Charging member, charging device, process cartridge, and image forming apparatus

Abstract

To provide a charging member that hardly generates density unevenness in an image and hardly generate cracks in a surface.SOLUTION: A charging member has a support member, an elastic layer provided on the support member, and a surface layer provided on the elastic layer. The surface layer contains a resin, conductive particles, and non-conductive inorganic particles. The surface layer contains the non-conductive inorganic particles in an amount of 5 pts.mass or more and 40 pts.mass or less relative to 100 pts.mass of the resin.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a charged member, a charging device, a process cartridge, and an image forming apparatus.

Background Art

[0002] Patent Document 1 discloses a charged member having a conductive support, a semiconductive elastic layer, and a protective layer, wherein the protective layer is a polyamide resin, a fluororesin, a polyvinyl butyral resin, or a polyester resin.

[0003] Patent Document 2 discloses a conductive roll having a shaft body, an elastic layer, and a surface layer, which contacts a charged object in a state where a voltage is applied to charge the charged object, and the surface layer has insulating particles, and a part of the insulating particles is arranged to overlap at least two or more in the thickness direction of the surface layer. The insulating particles are 12 nylon particles.

[0004] Patent Document 3 discloses a conductive roll including a core material, a rubber base material, and a surface layer, wherein the surface layer includes a conductive matrix and insulating particles dispersed in the conductive matrix, and the particles include large particles and small particles.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present disclosure aims to provide a charging member that is less likely to generate density unevenness in an image and less likely to generate cracks on the surface, compared to a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin.

Means for Solving the Problem

[0007] Specific means for solving the above problems include the following aspects. <1> It has a support member, an elastic layer provided on the support member, and a surface layer provided on the elastic layer, the surface layer contains a resin, conductive particles, and non-conductive inorganic particles, the surface layer contains 5 parts by mass or more and 40 parts by mass or less of the non-conductive inorganic particles with respect to 100 parts by mass of the resin, charging member. <2> The charging member according to <1>, wherein the thermal conductivity of the non-conductive inorganic particles is 40 W / (m·K) or more. <3> The charging member according to <1> or <2>, wherein the non-conductive inorganic particles include at least one selected from the group consisting of nitride particles, oxide particles, carbide particles, and boride particles. <4> The charging member according to any one of <1> to <3>, wherein the non-conductive inorganic particles include at least one selected from the group consisting of aluminum nitride particles, boron nitride particles, and magnesium oxide particles. <5> The charging member according to any one of <1> to <4>, wherein the average primary particle diameter of the non-conductive inorganic particles is 5 μm or more and 20 μm or less. <6> A charging device having the charging member according to any one of <1> to <5>. <7> a photoreceptor, A charging device having the charging member according to any one of <1> to <5> and charging the photoreceptor, and a process cartridge detachable from the image forming apparatus. <8> a photoreceptor, a charging device having the charging member according to any one of <1> to <5> and charging the photoreceptor, an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged photoreceptor, a developing device that develops the electrostatic latent image formed on the surface of the photoreceptor with a developer containing toner to form a toner image, a transfer device that transfers the toner image onto the surface of a recording medium, and an image forming apparatus comprising the same.

Advantages of the Invention

[0008] <1>, <3> or <4> provides a charging member in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared with a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin. <2> provides a charging member in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared with a charging member in which the thermal conductivity of the non-conductive inorganic particles contained in the surface layer is less than 40 W / (m·K). <5> provides a charging member in which cracks are less likely to occur on the surface, as compared with a charging member in which the average particle diameter of the non-conductive inorganic particles contained in the surface layer is more than 20 μm. <6> provides a charging device including a charging member in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared with a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin. <7> provides a process cartridge including a charging member in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared with a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin. <8> provides an image forming apparatus including a charging member in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared with a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present disclosure will be described. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the embodiments.

[0011] In the present disclosure, "A and / or B" is synonymous with "at least one of A and B". That is, "A and / or B" means that it may be only A, only B, or a combination of A and B.

[0012] In the present disclosure, the numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other stepwise descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0013] In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0014] When embodiments are described with reference to the drawings in the present disclosure, the configuration of the embodiments is not limited to the configuration shown in the drawings. Also, the sizes of the members in each drawing are conceptual, and the relative size relationships between the members are not limited thereto.

[0015] In the present disclosure, each component may include a plurality of corresponding substances. When referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition. In the present disclosure, the particles corresponding to each component may include a plurality of types. When there are a plurality of types of particles corresponding to each component in the composition, unless otherwise specified, the particle diameter of each component means a value for the mixture of the plurality of types of particles present in the composition.

[0016] In the present disclosure, the "axial direction" of the charged member means the direction in which the rotation axis of the charged member extends, and the "circumferential direction" of the charged member means the rotation direction of the charged member.

[0017] <Charged member> The charged member according to the present embodiment has a support member, an elastic layer provided on the support member, and a surface layer provided on the elastic layer. The surface layer is the outermost layer of the charged member according to the present embodiment.

[0018] FIG. 1 is a schematic perspective view showing an example of the charged member according to the present embodiment. FIG. 2 is a cross-sectional view taken along the line A-A of FIG. 1, and is a cross-sectional view of the charged member illustrated in FIG. 1 cut in the radial direction. The charged member 30 shown in FIG. 1 is a roll-shaped charged member. The charged member 30 has a structure in which an elastic layer 34 and a surface layer 36 are laminated in this order on a support member 32. The charged member 30 may have an adhesive layer (not shown) between the support member 32 and the elastic layer 34 and / or between the elastic layer 34 and the surface layer 36. The surface layer 36 is the outermost layer of the charged member 30.

[0019] The shape of the charging member according to this embodiment is not limited to a roll shape, and may be a belt shape, a tube shape, a blade shape, or the like.

[0020] The charging member according to this embodiment has a surface layer containing a resin, conductive particles, and non-conductive inorganic particles, and the surface layer contains 5 parts by mass or more and 40 parts by mass or less of non-conductive inorganic particles with respect to 100 parts by mass of the resin. Due to the above configuration, the charging member according to this embodiment is less likely to cause density unevenness in the image and less likely to generate cracks on the surface. The reason is speculated as follows.

[0021] When image formation is performed over a long period of time, dirt gradually accumulates on the surface of the charging member. This dirt mainly comes from toner. Dirt on the surface of the charging member is likely to occur in a charging member that contacts the surface of the photoreceptor, and may also occur in a charging member that does not contact the surface of the photoreceptor because it electrostatically adsorbs toner. When continuous image formation is performed, the temperature of the charging member rises, and the components of the surface layer of the charging member and the components derived from the toner chemically react, and contaminants adhere to the surface of the charging member to form a contamination layer. Due to this contamination layer, discharge unevenness occurs in the charging member, and density unevenness occurs in the image. In addition, since the contamination layer is relatively fragile, cracks are likely to occur, and cracks may occur in the charging member starting from the cracks in the contamination layer. In response to the above events, the charging member according to this embodiment contains inorganic particles, which are particles excellent in thermal conductivity, in the surface layer for the purpose of enhancing the heat dissipation property of the charging member. The inorganic particles contained in the surface layer for heat conduction purposes are non-conductive so that even if the content is relatively large, it does not affect the electrical characteristics of the charging member. The surface layer containing non-conductive inorganic particles suppresses the temperature rise of the charging member due to its excellent heat dissipation property. As a result, the chemical reaction between the components of the surface layer of the charging member and the components derived from the toner and the formation of the contamination layer are suppressed. Therefore, the charging member according to this embodiment is less likely to cause density unevenness in the image and less likely to generate cracks on the surface.

[0022] In the present disclosure, the distinction between non-conductive and conductive particles included in the surface layer is that particles with a volume resistivity of 1 × 10 8 Ω·cm or more are non-conductive particles, and particles with a volume resistivity of less than 1 × 10 8 Ω·cm are conductive particles. The method for measuring the volume resistivity of the particles included in the surface layer is as follows. Fill the sample holder of the powder resistance measuring device with the particles to be measured, and compress them by applying a load of 20 kN. The measurement is performed at an applied voltage of 90 V and a load of 4 kN in an environment of a temperature of 23°C and a relative humidity of 50%. The particles to be used for the measurement are particles that are the material forming the surface layer, or particles taken out from the surface layer. There is no limitation on the method for taking out the particles from the surface layer. The method is, for example, a method of immersing the surface layer peeled from the charged member in an organic solvent that dissolves the binder resin to dissolve the binder resin with the organic solvent and take out the particles; a method of heating the surface layer peeled from the charged member to a high temperature to disappear the binder resin and take out the particles; and the like.

[0023] In the charged member according to the present embodiment, the content of the non-conductive inorganic particles in the surface layer is 5 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the resin. From the viewpoints of the thermal conductivity and heat dissipation of the surface layer, the content of the non-conductive inorganic particles in the surface layer is 5 parts by mass or more, preferably 10 parts by mass or more, and more preferably 15 parts by mass or more with respect to 100 parts by mass of the resin. From the viewpoint that cracks are less likely to occur in the surface layer, the content of the non-conductive inorganic particles in the surface layer is 40 parts by mass or less, preferably 30 parts by mass or less, and more preferably 25 parts by mass or less.

[0024] In the charged member according to the present embodiment, from the viewpoint of suppressing the generation of a contamination layer on the surface of the charged member, it is preferable that the thermal conductivity from the lower surface of the elastic layer to the upper surface of the surface layer is 0.4 W / (m·K) or more, more preferably 0.5 W / (m·K) or more, and still more preferably 0.6 W / (m·K) or more. The thermal conductivity from the lower surface of the elastic layer to the upper surface of the surface layer may be, for example, 5.0 W / (m·K) or less, 4.0 W / (m·K) or less, or 3.0 W / (m·K) or less.

[0025] The method for measuring the thermal conductivity from the lower surface of the elastic layer to the upper surface of the surface layer of the charged member is as follows. From the central portion in the axial direction of the charged member, the entire layer from the elastic layer to the surface layer is cut out to have an axial length of 5 mm × a circumferential length of 2 mm, and this is used as a sample. Under room temperature (25°C ± 3°C), using a thermal diffusivity measuring device (FOX50, manufactured by Waters Corporation), the thermal diffusivity in the thickness direction (i.e., the direction from the lower surface of the elastic layer to the upper surface of the surface layer) is measured. The specific heat and density are multiplied by the thermal diffusivity to calculate the thermal conductivity (W / (m·K)). The method for measuring the specific heat is as follows. From the central portion in the axial direction of the charged member, after cutting out the entire layer from the elastic layer to the surface layer to have an axial length of 5 mm × a circumferential length of 2 mm, the axial length and circumferential length are adjusted so that the mass of the sample becomes 25 mg, and this is used as a sample. Measurement is performed using an input compensation differential scanning calorimeter (Diamond DSC, manufactured by ParkinElmer) in accordance with JIS K 7123:2012, and the specific heat is calculated. The method for measuring the density is as follows. From the central portion in the axial direction of the charged member, the entire layer from the elastic layer to the surface layer is cut out to have an axial length of 5 mm × a circumferential length of 2 mm, and this is used as a sample. The density is measured using a dry density measuring device (Accupic II1340, manufactured by Micromeritics).

[0026] Hereinafter, each layer of the charged member will be described in detail.

[0027] [Support member] The support member is a conductive member that functions as an electrode and a support of the charged member. The support member may be a hollow member or a non - hollow member, and for example, is a member in the shape of a rod, a cylinder, or an endless belt.

[0028] Examples of the support member include metal members such as iron (free-cutting steel, etc.), copper, copper alloy, brass, stainless steel, aluminum, nickel; iron members plated with chromium, nickel, etc.; members obtained by plating the outer peripheral surface of resin or ceramic members; resin or ceramic members containing a conductive agent; and the like.

[0029] [Elastic layer] The elastic layer has conductivity and preferably has a volume resistivity at a temperature of 20 °C of 1×10 3 Ω·cm or more and 1×10 14 Ω·cm or less.

[0030] The volume resistivity of the elastic layer is a value measured by the following method. After removing the surface layer of the charged member by polishing, cut out an elastic layer with an axial length of 25 mm and a circumferential length of 8 mm from the central part in the axial direction of the charged member and use this as a sample. Measure the thickness of the sample (i.e., the elastic layer). For the sample, according to JIS K 6911:1995, use a measuring jig (R12702A / B resistivity chamber: manufactured by Advantest Corporation) and a high-resistance measuring instrument (R8340A digital high-resistance / microammeter: manufactured by Advantest Corporation), and apply a voltage adjusted so that the electric field (applied voltage / composition sheet thickness) becomes 1000 V / cm for 30 seconds. Read the current value and calculate it using the following formula. Volume resistivity (Ω·cm) = (sample area (cm 2 ) × applied voltage (V)) / (current value (A) × sample thickness (cm))

[0031] The elastic layer may be a foamed elastic layer or a non-foamed elastic layer. The elastic layer may be directly disposed on the outer peripheral surface of the support member, or may be disposed on the outer peripheral surface of the support member via an adhesive layer.

[0032] An example of the embodiment of the elastic layer includes an elastic material, a conductive agent, and other additives.

[0033] Examples of the elastic material include polyurethane, nitrile rubber, isoprene rubber, butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, epichlorohydrin rubber, epichlorohydrin-ethylene oxide rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, butadiene rubber, chloroprene rubber, chlorinated polyisoprene, hydrogenated polybutadiene, butyl rubber, silicone rubber, fluorine rubber, natural rubber, and elastic materials obtained by mixing two or more of these. Among these elastic materials, polyurethane, silicone rubber, ethylene-propylene-diene rubber, epichlorohydrin-ethylene oxide rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether rubber, acrylonitrile-butadiene rubber, and elastic materials obtained by mixing two or more of these are preferred.

[0034] Examples of the conductive agent include an electron conductive agent and an ion conductive agent. Examples of the electron conductive agent include carbon blacks such as furnace black, thermal black, channel black, ketjen black, acetylene black, and color black; pyrolytic carbon; graphite; metals or alloys such as aluminum, copper, nickel, and stainless steel; metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, and tin oxide-indium oxide solid solution; substances obtained by making the surface of an insulating substance conductive; and the like in the form of powder. Examples of the ion conductive agent include perchlorates or chlorates such as tetraethylammonium, lauryltrimethylammonium, and benzyltrialkylammonium; perchlorates or chlorates of alkali metals or alkaline earth metals such as lithium and magnesium; and the like. The conductive agent may be used alone or in combination of two or more.

[0035] It is preferable to set the total content of the conductive agent contained in the elastic layer based on the volume resistivity of the elastic layer. When using an electronic conductive agent as the conductive agent, the total amount of the electronic conductive agent may be, for example, 1 part by mass or more and 20 parts by mass or less, and may be 3 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the elastic material. When using an ionic conductive agent as the conductive agent, the total amount of the ionic conductive agent may be, for example, 0.1 part by mass or more and 10 parts by mass or less, and may be 0.5 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the elastic material.

[0036] The average primary particle diameter of the conductive agent is preferably 1 nm or more and 500 nm or less, and more preferably 5 nm or more and 200 nm or less. The average primary particle diameter of the conductive agent is obtained by observing the cross section of the elastic layer with an electron microscope, measuring the major diameters of 100 conductive agents, and calculating the arithmetic mean thereof.

[0037] Carbon black is preferably used as the conductive agent. The average primary particle diameter of the carbon black is preferably 1 nm or more and 500 nm or less, and more preferably 5 nm or more and 200 nm or less. The content of the carbon black is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the elastic material.

[0038] Examples of other additives include vulcanizing agents, vulcanization accelerators, vulcanization accelerator aids, fillers, softeners, plasticizers, curing agents, antioxidants, surfactants, coupling agents, etc.

[0039] Examples of the filler include calcium carbonate, silica, clay minerals, etc. The filler may be used alone or in combination of two or more.

[0040] Calcium carbonate is preferably used as the filler. The content of the calcium carbonate is preferably 1 part by mass or more and 50 parts by mass or less, and more preferably 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the elastic material.

[0041] The layer thickness of the elastic layer is preferably 5 mm or more and 20 mm or less, and more preferably 10 mm or more and 15 mm or less. The layer thickness of the elastic layer is measured by imaging the cross-section with an electron microscope. Four points are measured at 90° intervals in the circumferential direction at the center of the axial direction of the charged member, and the arithmetic mean value is taken as the layer thickness of the elastic layer.

[0042] As a method for forming the elastic layer on the support member, for example, an elastic layer forming composition in which an elastic material, a conductive agent, and other additives are mixed, and a cylindrical support member are both extruded from an extruder to form a layer of the elastic layer forming composition on the outer peripheral surface of the support member. Then, the layer of the elastic layer forming composition is heated to cause a crosslinking reaction (including vulcanization) to form an elastic layer; a method in which a layer of an elastic layer forming composition in which an elastic material, a conductive agent, and other additives are mixed is extruded from an extruder onto the outer peripheral surface of an endless belt-shaped support member to form a layer of the elastic layer forming composition on the outer peripheral surface of the support member. Then, the layer of the elastic layer forming composition is heated to cause a crosslinking reaction (including vulcanization) to form an elastic layer; and the like. The support member may have an adhesive layer on its outer peripheral surface.

[0043] [Adhesive layer] There may be an adhesive layer for bonding the support member and the elastic layer between them. Specific examples of the adhesive layer interposed between the support member and the elastic layer include layers containing resins such as polyolefin, acrylic resin, epoxy resin, polyurethane, nitrile rubber, chloroprene rubber, vinyl chloride resin, vinyl acetate resin, polyester, phenol resin, and silicone resin. The adhesive layer may contain a conductive agent (for example, the aforementioned electron conductive agent or ion conductive agent).

[0044] From the viewpoint of the adhesion between the elastic layer and the support member, the layer thickness of the adhesive layer is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 40 μm or less, and still more preferably 5 μm or more and 20 μm or less. The layer thickness of the adhesive layer is measured by imaging the cross-section with an electron microscope. Four points are measured at 90° intervals in the circumferential direction at the center of the axial direction of the charged member, and the arithmetic mean value is taken as the layer thickness of the adhesive layer.

[0045] [Surface layer] The surface layer has conductivity and a volume resistivity at a temperature of 20 °C of 1×103 1×10 or more Ω·cm 14 It is preferably 1×10 or less Ω·cm. The volume resistivity of the surface layer is a value measured by the following method.

[0046] The layer thickness of the surface layer is measured by the measurement method described later. The support member of the charged member is used as the cathode, and an aluminum plate with a width of 1.5 cm wound around the surface layer once is used as the anode. SI 1260 inpedance / gain phase analyzer (Tokyo Teknika Co., Ltd.) is used as the power supply and ammeter, and 1296 dielectric interface (Tokyo Teknika Co., Ltd.) is used as the current amplifier. An AC voltage of 1Vp-p is applied from the high-frequency side from a frequency of 1 kHz to 0.01 Hz. The resistance component of the impedance in the range from 100 Hz to 0.1 Hz is obtained as the value of the volume resistance of the surface layer. The volume resistivity of the surface layer is calculated by the following formula. Volume resistivity (Ω·cm) = Volume resistance (Ω) × Area of anode (cm 2 ) / Layer thickness of surface layer (cm)

[0047] The surface layer contains a resin, conductive particles, and non-conductive inorganic particles.

[0048] Examples of the resin include copolymerized nylon, polyamide, polyimide, polyamideimide, polyvinyl butyral, polyester, polyethylene terephthalate, polyarylate, polycarbonate, polyethylene, polyurethane, phenolic resin, silicone resin, acrylic resin, fluorine-modified acrylic resin, silicone-modified acrylic resin, melamine resin, epoxy resin, fluororesin, polyvinylidene fluoride resin, tetrafluoroethylene resin, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluororubber, polyvinyl resin, polyvinyl alcohol, polyvinyl acetal, polyvinylidene chloride, polyvinyl chloride, ethylene-vinyl acetate copolymer, cellulose, polythiophene resin, a resin obtained by mixing two or more of these, and a resin obtained by curing or crosslinking at least one of these with a curing agent or catalyst. The resin may be used alone or in combination of two or more.

[0049] From the viewpoint of suppressing contamination of the surface layer, the resin contained in the surface layer is preferably polyamide, polyvinylidene fluoride resin, or tetrafluoroethylene resin, and more preferably polyamide. As the polyamide, from the viewpoint of suppressing contamination of the surface layer, alcohol-soluble polyamide is preferable, alkoxymethylated polyamide (for example, alkoxymethylated nylon) is more preferable, and methoxymethylated polyamide (for example, methoxymethylated nylon) is still more preferable.

[0050] From the viewpoint of the binding property of the non-conductive inorganic particles, the surface layer preferably contains polyvinyl butyral. An example of the embodiment of the surface layer contains polyamide and polyvinyl butyral as the binder resin. In this case, the mass ratio of the two is preferably polyamide:polyvinyl butyral = 95:5 to 65:35, more preferably 90:10 to 70:30, and still more preferably 85:15 to 75:25.

[0051] Examples of the conductive particles include carbon black; metal oxides such as tin oxide, titanium oxide, and zinc oxide; and the like. As the conductive particles contained in the surface layer, carbon black is preferred. The conductive particles may be used alone or in combination of two or more.

[0052] From the viewpoint of excellent dispersibility in the resin, the average primary particle size of the conductive particles contained in the surface layer is preferably 10 nm or more and 50 nm or less. The average primary particle size of the conductive particles is determined by observing the cross section of the surface layer with an electron microscope, measuring the major axis of 100 conductive particles, and calculating the arithmetic mean thereof.

[0053] The content of the conductive particles contained in the surface layer is preferably 5 parts by mass or more and 50 parts by mass or less, more preferably 8 parts by mass or more and 40 parts by mass or less, and still more preferably 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin.

[0054] The surface layer contains non-conductive inorganic particles for the purpose of enhancing the heat dissipation of the charged member. The non-conductive inorganic particles preferably have a thermal conductivity of 20 W / (m·K) or more, more preferably 30 W / (m·K) or more, and still more preferably 40 W / (m·K) or more. The thermal conductivity of the non-conductive inorganic particles may be, for example, 150 W / (m·K) or less, 120 W / (m·K) or less, or 100 W / (m·K) or less.

[0055] The measurement method of the thermal conductivity of the non-conductive inorganic particles is measured according to JIS R1611:2010 "Method for Measuring Thermal Diffusivity, Specific Heat Capacity, and Thermal Conductivity of Fine Ceramics by Flash Method". The sample holder of the measuring device is filled with the particles to be measured, and the bulk density is adjusted by applying a load according to the specifications of the measuring device. The measurement is performed in an environment of a temperature of 23°C and a relative humidity of 50%. The non-conductive inorganic particles to be used for measurement are either non-conductive inorganic particles that form a surface layer or non-conductive inorganic particles taken from the surface layer. There is no limitation on the method for extracting non-conductive inorganic particles from the surface layer. The method may be, for example, a method of immersing the surface layer peeled from the charged member in an organic solvent that dissolves the binder resin to dissolve the binder resin with the organic solvent and extract the non-conductive inorganic particles; a method of heating the surface layer peeled from the charged member to a high temperature to eliminate the binder resin and extract the non-conductive inorganic particles; and the like.

[0056] From the viewpoint of excellent thermal conductivity, fine ceramic particles are preferable as the non-conductive inorganic particles. Examples of the fine ceramic particles include nitride particles, oxide particles, carbide particles, and boride particles.

[0057] Examples of the nitride particles include particles of aluminum nitride, boron nitride, and silicon nitride. Examples of the oxide particles include particles of magnesium oxide and aluminum oxide. Examples of the carbide particles include particles of silicon carbide. Examples of the boride particles include particles of titanium boride, niobium boride, molybdenum boride, and the like. These particles may be used alone or in combination of two or more.

[0058] From the viewpoint of excellent thermal conductivity, at least one selected from the group consisting of nitride particles and oxide particles is preferable as the non-conductive inorganic particles, and at least one selected from the group consisting of aluminum nitride particles, boron nitride particles, and magnesium oxide particles is more preferable.

[0059] The non-conductive inorganic particles contained in the surface layer preferably have an average primary particle size of 5 μm or more and 20 μm or less, more preferably 5 μm or more and 15 μm or less, and still more preferably 5 μm or more and 10 μm or less. When the average primary particle size of the non-conductive inorganic particles is 5 μm or more, fine irregularities (i.e., discharge initiation points for discharging to the photosensitive layer) can be formed on the surface of the surface layer. When the average primary particle diameter of the non-conductive inorganic particles is 20 μm or less, cracks are less likely to occur in the surface layer. The average primary particle diameter of the non-conductive inorganic particles is determined by observing the cross-section of the surface layer with an electron microscope, measuring the major diameters of 100 non-conductive inorganic particles, and calculating the arithmetic mean.

[0060] The content of the non-conductive inorganic particles contained in the surface layer is 5 parts by mass or more and 40 parts by mass or less, preferably 10 parts by mass or more and 30 parts by mass or less, and more preferably 15 parts by mass or more and 25 parts by mass or less, based on 100 parts by mass of the resin, from the viewpoints of excellent heat dissipation of the surface layer and suppression of crack generation.

[0061] The surface layer may contain various additives. Examples of the additives include fillers, softeners, plasticizers, curing agents, antioxidants, coupling agents, surfactants, defoaming agents, leveling agents, and the like.

[0062] The layer thickness of the surface layer is preferably 1 μm or more and 25 μm or less, more preferably 3 μm or more and 20 μm or less, and still more preferably 5 μm or more and 15 μm or less. The layer thickness of the surface layer is measured by imaging the cross-section with an electron microscope. Four points are measured at 90° intervals in the circumferential direction at the center in the axial direction of the charged member, and the arithmetic mean value is taken as the layer thickness of the surface layer.

[0063] As a method of forming the surface layer on the elastic layer, for example, a surface layer forming composition in which a resin, conductive particles, non-conductive inorganic particles, and other additives are mixed is applied to the outer peripheral surface of the elastic layer to form a layer of the surface layer forming composition, and then the layer of the surface layer forming composition is dried. Examples of the method of applying the surface layer forming composition to the outer peripheral surface of the elastic layer include dipping coating, roll coating, blade coating, wire bar coating, spray coating, bead coating, air knife coating, curtain coating, and the like.

[0064] <Charging device, image forming device, process cartridge> The charging device according to this embodiment has a charging member according to this embodiment. The charging device according to this embodiment may be a charging device in which the charging member contacts the surface of the photoreceptor, or may be a charging device in which the charging member does not contact the surface of the photoreceptor. In the charging device in which the charging member contacts the surface of the photoreceptor, the effects achieved by this embodiment (less likely to generate density unevenness in the image and less likely to generate cracks on the surface of the charging member) are remarkable.

[0065] The image forming apparatus according to this embodiment includes a photoreceptor, a charging device that charges the surface of the photoreceptor, an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the photoreceptor, a developing device that develops the electrostatic latent image formed on the surface of the photoreceptor with a developer containing toner to form a toner image, and a transfer device that transfers the toner image onto the surface of a recording medium. And, as the charging device, a charging device having a charging member according to this embodiment is applied. The charging device may be a charging device in which the charging member contacts the surface of the photoreceptor, or may be a charging device in which the charging member does not contact the surface of the photoreceptor. In the charging device in which the charging member contacts the surface of the photoreceptor, the effects achieved by this embodiment (less likely to generate density unevenness in the image and less likely to generate cracks on the surface of the charging member) are remarkable.

[0066] In the image forming apparatus according to this embodiment, for example, the portion including the photoreceptor and the charging device may have a cartridge structure (that is, a process cartridge according to this embodiment) that is detachable from the image forming apparatus. The process cartridge may include at least one selected from the group consisting of, for example, an electrostatic latent image forming device, a developing device, and a transfer device, in addition to the photoreceptor and the charging device. The charging device may be a charging device in which the charging member contacts the surface of the photoreceptor, or may be a charging device in which the charging member does not contact the surface of the photoreceptor. In the charging device in which the charging member contacts the surface of the photoreceptor, the effects achieved by this embodiment (less likely to generate density unevenness in the image and less likely to generate cracks on the surface of the charging member) are remarkable.

[0067] The image forming apparatus according to the present embodiment includes an apparatus provided with a fixing device for fixing a toner image transferred onto the surface of a recording medium; an apparatus of a direct transfer method for directly transferring a toner image formed on the surface of a photoreceptor onto a recording medium; an apparatus of an intermediate transfer method for primarily transferring a toner image formed on the surface of a photoreceptor onto the surface of an intermediate transfer member and secondarily transferring the toner image transferred onto the surface of the intermediate transfer member onto the surface of a recording medium; an apparatus provided with a cleaning device for cleaning the surface of the photoreceptor after transfer of the toner image and before charging; an apparatus provided with a charge eliminating device for eliminating charge by irradiating the surface of the photoreceptor with charge eliminating light after transfer of the toner image and before charging; an apparatus provided with a photoreceptor heating member for raising the temperature of the photoreceptor and reducing the relative humidity; and the like, and known image forming apparatuses are applicable.

[0068] In the case of an apparatus of the intermediate transfer method, the transfer apparatus is configured to include, for example, an intermediate transfer member onto which a toner image is transferred on the surface, a primary transfer device for primarily transferring a toner image formed on the surface of the photoreceptor onto the surface of the intermediate transfer member, and a secondary transfer device for secondarily transferring the toner image transferred onto the surface of the intermediate transfer member onto the surface of a recording medium.

[0069] The image forming apparatus according to the present embodiment may be either a dry developing method image forming apparatus or a wet developing method (developing method using a liquid developer) image forming apparatus.

[0070] Hereinafter, an example of the image forming apparatus according to the present embodiment is shown, but the present invention is not limited thereto. The main parts shown in the drawings will be described, and the description of the others will be omitted.

[0071] FIG. 3 is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment. As shown in FIG. 3, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300, an exposure device 9 (an example of an electrostatic latent image forming device), a transfer device 40 (a primary transfer device), and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where it can expose the photosensitive member 7 from the opening of the process cartridge 300, the transfer device 40 is disposed at a position facing the photosensitive member 7 via the intermediate transfer member 50, and a part of the intermediate transfer member 50 is disposed in contact with the photosensitive member 7. Although not shown, the image forming apparatus also has a secondary transfer device that transfers the toner image transferred to the intermediate transfer member 50 to a recording medium (e.g., paper). The intermediate transfer member 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer device.

[0072] In FIG. 3, the process cartridge 300 integrally supports a photosensitive member 7, a charging device 8, a developing device 11, and a cleaning device 13 within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is disposed so as to contact the surface of the photosensitive member 7. The cleaning member may be a conductive or insulating fibrous member instead of the form of the cleaning blade 131, and this may be used alone or in combination with the cleaning blade 131.

[0073] FIG. 3 shows an example of an image forming apparatus including a fibrous member 132 (in a roll shape) that supplies a lubricant 14 to the surface of the photosensitive member 7 and a fibrous member 133 (in a flat brush shape) that assists in cleaning, but these are disposed as needed.

[0074] Hereinafter, each component of the image forming apparatus according to the present embodiment will be described.

[0075] - Photosensitive member - The photosensitive member 7 has, for example, a structure in which an undercoat layer and a photosensitive layer are laminated in this order on a conductive substrate. The photosensitive layer may be a single-layer photosensitive layer or a laminated photosensitive layer composed of a charge generation layer and a charge transport layer.

[0076] - Charging device - The charging device 8 has a charging member according to this embodiment. The charging device 8 may be a charging device in which the charging member contacts the surface of the photoreceptor, or a charging device in which the charging member does not contact the surface of the photoreceptor. The charging device 8 may be any of the following: a charging device that applies only a DC voltage to the charging member (DC charging method); a charging device that applies only an AC voltage to the charging member (AC charging method); a charging device that applies a voltage obtained by superimposing an AC voltage on a DC voltage to the charging member (AC / DC charging method).

[0077] - Exposure device - Examples of the exposure device 9 include optical system devices that expose the surface of the photoreceptor 7 with light such as semiconductor laser light, LED light, and liquid crystal shutter light in a defined image pattern. The wavelength of the light source is within the spectral sensitivity region of the photoreceptor. As the wavelength of the semiconductor laser, near-infrared light having an oscillation wavelength near 780 nm is the mainstream. However, it is not limited to this wavelength, and lasers having an oscillation wavelength in the 600 nm range or lasers having an oscillation wavelength of 400 nm or more and 450 nm or less as blue lasers may also be used. Also, for color image formation, a surface-emitting type laser light source of a type capable of outputting multi-beams is also effective.

[0078] - Developing device - Examples of the developing device 11 include general developing devices that develop by bringing the developer into contact or non-contact. The developing device 11 is not particularly limited as long as it has the above-described functions, and is selected according to the purpose. For example, known developers having a function of adhering a one-component developer or a two-component developer to the photoreceptor 7 using a brush, a roller, or the like can be mentioned. Among them, those using a developing roller that holds the developer on its surface are preferable.

[0079] The developer used in the developing device 11 may be a one-component developer composed of toner alone, or a two-component developer containing toner and carrier. Also, the developer may be magnetic or non-magnetic. Known developers are applied to these.

[0080] - Cleaning device - The cleaning device 13 uses a cleaning blade type device equipped with a cleaning blade 131. In addition to the cleaning blade type, a fur brush cleaning method or a simultaneous development and cleaning method may be adopted.

[0081] -Transfer device- As the transfer device 40, for example, known transfer chargers such as a contact type transfer charger using a belt, roller, film, rubber blade, etc., a scorotron transfer charger using corona discharge, or a corotron transfer charger can be mentioned.

[0082] -Intermediate transfer member- As the intermediate transfer member 50, a belt-shaped one (intermediate transfer belt) containing polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. with semiconductive properties is used. Also, as the form of the intermediate transfer member, a drum-shaped one may be used in addition to the belt-shaped one.

[0083] FIG. 4 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment. The image forming apparatus 120 shown in FIG. 4 is a tandem type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged in parallel on the intermediate transfer member 50, and one photosensitive member is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100 except that it is of the tandem type.

Examples

[0084] Hereinafter, embodiments of the invention will be described in detail with reference to examples, but the embodiments of the invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are based on mass. In the following description, unless otherwise specified, synthesis, production, processing, measurement, etc. were carried out at normal temperature (25°C ± 3°C).

[0085] <Manufacture of Charging Roll> [Example 1] -Preparation of Support Member- A support member with a diameter of 8 mm, which was obtained by subjecting a SUM22-made cylindrical member to electroless nickel plating with a thickness of 5 μm, was prepared.

[0086] -Formation of Adhesive Layer- · Chlorinated polypropylene resin (maleic anhydride chlorinated polypropylene resin, Super Cron 930, Nippon Paper Chemicals Co., Ltd.): 100 parts · Epoxy resin (EP4000, ADEKA Corporation): 10 parts · Conductive agent: Carbon black (Ketjen Black EC, Ketjen Black International Co., Ltd.): 2.5 parts · Toluene: Appropriate amount The above materials were mixed and processed using a ball mill for 1 hour to obtain a resin composition. The resin composition was brush-coated on the surface of the support member to form an adhesive layer with a thickness of 10 μm.

[0087] -Formation of Elastic Layer- · Epichlorohydrin rubber (Gechron 3106, Nippon Zeon Co., Ltd.): 100 parts · Electronic conductive agent: Carbon black (Asahi #60, Asahi Carbon Co., Ltd.): 10 parts · Ion conductive agent: Benzyltriethylammonium chloride (Lion Corporation): 5 parts · Calcium carbonate (Whiton SB, Shiraishi Calcium Co., Ltd.): 20 parts · Vulcanizing agent: Sulfur (Paranox R, Ouchi Shinko Chemical Industry Co., Ltd.): 1 part · Vulcanization accelerator: Stearic acid (NOF Corporation): 1 part · Vulcanization accelerator: Zinc oxide: 1.5 parts The above materials were mixed, kneaded using a tangential pressure kneader, passed through a strainer to obtain a rubber composition. The rubber composition was kneaded on an open roll and formed into a roll shape using a molding machine on the surface of the adhesive layer. Then, it was heated in a heating furnace at a temperature of 175 °C for 70 minutes to obtain an elastic layer. The elastic layer was polished to obtain a conductive elastic roll with a diameter of 14 mm.

[0088] -Formation of Surface Layer- · Resin: N-methoxymethylated nylon (F30K, Nagase ChemteX Corporation): 80 parts · Resin: Polyvinyl butyral (Esrec BL-1, Sekisui Chemical Co., Ltd.): 20 parts · Conductive particles: Carbon black (MONAHRCH1000, Cabot Corporation): 12 parts · Non-conductive particles: Aluminum nitride particles (AIN050AW, ThroughTek Corporation): 8 parts · Additive: Dimethylpolysiloxane (BYK-307, BYK-Chemie Japan Co., Ltd.): 0.8 part The above materials were mixed, diluted with methanol / 1-propanol, and dispersed using a bead mill. The resulting dispersion was dip-coated on the surface of the conductive elastic roll in an environment at a temperature of 24°C and a relative humidity of 45%, and then heated and dried at 130°C for 30 minutes to form a surface layer with a thickness of 10 μm. Thus, the charged roll of Example 1 was obtained.

[0089] [Comparative Example 1] In the same manner as in Example 1, except that the non-conductive particles were changed to polyamide particles (Orgasol, Arkema Corporation) and used in the amounts shown in Table 1 (parts per 100 parts by mass of the resin), a charged roll was manufactured.

[0090] [Examples 2 - 3, Comparative Examples 2 - 3] In the same manner as in Example 1, except that the amount of aluminum nitride particles added (parts per 100 parts by mass of the resin) was changed as shown in Table 1, a charged roll was manufactured.

[0091] [Examples 4 - 6] In the same manner as in Example 1, except that the non-conductive particles were changed to boron nitride particles (PT620, Momentive Performance Materials Inc.) and used in the amounts shown in Table 1 (parts per 100 parts by mass of the resin), a charged roll was manufactured.

[0092] [Examples 7 - 9] In the same manner as in Example 1, except that the non-conductive particles were changed to magnesium oxide particles (RF-10C-AC, Ube Materials Co., Ltd.) and used in the amounts shown in Table 1 (parts per 100 parts by mass of the resin), a charged roll was manufactured.

[0093] [Example 10] In the same manner as in Example 1, except that the non-conductive particles were changed to aluminum oxide particles (DAW-03, Denka Co., Ltd.) and used in the amounts shown in Table 1 (parts per 100 parts by mass of the resin), a charged roll was manufactured.

[0094] [Examples 11 to 13] In the same manner as in Example 1, except that the non-conductive particles were changed to aluminum nitride particles having different particle sizes and used in the amounts shown in Table 1 (parts per 100 parts by mass of the resin), a charged roll was manufactured. The aluminum nitride particles used in Examples 11 to 13 are as follows. The average primary particle size of each aluminum nitride particle is shown in Table 1. · Example 11: AIN020AW, ThroughTek · Example 12: AIN0300AW, ThroughTek · Example 13: AIN0200AW, ThroughTek

[0095] [Performance Evaluation of Charged Member] [Thermal Conductivity] From the central portion in the axial direction of the charged roll, a portion from the elastic layer to the surface layer was cut out to a size of 5 mm in the axial direction × 2 mm in the circumferential direction and used as a sample. At room temperature (25°C ± 3°C), the sample was placed on the probe of a thermal diffusivity measuring device ai-Phase Mobile (AiPhase Co., Ltd.), a 100 gf weight was placed, and three measurements were taken under the conditions of manual mode, voltage 1.41 V, frequency 1 Hz to 10 Hz (10 divisions), and measurement time 2 seconds, and the average value was calculated.

[0096] [Concentration Non-uniformity] The manufactured charged roll was installed in an image forming apparatus Apeos C2360 (Fuji Film Business Innovation Co., Ltd.). In an environment with a temperature of 28°C and a relative humidity of 80%, 400,000 black half-tone images with a density of 50% were output on one side of the entire surface of A3-sized plain paper. Subsequently, in an environment with a temperature of 10°C and a relative humidity of 15%, one black half-tone image with a density of 30% was output on one side of the entire surface of A3-sized plain paper. The image density was measured at one central point and four end points of the black half-tone image with a density of 30% using a reflection densitometer X-Rite 404A (manufactured by X-Rite). The difference between the maximum value and the minimum value of the image density was calculated and classified as follows. 1: The difference in image density is less than 0.3. 2: The difference in image density is 0.3 or more and 1.0 or less. Acceptable range. 3: The difference in image density exceeds 1.0. Not acceptable.

[0097] [Crack] After evaluating the density unevenness, the surface of the charging roll was observed with an optical microscope. The presence or absence of cracks and the crack width were classified as follows. 0: No cracks. 1: There are cracks, the crack width is less than 10 μm, and the crack length is less than 0.5 mm. 2: There are cracks, the crack width is less than 10 μm, and the crack length is 0.5 mm or more. 3: There are cracks with a crack width of 10 μm or more.

[0098]

Table 1

[0099] The charging member, charging device, process cartridge, and image forming apparatus of the present disclosure include the following aspects.

[0100] (Appended Note) (((1))) It has a support member, an elastic layer provided on the support member, and a surface layer provided on the elastic layer, The surface layer contains a resin, conductive particles, and non-conductive inorganic particles, The surface layer contains 5 parts by mass or more and 40 parts by mass or less of the non-conductive inorganic particles with respect to 100 parts by mass of the resin. Charging member. (((2))) The charging member according to (((1))), wherein the non-conductive inorganic particles have a thermal conductivity of 40 W / (m·K) or more. (((3))) The charging member according to (((1))) or (((2))), wherein the non-conductive inorganic particles contain at least one selected from the group consisting of nitride particles, oxide particles, carbide particles, and boride particles. (((4))) The charging member according to any one of (((1))) to (((3))), wherein the non-conductive inorganic particles contain at least one selected from the group consisting of aluminum nitride particles, boron nitride particles, and magnesium oxide particles. (((5))) The charging member according to any one of (((1))) to (((4))), wherein the average primary particle diameter of the non-conductive inorganic particles is 5 μm or more and 20 μm or less. (((6))) Charging device having the charging member according to any one of (((1))) to (((5))). (((7))) Photoreceptor, A charging device having the charging member according to any one of (((1))) to (((5))) and charging the photoreceptor, Process cartridge detachable from an image forming apparatus. (((8))) Photoreceptor, A charging device having the charging member according to any one of (((1))) to (((5))) and charging the photoreceptor, An electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged photoreceptor, A developing device for developing the electrostatic latent image formed on the surface of the photoreceptor with a developer containing toner to form a toner image, A transfer device for transferring the toner image to the surface of a recording medium, Image forming apparatus comprising the same.

[0101] According to ((1)), ((3)), or ((4)), a charging member is provided in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared to a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin. According to ((2)), a charging member is provided in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared to a charging member in which the thermal conductivity of the non-conductive inorganic particles contained in the surface layer is less than 40 W / (m·K). According to ((5)), a charging member is provided in which cracks are less likely to occur on the surface, as compared to a charging member in which the average particle diameter of the non-conductive inorganic particles contained in the surface layer is more than 20 μm. According to ((6)), a charging device is provided including a charging member in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared to a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin. According to ((7)), a process cartridge is provided including a charging member in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared to a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin. According to ((8)), an image forming apparatus is provided including a charging member in which density unevenness is less likely to occur in an image and cracks are less likely to occur on the surface, as compared to a charging member in which the surface layer contains less than 5 parts by mass or more than 40 parts by mass of non-conductive inorganic particles with respect to 100 parts by mass of the resin.

Explanation of Reference Numerals

[0102] 30 Charging member, 32 Support member, 34 Elastic layer, 36 Surface layer

[0103] 7 Photoreceptor, 8 Charging device, 9 Exposure device, 11 Developing device, 13 Cleaning device, 14 Lubricant, 40 Transfer device, 50 Intermediate transfer body, 100 Image forming device, 120 Image forming device, 131 Cleaning blade, 132 Fibrous member (roll shape), 133 Fibrous member (flat brush shape), 300 Process cartridge

Claims

1. A support member, an elastic layer provided on the support member, and a surface layer provided on the elastic layer, the surface layer contains a resin, conductive particles, and non-conductive inorganic particles; The surface layer contains the non-conductive inorganic particles in an amount of 5 parts by mass or more and 40 parts by mass or less relative to 100 parts by mass of the resin. Charged member.

2. 2. The charging member according to claim 1, wherein the non-conductive inorganic particles have a thermal conductivity of 40 W / (m·K) or more.

3. 2. The charging member according to claim 1, wherein the non-conductive inorganic particles include at least one kind selected from the group consisting of nitride particles, oxide particles, carbide particles and boride particles.

4. 2. The charging member according to claim 1, wherein the non-conductive inorganic particles include at least one selected from the group consisting of aluminum nitride particles, boron nitride particles, and magnesium oxide particles.

5. 2. The charging member according to claim 1, wherein the non-conductive inorganic particles have an average primary particle size of 5 [mu]m or more and 20 [mu]m or less.

6. A charging device comprising the charging member according to any one of claims 1 to 5.

7. A photoconductor; a charging device having the charging member according to any one of claims 1 to 5 and configured to charge the photoconductor; A process cartridge that is detachably attached to an image forming apparatus.

8. A photoconductor; a charging device having the charging member according to any one of claims 1 to 5 and configured to charge the photoconductor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the photoconductor; a developing device for developing the electrostatic latent image formed on the surface of the photoconductor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

Images