Process cartridge and electrophotographic image forming apparatus

Abstract

The invention relates to a process cartridge and an electrophotographic image forming apparatus. The process cartridge includes a developer bearing member and a developer layer thickness control member that contacts the developer bearing member and controls a layer thickness of a developer borne on the developer bearing member, wherein the developer bearing member includes a substrate having a conductive outer surface and a resin layer present on an outer surface side of the substrate, and an impedance measured by directly providing a metal film on the outer surface of the developer bearing member is 1.00 * 106 Omega or more, an ionization potential I (T) of the developer and an ionization potential I (R) of an outer surface of the developer bearing member satisfy a specific relationship, and a maximum value of the potentials measured on the outer surface of the developer bearing member is less than 20.0 V.

Description

Technical Field

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

[0002] For electrophotographic image forming apparatuses, there is a need for higher processing speeds, compatibility with various media, and compatibility with various environments. To meet these needs, the method of charging the developer can be changed from the conventional triboelectric charging method to an injection charging method. In the injection charging method, a high voltage is applied to a developer layer thickness control member that contacts a developer carrier member, so that charges can be transferred to the developer more rapidly. The charges injected from the developer layer thickness control member into the developer can be controlled by the voltage on the developer layer thickness control member, so that it is possible to expect a reduction in the influence of environments such as temperature and humidity. In addition, by increasing the voltage on the developer layer thickness control member, it is possible to expect appropriate charging of the developer even when the processing speed is increased.

[0003] Japanese Patent Application Laid-Open No. H03-233479 discloses a configuration in which a voltage can be applied to a developer layer thickness control member, and the triboelectric series difference among the developer, the developer layer thickness control member, and the developer carrier member in the process cartridge is reduced. According to this publication, under certain conditions, charges can be imparted to the developer. Summary of the Invention

[0004] However, the present inventors have recognized that in the case of the configuration disclosed in Japanese Patent Application Laid-Open No. H03-233479, when an electrophotographic image forming apparatus having a high processing speed is used in a high-temperature and high-humidity environment or a low-temperature and low-humidity environment, fogging may occur and the amount of charge imparted to the developer may fluctuate. Specifically, fogging is more likely to occur in a high-temperature and high-humidity environment, and the reduction in dot reproducibility in a low-temperature and low-humidity environment is more likely to be manifested as coarseness.

[0005] The present disclosure aims to provide a process cartridge and an electrophotographic image forming apparatus that can suppress the occurrence of fogging in a high-temperature and high-humidity environment and the occurrence of coarseness (reduced dot reproducibility) in a low-temperature and low-humidity environment by being durably used in a system having a high processing speed.

[0006] The present disclosure relates to a process cartridge including:

[0007] a developer,

[0008] a developer carrier member,

[0009] A developer layer thickness control member that contacts a developer carrier member and controls the layer thickness of the developer carried on the developer carrier member,

[0010] Contacts electrically connected to the developer layer thickness control member, and

[0011] A developer storage member that stores a developer, wherein

[0012] The process cartridge is detachably mounted to the main body of an electrophotographic image forming apparatus,

[0013] At least a part of the developer layer thickness control member is conductive,

[0014] When the process cartridge is mounted to the main body of the electrophotographic image forming apparatus, the contacts are electrically connected to the main body contacts of the main body of the electrophotographic image forming apparatus, and a predetermined voltage can be applied to the developer layer thickness control member,

[0015] The developer carrier member includes

[0016] A substrate including a conductive outer surface, and

[0017] A resin layer present on the outer surface side of the substrate,

[0018] When a metal film is directly provided on the outer surface of the developer carrier member, and a DC voltage of 50 V is applied between the outer surface of the substrate and the metal film in an environment where the temperature is 23°C and the relative humidity is 50%, while applying an AC voltage with an amplitude of 50 V whose frequency varies between 1.0×10 -1 to 1.0×10 5 Hz, the impedance at a frequency of 1.0×10 0 to 1.0×10 1 Hz is 1.00×10 6 Ω or more,

[0019] When the ionization potential of the developer is represented by I(T) and the ionization potential of the outer surface of the developer carrier member is represented by I(R), I(T) and I(R) satisfy the following formula (X):

[0020] |I(T) - I(R)| ≤ 0.3 eV...(X)

[0021] And in an environment where the temperature is 23 °C and the relative humidity is 50%, a corona discharger having a gate portion with a width of 3.0 mm is arranged such that the distance between the gate portion and the outer surface of the developer carrier member is 1.0 mm, and the width direction of the gate portion is aligned with the axial direction of the developer carrier member. A voltage of 8 kV is applied to the gate portion, and the corona discharger moves relative to the developer carrier member along the axial direction of the developer carrier member at a speed of 400 mm / second to charge the outer surface of the developer carrier member. When measuring the potential of the outer surface 0.06 seconds after passing through the gate portion, the maximum value of the potential is less than 20.0 V.

[0022] The present disclosure relates to an electrophotographic image forming apparatus, which includes

[0023] a main body of the electrophotographic image forming apparatus, and

[0024] a process cartridge detachably mounted to the main body, wherein

[0025] the process cartridge is the above-described process cartridge,

[0026] the main body has main body contacts that are electrically connected to the contacts of the process cartridge when the process cartridge is mounted to the main body, and

[0027] a predetermined voltage can be applied to the developer layer thickness control member when the process cartridge is mounted to the main body.

[0028] According to the present disclosure, it is possible to provide a process cartridge and an electrophotographic image forming apparatus that can suppress the occurrence of fogging in a high-temperature and high-humidity environment and roughness (reduced dot reproducibility) in a low-temperature and low-humidity environment by being durably used in a system with a high processing speed.

[0029] Other features of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic cross-sectional view showing an example of a developer carrier member;

[0031] Figure 2 is a schematic cross-sectional view showing another example of a developer carrier member;

[0032] Figure 3 is a schematic view of a process cartridge;

[0033] Figure 4 is a schematic view of an electrophotographic image forming apparatus;

[0034] Figure 5 is a schematic view showing a state where a measurement electrode is formed on a developer carrier member;

[0035] Figure 6 is a cross-sectional view of a developer carrier member and a measurement electrode;

[0036] Figure 7 is a schematic diagram of an impedance measurement system;

[0037] Figure 8 is a schematic diagram showing an example of an apparatus for measuring the surface potential of a developer carrier member;

[0038] Figure 9 is a schematic diagram of a circuit for measuring a leakage current flowing from a developer to a developer carrier member;

[0039] Figure 10 is a schematic diagram of an electrophotographic image forming apparatus for image evaluation;

[0040] Figure 11 is an example of a result obtained by ionization potential measurement; and

[0041] Figure 12 is a cross-sectional view of a developer carrier member. DETAILED DESCRIPTION

[0042] In the present disclosure, unless otherwise specified, the expression "from XX to YY" or "XX to YY (XX~YY)" indicating a numerical range means a numerical range including the lower limit and the upper limit as endpoints. In addition, when a numerical range is described in a segmented manner, the upper limit and the lower limit of each numerical range can be arbitrarily combined. Further, in the present disclosure, for example, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any one of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, and a combination of XX, YY, and ZZ.

[0043] The present inventors have studied a structure that can suppress the generation of fogging in a high-temperature and high-humidity environment and the generation of roughness in a low-temperature and low-humidity environment by being durably used in a system with a high processing speed. The present inventors have found that in an injection charging method in which a voltage is applied to a developer layer thickness control member to impart charge to the developer, compared with a friction charging method in which the developer is charged by friction between the developer layer thickness control member and the developer carrier member, it is more important to satisfy the following items.

[0044] Item (1): It includes a mechanism capable of applying a voltage to a developer layer thickness control member to inject charge into the developer.

[0045] Item (2): The developer carrier member should be such that the charge injected into the developer does not leak to the developer carrier member.

[0046] Item (3): The developer carrier member shall allow the excess charge that has been overcharged on the surface of the developer carrier member to leak out.

[0047] By satisfying the above items (1) to (3), the amount of charge injected into the developer can be controlled to a constant amount in a high-temperature and high-humidity environment and a low-temperature and low-humidity environment. In addition, by satisfying the following item (4), a very uniform high-quality image with high dot reproducibility and small roughness can be obtained.

[0048] Item (4): The triboelectric charging series of the developer and the developer carrier member shall be configured to suppress the application of charge to the developer due to triboelectric charging.

[0049] The above items (1) to (4) will be described below.

[0050] First, when charging the developer by the injection charging method, the above items (1) and (4) are necessary.

[0051] According to item (1), a voltage is applied to the developer layer thickness control member, and the developer contacts it, so that charge is injected into the developer. Item (1) can be implemented by the following process cartridge having:

[0052] A developer carrier member,

[0053] A developer layer thickness control member that contacts the developer carrier member and controls the layer thickness of the developer carried on the developer carrier member,

[0054] A contact point electrically connected to the developer layer thickness control member, and

[0055] A developer storage member for storing the developer.

[0056] By satisfying item (4), the degree of charging the developer caused by the friction between the developer and the developer carrier member can be suppressed. It is well known that the charge generated by triboelectric charging is easily affected by the surrounding environment. Specifically, when comparing the charge generated by triboelectric charging in a normal temperature and normal humidity environment with the charge generated in a low-temperature and low-humidity environment, the developer will acquire more charge in the latter environment. In addition, since the amount of friction varies according to the contact opportunity between the developer carrier member and the developer, the charge amount of each particle of the developer shows a wide charging performance, such that some developer particles have a high charge amount while some developer particles have a low charge amount. The feature of the present disclosure is to reduce the charge amount of the developer generated by this triboelectric charging and increase the charge amount of the developer generated by injection charging, which will be described below.

[0057] Regarding item (4), in the present disclosure, the triboelectric series of the developer and the developer carrier member is represented by the ionization potential. The ionization potential is a physical property value indicating the degree of charge release. When two substances having different ionization potentials come into contact and rub against each other, charge moves from the substance with the smaller ionization potential to the substance with the larger ionization potential. As a result, the substance with the smaller ionization potential becomes positively charged, and the substance with the larger ionization potential becomes negatively charged.

[0058] In the present disclosure, when the ionization potential of the developer is represented by I(T) and the ionization potential of the outer surface of the developer carrier member is represented by I(R), I(T) and I(R) satisfy the following formula (X).

[0059] |I(T) - I(R)| ≤ 0.3 eV...(X)

[0060] Formula (X) indicates that the triboelectric series (ionization potential) of the developer and the developer carrier member are close to each other. By satisfying this condition, the charge imparted to the developer by triboelectrification when the developer carrier member rubs against the developer can be suppressed. Therefore, roughness can be suppressed. The control of the ionization potential of the developer and the developer carrier member and the method for measuring the ionization potential are described below.

[0061] By satisfying item (2), when injecting charge from the developer layer thickness control member to which a voltage is applied into the developer, leakage of the charge of the developer to the developer carrier member can be suppressed. That is, regarding item (2), when a metal film is directly provided on the outer surface of the developer carrier member, and in an environment where the temperature is 23°C and the relative humidity is 50%, while applying a DC voltage of 50 V between the outer surface of the substrate and the metal film, with an AC voltage having an amplitude of 50 V applied at a frequency varying between 1.0×10 -1 to 1.0×10 5 Hz, the impedance at a frequency of 1.0×10 0 to 1.0×10 1 Hz is 1.00×10 6 Ω or more.

[0062] This impedance is a physical property value indicating the charge leakage from the developer to the developer carrier member. According to the research of the present inventor, according to the Figure 9 shown circuit diagram, the current value (leakage current value) of the current flowing through the developer carrier member when a blade bias is applied to the developer layer thickness control member is measured. As a result, it is found that this current value shows a higher correlation with the impedance value of the developer carrier member than the resistance value of the developer carrier member.

[0063] In other words, this indicates that when estimating charge leakage, it is necessary to consider not only the influence of the resistance element of the developer carrier member but also the influence of the capacitance element. This is considered to be because when the electrical characteristics of the developer carrier member are pseudo-represented by an RC parallel circuit, charge is sufficiently stored in the capacitance element, and the transient state until reaching the steady state dominated by the resistance element has a great influence on charge leakage.

[0064] The voltage application condition for impedance measurement is an AC voltage of 50V superimposed on a DC voltage of 50V. That is, a sine wave with a minimum and maximum applied voltage of 0V and 100V (Vpp 100V) is applied. The value of this Vpp 100V is the assumed maximum value of the shared voltage applied to the developer carrier member when a voltage is applied such that a voltage difference of 300V is applied between the developer carrier member and the developer layer thickness control member in an electrophotographic image forming apparatus.

[0065] The impedance exhibits bias dependence and has the property of decreasing as the bias increases, but it is known that the degree of this decrease varies depending on the developer carrier member. In the conventional impedance measurement of the developer carrier member, a voltage application condition of 1V AC voltage is usually used. However, the application condition of 1V AC voltage is significantly lower than the voltage (usually several hundred V) applied between the developer carrier member and the developer layer thickness control member in an actual electrophotographic image forming apparatus. Therefore, this condition usually makes it impossible to simulate the behavior of the developer carrier member in an electrophotographic image forming apparatus and is generally not suitable as an impedance measurement condition.

[0066] Therefore, in the present disclosure, a voltage application condition that simulates the high blade bias applied in an actual electrophotographic image forming apparatus is adopted. In addition, a sine wave with a minimum applied voltage of 0V is usually used to simulate the square wave for applying the blade bias to an actual electrophotographic image forming apparatus.

[0067] In the present disclosure, the impedance at a frequency of 1.0×10 0 to 1.0×10 1 Hz is specified, but the low-frequency range of the frequency from 1.0×10 0 to 1.0×10 1 Hz is the region where the transient state is completed and the steady state dominated by the resistance element is reached. In other words, the influences of both the capacitance element and the resistance element are reflected, and this region is suitable for determining the charge leakage from the developer to the developer carrier member. The impedance at a frequency of 1.0×10 0 to 1.0×10 1 Hz is 1.00×10 6In the case of Ω or more, charge leakage is low. Under a high blade bias voltage, charge leakage from the developer to the developer carrier member is suppressed, and a reduction in the charge amount of the developer can be prevented.

[0068] Item (3) is related to the surface potential of the developer carrier member and represents the characteristic of attenuating excess charge that has been overcharged on the surface of the developer carrier member. In the present disclosure, charge is injected into the developer by the voltage difference applied between the developer layer thickness control member and the developer carrier member. When excess charge remains on the surface of the developer carrier member, the voltage difference decreases, and the charge amount that can be injected into the developer decreases. The surface of the developer carrier member is given an attenuation characteristic so as to control the charge amount injected into the developer at a constant level.

[0069] Item (3) defines the attenuation characteristic of the surface of the developer carrier member as follows. In the present disclosure, a voltage of 8 kV is applied to the gate portion, and the corona discharger moves relative to the developer carrier member along the axial direction of the developer carrier member at a speed of 400 mm / second. At this time, the potential of the outer surface of the developer carrier member 0.06 seconds after passing through the gate portion of the corona discharger is checked. When the maximum value of the surface potential of the outer surface is less than 20.0 V, even in an electrophotographic image forming apparatus having a high processing speed, the occurrence of image defects caused by overcharging of the developer can be suppressed, where the time until the developer charged by the developer layer thickness control member is transported to the photosensitive member is shorter. The timing 0.06 seconds after passing through the gate portion of the corona discharger simulates an apparatus having a high processing speed.

[0070] By satisfying the above items (2) and (3), the conflicting problems of preventing charge leakage from the developer to the developer carrier member and removing the charge that has been overcharged on the surface of the developer carrier member can be solved at a high level. Therefore, the occurrence of fogging in a high-temperature and high-humidity environment and the occurrence of roughness in a low-temperature and low-humidity environment can be suppressed.

[0071] By combining the above items (1) to (4) in this way, it is possible to suppress the charge ratio of the developer applied by triboelectric charging and increase the charge ratio of the developer applied by injection charging at the same time. In addition, the charge of the developer obtained by injection charging can be controlled to a constant level.

[0072] As a result, the charge distribution of the developer becomes uniform, and high-quality images with less roughness can be obtained throughout the entire durability period. In addition, even in an electrophotographic image forming apparatus having a high processing speed, high-quality images with less fogging and roughness can be obtained during the durability period in both a high-temperature and high-humidity environment and a low-temperature and low-humidity environment.

[0073] Regarding item (4), when the formula (X) is not satisfied, the effect of charging the developer by triboelectrification increases. This may cause a decrease in image quality, such as roughness. |I(T)-I(R)| is, for example, 0 to 0.3, preferably 0 to 0.2, and more preferably 0 to 0.1.

[0074] Regarding item (2), when the impedance of the developer carrier member is less than 1.00×10 6 Ω, the charge of the developer easily leaks to the developer carrier member. As a result, it may not be possible to suppress fogging in a high-temperature and high-humidity environment. The impedance is preferably 1.00×10 6 to 5.00×10 7 Ω, more preferably 2.00×10 6 to 5.00×10 7 Ω, even more preferably 7.00×10 6 to 5.00×10 7 Ω, still more preferably 7.00×10 6 to 2.00×10 7 Ω.

[0075] Regarding item (3), when the surface potential of the developer carrier member is 20.0 V or more, the potential difference between the developer layer thickness control member and the developer carrier member is likely to decrease due to the influence of the excessively charged charges on the surface of the developer carrier member. Therefore, when continuous printing is performed, the charge of the developer decreases, fogging tends to occur, and the image quality tends to deteriorate. The lower the surface potential of the developer carrier member, the more preferable, and there is no particular lower limit. The preferable range of the surface potential of the developer carrier member is, for example, 0 V or more and less than 20.0 V, particularly 0 to 10.0 V, and particularly preferably 0 to 7.0 V.

[0076] The present disclosure will be described in detail below.

[0077] Developer carrier member

[0078] The developer carrier member according to at least one aspect of the present disclosure has a substrate having a conductive outer surface and a resin layer present on the outer surface side of the substrate.

[0079] In Figure 1 examples of the developer carrier member are shown. Figure 1 The shown developer carrier member 10 has a resin layer 12 laminated on the outer surface of the outer peripheral surface of a cylindrical or hollow cylindrical substrate 11.

[0080] The layer structure of the developer carrier member is not limited to Figure 1The embodiments shown. Other layers may be provided between the substrate 11 and the resin layer 12. In another embodiment of the developer carrier member, the developer carrier member has an elastic layer 13 as an intermediate layer between the substrate 11 and the resin layer 12 provided on the outer peripheral surface of the substrate, as shown in Figure 2 shown. The resin layer 12 is, for example, a surface layer. The outer surface of the resin layer 12 is preferably the outer surface of the developer carrier member.

[0081] Substrate

[0082] The substrate has a conductive outer surface and serves as a support member for the developer carrier member and, in some cases, as an electrode. Specific examples of the substrate are preferably a solid cylinder or a hollow cylinder.

[0083] The material constituting the substrate can be appropriately selected from those known in the field of conductive materials for electrophotography and materials that can be used as developer carrier members. Examples include metals such as aluminum and stainless steel, carbon steel alloys, conductive synthetic resins, and metals and alloys such as iron and copper alloys.

[0084] In addition, the material constituting the substrate can be subjected to an oxidation treatment or a plating treatment with chromium or nickel, etc. As the type of plating, either electroplating or electroless plating can be used. From the viewpoint of dimensional stability, electroless plating is preferred. Examples of electroless plating that can be used here include nickel plating, copper plating, gold plating, and various other types of alloy plating. The plating thickness is preferably 0.05 μm or more, and considering the balance between working efficiency and rust prevention ability, the plating thickness is preferably 0.1 to 30 μm.

[0085] A primer can be applied to the surface of the substrate to improve the adhesion between the substrate and the resin layer. As the primer, a known one can be selected according to the rubber material for forming the conductive layer and the material of the support, etc. Examples of primer materials include thermosetting resins and thermoplastic resins. Specifically, materials such as phenolic resins, polyurethanes, acrylic resins, polyester resins, polyether resins, and epoxy resins can be used.

[0086] Resin layer

[0087] Binder resin

[0088] The developer carrier member includes a resin layer on the outer surface of the substrate. For example, the resin layer is present on the outer surface of the developer carrier member. The resin layer may contain a binder resin. Known materials can be used as the binder resin of the resin layer. The binder resin of the resin layer is preferably a polyurethane resin, more preferably a crosslinked polyurethane resin. The polyurethane resin (preferably crosslinked polyurethane resin) is preferably a polyurethane having a polycarbonate structure to suppress charge leakage from the developer to the developer carrier member. That is, the resin layer preferably contains a polyurethane having a polycarbonate structure. The polyurethane having a polycarbonate structure is more preferably a crosslinked polyurethane resin. In addition, in order to suppress charge leakage from the developer to the developer carrier member while maintaining a light load on the developer and sufficient abrasion resistance of the resin layer, it is more preferable to use a polyurethane having the following-described structure as the binder resin of the resin layer.

[0089] The polyurethane having a polycarbonate structure preferably satisfies at least two of the following (A), (B), and (C). It may also satisfy all of the following (A), (B), and (C).

[0090] (A) The polyurethane has a structure represented by the following structural formula (1) in the molecule.

[0091] (B) The polyurethane has at least one structure selected from the group consisting of the structure represented by the following structural formula (2) and the structure represented by the following structural formula (3) in the molecule.

[0092] (C) The polyurethane has a structure represented by the following structural formula (4) in the molecule.

[0093] In other words, preferably, the polyurethane satisfies at least any one of the following.

[0094] - The polyurethane has at least the structure represented by structural formula (1) and the structure represented by structural formula (2)

[0095] - The polyurethane has at least the structure represented by structural formula (1) and the structure represented by structural formula (3)

[0096] - The polyurethane has at least the structure represented by structural formula (1) and the structure represented by structural formula (4)

[0097] - The polyurethane has at least the structure represented by structural formula (2) and the structure represented by structural formula (4)

[0098] - The polyurethane has at least the structure represented by structural formula (3) and the structure represented by structural formula (4)

[0099] Among them, from the viewpoint of better fogging suppression and roughness suppression, more preferably, the polyurethane has at least the structure represented by structural formula (1) and the structure represented by structural formula (2) in the molecule.

[0100] Structural formula (1)

[0101]

[0102] Structural formula (2)

[0103]

[0104] Structural formula (3)

[0105]

[0106] Structural formula (4)

[0107]

[0108] In structural formula (1), R11, R12, and R13 represent divalent hydrocarbon groups having 3 to 9 carbon atoms. However, R11 and R12 are different from each other, and R13 is the same as at least one selected from the group consisting of R11 and R12. m and n are average addition molar numbers, and each independently represents a number of 1.0 or more (preferably 1.0 to 20.0, more preferably 2.0 to 12.0).

[0109] In structural formula (2), o and p are average addition molar numbers, and each independently represents a number of 1.0 or more (preferably 1.0 to 15.0, more preferably 4.0 to 10.0).

[0110] In structural formula (3), R31 and R32 each independently represent divalent hydrocarbon groups having 3 to 8 carbon atoms. q and r each independently represent average addition molar numbers, and each independently represents a number of 1.0 or more (preferably 1.0 to 20.0, more preferably 2.0 to 14.0).

[0111] In structural formula (4), R41 represents a divalent hydrocarbon group having 6 to 9 (preferably 5 to 8) carbon atoms. s represents an average addition molar number, and represents a number of 1.0 or more (preferably 1.0 to 22.0, more preferably 4.0 to 18.0).

[0112] The structure represented by structural formula (1) is obtained by reacting a copolycarbonate polyol in which crystallization is inhibited by bonding two carbonate groups to two different types of hydrocarbon groups with an isocyanate. Since crystallization is inhibited, the cohesive energy in the soft segment is small, and flexibility and high volume resistivity can be imparted to the resin layer.

[0113] By combining the structure of the structural formula (1) with the structures of the above (2) to (4) and using them in the resin layer, the adhesiveness of the resin layer can be reduced. Therefore, the adhesion of a developer, powder, etc. to the surface of the resin layer can be suppressed, the increase in the surface resistance value of the resin layer due to contamination can be suppressed, and the developer can be easily and uniformly charged.

[0114] In the 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.

[0115] When the number of carbon atoms of R11 and R12 is 3 or more, in the polyurethane having a polycarbonate structure, the amount of carbonate groups, which are polar functional groups having a strong cohesive energy, is not excessive, making it easier to keep the resin layer soft and having a high resistance.

[0116] In addition, when the number of carbon atoms of R11 and R12 is 9 or less, the amount of carbonate groups in the polyurethane is not too small, so that the strength of the polymer can be maintained. Further, since R11 and R12 have different structures, the crystallinity of the polymer can be suppressed, and flexibility can be imparted to the resin layer. m and n each independently represent a number of 1.0 or more. The hydrocarbon groups represented by R11, R12, and R13 may have a branched structure or a cyclic structure.

[0117] The structures represented by the structural formula (2) and the structural formula (3) are obtained by reacting a copolymer polyol, which is a copolymer of a polycarbonate structure and a polyester structure, with an isocyanate. By copolymerizing the polycarbonate structure and the polyester structure, the crystallinity of the polymer is suppressed, and by introducing an ester group having a stronger cohesive energy than the carbonate group, the soft segment is appropriately strengthened, so that abrasion resistance can be imparted to the resin layer.

[0118] When a polymer in which the structure represented by the structural formula (2) and / or the structural formula (3) is combined with the structure of the above formula (1) or (4) is used to form a resin layer, sufficient volume resistivity can be imparted to the resin layer while having polar ester groups, and it becomes easier to suppress charge leakage from the developer to the developer carrier member.

[0119] In the structural formula (2), o and p each independently represent a number of 1.0 or more.

[0120] In the 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. When R31 and R32 each have 3 or more carbon atoms, the amounts of carbonate groups and ester groups, which are polar functional groups having a strong cohesive energy, in the polyurethane are not excessive, and the resin layer can remain soft. When R31 and R32 each have 8 or fewer carbon atoms, the amounts of carbonate groups and ester groups in the polyurethane are not too small, and abrasion resistance can be imparted to the resin layer.

[0121] The structure represented by the structural formula (4) is obtained by reacting a highly crystalline polycarbonate polyol in which two carbonate groups are bonded through a single hydrocarbon group with an isocyanate. This structure has high crystallinity and is easily disposed in the soft segment, and thus abrasion resistance and a high volume resistivity can be imparted to the resin layer. By using a polymer in which the structure represented by the structural formula (4) is combined with the structures of the above formulas (1) to (3) to form the resin layer, the hardness of the resin layer does not become too high and can be easily and appropriately controlled.

[0122] In the 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 the number of carbon atoms of R41 is 6 or more, crystallinity is easily exhibited, and abrasion resistance and a high volume resistivity can be imparted to the resin layer. When the number of carbon atoms of R41 is 9 or less, by further including at least one of the structures represented by the structural formulas (1), (2), and (3) in the polymer, excessive crystallinity can be suppressed, and thus an increase in the hardness of the resin layer can be suppressed.

[0123] The resin layer contains a polymer having a urethane bond, that is, a polyurethane having a polycarbonate structure, as a binder resin, and the polymer preferably satisfies at least two conditions selected from the group consisting of the above (A), (B), and (C). This makes the resin layer soft and not easily worn.

[0124] The structure of the polymer contained in the resin layer of the developer carrier member can be confirmed by, for example, pyrolysis GC / MS, FT-IR, or NMR analysis.

[0125] The polyurethane having a polycarbonate structure can be produced using (A) a polyol compound and (B) a polyisocyanate compound. Generally, the polyurethane is synthesized by the following methods (1) and (2).

[0126] (1) The one-shot method in which a polyol component and a polyisocyanate component are mixed and reacted.

[0127] (2) A method in which a prepolymer capped with an isocyanate group obtained by reacting a part of a polyol with an isocyanate is reacted with a chain extender such as a low molecular weight diol or a low molecular weight triol.

[0128] In the present disclosure, the polyurethane can be synthesized by any of the above methods. A more preferred method is to subject a hydroxyl group-capped prepolymer obtained by reacting a raw material polyol with an isocyanate and an isocyanate group-capped prepolymer obtained by reacting a raw material polyol with an isocyanate to a thermal curing reaction.

[0129] The polyurethane having a polycarbonate structure is preferably a reaction product of a mixture containing a hydroxyl group-capped prepolymer and an isocyanate group-capped prepolymer. This mixture can be used as a coating for forming a resin layer. The polyurethane having a polycarbonate structure is more preferably a reaction product of a mixture containing a hydroxyl group-capped prepolymer, an isocyanate group-capped prepolymer, a conductive filler, and an additive.

[0130] When there are multiple groups such as hydroxyl groups, isocyanate groups, or urea bonds, urethane bonds, isocyanurate bonds, etc., there are multiple polar functional groups in the polyurethane, whereby the water absorption of the polymer increases and the volume resistivity of the resin layer decreases, which may lead to charge leakage from the developer to the developer carrier member. At the same time, by thermally curing the above-mentioned hydroxyl group-capped prepolymer and isocyanate group-capped prepolymer, a polyurethane having few unreacted polyols and polar functional groups can be obtained without using an excessive amount of isocyanate.

[0131] (A) Polyol compound

[0132] As the polyol compound, a polyol known in the synthesis of polyurethane resins or capable of being used in the synthesis of polyurethane resins can be used. Examples of the polyol compound include the following. Polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols such as polybutadiene polyols and polyisoprene polyols, so-called high molecular polyols obtained by polymerizing an ethylenically unsaturated monomer in a polyol, and polyester polycarbonate copolymer polyols, etc.

[0133] Among them, polycarbonate polyols and polyester polycarbonate copolymer polyols are preferred.

[0134] Examples of the polycarbonate polyol include the following: poly(nonamethylene carbonate) diol, poly(2-methyl-octamethylene) carbonate diol, poly(hexamethylene carbonate) diol, poly(pentamethylene carbonate) diol, poly(3-methylpentamethylene) carbonate diol, poly(tetramethylene carbonate) diol, poly(trimethylene carbonate) diol, poly(1,4-cyclohexanedimethylene carbonate) diol, poly(2-ethyl-2-butyl-trimethylene) carbonate diol, and their random / block copolymers.

[0135] Examples of the polyester polycarbonate copolymer polyol include the following. Copolymers obtained by polycondensation of lactones such as ε-caprolactone with the above polycarbonate polyol, and copolymers of polyesters obtained by polycondensation of 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.

[0136] (B) Polyisocyanate compound

[0137] The polyisocyanate is selected from commonly known polyisocyanates, such as the following: toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane polyisocyanate, hydrogenated MDI, polymeric MDI, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI), etc. Among them, 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.

[0138] 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. When the NCO / OH ratio is 1.0 to 2.0, the crosslinking reaction proceeds, and so-called "bleeding" as the exudation of unreacted components and low-molecular-weight polyurethanes is suppressed. The NCO / OH ratio is more preferably 1.0 to 1.6. When the NCO / OH ratio is 1.0 to 1.6, bleeding is suppressed, and the hardness of the polymer can be suppressed.

[0139] For any materials used, a polyurethane resin can be obtained by reacting the polyol and the isocyanate by heating. In addition, if either or both of the polyol and the isocyanate have a branched structure and have three or more functional groups, the obtained polyurethane resin becomes a crosslinked polyurethane resin.

[0140] In the present disclosure, the elastic modulus E1 in the region from the outer surface of the developer carrier member to a depth of 0.1 μm measured in a cross-section in the thickness direction of the resin layer of the developer carrier member is preferably 200 MPa or more.

[0141] This elastic modulus E1 indicates that the surface of the developer carrier member is relatively hard. By making the developer carrier member have a hard surface, even when the developer is pressed against the developer carrier member by the developer layer thickness control member, the contact area between the developer and the developer carrier member can be reduced. This reduces the chance of triboelectrification between the developer carrier member and the developer. In addition, charge leakage of the developer to the developer carrier member can be prevented.

[0142] The elastic modulus E1 is preferably 200 to 700 MPa, more preferably 300 to 600 MPa.

[0143] As a means for controlling the elastic modulus E1 to a desired range, from the viewpoint of compatibility with item (3), it is preferable to form the following interpenetrating polymer network structure (IPN structure) on the surface of the developer carrier member.

[0144] As described above, the binder resin of the resin layer is preferably a polyurethane resin, more preferably a crosslinked polyurethane resin. The crosslinked polyurethane resin is suitable as a binder because it has excellent flexibility and strength and can form the interpenetrating polymer network structure (IPN structure) described later. The crosslinked polyurethane resin is preferably, for example, a polyurethane having the above polycarbonate structure.

[0145] The elastic modulus E2 in the region at a depth of 1.0 μm to 1.1 μm from the outer surface of the developer carrier member measured in the cross-section in the thickness direction of the resin layer of the electrophotographic roller is, for example, 1 to 150 MPa, preferably 1 to 100 MPa, more preferably 10 to 100 MPa, and even more preferably 30 to 70 MPa.

[0146] When E2 is within the above range, excessive stress is not applied to the developer, and even when the developer is pressed against the developer carrier member by the developer layer thickness control member, breakage of the developer can be suppressed. This is preferable because high-quality images can be obtained even in higher durability evaluations. From the viewpoint of selectively increasing E1 without increasing E2, it is preferable to form the following interpenetrating polymer network structure (IPN structure) on the surface of the developer carrier member.

[0147] Surface modifier

[0148] The ionization potential I(R) of the outer surface of the developer carrier member is preferably 4.0 to 5.8 eV, more preferably 4.5 to 5.6 eV.

[0149] The means for controlling the ionization potential of the surface of the developer carrier member to a desired range will be described below.

[0150] As a means for increasing the ionization potential of the surface of the developer carrier member, a large amount of a material containing silicon and / or fluorine can be provided on the surface of the developer carrier member. On the contrary, as a means for reducing the surface ionization potential, a large amount of a material having an amino group can be provided on the surface of the developer carrier member.

[0151] As a specific means for increasing the ionization potential of the surface of the developer carrier member, it is preferable to use a surface modifier containing silicon and / or fluorine in the resin layer of the developer carrier member. The surface modifier is preferably a (meth)acrylate monomer and / or oligomer having at least one or both of an organosilicon group and a fluorine group in the molecule. That is, preferably, the resin layer (preferably a crosslinked acrylic resin) contains at least one group selected from an organosilicon group and a fluorine group in the molecule.

[0152] By using these groups, it becomes easier to control the ionization potential of the surface of the developer carrier member within the range of 4.6 to 5.6 eV. The type of acrylate monomer or oligomer used here is preferably a polyfunctional monomer or polyfunctional oligomer having a plurality of acryloyl or methacryloyl groups as functional groups, in order to facilitate introduction into the IPN structure.

[0153] Specifically, the (meth)acrylate monomer or oligomer having an organosilicon group in the molecule is a (meth)acrylate monomer or oligomer having the structure of the following formula (1). The organosilicon group preferably has a siloxane structure, and more preferably has the structure of the following formula (1).

[0154]

[0155] In formula (1), R 1 and R 2 each independently represent H or a hydrocarbon group having 1 to 4 carbon atoms (e.g., an alkyl group).

[0156] Examples of the (meth)acrylate monomer or oligomer having an organosilicon group in the molecule include organosilicon (meth)acrylates such as organosilicon di(meth)acrylate and organosilicon hexa(meth)acrylate, and trifunctional alkylalkoxysilanes such as 3-methacryloxypropyltrimethoxysilane.

[0157] The (meth)acrylate monomer or oligomer having a fluorine group in the molecule is specifically a (meth)acrylate monomer or oligomer having the structure of the following formula (2). For example, fluorine-modified acrylates can be mentioned. (Meth)acrylic acid alkyl esters in which at least a part of the alkyl group is substituted with fluorine can be used.

[0158]

[0159] In formula (2), R 1 and R 2 each independently represent F or a hydrocarbon group having 1 to 4 carbon atoms (e.g., an alkyl group). At least one of R 1 and R 2 represents F.

[0160] Specifically, (meth)acrylate monomers or oligomers having a silicone group and a fluorine group in the molecule are those having a structure in which at least one of R 1 and R 2 in the above formula (1) is a fluoroalkyl group (having 1 to 4 carbon atoms). For example, fluoro / acryloyl-modified organopolysiloxane can be mentioned.

[0161] From the viewpoints of surface orientation and compatibility when mixing the above surface modifier with the raw materials of the polyurethane resin as the binder resin, it is preferable that the weight average molecular weight (Mw) of the surface modifier is 200 to 3000. By making the weight average molecular weight 200 or more, the resin layer is liable to phase-separate during the process from coating to curing, and surface orientation is easily achieved. In addition, when the weight average molecular weight is 3000 or less, the surface modifier is easily compatible. When the weight average molecular weight is 3000 or less, the above surface modifier can be prevented from oozing out to the surface of the developer carrier member. This can prevent the surface modifier from forming an insulating film on the surface of the electrophotographic roller, making it easier to maintain a low surface potential.

[0162] The blending amount of the surface modifier is preferably 1.0 to 5.0 parts by mass relative to 100 parts by mass of the resin constituting the resin layer.

[0163] As a specific means for reducing the ionization potential of the surface of the developer carrier member, it can have a large amount of materials containing an amino group. It is preferable to use a material containing an amino group as the surface modifier.

[0164] Specifically, it is preferable to use an acrylic monomer and / or oligomer containing an amino group as the surface modifier in the resin layer of the developer carrier member. By using these, it becomes easier to control the ionization potential of the surface of the developer carrier member within the range of 4.0 to 4.6 eV. For example, amino (meth)acrylate can be mentioned.

[0165] As the type of the acrylate monomer or oligomer used herein, it is preferable to use a polyfunctional monomer or oligomer having a plurality of acryloyl groups or methacryloyl groups as functional groups so that it is easier to introduce an IPN structure.

[0166] The preferable addition amount and the range of the weight average molecular weight (Mw) are as described above.

[0167] Crosslinked acrylic resin

[0168] Preferably, the resin layer contains a crosslinked polyurethane resin and a crosslinked acrylic resin. In the resin layer, the crosslinked polyurethane resin and the crosslinked acrylic resin preferably have an interpenetrating polymer network structure (IPN structure). The IPN structure is defined as a structure in which the network structures of two or more polymer compounds are intertwined and entangled without being covalently bonded. The IPN structure in the resin layer is preferably formed by the crosslinked acrylic resin penetrating into the network of the three-dimensional crosslinked structure of the crosslinked polyurethane resin.

[0169] The crosslinked acrylic resin is harder than the crosslinked polyurethane resin, so the hardness of the outermost surface can be improved. However, the crosslinked acrylic resin alone is insulating, so the surface potential may become extremely high. In addition, the crosslinked acrylic resin is brittle and is easily scratched by scratches caused by friction. Meanwhile, in the case of an IPN structure in which the crosslinked acrylic resin penetrates into the network of the three-dimensional crosslinked structure of the crosslinked polyurethane resin near the outer surface of the resin layer, it is less likely to have hardness and brittleness, and can impart high strength while maintaining flexibility.

[0170] In addition, the crosslinked acrylic resin is preferably a copolymer of the above surface modifier and a (meth)acrylic monomer provided by impregnation. From the viewpoints of controlling the ionization potential and surface potential of the developer carrier member and achieving both the hardness E1 and E2 which are preferred characteristics of the developer carrier member, this configuration is preferred.

[0171] In order to form an IPN structure of the crosslinked acrylic resin and the crosslinked polyurethane resin on the outer surface and near the outer surface of the resin layer, the following method is preferred. The resin layer containing the crosslinked polyurethane is impregnated with a liquid (meth)acrylic monomer. This is cured simultaneously with the surface modifier in the resin layer.

[0172] The content of the crosslinked acrylic resin in the resin layer is preferably 1.0 to 5.0 parts by mass, more preferably 3.0 to 5.0 parts by mass, relative to 100 parts by mass of the crosslinked polyurethane resin.

[0173] The thickness of the resin layer is, for example, 3 to 50 μm, preferably 5 to 30 μm, more preferably 10 to 20 μm.

[0174] The types of (meth)acrylic monomers used here include polyfunctional monomers having a plurality of acryloyl or methacryloyl groups as functional groups to form a crosslinked structure. As the (meth)acrylic monomer for the crosslinked acrylic resin, a difunctional (meth)acrylic monomer or a trifunctional (meth)acrylic monomer is preferably used, and these monomers are preferably used in combination.

[0175] The difunctional (meth)acrylic monomer is preferably at least one selected from the group consisting of alkylene glycol di(meth)acrylate and alkylene oxide (ethylene oxide, propylene oxide) modified products of alkylene glycol di(meth)acrylate. For example, propylene oxide-modified neopentyl glycol diacrylate can be mentioned.

[0176] Examples of the trifunctional (meth)acrylic monomer include trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate.

[0177] The polymerization method of the (meth)acrylic monomer is not particularly limited, and known methods can be used. Specifically, methods such as heating and ultraviolet irradiation can be mentioned. For each polymerization method, known radical polymerization initiators or ionic polymerization initiators can be used.

[0178] These polymerization initiators can be used alone, or two or more of them can be used in combination.

[0179] The heating device and the ultraviolet irradiation device can be any known devices. Examples of the light source for ultraviolet irradiation include LED lamps, high-pressure mercury lamps, metal halide lamps, xenon lamps, and low-pressure mercury lamps. The cumulative amount of light required for polymerization can be appropriately adjusted according to the type and amount of the compound and polymerization initiator used.

[0180] Conductive filler

[0181] The resin layer preferably contains a conductive filler to obtain conductivity. It is more preferable to use an electronic conductive agent as the conductive filler in the resin layer. The electronic conductive agent is preferably a conductive particle that exhibits electronic conductivity and has a surface functional group that can interact with the functional groups present in the following additives.

[0182] Examples of the electronic conductive agent that exhibits 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 that have been surface-treated with acidic functional groups; and metal-based conductive particles such as aluminum and iron that have been surface-treated with acidic functional groups.

[0183] Among them, it is preferable to use at least one selected from the group consisting of carbon black products with high surface functional group stability. The conductive filler preferably includes carbon black. In addition, in order to obtain the desired impedance value and surface potential, it is particularly preferable to use carbon black with a number average diameter of primary particles of 30 nm or less, a DBP absorption of 90 mL / 100 g or less, and a pH of 4.0 or less, which results in a higher degree of dispersion in the resin layer.

[0184] When the number-average diameter of the primary particles of carbon black is 30 nm or less, the aggregates (primary aggregates), which are the smallest dispersion units of carbon black, become smaller. As a result, the structure (the size of particle connection) also becomes smaller, 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 smaller 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 5 to 30 nm, more preferably 20 to 28 nm.

[0185] When the DBP absorption of carbon black is 90 mL / 100 g or less, the structure of carbon black becomes smaller, and it is not easy to form a conductive path, making it easier to obtain a sufficiently high impedance. The lower the DBP absorption, the more preferable, and there is no particular lower limit. For example, the DBP absorption of carbon black is 30 to 90 mL / 100 g, more preferably 40 to 60 mL / 100 g.

[0186] When the pH of carbon black is 4.0 or less, the repulsive force of the surface functional groups of carbon black provides a dispersion stability effect, and carbon black is not easily aggregated, making it easier to obtain a sufficiently high impedance. The lower the pH of carbon black, the more preferable, and there is no particular lower limit. For example, the pH of carbon black is 2.0 to 4.0, more preferably 2.2 to 2.8.

[0187] However, even when the number-average diameter of the primary particles, the DBP absorption, and the pH of carbon black are within the above ranges, when using polycarbonate polyurethane as the binder resin, it may not be completely dispersed and the desired impedance may not be obtained. The reason why carbon black with the desired raw material properties cannot be dispersed when using polycarbonate polyurethane as the binder resin is not clear, but it is speculated as follows.

[0188] The hydroxyl group as the surface functional group of carbon black easily interacts with the terminal hydroxyl group of polycarbonate diol. At the same time, the structure in which the carbonate bond is bonded to the hydrocarbon group and exists between the two hydroxyl groups of polycarbonate diol is hydrophobic due to the presence of the hydrocarbon group and is not easily interacted with carbon black. Since the structure is more stable when a hydrophobic segment is close to another hydrophobic segment and when a hydrophilic segment is close to another hydrophilic segment, hydrophilic carbon black will be present near similar hydrophilic carbon black. As a result, carbon black is easily aggregated and difficult to disperse.

[0189] When using polycarbonate polyurethane as the binder resin, in order to sufficiently disperse carbon black with the number-average diameter of the primary particles, the DBP absorption, and the pH within the above ranges, it is more preferable to add the following additives.

[0190] It is desirable to add carbon black to achieve a desired volume resistivity, but its content is preferably 30 parts by mass or less relative to 100 parts by mass of the resin component forming the resin layer. More preferably, the content of carbon black is 10 to 30 parts by mass, and even more preferably 15 to 25 parts by mass.

[0191] When the content of carbon black is 30 parts by mass or less, the distance between carbon black particles in the coating liquid is appropriately maintained, the probability of collision caused by the Brownian motion of carbon black is reduced, and carbon black is not easily aggregated. Therefore, carbon black is easily dispersed and the dispersion stability is also improved. As a result, carbon black is well dispersed in the resin layer formed by forming a film from the coating liquid.

[0192] To achieve the above specific resistance and surface potential, it is preferable to control the dispersion of carbon black. Regarding the dispersion particle size of carbon black, when the arithmetic mean of the equivalent circle diameter of carbon black in the resin layer is represented by Rc, preferably, Rc is 60.0 nm or less. When the standard deviation of the equivalent circle diameter is σc [nm], preferably, σc / Rc is from 0.000 to 0.650.

[0193] In addition, regarding the distance between carbon black particles, when the arithmetic mean of the distance between the walls of carbon black in the resin layer is represented by d, preferably, d is 80.0 to 150.0 nm, and when the standard deviation of the distance between the walls is represented by σd [nm], preferably, σd / d is from 0.000 to 0.600.

[0194] The reason for more easily achieving high impedance and low surface potential within the above numerical ranges of the equivalent circle diameter and the distance between the walls is speculated as follows.

[0195] When the dispersion particle size is large, there are places where the distance between the walls is close, and it is easy to form a conductive path, so both the impedance and the surface potential are low. At the same time, when the dispersion particle size is smaller, the distance between the walls becomes more uniform, making it difficult to form a conductive path, increasing the resistance, and at the same time the capacitance becomes smaller, resulting in a higher impedance. In terms of the surface potential, local charge accumulation is not likely to occur, thereby making it possible to lower the surface potential.

[0196] When an insulating material such as a silane coupling agent is coated on the surface of carbon black, it will no longer be able to function as an electric double layer capacitor. As a result, both the impedance and the surface potential are high.

[0197] A plurality of types of carbon black can also be used in combination, provided that the impedance value and the surface potential are not affected.

[0198] The arithmetic mean Rc of the circular equivalent diameter is more preferably from 40.0 to 60.0 nm, even more preferably from 50.0 to 60.0 nm. σc / Rc is more preferably from 0.500 to 0.650, even more preferably from 0.550 to 0.650. σc is more preferably from 25.0 to 45.0 nm, even more preferably from 30.0 to 40.0 nm.

[0199] The arithmetic mean Rc of the circular equivalent diameter and the standard deviation σc can be changed, for example, by the dispersion state in a grinder or the like when preparing the coating liquid for forming the resin layer. A weaker dispersion tends to increase Rc and σc, and a stronger dispersion tends to decrease Rc and σc. Normally, Rc converges, so once a certain dispersion state is exceeded, σc can be reduced while Rc remains almost constant, and σc / Rc can be reduced.

[0200] The arithmetic mean d of the wall-to-wall distance is more preferably from 90.0 to 130.0 nm, even more preferably from 105.0 to 115.0 nm. σd / d is more preferably from 0.500 to 0.600, even more preferably from 0.550 to 0.590. σd is more preferably from 50.0 to 80.0 nm, even more preferably from 60.0 to 70.0 nm.

[0201] The arithmetic mean d of the wall-to-wall distance and the standard deviation σd can be changed, for example, by the dispersion state in a grinder or the like when preparing the coating liquid for forming the resin layer. A weaker dispersion tends to decrease d and increase σd, and a stronger dispersion tends to increase d and decrease σd. Therefore, a weaker dispersion tends to increase σd / d, and a stronger dispersion tends to decrease σd / d.

[0202] Additive

[0203] A further preferred embodiment is to use an additive to further improve the dispersibility of carbon black in the binder resin using polycarbonate polyurethane. 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 appropriately used. One method of including the above additive in the surface layer is to include a dispersant in the coating liquid for forming the surface layer. In the surface layer formed using the coating liquid for forming the 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 can be introduced at the end of the polymer chain of the polyurethane. Even in such a case, an effect of improving the dispersibility of carbon black can be expected, but preferably, the additive exists independently of the polyurethane in the surface layer.

[0204] Among the compounds having the structures represented by Structural Formulas (5) to (7), the compound having the structure represented by Structural Formula (5) is more preferably used because particularly excellent carbon black dispersibility and affinity with polycarbonate polyurethane can be achieved.

[0205] Structural Formula (5)

[0206]

[0207] Structural Formula (6)

[0208]

[0209] Structural Formula (7)

[0210]

[0211] 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 addition mole numbers, and each independently represents a number of 1 or more (preferably 5 to 30, more preferably 10 to 25).

[0212] 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 addition mole numbers, and each independently represents a number of 1 or more (preferably 1 to 30, more preferably 5 to 30).

[0213] In Structural Formula (7), R71 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms. x is the average addition mole number, and is a number of 1 or more (preferably 1 to 30, more preferably 4 to 15).

[0214] Structural Formula (5) is a polyoxyethylene polyoxypropylene alkyl ether, which is a polyether monoalcohol having a structure in which ethylene oxide and propylene oxide are addition-polymerized in a block form. The terminal hydroxyl group of the polyether monoalcohol interacts with the surface functional groups of carbon black as a conductive filler through hydrogen bonds, and the polyether monoalcohol acts as a dispersant for carbon black. In addition, this structure has good compatibility with polycarbonate polyurethane to enhance the effect as a dispersant for carbon black.

[0215] Ethylene oxide is introduced into this structure to ensure the uniform presence of additives in polycarbonate polyurethane. This is considered because the ethylene group in ethylene oxide has good compatibility with the hydrophobic hydrocarbon groups in polycarbonate polyurethane. Furthermore, propylene oxide is introduced into this structure to improve the dispersibility of the conductive filler dispersed in the resin layer. This is considered because the side-chain methyl group of propylene oxide interacts with the conductive filler, thereby improving the dispersibility.

[0216] R51, which is a monovalent hydrocarbon group having 1 to 12 carbon atoms, is introduced into this structure to ensure the uniform presence of the additive in the polycarbonate polyurethane. As a monovalent hydrocarbon group, this group has good compatibility with the hydrophobic hydrocarbon groups in the polycarbonate polyurethane, allowing the additive to be uniformly present in the polycarbonate polyurethane. Due to the 12 or fewer carbon atoms in this group, steric hindrance is less likely to occur in the polycarbonate polyurethane, making it easier for the additive to be uniformly present.

[0217] Since the compound of formula (5) has a monoalcohol structure, its reactivity is lower than that of diols. As a result, it is less likely to participate in the urethanization reaction caused by the reaction of isocyanate with polyol, and it is less likely to cause a decrease in the resistance of the polyurethane due to the introduction of an ether structure into the polycarbonate polyurethane.

[0218] Commercially available polyoxyethylene polyoxypropylene alkyl ethers can be used, or they can be obtained by synthesis. The synthesis of polyoxyethylene polyoxypropylene alkyl ethers can be carried out by performing step (B) after the following step (A). Step (B) can be carried out on commercially available products having the structure obtained by completing step (A).

[0219] Step (A): Reaction of an alcohol with ethylene oxide.

[0220] Step (B): Reaction of the product obtained in step (A) with propylene oxide.

[0221] In step (A), the reaction can be promoted by adding ethylene oxide to the alcohol at 50 °C to 200 °C, more preferably at 100 °C to 160 °C, in the presence of a catalyst. Since the boiling point of ethylene oxide is 10.7 °C and it is a gas at the above temperatures, it is preferably carried out under a pressurized environment in a sealed container. The pressure is preferably 0.1 to 1.0 MPa. The reaction time is not particularly limited, but in order to reduce the amount of unreacted ethylene oxide, it is preferably about 1 to 3 h.

[0222] As the catalyst, an acidic catalyst or a basic catalyst can be used, but a basic catalyst is preferred for ease of purification after the reaction. Examples of basic catalysts include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, hydroxides of alkaline earth metals such as calcium hydroxide and barium hydroxide, ammonium hydroxide, and tertiary amines. Considering the ease of reaction and reaction efficiency, sodium hydroxide and potassium hydroxide are particularly preferred. Examples of acidic catalysts include Bronsted acids such as sulfuric acid and phosphoric acid, and Lewis acids such as tin tetrachloride and boron trifluoride.

[0223] For sodium hydroxide and potassium hydroxide, the amount of the catalyst used is preferably 0.1 to 5 mol% relative to 1 mole of the alcohol. Since ethylene oxide reacts with water to form ethylene glycol, it is important to prevent moisture from entering the reaction as much as possible, and if necessary, dehydration treatment can be carried out before the reaction in step (A).

[0224] Step (B) can be carried out under the same conditions as step (A). Since the boiling point of propylene oxide is 34.2 °C and it is a gas at a reaction temperature of 50 to 200 °C, it is preferable to carry out the reaction in a sealed container under a pressurized environment. The catalyst can be the catalyst used as such in step (A), or a newly added catalyst. If a new catalyst is added, the catalyst used in step (A) is preferred.

[0225] The structural formula (6) is a polyetheramine (monoamine) having a structure in which ethylene oxide and propylene oxide are addition-polymerized in a block form. The terminal amino group of the polyetheramine interacts with the surface functional groups of carbon black as a conductive filler through hydrogen bonds, and the polyetheramine acts as a dispersant for carbon black. In addition, in order to improve the effect as a dispersant, R61 which is a monovalent hydrocarbon group having 1 to 8 carbon atoms is introduced to obtain a structure that is easily compatible with the hydrophobic functional groups of polycarbonate polyurethane and also has good compatibility with polycarbonate polyurethane.

[0226] Commercially available polyether monoamines can be used or polyether monoamines can be obtained by synthesis. The synthesis of polyether monoamines can be carried out by performing step (D) after the following step (C).

[0227] Step (C): Oxidation reaction of the compound of structural formula (5) which is a secondary alcohol.

[0228] Step (D): Reductive amination reaction of the product obtained in step (C).

[0229] Step (C) is a reaction to form a ketone by the oxidation reaction of a secondary alcohol. The synthesis of a ketone by the oxidation of a secondary alcohol can be carried out by an oxidation reaction using heavy metal salts such as chromic acid and manganese dioxide and their derivatives, or by an oxidation reaction using non-heavy metal salts such as dimethyl sulfoxide (DMSO) and hypohalous acids such as hypochlorous acid.

[0230] Either method can be used for the synthesis, but considering the environmental impact of heavy metals, it is preferable to use the oxidation reaction of dimethyl sulfoxide (DMSO) and hypohalous acids such as hypochlorous acid. In addition, dimethyl sulfoxide (DMSO) can react explosively at room temperature depending on the electrophilic activating reagent used, so a low temperature of -60 °C is required, making the method using hypohalous acid more preferable. Hypohalous acids include hypochlorites such as sodium hypochlorite and calcium hypochlorite (bleaching powder). These hypochlorites can react with secondary alcohols in acetic acid to obtain ketones.

[0231] When using dimethyl sulfoxide (DMSO), an electrophilic activating reagent is also required. The electrophilic activating reagent increases the electrophilicity of sulfur in DMSO and then subjects it to nucleophilic attack by an alcohol hydroxyl group. This nucleophilic attack produces a dimethylalkoxysulfonium salt, which decomposes to produce a ketone and dimethyl sulfide. Examples of the electrophilic activating reagent include dicyclohexylcarbodiimide (DCC), acetic anhydride, phosphorus pentoxide, sulfur trioxide-pyridine complex, trifluoroacetic anhydride, oxalyl chloride, and halogens, etc.

[0232] Step (D) is a reductive amination reaction for converting a ketone into an amine. The reaction is divided into two steps. First, the carbonyl group reacts with an amine to produce an iminium cation. Next, a hydride reducing agent conducts a nucleophilic attack on the iminium cation to produce an amine. It is preferred to use a borohydride reagent as the reducing agent. Examples of the borohydride reagent include sodium cyanoborohydride, sodium triacetoxyborohydride, and 2-methylpyridine borane. Among them, sodium triacetoxyborohydride and 2-methylpyridine borane are preferred due to their low toxicity. In the reductive amination reaction using a borohydride reagent, where a bulky structure is formed, steric hindrance makes it difficult to generate an iminium cation. Therefore, R61 in Structural Formula (6) is preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms.

[0233] Structural Formula (7) is polyoxyethylene alkyl ether acetic acid. The terminal carboxylic acid in Structural Formula (7) interacts with the surface functional groups of carbon black, which serves as a conductive filler, through hydrogen bonding, and polyoxyethylene alkyl ether acetic acid acts as a dispersant for carbon black. Additionally, in order to improve the effect as a dispersant, R71, which is a monovalent hydrocarbon group having 1 to 12 carbon atoms, is introduced to obtain a structure that is easily compatible with the hydrophobic functional groups of polycarbonate polyurethane and also has good compatibility with polycarbonate polyurethane.

[0234] Commercially available polyoxyethylene alkyl ether acetic acid can be used, or polyoxyethylene alkyl ether acetic acid can be obtained through synthesis. The synthesis of polyoxyethylene alkyl ether acetic acid can be carried out by performing Step (F) after the following Step (E). Step (F) can be performed on a commercially available product having the structure obtained by completing Step (E).

[0235] Step (E): The reaction of an alcohol with ethylene oxide.

[0236] Step (F): The oxidation reaction of the primary alcohol that is the product of Step (E).

[0237] Step (E) is the same as Step (A) and can be implemented in the same manner as Step (A).

[0238] In step (F), a primary alcohol is oxidized to produce a carboxylic acid. When the primary alcohol is oxidized, an aldehyde is produced, and subsequent oxidation produces a carboxylic acid. Therefore, reaction methods and conditions that do not stop at the aldehyde need to be selected. Methods for obtaining a carboxylic acid by oxidizing a primary alcohol include oxidation with an oxidizing agent and catalytic dehydrogenation reaction with a catalyst. Examples of the oxidizing agent include permanganate, chromic acid, ruthenium tetroxide, and hypochlorite. Catalysts for the dehydrogenation reaction include palladium, platinum, iridium, rhodium, and manganese.

[0239] The compounds represented by structural formulas (5) to (7) are used as dispersants for carbon black and are also compounds having a high affinity for polycarbonate polyurethane. Surfactants are generally 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 acting on the surface functional groups of carbon black, so their surface activity is weak and they are generally not used. Coupling agents and nonionic surfactants are generally used as dispersants for carbon black.

[0240] Silane coupling agents, titanate coupling agents, and aluminum coupling agents are used as coupling agents, and polyester and polyether surfactants are used as nonionic surfactants. However, when these dispersants are added to a level sufficient to increase the dispersibility of carbon black in polycarbonate polyurethane (50 to 100% by mass relative to carbon black), the conductivity of the carbon black and the binder resin will be hindered. On the contrary, when the addition amount is at a level that does not hinder the conductivity of the carbon black and the binder resin (10 to 40% by mass relative to carbon black), the dispersibility of carbon black cannot be obtained.

[0241] The content of the compounds represented by structural formulas (5) to (7) is preferably within the following range. The content of the compounds represented by structural formulas (5) to (7) in the resin layer is preferably 3.0 to 7.0% by mass. This content is also preferably 18.9 to 46.0 parts by mass relative to 100 parts by mass of carbon black.

[0242] By maintaining the content of the additives in the resin layer within the above range, the dispersibility of carbon black in polyurethane is further improved, and it is possible to more easily achieve the desired impedance value and surface potential.

[0243] The presence of additives in the resin layer can be confirmed and quantitatively evaluated by the following method. By cutting the resin layer of the developer carrier member and using, for example, 1 1H-NMR, 13 13C-NMR, XPS, 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 additives in the resin layer, and the ratio can be calculated from the ratio of the peaks, etc.

[0244] Alternatively, by immersing the slices in an organic solvent such as 2-butanone (methyl ethyl ketone; MEK) overnight for extraction, and using 1 1H-NMR, 13 13C-NMR, XPS, and FT-IR, the ratio of additives introduced during the polymerization reaction of the resin and additives not introduced can be calculated.

[0245] The following are embodiments of a structure in which at least one of the compounds having the structures represented by the structural formulas (5) and (6) is bonded to polyurethane (a structure that reacts during the polymerization of polyurethane).

[0246] - In the case of the structure represented by the structural formula (5), the compound having the structure represented by the structural formula (5) is a urethanation structure.

[0247] - In the case of the structure represented by the structural formula (6), the compound having the structure represented by the structural formula (6) is a ureatation structure.

[0248] Roughening particles

[0249] The resin layer may contain roughening particles. The roughening particles may be, for example, spherical particles. The particle size of the roughening particles is preferably in the range of 1 to 150 μm, more preferably in the range of 5 to 30 μm. For example, at least one spherical particle selected from the following particles may be used.

[0250] Polyurethane 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, and polypropylene resin particles. Polyurethane resin particles are preferred.

[0251] The content of the roughening particles in the resin layer is preferably 1 to 20% by mass, more preferably 5 to 15% by mass.

[0252] Intermediate layer (elastic layer)

[0253] The electrophotographic roller may have an elastic layer as the intermediate layer 13 on the outer surface of the substrate. For example, the electrophotographic roller has an elastic layer between the substrate and the resin layer. The elastic layer is not particularly limited, and any known elastic layer for electrophotographic rollers can be used. For example, a cured product of an addition-curable liquid silicone rubber mixture can be used. The thickness of the intermediate layer can be, for example, 1.0 mm to 20.0 mm or 8.0 mm to 15.0 mm.

[0254] The addition-curable liquid silicone rubber can be, for example, a liquid dimethylpolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule, or a liquid dimethylpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule, etc., which are known addition-curable liquid silicone rubbers. Fillers such as carbon black can also be used in the addition-curable liquid silicone rubber mixture.

[0255] Production method of resin layer

[0256] The method for producing an electrophotographic roller preferably includes the steps of preparing a substrate including a conductive outer surface and forming a resin layer on the outer surface side of the substrate. The step of forming the resin layer preferably includes the step of coating a urethane raw material mixture containing a urethane raw material for forming a crosslinked polyurethane resin and a surface modifier and curing it to obtain a crosslinked polyurethane resin. Further, preferably, the crosslinked polyurethane resin is impregnated with a (meth)acrylic monomer for forming a crosslinked acrylic resin, and the surface modifier is polymerized with the (meth)acrylic monomer to form a crosslinked acrylic resin, thereby obtaining the resin layer.

[0257] Before the step of forming the resin layer, the step of forming an elastic layer on the outer surface of the substrate can also be performed. The elastic layer can be obtained, for example, by coating a silicone rubber mixture on the outer surface of the substrate and curing it.

[0258] The method for forming the resin layer containing the crosslinked polyurethane resin is not particularly limited, but a coating forming method using a liquid coating is preferred. For example, it is preferred to disperse and mix each material for the resin layer as a urethane raw material mixture in a solvent to form a coating, then coat it on the conductive substrate, and dry and cure or heat and cure it.

[0259] From the viewpoint of compatibility with the polyol and isocyanate compound which are raw materials for the crosslinked polyurethane resin, the solvent is preferably a polar solvent. Examples of the polar solvent include alcohols such as methanol, ethanol, and n-propanol, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and esters such as methyl acetate and ethyl acetate. Among them, one or more solvents compatible with other materials can be used in combination.

[0260] The solid content at the time of forming the coating can be freely adjusted by the amount of the mixed solvent, but from the viewpoint of uniformly dispersing an electroconductive material such as carbon black described later, it is preferred to set the solid content to 20 to 40% by mass. For dispersion and mixing, known dispersion devices using beads, such as a sand mill, a paint shaker, a dyno mill, or a bead mill, can be used. In addition, as the coating method, dip coating, loop coating, spraying, or roll coating, etc. can be used.

[0261] For example, a liquid coating is obtained by mixing a polyol, an isocyanate-based compound, etc. which are raw materials of a binder resin, a conductive filler, a surface modifier, an additive, and the like. Then, the resin layer coating is applied onto the above substrate. Then, a crosslinked polyurethane resin is formed by drying and solidifying or by heating and curing. At this time, by setting the weight-average molecular weight of the surface modifier to 2,000 to 3,000, it is possible to easily orient the surface modifier near the surface without bleeding out to the surface. At this time, the surface modifier exists in an unreacted state near the surface in the crosslinked polyurethane resin chain.

[0262] Next, the resin layer formed as described above is impregnated with a liquid (meth)acrylic acid-based monomer. The liquid (meth)acrylic acid-based monomer can be impregnated as it is, or can be impregnated as an impregnation treatment liquid appropriately diluted with various solvents. By appropriately diluting the liquid (meth)acrylic acid-based monomer with various solvents, a resin layer with a more uniform surface composition can be obtained.

[0263] The solvent can be freely selected as long as it satisfies both the affinity for the resin layer and the solubility of the (meth)acrylic acid-based monomer. For example, alcohols such as methanol, ethanol, and n-propanol, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and esters such as methyl acetate and ethyl acetate can be used.

[0264] The impregnation liquid is appropriately mixed with a polymerization initiator. Details of the polymerization initiator are as described above. There is no particular limitation on the method of impregnating with the impregnation liquid, and dip coating, loop coating, spray coating, or roll coating can be used. It is preferable to keep the air-drying time within 15 minutes to prevent the surface modifier added to the resin layer from bleeding out to the surface due to the solvent in the impregnation liquid. Then, drying is carried out at 90°C for 1 hour to volatilize the solvent.

[0265] After such impregnation treatment with the impregnation liquid, the (meth)acrylate monomer or oligomer added to the resin layer as a surface modifier polymerizes and cures simultaneously with the (meth)acrylic acid-based monomer from the impregnation treatment. As the reaction proceeds, the (meth)acrylate monomer or oligomer added to the resin layer has a large volume, and thus cures while orienting toward the outermost surface. Through such steps, an IPN structure is easily formed in an entangled form near the surface of the network structure of the crosslinked polyurethane resin in a state where groups derived from the surface modifier such as a silicone group and a fluorine group are oriented on the outermost surface. The polymerization and curing methods are not particularly limited, and known methods can be used. Specific examples include methods such as thermal curing and ultraviolet irradiation.

[0266] Developer

[0267] Next, the developer will be described. The developer is, for example, a toner. The toner preferably has toner particles containing a binder resin and external additives on the surface of the toner particles.

[0268] Examples of vinyl resins used as the binder resin include the following.

[0269] Homopolymers of styrene and its substituted derivatives, such as polystyrene and polyvinyltoluene;

[0270] Styrene copolymers, such as styrene - propylene copolymer, styrene - vinyltoluene copolymer, styrene - vinylnaphthalene copolymer, styrene - methyl acrylate copolymer, styrene - ethyl acrylate copolymer, styrene - butyl acrylate copolymer, styrene - octyl acrylate copolymer, styrene - dimethylaminoethyl acrylate copolymer, styrene - methyl methacrylate copolymer, styrene - ethyl methacrylate copolymer, styrene - butyl methacrylate copolymer, styrene - dimethylaminoethyl methacrylate copolymer, styrene - vinyl methyl ether copolymer, styrene - vinyl ethyl ether copolymer, styrene - vinyl methyl ketone copolymer, styrene - butadiene copolymer, styrene - isoprene copolymer, styrene - maleic acid copolymer, and styrene - maleate copolymer.

[0271] Polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, polyester resin, polyamide resin, epoxy resin, and polyacrylic acid.

[0272] These can be used alone or in combination. Among them, from the viewpoint of ease of controlling the developing characteristics and fixing performance, styrene copolymers and styrene - butyl acrylate copolymer are particularly preferred.

[0273] Wax

[0274] Next, the wax will be described. The toner particles may contain wax. As the wax, waxes known to be used in developers can be used.

[0275] For example, petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum and their derivatives;

[0276] Montan wax and its derivatives;

[0277] Hydrocarbon waxes produced by the Fischer - Tropsch process and their derivatives;

[0278] Polyolefin waxes such as polyethylene and their derivatives;

[0279] Natural waxes such as carnauba wax and candelilla wax and their derivatives, etc. Derivatives include oxides, block copolymers with vinyl monomers, and graft-modified products. In addition, higher fatty alcohols, fatty acids such as stearic acid and palmitic acid, amide waxes, ester waxes, hydrogenated castor oil and its derivatives, vegetable waxes, and animal waxes, etc. can also be used.

[0280] The wax content is preferably 1 to 30 parts by mass relative to 100 parts by mass of the binder resin.

[0281] Colorant

[0282] Next, the colorant will be described. The toner particles may contain a colorant. The colorant is selected in consideration of the hue angle, chroma, lightness, lightfastness, OHP transparency, and dispersibility in the developer.

[0283] Carbon black, magnetic fine particles, and a colorant toned to black using the following yellow, magenta, and cyan colorants can be used as the black colorant.

[0284] Many dyes and carbon black have polymerization inhibitory properties, so care must be taken when producing the developer by polymerization. In addition, when producing a magnetic developer, it is preferable to use magnetic fine particles as the black colorant, and the number average particle diameter of the magnetic fine particles is preferably 0.10 to 0.40 μm.

[0285] The content of the magnetic fine particles is preferably 20 to 200 parts by mass, more preferably 40 to 150 parts by mass, relative to every 100 parts by mass of the polymerizable monomer or binder resin.

[0286] The yellow colorant is represented by compounds such as condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methylene compounds, and allylamide compounds. Specific examples include the following: C.I. Pigment Yellow 12, 13, 14, 15, 17, 62, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 128, 129, 138, 147, 150, 151, 154, 155, 168, 180, 185, and 214.

[0287] Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone, quinacridone compounds, basic dye lakes compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specific examples include the following: C.I. Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 238, 254, and 269, and C.I. Pigment Violet 19.

[0288] Examples of cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specific examples include C.I. Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0289] These colorants can be used alone, in mixtures, or even in the form of solid solutions.

[0290] The content of colorants other than magnetic fine particles is preferably 1 to 20 parts by mass relative to 100 parts by mass of the polymerizable monomer or binder resin.

[0291] Production method

[0292] There is no particular limitation on the production method of the developer, and it can be produced by a pulverization method, dispersion polymerization method, association aggregation method, dissolution suspension method, suspension polymerization method, or the like.

[0293] The developer particles (particles before adding external additives) contained in the developer can be produced by a pulverization method, but are preferably produced in an aqueous medium by a dispersion polymerization method, association aggregation method, dissolution suspension method, suspension polymerization method, or the like, and among them, the suspension polymerization method is more preferred.

[0294] In the suspension polymerization method, a colorant and, if necessary, a polymerization initiator, crosslinking agent, charge control agent, and other additives are dissolved or dispersed in a polymerizable monomer to obtain a polymerizable monomer composition. Then, the polymerizable monomer composition is added to an aqueous medium (which may contain a dispersion stabilizer if necessary) to form particles of the polymerizable monomer composition, and the polymerizable monomer contained in the particles is polymerized to obtain developer particles. The developer obtained by the suspension polymerization method (hereinafter also referred to as "polymer developer") has individual developer particles with a shape that is almost uniformly spherical, which tends to improve the fluidity at the toner layer thickness control member and promote uniform triboelectrification. As a result, the image quality is easily improved.

[0295] Polymerizable monomers used for producing the polymer developer include the following.

[0296] Examples of polymerizable monomers include styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, and p-ethylstyrene;

[0297] acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate;

[0298] Methacrylates, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate, etc.; and so on.

[0299] Other examples include acrylonitrile, methacrylonitrile, and acrylamide, etc. These can be used alone or in combinations of two or more.

[0300] Among the above polymerizable monomers, from the viewpoints of the developing characteristics and durability of the developer, styrene or a styrene derivative is preferably used alone or in combinations of two or more.

[0301] As the polymerization initiator, a polymerization initiator having a half-life of 0.5 to 30.0 h during the polymerization reaction is preferred. The usage amount is preferably 0.5 to 20.0 parts by mass relative to 100 parts by mass of the polymerizable monomer.

[0302] Specific examples of the polymerization initiator include azo or diazo polymerization initiators such as 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile, and peroxide polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, tert-butyl 2-ethylhexanoate peroxide, and tert-butyl peroxyneopentanoate.

[0303] When producing developer particles by polymerization, a crosslinking agent can be added, and its preferred amount is 0.01 to 5.00 parts by mass relative to 100 parts by mass of the polymerizable monomer.

[0304] Here, the crosslinking agent used is mainly a compound having two or more polymerizable double bonds, and examples thereof include the following.

[0305] Aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene;

[0306] Carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate;

[0307] Divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and

[0308] Compounds having three or more vinyl groups.

[0309] These can be used alone or as a mixture of two or more kinds.

[0310] As a dispersion stabilizer present in an aqueous medium, various surfactants, organic dispersants, and inorganic dispersants can be used. Among them, inorganic dispersants are preferably used because they are less likely to generate harmful ultrafine powders and because they obtain dispersion stability due to their steric hindrance. Examples of such inorganic dispersants include polyvalent metal phosphates such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, and hydroxyapatite, carbonates such as calcium carbonate and magnesium carbonate, inorganic salts such as calcium metasilicate, calcium sulfate, and barium sulfate, and inorganic compounds such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide.

[0311] These inorganic dispersants are preferably used in an amount of 0.2 to 20.0 parts by mass relative to 100 parts by mass of the polymerizable monomer. In addition, the dispersion stabilizer can be used alone or in a combination of multiple kinds. Furthermore, surfactants can be used in combination.

[0312] The obtained resin particles are filtered, washed, and dried to obtain toner particles as developer particles. After drying, the toner particles can be classified into coarse particles and fine particles, and external additives such as inorganic fine particles can be added to the toner particles.

[0313] External additive

[0314] As the inorganic fine particles used as external additives, inorganic fine particles having a number average particle diameter of primary particles of 4 to 80 nm are preferred, and inorganic fine particles having a number average particle diameter of 6 to 40 nm are more preferred. In addition to the above inorganic fine particles, inorganic fine particles having a number average particle diameter of primary particles of 100 to 200 nm can also be used in combination. By doing so, the fluidity of the developer during the entire durability period can be ensured, and the concentration can be easily improved.

[0315] Inorganic fine particles are added to improve the fluidity of the developer and control the charging performance of the developer particles. In the present disclosure, from the viewpoint of controlling the triboelectric charging series of the developer, it is necessary to select inorganic fine particles. In order to control the triboelectric charging series to negative charging performance, a method of treating the surface of the inorganic fine particles with a silicone oil or a fluorine-based treatment agent can be mentioned. On the contrary, in order to control the triboelectric charging series to positive charging performance, it is necessary to treat the surface of the inorganic fine particles with a treatment agent such as an amino silane.

[0316] The number average particle diameter of the primary particles of the inorganic fine particles is measured using a photograph of the developer taken with a scanning electron microscope at an enlarged scale.

[0317] As the inorganic fine particles, fine particles such as silica, titanium oxide, and alumina, or fine particles of their composite oxides can be used. As the silica fine particles, for example, fumed silica (also referred to as fumed silica or pyrogenic silica) produced by the vapor phase oxidation of silicon halide, and wet-process silica can be mentioned.

[0318] The addition amount of the inorganic fine particles is preferably 0.1 to 4.0 parts by mass with respect to 100 parts by mass of the developer particles. The content of the inorganic fine particles can be quantified using a calibration curve created from standard samples by fluorescence X-ray analysis.

[0319] The triboelectric charging series of the developer is represented by the value of the ionization potential. The ionization potential I(T) of the developer is preferably 4.0 to 5.6 eV, more preferably 4.5 to 5.6 eV. Within the above range, it is easy to control the ionization potential difference of the developer carrier member to an appropriate range.

[0320] The ionization potential I(T) of the developer can be controlled by the surface treatment agent of the external additive used in the developer. The external additive is preferably surface-treated. The surface treatment agent having an amino group easily reduces I(T). In addition, the surface treatment agent containing fluorine easily increases I(T).

[0321] Processing cartridge and electrophotographic image forming apparatus

[0322] The developer carrier member according to the present disclosure can be suitably used as a developer carrier member, a developer supply roller, and a developing sleeve in a process cartridge. Figure 3 is a schematic cross-sectional view of an example of a process cartridge according to an aspect of the present disclosure. In Figure 3 it, the developer carrier member is installed as the developer carrier member 14.

[0323] The process cartridge 22 is configured to be detachably mounted to the main body of an electrophotographic image forming apparatus. That is, the electrophotographic image forming apparatus has a main body of the electrophotographic image forming apparatus and a process cartridge detachably mounted to the main body. In the process cartridge 22, a developing device 18 including a developer carrier member 14 and a developer layer thickness control member 15, a photosensitive member 19, a charging roller 20, and a cleaning blade 21 are integrated. The developer layer thickness control member 15 is, for example, a developing blade. The developing device 18 further includes a developer storage portion filled with a developer 16. The developer 16 is supplied to the surface of the developer carrier member 14 by a developer supply roller 17, and a layer of the developer 16 having a predetermined thickness is formed on the surface of the developer carrier member 14 by the developer layer thickness control member 15.

[0324] The developer carrier member 14 is in contact with the photosensitive member 19 and is driven to rotate relative to the photosensitive member 19 at a predetermined circumferential speed ratio. The developer layer thickness control member 15 has at least a conductive portion and has a contact point electrically connected to the developer layer thickness control member. When the processing cartridge is installed in the main body of the electrophotographic image forming apparatus, the contact point is electrically connected to the main body contact point of the main body, and a predetermined voltage can be applied to the developer layer thickness control member. A prescribed bias voltage is applied to the developer carrier member 14, and the electrostatic latent image on the photosensitive member 19 is developed and visualized using the developer 16.

[0325] The developer supply roller 17 is in contact with the developer carrier member 14, intrudes therein by a predetermined intrusion amount, and rotates in the same direction as the rotation direction of the developer carrier member 14. A bias voltage having the same potential as the bias voltage applied to the developer carrier member 14 is applied to the developer supply roller 17.

[0326] One end of the developer layer thickness control member 15 is fixed to the developing device 18, and the other free end is arranged to be in contact with the developer carrier member 14 in a direction opposite to the rotation direction of the developer carrier member 14. The developer layer thickness control member 15 is arranged to be in contact with the developer carrier member 14 to control the amount of the developer on the developer carrier member 14 to form a thin layer and form a uniform developer layer thickness. In addition, a predetermined bias voltage is applied to the developer layer thickness control member 15 to charge the developer 16.

[0327] Figure 4 It is a schematic cross-sectional view showing an example of an electrophotographic image forming apparatus in which the developer carrier member is installed as a developer carrier member of a contact type developing device using a one-component developer. The developing device 18 includes a developer 16 as a one-component developer, a developer carrier member 14, a developer supply roller 17 for supplying the developer to the developer carrier member 14, and a developer layer thickness control member 15 for controlling the thickness of the developer layer on the developer carrier member 14. The developer carrier member 14 is located at an opening extending in the longitudinal direction within the developing device 18 and is arranged to be in contact with the photosensitive member 19. The photosensitive member 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 equipped with black, cyan, magenta, and yellow developers and is capable of color printing.

[0328] The printing operation of the electrophotographic image forming apparatus will be described below. The photosensitive member 19 rotates in the direction of the arrow and is uniformly charged by the charging roller 20 for charging the photosensitive member 19. Next, an electrostatic latent image is formed on the surface of the photosensitive member 19 by the laser light 23 as an exposure means. When the developer 16 is applied from the developer carrier member 14 arranged in contact with the photosensitive member 19, the electrostatic latent image is visualized (developed) as a developer image by the developing device 18. The development is so-called reversal development in which the developer image is formed in the exposure section.

[0329] The developer image formed on the photosensitive member 19 is transferred to the annular belt-like intermediate transfer body 25 by the transfer roller 24 as a transfer member.

[0330] The paper 26 as a recording medium is supplied into the apparatus by the paper feed roller 27 and the secondary transfer roller 28, and is conveyed together with the intermediate transfer body 25 carrying the developer image to the nip between the secondary transfer roller 28 and the driven roller 29, where the developer image is transferred onto the paper 26. The intermediate transfer body 25 is driven by the driven roller 29, the driving roller 30, and the tension roller 31. The developer remaining on the intermediate transfer body 25 is cleaned by the cleaning device 32.

[0331] A voltage is applied from the bias power supply 33 to the developer carrier member 14, the developer layer thickness control member 15, the transfer roller 24, and the secondary transfer roller 28. The paper 26 with the transferred developer image is subjected to a fixing process by the fixing device 34 and discharged to the outside of the apparatus, completing the printing operation. At the same time, the untransferred developer remaining on the photosensitive member 19 is scraped off by the cleaning blade 21 as a cleaning member for cleaning the surface of the photosensitive member. The cleaned photosensitive member 19 repeats the above printing operation.

[0332] Impedance

[0333] In the impedance measurement, while changing the frequency and applying a DC voltage and an AC voltage, the response of the developer carrier member is examined. The AC voltage is applied, and the measurement is performed separately for the non-phase shift response and the response with a π / 2 phase shift with respect to the applied AC voltage. The measurement results are plotted on a complex plane, where the impedance of the non-phase shift response is Z′ (real part), the impedance of the response with a phase shift is Z″ (imaginary part), and the distance from the origin to the graph is calculated as the impedance value.

[0334] When the electrical characteristics of the developer carrier member are simulated by an RC parallel circuit, the real part without a phase shift represents the resistance element, and the imaginary part with a phase shift represents the capacitance element. The meaning of the measurement conditions and measurement values is omitted here, as explained in the previous section (2).

[0335] Hereinafter, the impedance measurement method, measurement apparatus, and measurement conditions will be described.

[0336] Method for measuring impedance

[0337] The impedance of the developer carrier member can be measured by the following methods (1) and (2).

[0338] (1) A method in which a thin film electrode is provided on the surface of the developer carrier member and measurement is performed using two terminals (one terminal is connected to the electrode and the other terminal is connected to the substrate).

[0339] (2) A method in which the developer carrier member is pressed against the metal drum with a constant load and measurement is performed using two terminals (one terminal is connected to the metal drum and the other terminal is connected to the substrate).

[0340] Although the impedance can be measured by any one of the methods, the results obtained by method (2) are affected by the nip width and contact area between the developer carrier member and the metal drum, and therefore it is necessary to perform the measurement using a developer carrier member having the same hardness. Therefore, in the present disclosure, the measurement is performed by method (1). The following describes the measurement method (1), and the following describes more specific conditions.

[0341] In order to eliminate the influence of the contact resistance between the developer carrier member and the measurement electrode when measuring the impedance, it is preferable to deposit a thin film with a low resistance on the surface of the developer carrier member, and measure the impedance using two terminals by using this thin film as the electrode and a conductive substrate as the ground electrode.

[0342] The method for forming the thin film includes a metal vapor deposition method, a sputtering method, coating of a metal paste, and attachment of a metal tape. Among them, from the viewpoint of reducing the contact resistance with the developer carrier member, a method of forming a metal thin film such as platinum or palladium as the electrode by vapor deposition is preferable. In the present disclosure, vacuum platinum vapor deposition is employed.

[0343] When forming a metal thin film on the surface of the developer carrier member, considering the simplicity of the process and the uniformity of the thin film, it is preferable to provide a mechanism capable of gripping the developer carrier member into a vacuum vapor deposition apparatus. In addition, for a developer carrier member having a cylindrical cross-section, it is preferable to use a vacuum vapor deposition apparatus further provided with a rotation mechanism.

[0344] Preferably, measurement is performed by forming a metal thin film electrode with a width of about 10 mm in the length direction of the developer carrier member, and connecting a metal sheet that is wound around the metal thin film electrode without any gap in a direction crossing the length direction to a measurement electrode protruding from a measurement device. In the case of a cylindrical developer carrier member, it is preferable to use a metal sheet that is wound around the circumferential direction of the developer carrier member without any gap. This enables impedance measurement without being affected by the surface shape or dimensional fluctuations of the outer edge (outer diameter of the cylindrical developer carrier member) in a cross section perpendicular to the length direction of the developer carrier member. Aluminum foil, metal tape, etc. can be used as the metal sheet.

[0345] Impedance measurement conditions

[0346] The impedance measurement device can be an impedance analyzer, a network analyzer, a spectrum analyzer, etc., as long as the device can measure the impedance in the frequency range of 1.0×10 -1 to 1.0×10 5 Hz. Among them, it is preferable to use an impedance analyzer to perform measurement from the resistance range of the developer carrier member.

[0347] The impedance measurement conditions are as follows. The impedance measurement device is used to measure the impedance in the frequency range of 1.0×10 -1 to 1.0×10 5 Hz. The measurement environment is a temperature of 23°C and a relative humidity of 50%. To account for measurement variations, it is preferable to measure at least 9 points in total, 3 points along the length of the developer carrier member and 3 points in the rotational direction. The voltage application condition is a DC voltage of 50 V superimposed with an AC voltage of 50 V.

[0348] Surface potential

[0349] In an environment of a temperature of 23°C and a relative humidity of 50%, the degree of overcharging (overcharging of the developer) is evaluated as follows: A corona discharger having a gate portion with a width of 3.0 mm is arranged such that the distance between the gate portion and the outer surface of the developer carrier member is 1.0 mm, and the width direction of the gate portion is aligned with the axial direction of the developer carrier member. An 8 kV voltage is applied to the gate portion, and the corona discharger is moved along the axial direction of the developer carrier member relative to the developer carrier member at a speed of 400 mm / second to charge the outer surface of the developer carrier member, and the potential of the outer surface 0.06 seconds after passing through the gate portion is measured.

[0350] The surface potential of the developer carrier member can be measured, for example, by Figure 8It is measured by the device shown. Both ends of the base 82 of the developer carrier member 81 are held by the chucks 83, and at a distance of 1.0 mm from the surface of the developer carrier member 81, a measuring unit 86 with a corona discharger 84 and a surface electrometer 85 arranged in parallel with a distance of 25 mm between them is placed facing the developer carrier member 81. In the stationary state of the developer carrier member 81, a voltage of 8 kV is applied to the grid portion of the corona discharger 84, the measuring unit 86 is moved along the axial direction of the developer carrier member 81 at a speed of 400 mm / second, and the surface potential 0.06 seconds after passing the corona discharger 84 is measured by the surface electrometer 85.

[0351] Ionization potential

[0352] The ionization potential is measured by the following measurement method. The ionization potential is a numerical value expressed as the energy (eV) required to remove electrons from a substance. The ionization potential is measured using a surface analyzer (product name: AC-5, manufactured by Riken Keiki Co., Ltd.). This device uses a deuterium lamp and measures under the following conditions:

[0353] - Irradiation light quantity: 800 nW

[0354] - Spectrometer: Grating type monochromator

[0355] - Spot size: 2 [mm] × 4 [mm]

[0356] - Energy scan range: 4.0 to 6.2 [eV]

[0357] - Measurement time: 5 [seconds / 1 energy]

[0358] The photoelectrons emitted from the sample surface are detected and processed using the ionization potential calculation software built into the surface analysis device.

[0359] In surface analysis, when the excitation energy of the monochromatic light is scanned from low to high at intervals of 0.05 eV, photon emission starts at a certain energy value [eV], and this energy threshold is regarded as the ionization potential [eV].

[0360] An example of the measurement curve of the work function measured under the above conditions is shown in Figure 11 . In Figure 11 , the horizontal axis represents the excitation energy [eV], and the vertical axis represents the value Y (normalized photon yield) which is the 0.5th power of the number of emitted photoelectrons. Generally, when the excitation energy value exceeds a certain threshold, photoelectrons are suddenly emitted. In other words, the normalized photon yield increases. The value of the excitation energy required when the normalized photon yield starts to increase is defined as the ionization potential.

[0361] Method for measuring elastic modulus

[0362] The elastic modulus is measured using a scanning probe microscope (SPM).

[0363] First, while maintaining the temperature at -110°C, a region including a cross-section in the thickness direction of the resin layer is cut into thin slices from the developer carrier member using a cryostat (product name: EMFC6, manufactured by Leica Microsystems GmbH) with a diamond knife. In addition, a 100-μm square sample with a width of 100 μm in the depth direction is prepared from the thin slices.

[0364] Herein, Figure 12 is a schematic cross-sectional view of the resin layer 12 formed on the conductive substrate 11. In the present disclosure, as Figure 12 shown, a region from the outer surface of the resin layer 12 forming the outer surface of the developer carrier member to a depth of 0.1 μm is defined as the first region 87, and a region from the outer surface to a depth of 1.0 μm to 1.1 μm is defined as the second region 88.

[0365] The elastic modulus is measured in each region that appears in the cross-section of the prepared sample. For the measurement, an SPM device (product name: MFP-3D-Origin, manufactured by Oxford Instruments plc) and a probe (product name: AC160, manufactured by Olympus Corporation) are used. At this time, after first obtaining a 5-μm square image, 10 force curves are measured in each of the first region 87 and the second region 88 other than the roughened formed particles and carbon black, and the arithmetic mean of 8 points excluding the maximum value and the minimum value is obtained, and the elastic modulus can be calculated by Hertz theory. The elastic moduli in the first region 87 and the second region 88 are defined as E1 and E2, respectively.

[0366] The meaning of E1 in the first region is as described above. E2 in the second region is the elastic modulus at a depth of 1.0 to 1.1 μm from the outer surface, and the elastic modulus E2 is preferably 1 to 100 MPa. When E2 in the second region is within the above range, deterioration of the developer in the durability evaluation can be suppressed, and high-quality images can be provided throughout the durability period.

[0367] Verification of IPN structure

[0368] The IPN structure is verified by micro-sampling mass spectrometry. Micro-sampling mass spectrometry uses an ion trap mass spectrometer. The sample is fixed to a filament located at the tip of the probe and directly inserted into the ionization chamber. Then it is rapidly heated from room temperature to a temperature of 1000°C at a constant heating rate. The sample decomposed and evaporated by heating is ionized by irradiation with an electron beam and detected by the mass spectrometer.

[0369] At this time, under the condition of a constant heating rate, a thermochromatogram similar to the TG-MS (thermogravimetric analysis - mass spectrometry) method is obtained, which has a mass spectrum called the total ion chromatogram (TIC). In addition, since a thermochromatogram of fragments of a predetermined mass can be obtained, the peak temperature of the thermochromatogram corresponding to the decomposition temperature of the desired molecular structure can be obtained. The peak temperature of the thermochromatogram is related to the crosslinked structure in the resin structure, and as the crosslinking becomes denser, the peak temperature shifts more towards the high-temperature side. In other words, compared with a single crosslinked acrylic resin, in the part where the crosslinked polyurethane resin and the crosslinked acrylic resin form an IPN structure, the peak temperature of the thermochromatogram is higher.

[0370] From a first sample obtained from a first region that is a region from the outer surface of the resin layer to a depth of 0.1 μm, the peak temperature A1 of the thermochromatogram derived from the crosslinked acrylic resin is obtained. In addition, the peak temperature A2 of the thermochromatogram derived from the crosslinked acrylic resin measured from a second sample obtained by decomposing the crosslinked polyurethane resin contained in the first sample is obtained. When forming an IPN structure, in terms of the peak temperature of the thermochromatogram, A1 is higher than A2.

[0371] A2 is a value obtained by performing micro-sampling mass spectrometry on a second sample obtained by decomposing the crosslinked polyurethane by the pyridine decomposition method described later.

[0372] A1 can be, for example, 390 - 398 °C and 393 - 397 °C. A2 can be, for example, 385 - 395 °C and 390 - 394 °C.

[0373] Pyridine decomposition method

[0374] The pyridine decomposition method is a method for selectively decomposing urethane bonds. By performing the pyridine decomposition method on a specimen having an IPN structure of a crosslinked acrylic resin and a crosslinked polyurethane resin, the crosslinked acrylic resin can be obtained after removing the structure derived from the crosslinked polyurethane. The presence or absence of the IPN structure can be confirmed by capturing the change in the peak temperature of the thermochromatogram of this crosslinked acrylic resin. Specifically, the pyridine decomposition method is carried out as follows.

[0375] Using a slicer, a sample with a thickness of 0.1 μm was cut from the outer surface of the resin layer of the developer carrier member, and 500 mg of the sample was collected. A total of 0.5 mL of a mixture of pyridine (manufactured by Wako Pure Chemical Industries, Ltd.) and water in a ratio of 3:1 was added to the obtained sample, and the sample was decomposed by heating at 130 °C for 15 hours in a sealed container made of fluororesin (Teflon (registered trademark)) with a stainless-steel jacket. Pyridine was removed from the obtained decomposition product under reduced pressure. The above-mentioned micro-sampling mass spectrometry was performed using the sample obtained in this way to obtain the value of A2.

[0376] Structure analysis of crosslinked acrylic resin

[0377] The presence of silicone groups and / or fluorine groups in the crosslinked acrylic resin molecules can be analyzed by known means such as pyrolysis GC / MS (gas chromatography-mass spectrometer), FT-IR (Fourier transform infrared spectrophotometer), and NMR (nuclear magnetic resonance apparatus).

[0378] The structure derived from the crosslinked polyurethane was removed by the pyridine method, and the obtained crosslinked acrylic resin was confirmed using FT-IR (product name: FT / IR-4700, manufactured by JASCO Corporation, FT-IR).

[0379] Examples

[0380] The present disclosure will be described in more detail below with reference to the examples, but these are not intended to limit the present disclosure in any way.

[0381] 1. Preparation and production of raw materials for resin layer formation

[0382] 1-1. Preparation and production examples of raw material polyols

[0383] The following are synthesis examples for obtaining a polyurethane resin layer.

[0384] Measurement of the number-average molecular weight of the raw material polyol

[0385] The apparatus and conditions for measuring the number-average molecular weight (Mn) in this production example are as follows.

[0386] Measurement apparatus: HLC-8120GPC (manufactured by Tosoh Corporation)

[0387] Column: TSKgel Super HZMM (manufactured by Tosoh Corporation) × 2

[0388] Solvent: Tetrahydrofuran (THF) (20 mmol / l, with triethylamine added)

[0389] Temperature: 40 °C

[0390] Flow rate of THF: 0.6 ml / min

[0391] The measurement sample is a 0.1 mass% THF solution. In addition, an RI (refractive index) detector is used as the detector for measurement.

[0392] TSK standard polystyrenes A-1000, A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40, F-80, and F-128 (manufactured by Tosoh Corporation) are used as standard samples for creating a calibration curve to create a calibration curve. Based on this calibration curve, the number-average molecular weight is calculated from the retention time of the obtained measurement sample.

[0393] Raw material polyol

[0394] Prepare raw material polyols A-1 to A-5.

[0395] Details are listed in Table 1.

[0396] [Table 1]

[0397] No. Raw material polyol A-1 Duranol T5652 Mn = 2000 (manufactured by Asahi Kasei Chemicals Corp.) A-2 Duranol G3452 Mn = 2000 (manufactured by Asahi Kasei Chemicals Corp.) A-3 ETERNACOLL UH-200 Mn = 2000 (manufactured by Ube Industries, Ltd.) A-4 Nippolan 982 Mn = 2000 (manufactured by Ube Industries, Ltd.) A-5 ETERNACOLL UM(1:3) Mn = 900 (manufactured by Ube Industries, Ltd.)

[0398] 1-2. Preparation of raw material isocyanates B-1 to B-3

[0399] Prepare raw material isocyanates B-1 to B-3.

[0400] Details are listed in Table 2.

[0401] [Table 2]

[0402]

[0403] 1-3. Production examples of hydroxyl-terminated urethane prepolymers C-1 to C-3

[0404] Synthesis of hydroxyl-terminated urethane prepolymer C-1

[0405] The materials listed in Table 3 below are reacted under heating and stirring at 90 °C for 3 hours in a nitrogen atmosphere. Then, 2-butanone (MEK) is added to the obtained reaction product to obtain a solution having a solid content of 50 mass parts, thereby producing a hydroxyl-terminated urethane prepolymer C-1.

[0406] Synthesis of hydroxyl-terminated urethane prepolymers C-2 and C-3

[0407] Using the raw materials listed in Table 3 below, hydroxyl-terminated urethane prepolymers C-2 and C-3 were produced in the same manner as the synthesis of hydroxyl-terminated urethane prepolymer C-1.

[0408] Using 1 H-NMR and 13 C-NMR to identify the chemical structures of these hydroxyl-terminated urethane prepolymers C-1 to C-3. In Table 3, m, n, o, p, q, r, and s in structural formulas (1), (2), (3), and (4) are average addition molar numbers.

[0409] [Table 3]

[0410]

[0411] For hydroxyl-terminated urethane prepolymers C-1 and C-2 containing the structure shown in structural formula (1) in the molecule, R13 in structural formula (1) is the same as R12.

[0412] In the table, the notation "x, y = A" such as m and n = 6.9 indicates that the average addition molar numbers of x and y are A. This also applies to the following tables.

[0413] 1-4. Production Examples of Isocyanate-Terminated Prepolymers D-1 to D-3

[0414] Synthesis of isocyanate-terminated prepolymer D-1

[0415] The materials listed in Table 4 below were reacted under heating and stirring at 90 °C for 3 hours in a nitrogen atmosphere. Then, 2-butanone (MEK) was added to the resulting reaction product to obtain a solution with a solid content of 50 parts by mass, thereby producing isocyanate-terminated urethane prepolymer D-1.

[0416] Synthesis of isocyanate-terminated prepolymers D-2 and D-3

[0417] Isocyanate-terminated urethane prepolymers D-2 and D-3 were produced in the same manner as the synthesis of isocyanate-terminated prepolymer D-1 by using the types and amounts of raw materials listed in Table 4 below.

[0418] Using 1 H-NMR and 13 C-NMR to identify the chemical structures of these isocyanate-terminated prepolymers D-1 to D-3. In Table 7, m, n, o, p, q, r, and s in structural formulas (1), (2), (3), and (4) are average addition molar numbers.

[0419] [Table 4]

[0420]

[0421] For the isocyanate - terminated prepolymer D - 2 containing the structure shown in structural formula (1) in its molecule, R13 in structural formula (1) is the same as at least one selected from the group consisting of R11 and R12.

[0422] 2. Preparation of resin layer, additive raw materials

[0423] 2 - 1. Preparation of polyoxyethylene - polyoxypropylene alkyl ether

[0424] Preparation of polyoxyethylene polyoxypropylene alkyl ether

[0425] Details of polyoxyethylene - polyoxypropylene alkyl ethers E - 1 to E - 3 are listed in Table 5.

[0426] [Table 5]

[0427]

[0428] Surface modifier

[0429] Materials used as surface modifiers are listed in Table 6.

[0430] [Table 6]

[0431]

[0432] Impregnation treatment liquid

[0433] Dissolve and mix the materials shown in Table 7 below as the materials for the impregnation treatment liquid for impregnation treatment.

[0434] [Table 7]

[0435]

[0436] 3. Production example of developer carrier member

[0437] In this example, a developer carrier member in which a resin layer is coated on an elastic roller having an elastic layer on the outer surface of a substrate is described, but the present disclosure is not limited to this configuration.

[0438] 3 - 1. Preparation of substrate

[0439] A substrate is produced by coating a primer (product name: DY35 - 051, manufactured by Dow Toray Co., Ltd.) on the outer peripheral surface of a 6 - mm - diameter mandrel made of stainless steel (SUS304) and baking it (130 °C, 5 minutes).

[0440] 3 - 2. Preparation of elastic layer

[0441] Place the substrate in a mold, and pour the addition-curing silicone rubber composition containing the materials shown in Table 8 into the cavity formed in the mold.

[0442] [Table 8]

[0443]

[0444] Then heat the mold at 150 °C for 15 minutes to vulcanize and cure the silicone rubber. After demolding, heat the silicone rubber at 180 °C for 1 hour to complete the curing reaction, and obtain an elastic roller having an elastic layer with a diameter of 11.5 mm on the outer periphery of the substrate.

[0445] 3-3. Preparation of the coating liquid for forming the resin layer

[0446] Add the materials of the types and amounts shown in Table 9 below as the materials for the coating liquid for forming the resin layer to a reaction vessel and stir. Then, add 2-butanone (MEK) so that the total solid content ratio is 30% by mass, and mix each component with a sand mill.

[0447] Next, add 2-butanone (MEK) to adjust the viscosity of the liquid to the range of 6 to 10 mPa·s, thereby preparing the coating for forming the resin layer.

[0448] [Table 9]

[0449]

[0450] 3-4. Preparation of the crosslinked polyurethane resin in the resin layer

[0451] Orient the elastic roller with its longitudinal direction along the vertical direction, hold its upper end, and immerse (dip) the elastic roller in the coating liquid for forming the resin layer to coat the surface of the elastic roller with the coating liquid. Air-dry the obtained coating at room temperature for 30 minutes, and then dry it in a hot air circulation dryer set at 160 °C for 1 hour. In this way, an elastic roller is obtained in which a crosslinked polyurethane resin having a thickness of 12 μm is formed on the elastic layer.

[0452] 3-5. Impregnation treatment

[0453] Then, perform the impregnation and curing treatment of the acrylic monomer capable of forming the crosslinked acrylic resin by the following method. Use the impregnation treatment liquid shown in Table 7 and Table 10 for the impregnation treatment. Immerse the elastic roller having the crosslinked polyurethane resin formed thereon in the above impregnation treatment liquid for 2 seconds to impregnate the acrylic monomer component. Then, immediately dry it at 90 °C for 1 hour to volatilize the solvent. After drying, rotate the elastic roller so that the cumulative light amount is 15,000 mJ / cm 2The acrylic monomer was cured by irradiating with ultraviolet light in such a manner to obtain the developer carrier member 1 having an IPN structure formed therein.

[0454] A high-pressure mercury lamp (product name: Handy Type UV Curing Device, manufactured by Marionetwork Co., Ltd.) was used as the ultraviolet irradiating device.

[0455] The physical properties of the obtained developer carrier member 1 are listed in Tables 10-1 and 10-2.

[0456] Manufacture of developer carrier members 2 to 11

[0457] Except that the materials and amounts were changed to those listed in Table 10-1, the developer carrier members 2 to 11 were manufactured in the same manner as the developer carrier member 1. The physical properties of the obtained developer carrier members 2 to 11 are listed in Tables 10-1 and 10-2.

[0458] When the presence or absence of the step in the impregnation liquid column is described as "present", the above-mentioned impregnation treatment is carried out. On the contrary, when it is described as "absent", the impregnation treatment is not carried out.

[0459] [Table 10-1]

[0460]

[0461] [Table 10-2]

[0462]

[0463] In the table, for example, notations such as "9.12E+06" represent "9.12×10 6 ". A1 is the above-mentioned peak temperature A1 (°C), and A2 is the above-mentioned peak temperature A2 (°C).

[0464] An IPN structure composed of a crosslinked polyurethane resin and a crosslinked acrylic resin was confirmed in the developer carrier members 1 to 5, but no IPN structure was confirmed in the other developer carrier members.

[0465] Production of developer carrier member 12

[0466] The materials of the types and amounts shown in Table 11 below were added to the reaction vessel and stirred. Then, 2-butanone (MEK) was added in such a manner that the total solid content ratio was 30% by mass, and the components were mixed with a sand mill. Then, 2-butanone (MEK) was added to adjust the viscosity of the liquid to be in the range of 6 to 10 mPa·s, thereby preparing a coating for forming a resin layer.

[0467] The elastic roller obtained in the production of the developer carrier member 1 is oriented such that its longitudinal direction is oriented along the vertical direction. Hold its upper end and immerse (dip) the elastic roller into the coating liquid for resin layer formation to coat the surface of the elastic roller with the coating liquid. Air-dry the obtained coating at room temperature for 30 minutes, and then dry it in a hot air circulation dryer set at 160 °C for 1 hour. Thus, a resin layer is formed on the elastic roller having a resin layer with a thickness of 12 μm formed on the elastic layer, and the developer carrier member 12 is obtained.

[0468] The physical properties of the developer carrier member 12 are shown in Tables 10-1 and 10-2.

[0469] [Table 11]

[0470]

[0471] Production of developer carrier member 13

[0472] Except that the additive E-1 is changed to 14 parts by mass of a silane coupling agent (product name: A-187, manufactured by Momentive Corp.) and the dipping treatment is not performed, the developer carrier member 13 is produced in the same manner as the production of the developer carrier member 1. The physical properties of the developer carrier member 13 are shown in Tables 10-1 and 10-2.

[0473] Production of developer carrier member 14

[0474] The mold used in the production of the above elastic roller is pre-coated with a fluorine-based release agent (product name: Frelease 310, manufactured by Neos Co., Ltd.), and a liquid of a foaming material in which the following materials (A) to (F) are blended and dispersed is injected into the mold.

[0475] (A): Polyol A (polyethylene propylene ether triol with a number average molecular weight of 3100, trade name: Actcol EP-550N, manufactured by Mitsui Chemicals SKC Polyurethanes Inc.): 100.0 parts by mass.

[0476] (B): Polyisocyanate mixture (NCO% = 45, containing 20% MDI, product name: Cosmonate TM-20, manufactured by Mitsui Chemicals SKC Polyurethanes Inc.): 23.9 parts by mass.

[0477] (C): Organosilicon foam stabilizer (product name: SRX274C, manufactured by Toray Industries, Inc.): 1.0 part by mass.

[0478] (D): Tertiary amine catalyst A (a mixture of bis(2-dimethylaminoethyl) ether and dipropylene glycol, trade name: TOYOCAT-ET, manufactured by Tosoh Corporation): 0.3 parts by mass.

[0479] (E): Amine catalyst B (trade name: TOYOCAT-L33, manufactured by Tosoh Corporation): 0.2 parts by mass.

[0480] (F): Blowing agent (water): 1.4 parts by mass.

[0481] After injecting the foaming material, it is heated at 75 °C for 7 minutes and then demolded.

[0482] By the above method, an elastic roller having an elastic layer containing a foamed polyurethane resin is produced.

[0483] The elastic roller is coated with a PTFE coating (polytetrafluoroethylene). Thus, a developer carrier member 14 in which a Teflon resin is coated on the surface of the porous body is obtained. The physical properties of the developer carrier member 14 are shown in Tables 10-1 and 10-2.

[0484] 4. Production example of developer

[0485] Production of treated magnetic body

[0486] A caustic soda solution in an amount of 1.00 to 1.10 equivalents relative to iron element, P2O5 in an amount of 0.15% by mass in terms of phosphorus element relative to iron element, and SiO2 in an amount of 0.50% by mass in terms of silicon element relative to iron element are mixed in an aqueous solution of ferrous sulfate to prepare an aqueous solution containing ferrous hydroxide. The pH of the aqueous solution is set to 8.0, and an oxidation reaction is carried out at 85 °C while blowing air into the solution to prepare a slurry containing seeds.

[0487] Next, an aqueous solution of ferrous sulfate is added to the slurry in an amount of 0.90 to 1.20 equivalents relative to the initial amount of the alkali (sodium component of caustic soda), and the pH of the slurry is maintained at 7.6. An oxidation reaction is carried out while blowing air into the slurry to obtain a slurry containing magnetic iron oxide. After filtration and washing, the aqueous slurry is temporarily removed. At this time, a small amount of the aqueous sample is taken and the water content is measured. Then, the aqueous sample is put into another aqueous medium without drying, redispersed in a needle mill while stirring and circulating the slurry, and the pH of the redispersed liquid is adjusted to about 4.8. Then, while stirring, 1.6 parts of n-hexyltrimethoxysilane are added to 100 parts of magnetic iron oxide (the amount of magnetic iron oxide is calculated as the value obtained by subtracting the water content from the aqueous sample), and hydrolysis is carried out. After that, sufficient stirring is carried out, the pH of the dispersion is adjusted to 8.6, and surface treatment is carried out. The resulting hydrophobic magnetic material is filtered with a plate filter press, washed with a large amount of water, then dried at 100 °C for 15 minutes and at 90 °C for 30 minutes, and the obtained particles are pulverized to obtain a treated magnetic material with a number average particle size of 0.21 μm.

[0488] Production of non-crystalline polyester

[0489] The raw material monomers are prepared as follows and placed in a reaction vessel equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer, and a thermocouple. 1.5 parts of dibutyltin are added as a catalyst relative to 100 parts of the monomer. Then, the temperature is rapidly raised to 180 °C at normal pressure in a nitrogen atmosphere, and water is distilled off while heating from 180 °C to 210 °C at a rate of 10 °C / h to carry out polycondensation.

[0490] After reaching 210 °C, the pressure inside the reaction vessel is reduced to below 5 kPa, and polycondensation is carried out under the conditions of 210 °C and below 5 kPa to obtain an amorphous polyester. The obtained amorphous polyester has a number average molecular weight of 7800 and a glass transition temperature of 73 °C.

[0491] - 90.0 parts of bisphenol A (2-mole adduct of propylene oxide)

[0492] - 74.0 parts of terephthalic acid

[0493] - 4.0 parts of trimellitic anhydride

[0494] Production example of developer particles

[0495] A total of 450 parts of 0.1 mol / L - Na3PO4 aqueous solution are added to 720 parts of ion-exchanged water and heated to 60 °C, and then 67.7 parts of 1.0 mol / L - CaCl2 aqueous solution are added to obtain an aqueous medium containing a dispersion stabilizer.

[0496] - Styrene 75.0 parts

[0497] - n-Butyl acrylate 25.0 parts

[0498] - Amorphous polyester

[0499] - Divinylbenzene 0.6 part

[0500] - The above-mentioned treated magnetic material 65.0 parts

[0501] The above-mentioned preparation was dispersed and mixed using a grinder (Mitsui Miike Chemical Engineering Co., Ltd.) to obtain a monomer composition. The monomer composition was heated to 63°C, 5.0 parts of an ester wax (melting point 70°C) was added, and the mixture was mixed and dissolved. Then, 6.0 parts of tert-butyl peroxyneodecanoate was dissolved as a polymerization initiator.

[0502] The monomer composition was added to an aqueous medium and granulated by stirring at 12,000 rpm for 10 minutes in a N2 atmosphere at 60°C using a TK homomixer (Tokushu Kika Kogyo Co., Ltd.). Then, the reaction was carried out at 70°C for 4 hours while stirring with a paddle impeller. After the reaction was completed, it was confirmed that colored particles were dispersed in the aqueous medium thus obtained, and calcium phosphate was attached to the surface of the colored particles as an inorganic dispersant.

[0503] Then, hydrochloric acid was added to the aqueous medium to dissolve calcium phosphate, and the mixture was washed, filtered, and dried to obtain developer particles.

[0504] Silica fine particles

[0505] The surface of the raw material of the silica fine particles was treated with the treating agent shown in Table 12 to obtain each of the silica fine particles 1 to 3. Details of the silica fine particles 1 to 3 are shown in Table 12.

[0506] The raw material of the silica fine particles was silica fine particles having a BET specific surface area of 120 m 2 / g (number average particle diameter of primary particles: 12 nm).

[0507] [Table 12]

[0508]

[0509] Production of developer (toner) 1

[0510] Using a Henschel mixer (Mitsui Miike Chemical Engineering Co., Ltd.), 100 parts by mass of developer particles in total were mixed with the fine silica particles 1 listed in Table 12 obtained in the parts by mass listed in Table 13, thereby preparing Developer 1.

[0511] The physical properties of Developer 1 are shown in Table 13.

[0512] [Table 13]

[0513]

[0514] The parts represent parts by mass.

[0515] Production of developers (toners) 2 to 7

[0516] Except for changing the parts of the hydrophobic fine silica particles as shown in Table 13, the hydrophobic fine silica particles listed in Table 12 used in the production of Developer 1 were used to produce Developers 2 to 7 in the same manner as Developer 1. The physical properties of Developers 2 to 7 are shown in Table 13.

[0517] Example 1

[0518] Impedance measurement

[0519] The impedance measurement was carried out as follows.

[0520] First, as a pretreatment, a measurement electrode was prepared by vacuum vapor deposition of platinum on a rotating developer carrier member. For the vapor deposition, a vacuum vapor deposition apparatus having a mechanism that holds the base of the carrier member for vapor deposition and rotates the base circumferentially was used, and the deposition was carried out by controlling the carrier rotation speed, deposition distance, and deposition time so that the film thickness was 100 nm or more. At this time, a masking tape was used to make an electrode with a width of 1.5 cm and uniform circumferentially. By forming an electrode with a film thickness of 100 nm or more, the contribution of the contact area between the measurement electrode and the developer carrier member due to the surface roughness of the developer carrier member can be reduced as much as possible.

[0521] Next, an aluminum sheet was wound around the electrode without any gap, and the aluminum sheet was connected to the measurement electrodes of an impedance measurement device (product names Solartron 1260 and Solartron 1296, manufactured by Solartron Corp.) and a high-voltage system (product names 6792 and HVA-500, manufactured by Toyo Corporation).

[0522] Figure 5is a schematic diagram showing a state in which a measurement electrode is formed on a developer carrier member. In Figure 5 , reference numeral 51 is a conductive substrate, reference numeral 52 is a resin layer, reference numeral 53 is a platinum vapor deposition layer, and reference numeral 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.

[0523] Figure 6 is a cross-sectional view of a state in which a measurement electrode is formed on a developer carrier member. Reference numeral 61 is a conductive substrate, reference numeral 62 is an elastic layer, reference numeral 63 is a resin layer, reference numeral 64 is a platinum vapor deposition layer, and reference numeral 65 is an aluminum sheet. As Figure 6 shown, importantly, a state is achieved in which the resin layer is sandwiched between the conductive substrate and the measurement electrode.

[0524] Then, the aluminum sheet is connected to an impedance measurement device (Solartron 1260 and Solartron 1296, manufactured by Solartron Co.) and a measurement electrode (product names: 6792 and HVA - 500, Toyo Corporation) on a high - voltage system. Figure 7 is a schematic diagram of this measurement system. Impedance measurement is performed by using the conductive substrate and the aluminum sheet as the two electrodes for measurement.

[0525] The impedance is measured in an environment of temperature 23°C and relative humidity 50%, with a DC voltage of 50V and an AC voltage of 50V applied, and the absolute value of the impedance is obtained at a frequency from 1.0×10 -1 to 1.0×10 5 Hz.

[0526] Measurement of surface potential

[0527] The surface potential of the developer carrier member is measured using a charge amount measurement device (product name: DRA - 2000L, manufactured by QEA, Inc.). Specifically, in an environment of temperature 23°C and relative humidity 50%, the gate part of the corona discharger of the charge amount measurement device is arranged such that the gap between the gate part and the outer surface of the developer carrier member is 1.0 mm. The gate part of the corona discharger of the above - mentioned device has a width of 3.0 mm.

[0528] Next, a voltage of 8 kV is applied to the corona discharger, and the corona discharger is moved relative to the developer carrier member along the axial direction of the developer carrier member at a speed of 400 mm / second to charge the surface of the conductive member, and the potential of the outer surface is measured 0.06 seconds after passing through the gate part. The maximum value of all the measured values measured at 8 points at 45° intervals in the length direction around the electrophotographic roller is used.

[0529] Calculation of various physical properties such as circular equivalent diameter and wall-to-wall distance of carbon black dispersed in the resin layer

[0530] The dispersion particle diameter of the carbon black dispersed in the resin layer and the distance between the wall surfaces are measured by the following method.

[0531] First, a thin slice (with a thickness of 0.5 to 1.0 mm) is cut with a razor blade so that a cross-section perpendicular to the longitudinal direction of the developer carrier member can be observed. When the adhesion between the substrate and the resin layer is high and it is difficult to cut with a razor blade, the substrate is cut with a hacksaw or the like, and then cross-section processing is performed using a FIB (focused ion beam) device.

[0532] Then, platinum is vapor-deposited on the section, and a cross-sectional image of the resin layer is taken at a magnification of 15,000 times using a scanning electron microscope (SEM) (product name: JSM-7800F, manufactured by JEOL Ltd.).

[0533] In addition, in order to quantify the cross-sectional image obtained by SEM observation, the cross-sectional image is converted into an 8-bit grayscale using image processing software (product name: Luzex AP, manufactured by Nireco Corporation) to obtain a monochromatic image with 256 gray levels. Then, the black and white of the image are inverted so that the carbon black in the cross-sectional image is white, and then a binarization threshold is set for the brightness distribution of the image based on the algorithm of Otsu's discriminant analysis method, thereby obtaining a binarized image in which the carbon black is white and the binder resin part is black.

[0534] Then, the obtained binary image is applied to image processing software (product name: Luzex AP, manufactured by Nireco Corporation) to calculate the circular equivalent diameter of the whitened carbon black part and the distance between adjacent wall surfaces. The image area used to calculate the circular equivalent diameter and the distance between adjacent wall surfaces is set to an area 0.075 μm inside the actual image size (the part with text describing the SEM measurement conditions, etc., 0.075 μm inside the part starting from the actual image) to eliminate the uncertainty of the calculated values of the carbon black divided at the upper, lower, left, and right ends of the image, and calculate the circular equivalent diameter of the entire carbon black in the specified image and the distance between adjacent wall surfaces.

[0535] For the distributions of the obtained circular equivalent diameter and the distance between adjacent wall surfaces, the arithmetic mean and the standard deviation are calculated. Regarding the number of images used for image analysis, although results can be obtained without any complexity even from one image, at least three or more images are used to eliminate the influence of the position difference in the longitudinal direction of the carbon black dispersed in the resin layer of the developer carrier member.

[0536] 5. Image evaluation

[0537] The following describes the image evaluation method.

[0538] A modified machine of a commercially available laser printer LBP-7600C (manufactured by Canon Inc.) is used as the electrophotographic image forming apparatus. The structure of the modified machine is as Figure 10 shown. Except for the power supplies 14C and 15C, the printer is modified by connecting to an external high-voltage power supply 20C, so that a freely selectable potential difference can be set between the developer layer thickness control member and the developer carrier member, and for A4 paper, the number of sheets output per unit time is set to 50 sheets / minute for evaluation during high-speed processing.

[0539] The processing cartridge used is a commercially available developer cartridge 318 (black) (manufactured by Canon Inc.), and the developer and the developer carrier member are replaced with the combinations shown in Table 14-1. At this time, the filling amount of the developer is adjusted to 100 g. The product developer is removed from each of the yellow, cyan, and magenta stations, and the evaluation is performed by inserting yellow cartridges, cyan cartridges, and magenta cartridges in which the developer residue detection mechanism is ineffective.

[0540] 5-1. Fogging evaluation

[0541] The prepared processing cartridge is installed in the main body of the electrophotographic image forming apparatus, and it is left standing for 24 hours in an environment where the temperature is 30°C and the relative humidity is 80%. After that, using the external high-voltage power supply, the potential difference between the developer layer thickness control member and the developer carrier member is set to -300 V, and in the same environment, an image of the 4-point-sized letter "E" is continuously output onto A4 evaluation paper (GF-C081, manufactured by Canon Inc.) at a printing percentage of 2% of the area of A4-sized paper. For every 1000 sheets of solid white images output, this operation is repeated until 20,000 sheets, and the fogging value is measured using the following method.

[0542] A total of 10 solid white images are continuously printed at one time, and the fogging values of the first and tenth images are used.

[0543] 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 is printed are measured, and the increase in reflection density (R2 - R1) is taken as the "fogging value" of the developer carrier member. The reflection density is measured over the entire image printing area of the recording material, and the maximum value is used.

[0544] The smaller the fogging value, the better. Generally, on the transfer paper where the developer is not transferred to form a solid white image. When the charge amount of the developer is insufficient, even when forming a solid white image, the developer moves to the photosensitive member and is further transferred to the transfer paper, thereby increasing the fogging value. In the fogging evaluation at the time of the output number being 0 (initial state) and after outputting 20,000 sheets, the fogging values of the first sheet and the tenth sheet are respectively evaluated. The evaluation results are shown in Table 14-1.

[0545] Since fogging is likely to occur in a high-temperature and high-humidity environment of 30°C and a relative humidity of 80%, the evaluation is carried out in an environment of 30°C and a relative humidity of 80%.

[0546] Evaluation of roughness

[0547] The dot reproducibility evaluation is rough. The prepared process cartridge is installed on the main body of the electrophotographic image forming apparatus, and it is left standing for 24 hours in an environment of 15°C and a relative humidity of 10%. After that, using an external high-voltage power supply, the potential difference between the developer layer thickness control member and the developer carrier member is set to -300V, and in the same environment, an image of the 4-point-sized letter "E" is continuously output to A4 evaluation paper (GF-C081, manufactured by Canon Inc.) at a printing percentage of 2% of the area of A4-sized paper. For every 1000 sheets of output of a solid white image, this operation is repeated until 20,000 sheets, a halftone (30H) image is formed, and the dot reproducibility of this image is evaluated. The 30H image is a halftone image in which 256 gradations are represented in hexadecimal, where 00H is a solid white (non-image) and FFH is a solid image (full-surface image).

[0548] For the image, the area of 1000 points is measured using a VHX-500 digital microscope (wide-range zoom lens VH-Z100, manufactured by Keyence Corporation).

[0549] The arithmetic mean value (S) of the dot areas and the standard deviation (σ) of the dot areas are calculated, and the dot reproducibility index is calculated using the following formula.

[0550] The halftone image is evaluated using the dot reproducibility index (I). The smaller the value of the dot reproducibility index (I), the better the dot reproducibility.

[0551] Dot reproducibility index (I) = σ / S × 100

[0552] Since roughness tends to occur more easily in a low-temperature and low-humidity environment of 15°C and a relative humidity of 10%, the evaluation is carried out in an environment of 15°C and a relative humidity of 10%.

[0553] The evaluation results of Example 1 are shown in Table 14-1.

[0554] Examples 2 to 13

[0555] In Examples 2 to 13, except that the developer carrier member and the developer were changed to those shown in Table 14-1, each measurement and each evaluation were carried out in the same manner as in Example 1.

[0556] The evaluation results are shown in Table 14-1 and Table 14-2.

[0557] [Table 14-1]

[0558]

[0559] [Table 14-2]

[0560]

[0561] Comparative Examples 1 - 6

[0562] In Comparative Examples 1 to 6, except that the developer carrier member and the developer were changed to those shown in Table 14-2, each measurement and each evaluation were carried out in the same manner as in Example 1. The evaluation results are shown in Table 14-2.

[0563] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation so as to cover all such modifications as well as equivalent structures and functions.

Claims

1. A processing cartridge, comprising: a developer, a developer carrier member, a developer layer thickness control member that contacts the developer carrier member and controls the layer thickness of the developer carried on the developer carrier member, a contact that is electrically connected to the developer layer thickness control member, and a developer storage member that stores the developer, wherein the processing cartridge is detachably mounted to a main body of an electrophotographic image forming apparatus, at least a part of the developer layer thickness control member is conductive, when the processing cartridge is mounted to the main body of the electrophotographic image forming apparatus, the contact is electrically connected to a main body contact of the main body of the electrophotographic image forming apparatus and can apply a predetermined voltage to the developer layer thickness control member, the developer carrier member includes a substrate including a conductive outer surface, and a resin layer present on the outer surface side of the substrate, When the metal film is directly disposed on the outer surface of the developer carrier member, and while applying a DC voltage of 50 V between the outer surface of the substrate and the metal film in an environment with a temperature of 23 °C and a relative humidity of 50%, an AC voltage with an amplitude of 50 V is applied at a frequency varying between 1.0×10 -1 and 1.0×10 5 Hz, the impedance at a frequency of 1.0×10 0 to 1.0×10 1 Hz is 1.00×10 6 Ω or more. when the ionization potential of the developer is represented by I(T) and the ionization potential of the outer surface of the developer carrier member is represented by I(R), I(T) and I(R) satisfy the following formula (X): |I(T) - I(R)| ≤ 0.3 eV......(X) and in an environment where the temperature is 23°C and the relative humidity is 50%, a corona discharger having a gate portion with a width of 3.0 mm is arranged such that the distance between the gate portion and the outer surface of the developer carrier member is 1.0 mm, and the width direction of the gate portion is aligned with the axial direction of the developer carrier member. An 8 kV voltage is applied to the gate portion, and the corona discharger is moved relative to the developer carrier member along the axial direction of the developer carrier member at a speed of 400 mm / second to charge the outer surface of the developer carrier member, and when measuring the potential of the outer surface 0.06 seconds after passing through the gate portion, the maximum value of the potential is less than 20.0 V.

2. The processing cartridge according to claim 1, wherein the ionization potential I(T) of the developer is 4.0 to 5.6 eV.

3. The processing cartridge according to claim 1 or 2, wherein, The elastic modulus E1 in the region from the outer surface of the developer carrier member to a depth of 0.1 μm measured in a cross-section in the thickness direction of the resin layer is 200 MPa or more.

4. The processing cartridge according to claim 3, wherein, The elastic modulus E2 in the region at a depth of 1.0 μm to 1.1 μm from the outer surface of the developer carrier member measured in a cross-section in the thickness direction of the resin layer is 1 to 100 MPa.

5. The processing cartridge according to claim 1 or 2, wherein, The resin layer includes a polyurethane having a polycarbonate structure.

6. The processing cartridge according to claim 5, wherein the polyurethane satisfies at least two of the following (A), (B), and (C): (A) The polyurethane has a structure represented by the following structural formula (1) in the molecule; (B) The polyurethane has at least one structure selected from the group consisting of the structure represented by the following structural formula (2) and the structure represented by the following structural formula (3) in the molecule; and (C) The polyurethane has a structure represented by the following structural formula (4) in the molecule; Structural formula (1) Structural formula (2) Structural formula (3) Structural formula (4) In the structural formula (1), R11, R12, and R13 represent divalent hydrocarbon groups having 3 to 9 carbon atoms; however, R11 and R12 are different from each other, and R13 is the same as at least one selected from the group consisting of R11 and R12; m and n are average addition molar numbers, and each independently represents a number of 1.0 or more; In the structural formula (2), o and p are average addition molar numbers, and each independently represents a number of 1.0 or more; In the structural formula (3), R31 and R32 each independently represent divalent hydrocarbon groups having 3 to 8 carbon atoms; q and r each independently represent average addition molar numbers, and each independently represents a number of 1.0 or more; In the structural formula (4), R41 represents a divalent hydrocarbon group having 6 to 9 carbon atoms; s represents an average addition molar number, and represents a number of 1.0 or more.

7. The processing cartridge according to claim 5, wherein the polyurethane is a crosslinked polyurethane resin, the resin layer further contains a crosslinked acrylic resin, and the crosslinked polyurethane resin and the crosslinked acrylic resin form an interpenetrating polymer network IPN in the resin layer.

8. The processing cartridge according to claim 1 or 2, wherein the resin layer contains carbon black, when the arithmetic average of the circular equivalent diameters of the carbon black in the resin layer is represented by Rc, Rc is 60.0 nm or less, and when the standard deviation of the circular equivalent diameters is represented by σc, σc / Rc is 0.000 to 0.

650.

9. The processing cartridge according to claim 1 or 2, wherein the resin layer contains carbon black, when the arithmetic average of the distances between the walls of the carbon black in the resin layer is represented by d, d is 80.0 to 150.0 nm, and when the standard deviation of the distances between the walls is represented by σd, σd / d is 0.000 to 0.

600.

10. The processing cartridge according to claim 1 or 2, wherein the outer surface of the resin layer is the outer surface of the developer carrier member.

11. An electrophotographic image forming apparatus, comprising the main body of the electrophotographic image forming apparatus, and a processing cartridge detachably mounted to the main body, wherein the processing cartridge is the processing cartridge according to claim 1 or 2, the main body has main body contacts that are electrically connected to the contacts of the processing cartridge when the processing cartridge is mounted to the main body, and when the processing cartridge is mounted to the main body, a predetermined voltage can be applied to the developer layer thickness control member.

12. An electrophotographic image forming apparatus, comprising: a developer, a developer carrier member, a developer layer thickness control member that contacts the developer carrier member and controls the layer thickness of the developer carried on the developer carrier member, and a developer storage member that stores the developer, wherein at least a part of the developer layer thickness control member is conductive, a predetermined voltage can be applied to the developer layer thickness control member, the developer carrier member includes a substrate including a conductive outer surface, and a resin layer present on the outer surface side of the substrate, While a metal film is directly provided on the outer surface of the developer carrier member, and a DC voltage of 50 V is applied between the outer surface of the substrate and the metal film in an environment where the temperature is 23°C and the relative humidity is 50%, an AC voltage with an amplitude of 50 V is applied at a frequency varying between 1.0×10 -1 and 1.0×10 5 Hz. In the case where the AC voltage is applied, the impedance at a frequency of 1.0×10 0 to 1.0×10 1 Hz is 1.00×10 6 Ω or more. When the ionization potential of the developer is represented by I(T) and the ionization potential of the outer surface of the developer carrier member is represented by I(R), I(T) and I(R) satisfy the following formula (X): |I(T) - I(R)| ≤ 0.3 eV......(X) And in an environment where the temperature is 23°C and the relative humidity is 50%, a corotron having a gate portion with a width of 3.0 mm is arranged such that the distance between the gate portion and the outer surface of the developer carrier member is 1.0 mm, and the width direction of the gate portion is aligned with the axial direction of the developer carrier member. A voltage of 8 kV is applied to the gate portion, and the corotron is moved relative to the developer carrier member at a speed of 400 mm / second along the axial direction of the developer carrier member to charge the outer surface of the developer carrier member, and when measuring the potential of the outer surface 0.06 seconds after passing through the gate portion, the maximum value of the potential is less than 20.0 V.

Images