JP4678766B2 - Conductive roller - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roller (hereinafter, also simply referred to as “roller”), and more specifically, a roller used for various applications such as development, charging, and transfer (toner supply and cleaning) in an image forming apparatus using an electrophotographic system. The present invention relates to a member, particularly a conductive roller suitable as a developing roller or a charging roller.

  In an image forming apparatus using an electrophotographic system such as a copying machine or a printer, a roller member imparted with conductivity is used in each of electrophotographic processes such as development, charging, and transfer (toner supply and cleaning). .

  Conventionally, as a conductive roller used as a developing roller, a charging roller, a transfer roller (toner supply, cleaning), etc., a conductive material provided with conductivity by adding a conductive agent to the outer periphery of a conductive metal shaft. In order to obtain the desired surface roughness, conductivity, hardness, etc., using a structure in which a conductive elastic layer made of rubber, polymer elastomer, polymer foam, etc. is formed as a basic structure, one or more layers are coated on the outer periphery. A film provided with a film is used.

  Such a conductive roller is usually formed by applying paint to the surface of an elastic layer carried on the outer periphery of a metal shaft. However, when a coating film is formed on the elastic layer, depending on the solvent resistance of the elastic layer, the surface of the elastic layer is dissolved by the solvent contained in the paint. In some cases, roughness could not be ensured.

As a technique for eliminating the influence of the solvent on the elastic layer by providing a coating film using a water-based paint on the elastic layer, for example, Patent Document 1 discloses a technique in which an organic compound is dissolved in an organic solvent. In the composite roller having the surface coating formed on the roller body surface made of an organic compound foam having solubility or swelling with an organic solvent, a coating formed from a mixed solution containing a predetermined organic compound and an aqueous solvent, By providing it between the roller body and the surface coating as a solvent shielding film against the organic solvent contained in the surface coating forming paint, it prevents dissolution and swelling of the roller body by the organic solvent in the coating for forming the surface coating, and provides a smooth surface. A technique for obtaining a composite roller having the same is described. In this composite roller, it is disclosed that the roller body is made of a foam having an open cell structure, vinylidene fluoride is used as the solvent shielding coating, and fluororubber is used as the surface coating.
Japanese Patent No. 2999684 (claims, paragraph [0005], etc.)

  Usually, as described above, in order to ensure solvent shielding by using a water-based paint film, the paint film requires a certain thickness, but on the other hand, if the paint film is too thick, There is a problem that the roller surface becomes hard and desired roller performance cannot be obtained. In this regard, in Patent Document 1, the use of vinylidene fluoride having a high solvent resistance as the solute of the solvent shielding film having adhesiveness to the roller body and the surface film has a thickness of about 3 to 7 μm. The thin film avoids the problem of insufficient flexibility while obtaining a solvent shielding function (paragraph [0012]).

  However, in the above technique, a wide range of materials cannot be selected as the water-based paint, and thus there is a problem that the surface coating material as the surface layer is also limited. Therefore, from the viewpoint of the degree of freedom in roller design, there has been a demand for a technique that can solve the above-described problems while allowing a wider range of materials to be used.

  Accordingly, an object of the present invention is to provide a conductive material that can ensure a desired surface roughness and roller hardness even when the elastic layer does not have sufficient solvent resistance and has a wide range of material selection. It is to provide a sex roller.

  As a result of intensive studies, the present inventor has found that the above-described configuration can solve the above problem, and has completed the present invention.

That is, the developing roller of the present invention is a developing roller comprising a lower conductive layer and a surface resin layer sequentially on an elastic layer.
The elastic layer is made of a foam having a closed cell structure, the lower conductive layer is made of a water-based paint containing a conductive agent, and the thickness of the lower conductive layer is in the range of 10 to 100 μm. Is.

  In the present invention, the lower conductive layer can be formed by dip coating of the water-based paint. The micro-hardness of the lower conductive layer is preferably in the range of 10 to 45 °, and the water-based paint is preferably any one selected from the group consisting of rubber, urethane, and acrylic. Species or two or more. Furthermore, a polyurethane foam can be suitably used as the foam. Furthermore, the surface resin layer preferably contains spherical fine particles.

  According to the present invention, by providing a lower conductive layer made of a water-based paint, even when the elastic layer does not have sufficient solvent resistance, it is possible to prevent the occurrence of a problem such as solvent leakage of the elastic layer, It has become possible to ensure a desired surface roughness and roller hardness, and to realize a conductive roller having a wide range of material selection to some extent.

Hereinafter, preferred embodiments of the present invention will be described in detail.
FIG. 1 shows a cross-sectional view of a conductive roller as an example of the present invention. As shown in the figure, the conductive roller of the present invention comprises a lower conductive layer 3 and a surface resin layer 4 in this order on an elastic layer 2 carried on the outer periphery of the shaft 1.

  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 is a foam having a closed cell structure, and polyurethane foam is preferably used in the present invention. The polyurethane raw material for forming such a polyurethane foam is not particularly limited as long as it contains a urethane bond in the resin. As the polyisocyanate constituting the polyurethane raw material, aromatic isocyanate or a derivative thereof, aliphatic isocyanate or a derivative thereof, alicyclic isocyanate or a derivative thereof is used. Among these, aromatic isocyanate or a derivative thereof is preferable, and tolylene diisocyanate or a derivative thereof, diphenylmethane diisocyanate 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 derivatives thereof, 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.

  Polyol components constituting the polyurethane raw material include polyether polyols obtained by addition polymerization of ethylene oxide and propylene oxide, polytetramethylene ether glycol, polyester polyols obtained by condensing acid components and glycol components, polyester polyols obtained by ring-opening polymerization of caprolactone, Polycarbonate diol or the like can be used. Polyether polyols obtained by addition polymerization of ethylene oxide and propylene oxide are, for example, water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, ethylenediamine, methylglucotite, Examples include aromatic diamines, sorbitol, sucrose, phosphoric acid and the like as starting materials, and addition polymerization of ethylene oxide and propylene oxide. Particularly, water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, Those starting from hexanetriol are preferred. Regarding the ratio of ethylene oxide to propylene oxide to be added and the microstructure, the ratio of ethylene oxide is preferably 2 to 95% by weight, more preferably 5 to 90% by weight. In particular, those having ethylene oxide added to the terminal are preferably used. Further, 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, particularly in the range of 400 to 3000. preferable. Further, when glycerin, trimethylolpropane, and hexanetriol are used as starting materials, they are trifunctional and preferably have a weight average molecular weight in the range of 900 to 9000, particularly preferably in the range of 1500 to 6000. Further, a bifunctional polyol and a trifunctional polyol can be appropriately blended and used.

  Polytetramethylene ether glycol is obtained, for example, by cationic polymerization of tetrahydrofuran, and those having a weight average molecular weight of 400 to 4000, particularly 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 alkylene oxide such as ethylene oxide or propylene oxide can also be used. 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, polytetramethylene ether glycol, addition polymerization of ethylene oxide and propylene oxide was performed. It is preferably used so that the ratio with the polyether polyol is in the range of 95: 5 to 20:80, particularly in the range of 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 can be used in combination.

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

  Addition of conductive agents such as ionic conductive agents and electronic conductive agents, fillers such as carbon black and inorganic carbonates, antioxidants such as phenol and phenylamine, low friction agents, charge control agents, etc. to polyurethane raw materials be able to. Examples of ionic conductive agents include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (eg, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (eg, stearyltrimethylammonium), benzyltrimethylammonium, modified fatty acid dimethylethyl. Perchlorates such as ammonium, chlorates, hydrochlorides, bromates, iodates, borofluorides, sulfates, ethyl sulfates, carboxylates, ammonium salts such as sulfonates, lithium, Perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, trifluoromethyl of alkali metals and alkaline earth metals such as sodium, potassium, calcium and magnesium 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. There is no restriction | limiting in particular in the compounding quantity, Although it can select suitably as desired, Usually, the ratio of 0.1-40 weight part with respect to 100 weight part of polyurethane raw materials, Preferably 0.3-20 weight part It is.

  Catalysts used for curing the polyurethane raw material 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; (Dimethylaminoethyl) ether, ether amines such as ethylene glycol bis (dimethyl) aminopropyl ether, stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker peptide, dibutyltin thiocarboxylate, dibutyltin dimaleate, And organic metal 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 add a silicone foam stabilizer and various surfactants to the polyurethane raw material 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. The blending amount of the silicone foam stabilizer and various surfactants is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the polyurethane raw material. The blending amount of the silicone foam stabilizer and various surfactants is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the polyurethane raw material.

The polyurethane foam used in the present invention preferably has a density of 0.2 to 0.8 g / cm ³ , more preferably 0.3 to 0.6 g / cm ³ . Further, the Asker C hardness of the polyurethane foam is preferably 15 to 70 °, more preferably 15 to 45 °. In the present invention, as a method for foaming the polyurethane raw material in advance, a conventionally used method such as a mechanical floss method, a water foam method, a foaming agent floss method, etc. can be used, but the density is 0.2 to 0. From the viewpoint of obtaining a polyurethane foam having a closed cell structure having an .8 g / cm ³ and Asker C hardness of 20 to 65 °, it is preferable to use a mechanical floss method in which foaming is performed by mechanical stirring while mixing an inert gas. Here, the inert gas used in the mechanical froth method may be an inert gas in the polyurethane reaction. In addition to inert gases in a narrow sense such as helium, argon, xenon, radon, krypton, nitrogen, carbon dioxide, drying Examples thereof include gases that do not react with polyurethane raw materials such as air. A polyurethane foam in which a self-skin layer (thin layered film) is formed on a portion in contact with the metal mold can be obtained by casting the foamed polyurethane material into a metal mold or the like and curing it. At that time, the moldability can be imparted to the metal mold by a method such as coating the inner surface of the metal mold with a fluororesin or the like.

  Moreover, there is no restriction | limiting in particular about the shaping | molding conditions of the elastic layer 2, It can follow a normal condition, For example, foaming of a polyurethane raw material is started at the temperature of 15-80 degreeC, Preferably it is the range of 20-65 degreeC, A shaft The elastic layer 2 can be obtained by performing curing at a temperature of about 70 to 120 ° C. and then removing the mold after completing the injection into the metal mold in which 1 is disposed.

  The lower conductive layer 3 is composed of a water-based paint containing a conductive agent. As the water-based paint, any one or two or more selected from the group consisting of rubber-based, urethane-based, and acrylic-based materials is preferably used. it can. As rubber type, natural rubber (NR), chloroprene rubber (CR), nitrile rubber (NBR), latex such as styrene butadiene rubber (SBR), etc., as urethane type, emulsion and dispersion such as ether type, ester type, As the acrylic, an emulsion such as acrylic or acrylic styrene can be suitably used. Moreover, as a electrically conductive agent contained in these, the thing similar to what was mentioned previously about the elastic layer 2 can be used, and it does not restrict | limit in particular. In the lower conductive layer 3, other vulcanizing agents, vulcanization accelerators, anti-aging agents, and the like can be appropriately added as desired.

  Moreover, the thickness of the lower conductive layer 3 needs to be 10 to 100 μm, and particularly within the range of 30 to 80 μm. When the thickness is less than 10 μm, the solvent shielding effect on the elastic layer and the prevention effect of preventing the contaminant from seeping out from the lower layer side are insufficient, and the desired surface roughness cannot be imparted by the solvent dripping. On the other hand, if the thickness exceeds 100 μm, the lower conductive layer 3 cannot follow the softness of the elastic layer 2 and is cracked, peeled off, etc., and the roller itself becomes hard, and in terms of roller performance such as toner damage. Problems also occur.

  The lower conductive layer 3 can be formed of one layer or two or more layers by applying the water-based paint on the elastic layer 2. The coating method is not particularly limited, and known methods such as dip coating, spray coating, and roll coater coating can be used, but dip coating is preferably used. In the roller main body made of the foam having an open cell structure as described in Patent Document 1 described above, since the water-based paint penetrates into the inside of the cell, a smooth coating film cannot be formed by dip coating. Since the elastic layer 2 according to the invention has a closed cell structure, a smooth coating film can be formed even by dip coating.

  The micro hardness of the lower conductive layer 3 is preferably in the range of 10 to 45 ° in the case of a film thickness of 500 μm. With this degree of hardness, the desired roller surface can be obtained finally. The roller hardness can be realized. Such micro hardness can be measured by, for example, a micro rubber hardness meter MD-1 type.

  The surface resin layer 4 can be formed with a solvent-based paint such as urethane, acrylic, acrylurethane, or fluorine, and the surface roughness is adjusted by containing spherical fine particles such as urethane, acrylic, and silica. can do. The surface roughness of the surface resin layer 4 is JIS arithmetic average roughness Ra, and is usually 2 μm or less, particularly preferably in the range of 0.5 to 1.5 μm. Moreover, desired electroconductivity can be provided by containing suitably the ionic conductive agent and electronic conductive agent which were mentioned above as a electrically conductive agent. The thickness of the surface resin layer 4 is not particularly limited, but is usually 1 to 50 μm, particularly about 1 to 40 μm.

  The conductive roller of the present invention is not particularly limited, and can be suitably used as various roller members such as a developing roller, a charging roller, and a transfer roller (toner supply roller, cleaning roller) in an electrophotographic image forming apparatus. In particular, it is useful as a developing roller or a charging roller.

Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
First, polyurethane foam was supported on the outer periphery of a core metal 1 (φ8 mm, length 260 mm, material: sulfur free-cutting steel) by a mechanical floss method.

  Specifically, 100 parts by weight of an isocyanate component (prepolymerized isocyanate TDI + polyether polyol), 20 parts by weight of a polyol component (polyether polyol), 2 parts by weight of carbon black (acetylene black), an ionic conductive agent (peroxide A polyurethane raw material consisting of 0.2 parts by weight of sodium chlorate) was prepared, and this polyurethane raw material was mechanically stirred by a mixer and mixed with dry air to be foamed. This polyurethane foam raw material was cast into a metal cylindrical split mold in which a hole for penetrating the shaft was provided at the end, and a metal cap for supporting the shaft was installed. Inside the mold, the core metal 1 was disposed in a state where an adhesive was applied to the outer periphery. Next, the mold in which the foamed polyurethane raw material was cast was left in a hot air oven adjusted to 110 ° C. for 1 hour to cure the foamed polyurethane raw material.

The cured polyurethane foam was removed from the mold, and a CR rubber latex paint blended with carbon black (Ketjen black) was applied by dip coating to form a lower conductive layer 3 having a thickness of 60 μm on the outer periphery of the elastic layer 2. Next, the surface resin layer 4 having a film thickness of 15 μm is formed by dip-coating a polyurethane solvent-based paint containing D ⁵⁰ = 10 μm spherical polyurethane particles and carbon black (acetylene black). A conductive roller having a diameter of 16 mm and a length of 240 mm was produced. The surface roughness of the obtained roller was 0.6 to 0.9 μm in terms of JIS arithmetic average roughness Ra.

Example 2
In the same manner as in Example 1, except that an acrylic solvent-based paint in which spherical polyurethane particles of D ⁵⁰ = 10 μm and carbon black (acetylene black) were used as the paint for forming the surface resin layer 4 was used. Was made. The surface roughness of the obtained roller was 0.6 to 0.9 μm in terms of JIS arithmetic average roughness Ra.

Example 3
Example except that a urethane-based emulsion paint containing a polyether-based polyurethane as a main component and carbon black (Ketjen Black) and an ionic conductive agent (quaternary ammonium salt) was used as a paint for forming the lower conductive layer 3 In the same manner as in Example 1, a conductive roller was produced. The surface roughness of the obtained roller was 0.6 to 0.9 μm in terms of JIS arithmetic average roughness Ra.

Example 4
In the same manner as in Example 3, except that an acrylic solvent-based paint in which spherical polyurethane particles of D ⁵⁰ = 10 μm and carbon black (acetylene black) were used as the paint for forming the surface resin layer 4 was used. Was made. The surface roughness of the obtained roller was 0.6 to 0.9 μm in terms of JIS arithmetic average roughness Ra.

Example 5
A conductive roller was produced in the same manner as in Example 1 except that an acrylic emulsion paint blended with carbon black (Ketjen black) was used as a paint for forming the lower conductive layer 3. The surface roughness of the obtained roller was 0.6 to 0.9 μm in terms of JIS arithmetic average roughness Ra.

Example 6
In the same manner as in Example 5, except that an acrylic solvent-based paint in which spherical polyurethane particles with D ⁵⁰ = 10 μm and carbon black (acetylene black) were used as the paint for forming the surface resin layer 4 was used. Was made. The surface roughness of the obtained roller was 0.6 to 0.9 μm in terms of JIS arithmetic average roughness Ra.

Comparative Example As a paint for forming the lower conductive layer 3, a urethane emulsion paint blended with carbon black (Ketjen Black) was used, and the film thickness of the lower conductive layer 3 was set to 8 μm. A conductive roller was produced. Although the surface roughness of the obtained roller was 0.6 to 0.9 μm in terms of JIS arithmetic average roughness Ra, uniform surface roughness control could not be performed due to solvent dripping with the paint of the surface resin layer 4.

  The micro hardness of the conductive roller obtained in each Example and Comparative Example up to the lower conductive layer 3 and the micro hardness of the final roller were measured using a micro rubber hardness meter MD-1. The results are shown in Table 1 below. Further, each conductive roller was mounted on a printer cartridge as a developing roller, an image printing test was performed with Laserjet 4050 manufactured by Hewlett-Packard, and the result was evaluated for image unevenness. Good ones were marked with ○, and ones with image unevenness were marked with ×. The results are also shown in Table 1 below.

  As shown in Table 1 above, in the rollers of Examples 1 to 6, good hardness is obtained both when the lower conductive layer 3 is formed and finally obtained. As a result, it was confirmed that the desired roller hardness was obtained until the lower conductive layer 3 was formed. On the other hand, the roller of the comparative example has high hardness both in the formation of the lower conductive layer 3 and in the finally obtained roller, and image defects have occurred due to the solvent.

It is sectional drawing of the electroconductive roller which concerns on one embodiment of this invention.

Explanation of symbols

1 Shaft 2 Elastic layer 3 Lower conductive layer 4 Surface resin layer

Claims (6)

In the developing roller comprising the lower conductive layer and the surface resin layer sequentially on the elastic layer,
The elastic layer is made of a foam having a closed cell structure, the lower conductive layer is made of a water-based paint containing a conductive agent, and the thickness of the lower conductive layer is in the range of 10 to 100 μm. Development roller . The developing roller according to claim 1, wherein the lower conductive layer is formed by dip coating of the water-based paint. The developing roller according to claim 1 or 2, wherein the lower conductive layer has a micro hardness in a range of 10 to 45 °. The developing roller according to any one of claims 1 to 3, wherein the water-based paint is one or more selected from the group consisting of rubber, urethane, and acrylic. The developing roller according to claim 1, wherein the foam is polyurethane foam. The developing roller according to claim 1, wherein the surface resin layer contains spherical fine particles.

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