JP6010280B2 - Developing roller - Google Patents

Description

  The present invention relates to a developing roller (hereinafter also simply referred to as “roller”), and more particularly to a developing roller used in an image forming apparatus such as an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus.

  In recent years, with the advancement of electrophotographic technology, there has been an increasing demand for conductive members used in each electrophotographic process. In particular, the developing roller used in the developing process is required to have not only a predetermined electric resistance value but also various characteristics corresponding to the developing mechanism.

  Conventionally, as a developing method when a non-magnetic one-component developer is used as a developer (toner), toner is supplied to an image carrier such as a photosensitive drum holding an electrostatic latent image, and a latent image on the image carrier is obtained. A development method (pressure development method) is known in which a latent image is visualized by adhering toner to the toner. According to this method, since no magnetic material is required, the apparatus can be easily simplified and miniaturized, and the toner can be easily colored. In the pressure development method, development is performed by bringing a developing roller carrying toner into contact with an image carrier holding an electrostatic latent image and attaching the toner to the latent image on the image carrier. The developing roller used in this method needs to be formed of a conductive elastic body.

  FIG. 2 shows a configuration example of a developing device using a pressure developing method. In the illustrated developing device, a developing roller 10 is disposed in contact with a photosensitive drum 12 between a toner supply roller 11 for supplying toner and a photosensitive drum 12 holding an electrostatic latent image. As the developing roller 10, the photosensitive drum 12, and the toner supply roller 11 rotate in the directions of the arrows in the drawing, the toner 13 is supplied to the surface of the developing roller 10 by the toner supply roller 11. The supplied toner is adjusted to a uniform thin layer by the stratifying blade 14, and the developing roller 10 rotates in contact with the photosensitive drum 12 in this state, whereby the toner formed in the thin layer is transferred from the developing roller 10 to the photosensitive drum. The latent image is visualized by attaching to the 12 latent images. Note that reference numeral 15 in the drawing denotes a transfer portion, where a toner image is transferred to a recording medium such as paper. Reference numeral 16 denotes a cleaning unit, and toner remaining on the surface of the photosensitive drum 12 after transfer is removed by a cleaning blade 17. Reference numeral 18 denotes a charging roller that contacts the photosensitive drum 12 and charges the photosensitive drum 12.

  In this case, since the developing roller 10 must rotate while securely holding the photosensitive drum 12 in close contact, a conductive agent is usually added to the outer periphery of the shaft made of a highly conductive material such as metal. In order to obtain the desired surface roughness, conductivity, hardness, etc. as a basic structure, a structure in which an elastic layer made of conductive rubber, polymer elastomer, polymer foam, etc., to which conductivity has been imparted by The thing provided with the coating film of one layer or multiple layers is used.

  As an improved technique related to such a developing roller, for example, Patent Document 1 discloses a conductive roll in which a conductive rubber member made of a rubber-like elastic body containing at least one ionic liquid as a conductive agent is provided around a core member. A conductive roll is disclosed wherein the ionic liquid comprises a cation selected from a predetermined group.

Japanese Patent No. 4193193 (claims, etc.)

  However, a resistance region of 4 to 8 LogΩ · cm cannot be realized only by adding an ionic conductive agent to a polymer material such as urethane resin or rubber constituting the surface layer of the roller. If conductive carbon or a blend of conductive carbon and ionic conductive agent is used, it is possible to realize a resistance region of 4 to 8 LogΩ · cm. However, in this case, the percolation curve is tight, so that 4 to 8 LogΩ. There is a problem that resistance control in the resistance region of cm is difficult and resistance variation is large. In addition, a solid ionic conductive agent has low ionization in a polymer material, and ions are difficult to move. As a result, the movement of the charge is slowed down, the charge accumulates on the surface of the developing roller, and the toner moves excessively from the roller surface onto the photosensitive drum, thereby causing an image such as ghost, fogging, and gradation deterioration. There was a case where a malfunction occurred.

  Accordingly, an object of the present invention is to provide a technique for solving the above-described problems and realizing a low resistance of about 4 to 8 LogΩ · cm while suppressing variation in resistance in the developing roller. An object of the present invention is to provide a developing roller that has a fast surface potential decay rate and that does not cause image defects due to charge accumulation.

  As a result of intensive studies, the present inventors have determined that, in a developing roller having at least two elastic layers and a coating layer on the outer periphery of the shaft, an ionic liquid is added to at least one of the coating layers in a predetermined amount. It discovered that the said subject could be solved by mix | blending, and came to complete this invention.

That is, the present invention is a developing roller comprising a shaft, an elastic layer carried on the outer periphery of the shaft, and at least one coating layer formed on the outer peripheral surface of the elastic layer.
The elastic layer and the coating layer contain a resin component having a urethane bond, and the coating layer is a surface coating layer provided on the outermost surface, and between the surface coating layer and the elastic layer. Having at least two intermediate coating layers provided in
The intermediate coating layer consists only of a resin component, an ionic liquid and conductive carbon,
The surface coating layer contains a resin component, an ionic liquid, conductive carbon and fine particles,
Each of the intermediate coating layer and the surface coating layer contains 0.1 to 2.5 parts by mass of the ionic liquid with respect to 100 parts by mass of the resin component.

  In the present invention, the ionic liquid is preferably contained in all of the elastic layer and the coating layer. Moreover, it is preferable that the coating-film layer containing the said ionic liquid contains 1-10 mass parts of conductive carbon with respect to 100 mass parts of resin components.

  According to the present invention, with the above-described configuration, it is possible to obtain a resistance of about 4 to 8 Log Ω · cm while suppressing variation in resistance in the developing roller. Thus, it is possible to realize a developing roller that does not cause image defects due to the accumulation of toner.

It is a longitudinal direction sectional view showing an example of a developing roller of the present invention. It is the schematic which shows one structural example of the image development apparatus using a pressure development method.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an example of the developing roller of the present invention. As shown in the figure, the developing roller 10 of the present invention includes a shaft 1, an elastic layer 2 carried on the outer periphery thereof, at least one layer formed on the outer peripheral surface of the elastic layer 2, and in the illustrated example, an intermediate coating layer 3. And two coating layers consisting of the surface coating layer 4.

  In the present invention, at least one of the coating layers contains the ionic liquid in an amount of 0.1 to 2.5 parts by weight, preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the resin component. The point is important. The ionic liquid has a large ionization constant and high mobility compared to a normal solid ionic conductive agent, so the surface of the coating layer is blended with an ionic liquid instead of a solid ionic conductive agent. It has become possible to realize a developing roller that has a fast potential decay rate, does not cause image defects due to charge accumulation on the roller surface, and can cope with high speed printers. Also, by blending an ionic liquid into the paint of the coating layer, the conductive percolation curve is alleviated and resistance variation is reduced, while a desired low resistance is achieved in a resistance region of about 4 to 8 LogΩ · cm. Can be realized. In the present invention, the ionic liquid is added to the coating film layer because it is difficult to reduce the resistance with the conventional solid ionic conductive agent, and the ionic liquid is added to the coating film layer having a high resin resistance for adjusting the resistance. This is because the effect of lowering the resistance and speeding up the surface potential attenuation can be obtained.

If the blending amount of the ionic liquid is less than 0.1 parts by mass, sufficient conductivity cannot be imparted, while if it exceeds 2.5 parts by mass, bleeding out is a concern. Examples of the ionic liquid used in the present invention include pyridinium-based, imidazolium-based, alicyclic amine-based, and aliphatic amine-based cations, (CF ₂ SO ₂ ) ₂ N ⁻ , and (CF ₂ SO ₃ ) ^−. , (FSO ₂ ) ₂ N ⁻ , BF ₄ ⁻ , and PF ₆ ⁻ anions can be used, and one or more of them can be appropriately mixed and used.

  In the developing roller of the present invention, only the point that the ionized liquid is blended into at least one of the coating layers in the predetermined amount is important, and thereby the desired effect of the present invention can be obtained. It is. The specific configuration of the other rollers and the constituent materials of each layer can be appropriately selected according to a conventional method, and are not particularly limited.

  The shaft 1 is not particularly limited as long as it has good conductivity, and any one can be used. For example, a steel material such as sulfur free-cutting steel plated with nickel or zinc, A metal shaft such as a metal core made of solid metal such as iron, stainless steel, or aluminum, or a metal cylinder hollowed out inside can be used.

  The elastic layer 2 can be formed of rubber, resin, or a foam thereof according to the use of the roller. Specifically, for example, polyurethane, silicone rubber, butadiene rubber, isoprene rubber, chloroprene. Examples of the rubber composition include rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber, and the like, and foams thereof.

  In the present invention, it is particularly preferable to use polyurethane foam. The raw material for forming such a polyurethane foam is not particularly limited as long as it contains a urethane bond in the resin.

  Examples of the polyol component include polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide, polytetramethylene ether glycol, polyester polyol obtained by condensing an acid component and a glycol component, polyester polyol obtained by ring-opening polymerization of caprolactone, polycarbonate diol, and the like. Can be used.

  Examples of polyether polyols obtained by addition polymerization of ethylene oxide and propylene oxide include water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, ethylenediamine, and methylglucotite. , Aromatic diamine, sorbitol, sucrose, phosphoric acid, etc. as starting materials, and those obtained by addition polymerization of ethylene oxide and propylene oxide. Particularly, water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane. Those starting from hexanetriol are preferred. As for the ratio of ethylene oxide and propylene oxide to be added and the microstructure, the ratio of ethylene oxide is preferably 2 to 95% by mass, more preferably 5 to 90% by mass, and ethylene oxide is added to the terminal. preferable. In addition, the arrangement of ethylene oxide and propylene oxide in the molecular chain is preferably random.

  The molecular weight of the polyether polyol is bifunctional when water, propylene glycol, or ethylene glycol is used as a starting material, and preferably has a weight average molecular weight in the range of 300 to 6000, preferably in the range of 400 to 3000. Is more preferable. Further, when glycerin, trimethylolpropane, and hexanetriol are used as starting materials, they are trifunctional, and those having a weight average molecular weight in the range of 900 to 9000 are preferable, and those in the range of 1500 to 6000 are more preferable. Furthermore, a bifunctional polyol and a trifunctional polyol can be appropriately blended and used.

  Polytetramethylene ether glycol can be obtained, for example, by cationic polymerization of tetrahydrofuran, and those having a weight average molecular weight in the range of 400 to 4000, particularly in the range of 650 to 3000 are preferably used. It is also preferable to blend polytetramethylene ether glycols having different molecular weights. Furthermore, polytetramethylene ether glycol obtained by copolymerizing an alkylene oxide such as ethylene oxide or propylene oxide can also be used.

  Further, it is also preferable to use a blend of polytetramethylene ether glycol and a polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide. In this case, it is preferable to use such a blend ratio so that the weight ratio is in the range of 95: 5 to 20:80, particularly 90:10 to 50:50.

  In addition to the polyol component, a polymer polyol obtained by modifying the polyol with acrylonitrile, a polyol obtained by adding melamine to the polyol, a diol such as butanediol, a polyol such as trimethylolpropane, or a derivative thereof may be used in combination.

  Moreover, as an isocyanate component which comprises a polyurethane foam, aromatic isocyanate or its derivative (s), aliphatic isocyanate or its derivative (s), alicyclic isocyanate or its derivative (s) is used. Among these, aromatic isocyanate or a derivative thereof is preferable, and tolylene diisocyanate (TDI) or a derivative thereof, diphenylmethane diisocyanate (MDI) or a derivative thereof is particularly preferably used.

  Tolylene diisocyanate or derivatives thereof include crude tolylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, these These are urea-modified products, burette-modified products, carbodiimide-modified products, urethane-modified products modified with polyols, and the like. As diphenylmethane diisocyanate or a derivative thereof, for example, diphenylmethane diisocyanate or a derivative thereof obtained by phosgenating diaminodiphenylmethane or a derivative thereof is used. Examples of the derivatives of diaminodiphenylmethane include polynuclear bodies, and pure diphenylmethane diisocyanate obtained from diaminodiphenylmethane, polymeric diphenylmethane diisocyanate obtained from a polynuclear body of diaminodiphenylmethane, and the like can be used. Regarding the number of functional groups of polymeric diphenylmethane diisocyanate, a mixture of pure diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate having various functional groups is usually used, and the average number of functional groups is preferably 2.05 to 4.00, more preferably 2. .50 to 3.50 are used. Derivatives obtained by modifying these diphenylmethane diisocyanates or their derivatives, such as urethane-modified products modified with polyols, dimers formed by uretidione formation, isocyanurate-modified products, carbodiimide / uretonimine-modified products, allophanate-modified products , Urea-modified products, burette-modified products, and the like can also be used. Also, several types of diphenylmethane diisocyanate and its derivatives can be blended and used.

  In addition, the isocyanate may be prepolymerized with a polyol in advance. As a method for this, the polyol and the isocyanate are put in a suitable container and sufficiently stirred, and 30 to 90 ° C, more preferably 40 to 70 ° C, A method of keeping the temperature for 240 hours, more preferably 24 to 72 hours can be mentioned. In this case, the ratio of the amount of polyol and isocyanate is preferably adjusted so that the isocyanate content of the resulting prepolymer is 4 to 30% by mass, more preferably 6 to 15% by mass. If the isocyanate content is less than 4% by mass, the stability of the prepolymer is impaired, and the prepolymer may be cured during storage, making it impossible to use. Further, when the isocyanate content exceeds 30% by mass, the content of isocyanate that has not been prepolymerized increases, and this polyisocyanate undergoes a prepolymerization reaction with a polyol component used in the subsequent polyurethane curing reaction. The effect of using the prepolymer method is diminished because it cures by a reaction mechanism similar to the one-shot process. In the case of using an isocyanate component in which isocyanate is prepolymerized with a polyol in advance, in addition to the above polyol component, diols such as ethylene glycol and butanediol, polyols such as trimethylolpropane and sorbitol, and derivatives thereof Can also be used.

  In polyurethane foam raw materials, in addition to these polyol component and isocyanate component, conductive agent and foaming agent (water, low-boiling substances, gas bodies, etc.), cross-linking agent, surfactant, catalyst, foam stabilizer, as desired. Etc. can be added, and it can be set as the elastic layer as desired by this.

  Examples of the ionic conductive agent include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (eg, lauryltrimethylammonium), hexadecyltrimethylammonium, and octadecyltrimethylammonium. (Eg stearyltrimethylammonium), benzyltrimethylammonium, modified fatty acid dimethylethylammonium perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, ethyl sulfate Ammonium salts such as salts, carboxylates and sulfonates, perchlorates, chlorates, hydrochlorides and bromates of alkali metals and alkaline earth metals such as lithium, sodium, potassium, calcium and magnesium Iodates, fluoroboric acid salts, trifluoromethyl sulfate, and sulfonic acid salts. Examples of the electronic conductive agent include conductive carbon such as ketjen black and acetylene black; carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; for ink subjected to oxidation treatment Examples thereof include carbon, pyrolytic carbon, natural graphite, and artificial graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; metals such as nickel, copper, silver, and germanium. These conductive agents may be used alone or in combination of two or more. Moreover, there is no restriction | limiting in particular in the compounding quantity, Although it can select suitably as desired, For example, it can be set as 1-20 mass parts with respect to 100 mass parts of resin components which comprise an elastic layer.

  Catalysts used for the polyurethane foam curing reaction include monoamines such as triethylamine and dimethylcyclohexylamine, diamines such as tetramethylethylenediamine, tetramethylpropanediamine, and tetramethylhexanediamine, pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, tetra Triamines such as methylguanidine, triethylenediamine, dimethylpiperazine, methylethylpiperazine, cyclic amines such as methylmorpholine, dimethylaminoethylmorpholine, dimethylimidazole, dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxy Alcohol amines such as ethyl piperazine and hydroxyethyl morpholine Ether amines such as bis (dimethylaminoethyl) ether and ethylene glycol bis (dimethyl) aminopropyl ether, stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker peptide, dibutyltin thiocarboxylate, dibutyltin dimaleate And organometallic compounds such as dioctyltin marker peptide, dioctyltin thiocarboxylate, phenylmercury propionate and lead octenoate. These catalysts may be used alone or in combination of two or more.

  In the present invention, it is preferable to blend a silicone foam stabilizer and various surfactants during blending of the polyurethane foam in order to stabilize the cells of the foam material. As the silicone foam stabilizer, a dimethylpolysiloxane-polyoxyalkylene copolymer or the like is suitably used, and those composed of a dimethylpolysiloxane moiety having a molecular weight of 350 to 15000 and a polyoxyalkylene moiety having a molecular weight of 200 to 4000 are particularly preferable. . The molecular structure of the polyoxyalkylene moiety is preferably an addition polymer of ethylene oxide or a co-addition polymer of ethylene oxide and propylene oxide, and its molecular terminal is preferably ethylene oxide. Examples of the surfactant include cationic surfactants, anionic surfactants, ionic surfactants such as amphoteric, nonionic surfactants such as various polyethers and various polyesters. These may be used alone or in combination of two or more. The blending amount of the silicone foam stabilizer and various surfactants is preferably 0.1 to 10 parts by mass, and 0.5 to 5 parts by mass with respect to 100 parts by mass of the total amount of the polyol component and the isocyanate component. More preferably.

  As a foaming method of the polyurethane foam raw material in the present invention, conventionally used methods such as a mechanical froth method, a water foaming method, and a foaming agent froth method can be used. In particular, while mixing an inert gas. It is preferable to use a mechanical floss method in which foaming is performed by mechanical stirring. Here, the inert gas used in the mechanical froth method may be an inert gas in the polyurethane reaction, and in addition to inert gases in a narrow sense such as helium, argon, xenon, radon, krypton, nitrogen, carbon dioxide, drying The gas which does not react with urethane foam raw materials, such as air, is mentioned. In the present invention, the molding conditions for the elastic layer made of such polyurethane foam raw material are not particularly limited, and may be according to ordinary conditions.

  In order to adjust the roller physical properties, the coating layer needs to be provided on the elastic layer 2 in at least one layer, preferably two or more layers, more preferably two to three layers. Can do. Specifically, for example, as shown in the figure, two layers of an intermediate coating layer 3 and a surface coating layer 4 can be sequentially provided on the elastic layer 2, and three or more coating layers are provided. In this case, the intermediate coating layer may be two or more layers.

  In the present invention, the coating layer can be formed of various solvent-based paints such as urethane, acrylic, acrylurethane, and fluorine. Particularly, the surface coating layer forming the roller surface is urethane, acrylic. The surface roughness can be adjusted by adding fine particles made of silica or the like.

  In the present invention, it is necessary that at least one of the coating layers contains the ionic liquid, and the coating layer further includes the above-described ionic conductive agent or electronic conductivity as a conductive agent. An agent can be appropriately contained, and a vulcanizing agent, a vulcanization accelerator, an antiaging agent, and the like can be appropriately added as desired. Preferably, the coating layer containing the ionic liquid further contains conductive carbon at 1 to 10 parts by mass, preferably 1 to 5 parts by mass with respect to 100 parts by mass of the resin component. By blending an ionic liquid with a high ionization constant and high mobility with conductive carbon, the ionic liquid has high conductivity before the conductive path of conductive carbon is made. The percolation curve can be made gentler. Thereby, compared with the case of the blend of a solid ionic conductive agent and conductive carbon, a wide resistance control and reduction of resistance variation can be aimed at.

  The coating layer is coated on the elastic layer 2 using a known method such as dip coating, spray coating, roll coater coating, etc., dried, and then heat-cured as desired. Can be formed.

  In the present invention, the thickness of the elastic layer 2 is not particularly limited, but can usually be in the range of 1 to 7 mm. Moreover, the total thickness of a middle layer coating-film layer can be normally made into the range of 10-100 micrometers, and the thickness of a surface layer coating-film layer can be normally made into the range of 5-50 micrometers. In addition, as surface roughness of a surface layer coating-film layer, it is JIS arithmetic average roughness Ra, and can usually be in the range of 2 micrometers or less, especially 0.5-1.5 micrometers.

Hereinafter, the present invention will be described in more detail with reference to examples.
10 parts by mass of an ether polyol (Asahi Glass Co., Ltd., EL430), 12 parts by mass of an ester polyol (Kuraray Co., Ltd., F510), and 3 parts of a foam stabilizer (manufactured by Toray Dow Corning Co., Ltd., SF2937F) Part, a polyol component containing 0.05 parts by mass of a catalyst (manufactured by Nitto Kasei Co., Ltd., U-100) and an ionic conductive agent shown in the following table, and a prepolymerized TDI (manufactured by Asahi Glass Co., Ltd.) , Prototype) An isocyanate component blended with 100 parts by mass and conductive carbon shown in the table below was mixed, foamed by a mechanical floss method, and injected into a mold on which a metal shaft was set. Thereafter, this mixture was heated and cured at 105 ° C. for 40 minutes to form an elastic layer having a thickness of 6 mm on the outer periphery of the metal shaft.

  100 parts by mass of prepolymerized TDI (Asahi Glass Co., Ltd., prototype), 18 parts by mass of an ether polyol (Asahi Glass Co., Ltd., EL430), 200 parts by mass of methyl ethyl ketone (MEK), and shown in the table below A paint containing conductive carbon and an ionic conductive agent was prepared. This paint was applied onto the elastic layer by dipping and dried at 105 ° C. for 200 minutes to form an intermediate coating layer having a thickness of 20 μm.

  55 parts by mass of isocyanurated HDI (manufactured by Nippon Polyurethane Industry Co., Ltd., HX), 100 parts by mass of polytetramethylene glycol (manufactured by Hodogaya Chemical Co., Ltd., PTG1000), and acrylic particles (manufactured by Toyobo Co., Ltd., FH) -S010) A paint in which 15 parts by mass, 3 parts by mass of silica (manufactured by Tosoh Silica Co., Ltd., SS-20), an ion conductive agent and conductive carbon shown in the following table, and 150 parts by mass of MEK are blended. Prepared. This paint was applied onto the intermediate coating layer by dipping and dried at 105 ° C. for 120 minutes to form a surface coating layer having a thickness of 18 μm.

  Moreover, using the coating material for forming each layer, a sheet-like sample of 80 mm × 150 mm × 0.2 mm was prepared, resistance measurement was performed, and the volume resistivity was converted. The resistance variation was calculated based on a value obtained by measuring the resistance of three rollers and converting to volume resistivity. The attenuation of the surface potential was measured using a CRT2000 manufactured by QEA, and the time from the initial surface potential to a value of 1 / e was measured to obtain a relaxation time τ. These results are also shown in Table 1 below. Table 2 below shows specific examples of ionic liquids that can be used in the present invention.

＊１）イオン性液体（下記表２参照）
＊２）花王（株）製，脂肪族第四級アンモニウムサルフェート
＊３）電気化学工業（株）製，アセチレンブラック
＊４）三菱化学（株）製カーボンブラックＭＡ１００をＭＥＫに分散させたもの（カーボン含有量３０％）。

* 1) Ionic liquid (See Table 2 below)
* 2) Kao Corporation, aliphatic quaternary ammonium sulfate * 3) Denki Kagaku Kogyo Co., Ltd., acetylene black * 4) Carbon black MA100 made by Mitsubishi Chemical Corporation dispersed in MEK (carbon Content 30%).

＊５）日本カーリット（株）製
＊６）第一工業製薬（株）製
＊７）広栄化学工業（株）製

* 5) Nippon Carlit Co., Ltd. * 6) Daiichi Kogyo Seiyaku Co., Ltd. * 7) Koei Chemical Co., Ltd.

  As shown in the above table, by including an ionic liquid in the coating layer, it is possible to achieve a resistance of about 4 to 8 Log Ω · cm while suppressing variation in resistance in the developing roller. It was confirmed that a developing roller having a high surface potential decay rate and no image defects caused by charge accumulation can be obtained.

DESCRIPTION OF SYMBOLS 1 Shaft 2 Elastic layer 3 Middle layer coating layer 4 Surface layer coating layer 10 Developing roller

Claims (3)

In a developing roller comprising a shaft, an elastic layer carried on the outer periphery of the shaft, and at least one coating layer formed on the outer peripheral surface of the elastic layer,
The elastic layer and the coating layer contain a resin component having a urethane bond , and the coating layer is a surface coating layer provided on the outermost surface, and between the surface coating layer and the elastic layer. Having at least two intermediate coating layers provided in
The intermediate coating layer consists only of a resin component, an ionic liquid and conductive carbon,
The surface coating layer contains a resin component, an ionic liquid, conductive carbon and fine particles,
The developing roller, wherein each of the intermediate coating layer and the surface coating layer contains 0.1 to 2.5 parts by mass of an ionic liquid with respect to 100 parts by mass of the resin component. Wherein the ionic liquid, the elastic layer and the coating layer of the developing roller according to claim 1, wherein it contains all. The developing roller according to claim 1 or 2, wherein the coating layer containing the ionic liquid contains 1 to 10 parts by mass of conductive carbon with respect to 100 parts by mass of the resin component.

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