Electrophotographic member and development roller

Abstract

To provide an electrophotographic member with improved filming, and a development roller.SOLUTION: The present invention is an electrophotographic member having a Hansen solubility parameter dispersion term δD of 17.0 MPa0.5 or less, a polar term δP of 8.0 MPa0.5 or less, and a hydrogen bond term δH of 7.0 MPa0.5 or less. A development roller of the present invention uses the electrophotographic member of the present invention in a coating layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to electrophotographic members and developing rollers. [Background technology]

[0002] The developing rollers used in electrophotographic image forming apparatuses such as copying machines, printers, and facsimiles have the function of applying a uniform triboelectric charge to the toner and transporting a predetermined amount of toner stably to the development area. In the process of responding to the recent demands for faster operation, longer life, and higher image quality in electrophotographic devices, the performance of the toner has improved, and therefore studies are being conducted on improving the developer transport performance of the developing roller by adjusting the electrical properties of various materials constituting the developing roller.

[0003] For example, Patent Documents 1 and 2 propose a semiconductive roll having excellent electrostatic properties, in which a silane coupling agent is laminated and coated on the outermost layer of a urethane resin film, thereby achieving both excellent durability, flexibility, and a low coefficient of friction.

[0004] When a developing roller is used for a long period of time, the developer may adhere to the surface of the developing roller (hereinafter, also referred to as "filming"). Filming is thought to occur due to deformation or destruction of the developer caused by sliding stress between the developing roller and the contact object that is in pressure contact with the developing roller when the developer is charged or adhered, and further due to melting of the developer caused by frictional heat with the blade, etc. In addition, deformation of the developer may cause vertical streaks in the recorded image. For these reasons, there is a demand for a developing roller that minimizes the occurrence of filming and has stable durable printing performance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-318249 [Patent Document 2] JP 2003-98782 A Summary of the Invention [Problem to be solved by the invention]

[0006] Although the conventional techniques described in the above patent documents have the effect of controlling the amount of contact electrification, in recent years, in the circumstances where higher speeds and higher durability are required, there is a demand for suppressing filming to a higher level. The present invention has been made in view of the above circumstances, and has an object to provide an electrophotographic member and a developing roller capable of improving filming. [Means for solving the problem]

[0007] In the present invention, the dispersion term δD of the Hansen solubility parameter is 17.0MPa 0.5 The polar term δP is 8.0 MPa or less. 0.5 The hydrogen bond term δH is 7.0 MPa or less. 0.5 The electrophotographic member is as follows.

[0008] The electrophotographic member of the present invention preferably contains a urethane resin.

[0009] The present invention includes a shaft body, an elastic layer provided on the outside of the shaft body, and a coating layer provided on the outside of the elastic layer, and the dispersion term δD of the Hansen solubility parameter of the coating layer is 17.0 MPa 0.5 The polar term δP is 8.0 MPa or less. 0.5 The hydrogen bond term δH is 7.0 MPa or less. 0.5 The developing roller is as follows.

[0010] The hardness H of the coating layer is preferably 1.5 GPa or less.

[0011] The composite elastic modulus Er of the coating layer is preferably 7.0 GPa or less.

[0012] The maximum load Pmax in the load-unload curve of the coating layer is preferably 200 μN or less.

[0013] The coating layer preferably contains a urethane resin. Effect of the Invention

[0014] According to the present invention, it is possible to provide an electrophotographic member and a developing roller capable of improving filming. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view illustrating an embodiment of a developing roller of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. [Electrophotographic materials] The electrophotographic member of the present invention has a dispersion term δD of the Hansen solubility parameter of 17.0 MPa. 0.5 The polar term δP is 8.0 MPa or less. 0.5 The hydrogen bond term δH is 7.0 MPa or less. 0.5 The following is the result.

[0017] (Hansen solubility parameters) Here, the Hansen solubility parameter (hereinafter sometimes referred to as "HSP value") will be explained. The Hansen solubility parameter is a value calculated by the following formula (I). HSP value 2 =(δD) 2 +(δP) 2 +(δH) 2 (I) In formula (I), δD, δP, and δH are the following three-dimensional parameters: δD: dispersion term δP: polar term δH: Hydrogen bond term

[0018] δD, δP, and δH can be calculated, for example, by referring to A User's Handbook, Second Edition, C.M. Hansen (2007), Taylor and Francis Group, LLC (HSPiP manual). Specifically, a swelling test is performed on the coating layer in various solvents for which the Hansen solubility parameters have been established, and it is determined whether or not the coating layer swells. The measurement results are then calculated using computer software Hansen Solubility Parameters in Practice (HSPiP), and the dispersion term δD, polar term δP, and hydrogen bond term δH are calculated, respectively. As the solvent, acetone, acetonitrile, 1-butanol, n-butyl acetate, chloroform, cyclohexane, cyclohexanone, diethyl ether, DMF, ethanol, ethyl acetate, ethylene glycol monomethyl ether acetate, hexane, methanol, methyl ethyl ketone, 1-propanol, 2-propanol, t-butyl alcohol, tetrahydrofuran, toluene, etc. can be used.

[0019] The electrophotographic member of the present invention can be produced by curing a composition for forming a coating layer of the developing roller 1, which will be described later.

[0020] The electrophotographic member of the present invention can be used as a surface layer (also called a coating layer) of a developing roller, a pressure roller, a cleaning roller, etc. in an electrophotographic image forming apparatus, for example, a copier, a printer, a facsimile, etc. When the surface layer of these rollers is the electrophotographic member of the present invention, filming can be effectively suppressed.

[0021] [Developing roller] 1, the developing roller 1 of the present invention includes a shaft 2, an elastic layer 3 provided on the outside of the shaft 2, and a coating layer 4 provided on the outside of the elastic layer 3. Each of the components will be described in detail below.

[0022] (Shaft body) The shaft 2 may preferably be a shaft having conductive properties and used in a conventionally known developing roller. The shaft 2 is preferably made of at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass. Such a shaft 2 is also generally known as a "core metal."

[0023] The shaft body 2 may contain an insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. The shaft body 2 may include, for example, a core body made of an insulating resin and a plating layer provided on the core body. Such a shaft body 2 can be obtained, for example, by plating a core body made of an insulating resin to make it conductive. The shaft body 2 is preferably a core bar in order to obtain good electrical conductivity.

[0024] The shape of the shaft body 2 is preferably, for example, rod-like, tubular, etc. The cross-sectional shape of the shaft body 2 may be, for example, circular, elliptical, or non-circular, such as polygonal. The outer peripheral surface of the shaft body 2 may be subjected to treatment such as cleaning treatment, degreasing treatment, and primer treatment.

[0025] The axial length of the shaft body 2 is not particularly limited, and may be adjusted as appropriate depending on the type of the image forming apparatus in which it is installed. The diameter (diameter of the circumscribing circle) of the shaft body 2 is also not particularly limited, and may be adjusted as appropriate depending on the type of the image forming apparatus in which it is installed.

[0026] (Elastic layer) The elastic layer 3 is provided to impart to the developing roller 1 hardness and elasticity that enables it to be pressed against the photosensitive member with an appropriate nip width and nip pressure so that the toner can be supplied to the electrostatic latent image formed on the surface of the photosensitive member without excess or deficiency. Various rubber materials can be used for the elastic layer 3. Examples of rubbers used for the rubber material include ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), fluororubber, silicone rubber, epichlorohydrin rubber, NBR hydride, and urethane rubber. These can be used alone or in combination of two or more. Among these, silicone rubber is preferable from the viewpoint of reducing damage to the toner and compressive stress distortion due to pressing. Examples of silicone rubber include polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, polyphenylvinylsiloxane, and copolymers of these siloxanes. When the elastic layer 3 is made of silicone rubber, it may be a cured product of the rubber composition shown below.

[0027] (Rubber composition) The rubber composition preferably contains a rubber component that forms a silicone rubber by crosslinking, such as a silicone raw rubber such as organopolysiloxane.

[0028] Examples of the organopolysiloxane include organopolysiloxanes represented by the following average composition formula: RnSiO (4-n) / 2 [R represents a monovalent hydrocarbon group which may be substituted. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 12 or less, more preferably 1 or more and 8 or less. Multiple R may be the same or different. n represents a number of 1.95 or more and 2.05 or less.]

[0029] Examples of R in the above formula include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl groups; cycloalkyl groups such as cyclohexyl groups; alkenyl groups such as vinyl, allyl, butenyl, and hexenyl groups; aryl groups such as phenyl and tolyl groups; aralkyl groups such as β-phenylpropyl groups; and organic groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the above groups have been substituted with halogen atoms, cyano groups, or the like, such as chloromethyl, trifluoropropyl, and cyanoethyl groups.

[0030] The organopolysiloxane is preferably an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule. For example, in the above formula, it is preferable that at least two R have the above alkenyl group. It is more preferable that the organopolysiloxane has a vinyl group.

[0031] Specific examples of organopolysiloxane include dimethylpolysiloxane, diphenylpolysiloxane, etc. It is preferable that the molecular chain terminals of the organopolysiloxane are blocked with a trimethylsilyl group, a dimethylvinylsilyl group, a dimethylhydroxysilyl group, a trivinylsilyl group, etc.

[0032] The rubber composition may contain various additives, such as an auxiliary agent such as a conductivity imparting agent, a chain extender, and a crosslinking agent, a catalyst such as an addition reaction catalyst, a reaction control agent, a dispersant, an antiaging agent, an antioxidant, a filler, a pigment, a colorant, a processing aid, a softener, a plasticizer, an emulsifier, a heat resistance improver, a flame retardant improver, an acid acceptor, a thermal conductivity improver, a release agent, and a solvent.

[0033] The rubber composition may be a liquid rubber composition or a millable type rubber composition.

[0034] The rubber composition for forming the elastic layer may contain various additives, such as an auxiliary such as a conductivity imparting agent, a chain extender, and a crosslinking agent, a catalyst such as an addition reaction catalyst, a reaction control agent, a dispersant, an antiaging agent, an antioxidant, a filler, a pigment, a colorant, a processing aid, a softener, a plasticizer, an emulsifier, a heat resistance improver, a flame retardant improver, an acid acceptor, a thermal conductivity improver, a release agent, and a solvent.

[0035] When forming the elastic layer 3 made of silicone rubber, it may be formed by a liquid silicone rubber composition using a LIMS (Liquid Injection Molding System) method, or it may be formed by injection molding using a millable silicone rubber composition. When a millable silicone rubber composition is used, it is preferable that the surface of the elastic layer is polished.

[0036] The elastic layer 3 is preferably a solid layer, and preferably has no hollow space inside the layer. In this specification, "solid" means that the layer has a hollow space of 0.1 mm or less inside. 2 This means that the material does not have more than one hollow space.

[0037] The JIS A hardness (JIS K 6301) of the elastic layer 3 is preferably 20 or more and 55 or less. When the JIS A hardness of the elastic layer 3 is within the above range, the contact area (nip width) between the developing roller 1 and the contacted body (for example, an image carrier such as a photoconductor) becomes large, which tends to further improve the performance such as transfer efficiency, charging efficiency, and development efficiency. In addition, the possibility of mechanically damaging the contacted body is reduced.

[0038] The thickness of the elastic layer 3 is preferably 0.5 mm or more and 10 mm or less, and more preferably 1 mm or more and 5 mm or less, from the viewpoint of ensuring a uniform nip width with the contacted body when in contact with the contacted body. In the present invention, the term "thickness" refers to the thickness in a direction perpendicular to the axial direction of the developing roller 1. The outer diameter of the elastic layer 3 is not particularly limited. The outer diameter may be, for example, 5 mm or more and 20 mm or less. In this specification, the "outer diameter" refers to the outer diameter in a cross section perpendicular to the axial direction of the developing roller 1. The thickness and outer diameter of the elastic layer 3 can be adjusted by methods such as adjusting the amount of rubber composition used when forming the elastic layer 3, or polishing or grinding the outer peripheral surface of the elastic layer 3 after forming the elastic layer 3.

[0039] The outer peripheral surface of the elastic layer 3 may be subjected to a surface treatment such as a primer treatment, a corona treatment, a plasma treatment, an excimer treatment, a UV treatment, an ITO treatment, or a frame treatment.

[0040] (Resistance value of elastic layer) The resistance value of the elastic layer 3 is 1×10 1 Ω or more 1×10 7 By adjusting the resistance value of the elastic layer 3 to fall within this range, it is possible to stabilize the chargeability of the developer, particularly in the initial stage (for example, from 1 to 500 sheets), and to suppress a decrease in print density. The resistance value of the elastic layer 3 is 1×10 3 Ω or more 1×10 7 Ω or less is preferable, and 1×10 4 Ω or more 5×10 6 It is more preferable that it is Ω or less. The resistance value of the elastic layer is measured by the measurement method in the examples described later.

[0041] (covering layer) In order to prevent the occurrence of filming, the coating layer 4 preferably contains a urethane resin, and can be prepared by applying and curing a mixture of the following components (A) to (D) (hereinafter referred to as the coating layer-forming composition). (A) A binder base material obtained by polymerizing a composition consisting of a silicone oil modified at both ends and a first isocyanate compound (hereinafter, simply referred to as the binder base material). (B) a second isocyanate compound (C) Silicone rubber particles and / or acrylic particles having a particle diameter of 0.2 μm or more and 10 μm or less. (D) Diluent solvent

[0042] The mixture is in a liquid state before being heat-cured.

[0043] ((A) Main binder) The binder base is a polymerized composition consisting of a silicone oil modified at both ends and a first isocyanate compound. This composition may further contain a silicone oil modified at one end with a diol, a polyol, and a fluororesin such as a tetrafluoroethylene copolymer, as required.

[0044] (Both end-modified silicone oil) The silicone oil modified at both ends is a type of so-called reactive silicone oil, and has the property of polymerizing with an isocyanate compound.Therefore, it is preferable that the silicone oil modified at both ends of the silicone chain is modified by an amino group (primary or secondary amino group), a mercapto group, or a hydroxyl group.These silicone oils modified at both ends are commercially available as the silicone oil modified at both ends, the mercapto group modified at both ends, the carboxyl group modified at both ends, the phenol group modified at both ends, and the carbinol group modified at both ends.

[0045] Here, examples of the silicone oils that are preferably used in the present invention include silicone oils that are both-end-modified, which are represented by the following general formula (1).

[0046] [ka]

[0047] In general formula (1), R represents -C3H6OC2H4OH or -C3H6OCH2-C(CH2OH)2C2H5, and n represents an integer of 20 or less.

[0048] Among the silicone oils modified at both ends represented by the general formula (1), it is particularly preferable to use a silicone oil in which R at both ends is -C3H6OC2H4OH and n is about 10. Such silicone oils can be appropriately obtained from commercial sources.

[0049] In the general formula (1), the functional group bonded to the silicon atom is a methyl group, but the silicone oil may be one in which the methyl groups are replaced with hydrogen atoms and modified at both ends.

[0050] By including a silicone oil modified at both ends in the mixture for forming the coating layer 4, it is possible to impart appropriate elasticity to the coating layer 4, and also to adjust the electrical properties of the coating layer 4, thereby lowering the relative dielectric constant of the coating layer 4 and effectively suppressing the occurrence of filming.

[0051] (First Isocyanate Compound) In the present invention, the first isocyanate compound used for preparing the binder base is not particularly limited as long as it has reactivity with the reactive group introduced into the silicone oil, but for example, diisocyanates such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and the adduct type, biuret type, isocyanurate type, allophanate type, etc., which are modified products of these isocyanates can be mentioned. Among these isocyanate compounds, isocyanurate type isocyanate compounds and adduct type isocyanate compounds are preferable, and these may be used alone or in combination. The longer the molecular chain of the first isocyanate compound, the more flexible the polyurethane that can be produced.

[0052] In the present invention, the first isocyanate compound used for preparing the binder base is preferably 7.78 parts by mass or more and 23.30 parts by mass or less, more preferably 11.67 parts by mass or more and 19.45 parts by mass or less, relative to 100 parts by mass of both-end modified silicone oil.By making the amount of the first isocyanate compound used relative to both-end modified silicone oil within the above range, the viscosity of the mixture for forming the coating layer 4 can be made suitable, and the workability can be improved.

[0053] (Polyol) As the polyol, an acrylic polyol, a silicone polyol, or the like can be used. The carbonate polyol, the fluorine polyol, and the hydrogenated butadiene polyol react with the first isocyanate compound described above or the second isocyanate compound described below to form a polyurethane. In the present invention, these polyols may be used alone or in combination. As the polyols to be used, it is preferable to use the carbonate polyol and the fluorine polyol alone or in combination.

[0054] The carbonate polyol and / or the fluorine polyol is preferably 5 parts by mass or more and 40 parts by mass or less, more preferably 15 parts by mass or more and 25 parts by mass or less, based on 100 parts by mass of the both-end-modified silicone oil. As these polyols, commercially available products can be used.

[0055] ((B) Second Isocyanate Compound) As the (B) second isocyanate compound used in the coating layer forming composition, various isocyanate compounds (e.g., aromatic isocyanate compounds, aliphatic isocyanate compounds, alicyclic isocyanate compounds) that are usually used in the preparation of polyurethane 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 the aliphatic isocyanate compound include hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornene diisocyanate methyl (NBDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), etc. Examples of the alicyclic polyisocyanate include transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6XDI (hydrogenated XDI), H12MDI (hydrogenated MDI), 4,4'-dicyclohexylmethane diisocyanate, etc.

[0056] In the present invention, the amount of the second isocyanate compound used in the mixed liquid used to form the coating layer 4 is preferably used so that the reaction rate of the second isocyanate compound is 80% or more and 126% or less, preferably 95% or more and 112% or less.

[0057] ((C) Silicone rubber particles, acrylic particles) The mixed liquid for forming the coating layer 4 contains silicone rubber particles and / or acrylic particles. The particle diameter of the silicone rubber particles and acrylic particles is preferably 0.2 μm or more and 10 μm or less, and more preferably 0.8 μm or more and 5 μm or less. By making the particle diameter of the silicone rubber particles and acrylic particles within the above range, the surface roughness of the developing roller 1 is appropriately maintained, and the developer transportability is kept good, while the resolution is maintained at a high level, and deterioration of the image quality can be prevented. The particle diameter of the silicone rubber particles and acrylic particles can be measured by cutting the developing roller 1 and then observing the cross section with a microscope.

[0058] The silicone rubber particles and acrylic particles used in the present invention preferably have heat resistance such that they do not deform or melt even at temperatures of 100° C. or higher, and more preferably have heat resistance at temperatures from 130° C. to 180° C. This makes it possible to prevent the silicone rubber particles and acrylic particles from deforming even at the crosslinking temperature of the coating layer 4. The heat resistance of the silicone rubber particles and acrylic particles can be evaluated by confirming that the silicone rubber particles and acrylic particles do not melt and flow out even when pressure and heat are applied in a melt flow indexer.

[0059] The silicone rubber particles and the acrylic particles may be present (embedded) in the coating layer 4, or a part of them may protrude from the surface of the coating layer 4. In addition, the silicone rubber particles and the acrylic particles may be unevenly dispersed in the coating layer 4, or may be unevenly distributed on the surface side of the coating layer 4.

[0060] Of the silicone rubber particles and the acrylic particles, the silicone rubber particles are preferably those having a structure in which organopolysiloxane such as dimethylpolysiloxane or polyorganosilsesquioxane is crosslinked, and the acrylic particles may be commercially available acrylic particles.

[0061] It is preferable that the silicone rubber particles are prepared from an organopolysiloxane or organopolysilsesquioxane having, as an organic group, one or more monovalent organic groups having 1 to 20 carbon atoms selected from the following: alkyl groups, such as methyl groups, ethyl groups, propyl groups, and butyl groups; aryl groups, such as phenyl groups and tolyl groups; alkenyl groups, such as vinyl groups and allyl groups; aralkyl groups, such as β-phenylethyl groups and β-phenylpropyl groups; monovalent halogenated hydrocarbon groups, such as chloromethyl groups and 3,3,3-trifluoropropyl groups; and reactive group-containing organic groups, such as epoxy groups, amino groups, mercapto groups, acryloxy groups, and methacryloxy groups. The particles prepared from these organopolysiloxanes or organopolysilsesquioxanes may be surface-treated with an organoalkoxysilane. Examples of such silicone rubber particles that can be used include "KMP-597" manufactured by Shin-Etsu Chemical Co., Ltd., and "EP-5500", "EP-2600", "EP-2601", "E-2720", "DY 33-430M", "EP-2720", "EP-9215 Cosmetic Powder", and "9701 Cosmetic Powder" manufactured by Dow Corning Toray Co., Ltd.

[0062] The amount of silicone rubber particles and / or acrylic particles used is preferably 15 to 40 parts by mass, more preferably 20 to 35 parts by mass, relative to 100 parts by mass of the binder base. By setting the amount of silicone rubber particles and / or acrylic particles used within the above range, the surface roughness of the developing roller 1 is appropriately maintained, developer transportability is kept good, while resolution is maintained at a high level, and deterioration of image quality can be prevented.

[0063] ((D) Diluent solvent) As the dilution solvent, aqueous solvents and organic solvents can be used, and low-boiling point solvents and high-boiling point solvents can be used in combination depending on the required drying speed.

[0064] In the present invention, the solid content of the mixture for forming the coating layer 4 is preferably in the range of 10% by mass to 50% by mass, more preferably in the range of 20% by mass to 40% by mass, based on the total amount of the composition for forming the coating layer. If the solid content is low, dripping is likely to occur during application and drying takes a long time, while if the solid content is high, the coating surface becomes rough and thickness control becomes difficult.

[0065] In the present invention, it is preferable to use a dilution solvent that swells the above-mentioned silicone rubber particles or acrylic particles, which allows the silicone rubber particles or acrylic particles to swell in the mixed liquid, making it possible to form a coating layer 4 that is free of repellency or dents, and also to suppress the sedimentation of the silicone rubber particles or acrylic particles in the mixed liquid.

[0066] As such a dilution solvent, it is preferable to use an organic solvent such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), tetrahydrofuran (THF), acetone, ethyl acetate, butyl acetate, toluene, xylene, heptane, cyclohexanone, or isophorone.

[0067] (Composite elastic modulus of coating layer Er) The composite elastic modulus Er of the coating layer is preferably 7.0 GPa or less, and more preferably 6.0 GPa or less.

[0068] (Hardness of coating layer) The hardness H of the coating layer is preferably 1.5 GPa or less, and more preferably 1.0 GPa or less.

[0069] (Maximum load Pmax of the loading / unloading curve of the coating layer) The maximum load Pmax in the load-unload curve of the coating layer is preferably 200 μN or less, and more preferably 190 μN or less.

[0070] If the HSP value is lowered to prevent filming, the resin hardness increases, and vertical streaks may appear in the recorded image during printing. By setting the hardness, composite elastic modulus Er, and maximum load Pmax of the load-unload curve of the coating layer of the present invention within the above-mentioned ranges, filming can be prevented and vertical streaks can also be suppressed.

[0071] Although the present invention has been described above using the embodiments, it goes without saying that the technical scope of the present invention is not limited to the scope of the invention described in the above embodiments, and it is clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. Furthermore, it is clear from the description of the claims that inventions with such modifications or improvements can also be included in the technical scope of the present invention. EXAMPLES

[0072] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples shown below.

[0073] [Examples 1 to 10 and Comparative Examples 1 to 5] The developing roller was produced according to the following procedure.

[0074] (Formation of primer layer) The electroless nickel-plated shaft (made of SUM22, diameter 7.5 mm, length 274.1 mm) was washed with ethanol, and its surface was coated with a silicone primer (product name "Primer No. 16", made by Shin-Etsu Chemical Co., Ltd.). The primer-treated shaft was baked in a gear oven at 150°C for 10 minutes and then cooled at room temperature for 30 minutes or more to form a primer layer on the outer circumferential surface of the shaft.

[0075] (Formation of elastic layer) An elastic body made of a rubber material was molded on the outer circumferential surface of the shaft by extrusion molding using a rubber composition made of silicone rubber. In the extrusion molding, the rubber composition made of silicone rubber was heated at 360°C for 5 minutes using an infrared heating furnace (IR furnace), and then heated at 200°C for 4 hours using a gear oven to harden it. As a result, an elastic layer made of a hardened product of the rubber composition was formed on the outer circumferential surface of the shaft treated with the primer. The elastic layer was a solid layer and the thickness of the elastic layer was 4.25 mm.

[0076] (Formation of coating layer) <(A) Preparation of binder base agent> First, the binder base materials (A1) to (A15) used in the resin composition for forming the covering layer were prepared using the following materials. The formulations are shown in Table 1. Both ends of carbinol-modified silicone oil (KF-6000, Shin-Etsu Chemical Co., Ltd.) Isocyanurate (Duranate TPA-100, manufactured by Asahi Kasei Corporation) Allophanate-modified bifunctional isocyanate (Duranate A201H, manufactured by Asahi Kasei Corporation) Bifunctional isocyanate (Duranate D101, manufactured by Asahi Kasei Corporation) Bifunctional isocyanate (Duranate D201, manufactured by Asahi Kasei Corporation)

[0077] <Preparation of Composition for Forming Coating Layer> Next, compositions for forming a coating layer were prepared using the above-mentioned binder main agents (A1) to (A15) and the following (B) to (D). The formulations are shown in Table 2.

[0078] (B) a second isocyanate compound (B1) Isocyanurate type isocyanate (Duranate TPA-100, manufactured by Asahi Kasei Corporation) (B2) Adduct type isocyanate (Duranate E402-80B, manufactured by Asahi Kasei Corporation) (B3) Biuret type isocyanate (Duranate 24A-100, manufactured by Asahi Kasei Corporation)

[0079] (C) Silicone rubber particles (C1) Silicone rubber spherical particles (EP-2601, average particle size 2 μm, manufactured by Dow Toray Co., Ltd.)

[0080] (D) Diluent solvent (D1) Butyl acetate

[0081] The resin composition for the covering layer was applied to the outer peripheral surface of the elastic layer by spray coating, and heated at 170° C. for 20 minutes to form a covering layer having a thickness of 10 μm. In this manner, a developing roller having a shaft body, an elastic layer, and a covering layer was manufactured.

[0082] [evaluation] The following evaluations were carried out for the above-mentioned Examples and Comparative Examples. The evaluation results are shown in Table 2.

[0083] (Evaluation of print density and filming amount) The print density and filming amount were measured for each of the manufactured developing rollers as follows. The image forming apparatus used was model number: HL-L2360DN (manufactured by Brother Industries, Ltd.). Each of the manufactured developing rollers was mounted in the developing apparatus as the developing roller for this image forming apparatus. Next, a solid image was formed under conditions of a temperature of 23°C and a humidity of 55%, and the print evaluation was confirmed. The filming state after printing 4000 sheets at 1.0% duty and the image quality after printing 4000 sheets (density step rate between the initial print formation part and the final print formation part of the solid print) were evaluated. The density was measured using an X-Rite504 spectrodensitometer manufactured by X-Rite.

[0084] <Print density> After printing each solid image under conditions of temperature 23°C and humidity 55% RH, the print density of the solid image was measured using a spectrodensitometer 504 manufactured by X-Rite Corp. Specifically, 1.35 or more was rated as ◯, 1.30 or more but less than 1.35 was rated as △, and less than 1.30 was rated as ×, with a rating of A or more being a pass. 〇: 1.35 or higher △: 1.30 or more and less than 1.35 ×: Less than 1.30

[0085] <Filming amount> After sucking the developer adhering to the surface of the developing roller, the mass of the developer transferred to the filming weight measuring jig was measured. The mass of the transferred developer was evaluated according to the following evaluation criteria. The filming evaluation was passed when it was rated as ◯. -Evaluation criteria- ○: 0.00 mg / cm 2 More than 0.03mg / cm 2 below △: 0.03mg / cm 2 More than 0.06mg / cm 2 below ×:0.06mg / cm 2 More

[0086] (Suppression of vertical streaks) The developing rollers of the above examples and comparative examples were mounted in cartridges in a monochrome image forming apparatus (model number: HL-L2360DN (manufactured by Brother Industries, Ltd.)), and the occurrence of vertical streaks after printing 4,000 sheets at 1.0% duty under environmental conditions of 23°C and 55% RH was evaluated. Images in which no vertical white streaks occurred were marked with an ◯, and images in which vertical white streaks occurred were marked with an X.

[0087] (Resistance value of elastic layer) After the elastic layer was formed, the resistance value of the elastic layer was measured using an R8340 ULTRA HIGH RESISTANCE METER (manufactured by ADVANTEST Co., Ltd.).

[0088] (HSP value of coating layer) A film sample of the coating layer measuring 5 mm in length, 10 mm in width, and 0.5 mm in thickness was prepared, and a wettability test was performed by immersing it in various solvents for which the Hansen solubility parameters have been established to determine whether it would swell. The measurement results were then calculated using computer software Hansen Solubility Parameters in Practice (HSPiP), and the dispersion term δD, polar term δP, and hydrogen bond term δH were calculated. The solvents used were acetone, acetonitrile, 1-butanol, n-butyl acetate, chloroform, cyclohexane, cyclohexanone, diethyl ether, DMF, ethanol, ethyl acetate, ethylene glycol monomethyl ether acetate, hexane, methanol, methyl ethyl ketone, 1-propanol, 2-propanol, t-butyl alcohol, tetrahydrofuran, and toluene.

[0089] (Nanoindenter measurement: composite elastic modulus Er, hardness H, maximum load) The nanoindentation method was used to measure the composite elastic modulus Er (GPa), hardness H (GPa), and maximum load (μN) using a nanoindenter measuring device (product name: Hysitron TI Premier, manufactured by Bruker) as the measuring device and a Berkovich indenter as the measuring terminal, with a pressing depth of 5 μm during measurement.

[0090] [Table 1]

[0091] [Table 2]

[0092] The dispersion term δD of the Hansen solubility parameter is 17.0MPa. 0.5 The polar term δP is 8.0 MPa or less. 0.5 The hydrogen bond term δH is 7.0 MPa or less. 0.5 The examples in which the following members were used for the covering layer were evaluated as being good in terms of print density, amount of filming, and vertical streaks. [Explanation of symbols]

[0093] 1 Developing roller 2-axis body 3 Elastic layer 4 Covering layer

Claims

1. The dispersion term δD of the Hansen solubility parameter is 17.0 MPa. ０．５ The polar term δP is 8.0 MPa or less. ０．５ The hydrogen bond term δH is 7.0 MPa or less. ０．５ 1. An electrophotographic member comprising:

2. 2. The electrophotographic member of claim 1, which comprises a urethane resin.

3. The shaft body includes an elastic layer provided on the outside of the shaft body, and a coating layer provided on the outside of the elastic layer, The dispersion term δD of the Hansen solubility parameter of the coating layer is 17.0 MPa. ０．５ The polar term δP is 8.0 MPa or less. ０．５ The hydrogen bond term δH is 7.0 MPa or less. ０．５ The developing roller is as follows.

4. 4. The developing roller according to claim 3, wherein the hardness H of the coating layer is 1.5 GPa or less.

5. 4. The developing roller according to claim 3, wherein the coating layer has a composite elastic modulus Er of 7.0 GPa or less.

6. 4. The developing roller according to claim 3, wherein the maximum load Pmax in a load-unload curve of said coating layer is 200 [mu]N or less.

7. 7. The developing roller according to claim 3, wherein the coating layer contains a urethane resin.

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