Conductive member, electrifying device, process cartridge, and image forming apparatus

Abstract

To provide a conductive member that is excellent in color streak generation prevention properties.SOLUTION: A conductive member has a particulate conductive part having an area ratio of 15 area% or more, which is measured when a conductive point on its surface is measured using a current simultaneous measurement atomic force microscope. The conductive member has the particulate conductive part having an average area of 0.05 μm2 or more, which is measured when the conductive point on its surface is measured using the current simultaneous measurement atomic force microscope.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a conductive member, a charging device, a process cartridge, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 describes a conductive member having a substrate, an elastic layer disposed on the substrate, and a surface layer disposed on the elastic layer, the surface layer having a sea-island structure consisting of a sea portion containing a first resin and island portions containing a second resin, and the surface layer containing carbon black at least inside the island portions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-022410 Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to provide a method for determining whether the area ratio of particulate conductive portions measured when conductive points on a surface are measured by a current simultaneous measurement atomic force microscope is less than 15 area %, or whether the average area of ​​particulate conductive portions measured when conductive points on a surface are measured by a current simultaneous measurement atomic force microscope is less than 0.05 μm 2 The object of the present invention is to provide a conductive member that is excellent in suppressing the occurrence of color streaks, compared to when the thickness is less than 100 μm. [Means for solving the problem]

[0005] Specific means for solving the above problems include the following aspects. <1> A conductive material in which the area ratio of particulate conductive parts measured when measuring conductive points on the surface using a current simultaneous measurement atomic force microscope is 15 area % or more. <2> The average area of ​​the particulate conductive parts measured when measuring conductive points on the surface using an atomic force microscope with simultaneous current measurement is 0.05 μm 2 The conductive member is as described above. <3> The area ratio of the conductive portion is 15 area % or more and 80 area % or less. <1> The conductive member according to claim 1. <4> The area ratio of the conductive portion is 30% by area or more and 60% by area or less. <3> The conductive member according to claim 1. <5> The average area of ​​the conductive portion is 0.05 μm 2 1.0μm or more 2 is <1> or <2> The conductive member according to claim 1. <6> The average area of ​​the conductive portion is 0.20 μm 2 More than 0.50μm 2 is <5> The conductive member according to claim 1. <7> When a 100 nm diameter probe is applied with -30 V and moved while measuring the current value, a 50 μm square area is divided into a 256 × 256 grid, and the area in which the current value in each division is 60 pA or more accounts for 60% or more of the area. <1> ~ <6> 10. The conductive member according to claim 9, wherein the conductive member is a conductive material. <8> The device comprises a substrate, an elastic layer provided on the substrate, and a surface layer provided on the elastic layer. <1> ~ <7> 10. The conductive member according to claim 9, wherein the conductive member is a conductive material. <9> The surface layer includes a first resin, a second resin, and a conductive agent. <8> The conductive member according to claim 1. <10> The surface layer has a sea-island structure consisting of a sea portion containing the first resin and an island portion containing the second resin. <9> The conductive member according to claim 1. <11> <1> ~ <10> 10. A charging device comprising the conductive member according to any one of the above items. <12> <11> A process cartridge equipped with the charging device according to claim 1, which is detachably mounted on an image forming apparatus. <13> an image carrier and charging the surface of the image carrier; <11> an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the image carrier; a developing device that develops the electrostatic latent image formed on the surface of the image carrier with a developer containing toner to form a toner image; and a transfer device that transfers the toner image to the surface of a recording medium. [Effects of the Invention]

[0006] <1> or <8> According to the present invention, a conductive member is provided that is superior in suppressing the occurrence of color streaks compared to a conductive member in which the area ratio of particulate conductive portions measured when measuring conductive points on the surface using a current simultaneous measurement atomic force microscope is less than 15 area %. <2> According to the invention, the average area of ​​the particulate conductive portions measured when measuring conductive points on the surface using a current simultaneous measurement atomic force microscope is 0.05 μm 2 In this case, a conductive member having excellent suppression of color streaks can be provided, as compared with a case where the thickness is less than 100 μm. <3> According to the invention, a conductive member is provided that is more excellent in suppressing the occurrence of color streaks than when the area ratio of the conductive portion is less than 15 area % or more than 80 area %. <4> According to the invention, a conductive member is provided that is more excellent in suppressing the occurrence of color streaks than when the area ratio of the conductive portion is less than 30 area % or more than 60 area %. <5> According to the invention, the average area of ​​the conductive portion is 0.05 μm 2 Less than or 1.0 μm 2 In this case, a conductive member having superior color streak suppression properties is provided compared to when the thickness is greater than 100 μm. <6> According to the invention, the average area of ​​the conductive portion is 0.20 μm 2 Less than or 0.50 μm 2 In this case, a conductive member having superior color streak suppression properties is provided compared to when the thickness is greater than 100 μm. <7> According to the invention, when a voltage of -30 V is applied to a probe having a diameter of 100 nm on the surface and the current value is measured while the probe is moved, a conductive member is provided which is superior in suppressing the occurrence of color streaks compared to a case where a 50 μm square area is divided into a 256 × 256 grid and the area in which a current value of 60 pA or more flows in each divided area accounts for less than 60 area%. <9> or <10> According to the invention, a conductive member is provided which is more excellent in suppressing the occurrence of color streaks than when the surface layer contains only one type of resin. <11> , <12> or <13> According to the invention, the conductive member provided has an area ratio of particulate conductive portions measured when conductive points on the surface are measured by a current simultaneous measurement atomic force microscope, which is less than 15 area %, or an average area of ​​particulate conductive portions measured when conductive points on the surface are measured by a current simultaneous measurement atomic force microscope, which is less than 0.05 μm 2 Therefore, a charging device, a process cartridge, or an image forming apparatus that is superior in suppressing the occurrence of color streaks compared to when the charging device, the process cartridge, or the image forming apparatus is provided. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a schematic perspective view illustrating an example of a conductive member according to the present embodiment. [Figure 2] 2 is a schematic cross-sectional view showing an example of the conductive member according to the present embodiment, taken along the line AA in FIG. 1. [Figure 3] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described. These descriptions and examples are intended to illustrate the embodiment and are not intended to limit the scope of the invention. In the present specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range. In addition, in the present specification, the upper or lower limit of a numerical range may be replaced with a value shown in the examples.

[0009] Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0010] (Conductive material) In a first embodiment of the conductive member according to this embodiment, the area ratio of particulate conductive portions measured when conductive points on the surface are measured using a current simultaneous measurement atomic force microscope is 15 area % or more. In a second embodiment of the conductive member according to the present invention, the average area of ​​the particulate conductive portions measured when the conductive points on the surface are measured by a current simultaneous measurement atomic force microscope is 0.05 μm 2 That's all.

[0011] In this specification, unless otherwise specified, simply referring to the "conductive member according to this embodiment" refers to both the first embodiment and the second embodiment. Furthermore, unless otherwise specified, simply referring to a "conductive portion," a "surface layer," etc. refers to the conductive portion, the surface layer, etc. of both the first embodiment and the second embodiment.

[0012] The conductive member according to this embodiment can be suitably used as a charging member.

[0013] Conventional conductive members have had problems in that the particulate conductive portions are not sufficiently formed on the surface, resulting in charging defects and color streaks. In the conductive member according to this embodiment, the area ratio of the particulate conductive portions measured when the conductive points on the surface are measured by a current simultaneous measurement atomic force microscope is 15 area % or more, or the average area of ​​the particulate conductive portions measured when the conductive points on the surface are measured by a current simultaneous measurement atomic force microscope is 0.05 μm 2 It is presumed that, due to the above, there are many areas on the surface with low resistance, and the surface is sufficiently charged, thereby suppressing the occurrence of color streaks.

[0014] The conductive member according to this embodiment will be described in detail below.

[0015] <Area ratio and average area of ​​particulate conductive parts> In a first embodiment of the conductive member according to this embodiment, the area ratio of the particulate conductive portions measured when measuring conductive points on the surface using a current-simultaneous atomic force microscope (C-AFM, Conductive Atomic Force Microscopy) is 15 area % or more, and from the viewpoints of suppressing the occurrence of color streaks and achieving low resistance, the area ratio is preferably 15 area % or more and 80 area % or less, more preferably 20 area % or more and 70 area % or less, even more preferably 30 area % or more and 60 area % or less, and particularly preferably 30 area % or more and 50 area % or less. In a second embodiment of the conductive member according to this embodiment, the area ratio of the particulate conductive portions measured when measuring conductive points on the surface by C-AFM is preferably 15 area% or more, more preferably 15 area% or more and 80 area% or less, even more preferably 20 area% or more and 70 area% or less, particularly preferably 30 area% or more and 60 area% or less, and most preferably 30 area% or more and 50 area% or less, from the viewpoints of suppressing the occurrence of color streaks and low resistance.

[0016] In a second embodiment of the conductive member according to the present invention, the average area of ​​the particulate conductive portions measured when measuring conductive points on the surface by C-AFM is 0.05 μm 2From the viewpoint of suppressing color streaks and low resistance, 0.05 μm 2 1.0μm or more 2 Preferably, it is 0.10 μm or less. 2 More than 0.80μm 2 More preferably, it is 0.20 μm or less. 2 More than 0.50μm 2 More preferably, it is 0.30 μm or less. 2 More than 0.40μm 2 It is particularly preferred that: In a first embodiment of the conductive member according to the present embodiment, the average area of ​​the particulate conductive portions measured when measuring conductive points on the surface by C-AFM is 0.05 μm from the viewpoints of suppressing the occurrence of color streaks and low resistance. 2 It is preferable that the thickness is 0.05 μm or more. 2 1.0μm or more 2 More preferably, it is 0.10 μm or less. 2 More than 0.80μm 2 More preferably, it is 0.20 μm or less. 2 More than 0.50μm 2 It is particularly preferable that the value is equal to or less than 0.30 μm. 2 More than 0.40μm 2 Most preferably, the following:

[0017] In this embodiment, the method for measuring conductive points on the surface of a conductive member using a current-simultaneous atomic force microscope (C-AFM) is as follows. The isoelectric point of the surface of the conductive material is measured under the following conditions using a Hitachi High-Tech AFM5200S (simultaneous AFM / current measurement) and an S-image CL scanner (110 μm). The area of ​​60 pA or more is considered to be the conductive area, and the area ratio and average area of ​​the conductive area measured in particulate form are calculated. Probe holder: Multi-holder Cantilever: SI-DF20-R (100 nm) Bias voltage: -10V Measurement range: 50 μm x 50 μm Number of data X:512 Y:512

[0018] <Area ratio of the region where the current value is 60 pA or more> In the conductive member according to this embodiment, when a current value is measured while a probe having a diameter of 100 nm is applied with -30 V and moved, a 50 μm square (= 50 μm × 50 μm) area is divided into a 256 × 256 grid on the surface, and from the viewpoint of suppressing the occurrence of color streaks, the area in which a current value of 60 pA or more flows in each divided area preferably accounts for 60 area% or more, more preferably 60 area% to 90 area%, even more preferably 60 area% to 80 area%, and particularly preferably 65 area% to 75 area%. Furthermore, in the conductive member according to this embodiment, from the viewpoint of suppressing the occurrence of color streaks, the area in which the current value flowing through one section is 60 pA or more and 100 pA or less preferably accounts for 60 area% or more, more preferably 60 area% or more and 90 area% or less, even more preferably 60 area% or more and 80 area% or less, and particularly preferably 65 area% or more and 75 area% or less.

[0019] In this embodiment, the method for measuring the area on the surface of the conductive member where the current value is 60 pA or more is as follows. On the surface of the obtained conductive member, the current simultaneous measurement atomic force microscope is used to apply -30 V to a 100 nm diameter probe (cantilever) and move it while dividing a 50 μm square area into a 256 × 256 grid, and the current value flowing in each grid is measured. Other measurement conditions are the same as those for the conductive point measurement method described above.

[0020] From the viewpoints of chargeability and ease of fabrication, the conductive member according to this embodiment preferably comprises a substrate, an elastic layer provided on the substrate, and a surface layer provided on the elastic layer. Moreover, from the viewpoint of ease of forming the particulate conductive portion, the surface layer in the conductive member according to this embodiment preferably contains a first resin, a second resin, and a conductive agent. Furthermore, from the viewpoint of ease of forming particulate conductive portions, it is more preferable that the surface layer in the conductive member according to this embodiment has a sea-island structure consisting of a sea portion comprising the first resin and an island portion comprising the second resin.

[0021] Fig. 1 is a schematic perspective view showing an example of a conductive member according to the present embodiment, Fig. 2 is a schematic cross-sectional view of an example of a conductive member according to the present embodiment, and Fig. 2 is a cross-sectional view taken along line AA in Fig. 1.

[0022] As shown in Figures 1 and 2, the conductive member 121A of this embodiment is a roll-shaped member having, for example, a shaft 30 (an example of a substrate), an elastic layer 31 arranged on the outer peripheral surface of the shaft 30, and a surface layer 32 arranged on the outer peripheral surface of the elastic layer 31.

[0023] Hereinafter, each component of the conductive member according to this embodiment will be described in detail, although the reference numerals attached to each component may be omitted.

[0024] <Base material> The conductive member according to this embodiment preferably includes a substrate. The substrate is preferably a conductive cylindrical or columnar member. Here, the conductive property means a material having a volume resistivity of 10 13 It means less than Ω·cm.

[0025] Examples of materials for the substrate include metals such as iron (free-cutting steel, etc.), copper, brass, stainless steel, aluminum, nickel, etc. Examples of the substrate include members whose outer periphery is plated (for example, resin or ceramic members), members in which a conductive agent is dispersed (for example, resin or ceramic members), etc.

[0026] <Elastic layer> The conductive member according to this embodiment preferably includes an elastic layer provided on the substrate. The elastic layer preferably contains, for example, an elastic material and a conductive agent, and may further contain other additives.

[0027] Examples of elastic materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluororubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene-propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and blends thereof. Among these, polyurethane, silicone rubber, EPDM, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, NBR, and blends thereof are preferred. These elastic materials may be foamed or unfoamed.

[0028] Examples of conductive agents include electronic conductive agents and ionic conductive agents. Examples of electronic conductive agents include powders of carbon black such as ketjen black and acetylene black; pyrolytic carbon, graphite; conductive metals or alloys such as aluminum, copper, nickel, and stainless steel; conductive metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, and tin oxide-indium oxide solid solution; and insulating materials whose surfaces have been treated to be conductive. Examples of ionic conductive agents include perchlorates or chlorates of oniums such as tetraethylammonium and lauryltrimethylammonium; and perchlorates or chlorates of alkali metals or alkaline earth metals such as lithium and magnesium. One type of conductive agent may be used alone, or two or more types may be used in combination.

[0029] Specific examples of carbon black include Orion Engineered Carbons' "Special Black 350," "Special Black 100," "Special Black 250," "Special Black 5," "Special Black 4," "Special Black 4A," "Special Black 550," "Special Black 6," "Color Black FW200," "Color Black FW2," and "Color Black FW2V," as well as Cabot's "MONARCH 880," "MONARCH 1000," "MONARCH 1300," "MONARCH 1400," "MOGUL-L," and "REGAL 400R."

[0030] The amount of the conductive agent is not particularly limited, but in the case of an electronic conductive agent, it is preferably in the range of 1 to 30 parts by mass, and more preferably 15 to 25 parts by mass, per 100 parts by mass of the elastic material. In the case of an ionic conductive agent, it is preferably in the range of 0.1 to 5.0 parts by mass, and more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of the elastic material.

[0031] Other additives that may be incorporated into the elastic layer include, for example, conventional materials that may be incorporated into elastic layers, such as softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, antioxidants, surfactants, coupling agents, and fillers (silica, calcium carbonate, etc.).

[0032] The thickness of the elastic layer is preferably about 1 mm or more and 15 mm or less on average, and more preferably about 2 mm or more and 10 mm or less. The volume resistivity of the elastic layer is 10 3 Ω cm or more 10 14 Ω·cm or less is preferable.

[0033] <Surface layer> The conductive member according to this embodiment preferably includes a surface layer, and more preferably includes a surface layer provided on the elastic layer.

[0034] -Composition of the surface layer- From the viewpoint of ease of forming the particulate conductive portions, the surface layer preferably contains a first resin, a second resin, and a conductive agent, and more preferably has a sea-island structure consisting of a sea portion containing the first resin and an island portion containing the second resin, and contains a conductive agent. Here, the term "sea-island structure" refers to a structure in which at least two types of resins are mixed in an incompatible state, and islands, which are a dispersed phase, are contained in a sea, which is a continuous phase.

[0035] The sea-island structure is formed by adjusting the difference in solubility parameter (SP value) between the first resin and the second resin and the mixing ratio of the first resin and the second resin. From the viewpoint of facilitating the formation of the sea-island structure, the difference in SP value between the first resin and the second resin is preferably 2 or more and 10 or less. The mixing ratio of the first resin and the second resin will be described later.

[0036] The method for calculating the solubility parameter (SP value) is the method described in "Polymer Handbook, 4th Edition, John Wiley & Sons," VII680-683. The solubility parameters of major resins are described in VII702-711 of the above document.

[0037] Examples of the first resin include acrylic resin, cellulose resin, polyamide resin, copolymer nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, styrene-butadiene resin, melamine resin, epoxy resin, urethane resin, silicone resin, fluororesin (e.g., tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride, etc.), urea resin, etc. Copolymer nylon is a copolymer containing one or more of nylon 610, nylon 11, and nylon 12 as polymerization units, and may also contain nylon 6, nylon 66, etc. as other polymerization units. The elastic material blended in the elastic layer may be used as the first resin. As the first resin, one type of resin may be used alone, or two or more types of resins may be used in combination.

[0038] The first resin is preferably a polyamide resin (e.g., nylon), and more preferably a methoxymethylated polyamide resin (e.g., methoxymethylated nylon), from the viewpoints of the electrical properties of the surface layer or resistance to contamination; the appropriate hardness or maintainability of the surface layer since the surface layer is formed on the elastic layer; and the dispersibility or coating film formability of the conductive agent when the surface layer is formed using a dispersion liquid.

[0039] Examples of the second resin include polyvinyl butyral resin, polystyrene resin, polyvinyl alcohol, etc. As the second resin, one type of resin may be used alone, or two or more types of resins may be used in combination.

[0040] The second resin is preferably a polyvinyl butyral resin from the viewpoints of the electrical properties or resistance to contamination of the surface layer; the appropriate hardness or maintainability of the surface layer since the surface layer is formed on the elastic layer; the dispersibility or coating film formability of the conductive agent when the surface layer is formed using a dispersion liquid; and the like.

[0041] The content of the second resin is preferably 10 parts by mass or more and 30 parts by mass or less, more preferably 12 parts by mass or more and 28 parts by mass or less, and even more preferably 15 parts by mass or more and 25 parts by mass or less, relative to 100 parts by mass of the total of the first resin and the second resin.

[0042] By setting the content of the second resin to 10 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the total of the first resin and the second resin, a conductive member can be obtained that further suppresses the occurrence of color streaks in the axial direction when an image is formed. The reason for this is presumed to be as follows. By setting the content of the second resin to 10 parts by mass or more relative to 100 parts by mass of the total of the first resin and the second resin, the occupancy rate of the island portions in the surface layer is increased, thereby further increasing the number of conductive paths in the surface layer. Furthermore, by setting the content of the second resin to 30 parts by mass or more relative to 100 parts by mass of the total of the first resin and the second resin, the occupancy rate of the island portions in the surface layer is not too high, and the island portions tend to be dispersed and present in a nearly uniform manner throughout the surface layer.

[0043] The total content of the first resin and the second resin is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 90% by mass or less, and even more preferably 70% by mass or more and 85% by mass or less, based on the entire surface layer.

[0044] Examples of conductive agents include electronic conductive agents and ionic conductive agents. Examples of electronic conductive agents include powders of carbon black such as ketjen black and acetylene black; pyrolytic carbon, graphite; conductive metals or alloys such as aluminum, copper, nickel, and stainless steel; conductive metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, and tin oxide-indium oxide solid solution; and insulating materials whose surfaces have been treated to be conductive. Examples of ionic conductive agents include perchlorates or chlorates of oniums such as tetraethylammonium and lauryltrimethylammonium; and perchlorates or chlorates of alkali metals or alkaline earth metals such as lithium and magnesium. One type of conductive agent may be used alone, or two or more types may be used in combination.

[0045] As the conductive agent, carbon black is preferred. By using carbon black as a conductive agent, it becomes easier to obtain a conductive member that suppresses the occurrence of color streaks in the axial direction when an image is formed. The reason for this is presumed to be as follows. Compared with conductive agents other than carbon black, carbon black tends to be more unevenly distributed near the island regions of the surface layer. Therefore, by setting the island area occupancy rate to 10% or more and 45% or by setting the island diameter to 100 nm or more and 750 nm or less, the effect of increasing the conductive paths in the surface layer is further enhanced. From the above, it is presumed that the use of carbon black as a conductive agent makes it easier to obtain a conductive member that suppresses the occurrence of color streaks in the axial direction when an image is formed.

[0046] Examples of carbon black include ketjen black, acetylene black, and oxidation-treated carbon black with a pH of 5 or less. More specific examples include Orion Engineered Carbons' "Special Black 350," "Special Black 100," "Special Black 250," "Special Black 5," "Special Black 4," "Special Black 4A," "Special Black 550," "Special Black 6," "Color Black FW200," "Color Black FW2," and "Color Black FW2V," as well as Cabot's "MONARCH 880," "MONARCH 1000," "MONARCH 1300," "MONARCH 1400," "MOGUL-L," and "REGAL 400R."

[0047] The average particle size of the carbon black is preferably 15 nm or more and 30 nm or less, more preferably 15 nm or more and 25 nm or less, and even more preferably 15 nm or more and 20 nm or less. By setting the average particle size of the carbon black to 15 nm or more and 30 nm or less, it becomes possible to obtain a conductive member that further suppresses the occurrence of color streaks in the axial direction when an image is formed. The reason for this is presumed to be as follows. By setting the average particle size of the carbon black to 15 nm or more and 30 nm or less, the carbon black particles become denser and tend to be concentrated near the island regions of the surface layer. This makes it easier for current to flow between the conductive materials. Therefore, by setting the island area occupancy rate to 10% or more and 45% or the island diameter to 100 nm or more and 750 nm or less, the effect of increasing the conductive paths in the surface layer is further enhanced. From the above, it is presumed that the conductive member is more likely to suppress the occurrence of color streaks in the axial direction when an image is formed.

[0048] The average particle size of carbon black is a value measured by a TEM (transmission electron microscope). The measurement method is as follows. First, the surface layer is cut using a microtome, and the resulting cross section is observed using a TEM (transmission electron microscope). The diameter of a circle equal to the projected area of ​​each of 50 carbon black particles is taken as the particle size, and the average of these diameters is taken as the average particle size.

[0049] The content of the conductive agent is preferably 10 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the total of the first resin and the second resin.

[0050] By setting the content of the conductive agent to 10 parts by mass or more and 15 parts by mass or less relative to 100 parts by mass of the total of the first resin and the second resin, the conductive member is more likely to suppress the occurrence of color streaks in the axial direction when an image is formed. The reason for this is presumed to be as follows. By setting the content of the conductive agent to 10 parts by mass or more per 100 parts by mass of the total of the first resin and the second resin, the amount of conductive agent contained in the surface layer is increased. This makes it easier for the conductive agents to be in close proximity to each other, making it easier for current to flow between the conductive agents. As a result, by setting the area occupancy rate of the island portions to 10% or more and 45% or less, or by setting the diameter of the island portions to 100 nm or more and 750 nm or less, the effect of increasing the conductive paths in the surface layer is further enhanced. By setting the content of the conductive agent to 15 parts by mass or less per 100 parts by mass of the total of the first resin and the second resin, the conductive agent is less likely to be scattered throughout the sea portion contained in the surface layer, and the conductive path is prevented from being dispersed and the conductive effect is prevented from being reduced. From the above, it is presumed that the conductive member is more likely to suppress the occurrence of color streaks in the axial direction when an image is formed.

[0051] The surface layer preferably further contains a silicon-containing compound. The content of the silicon-containing compound is preferably 0.05 parts by mass or more and 0.15 parts by mass or less relative to 100 parts by mass of the total of the first resin and the second resin.

[0052] The surface layer further contains a silicon-containing compound, and the content of the silicon-containing compound is 0.05 parts by mass or more and 0.15 parts by mass or less per 100 parts by mass of the total of the first resin and the second resin, thereby suppressing the occurrence of axial color streaks when forming an image. Furthermore, the contamination resistance and fogging suppression effect of the conductive member are improved. The reasons for this are presumed to be as follows. By setting the content of the silicon-containing compound to 0.05 parts by mass or more relative to 100 parts by mass of the total of the first resin and the second resin, the surface roughness of the surface layer is appropriately reduced, and the contamination resistance and fogging suppression effect of the conductive member are improved. Furthermore, by setting the content of the silicon-containing compound to 0.15 parts by mass or less relative to 100 parts by mass of the total of the first resin and the second resin, the resistance of the surface layer is reduced.

[0053] The content of the silicon-containing compound is more preferably 0.075 parts by mass or more and 0.125 parts by mass or less, and even more preferably 0.09 parts by mass or more and 0.11 parts by mass or less, relative to 100 parts by mass of the total of the first resin and the second resin.

[0054] The content of the silicon-containing compound is measured using an X-ray photoelectron spectrometer (XPS), such as Shimadzu Corporation's ESCA-3400. The procedure for measuring the content of the silicon-containing compound will be described below. The Si element is detected from the peak position of photoelectrons due to X-ray excitation, and quantification is performed from the area intensity of each peak intensity. The total mass of the first resin and the second resin is calculated by determining the blending ratio of the first resin to the second resin from the peak ratio of C=O and NH derived from amide bonds contained in the first resin and CO derived from butyral groups contained in the second resin detected by FT-IR (Fourier transform infrared spectroscopy). An FT-IR device that can be used is, for example, an IRSpirit manufactured by Shimadzu Corporation.

[0055] Examples of silicon-containing compounds include silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, and phenylmethylpolysiloxane; and modified silicone oils such as polyether-modified polysiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, fluorine-modified polysiloxane, methacryl-modified polysiloxane, mercapto-modified polysiloxane, and phenol-modified polysiloxane. From the viewpoint of compatibility, the silicon-containing compound is preferably a polyether-modified polysiloxane.

[0056] The surface layer may contain other additives. Other additives to be blended in the surface layer may be known additives, such as acid catalysts, softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, antioxidants, surfactants, coupling agents, and fillers (porous polyamide, silica, calcium carbonate, etc.).

[0057] -Island area ratio- When observing a cross section of the surface layer, the area ratio A of the islands in a region A from the surface of the surface layer to a depth of 20% of the film thickness is 25% or more and 45% or less. From the viewpoint of suppressing a decrease in mechanical strength and suppressing the occurrence of color streaks, the area ratio A of the islands is preferably 30% or more and 40% or less, and more preferably 35% or more and 40% or less.

[0058] By ensuring that the area ratio of the island portions in the entire surface layer falls within an appropriate range, the occurrence of color streaks can be easily suppressed while maintaining mechanical strength. Therefore, when observing a cross section of the surface layer, the area ratio B of the island portions in a region B deeper than 20% of the film thickness from the surface of the surface layer is preferably 40% or more and 50% or less, more preferably 42.5% or more and 50% or less, and even more preferably 45% or more and 50% or less, from the viewpoint of suppressing a decrease in mechanical strength and suppressing the occurrence of color streaks. Furthermore, the difference between the island area ratio A and the island area ratio B is preferably within 15% in absolute value, more preferably within 10%, and even more preferably within 5%, from the viewpoint of suppressing a decrease in mechanical strength and suppressing the occurrence of color streaks.

[0059] The area ratio of the island portion is a value measured as follows. A section sample of the surface layer is prepared by cutting it in the thickness direction using a cryomicrotome method. The cut surface of the surface layer cut by the cryomicrotome method is observed using a scanning electron microscope. Then, in the observed image, the area of ​​the region corresponding to region A from the surface of the surface layer to a depth of 20% of the film thickness is measured, and the area of ​​the island portions in region A is measured. The ratio of the area of ​​the island portions in region A to the area of ​​the region corresponding to region A is calculated as the island area ratio A. Similarly, the area of ​​the region corresponding to region B, which is deeper than 20% of the film thickness from the surface of the surface layer, and the area of ​​the island portion in region B are measured, and the ratio of the area of ​​the island portion in region B to the area of ​​the region corresponding to region B is calculated as the island portion area ratio B.

[0060] -Island diameter- In the conductive member according to this embodiment, the diameter of the island portion in the cross section of the surface layer (the cross section of either region A or region B) is preferably 100 nm or more and 750 nm or less, more preferably 150 nm or more and 650 nm or less, even more preferably 200 nm or more and 600 nm or less, and particularly preferably 300 nm or more and 400 nm or less.

[0061] The diameter of the island portion is a value measured as follows. A section sample of the surface layer is prepared by cutting it in the thickness direction using a cryomicrotome. The cut surface of the surface layer cut by the cryomicrotome is observed using a scanning electron microscope. Ten islands are randomly selected. For each of the ten islands, the maximum length (i.e., the longest diameter) drawn between any two points on the island's outline is measured, and the average of the ten longest diameters is taken as the island's diameter (nm).

[0062] -Surface roughness Rz of the outer surface of the surface layer- The surface roughness Rz of the outer peripheral surface of the surface layer may be 8.0 μm or less. Conventionally, when the surface roughness Rz of the outer peripheral surface of the surface layer exceeds 5.0 μm, fogging is likely to occur. However, in the conductive member according to the present embodiment, even if the surface roughness Rz of the outer peripheral surface of the surface layer exceeds 5.0 μm, the occurrence of fogging is suppressed as long as it is 8.0 μm or less.

[0063] The surface roughness Rz was measured in an environment of 23°C and 55% relative humidity using a contact surface roughness measuring device (Surfcom 570A, manufactured by Tokyo Seimitsu Co., Ltd.) and a diamond-tipped contact needle (5 μmR, 90° cone). The measurement distance was 2.5 mm, and the measurement area was from 5 mm to 7.5 mm from the end of the discharge area. Measurements were taken at four locations at 90° intervals around the circumference of the roll-shaped charging member, as well as at both ends of the discharge area, and the average value of a total of eight locations was calculated.

[0064] -Surface layer thickness- The thickness of the surface layer is preferably 3 μm or more and 25 μm or less, more preferably 5 μm or more and 20 μm or less, and even more preferably 6 μm or more and 15 μm or less.

[0065] The thickness of the surface layer is measured by cutting the surface layer in the thickness direction and observing the resulting cross section with an optical microscope.

[0066] <Resistance Z of conductive material> The conductive member according to this embodiment has a resistance Z measured by an impedance method of 4.5×10 5 Ω or less is preferable, and 4.0×10 5 Ω or less is more preferable, and 3.5×10 5 It is more preferable that the resistance Z is 1.0×10 4 Ω or more is preferable, and 5.0×10 4 It is more preferable that it is Ω or more. By setting the resistance Z measured by the impedance method within the above range, the ease of current flow throughout the entire conductive member is improved, which further reduces the occurrence of color streaks in the axial direction when an image is formed.

[0067] The procedure for measuring resistance Z is as follows. The power supply and ammeter used are an SI 1260 impedance / gain phase analyzer (manufactured by Toyo Corporation), and the current amplifier is a 1296 dielectric interface (manufactured by Toyo Corporation). The base material of the impedance measurement sample (conductive material) is used as the cathode, and a 1.5 cm wide aluminum plate wrapped around the surface of the conductive material is used as the anode. An AC voltage of 1 Vp-p is applied from the high frequency side in the frequency range of 1 MHz to 1 mHz, and the resistance Z of each sample is measured using the AC impedance method.

[0068] <Method of manufacturing conductive member> An example of a method for manufacturing the conductive member according to this embodiment will be described below. A roll-shaped member is prepared, which has an elastic layer provided on the outer peripheral surface of a cylindrical or columnar substrate. The method for producing this roll-shaped member is not particularly limited. For example, a method for producing the roll-shaped member includes winding a mixture containing a rubber material, and optionally a conductive agent and other additives, around the substrate, and heating and vulcanizing the mixture to form the elastic layer.

[0069] The method for providing the surface layer on the outer peripheral surface of the elastic layer is not particularly limited, but it is preferable to apply a dispersion liquid, in which the first resin, the second resin, and the conductive agent are dissolved and dispersed in a solvent, to the outer peripheral surface of the elastic layer and then dry the applied dispersion liquid. Examples of methods for applying the dispersion liquid include blade coating, Mayer bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. The conductive member according to this embodiment can be easily obtained by applying the dispersion liquid to the outer peripheral surface of the elastic layer and drying the applied dispersion liquid while maintaining the dew point of the environment at 12° C. or higher and 18° C. or lower. Typically, the dew point of the environment during the drying process of the applied dispersion liquid is about 5° C. Furthermore, in the step of drying the applied dispersion, for example, by reducing the wind speed during drying by half, the conductive member according to this embodiment can be easily obtained.

[0070] <Applications of conductive materials> The conductive member according to the present embodiment is used, for example, in a charging roll for charging the surface of an image carrier in an electrophotographic copying machine, an electrostatic printer, etc., a transfer roll for transferring a toner image formed on an image carrier to a transfer medium, a toner transport roll for transporting toner onto an image carrier, a conductive roll for supplying power or driving the conductive belt in combination with the conductive belt for electrostatically transporting paper, a cleaning roll for removing toner from an image carrier, etc. Also, in an inkjet image forming apparatus, it is used, for example, in a power supply roll for charging an intermediate transfer body before ink is ejected from an inkjet head. In particular, the conductive member according to this embodiment is suitably used as a charging roll.

[0071] The conductive member 121A according to this embodiment is a roll-shaped member, but the conductive member according to this embodiment is not limited to this and may be an endless belt-shaped member or a sheet-shaped member. Furthermore, the conductive member according to this embodiment may be configured to include, for example, an adhesive layer (primer layer) disposed between the substrate and the elastic layer, a resistance adjusting layer or migration preventing layer disposed between the elastic layer and the surface layer, and a coating layer (protective layer) disposed on the outside (outermost surface) of the surface layer.

[0072] (Charging device, image forming apparatus, and process cartridge) The charging device according to this embodiment includes the conductive member according to this embodiment. The charging device according to this embodiment is preferably a charging device that includes the conductive member according to this embodiment and charges the image carrier by a contact charging method. The contact width of the conductive member in the circumferential direction with the image carrier (i.e., the width of the conductive member in the circumferential direction in the region where the image carrier and the conductive member are in contact) is not particularly limited, and may be, for example, in the range of 0.5 mm or more and 5 mm or less, and preferably in the range of 1 mm or more and 3 mm or less.

[0073] The process cartridge according to the present embodiment is detachably mounted on, for example, an image forming apparatus having the following configuration, and includes a charging device for charging the surface of an image carrier. The charging device according to the present embodiment is used as the charging device. The process cartridge according to the present embodiment may, as necessary, include at least one selected from the group consisting of an image carrier, an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged image carrier, a developing device that develops the latent image formed on the surface of the image carrier with toner to form a toner image, a transfer device that transfers the toner image formed on the surface of the image carrier to a recording medium, and a cleaning device that cleans the surface of the image carrier.

[0074] The image forming apparatus according to the present embodiment includes an image carrier, a charging device that charges the surface of the image carrier, an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the image carrier, a developing device that develops the electrostatic latent image formed on the surface of the image carrier with a developer containing toner to form a toner image, and a transfer device that transfers the toner image to the surface of a recording medium.The charging device according to the present embodiment is used as the charging device.

[0075] Next, the image forming apparatus and the process cartridge according to this embodiment will be described with reference to the drawings.

[0076] 3 is a schematic diagram showing the configuration of an image forming apparatus according to this embodiment, in which the arrow UP indicates the vertically upward direction.

[0077] 3, the image forming device 210 includes an image forming device main body 211 that houses various components therein. Inside the image forming device main body 211, there are provided a storage section 212 that stores recording media P such as paper, an image forming section 214 that forms an image on the recording media P, a transport section 216 that transports the recording media P from the storage section 212 to the image forming section 214, and a control section 220 that controls the operation of each section of the image forming device 210. In addition, at the top of the image forming device main body 211, there is provided a discharge section 218 that discharges the recording media P on which an image has been formed by the image forming section 214.

[0078] Image forming section 214 includes image forming units 222Y, 222M, 222C, and 222K (hereinafter referred to as 222Y-222K) that form toner images of yellow (Y), magenta (M), cyan (C), and black (K), an intermediate transfer belt 224 (an example of a transfer target) onto which the toner images formed by image forming units 222Y-222K are transferred, a first transfer roll 226 (an example of a transfer roll) that transfers the toner images formed by image forming units 222Y-222K onto intermediate transfer belt 224, and a second transfer roll 228 (an example of a transfer member) that transfers the toner images transferred onto intermediate transfer belt 224 by first transfer roll 226 from intermediate transfer belt 224 to recording medium P. Note that image forming section 214 is not limited to the above configuration and may have other configurations as long as it forms an image on recording medium P (an example of a transfer target). Here, the unit consisting of the intermediate transfer belt 224, the first transfer roll 226, and the second transfer roll 228 corresponds to an example of a transfer device. This unit may be made into a cartridge (process cartridge).

[0079] Image forming units 222Y-222K are arranged side by side in the vertical center of image forming device 210, tilted relative to the horizontal. Each of image forming units 222Y-222K has a photoconductor 232 (an example of an image carrier) that rotates in one direction (for example, clockwise in FIG. 3). Note that image forming units 222Y-222K have the same configuration, and therefore reference numerals for the components of image forming units 222M, 222C, and 222K are omitted in FIG. 3.

[0080] Around each photoconductor 232, in order from the upstream side in the rotation direction of the photoconductor 232, there are provided a charging device 223 having a charging roll 223A (an example of a charging member) that charges the photoconductor 232, an exposure device 236 (an example of an electrostatic latent image forming device) that exposes the photoconductor 232 charged by the charging device 223 to light to form an electrostatic latent image on the photoconductor 232, a developing device 238 that develops the latent image formed on the photoconductor 232 by the exposure device 236 to form a toner image, and a removal member (cleaning blade, etc.) 240 that comes into contact with the photoconductor 232 and removes toner remaining on the photoconductor 232.

[0081] Here, the photosensitive member 232, the charging device 223, the exposure device 236, the developing device 238, and the removing member 240 are integrally held by a housing (casing) 222A and formed into a cartridge (process cartridge).

[0082] A self-scanning LED print head is applied to the exposure device 236. Note that the exposure device 236 may be an optical exposure device that exposes the photosensitive member 232 to light from a light source via a polygon mirror. The exposure device 236 forms a latent image based on an image signal sent from the control unit 220. The image signal sent from the control unit 220 is, for example, an image signal that the control unit 220 acquires from an external device.

[0083] The developing device 238 includes a developer supplier 238A that supplies developer to the photoreceptor 232, and a plurality of transport members 238B that transport the developer applied to the developer supplier 238A while stirring it.

[0084] The intermediate transfer belt 224 is formed in a circular shape and is disposed above the image forming units 222Y to 222K. On the inner periphery of the intermediate transfer belt 224, winding rolls 242 and 244 around which the intermediate transfer belt 224 is wound are provided. When one of the winding rolls 242 and 244 is driven to rotate, the intermediate transfer belt 224 moves (rotates) in a circular motion in one direction (for example, counterclockwise in FIG. 3) while in contact with the photosensitive member 232. The winding roll 242 serves as an opposing roll that faces the second transfer roll 228.

[0085] The first transfer roll 226 faces the photoconductor 232 across the intermediate transfer belt 224. The space between the first transfer roll 226 and the photoconductor 232 is a first transfer position where the toner image formed on the photoconductor 232 is transferred to the intermediate transfer belt 224.

[0086] The second transfer roll 228 faces the winding roll 242 across the intermediate transfer belt 224. The space between the second transfer roll 228 and the winding roll 242 is a second transfer position where the toner image transferred to the intermediate transfer belt 224 is transferred to the recording medium P.

[0087] The conveying section 216 is provided with a feed roll 246 that feeds out the recording medium P stored in the storage section 212, a conveying path 248 along which the recording medium P sent out to the feed roll 246 is conveyed, and a plurality of conveying rolls 250 that are arranged along the conveying path 248 and convey the recording medium P sent out by the feed roll 246 to a second transfer position.

[0088] A fixing device 260 that fixes the toner image formed on the recording medium P by the image forming section 214 onto the recording medium P is provided downstream in the transport direction from the second transfer position.

[0089] The fixing device 260 is provided with a heating roll 264 that heats the image on the recording medium P, and a pressure roll 266 as an example of a pressure member. The heating roll 264 is provided with a heat source 264B inside.

[0090] Discharge rolls 252 are provided downstream of the fixing device 260 in the transport direction to discharge the recording medium P onto which the toner image has been fixed to a discharge section 218.

[0091] Next, the image forming operation of the image forming apparatus 210 for forming an image on the recording medium P will be described.

[0092] In the image forming apparatus 210, the recording medium P is sent out from the storage section 212 by a sending roll 246, and is sent to a second transfer position by a plurality of transport rolls 250.

[0093] Meanwhile, in the image forming units 222Y to 222K, the photoconductor 232 charged by the charging device 223 is exposed by the exposure device 236 to form a latent image on the photoconductor 232. The latent image is developed by the developing device 238 to form a toner image on the photoconductor 232. The toner images of each color formed by the image forming units 222Y to 222K are superimposed on the intermediate transfer belt 224 at the first transfer position to form a color image. Then, the color image formed on the intermediate transfer belt 224 is transferred to the recording medium P at the second transfer position.

[0094] The recording medium P onto which the toner image has been transferred is transported to the fixing device 260, where the transferred toner image is fixed. The recording medium P onto which the toner image has been fixed is discharged to the discharge section 218 by the discharge rolls 252. A series of image forming operations is carried out as described above.

[0095] The image forming apparatus 210 according to this embodiment is not limited to the above configuration, and may employ a known image forming apparatus, such as a direct transfer type image forming apparatus that directly transfers the toner image formed on each photosensitive member 232 of the image forming units 222Y to 222K onto the recording medium P. [Example]

[0096] Examples will be described below, but the present embodiment is not limited to these examples. In the following description, unless otherwise specified, all "parts" and "%" are based on mass.

[0097] (Example 1: Preparation of conductive member) <Formation of elastic layer> For 100 parts by mass of elastic material (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber), 15 parts by mass of conductive agent (carbon black, Asahi Thermal manufactured by Asahi Carbon Co., Ltd.), 1 part by mass of vulcanizing agent (sulfur, 200 mesh, manufactured by Tsurumi Chemical Industry Co., Ltd.) as other additives to be blended in the elastic layer, and vulcanization accelerator as other additives to be blended in the elastic layer The mixture, to which 2.0 parts by mass of Noccela DM (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) was added, was kneaded using an open roll to obtain a composition for forming an elastic layer. The composition for forming an elastic layer was wound, via an adhesive layer, around the outer surface of an 8 mm diameter shaft (substrate) made of SUS303 using a press molding machine, and then heated in an oven at 180°C for 30 minutes to form a 3.5 mm thick elastic layer on the shaft. The outer surface of this elastic layer was polished to obtain a 14 mm diameter conductive elastic roll having a 3.0 mm thick elastic layer.

[0098] (Formation of surface layer) A dispersion was obtained by diluting 15 parts by mass of a composition consisting of 76 parts by mass of a polyamide resin (N-methoxymethylated nylon, F30K manufactured by Nagase ChemteX Corporation) as the first resin, 24 parts by mass of a polyvinyl butyral resin (S-LEC BL-1, manufactured by Sekisui Chemical Co., Ltd.) as the second resin, 13 parts by mass of carbon black (MONARCH1000, manufactured by Cabot Corporation) as a conductive agent, 10 parts by mass of a porous polyamide filler (Orgasol2001UDNAT1, manufactured by Arkema) as a filler, 1.0 part by mass of an acid catalyst (NACURE4167, manufactured by King Industries Co., Ltd.), and 0.025 parts by mass of a leveling agent (polyether-modified polydimethylsiloxane, BYK307, manufactured by BYK) with 85 parts by mass of methanol and dispersing the mixture using a bead mill. The obtained dispersion was dip-coated onto the outer surface of the elastic layer of a conductive elastic roll in an environment with a temperature of 24°C and a dew point of 14°C, and then air-dried. After that, the dispersion was heated at 140°C for 30 minutes to crosslink the surface, forming a surface layer with a thickness of 10 μm, and a conductive member was obtained.

[0099] (Comparative Example 1) A conductive member was obtained in the same manner as in Example 1, except that the dew point was set to 5°C during air drying in forming the surface layer.

[0100] (Examples 2 to 8) As shown in Table 1, conductive members were obtained in the same manner as in Example 1, except that the application environment (dew point) and the amounts of the first resin and the second resin added were changed.

[0101] Example 9 A conductive member was obtained in the same manner as in Example 1, except that the air volume in the coating booth was reduced by half during air drying in forming the surface layer.

[0102] Example 10 A conductive member was obtained in the same manner as in Example 1, except that the air volume in the coating booth was further reduced during air drying in forming the surface layer.

[0103] The following properties of the conductive members obtained in each example were measured according to the methods described above. The results are shown in Table 2.

[0104] <Conductive point measurement using current-simultaneous atomic force microscope (C-AFM)> The isoelectric point of the surface of the obtained conductive member was measured under the following conditions using a Hitachi High-Tech AFM5200S (simultaneous AFM / current measurement) and an S-image CL scanner (110 μm). Areas with a current of 60 pA or higher were considered conductive, and the area ratio and average area of ​​the conductive areas measured as particles were calculated. The measurement results are shown in Table 2. Probe holder: Multi-holder Cantilever: SI-DF20-R (100 nm) Bias voltage: -10V Measurement range: 50 μm x 50 μm Number of data X:512 Y:512

[0105] <Percentage of areas where the current value is 60 pA or more> On the surface of the obtained conductive member, the current simultaneous measurement atomic force microscope was used to apply -30 V to a 100 nm diameter probe (cantilever) and move it while dividing an area of ​​50 μm square (= 50 μm × 50 μm) into a 256 × 256 grid, and the current value flowing in each section was measured. Table 2 shows the area ratio of each section where the current value is 60 pA or more.

[0106] <Measurement of resistance Z of conductive material> The power supply and ammeter used were an SI 1260 impedance / gain phase analyzer (manufactured by Toyo Corporation), and the current amplifier was a 1296 dielectric interface (manufactured by Toyo Corporation). The substrate of the impedance measurement sample (conductive member) was used as the cathode, and a 1.5 cm wide aluminum plate wrapped around the surface of the conductive member was used as the anode. An AC voltage of 1 Vp-p was applied from the high frequency side in the frequency range of 1 MHz to 1 mHz, and the resistance Z of each sample was measured using the AC impedance method.

[0107] <Evaluation> -Color streak evaluation- The conductive member obtained in the Examples or Comparative Examples was incorporated as a charging roll into a modified image forming apparatus (DocuCentre-V C7776, manufactured by FUJIFILM Business Innovation Co., Ltd.), and 5,000 A4 images with an image density of 30% were output under conditions of 28°C and 85% RH. The level of color streaks that appeared on the image printed on the 5,000th sheet and extended in the axial direction of the photoreceptor was evaluated on a scale of G0 to G3. G0 to G2 are levels that are acceptable for use. The evaluation results are shown in Table 2. G0: No color streaks extending in the axial direction of the photosensitive member are observed. G0.5: There is one or less color streak extending in the axial direction of the photoreceptor. G1: There are 2 to 4 color streaks extending in the axial direction of the photosensitive member. G1.5: There are 5 to 7 color streaks extending in the axial direction of the photoreceptor. G2: There are 8 to 10 color streaks extending in the axial direction of the photosensitive member. G2.5: There are 11 to 13 color streaks extending in the axial direction of the photoreceptor. G3: There are 14 or more color streaks extending in the axial direction of the photoreceptor.

[0108] -Mechanical strength evaluation- The mechanical strength of the surface layer was evaluated by the MIT test. The MIT test was performed in accordance with JIS P 8115:2001 (MIT test machine method). Specifically, a rectangular test piece (the thickness of the test piece is the layer thickness of the surface layer) having a width of 15 mm and a length of 200 mm was cut out in the circumferential direction from the surface layer of the conductive member. Both ends of this rectangular test piece were fixed, and a tensile force of 1 kgf was applied, and the test piece was repeatedly bent (folded) in a 90° direction to the left and right using a clamp with a curvature radius R = 0.05 as a fulcrum. The number of flexions at which the rectangular test piece broke was taken as the number of times it could be bent, and the strength was evaluated based on the number of times it could be bent according to the following evaluation criteria. The MIT test was carried out in an environment with a temperature of 22°C and a humidity of 55% RH. Table 2 shows the evaluation results. G0: Break resistance is 100,000 times or more. G1: Break resistance is between 50,000 and 100,000 times. G2: Break resistance is between 10,000 and 50,000 times. G3: Break resistance is less than 10,000 times.

[0109] [Table 1]

[0110] [Table 2]

[0111] The abbreviations in Tables 1 and 2 are as follows: -First Resin- PA1: Polyamide resin (F30K manufactured by Nagase ChemteX Corporation) -Second Resin- PVB1: Polyvinyl butyral resin (S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) -Conductive material- CB1: Carbon black (MONARCH1000, manufactured by Cabot Corporation) -Filler- F1: Porous polyamide filler (Orgasol2001UDNAT1, manufactured by Arkema) -Acid catalyst- CAT1: Amine-neutralized phosphoric acid catalyst (NACURE4167, King Industries) -Silicon-containing compounds- LA1: Polyether-modified polydimethylsiloxane (BYK307, manufactured by BYK) as polyether-modified polysiloxane

[0112] From the above results, it can be seen that the conductive member of this example is superior in suppressing the occurrence of color streaks compared to the conductive member of the comparative example.

[0113] (((1))) A conductive member in which the area ratio of particulate conductive parts measured when measuring conductive points on the surface using a current simultaneous measurement atomic force microscope is 15 area % or more. (((2))) When measuring conductive points on the surface using an atomic force microscope with simultaneous current measurement, the average area of ​​the particulate conductive parts measured is 0.05 μm 2 The conductive member is as described above. (((3))) The conductive member according to (((1))), wherein the area ratio of the conductive portion is 15 area % or more and 80 area % or less. (((4))) The conductive member according to (((3))), wherein the area ratio of the conductive portion is 30 area % or more and 60 area % or less. (((5))) The average area of ​​the conductive portion is 0.05 μm 2 1.0μm or more 2 The conductive member according to (((1))) or (((2))) below. (((6))) The average area of ​​the conductive portion is 0.20 μm 2 More than 0.50μm 2 The conductive member according to (((5))) below. (((7))) A conductive member according to any one of (((1))) to (((6))), wherein, when a voltage of -30 V is applied to a probe having a diameter of 100 nm on the surface and the current value is measured while the probe is moved, a 50 μm square area is divided into a 256 × 256 grid, and 60% or more of the area of ​​each divided area has a current value of 60 pA or more. (((8))) A conductive member according to any one of (((1))) to (((7))), comprising a substrate, an elastic layer provided on the substrate, and a surface layer provided on the elastic layer. (((9))) The conductive member according to (((8))), wherein the surface layer contains a first resin, a second resin, and a conductive agent. (((10))) The conductive member according to (((9))), wherein the surface layer has a sea-island structure consisting of a sea portion comprising the first resin and island portions comprising the second resin. (((11))) A charging device comprising the conductive member according to any one of (((1))) to (((10))). (((12))) A process cartridge equipped with the charging device according to (((11))), which is detachably mounted on an image forming apparatus. (((13))) An image forming apparatus comprising: an image carrier; a charging device according to (((11))) that charges the surface of the image carrier; an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the image carrier; a developing device that develops the electrostatic latent image formed on the surface of the image carrier with a developer containing toner to form a toner image; and a transfer device that transfers the toner image to the surface of a recording medium.

[0114] According to the inventions (((1))) or (((8))), a conductive member is provided which is superior in suppressing the occurrence of color streaks compared to a conductive member in which the area ratio of particulate conductive portions measured when conductive points on the surface are measured using a current simultaneous measurement atomic force microscope is less than 15 area %. According to the invention of (((2))), the average area of ​​the particulate conductive portions measured when measuring conductive points on the surface using a current simultaneous measurement atomic force microscope is 0.05 μm 2 In this case, a conductive member having excellent suppression of color streaks can be provided, as compared with a case where the thickness is less than 100 μm. According to the invention (((3))), a conductive member is provided that is more excellent in suppressing the occurrence of color streaks than when the area ratio of the conductive portion is less than 15 area % or more than 80 area %. According to the invention related to (((4))), a conductive member is provided which is more excellent in suppressing the occurrence of color streaks than when the area ratio of the conductive portion is less than 30 area % or more than 60 area %. According to the invention (((5))), the average area of ​​the conductive portion is 0.05 μm 2 Less than or 1.0 μm 2 In this case, a conductive member having superior color streak suppression properties is provided compared to when the thickness is greater than 100 μm. According to the invention (((6))), the average area of ​​the conductive portion is 0.20 μm 2 Less than or 0.50 μm 2 In this case, a conductive member having superior color streak suppression properties is provided compared to when the thickness is greater than 100 μm. According to the invention of (((7))), when a voltage of -30 V is applied to a probe having a diameter of 100 nm on the surface and the current value is measured while the probe is moved, a conductive member is provided which is superior in suppressing the occurrence of color streaks compared to a case where a 50 μm square area is divided into a 256 × 256 grid and the area in which a current value of 60 pA or more flows in each divided area accounts for less than 60 area%. According to the invention of (((9))) or (((10))), a conductive member is provided which is more excellent in suppressing the occurrence of color streaks than when the surface layer contains only one type of resin. According to the inventions of (((11))), (((12))) or (((13))), the conductive member provided has an area ratio of particulate conductive portions measured when conductive points on the surface are measured by a current simultaneous measurement atomic force microscope of less than 15 area %, or an average area of ​​particulate conductive portions measured when conductive points on the surface are measured by a current simultaneous measurement atomic force microscope of less than 0.05 μm 2 Therefore, a charging device, a process cartridge, or an image forming apparatus that is superior in suppressing the occurrence of color streaks compared to when the charging device, the process cartridge, or the image forming apparatus is provided. [Explanation of symbols]

[0115] 30 shaft, 31 elastic layer, 32 surface layer, 121A conductive member, 210 image forming apparatus, 214 image forming section, 216 conveying section, 218 discharge section, 220 control section, 222 image forming unit, 223 charging device, 223A charging roll, 224 intermediate transfer belt, 226 first transfer roll, 228 second transfer roll, 232 photosensitive member, 236 exposure device, 238 developing device, 240 removal member, 260 fixing device

Claims

1. The area ratio of particulate conductive parts measured when measuring conductive points on the surface using a current simultaneous measurement atomic force microscope is 15% or more. Conductive material.

2. The average area of ​​the particulate conductive parts measured when measuring the conductive points on the surface using a current simultaneous measurement atomic force microscope is 0.05 μm ２ That's all Conductive material.

3. The conductive member according to claim 1 , wherein the area ratio of the conductive portion is 15 area % or more and 80 area % or less.

4. The conductive member according to claim 3 , wherein the area ratio of the conductive portion is 30% by area or more and 60% by area or less.

5. The average area of ​​the conductive portion is 0.05 μm ２ 1.0 μm or more ２ The conductive member according to claim 1 or 2, wherein:

6. The average area of ​​the conductive portion is 0.20 μm ２ 0.50 μm or more ２ The conductive member according to claim 5, wherein:

7. The conductive member according to claim 1 or 2, wherein, when a current value is measured while a probe having a diameter of 100 nm is applied with −30 V and moved on the surface, a 50 μm square region is divided into a 256 × 256 grid, and the area in which a current value of 60 pA or more flows in each divided region accounts for 60 area% or more of the divided region.

8. The conductive member according to claim 1 or 2, comprising: a substrate; an elastic layer provided on the substrate; and a surface layer provided on the elastic layer.

9. The conductive member according to claim 8 , wherein the surface layer contains a first resin, a second resin, and a conductive agent.

10. The conductive member according to claim 9 , wherein the surface layer has a sea-island structure consisting of a sea portion containing the first resin and island portions containing the second resin.

11. A charging device comprising the conductive member according to claim 1 or 2.

12. The charging device according to claim 11, A process cartridge is detachably mounted in an image forming apparatus.

13. an image carrier; The charging device according to claim 11 , which charges the surface of the image carrier; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the image carrier; a developing device that develops the electrostatic latent image formed on the surface of the image carrier with a developer containing toner to form a toner image; a transfer device that transfers the toner image onto a surface of a recording medium. Image forming device.

Images