Charging member having a surface layer with waviness

Abstract

An example charging member (100) has a conductive support (101); a conductive elastic body layer (102, 202) on the conductive support, where the conductive elastic body layer is formed of a resin mixture, where the resin mixture comprises a recycled-rubber resin and a recycled filler; and a surface layer (103, 203) on the conductive elastic body layer, where the surface layer includes a binder resin (203a) and particles (203b, 203c) dispersed in the binder resin, the particles including acrylic resin particles having an average particle diameter of about 5 micrometer (µm) to about 33 µm, wherein the surface layer satisfies the condition of 3 µm ≤ waviness (Wt) ≤15 µm as determined by microscope-enhanced visual observation of the surface layer.

Description

86273579 CHARGING MEMBER HAVING A SURFACE LAYER WITH WAVINESS BACKGROUND

[0001] An electrophotographic imaging apparatus includes a photoconductor and a charging member such as a charging roller, a developing roller, or a transfer roller, which are provided around the photoconductor. The charging member charges a surface of the photoconductor to a predetermined voltage.

[0002] An electrostatic latent image corresponding to print data is formed on the charged surface of the photoconductor with light emitted from an exposure unit. The developing roller supplies a developer to the photoconductor to develop the electrostatic latent image into a developer image. The developer image is transferred by the transfer roller onto an image receiving member passing between the photoconductor and the transfer roller. BRIEF DESCRIPTION OF DRAWINGS

[0003] Various examples will be described below with reference to the following figures.

[0004] FIG. 1 is a cross-sectional view schematically illustrating an example of a charging member according to an example.

[0005] FIG. 2 is a cross-sectional view schematically illustrating an enlarged surface layer of an example of a charging member according to an example.

[0006] FIG. 3 is a cross-sectional view schematically illustrating an electrophotographic imaging apparatus and an electrophotographic cartridge including an example of a charging member according to an example. DETAILED DESCRIPTION

[0007] When an electrostatic latent image is formed, a contact charging method may be used in which a charging member contacts a photoconductor to charge a surface of the photoconductor as an image carrier. In an example, an electroconductive roller may be used as the charging member. In this example method, a surface of the photoconductor is charged by applying a voltage to a conductive support (e.g., a shaft) using the charging member to perform a micro discharge in the vicinity of a contact nip between the charging member and the photoconductor. The charging86273579 member may have a structure in which a conductive elastic body layer is formed on the conductive support (e.g., a shaft) and a surface layer or resistance layer is formed on the conductive elastic body layer. In some examples, a charging member includes a conductive support, a conductive elastic body layer on the conductive support, where the conductive elastic body layer is formed of a resin mixture, where the resin mixture comprises a recycled-rubber resin and a recycled filler, and a surface layer on the conductive elastic body layer, where the surface layer includes a binder resin and particles dispersed in the binder resin, the particles including acrylic resin particles having an average particle diameter of about 5 micrometer (μm) to about 33 μm, where the surface layer satisfies the condition of 3 μm ≤ waviness (Wt) ≤ 15 μm as determined by microscope-enhanced visual observation of the surface layer, as detailed herein. The following numbered examples are also discussed herein: 2 - the charging member where an amount of the recycled-rubber resin in the resin mixture is in a range of about 5 parts by weight to about 40 parts by weight, based on 100 parts by weight of the resin mixture; 3 - the charging member where an amount of the recycled filler in the resin mixture is in a range of about 5 parts by weight to about 15 parts by weight, based on 100 parts by weight of the resin mixture; 4 - the charging member where a ratio of the recycled-rubber resin to the recycled filler is in a range from about 6 parts by weight to about 0.5 parts by weight; 5 - the charging member where the resin mixture further comprises virgin rubber resin, where an amount of the virgin rubber resin in the resin mixture is in a range of about 45 parts by weight to about 90 parts by weight, based on 100 parts by weight of the resin mixture; 6 - the charging member of 5, where the recycled rubber resin and the virgin rubber resin comprise acrylonitrile-butadiene rubber (NBR), Styrene Butadiene Rubber (SBR), epichlorohydrin rubber, or a combination thereof; 7 - the charging member of 6, where: the recycled rubber resin comprises SBR; and the virgin rubber resin comprises epichlorohydrin rubber; 8 - the charging member, where the charging member is formed as a charging roller; 9 - the charging member where the recycled filler comprises recycled carbon black; 10 - an electrophotographic cartridge for an electrophotographic imaging apparatus, the electrophotographic cartridge comprising: an electrophotographic photoconductor drum; a charging member contacting the electrophotographic photoconductor drum to charge the electrophotographic photoconductor drum; a developing unit to develop an electrostatic latent image to a visible image; and a cleaning unit to clean a surface of the electrophotographic photoconductor86273579 drum, where the charging member comprises: a conductive support; a conductive elastic body layer on the conductive support, where the conductive elastic body layer is formed of a resin mixture that includes: a recycled-rubber resin, where an amount of the recycled-rubber resin in the resin mixture is in a range of about 5 parts by weight to about 40 parts by weight, based on 100 parts by weight of the resin mixture; and a recycled filler, where an amount of the recycled filler in the resin mixture is in a range of about 5 parts by weight to about 15 parts by weight, based on 100 parts by weight of the resin mixture; and a surface layer on the conductive elastic body layer, where the surface layer includes a binder resin and particles dispersed in the binder resin, the particles including acrylic resin particles having an average particle diameter of about 5 micrometer (μm) to about 33 μm, and where the surface layer satisfies the condition of 3 μm ≤ waviness (Wt) ≤ 15 μm as determined by microscope-enhanced visual observation of the surface layer; 11 - the cartridge of 10, where the acrylic resin particles further comprises first particles and second particle, and where: the first particles have an average particle diameter of about 8 μm to about 27 μm; and the second particles have an average particle diameter that is less than the first particles; 12 - the cartridge of 11, where: an amount of the first particles in the binder resin is in a range of about 8 parts by weight to about 12 parts by weight, based on 100 parts by weight of the binder resin; and an amount of the second particles in the binder resin is in a range of about 5 parts by weight to about 10 parts by weight, based on 100 parts by weight of the binder resin; 13 - the cartridge of 10, where the acrylic resin particles are polymethyl methacrylate (PMMA) particles, polymethyl acrylate (PMAA) particles, or a combination thereof; 14 - an electrophotographic imaging apparatus comprising: an electrophotographic photoconductor drum; a charging member contacting the electrophotographic photoconductor drum to charge the electrophotographic photoconductor drum;86273579 an exposure unit to form an electrostatic latent image on a surface of the electrophotographic photoconductor drum; a developing unit to develop the electrostatic latent image to a visible image; a transfer unit to transfer the visible image onto an image receiving member; and a cleaning unit to clean a surface of the electrophotographic photoconductor drum, where the charging member comprises: a conductive support; a conductive elastic body layer on the conductive support, where the conductive elastic body layer is formed of a resin mixture that includes: a recycled-rubber resin, where an amount of the recycled-rubber resin in the resin mixture is in a range of about 5 parts by weight to about 40 parts by weight, based on 100 parts by weight of the resin mixture; a virgin resin, where an amount of the virgin resin in the resin mixture is in a range of about 45 parts by weight to about 90 parts by weight, based on 100 parts by weight of the resin mixture; and a recycled filler, where an amount of the recycled filler in the resin mixture is in a range of about 5 parts by weight to about 15 parts by weight, based on 100 parts by weight of the resin mixture; and a surface layer on the conductive elastic body layer, where the surface layer includes a binder resin and particles dispersed in the binder resin, the particles including acrylic resin particles having an average particle diameter of about 5 micrometer (μm) to about 33 μm, where the surface layer satisfies the condition of 3 μm ≤ waviness (Wt) ≤ 15 μm when the surface layer has a roughness in a range from about 5 μm to about 30 μm, and where the Wt and roughness are determined by microscope-enhanced visual observation of the surface layer; and 15 - the electrophotographic imaging apparatus of 14, where the electrophotographic imaging apparatus exhibits: a background noise performance of less than 0.8; an absence of micro-jitter; and an absence of image stains. The following includes further details on the above examples of the present disclosure.

[0008] Charging members may contain recycled materials such as recycled rubber (e.g., acrylonitrile-butadiene rubber [NBR], Styrene Butadiene Rubber [SBR], etc.)86273579 and / or recycled filler (e.g., recycled carbon black, etc.). However, the addition of the recycled materials can negatively impact charging / print properties relative to the exclusive use of virgin rubber. For instance, the presence of the recycled materials may increase a waviness of a surface layer and therefore may degrade charging / printing properties relative to charging members that exclusively employ virgin materials.

[0009] Particles such as beads can be added to a surface layer of a charging member in an electrophotographic imaging apparatus to increase an operational lifetime and / or improve charging / printing properties (e.g., 2D noise, micro-jitter, etc.) of the charging member. However, providing the appropriate particles (e.g., in terms of size and / or relative amounts) to ensure satisfactory charging / print properties may be particularly challenging when recycled materials are present as the recycled materials may adversely impact charging / printing properties relative to charging members that exclusively employ virgin materials.

[0010] As such, the present disclosure is directed to a charging member that employs recycled rubber / recycled carbon in a conductive elastic body layer. The relative amounts of the recycled rubber / recycled carbon and the use of the particular particles (e.g., particular materials, sizes, etc.) herein provide a surface layer of the charging member with a waviness that satisfies the condition of 3 micrometers (um) ≤ waviness (Wt) ≤ 15 um. As a result, the charging members herein exhibit good charging / printing properties and exhibit a long operational lifetime.

[0011] Hereinafter, an example charging member, an electrophotographic imaging apparatus, and an electrophotographic cartridge including the charging member will be described. Notably, the charging member herein can satisfy both micro-jitter and 2D noise, and yet is durable to provide a long operational lifetime and is electrically suitable for an electrophotographic imaging apparatus. A description will be made based on a charging member, where the charging member is formed as a charging roller as an example. Where appropriate, the term charging member can be replaced with charging roller and vice versa. However, the following description may be equally applied to a charging member having a shape other than a roller, such as a corona charger or a charging brush.

[0012] A charging member according to an example includes a conductive support, a conductive elastic body layer on the conductive support, and a surface layer on the conductive elastic body layer as an outermost layer.

[0013] FIG. 1 is a schematic cross-sectional view of an example of a charging86273579 member according to an example. Referring to FIG.1, in a charging member 100, a conductive elastic body layer 102 and a surface layer 103 are provided on an outer circumference surface of a conductive support 101 having a shaft shape. The conductive elastic body layer 102 and the surface layer 103 may be provided in this order from an inner side in the diameter direction of the charging member 100 toward the outer side in the diameter direction of the charging member 100. In an example, the conductive elastic body layer 102 and the surface layer 103 may be integrally laminated on the outer circumference surface of the conductive support 101. An intermediate layer (not shown) such as a resistance adjustment layer for increasing voltage resistance (i.e., leak resistance) may be formed between the conductive elastic body layer 102 and the surface layer 103.

[0014] In an example imaging apparatus, the charging member 100 shown in FIG. 1 is provided as a charging means for charging a body to be charged, and may function as a charging means for charging the surface of the photoconductor as an image carrier.

[0015] Conductive support

[0016] In an example, the conductive support 101 includes a metal having electrical conductivity. For example, a metallic hollow body (a pipe shape) or a metallic solid body (a rod shape) including iron, copper, aluminum, nickel, or stainless steel may be used. An outer circumference surface of the conductive support 101 may be plated for reducing or preventing rust or to provide scratch resistance. The outer circumference surface of the conductive support 101 may be plated to a degree that does not impair electrical conductivity. Further, the outer circumference surface of the conductive support 101 may be coated with an adhesive, a primer, or the like to increase adhesion to the conductive elastic body layer 102. In this case, to provide electrical conductivity, this adhesive, primer, etc. in itself may be made electrically conductive.

[0017] The conductive support 101 may have a cylindrical shape having a diameter of about 4 millimeters (mm) to about 20 mm, for example, about 5 mm to about 10 mm and having a length of about 200 mm to about 400 mm, for example, about 250 mm to about 360 mm.

[0018] Conductive Elastic body layer

[0019] In an example, the conductive elastic body layer 102 may have elasticity suitable for securing uniform adhesion to the photoconductor. For example, the conductive elastic body layer 102 may be formed using a binder resin selected from86273579 7 natural rubbers, synthetic rubbers such as ethylene-propylene-diene monomer rubber (EPDM), styrene-butadiene rubber (SBR), a silicone rubber, a polyurethane-based elastomer, epichlorohydrin (ECO) rubber, isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (H-NBR) and chloroprene rubber (CR), synthetic resins such as an amide resin, a urethane resin, and a silicone resin, and a recycled-rubber resin and a recycled filler. These may be used alone or in combination of two or more. Examples of recycled-rubber resins include, but are not limited to, recycled (e.g., non-virgin) EPDM, recycled SBR, recycled silicone rubber, recycled polyurethane-based elastomer, recycled ECO rubber, recycled isoprene rubber IR, recycled BR, recycled NBR, recycled H-NBR and recycled CR, among others. Examples of recycled fillers include, but are not limited to, recycled carbon black, recycled carbon nanotubes, recycled graphene, recycled metal fibers and / or powders (e.g., copper, nickel, etc.).

[0020] In an example, the conductive elastic body layer 102 is formed from a resin mixture, where the resin mixture comprises a recycled-rubber resin and a recycled filler. For example, an amount of the recycled-rubber resin in the resin mixture is in a range of about 5 parts by weight to about 40 parts by weight, based on 100 parts by weight of the resin mixture. In an additional example, an amount of the recycled filler in the resin mixture is in a range of about 5 parts by weight to about 15 parts by weight, based on 100 parts by weight of the resin mixture. Regarding the relative amounts of the recycled-rubber resin to the recycled filler, in an example a ratio of the recycled-rubber resin to the recycled filler is in a range from about 6 parts by weight to about 0.5 parts by weight.

[0021] In an example, the resin mixture as provided herein can further comprise virgin rubber resin. In an example, an amount of the virgin rubber resin in the resin mixture is in a range of about 45 parts by weight to about 90 parts by weight, based on 100 parts by weight of the resin mixture. In an example, the recycled-rubber resin and the virgin rubber resin comprise acrylonitrile-butadiene rubber (NBR), Styrene Butadiene Rubber (SBR), epichlorohydrin rubber, or a combination thereof. In another example, the recycled-rubber resin comprises SBR and the virgin rubber resin comprises epichlorohydrin rubber.

[0022] Identifying recycled rubber from, for example, virgin rubber that might also be present in a charging member can include identifiable color and texture differences and / or density differences. For example, recycled rubber often has a86273579 different color and texture compared to virgin rubber, where the recycled rubber can have small imperfections, such as tiny dark specks, whereas virgin rubber tends to have a more consistent, uniform appearance. To make such an assessment a variety of optical and / or electron microscopes may be employed. For example, any one of a brightfield microscope, darkfield microscope and / or polarizing microscope might be used to assess and identify recycled rubber from, for example, virgin rubber based on the above identified differences. A scanning electron microscope can also be used to provide a high-resolution, three-dimensional image of the rubber particle’s surface, which can assist in differentiating recycled rubber from, for example, virgin rubber based on the above identified differences. In addition, recycled rubber products are sometimes less dense than virgin rubber, which can be used in distinguishing the two types of rubber. Density measurements for making this distinction can be made by standard methods of measuring mass and volume of the rubber particles and / or by using ASTM D297-93, which includes methods for determining the specific gravity of rubber from which a density can be determined using the density of the reference substance.

[0023] The charging member 100 may be in contact with a photoconductor (e.g., electrophotographic photoconductor drum 311 of FIG.3) when used in a contact developing method, and may be spaced apart from the photoconductor when used in a non-contact developing method.

[0024] In the case of a contact developing method, the conductive elastic body layer 102 may be adjusted to have a hardness of about 25 to about 45 as measured by an Asker-A TYPE durometer, and in the case of a non-contact developing method, the conductive elastic body layer 102 may be adjusted to have a hardness of about 40 to about 65 as measured by an Asker-A TYPE®durometer. In other examples, the hardness may be determined according to a printer speed, lifetime, cost, etc., and the hardness may vary depending on the developing method.

[0025] The conductive elastic body layer 102 may have a thickness of about 0.5 mm to about 8.0 mm, for example, about 1.25 mm to about 3.00 mm. Within the thickness range, the charging member 100 exhibits elasticity and recovery against deformation, and a stress imparted on toner may be reduced. In the case of the one- component non-contact developing method, the thickness of the conductive elastic body layer 102 may be about 0.5 mm to about 2.0 mm, and in the case of the one-component contact developing method, the thickness of the conductive elastic body layer 102 may be about 1.5 mm to about 8.0 mm.86273579

[0026] The conductive elastic body layer 102 may include a conductive agent. The conductive agent may include an ion-conducting agent and an electron-conducting agent. The conductive elastic body layer 102 may include an ion-conducting agent in consideration of resistance stability. Since the ion-conducting agent may be uniformly dispersed in a polymer elastic body to make the electrical resistance of the conductive elastic body layer 102 uniform, uniform charging may be obtained even when the charging member 100 is charged using a DC voltage.

[0027] The ion-conducting agent may be selected depending on the purpose for the conductive elastic body 102, which can include which ions are to be transported, the ion conductivity for the conductive elastic body layer 102 and the chemical stability of the ion-conducting agent, among other considerations. Examples of the ion-conducting agent may include alkali metal salts, alkaline earth metal salts, perchlorates of quaternary ammonium, chlorates, hydrochlorides, bromates, iodates, hydroborates, sulfates, trifluoromethyl sulfates, sulfonates, and trifluoromethane sulfonates. These may be used alone or in combination of two or more. The alkali metal salts may be selected depending on the purpose for the conductive elastic body 102 as discussed above. Examples thereof may include lithium salts, sodium salts, and potassium salts. These may be used alone or in combination of two or more. Examples of the lithium salts may include Li[B(C14H10O3)2], Li(CF3SO2)2N, Li(C2F5SO2)2N, LiClO4, LiBF4, LiPF6, LiCF3SO3, LiAsF6, and LiC4F9SO3.

[0028] Examples of the quaternary ammonium salts may include cationic surfactants such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, didecyldimethylammonium chloride, hexadecyltrimethylammonium chloride, trioctylpropylammonium bromide, tetrabutylammonium chloride, and behenyltrimethylammonium chloride, amphoteric surfactants such as lauryl betaine, stearyl betatine, dimethyl lauryl betaine, and tetraethyl ammonium perchlorate, tetrabutyl ammonium perchlorate, and trimethyl octadecyl ammonium perchlorate, or the like.

[0029] The amount of the ion-conducting agent used may be in a range of about 0.01 parts by weight to about 10 parts by weight, or in a range of about 0.5 parts by weight to about 5 parts by weight, based on 100 parts by weight of the binder resin. These ion-conducting agents may be used alone or in combination of two or more.

[0030] The electron-conducting agent may be used in combination with the ion-conducting agent. As the electron-conducting agent, for example, carbon black, as86273579 discussed herein, may be used. Examples of the carbon black may include conductive carbon black such as oxidized carbon black for use in ink to improve dispersibility, ketjen black, and acetylene black, carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT grades, and pyrolytic carbon black, natural graphite, and artificial graphite. As the electron-conducting agent, for example, metal oxides such as antimony- doped tin oxide, indium tin oxide (ITO), tin oxide, titanium oxide, zinc oxide, metals such as nickel, copper, silver, and germanium, electrically conductive polymers such as polyaniline, polypyrrole, and polyacetylene, and conductive whiskers such as carbon whisker, graphite whisker, titanium carbide whisker, conductive potassium titanate whisker, conductive barium titanate whisker, conductive titanium oxide whisker, and conductive zinc oxide whisker may be used. To reduce a difference in electrical resistance and to reduce a hardness, a small amount of the electron-conducting agent may be used. The amount of the electron-conducting agent used may be in a range of about 50 parts by weight or less, for example, in a range of about 15 parts by weight or less, based on 100 parts by weight of the binder resin.

[0031] The resistance value of the conductive elastic body layer 102 by the combination of the conducting agent may be adjusted to about 103Ω to about 1011Ω, and may be adjusted to about 104Ω to about 109Ω. When the resistance value of the conductive elastic body layer 102 is less than 103Ω, the charges on the photoconductor may leak and thus an imbalance in electrical resistance may occur resulting in spots on an image. Additionally, when the resistance value of the conductive elastic body layer 102 is less than 103Ω, hardness may increase to make uniform contact with the photoconductor difficult, and image stains may occur. When the resistance value of the conductive elastic body layer 102 is more than 1011Ω, background (B / G) image defects may occur.

[0032] The conductive elastic body layer 102 may contain additives such as a filler other than the recycled filler discussed herein, a foaming agent, a crosslinking agent, a crosslinking accelerator, a lubricant, and / or an auxiliary agent. The crosslinking agent may include sulfur. The crosslinking accelerator may include tetramethylthiuram disulfide (CZ). The lubricant may include stearic acid. The auxiliary agent may include zinc oxide (ZnO).

[0033] Surface layer

[0034] The surface layer 103 may include a binder resin and particles, as described herein, dispersed in the binder resin. The surface layer 103 can additionally86273579 include an ion-conducting agent and / or an electron-conducting agent, such as those described herein. For example, the surface layer 103 can include an electron conducting agent in the form of electroconductive particles including carbon black such as KETJEN BLACK®EC and acetylene black; carbon black for rubber such as Super Abrasion Furnace (SAF), Intermediate Super Abrasion Furnace (ISAF), High Abrasion Furnace (HAF), Extra Conductive Furnace (XCF), Fast Extruding Furnace (FEF), General Purpose Furnace (GPF), Semi Reinforcing Furnace (SRF), Fine Thermal (FT) and Medium Thermal (MT); oxidation-treated carbon black for color ink; metal particles of copper, silver, or germanium, and / or metal oxide particles. For instance, carbon black may be employed to control a conductivity of the surface layer 103. For example, an amount of the electroconductive particles may be in the range of about 1 part to about 50 parts by weight based on 100 parts by weight of the binder resin.

[0035] The surface layer 103 can include an ion-conducting agent in the form of an ion conductive material in the binder resin. Examples of the ion conductive material include an inorganic ion conductive material such as sodium perchlorate, lithium perchlorat, calcium perchlorate, or lithium chloride; an organic ion conductive material such as modified aliphatic dimethylaluminum isosulfate or stearylammonium acetate; or a mixture thereof. An amount of the ion conductive material may be in a range of about 1 part to about 50 parts by weight based on 100 parts by weight of the resin.

[0036] FIG. 2 is a schematic cross-sectional view illustrating an enlarged surface layer of a charging member according to an example.

[0037] Referring to FIG.2, the surface layer 203 may contain a urethane resin as a binder resin 203a, which forms a matrix material, and may contain particles 203b, 203c dispersed in the binder resin. As discussed herein, the particles can have an average particle diameter of about 5 μm to about 33 μm, for example, or having an average particle diameter of about 8 μm to about 27 μm, where the particles 203b and 203c have different average particle diameters. As used herein, the average particle diameter refers to refers to the diameter of a spherical particle, or the average diameter of a non-spherical particle (e.g., the average of multiple diameters across the non- spherical particle).

[0038] Urethane resin is a polymer having a urethane bond. For example, urethane resin may include an isocyanate moiety including an isocyanate group and a polyol moiety including a hydroxyl group. Examples of the isocyanate moiety may include trilene diisocyanate (TDI), 4,4′-methylene diphenyl diisocyanate (MDI), polymeric MDI,86273579 modified MDI, naphthalene 1,5-diisocyanate, trizine diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, p-phenylene diisocyanate, trans-cyclohexane- 1,4-diisocyanate, xylene diisocyanate (XDI), hydrogenated XDI, hydrogenated MDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanate phenyl)thiophosphate, tetramethyl xylene diisocyanate, lysine ester triisocyanate, 1,6,11- undecane triisocyanate, 1,8-diisocyanate-4-isocyanatemethyl octane, 1,3,6- hexamethylene triisocyanate, bicyclo heptane triisocyanate, trimethylhexamethylene diisocyanate, block-type isocyanate (having a structure in which isocyanate is masked with a blocking agent), or a combination thereof. The block-type isocyanate does not react at room temperature, but when heated to a temperature at which the blocking agent dissociates, an isocyanate group may be re-produced in the block-type isocyanate. These may be used as a single material or as a combination of at least two selected therefrom. Examples of the polyol moiety may include polyoxypropylene glycol, polytetramethylene ether glycol, THF-alkylene oxide copolymer polyol, polyester polyol, acrylic polyol, polyolefin polyol, a partially hydrolysate product of a ethylene-vinyl acetate copolymer, phosphate-based polyol, halogen-containing polyol, adipate-based polyol, polycarbonate polyol, polycaprolactone-based polyol, polybutadiene polyol, or a combination of at least two selected therefrom.

[0039] The urethane resin material may further include a catalyst. Examples of the catalyst may include triethylamine, N,N,N′,N′-tetramethyl-ethylenediamine, N,N,N′,N″,N″-pentamethyldiethylenetriamine, triethylenediamine, dimethylaminoethanol, bis(2-methylaminoethyl)ether, or a combination of at least two selected therefrom. An amount of the catalyst may be, for example, in a range of about 0.05 parts to about 5 parts by weight based on 100 parts by weight of the total of polyol components and isocyanate components. The urethane resin material may further include an additional resin and a functional additive.

[0040] Examples of the additional resin may include styrene resin, acryl resin, vinyl chloride resin, styrene-vinyl acetate copolymer, modified maleic acid resin, phenol resin, epoxy resin, polyester resin, fluorine resin, low-molecular weight polyethylene, low- molecular weight polypropylene, ionomer resin, polyurethane resin, nylon resin, silicon resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, or a combination of at least two selected therefrom. Particularly, urethane resin, nylon resin, acryl resin, or fluorine resin may be used as they have excellent abrasion resistance, toner charging property, and toner transporting property. The functional86273579 additive may be, for example, a conductive agent such as carbon black or metal oxide; a stabilizing agent; or a combination thereof.

[0041] The binder resin 203a may be selected to avoid contamination of the photoconductor, which is a body to be charged. Examples of the binder resin may include a fluorine resin, a polyamide resin, an acrylic resin, a nylon resin, a urethane resin, a silicone resin, a butyral resin, styrene-ethylene / butylene-olefin copolymer (SEBC), and olefin-ethylene / butylene-olefin copolymer (OEBC). These may be used alone or in combination of two or more. In an example, the binder resin may be selected from a fluorine resin, an acrylic resin, a nylon resin, a urethane resin, and a silicone resin. The binder resin may be selected from a nylon resin and a urethane resin. The binder resin may contain a urethane resin.

[0042] When the binder resin contains urethane resin, the urethane resin may be formed by a chain extension reaction of a polyol mixture of polyester polyol and polyether polyol with a polyisocyanate.

[0043] The urethane resin formed by the chain extension reaction of a polyester polyol with a polyisocyanate has excellent wear resistance at relatively low hardness. However, since the urethane resin obtained by using a polyester polyol may deteriorate at low temperature, when the urethane resin is used for a long period of time under low-temperature environments, electrical resistance may vary, and a background (B / G) image may occur. Further, since an ester-based urethane may be vulnerable to hydrolysis, when the ester-based urethane is used under high-temperature and high- humidity environments, its properties may change.

[0044] The urethane resin formed by the chain extension reaction of a polyether polyol with a polyisocyanate has low-temperature flexibility, has relatively low electrical resistance, and thus has stability. However, a polyester polyol and a polyether polyol have poor compatibility and may thus cause separation or curing difficulties. When a polyether polyol having an ethylene oxide (EO) content of about 60 wt.% to about 90 wt.% is used, compatibility with a polyester polyol may be addressed. The polyether polyol having an ethylene oxide (EO) content of about 60 wt.% to about 90 wt.% may have good compatibility with a polyester polyol. In addition, the surface layer 203 produced using this urethane resin may have low-temperature flexibility, relatively low electrical resistance, physical stability, and resistance stability at low hardness.

[0045] The surface layer 203 may include a urethane resin formed by a chain extension reaction of a polyol mixture of a polyester polyol and a polyether polyol having86273579 an ethylene oxide (EO) content of about 60 wt.% to about 90 wt.% with a polyisocyanate. The content ratio of a polyester polyol and a polyether polyol may be adjusted in a range of 8:2 to 2:8. When the content ratio of any one of the polyester polyol and polyether polyol is too low, improvement effects may be reduced.

[0046] As the polyester polyol, a polycaprolactam-based polyol, an adipic acid-based polyol, or the like may be used. The polyester polyol may be obtained by an esterification reaction between a compound having two or more hydroxyl groups and a polybasic acid, or may be obtained by a ring-opening addition reaction of cyclic esters such as ε-caprolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, and δ- valerolactone using a compound having two or more hydroxyl groups as an initiator. Although polylactone-based polyols may be distinguished from polyester polyols, here, they are considered as a kind of the polyester polyols.

[0047] Examples of the aforementioned compound having two or more hydroxyl groups may include glycol compounds such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4- cyclohexanedimethanol, glycol compounds having a branched structure such as 2- methyl-1,5-pentane diol, 3-methyl-1,5-pentane diol, 1,2-butanediol, 1,3-butanediol, 2- butyl-2-ethyl-1,3-propanediol, 1,2-propane diol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentane diol, 2,4-di ethyl-1,5-pentane diol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 3,5-pentanediol, and 2-methyl-1,8- octane diol, and trimethylol propane, trimethylol ethane, pentaerythritol, and sorbitol. These compounds may be used alone or in combination of two or more.

[0048] Among ester-based polyols, an ester-based polyol having a liquid phase at room temperature may be easy to handle, may be difficult to aggregate in a coating composition, and may not generate spots on an image. Further, ester-based polyols having three or more hydroxyl groups may have a small amount of permanent deformation and good stability.

[0049] Examples of the aforementioned polybasic acid may include adipic acid, succinic acid, azeraic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and anhydrides thereof. These polybasic acids may be used alone or in combination of two or more.

[0050] As the polyether polyol having an ethylene oxide (EO) content of about86273579 60 wt.% to about 90 wt.%, a bifunctional glycol or a trifunctional or more polyether polyol such as an ethylene oxide-polypropylene oxide copolymer may be used. In an example, the ethylene oxide-polypropylene oxide copolymer may be a random copolymer because hardness of the urethane resin may become low due to low crystallinity. The polyether polyol having an ethylene oxide (EO) content of about 60 wt.% to about 90 wt.% may be a polyether polyol produced by a random addition and / or block addition of alkylene oxides of 2 to 6 carbon atoms to the aforementioned compound having two or more hydroxyl groups. Examples of the polyether polyol may include polyoxyethylene polyoxypropylene polyol and polyoxyethylene polyoxytetramethylene polyol. For example, a trifunctional or more polyoxyethylene polyoxypropylene polyol having an ethylene oxide residue at its molecular end obtained by random addition polymerization of ethylene oxide and propylene oxide may be used. A trifunctional or more polyoxyethylene polyoxypropylene polyol may be employed to suppress image defect occurrence in low-temperature and low-humidity environments, as compared with a difunctional or less polyoxyethylene polyoxypropylene polyol.

[0051] As the polyisocyanate which undergoes chain-extension with the polyol mixture including a polyester polyol and a polyether polyol having an ethylene oxide (EO) content of about 60 wt.% to about 90 wt.%, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated toluene diisocyanate, or hexamethylene Diisocyanate (HDI) may be used. In addition, blocked polyisocyanates can be obtained by reacting, for example, HDI and a blocking agent, where a blocked polyisocyanate can be a polyisocyanurate compound, such as a trimer, having at least one free isocyanate group. Blocked polyisocyanates obtained by reacting HDI and a blocking agent has storage stability because reactive isocyanate group is blocked to inhibit a reaction at room temperature. As the blocking agent, for example, methyl ethyl ketone oxime having good storage stability and productivity and capable of adjusting dissociation temperature in a range of about 120°C to about 160°C may be used. When the blocking agent is dissociated by heating, an isocyanate group is regenerated, and thus the blocked polyisocyanate may react with a polyol.

[0052] The amount of polyisocyanate added may be adjusted such that the molar ratio ([NCO] / [OH]) of isocyanate (NCO) groups of polyisocyanate to total hydroxyl (OH) groups of the polyol mixture is in a range of about 12 to about 25. Polyether polyols are likely to have a lower reactivity than that of polyester polyols, and unreacted products86273579 may be left when the molar ratio is less than 12, and low-temperature flexibility may deteriorate when the molar ratio is more than 25.

[0053] When a urethane resin is used as the binder resin of the surface layer 203, the surface layer 203 may contain a small amount of other resin components for the purpose of modifying the surface layer 203. As the other resin components, a silicone graft polymer, silicone oil, an acrylic resin, or a fluorine resin may be used for improving the stain resistance of the surface.

[0054] The surface layer 203 may include other additives such as a conducting agent, a leveling agent, a filler, an antifoaming agent, a surface modifier, a dispersant, and a charge control agent. For instance, as the conducting agent, an ion- conducting agent and / or an electron-conducting agent may be used.

[0055] As the ion-conducting agent that may be used for the surface layer, there are alkali metal salts, alkaline earth metal salts, and quaternary ammonium salts, which may be used for the aforementioned conductive elastic body layer 202. For example, ionic liquid (3M™ Ionic Liquid Antistat FC-5000) represented by the chemical structure of (n-Bu)3MeN+-N(SO2CF3) may be used as the ion-conducting agent because it has thermal stability and may thus be easily dispersed in the urethane resin. The amount of the ion-conducting agent combined may be in a range of about 0.01 parts by weight to about 10 parts by weight or in a range of about 0.5 parts by weight to about 5 parts by weight, based on 100 parts by weight of the urethane resin. As the electron- conducting agent that may be used for the surface layer 203, the aforementioned electron-conducting agent that may be used for the conductive elastic body layer 202 may be used. For example, oxidized carbon black having good dispersibility in the surface layer 203 may be used. Because the electron-conducting agent may have a small variation in electrical resistance, the amount of the electron-conducting agent combined may be in a range of about 0.5 parts by weight to about 10 parts by weight, based on 100 parts by weight of the urethane resin.

[0056] To change the photoconductor stably, the surface layer 203 may contain particles (203b, 203c) forming unevenness on the surface thereof (i.e., particles for forming roughness and / or waviness). The particles may include resin particles or inorganic particles. Examples of the resin particles may include acrylic resin particles. In some examples, the particles 203b, 203c can be acrylic resin particles. Examples of acrylic resin particles include polymethyl methacrylate (PMMA) particles, polymethyl acrylate (PMAA) particles or a combination thereof.86273579

[0057] The acrylic particles can have an average particle diameter of about 5 μm to about 33 μm, for example, having an average particle diameter of about 8 μm to about 27 μm. As used herein, the average particle diameter refers to the diameter of a spherical particle, or the average diameter of a non-spherical particle (e.g., the average of multiple diameters across the non-spherical particle). The average particle diameter of particles may be measured by a particle diameter distribution measuring device (manufacturer: Beckman Coulter®, trade name: Multisizer 3).

[0058] The content of the particles can be in a range of about 1 parts by weight to about 50 parts by weight, for example, about 5 parts by weight to about 20 parts by weight, about 5 parts by weight to about 15 parts by weight, or about 10 parts by weight to about 15 parts by weight, based on 100 parts by weight of the binder resin. Stated differently, the content of the particles in the surface layer is in a range of about 1 to about 50 parts per hundred (phr), for example, about 5 to about 20 phr, about 5 to about 15 phr, or about 10 to about 15 phr binder resin / rubber in the surface layer.

[0059] In addition, the acrylic resin particles can further comprise first particles (e.g., 203b) and second particle (e.g., 203c), where the first particles and second particle have different average particle diameters. For example, the first particles can have an average particle diameter of about 8 μm to about 27 μm, and the second particles can have an average particle diameter that is less than the first particles. Having both first particles and second particles as provided herein can allow for increases in the wear resistance and resistance to electrical deterioration of the charging member along with helping to suppress charging non-uniformity so that the charging performance of the charging members may be sufficiently maintained even when the charging members are used for a longer period of time. Such advantages can lead to high-quality images in which image defects such as background (BG) and micro-jitter are suppressed.

[0060] The amount of the first particles in the binder resin can also differ from the amount of the second particles in the binder resin for the present disclosure. For example, an amount of the first particles in the binder resin can be in a range of about 8 parts by weight to about 12 parts by weight, based on 100 parts by weight of the binder resin, while an amount of the second particles in the binder resin can be in a range of about 5 parts by weight to about 10 parts by weight, based on 100 parts by weight of the binder resin. Stated differently, the content of the first particles are in a range of about 8 to about 12 parts per hundred (phr) binder resin / rubber in the surface layer, for example, while the second particles are in a range of about 5 to about 10 phr binder resin / rubber in86273579 the surface layer, for example.

[0061] As illustrated in the Fig. 2, the particles 203b, 203c can be entirely disposed in the binder resin 203a and thus can form portions of the binder resin that protrude above other portions of the binder resin which do not include the particles 203b, 203c. Having the particles 203b, 203c be entirely disposed in the binder resin 203a can promote aspects herein such as having a given waviness (Wt) value.

[0062] As discussed herein, the conductive elastic body layer of the charging member contains recycled materials, such as recycled-rubber or recycled-carbon, which provides for a specific surface design that considers not only roughness but also waviness within a specific range, even if it has the same roughness, to achieve uniform charging with smaller bead size and lower bead content compared to the charging roller containing the virgin materials. Roughness and waviness are two different aspects of the charging member surface texture that play distinct roles. Roughness refers to the irregularities or fine-scale variations on the surface of the charging member and is characterized by small peaks and valleys in the surface texture as discussed herein. In contrast, waviness refers to the larger, more regular or periodic variations on the surface of the charging member, where the waves on the charging member provide a more extended pattern of peaks and valleys that are on a scale larger than that of roughness.

[0063] Regarding the pattern of the waviness, the relative amounts of the recycled materials in the charging member allow for both a wavelength (distance between successive peaks or valleys in the waviness pattern) and a frequency (number of wave cycles, peaks and valleys, per unit length on the surface) of the waviness that results in improvements of the background noise performance (e.g., of less than 0.8), an absence of micro-jitter; and an absence of image stains. The consistency and alignment of the waves on the charging member (e.g., the waviness) as provided herein also helps in achieving the above noted print properties.

[0064] The present disclosure provides that when the conductive elastic body layer of the charging member contains the recycled material as provided herein waviness is imparted to the charging member (e.g., at the surface layer of the charging member). The waviness includes both an amplitude and a frequency that is influenced by the relative amount of the recycled resin content (e.g., the recycled rubber content relative the virgin rubber content), where the higher the relative recycled resin content the larger the amplitude of the waviness, even though the same roughness is achieved compared to the charging member containing only virgin material (e.g., virgin rubber).86273579 Imparting the waviness to the charging member allows for unevenness to be achieved in the charging member while also allowing for a reduction in both the weight percentage (e.g., less content) and size of the particles used to provide roughness, as discussed herein.

[0065] When using the charging members herein having the surface layer 203 satisfying the above-described conditions, stable charging characteristics may be maintained for a longer period of time even when a DC voltage is applied, and high- quality output images may be obtained. Accordingly, the charging members herein may maintain the ability to uniformly charge the photoconductor over a longer period even when it is used in a contact charging manner. Therefore, since the charging member herein can maintain charging performance and charging uniformity even when the charging members are used for a longer time in an electrophotographic imaging apparatus, it is possible to stably obtain high quality images in which image defects such that background (BG) noise performance is less than 0.8, there is an absence of micro- jitter and an absence of image stains are achieved. Moreover, the charging member herein may maintain stable charging characteristics over a longer period of time even when a DC voltage is applied, high-quality output images may be obtained, and an occurrence of BG under low-temperature and low-moisture environments may be reduced or prevented.

[0066] In some examples, the surface layer 203 satisfies the condition of 3 μm ≤ waviness (Wt) ≤ 15 μm as determined by microscope-enhanced visual observation of the surface layer. As provided herein, the waviness (Wt) is the sum of the largest profile peak height and the largest profile valley depth. For example, the Wt of the surface layer 203 can be 5 μm ≤ Wt ≤ 13 μm as determined by microscope-enhanced visual observation of the surface layer.

[0067] A thickness of the surface layer 203 may be in a range of about 0.1 μm to about 100 μm, or, for example, about 3 μm to about 30 μm. The thickness of the surface layer 203 may be a layer thickness of the portion formed by the binder resin alone. For example, the thickness of the conductive resin layer is a thickness of the binder resin at a point such as an intermediate point between neighboring particles. The thickness of the surface layer 203 may be measured by cutting out the charging member cross section with a sharp blade and observing the piece with an optical microscope or an electron microscope.

[0068] In an example, a DC voltage is applied to the charging members86273579 herein (e.g., charging member 100 as illustrated in Fig.1). For example, the bias voltage applied during image output may be about -1500 V to about -1000 V. This may assist in controlling the image density and various conditions while maintaining the charging performance under various environments. When the bias voltage is higher than -1000 V, it becomes difficult to optimize the developing conditions for image formation. In contrast, when the bias voltage is lower than -1500 V, over-discharge may occur in the particle portions of the conductive resin layer, and white spot-like image defects may occur after image formation.

[0069] Method of Manufacturing Charging member

[0070] The charging member of the example shown in FIG.1 may be manufactured as follows. In an example method, components of the materials for the conductive elastic body layer 102 are kneaded using a kneader to prepare materials for the conductive elastic body layer 102. The materials for the surface layer 103 are kneaded using a kneader such as a roll to obtain a mixture, and an organic solvent is added to this mixture, mixed and stirred, thereby preparing a coating liquid for the surface layer 103. A mold for injection molding, which is provided with a core (usually a shaft) serving as the conductive support 101 therein, is filled with the materials for the conductive elastic body layer 102 by injecting the materials, followed by heating and crosslinking under predetermined conditions. Demolding is performed to a base roll in which the conductive elastic body layer 102 is formed along the outer circumference surface of the conductive support 101. The coating liquid for the surface layer 103 is applied onto the outer circumference surface of the base roll to form the surface layer 103. In this way, a charging member 100 in which the conductive elastic body layer 102 is formed on the outer circumference surface of the conductive support 101 and the surface layer 103 on the outer circumference of the conductive elastic body layer 102 may be manufactured.

[0071] The method of forming the conductive elastic body layer 102 is not limited to injection molding, and casting, press molding, polishing, or a combination thereof may be employed. The method of applying the coating liquid for the surface layer 103 is not particularly limited, and dipping, spray coating, and roll coating may be employed.

[0072] Electrophotographic Imaging Apparatus

[0073] A charging member according to an example may be integrated into a cartridge for an electrophotographic imaging apparatus (referred to herein as an86273579 electrophotographic cartridge) or an electrophotographic imaging apparatus such as a printer, a copier, a scanner, a fax machine, or a multifunction peripheral incorporating two or more of these.

[0074] FIG. 3 is a cross-sectional view schematically illustrating an electrophotographic imaging apparatus and an electrophotographic cartridge including a charging member according to an example. The electrophotographic imaging apparatus having the charging member as provided herein can exhibit a background noise performance of less than 0.8; an absence of micro-jitter; and an absence of image stains.

[0075] Referring to FIG.3, an electrophotographic imaging apparatus 331 may include an electrophotographic cartridge 330. The electrophotographic cartridge 330 may include an electrophotographic photoconductor drum 311 and a charging member 300 contacting the electrophotographic photoconductor drum 311 to charge the electrophotographic photoconductor drum 311 according to an example, which is a charging means disposed in contact with the electrophotographic photoconductor drum 311. The electrophotographic photoconductor drum 311 may be rotationally driven at a predetermined circumferential speed about an axis. The electrophotographic photoconductor drum 311 may be subjected to uniform charging of a positive or a negative predetermined potential on its surface by the charging member 300 in the rotation process. The voltage applied to the charging member 300 may be, for example, a DC voltage. However, the voltage applied to the charging member 300 may be, for example, a combination of an AC voltage and a DC voltage. In the electrophotographic imaging apparatus 331 according to an example, even when a DC voltage is applied to the charging member 300, stable charging characteristics may be maintained for a longer period of time, and a high-quality output image may be obtained.

[0076] The charging member 300 may charge the surface of the electrophotographic photoconductor drum 311 to a uniform potential value while rotating in contact with the electrophotographic photoconductor drum 311. An exposure unit forms an electrostatic latent image on a surface of the electrophotographic photoconductor drum 311. The image portion is exposed by laser light to form an electrostatic latent image on the electrophotographic photoconductor drum 311. After the electrostatic latent image is made a visible image, for example, a toner image, by a developing unit 315 to develop the electrostatic latent image to a visible image, the toner image is transferred to an image receiving member 319 such as paper by a transfer unit86273579 such as the transfer roller 317 to which a voltage is applied to transfer the visible image onto the image receiving member 319. Toner remaining on a surface of the electrophotographic photoconductor drum 311 after the image transfer is cleaned by a cleaning unit to clean a surface of the electrophotographic photoconductor drum, for example, by a cleaning blade 321. The electrophotographic photoconductor drum 311 may be used again for image formation. The developing unit 315 includes a regulating blade 323, a developing roller 325, and a supply roller 327.

[0077] The electrophotographic cartridge 330 according to an example may integrally support the electrophotographic photoconductor drum 311, the charging member 300, and the cleaning blade 321, may be attached to the electrophotographic imaging apparatus 331, and may be detached from the electrophotographic imaging apparatus 331. Another cartridge 329 may integrally support the developing unit 315 including the regulating blade 323, the developing roller 325, and the supply roller 327, and may be detachable to the electrophotographic imaging apparatus 331. Toner (not shown) may be located inside the developing unit 315.

[0078] Examples

[0079] Hereinafter, various examples will be described. However, the scope of the disclosure is not limited thereto.

[0080] Formation of Conductive Elastic Body layer

[0081] An adhesive was applied to a cylindrical stainless-steel shaft having a diameter of 8 mm and a total length of 324 mm (the surface thereof was electroless plated with nickel) and was dried. This shaft was used as a conductive support. The exact amounts (phr) of each component used in forming the conductive elastic body layer are found in Tables 2A, 2B, 3A and 3B. The conductive elastic body layer was formed as follows. Into a hermetic mixer were added the following: 60 to 100 parts by weight of epichlorohydrin virgin rubber (Manufacturer: Daiso Chemical Co., Ltd., product name: EPICHLOMER DG), 0 to 40 parts by weight of recycled acrylonitrile-butadiene rubber (Manufacturer : Earth polymer Co., Ltd., product name : rePRO NBR), 5 to 20 parts by weight of calcium carbonate, 0 to 15 parts by weight of recycled carbon black (Recycled Filler C / B) (Manufacturer : LD carbon Co., Ltd., product name : GCB 770) , 2 parts by weight of carbon black (Manufacturer: Mitsubishi Chemical Corporation, product name: MA100) as a filler, 5 parts by weight of zinc oxide, and 2 parts by weight of tetrabutylammonium chloride as an ion-conducting agent. The resulting mixture was kneaded for 20 minutes after which 1.5 parts by weight of dibenzothiazyl disulfide as a86273579 vulcanization accelerator, 1.2 parts by weight of dipentamethylene thiuram tetrasulfide, and 1.0 part by weight of sulfur as a crosslinking agent were further added thereto and kneaded in an open roll for about 15 minutes to obtain a resin mixture. This resin mixture was extruded together with the shaft using a crosshead rubber extruder to be formed into a roller shape having an outer diameter of about 13 mm. Next, after a vulcanization process was performed in a vulcanization tube at about 160 °C for about 1.5 hours, both ends of the rubber were cut, the surface of the rubber was polished such that the outer diameter of the center portion of the roller became about 12 mm, and then the surface thereof was washed, dried and then irradiated with ultraviolet light to form a conductive elastic body layer (e.g., conductive elastic body layer 102). Thus, a conductive elastic body layer having a thickness of about 4 mm and formed along the outer circumference surface of the shaft was obtained.

[0082] Formation of surface layer on the conducive elastic body layer

[0083] Examples 1 to 12 and Comparative Examples 1 to 12

[0084] 69.26 parts by weight of a polycaprolactone polyol (Manufacturer: Daicel Chemical Industries, product name: PCL320, hydroxyl value: 84 KOH mg / g), 51.24 parts by weight of isocyanate-type blocked HDI (Manufacturer: Aekyung Chemical Co., Ltd., product name: D660, non-volatile matter 60%, NCO 6.5%, blocking agent: methyl ethyl ketone oxime), 1 part by weight of a polymer dispersant (Manufacturer: Lubrizol Co., Ltd., product name: SOLSPERSE™ 20000), 3 parts by weight of carbon black (Manufacturer: Mitsubishi Chemical Corporation, product name: MA100, specific surface area: 110 m2 / g, pH 3.5), 2 parts by weight of hydrophobic fumed silica (Manufacturer: Evonik Resource Efficiency GmbH, trade name: AEROSIL R 974, specific surface area: 110 m2 / g), and 0.1 parts by weight of silicone oil (Manufacturer: ShineEtsu Chemical Co., Ltd., product name: KF6002) were mixed with 200 parts by weight of a methyl isobutyl ketone (MIBK) solvent to form a mixture. Table 1 - Resin and Inorganic Particles86273579

[0085] To the above mixture, resin particles and / or inorganic particles from Table 1 were added in the amounts found in Tables 2A, 2B, 3A and 3B for the given Examples and Comparative Examples and subsequently mixed to form a coating liquid. The coating liquid for each Example and Comparative Example was then used to form the surface layer as follows.

[0086] The coating liquid for forming the surface layer was applied to the surface of the roller having the conductive elastic body layer by a roll coating method. In this case, to obtain a particular layer thickness, coating was performed while scraping off additional coating liquid with a scraper. The coated roller was air-dried for about 10 minutes and then dried at 160 °C for about 1 hour using an oven. Thus, a charging member in which the surface layer having a thickness of about 1.0 μm is laminated on the conductive elastic body layer was obtained. Thus, a charging member including the shaft, which is the conductive support, the conductive elastic body layer laminated along the outer circumference surface of the shaft, and the surface layer laminated along the outer circumference surface of the conductive elastic body layer was manufactured.

[0087] The formulation of the conductive elastic body layer, surface layer and the types and properties of the resin particles or inorganic particles used in Examples 1 to 12 and Comparative Examples 1 to 12 are summarized in Tables 2A, 2B, 3A and 3B. The evaluation results of the charging members are summarized in Tables 4 and 5.862735798627357986273579

[0088] Image Evaluation

[0089] Image evaluations in the case of using the charging members obtained in Examples 1 to 12 and Comparative Examples 1 to 12 are performed as follows. After removing the charging member from a commercially available laser printer (Manufacturer: HP, Model: HP 50PPM Color LaserJet A3), each of the charging members obtained in Examples 1 to 12 and Comparative Examples 1 to 12 was mounted thereon instead of the above charging member. The printer was left for 8 hours86273579 under N / N (temperature 23 °C and relative humidity 55%) environmental conditions. Regarding the initial image obtained using this printer and the image after printing 350,000 sheets of paper, micro-jitter (M / J), background (B / G), and image uniformity (2D noise) were evaluated as follows. The results thereof are summarized in Tables 4 and 5. In this case, printing conditions were as follows.

[0090] Printing speed: typical speed 500 mm / sec;

[0091] Print paper type: Office Paper EC;

[0092] Applied bias: a DC voltage applied to the charging member contacting the photoconductor is appropriately adjusted such that the photoconductor surface potential is - 600 V.

[0093] Evaluation Of Micro-Jitter (M / J)

[0094] The electrophotographic image for micro-jitter evaluation was a half- tone image (medium-concentration image having horizontal stripes of width 1 dot and interval 2 dots in a direction perpendicular to the rotation direction of the photoconductor). This image was observed, and the presence or absence and / or degree of fine horizontal stripes (micro-jitter (M / J)) was evaluated according to the following criteria.

[0095] : Micro-jitter does not appear in the image at all;

[0096] : Micro-jitter appears slightly on a part of the image, but there is no practical issue;

[0097] : Micro-jitter appears slightly at the front of the image, but this is within the usable range; and

[0098] X : Micro-jitter appears at the front of the image, thus causing practical issues.

[0099] Evaluation Of Background (B / G)

[0100] The electrophotographic image for background evaluation is a white image with a medium concentration (density). The whiteness of this output image was measured by "Reflectometer" (Manufacturer: Nippon Denshoku Ind. Ltd., Model Name: Microscopic Area Color Meter / Reflectometer VSR 400). Then, the background concentration (background density) (%) was calculated from a difference between whiteness of the output image and whiteness of the paper. The image background was evaluated according to the following criteria. In the case of initial image evaluation, after86273579 printing 20 sheets of paper under L / L conditions (temperature 12 °C and relative humidity 10%), one sheet of image having the worst image quality was evaluated.

[0101] ©: background density is less than 0.8% (optimally usable);

[0102] : background density is less than 0.8% (usable);

[0103] : background density is 0.8% or greater and less than 1.5% (usable);

[0104] : background density is 1.5% or greater and less than 2.5% (in some cases, usable); and

[0105] X : background density is 2.5% or greater (not usable).

[0106] Evaluation Of Image Uniformity (2D Noise)

[0107] The electrophotographic image for image uniformity evaluation, similar to electrophotographic image for micro-jitter evaluation, is a half-tone image (medium- density image having horizontal stripes of width 2 dots and interval 2 dots in a direction perpendicular to the rotation direction of the photoconductor). This image was observed, and image uniformity was evaluated according to the following criteria. In the case of image evaluation, after printing 20 sheets of paper under H / H conditions (temperature 32 °C and relative humidity 80%), one sheet of image having the worst image quality was evaluated.

[0108] : image density unevenness (so called, image stains) does not exist;

[0109] : image density unevenness does not exist, but image has slight granularity;

[0110] : image density unevenness slightly exists to such a degree of no practical issue; and

[0111] X : image density unevenness exists to impair image quality.

[0112] Wt and Rz measurements

[0113] Measuring equipment: Keyence Laser Microscope

[0114] Measurement method: Measured under the condition of 20x basic lens + 50x optional lens,

[0115] Measurement area: three-dimensional height data with Wt / Rz of multi- lines.

[0116] When getting Wt distinguished from primary profile, cutoff λc.8627357986273579Test Results

[0117] Examples 1 to 6 with the mean roughness depth Rz of 27 μm to 28 μm and waviness height (Wt) 3 μm to 15 μm satisfied the image quality standard, especially in 2D noise and micro-jitter defect up to 350 kpv. Furthermore, the background did not deteriorate due to longitudinal electric resistance increase. In contrast, Comparative Examples 1 to 6 with the mean roughness depth Rz of 27 μm to 28 μm and waviness height (Wt) of less than 3 μm and more than 15 μm had problems in the quality of 2D noise or micro-jitter. In addition, Examples 1 to 6 with the mean roughness depth Rz of 7 μm to 8 μm and waviness height (Wt) 3 μm to 15 μm had no image quality problems including micro-jitter, 2D noise and Background. In Comparative Examples 1 to 6 with the mean roughness depth Rz of 7 μm to 8 μm and waviness height (Wt) of less than 3 μm and more than 1586273579 μm the print quality both of 2D noise and micro-jitter were not satisfied.

[0118] Although examples of the disclosure have been illustrated and described hereinabove, the disclosure is not limited thereto, and may be variously modified and altered by those skilled in the art to which the disclosure pertains without departing from the disclosure claimed. These modifications and alterations are to fall within the scope of the disclosure.

[0119] It will be understood that when an element is referred to as being "on," "connected to", “coupled to”, or "coupled with" another element, it can be directly on, connected, or coupled with the other element or intervening elements may be present. In contrast, when an object is “directly coupled to” or “directly coupled with” another element it is understood that are no intervening elements (adhesives, screws, other elements) etc. As used herein the term “about” refers to value(s) that are within 10 percent, within 5 percent or within 1 percent of a given value that the term about modifies. For instance, the term about can refer to a value(s) that are within 10 percent of a given value.

[0120] The figures herein follow a numbering convention in which the first digit corresponds to the drawing figure number and the remaining digits identify an element or component in the drawing. For example, reference numeral 103 may refer to element 103 in Fig.1 and an analogous element may be identified by reference numeral 203 in Fig. 2. Elements shown in the various figures herein can be added, exchanged, and / or eliminated to provide additional examples of the disclosure. In addition, the proportion and the relative scale of the elements provided in the figures are intended to illustrate the examples of the disclosure, and should not be taken in a limiting sense.

Claims

86273579 WHAT IS CLAIMED IS:

1. A charging member comprising: a conductive support; a conductive elastic body layer on the conductive support, wherein the conductive elastic body layer is formed of a resin mixture, wherein the resin mixture comprises a recycled-rubber resin and a recycled filler; and a surface layer on the conductive elastic body layer, wherein the surface layer includes a binder resin and particles dispersed in the binder resin, the particles including acrylic resin particles having an average particle diameter of about 5 micrometer (μm) to about 33 μm, wherein the surface layer satisfies the condition of 3 μm ≤ waviness (Wt) ≤ 15 μm as determined by microscope-enhanced visual observation of the surface layer.

2. The charging member of claim 1, wherein an amount of the recycled-rubber resin in the resin mixture is in a range of about 5 parts by weight to about 40 parts by weight, based on 100 parts by weight of the resin mixture.

3. The charging member of claim 1, wherein an amount of the recycled filler in the resin mixture is in a range of about 5 parts by weight to about 15 parts by weight, based on 100 parts by weight of the resin mixture.

4. The charging member of claim 1, wherein a ratio of the recycled-rubber resin to the recycled filler is in a range from about 6 parts by weight to about 0.5 parts by weight.

5. The charging member of claim 1, wherein the resin mixture further comprises virgin rubber resin, wherein an amount of the virgin rubber resin in the resin mixture is in a range of about 45 parts by weight to about 90 parts by weight, based on 100 parts by weight of the resin mixture.

6. The charging member of claim 5, wherein the recycled rubber resin and the virgin rubber resin comprise acrylonitrile-butadiene rubber (NBR), Styrene Butadiene Rubber (SBR), epichlorohydrin rubber, or a combination thereof.

7. The charging member of claim 6, wherein:86273579 the recycled rubber resin comprises SBR; and the virgin rubber resin comprises epichlorohydrin rubber.

8. The charging member of claim 1, wherein the charging member is formed as a charging roller.

9. The charging member of claim 1, wherein the recycled filler comprises recycled carbon black.

10. An electrophotographic cartridge for an electrophotographic imaging apparatus, the electrophotographic cartridge comprising: an electrophotographic photoconductor drum; a charging member contacting the electrophotographic photoconductor drum to charge the electrophotographic photoconductor drum; a developing unit to develop an electrostatic latent image to a visible image; and a cleaning unit to clean a surface of the electrophotographic photoconductor drum, wherein the charging member comprises: a conductive support; a conductive elastic body layer on the conductive support, wherein the conductive elastic body layer is formed of a resin mixture that includes: a recycled-rubber resin, wherein an amount of the recycled-rubber resin in the resin mixture is in a range of about 5 parts by weight to about 40 parts by weight, based on 100 parts by weight of the resin mixture; and a recycled filler, wherein an amount of the recycled filler in the resin mixture is in a range of about 5 parts by weight to about 15 parts by weight, based on 100 parts by weight of the resin mixture; and a surface layer on the conductive elastic body layer, wherein the surface layer includes a binder resin and particles dispersed in the binder resin, the particles including acrylic resin particles having an average particle diameter of about 5 micrometer (μm) to about 33 μm, and wherein the surface layer satisfies the condition of 3 μm ≤ waviness (Wt) ≤ 15 μm as determined by microscope-enhanced visual observation of the surface layer.86273579 11. The cartridge of claim 10, wherein the acrylic resin particles further comprises first particles and second particle, and wherein: the first particles have an average particle diameter of about 8 μm to about 27 μm; and the second particles have an average particle diameter that is less than the first particles.

12. The cartridge of claim 11, wherein: an amount of the first particles in the binder resin is in a range of about 8 parts by weight to about 12 parts by weight, based on 100 parts by weight of the binder resin; and an amount of the second particles in the binder resin is in a range of about 5 parts by weight to about 10 parts by weight, based on 100 parts by weight of the binder resin.

13. The cartridge of claim 10, wherein the acrylic resin particles are polymethyl methacrylate (PMMA) particles, polymethyl acrylate (PMAA) particles, or a combination thereof.

14. An electrophotographic imaging apparatus comprising: an electrophotographic photoconductor drum; a charging member contacting the electrophotographic photoconductor drum to charge the electrophotographic photoconductor drum; an exposure unit to form an electrostatic latent image on a surface of the electrophotographic photoconductor drum; a developing unit to develop the electrostatic latent image to a visible image; a transfer unit to transfer the visible image onto an image receiving member; and a cleaning unit to clean a surface of the electrophotographic photoconductor drum, wherein the charging member comprises: a conductive support; a conductive elastic body layer on the conductive support, wherein the conductive elastic body layer is formed of a resin mixture that includes: a recycled-rubber resin, wherein an amount of the recycled-rubber resin in the resin mixture is in a range of about 5 parts by weight to about 40 parts by weight, based on 100 parts by weight of the resin mixture; a virgin resin, wherein an amount of the virgin resin in the resin mixture is in a86273579 range of about 45 parts by weight to about 90 parts by weight, based on 100 parts by weight of the resin mixture; and a recycled filler, wherein an amount of the recycled filler in the resin mixture is in a range of about 5 parts by weight to about 15 parts by weight, based on 100 parts by weight of the resin mixture; and a surface layer on the conductive elastic body layer, wherein the surface layer includes a binder resin and particles dispersed in the binder resin, the particles including acrylic resin particles having an average particle diameter of about 5 micrometer (μm) to about 33 μm, wherein the surface layer satisfies the condition of 3 μm ≤ waviness (Wt) ≤ 15 μm when the surface layer has a roughness in a range from about 5 μm to about 30 μm, and wherein the Wt and roughness are determined by microscope-enhanced visual observation of the surface layer.

15. The electrophotographic imaging apparatus of claim 14, wherein the electrophotographic imaging apparatus exhibits: a background noise performance of less than 0.8; an absence of micro-jitter; and an absence of image stains.

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