BACKGROUND

[0001 ] Some image forming apparatuses include a photoreceptor, a charging device, an exposure device which forms an electrostatic latent image on the photoreceptor, a development device which applies a toner onto the electrostatic latent image to develop a toner image, and a transfer device to transfer the toner image formed on the photoreceptor to a transfer material. The charging device includes a charging member to charge the photoreceptor.

BRIEF DESCRIPTION OF DRAWINGS

[0002] FIG. 1 is a schematic cross-sectional view of an example charging member.

FIG. 2 is a schematic cross-sectional view illustrating an enlarged portion of the example charging member of FIG. 1 .

FIG. 3 is a schematic cross-sectional view illustrating an enlarged portion of the example charging member of FIG. 1 .

FIG. 4 is a schematic cross-sectional view illustrating an enlarged portion of the example charging member of FIG. 1 including a coating layer portion.

FIG. 5 is a plan view photograph of a coating layer of a Test Example

1.

DETAILED DESCRIPTION

[0003] Hereinafter, examples of a charging member will be described with reference to the drawings. In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted. In addition, the dimensional ratio of each constituent is not limited to the illustrated ratio. In addition, a value noted with ''approximately" indicates a range including the value and the vicinity of the value. Accordingly, the value indicated with "approximately", in some examples, may correspond to the exact value (excluding "approximately"). In addition, a numerical range indicated by using "to" indicates a range including numerical values before and after "to" as the minimum value and the maximum value, respectively.

[0004] Charging Member and Image Forming Apparatus

A charging member includes a conductive support and a conductive body mounted on the conductive support. The conductive body includes an elastic layer located on the conductive support, a resin layer located on the elastic layer, and a coating layer located on the resin layer to form the outermost surface of the conductive body. Hereinafter, an example of the charging member will be described.

[0005] With reference to FIG. 1 , the example charging member is a charging roller 10 forms a conductive body 5that includes a conductive support 1 extending along a rotation axis of the conductive body 5. The conductive body 5 is in the shape of a roller to rotate about a rotation axis line L of the support 1 . The conductive body 5 is rotationally symmetric about the rotation axis line L.

[0006] The conductive body 5 includes a conductive base 6 including an elastic layer having conductivity (a conductive elastic layer) 2 that is in contact with the outer circumferential surface of the conductive support 1 and a resin layer having conductivity (a conductive resin layer) 3 that is in contact with the outer circumferential surface of the elastic layer 2, and a coating layer having insulating properties (an insulating coating layer) 4 that is in contact with the outer circumferential surface of the resin layer 3. The resin layer 3 may be located around the elastic layer 2 via one or more other layers. For example, an intermediate layer such as a resistance adjustment layer for increasing voltage resistance (leakage resistance) may be interposed between the elastic layer 2 and the resin layer 3. In addition, the coating layer 4 may be located around the resin layer 3 via the other layers. However, for example, an oriented state of a polysiloxane compound (for example, a polysiloxane compound having a silicone structure or the like) in the coating layer 4 described below may be changed in accordance with a layer in contact with the coating layer 4, and thus, a physical state (an irregular state) and chemical properties (surface free energy or the like) of the outermost surface may be changed. In a case where the coating layer 4 is formed to be directly in contact with the outer circumferential surface of the resin layer 3, contamination on the surface of the conductive body 5 due to the contact with a photoreceptor (for example, contamination due to an external additive) is more easily suppressed.

[0007] Conductive Support

The conductive support 1 may be any suitable conductive support that is formed of a metal having conductivity. In some examples, conductive support 1 may be a hollow body (e.g., in the shape of a pipe or of a circular tube), a solid body (e.g., in the shape of a rod), or the like that is formed of a metal including iron, copper, aluminum, nickel, stainless steel, and the like. The outer circumferential surface of the conductive support 1 may be subjected to a plating treatment, in some examples, in order to rustproof the conductive support 1 , or to impart scratch resistance to the extent that the conductivity is not impaired. In addition, the outer circumferential surface of the conductive support 1 may be coated with an adhesive agent, a primer, or the like, according to examples, in order to increase adhesiveness with respect to the eiastic layer 2. In such cases, the adhesive agent, the primer, or the like may be selected to have a suitable conductivity, in order to provide sufficient conductivity,

[0008] The conductive support 1 , for example, may be in the shape of a cylinder having a length of approximately 250 mm to 360 mm. A portion of the conductive support 1 that is covered with the elastic layer 2, for example, is formed into the shape of a cylinder or a circular tube that extends along a rotation axis line L direction of the conductive support 1 (an extending direction of the conductive support 1 ), and may have a diameter (an outer diameter) that is constant in the rotation axis line L direction (in the shape of a straight cylinder or a straight circular tube). The diameter of the portion of the conductive support 1 that is covered with the elastic layer 2, for example, may be approximately 8 mm or more, and may be approximately 10 mm or less.

[0009] A portion of the conductive support 1 that is not covered with the elastic layer 2, namely, opposite end portions of the conductive support 1 are supported by a support member. In some examples, the diameter of the portion of the conductive support 1 that is not covered with the elastic layer 2 may be less than the diameter of the portion that is covered with the elastic layer 2. The conductive support 1 rotates about the rotation axis line (a center line of a cylinder) L of the conductive support 1 , in a state of being supported on the support member.

[0010] The conductive support 1 is biased (or urged) toward a photoreceptor such that the surface of the coating layer 4 is in contact with the surface of the photoreceptor. Namely, in order to push the surface of the coating layer 4 against the surface of the photoreceptor, respective loads may be applied to the opposite end portions of the conductive support 1 toward the photoreceptor. In order to achieve a more suitable coherence of the charging roller 10 with respect to the rotating photoreceptor, a toad to be applied to each of the end portions of the conductive support 1 , may be approximately 450 g or more, and may be approximately 750 g or less, depending on examples.

[0011 ] Elastic Layer

The elastic layer 2 may be any suitable elastic layer that has a suitable elasticity in order to provide uniform cohesiveness with respect to the photoreceptor. The elastic layer 2, for example, may be formed by using: natural rubber; synthetic rubber such as ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, a polyurethane-based elastomer, epichlorohydrin rubber, isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (H-NBR), and chloroprene rubber (CR); a synthetic resin such as a polyamide resin, a polyurethane resin, and a silicone resin; and the like. Namely, the elastic layer 2 may include an elastic body containing such base polymers or cross-linked bodies thereof. In some examples, a single type of the materials may be used, and in other examples, two or more types thereof may be used in combination. In order to achieve a more uniform cohesiveness with respect to the photoreceptor, the base polymer may contain a rubber component (natural rubber or synthetic rubber) as a main component. Namely, the base polymer may contain approximately 50 mass% or more of the rubber component, according to some examples, and may contain approximately 80 mass% or more of the rubber component, in other examples.

[0012] In the base polymer, additives such as a conductive agent, a vulcanizing agent, a vulcanization promoter, a lubricant, and an auxiliary agent may be suitably compounded, according to examples, in order to impart suitable properties to the elastic layer 2. In some examples, in order to form a more stable resistance, the elastic layer 2 (the elastic body) may contain epichlorohydrin rubber and a cross-linked body thereof as a main component. Namely, the elastic layer 2 may contain approximately 50 mass% or more of epichlorohydrin rubber or the cross-linked body thereof, in some examples, and may contain approximately 80 mass% or more of epichlorohydrin rubber or the cross-linked body thereof in other examples.

[0013] Examples of the conductive agent include carbon black, graphite, potassium titanate, iron oxide, conductive titanium oxide (c-TiO2), conductive zinc oxide (c-ZnO), conductive tin oxide (c-SnO2), quaternary ammonium salt, and the like. Sulfur and the like may be used as the vulcanizing agent. Tetramethyl thiuram disulfide (CZ) and the like may be used as the vulcanization promoter. A stearic acid and the like may be used as the lubricant. Zinc flower (ZnO) and the like may be used as the auxiliary agent.

[0014] According to examples, the thickness of the elastic layer 2 may be approximately 1.25 mm or more, and may be approximately 3.00 mm or less, in order to exhibit suitable elasticity.

[0015] Resin Layer

The resin layer 3 contains a resin, and is a layer harder (for example, having a greater elastic modulus that is measurable on the basis of JIS K7162) than the elastic layer. The resin layer 3 is located on the elastic layer 2, so as to suppress the bleeding of a plasticizer or the like from the elastic layer 2 to the surface of the conductive body 5.

[0016] According to examples, the resin layer 3 may contain a matrix material, and particles dispersed in the material. The resin layer 3 contains the particles, and thus, has an irregular shape on the surface. The particles may include a single type of particles, or may include two or more types of particles, according to examples. For example, the resin layer 3, as illustrated in FIG. 2, may be a layer containing a matrix material 30, and first particles 31 dispersed in the material, or as illustrated in FIG. 3, may be a layer containing the matrix material 30, the first particles 31 and second particles 32 having a type different from that of the first particles 31 , which are dispersed in the material. Such different types refer to different materials, different shapes, and the like. For example, even in a case where the material of the first particles 31 and the material of the second particles 32 are identical to each other, the first particles 31 and the second particles 32 are considered to be of different types in a case where the shapes thereof are different from each other.

[0017] According to examples, the matrix material may contain a base polymer. For example, a polymer such as a fluorine resin, a polyamide resin, an acrylic resin, a nylon resin, a polyurethane resin, a silicone resin, a butyral resin, a styrene-ethylene-butylene-olefin copolymer (SEBC), and an olefin-ethylene butylene-olefin copolymer (CEBC) may be used as the base polymer. A single type of the materials may be used, or two or more types thereof may be used together. For example, in order to increase ease of handling, the freedom degree of material design (e.g., the range of materials that may be selected), or the like, the base polymer may be of at least one type selected from the group consisting of a fluorine resin, an acrylic resin, a nylon resin, a polyurethane resin, and a silicone resin, according to some examples, or may be of at least one type selected from the group consisting of a nylon resin and a polyurethane resin according to other examples.

[0018] The content of the base polymer in the resin layer, for example, may be approximately 30 mass% or more, and may be approximately 90 mass% or less, relative to the total amount of the resin layer.

[0019] According to examples, the matrix material may further contain various conductive agents (conductive carbon, graphite, copper, aluminum, nickel, an iron powder, conductive tin oxide, conductive titanium oxide, an ion conductive agent, and the like), a charging control agent, and the like.

[0020] The particles (for example, the first particles 31 and the second particles 32) may be insulating particles. The particles may be resin particles, or may be inorganic particles. The particles may be any suitable particles that are capable of forming irregularity with respect to the surface of the resin layer in order to sufficiently provide a discharge point. Examples of the material of the resin particles include a urethane resin, a polyamide resin, a fluorine resin, a nylon resin, an acrylic resin, a urea resin, and the like. Examples of the material of the inorganic particles include silica, alumina, and the like. A single type of the materials may be used in some examples, or two or more types thereof may be used in combination in other examples. In order to increase compatibility with respect to the matrix material 30, dispersion retainability after the particles are added, stability after forming a coating material (pot life), or the like, the particles may be of at least one type selected from the group consisting of nylon resin particles, acrylic resin particles, and polyamide resin particles, or may be of at least one type selected from the group consisting of nylon resin particles and acrylic resin particles.

[0021 ] The shape of the particles (for example, the first particles 31 and the second particles 32) may be any suitable shape that forms an irregularity with respect to the surface of the resin layer 3. According to examples, the shape may be a spherical shape and an ovoidal shape, an amorphous shape, and the like.

[0022] The content of the particles (for example, the total amount of the first particles 31 and the second particles 32), for example, may be approximately 5 mass% to 50 mass%, relative to the total mass of the resin layer. The charging performance tends to be more easily satisfied by setting the content of the particles to be approximately 5 mass% or more, and the control of particle precipitation at the time of being a coating material is further facilitated and coating material stability is better maintained by setting the content of the particles to be approximately 50 mass% or less. From the same viewpoint, the content of the particles may be approximately 10 mass% to 40 mass%, in some examples, or may be approximately 20 mass% to 30 mass%, in other examples, relative to the total mass of the resin layer. The content of the particles contained in the resin layer, for example, can be quantified by sampling the resin layer from the charging member, and by measuring a weight change (TG), differential heat (DTA), calory (DSC), and the mass (MS) of a volatile component, which occur by heating the sampled resin layer (TG-DTA-MS, DSC (heat analysis)).

[0023] In a case where the particles include the first particles 31 and the second particles 32, a ratio of the content of the first particles 31 to the content of the second particles 32, for example, may be approximately 5 : 1 to 1 : 5, or may be approximately 3 : 1 to 1 : 3, in order to more easily achieve suitable charging performance.

[0024] With reference to FIGS. 2 and 3, in the resin layer 3, a layer thickness A of a portion not containing the particles, for example, a portion containing the matrix material 30 exclusively (e.g., a portion not containing the first particles 31 and the second particles 32), may be within a range having a minimum of approximately 1.0 μm in some examples, of approximately 2.0 μm in other examples, or of approximately 3.0 μm or in yet other examples, and having a maximum of approximately 7.0 μm in some examples, of approximately 6.0 μm in other examples, or of approximately 5.0 μm in yet other examples. In a case where the resin layer 3 contains the particles, the layer thickness A corresponds to a thickness of the resin layer 3 at a middle point between the nearest particles. By setting the layer thickness A to be approximately 1.0 μm or more, the resin particles to be added are more easily continuously retained without having any dropout of the resin particles for a long period of time. By setting the layer thickness A to be approximately 7.0 μm or less, the charging performance is more easily excellently maintained. The layer thickness A may be measured by cutting out a sectional surface of the conductive body 5 with a sharp blade, and by observing the sectional surface with an optical microscope or an electronic microscope.

[0025] In a case where the particles correspond to the first particles 31 exclusively, the average of particle diameters (e.g., an average particle diameter B in FIG. 2) of the first particles 31 may be approximately 5.0 μm to 50.0 μm, in order to suppress charging unevenness which is an initial image defect. From the same viewpoint, the average particle diameter B of the first particles 31 may be approximately 15.0 μm to 30.0 μm in some examples. The average particle diameter of the particles can be derived by extracting 100 particles randomly, from a population of a plurality of particles with SEM observation, and by obtaining an average value of particle diameters. However, in a case where a particle shape is not a spherical shape, but rather a shape having a variable diameter or non-uniform dimensions, such as an ovoidal shape (having an oval cross-section) or an amorphous shape, an average value of the longest diameter (or longest transverse dimension) and the shortest diameter (or shortest transverse dimension) may be considered as the particle diameter of the particles.

[0026] In a case where the resin layer 3 contains the first particles 31 and the second particles 32, the average of the particle diameters (e.g., an average particle diameter B in FIG. 3) of the first particles 31 may be approximately 15.0 μm to 40.0 μm, in order to suppress the charging unevenness which is the initial image defect, and the average of particle diameters (e.g., an average particle diameter C in FIG. 3) of the second particles 32 may be approximately 15.0 μm or more, and may be approximately 40.0 μm or less, in order to suppress the charging unevenness which is the initial image defect. In order to suppress the charging unevenness, the average particle diameter B of the first particles 31 may be greater than the average particle diameter C of the second particles 32. In some examples, the average particle diameter B of the first particles 31 may be greater than the average particle diameter C of the second particles 32 by approximately 10 μm or more.

[0027] A ratio (B/A) of the average particle diameter B of the first particles 31 to the layer thickness A of the resin layer 3 may be approximately 5.0 to 30.0. The ratio B/A may be set to approximately 5.0 or more, to achieve a more suitable charging evenness, and may be further set to approximately 30.0 or less, in order to achieve suitable coating properties of a coating liquid for forming a conductive resin layer and to suppress the particle dropout. From the same viewpoint, B/A may be approximately 7.5 to 20.0 in some examples, or may be approximately 8.0 to 12.5 in other examples.

[0028] An interparticle distance of the particles (namely, an interparticle distance of all of the particles including the first particles 31 and the second particles 32 included in accordance with a case) may be approximately 50 μm to 400 μm. Surface roughness of the conductive resin layer and particle dropout are more easily suppressed by setting the interparticle distance to be approximately 50 μm or more, and the particle dropout is more easily suppressed by setting the interparticle distance to be approximately 400 μm or less. From the same viewpoint, the interparticle distance may be approximately 75 μm to 300 μm in some examples, or may be approximately 100 μm to 250 μm in other examples. The interparticle distance can be measured on the basis of JIS B0601-1994.

[0029] According to examples, the resin layer 3 may be formed by impregnating the surface of the originally existing elastic layer with a solution containing an isocyanate compound, and then, by curing the solution. In this case, a cured portion on the surface side of the originally existing elastic layer is the resin layer 3, and other cured portions are the elastic layer 2. In such a method, the elastic layer may be formed by grinding, and thus, the irregularity may be formed on the surface of the elastic layer (the surface of the resin layer 3 to be formed after the solution impregnation). Accordingly, a skewness (Rsk) and a ten-point average roughness (Rzjis) of the outermost surface of the conductive body 5 can be adjusted in the following range.

[0030] The isocyanate compound, for example, may be 2,6-tolylene diisocyanate (TDI), 4,4'-diphenyl methane diisocyanate (MDI), paraphenylene diisocyanate (PPDI), 1 ,5-naphthalene diisocyanate (NDI), and 3,3-dimethyl diphenyl-4,4'-diisocyanate (TODI), multimers and modified bodies thereof, and the like.

[0031 ] A solvent of the solution containing the isocyanate compound may be any suitable solvent that is an organic solvent in which the isocyanate compound can be dissolved. The organic solvent may be ethyl acetate or the like, according to examples. The solution may further contain carbon black, at least one type of polymer selected from an acrylic fluorine-based polymer and an acrylic silicone-based polymer, a conductivity imparting agent, and the like.

[0032] The resin layer formed by impregnating the elastic layer with the solution containing the isocyanate compound, and then, by curing the solution, for example, may contain the elastic body configuring the elastic layer 2, and a resin derived from the isocyanate compound.

[0033] The elastic body may be formed of a base polymer containing acrylonitrile-butadiene rubber (NBR) or epichlorohydrin rubber as a main component, in order to impart suitable binding properties with respect to the resin derived from the isocyanate compound. Namely, the base polymer may contain 50 mass% or more of acrylonitrile-butadiene rubber (NBR) or epichlorohydrin rubber in some examples, or may contain 80 mass% or more of acrylonitrile-butadiene rubber (NBR) or epichlorohydrin rubber in other examples, [0034] According to examples, the resin derived from the isocyanate compound, may be a resin having a urea bond, a urethane bond, or the like (a urea resin, a urethane resin, or the like). The resin derived from the isocyanate compound may be bonded to the base polymer and/or the cross-linked body in the elastic body by a urethane bond or the like.

[0035] In a case where the resin layer 3 is formed by the above method for impregnating the elastic layer with the solution containing the isocyanate compound, the thickness of the resin layer 3 may be within a range having a minimum of 1.0 μm in some examples, of 10.0 μm in other examples, or of 20.0 μm in yet other examples, and having a maximum of 250.0 μm in some examples, of 200.0 μm in other examples, or of 150.0 μm in yet other examples. [0036] Coating Layer

The coating layer 4 may contain a polysiloxane compound. The surface of the coating layer 4 containing the polysiloxane compound is located on the resin layer 3 to form an outermost surface S of the conductive body 5, and thus, the contamination on the surface of the conductive body 5 due to the contact with the photoreceptor (for example, the contamination due to the external additive) is suppressed. For example, in a case where the photoreceptor is downsized (reduced in size) and the number of rotations of the charging roller 10 increases or in a case where the image forming apparatus does not include a cleaning charge roller (CCR) for removing the external additive attached to the charging roller 10, the contamination of the charging roller 10 due to the external additive may tend to occur easily. Since the example charging roller 10 includes the coating layer 4, even in the case described above, the contamination due to the external additive is prevented. Here, the "polysiloxane compound" indicates a compound having a plurality of Si-O-Si bonds (siloxane bonds) in the molecular structure. Three or four oxygen atoms may be bonded to Si configuring the Si-O-Si bond.

[0037] The polysiloxane compound, for example, has a Si-O-Zr bond in the molecular structure. The Si-O-Zr bond, for example, is a bond to be formed between a zirconium chelate compound and a hydrolyzable silane compound at the time of polymerizing (self-condensing) the hydrolyzable silane compound in the presence of the zirconium chelate compound. Si configuring the Si-O-Zr bond can be the same as Si configuring the Si-O-Si bond. Three or four oxygen atoms may be bonded to Si configuring the Si-O-Zr bond.

[0038] The polysiloxane compound may have a cross-linking structure derived from an epoxy group, in order to achieve a suitable surface hardness. Namely, the polysiloxane compound may have a structural unit represented by Formula (1) or (2) described below.

[0039] In Formula (1 ), R ¹ to R ³ each independently indicates one among a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a carboxyl group, or an amino group, X indicates a single bond or a divalent organic group, * indicates a bonding hand with respect to Si, and n indicates 0 or 1. Si may be Si configuring the Si-O-Zr bond, or may be Si configuring the Si-O-Si bond.

[0040] In Formula (2), R ⁴ to R ⁵ each independently indicates one among a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a carboxyl group, or an amino group, R ⁶ to R ⁷ each independently indicates one among a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxyi group having 1 to 4 carbon atoms, and m indicates an integer of 4 to 12. X and * respectively correspond to the same as X and * in Formula (1 ).

[0041 ] A divalent organic group of X, for example, may be a divalent hydrocarbon group having 1 to 16 carbon atoms. A part of the carbon atoms of the hydrocarbon group may be substituted with an oxygen atom. The hydrocarbon group may be a straight-chain hydrocarbon group in some examples, a branched-chain hydrocarbon group in other examples, or a saturated or unsaturated hydrocarbon group in yet other examples. Namely, the divalent organic group may be a group represented by Formula (3) or Formula (4) described below. [0042] In Formula (3), R ⁸ to R ³ each independently indicates one among a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and I indicates an integer of 1 to 8. In Formula (4), R ¹⁰ to R ¹³ each independently indicates one among a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and p and q each independently indicates an integer of 1 to 8. * in Formula (3) and

Formula (4) corresponds to the same as * in Formula (1 ) or Formula (2).

[0043] The structural unit represented by Formula (1 ) described above may be a structural unit represented by Formula (5) or Formula (6) described below.

[0044] In Formula (5) and Formula (6), n and * respectively correspond to the same as n and * in Formula (1 ). I in Formula (5) corresponds to the same as I in Formula (3), and p and q in Formula (6) respectively correspond to the same as p and q in Formula (4).

[0045] The structural unit represented by Formula (2) described above may be a structural unit represented by Formula (7) or (8) described below.

[0046] * in Formula (7) and Formula (8) corresponds to the same as * in

Formula (2). I in Formula (7) corresponds to the same as I in Formula (3), and p and q in Formula (8) respectively correspond to the same as p and q in Formula (4).

[0047] The polysiloxane compound may have a structure represented by Formula (9) described below, in order to further decrease a frictional coefficient of the surface of the conductive body 5 (the surface of the coating layer 4), and to further suppress the contamination on the surface of the conductive body 5 due to the contact with the photoreceptor (for example, the contamination due to the external additive).

[0048] In Formula (9), R ¹⁴ to R ¹⁸ each independently indicates an alkyl group having 1 to 4 carbon atoms, r indicates an integer of 10 to 100, and Y indicates a divalent organic group. * in Formula (9) corresponds to the same as * in Formula (1 ).

[0049] Y in Formula (9) may have an oxazolidone ring in a main chain. Namely, Y may be a group represented by Formula (10) or (11 ) described below.

[0050] In Formula (10), R ¹⁹ to R ²¹ each independently indicates one among a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a carboxyl group, or an amino group. In Formula (11 ), R ²² to R ²³ each independently indicates one among a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a carboxyl group, or an amino group, R ²⁴ to R ²⁵ each independently indicates one among a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxyl group having 1 to 4 carbon atoms, and s indicates an integer of 4 to 12. In Formula (10) and Formula (11 ), A and B each independently indicates one among a single bond or a divalent organic group. The details of the divalent organic group correspond to the same as the details of the divalent organic group of X in Formula (1 ) described above. * in Formula (10) and Formula (11 ) corresponds to the same as * in Formula (9). [0051 ] As illustrated in FIGS. 2 to 4, the coating layer 4 includes protuberances 4a that are substantially dome-shaped. A plurality of protuberances 4a are formed along the outermost surface of the conductive body 5, and may be arranged randomly in a dot pattern along the outermost surface. Here, "substantially dome-shaped" includes a shape having a non-uniform radius curvature, in addition to a spherical crown shape.

[0052] The protuberances 4a are substantially circular in the plan view, and an average diameter (or width dimension) thereof is approximately 4 μm to 16 μm. The average diameter may be approximately 8 μm or more in some examples, or may be approximately 12 μm or more in other examples, to further suppress the contamination on the surface of the conductive body 5 due to the contact with the photoreceptor (for example, the contamination due to the external additive) while suppressing the charging unevenness which is the initial image defect. The average diameter may be approximately 13 μm or less in some examples, or may be approximately 10 μm or less in other examples, in order to further suppress the contamination on the surface of the conductive body 5 due to the contact with the photoreceptor (for example, the contamination due to the external additive).

[0053] The average diameter of the protuberances 4a corresponds to an average value of the diameters (or width dimension) of the protuberances 4a (e.g., a portion indicated by "R" in FIG. 4) to be measured when observing the protuberances 4a in the plan view. Specifically, the coating layer 4 is observed by using KEYENCE VK-X121 in a range of 107 μm x 143 μm from above, the diameters of the protuberances in an observation range is measured, and an average value thereof is obtained. Any protuberance having a diameter of less than 4 μm, is not considered as a protuberance to be observed, and thus, is not included as a measurement target. The same operation is performed in six portions, the diameters (average values) of the protuberances obtained in each of the portions are averaged, and the obtained value is set to the average diameter of the protuberances. In a case where the shape of the protuberance in the plan view is not a true circular shape, an average value of the longest diameter and the shortest diameter is set to the diameter of the protuberance. For example, in a case where the shape of the protuberance is an elliptical (or oval) shape in the plan view, an average value of the longest diameter and the shortest diameter of the ellipse (or oval) is set as the diameter of the protuberance.

[0054] According to examples, the number of protuberances 4a per unit area may be approximately 8.5 pieces/mm ² to 34 pieces/mm ² . In a case where the number of protuberances 4a is in the above-range, the contamination on the surface of the conductive body 5 due to the contact with the photoreceptor (for example, the contamination due to the external additive) can be better suppressed while suppressing the charging unevenness which Is the initial image defect. The number of protuberances 4a per unit area can be obtained similarly as with the measurement method of the average diameter of the protuberances 4a.

[0055] The protuberances 4a may be formed on the entire coating layer 4 (the entire surface) in some examples, or may be formed on a part of the coating layer 4. In order to further suppress the contamination on the surface of the conductive body 5 due to the contact with the photoreceptor (for example, the contamination due to the external additive), a ratio of a region in the coating layer 4 in which the protuberances 4a are formed (for example, a region in which the number of protuberances 4a Is approximately 8.5 pieces/mm ² to 34 pieces/mm ² ) may be 95% or more of the total area of the coating layer 4.

[0056] In the coating layer 4, a layer thickness D of a portion in which the protuberances 4a are not provided (e.g., a portion indicated by "D" in FIG. 2 to FIG. 4), for example, may be within a range having a minimum of approximately 30 nm in some examples, of approximately 50 nm in other examples, or of approximately 70 nm in yet other examples, and having a maximum of approximately 500 nm in some examples, of approximately 400 nm in other examples, or of approximately 300 nm in yet other examples.

[0057] Surface free energy γ ^Total of the coating layer 4 (surface free energy of the outermost surface of the conductive body 5) may be approximately 35.0 mJ/m ² or less in some examples, may be approximately 25.0 mJ/m ² or less in other examples, or may be approximately 20.0 mJ/m ² or less in yet other examples, in order to suppress the contamination on the surface of the conductive body 5 due to the contact with the photoreceptor (for example, the contamination due to the external additive). The surface free energy γ ^Total of the coating layer 4 may be measured by a method described in Test Examples.

[0058] The surface free energy described above is a sum of a dispersion component (γs ^d ), a dipole component (γs ^p ), and a hydrogen-bond component (γs ^h ). In addition to the above-range of the surface free energy of the coating layer 4, a sum of the dipole component (γs ^p ) and the hydrogen-bond component (γs ^h ) may be approximately 12.0 mJ/m ² or less in some examples, may be approximately 8.0 mJ/m ² or less in other examples, or may be approximately 5.0 mJ/m ² or less in yet other examples, in order to further suppress the contamination on the surface of the conductive body 5 due to the contact with the photoreceptor (for example, the contamination due to the external additive).

[0059] According to the resin layer 3 and the coating layer 4 as described above, the outermost surface of the conductive body 5 forms irregularities (for example, the irregularity derived from the resin layer 3 and the fine irregularity derived from the coating layer 4). [0060] The skewness (Rsk) of the outermost surface of the conductive body 5 is approximately 1.0 or more, and may be approximateiy 1.2 or more in some examples, may be approximately 1.4 or more in other examples, may be approximately 1.6 or more in other examples, may be approximately 1.8 or more in other examples, or may be approximately 2.0 or more in yet other examples, so that the protuberances 4a of the coating layer 4 cause a suppression effect of the contamination on the surface of the conductive body 5. The skewness (Rsk) of the outermost surface of the conductive body 5 is approximately 3.2 or less in some examples, and may be approximately 3.0 or less in other examples, may be approximately 2.8 or less in other examples, may be approximately 2.6 or less in other examples, may be approximately 2.4 or less in other examples, or may be approximately 2.2 or less in yet other examples, from the viewpoint of suppressing the charging unevenness. The skewness (Rsk) indicates the cubic mean of Z(x) at a reference length that is non-dimensionalized by the cube of the root mean square height (Zq).

[0061] The ten-point average roughness (Rzjis) of the outermost surface of the conductive body 5 is 11.5 μm or more, and may be 15.0 μm or more in some examples, may be 18.0 μm or more in other examples, may be 20.0 μm or more in other examples, may be 22.0 μm or more in other examples, may be 22.5 μm or more in other examples, or may be 23.0 μm or more in yet other examples, in order to suppress the charging unevenness. The ten-point average roughness (Rzjis) of the outermost surface of the conductive body 5 is 32.0 μm or less, and may be 30.0 μm or less in some examples, may be 29.0 μm or less in other examples, may be 28.0 μm or less in other examples, may be 27.5 μm or less in other examples, may be 27.0 μm or less in other examples, may be 26.5 μm or less in other examples, or may be 26.0 μm or less in yet other examples, in order to suppress rotation unevenness of the charging roller 10 (a circumferential speed deviation).

[0062] The skewness (Rsk) and the ten-point average roughness (Rzjis) are measured on the basis of JIS B0601 -2001 by using a surface roughness meter SE-3400 manufactured by Kosaka Laboratory Ltd. The skewness (Rsk) and the ten-point average roughness (Rzjis), and other surface properties of the conductive body can be adjusted by changing the size, the shape, and the amount of the particles to be contained in the resin layer 3, the number of protuberances 4a of the coating layer 4 and the size thereof, the layer thickness of the coating layer 4, and the like.

[0063] The conductive body 5 may include a surface that is curved with respect to the rotation axis line L. Namely, the surface of the coating layer 4 may be curved with respect to the rotation axis line L. The shortest distance (corresponding to 1/2 of an outer diameter of the conductive body 5) from the rotation axis line L to the surface of the conductive body 5 (the surface of the coating layer 4) varies along the direction of the rotation axis line L (a longitudinal direction). Namely, the shortest distance is the greatest (maximum) at a center point of the conductive body 5 on the rotation axis line L (a center point of the conductive body 5 in the longitudinal direction), and decreases respectively, toward the opposite end portions of the conductive body 5.

[0064] A crown amount can be used as an index expressing a roller shape of the conductive body 5. The crown amount of the conductive body 5 is defined as follows.

Crown Amount = d2 - (d1 + d3)/2

In the above expression, d1 indicates the outer diameter of the conductive body 5 in a position that is 30 mm separated from a first end of the conductive body 5 in the longitudinal direction (a rubber length) toward the center point, d2 indicates the outer diameter of the conductive body 5 at the center point of the conductive body 5 in the longitudinal direction (the rubber length), and d3 indicates the outer diameter of the conductive body 5 in a position that is offset from the second end of the conductive body 5 by 30 mm, in the longitudinal direction (the rubber length) toward the center point.

[0065] The crown amount of the conductive body 5 may be 50 μm or more in some examples, may be 60 μm or more in other examples, or may be 70 μm or more in yet other examples, and may be 130 μm or less in some examples, may be 120 μm or less in other examples, or may be 110 μm or less in yet other examples, to achieve a stable charging evenness for a long period of time while allowing the charging roller 10 to suitably cohere to the photoreceptor, and of maintaining the granularity of image quality.

[0066] The charging member described above is provided in an image forming apparatus, as charging means to charge the photoreceptor. Namely, the charging member performs a charging treatment uniformly with respect to the surface of the photoreceptor that is an image carrier. For example, the example image forming apparatus includes the photoreceptor, and the charging member to charge the photoreceptor.

[0067] In the example image forming apparatus, a direct-current voltage exclusively, may be applied to the charging member. In such a case, a bias voltage to be applied while an image is output may be -1000 V to -1500 V.

[0068] Manufacturing Method of Charging Member

Hereinafter, an example manufacturing method of a charging member will be described based on a manufacturing method of the charging roller 10 as an example.

[0069] The example manufacturing method of the charging roller 10 includes preparing the conductive base 6 that is mountable on the conductive support 1 , preparing a coating liquid containing a composition containing a hydrolyzable silane compound, spraying the coating liquid onto the surface of the conductive base 6, and curing the composition to form the coating layer 4 over the conductive base 6. In such a manufacturing method, the coating liquid containing the composition containing the hydrolyzable silane compound is spray-applied (applied as a spray), and accordingly, droplets (a film including the droplets) is formed on the surface of the conductive base, and the protuberances 4a are formed by curing the composition. The protuberances 4a have a shape derived from the droplets, and for example, the droplets and the protuberances 4a have substantially the same shape.

[0070] The conductive base 6, for example, can be prepared as follows. Namely, first, a material for an elastic layer and a coating liquid for a resin layer are prepared. The material for an elastic layer can be prepared by kneading a material for the elastic layer 2 with a kneading machine such as a kneader. In addition, the coating liquid for a resin layer can be prepared by kneading a material for the resin layer 3 with a kneading machine such as a roller, by adding an organic solvent to the mixture, and by performing mixing and stirring. Next, a metal mold for injection molding in which a core bar that is the conductive support 1 is set is filled with the material for an elastic layer, and is thermally crosslinked in a predetermined condition. Subsequently, demolding is performed, and thus, a base roll is manufactured in which the elastic layer is formed along the outer circumferential surface of the conductive support 1. Next, the coating liquid for a resin layer is applied onto an outer circumferential surface of the base roll described above, so as to form the resin layer 3. As described above, it is possible to prepare the conductive base 6 including the elastic layer 2 formed on the outer circumferential surface of the conductive support 1 , and the resin layer 3 formed on the outer circumferential surface of the elastic layer 2. [0071 ] In addition to an injection molding method, the formation method of the elastic layer may include a cast molding method, or a method in which press molding and grinding are combined together. In addition, a coating method of the coating liquid for a resin layer may include any suitable method, such as a dipping method, a roll coating method, and the like.

[0072] According to examples, the coating liquid may contain a composition containing a hydrolyzable silane compound (a curable composition) that is a curable component, and a solvent in which the components of the composition are dissolved or dispersed. Such curable component may refer to a component to be incorporated in the structure of a polysiloxane compound that is generated at the time of curing the coating liquid. Accordingly, an acid generating agent described below is not contained in the curable component.

[0073] The hydrolyzable silane compound has a hydrolyzable silyl group represented by Formula (12) described below.

[0074] In Formula (12), R ³¹ to R ³³ each independently indicates a hydrocarbon group. The hydrocarbon group, for example, is an alkyl group having 1 to 4 carbon atoms. In some examples, a single type of the hydrolyzable silane compound may be used, or in other examples, a plurality of types of the hydrolyzable silane compounds may be used in combination.

[0075] The content of the hydrolyzable silane compound may be 84.0 mol% or more in some examples, may be 88.0 mol% or more in other examples, or may be 90.0 mol% or more in yet other examples, with respect to the total amount of the curable component, in order to more easily impart a suitable condensation efficiency. The content of the hydrolyzable silane compound may be 98.0 mol% or less in some examples, may be 97.0 mol% or less in other examples, or may be 96.0 mol% or less in yet other examples, with respect to the total amount of the curable component, in order to more easily impart a suitable condensation efficiency.

[0076] The composition may contain a zirconium chelate compound, as the curable component. The zirconium chelate compound has a zirconium atom (Zr) that is a central metal, and 1 to 4 chelate ligands (polydendate ligands) that are coordinated to the zirconium atom. The zirconium chelate compound accelerates a polymerization (self-condensation) reaction of the hydrolyzable silane compound, and contributes to the formation of a coating layer having low surface free energy.

[0077] The chelate ligand, for example, may be a bidentate ligand or a tridentate ligand. An example of a ligand atom of the chelate ligand includes an oxygen atom. In some examples, the chelate ligand may be an acetylacetonate group or an alkyl acetoacetate group. Alkyl of the alkyl acetoacetate group, for example, may be alkyl having 1 to 10 carbon atoms.

[0078] The zirconium chelate compound has a monodentate ligand. An example of the monodentate ligand includes an alkoxy group. The number of carbon atoms of the alkoxy group, for example, may be 1 to 10.

[0079] The zirconium chelate compound, for example, may be zirconium tributoxymonoacetylacetonate, zirconium dibutoxybis(acetylacetonate), zirconium dibutoxybis(ethyl acetoacetate), or the like. In some examples, a single type of zirconium chelate compound may be used, and in other examples, a plurality of types of the zirconium chelate compounds may be used in combination.

[0080] The content of the zirconium chelate compound may be 2.0 mol% or more in some examples, may be 3.0 mol% or more in other examples, or may be 4.0 mol% or more in yet other examples, with respect to the total amount of the curable component, in order to shorten a reaction time. The content of the zirconium chelate compound may be 10.0 mol% or less in some examples, may be 8.0 mol% or less in other examples, or may be 6.0 mol% or less in yet other examples, with respect to the total amount of the curable component, in order to achieve a suitable condensation rate.

[0081 ] The composition may contain a hydrolyzable silane compound having an epoxy group, as the curable component. Namely, at least a part of the hydrolyzable silane compound may be the hydrolyzable silane compound having an epoxy group. When the composition contains the hydrolyzable silane compound having an epoxy group, it is possible to use photocationic polymerization and thermal curing together. The hydrolyzable silane compound having an epoxy group, for example, may have a structure represented by Formula (13) or (14) described below, in order to suppress the occurrence of polymerization inhibition due to oxygen and to impart suitable surface curing properties.

[0082] In Formula (13), R ¹ to R ³ and X respectively correspond to the same as R ¹ to R ³ and X in Formula (1 ). In Formula (14), R ⁴ to R ⁷ , and m and X respectively correspond to the same as R ⁴ to R ⁷ , and m and X in Formula (2). Q in Formula (13) and Formula (14) indicates the hydrolyzable silyl group represented by Formula (12) described above. [0083] The hydrolyzable silane compound having an epoxy group, for example, may be (3-giycidoxypropyl) trimethoxysilane, (3-glycidoxypropyl) triethoxysilane, 2-(3,4-epoxy cyclohexyl) ethyl trimethoxysilane, 2-(3,4-epoxy cyclohexyl) ethyl triethoxysilane, or the like. In some examples, a single type of the hydrolyzable silane compound having an epoxy group may be used, and in other examples, a plurality of types of the hydrolyzable silane compounds having an epoxy group may be used in combination.

[0084] The content of the hydrolyzable silane compound having an epoxy group may be 80.0 mol% or more in some examples, may be 85.0 mol% or more in other examples, or may be 90.0 mol% or more in yet other examples, with respect to the total amount of the curable component, to further suppress the polymerization inhibition due to the oxygen and to impart more suitable surface curing properties. The content of the hydrolyzable silane compound having an epoxy group may be 97.5 mol% or less in some examples, may be 96.0 mol% or less in other examples, or may be 95.0 mol% or less in yet other examples, with respect to the total amount of the curable component, in order to reduce curing shrinkage and in order to achieve a suitable cohesiveness with respect to a surface layer resin.

[0085] The composition containing the hydrolyzable silane compound having an epoxy group may further contain an acid generating agent. The acid generating agent may be a photo-acid generating agent in some examples, or may be a thermal-acid generating agent in other examples. In some examples, a single type of the acid generating agent may be used, and in other examples, a plurality of types of the acid generating agents may be used in combination.

[0086] The photo-acid generating agent may be selected to be activated with light having a wavelength of 365 nm to 405 nm from a UV-LED light source, in order to suppress damage to the base material due to heat from a light source and oxidation degradation of the coating layer. The photo-acid generating agent, for example, may be a triarylsulfonium salt-based photo-acid generating agent or the like.

[0087] The thermal-acid generating agent may be selected to be activated at a low temperature (for example, 250°C or less), in order to suppress damage to the base material due to heat and the oxidation degradation of the coating layer. The thermal-acid generating agent, for example, may be a quaternary ammonium trifluoromethane sulfonic acid or the like.

[0088] The content of the acid generating agent may be 0.01 parts by mass or more in some examples, may be 0.03 parts by mass or more in other examples, or may be 0.05 parts by mass or more in yet other examples, with respect to 100 parts by mass of a compound having an epoxy group (for example, the hydrolyzable silane compound having an epoxy group), in order to increase the condensation rate. The content of the acid generating agent may be 1.00 parts by mass or less in some examples, may be 0.08 parts by mass or less in other examples, or may be 0.07 parts by mass or less in other examples, with respect to 100 parts by mass of the compound having an epoxy group (for example, the hydrolyzable silane compound having an epoxy group), in order to shorten a synthesis time.

[0089] The composition may contain a one end-modified silicone compound having a structure represented by Formula (16) described below (a silicone compound having a reactive group on one terminal), and a hydrolyzable silane compound having a functional group capable of forming a bond by reacting with a reactive group of the silicone compound (hereinafter, also referred to as a "bonding functional group"), as the curable component, in order to reduce the frictional coefficient of the surface of the coating layer 4.

[0090] in Formula (16), U Indicates a reactive group. R ¹⁴ to R ¹⁸ and r respectively correspond to the same as R ¹⁴ to R ¹⁸ and r in Formula (9), and A corresponds to the same as A in Formulas (10) and (11 ).

[0091 ] The one end-modified silicone compound reacts with the hydrolyzable silane compound having a bonding functional group, so as to obtain a silicone compound having a suitable compatibility with other components in the coating liquid (for example, hydrolyzable silane having an epoxy group). Accordingly, it is possible to suppress the occurrence of phase separation in the coating layer 4, and to reduce the frictional coefficient over the entire surface of the coating layer 4.

[0092] The reactive group, for example, may be an epoxy group. For example, the reactive group may be a group represented by Formula (17) or (18) described below.

[0093] In Formula (17), R ¹⁹ to R ²¹ respectively correspond to the same as R ¹⁹ to R ²¹ in Formula (10). In Formula (18), R ²² to R ²⁵ and s respectively correspond to the same as R ²² to R ²⁵ and s in Formula (11 ). [0094] A functional group equivalent (a reactive group equivalent) of the one end-modified silicone compound, for example, may be 1000 g/mol to 5000 g/mol. [0095] The viscosity of the one end-modified silicone compound at 25°C, for example, may be 10 mm ² /s to 120 mm ² /s.

[0096] In some examples, a single type of the one end-modified silicone compound may be independently used, and in other examples, a plurality of types of the one end-modified silicone compounds may be used in combination.

[0097] The content of the one end-modified silicone compound may be 0.1 mol% or more in some examples, may be 0.2 mol% or more in other examples, or may be 0.3 mol% or more in yet other examples, with respect to the total amount of the curable component, in order to further reduce the frictional coefficient. The content of the one end-modified silicone compound may be 1 .0 mol% or less in some examples, may be 0.9 mol% or less in other examples, or may be 0.8 mol% or less in yet other examples, with respect to the total amount of the curable component, in order to suppress the phase separation.

[0098] In some examples, the hydrolyzable silane compound having a bonding functional group may have a structure represented by Formula (19) described below.

[0099] In Formula (19), L indicates a bonding functional group, and Q indicates a hydrolyzable silyl group represented by Formula (12) described above. B corresponds to the same as B in Formulas (10) and (11 ).

[0100] The bonding functional group indicated by L may be a functional group capable of forming a bond by reacting with an epoxy group (an amino group, an isocyanate group, or the like) in some examples, or may be an isocyanate group in other examples, in order to further reduce the frictional coefficient of the surface of the coating layer 4. [0101 ] Examples of the hydrolyzable silane compound having a bonding functional group include 3~isocyanate propyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, or the like. In some examples, a single type of the hydrolyzable silane compound having a bonding functional group may be used, and in other examples, a plurality of types of the hydrolyzable silane compounds having a bonding functional group may be used in combination.

[0102] The content of the hydrolyzable silane compound having a bonding functional group may be 1.0 mol% or more in some examples, may be 1.5 mol% or more in other examples, or may be 2.0 mol% or more in yet other examples, with respect to the total amount of the curable component, in order to suppress the phase separation. The content of the hydrolyzable silane compound having a bonding functional group may be 5.0 mol% or less in some examples, may be 4.5 mol% or less in other examples, or may be 4.0 mol% or less in yet other examples, with respect to the total amount of the curable component, in order to further reduce the frictional coefficient.

[0103] The composition may further contain a reaction product between the one end-modified silicone compound and the hydrolyzable silane compound having a bonding functional group. The reaction product may be synthesized in advance before the coating liquid is prepared according to some examples, or may be generated in the coating liquid in other examples. In a case where the composition contains the reaction product, the content of the one end-modified silicone compound and the hydrolyzable silane compound having a bonding functional group is calculated by considering that the one end-modified silicone compound and the hydrolyzable silane compound having a bonding functional group are respectively compounded.

[0104] The solvent may contain water, for example. The solvent may further contain an alcohol solvent. Namely, the solvent may be a mixed solvent of water and the alcohol solvent. In this case, the content of water in the solvent may be 10.0 mass% or more, and may be 60.0 mass% or less, relative to the total mass of the solvent. Methanol, ethanol, isopropyl alcohol, or the like may be used as the alcohol solvent.

[0105] The content of the solvent may be adjusted, according to examples, to adjust the viscosity of the coating liquid. In some example, the content of the solvent may be 95.0 mass% to 99.9 mass%, relative to the total mass of the coating liquid.

[0106] The application of the coating liquid is spray application (the application using a spray coating method). The spray application may be performed by using an air brush, for example.

[0107] In the spray application, the size of the droplets can be adjusted by adjusting an injection amount of the coating liquid per unit time, the size of an injection port, an injection time with respect to a predetermined portion, and the like. For example, in a case where the air brush is used, the position of a needle may be adjusted by a needle adjustment dial, so as to adjust the size of a gap between the needle and the injection port, and to adjust the amount of coating liquid to be injected (the injection amount) per unit time. Accordingly, the protuberances 4a having a suitable average diameter can be formed.

[0108] Drying or the like may be performed after the coating liquid is applied and before the composition is cured so that the solvent in the formed coating may be removed. The drying may be performed at 130°C to 220°C.

[0109] A curing method of the composition is not particularly limited. In a case where the composition contains the acid generating agent, suitable curing means (heating, light irradiation, or the like) may be adopted, in accordance with the type of acid generating agent. The heating and the light irradiation may be used together as the curing means. In a case of using the photo-acid generating agent, the composition may be cured by being irradiated with light having a wavelength of 365 nm to 405 nm from the UV-LED light source, from the viewpoint of suppressing the damage on the base due to heat generated from the light source and the oxidation degradation of the coating layer. The UV-LED light source, for example, may be a UV-LED light source manufactured by Hamamatsu Photonics K.K., a UV-LED light source manufactured by HOYA Corporation, a UV-LED light source manufactured by Iwasaki Electric Co., Ltd., a UV-LED light source manufactured by Ushio Inc., a UV-LED light source manufactured by Heraeus K.K., a UV-LED light source manufactured by AITEC SYSTEM Co., Ltd., a UV-LED light source manufactured by Micro-Sphere S.A., and the like. In addition, in a case of using the thermal-acid generating agent, the composition may be cured by heating to 250°C or less, in order to suppress the damage on the base due to heat and the oxidation degradation of the coating layer.

[0110] Test Examples

Hereinafter, Test Examples of the charging member will be described, but the charging member is not limited to these Test Examples.

[0111 ] Preparation of Coating Liquid

A mixture was prepared by mixing together KBM-403 (Product Name, manufactured by Shin-Etsu Chemical Co., Ltd., (3-glycidoxypropyl) trimethoxysilane) that is a hydrolyzable silane compound having an epoxy group, MCR-E11 (Product Name, manufactured by Gelest, Inc., a viscosity of 10 mm ² /s to 15 mm ² /s (25°C), a functional group equivalent of 1000 g/mol) that is a one end-modified silicone compound, KBE-9007N (Product Name, manufactured by Shin-Etsu Chemical Co., Ltd., 3-isocyanate propyl triethoxysilane) that is a hydrolyzable silane compound having an isocyanate group, AKZ947 (Product Name, manufactured by Gelest, Inc., a solution of zirconium dibutoxybis(acetylacetonate), a solid content of 25 mass%) that is a zirconium chelate compound, and a solvent (water and ethanol). The mixture was then stirred at a room temperature, and then, heated to reflux for 24 hours, to obtain a condensate of hydrolyzable silane having a silicone skeleton. The condensate was added to a mixed solvent of 2-butanol/ethanol, so as to obtain a condensate-containing alcohol solution having a solid content of 1.0 mass%. In such a case, KBM-403, MCR-E11 , KBE-9007N, and AKZ947 were compounded at a compounding ratio (a solid content) of 88.0 mol% : 1 .0 mol% : 5.0 mol% : 6.0 mol%. In addition, a compounding amount of water was adjusted such that was indicates a molar number ratio of water with respect to a condensation point of the silane compound to be used. For example, the minimum number of water molecules for condensing one molecule of a silane compound having a trimethoxy group is 3. Such a relationship is set to An optimal range of is set to

[0112] Next, TAG-2689 (Product Name, manufactured by Kusumoto Chemicals, Ltd., a quaternary ammonium salt-based thermal-acid generating agent) or CPI-31 OS (Product Name, manufactured by San-Apro Ltd., a triarylsulfonium salt-based photo-acid generating agent) as an acid generating agent was dissolved in acetone, and was adjusted to be 10 mass%, and 0.35 g of an acid generating agent solution of 10 mass% was added to 100 g of the condensate-containing alcohol solution, so as to obtain a thermal-curable coating liquid and a photo-curable coating liquid.

[0113] Manufacturing of Conductive Base A

Preparation of Material for Forming Elastic Layer

A material for forming an elastic layer was prepared by compounding together and subsequently kneading with a roller, 100.00 parts by mass of epichlorohydrin rubber ("EPICHLOMER CG-102", manufactured by DAISO CHEMICAL CO., LTD.) as a rubber component, 5.00 parts by mass of sorbitan fatty acid ester ("SPLENDER R-300", manufactured by Kao Corporation) as a lubricant, 5.00 parts by mass of a ricinoleic acid as a softener, 0.50 part by mass of a hydrotalcites compound ("DHT-4A", manufactured by Kyowa Chemical Industry Co., Ltd.) as an acid acceptor, 1.00 part by mass of tetrabutyl ammonium chloride ("tetrabutyl ammonium chloride", manufactured by Tokyo Chemical Industry Co., Ltd.) as a conductive agent (an ion conductive agent), 50.00 parts by mass of silica ("Nipsil ER", manufactured by Tosoh Silica Corporation) as a filler, 5.00 parts by mass of zinc oxide as a cross-linking promoter, 1.50 parts by mass of dibenzothiazole sulfide, 0.50 part by mass of tetramethyl thiuram monosulfide, and 1.05 parts by mass of sulfur as a cross-linking agent. As a result, the material for forming an elastic layer was obtained.

[0114] Preparation of Coating Liquid 1 for Forming Resin Layer

A mixed liquid was prepared by mixing into tetrahydrofuran (THF), 100.00 parts by mass of thermoplastic N-methoxy methylated 6-nylon ("Toresin F-30K", manufactured by Nagase ChemteX Corporation) as a polymer component, 5.00 parts by mass of methylene bisethyl methyl aniline ("CUREHARD-MED", manufactured by lhara Chemical Industry Co., Ltd.) as a curing agent, and 18.00 parts by mass of carbon black ("Denka Black HS100", manufactured by Denka Company Limited) as a conductive agent (an electronic conductive agent). In the mixed liquid, two types of amorphous nylon resin particles having different average particle diameters (25.0 μm and 5.0 μm) ("Orgasol Series", manufactured by Arkema S.A.) were added as the first particles 31 and the second particles 32, and were sufficiently stirred until the solution became uniform. An additive amount was adjusted based on the total amount of the resin layer 3 to be obtained such that the content of the first particles 31 was 25 mass% and the content of the second particles 32 was 5 mass%. Subsequently, each component in the solution was dispersed by using a double roll Accordingly, a coating liquid 1 for forming a resin layer was obtained.

[0115] The average particle diameter of the first particles 31 and the second particles 32 was measured as follows. Namely, 100 particles were extracted randomly from a population of a plurality of particles with SEM observation, and an average value of particle diameters was set to the average particle diameter of the resin particles. A particle shape of the used resin particles was an amorphous shape, and thus, an average value of the longest diameter (longest transverse dimension) and the shortest diameter (shortest transverse dimension) of the observed particles was set as the particle diameter of the respective particles.

[0116] Preparation of Conductive Base A

A roll molding metal mold including a cylindrical roll molding space was prepared, and a core bar having a diameter of 8 mm (the conductive support 1 ) onto which a conductive adhesive agent was applied was set to be coaxial with the roll molding space. The material for forming an elastic layer prepared as described above, was injected into the roll molding space in which the core bar was set, was subsequently heated at 170°C for 30 minutes, and then, was cooled, and was further demolded. Accordingly, a base roll including the conductive support 1 as a conductive axis body, and the elastic layer 2 having a thickness of 2 mm (a thickness in the central position in the rotation axis line L direction) that was formed along the outer circumferential surface of the conductive support 1 was obtained.

[0117] Next, the coating liquid 1 for forming a resin layer prepared as described above, was applied onto the surface of the elastic layer 2 of the base roll by a roll coating method. In such a case, the coating was performed while an excess (unnecessary) coating liquid was scraped with a scraper to achieve a suitable film thickness. After a coated film was formed, the film was heated at 150°C for 30 minutes so as to form the resin layer 3 having a layer thickness A of 5.0 μm. Accordingly, a conductive base A including the elastic layer 2 formed along the outer circumferential surface of the axis body (the conductive support 1 ), and the resin layer 3 formed along the outer circumferential surface of the elastic layer 2 was obtained.

[0118] Manufacturing of Conductive Base B

A conductive adhesive agent was applied onto the conductive support 1 (a core bar having a diameter of 8 mm) as a conductive axis body, and then, the material for forming an elastic layer prepared as described above under the title "Manufacturing of Conductive Base A", was subjected to extrusion molding along the outer circumferential surface thereof, so as to form an elastic layer having a thickness of 3 mm (a thickness in the central position in the rotation axis line L direction). An end portion was cut to have a predetermined elastic layer length, and grinding was performed, to obtain a base roll having a crown shape. Next, 20 parts by mass of an isocyanate compound (MDI: manufactured by DIG Corporation) was added to 100 parts by mass of ethyl acetate, and was mixed and dissolved, so as to obtain an isocyanate solution. Next, the isocyanate solution was applied onto the surface of the elastic layer of the base roll, and subsequently, a portion impregnated with the isocyanate solution was cured, to form the resin layer 3 having a thickness of 50 μm. Specifically, the base roll was immersed in the isocyanate solution for 30 seconds while the temperature of the isocyanate solution was retained at 23°C, and then, the base roll was taken out, and the base roll that was taken out (the base roll of which the surface was impregnated with the isocyanate solution) was heated for 1 hour in an oven that was retained at 120°C, and thus, the resin iayer 3 was formed. Accordingly, a conductive base B including the elastic iayer 2 formed along the outer circumferential surface the axis body (the conductive support 1 ), and the resin layer 3 formed along the outer circumferential surface of the elastic layer 2 was obtained.

[0119] Manufacturing of Conductive Base C

Preparation of Coating Liquid 2 for Forming Resin Layer

A mixed liquid was prepared by mixing into tetrahydrofuran (THF), 100.00 parts by mass of thermoplastic N-methoxymethylated 6~nylon ("Toresin F-30K", manufactured by Nagase ChemteX Corporation) as a polymer component, 5.00 parts by mass of methylene bisethyl methyl aniline ("CUREHARD-MED”, manufactured by lhara Chemical Industry Co., Ltd.) as a curing agent, and 18.00 parts by mass of carbon black ("Denka Black HS100", manufactured by Denka Company Limited) as a conductive agent (an electronic conductive agent). In the mixed liquid, two types of amorphous nylon resin particles having different average particle diameters (10.0 μm and 5.0 μm) ("Orgasol Series”, manufactured by Arkema S.A.) were added as the first particles 31 and the second particles 32, and were sufficiently stirred until the solution became uniform. An additive amount was adjusted based on the total amount of the resin layer 3 to be obtained such that the content of the first particles 31 was 25 mass% and the content of the second particles 32 was 5 mass%. Subsequently, each component in the solution was dispersed by using a double roll. Accordingly, a coating liquid 2 for forming a resin layer was obtained.

[0120] The average particle diameter of the first particles 31 and the second particles 32 was measured as follows. Namely, 100 particles were extracted randomly from a population of a plurality of particles with SEM observation, and an average value of particle diameters was set as the average partide diameter of the resin partides. A particle shape of the used resin particles was an amorphous shape, and thus, an average value of the longest diameter (longest transverse dimension) and the shortest diameter (shortest transverse dimension) of the observed particles was set as the particle diameter of the respective particles.

[0121 ] Preparation of Conductive Base C

A roll molding metal mold including a cylindrical roll molding space was prepared, and a core bar having a diameter of 8 mm (the conductive support 1) onto which a conductive adhesive agent was applied was set to be coaxial with the roll molding space. The material for forming an elastic layer prepared in "Manufacturing of Conductive Base A" described above was injected into the roll molding space in which the core bar was set, was subsequently heated at 170°C for 30 minutes, and then, was cooled and further demolded. Accordingly, a base roll including the conductive support 1 as a conductive axis body, and the elastic layer 2 having a thickness of 2 mm (a thickness in the central position in the rotation axis line L direction) that was formed along the outer circumferential surface of the conductive support 1 was obtained.

[0122] Next, the coating liquid 2 for forming a resin layer prepared as described above, was applied onto the surface of the elastic layer 2 of the base roll by a roll coating method. In such a case, the coating was performed while an excess (unnecessary) coating liquid was scraped with a scraper to have a suitable film thickness. After a coated film was formed, the film was heated at 150°C for 30 minutes, to form the resin layer 3 having a layer thickness A of 15.0 μm. Accordingly, a conductive base C including the elastic layer 2 formed along the outer circumferential surface of the axis body (the conductive support 1 ) and the resin layer 3 formed along the outer circumferential surface of the elastic layer 2 was obtained.

[0123] Test Examples 1 to 25

Manufacturing of Charging Roller 10

The thermal-curable coating liquid or the photo-curable coating liquid prepared as described above, was applied onto the surface of the conductive base A, B, or C prepared as described above by using an air brush (Product Name: SPRAY-WORK HG single air brush, manufactured by TAMIYA, INC.), so as to form a coated film including droplets (e.g., a film of a coating liquid). The coating was implemented at a spray injection amount shown in Table 1 by performing needle setting of the air brush (the number of rotations of a needle adjustment dial from the closed state) to a value as shown in Table 1. After a coated film was formed, in a case of using the thermal-curable coating liquid, the coated film was cured by being heated at 160°C for 20 minutes, and in a case of using the photo-curable coating liquid, the coated film was cured by being irradiated with light having a wavelength of 365 nm at a cumulative light amount mJ/cm ² by using a UV irradiation device (manufactured by Heraeus K.K.) including a UV-LED light source. Accordingly, the coating layer 4 including the protuberances 4a was formed.

[0124] According to the preparation methods described above, the charging roller 10 including the axis body (the conductive support 1 ), and the conductive body 5 including the elastic layer 2 formed along the outer circumferential surface of the axis body, the resin layer 3 formed along the outer circumferential surface of the elastic layer 2, and the coating layer 4 formed along the outer circumferential surface of the resin layer 3 were obtained. The coating liquid contained hydrolyzable silane and a zirconium chelate compound, and thus, the coating layer 4 contained a polysiloxane compound having a Si-O-Zr bond in the molecular structure. [0125] Measurement of Average Diameter of Protuberances 4a

In the following method, the average diameter of the protuberances 4a of the coating layer 4 was measured. The average diameter of the protuberances 4a is an average value of the diameters of the protuberances 4a to be measured when observing the protuberances 4a in the plan view. Specifically, first, the coating layer 4 was observed by using KEYENCE VK-X121 (Lens Magnification x 100) in a range of 107 μm x 143 μm from above, the diameters of the protuberances in an observation range were measured, and an average value thereof was obtained. The same operations were performed in six portions, the diameters (average values) of the protuberances obtained in each of the portions were averaged, and the obtained value was set to the average diameter of the protuberances. In a case where the diameter was less than 4 μm, such a protuberance was not regarded as a protuberance to be observed, and thus, was not included in a measurement target. In addition, in a case where the shape of the protuberance in the plan view was not a true circular shape, an average value of the longest diameter (longest transversal dimension) and the shortest diameter (shortest transversal dimension) was set to the diameter of the protuberance. Measurement results are shown in Table 1. In addition, for reference, a plane photograph of the coating layer of Test Example 1 that was observed in the measurement is shown in FIG. 5. In a case where the injection amount was excessively small or the injection amount was excessively large, and thus, dripping occurred, no protuberance 4a was formed, and thus, in the average diameter of Table 1 , "Not formable" was stated.

[0126] Measurement of Rsk and Rzjis of Surface of Conductive Body 5

The skewness (Rsk) and the ten-point average roughness (Rzjis) of the surface of the conductive body 5 were measured with a method based on JIS B0601 -2001 by using a surface roughness meter SE-3400 manufactured by Kosaka Laboratory Ltd., at a cutoff value of 0.8 mm, a measurement speed of 0.5 mm/s, and a measurement length of 8 mm. According to this meter, six portions arbitrarily selected on the surface of the conductive body 5 were measured, and an average value of the six portions was set to each measured value. Results are shown in Table 1 .

127] [Table 1]

[0128] Measurement of Surface Free Energy

A contact angle 0 of the outermost surface of the charging colter 10 (the surface of the coating layer 4) with respect to three types of probe liquids shown in Table 2 described below was measured by using a contact angle meter (Product Name: CA-X ROLL Type, manufactured by Kyowa Interface Science, Inc.). Measurement conditions of the contact angle was as follows.

Measurement Conditions:

• Measurement: Liquid Droplet Method (True Circle Fitting)

• Flow Rate: 1 pL

• Droplet Landing Recognition: Automatic

• Image Treatment: Algorithm - No Reflection

• Image Mode: Frame

• Threshold Level: Automatic

[0129] [Table 2]

[0130] In Table 2 described above, γL ^d , γL. ^p , and γL ^h respectively indicate a dispersion component, a dipole component, and a hydrogen-bond component in a probe liquid. Each of components ( γL ^d , γL ^P , and γL ^h ) of three types of probe liquids in Table 2 described above, and a contact angle 9 with respect to each of the probe liquids obtained by measurement were assigned to the following theoretical equation (Calculation Formula (1 )) of Kitazaki and Hata, three equations with respect to each of the probe liquids were created, and such simultaneous equations with 3 variables were solved, and thus, the dispersion component (γs ^d ), the dipole component (γs ^p ), and the hydrogen-bond component (γs ^h ) in the coating layer 4 were calculated. Then, a sum of γs ^d , γs ^p , and γs ^h was set to surface free energy (γs ^Total )- Results are shown in Table 3.

[Expression 1]

Calculation Formula (1 )

[0131 ] Evaluation of Surface Contamination

The charging member (the charging roller 10) obtained as described above was incorporated in Multixpress C8640 ND manufactured by Samsung Electronics Co., Ltd., to obtain an image forming apparatus, and an image was formed in accordance with the following condition.

Image Forming Condition

• Printing Environment: in Low Temperature Low Humidity Environment (15°C/10%RH)

• Printing Condition: General Printing Speed of 305 mm/sec and Half Speed thereof, Number of Printed Sheets (80 kPV), Type of Sheet (Office Paper EC)

- Load with respect to Conductive Support End Portion: 5.88 N on One Side

• Applied Bias: Suitably adjusted and Determined such that

Photoreceptor Surface Potential Becomes -600 V

[0132] Next, surface contamination of the charging roller 10 after the image was formed was evaluated. The surface contamination of the charging roller 10 was mainly derived from silica of an external additive to be used in a toner, and thus, the degree of contamination was evaluated by quantifying an element Si on the surface of the charging roller 10 with a fluorescence X-ray measurement device (EDXL300: manufactured by Rigaku Corporation). Specifically, in a chamber of the fluorescence X-ray measurement device, the charging roller 10 was arranged such that the center of the charging roller 10 was aligned with a detector, and the element Si on the surface of the charging roller 10 was quantified. Such measurement was performed with respect to the charging roller 10 before the image was formed and after the image was formed (for each 20 kPV), to calculate a difference ΔSi [cps/mA] in the amount of Si (= Amount of Si [cps/mA] after Endurance Test - Amount of Si [cps/mA] before Endurance Test). The difference ΔSi was plotted on a vertical axis, the total number of rotations of the photoreceptor was plotted on a horizontal axis, and the surface contamination was evaluated by using the slope of the obtained graph as an index. ΔSi decreases in proportion to the number of rotations of the photoreceptor as the slope decreases, and the contamination due to the external additive is less likely to occur. Results are shown in Table 3. [0133] Evaluation of Image Forming Properties (Charging Evenness)

The charging member (the charging roller 10) obtained as described above was incorporated in Multixpress C8640 ND manufactured by Samsung Electronics Co., Ltd. as the image forming apparatus, and a halftone image was output in accordance with the following condition.

Printing Environment: in Normal Temperature Normal Humidity

Environment (23°C/60%RH) Printing Condition: General Printing Speed of 305 mm/sec and Half Speed Thereof, Number of Printed Sheets (Two Points of 180 kPV and 360 kPV), Type of Sheet (Office Paper EC)

Load with respect to Conductive Support End Portion: 5.88 N on One Side

Applied Bias: Suitably adjusted and Determined such that Photoreceptor Surface Potential Becomes -600 V

[0134] Microjitter appearing in the halftone image was visually observed, and was evaluated based on the following standards. Evaluation results are shown in Table 3. The microjitter is one of the indices for evaluating the charging evenness. The microjitter was observed at the initial stage of image formation (the initial stage) and after an endurance test (after run) in order to determine whether or not stable charging evenness was obtained for a long period of time.

Evaluation A: Uniform Halftone Image Was Obtained.

Evaluation B: Charging Unevenness Slightly Occurred in Image End

Portion.

Evaluation C: Charging Unevenness Obviously Occurred in Image

End Portion.

Evaluation D: Charging Unevenness Occurred on Entire Image

Surface.

[0135] [Table 3]

[0136] It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail is omitted.