Electrophotographic roller, process cartridge, and electrophotographic image forming apparatus

Abstract

To provide an electrophotographic roller that can more reliably reduce leakage of electric charges of toner to an electrophotographic roller, even in an electrophotographic image forming apparatus applying high voltage to a developing blade.SOLUTION: An electrophotographic roller 10 has a substrate 11 having a conductive outer surface, and a resin layer 12 on the outer surface of the substrate. The resin layer includes polyurethane having a polycarbonate structure. When specific AC voltage is applied to the outer surface of the electrophotographic roller while changing the AC voltage between specific frequencies, an impedance at frequencies from 1.0×100 to 1.0×101 Hz is 1.00×106 Ω or more. When a corona discharger having a grid part is relatively moved at a speed of 400 mm / sec along an axial direction of the electrophotographic roller to charge the outer surface of the electrophotographic roller with electricity, and the electric potential of the outer surface is measured 0.06 seconds after the passing of the grid part, the maximum value of the electric potential is less than 20.0 V.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] As the process speed of electrophotographic image forming apparatuses becomes ever faster, it is considered to apply a high voltage to the developing blade in contact with the developing roller to make the toner carry electric charge more quickly. Here, one of the problems when applying a high voltage to the developing blade is the leakage of electric charge to the developing roller.

[0003] Patent Document 1 discloses a developing roller having a surface layer containing polyurethane having an oxyalkylene structure, an oxyalkylene structure having a methyl group in a side chain, and a structure having a polycarbonate portion between two adjacent urethane bonds. Patent Document 1 discloses that the development roller can be made to have a high resistance by introducing a specific structure having a polycarbonate structure into the surface layer, and as a result, charge leakage from the toner to the development roller can be effectively suppressed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-191316 A Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, the present inventors have considered applying the developing roller according to Patent Document 1 to an electrophotographic image forming apparatus equipped with a developing blade capable of applying a higher voltage. However, the developing roller according to Patent Document 1 in the electrophotographic apparatus sometimes causes charge leakage from the toner into which charge is injected by the developing blade to the developing roller. The leakage of charge from the toner to the developing roller causes a decrease in the charge of the toner. When the charge of the toner decreases, a decrease in image density or toner transfer to a solid white image on paper, which is a deterioration in image quality known as "fogging," may occur. In particular, as the process speed of an electrophotographic image forming apparatus increases, the occurrence of decrease in image density and fogging becomes more noticeable. At least one aspect of the present disclosure is directed to providing an electrophotographic roller capable of more reliably reducing leakage of toner charge to the electrophotographic roller even in an electrophotographic image forming apparatus that applies a high voltage to a development blade. At least one aspect of the present disclosure is directed to providing a process cartridge capable of providing a high-quality electrophotographic image even in an electrophotographic image forming apparatus having a high process speed. At least one aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus capable of providing a high-quality electrophotographic image even in a high process speed. [Means for solving the problem]

[0006] According to at least one embodiment of the present disclosure, a substrate having an electrically conductive outer surface; a resin layer on the outer surface of the substrate. The resin layer contains polyurethane having a polycarbonate structure, A metal film was provided directly on the outer surface of the electrophotographic 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 in amplitude and a frequency of 1.0×10 -1 ~1.0×10 5 Hz. When the frequency is 1.0×10 0 ~1.0×10 1 Impedance at Hz is 1.00 x 10 6 Ω or more, and An electrophotographic roller is provided in which, in an environment of a temperature of 23° C. and a relative humidity of 50%, a corona discharger having a grid portion having a width of 3.0 mm is disposed so that the distance between the grid portion and the outer surface of the electrophotographic roller is 1.0 mm and the direction of the width of the grid portion coincides with the axial direction of the electrophotographic 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 electrophotographic roller at a speed of 400 mm / sec to charge the outer surface of the electrophotographic 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.

[0007] According to at least one aspect of the present disclosure, there is provided a process cartridge configured to be detachably mountable to a main body of an electrophotographic image forming apparatus, the process cartridge including the electrophotographic roller described above.

[0008] Further, according to at least one aspect of the present disclosure, An electrophotographic image forming apparatus having a photoconductor and a developing roller that supplies a developer to an electrostatic latent image formed on the photoconductor, An electrophotographic imaging apparatus is provided, wherein the developing roller is the electrophotographic roller described above. Effect of the Invention

[0009] According to at least one aspect of the present disclosure, an electrophotographic roller capable of more reliably reducing leakage of toner charge to the electrophotographic roller can be obtained even in an electrophotographic image forming apparatus that applies a high voltage to a developing blade. Also, according to at least one aspect of the present disclosure, a process cartridge capable of providing high-quality electrophotographic images even in an electrophotographic image forming apparatus having a high process speed can be obtained. Also, according to at least one aspect of the present disclosure, an electrophotographic image forming apparatus capable of providing high-quality electrophotographic images even in a high process speed can be obtained. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of an electrophotographic roller. [Diagram 2] FIG. 4 is a schematic cross-sectional view showing another example of an electrophotographic roller. [Diagram 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. [Diagram 5] FIG. 4 is a schematic diagram showing a state in which measurement electrodes are formed on an electrophotographic roller. [Figure 6] FIG. 2 is a cross-sectional view of an electrophotographic roller and a measuring electrode. [Figure 7] FIG. 1 is a schematic diagram of an impedance measurement system. [Figure 8] FIG. 2 is a schematic diagram showing an example of an apparatus for measuring the surface potential of an electrophotographic roller. [Figure 9] FIG. 2 is a schematic diagram of a circuit for measuring a leakage current flowing from a toner to an electrophotographic roller. [Figure 10] FIG. 1 is a schematic diagram of an electrophotographic image forming apparatus for image evaluation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the present disclosure, the description of "XX or more and YY or less" or "XX to YY" expressing a numerical range means 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 arbitrarily combined. In addition, in the present disclosure, 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.

[0012] The present inventors speculate as follows about the reason why the developing roller according to Patent Document 1 cannot sufficiently prevent charge leakage from the toner when combined with a developing blade to which a high voltage is applied. In the developing roller disclosed in Patent Document 1, a specific structure having a polycarbonate structure is introduced into polyurethane to increase the resistance of the surface layer. Meanwhile, to cope with the increase in hardness of the surface layer caused by the introduction of the specific structure having a polycarbonate structure, a specific structure having an oxyalkylene structure is introduced.

[0013] The present inventors presumed that the oxyalkylene structure caused charge leakage from the toner. In other words, they considered that the oxyalkylene structure promoted the movement of charge within the polyurethane. Therefore, the present inventors considered combining a developing roller having a surface layer formed using polyurethane having only a polycarbonate structure (hereinafter referred to as polycarbonate urethane), which is obtained by removing a specific structure including an oxyalkylene structure from the polyurethane of Patent Document 1, with a developing blade to which a high voltage was applied. As a result, although it was possible to prevent charge leakage from the toner to the developing roller, a new problem arose in that the electrical resistance of the surface layer became too high, causing excessively charged toner to adhere to the surface of the developing roller.

[0014] Therefore, the present inventors have studied how to remove excess charge from an excessively charged toner. For example, when they have studied the inclusion of a conductive filler in the surface layer, they have found a new problem that it is difficult to disperse the conductive filler well in polycarbonate urethane that does not have an oxyalkylene structure. If the dispersibility of the conductive filler is insufficient, a conductive path is formed by the conductive filler in the surface layer, which leads to charge leakage, or conversely, the effect of removing excess charge expected from the conductive filler may be insufficient.

[0015] That is, the present inventors recognized that in order to achieve a high level of resolution of the conflicting objectives of preventing charge leakage from toner in a surface layer containing polycarbonate urethane and removing excess charge from overcharged toner, it is necessary to develop a new surface layer that can remove excess charge while maintaining high electrical resistance of the surface layer. Based on this recognition, the present inventors have conducted further research.

[0016] As a result, the inventors have recognized that satisfying the following two requirements for an electrophotographic roller having a substrate with a conductive outer surface and a resin layer containing polyurethane having a polycarbonate structure on the outer surface of the substrate is effective in resolving the above two conflicting issues at a high level.

[0017] Requirement (1) A metal film is provided directly on the outer surface of an electrophotographic roller, and a DC voltage of 50 V is 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%. At the same time, an AC voltage of 50 V in amplitude and at a frequency of 1.0×10 -1 ~1.0×10 5 The frequency is changed between 1.0×10 0 ~1.0×10 1 Impedance at Hz is 1.00×10 6 It is greater than or equal to Ω.

[0018] Requirement (2) In an environment of 23°C temperature and 50% relative humidity, a corona discharger having a grid section with a width of 3.0 mm is placed so that the distance between the grid section and the outer surface of the electrophotographic roller is 1.0 mm and the direction of the width of the grid coincides with the axial direction of the electrophotographic roller. A voltage of 8 kV is applied to the grid section, and the corona discharger is moved relatively along the axial direction of the electrophotographic roller at a speed of 400 mm / sec to charge the outer surface of the electrophotographic roller, and the potential of the outer surface is measured 0.06 seconds after the grid has passed. The maximum value of the potential at this time is less than 20.0 V.

[0019] The above requirements (1) and (2) are explained in detail below. <Technical significance of requirement (1)> Requirement (1) specifies the impedance value of the electrophotographic roller. This impedance is a physical property value that indicates the charge leakage from the toner to the electrophotographic roller. The present inventors measured the current value (leakage current value) that flows through the electrophotographic 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 shows a higher correlation with the impedance value of the electrophotographic roller than the electrical resistance value of the electrophotographic roller. In other words, this shows that it is necessary to consider the effects of not only the resistance component of the electrophotographic roller but also the capacitance component when it comes to charge leakage.This is thought to be because, when the electrical characteristics of an electrophotographic roller are pseudo-represented by an RC parallel circuit, the transient state in which a sufficient amount of charge is stored in the capacitor component and reaches a steady state dominated by the resistance component has a large effect on charge leakage.

[0020] The voltage application condition for impedance measurement was a DC voltage of 50 V superimposed with 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 an assumed maximum value of the shared voltage applied to the electrophotographic roller when a voltage is applied in an electrophotographic image forming apparatus so that a voltage difference of 300 V is applied between the electrophotographic roller and the developing blade.

[0021] Impedance exhibits bias dependency, and has the property of decreasing as the bias increases, but it is known that the degree of decrease varies depending on the electrophotographic roller. In conventional impedance measurements of electrophotographic rollers, a voltage application condition of 1 V AC is generally used, but this condition of 1 V AC is clearly smaller than the voltage (generally several hundred V) applied between the electrophotographic roller and the developing blade in an actual electrophotographic image forming apparatus. Therefore, it is often not possible to simulate the behavior of the electrophotographic roller in an electrophotographic image forming apparatus, and is often not suitable as an impedance measurement condition. Therefore, in the present disclosure, voltage application conditions simulating a 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 imitates a square wave generally used in applying a blade bias to an actual electrophotographic image forming apparatus.

[0022] In this disclosure, the frequency is 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 1.0×10 Hz is a region where the transient state is completed and a steady state dominated by the resistance component is reached. In other words, the effects of both the capacitance component and the resistance component are reflected, and this is a region suitable for grasping the charge leakage from the toner to the electrophotographic roller. 0 ~1.0×10 1 Impedance at Hz is 1.00×10 6 When the toner has a resistance of Ω or more, the charge leakage is low, and the charge leakage from the toner to the electrophotographic roller under a high blade bias is suppressed, and the charge amount of the toner can be prevented from decreasing. As a result, fogging can be suppressed, and good image density stability can be obtained.

[0023] The frequency is 1.0 x 10 0 ~1.0×10 1 The impedance in Hz is preferably 1.40 x 10 6 The impedance is preferably as high as possible, and the upper limit is not particularly limited. For example, the impedance is preferably 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 impedance is preferably in the range of 1.00×106 Ω or more 5.00×1 0 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.

[0024] <Technical significance of requirement (2)> Requirement (2) specifies the surface potential of the electrophotographic roller. The surface potential of the electrophotographic roller indicates the residual charge on the surface of the electrophotographic roller, and is a physical property value that indicates the degree of excessive charging (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 reasons why image density decreases. The first is that excessively charged toner adheres electrically to the surface of the electrophotographic roller, making it impossible to charge the next toner transported to the same location. The second is that after toner is removed from the surface of the electrophotographic roller, residual charges remain on the surface of the electrophotographic roller, making it impossible to charge the next toner transported to the same location.

[0025] In the present disclosure, when a voltage of 8 kV is applied to the grid portion and the corona discharger is moved relatively along the axial direction of the electrophotographic roller at a speed of 400 mm / sec, the potential of the outer surface of the electrophotographic roller 0.06 seconds after the grid portion of the corona discharger passes is confirmed. If the maximum value of the potential of the outer surface is less than 20.0 V, the occurrence of image defects due to excessive charging of toner can be suppressed even in an electrophotographic image forming apparatus with a high process speed in which the time until the toner charged by the developing blade is transported to the photoconductor is shorter. Note that the time 0.06 seconds after the grid portion of the corona discharger passes is simulating a model with a high process speed. The maximum value of the potential of the outer surface is preferably not more than 15.0 V, and more preferably not more than 10.0 V. The lower the maximum value of the potential of the outer surface, the more preferable it is, 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.

[0026] By satisfying the above requirements (1) and (2), it is possible to solve the conflicting problems of preventing charge leakage from the toner to the electrophotographic roller and removing excess charge from the overcharged toner at a high level, thereby suppressing fogging and achieving good image density stability. There are no particular limitations on the means for satisfying the above requirements (1) and (2). Specifically, as described below, the following resin layer materials, conductive filler materials, and additives can be used to improve the dispersibility of the conductive filler.

[0027] The present disclosure will be described in detail below. <Electrophotographic roller> An electrophotographic roller according to at least one embodiment of the present disclosure has a conductive substrate and at least one resin layer on the outer peripheral surface of the substrate. An example of an electrophotographic roller is shown in Fig. 1. The electrophotographic 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 electrophotographic roller is not limited to the form shown in Fig. 1. As another form of the electrophotographic 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 circumferential surface of the base 11.

[0028] [Base] The substrate has a conductive outer surface and functions as a support member for the electrophotographic roller and, in some cases, as an electrode. Specific examples of the substrate preferably have a solid columnar or hollow cylindrical shape.

[0029] The material constituting the substrate can be appropriately selected from those known in the field of electroconductive members for electrophotography and those usable for such electrophotographic rollers. Examples include metals or alloys such as aluminum and stainless steel, carbon steel alloys, conductive synthetic resins, iron, and copper alloys.

[0030] Furthermore, the material constituting the substrate may be subjected to an oxidation treatment or a plating treatment with chromium, nickel, or the like. As the type of plating, either electroplating or electroless plating can be used. From the viewpoint of dimensional stability, electroless plating is preferred. The types of electroless plating 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.

[0031] A primer may be applied to the surface of the substrate in order to improve the adhesion between the substrate and the resin layer. As the primer, 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 the primer material include thermosetting resins and thermoplastic resins, and specifically, materials such as phenolic resins, polyurethanes, acrylic resins, polyester resins, polyether resins, and epoxy resins can be used.

[0032] [Resin layer] The electrophotographic 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 electrophotographic roller. The resin layer may have a binder resin. As the binder resin of the resin layer in the electrophotographic roller, it is preferable to use polyurethane having a polycarbonate structure in order to suppress charge leakage from the toner to the electrophotographic roller. That is, the resin layer contains polyurethane having a polycarbonate structure. Furthermore, in order to suppress charge leakage from the toner to the electrophotographic roller while maintaining a light load on the toner and sufficient wear resistance of the resin layer, it is more preferable to use polyurethane having the structure described below as the binder resin of the resin layer.

[0033] The resin layer contains a polyurethane having a polycarbonate structure, and the polyurethane preferably satisfies at least two of the following (A), (B), and (C). The polyurethane may also satisfy all of the following (A), (B), and (C). (A) The polyurethane has a structure represented by the following structural formula (1) in the molecule: (B) The polyurethane has, in the 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.

[0034] That is, it is preferable that the polyurethane satisfies at least one of the following: 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. [ka]

[0035] In structural formula (1), R11, R12, and R13 represent a divalent hydrocarbon group 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 more (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).

[0036] The structure shown in structural formula (1) is a structure in which a copolymer polycarbonate polyol, in which crystallinity is suppressed by bonding two carbonate groups with two different types of hydrocarbon groups, is reacted with an isocyanate. Because the crystallinity is suppressed, the cohesive energy in the soft segment is small, and it is possible to impart flexibility and high volume resistivity to the resin layer. 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. Therefore, the adhesion of toner, powder, etc. to the surface of the resin layer can be suppressed, and the increase in the electrical resistance value of the surface of the resin layer due to contamination can be suppressed. This makes it easier to charge the toner uniformly.

[0037] 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. When 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 having a polycarbonate structure is not too large, making it easier to maintain the resin layer flexible and with a high electrical resistance. In addition, if the carbon number of R11 and R12 is 9 or less, the amount of carbonate groups in the polyurethane is not too small, and the strength of the polymer can be maintained. In addition, if 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 group represented by R11, R12, and R13 may have a branched structure or a cyclic structure.

[0038] The structures shown in structural formulas (2) and (3) are structures in which a copolymer polyol, which is a copolymer of a polycarbonate structure and a polyester structure, is reacted 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, so that the resin layer can be given abrasion resistance. 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) described above, the resin layer can be given sufficient volume resistivity while having a polar ester group, and charge leakage from the toner to the electrophotographic roller can be more easily suppressed.

[0039] 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 of 1.0 or more. If R31 and R32 each have 3 or more carbon atoms, the amount of carbonate groups and ester groups, which are polar functional groups with strong cohesive energy, in the polyurethane is not too large, and the resin layer can be kept flexible. If 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, and the resin layer can be given abrasion resistance.

[0040] The structure shown by structural formula (4) is a structure in which a highly crystalline polycarbonate polyol in which two carbonate groups are bonded by a single hydrocarbon group is reacted with an isocyanate. This structure is highly crystalline and easily arranged in the soft segment, so that it can impart abrasion resistance and high volume resistivity to the resin layer. By forming a resin layer using a polymer in which the structure shown by structural formula (4) is combined with the structures of the above formulas (1) to (3), the hardness of the resin layer does not become too high and can be easily controlled appropriately.

[0041] 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 expressed, and the resin layer can be provided with wear resistance and high volume resistivity. When R41 has 9 or less carbon atoms, excessive crystallinity can be suppressed, and thus an increase in hardness of the resin layer can be suppressed by further containing at least one of the structures represented by structural formulas (1), (2), and (3) in the polymer.

[0042] The resin layer contains a polymer having a urethane bond, i.e., a polyurethane having a polycarbonate structure, 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.

[0043] The structure of the polymer contained in the resin layer of the electrophotographic roller can be confirmed by, for example, pyrolysis GC / MS, FT-IR, or NMR analysis.

[0044] Polyurethane having a polycarbonate structure can be produced by using (A) a polyol compound and (B) a polyisocyanate compound. Usually, polyurethane is 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.

[0045] In the present disclosure, polyurethane may be synthesized by any of the above methods, but a method in which a hydroxyl-terminated prepolymer obtained by reacting a raw material polyol with an isocyanate and an isocyanate-terminated prepolymer obtained by reacting a raw material polyol with an isocyanate are subjected to a thermal curing reaction is more preferable. The polyurethane having a polycarbonate structure 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 having a polycarbonate structure is more preferably a reaction product of a mixture containing a hydroxyl-terminated prepolymer, an isocyanate-terminated prepolymer, a conductive filler, and an additive.

[0046] When there are many hydroxyl groups, isocyanate groups, or urea bonds, allophanate bonds, isocyanurate bonds, etc., many polar functional groups are present in the polyurethane, which increases the water absorption of the polymer and reduces the volume resistivity of the resin layer, which may lead to charge leakage from the toner to the electrophotographic roller. On the other hand, by thermally curing the above-mentioned hydroxyl-terminated prepolymer and isocyanate-terminated prepolymer, it is possible to obtain a polyurethane with few unreacted polyols and polar functional groups without using an excessive amount of isocyanate.

[0047] (A) Polyol compound The polyol is selected from known polycarbonate polyols and polyester-polycarbonate copolymer polyols. 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.

[0048] 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.

[0049] (B) Polyisocyanate compound The polyisocyanate is selected from known and commonly used ones, for example, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, hydrogenated MDI, polymeric MDI, xylylene diisocyanate (XDI), hexamethylene diisocyanate. (HDI), isophorone diisocyanate (IPDI), etc. Among these, aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, and polymeric MDI are more preferably used. Other polyisocyanates can also be used as long as they do not affect the impedance value and surface potential.

[0050] 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, so-called "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 suppressed.

[0051] 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 further preferably 65 to 75% by mass.

[0052] (Conductive filler) The resin layer preferably contains a conductive filler to obtain electrical conductivity. As the conductive filler in the resin layer, it is more preferable to use an electronic conductive agent. As the electronic conductive agent, it is preferable that the electronic conductive agent is a conductive particle exhibiting electronic conductivity and has a surface functional group capable of interacting with a functional group present in the additive described later. Examples of electronic conductive agents exhibiting these properties include at least one selected from the group consisting of carbon blacks such as furnace black, thermal black, acetylene black, and ketjen black; metal oxide-based conductive particles such as titanium oxide having their surfaces treated with acidic functional groups; and metal-based conductive particles such as aluminum and iron having their surfaces treated with acidic functional groups. Among them, at least one selected from the group consisting of carbon blacks having high stability of surface functional groups is preferably used. The conductive filler preferably contains carbon black. Furthermore, in order to obtain a desired impedance value and surface potential, carbon black having a number average diameter of primary particles of 30 nm or less, which allows higher dispersion in the resin layer, DBP absorption of 90 ml / 100 g or less, and pH of 4.0 or less is particularly preferably used.

[0053] 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 a conductive path. Therefore, it is easy to obtain a sufficiently high impedance. The primary particle diameter of carbon black can be calculated using a transmission electron microscope (TEM). The lower the number-average diameter, the more preferable, and there is no particular lower limit. For example, the number-average diameter of the primary particles of carbon black is more preferably 5 to 30 nm, and more preferably 20 to 28 nm.

[0054] When the DBP absorption of carbon black is 90 ml / 100 g or less, the structure of the carbon black becomes small and it becomes difficult to form a conductive path, so that it is easy to obtain a sufficiently high impedance. The lower the DBP absorption, the more preferable it is, and there is no particular lower limit. For example, the DBP absorption of carbon black is more preferably 30 to 90 ml / 100 g, and more preferably 40 to 60 ml / 100 g.

[0055] When the pH of carbon black is 4.0 or less, the repulsion of the surface functional groups of carbon black provides a dispersion stability effect, and carbon black is less likely to aggregate, 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 2.0 to 4.0, 2.2 to 4.0, or 5.0 to 6.0. 2.8 is more preferred.

[0056] However, even if the number-average diameter of the primary particles of carbon black, DBP absorption amount, and pH are within the above ranges, when polycarbonate urethane is used as the binder resin, it may not be fully dispersed and the desired impedance may not be obtained. 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.

[0057] 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 carbonate bonds and hydrocarbon groups that exist between the two hydroxyl groups of polycarbonate diol is hydrophobic due to the presence of the hydrocarbon groups, and does not easily interact with carbon black. Hydrophobic and hydrophilic are structurally more stable when they are close to each other, so hydrophilic carbon black will be in the vicinity of hydrophilic carbon black. As a result, carbon black tends to aggregate and is difficult to disperse.

[0058] In order to sufficiently disperse carbon black having a primary particle number average diameter, DBP absorption amount, and pH within the above numerical ranges when using polycarbonate urethane as a binder resin, it is more preferable to add the additives described below.

[0059] The carbon black content is preferably added so as to obtain 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 the polyurethane forming the resin layer. When the content is 30 parts by mass or less, the distance between the carbon black particles in the coating liquid is appropriately maintained, the probability of collision due to Brownian motion of the carbon black is reduced, and the carbon black is less likely to aggregate. Therefore, the carbon black is easily dispersed and the dispersion stability is also improved. As a result, the carbon black is well dispersed in the resin layer formed by forming a film from the coating liquid.

[0060] In order to achieve the above specific impedance and surface potential, it is preferable to control the dispersion of carbon black. As for the dispersed particle size of carbon black, the arithmetic mean value Rc of the equivalent circle diameter of carbon black in the resin layer is preferably 60.0 nm or less. And, 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. 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.

[0061] The reason why high impedance and low surface potential can be achieved more easily with the above-mentioned ranges of the equivalent circle diameter and the wall-to-wall distance is presumed to be as follows. When the dispersed particle size is large, there are places where the distance between the walls is close, making it easier for conductive paths to form, resulting in low 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, increasing resistance, and reducing capacitance, resulting in higher impedance. In terms of surface potential, resistance becomes high, the effect of the capacitance component becomes greater, and it becomes possible to lower the surface potential by the amount of charge that can be stored in the pseudo-capacitor component. If the surface of carbon black is coated with an insulating material such as a silane coupling agent, it will no longer be able to function as a pseudo-capacitor, and the impedance and surface potential will Both results are high. In addition, multiple types of carbon black may be used in combination as long as the impedance value and the surface potential are not affected.

[0062] 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 circle equivalent diameter can be changed, for example, by the dispersion state in a mill when preparing the coating liquid for forming the resin layer. Rc and σc tend to increase when the dispersion is weakened, and Rc and σc tend to decrease when the dispersion is strengthened. 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.

[0063] 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 distance can be changed, for example, by the dispersion state in a mill or the like when preparing the coating liquid for forming the resin layer. If the dispersion is weakened, d tends to be small and σd tends to be large, and if the dispersion is strengthened, d tends to be large and σd tends to be small. Therefore, if the dispersion is weak, σd / d tends to be large, and if the dispersion is strong, σd / d tends to be small.

[0064] (Additives) It is also a preferred embodiment 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. As one method for incorporating the above-mentioned additive in the surface layer, a method of incorporating a dispersant in a coating liquid for forming a surface layer can be mentioned. In addition, in the surface layer formed using a coating liquid for forming a surface layer 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), the compound may be incorporated at the end of the polymer chain of polyurethane. Even in such a case, the effect of improving the dispersibility of carbon black can be expected, but it is preferable that the additive is present in the surface layer independently of the polyurethane.

[0065] 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 since it has particularly excellent dispersibility of carbon black and affinity with polycarbonate urethane. [ka]

[0066] 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, each independently representing 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, each independently representing 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).

[0067] Structural formula (5) is polyoxyethylene polyoxypropylene alkyl ether, a polyether monol having a structure in which ethylene oxide and propylene oxide are added together in a block form. The terminal hydroxyl group of this polyether monol interacts with the surface functional group of the conductive filler carbon black through hydrogen bonding, acting as a dispersant for the carbon black. In addition, the structure is also compatible with polycarbonate urethane to enhance its effect as a dispersant for the carbon black.

[0068] Ethylene oxide is introduced into the structure to make the additives uniformly present in the polycarbonate urethane. This is believed to be because the ethylene group in ethylene oxide has good compatibility with the hydrophobic hydrocarbon group in the polycarbonate urethane. Propylene oxide is also introduced into the structure to improve the dispersibility of the conductive filler dispersed in the resin layer. This is believed to be because the side chain methyl group of propylene oxide interacts with the conductive filler, improving the dispersibility of the conductive filler.

[0069] R51, a monovalent hydrocarbon group having 1 to 12 carbon atoms, is introduced into the structure to allow the additive to be uniformly present in the polycarbonate urethane. Being a monovalent hydrocarbon group improves compatibility with the hydrophobic hydrocarbon group in the polycarbonate urethane, allowing the additive to be uniformly present in the polycarbonate urethane. Having 12 or less carbon atoms makes it difficult for steric hindrance to occur with the polycarbonate urethane, making it easier for the additive to be uniformly present. 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 an isocyanate with a polyol. This makes it less likely that the resistance of the tank will decrease.

[0070] Polyoxyethylene polyoxypropylene alkyl ether can be obtained by using a commercially available product or by synthesis. Polyoxyethylene polyoxypropylene alkyl ether can be synthesized by carrying out the following step (A) followed by step (B). Note that step (B) may be carried out on a commercially available product having a structure in which step (A) has already been completed.

[0071] 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 alcohol in the presence of a catalyst at 50 to 200°C, more preferably at 100 to 160°C. Since ethylene oxide has a boiling point of 10.7°C and is in the form of a gas at the above temperature, it is preferable to carry out the reaction 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 hour to 3 hours in order to reduce the amount of unreacted ethylene oxide.

[0072] The catalyst may be an acid catalyst or an alkali catalyst, but is preferably an alkali catalyst in order to facilitate purification after the reaction. Examples of the alkali catalyst 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 of reaction and reaction efficiency, sodium hydroxide and potassium hydroxide are particularly preferred. Examples of the acid catalyst include Bronsted acids such as sulfuric acid and phosphoric acid, and Lewis acids such as stannic chloride and boron trifluoride.

[0073] The amount of the catalyst used is preferably 0.1 to 5 mol% per 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 moisture 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.

[0074] 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 it is preferable to carry out the reaction in a pressurized environment in a sealed container. The catalyst used in step (A) may be used as is, or may be newly added. When a new catalyst is added, it is preferable to use the catalyst used in step (A).

[0075] Structural formula (6) is a polyetheramine (monoamine) with a block-type addition polymerization structure of ethylene oxide and propylene oxide. The amino group at the end of this polyetheramine interacts with the surface functional group of the conductive filler carbon black through hydrogen bonding, acting as a dispersant for the carbon black. In addition, to enhance its effect 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 group of polycarbonate urethane, and is also compatible with polycarbonate urethane.

[0076] The polyether monoamine may be a commercially available product or may be obtained by synthesis. The synthesis of the polyether monoamine may be carried out by carrying out the following step (C) followed by step (D).

[0077] Step (C): Oxidation reaction of the compound of formula (5), which is a secondary alcohol Step (D): Reductive amination of the product obtained in step (C) Step (C) is a reaction to produce a ketone by oxidation of a secondary alcohol. The synthesis of ketones by the oxidation of alcohols can be carried out using heavy metal salts and their derivatives, such as chromic acid and manganese dioxide, or non-heavy metal salt oxidation using hypohalous acids, such as dimethyl sulfoxide (DMSO) and hypochlorous acid.

[0078] Although any method may be used for synthesis, in consideration of the environmental impact of heavy metals, oxidation reactions using hypohalous acids such as dimethyl sulfoxide (DMSO) or hypochlorous acid are preferred. Furthermore, dimethyl sulfoxide (DMSO) reacts explosively at room temperature depending on the electrophilic activation reagent used, so a low temperature of -60°C is required, making the method using hypohalous acids more preferred. 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.

[0079] When using dimethyl sulfoxide (DMSO), an electrophilic activating agent is also required. The electrophilic activating agent increases the electrophilicity of the sulfur in DMSO, allowing it to be subjected to nucleophilic attack by the alcohol hydroxyl group. This nucleophilic attack produces a dimethylalkoxysulfonium salt, which decomposes to produce a ketone and dimethyl sulfide. Examples of electrophilic activating agents include dicyclohexylcarbodiimide (DCC), acetic anhydride, phosphorus pentoxide, sulfur trisulfide-pyridine complex, trifluoroacetic anhydride, oxalyl chloride, and halogens.

[0080] Step (D) is a reductive amination reaction that converts a ketone into an amine. The reaction is divided into two steps. First, a carbonyl group reacts with an amine to generate an iminium cation. Then, a hydride reducing agent attacks the iminium cation with a nucleophilic attack to generate an amine. A borohydride reagent is preferably used as the reducing agent. Examples of the borohydride reagent include sodium cyanoborohydride, sodium triacetoxyborohydride, and 2-picoline-borane, and among these, sodium triacetoxyborohydride and 2-picoline-borane, which are less toxic, are preferred. 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 the structural formula (6) is preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms.

[0081] Structural formula (7) is polyoxyethylene alkyl ether acetic acid. The terminal carboxylic acid in structural formula (7) interacts with the surface functional group of the conductive filler carbon black through hydrogen bonding, and acts as a dispersant for the carbon black. In addition, in order to enhance the effect as a dispersant, R71, a monovalent hydrocarbon group having 1 to 12 carbon atoms, is introduced, resulting in a structure that is easily compatible with the hydrophobic functional group of polycarbonate urethane, and is also compatible with polycarbonate urethane.

[0082] Polyoxyethylene alkyl ether acetic acid can be obtained by synthesis or by using a commercially available product. Polyoxyethylene alkyl ether acetic acid can be synthesized by carrying out the following step (E) followed by step (F). Note that step (F) may be carried out on a commercially available product having a structure in which step (E) has been completed. 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 in the same manner as step (A).

[0083] Step (F) is a step in which a primary alcohol is oxidized to produce a carboxylic acid. Since the oxidation of a primary alcohol produces an aldehyde, which is then further oxidized 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 carboxylic acids by oxidation of alcohols include oxidation with an oxidizing agent and catalytic dehydrogenation with a catalyst. Oxidizing agents include permanganate, chromic acid, ruthenium tetroxide, and hypochlorite. Catalysts for dehydrogenation include palladium, platinum, iridium, rhodium, and manganese.

[0084] The compounds represented by structural formulas (5) to (7) function as dispersants for carbon black and have high affinity with polycarbonate urethane. Usually, surfactants are used to improve the dispersibility and dispersion stability of carbon black. However, the compounds represented by structural formulas (5) to (7) have a small number of functional groups that act on the surface functional groups of carbon black, so their surface activity is weak and they are not generally used. Coupling agents and nonionic surfactants are commonly used as dispersants for carbon black.

[0085] As coupling agents, silane coupling agents, titanate coupling agents, and aluminum coupling agents are used, and as nonionic surfactants, polyester-based and polyether-based ones are used. However, if these dispersants are added to polycarbonate urethane to a level that sufficiently increases the dispersibility of carbon black (50-100% by mass relative to carbon black), the conductivity of the carbon black and binder resin is inhibited. Conversely, if the amount added is at a level that does not inhibit the conductivity of carbon black and binder resin (10-40% by mass relative to carbon black), the dispersibility of carbon black cannot be obtained.

[0086] 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, making it easier to achieve the desired impedance value and surface potential.

[0087] The presence of additives in the resin layer can be confirmed and quantitatively evaluated by the following method. The resin layer of the electrophotographic roller is cut out, and the cut piece is subjected to, for example, 1 H-NMR, 13 By using C-NMR, XPS, and FT-IR, it is possible to detect the carbonate structure of the binder resin, and the ether structure, amine structure, and carboxylic acid structure of the additive in the resin layer, and the ratio can be calculated from the peak ratios, etc. In addition, sections were extracted by soaking them overnight in an organic solvent such as 2-butanone (methyl ethyl ketone; MEK), and the extract and the extracted sections were then 1 H-NMR, 13 By using C-NMR, XPS, and FT-IR, it is possible to calculate the proportion of additives that are incorporated into the resin during the polymerization reaction and the proportion that are not incorporated.

[0088] Examples of the structure in which at least one of the compounds having the structures represented by structural formulas (5) and (6) is bonded to polyurethane (the structure resulting from the reaction during polymerization of polyurethane) 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 the structural formula (6), in polyurethane, the compound having the structure represented by the structural formula (6) is a urea-modified structure.

[0089] [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 can be used. Urethane resin particles, acrylic resin particles, phenolic resin particles, silicone resin particles, polyacrylonitrile resin particles, polystyrene resin particles, polyurethane resin particles, nylon resin particles, polyethylene resin particles, polypropylene resin particles, preferably urethane resin particles. The content of the roughening particles in the resin layer is preferably from 1 to 20% by mass, and more preferably from 5 to 15% by mass.

[0090] The electrophotographic roller may have an elastic layer on the outer surface of the substrate. The electrophotographic roller has an elastic layer between the substrate and the resin layer, for example. The elastic layer is not particularly limited, and any known elastic layer for electrophotographic rollers may be used. For example, a cured product of an addition curing type liquid silicone rubber mixture may be used.

[0091] (Production method) The method of forming the resin layer is not particularly limited, but includes spraying, dip coating, and roll coating. For example, a resin layer can be formed by applying a coating liquid for forming a resin layer to the substrate or the elastic layer formed on the outer surface of the substrate by a known method, and then drying by heating. The conditions for drying by heating are not particularly limited, and examples of the method include drying at 120 to 200°C. The thickness of the resin layer is also not particularly limited, and is preferably 1 to 50 μm, more preferably 5 to 20 μm.

[0092] <Process cartridge and electrophotographic image forming apparatus> The electrophotographic roller according to the present disclosure can be suitably used as a developing roller, a toner supply roller, and a developing sleeve in a process cartridge. FIG. 3 is a schematic cross-sectional view of an example of a process cartridge according to one embodiment of the present disclosure. In FIG. 3, the electrophotographic roller is mounted as a developing roller 14. The process cartridge 22 is configured to be detachable from the main body of an electrophotographic image forming apparatus. The process cartridge 22 is an integrated unit of a developing device 18 including a developing roller 14 and a developing blade 15, a photoconductor 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 the toner 16 having a predetermined thickness is formed on the surface of the developing roller 14 by the developing blade 15.

[0093] The developing roller 14 is in contact with the photoconductor 19, and is driven to rotate at a predetermined peripheral speed ratio with respect to the photoconductor 19. A predetermined bias is applied to the developing roller 14, and the electrostatic latent image on the photoconductor 19 is developed with the toner 16 to be visualized.

[0094] The toner supply roller 17 comes into contact with the developing roller 14, penetrates therein by a predetermined amount, and rotates in the same direction as the rotation direction of the developing roller 14. In addition, a bias of the same potential as that applied to the developing roller 14 is applied to the toner supply roller 17.

[0095] 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 of the developing roller 14. By arranging the developing blade 15 in contact with the developing roller 14, the amount of toner on the developing roller 14 is regulated and made thin, 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.

[0096] FIG. 4 shows an electrophotographic roller as a developing roller of a contact type developing device using one-component toner. 1 is a schematic cross-sectional view showing an example of an electrophotographic image forming apparatus equipped with the toner cartridge 16. The developing device 18 includes a toner 16 as a one-component toner, a developing roller 14, a toner supply roller 17 that supplies the 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 inside the developing device 18, and is placed in contact with the photoconductor 19. The photoconductor 19, the charging roller 20, and the cleaning blade 21 may be provided in the main body of the electrophotographic image forming apparatus. The developing device 18 is provided with toner of each color, black, cyan, magenta, and yellow, enabling color printing.

[0097] The printing operation of the electrophotographic image forming apparatus will be described below. The photoconductor 19 rotates in the direction of the arrow, and is uniformly charged by a charging roller 20 for charging the photoconductor 19. Next, an electrostatic latent image is formed on the surface of the photoconductor 19 by a laser beam 23, which is an exposure means. The electrostatic latent image is visualized as a toner image (developed) by the development device 18, which applies toner 16 from a development roller 14 arranged in contact with the photoconductor 19. The development is a so-called reversal development in which a toner image is formed in the exposed portion.

[0098] The toner image formed on the photoconductor 19 is transferred onto an intermediate transfer body 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 a paper feed roller 27 and a secondary transfer roller 28, and is transported together with intermediate transfer body 25 carrying a toner image to a nip portion 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 a cleaning device 32.

[0099] 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 discharged outside the device, completing the printing operation. Meanwhile, residual toner remaining on the photoconductor 19 without being transferred is scraped off by a cleaning blade 21, which is a cleaning member for cleaning the surface of the photoconductor. The cleaned photoconductor 19 repeats the above printing operation.

[0100] <Impedance> In impedance measurement, the response of the electrophotographic 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 relative to the applied AC voltage. The impedance of the response with no phase shift is plotted on a complex plane as Z' (real part), and the impedance of the response with a phase shift is plotted as Z" (imaginary part), and the distance from the origin to the plot is calculated as the impedance value. When the electrical characteristics of an electrophotographic roller are expressed pseudo-analyzed by an RC parallel circuit, the real part without phase shift indicates the resistance component, and the imaginary part with phase shift indicates the capacitance component. Note that the meaning of the measurement conditions and measured values ​​was explained in the above <Technical significance of requirement (1)>, so it will be omitted in this section.

[0101] The impedance measuring method, measuring device, and measuring conditions are described below. (Method of measuring impedance) The impedance of the electrophotographic 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 an electrophotographic roller and measurement is performed using two terminals, one connected to the electrode and the other connected to the substrate. (2) A method in which an electrophotographic roller is pressed against a metal drum with a constant load and measured at two terminals, one on the metal drum and one on the substrate.

[0102] Although impedance can be measured by either method, method (2) is affected by the nip width and contact area between the electrophotographic roller and the metal drum, so it is necessary to measure with an electrophotographic roller of equivalent hardness. Therefore, in this disclosure, measurement is performed using method (1). The measurement method (1) is described below, but more specific conditions will be described later. In order to eliminate the influence of contact resistance between the electrophotographic roller and the measurement electrode when measuring the impedance, it is preferable to deposit a low-resistance thin film on the surface of the electrophotographic roller and use the thin film as an electrode while using the conductive substrate as a ground electrode to measure the impedance via two terminals.

[0103] Examples of the method for forming the thin film include metal deposition, sputtering, application of a metal paste, and application of a metal tape. Among these, from the viewpoint of reducing the contact resistance with the electrophotographic roller, a method for forming a thin metal film of platinum or palladium by deposition as an electrode is preferred. In the present disclosure, vacuum platinum deposition is adopted.

[0104] When forming a thin metal film on the surface of an electrophotographic roller, in consideration of the simplicity of the process and the uniformity of the thin film, it is preferable to use a vacuum deposition apparatus provided with a mechanism capable of gripping the electrophotographic roller, and for an electrophotographic roller having a cylindrical cross section, to which a rotation mechanism is further added.

[0105] It is preferable to form a thin metal film electrode with a width of about 10 mm in the longitudinal direction of the electrophotographic roller, and connect a metal sheet wrapped around the thin metal film electrode in a direction intersecting the longitudinal direction without any gaps to a measurement electrode protruding from a measurement device to perform the measurement. In the case of a cylindrical electrophotographic roller, it is preferable to use a metal sheet wrapped around the electrophotographic roller in the circumferential direction without any gaps. This makes it possible to perform impedance measurement without being affected by the variation in the size of the outer edge (outer diameter in the case of a cylindrical electrophotographic roller) in the cross section perpendicular to the longitudinal direction of the electrophotographic roller or the surface shape. As the metal sheet, aluminum foil, metal tape, etc. can be used.

[0106] (Impedance measurement conditions) The impedance measuring device 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 may be used. Among these, it is preferable to measure the impedance using an impedance analyzer in the range of electrical resistance of the electrophotographic roller. The impedance measurement conditions are as follows. An impedance measuring device was used, and the impedance was measured at 1.0×10 -1 ~1.0×10 5 The impedance is measured in the frequency range of 100 Hz. The measurement environment is a temperature of 23°C and a relative humidity of 50%. In order to take into account measurement variations, it is preferable to measure at least 9 points in total, 3 points in the longitudinal direction and 3 points in the rotational direction of the electrophotographic roller. The voltage application condition is a DC voltage of 50V superimposed with an AC voltage of 50V.

[0107] <Surface potential> In an environment of 23°C temperature and 50% relative humidity, a corona discharger having a 3.0 mm wide grid portion was positioned so that the distance between the grid portion and the outer surface of the electrophotographic roller was 1.0 mm and the direction of the width of the grid portion coincided with the axial direction of the electrophotographic 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 electrophotographic roller at a speed of 400 mm / sec to charge the outer surface of the electrophotographic roller. The potential of the outer surface 0.06 seconds after passing the grid portion was measured, and the degree of excessive charging (charge-up) of the toner was evaluated.

[0108] The surface potential of the electrophotographic roller can be measured, for example, by the device shown in FIG. Both ends of substrate 82 of electrophotographic roller 81 are held by chucks 83, and measuring unit 86, in which corona discharger 84 and surface potential meter 85 are arranged in parallel with an interval of 25 mm, is arranged facing the surface of electrophotographic roller 81 at a distance of 1.0 mm. With electrophotographic roller 81 stationary, a voltage of 8 kV is applied to the grid portion of corona discharger 84, and measuring unit 86 is moved in the axial direction of electrophotographic roller 81 at a speed of 400 mm / sec, and the surface potential 0.06 seconds after passing by corona discharger 84 is measured by surface potential meter 85. The measurement conditions and the meaning of the measured values ​​have been explained in the above section <Technical significance of requirement (2)>, so they will not be repeated here. EXAMPLES

[0109] The present invention will be described in more detail below with reference to examples, but these are not intended to limit the present invention in any way.

[0110] [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 described below.

[0111] [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 performed using an RI (refractive index) detector as a detector. A calibration curve was created using TSK standard polystyrene 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 for creating a calibration curve. Based on this calibration curve, the number average molecular weight was calculated from the retention time of the obtained measurement sample.

[0112] [Preparation of raw polyol] The 16 raw material polyols A-1 to A-16 shown in Table 1 below were commercially available products. Raw material polyols A-17 and A-18 were synthesized. [Table 1]

[0113] [Synthesis of raw material polyol A-17] Under a nitrogen atmosphere, 100.0 g of 1,3-propanediol, 49.4 g of adipic acid, and 69.5 g of ethylene carbonate were mixed and heated, and the temperature was raised to 200°C, while distilling off the ethylene glycol and water produced in the reaction system. After the ethylene glycol and water were distilled off, 15 ppm of titanium tetraisopropoxide was added, and the polycondensation reaction was further carried out under a reduced pressure of 266.7 Pa. The reaction liquid was cooled to room temperature to obtain raw material polyol A-17. The number average molecular weight of the obtained raw material polyol A-17 was 2030.

[0114] [Synthesis of raw material polyol A-18] Raw material polyol A-18 was produced in the same manner as raw material polyol A-17, except that the starting materials shown in Table 2 below were used. The number average molecular weight of raw material polyol A-18 was 2,040. [Table 2]

[0115] <1-2. Preparation of raw material isocyanates B-1 to B-6> The raw material isocyanates shown in Table 3 below were prepared. [Table 3]

[0116] <1-3. Production Examples of Hydroxyl-Terminated Urethane Prepolymers C-1 to C-14> [Synthesis of hydroxyl-terminated urethane prepolymer C-1] Under a nitrogen atmosphere, the materials shown in Table 4 below were reacted by heating and stirring at a temperature of 90° C. for 3 hours. Then, 2-butanone (MEK) was added to the resulting reaction product to prepare a solution with a solid content of 50 parts by mass, thereby producing hydroxyl group-terminated urethane prepolymer C-1. [Table 4]

[0117] [Synthesis of hydroxyl-terminated urethane prepolymers C-2 to C-14] Hydroxyl-terminated urethane prepolymers C-2 to C-14 were prepared using the starting materials shown in Table 5 below in the same manner as in the synthesis of hydroxyl-terminated urethane prepolymer C-1. The chemical structures of these hydroxyl-terminated urethane prepolymers C-1 to C-14 are as follows: 1 H-NMR and 13 The molecular weights of the compounds were determined by C-NMR. In Table 5, m, n, o, p, q, r, and s in the structural formulas (1), (2), (3), and (4) are the average mole numbers added. [Table 5] For the hydroxyl-terminated urethane prepolymers C-1 to C-14 containing the structure represented by structural formula (1) in the molecule, R13 in structural formula (1) was the same as R12. In the tables, the description "x, y = A", such as m and n = 6.9, indicates that the average number of moles added of x and y is A. The same applies to the following tables.

[0118] <1-4. Production Examples of Isocyanate-Terminated Prepolymers D-1 to D-9> [Synthesis of isocyanate-terminated prepolymer D-1] In a nitrogen atmosphere, the materials shown in Table 6 below were reacted by heating and stirring at a temperature of 90° C. for 3 hours. Then, 2-butanone (MEK) was added to the resulting reaction product to prepare a solution with a solid content of 50 parts by mass, thereby producing isocyanate-terminated prepolymer D-1. [Table 6]

[0119] [Synthesis of isocyanate-terminated prepolymers D-2 to D-9] Isocyanate-terminated prepolymers D-2 to D-9 were prepared using the types and amounts of starting materials shown in Table 7 below in the same manner as in the synthesis of isocyanate-terminated prepolymer D-1. The chemical structures of these isocyanate-terminated prepolymers D-1 to D-9 are as follows: 1 H-NMR and 13 The molecular weights of the compounds were determined by C-NMR. In Table 7, m, n, o, p, q, r, and s in the structural formulas (1), (2), (3), and (4) are the average mole numbers added. [Table 7] For isocyanate-terminated prepolymers D-2 and D-3 containing the structure shown in 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. Also, for isocyanate-terminated prepolymer D-9 containing the structure shown in structural formula (1) in the molecule, R13 in structural formula (1) was the same as R12.

[0120] [2. Preparation and manufacturing of resin layer additive raw materials] <2-1. Preparation and manufacturing examples of polyoxyethylene polyoxypropylene alkyl ethers E-1 to E-7> [Preparation of polyoxyethylene polyoxypropylene alkyl ether] Additives E-1 to E-5, which are polyoxyethylene polyoxypropylene alkyl ethers, shown in Table 8 below, were purchased commercially, while polyoxyethylene polyoxypropylene alkyl ethers E-6 and E-7 were synthesized.

[0121] [Synthesis of polyoxyethylene polyoxypropylene alkyl ether E-6] 169.3 g of 1-octanol (Tokyo Chemical Industry Co., Ltd.) and 3.0 g of potassium hydroxide were charged into an autoclave equipped with a stirrer, temperature controller, and automatic charger, and dehydration was carried out for 30 minutes at 110°C and 1.2 kPa. After completion of dehydration, nitrogen replacement was carried out, and the temperature was raised to 150°C, after which 858.0 g of ethylene oxide (15 mol relative to alcohol) was charged. The reaction was carried out for 1 hour at 150°C, and an ethylene oxide adduct with an average added mole number of 15 mol was obtained.

[0122] The obtained ethylene oxide adduct was cooled to 130°C, and then 1132.6 g of propylene oxide (based on 15 mol of alcohol) was added. After the addition was completed, the reaction was carried out at 130°C for 5 hours to obtain a polyoxyethylene polyoxypropylene octyl 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.

[0123] The obtained polyoxyethylene polyoxypropylene octyl ether adduct was heated to 80°C. The mixture was cooled and stirred at 2.5 kPa for 30 minutes to remove unreacted ethylene oxide and propylene oxide. Then, 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 octyl ether E-6. The structure of R51 and the values ​​of t and u in E-6 are shown in Table 8.

[0124] [Synthesis of polyoxyethylene polyoxypropylene alkyl ether E-7] 550.0 g of polyoxyethylene methyl ether (product name: BROWNON MP-550, manufactured by Aoki Oil Chemical Industry Co., Ltd., the average number of moles of ethylene oxide added relative to alcohol is 12 moles) and 3.0 g of potassium hydroxide were charged into an autoclave equipped with a stirrer, a temperature control device, and an automatic charger, and dehydration was carried out for 30 minutes at 110°C and 1.2 kPa. After completion of dehydration, nitrogen replacement was carried out, the temperature was raised to 130°C, and then 871.2 g of propylene oxide (relative to alcohol: 12 moles) was charged. After completion of charging, a reaction was carried out at 130°C for 4 hours to obtain a polyoxyethylene polyoxypropylene methyl ether adduct, which is a block polymer with an average number of moles added of 12 moles of ethylene oxide and 12 moles of propylene oxide.

[0125] The obtained polyoxyethylene polyoxypropylene methyl ether adduct was cooled to 80°C, and unreacted propylene oxide was removed at 2.5kPa for 30 minutes. Then, 6.0g of 90% lactic acid was added to the autoclave, and the mixture was stirred at 80°C for 30 minutes, followed by extraction to obtain polyoxyethylene polyoxypropylene methyl ether E-7. The structure of R51 and the values ​​of t and u in E-7 are shown in Table 8. [Table 8]

[0126] <2-2. Preparation of polyetheramine, manufacturing example> [Preparation of polyetheramine] The polyetheramines E-8 and E-9 shown in Table 9 below, which are used as additives, were purchased commercially. Polyetheramine E-10 was synthesized.

[0127] [Synthesis of polyetheramine E-10] A three-neck flask was equipped with a stirrer, and 1658 g of polyoxyethylene polyoxypropylene octyl ether and 460 ml of acetic acid were added. 600 ml of 2 mol / l aqueous sodium hypochlorite solution was added dropwise over 1 hour. The reaction vessel was placed in an ice bath to cool the temperature to within the range of 15 to 25°C. After the dropwise addition was completed, stirring was continued for 1 hour. Dichloromethane was added to the resulting liquid, and the aqueous layer was extracted, post-treated, and purified using a column to obtain a compound in which the secondary alcohol was ketonized.

[0128] The mixture was cooled to 0°C in an ice bath, and 250ml of a methanol-acetic acid mixed solution (volume ratio 10:1) was added to 41.4g of the compound obtained by ketonizing the secondary alcohol, and 2.7g of 2-picoline-borane was added. The ice bath was removed, and the mixture was stirred overnight at room temperature in an open system. After concentration, the mixture was cooled to 0°C, and 360ml of 35% aqueous hydrochloric acid was added, and the mixture was stirred at room temperature for 2 hours. An aqueous sodium hydroxide solution was added to make the mixture basic, and the aqueous layer was extracted with dichloromethane, post-treated, and purified using a column to obtain polyetheramine E-10. The structure of R61 of E-10 and the values ​​of v and w are shown in Table 9. [Table 9]

[0129] <2-3. Preparation and manufacturing example of polyoxyethylene alkyl ether acetic acid> [Preparation of polyoxyethylene alkyl ether acetic acid] The polyoxyethylene alkyl ether acetic acid E-11 shown in Table 10 below as an additive was purchased commercially. Polyoxyethylene alkyl ether acetic acids E-12 and E-13 were synthesized.

[0130] [Synthesis of polyoxyethylene alkyl ether acetic acid E-12] Polyoxyethylene methyl ether (Product name: Brownon MP-550, Aoki Yushika) 55.0 g of ethylene oxide (12 mol / l average number of moles added per alcohol) was mixed with 510 ml of 1 mol / l aqueous sodium hydroxide solution, 71.1 g of potassium permanganate was added, and the mixture was stirred at room temperature for 6 hours. The mixture was stirred for 1 hour to quench the excess potassium permanganate, and the by-product manganese oxide was filtered off. The aqueous layer was extracted with dichloromethane and purified to obtain polyoxyethylene methyl ether acetic acid E-12. The structure of R71 in E-12 and the value of x are shown in Table 10.

[0131] [Synthesis of polyoxyethylene alkyl ether acetic acid E-13] 169.3 g of 1-octanol (Tokyo Chemical Industry Co., Ltd.) and 3.0 g of potassium hydroxide were charged into an autoclave equipped with a stirrer, temperature controller, and automatic charger, and dehydration was carried out for 30 minutes at 110°C and 1.2 kPa. After completion of dehydration, nitrogen replacement was carried out, and the temperature was raised to 150°C, after which 858.0 g of ethylene oxide (15 mol relative to alcohol) was charged. The reaction was carried out for 1 hour at 150°C, and an ethylene oxide adduct with an average added mole number of 15 mol was obtained.

[0132] 77.4 g of the obtained ethylene oxide adduct was mixed with 510 ml of a 1 mol / l aqueous solution of sodium hydroxide, 71.1 g of potassium permanganate was added, and the mixture was stirred at room temperature for 6 hours. Then, 760 ml of 2-propanol was added, and the mixture was stirred for 1 hour to remove excess potassium permanganate. The sodium was quenched, and the by-product manganese oxide was filtered. The aqueous layer was extracted with dichloromethane and purified to obtain polyoxyethylene methyl ether acetic acid E-13. The structure of R71 and the value of x of E-13 are shown in Table 10. [Table 10]

[0133] [3. Manufacturing Examples of Coating Solutions F-1 to F-44 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 11 below, were added to a reaction vessel and stirred. Next, 2-butanone (MEK) was added so that the total solids ratio was 30 mass%, and then mixed with 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, and resin layer forming coating solution F-1 was prepared. [Table 11]

[0134] <3-2. Preparation of coating solutions F-2 to F-44 for forming resin layer> Resin layer forming coating solutions F-2 to F-44 were prepared by the following method. First, the hydroxyl group-terminated urethane prepolymer, isocyanate group-terminated prepolymer, additives, carbon black, and roughening particles shown in Table 12 below were mixed in the same manner as in the preparation of resin layer forming coating solution F-1. Then, 2-butanone (MEK) was added to adjust the viscosity of the solution to within the range of 6 to 10 mPa s to prepare resin layer forming coating solutions F-2 to F-44. [Table 12]

[0135] [Example 1] <1. Manufacturing of electrophotographic rollers> In this embodiment, an electrophotographic roller in which a resin layer is coated on an elastic roller having an elastic layer provided on the outer surface of a substrate will be described, but the present invention is not limited to this configuration.

[0136] [1-1. Adjustment of the base] As a substrate, a 6 mm diameter core bar made of stainless steel (SUS304) was prepared by coating and baking a primer (product name: DY35-051, manufactured by Dow Toray Industries, Inc.) on the peripheral surface.

[0137] [1-2. 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 13 was poured into the cavity formed in the mold. [Table 13]

[0138] The mold was then heated to vulcanize and harden the silicone rubber at 150°C for 15 minutes, and after demolding, it was further heated at 180°C for 1 hour to complete the hardening reaction, yielding an elastic roller with an elastic layer having a diameter of 11.5 mm on the outer periphery of the base body.

[0139] [1-3. 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, an electrophotographic roller G-1 was obtained in which a resin layer having a thickness of 12 μm was formed on the elastic layer.

[0140] <2. Impedance measurement> The impedance was measured as follows. First, as a pretreatment, a measurement electrode was prepared by vacuum-depositing platinum on the electrophotographic roller G-1 while rotating it. For the deposition, a vacuum deposition device having a mechanism for gripping the base part of the roller on which the film was to be formed and rotating it in the circumferential direction was used, and the roller rotation speed, deposition distance, and deposition time were controlled to deposit the film to a thickness of 100 nm or more. At this time, a masking tape was used to prepare an electrode with a width of 1.5 cm. By forming the electrode with a thickness of 100 nm or more, it is possible to minimize the contribution of the contact area between the measurement electrode and the electrophotographic roller due to the surface roughness of the electrophotographic roller.

[0141] Next, an aluminum sheet was wrapped around the electrode without any gaps, and an impedance measuring device (product name: Solartron 1260 and Solartron 1296, manufactured by Solartron) and a high voltage system (product name: 6792 and HVA-500, manufactured by Toyo Technolo- gy) were used to measure the impedance of the electrode. The device was connected to a measuring electrode (manufactured by Kabushiki Kaisha).

[0142] Fig. 5 shows a schematic diagram of the state in which the measurement electrodes are formed on the electrophotographic roller. In Fig. 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.

[0143] Figure 6 shows a cross-sectional view of an electrophotographic roller with a measurement electrode formed thereon. 61 is a conductive substrate, 62 is an elastic layer, 63 is a resin layer, 64 is a platinum vapor deposition layer, and 65 is an aluminum sheet. As shown in Figure 6, it is important to sandwich the resin layer between the conductive substrate and the measurement electrode.

[0144] The aluminum sheet was then connected to the measurement electrodes of an impedance measuring device (Solatron 1260 and Solartron 1296, Solartron Corporation) and a high voltage system (product names: 6792 and HVA-500, Toyo Corporation). A schematic diagram of this measurement system is shown in Figure 7. Impedance measurements were performed using the conductive substrate and the aluminum sheet as the two electrodes for measurement.

[0145] 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 at a frequency of 1.0 x 10 -1 ~1.0×10 5 The absolute value of the impedance was obtained at frequencies of 1.0×10 0 ~1.0×10 1 The minimum impedance value in Hz was confirmed. The impedance was measured at the center of the electrophotographic roller in the longitudinal direction.

[0146] <3. Measurement of surface potential> The surface potential of the electrophotographic 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 electrophotographic roller was 1.0 mm. The grid part of the corona discharger of the above device had a width of 3.0 mm. Next, a voltage of 8 kV was applied to the corona charger, and the corona charger was moved relatively along the axial direction of the electrophotographic roller 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. The maximum value of all the measured values ​​measured at eight points in the longitudinal direction at 45° intervals in the circumferential direction of the electrophotographic roller was used.

[0147] <4. Calculation of each physical property such as circle equivalent diameter, wall distance, etc. of carbon black dispersed in resin layer> The particle size of the carbon black dispersed in the resin layer and the wall distance were measured by the following method. First, a slice (0.5 to 1.0 mm thick) is cut out using a razor so that a cross section perpendicular to the longitudinal direction of the electrophotographic roller can be observed. If the adhesion between the substrate and the resin layer is high and cutting out with a razor is difficult, the substrate is cut out with a hacksaw or the like, and then the cross section is processed using a FIB (Focused Ion Beam) device.

[0148] Next, the slices are platinum-deposited, and the resin layer is photographed at 15,000 times magnification using a scanning electron microscope (SEM) (product name: JSM-7800F, manufactured by JEOL Ltd.) to obtain a cross-sectional image. Furthermore, in order to quantify the cross-sectional images obtained by SEM observation, the cross-sectional images were processed using image processing software (product name: Luzex AP, manufactured by Nireco Corporation) to obtain 8-bit resolution. The cross-sectional image is then grayscaled to obtain a monochrome image with 256 gradations. Next, the black and white of the image are inverted so that the carbon black in the cross-sectional image becomes white, and a binarization threshold is set for the brightness distribution of the image based on the algorithm of Otsu's discriminant analysis method, to obtain a binarized image in which the carbon black is white and the binder resin is black.

[0149] The obtained binarized image was then processed using image processing software (product name: Luzex AP, A 3D scanner (manufactured by Nireco Corporation) is used to calculate the equivalent circle diameter and the distance between adjacent wall surfaces of the whitened carbon black portion. Calculate the equivalent circle diameter and the distance between adjacent wall surfaces. In order to eliminate the uncertainty of the calculated values ​​for the carbon black that is divided at the top, bottom, left, and right ends of the image, the image area is set to an area 0.075 μm inside in actual image dimensions (if there is a text area listing SEM measurement conditions, etc., then 0.075 μm inside from where the actual image begins), and calculate the equivalent circle diameter and the distance between adjacent wall surfaces for all carbon black within the specified image area. Then, the arithmetic mean value and standard deviation are calculated for the distribution of the obtained circle equivalent diameter and the distance between adjacent wall surfaces. Although there is no particular problem with the number of images for image analysis, at least three images are used in order to eliminate the influence of the location difference in the longitudinal direction of the carbon black dispersed in the resin layer of the electrophotographic roller.

[0150] The number average diameter of the primary particles of the carbon black dispersed in the resin was measured by a transmission electron microscope (TEM). First, a sliced ​​sample was prepared. A known method can be used for the slice. For example, the sample can be sliced ​​using an ion beam or a diamond knife. In this disclosure, a sliced ​​sample for observation with a thickness of 40 nm was prepared using an ultramicrotome (product name: ULTRACUT-S, manufactured by Leica Microsystems, Inc.). Then, a TEM image was obtained using a transmission electron microscope (product name: H-7100FA, manufactured by Hitachi High-Technologies Corporation) under measurement conditions of TE mode and an accelerating voltage of 100 kV. Then, using image analysis software (product name: WinROOF, manufactured by Mitani Shoji Co., Ltd.) for the obtained TEM image, the circular equivalent diameters of 50 arbitrarily selected 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.

[0151] (Measurement of DBP absorption of carbon black) The DBP absorption of carbon black was measured for carbon black powder in accordance with Japanese Industrial Standards (JIS) K6217-4.

[0152] (Measurement of pH of Carbon Black) Carbon black pH was measured on carbon black powder according to ASTM D1512.

[0153] <5. Image evaluation> The image evaluation method 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. Modified parts included connecting to power sources 14C and 15C as well as an external high voltage power source 20C so that an arbitrary potential difference could be set between the developing blade and the electrophotographic roller, and in order to evaluate a high speed process, the output rate per unit time was set to 50 sheets / min for A4 size paper. The process cartridge used was a commercially available toner cartridge 318 (black) (manufactured by Canon Inc.), and the developing roller was replaced with electrophotographic roller G-1. At this time, the amount of toner filled was adjusted to 100 g. The product toner was removed from each of the yellow, cyan, and magenta stations, and yellow, cyan, and magenta cartridges with the toner remaining amount detection mechanism disabled were inserted for evaluation.

[0154] [5-1. Fog evaluation] The prepared process cartridge was mounted in the main body of an electrophotographic image forming apparatus and left for 24 hours in an environment of a temperature of 30° C. and a relative humidity of 80%. The potential difference between the printer and the electrophotographic roller was set to -300V, and in the same environment, an image of the 4-point size alphabet "E" was continuously printed on an A4 evaluation paper (GF-C081, manufactured by Canon Inc.) with a print rate of 2% of the area of ​​the A4 size paper. A solid white image was printed every 1000 sheets, and this was repeated up to 20000 sheets, and the fogging value was measured using the following method.

[0155] Using a reflection densitometer (product name: TC-6DS / A, manufactured by Tokyo Denshoku Technology Center Co., Ltd.), the reflection density R1 of the recording material before image formation and the reflection density R2 of the recording material on which a solid white image was output were measured, and the increase in reflection density (R2-R1) was taken as the "fog value" of the electrophotographic roller. The reflection density was measured over the entire image printing area of ​​the recording material, and the arithmetic mean value was used for the recording material before image formation, and the maximum value was used for the recording material on which a solid white image was output. Next, the arithmetic mean value of the fog values ​​of each image up to 20,000 sheets was calculated. The smaller the fog value, the better, and usually, toner is not transferred onto the transfer paper on which a solid white image was formed. If the charge amount of the toner is insufficient, the toner moves onto the photoconductor even when the solid white image is formed, and is further transferred onto the transfer paper, increasing the fog value. The evaluation results are shown in Table 14-4. Incidentally, since fogging tends to occur easily in high temperature and high humidity environments of 30°C and 80% relative humidity, the evaluation was carried out in an environment of 30°C and 80% relative humidity.

[0156] [5-2. Image density stability evaluation] The prepared process cartridge was mounted on the main body of an electrophotographic image forming apparatus and left for 24 hours in an environment of 23°C temperature and 50% relative humidity. Thereafter, an external high voltage power supply was used to set the potential difference between the developing blade and the electrophotographic roller to -300V, and one halftone image with 25% solid black, 48 solid white images, and one halftone image with 25% solid black were output in this order. The densities of the obtained first and 50th halftone images were measured using a spectrodensitometer (product name: 508, manufactured by Xrite Corporation), and the density difference between the first and 50th sheets was obtained. The smaller the density difference, the better. The evaluation results are shown in Table 14-4.

[0157] [Examples 2 to 44] In Examples 2 to 44, electrophotographic rollers G-2 to G-44 were produced in the same manner as in Example 1, except that the coating material for forming the surface layer (F-2 to F-44) was changed to those shown in Tables 14-1 and 14-2. Then, the respective measurements and evaluations were carried out in the same manner as in Example 1.

[0158] The physical properties and evaluation results are shown in Tables 14-3 and 14-4. [Table 14-1] In the table, Me represents a methyl group, Et represents an ethyl group, and Bu represents a butyl group.

[0159] [Table 14-2]

[0160] [Table 14-3] In the table, X is the total amount (mass %) of the compounds having structures represented by structural formulas (5) to (7) based on the solid content in the coating material for forming a surface layer. The impedance value is 1.0×10 0 Hz~1.0×10 1 This indicates the minimum impedance value in Hz. Note that notations such as "9.12E+06" mean "9.12 x 10 6 " indicates that.

[0161] [Table 14-4]

[0162] [Comparative Example 1] The materials of the types and amounts shown in Table 15 below were added to a reaction vessel and stirred. Next, 2-butanone (MEK) was added so that the total solid content ratio was 30 mass%, and then mixed with a sand mill. Next, 2-butanone (MEK) was added to adjust the viscosity of the liquid to within a range of 6 to 10 mPa·s to prepare a resin layer forming paint F-45. An electrophotographic roller G-45 was prepared and evaluated in the same manner as in Example 1, except that the resin layer forming paint F-1 was changed to the resin layer forming paint F-45. The evaluation results are shown in Table 19. [Table 15]

[0163] [Comparative Examples 2 to 3] Except for changing the carbon black used in the resin layer-forming paint F-1 to the material shown in Table 16 below, resin layer-forming paints F-46 and F-47 and electrophotographic rollers G-46 and G-47 were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 19. [Table 16]

[0164] [Comparative Examples 4 to 6] Except for changing the additives used in the resin layer-forming paint F-1 to the materials and parts by mass shown in Table 17 below, resin layer-forming paints F-48 to F-50 and electrophotographic rollers G-48 to G-50 were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 19. [Table 17]

[0165] [Comparative Example 7] Except for changing the additive used in the resin layer-forming paint F-1 to E-14 shown in Table 18 below, the resin layer-forming paint F-51 and the electrophotographic roller G-51 were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 19.

[0166] [Comparative Example 8] <Synthesis of Additive E-15> The polyetheramine additive E-15 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.

[0167] (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 charged into an autoclave equipped with a stirrer, temperature controller, and automatic charger, and dehydration was carried out for 30 minutes at 110°C and 1.2 kPa. After completion of dehydration, nitrogen replacement was carried out, and the temperature was raised to 150°C, after which 858.0 g of ethylene oxide (15 mol relative to alcohol) was charged. The reaction was carried out for 1 hour at 150°C, and an ethylene oxide adduct with an average added mole number of 15 mol was obtained.

[0168] The obtained ethylene oxide adduct was cooled to 130°C, and then 1132.6 g of propylene oxide (based on 15 mol of alcohol) 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.

[0169] The obtained polyoxyethylene polyoxypropylene octyldecyl adduct was cooled to 80°C, and unreacted ethylene oxide and propylene oxide were removed at 2.5 kPa for 30 minutes. Then, 6.0 g of 90% lactic acid was charged into the autoclave, and the mixture was stirred at 80°C for 30 minutes, followed by extraction to obtain polyoxyethylene polyoxypropylene decyl ether.

[0170] (Synthesis of polyetheramine E-15) A three-neck flask was equipped with a stirrer, and 1688 g of polyoxyethylene polyoxypropylene decyl ether and 460 ml of acetic acid were added. 600 ml of 2 mol / l aqueous sodium hypochlorite solution was added dropwise over 1 hour. The reaction vessel was placed in an ice bath to cool the mixture to a temperature within the range of 15 to 25°C. After the addition was complete, stirring was continued for 1 hour. Dichloromethane was added to the resulting liquid, and the aqueous layer was extracted, post-treated, and purified using a column to obtain a compound in which the secondary alcohol was ketonized.

[0171] Cool to 0°C in an ice bath, add 250ml of a methanol-acetic acid mixed solution (volume ratio 10:1) to 41.4g of the compound obtained by ketonizing the secondary alcohol, and add 2.7g of 2-picoline-borane. Remove the ice bath and stir overnight at room temperature in an open system. After concentration, cool to 0°C, add 360ml of 35% aqueous hydrochloric acid, and stir at room temperature for 2 hours. Add an aqueous sodium hydroxide solution to make it basic, extract the aqueous layer with dichloromethane, post-treat, and purify with a column to obtain polyetheramine E-15. The structure of R61 of E-15 and the values ​​of v and w are shown in Table 18.

[0172] <Synthesis of resin layer forming paint F-52 and electrophotographic roller G-52> Except for changing the additive used in the resin layer forming paint F-1 to the additive E-15, the resin layer forming paint F-52 and the electrophotographic roller G-52 were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 19.

[0173] [Comparative Example 9] <Synthesis of Additive E-16> 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 for 30 minutes at 110°C and 1.2 kPa. After completion of dehydration, nitrogen replacement was carried out, the temperature was raised to 150°C, and 858.0 g of ethylene oxide (15 mol relative to alcohol) was then added. The reaction was carried out for 1 hour at 150°C, and an ethylene oxide adduct with an average added mole number of 15 mol was obtained.

[0174] The resulting ethylene oxide adduct (90.2 g) was mixed with 510 ml of a 1 mol / l aqueous solution of sodium hydroxide, and 71.1 g of potassium permanganate was added thereto and stirred at room temperature for 6 hours. Then, 760 ml of 2-propanol was added thereto and stirred for 1 hour to remove excess potassium permanganate. The sodium was quenched, and the by-product manganese oxide was filtered. The aqueous layer was extracted with dichloromethane and purified to obtain polyoxyethylene methyl ether acetic acid E-16. The structure of R71 and the value of x of E-16 are shown in Table 18.

[0175] <Synthesis of F-53, paint for forming resin layer, and G-53, electrophotographic roller> Except for changing the additive used in the resin layer forming paint F-1 to the additive E-16, the resin layer forming paint F-53 and the electrophotographic roller G-53 were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 19. [Table 18]

[0176] [Table 19] In the table, X is the amount of the compound represented by the structural formulas (5) to (7) based on the solid content in the coating material for forming the surface layer. The total amount (mass %) of compounds having the structure is The impedance value is 1.0×10 0 Hz~1.0×10 1 This indicates the minimum impedance value in Hz.

[0177] Examples 1 to 44 show good results in the evaluation of fog and image density stability. In particular, it is good to use a polyurethane having only a polycarbonate structure, which is a combination of structural formula (1) and structural formula (4). Since ester structures exist in structural formula (2) and structural formula (3), and the ester structure is more electrically conductive than the polycarbonate structure, it is considered that the combination of structural formula (1) and structural formula (4), which has only a polycarbonate structure, shows better results.

[0178] Furthermore, when the hydrocarbon groups of R12 in structural formula (1) and R41 in structural formula (4) have side chains, good results are observed. Although the details are not known, it is believed that there is an interaction between the hydrocarbon groups of the side chains in the polyurethane structure and the carbon black itself, which exhibits hydrophobic properties (the surface functional groups of acidic carbon black are treated to be hydrophilic, but the carbon black itself exhibits hydrophobic properties). It is speculated that this increases the dispersibility of the carbon black, resulting in good results.

[0179] Similarly, in terms of the structure of the additive, those that have not only ethylene oxide but also propylene oxide show better results. In addition, the terminal functional group of the additive is the best hydroxyl group, followed by amine and then carboxylic acid, in that order. When the terminal functional group is a hydroxyl group, it is possible to undergo a urethane reaction, so it has good compatibility with urethane, and even if it is incorporated into the urethane reaction, it does not inhibit the electrical properties of the urethane, so it is presumed that this is why it showed good results. When the terminal functional group is an amine, it is possible to undergo a urea reaction, so it has a moderate compatibility with urethane, but if it is incorporated into the urethane reaction, it affects the electrical properties of the urethane, so it is presumed that the terminal functional group is a hydroxyl group, which is slightly better.

[0180] On the other hand, in Comparative Examples 1 to 9, the process speed is high, and in the configuration of a high blade bias, the results are low in the fogging evaluation and the image density stability evaluation. Comparative Example 1 uses polyether diol and polycarbonate diol, and both ether structure and polycarbonate structure are incorporated into the polyurethane structure. As a result, it is considered that the electrical properties of the polycarbonate structure are hindered by the ether structure, and the desired impedance value cannot be obtained. Therefore, it is considered that good results were not obtained in the configuration with a high process speed and high blade bias.

[0181] The desired impedance values ​​were not obtained, and good results were not obtained, either, in Comparative Examples 2 and 3. The reason for the low impedance values ​​is believed to be that carbon black with a large number average diameter of primary particles and large DBP absorption was used, which resulted in a large structure of the carbon black after mill dispersion, a large dispersed particle size, and a large wall distance.

[0182] The desired impedance value was not obtained in Comparative Example 4, and thus good results were not obtained. The impedance value was low because the amount of additive was small, which resulted in insufficient dispersion of the conductive filler, and thus the conductive path was formed by the conductive filler in the surface layer. In Comparative Example 5, the surface potential was too high, and therefore good results were not obtained in the fogging evaluation and image density stability evaluation. It is considered that such results were due to the high surface potential caused by the carbon black being coated with an insulating silane coupling agent.

[0183] In Comparative Example 6, the impedance was low, and the fogging evaluation and the image density stability evaluation were low. 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, affecting the electrical properties of the resin. The impedance was low and the fogging evaluation and image density stability evaluation were low in Comparative Examples 7 to 9. The reason for the low impedance is believed 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 desired range, which reduced the dispersibility of the carbon black and resulted in the low impedance.

[0184] The present disclosure relates to the following configurations. (Configuration 1) a substrate having an electrically conductive outer surface; a resin layer on the outer surface of the substrate. The resin layer contains polyurethane having a polycarbonate structure, A metal film was provided directly on the outer surface of the electrophotographic 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 in amplitude and a frequency of 1.0×10 -1 ~1.0×10 5 When applied while changing between 1.0×10 Hz, 0 ~1.0×10 1 Impedance at Hz is 1.00 x 10 6 Ω or more, and an electrophotographic roller, 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 having a width of 3.0 mm is disposed so that the distance between the grid portion and the outer surface of the electrophotographic roller is 1.0 mm and the direction of the width of the grid portion coincides with the axial direction of the electrophotographic 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 electrophotographic roller at a speed of 400 mm / sec to charge the outer surface of the electrophotographic roller, and when the potential of the outer surface is measured 0.06 seconds after passing the grid portion, the maximum value of the potential is less than 20.0 V. (Configuration 2) The electrophotographic roller according to configuration 1, wherein the polyurethane having a polycarbonate structure 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. TIFF2024123617000026.tif138153 In structural formula (1), R11, R12, and R13 each represent a divalent hydrocarbon group 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 each represent the average number of moles added, and each independently represents a number of 1.0 or more. 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. In structural formula (3), R31 and R32 each independently represent a divalent hydrocarbon group having 3 to 8 carbon atoms, and q and r each independently represent the average number of moles added and are each a number of 1.0 or greater. In structural formula (4), R41 represents a divalent hydrocarbon group having 6 to 9 carbon atoms, and s represents the average number of moles added and is a number of 1.0 or more. (Configuration 3) 3. The electrophotographic roller according to configuration 1 or 2, wherein the resin layer contains a conductive filler. (Configuration 4) 4. The electrophotographic roller of claim 3, wherein the conductive filler comprises carbon black. (Configuration 5) the arithmetic average value Rc of the equivalent circle diameter of the carbon black in the resin layer is 60.0 nm or less; 5. The electrophotographic roller according to configuration 4, 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 6) the arithmetic mean value d of the distance between the wall surfaces of the carbon black in the resin layer is 80.0 to 150.0 nm; 6. The electrophotographic roller according to configuration 4 or 5, wherein σd / d is 0.000 to 0.600, where σd is the standard deviation of the distance between the wall surfaces. (Configuration 7) 7. The electrophotographic roller according to any one of Configurations 4 to 6, wherein the number average diameter of primary particles of the carbon black in the resin layer is 30 nm or less. (Configuration 8) the DBP absorption amount of the carbon black in the resin layer is 90 ml / 100 g or less; 8. The electrophotographic roller according to any one of Configurations 4 to 7, wherein the carbon black has a pH of 4.0 or less. (Configuration 9) The electrophotographic roller according to any one of Structures 1 to 8, wherein the resin layer contains at least one 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): TIFF2024123617000027.tif88153 In structural formula (5), R51 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms. t and u represent the average number of moles added and each independently represents a number of 1 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, each independently representing 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 10) 10. The electrophotographic roller according to any one of Configurations 1 to 9, wherein the maximum value of the potential is 10.0 V or less. (Configuration 11) A process cartridge configured to be detachably mounted on a main body of an electrophotographic image forming apparatus, 11. A process cartridge comprising the electrophotographic roller according to any one of configurations 1 to 10. (Configuration 12) An electrophotographic image forming apparatus having a photoconductor and a developing roller that supplies a developer to an electrostatic latent image formed on the photoconductor, 11. An electrophotographic image forming apparatus, wherein the developing roller is the electrophotographic roller according to any one of Configurations 1 to 10. [Explanation of symbols]

[0185] 10 electrophotographic roller, 11 substrate, 12 resin layer, 14 developing roller, 15 developing blade, 16 toner, 17 toner supply roller, 18 developing device, 19 photoconductor, 20 charging roller, 21 cleaning blade, 22 process cartridge

Claims

1. a substrate having an electrically conductive outer surface; a resin layer on the outer surface of the substrate. The resin layer contains polyurethane having a polycarbonate structure, A metal film was provided directly on the outer surface of the electrophotographic 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%. At the same time, an AC voltage of 50 V in amplitude and at 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 Ω or more, and an electrophotographic roller, 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 having a width of 3.0 mm is disposed so that the distance between the grid portion and the outer surface of the electrophotographic roller is 1.0 mm and the direction of the width of the grid portion coincides with the axial direction of the electrophotographic 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 electrophotographic roller at a speed of 400 mm / sec to charge the outer surface of the electrophotographic roller, and when the potential of the outer surface is measured 0.06 seconds after passing the grid portion, the maximum value of the potential is less than 20.0 V.

2. 2. The electrophotographic roller according to claim 1, wherein the polyurethane having a polycarbonate structure 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 the 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 a divalent hydrocarbon group 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 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 more. 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.

3. The electrophotographic roller of claim 1 , wherein the resin layer comprises a conductive filler.

4. 4. The electrophotographic roller of claim 3, wherein said conductive filler comprises carbon black.

5. the arithmetic average value Rc of the equivalent circle diameter of the carbon black in the resin layer is 60.0 nm or less; 5. The electrophotographic roller according to claim 4, wherein, when the standard deviation of the equivalent circle diameter of the carbon black is σc, σc / Rc is 0.000 to 0.

650.

6. 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; 5. The electrophotographic roller according to claim 4, wherein, when the standard deviation of the inter-wall distance is σd, σd / d is 0.000 to 0.

600.

7. 5. The electrophotographic roller according to claim 4, wherein the number average particle size of the primary particles of said carbon black in said resin layer is 30 nm or less.

8. the carbon black in the resin layer has a DBP absorption of 90 ml / 100 g or less; 5. The electrophotographic roller of claim 4, wherein the carbon black has a pH of 4.0 or less.

9. 2. The electrophotographic roller according to claim 1, wherein the resin layer contains at least one 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. t and u represent the average number of moles added and each independently represents 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.

10. 2. The electrophotographic roller according to claim 1, wherein the maximum value of the potential is 10.0 V or less.

11. A process cartridge configured to be detachably mounted on a main body of an electrophotographic image forming apparatus, 11. A process cartridge comprising the electrophotographic roller according to claim 1.

12. An electrophotographic image forming apparatus having a photoconductor and a developing roller that supplies a developer to an electrostatic latent image formed on the photoconductor, 11. An electrophotographic image forming apparatus, wherein the developing roller is the electrophotographic roller according to claim 1.

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