Developing roller, process cartridge, and electrophotographic image forming apparatus

Abstract

To provide a developing roller that can prevent a reduction in image density for a long period even when driving torque is reduced and the process speed is accelerated.SOLUTION: A developing roller 1 has a substrate 2 having a conductive surface, and a conductive layer 3 on the surface of the substrate. An outer surface of the developing roller 1 comprises at least a first area 4 and a second area 5 having a higher conductivity than the first area. The first area and the second area are arranged adjacent to each other. The first area has at least one polycarbonate. The at least one polycarbonate has a specific structure having a substituent on an aromatic ring of a main chain.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, there has been a growing trend toward higher speeds, higher durability, and energy savings in electrophotographic image forming apparatuses (electrophotographic apparatuses), and there is a demand for reducing the drive torque required to drive the electrophotographic apparatuses. The developing device accounts for a large proportion of the drive torque of an electrophotographic apparatus, and the drive torque generated between the toner supply roller and the developing roller accounts for the majority of this torque. Therefore, energy savings can be achieved by reducing the drive torque between the toner supply roller and the developing roller. In order to reduce the driving torque, for example, it is possible to reduce the contact area of ​​the toner supply roller with the developing roller, or to reduce the difference in peripheral speed between the developing roller and the toner supply roller. However, when the contact area of ​​the toner supply roller or the difference in peripheral speed is reduced as described above, the amount of toner supplied from the toner supply roller to the developing roller may be insufficient.

[0003] Patent Document 1 discloses a developing roller that can attract a sufficient amount of toner even when the driving torque is reduced by mixing insulating portions and conductive portions in a small area near the surface. The developing roller of Patent Document 1 has a small area of ​​insulating and conductive parts mixed near the surface, so that it can attract a sufficient amount of toner even when the driving torque is reduced by, for example, slowing down the rotation speed of the toner supply roller to reduce the difference in peripheral speed of the developing roller.An example is disclosed in which highly durable polycarbonate is used for the insulating parts. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-020958 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the developing roller of Patent Document 1 is used, the image density may decrease if the process speed is increased.

[0006] Therefore, the present disclosure provides a developing roller that can reduce the drive torque between the toner supply roller and the developing roller and can suppress a decrease in density of an electrophotographic image over a long period of time even when the process speed is increased.The present disclosure also provides a process cartridge and an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images. [Means for solving the problem]

[0007] The present disclosure provides a developer roller having a substrate having an electrically conductive surface and a conductive layer on the surface of the substrate, the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region, the first region and the second region are disposed adjacent to each other; The first region includes at least one polycarbonate, and the at least one polycarbonate has a structure represented by the following general formula (1A): [ka] In general formula (1A), R1 to R8 each independently represent a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R9 and R 10 are each independently a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms, or R9 and R 10 is R9 and R 10are a group of atoms necessary to bond with each other to form an alicyclic structure having 6 to 12 carbon atoms, However, (1A) satisfies at least one condition selected from the group consisting of the following conditions 1 and 2: ·Condition 1 At least one selected from the group consisting of R1 to R8 is the alkyl group having 1 to 9 carbon atoms or the aryl group having 6 to 10 carbon atoms. ·Condition 2 R9 and R 10 At least one selected from the group consisting of is a linear or branched alkyl group having 2 or more carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0008] The present disclosure also provides a process cartridge configured to be detachably attached to a main body of an electrophotographic image forming apparatus, The process cartridge includes at least a developing means, The present invention relates to a process cartridge, wherein the developing means has the above-mentioned developing roller.

[0009] The present disclosure also provides an electrophotographic image forming apparatus, the electrophotographic image forming apparatus comprises a developing means, The present invention also relates to an electrophotographic image forming apparatus, wherein the developing means has the above-mentioned developing roller. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to obtain a developing roller that can reduce the drive torque between the toner supply roller and the developing roller and suppress a decrease in density of an electrophotographic image over a long period of time even when the process speed is increased.Furthermore, according to the present disclosure, it is possible to obtain a process cartridge and an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic cross-sectional view illustrating an example of a developing roller. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of a process cartridge. [Figure 3] 1 is a schematic cross-sectional view of an example of an electrophotographic apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0012] In the present disclosure, unless otherwise specified, the expressions "XX or more and YY or less" and "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. When a range is specifically described, the upper and lower limits of each numerical range can be arbitrarily combined. In addition, in the present disclosure, for example, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. When XX is a group, multiple XXs may be selected, and the same applies to YY and ZZ.

[0013] In a typical non-magnetic one-component development method, a sufficient amount of toner in the development device is first supplied onto the development roller by a toner supply roller. The toner supplied onto the development roller is then regulated by a toner regulating member such as a development blade. This results in an appropriate amount of toner being coated onto the development roller.

[0014] The developing roller disclosed in Patent Document 1 has a substrate with a conductive surface and a conductive layer on the surface of the substrate. The outer surface of the developing roller is composed of at least an insulating portion and a conductive portion, and the insulating portion and the conductive portion are arranged adjacent to each other. When such a developing roller is driven in a developing device, the insulating portion of the developing roller surface becomes charged by rubbing against a contact member such as a developing blade and toner at the contact position. This generates a local potential difference between the charged insulating portion surface and the uncharged conductive portion surface.

[0015] When there is a localized potential difference on the surface of the developing roller, an electric field gradient is generated due to the potential difference. If an object is present in this electric field gradient, the object is polarized by the electric field gradient, generating a gradient force that points toward the surface of the developing roller. In other words, when toner is present near a developing roller that has such a localized potential difference on its surface, the developing roller can attract the toner to its surface. As a result, even if the amount of toner supplied from the toner supply roller to the developing roller is reduced by reducing the contact area of ​​the toner supply roller with the developing roller, the developing roller can attract the toner itself, allowing image formation without a decrease in density.

[0016] However, when the process speed of the developing roller of Patent Document 1 is increased, the time that the insulating portion rubs against the contact member and toner when passing through the contact position is shortened, and the amount of charge on the insulating portion decreases. As a result, the local potential difference generated between the surface of the insulating portion and the conductive portion becomes smaller, the gradient force decreases, the amount of toner attracted to the developing roller decreases, and the density decreases.

[0017] Furthermore, when used for a long period of time, defects such as wear and cracks may occur on the surface of the insulating part. As a result, for example, the area of ​​the insulating part becomes smaller, the amount of charge on the insulating part decreases, and the gradient force decreases. As a result, the amount of toner attracted decreases, and the density is thought to decrease.

[0018] Therefore, the present inventors have conducted extensive research, focusing on the dielectric properties of the insulating portion and durability against wear and cracking, from the viewpoint of obtaining a developing roller that can suppress a decrease in image density even when the process speed is increased and the roller is used for a long period of time. As a result, they have found that a developing roller having the following configuration can suppress a decrease in density even when the process speed is increased and the roller is used for a long period of time.

[0019] The present disclosure provides a developer roller having a substrate having an electrically conductive surface and a conductive layer on the surface of the substrate, the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region, the first region and the second region are disposed adjacent to each other; The first region includes at least one polycarbonate, and the at least one polycarbonate has a structure represented by the following general formula (1A). [ka]

[0020] In general formula (1A), R1 to R8 each independently represent a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R9 and R 10 are each independently a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms, or R9 and R 10 is R9 and R 10 are a group of atoms necessary to bond with each other to form an alicyclic structure having 6 to 12 carbon atoms, However, (1A) satisfies at least one condition selected from the group consisting of the following conditions 1 and 2: ·Condition 1 At least one selected from the group consisting of R1 to R8 is the alkyl group having 1 to 9 carbon atoms or the aryl group having 6 to 10 carbon atoms. ·Condition 2 R9 and R 10 At least one selected from the group consisting of is a linear or branched alkyl group having 2 or more carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0021] The reason why the first region (insulating portion) containing polycarbonate having such a structure exhibits the effects of suppressing a decrease in image density and improving durability is presumed to be as follows. First, polycarbonates having the structure of general formula (1A) included in the first region have benzene rings in the main chain, and therefore are highly durable and have excellent resistance to wear, cracking, etc. even when used for a long period of time.

[0022] In addition, polycarbonates having the structure of general formula (1A) have steric hindrance in the aromatic rings of the main chain, resulting in lower molecular orientation and higher molecular mobility than general polycarbonates. Therefore, it is believed that the use of polycarbonates of general formula (1A) could suppress concentration loss even when the process speed was increased.

[0023] The insulating portion becomes charged at the contact point with a contact member such as a developing blade. The contact point has a width of less than 1 mm, and a high electric field is applied due to the blade bias and the charge of the toner. When the process speed is increased, the contact point is passed in a short time, and the time of friction between the insulating portion and the contact member or toner is further shortened, which may result in insufficient charging. Therefore, when the process speed is increased, charging must be achieved in a short time, and it is thought that a high dielectric constant is required in a short time, making it easy for charge exchange to occur.

[0024] On the other hand, in order to strongly express the gradient force that attracts the toner, Since a large electric field needs to be generated by the charge generated, it is preferable that the dielectric constant of the insulating portion is small. When attracting the toner in the developer container, no external electric field acts on the developing roller, so it is considered necessary for the dielectric constant to be small when no external electric field acts.

[0025] The dielectric constant of a resin is strongly affected by molecular orientation, with a high dielectric constant when the molecular orientation is high and a low dielectric constant when the molecular orientation is low. Based on this, we inferred the dielectric constant of polycarbonate due to the molecular orientation of its structure.

[0026] The polycarbonate used in the present disclosure is presumed to have steric hindrances around the aromatic rings, which act to loosen the adhesive forces of the aromatic rings compared to conventional polycarbonates, resulting in low crystallinity and less uniform molecular orientation than conventional polycarbonates. Therefore, when a high electric field is applied for a short period of time, there are areas with high molecular mobility, such as steric hindrances around the aromatic rings, and microscopic molecular orientation occurs in some of these areas, resulting in a higher dielectric constant than conventional polycarbonates. On the other hand, when no external electric field is applied, the molecular orientation is lower than conventional polycarbonates, which is thought to result in a lower dielectric constant than conventional polycarbonates.

[0027] From the above speculation, it is believed that by using polycarbonate of general formula (1A), when the process speed is increased, the dielectric constant immediately after passing the contact position is higher than that of conventional materials, which facilitates charge transfer between the contact member and the toner, and the insulating part is sufficiently charged. Furthermore, since the dielectric constant when no external electric field is acting after passing the contact position is lower than that of conventional materials, it is possible to increase the gradient force and attract a sufficient amount of toner.

[0028] That is, in the present disclosure, a steric hindrance is provided around the aromatic ring of the polycarbonate structure, thereby reducing the driving torque and obtaining a developing roller that can be applied to electrophotographic devices with faster process speeds and that can suppress a decrease in image density even when used for a long period of time.

[0029] The developing roller according to this embodiment will be described in detail below. <Developing roller> Examples of developing rollers include schematic cross-sectional views of the developing roller taken in a direction perpendicular to the longitudinal direction (axial direction) of the developing roller, as shown in Figures 1A and 1B. Specifically, as shown in Figure 1A, developing roller 1 has a conductive substrate 2 and a conductive layer 3 on the substrate. The developing roller 1 has a first region 4 (insulating portion) exposed on the outer surface of the conductive layer 3 (the surface opposite to the surface facing the substrate), and a second region 5 (conductive portion) having a higher conductivity than the first region. As shown in Figure 1A, the first region 4 may protrude from the outer surface of the developing roller, for example.

[0030] 1B, the developing roller may have a configuration in which a first region 4 is present in the conductive layer 3, and the first region 4 and the second region 5 are exposed on the outer surface. For example, the first region 4 and the second region 5 may form a substantially flat outer surface. That is, the developing roller may have the second region 5 disposed on a portion of the surface (outer surface) of the conductive layer 3, and the outer surface of the developing roller may include at least the first region 4 and the second region 5 adjacent to each other. The conductive layer 3 may be a single layer or multiple layers.

[0031] <Base> The substrate is conductive and has the function of supporting the conductive layer formed thereon. Examples of the material of the substrate include metals such as iron, copper, aluminum, and nickel; and alloys containing these metals such as stainless steel, duralumin, brass, and bronze. These may be used alone or in combination of two or more. The surface of the substrate may be coated with a coating for the purpose of imparting scratch resistance. Furthermore, a substrate made of a resin whose surface is coated with a metal to make the surface conductive, or a substrate made of a conductive resin composition, can also be used.

[0032] <Conductive layer> In the developing roller, the conductive layer is disposed on the substrate and can have a single-layer structure or a laminated structure of two or more layers. In particular, in a non-magnetic one-component contact development process, a developing roller having two conductive layers is preferably used. Note that when the developing roller has multiple conductive layers, it is preferable that each conductive layer satisfies the following conditions unless otherwise specified.

[0033] The conductive layer may contain elastic materials such as resin and rubber. Specific examples of resin and rubber include polyurethane resin, polyamide, urea resin, polyimide, melamine resin, fluororesin, phenolic resin, alkyd resin, silicone resin, polyester, ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), fluororubber, silicone rubber, epichlorohydrin rubber, NBR hydride, and urethane rubber. These resins and rubbers may be used alone or in combination as needed.

[0034] The second region 5 preferably contains at least one selected from the group consisting of the above-mentioned resins and rubbers. The materials of the resins and rubbers can be identified by measuring the conductive layer of the developing roller using a Fourier transform infrared-visible spectrophotometer. Among the materials mentioned above, when the conductive layer has a laminated structure, it is preferable that the layer (lower layer) of the conductive layer that is disposed closest to the substrate contains silicone rubber.

[0035] Examples of silicone rubbers include polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, and polyphenylvinylsiloxane, as well as copolymers of these siloxanes.

[0036] Furthermore, the layer (outermost layer) of the conductive layer disposed on the outermost surface side preferably contains a polyurethane resin. Polyurethane resins are preferred because they have excellent frictional charging performance with toner, excellent flexibility, which increases the chance of contact with toner, and abrasion resistance. The conductive layer preferably has a two-layer structure, with the layer (lower layer) disposed on the substrate side preferably containing silicone rubber and the layer (outermost layer) disposed on the outer surface side of the conductive layer preferably containing a polyurethane resin.

[0037] Examples of polyurethane resins include ether-based polyurethane resins, ester-based polyurethane resins, acrylic-based polyurethane resins, and carbonate-based polyurethane resins. These polyurethane resins can be obtained by reacting a known polyol with an isocyanate compound.

[0038] Specific examples of polyols include polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol; polyester polyols such as polyethylene succinate diol, polybutylene succinate diol, polyethylene adipate diol, and polybutylene adipate diol; and polycarbonate polyols such as polyethylene carbonate diol and polybutylene carbonate diol.

[0039] The isocyanate component to be reacted with these polyol components is not particularly limited, but examples thereof include aliphatic polyisocyanates such as ethylene diisocyanate and 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPD), and the like. I), alicyclic polyisocyanates such as cyclohexane 1,3-diisocyanate and cyclohexane 1,4-diisocyanate, aromatic isocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), polymeric diphenylmethane diisocyanate, xylylene diisocyanate and naphthalene diisocyanate, as well as copolymers thereof, isocyanurates, TMP adducts, biurets and block products thereof can be used. Among these, aromatic isocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate are more preferably used.

[0040] The conductive layer preferably contains a conductive agent to obtain conductivity. Examples of conductive agents include ionic conductive agents and electronic conductive agents such as carbon black. Carbon black is preferred because it can control the conductivity of the conductive layer and the charging performance of the conductive layer with respect to the toner. The volume resistivity of the conductive layer is usually 1.0×10 3 Ω cm or more, 1.0×10 11 The volume resistivity of the conductive layer is preferably in the range of Ω·cm or less. The volume resistivity of the conductive layer can be measured using the same method as that for the volume resistivity of the first region, which will be described later.

[0041] Specific examples of the carbon black include conductive carbon black such as "Ketjenblack" (trade name, manufactured by Lion Corporation) and acetylene black; and rubber carbon black such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT. Other carbon blacks that can be used include oxidation-treated carbon black for color inks and pyrolytic carbon black.

[0042] The amount of carbon black added is preferably 5 parts by mass or more and 50 parts by mass or less, relative to 100 parts by mass of the total of the resin and rubber in the conductive layer. The content of carbon black in the conductive layer can be measured using a thermogravimetric analyzer (TGA).

[0043] In addition to the carbon black, examples of conductive agents that can be used in the conductive layer include: graphite such as natural graphite and artificial graphite; metal powders such as copper, nickel, iron, and aluminum; metal oxide powders such as titanium oxide, zinc oxide, and tin oxide; and conductive polymers such as polyaniline, polypyrrole, and polyacetylene. These can be used alone or in combination of two or more, as needed. The amount of these conductive agents added can be appropriately determined.

[0044] The conductive layer may also contain a charge control agent, a lubricant, a filler, an antioxidant, an antiaging agent, etc., to the extent that the functions of the resin, rubber, and conductive agent are not impaired. The amounts of these additives added can be set appropriately.

[0045] The thickness of the conductive layer (total thickness in the case of a laminated structure) is preferably 1 μm or more and 5 mm or less. The thickness of the conductive layer can be determined by observing and measuring the cross section of the developing roller cut in a direction perpendicular to the axial direction using an optical microscope. When the conductive layer has a two-layer structure, the thickness of the lower layer is preferably 0.1 mm or more and 50.0 mm or less, and more preferably 0.5 mm or more and 10.0 mm or less. The thickness of the outermost layer is preferably 4 μm or more and 100 μm or less, and more preferably 6 μm or more and 30 μm or less.

[0046] When a certain surface roughness is required for the developing roller, roughness-controlling particles can be contained in the conductive layer. In this case, the volume average particle size of the roughness-controlling particles is preferably 3 μm or more and 20 μm or less. Furthermore, the amount of the particles contained in the conductive layer is preferably 1 part by mass or more and 50 parts by mass per 100 parts by mass of the resin and rubber in the conductive layer combined. The content of the particles in the conductive layer can be measured using an analytical method such as thermogravimetric analysis. As the roughness-controlling particles, fine particles of polyurethane resin, polyester resin, polyether resin, polyamide resin, acrylic resin, polycarbonate, or the like can be used.

[0047] <First Area> The first region (hereinafter also referred to as the insulating portion) is disposed on the outermost layer of the conductive layer and is exposed. The first region preferably covers a portion of the outermost layer and constitutes a portion of the outer surface of the developing roller. The first region may be, for example, scattered on the outer surface of the developing roller. The first regions may be connected to each other to the extent that the conductive layer (second region) of the developing roller is exposed.

[0048] (Materials constituting the first region (insulating portion)) The material constituting the insulating part (insulating material) contains a polycarbonate represented by the following general formula (1A), which reduces the driving torque between the toner supply roller and the developing roller and makes it possible to suppress a decrease in density of electrophotographic images over a long period of time, even when the process speed is increased.

[0049] [ka]

[0050] In general formula (1A), R1 to R8 are each independently a hydrogen atom, an alkyl group having 1 to 9 carbon atoms (preferably 1 to 4, more preferably 1 to 3), or an aryl group having 6 to 10 carbon atoms (preferably 6 to 8, more preferably 6). R9 and R 10 are each independently a hydrogen atom, an alkyl group having 1 to 9 carbon atoms (preferably 1 to 4, more preferably 1 to 3), or an aryl group having 6 to 10 carbon atoms (preferably 6 to 8, more preferably 6), or R9 and R 10 is R9 and R 10 are a group of atoms necessary to bond with each other to form an alicyclic structure having 6 to 12 carbon atoms.

[0051] However, (1A) satisfies at least one condition selected from the group consisting of the following conditions 1 and 2. ·Condition 1 At least one (preferably 1 to 4, more preferably 1 to 3, and even more preferably 2) selected from the group consisting of R1 to R8 is an alkyl group having 1 to 9 carbon atoms (preferably 1 to 4, more preferably 1 to 3), or an aryl group having 6 to 10 carbon atoms (preferably 6 to 8, more preferably 6). The remainder of R1 to R8 are preferably hydrogen atoms. ·Condition 2 R9 and R 10 At least one selected from the group consisting of R9 and R is a linear or branched alkyl group having 2 or more carbon atoms (preferably 2 to 10, more preferably 3 to 6), or an aryl group having 6 to 10 carbon atoms (preferably 6 to 8, more preferably 6). 10 It is preferable that one of them satisfies the above conditions, and the other is an alkyl group having 1 to 3 carbon atoms (preferably 1).

[0052] Preferred polycarbonates are described below. Examples of polycarbonates include polycarbonates in which, in the general formula (1A), at least one of R1 and R3 is the above-mentioned alkyl group or aryl group, and at least one of R6 and R8 is the above-mentioned alkyl group or aryl group. In this case, the remaining R1 to R8 are hydrogen atoms.

[0053] In addition, in the general formula (1A), R9 and R 10 In this case, at least one of R9 and R10 is a linear or branched alkyl group having 1 to 9 carbon atoms (preferably 1 to 4 carbon atoms), or an unsubstituted phenyl group. 10 The remainder is a methyl group. Specifically, the polycarbonate preferably contains at least one selected from the group consisting of the following structural formulas (1) to (3).

[0054] [ka]

[0055] The polycarbonate containing the structural formulas (1) to (3) can enhance the micro-molecular orientation in addition to excellent durability. As a result, it is possible to obtain a developing roller that can reduce the driving torque and can be applied to an electrophotographic image forming apparatus with a faster process speed, and can further suppress the decrease in image density even when used for a long period of time. can be done.

[0056] Furthermore, it is preferable that the polycarbonate has at least one structure selected from the group consisting of the structure represented by the structural formula (2) and the structure represented by the structural formula (3). This can loosen the adhesive force between aromatic rings in the main chain and enhance the micro-molecular orientation. As a result, a developing roller can be obtained that can further suppress density reduction in electrophotographic images even when applied to an electrophotographic image forming apparatus with a higher process speed.

[0057] Furthermore, it is preferable that the at least one polycarbonate comprises a first polycarbonate and a second polycarbonate having mutually different structures, and it is preferable that the first polycarbonate has a structure represented by structural formula (1), and the second polycarbonate comprises a polycarbonate having at least one structure selected from the group consisting of a structure represented by structural formula (2) and a structure represented by structural formula (3).

[0058] The above-mentioned structure can further loosen the adhesive force of the aromatic rings and enhance the micro-molecular orientation, thereby providing a developing roller that can further suppress a decrease in density of an electrophotographic image even when applied to an electrophotographic image forming apparatus with a higher process speed.

[0059] Furthermore, it is more preferable that the first polycarbonate further has a structure represented by structural formula (4). Also, it is more preferable that the second polycarbonate further has a structure represented by structural formula (4). [ka]

[0060] In addition to the fact that structural formulas (1) to (3) loosen microscopic adhesive forces, the inclusion of structural formula (4) makes it possible to obtain a developing roller with even greater durability. From the viewpoint of durability, the polycarbonate is preferably a copolymer.

[0061] The methods for synthesizing the present polycarbonate are described below. For example, the following two methods can be mentioned. The first is a method in which a bisphenol compound is directly reacted with phosgene (the phosgene method). The second is a method in which a bisphenol compound is subjected to an ester exchange reaction with a bisaryl carbonate such as diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, or dinaphthyl carbonate (the ester exchange method).

[0062] In the phosgene method, a bisphenol compound is usually reacted with phosgene in the presence of an acid binder and a solvent. Examples of the acid binder used here include pyridine and alkali metal hydroxides such as potassium hydroxide and sodium hydroxide. Examples of the solvent include methylene chloride and chloroform. Furthermore, a catalyst or a molecular weight modifier may be added to promote the polycondensation reaction. Examples of the catalyst include triethylamine. Examples of the molecular weight regulator include tertiary amines, quaternary ammonium salts, etc. Examples of the molecular weight regulator include monofunctional compounds such as phenol, p-cumylphenol, t-butylphenol, and long-chain alkyl-substituted phenols.

[0063] In addition, when synthesizing polycarbonate, antioxidants such as sodium sulfite and hydrosulfite, and branching agents such as phloroglucin and isatin bisphenol may be used. The reaction temperature when synthesizing polycarbonate is preferably 0 to 150°C, more preferably 5 to 40°C. The reaction time varies depending on the reaction temperature, but is generally preferably 0.5 minutes to 10 hours, more preferably 1 minute to 2 hours. During the reaction, it is preferable to maintain the pH of the reaction system at 10 or higher.

[0064] The material constituting the insulating part is preferably a polycarbonate having a structure represented by general formula (1A): The chemical structure of the material constituting the insulating part can be identified by NMR analysis.

[0065] In the present invention, the weight-average molecular weight (Mw) of the polycarbonate is preferably 1,000 to 800,000, more preferably 10,000 to 100,000, and even more preferably 50,000 to 75,000. Generally, the smaller the number-average molecular weight of the polycarbonate, the more likely it is that the insulating portions will gather together when formed on the elastic layer, resulting in a relatively tall, bowl-shaped configuration. Furthermore, the larger the number-average molecular weight of the polycarbonate, the more likely it is that the insulating portions will spread on the elastic layer, resulting in a low, branched configuration. Therefore, it is preferable to set the number-average molecular weight of the polycarbonate within the above range, as this facilitates the formation of an insulating portion that covers a portion of the elastic layer.

[0066] The weight average molecular weight of a resin can be measured as follows. GPC The molecular weight distribution of the polycarbonate is measured by gel permeation chromatography (GPC) as follows. First, the sample is dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. The resulting solution is then filtered through a solvent-resistant membrane filter "Myshoridisc" (manufactured by Tosoh Corporation) with a pore size of 0.5 μm to obtain a sample solution. The sample solution is prepared so that its concentration is 0.5% by mass. This sample solution is measured under the following conditions: Apparatus: HLC-8320GPC (detector: RI) (manufactured by Tosoh Corporation) Column: Shodex LF-404, 2 columns of LF-404 (Showa Denko) Eluent: tetrahydrofuran (THF) ·Flow rate: 0.4ml / min Oven temperature: 40.0℃ Sample injection volume: 0.10 ml To calculate the molecular weight of a sample, a molecular weight calibration curve prepared using a standard polystyrene resin (for example, "EasiVial PS-H Polystyrene" manufactured by Agilent Technologies) is used.

[0067] The content of the structure represented by general formula (1A) in at least one polycarbonate is preferably 20 to 100 mol % based on all structural units in the polycarbonate. Furthermore, the content of the structure represented by general formula (1A) is preferably 30 to 100 mol % based on all resins in the first region. By setting the content within this range, steric hindrance near the aromatic ring can be used to relax microscopic adhesion forces, achieving a desired dielectric constant and attracting a sufficient amount of toner. In calculating mol %, the polycarbonate structural unit is defined as -OR-OCO- (R is any group).

[0068] The content of the structure represented by general formula (1A) in the at least one polycarbonate is preferably 20 to 100 mass%, more preferably 40 to 100 mass%, and even more preferably 50 to 90 mass%, based on the mass of the polycarbonate. The content of the structure represented by general formula (1A) is preferably 5 to 100 mass%, more preferably 5 to 25 mass%, based on the total mass of the resin in the first region.

[0069] The content of the structure represented by structural formula (1) in the polycarbonate is preferably 10 to 100 mass %, more preferably 20 to 70 mass %. The content of the structure represented by structural formula (2) in the polycarbonate is preferably from 10 to 100% by mass, more preferably from 20 to 70% by mass. The content of the structure represented by structural formula (3) in the polycarbonate is preferably from 10 to 100% by mass, more preferably from 20 to 70% by mass. The polycarbonate preferably contains 0 to 80 mass %, more preferably 15 to 50 mass %, of the structure represented by structural formula (4).

[0070] The content of each structure in polycarbonate can be analyzed by infrared absorption spectroscopy and NMR.

[0071] IR analysis of polycarbonate ATR-IR analysis using polycarbonate is carried out as follows. For the IR analysis, a Fourier transform infrared spectrometer (Spectrum One: manufactured by PerkinElmer) equipped with a universal ATR sampling accessory was used. Other conditions were as follows: The incident angle of the infrared light (λ = 5 μm) is set to 45°. A Ge ATR crystal (refractive index = 4.0) is used as the ATR crystal. Other conditions are as follows: Range Start: 4000cm -1 End: 650cm -1 (Ge ATR crystal) Duration Scan number: 16 Resolution: 4.00cm -1 Advanced: CO2 / H2O correction

[0072] (1) A Ge ATR crystal (refractive index = 4.0) is attached to the device. (2) Set the Scan type to Background and Units to EGY and measure the background. (3) Set Scan type to Sample and Units to A. (4) 0.01 g of sample is precisely weighed onto the ATR crystal. (5) Pressurize the sample with the pressure arm (Force Gauge is 90). (6) Measure the sample.

[0073] NMR analysis of polycarbonate NMR analysis using polycarbonate is carried out as follows. 1 g of deuterated chloroform (chloroform-d, 99.8 atom% D, containing 0.05% (v / v) TMS, manufactured by Sigma-Aldrich Japan Co., Ltd.) was added to 20 mg of sample and completely dissolved. This solution was transferred to a glass NMR sample tube with an outer diameter of 5 mm (manufactured by Norell, ST500-7) and proton NMR measurement was performed. The NMR instrument used was a Bruker AVANCE500. Other conditions were as follows: - 32 times total Rotation speed: 20Hz

[0074] The remaining parameters were set automatically by ICON-NMR. In the obtained spectrum, the chemical shift value of the peak of the methyl group of tetramethylsilane was corrected to 0 ppm. In order to confirm the polycarbonate structure of the insulating portion formed on the outer surface of the developing roller, a micromanipulator (product name: Axis Pro, manufactured by Micro Support Co., Ltd.) was used to sample the insulating portion of the developing roller, and the polycarbonate structure was confirmed by analyzing it as described above.

[0075] The first region (insulating portion) may be made of polycarbonate alone, or may contain the second resin described below. Specific examples of the second resin include at least one selected from the group consisting of acrylic resin, polyolefin resin, epoxy resin, and polyester resin. The first region preferably further contains a (meth)acrylic resin, and more preferably contains an acrylic resin. The present inventors speculate that the reason why the use of the second resin in combination is more effective is as follows.

[0076] Polycarbonate has steric hindrance in the aromatic rings of its main chain, resulting in lower molecular orientation and higher molecular mobility than general polycarbonates. However, the microscopic adhesive forces of the polycarbonate main chain are strong, and further improvement of molecular mobility requires loosening these microscopic adhesive forces. Here, the second resin, particularly with a bifunctional or higher monomer, forms a three-dimensional structure. When this second resin is used, it penetrates between the main chains, contributing to loosening the microscopic adhesive forces and further increasing the molecular orientation of the polycarbonate. Therefore, when a high electric field is applied instantaneously, in addition to the steric hindrance around the aromatic rings, areas of high molecular mobility are created in the main chain itself, resulting in microscopic molecular orientation in some of these areas, further increasing the dielectric constant.

[0077] From the above speculation, it is believed that by using a second resin in addition to the polycarbonate of general formula (1A), when the process speed is increased, the instantaneous dielectric constant when passing through the contact position becomes even larger, making it easier for charge to be exchanged with the contacting member and toner, and the insulating part is more sufficiently charged. Furthermore, since the dielectric constant is small when no external electric field is acting after passing through the contact position, it is possible to increase the gradient force and attract a sufficient amount of toner.

[0078] Specific examples of the acrylic resin include polymers and copolymers of at least one selected from the group consisting of the following monomers: methyl methacrylate, 4-tert-butylcyclohexanol acrylate, stearyl acrylate, lauryl acrylate, 2-phenoxyethyl acrylate, isodecyl acrylate, isooctyl acrylate, isobornyl acrylate, 4-ethoxylated nonylphenol acrylate, isobornyl acrylate, ethoxylated bisphenol A diacrylate, and PO-modified neopentyl glycol diacrylate.

[0079] The content of polycarbonate in the first region is preferably 20 to 90 mass %, and more preferably 40 to 70 mass %, based on the total resin in the first region. The first region may contain, for example, 10 to 80 mass % of the second resin, and more preferably 30 to 60 mass %, based on the total mass of the resin in the first region. When the first region contains a second resin, the presence of the second resin can be confirmed by analyzing it using infrared absorption spectroscopy.

[0080] (Volume resistivity of the first region) The volume resistivity of the first region is 1.0×10 13 ~1.0×10 18 Ω·cm is preferred, and 1.0×10 14 ~1.0×10 17It is more preferable that the volume resistivity of the first region is within the above range. If the volume resistivity of the first region is within the above range, the first region can be charged quickly and easily. The volume resistivity of the first region can be controlled by the amount of polar groups and crystallinity of the polycarbonate used or the second resin, such as an acrylic resin, used as needed.

[0081] Confirmation of the first and second areas First, an optical microscope or a scanning electron microscope is used to confirm that two or more regions exist on the outer surface of the electrophotographic member, and the first region and the second region can be distinguished. The first and second regions can be identified as a difference in reflectance intensity due to differences in the exposed surface and surface morphology. Furthermore, because the first and second regions have different resistivities, they can be more clearly distinguished by combining them with an electrostatic force microscope (EFM). For example, the optical microscope can be the Digital Microscope VHX-5000 (product name, manufactured by Keyence Corporation), the electron microscope can be the JSM-7800FPRIME (product name, manufactured by JEOL Ltd.), and the electrostatic force microscope can be the Model 1100TN (product name, manufactured by Trek Japan).

[0082] Measurement of volume resistivity of the first region A sample was cut out from the developing roller and a thin sample with a planar size of 50 μm square and a thickness t of 100 nm was prepared using a microtome. Next, this thin sample was placed on a metal flat plate and pressed from above with a surface area S of 100 μm. 2 The thin sample was pressed against the metal terminal. In this state, a voltage of 1 V was applied between the metal terminal and the metal plate using an electrometer (product name: 6517B, manufactured by KEITHLEY) to measure the resistance R. From this resistance R, the volume resistivity pv was calculated using the following calculation formula (1). Calculation formula (1) pv=R×S / t

[0083] (Occupied area of ​​the first area) When a square observation area with sides of 900 μm is placed on the outer surface of the developing roller so that the axial direction of the developing roller and one side of the observation area are parallel, the ratio of the total area of ​​the first area to the area of ​​the square area (hereinafter also referred to as "occupancy rate RE") is preferably 10 to 60 area %. The occupancy rate RE is more preferably 20 to 50 area %, and even more preferably 20 to 40 area %. By setting the occupancy rate RE within the above range, it is possible to improve the toner transport force of the developing roller. The occupancy ratio RE can be controlled by the wettability of the constituent material solution of the first region, the viscosity of the solution, the drying speed, the surface roughness of the conductive layer, the solid content of the solution, and the like. On the other hand, the proportion of the total area of ​​the second regions in the area of ​​the square regions is preferably 40 to 90 area %, more preferably 50 to 80 area %, and even more preferably 60 to 80 area %.

[0084] Measurement of the occupancy rate (RE) of the first region The occupancy rate RE of the first region was measured as follows. An objective lens with a magnification of 20x was installed on a laser microscope (product name: VK-X100, manufactured by Keyence Corporation). Images of the surface of the developing roller were taken at nine areas: two locations 10 mm inward from both ends in the longitudinal direction, one location in the center, and three locations in the circumferential direction (at 120° intervals), and the images were joined so that each side was 900 μm. Next, the tilt of the obtained observation image was corrected in quadratic surface correction mode. At the center of the corrected image, the area occupied by the first region within a square area with sides of 900 μm was measured. The measurement was carried out using image processing software such as ImageJ. The area occupied by this first region was divided by the area of ​​a square with sides of 900 μm, and the resulting value was taken as the occupancy rate RE in this area. The arithmetic mean value of the occupancy rates RE obtained in the nine regions was calculated, and this was taken as the occupancy rate RE of the developing roller 1. The first and second regions on the surface of the developing roller were distinguished by the above-mentioned procedure using an electron microscope and an electrostatic force microscope.

[0085] (Height of the first area) The average height HD of each of the plurality of first regions from the contact point with the second region is preferably 0.1 to 15.0 μm, and more preferably 0.5 to 7.0 μm. By setting this average height HD to 0.1 μm or more, it is possible to better attract toner while maintaining durability against wear and cracking. By setting the average height HD to 15.0 μm or less, friction between the insulating portion and toner is more likely to occur, even when the process speed is increased, and the insulating portion is more likely to be charged.

[0086] First area height measurement The height of the first region is measured by observing the surface of the developing roller using a laser microscope (product name: VK-8700, manufactured by Keyence Corporation) equipped with an objective lens with a magnification of 20x. Next, the tilt of the obtained observation image is corrected. The tilt correction is performed in quadratic surface correction mode. The corrected image is used to measure the first region that fits within the image. The obtained three-dimensional observation image is used to calculate the difference "H2 - H1" between the highest point H2 of the first region and the height H1 of the conductive elastic layer (contact area between the first region and the second region).

[0087] The first and second regions were distinguished by the above-mentioned procedure using an electron microscope and an electrostatic force microscope. Observations are made at 10 points on the developing roller (one point in each of the 10 regions obtained by dividing the longitudinal direction into 10 equal parts), and the arithmetic mean value of the obtained "H2 - H1" is taken as the average height HD of the first region. In this case, all of the first region that is completely contained within a square area with sides of 300 μm is measured, and first regions that are not completely contained within this area are not measured.

[0088] <Second Area> The second region is a part of the outer surface of the developing roller, and is adjacent to the insulating portion, and functions as a conductive portion having higher conductivity than the insulating portion. In the embodiment shown in Figures 1A and 1B, a part of the conductive layer constituting the outer surface of the developing roller corresponds to the second region.

[0089] The second region may be present (exposed) in a portion of the outer surface of the developing roller, and the conductive portion may be separated into multiple parts on the outer surface of the developing roller, or multiple conductive portions may be connected (for example, as a series of conductive portions). However, from the viewpoint of uniformly transporting toner, it is preferable that a (series of) second region is arranged on the outer surface of the developing roller so as to surround multiple first regions arranged at equal intervals on the outer surface of the developing roller.

[0090] The volume resistivity of the second region is 1.0×10 5 ~1.0×10 11 Ω·cm is preferred, and 1.0×10 5 ~1.0×10 8 It is more preferable that the volume resistivity of the second region is Ω·cm. If the volume resistivity of the second region is within the above range, the charge can be sufficiently removed. The volume resistivity of the second region can be measured in the same manner as in the measurement of the volume resistivity of the first region described above, by selecting the second region. The volume resistivity of the second region can be controlled by, for example, the content or dispersion state of the conductive agent. can be done.

[0091] <Confirmation of the first and second areas> The presence of the first and second regions in the developing roller can be confirmed by first observing the presence of two or more regions on the outer surface of the developing roller using an optical microscope, a scanning electron microscope, or the like. Furthermore, the fact that the first region is electrically insulating and that the second region has higher conductivity than the first region can be confirmed by charging the outer surface of the developing roller including the first region and the second region and then measuring the residual potential distribution. The residual potential distribution can be confirmed, for example, by sufficiently charging the outer surface of the developing roller using a charging device such as a corona discharge device, and then measuring the residual potential distribution on the charged outer surface of the developing roller using an electrostatic force microscope (EFM) or a surface potential microscope (KFM).

[0092] The electrical insulation of the electrically insulating portion constituting the first region and the electrical conductivity of the conductive layer constituting the second region can also be evaluated by the time constant of the residual potential, in addition to the volume resistivity. The time constant of the residual potential is the time it takes for the residual potential to decay to 1 / e of its initial value, and is an index of how easily the charged potential can be maintained. Here, e is the base of the natural logarithm.

[0093] The potential decay time constant, which is defined as the time required for the potential of the surface of the first region to decay to V0 × (1 / e) (V) when the surface potential of the first region is charged to V0 (V), is preferably 60.0 seconds or more, and more preferably 2000 to 5000 seconds. When the time constant of the first region is 60.0 seconds or more, charging of the first region is carried out quickly and the potential due to charging is easily maintained, which is preferable.

[0094] Furthermore, the potential decay time constant, defined as the time required for the potential of the surface of the second region to decay to V × (1 / e) (V) when the surface potential of the second region is charged to V, is preferably less than 6.0 seconds, more preferably less than the lower limit of measurement. If the time constant of the second region is 6.0 seconds or less, charging of the second region is suppressed, making it easier to generate a potential difference between the second region and the charged first region, and making it easier to exhibit a gradient force.

[0095] In measuring the time constant, if the residual potential is approximately 0 V at the start of measurement using the measurement method described below, that is, if the potential has completely decayed at the start of measurement, the time constant at that measurement point is considered to be less than 6.0 seconds. The time constant of the residual potential can be determined, for example, by sufficiently charging the outer surface of the developing roller using a charging device such as a corona discharge device, and then measuring the time progression of the residual potential in the first and second regions of the charged outer surface of the developing roller using an electrostatic force microscope (EFM).

[0096] Observation of the outer surface of the developing roller The outer surface of the developing roller was observed using an optical microscope (VHX5000 (product name), manufactured by Keyence Corporation), and it was confirmed that two or more regions were present on the outer surface.

[0097] Residual potential distribution measurement The residual potential distribution was measured by corona charging the outer surface of the developing roller on the thin section described below using a corona discharge device, and measuring the residual potential on the outer surface using an electrostatic force microscope (MODEL 1100TN, manufactured by Trek Japan Co., Ltd.) while scanning the thin section.

[0098] Thin sections were prepared using a cryomicrotome (UC-6, Leica Microsystems) A thin section including the outer surface of the developing roller was cut from the developing roller using a cutting tool (manufactured by Epson Corporation). The thin section was cut at a temperature of -150°C so as to have a size of 100 μm × 100 μm of the outer surface of the developing roller, a thickness of 1 μm based on the outer surface of the conductive layer, and include two or more regions on the outer surface of the developing roller. The thin section was placed on a smooth silicon wafer with the surface including the outer surface of the developing roller facing up, and left to stand for 24 hours in an environment at a temperature of 23°C and a relative humidity of 50%.

[0099] In the same environment, the silicon wafer carrying the flake was placed on a high-precision XY stage integrated into the electrostatic force microscope. A corona discharge device with a wire-to-grid electrode distance of 8 mm was used. The corona discharge device was positioned so that the grid electrode was 2 mm away from the silicon wafer surface. The silicon wafer was then grounded, and a voltage of -5 kV was applied to the wire and -0.5 kV to the grid electrode using an external power supply. After the voltage application began, the high-precision XY stage was used to scan the flake parallel to the silicon wafer surface at a speed of 20 mm / s so that the flake passed directly beneath the corona discharge device, thereby corona-charging the outer surface of the developing roller above the flake.

[0100] Next, the thin section was moved directly below the cantilever of the electrostatic force microscope using the high-precision XY stage. The residual potential of the corona-charged outer surface of the developing roller was measured while scanning using the high-precision XY stage, thereby measuring the residual potential distribution. The measurement conditions are as follows: Measurement environment: Temperature 23°C, relative humidity 50% Time from when the measurement point passes directly under the corona discharge device to when the measurement starts: 60 seconds Cantilever: Model 1100TN cantilever (Model number: Model 1100TNC-N, manufactured by Trek Japan Co., Ltd.) Gap between the measurement surface and the tip of the cantilever: 10 μm Measurement range: 99μm x 99μm Measurement interval: 3μm x 3μm

[0101] From the residual potential distribution obtained by the measurement, the presence or absence of residual potential in two or more regions present on the flake was confirmed to determine whether each region was an electrically insulating first region or a second region having higher conductivity than the first region. Specifically, of the two or more regions, a region containing a location where the absolute value of the residual potential was less than 1 V was defined as the second region, and a region containing a location where the absolute value of the residual potential was 1 V or more greater than the absolute value of the residual potential of the second region was defined as the first region, and their presence was confirmed. The above-mentioned method for measuring the residual potential distribution is merely an example, and the device and conditions may be changed to suit the size, spacing, time constant, etc. of the first and second regions to confirm the presence or absence of residual potential in the two or more regions.

[0102] Measurement of the time constant of residual potential The time constant of the residual potential was determined by corona charging the outer surface of the developing roller using a corona discharge device, measuring the time course of the residual potential on the first region or the second region present on the outer surface using an electrostatic force microscope (Model 1100TN, manufactured by Trek Japan Co., Ltd.), and fitting the results to the following equation (1). Here, the measurement point for the first region was the point in the first region confirmed by the measurement of the residual potential distribution where the absolute value of the residual potential was largest. The measurement point for the second region was the point in the second region confirmed by the measurement of the residual potential where the residual potential was approximately 0 V.

[0103] First, the thin piece used to measure the residual potential distribution was placed on a smooth silicon wafer with the surface including the outer surface of the developing roller facing up, and left in an environment of room temperature 23°C and relative humidity 50% for 24 hours.

[0104] Next, in the same environment, the silicon wafer carrying the flake was placed on a high-precision XY stage integrated into the electrostatic force microscope. A corona discharge device with a distance between the wire and grid electrode of 8 mm was used. The corona discharge device was positioned so that the distance between the grid electrode and the silicon wafer surface was 2 mm. The silicon wafer was then grounded, and a voltage of -5 kV was applied to the wire and -0.5 kV to the grid electrode using an external power supply. After the voltage application began, the high-precision XY stage was used to scan the flake parallel to the silicon wafer surface at a speed of 20 mm / s so that the flake passed directly beneath the corona discharge device, thereby corona-charging the flake.

[0105] Next, the high-precision XY stage was used to move the measurement point of the first or second region to directly below the cantilever of the electrostatic force microscope, and the time transition of the residual potential was measured. The electrostatic force microscope was used for the measurement. The measurement conditions are as follows. Measurement environment: Temperature 23°C, relative humidity 50% Time from when the measurement point passes directly under the corona discharge device to when the measurement starts: 15 seconds Cantilever: Model 1100TN cantilever (Model number: Model 1100TNC-N, manufactured by Trek Japan Co., Ltd.) Gap between the measurement surface and the tip of the cantilever: 10 μm ·Measurement frequency: 6.25Hz Measurement time: 1000 seconds

[0106] The time constant τ was calculated by fitting the time transition of the residual potential obtained in the above measurement to the following equation (1) by the least squares method. V0 = V(t) × exp(-t / τ) … (1) t: Time (seconds) elapsed since the measurement point passed directly under the corona discharge device V0: Initial potential (potential at t = 0 seconds) (V) V(t): Residual potential (V) t seconds after the measurement point passes directly under the corona discharge device τ: time constant of residual potential (seconds)

[0107] The time constant τ of the residual potential was measured at a total of nine points on the outer surface of the developing roller, three longitudinally and three circumferentially, and the average value was used as the time constant of the residual potential of the first or second region according to the present invention. Note that, in the measurement of the second region, if the measurement included a point where the residual potential was approximately 0 V at the start of measurement, i.e., 15 seconds after corona charging, the time constant was considered to be less than the average value of the time constants of the remaining measurement points. Furthermore, if the potential at the start of measurement at all measurement points was approximately 0 V, the time constant was considered to be less than the lower limit of measurement.

[0108] <Method of forming the first region and the second region> When the conductive layer on the conductive substrate has a laminated structure, the conductive layer (outermost layer) that is arranged on the outermost surface side and includes the first region and the second region on the layer (lower layer) that is arranged closest to the substrate among the conductive layers can be prepared, for example, by the following method. First, an outermost layer is formed on a conductive lower layer using materials other than the resin of the first region (conductive layer forming step). Subsequently, an insulating portion is formed on the surface of this conductive layer using the resin of the first region, thereby forming a conductive layer containing the resins of the first region and the second region (insulating portion forming step).

[0109] ·Conductive layer formation process The conductive lower layer may be formed by a known method depending on the material used. The formation of the outermost layer will be described using a urethane resin as an example. As a method for forming the outermost layer on the conductive lower layer, for example, a method of coating a coating liquid prepared by mixing and dispersing a urethane resin, carbon black, a solvent, and additives onto a substrate can be mentioned.

[0110] The solvent used in the coating liquid is selected appropriately within the condition that the urethane resin dissolves (or disperses). A solvent can be selected from the following: ketones such as methyl ethyl ketone and methyl isobutyl ketone; hydrocarbons such as hexane and toluene; alcohols such as methanol and isopropanol; esters; and water. From the viewpoints of resin solubility and boiling point, a particularly preferred solvent is methyl ethyl ketone or methyl isobutyl ketone.

[0111] First area formation process The method for forming the first region that becomes the insulating part is not particularly limited, but the following methods can be used, for example. Specifically, a material (insulating material) (before hardening) such as polycarbonate that constitutes the first region can be applied in dots onto the conductive layer by screen printing or a jet dispenser, and then cured (polymerized) by heating or ultraviolet irradiation as needed. Another example is a method in which the insulating material is applied onto the conductive layer by dipping, spraying, roll coating, or the like, and the insulating material is intentionally repelled by the conductive layer, and then cured by heating or ultraviolet irradiation as needed. In order to repel the material forming the first region on the conductive layer, a solution of the constituent material of the first region is applied (by spraying, dipping, etc.) onto the conductive layer, and, for example, the wettability of the constituent material solutions of the first and second regions, the viscosity of the solutions, the drying speed, and the surface roughness of the conductive layer may be controlled.

[0112] When a second resin is used in addition to polycarbonate, an insulating material (before curing) containing the second resin monomer and polycarbonate can be dissolved in a solvent, applied to the elastic layer by spraying, dipping, roll coating, or other methods, and cured by heating and / or ultraviolet irradiation as needed. Note that a drying operation can also be performed as needed when forming the insulating portion.

[0113] The insulating material may contain the material constituting the first region described above (such as a polycarbonate having a structure represented by general formula (1A) or a second resin), a solvent described later, and, if necessary, additives such as a polymerization initiator. The solid content concentration (dilution concentration) of the insulating material is preferably 0.1 to 50 mass %, more preferably 0.5 to 5 mass %, from the viewpoint of forming the first region on the conductive layer and also exposing the second region on the surface.

[0114] As the polymerization initiator, any known initiator can be used as appropriate, and specifically, the following can be used.

[0115] Examples of the polymerization initiator when polymerizing by heating include peroxides such as 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate, α-cumylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-butylperoxypivalate, t-amylperoxynormaloctoate, t-butylperoxy2-ethylhexylcarbonate, dicumyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, 1,1-di(t-butylperoxy)cyclohexane, and n-butyl-4,4-di(t-butylperoxy)valerate; 2,2-azobisisobutyronitrile, 2, Examples of azo compounds include 2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2-methylbutyronitrile), 1,1-azobis(cyclohexane-1-carbonitrile), 2,2-azobis[2-(2-imidazolin-2-yl)propane], 2,2-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2-azobis(N-butyl-2-methoxypropionamide), and dimethyl-2,2-azobis(isobutyrate).

[0116] Examples of the polymerization initiator when polymerizing by irradiation with ultraviolet light include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methylpropan- 1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0117] Among these, the use of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methylpropan-1-one, which has high surface curing properties, as an initiator is preferred because it facilitates surface curing, increases the crosslink density of the second resin, and further improves durability.

[0118] These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator is preferably 0.5 parts by mass or more and 20 parts by mass or less, based on 100 parts by mass of the total amount of the compounds for forming the second resin (for example, compounds having a (meth)acryloyl group), from the viewpoint of efficiently progressing the reaction.

[0119] It should be noted that known heating devices and ultraviolet irradiation devices can be used as appropriate. Examples of light sources that can be used to irradiate ultraviolet light include LED lamps, high-pressure mercury lamps, metal halide lamps, xenon lamps, and low-pressure mercury lamps. The integrated light intensity required for polymerization can be adjusted as appropriate depending on the type and amount of compound and polymerization initiator used. The solvent used in the coating liquid can be selected as appropriate within the condition that it dissolves the acrylic resin, methacrylic resin, or the like.

[0120] Specific examples of the solvent include the following: ketones such as methyl ethyl ketone and methyl isobutyl ketone; hydrocarbons such as hexane and toluene; alcohols such as methanol and isopropanol; esters; and water. Particularly preferred solvents are low-boiling point solvents such as methyl ethyl ketone, as sufficient drying is required when the composition is subsequently cured using ultraviolet light.

[0121] As a method for controlling the wettability of the surface of the conductive layer, for example, a method of adding a surface conditioner or the like can be used.

[0122] The developing roller of this embodiment can also be applied to a non-contact type developing device and a contact type developing device using a magnetic one-component developer or a non-magnetic one-component developer.

[0123] <Process cartridge> The process cartridge according to this embodiment is characterized by including at least a developing unit, and the developing unit has the developing roller according to this embodiment. Figure 2 is a schematic cross-sectional view of an example of a process cartridge according to one embodiment of the present disclosure. The process cartridge is configured to be detachably mountable to the main body of an electrophotographic image forming apparatus, and includes at least a developing unit.

[0124] The process cartridge 100 shown in Figure 2 is detachably mounted to the main body of the electrophotographic apparatus. The process cartridge 100 is provided with a developing chamber 102 as a developing means having a developing portion, and a toner container 104 that stores toner 103 is disposed at the rear of the developing chamber 102. A transport member 107 for transporting the toner 103 to the developing chamber 102 is disposed in the toner container 104 as needed. An opening that communicates between the developing chamber 102 and the toner container 104 is partitioned by a sealing member 105, and this sealing member 105 is removed when the process cartridge 100 is first used. The developing chamber 102 is also provided with a developing roller 106, a toner supply roller 108, a developing blade 109, and a toner blow-out prevention sheet 110. The developing roller 106 can be the same as that described above.

[0125] Toner 103 is applied to developing roller 106 by toner supply roller 108. Developing roller 106 rotates in the direction indicated by the arrow in the figure, and the toner 103 carried on this developing roller 106 is regulated to a predetermined layer thickness by developing blade 109, and then sent to a developing area facing electrophotographic photosensitive member 101.

[0126] In addition to the above configuration, the process cartridge 100 includes a charging roller 111, a cleaning blade 112, and a waste toner container 119.

[0127] <Electrophotographic image forming apparatus> The electrophotographic image forming apparatus (electrophotographic apparatus) according to this embodiment is equipped with a developing unit, and the developing unit is characterized in that the developing unit has the developing roller according to this embodiment. Figure 3 is a schematic cross-sectional view of an example of the electrophotographic apparatus. This electrophotographic apparatus can be used by mounting the process cartridge 100 shown in Figure 2. The developing unit is the developing chamber 102 described above.

[0128] The printing operation of the electrophotographic device will be described below. The electrophotographic photosensitive member 101 is uniformly charged by a charging roller 111 connected to a bias power supply (not shown). Next, an electrostatic latent image is formed on the surface of the electrophotographic photosensitive member 101 by exposure light 113 for writing the electrostatic latent image. Either LED light or laser light can be used as the exposure light 113.

[0129] Next, negatively charged toner is applied (developed) to the electrostatic latent image by a developing roller 106 built into a process cartridge 100 configured to be detachable from the main body of the electrophotographic apparatus. Next, a toner image is formed on the electrophotographic photosensitive member 101, and the electrostatic latent image is converted into a visible image. At this time, a voltage is applied to the developing roller 106 by a bias power supply (not shown).

[0130] The toner image developed on the electrophotographic photosensitive member 101 is primarily transferred to the intermediate transfer belt 114. A primary transfer member 115 is in contact with the rear surface of the intermediate transfer belt 114, and by applying a voltage to the primary transfer member 115, the negative polarity toner image is primarily transferred from the electrophotographic photosensitive member 101 to the intermediate transfer belt 114. The primary transfer member 115 may be in the form of a roller or a blade.

[0131] 3, a total of four process cartridges 100, one each containing yellow, cyan, magenta, and black toner, are detachably mounted in the main body of the electrophotographic apparatus. The above-mentioned charging, exposure, development, and primary transfer processes are performed sequentially with a predetermined time difference, and a state in which four color toner images are superimposed on the intermediate transfer belt 114 to represent a full-color image is created.

[0132] The toner image on the intermediate transfer belt 114 is conveyed to a position facing a secondary transfer member 116 as the intermediate transfer belt 114 rotates. At this time, a transfer material is conveyed between the intermediate transfer belt 114 and the secondary transfer member 116 along a conveyance route 117 of the recording paper at a predetermined timing. Then, a secondary transfer bias is applied to the secondary transfer member 116, whereby the toner image on the intermediate transfer belt 114 is transferred onto the recording paper.

[0133] The recording paper onto which the toner image has been transferred by the secondary transfer member 116 is transported to a fixing device 118, where the toner image on the recording paper is melted and fixed onto the recording paper, and then the recording paper is discharged outside the electrophotographic device, thereby completing the printing operation. Note that any toner image remaining on the electrophotographic photosensitive member 101 without being transferred from the electrophotographic photosensitive member 101 to the intermediate transfer belt 114 is scraped off by a cleaning blade 112 and stored in a waste toner storage container 119. [Example]

[0134] Examples and comparative examples of the present disclosure are shown below, but the present disclosure is not limited to these.

[0135] <Synthesis of Polycarbonate> Polycarbonate was synthesized as follows. (Polycarbonate Synthesis Example 1) 42.5 g of 2,2-bis(4-hydroxyphenyl)propane (Tokyo Chemical Industry Co., Ltd., product code B0494), 37.5 g of 2,2-bis(3-methyl-4-hydroxyphenyl)propane (Tokyo Chemical Industry Co., Ltd., product code B1567), and 0.1 g of hydrosulfite were dissolved in 1100 ml of a 5% by mass aqueous sodium hydroxide solution. 500 ml of methylene chloride was added to the solution, and while stirring and maintaining the temperature at 15°C, 60 g of phosgene was then blown in over 60 minutes.

[0136] After the phosgene injection was completed, 1.3 g of pt-butylphenol (hereinafter abbreviated as "PTBP": manufactured by Tokyo Chemical Industry Co., Ltd., product code B0383) was added as a molecular weight modifier and stirred to emulsify the reaction solution. After emulsification, 0.4 ml of triethylamine was added, and the mixture was stirred at 23°C for 1 hour to allow polymerization.

[0137] After polymerization was completed, the reaction mixture was separated into an aqueous phase and an organic phase. The organic phase was neutralized with phosphoric acid and repeatedly washed with water until the conductivity of the washings (aqueous phase) reached 10 μS / cm or less. The resulting polymer solution was added dropwise to warm water maintained at 45°C, and the solvent was evaporated to obtain a white powdery precipitate. The resulting precipitate was filtered and dried at 110°C for 24 hours to obtain polycarbonate (PC-1). The molecular weight of this polycarbonate was measured by GPC, which gave a value of Mw = 56,000. The GPC measurement method was as described above.

[0138] Next, the obtained polycarbonate was analyzed by IR and NMR, and it was confirmed that the polycarbonate structure was composed of structural formulas (1) and (4). The IR and NMR analyses were performed as described above.

[0139] [ka]

[0140] (Polycarbonate Synthesis Examples 2 to 17) PC-2 to PC-17 were obtained as shown in Table 2 in the same manner as in Polycarbonate Synthesis Example 1, except that the materials and compounding ratios shown in Table 1 below were used.

[0141] The materials 1 to 5 used in Table 1 are as follows. Material 1: 2,2-bis(4-hydroxyphenyl)propane (corresponding to structural formula (4)) (product name: Tokyo Chemical Industry Co., Ltd., product code B0494) Material 2: 2,2-bis(3-methyl-4-hydroxyphenyl)propane (corresponding to structural formula (1)) (Product name: Tokyo Chemical Industry Co., Ltd., product code B1567) Material 3: 1,1-bis(4-hydroxyphenyl)-1-phenylethane (corresponding to structural formula (3)) (Product name: Tokyo Chemical Industry Co., Ltd., product code M1098) Material 4: 2,2-bis(4-hydroxyphenyl)-4-methylpentane (corresponding to structural formula (2)) (Product name: Tokyo Chemical Industry Co., Ltd., product code D3267) Material 5: 4,4'-dihydroxybiphenyl (corresponding to structural formula (5)) (Product name: Tokyo Chemical Industry Co., Ltd., product code B0464)

[0142] [Table 1] The values ​​for each ingredient are in grams.

[0143] [ka]

[0144] [Table 2] The numbers in Table 2 indicate the molar ratio of each structural formula.

[0145] Example 1 (Formation of the first conductive layer) A conductive substrate was prepared by applying a primer (product name "DY39-012"; manufactured by Dow Corning Toray Co., Ltd.) to a thickness of 10 μm to a 6 mm diameter core bar made of stainless steel (SUS304) and placing it in a hot air vulcanization oven at 150°C for 15 minutes to cure it. This core bar was placed in a mold, and an addition-type silicone rubber composition made by mixing the materials shown in Table 3 below was injected into the cavity formed in the mold.

[0146] [Table 3]

[0147] The mold was then heated to vulcanize and harden the addition-type silicone rubber composition at 130°C for 5 minutes, and the composition was then removed from the mold. After that, it was further heated at 180°C for 1 hour to complete the hardening reaction of the silicone rubber layer, thereby producing an elastic roller having a 3 mm-thick first conductive layer on the outer periphery of the base.

[0148] (Formation of second conductive layer) Next, the materials shown in Table 4 below were mixed, and methyl ethyl ketone was added so that the total solids ratio was 30% by mass, and then the mixture was mixed in a sand mill. The viscosity was then adjusted to 10-12 cps (mPa s) with methyl ethyl ketone to prepare a coating liquid.

[0149] [Table 4]

[0150] This coating liquid was applied to the elastic roller by dipping to a film thickness of 10 μm. In the dipping method, the elastic roller was oriented with its longitudinal direction vertical, and the upper end of the base was gripped and immersed in the coating liquid. The resulting coating was dried at room temperature (23°C) for 30 minutes, and then subjected to a curing reaction in an oven at 150°C for 2 hours to produce a urethane roller having a second conductive layer on the outer peripheral surface of the first conductive layer. The surface of this urethane roller can be the second region.

[0151] (Formation of the first area) Polycarbonate (PC-1) was dispersed in MEK and applied to the outer circumferential surface of the urethane roller, thereby forming a first region on the outer circumferential surface. Specifically, 20 parts by weight of polycarbonate (PC-1) was weighed, MEK was added so that the insulating resin-forming compound for the first region had a concentration of 2% by weight, and the resulting well-dissolved mixture was placed in an overflow circulation coating device. The urethane roller was immersed in the coating device, pulled out, air-dried for 40 minutes, and then heated at 90°C for 1 hour to produce developing roller 1. Note that at this time, the first region was coated on the conductive layer in a repelled state.

[0152] (Confirmation of the first and second areas) As described above, it was confirmed that the first region and the second region were present on the outer surface of the developing roller 1. The area ratios of the first region and the second region to the outer surface area of ​​the resulting developing roller were 30% and 70%, respectively.

[0153] (Analysis of insulating parts) The chemical structure of the insulating part was confirmed by IR and NMR analysis as described above, and it was confirmed that the polycarbonate was composed of structural formulas (1) and (4).

[0154] (Measurement of resistance of insulating parts) The volume resistivity was confirmed as described above and was 2.8 x 10 14 The resistance was Ω·cm.

[0155] (Measurement of resistance of conductive parts) The volume resistivity was confirmed as described above and was 7.2 x 10 6 The resistance was Ω·cm.

[0156] (Time constant of the first region (insulating part)) The time constant was confirmed as described above and was found to be 2958.0 seconds.

[0157] (Time constant of the second region (conductive part)) The time constant was confirmed as described above and was below the lower limit of measurement.

[0158] (Height of the first region (insulation part)) The height of the first region (insulating portion) was confirmed as described above and was 5.5 μm.

[0159] (Image evaluation) First, in order to reduce the torque of the produced developing roller, the gear of the toner supply roller was removed from a commercially available process cartridge, Toner Cartridge 318 (cyan) (manufactured by Canon Inc.) By removing the gear, the torque of the toner supply roller relative to the developing roller becomes low, and the amount of toner scraped off from the developing roller is reduced. Next, the prepared developing roller 1 was incorporated into the process cartridge, and the process cartridge was loaded into a commercially available laser printer, LBP-7600C (manufactured by Canon Inc.) This laser beam printer was left for 24 hours in an environment of a temperature of 23°C and a relative humidity of 50%.

[0160] Next, under the same environment, one full-surface solid image was output, and then 20,000 images with a print rate of 0.2% were output 25 times, and one full-surface solid image was output (normal). Furthermore, the electrophotographic image forming apparatus was modified so that it could output A4 size paper at a speed of 50 sheets per minute, and after outputting one full-page solid image under the same environment, the output of 20,000 images with a printing rate of 0.2% was repeated 25 times, and one full-page solid image was output (50 sheets per minute).

[0161] The image density of all 26 full-area solid images obtained under both the (normal) and (50 sheets / min) conditions was then measured using a spectrodensitometer: X-Rite504 (trade name, S-DG Corporation). The image density was calculated as the average of 15 measurements per full-area solid image. Image densities were compared based on the number of prints and evaluated based on the following evaluation criteria 1 and 2. Evaluation criteria 1 was used to evaluate images printed under normal conditions. The results are shown in Tables 6-1 and 6-2. Hereinafter, the image density of the first printed solid image will be referred to as the "first image density," and the image density of the solid image printed in the Xth process will be referred to as the "Xth image density."

[0162] (Evaluation Criteria 1) S: The difference between the image density of the first sheet and the image density of the 20th sheet is less than 0.1, and the difference between the image density of the first sheet and the image density of the 26th sheet is less than 0.1. A: The difference in image density between the first sheet and the 20th sheet is less than 0.1, and the difference in image density between the first sheet and the 26th sheet is 0.1 or more. B: The difference between the image density of the first sheet and the image density of the 20th sheet is 0.1 or more and less than 0.2, and the difference between the image density of the first sheet and the image density of the 26th sheet is less than 0.2. C: The difference between the image density of the first sheet and the image density of the 20th sheet is 0.1 or more and less than 0.2, and the difference between the image density of the first sheet and the image density of the 26th sheet is 0.2 or more. D: The difference between the image density of the first sheet and the image density of the 20th sheet is 0.2 or more and less than 0.3. E: The difference between the image density of the first sheet and the image density of the 20th sheet is 0.3 or more.

[0163] (Evaluation Criteria 2) S: The difference in image density between the 20th sheet under normal conditions and the 20th sheet when printed at a speed of 50 sheets per minute is less than 0.1, and the difference in image density between the 26th sheet under normal conditions and the 26th sheet when printed at a speed of 50 sheets per minute is less than 0.1. A: The difference in image density between the 20th sheet under normal conditions and the 20th sheet when printed at a speed of 50 sheets per minute is less than 0.1, and the difference in image density between the 26th sheet under normal conditions and the 26th sheet when printed at a speed of 50 sheets per minute is 0.1 or more. B: The difference between the image density of the 20th sheet under normal conditions and the image density of the 20th sheet when output at a speed of 50 sheets / minute is 0.1 or more and less than 0.2, and the difference between the image density of the 26th sheet under normal conditions and the image density of the 26th sheet when output at a speed of 50 sheets / minute is 0.1 or more and less than 0.2. The difference in image density between the 26th sheet and the previous one is less than 0.2. C: The difference between the image density of the 20th sheet under normal conditions and the image density of the 20th sheet when printed at a speed of 50 sheets per minute is 0.1 or more but less than 0.2, and the difference between the image density of the 26th sheet under normal conditions and the image density of the 26th sheet when printed at a speed of 50 sheets per minute is 0.2 or more. D: The difference between the image density on the 20th sheet under normal conditions and the image density on the 20th sheet when output at a speed of 50 sheets per minute is 0.2 or more and less than 0.3. E: The difference between the image density on the 20th sheet under normal conditions and the image density on the 20th sheet when output at a speed of 50 sheets per minute is 0.3 or more.

[0164] <Examples 2 to 33 and Comparative Examples 1 and 2> Developing rollers 2 to 35 of Examples 2 to 33 and Comparative Examples 1 and 2 were produced in the same manner as in Example 1, except that the materials and amounts used for the insulating resin-forming compound that forms the first region were changed as shown in Table 5 below. The resulting developing rollers 2 to 35 were evaluated in the same manner as in Example 1. The results are shown in Tables 6-1 and 6-2. However, in the following examples, the molecular weight regulator PTBP was added as follows: 1.0 g in Example 30, and 1.2 g in Example 31. In addition, in Examples 5 to 8, 11, 12, 14, 16, 19, 21, 23, 25, and 29 and Comparative Example 1, the insulating portion was formed as follows.

[0165] Specifically, each material (parts by mass) shown in Table 5 was weighed, MEK was added so that the insulating resin-forming compound forming the first region had a concentration of 2% by mass, and the well-dissolved mixture was placed in an overflow circulation coating device. The urethane roller was immersed in the coating device and then removed. After that, it was air-dried for 40 minutes and then heated at 90°C for 1 hour. Note that during this process, the component forming the first region was repelled onto the conductive layer when applied. After that, the outer surface of the urethane roller to which this mixture was attached was exposed to an integrated light dose of 2000 mJ / cm 2 The component forming the first region was cured by irradiating it with ultraviolet light so that the first region was formed. In this way, the developing roller according to this example was produced. Note that a high-pressure mercury lamp (product name: handy type UV curing device, manufactured by Mario Network Co., Ltd.) was used as the ultraviolet irradiating device.

[0166] In Examples 1 to 33, the first regions and the second regions were disposed adjacent to each other, and the first regions were scattered. Comparative Examples 1 and 2 are examples that do not have the structure represented by general formula (1A).

[0167] [Table 5] The acrylic compounds and polymerization initiators used were as follows: Acrylic compounds: PO-modified neopentyl glycol diacrylate (Product name: EBECRYL145, manufactured by Daicel Allnex Co., Ltd.) Polymerization initiator: 1-Hydroxycyclohexyl phenyl ketone (Product name: IRAGACURE184, manufactured by BASF)

[0168] [Table 6-1]

[0169] [Table 6-2]

[0170] In the table, the insulating portion indicates the first region and the conductive portion indicates the second region. The occupancy rate of the insulating part indicates the ratio (occupancy rate RE) of the total area of ​​the first region to the area of ​​a square observation area with each side of 900 μm placed on the outer surface of the developing roller so that the axial direction of the developing roller and one side of the observation area are parallel. The height of the insulating portion indicates the average height HD of each of the first regions from the contact portion with the second region.

[0171] As shown in Tables 6-1 and 6-2, by using the developing rollers according to Examples 1 to 33, it was found that it was possible to reduce the drive torque between the toner supply roller and the developing roller and to suppress a decrease in density of an electrophotographic image over a long period of time, even when the process speed was increased. On the other hand, Comparative Examples 1 and 2 resulted in a large change in image density.

[0172] The present disclosure relates to the following configurations. (Configuration 1) 1. A developer roller having a substrate having an electrically conductive surface and a conductive layer on the surface of the substrate, the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region, the first region and the second region are disposed adjacent to each other; the first region comprises at least one polycarbonate; The at least one polycarbonate has a structure represented by the following general formula (1A): A developing roller characterized by: TIFF2025161772000016.tif43153 In general formula (1A), R1 to R8 each independently represent a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R9 and R 10are each independently a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms, or R9 and R 10 is R9 and R 10 are a group of atoms necessary to bond with each other to form an alicyclic structure having 6 to 12 carbon atoms, However, (1A) satisfies at least one condition selected from the group consisting of the following conditions 1 and 2: ·Condition 1 At least one selected from the group consisting of R1 to R8 is the alkyl group having 1 to 9 carbon atoms or the aryl group having 6 to 10 carbon atoms. ·Condition 2 R9 and R 10 At least one selected from the group consisting of is a linear or branched alkyl group having 2 or more carbon atoms, or an aryl group having 6 to 10 carbon atoms. (Configuration 2) In the general formula (1A), at least one of R1 and R3 is an alkyl group having 1 to 9 carbon atoms or an aryl group having 6 to 10 carbon atoms, and at least one of R6 and R8 is 2. The developing roller according to claim 1, wherein the alkyl group has 1 to 9 carbon atoms or the aryl group has 6 to 10 carbon atoms, and the remainder is a hydrogen atom. (Configuration 3) The developing roller according to configuration 1 or 2, wherein the at least one polycarbonate has at least one structure selected from the group consisting of a structure represented by the following structural formula (2) and a structure represented by the following structural formula (3): TIFF2025161772000017.tif117153 (Configuration 4) the at least one polycarbonate comprises a first polycarbonate and a second polycarbonate having different structures; The first polycarbonate has a structure represented by the following structural formula (1): The developing roller according to any one of configurations 1 to 3, wherein the second polycarbonate has at least one structure selected from the group consisting of a structure represented by the following structural formula (2) and a structure represented by the following structural formula (3): TIFF2025161772000018.tif167153(Configuration 5) The developing roller according to Configuration 4, wherein the first polycarbonate further has a structure represented by the following structural formula (4): TIFF2025161772000019.tif46153 (Configuration 6) The developing roller according to Configuration 4 or 5, wherein the second polycarbonate further has a structure represented by the following structural formula (4): TIFF2025161772000020.tif46153 (Configuration 7) 7. The developing roller according to any one of configurations 1 to 6, wherein the content of the structure represented by general formula (1A) in the at least one polycarbonate is 20 to 100 mol % based on all structural units in the polycarbonate. (Configuration 8) 8. The developing roller according to any one of configurations 1 to 7, wherein the content of the structure represented by general formula (1A) is 30 to 100 mol % based on the total resin in the first region. (Configuration 9) The volume resistivity of the second region is 1.0×10 5 ~1.0×10 11 9. The developing roller according to any one of configurations 1 to 8, which has a resistivity of Ω·cm or less. (Configuration 10) The volume resistivity of the first region is 1.0×10 13 ~1.0×10 18 10. The developing roller according to any one of configurations 1 to 9, wherein the resistivity is Ω·cm. (Configuration 11) 11. The developing roller according to any one of configurations 1 to 10, wherein a potential decay time constant, defined as the time required for the potential of the surface of the first region to decay to V0×(1 / e)(V) when the surface potential of the first region is charged to V0 (V), is 60.0 seconds or longer. (Configuration 12) 12. The developing roller according to any one of configurations 1 to 11, wherein a potential decay time constant, defined as the time required for the potential of the surface of the second region to decay to V0×(1 / e)(V) when the surface potential of the second region is charged to V0 (V), is less than 6.0 seconds. (Configuration 13) 13. The developing roller according to any one of configurations 1 to 12, wherein when a square observation area with a side of 900 μm is placed on the outer surface of the developing roller so that one side of the observation area is parallel to the axial direction of the developing roller, the proportion of the total area of ​​the first area to the area of ​​the square area is 10 to 60 area %. (Configuration 14) 14. The developing roller according to any one of configurations 1 to 13, wherein the first region further contains an acrylic resin. (Configuration 15) A process cartridge configured to be detachably mounted in a main body of an electrophotographic image forming apparatus, The process cartridge includes at least a developing means, 15. A process cartridge, wherein the developing means comprises the developing roller according to any one of configurations 1 to 14. (Configuration 16) An electrophotographic image forming apparatus, the electrophotographic image forming apparatus comprises a developing means, 15. An electrophotographic image forming apparatus, wherein the developing means comprises the developing roller according to any one of Configurations 1 to 14. [Explanation of symbols]

[0173] 1 developing roller, 2 mandrel, 3 conductive layer, 4 first region, 5 second region

Claims

1. 1. A developer roller having a substrate having an electrically conductive surface and a conductive layer on the surface of the substrate, the outer surface of the developing roller is composed of at least a first region and a second region having a higher conductivity than the first region; the first region and the second region are disposed adjacent to each other; the first region comprises at least one polycarbonate; The at least one polycarbonate has a structure represented by the following general formula (1A): A developing roller characterized by: In general formula (1A), R １ ~R ８ are each independently a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms, R ９ and R １０ are each independently a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms, or R ９ and R １０ is R ９ and R １０ are a group of atoms necessary to bond together to form an alicyclic structure having 6 to 12 carbon atoms, However, (1A) satisfies at least one condition selected from the group consisting of the following conditions 1 and 2: ・Condition 1 R １ ~R ８ At least one selected from the group consisting of: is an alkyl group having 1 to 9 carbon atoms or an aryl group having 6 to 10 carbon atoms. ・Condition 2 R ９ and R １０ At least one selected from the group consisting of: is a linear or branched alkyl group having 2 or more carbon atoms, or an aryl group having 6 to 10 carbon atoms.

2. In the general formula (1A), R １ and R ３ At least one of R is an alkyl group having 1 to 9 carbon atoms or an aryl group having 6 to 10 carbon atoms, and ６ and R ８ 2. The developing roller according to claim 1, wherein at least one of the groups is an alkyl group having 1 to 9 carbon atoms or an aryl group having 6 to 10 carbon atoms, and the remainder are hydrogen atoms.

3. 2. The developing roller according to claim 1, wherein the at least one polycarbonate has at least one structure selected from the group consisting of a structure represented by the following structural formula (2) and a structure represented by the following structural formula (3):

4. the at least one polycarbonate comprises a first polycarbonate and a second polycarbonate having different structures; The first polycarbonate has a structure represented by the following structural formula (1):

2. The developing roller according to claim 1, wherein the second polycarbonate has at least one structure selected from the group consisting of a structure represented by the following structural formula (2) and a structure represented by the following structural formula (3).

5. 5. The developing roller according to claim 4, wherein the first polycarbonate further has a structure represented by the following structural formula (4):

6. 5. The developing roller according to claim 4, wherein the second polycarbonate further has a structure represented by the following structural formula (4):

7. 2. The developing roller according to claim 1, wherein the content of the structure represented by general formula (1A) in the at least one polycarbonate is 20 to 100 mol % based on all structural units in the polycarbonate.

8. 2. The developing roller according to claim 1, wherein the content of the structure represented by general formula (1A) is 30 to 100 mol % based on the total resin in the first region.

9. The volume resistivity of the second region is 1.0×10 ５ ~1.0 x 10 １１ 2. The developing roller according to claim 1, wherein the developing roller has a surface roughness of Ω·cm or less.

10. The volume resistivity of the first region is 1.0×10 １３ ~1.0 x 10 １８ 2. The developer roller of claim 1, wherein the developer roller has a surface area of ​​Ω·cm.

11. The potential of the surface of the first region is V ０ When the surface is charged to (V), the potential of the surface is V ０ 2. The developing roller according to claim 1, wherein a potential decay time constant, defined as the time required for decay to 1 / (V)×(1 / e)(V), is 60.0 seconds or more.

12. The potential of the surface of the second region is V ０ When the surface is charged to (V), the potential of the surface is V ０ 2. The developing roller according to claim 1, wherein the potential decay time constant, defined as the time required for decay to .times.(1 / e)(V), is less than 6.0 seconds.

13. 2. The developing roller according to claim 1, wherein when a square observation area with a side of 900 μm is placed on the outer surface of the developing roller so that one side of the observation area is parallel to the axial direction of the developing roller, the proportion of the total area of ​​the first area to the area of ​​the square area is 10 to 60 area %.

14. The developer roller of claim 1 , wherein the first region further comprises an acrylic resin.

15. A process cartridge configured to be detachably mounted in a main body of an electrophotographic image forming apparatus, The process cartridge includes at least a developing means, A process cartridge, wherein the developing means comprises the developing roller according to any one of claims 1 to 14.

16. An electrophotographic image forming apparatus, the electrophotographic image forming apparatus comprises a developing means, 15. An electrophotographic image forming apparatus, wherein the developing means comprises the developing roller according to claim 1.

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