruments) in accordance with ASTM D3418-82. The melting points of indium and zinc are used to correct the temperature of the detector, and the heat of fusion of indium is used to correct the amount of heat. Specifically, 5 mg of a sample is precisely weighed and placed in an aluminum pan, and an empty aluminum pan is used as a reference. Measurements are performed in the measurement range of 30°C to 200°C at a temperature rise rate of 1°C / min. During this temperature rise process, a change in specific heat is obtained in the temperature range of 40°C to 100°C. The glass transition temperature (Tg) is determined as the point where the line midway between the baselines before and after the specific heat change occurs and the differential thermal curve intersect.

[0221] <Method for measuring particle size such as volume-based median diameter of toner> The particle size, such as the volumetric median diameter of the toner, is calculated as follows. The measurement device used is a precision particle size distribution measuring device, "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), equipped with a 100 μm aperture tube and employing the narrow-pore electrical resistance method. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software, "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.). The measurement is performed using an effective number of measurement channels of 25,000. The aqueous electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of approximately 1% by mass, such as "ISOTON II" (manufactured by Beckman Coulter). Before carrying out the measurements and analysis, the dedicated software is set up as follows. On the "Change Standard Measurement Method (SOMME)" screen of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particles 10.0 μm" (Beckman Coulter). Press the "Threshold / Noise Level Measurement Button" to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement." On the "Pulse to particle size conversion setting" screen of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bins, and the particle size range is set to 2 μm to 60 μm. The specific measurement method is as follows.

[0222] (1) Pour 200 mL of the electrolyte solution into a 250 mL round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "Aperture Tube Flush" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube. (2) 30 mL of the above-mentioned electrolyte solution is placed in a 100 mL flat-bottom glass beaker, and 0.3 mL of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) three times by weight with ion-exchanged water is added as a dispersant. (3) Prepare an ultrasonic disperser "Ultrasonic Dispersion System Tetra150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees. Place 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank and add 2 mL of Contaminon N to this water tank. (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized. (5) While the electrolyte solution in the beaker in (4) is being irradiated with ultrasonic waves, 10 mg of toner is added little by little to the electrolyte solution and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C. (6) Using a pipette, the electrolytic solution (5) containing the dispersed toner is dropped into the round-bottom beaker (1) placed in the sample stand, and the measurement concentration is adjusted to 5%. Then, measurements are continued until the number of particles measured reaches 50,000. (7) The measurement data is analyzed using the dedicated software provided with the device, and the volume-based median diameter is calculated.

[0223] <Binder resin composition analysis> -Method for separating binder resin from toner 100 mg of toner was dissolved in 3 ml of chloroform. Next, the insoluble matter was removed by suction filtration using a syringe equipped with a sample processing filter (pore size 0.2 μm to 0.5 μm, such as a Myshoridisk H-25-2 (Tosoh Corporation)). The soluble matter was introduced into a preparative HPLC (apparatus: Japan Analytical Industry Co., Ltd. LC-9130 NEXT preparative column [60 cm], exclusion limits: 20,000 and 70,000, two columns connected), and chloroform eluent was pumped. Once a peak was confirmed in the resulting chromatographic display, fractions with retention times greater than 2,000 molecular weight were collected using a monodisperse polystyrene standard sample. The resulting fraction solution was dried and solidified to obtain the binder resin.

[0224] - Identification of binder resin components and measurement of mass ratios using nuclear magnetic resonance spectroscopy (NMR) 1 mL of deuterated chloroform is added to 20 mg of toner, and the NMR spectrum of the protons in the dissolved binder resin is measured. From the obtained NMR spectrum, the molar ratio and mass ratio of each monomer are calculated, and the content of the constituent monomer units of the binder resin, such as styrene acrylic resin, can be determined. For example, in the case of a styrene-acrylic copolymer, the composition ratio and mass ratio can be calculated based on the peak at around 6.5 ppm derived from the styrene monomer and the peak at around 3.5-4.0 ppm derived from the acrylic monomer. In addition, in the case of a polyester resin and a copolymer of styrene-acrylic resin, the molar ratio and mass ratio are calculated based on the peaks derived from each monomer constituting the polyester resin and the peak derived from the styrene-acrylic copolymer. NMR device: JEOL RESONANCE ECX500 Observation nucleus: Proton Measurement mode: Single pulse Base peak: TMS

[0225] <Measurement of weight average molecular weight Mw, number average molecular weight Mn, and peak molecular weight> The molecular weight distribution (weight average molecular weight Mw, number average molecular weight Mn, peak molecular weight) of a resin or the like is measured by gel permeation chromatography (GPC) 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 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of components soluble in THF is 0.8 mass%. This sample solution is used for measurements under the following conditions. Apparatus: HLC8120GPC (detector: RI) (Tosoh Corporation) Column: Shodex KF-801, 802, 803, 804, 805, 806, 807 (7 columns, manufactured by Showa Denko Co., Ltd.) Eluent: tetrahydrofuran (THF) ·Flow rate: 1.0ml / min Oven temperature: 40.0℃ Sample injection volume: 0.10 ml To calculate the molecular weight of a sample, a molecular weight calibration curve prepared using standard polystyrene resins (for example, trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500", manufactured by Tosoh Corporation) is used.

[0226] <Developing roller impedance> In impedance measurement, 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 made for two responses: one with no phase shift 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). The distance from the origin to the plot is the impedance. The value is calculated as the luminance 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.

[0227] The method, device and conditions for measuring the impedance of the developing roller will be described below. (Method for measuring the impedance of the developing roller) 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.

[0228] 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.

[0229] 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.

[0230] 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.

[0231] It is preferable to form a thin metal film electrode approximately 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 for 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 allows impedance measurement to be performed without being affected by fluctuations in the size of the outer edge (outer diameter for cylindrical developing rollers) in the cross section perpendicular to the longitudinal direction of the developing roller or by the surface shape. Aluminum foil, metal tape, etc. can be used as the metal sheet.

[0232] (Conditions for measuring the impedance of the developing roller) 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.

[0233] More specifically, it is as follows. First, as a pretreatment, a measurement electrode was created by vacuum vapor deposition of platinum onto the developing roller while it was rotating. Vacuum deposition was performed using a vacuum deposition device with a mechanism for gripping the base of the roller (the object to be deposited) and rotating it circumferentially. The roller rotation speed, deposition distance, and deposition time were controlled to deposit a film thickness of 100 nm or more. A 1.5 cm wide electrode was created using masking tape. By forming the electrode with a 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.

[0234] Next, an aluminum sheet was wrapped tightly around the electrode, and the aluminum sheet was connected to the measurement electrodes of an impedance measuring device (product names: Solartron 1260 and Solartron 1296, manufactured by Solartron Corporation) and a high-voltage system (product names: 6792 and HVA-500, manufactured by Toyo Corporation).

[0235] 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 resin 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 resin layer 52.

[0236] 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 resin layer, 64 is the platinum vapor deposition layer, and 65 is the aluminum sheet. As shown in Figure 6, it is important to sandwich the resin layer between the conductive substrate and the measurement electrode.

[0237] 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.

[0238] 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 was obtained in Hz. And, at a frequency of 1.0 x 10 0 ~1.0×10 1 The minimum impedance value in Hz was confirmed. The impedance was measured at the center of the developing roller in the longitudinal direction.

[0239] <Surface potential measurement> In an environment with a temperature of 23°C and a relative humidity of 50%, a corona discharger with a 3.0 mm wide grid was placed so that the distance between the grid and the outer surface of the developing roller was 1.0 mm and the width direction of the grid was aligned with the axial direction of the developing roller. A voltage of 8 kV was applied to the grid, and the corona discharger was moved relative to the developing roller in the axial direction at a speed of 400 mm / s to charge the outer surface of the developing roller. The potential of the outer surface 0.06 seconds after passing the grid was measured, and the degree of overcharging (charge-up) of the toner was evaluated.

[0240] The surface potential of the developing roller can be measured, for example, by the device shown in Figure 8. Both ends of the substrate 82 of the developing roller 81 are held by chucks 83, and a measuring unit 86, which has a corona discharger 84 and a surface potential meter 85 arranged in parallel at an interval of 25 mm, is placed facing the surface of the developing roller 81 at a distance of 1.0 mm. With the developing roller 81 stationary, a voltage of 8 kV is applied to the grid part of the corona discharger 84, and the measuring unit 86 is moved in the axial direction of the developing roller 81 at a speed of 400 mm / sec., and the measuring unit 86 is measured at a speed of 0.06 mm / sec from the time when the corona discharger 84 has passed. The surface potential after 2 seconds is measured by the surface potential meter 85. 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.

[0241] More specifically, it is as follows. The surface potential of the developing roller was measured using a charge amount measuring device (product name: DRA-2000L, manufactured by QEA). Specifically, in an environment of 23°C temperature and 50% relative humidity, the grid part of the corona discharger of the charge amount measuring device was positioned so that the gap between the grid part and the outer surface of the developing roller was 1.0 mm. The grid part of the corona discharger of the above device was 3.0 mm wide. Next, a voltage of 8 kV was applied to the corona charger, and the corona charger was moved relative to the developing roller in the axial direction at a speed of 400 mm / sec to charge the surface of the conductive member, and the potential of the outer surface was measured 0.06 sec after passing the grid section. Measurements were taken at eight locations in the longitudinal direction at 45° intervals around the circumference of the developing roller, and the maximum value of all measurements was used.

[0242] <Calculation of various physical properties such as the equivalent circle diameter and wall distance of carbon black dispersed in a resin layer> The circle-equivalent diameter and wall-to-wall distance of the carbon black dispersed in the resin layer were measured by the following method. First, a section (0.5 to 1.0 mm thick) is cut using a razor so that a cross section perpendicular to the longitudinal direction of the developing roller can be observed. If the adhesion between the substrate and the resin layer is high and cutting with a razor is difficult, the entire 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.

[0243] Next, the slice is platinum-deposited, and the resin layer is photographed at 15,000x magnification using a scanning electron microscope (SEM) (trade name: JSM-7800F, manufactured by JEOL Ltd.) to obtain a cross-sectional image. Furthermore, to quantify the cross-sectional images obtained by SEM observation, the cross-sectional images were converted to 8-bit grayscale using image processing software (trade name: Luzex AP, manufactured by Nireco Corporation) to obtain a monochrome image with 256 gradations. Next, the black and white of the image were inverted so that the carbon black in the cross-sectional image appeared white, and then a binarization threshold was set for the brightness distribution of the image based on the algorithm of Otsu's discriminant analysis method, obtaining a binarized image in which the carbon black appeared white and the binder resin appeared black.

[0244] Then, using image processing software (trade name: Luzex AP, manufactured by Nireco Corporation) on the obtained binary image, the equivalent circle diameter and the distance between adjacent wall surfaces of the whitened carbon black portions are calculated. The equivalent circle diameter and the distance between adjacent wall surfaces are calculated. In order to eliminate the uncertainty of the calculated values ​​for the carbon black, which is divided at the top, bottom, left, and right edges of the image, the image region 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), 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 resin layer of the developing roller.

[0245] The number-average diameter of the primary particles of the carbon black dispersed in the resin was measured using a transmission electron microscope (TEM). First, a thin sectioned sample was prepared. A known method can be used for thinning. For example, a sample can be thinned using an ion beam or a diamond knife. In this disclosure, a 40-nm-thick thin sectioned sample for observation was prepared using an ultramicrotome (product name: ULTRACUT-S, manufactured by Leica Microsystems). Then, a transmission electron microscope (product name: H-7100FA, manufactured by Hitachi High-Tech Corporation) was used. TEM images were obtained using the microscope 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 were measured, and the number-average value of the 50 particles was defined as the number-average diameter of the primary particles.

[0246] (Measurement of DBP absorption amount of carbon black) The DBP absorption amount of carbon black was measured for carbon black powder in accordance with Japanese Industrial Standards (JIS) K6217-4.

[0247] (Measurement of pH of carbon black) The pH of the carbon black was measured on the carbon black powder according to ASTM D1512. [Example]

[0248] 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.

[0249] [Toner manufacturing example] [Example of toner particle production] <Aqueous medium preparation process> 14.0 parts of sodium phosphate (Rasa Kogyo Co., Ltd., 12-hydrate) was added to 1000.0 parts of ion-exchanged water in a reaction vessel, and the temperature was maintained at 65 ° C for 1 hour while purging with nitrogen. Using a TK homomixer (Tokushu Kika Kogyo Co., Ltd.), an aqueous calcium chloride solution containing 9.2 parts of calcium chloride (dihydrate) dissolved in 10.0 parts of ion-exchanged water was added all at once while stirring at 12,000 rpm to prepare an aqueous medium containing a dispersion stabilizer. Furthermore, 10% by mass of hydrochloric acid was added to the aqueous medium, and the pH was adjusted to 6.0 to obtain an aqueous medium.

[0250] <Preparation step of polymerizable monomer composition> Styrene: 60.0 parts Carbon black (Nipex 35): 6.0 parts The above materials were placed in an attritor (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.), and further dispersed using zirconia particles having a diameter of 1.7 mm at 220 rpm for 5 hours to prepare a pigment dispersion.

[0251] To this pigment dispersion were added the following materials: Styrene: 11.0 parts n-Butyl acrylate: 29.0 parts Crosslinking agent (divinylbenzene): 0.2 parts Saturated polyester resin: 6.0 parts (Condensation polymer of propylene oxide-modified bisphenol A (2-mol adduct) and terephthalic acid (molar ratio 10:12), glass transition temperature Tg = 68°C, weight average molecular weight Mw = 10,000, molecular weight distribution Mw / Mn = 5.12) Fischer-Tropsch wax (melting point 78°C): 10.0 parts Charge control agent: 0.5 parts (Aluminum compound of 3,5-di-tert-butylsalicylic acid) The mixture was kept at 65°C and uniformly dissolved and dispersed at 500 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a polymerizable monomer composition.

[0252] <Granulation process> While maintaining the temperature of the aqueous medium at 70°C and the rotation speed of the stirring device at 12,000 rpm, the polymerizable monomer composition was added to the aqueous medium, and t-butyl peroxypivalate, a polymerization initiator, was added. While maintaining the rotation speed of the stirrer at 12,000 rpm, granulation was continued for 10 minutes.

[0253] <Polymerization process> The agitator was changed from the high-speed agitator to a propeller agitator blade, and polymerization was carried out for 5 hours while stirring at 150 rpm and maintaining the temperature at 70°C. The temperature was then raised to 95°C and heated for 5 hours to carry out the polymerization reaction, thereby obtaining a toner particle slurry.

[0254] <Cleaning and drying process> After the polymerization process was completed, the toner particle slurry was cooled, and hydrochloric acid was added to the toner particle slurry to adjust the pH of the system to 1.5 or less. After stirring for 1 hour, the toner cake was subjected to solid-liquid separation using a pressure filter. The toner cake was reslurried in ion-exchanged water to form a dispersion again, and then subjected to solid-liquid separation again using a pressure filter. The reslurrying and solid-liquid separation were repeated until the electrical conductivity of the filtrate reached 5.0 μS / cm or less, and finally solid-liquid separation was performed to obtain a toner cake.

[0255] The resulting toner cake was dried in a flash jet dryer (manufactured by Seishin Enterprises), and then fine and coarse particles were removed using a multi-division classifier utilizing the Coanda effect to obtain toner particles. The drying conditions were an inlet temperature of 90°C, a dryer outlet temperature of 40°C, and the toner cake feed rate was adjusted depending on the moisture content of the toner cake so that the outlet temperature did not deviate from 40°C. The volume-based median diameter of the resulting toner particles was 6.7 μm.

[0256] <Fine particles A> As the fine particles A, the fine particles shown in Table 1 below were used.

[0257] [Table 1] In the table, particle size indicates the number average particle size of primary particles. -15 " indicates that

[0258] <Fine particles B> The fine particles listed in Table 2 below were used as fine particle B. For fine particle B1, ET-300W manufactured by Ishihara Sangyo Kaisha Ltd. was used as is, while for B2 to B4, the same product was crushed and classified to obtain the desired particle size.

[0259] [Table 2] In the table, the particle size indicates the number average particle size of primary particles.

[0260] <Toner 1 manufacturing example> To the toner particles (100.0 parts) obtained above, external additives, fine particles A1 (3.6 parts) and fine particles B1 (1.2 parts), were added and mixed using an FM10C (manufactured by Nippon Coke & Engineering Co., Ltd.) The external addition conditions were as follows: the lower blade was set to A0 blade, the gap between the deflector wall was set to 20 mm, the amount of toner particles charged was 1.5 kg, and the rotation speed was set to 66.6 s -1The external addition time was 10 minutes, and the cooling water temperature was 20° C. and the flow rate was 10 L / min. After that, the mixture was sieved through a mesh with an opening of 200 μm to obtain Toner 1. The average particle size of fine particles A1 obtained from the TEM EDX mapping image of the cross section of the obtained toner 1 was 0.06 μm, and the average particle size of fine particles B1 obtained from the SEM EDX mapping image was 48% and 11%. The physical properties of the obtained toner 1 are shown in Table 3.

[0261] [Table 3]

[0262] The calculated particle size of fine particles A indicates the number average length (μm) of fine particles having a signal derived from silicon, and the calculated particle size of fine particles B indicates the number average length (μm) of fine particles having a signal derived from the constituent elements of fine particles B. The Si element coverage indicates the coverage (area %) of fine particles having signals derived from silicon atoms on the toner surface. The fine particle B-derived element coverage indicates the coverage (area %) of fine particles having signals derived from the constituent elements of fine particle B on the toner surface.

[0263] <Production example of toners 2 to 21> Toners 2 to 21 were obtained in the same manner as in the production example of Toner 1, except that the conditions for external addition to the toner particles were changed as shown in Table 3. The physical properties of Toners 2 to 21 obtained are shown in Table 3.

[0264] <Production example of comparative toners 22 to 25> Comparative toners 22 to 25 were obtained in the same manner as in the production example of toner 1, except that the conditions for external addition to the toner particles were changed as shown in Table 4. The physical properties of the obtained comparative toners 22 to 25 are shown in Table 4.

[0265] [Table 4]

[0266] <Developing roller manufacturing example> In this embodiment, a developing roller in which a resin layer is coated on an elastic roller provided with an elastic layer on the outer surface of a base body will be described, but the developing roller is not limited to this configuration.

[0267] [1. Preparation and manufacturing of raw materials for forming resin layer] <1-1. Preparation of raw polyol and manufacturing example> A synthesis example for obtaining a polyurethane resin layer will be shown below.

[0268] [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.

[0269] [Preparing raw polyol] The five raw material polyols A-1 to A-5 shown in Table 5 below were commercially available products.

[0270] [Table 5]

[0271] <1-2. Preparation of raw material isocyanates B-1 to B-3> The raw material isocyanates shown in Table 6 below were prepared.

[0272] [Table 6]

[0273] <1-3. Production Examples of Hydroxyl-Terminated Urethane Prepolymers C-1 to C-3> [Synthesis of hydroxyl-terminated urethane prepolymer C-1] The materials listed in Table 7 below were reacted under a nitrogen atmosphere with 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 hydroxyl-terminated urethane prepolymer C-1.

[0274] [Table 7]

[0275] [Synthesis of Hydroxyl-Terminated Urethane Prepolymers C-2 to C-3] Hydroxyl-terminated urethane prepolymers C-2 and C-3 were prepared using the starting materials listed in Table 8 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-3 are as follows: 1 H-NMR and 13 The molecular weights of the compounds were determined using C-NMR. In Table 8, m, n, and s in the structural formulas (1) and (4) represent the average number of moles added.

[0276] [Table 8]

[0277] For the hydroxyl group-terminated urethane prepolymers C-1 and C-2 containing the structure shown in 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.

[0278] <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 9 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.

[0279] [Table 9]

[0280] [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 10 below in the same manner as in the synthesis of isocyanate group-terminated prepolymer D-1. The chemical structures of these isocyanate-terminated prepolymers D-1 to D-9 were identified using H-NMR and C-NMR. In Table 10, 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.

[0281] [Table 10]

[0282] 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.

[0283] [2. Preparation and manufacturing of resin layer additive raw materials] <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 10 below, which are polyoxyethylene polyoxypropylene alkyl ethers, were commercially available products.

[0284] <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 11 below.

[0285] [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 is 12 moles) 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 11.

[0286] [Table 11]

[0287] [3. Production examples of coating solutions F-1 to F-10 for forming resin layers] <3-1. Preparation of coating solution F-1 for forming resin layer> The materials for resin layer-forming coating solution F-1, the types and amounts of which are listed in Table 12 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, producing resin layer-forming coating solution F-1.

[0288] [Table 12]

[0289] <3-2. Preparation of Coating Solutions F-2 to F-10 for Forming Resin Layer> Resin layer-forming coating solutions F-2 to F-10 were prepared using the following method. First, the hydroxyl-terminated urethane prepolymer, isocyanate-terminated prepolymer, additives, carbon black, and roughening particles listed in Table 13 below were mixed in the same manner as in the preparation of resin 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 resin layer-forming coating solutions F-2 to F-10.

[0290] [Table 13] In the table, parts indicate parts by mass.

[0291] <4. Manufacturing example of developing roller G1> [4-1. Adjustment of the base] 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.

[0292] [4-2. Preparation of Elastic Layer] The substrate was placed in a mold, and an addition-type silicone rubber composition prepared by mixing the materials shown in Table 14 was poured into the cavity formed in the mold.

[0293] [Table 14]

[0294] Next, the mold is heated to vulcanize and harden the silicone rubber at a temperature of 150°C for 15 minutes, and then demolded. Thereafter, the substrate was further heated at 180° C. for 1 hour to complete the curing reaction, thereby obtaining an elastic roller having an elastic layer with a diameter of 11.5 mm provided on the outer periphery of the substrate.

[0295] [4-3. Preparation of resin layer] The elastic roller was oriented with its longitudinal direction in the vertical direction, and its upper end was gripped and immersed (dipped) in the resin 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 for 1 hour in a hot air circulating dryer set at 160°C. In this way, developing roller G-1 was obtained, with a 12 μm-thick resin layer formed on the elastic layer. The physical properties of the resulting developing roller G-1 are shown in Table 15.

[0296] [Table 15-1]

[0297] [Table 15-2]

[0298] The primary particle size indicates the number average size of the primary particles. The minimum impedance is 1.0 x 10 0 Hz~1.0×10 1 This indicates the minimum impedance value in Hz. Note that notations such as "9.12E+06" represent "9.12 x 10 6 " indicates that

[0299] <Manufacturing examples of developing rollers G-2 to G-10> Developing rollers G-2 to G-10 were produced in the same manner as in the manufacturing example of developing roller G-1, except that the coating material for forming the developing roller surface layer was changed to (F-2 to F-10). The physical properties of the resulting developing rollers G-2 to G-10 are shown in Table 15-2.

[0300] <Manufacturing example of comparative developing roller G-11> The types and amounts of materials listed in Table 16 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. 2-butanone (MEK) was then added to adjust the viscosity of the liquid to within the range of 6 to 10 mPa·s, producing resin layer-forming paint F-11. Developing roller G-11 was produced in the same manner as in the manufacturing example for developing roller G-1, except that resin layer-forming paint F-11 was used instead of resin layer-forming paint F-11, and the physical properties were evaluated. The evaluation results are shown in Table 20.

[0301] [Table 16]

[0302] <Manufacturing examples of comparative developing rollers G-12 and G-13> Resin layer forming paints F-12 and F-13 were prepared in the same manner as in the manufacturing example of developing roller G-1, except that the carbon black used in resin layer forming paint F-1 was changed to the material shown in Table 17 below. The results of the evaluation are shown in Table 20.

[0303] [Table 17]

[0304] <Manufacturing Examples of Comparative Developing Rollers G-14 to G-16> Resin layer-forming paints F-14 to F-16 and developing rollers G-14 to G-16 were prepared in the same manner as in the manufacturing example for developing roller G-1, except that the additives used in resin layer-forming paint F-1 were changed to the materials and parts by mass shown in Table 18 below, and their physical properties were evaluated. The evaluation results are shown in Table 20.

[0305] [Table 18]

[0306] <Manufacturing example of comparative developing roller G-17> Resin layer-forming paint F-17 and developing roller G-17 were prepared in the same manner as in the manufacturing example of developing roller G-1, except that the additive used in resin layer-forming paint F-1 was changed to E-4 listed in Table 19 below, and their physical properties were evaluated. The evaluation results are shown in Table 20.

[0307] <Synthesis of Additive E-5> Additive E-5, 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.

[0308] (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.

[0309] 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.

[0310] 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.

[0311] (Synthesis of Polyetheramine E-5) 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.

[0312] The mixture was cooled to 0°C in an ice bath, and 41.4 g of the resulting compound, ketones of the 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 in an open system at room temperature. 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. The mixture was made basic by adding aqueous sodium hydroxide, and the aqueous layer was extracted with dichloromethane, post-treated, and purified using a column to obtain polyetheramine E-5. The structure of R61 of E-5 and the values ​​of v and w are shown in Table 19.

[0313] <Synthesis of resin layer forming paint F-18 and developing roller G-18> Except for changing the additive used in the resin layer-forming paint F-1 to additive E-5, the resin layer-forming paint F-18 and the developing roller G-18 were prepared in the same manner as in the manufacturing example of the developing roller G-1, and the physical properties were evaluated. The evaluation results are shown in Table 20.

[0314] <Synthesis of Additive E-6> 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.

[0315] 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-6. The structure of R71 and the value of x for E-6 are shown in Table 19.

[0316] <Synthesis of resin layer forming paint F-19 and developing roller G-19> Resin layer forming paint F-19 and developing roller G-19 were prepared in the same manner as in the manufacturing example of developing roller G-1, except that the additive used in resin layer forming paint F-1 was changed to additive E-6. The results are shown in Table 20.

[0317] [Table 19]

[0318] [Table 20] The minimum impedance is 1.0 x 10 0 Hz~1.0×10 1 Indicates the minimum impedance value in Hz.

[0319] <Examples 1 to 37 and Comparative Examples 1 to 13> The evaluation was carried out using the combinations of toner and developing roller shown in Tables 21-1 and 21-2, and the evaluation results are shown in Tables 21-1 and 21-2.

[0320] [Table 21-1]

[0321] [Table 21-2]

[0322] 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, LBP-7600C (manufactured by Canon Inc.). The configuration of the modified machine is shown in Figure 10. The modified parts included connecting an external high-voltage power supply 20C in addition to power supplies 14C and 15C, allowing any potential difference to be set between the developing blade and the developing roller, and setting the output rate per unit time to 40 sheets / minute for A4 size paper. The volume resistivity of the developing blade, which is a developer layer thickness regulating member, was 1.0 x 10 -5 Ω·cm.

[0323] The developing device in the process cartridge was also modified to use the combination of toner and developing roller shown in Table 21-1. The process cartridge used was a commercially available Toner Cartridge 318 (black) (manufactured by Canon Inc.). The product toner was removed from the inside of the cartridge, which was then cleaned with an air blower, and 100 g of the toner to be evaluated was then filled in. The developing roller was also replaced with the developing roller to be evaluated. The evaluation was performed by removing the product toner from each of the yellow, cyan, and magenta stations, and inserting yellow, cyan, and magenta cartridges with their remaining toner detection mechanisms disabled.

[0324] <Evaluation of charge injection (amount of injected charge) and injection ratio (initial evaluation of charge imparting property in the table), and evaluation of fogging in non-image areas on the photoreceptor Dr> This evaluation was carried out in a normal temperature and humidity environment (23°C / 50% RH, hereinafter referred to as N / N environment) and a high temperature and high humidity environment (30°C / 80% RH, hereinafter referred to as H / H environment). The above process cartridge, the modified laser printer, and evaluation paper (GFC81 (Canon) A4: 81.4 g / m 2 ) was left in the evaluation environment for 48 hours. First, the potential difference between the developing blade and the developing roller was set to 0 V, and one all-black image was output. Next, an all-white image was output using the same settings, and the device was stopped during image formation. The process cartridge was removed from the main body, and the toner charge amount on the developing roller immediately after it had passed the developing blade was measured.

[0325] The charge amount on the developing roller was measured using a Faraday cage 40, shown in the perspective view of Figure 11. The inside (right side of the figure) was depressurized so that the toner on the developing roller was sucked in, and a toner filter 43 was provided to collect the toner. Reference numeral 41 denotes the suction part, and 42 denotes a holder. The charge amount per unit mass, Q / M (μC / g), was calculated from the mass M of the collected toner and the total charge Q measured directly with a coulomb meter, and this was taken as the toner charge amount (Q / M). Next, the potential difference between the developing blade and the developing roller was set to −300 V, and the same evaluation was carried out.

[0326] The change in charge amount Δ charge amount Q / M (unit: μC / g) between when the potential difference is 0V and when it is -300V is divided by the charge amount when it is -300V and multiplied by 100 to obtain the injection ratio (%), which was ranked and evaluated as follows: In this case, the injection ratio represents the ratio of the charge amount obtained by injected charging to the toner charge amount when the potential difference is -300V, and the larger this value, the easier it is to control the charge amount by the potential difference, which is preferable. Evaluation was performed in N / N environment and H / H environment using the following criteria. Rank A: Injection ratio 50% or more Rank B: Injection ratio 40% or more but less than 50% Rank C: Injection ratio 30% or more but less than 40% Rank D: Injection ratio less than 30%

[0327] (Initial Dr. Overlap @N / N) In addition, the fog toner on the photosensitive member of the removed process cartridge after passing the developing roller and before contacting the transfer unit was taped and peeled off with Mylar tape. Then, the tape and the untaped tape were placed on a letter-size XEROX 4200 paper (manufactured by XEROX Corporation, 75 g / m 2 The fog (%) in the non-image area on the photoreceptor was calculated from the difference between the reflectance Ds (%) of the tape and the reflectance Dr (%) of the tape applied without taping, as Dr (%) (= Dr (%) - Ds (%)), and evaluated according to the following criteria. A green filter was used. A: Less than 1.0% B: 1.0% or more and less than 2.0% C: 2.0% or more and less than 3.0% D: 3.0% or more

[0328] (Early Dr. Over-the-Hand) The fog (%) in the non-image area was calculated in the same manner in a high temperature and high humidity environment (30° C. / 80% RH, hereinafter referred to as H / H environment) and evaluated according to the following criteria. A+: Less than 0.3% A: 0.3% or more and less than 0.6% A-: 0.6% or more and less than 1.0% B: 1.0% or more and less than 1.7% B-: 1.7% or more and less than 2.0% C+: 2.0% or more and less than 2.4% C: 2.4% or more and less than 3.0% D: 3.0% or more The toner of the present disclosure exhibited negative chargeability, but Tables 21-1 and 21-2 show the absolute values.

[0329] <Evaluation of charge retention after endurance printing (charge retention evaluation on the front @N / N) and evaluation of fog on non-image areas on the photoreceptor after endurance printing (fog on the Dr after endurance printing on the front @N / N)> Durability evaluation was carried out under the following conditions only for those products that showed no problems in the initial evaluation in the N / N environment. After evaluating the injected charge amount and the injected charge amount distribution, the potential difference between the developing blade and the developing roller was set to -200 V, and 20,000 sheets of images with a print ratio of 0.1% were continuously printed on evaluation paper in an N / N environment. The paper was then left to stand for 48 hours in an N / N environment. The output paper was XEROX 4200 paper (manufactured by XEROX, 75 g / m 2 ) was used.

[0330] Next, the potential difference between the developing blade and the developing roller was set to -300V, and one all-black image was output. Next, an all-white image was output, and the device was stopped during image formation, and the process cartridge was removed from the main body. The fog toner on the photosensitive element of the removed process cartridge after it had passed the D roller and before it came into contact with the transfer unit was taped with Mylar tape and peeled off. Then, the tape and the untaped tape were applied to a sheet of Letter-size XEROX 4200 paper (manufactured by XEROX Corporation, 75 g / m 2 The fog (%) in the non-image area on the photoreceptor was calculated from the difference between the reflectance Ds (%) of the tape and the reflectance Dr (%) of the tape attached without taping, (= Dr (%) - Ds (%)), and the fog on Dr after the durability test was evaluated according to the following criteria. A green filter was used. A: Less than 1.0% B: 1.0% or more and less than 2.0% C: 2.0% or more and less than 3.0% D: 3.0% or more

[0331] (Charge retention rating @N / N) In addition, the toner charge amount on the developing roller immediately after passing the developing blade of the removed process cartridge was measured using a Faraday cage. The obtained toner charge amount (Q / M) was compared with the value obtained before continuous output to calculate the toner charge amount maintenance rate, which was ranked and evaluated as follows: The higher the maintenance rate value, the less change in charge amount due to durability, and the more stable the charging development system. Rank A: Retention rate of 80% or more Rank B: Retention rate between 70% and 80% Rank C: Retention rate between 60% and 70% Rank D: Retention rate less than 60%

[0332] Examples 1 to 37 showed good results in the evaluation of charge injection property and charge retention property after durable output. In particular, the combination of the toner having a configuration in which the toner is moderately coated with highly insulating fine particles A and highly conductive fine particles B, and the fine particles B are smaller than the fine particles A, with the developing roller of the examples showed better results in terms of initial injection property and retention of injection property after durable output.

[0333] It can be seen that the initial injection ratio was low and charge injection properties were not obtained in Comparative Examples 1 to 4, 6 to 9, and 11 to 12. In Comparative Examples 5, 10, and 13, which had good initial injection properties, charge retention properties after durable output were evaluated.

[0334] In Comparative Example 5, initial charge injection properties were obtained, but the charge amount retention rate after durability testing was low, and it can be said that this development system is not stable in charge. In Comparative Examples 10 and 13, the initial injection ratio was low in the H / H environment, and it can be seen that charge injection properties were not obtained.

[0335] The developing roller used in Comparative Example 1 did not achieve the desired impedance value, and therefore did not provide good results. This is thought to be because the ether structure in the polyurethane structure reduced the impedance.

[0336] The developing rollers used in Comparative Examples 2 and 3 also did not achieve the desired impedance values, and poor results were not obtained. The reason for the low impedance values ​​is thought to be that carbon black with a large number average diameter of primary particles and a large DBP absorption amount was used, which resulted in a larger carbon black structure after mill dispersion, a larger dispersed particle size, and a larger wall-to-wall distance.

[0337] The developing roller used in Comparative Example 4 also did not achieve the desired impedance value, and therefore did not produce good results. The reason for the low impedance value is thought to be that the amount of additive was small, which resulted in insufficient dispersion of the conductive filler, and thus the conductive filler formed a conductive path within the surface layer.

[0338] In Comparative Example 5, the surface potential of the developing roller was too high, and therefore poor results were not obtained in the evaluation of charge retention after durability testing. It is believed that this was due to the high surface potential caused by the carbon black being coated with an insulating silane coupling agent, which resulted in excessively charged toner adhering to the surface of the developing roller, causing contamination of the developing roller.

[0339] The impedance of the developing roller was low and the injection charging performance was poor in Comparative Example 6. The reason for the low impedance is thought to be that although a polymer dispersant suitable for dispersing carbon black was used, the dispersibility of the carbon black in the resin was not improved, and the amount of dispersant added was also high, which affected the electrical properties of the resin.

[0340] The developing rollers of Comparative Examples 7 to 9 also had low impedance and poor injection charging properties. The reason for the low impedance is thought to be that the carbon chains of R51, R61, and R71 in structural formula (5), structural formula (6), and structural formula (7) used in Comparative Examples 7 to 9, respectively, exceeded the favorable range, reducing the dispersibility of the carbon black and resulting in low impedance.

[0341] In Comparative Example 10, since there is no insulating fine particle A, the fine particle B and the roller D tend to come into contact with each other. Therefore, it is thought that the charge injected into the fine particle B tends to leak to the roller D.

[0342] In Comparative Example 11, it is believed that the conductivity of titania was low, and therefore sufficient charge injection properties could not be obtained.

[0343] In Comparative Example 12, the fine particles B that serve as injection points were not present, and therefore, charge injection was not possible.

[0344] In Comparative Example 13, it is believed that the highly hygroscopic titanium phosphate fine particles caused a conductive path to be formed at the toner interface, resulting in charge leakage and making it impossible to obtain the desired injection charging property.

[0345] The present disclosure relates to the following configurations. (Configuration 1) A developing device having a developer and a developer carrier that carries the developer, the developer is a toner having toner particles and an external additive; The external additive contains fine particles A and fine particles B, the fine particles A are at least one fine particle selected from the group consisting of silica fine particles and silicone fine particles, the fine particles B are at least one fine particle selected from the group consisting of antimony-tin-based oxide-titanium-based oxide, antimony-titanium-based oxide, antimony-tin-based oxide, indium-tin-based oxide, indium-titanium-based oxide, niobium-tin-based oxide, niobium-titanium-based oxide, and zinc oxide; the developer carrier is a developing roller having a substrate with a conductive outer surface and a resin layer on the outer surface of the substrate, 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%. 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 1.00 x 10 6 is greater than or equal to Ω, and A developing device characterized in that, in an environment of a temperature of 23°C and a relative humidity of 50%, a corona charger having a grid portion with a width of 3.0 mm is arranged so that the distance between the grid portion and the outer surface of the developing roller is 1.0 mm and the direction of the width of the grid portion coincides with the axial direction of the developing roller, a voltage of 8 kV is applied to the grid portion, and the corona charger is 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 is measured 0.06 seconds after the grid portion has passed, the maximum value of the potential is less than 20.0 V. (Configuration 2) When an EDS mapping image of constituent elements of a cross section of the toner is obtained by analyzing the cross section of the toner observed with a transmission electron microscope using energy dispersive X-ray spectroscopy, In a region outside the outline of the toner particle, the number average length of the fine particles having a signal derived from silicon in a normal direction to the outline of the toner particle at a contact point between the fine particles having a signal derived from silicon and the toner particle is 0.02 to 0.20 μm; The developing device according to configuration 1, wherein the number average length of the fine particles having a signal derived from the constituent elements of the fine particles B in the normal direction to the contour of the toner particle at the contact point between the fine particles having a signal derived from the constituent elements of the fine particles B and the toner particle is 0.01 to 0.05 μm. (Configuration 3) The developing device according to Configuration 2, wherein the number average value of the lengths of the fine particles having the signal derived from silicon is greater than the number average value of the lengths of the fine particles having the signal derived from the constituent elements of the fine particles B. (Configuration 4) In an EDS mapping image of constituent elements of the toner surface obtained by analyzing the toner surface observed with a reflection electron microscope using energy dispersive X-ray spectroscopy, the coverage of the toner surface with fine particles having a signal derived from silicon atoms is 30 to 70 area %; 4. The developing device according to any one of Configurations 1 to 3, wherein the coverage of the toner surface with fine particles having signals derived from the constituent elements of the fine particles B is 5 to 30 area %. (Configuration 5) When the work function of the fine particles A is Wa and the work function of the fine particles B is Wb, Wb>4.0 is met, 5. The developing device according to any one of configurations 1 to 4, wherein Wa-Wb>0 is satisfied. (Configuration 6) 6. The developing device according to any one of configurations 1 to 5, wherein the fine particles A are sol-gel silica fine particles. (Configuration 7) 7. The developing device according to any one of configurations 1 to 6, wherein the fine particles B are titanium-based oxide fine particles doped with antimony and tin. (Configuration 8) 8. The developing device according to any one of configurations 1 to 7, wherein the maximum value of the potential is 10.0 V or less. (Configuration 9) 9. The developing device according to any one of configurations 1 to 8, wherein the resin layer contains polyurethane. (Configuration 10) 10. The developing device according to any one of configurations 1 to 9, wherein the resin layer contains polyurethane having a polycarbonate structure. (Configuration 11) 11. The developing device according to claim 10, 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. TIFF2026042350000027.tif138153 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 the 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 12) 12. The developing device according to any one of configurations 1 to 11, wherein the resin layer contains a conductive filler. (Configuration 13) 13. The development apparatus of claim 12, wherein the conductive filler comprises carbon black. (Configuration 14) the arithmetic mean value Rc of the equivalent circle diameter of the carbon black in the resin layer is 60.0 nm or less, 14. The developing device according to claim 13, 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 15) the arithmetic mean value d of the distance between wall surfaces of the carbon black in the resin layer is 80.0 to 150.0 nm; 15. The developing device according to configuration 13 or 14, wherein σd / d is 0.000 to 0.600, where σd is the standard deviation of the distance between the wall surfaces. (Configuration 16) 16. The developing device according to any one of Configurations 13 to 15, wherein the number average particle diameter of the primary particles of the carbon black in the resin layer is 30 nm or less. (Configuration 17) the DBP absorption amount of the carbon black in the resin layer is 90 ml / 100 g or less; 17. The developing device according to any one of Configurations 13 to 16, wherein the carbon black has a pH of 4.0 or less. (Configuration 18) A developing device having a developer and a developer carrier that carries the developer, the developer is a toner having toner particles and an external additive; The external additive contains fine particles A and fine particles B, the fine particles A are at least one fine particle selected from the group consisting of silica fine particles and silicone fine particles, The conductivity of the particle B determined by impedance measurement is 1.0 × 10 -5 ~1.0×10 2 S / m, the developer carrier is a developing roller having a substrate with a conductive outer surface and a resin layer on the outer surface of the substrate, 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%. 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 1.00 x 10 6 is greater than or equal to Ω, and A developing device characterized in that, in an environment of a temperature of 23°C and a relative humidity of 50%, a corona charger having a grid portion with a width of 3.0 mm is arranged so that the distance between the grid portion and the outer surface of the developing roller is 1.0 mm and the direction of the width of the grid portion coincides with the axial direction of the developing roller, a voltage of 8 kV is applied to the grid portion, and the corona charger is 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 is measured 0.06 seconds after the grid portion has passed, the maximum value of the potential is less than 20.0 V. (Configuration 19) The developing device is a developer layer thickness regulating member that contacts the developer carrier and regulates the layer thickness of the developer carried on the developer carrier; a contact point electrically connected to the developer layer thickness regulating member; and the contact is electrically connected to a main body contact of the main body of the electrophotographic image forming apparatus when the developing device is mounted in the main body of the electrophotographic image forming apparatus, and enables a predetermined voltage to be applied to the developer layer thickness regulating member, The volume resistivity of the developer layer thickness regulating member is 1.0×10 6 Ω·cm or less, 19. The developing device according to any one of Configurations 1 to 18. (Configuration 20) The developing device according to any one of Structures 1 to 19, wherein the resin layer contains 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): TIFF2026042350000028.tif97168 In structural formula (5), R51 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, and t and u represent the average number of moles added, each independently representing a number of 1 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 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 or more. (Configuration 21) A process cartridge configured to be detachably mounted in a main body of an electrophotographic image forming apparatus, 21. A process cartridge comprising the developing device according to any one of configurations 1 to 20. (Configuration 22) 21. An electrophotographic image forming apparatus comprising the developing device according to any one of Configurations 1 to 20.

Claims

1. A developing device having a developer and a developer carrier that carries the developer, the developer is a toner having toner particles and an external additive; The external additive contains fine particles A and fine particles B, the fine particles A are at least one fine particle selected from the group consisting of silica fine particles and silicone fine particles, the fine particles B are at least one fine particle selected from the group consisting of antimony-tin-based oxide-titanium-based oxide, antimony-titanium-based oxide, antimony-tin-based oxide, indium-tin-based oxide, indium-titanium-based oxide, niobium-tin-based oxide, niobium-titanium-based oxide, and zinc oxide; the developer carrier is a developing roller having a substrate with a conductive outer surface and a resin layer on the outer surface of the substrate, 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%. 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 1.00 x 10 ６ is greater than or equal to Ω, and A developing device characterized in that, in an environment of a temperature of 23°C and a relative humidity of 50%, a corona discharger having a grid portion 3.0 mm wide is disposed so that the distance between the grid portion and the outer surface of the developing roller is 1.0 mm and the direction of the width of the grid portion coincides with the axial direction of the developing roller, a voltage of 8 kV is applied to the grid portion, and the corona discharger is 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 is measured 0.06 seconds after the grid portion has passed, the maximum value of the potential is less than 20.0 V.

2. When an EDS mapping image of constituent elements of a cross section of the toner is obtained by analyzing the cross section of the toner observed with a transmission electron microscope by energy dispersive X-ray spectroscopy, In a region outside the outline of the toner particle, a number-average length of the fine particles having a signal derived from silicon in a normal direction to the outline of the toner particle at a contact point between the fine particles having a signal derived from silicon and the toner particle is 0.02 to 0.20 μm; The developing device according to claim 1, wherein the number average length of the fine particles having a signal derived from the constituent elements of the fine particles B in the normal direction to the contour of the toner particle at the point of contact between the fine particles having a signal derived from the constituent elements of the fine particles B and the toner particle is 0.01 to 0.05 μm.

3. 3. The developing device according to claim 2, wherein the number average value of the lengths of the fine particles having the signal derived from silicon is greater than the number average value of the lengths of the fine particles having the signal derived from the constituent elements of the fine particles B.

4. In an EDS mapping image of the constituent elements of the toner surface, which is obtained by analyzing the toner surface observed with a reflection electron microscope using energy dispersive X-ray spectroscopy, the coverage of the toner surface with fine particles having a signal derived from silicon atoms is 30 to 70 area %; 2. The developing device according to claim 1, wherein the coverage of the toner surface with the fine particles having signals derived from the constituent elements of the fine particles B is 5 to 30 area %.

5. When the work function of the fine particles A is Wa and the work function of the fine particles B is Wb, Wb>4.0 is satisfied, 2. The developing device according to claim 1, wherein Wa-Wb>0 is satisfied.

6. 2. The developing device according to claim 1, wherein the fine particles A are sol-gel silica fine particles.

7. 2. The developing device according to claim 1, wherein said fine particles B are titanium-based oxide fine particles doped with antimony and tin.

8. 2. The developing device according to claim 1, wherein the maximum value of the potential is 10.0 V or less.

9. The developing device according to claim 1 , wherein the resin layer comprises polyurethane.

10. 2. The developing device according to claim 1, wherein the resin layer comprises polyurethane having a polycarbonate structure.

11. The developing device according to claim 10 , 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, provided that R11 and R12 are different from each other, and R13 is a group consisting of R11 and R12. m and n are 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.

12. The developing device according to claim 1 , wherein the resin layer contains a conductive filler.

13. 13. The development apparatus of claim 12, wherein the conductive filler comprises carbon black.

14. the arithmetic mean value Rc of the equivalent circle diameter of the carbon black in the resin layer is 60.0 nm or less, 14. The developing device according to claim 13, wherein σc / Rc is 0.000 to 0.650, where σc is the standard deviation of the equivalent circle diameter of said carbon black.

15. an arithmetic mean value d of the distance between wall surfaces of the carbon black in the resin layer is 80.0 to 150.0 nm; 14. The developing device according to claim 13, wherein σd / d is 0.000 to 0.600, where σd is the standard deviation of the distance between the wall surfaces.

16. 14. The developing device according to claim 13, wherein the number average particle diameter of the primary particles of the carbon black in the resin layer is 30 nm or less.

17. the carbon black in the resin layer has a DBP absorption of 90 ml / 100 g or less; 14. The developing device according to claim 13, wherein the carbon black has a pH of 4.0 or less.

18. A developing device having a developer and a developer carrier that carries the developer, the developer is a toner having toner particles and an external additive; The external additive contains fine particles A and fine particles B, the fine particles A are at least one fine particle selected from the group consisting of silica fine particles and silicone fine particles, The conductivity of the fine particles B determined by impedance measurement is 1.0×10 －５ ~1.0 x 10 ２ S / m, the developer carrier is a developing roller having a substrate with a conductive outer surface and a resin layer on the outer surface of the substrate, 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%. 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 1.00 x 10 ６ is greater than or equal to Ω, and 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 maximum value of the potential when measured 0.06 seconds after passing the grid portion was less than 20.0 V. A developing device characterized in that:

19. The developing device is a developer layer thickness regulating member that contacts the developer carrier and regulates the layer thickness of the developer carried on the developer carrier; a contact point electrically connected to the developer layer thickness regulating member; and the contact is electrically connected to a main body contact of the main body of the electrophotographic image forming apparatus when the developing device is mounted in the main body of the electrophotographic image forming apparatus, and enables a predetermined voltage to be applied to the developer layer thickness regulating member, The volume resistivity of the developer layer thickness regulating member is 1.0×10 ６ Ω cm or less, The developing device according to claim 1 .

20. 14. The developing device according to claim 13, wherein the resin layer contains 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): In structural formula (5), R51 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, and t and u represent the average number of moles added, each independently representing a number of 1 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 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 or more.

21. A process cartridge configured to be detachably mounted in a main body of an electrophotographic image forming apparatus, A process cartridge comprising the developing device according to any one of claims 1 to 20.

22. An electrophotographic image forming apparatus comprising the developing device according to any one of claims 1 to 20.

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