Image forming unit, process cartridge, and image forming apparatus

Abstract

The present invention provides an image forming unit that is less prone to image fogging and less prone to streaky density unevenness in low-temperature, low-humidity environments. [Solution] The image forming unit comprises a photoreceptor and a charging member that contacts the surface of the photoreceptor and charges the photoreceptor, wherein the photoreceptor has a conductive substrate and a laminated photoreceptor layer having a charge generating layer and a charge transport layer disposed on the conductive substrate, the charge transport layer contains polyarylate resin and substantially does not contain organofluorine compounds, and the charging member has a support member, an elastic layer disposed on the support member and a surface layer disposed on the elastic layer, the surface layer contains resin, conductive particles and silicon compounds, and the silicon element concentration on the surface of the surface layer is 0.2 atm% or more and 1.2 atm% or less.

Description

[Technical Field]

[0001] This disclosure relates to an image forming unit, a process cartridge, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses an image forming unit comprising a photoreceptor and a contact-type charging member, wherein the charge transport layer of the photoreceptor contains at least one of a polyester resin having a constituent unit having an aromatic ring and a polycarbonate resin having a constituent unit having an aromatic ring, and the storage modulus G' of the elastic layer of the contact-type charging member is 5.0 MPa or less.

[0003] Patent Document 2 discloses an example in which a conductive member containing polyether-modified polydimethylsiloxane in its surface layer is applied to a contact-type charging roll. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-121553 [Patent Document 2] Japanese Patent Publication No. 2023-134202 [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of this disclosure is to provide an image forming unit that is less prone to image fogging and less prone to streaky density unevenness in images in low temperature and low humidity environments. [Means for solving the problem]

[0006] <1> Photoreceptor and The system comprises a charging member that contacts the surface of the photoreceptor and charges the photoreceptor, The photoreceptor comprises a conductive substrate and a laminated photoreceptor having a charge generation layer and a charge transport layer disposed on the conductive substrate. The charge transport layer contains a polyarylate resin and is substantially free of organofluorine compounds. The charging member comprises a support member, an elastic layer disposed on the support member, and a surface layer disposed on the elastic layer. The surface layer contains a resin, conductive particles, and a silicon compound, and the silicon element concentration on the surface of the surface layer is 0.2 atm% or more and 1.2 atm% or less. Image forming unit. <2> The silicon element concentration on the surface of the aforementioned surface layer is 0.3 atm% or more and 1.0 atm% or less. <1> The image forming unit described above. <3> The surface layer of the charging member contains polyamide resin and polyvinyl butyral resin as a binder resin, and the proportion of the polyvinyl butyral resin to the total amount of the polyamide resin and the polyvinyl butyral resin is 10% by mass or more and 30% by mass or less. <1> or <2> The image forming unit described above. <4> The proportion of the polyvinyl butyral resin to the total amount of the polyamide resin and the polyvinyl butyral resin is 15% by mass or more and 20% by mass or less. <3> The image forming unit described above. <5> The ten-point average roughness RzJIS (JIS B0601:2013) of the outer surface of the charging member is 5.9 μm or less. <1> ~ <4> An image forming unit as described in any one of the following. <6> <1> ~ <5> The image forming unit is provided as described in any one of the following: To be attached to and detached from the image forming apparatus, Process cartridge. <7> <1> ~ <5> An image forming unit as described in any one of the following, An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged photoreceptor, A developing apparatus that develops an electrostatic latent image formed on the surface of a photoreceptor using a developer containing toner to form a toner image, The system includes a transfer device for transferring the toner image onto the surface of a recording medium. Image forming apparatus. [Effects of the Invention]

[0007] <1> or <2> According to the report, compared to an image forming unit in which the silicon element concentration on the surface of the surface layer of the charged member is less than 0.2 atm%, image fogging is less likely to occur in low-temperature, low-humidity environments, and compared to an image forming unit in which the silicon element concentration on the surface of the surface layer of the charged member is more than 1.2 atm%, an image forming unit is provided in which streaky density unevenness is less likely to occur in images. <3> or <4> According to the report, compared to an image forming unit in which the proportion of polyvinyl butyral resin in the total amount of polyamide resin and polyvinyl butyral resin contained in the surface layer of the charging member is less than 10% by mass or more than 30% by mass, an image forming unit is provided that is less prone to image fogging in low-temperature, low-humidity environments. <5> According to this, compared to an image forming unit in which the ten-point average roughness RzJIS of the outer surface of the charged member exceeds 5.9 μm, an image forming unit is provided that is less prone to image fogging in low-temperature and low-humidity environments. <6> According to the report, a process cartridge is provided that is less prone to image fringing in low-temperature, low-humidity environments compared to a process cartridge in which the silicon element concentration on the surface layer of the charged member is less than 0.2 atm%, and less prone to streaky density unevenness in images compared to a process cartridge in which the silicon element concentration on the surface layer of the charged member is more than 1.2 atm%. <7> According to the findings, compared to an image forming apparatus in which the silicon element concentration on the surface of the surface layer of the charged member is less than 0.2 atm%, image fogging is less likely to occur in low-temperature, low-humidity environments, and compared to an image forming apparatus in which the silicon element concentration on the surface of the surface layer of the charged member is more than 1.2 atm%, an image forming apparatus is provided in which streaky density unevenness is less likely to occur in images. [Brief explanation of the drawing]

[0008] [Figure 1] This is a partial cross-sectional view showing an example of the layer configuration of the photoreceptor in the image forming unit of the present disclosure. [Figure 2] This is a schematic perspective view showing an example of a charging member included in the image forming unit of this disclosure. [Figure 3] This is a schematic cross-sectional view showing an example of a charging member included in the image forming unit of the present disclosure, and is a cross-sectional view AA of Figure 2. [Figure 4] This is a schematic diagram showing an example of an image forming apparatus according to the present disclosure. [Figure 5] This is a schematic diagram showing another example of the image forming apparatus disclosed herein. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure are described below. These descriptions and embodiments are illustrative and do not limit the scope of the embodiments.

[0010] In this disclosure, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" may be A alone, B alone, or a combination of A and B.

[0011] In this disclosure, the numerical range indicated using "~" represents a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0012] In this disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that their objectives are achieved.

[0013] When embodiments are described in this disclosure with reference to the drawings, the configuration of such embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the components are not limited thereto.

[0014] In this disclosure, each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition in this disclosure, if there are multiple types of the substance corresponding to each component in the composition, it means the total amount of those multiple types of substances present in the composition unless otherwise specified. In this disclosure, each component may contain multiple types of particles. If multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for a mixture of such multiple types of particles present in the composition, unless otherwise specified.

[0015] In this 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 direction of rotation of the charged member.

[0016] In this disclosure, when the layering relationship of the layers constituting the charged member is expressed as "upper layer" and "lower layer," the layer closer to the photoreceptor is called the "upper layer," and the layer further away from the photoreceptor is called the "lower layer."

[0017] <Image Forming Unit> The image forming unit disclosed herein comprises a photoreceptor and a charging member (a so-called contact-type charging member) that contacts the surface of the photoreceptor and charges the photoreceptor. The photoreceptor in the image forming unit of the present disclosure comprises a conductive substrate and a laminated photoreceptor having a charge generating layer and a charge transport layer disposed on the conductive substrate, wherein the charge transport layer contains a polyarylate resin and substantially does not contain an organofluorine compound. The charging member of the image forming unit of this disclosure comprises a support member, an elastic layer disposed on the support member, and a surface layer disposed on the elastic layer, wherein the surface layer contains a resin, conductive particles, and a silicon compound, and the silicon element concentration on the surface of the surface layer is 0.2 atm% or more and 1.2 atm% or less.

[0018] The image forming unit disclosed herein is less prone to image fogging and less prone to streaky density unevenness in images in low-temperature, low-humidity environments.

[0019] The surface of the surface layer of the charged component is the surface that comes into contact with the photoreceptor. If the silicon element concentration on the surface layer of the charged member is less than 0.2 atm%, the ten-point average roughness RzJIS (JIS B0601:2013) of the outer surface of the charged member increases, and the surface resistance increases, making image fringing more likely to occur in low-temperature, low-humidity environments. From the viewpoint of suppressing this phenomenon, the silicon element concentration on the surface layer of the charged member should be 0.2 atm or higher, and more preferably 0.3 atm or higher. If the silicon element concentration on the surface of the surface layer of the charged member exceeds 1.2 atm%, contact charging with the photoreceptor is likely to occur, and streaky density unevenness is likely to occur in the image. From the viewpoint of suppressing this phenomenon, the silicon element concentration on the surface of the surface layer of the charged member is 1.2 atm or less, more preferably 1.1 atm or less, and even more preferably 1.0 atm or less. The silicon element concentration on the surface of the surface layer of the charged member is particularly preferably 0.3 atm% to 1.0 atm%.

[0020] The photoreceptor and the charging component will be described in detail below.

[0021] [Photoreceptor] Figure 1 is a schematic partial cross-sectional view showing an example of the layer structure of a photoreceptor. The photoreceptor 10A shown in Figure 1 has a structure in which a base layer 2, a charge generation layer 3, and a charge transport layer 4 are stacked in this order on a conductive substrate 1, with the charge generation layer 3 and the charge transport layer 4 constituting the photosensitive layer 5 (stacked photosensitive layer). The base layer 1 may or may not be present. The photoreceptor 10A may also have an intermediate layer (not shown) between the base layer 1 and the charge generation layer 3.

[0022] The charge transport layer of the photoreceptor contains a polyarylate resin. In the polyarylate resin, the resin molecules are bound together by intermolecular forces through the stacking of aromatic rings, which improves the wear resistance of the charge transport layer. A polycondensate of bisphenols and aromatic divalent carboxylic acids is preferred as the polyarylate resin.

[0023] The charge transport layer of the photoreceptor is substantially free of organofluorine compounds. If the charge transport layer contains organofluorine compounds, the charge in that layer tends to decrease below the expected value, making it easy for streaky density unevenness to occur in the image. Examples of organofluorine compounds include polytetrafluoroethylene, polyvinylidene fluoride resins, fluorinated rubber, fluorinated graft polymers, and fluorinated surfactants.

[0024] The statement that a charge transport layer is substantially free of organofluorine compounds means that the mass percentage of organofluorine compounds in the total mass of the charge transport layer is 1% by mass or less. The mass percentage of the organofluorine compound in the total mass of the charge transport layer is preferably as low as possible, preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0% by mass. In other words, it is particularly preferable that the charge transport layer does not contain an organofluorine compound.

[0025] -Conductive substrate- Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Other examples of conductive substrates include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. Here, "conductive" refers to a volume resistivity of 1 × 10⁻⁶. 13 This refers to a value less than Ω·cm.

[0026] When an electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center-line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiated with laser light. When non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for a longer lifespan because it suppresses the occurrence of defects due to surface irregularities of the conductive substrate.

[0027] Methods for roughening a surface include, for example, wet honing, which involves suspending an abrasive in water and spraying it onto a conductive substrate; centerless grinding, which involves pressing a conductive substrate against a rotating grinding wheel and continuously grinding it; and anodizing.

[0028] One method for roughening the surface is to disperse conductive or semiconductive powder in a resin without roughening the surface of the conductive substrate, to form a layer on the surface of the conductive substrate, and then roughen the surface with the particles dispersed in that layer.

[0029] Anodizing roughening treatment involves forming an oxide film on the surface of a conductive substrate (e.g., aluminum) by anodizing it in an electrolyte solution. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodizing is chemically active, easily contaminated, and exhibits large resistance fluctuations depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film to block the micropores of the oxide film by volume expansion due to a hydration reaction using pressurized steam or boiling water (metal salts such as nickel may be added), thereby converting it into a more stable hydrated oxide.

[0030] The thickness of the anodic oxide film is preferably, for example, 0.3 μm to 15 μm. When the film thickness is within this range, it tends to exhibit barrier properties against injection and tends to suppress the increase in residual potential due to repeated use.

[0031] The conductive substrate may be treated with an acidic treatment solution or with boehmite. Treatment with an acidic solution is carried out, for example, as follows: First, an acidic solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic solution is, for example, in the range of 10% to 11% by mass for phosphoric acid, 3% to 5% by mass for chromic acid, and 0.5% to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness is preferably 0.3 μm to 15 μm.

[0032] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting it with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. This can be further treated with anodic oxidation using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0033] -Sublayer- The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0034] As for inorganic particles, for example, powder resistance (volume resistivity) 1 × 10 2 Ω cm or more 1×10 11 Examples include inorganic particles with a size of Ω·cm or less. Among these, suitable inorganic particles having the above-mentioned resistance values ​​include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, with zinc oxide particles being particularly preferred.

[0035] The specific surface area of ​​inorganic particles using the BET method is, for example, 10 m². 2 A value of 1g or more is preferable. The volume-average particle size of the inorganic particles is preferably between 50 nm and 2000 nm (preferably between 60 nm and 1000 nm).

[0036] The inorganic particle content is preferably 10% by mass or more and 80% by mass or less relative to the binder resin, and more preferably 40% by mass or more and 80% by mass or less.

[0037] The inorganic particles may be surface-treated. Two or more types of inorganic particles with different surface treatments or particle sizes may be mixed and used.

[0038] Examples of surface treatment agents include silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and surfactants. Silane coupling agents are particularly preferred, and silane coupling agents having an amino group are more preferred.

[0039] Examples of silane coupling agents having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0040] Silane coupling agents may be used in combination of two or more types. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0041] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry or wet method.

[0042] The amount of surface treatment agent applied is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0043] In this case, it is preferable for the underlayer to contain electron-accepting compounds (acceptor compounds) along with inorganic particles, from the viewpoint of improving the long-term stability of electrical properties and carrier blocking ability.

[0044] Examples of electron-accepting compounds include electron-transporting substances such as: compounds having an anthraquinone structure; quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; and benzophenone compounds such as 4-hydroxybenzophenone and 2,3,4-trihydroxybenzophenone. In particular, compounds having an anthraquinone structure are preferred as electron-accepting compounds. Examples of compounds having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds. Specifically, examples of preferred compounds include anthraquinone, alizarin, quinizarin, anthralphine, purpurin, 4-ethoxy-1,2-hydroxy-9,10-anthraquinone, and their derivatives.

[0045] The electron-accepting compound may be dispersed in the underlayer together with inorganic particles, or it may be present attached to the surface of the inorganic particles.

[0046] Methods for attaching electron-accepting compounds to the surface of inorganic particles include, for example, dry methods or wet methods.

[0047] The dry method involves, for example, adding an electron-accepting compound, either directly or dissolved in an organic solvent, dropwise while stirring inorganic particles with a mixer that has a high shear force, or spraying it with dry air or nitrogen gas, to adhere the electron-accepting compound to the surface of the inorganic particles. When adding or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After adding or spraying the electron-accepting compound, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained.

[0048] The wet method involves dispersing inorganic particles in a solvent using, for example, a stirrer, ultrasonic disperser, sand mill, attritor, or ball mill, while adding an electron-accepting compound. After stirring or dispersion, the solvent is removed, and the electron-accepting compound adheres to the surface of the inorganic particles. Solvent removal methods include, for example, filtration or distillation. After solvent removal, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may be removed before adding the electron-accepting compound. Examples of this include removing water while stirring and heating in the solvent, or removing water by azeotrope with the solvent.

[0049] The electron-accepting compound may be applied before or after surface treatment with a surface treatment agent to the inorganic particles, or it may be applied simultaneously with the surface treatment with the surface treatment agent.

[0050] The content of the electron-accepting compound is preferably, for example, 0.01% by mass or more and 20% by mass or less relative to the inorganic particles, and more preferably 0.01% by mass or more and 10% by mass or less.

[0051] Examples of known polymer compounds used as the binder resin for the undercoat include acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, unsaturated polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, alkyd resin, epoxy resin, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. Examples of binder resins used in the undercoat include charge-transporting resins having charge-transporting groups, conductive resins (e.g., polyaniline), and the like.

[0052] Among these, a resin insoluble in the coating solvent of the upper layer is preferred as the binder resin used for the undercoat layer. In particular, a resin obtained by the reaction of a curing agent with at least one resin selected from the group consisting of thermosetting resins such as urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, and epoxy resin is preferred. When using two or more of these binder resins in combination, the mixing ratio is set as needed.

[0053] The undercoat may contain various additives to improve electrical properties, environmental stability, and image quality. Examples of known additives include electron-transporting pigments such as polycyclic condensation and azo pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but they may also be added to the undercoat as additives.

[0054] Examples of silane coupling agents used as additives include vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0055] Examples of zirconium chelate compounds include zirconium butoxide, ethyl zirconium acetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0056] Examples of titanium chelate compounds include tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0057] Examples of aluminum chelating compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0058] These additives may be used individually or as a mixture or polycondensate of multiple compounds.

[0059] The underlayer should ideally have a Vickers hardness of 35 or higher. The surface roughness (ten-point average roughness) of the undercoat layer should be adjusted to between 1 / (4n) (where n is the refractive index of the upper layer) and 1 / 2 of the exposure laser wavelength λ used, in order to suppress moiré patterns. Resin particles may be added to the undercoat to adjust the surface roughness. Examples of resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. The surface of the undercoat may also be polished to adjust the surface roughness. Polishing methods include buffing, sandblasting, wet honing, and grinding.

[0060] The formation of the undercoat is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of an undercoat-forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0061] Solvents for preparing the coating solution for forming the undercoat include known organic solvents such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0062] Known methods for dispersing inorganic particles when preparing a coating solution for forming an undercoat include, for example, roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, and paint shakers.

[0063] Conventional methods for applying the undercoating solution onto a conductive substrate include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0064] The thickness of the undercoat layer is preferably set to a range of 15 μm or more, and more preferably within the range of 20 μm to 50 μm.

[0065] -Middle class- The intermediate layer is, for example, a layer containing a resin. Examples of resins used in the intermediate layer include polymer compounds such as acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin. The intermediate layer may contain an organometallic compound. Examples of organometallic compounds used in the intermediate layer include those containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in these intermediate layers may be used individually, as a mixture of multiple compounds, or as polycondensates.

[0066] Among these, the intermediate layer is preferably a layer containing an organometallic compound that contains zirconium atoms or silicon atoms.

[0067] The formation of the intermediate layer is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of an intermediate layer-forming coating solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary. Conventional methods such as immersion coating, push-up coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating are used to form the intermediate layer.

[0068] The thickness of the intermediate layer is preferably set in the range of 0.1 μm to 3 μm. The intermediate layer may also be used as a base layer.

[0069] -Charge generation layer- The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. Alternatively, the charge generation layer may be a vapor-deposited layer of the charge generation material. A vapor-deposited layer of the charge generation material is suitable when using non-coherent light sources such as LEDs (Light Emitting Diodes) or organic EL (Electro-Luminescence) image arrays.

[0070] Examples of charge-generating materials include azo pigments such as bisazo and trisazo; fused aromatic pigments such as dibromoanthonthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0071] Among these, in order to accommodate laser exposure in the near-infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material. Specifically, for example, hydroxygallium phthalocyanine; chlorogallium phthalocyanine; dichlorotin phthalocyanine; and titanyl phthalocyanine are more preferable.

[0072] On the other hand, to accommodate laser exposure in the near-ultraviolet region, preferred charge-generating materials include fused aromatic pigments such as dibromoanthoten; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and bisazo pigments.

[0073] The above charge generating material may also be used when using non-coherent light sources such as LEDs and organic EL image arrays, which have a central emission wavelength between 450 nm and 780 nm.

[0074] When n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark currents are less likely to be generated, and image defects called black spots can be suppressed even in thin films. The n-type is determined using the commonly used time-of-flight method, which is determined by the polarity of the photocurrent that flows, and materials that readily carry electrons as carriers rather than holes are classified as n-type.

[0075] The binder resin used in the charge generation layer can be selected from a wide range of insulating resins, or it may be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Examples of binder resins include polyvinyl butyral resin, polyarylate resin (such as polycondensates of bisphenols and aromatic divalent carboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinylpyrrolidone resin. Here, "insulating properties" refer to a volume resistivity of 1 × 10⁻⁶. 13This refers to a density of Ω·cm or greater. These binder resins can be used individually or in mixtures of two or more types.

[0076] The mixing ratio of the charge-generating material to the binder resin is preferably within the range of 10:1 to 1:10 by mass ratio.

[0077] The charge generation layer may also contain other known additives.

[0078] The formation of the charge generation layer is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of a coating solution for forming a charge generation layer by adding the above components to a solvent, drying the coating film, and heating it as necessary. The charge generation layer may also be formed by vapor deposition of a charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when using fused ring aromatic pigments or perylene pigments as the charge generation material.

[0079] Solvents for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. These solvents may be used individually or in mixtures of two or more.

[0080] Methods for dispersing particles (e.g., charge-generating material) in a coating solution for forming a charge-generating layer include, for example, media dispersers such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, as well as media-less dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include collision methods, in which the dispersion is dispersed by liquid-liquid collisions or liquid-wall collisions under high pressure, and penetration methods, in which the dispersion is dispersed by penetrating fine channels under high pressure. During dispersion, it is effective to set the average particle size of the charge-generating material in the coating solution for forming the charge-generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0081] Conventional methods for applying the charge-generating layer forming coating solution onto the undercoat (or intermediate layer) include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0082] The thickness of the charge generation layer is preferably set within the range of 0.1 μm to 5.0 μm, and more preferably within the range of 0.2 μm to 2.0 μm.

[0083] -Charge transport layer- The charge transport layer is, for example, a layer containing a binder resin and a charge transport material. The charge transport layer may also be a layer containing a polymer charge transport material.

[0084] Examples of charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds, which are electron transport compounds. Other examples of charge transport materials include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used individually or in combination of two or more, but are not limited to these.

[0085] Examples of polymeric charge transport materials include known chemical substances with charge transport properties such as poly-N-vinylcarbazole and polysilane. For example, polyester-based polymeric charge transport materials are preferred. Polymeric charge transport materials may be used alone or in combination with a binder resin.

[0086] Examples of the charge transport material or polymer charge transport material include polycyclic aromatic compounds, aromatic nitro compounds, aromatic amine compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds (particularly triphenylamine compounds), diamine compounds, oxadiazole compounds, carbazole compounds, organopolysilane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, cyano compounds, benzofuran compounds, aniline compounds, butadiene compounds, and resins having groups derived from these substances. Specifically, the compounds described in paragraphs 0078 to 0080 of JP-A No. 2021-117377, paragraphs 0046 to 0048 of JP-A No. 2019-035900, paragraphs 0052 to 0053 of JP-A No. 2019-012141, paragraphs 0122 to 0134 of JP-A No. 2021-071565, paragraphs 0101 to 0110 of JP-A No. 2021-015223, paragraph 0116 of JP-A No. 2013-097300, paragraphs 0309 to 0316 of WO 2019 / 070003, paragraphs 0103 to 0107 of JP-A No. 2018-159087, and paragraphs 0102 to 0113 of JP-A No. 2021-148818 are included.

[0087] From the viewpoint of charge mobility, the charge transport material preferably contains at least one selected from the group consisting of a chemical substance (C1) represented by the following formula (C1), a chemical substance (C2) represented by formula (C2), a chemical substance (C3) represented by formula (C3), and a chemical substance (C4) represented by formula (C4).

[0088] ​​​​​​​​​​​​​​​​​T5 )(R T6 ) or -C6H4-CH=CH-CH=C(R T7 )(R T8 ) is R T4 , R T5 , R T6 , R T7 and R T8 Each of these is independently a hydrogen atom, an alkyl group, or an aryl group. T5 and R T6 When it is an aryl group, the aryl groups are -C(R 51 )(R 52 )-and / or-C(R 61 )=C(R 62 )- may be linked by a divalent group. R 51 , R 52 , R 61 and R 62 Each of these is independently either a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0090] The group in formula (C1) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0091] As for the chemical substance (C1), from the viewpoint of charge mobility, it is an aryl group or -C6H4-CH=CH-CH=C(R T7 )(R T8 A chemical substance having at least one of the following is preferred, and a chemical substance (C'1) represented by the following formula (C'1) is more preferred.

[0092] [ka]

[0093] In equation (C'1), R T111 , R T112 , R T121 , R T122 , R T131 and R T132Each of these is independently a hydrogen atom, a halogen atom, an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 3 carbon atoms), a phenyl group, or a phenoxy group. Tj1, Tj2, Tj3, Tk1, Tk2, and Tk3 are each independently 0, 1, or 2.

[0094] [ka]

[0095] In equation (C2), R T201 , R T202 , R T211 and R T212 Each of these is independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, and -C(R T21 )=C(R T22 )(R T23 ) or -CH=CH-CH=C(R T24 )(R T25 ) is R T21 , R T22 , R T23 , R T24 and R T25 Each of these is independently a hydrogen atom, an alkyl group, or an aryl group. T221 and R T222 Each of these is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. Tm1, Tm2, ​​Tn1, and Tn2 are each independently 0, 1, or 2.

[0096] The group in formula (C2) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0097] As for the chemical substance (C2), from the viewpoint of charge mobility, alkyl groups, aryl groups, or -CH=CH-CH=C(R T24 )(R T25A chemical substance having at least one alkyl group, aryl group, or -CH=CH-CH=C(R T24 )(R T25 A chemical substance having two of these is more preferable.

[0098] [ka]

[0099] In equation (C3), R T301 , R T302 , R T311 and R T312 Each of these is independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, and -C(R T31 )=C(R T32 )(R T33 ) or -CH=CH-CH=C(R T34 )(R T35 ) is R T31 , R T32 , R T33 , R T34 and R T35 Each of these is independently a hydrogen atom, an alkyl group, or an aryl group. T321 , R T322 and R T331 Each of these is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. To1, To2, Tp1, Tp2, Tq1, Tq2, and Tr1 are each independently 0, 1, or 2.

[0100] The group in formula (C3) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0101] [ka]

[0102] In formula (C4), R T401 , R T402 , R T411 and R T412 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T41 )=C(R T42 )(R T43 ) or -CH=CH-CH=C(R T44 )(R T45 ). R T41 , R T42 , R T43 , R T44 and R T45 are each independently a hydrogen atom, an alkyl group or an aryl group. R T421 , R T422 and R T431 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2 and Tv1 are each independently 0, 1 or 2.

[0103] The groups in formula (C4) may be substituted by a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0104] The charge transport layer contains at least a polyarylate resin as a binder resin and may contain other binder resins other than the polyarylate resin. Examples of the other binder resins include polycarbonate resins, aliphatic polyester resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, polysilanes and the like. The preferred mixing ratio of the charge transport material to the binder resin is between 10:1 and 1:5 by mass.

[0105] When the charge transport layer is the outermost layer of the photoreceptor, the charge transport layer may contain a phenol compound having three or fewer phenolic functional groups and a molecular weight of 300 or more. The preferred form of the phenol compound is as follows.

[0106] From the viewpoint of suppressing molecular polarity, phenol compounds with three or fewer phenolic functional groups and a molecular weight of 300 or more are preferable to have a small number of phenolic functional groups and a large molecular weight. The number of phenolic functional groups in the phenol compound is 3 or less, preferably 1 or 2. The molecular weight of the phenol compound is 300 or more, preferably 350 or more, more preferably 400 or more, and even more preferably 450 or more. From the viewpoint of easy dispersion in the outermost layer, the upper limit of the molecular weight of the phenol compound is preferably 1000 or less, more preferably 900 or less, and even more preferably 800 or less. The phenol compound is preferably a phenol compound having two or fewer phenolic functional groups and a molecular weight of 350 or more, preferably a phenol compound having two or fewer phenolic functional groups and a molecular weight of 350 to 1000, more preferably a phenol compound having two or fewer phenolic functional groups and a molecular weight of 400 to 900, and even more preferably a phenol compound having two or fewer phenolic functional groups and a molecular weight of 450 to 800. In this disclosure, the phenolic functional group of a phenol compound means a hydroxyl group bonded to a benzene ring.

[0107] Hindered phenol compounds are examples of phenol compounds having three or fewer phenolic functional groups and a molecular weight of 300 or more. Hindered phenol compounds are generally compounds in which at least one of the ortho positions of the hydroxyl group of phenol is substituted with a bulky group, and are known to exhibit an antioxidant effect on compositions. Hindered phenol compounds may be used individually or in combination of two or more.

[0108] Examples of hindered phenol compounds include the following: • Alkylated monophenol compounds and their derivatives: for example, octyl-3,5-di-t-butyl-4-hydroxy-hydrocinnamate • Alkylthiomethylphenol compounds and their derivatives: For example, 2,4-dioctylthiomethyl-6-t-butylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-didodecylthiomethyl-4-nonylphenol • Alkylidenebisphenol compounds and their derivatives: e.g., 4,4'-Butylidenebis(6-t-butyl-3-methylphenol), 2,2'-Methylenebis(6-t-butyl-4-methylphenol), 2,2'-Methylenebis(6-t-butyl-4-ethylphenol), 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 3,9-bis[2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane

[0109] Commercially available hindered phenol compounds include ADEKA Corporation's "ADEKA Stab AO-80," "ADEKA Stab AO-50," "ADEKA Stab AO-40," "ADEKA Stab AO-30," "ADEKA Stab AO-20," and "ADEKA Stab AO-330," BASF Japan Ltd.'s "Irganox 245," "Irganox 1076," and "Irganox 1520," and Sumitomo Chemical Co., Ltd.'s "Sumilizer GA-80," "Sumilizer GM," and "Sumilizer GS."

[0110] The content of phenolic compounds in the outermost layer is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less, and even more preferably 1% by mass or more and 5% by mass or less, based on the total mass of the outermost layer.

[0111] The charge transport layer may also contain other known additives.

[0112] The formation of the charge transport layer is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of a charge transport layer forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0113] Suitable solvents for preparing the coating solution for forming the charge transport layer include common organic solvents such as aromatic hydrocarbons like benzene, toluene, xylene, and chlorobenzene; ketones like acetone and 2-butanone; halogenated aliphatic hydrocarbons like methylene chloride, chloroform, and ethylene chloride; and cyclic or linear ethers like tetrahydrofuran and ethyl ether. These solvents can be used individually or in mixtures of two or more.

[0114] Conventional methods for applying a charge transport layer forming coating solution onto a charge generation layer include blade coating, wire bar coating, spray coating, immersion coating, bead coating, air knife coating, and curtain coating.

[0115] The thickness of the charge transport layer is preferably set within the range of 5 μm to 50 μm, more preferably 8 μm to 45 μm, and even more preferably 10 μm to 40 μm.

[0116] [Charging component] The charging member may be a charging member that is charged using a method in which only a direct current voltage is applied (DC charging method), a charging member that is charged using a method in which only an alternating current voltage is applied (AC charging method), or a charging member that is charged using a method in which a voltage obtained by superimposing an alternating current voltage on a direct current voltage is applied (AC / DC charging method).

[0117] The charging member contacts the surface of the photoreceptor to charge it. The charging member comprises a support member, an elastic layer placed on the support member, and a surface layer placed on the elastic layer. The charging member may be in the form of a roll or a belt.

[0118] Figure 2 is a schematic perspective view showing an example of a charged member. Figure 3 is a cross-sectional view AA of Figure 2, which is a cross-sectional view of the charged member shown in Figure 2, cut radially. The charging member 30 shown in Figure 2 is a roll-shaped charging member. The charging member 30 has a structure in which an elastic layer 34 and a surface layer 36 are laminated in that order on a support member 32. The charging 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 charging member 30.

[0119] From the viewpoint of minimizing image fogging in low-temperature, low-humidity environments, the charged member preferably has a ten-point average roughness RzJIS (JIS B0601:2013) of 5.9 μm or less on its outer surface (i.e., the surface of the surface layer), more preferably 5.7 μm or less, and even more preferably 5.5 μm or less. The ten-point average roughness RzJIS of the outer surface of the charged member is preferably 5.0 μm or more, from the viewpoint of ease of implementation.

[0120] The ten-point average roughness RzJIS of the outer surface of the charged component shall be measured in accordance with the provisions of JIS B0601:2013. The measurement environment is 22°C and 55% relative humidity. The sample is placed in the measurement environment for 24 hours or more to control temperature and humidity. A contact-type surface roughness measuring instrument (Surfcom, Tokyo Seimitsu Co., Ltd.) is used, with a conical probe having a 90° apex angle, a tip curvature radius of 5 μm, and a diamond tip material. The instrument is scanned axially at the axial center of the charged material, with a scanning speed of 0.30 mm / second, a measurement length of 4.0 mm, and a cutoff value of 0.8 mm.

[0121] The surface roughness of the outer surface of the charged member can be controlled by the particle size and content of particulate components contained in the surface layer.

[0122] -Support member- The support member is a conductive member that functions as an electrode and support for the charged member. The support member may be a hollow member or a non-hollow member, for example, a rod-shaped, cylindrical, or endless belt-shaped member.

[0123] Examples of support members include metal members such as iron (free-cutting steel, etc.), copper, copper alloys, brass, stainless steel, aluminum, and nickel; iron members plated with chromium, nickel, etc.; resin or ceramic members with plated outer surfaces; and resin or ceramic members containing conductive agents.

[0124] -Elastic layer- The elastic layer is conductive, and its volume resistivity at 20°C is 1 × 10⁻⁶. 3 Ω cm or more 1×10 14 It is preferable that the value is Ω·cm or less.

[0125] The volume resistivity of the elastic layer is the value measured by the following method. After removing the surface layer of the charged material by polishing, the elastic layer is cut from the axial center of the charged material to a length of 25 mm in the axial direction and 8 mm in the circumferential direction, and this is used as the sample. The thickness of the sample (i.e., the elastic layer) is measured. Using a measuring jig (R12702A / B Resistivity Chamber: Advantest Corporation) and a high-resistance meter (R8340A Digital High-Resistance / Micro-Ammeter: Advantest Corporation) in accordance with JIS K 6911:1995, a voltage adjusted to produce an electric field (applied voltage / composition sheet thickness) of 1000 V / cm is applied to the sample for 30 seconds. The current value is read and calculated using the following formula. Volume resistivity (Ω cm) = (sample area (cm 2 ((Current value (A) × Applied voltage (V)) / (Sample thickness (cm))

[0126] The elastic layer may be a foamed elastic layer or a non-foamed elastic layer. The elastic layer may be directly placed on the outer surface of the support member, or it may be placed on the outer surface of the support member via an adhesive layer.

[0127] An example of an embodiment of the elastic layer includes an elastic material, a conductive agent, and other additives.

[0128] Examples of elastic materials 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, fluororubber, 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.

[0129] Examples of conductive agents include electronic conductive agents and ionic conductive agents. Examples of electronic conductive agents include powders such as carbon black 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; and materials whose insulating surfaces have been treated to become conductive. Examples of ionic conductive agents include perchlorates or chlorates such as tetraethylammonium, lauryltrimethylammonium, and benzyltrialkylammonium; and perchlorates or chlorates of alkali metals or alkaline earth metals such as lithium and magnesium. Conductive agents may be used individually or in combination of two or more types.

[0130] The total amount of conductive agent contained in the elastic layer is preferably set based on the volume resistivity of the elastic layer. When an electronically conductive agent is used as the conductive material, the total amount of the electronically conductive agent may be, for example, 1 to 20 parts by mass, or 3 to 20 parts by mass, per 100 parts by mass of the elastic material. When an ionic conductive agent is used as the conductive material, the total amount of the ionic conductive agent may be, for example, 0.1 parts by mass or more and 10 parts by mass or 0.5 parts by mass or more and 5 parts by mass per 100 parts by mass of the elastic material.

[0131] The average primary particle size of the conductive agent is preferably between 1 nm and 500 nm, and more preferably between 5 nm and 200 nm. The average primary particle size of the conductive agent is determined by observing the cross-section of the elastic layer with an electron microscope, measuring the major axis of 100 conductive agent particles, and taking the arithmetic mean of the results.

[0132] Carbon black is preferred as the conductive agent. The average primary particle size of the carbon black is preferably 1 nm to 500 nm, and more preferably 5 nm to 200 nm. The carbon black content is preferably 1 to 20 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of elastic material.

[0133] Other additives include vulcanizing agents, vulcanization accelerators, vulcanization accelerators, fillers, softeners, plasticizers, hardeners, antioxidants, surfactants, and coupling agents.

[0134] Examples of fillers include calcium carbonate, silica, and clay minerals. A single filler may be used, or two or more may be used in combination.

[0135] Calcium carbonate is preferred as a filler. The calcium carbonate content is preferably 1 to 50 parts by mass, and more preferably 10 to 40 parts by mass, per 100 parts by mass of elastic material.

[0136] The thickness of the elastic layer is preferably 5 mm to 20 mm, and more preferably 10 mm to 15 mm. The thickness of the elastic layer is measured by imaging the cross-section with an electron microscope. Measurements are taken at four points in the circumferential direction at 90° intervals in the axial center of the charged member, and the arithmetic mean value is taken as the thickness of the elastic layer.

[0137] Methods for forming an elastic layer on a support member include, for example, extruding an elastic layer-forming composition, which is a mixture of an elastic material, a conductive agent, and other additives, and a cylindrical support member together from an extrusion molding machine to form a layer of the elastic layer-forming composition on the outer surface of the support member, and then heating the layer of the elastic layer-forming composition to cause a crosslinking reaction (including vulcanization) to form an elastic layer; and extruding an elastic layer-forming composition, which is a mixture of an elastic material, a conductive agent, and other additives, from an extrusion molding machine onto the outer surface of an endless belt-shaped support member to form a layer of the elastic layer-forming composition on the outer surface of the support member, and then heating the layer of the elastic layer-forming composition to cause a crosslinking reaction (including vulcanization) to form an elastic layer. The support member may have an adhesive layer on its outer surface.

[0138] -Adhesive layer- An adhesive layer may be provided between the support member and the elastic layer to bond them together. Specific examples of adhesive layers interposed between the support member and the elastic layer include layers containing resins such as polyolefin, acrylic resin, epoxy resin, polyurethane, nitrile rubber, chlorine rubber, vinyl chloride resin, vinyl acetate resin, polyester, phenolic resin, and silicone resin. The adhesive layer may also contain a conductive agent (for example, the aforementioned electronic conductive agent or ionic conductive agent).

[0139] From the viewpoint of adhesion between the elastic layer and the support member, the thickness of the adhesive layer is preferably 1 μm to 50 μm, more preferably 2 μm to 40 μm, and even more preferably 5 μm to 20 μm. The thickness of the adhesive layer is measured by imaging the cross-section with an electron microscope. Measurements are taken at four points in the circumferential direction at 90° intervals in the axial center of the charged member, and the arithmetic mean value is taken as the thickness of the adhesive layer.

[0140] -Surface layer- The surface layer is conductive, and its volume resistivity at 20°C is 1 × 10⁻⁶.3 Ω cm or more 1×10 14 It is preferable that it be Ω·cm or less. The volume resistivity of the surface layer is a value measured by the following method.

[0141] The thickness of the surface layer is measured using the measurement method described below. The support member of the charged component is used as the cathode, and a 1.5 cm wide aluminum plate wrapped around the surface layer is used as the anode. An SI 1260 impedance / gain phase analyzer (Toyo Technica Co., Ltd.) is used as the power supply and ammeter, and a 1296 dielectric interface (Toyo Technica Co., Ltd.) is used as the current amplifier. An AC voltage of 1 Vp-p is applied from the high-frequency side from 1 kHz to 0.01 Hz. The resistance component of the impedance in the range of 100 Hz to 0.1 Hz is determined as the volume resistivity of the surface layer. The volume resistivity of the surface layer is calculated using the following formula. Volume resistivity (Ω·cm) = Volume resistivity (Ω) × Anode area (cm²) 2 ) / Surface layer thickness (cm)

[0142] The surface layer contains resin, conductive particles, and a silicon compound.

[0143] Examples of resins include copolymerized nylon, polyamide, polyimide, polyamide-imide, 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, resins obtained by mixing two or more of these, and resins obtained by curing or crosslinking at least one of these with a curing agent or catalyst. The resin may be used individually or in combination of two or more.

[0144] From the viewpoint of suppressing contamination of the surface layer, the resin contained in the surface layer is preferably polyamide resin, polyvinylidene fluoride resin, or tetrafluoroethylene resin, with polyamide resin being more preferred. As for the polyamide resin, from the viewpoint of suppressing contamination of the surface layer, alcohol-soluble polyamide is preferred, alkoxymethylated polyamide (e.g., alkoxymethylated nylon) is more preferred, and methoxymethylated polyamide (e.g., methoxymethylated nylon) is even more preferred.

[0145] The surface layer preferably contains polyvinyl butyral resin from the viewpoint of the binding properties of conductive particles. The surface layer preferably contains polyamide resin and polyvinyl butyral resin as binding resins from the viewpoint of suppressing contamination of the surface layer and forming excellent image quality, and from the viewpoint of the binding properties of conductive particles. In this embodiment, the proportion of polyvinyl butyral resin in the total amount of polyamide resin and polyvinyl butyral resin is preferably 10% by mass or more and 30% by mass or less, more preferably 12% by mass or more and 25% by mass or less, and even more preferably 15% by mass or more and 20% by mass or less.

[0146] Examples of conductive particles include carbon black; metal oxides such as tin oxide, titanium oxide, and zinc oxide; etc. Carbon black is preferred as the conductive particle included in the surface layer. Conductive particles may be used individually or in combination of two or more types.

[0147] From the viewpoint of excellent dispersibility in the resin, the conductive particles contained in the surface layer preferably have an average primary particle size of 10 nm to 50 nm. The average primary particle size of conductive particles is determined by observing a cross-section of the surface layer with an electron microscope, measuring the major axis of 100 conductive particles, and taking the arithmetic mean of these measurements.

[0148] The content of conductive particles in the surface layer is preferably 5 to 30 parts by mass, more preferably 8 to 25 parts by mass, and even more preferably 10 to 20 parts by mass, per 100 parts by mass of the binder resin.

[0149] Examples of silicon compounds include at least one silicone oil selected from the group consisting of dimethylpolysiloxane and organically substituted derivatives of dimethylpolysiloxane. Examples of organically substituted derivatives of dimethylpolysiloxane include polyether-modified silicone oil and methylstyryl-modified silicone oil.

[0150] From the viewpoint of image quality, the silicon compound content in the surface layer is preferably 0.01 parts by mass or more and 1 part by mass or less per 100 parts by mass of binder resin, more preferably 0.02 parts by mass or more and 0.5 parts by mass or less, and even more preferably 0.03 parts by mass or more and 0.1 parts by mass or less.

[0151] From the viewpoint of image quality, the content of silicone oil in the surface layer is preferably 0.01 parts by mass or more and 1 part by mass or less per 100 parts by mass of binder resin, more preferably 0.02 parts by mass or more and 0.5 parts by mass or less, and even more preferably 0.03 parts by mass or more and 0.1 parts by mass or less.

[0152] The surface layer may contain organic resin particles for the purpose of adjusting the surface roughness. The surface layer may contain various additives. Examples of additives include fillers, softeners, plasticizers, hardeners, antioxidants, coupling agents, surfactants, defoamers, and leveling agents.

[0153] The thickness of the surface layer is preferably 1 μm to 25 μm, preferably 3 μm to 20 μm, and more preferably 5 μm to 15 μm. The thickness of the surface layer is measured by imaging the cross-section with an electron microscope. Measurements are taken at four points in the circumferential direction at 90° intervals in the axial center of the charged member, and the arithmetic mean value is taken as the thickness of the surface layer.

[0154] One method for forming a surface layer on an elastic layer is to apply a surface layer forming composition, which is a mixture of resin, conductive particles, silicon compounds, and other additives, to the outer surface of the elastic layer to form a layer of the surface layer forming composition, and then to dry the layer of the surface layer forming composition. Examples of methods for applying the surface layer forming composition to the outer surface of the elastic layer include immersion coating, roll coating, blade coating, wire bar coating, spray coating, bead coating, air knife coating, and curtain coating.

[0155] <Image forming apparatus, process cartridge> The image forming apparatus disclosed herein comprises a photoreceptor, a charging member for charging the surface of the photoreceptor, an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the photoreceptor, a developing means for developing the electrostatic latent image formed on the surface of the photoreceptor with a developer containing toner to form a toner image, and a transfer means for transferring the toner image to the surface of a recording medium. The image forming unit disclosed herein is applied as the photoreceptor and the charging member.

[0156] The image forming apparatus of this disclosure includes known image forming apparatuses such as: an apparatus equipped with a fixing device for fixing a toner image transferred to the surface of a recording medium; a direct transfer apparatus for directly transferring a toner image formed on the surface of a photoreceptor to a recording medium; an intermediate transfer apparatus for first transferring a toner image formed on the surface of a photoreceptor to the surface of an intermediate transfer body, and secondarily transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; an apparatus equipped with a cleaning device for cleaning the surface of the photoreceptor after the transfer of the toner image and before charging; an apparatus equipped with a static elimination device for irradiating the surface of the photoreceptor with static elimination light to eliminate static charge after the transfer of the toner image and before charging; and an apparatus equipped with a photoreceptor heating member for raising the temperature of the photoreceptor and reducing the relative temperature.

[0157] In the case of an intermediate transfer method apparatus, the transfer apparatus may be configured to include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer apparatus that first transfers the toner image formed on the surface of the photoreceptor to the surface of the intermediate transfer body; and a secondary transfer apparatus that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0158] The image forming apparatus disclosed herein may be either a dry developing type image forming apparatus or a wet developing type image forming apparatus (a developing method using a liquid developer).

[0159] In the image forming apparatus of this disclosure, for example, the portion comprising the photoreceptor may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge comprising the image forming unit of this disclosure is preferably used. In addition to the photoreceptor and the charging member, the process cartridge may comprise at least one selected from the group consisting of, for example, an electrostatic latent image forming means, a developing means, and a transfer means.

[0160] The following is an example of an image forming apparatus according to the disclosure, but is not limited to this example. The main parts shown in the figure will be described, and the descriptions of other parts will be omitted.

[0161] Figure 4 is a schematic diagram showing an example of an image forming apparatus according to the present disclosure. As shown in Figure 4, the image forming apparatus 100 comprises a process cartridge 300, an exposure device 9 (an example of an electrostatic latent image forming apparatus), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is positioned to expose the photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 is positioned opposite the photoreceptor 7 via the intermediate transfer body 50, with a portion of the intermediate transfer body 50 in contact with the photoreceptor 7. Although not shown, it also has a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) are examples of transfer devices.

[0162] The process cartridge 300 integrally supports a photoreceptor 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, which is positioned to contact the surface of the photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member, rather than a cleaning blade 131, and may be used alone or in combination with the cleaning blade 131. The image forming unit of this disclosure is applied as the charging member of the photoreceptor 7 and the charging device 8.

[0163] Figure 4 shows an example of an image forming apparatus that includes a fibrous member 132 (roll-shaped) for supplying lubricant 14 to the surface of the photoreceptor 7, and a fibrous member 133 (flat brush-shaped) for assisting cleaning. These can be arranged as needed.

[0164] The following describes each component other than the photoreceptor 7 and the charging device 8.

[0165] -Exposure equipment- Examples of exposure devices 9 include optical equipment that exposes the surface of a photoreceptor 7 to a predetermined image using light such as semiconductor laser light, LED light, or liquid crystal shutter light. The wavelength of the light source is within the spectral sensitivity range of the photoreceptor. As for semiconductor lasers, near-infrared lasers with an oscillation wavelength of around 780 nm are the mainstream. However, the wavelength is not limited to this, and lasers with oscillation wavelengths in the 600 nm range or blue lasers with oscillation wavelengths between 400 nm and 450 nm may also be used. Furthermore, for color image formation, surface-emitting laser light sources capable of outputting multiple beams are also effective.

[0166] -Developing equipment- Examples of developing devices 11 include general developing devices that develop by contacting or not contacting the developing agent. There are no particular restrictions on the developing device 11 as long as it has the above-described functions, and it can be selected according to the purpose. For example, known developing devices that have the function of applying a one-component or two-component developing agent to the photoreceptor 7 using a brush, roller, etc. Among these, those that use a developing roller that holds the developing agent on its surface are preferred.

[0167] The developer used in the developing device 11 may be a one-component developer consisting of toner alone, or a two-component developer containing toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. Known developers can be used.

[0168] -Cleaning device- The cleaning device 13 uses a cleaning blade system equipped with a cleaning blade 131. In addition to the cleaning blade system, a fur brush cleaning system or a developing and cleaning system may also be used.

[0169] -Transfer device- Examples of the transfer device 40 include contact-type transfer chargers using belts, rollers, films, rubber blades, etc., and transfer chargers that are known themselves, such as scorotron transfer chargers and corotron transfer chargers that utilize corona discharge.

[0170] -Intermediate transfer body- As the intermediate transfer body 50, a belt-shaped body (intermediate transfer belt) containing polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductive properties is used. Further, as the form of the intermediate transfer body, a drum-shaped body may be used in addition to the belt-shaped body.

[0171] FIG. 5 is a schematic configuration diagram showing another example of the image forming apparatus of the present disclosure. The image forming apparatus 120 shown in FIG. 5 is a tandem-type full-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 body 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.

Example

[0172] 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 any way. In the following description, unless otherwise specified, "parts" and "%" are based on mass. In the following description, synthesis, processing, manufacturing, etc. were carried out at room temperature (25 ° C ± 3 ° C) unless otherwise specified.

[0173] <Manufacture of photosensitive member> [Photosensitive member (1)] -Formation of undercoat layer- 100 parts of zinc oxide particles (average particle size 70 nm, specific surface area 15 m 2 / g, Tayca Corporation) were stirred and mixed with 500 parts of tetrahydrofuran, 1.25 parts of a silane coupling agent (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, trade name: KBM603, Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 2 hours. Tetrahydrofuran was distilled off under reduced pressure, and baking was carried out at 120 ° C for 3 hours to obtain zinc oxide particles surface-treated with a silane coupling agent.

[0174] 60 parts surface-treated zinc oxide particles, 0.6 parts 4-ethoxy-1,2-dihydroxy-9,10-anthraquinone, 13.5 parts curing agent (blocked isocyanate, trade name: Sumijule 3173, Sumitomo Bayer Urethane Co., Ltd.), 5 parts butyral resin (trade name: Esrec BM-1, Sekisui Chemical Co., Ltd.), and 42 parts methyl ethyl ketone were mixed and dispersed for 4 hours using 1 mm diameter glass beads in a sand mill to obtain a dispersion. To the dispersion, 0.005 parts dioctyl tin dilaurate as a catalyst and 4 parts silicone resin particles (trade name: Tospar 145, Momentive Performance Materials) were added to obtain a coating solution for forming an undercoat.

[0175] A coating solution for forming the undercoat layer was applied to the outer surface of an aluminum cylindrical tube (conductive substrate) with an outer diameter of 30 mm and a wall thickness of 1 mm using an immersion coating method. Drying and curing was performed at 180°C for 40 minutes to form an undercoat layer with an average thickness of 25 μm.

[0176] -Formation of a charge generation layer- Fifteen parts of the charge-generating material chlorogallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.4°, 16.6°, 25.5°, and 28.3° in its X-ray diffraction spectrum using CuKα characteristic X-rays) were mixed with ten parts of vinyl chloride-vinyl acetate copolymer and 300 parts of n-butyl alcohol as binder resins. The mixture was dispersed for 4 hours using glass beads with a diameter of 1 mm in a sand mill to obtain a coating solution for forming a charge-generating layer. A coating solution for forming a charge generation layer was applied to the base layer by immersion, and dried at 120°C for 5 minutes to form a charge generation layer with an average thickness of 0.2 μm.

[0177] -Formation of a charge transport layer- Forty parts of the charge transport material N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine and 60 parts of polyarylate resin (PA1) as a binder resin were dissolved in 270 parts of tetrahydrofuran and 30 parts of toluene to obtain a coating solution for forming a charge transport layer. A charge transport layer formation solution was applied to the charge generation layer by immersion, and dried at 145°C for 30 minutes to form a charge transport layer with an average thickness of 40 μm. Polyarylate resin (PA1) is a polyarylate resin consisting of the following dicarboxylic acid units (A2-3) and diol units (B1-2).

[0178] [ka]

[0179] [Photoconductor (2)] -Formation of a charge transport layer- The undercoat layer and charge generation layer were formed in the same manner as in photoreceptor (1). Solution (1) was obtained by dissolving 40 parts of the charge transport material N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine and 60 parts of polycarbonate resin (PC1) as a binder resin in 270 parts of tetrahydrofuran and 30 parts of toluene. Separately, a mixture (2) was prepared by mixing 0.02 parts of a fluorine-based comb-type graft polymer (product name: GF-300, Toagosei Co., Ltd.), 5 parts of polytetrafluoroethylene particles (product name: Lebron L2, Daikin Industries, Ltd.), and 20 parts of tetrahydrofuran. Solution (1) and mixture (2) were mixed and dispersed using a collision-type high-pressure disperser to obtain a coating solution for the charge transport layer. A charge transport layer coating solution was applied to the charge generation layer by immersion, and dried at 135°C for 40 minutes to form a charge transport layer with an average thickness of 40 μm. The constituent units of polycarbonate resin (PC1) are shown below.

[0180] [ka]

[0181] <Manufacturing of electrostatic rolls> [Charged Roll (1)] -Formation of the elastic layer- • Epichlorohydrin rubber (Gechron3106, Zeon Corporation): 100 units • Carbon black (Asahi #60, Asahi Carbon Co., Ltd.): 6 parts • Calcium carbonate (Whiteon SB, Shiraishi Calcium Co., Ltd.): 20 units • Ionic conductive agent (BTEAC, Lion Specialty Chemicals Co., Ltd.): 5 parts • Vulcanization accelerator: Stearic acid (NOF Co., Ltd.): 1 part • Vulcanizing agent: Sulfur (Parnock®, Ouchi Shinko Chemical Industry Co., Ltd.): 1 part • Vulcanization accelerator: Zinc oxide: 1.5 parts The above materials were mixed and kneaded in an open roll. The mixture was press-molded onto the outer surface of an 8mm diameter SUS303 shaft (support member) via an adhesive layer to form an elastic layer. The diameter up to the elastic layer was 15mm. The outer surface of the elastic layer was polished to obtain a 14mm diameter conductive elastic roll.

[0182] -Formation of the surface layer- • N-methoxymethylated nylon (F30K, Nagase ChemteX Corporation): 85 parts • Polyvinyl butyral (Eslec BL-1, Sekisui Chemical Co., Ltd.): 15 units • Carbon black (MONARCH1000, Cabot Japan Co., Ltd.): 15 units • Polyamide particles (Polyamide 12, Arkema Corporation): 10 units • Polyether-modified dimethylpolysiloxane (BYK-307, Altana): 0.05 parts The above materials were mixed, diluted with methanol / 1-propanol, and dispersed in a bead mill to obtain a coating solution for surface layer formation. The coating solution was applied by immersion to the outer surface of a conductive elastic roll in an environment of 22°C and 50% relative humidity, and dried at 130°C for 30 minutes to form a surface layer with an average thickness of 10 μm.

[0183] [Charging Rolls (2)~(16)] A charged roll was manufactured in the same manner as the charged roll (1), except that the mass ratio of polyvinyl butyral in the binder resin (N-methoxymethylated nylon and polyvinyl butyral), the amount of silicon compound (polyether-modified dimethylpolysiloxane, BYK-307, Altana Co., Ltd.) added, and / or the temperature and humidity when immersing and applying the surface layer forming coating solution to the outer surface of the conductive elastic roll were changed as shown in Table 2.

[0184] <Examples 1-14, Comparative Examples 1-3: Manufacturing of Image Forming Units> A photoreceptor (1) or (2) and one of the charging rolls (1) to (16) were assembled into an image forming unit in the combinations shown in Table 2.

[0185] <Performance Evaluation> [cover] An image forming unit equipped with a photoreceptor and a charging roll was installed in the black image forming section of an image forming apparatus, ApeosPrint C3560 S (Fujifilm Business Innovation Co., Ltd.), and evaluation was conducted using this image forming apparatus. An image with 0% density was printed on A4 size plain paper in an environment with a temperature of 10°C and a relative humidity of 15% (i.e., a blank page was printed). The density of one central point on both the blank and printed paper was measured using an X-Rite 404A densitometer. The density difference between the two was classified as follows. The evaluation results are shown in Table 2.

[0186] G0: Concentration difference 0.00. No fogging occurred. G1: Concentration difference of 0.01 or less. Very slight overlap occurred. G2: Concentration difference greater than 0.01 and less than 0.03. Slight overlap occurred. No practical problems. G3: Concentration difference of 0.03 or more. Clear fogging occurred. This poses a practical problem.

[0187] [Streaky density variations] The image forming unit underwent vibration and drop tests simulating product transport, followed by image formation. The vibration and drop tests were designed to cause friction between the photoreceptor and the charging roll, leading to the photoreceptor becoming charged. -Vibration Test- The photoreceptor and charging roll were assembled into process cartridges for the ApeosPrint C3560 S image forming machine (Fujifilm Business Innovation Co., Ltd.). The process cartridges were individually packaged in their shipping configuration. Each individual package (a rectangular parallelepiped) was placed on the vibration table of a vibration testing machine (Shinken Co., Ltd., G-9223LS model) with one of its largest surfaces as the base, and metal blocks were placed on all four sides of the base to prevent movement on the vibration table. A vibration test was performed on the individual package using the vibration conditions (i) to (iii) shown in Table 1, in that order.

[0188] [Table 1]

[0189] - Drop test - After conducting vibration tests, the individual packages (i.e., rectangular prisms) were dropped onto a steel plate from a height of 1 meter a total of 10 times in the order of (1) to (3) below. Here, the height is the distance from the bottom of the individual package to the top surface of the steel plate. (1) The rectangular prism was dropped a total of six times, with each face touching once, ensuring the faces were aligned horizontally. (2) Align one of the diagonals with the direction of gravity, point one of the vertices downwards, and drop it once. (3) The object was dropped a total of three times, once along each of the three edges extending from one corner, along the edges in a horizontal direction, and with the plane that bisects the rectangular prism including the diagonal aligned with the direction of gravity.

[0190] -Image Formation- After conducting vibration and drop tests on the individual packaging, the process cartridges were removed from the packaging and mounted in the black image forming section of the ApeosPrint C3560 S image forming machine (Fujifilm Business Innovation Co., Ltd.). Evaluation was then performed using this image forming machine. An image density 30% black halftone image was output in an environment with a temperature of 22°C and a relative humidity of 55%. The black halftone image was visually observed, and streak-like density unevenness was classified as follows. Table 2 shows the evaluation results.

[0191] A: No streak-like density unevenness is observed. B: Streak-like density unevenness is slightly observed, but there is no problem in practical use. C: Streak-like density unevenness is observed, and there is a problem in practical use.

[0192]

Table 2

[0193] The image forming unit, process cartridge, and image forming apparatus of the present disclosure include the following aspects.

[0194] (Supplementary Note) (((1))) A photoreceptor, and A charging member that contacts the surface of the photoreceptor and charges the photoreceptor, The photoreceptor has a conductive substrate and a laminated photosensitive layer having a charge generation layer and a charge transport layer disposed on the conductive substrate, The charge transport layer contains a polyarylate resin and does not substantially contain an organic fluorine compound, The charging member has a support member, an elastic layer disposed on the support member, and a surface layer disposed on the elastic layer, The surface layer contains a resin, conductive particles, and a silicon compound, and the silicon element concentration on the surface of the surface layer is 0.2 atm% or more and 1.2 atm% or less, An image forming unit. (((2))) The image forming unit according to (((1))), wherein the silicon element concentration on the surface of the surface layer is 0.3 atm% or more and 1.0 atm% or less. (((3))) The surface layer of the charging member contains a polyamide resin and a polyvinyl butyral resin as a binder resin, and the proportion of the polyvinyl butyral resin in the total amount of the polyamide resin and the polyvinyl butyral resin is 10% by mass or more and 30% by mass or less. The image forming unit according to ((1)) or ((2)). (((4))) The proportion of the polyvinyl butyral resin in the total amount of the polyamide resin and the polyvinyl butyral resin is 15% by mass or more and 20% by mass or less. The image forming unit according to ((3)). (((5))) The ten-point average roughness RzJIS (JIS B0601: 2013) of the outer peripheral surface of the charging member is 5.9 μm or less. The image forming unit according to any one of ((1)) to ((4)). (((6))) The image forming unit according to any one of ((1)) to ((5)), Detachable to an image forming apparatus Process cartridge (((7))) The image forming unit according to any one of ((1)) to ((5)), and 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, And a transfer device for transferring the toner image onto the surface of a recording medium. An image forming apparatus comprising Image forming apparatus

[0195] (((1))) or ((2)), compared with an image forming unit in which the silicon element concentration on the surface of the surface layer of the charging member is less than 0.2 atm%, fogging in the image is less likely to occur in a low temperature and low humidity environment, and compared with an image forming unit in which the silicon element concentration on the surface of the surface layer of the charging member is more than 1.2 atm%, an image forming unit in which streak-like density unevenness is less likely to occur in the image is provided. According to (((3))) or (((4))), compared to an image forming unit in which the proportion of polyvinyl butyral resin in the total amount of polyamide resin and polyvinyl butyral resin contained in the surface layer of the charging member is less than 10% by mass or more than 30% by mass, an image forming unit is provided in which image fogging is less likely to occur in low temperature and low humidity environments. According to (((5))), compared to an image forming unit in which the ten-point average roughness RzJIS of the outer surface of the charged member exceeds 5.9 μm, an image forming unit is provided in which image fogging is less likely to occur in low temperature and low humidity environments. According to (((6))), a process cartridge is provided that is less prone to image fringing in low-temperature, low-humidity environments compared to a process cartridge in which the silicon element concentration on the surface layer of the charged member is less than 0.2 atm%, and less prone to streaky density unevenness in images compared to a process cartridge in which the silicon element concentration on the surface layer of the charged member is greater than 1.2 atm%. According to (((7))), compared to an image forming apparatus in which the silicon element concentration on the surface of the surface layer of the charged member is less than 0.2 atm%, image fogging is less likely to occur in low temperature and low humidity environments, and compared to an image forming apparatus in which the silicon element concentration on the surface of the surface layer of the charged member is more than 1.2 atm%, an image forming apparatus is provided in which streaky density unevenness is less likely to occur in images. [Explanation of symbols]

[0196] 1 conductive substrate, 2 subbing layer, 3 charge generation layer, 4 charge transport layer, 5 photosensitive layer, 10A photoreceptor

[0197] 30 Charging member, 32 Support member, 34 Elastic layer, 36 Surface layer

[0198] 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 material (roll type), 133 Fibrous material (flat brush type), 300 Process cartridge

Claims

1. Photoreceptor and The system comprises a charging member that contacts the surface of the photoreceptor and charges the photoreceptor, The photoreceptor comprises a conductive substrate and a laminated photoreceptor having a charge generation layer and a charge transport layer disposed on the conductive substrate. The charge transport layer contains a polyarylate resin and is substantially free of organofluorine compounds. The charging member comprises a support member, an elastic layer disposed on the support member, and a surface layer disposed on the elastic layer. The surface layer contains a resin, conductive particles, and a silicon compound, and the silicon element concentration on the surface of the surface layer is 0.2 atm% or more and 1.2 atm% or less. Image forming unit.

2. The image forming unit according to claim 1, wherein the silicon element concentration on the surface of the surface layer is 0.3 atm% or more and 1.0 atm% or less.

3. The image forming unit according to claim 1, wherein the surface layer of the charging member contains a polyamide resin and a polyvinyl butyral resin as a binder resin, and the proportion of the polyvinyl butyral resin to the total amount of the polyamide resin and the polyvinyl butyral resin is 10% by mass or more and 30% by mass or less.

4. The image forming unit according to claim 3, wherein the proportion of the polyvinyl butyral resin to the total amount of the polyamide resin and the polyvinyl butyral resin is 15% by mass or more and 20% by mass or less.

5. The image forming unit according to claim 1, wherein the ten-point average roughness RzJIS (JIS B0601:2013) of the outer surface of the charging member is 5.9 μm or less.

6. The image forming unit comprises the image forming unit according to any one of claims 1 to 5, To be attached to and detached from the image forming apparatus, Process cartridge.

7. An image forming unit according to any one of claims 1 to 5, An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged photoreceptor, A developing apparatus that develops an electrostatic latent image formed on the surface of a photoreceptor using a developer containing toner to form a toner image, The system includes a transfer device for transferring the toner image onto the surface of a recording medium. Image forming apparatus.

Images