Developing roller

Abstract

To provide a developing roller that satisfactorily reduces fogging at the last stage of a durable period in a high temperature and high humidity environment and ghost in a low temperature and low humidity environment.SOLUTION: The present invention is a developing roller comprising a shaft body 2, an elastic layer 3 provided on an outer peripheral surface of the shaft body 2, and a coating layer 4 provided on the outside of the elastic layer 3. The coating layer 4 contains silicone-modified urethane resin and silicone rubber particles. The developed area ratio Sdr of an interface of the coating layer 4 is 0.4 or more and 1.5 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a developing roller.

Background Art

[0002] A developing roller used in an image forming apparatus such as a copying machine, a printer, or a facsimile machine that employs an electrophotographic method has a function of imparting a uniform frictional charge to toner and stably transporting a predetermined amount of toner to a developing area. In recent years, for the purpose of suppressing power consumption in an electrophotographic copying machine and high-speed printing, etc., the melting point of the toner used for printing has been lowered.

[0003] However, such a low-melting-point toner has a problem that it is easily melted by frictional heat due to the pressing of the developing roller and other regulating members, and the melted toner adheres to the developing roller. Further, in a high-temperature and high-humidity environment, due to the influence of moisture, the charging property of the toner itself tends to decrease. Therefore, at the end of durability, a phenomenon called fogging occurs, in which defective charged toner adheres to the white area (background area) of the image. Also, in a low-temperature and low-humidity environment, a phenomenon called ghosting occurs, in which the image history from a week ago on the developing roller appears in the image corresponding to the next week.

[0004] In order to solve such problems, Patent Document 1 discloses providing recesses in an elastic layer by laser and setting Sdr (interface development area ratio, hereinafter sometimes simply referred to as Sdr) to 5 or less.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in order to meet the demands for faster image forming apparatuses, a higher level of improvement in fogging and ghosting than that described in Patent Document 1 is desired. This invention has been made in view of the above circumstances, and aims to provide a developing roller that effectively reduces fogging at the end of its lifespan in high-temperature, high-humidity environments and ghosting in low-temperature, low-humidity environments. [Means for solving the problem]

[0007] A higher Sdr value increases the number of contacts between the toner and the developing roller, allowing the toner to be sufficiently charged and improving fogging in high-temperature, high-humidity environments. On the other hand, if Sdr is too high, overcharged toner is more likely to occur in low-temperature, low-humidity environments, worsening ghosting. As a result of diligent research, the inventors discovered that by adding silicone rubber particles to the elastic layer and setting Sdr within a specific range, both fogging at the end of durability in high-temperature, high-humidity environments and ghosting in low-temperature, low-humidity environments can be improved, leading to the present invention. The present invention relates to a developing roller comprising a shaft, an elastic layer provided on the outer circumferential surface of the shaft, and a coating layer provided outside the elastic layer, wherein the coating layer contains a silicone-modified urethane resin and silicone rubber particles, and the developed area ratio Sdr of the interface of the coating layer is 0.4 or more and 1.5 or less.

[0008] The average particle size of the silicone rubber particles is preferably between 0.2 μm and 10 μm.

[0009] The content of silicone rubber particles is preferably 35 parts by mass or more and 70 parts by mass or less per 100 parts by mass of silicone-modified urethane resin. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a developing roller in which fogging at the end of its lifespan in a high-temperature, high-humidity environment and ghosting in a low-temperature, low-humidity environment are significantly reduced. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view showing one embodiment of the developing roller of the present invention. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described in detail below with reference to the drawings. [developing roller] As shown in Figure 1, the developing roller 1 of the present invention comprises a shaft 2, an elastic layer 3 provided on the outer circumferential surface of the shaft 2, and a coating layer 4 provided outside the elastic layer 3. The details of each component are explained below.

[0013] <Shaft> The shaft 2 can preferably be a conventionally known shaft used in developing rollers, which has conductive properties. The shaft 2 is preferably made of at least one metal selected from the group consisting of, for example, iron, aluminum, stainless steel, and brass. Such a shaft 2 is also generally known as a "core metal".

[0014] The shaft 2 may contain an insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. The shaft 2 may comprise, for example, a core made of an insulating resin and a plating layer provided on this core. Such a shaft 2 can be obtained, for example, by plating a core made of an insulating resin to make it conductive. The shaft 2 is preferably a core metal in order to obtain good conductivity characteristics.

[0015] The shape of the shaft 2 is preferably, for example, rod-shaped, tubular, etc. The cross-sectional shape of the shaft 2 may be, for example, circular, elliptical, or non-circular, such as a polygon. The outer surface of the shaft 2 may be treated with cleaning, degreasing, priming, etc.

[0016] The axial length of the shaft body 2 is not particularly limited and may be appropriately adjusted according to the form of the image forming apparatus to be installed. Also, the diameter (diameter of the circumscribed circle) of the shaft body 2 is not particularly limited and may be appropriately adjusted according to the form of the image forming apparatus to be installed.

[0017] <Elastic layer> The elastic layer 3 is provided to impart to the developing roller 1 a hardness and elasticity that can press the photosensitive member with an appropriate nip width and nip pressure so that toner can be supplied to the electrostatic latent image formed on the surface of the photosensitive member without excess or deficiency. The elastic layer 3 contains silicone rubber. Silicone rubber has the advantage that the compressive stress strain due to pressing is small. Examples of silicone rubber include polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, polyphenylvinylsiloxane, and copolymers of these siloxanes.

[0018] The conductivity of the elastic layer 3 can be appropriately adjusted by blending a conductivity-imparting agent such as an electron-conductive substance or an ion-conductive substance therein. Examples of electron-conductive substances include conductive carbons such as Ketjen black EC and acetylene black, rubbers carbons such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, carbons for color (ink) subjected to oxidation treatment, metals such as copper, silver, and germanium, and metal oxides thereof. Among these, carbon black (conductive carbon, rubber carbon, carbon for color (ink)) is preferable because the conductivity can be easily controlled with a small amount. Examples of ion-conductive substances include inorganic ion-conductive substances such as sodium perchlorate, lithium perchlorate, calcium perchlorate, lithium chloride, lithium bisimide, and potassium bisimide, and organic ion-conductive substances such as modified aliphatic dimethylammonium ethosulfate and stearylammonium acetate. A reactive ether-modified silicone oil may be added to the elastic layer 3.

[0019] <Coating layer> The coating layer 4 contains a silicone-modified urethane resin and silicone rubber particles. The coating layer 4 can be formed by heating and curing a coating layer composition containing (A) a silicone-modified polyol, (B) an isocyanate compound, and (C) silicone rubber particles. The details of the coating layer composition are described below.

[0020] (A) Silicone-modified polyol Silicone-modified polyols are prepolymerized by polymerizing a composition consisting of modified silicone oil and an isocyanate compound. The details of the modified silicone oils and isocyanate compounds used in the synthesis of silicone-modified polyols are described below. Modified silicone oils include double-ended modified silicone oils and single-ended modified silicone oils.

[0021] - Modified silicone oil at both ends - Double-ended modified silicone oils are a type of so-called reactive silicone oil and have the property of polymerizing with isocyanate compounds. Therefore, it is preferable that both ends of the silicone chain of the double-ended modified silicone oil are modified with ether groups, amino groups (primary or secondary amino groups), mercapto groups, or hydroxyl groups. These double-ended modified silicone oils are commercially available as double-ended ether-modified silicone oils, double-ended amino-modified silicone oils, double-ended mercapto-modified silicone oils, double-ended carboxyl-modified silicone oils, double-ended phenol-modified silicone oils, and double-ended carbinol-modified silicone oils.

[0022] In this invention, preferred double-ended modified silicone oils used in this invention include the double-ended modified silicone oil represented by the following general formula (1).

[0023] [ka]

[0024] In general formula (1), R represents -C3H6OC2H4OH or -C3H6OCH2-C(CH2OH)2C2H5, and n represents an integer less than or equal to 20.

[0025] Among the double-ended modified silicone oils represented by general formula (1), it is particularly preferable to use a silicone oil in which the R at both ends is -C3H6OC2H4OH and n is approximately 10. Such silicone oils can be appropriately obtained from the market.

[0026] In general formula (1), the functional group bonded to the silicon atom is a methyl group, but this methyl group may be replaced with a hydrogen atom in a modified silicone oil with modified ends.

[0027] By including modified silicone oil at both ends in the composition for forming the coating layer 4, the coating layer 4 can be given appropriate elasticity, its electrical properties can be adjusted, and the occurrence of filming can be effectively suppressed.

[0028] -Terminal diol-modified silicone oil- One-ended diol-modified silicone oil is a reactive silicone oil, similar to two-ended modified silicone oil, but it has two hydroxyl groups bonded to one end of the silicone chain. Normally, when two-ended modified silicone oil is polymerized with an isocyanate compound, a linear polyurethane is produced. However, by using one-ended diol-modified silicone oil in combination, branched chains are introduced into the polyurethane, which can improve the nanoscale fine roughness of the developing roller 1.

[0029] Examples of one-ended diol-modified silicone oils include the one-ended modified silicone oil represented by the following general formula (2).

[0030] [ka]

[0031] In general formula (2), R' represents -C3H6OCH2-C(CH2OH)2C2H5, and n represents an integer less than or equal to 20.

[0032] Among the one-terminated diol-modified silicone oils represented by general formula (2), it is particularly preferable to use a silicone oil in which n is approximately 10. In general formula (2), the functional group bonded to the silicon atom is a methyl group, but a silicone oil in which this methyl group is substituted with a hydrogen atom may also be used.

[0033] In the present invention, the amount of one-ended diol-modified silicone oil used for preparing the silicone-modified polyol is preferably 1 to 10 parts by mass, and more preferably 2 to 8 parts by mass, per 100 parts by mass of the double-ended modified silicone oil. By adjusting the amount of one-ended diol-modified silicone oil used relative to the double-ended modified silicone oil within the above range, the surface roughness of the coating layer 4 can be adjusted, thereby effectively preventing filming while maintaining good developing performance.

[0034] -Isocyanate compounds- In the present invention, the isocyanate compound used for prepolymerization of the silicone-modified polyol is not particularly limited as long as it has reactivity with the reactive group introduced into the silicone oil. Examples include diisocyanates such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), and hexamethylene diisocyanate (HDI), as well as modified forms of these isocyanates, such as adduct type, burette type, isocyanurate type, and allophanate type. Among these isocyanate compounds, bifunctional isocyanate compounds, isocyanurate type isocyanate compounds, and adduct type isocyanate compounds are preferred, and these may be used individually or in combination. The longer the molecular chain of the isocyanate compound, the more flexible the polyurethane that can be produced.

[0035] (B) Isocyanate compounds As isocyanate compounds for curing silicone-modified polyols, various isocyanate compounds commonly used in the preparation of polyurethanes, such as aromatic isocyanate compounds, aliphatic isocyanate compounds, and alicyclic isocyanate compounds, can be used. Examples of aromatic isocyanate compounds include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), and 3,3'-dimethylbiphenyl-4,4'-diisocyanate. Examples of aliphatic isocyanate compounds include hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornene diisocyanate methyl (NBDI), xylylene diisocyanate (XDI), and tetramethyl xylylene diisocyanate (TMXDI). Furthermore, examples of alicyclic polyisocyanates include transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6XDI (hydrogenated XDI), H12MDI (hydrogenated MDI), and 4,4'-dicyclohexylmethane diisocyanate.

[0036] In the present invention, the amount of isocyanate compound used in the composition for forming the coating layer 4 is preferably such that the reaction rate of the isocyanate compound is 80% or more and 126% or less, preferably 95% or more and 112% or less.

[0037] (C) Silicone rubber particles The silicone rubber of the silicone rubber particles preferably has a crosslinked structure of dimethylpolysiloxane, organopolysiloxane, or polyorganosilsesquioxane. Specifically, it is preferable to prepare the particles from an organopolysiloxane or organopolysilsesquioxane having a group selected from one or more monovalent organic groups having 1 to 20 carbon atoms, selected from alkyl groups such as methyl, ethyl, propyl, and butyl groups; aryl groups such as phenyl and tolyl groups; alkenyl groups such as vinyl and allyl groups; aralkyl groups such as β-phenylethyl and β-phenylpropyl groups; monovalent halogenated hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl groups; and reactive group-containing organic groups such as epoxy, amino, mercapto, acryloxy, and methacryloxy groups. Furthermore, particles prepared from the above organopolysiloxane or organopolysilsesquioxane may also be surface-treated with organoalkoxysilane.

[0038] Examples of such silicone rubber particles include "KMP-597" and "KMP-600" from Shin-Etsu Chemical Co., Ltd., and "EP-5500," "EP-2600," "EP-2601," "EP-2720," "DY 33-430M," "EP-9215 Cosmetic Powder," and "9701 Cosmetic Powder" from Dow Toray Industries, Inc.

[0039] The silicone rubber particles used in this invention preferably have heat resistance that prevents deformation or melting even at temperatures of 100°C or higher, and more preferably have heat resistance between 130°C and 180°C. This prevents deformation of these silicone rubber particles even at the crosslinking temperature of the coating layer 4. The heat resistance of the silicone rubber particles can be evaluated by confirming in a melt flow indexer that the silicone rubber particles do not melt and flow out even when pressure and heat are applied.

[0040] The hardness of the silicone rubber particles is preferably 20 degrees to 80 degrees, and more preferably 50 degrees to 75 degrees, as measured by durometer A (instantaneous) (JIS K 6253:1997). By keeping the hardness of the silicone rubber particles within the above range, it is possible to effectively prevent an increase in the friction coefficient of the coating layer 4 due to the fracture or deformation of the silicone rubber particles. Furthermore, it is possible to prevent the occurrence of cracks and fissures in the coating layer 4 due to excessive hardness of the coating layer 4, thereby preventing excessive stress on the toner.

[0041] The content of silicone rubber particles is preferably 35 parts by mass or more and 70 parts by mass or less, and more preferably 40 parts by mass or more and 60 parts by mass or less, per 100 parts by mass of silicone-modified urethane resin. By using silicone rubber particles within the above range, the chargeability of the positively charged toner can be improved, thereby improving fogging. The coating layer 4 may contain only one type of silicone rubber particle, or it may contain two or more types.

[0042] The average particle size of the silicone rubber particles is preferably 0.2 μm to 10 μm, and more preferably 0.8 μm to 5 μm. By keeping the average particle size of the silicone rubber particles within the above range, the surface roughness of the elastic roller 1 is appropriately maintained, good developer transportability is maintained, and at the same time, a high level of resolution can be maintained, preventing deterioration of image quality. The average particle size of silicone rubber particles can be measured as the median diameter using a particle size distribution analyzer based on laser diffraction.

[0043] The thickness of the coating layer 4 is preferably 5 μm to 13 μm, and more preferably 6 μm to 11 μm.

[0044] (Interface area ratio Sdr) The Sdr ratio of the interface of the coating layer 4 is 0.4 or more and 1.5 or less, preferably 0.4 or more and 1.4 or less. A Sdr ratio of 0.4 or more effectively prevents fogging in high-temperature and high-humidity environments. Furthermore, a Sdr ratio of 1.5 or less effectively prevents ghosting in low-temperature and low-humidity environments.

[0045] (Arithmetic mean curvature of the mountain peak Spc) The arithmetic mean curvature Spc at the peak of the coating layer 4 is preferably 5000 / mm or more and 11000 / mm or less, and more preferably 6000 / mm or more and 10500 / mm or less. An arithmetic mean curvature Spc of 5000 / mm or more at the peak of the coating layer 4 effectively prevents clouding in high-temperature, high-humidity environments. Furthermore, an arithmetic mean curvature Spc of 11000 / mm or less effectively prevents ghosting in low-temperature, low-humidity environments.

[0046] (Resistance value of the surface of the coating layer) The surface resistance of the coating layer 4 of the developing roller 1 of the present invention is 1 × 10 7 Ω or more 9×10 9 Preferably, it is less than or equal to Ω, and 1 × 10 7 Ω or more 3×10 9 It is more preferable that the resistance is less than or equal to Ω. 9 Image quality is good when the resistance is below Ω. The lower limit of the resistance value is the maximum resistance value that can be achieved without conductive material. The surface resistance of the developing roller 1 can be adjusted by the combination of silicone-modified polyol and isocyanate compound types in the coating layer 4. If necessary, the resistance can be controlled by adding reactive ether-modified silicone oil. The resistance value of the surface of the coating layer 4 shall be the value measured by the method described in the embodiment below.

[0047] (Capacitance of the coating layer) The capacitance of the coating layer 4 of the developing roller 1 is preferably 11 nF or less at 0.1 Hz, and from the viewpoint of maintaining good tonal gradation of the resulting image density, the lower limit is preferably around 0.5 nF. That is, the capacitance is more preferably between 0.5 nF and 11 nF. By having the capacitance within the above range, the toner release properties are good and filming can be effectively suppressed. In the coating layer 4, conductive agents such as carbon or ionic conductive materials are not used because they increase capacitance, resulting in poor toner release properties.

[0048] (MD-1 hardness) The MD-1 hardness of the coating layer 4 is more preferably 20° to 60°, and even more preferably 30° to 50°. By adjusting the MD-1 hardness of the coating layer 4 to the above range, the load on the developer can be reduced while maintaining the amount of developer transported. An MD-1 hardness tester ("Micro Rubber Hardness Tester MD-1," manufactured by Polymer Instruments Co., Ltd.) can be used to measure MD-1 hardness. In this invention, the indenter of the MD-1 hardness tester is pressed against the roller surface, and the value read in peak hold mode with a hold time of 3 seconds is defined as the MD-1 hardness. The MD-1 hardness tester is, in principle, based on the Type A durometer described in JIS K6253.

[0049] (Other ingredients) The coating layer composition may contain a diluent solvent and auxiliary agents commonly used in the reaction between (a) a silicone-modified polyol and (b) an isocyanate compound, such as chain extenders and crosslinking agents. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, and amines. Furthermore, known fillers, such as silica, spherical resin particles, and metal oxides, may be included, to the extent that they do not impede the effects of the present invention.

[0050] <Other configurations> The developing roller 1 of the present invention may have adhesive layers between the shaft 2 and the elastic layer 3, and between the elastic layer 3 and the coating layer 4. The surface of the elastic layer 3 may be modified by irradiating it with UV light or the like, or an adhesive layer may be provided by priming. Alternatively, surface modification and an adhesive layer may be provided simultaneously by plasma coating. [Examples]

[0051] The present invention will be described in detail below with reference to examples. However, the present invention is not limited in any way to the examples shown below.

[0052] [Example 1] The developing roller for Example 1 was fabricated using the following procedure. (Formation of primer layer) A shaft (made of SUM23, 6.0 mm in diameter, 262.3 mm in length) that had been electroless nickel plated was cleaned with ethanol, and a silicone-based primer (product name "Primer No. 16", manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to its surface. The primer-treated shaft was then baked in a gear oven at 150°C for 10 minutes, and then cooled at room temperature for more than 30 minutes to form a primer layer on the outer surface of the shaft.

[0053] (Formation of an elastic layer) An elastic body made of rubber material was formed on the outer surface of a shaft by extrusion molding using a millable-type silicone rubber composition. In the extrusion molding process, the silicone rubber composition was heated at 270°C for 5 minutes using an infrared (IR) furnace, and then cured by heating at 200°C for 4 hours using a gear oven. This formed an elastic layer made of the cured rubber composition on the outer surface of the primer-treated shaft. The elastic layer 3 was a solid layer, and its thickness was 3.5 mm.

[0054] (Formation of the coating layer) The coating layer composition was prepared using the following materials according to the formulation shown in Table 1. The base resin was a silicone-modified urethane resin formed from the silicone-modified polyol and isocyanate described below.

[0055] -(A) Preparation of silicone-modified polyols- The following materials were mixed in the following proportions: (A1) 71.5 parts by mass, (A2) 3.7 parts by mass, and (A3) 24.8 parts by mass. This mixture was then held at 100°C to 120°C for 4 to 6 hours to prepare a silicone-modified polyol. • (A1) End-modified silicone oil (product name "KF-6000", manufactured by Shin-Etsu Chemical Co., Ltd.) • (A2) Diol-modified silicone oil (product name "X-22-176DX", manufactured by Shin-Etsu Chemical Co., Ltd.) • (A3) Isocyanate (product name "D201", manufactured by Asahi Kasei Corporation) In preparing the above composition, a catalyst and diluent solvent may be added as appropriate.

[0056] -Coating layer composition- (A) Silicone-modified polyol 89.4 parts by mass (B) Isocyanate (product name "TPA-100", manufactured by Asahi Kasei Corporation) 10.6 parts by mass • (C) Silicone rubber particles (product name "KMP-600", average particle size 5 μm, manufactured by Shin-Etsu Chemical Co., Ltd.) 41.8 parts by mass A catalyst and a diluent solvent may be added to the above coating layer composition as appropriate.

[0057] Next, the outer surface of the elastic layer was UV treated. Then, the coating layer composition was applied to the UV-treated elastic layer by spraying. The applied composition was heated at 150°C to 160°C for 30 minutes to obtain a developing roller. The thickness of the coating layer after drying was 9 μm.

[0058] [Example 2, Example 3, Comparative Example 1, and Comparative Example 2] As shown in Table 1, a developing roller was prepared in the same manner as in Example 1, except that the content of silicone rubber particles was changed.

[0059] [evaluation] The above examples and comparative examples were evaluated as follows. The evaluation results are shown in Table 1.

[0060] (Method for evaluating overlap) The developing rollers prepared in the above examples and comparative examples were mounted in an image forming apparatus "HL-1110 (manufactured by Brother Industries, Ltd.)" and 1500 prints were made with 0.3% duty cycle in a high-temperature, high-humidity environment (32°C, 80%RH). The solid white print was stopped instantaneously, and the image was transferred to white paper by attaching tape to the photosensitive drum. The tape was attached to a reference sheet of paper, and the color difference ΔE between the reference value and the transferred area was measured. Note that in Table 1, the evaluation item is labeled as "HH fogging". ○: ΔE is less than 1.0 △: ΔE is between 1.0 and 1.5 (inclusive). ×: ΔE is 1.5 or greater

[0061] (How to evaluate ghosts) In a low-temperature, low-humidity environment (10°C, 20%RH), originals with a solid image followed by a 50% halftone image were printed, and the afterimage was evaluated based on the density difference. Note that the evaluation item in Table 1 is labeled "LL Ghost". ○: Concentration difference is less than 0.05 △: Concentration difference is 0.05 or more but less than 0.1 ×: Concentration difference is 0.1 or greater

[0062] (Measurement of surface roughness according to ISO 25178 parameters) For the coating layer of the fabricated developing roller, the interface development area ratio Sdr and the arithmetic mean curvature Spc of the peaks were calculated using a shape analysis laser microscope VK-X1000 (manufactured by Keyence Corporation) under the following measurement conditions. <Measurement conditions> Observation magnification: 1200x Observation area: 60,000 μm² 2 Tilt correction: Surface tilt correction (automatic) S-filter: None F-Operation: None L-filter: None

[0063] [Table 1]

[0064] As shown in Table 1, it can be seen that both fogging and ghosting are improved when the Sdr of the elastic layer of the developing roller of the present invention is between 0.4 and 1.5. [Explanation of Symbols]

[0065] 1. Developing roller 2-axis body 3. Elastic layer 4 Covering layer

Claims

1. A developing roller comprising a shaft, an elastic layer provided on the outer circumferential surface of the shaft, and a coating layer provided outside the elastic layer, The coating layer contains a silicone-modified urethane resin and silicone rubber particles, The interface area ratio Sdr of the coating layer is 0.50 or more and 1.32 or less. A developing roller in which the average particle size of the silicone rubber particles is 0.8 μm or more and 5 μm or less.

2. The developing roller according to claim 1, wherein the content of the silicone rubber particles is 41.8 parts by mass or more and 62.6 parts by mass or less per 100 parts by mass of silicone-modified urethane resin.

3. The developing roller according to claim 1, wherein the elastic layer contains silicone rubber.

4. The developing roller according to claim 1, wherein the arithmetic mean curvature Spc of the peak of the coating layer is 5000 / mm or more and 11000 / mm or less.

Images