JP2009025418A - Conductive roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller that is free from bleed even in a high temperature/high humidity environment and is electrically stable and also to provide a conductive roller that is free from the problem of hindrance to curing, especially even in the case of use of a UV curable resin as a resin material for a coating film layer. <P>SOLUTION: The conductive roller has: a shaft 1; an elastic layer 2 held on the periphery of the shaft 1; at least one coating film layer 3 formed on the peripheral face of the elastic layer 2. Of the coating film layers, at least the coating film layer 3 serving as the outermost layer contains: a ultraviolet curable resin as a resin component and; a silica satisfying condition (1) the content of Na<SB>2</SB>O is more than or equal to 1% by mass or/and condition (2) in which the content of Al<SB>2</SB>O<SB>3</SB>is equal to or 1% by mass. The content of silica is in the range of 20 to 100 parts by mass based on 100 parts by mass of the resin component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a conductive roller (hereinafter also simply referred to as “roller”), and more particularly to a conductive roller used in various electrophotographic apparatuses such as a copying machine and a printer.

  Conventionally, in an image forming apparatus using an electrophotographic method such as a copying machine or a printer, the surface of the photosensitive member is uniformly charged, and an image is projected onto the photosensitive member from the optical system, and the charged portion is erased. Thus, a method is used in which a latent image is formed, and then this electrostatic latent image is developed and transferred for printing.

In this electrophotographic process, the charging roller used for charging the photosensitive member is generally made of solid rubber, foam rubber, resin material, or the like on the outer peripheral surface of a predetermined conductive shaft that is a conductor. A semiconductive elastic layer having a relatively low resistance region (10 ² to 10 ⁶ Ω) is provided, and a coating layer for adjusting the resistance of the medium resistance region (10 ⁷ to 10 ¹⁰ Ω) is further provided on the outer peripheral surface thereof. The formed configuration is generally adopted.

A typical conductive agent used for the purpose of adjusting the roller resistance includes, for example, carbon black. Further, for example, in Patent Document 1, an electronic conductive agent such as carbon black and an ionic conductive agent are used as a usable conductive agent when the resin coating layer of the developing roller is formed of an ultraviolet curable resin containing a conductive agent. Both are listed.
JP 2004-240389 A (Claims etc.)

  However, when conductive carbon black such as acetylene black is used for adjusting the roller resistance, there is a problem in that it is difficult to stabilize the resistance value because the resistance value greatly fluctuates with a small amount of addition.

  In addition, when carbon black for rubber such as furnace carbon black is used to reduce resistance, a large amount of addition is required to obtain desired conductivity. In this case, it is necessary to use a dispersing agent in order to uniformly disperse a large amount of carbon black. However, this dispersing agent may bleed in a high temperature and humidity environment, and there is a problem that the photosensitive member is contaminated. It was happening.

  Furthermore, particularly when an ultraviolet (UV) curable resin is used as the resin material of the coating layer, when carbon black is mixed in the coating layer, the ultraviolet light is absorbed on the surface of the coating layer and causes inhibition of curing. Therefore, it is not suitable to use carbon black as a means for obtaining conductivity. Furthermore, it is conceivable to use an ionic conductive agent instead of carbon black. However, even when an ionic conductive agent is added, the problem of bleeding occurs.

  As described above, the conventional method of adjusting the roller resistance using carbon black or an ionic conductive agent does not stably obtain the desired conductivity, and does not cause other problems such as bleeding. The establishment of a technology that enables adjustment of roller resistance has been demanded.

  Accordingly, an object of the present invention is to provide an electrically stable conductive roller that does not cause bleed even in a high-temperature and high-humidity environment. In particular, an ultraviolet curable resin is used as a resin material for a coating layer. An object of the present invention is to provide a conductive roller that does not cause a problem of inhibition of curing even when used.

  As a result of intensive studies, the present inventor used a conductive agent provided with conductivity to silica, and applied it to the coating layer of the roller, so that the problem can occur without causing bleeding or curing inhibition problems. The inventors have found that a conductive roller having a stable conductivity can be obtained, and have completed the present invention.

That is, the conductive roller of the present invention is a conductive 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. ,
Among the coating layers, at least the outermost coating layer is an ultraviolet curable resin as a resin component, and the following (1) and (2):
(1) The content of Na ₂ O is 1% by mass or more,
(2) The content of A1 ₂ O ₃ is 1% by mass or more,
Silica satisfying any one or both of the above conditions, and the content of the silica is in the range of 20 to 100 parts by mass with respect to 100 parts by mass of the resin component. Is.

In the roller of the present invention, it is preferable to use a urethane resin or an acrylic urethane resin having a polyester skeleton as the ultraviolet curable resin. The silica is preferably the following (3) and (4),
(3) The content of Na ₂ O is 5 to 20% by mass,
(4) The content of A1 ₂ O ₃ is 5 to 20% by mass,
One or both of the conditions are satisfied. Furthermore, in the present invention, the elastic layer is preferably made of a foam, and more preferably, the foam is a urethane foam obtained by foaming a urethane raw material by mechanical stirring.

  According to the present invention, by adopting the above configuration, it is possible to realize an electrically stable conductive roller having desired conductivity without causing problems such as photoconductor contamination and curing inhibition due to bleeding. It has become possible.

Hereinafter, preferred embodiments of the present invention will be described in detail.
FIG. 1 is a cross-sectional view in the width direction of an example of the conductive roller of the present invention. As shown in the drawing, the conductive 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 example shown, one layer. A coating layer 3.

In the present invention, the coating layer 3 comprises an ultraviolet curable resin as a resin component and the following (1) and (2),
(1) The content of Na ₂ O is 1% by mass or more,
(2) The content of A1 ₂ O ₃ is 1% by mass or more,
And silica that satisfies one or both of the conditions, and the silica content is in the range of 20 to 100 parts by mass with respect to 100 parts by mass of the resin component.

Silica usually does not have conductivity, but it can be made conductive by containing the Na ₂ O and / or A1 ₂ O ₃ . In the present invention, a silica satisfying the above conditions (1) or (2), particularly (1) and (2), is contained in the coating layer composition so that a desired conductive roller can be obtained. It is possible to impart conductivity. In this case, there is no bleed of pollutants as in the prior art, and silica has a high light transmittance and does not absorb ultraviolet light unlike carbon black, so that there is no problem of inhibiting the curing of the coating layer.

The silica used in the present invention is either or both of the above (1) and (2), preferably the following (3) and (4),
(3) The content of Na ₂ O is 5 to 20% by mass,
(4) The content of A1 ₂ O ₃ is 5 to 20% by mass,
One or both of the conditions are satisfied. When the content of Na ₂ O or A1 ₂ O ₃ is less than 1% by mass, a desired resistance value cannot be obtained. Moreover, when there is too much these content, since the dispersibility of a silica and resin worsens, it is not preferable. Such silica used in the present invention can be easily obtained by externally adding the predetermined conductivity-imparting component to commercially available silica.

Moreover, even if the content of the silica in the coating layer 3 is less than 20 parts by mass with respect to 100 parts by mass of the resin component, a desired resistance value cannot be obtained. It will cause problems such as. In the present invention, the resistance value of the coating layer 3 can be adjusted to, for example, about 10 ⁶ to 10 ⁹ Ω.

  In the conductive roller 10 of the present invention, it is important that the coating layer 3 forming the outermost layer of the roller contains the silica together with the ultraviolet curable resin. Thus, a desired roller resistance value can be obtained without causing any problems. In addition, when two or more coating layers are provided, it is necessary to contain the ultraviolet curable resin and silica in at least the outermost coating layer, but the coating layers other than the outermost layer are also included. It is preferable to have the same configuration as the outermost layer.

  The ultraviolet curable resin used for the coating layer 3 in the present invention is not particularly limited as long as it is a resin that usually contains a prepolymer, a monomer, an ultraviolet polymerization initiator and an additive and is cured by irradiation with ultraviolet light. It can be appropriately selected from those used. Specifically, for example, polyester resin, polyether resin, fluororesin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, melamine resin, urea resin, silicone resin, Polyvinyl butyral resin etc. are mentioned, These 1 type (s) or 2 or more types can be mixed and used. Among these, a urethane resin or an acrylic urethane resin having a polyester skeleton can be preferably used.

  In addition to the ultraviolet curable resin and silica, known additives can be appropriately added to the coating layer 3 as desired. In particular, in order to control the surface properties of the roller, it is preferable to contain fine particles, whereby appropriate fine irregularities can be formed on the surface of the coating layer. As such fine particles, fine particles composed of rubber or synthetic resin, fine particles composed of carbon, inorganic fine particles such as silica-based fine particles can be used. Silicone rubber, silicone resin, fluorine resin, urethane elastomer, polyolefin resin, epoxy resin, Polystyrene resin, urethane acrylate, melamine resin, phenol resin, (meth) acrylic resin, fine particles made of glassy carbon and silica fine particles are particularly preferable. These fine particles may be used alone or in combination of two or more. Further, the content of the fine particles is preferably 0.1 to 100 parts by mass, and more preferably 5 to 80 parts by mass with respect to 100 parts by mass of the resin component of the coating layer. The average particle size of the fine particles is preferably 1 to 50 μm, more preferably 3 to 20 μm.

  Although the total thickness of the coating layer 3 is not particularly limited, it can usually be about 1 to 50 μm, particularly about 1 to 40 μm. Further, the surface roughness of the coating film layer 3, that is, the surface roughness of the roller is preferably JIS arithmetic average roughness Ra, usually 2 μm or less, and particularly preferably in the range of 0.5 to 1.5 μm.

  In addition, the shaft 1 of the conductive roller of the present invention is not particularly limited as long as it has good conductivity, and any one can be used. For example, nickel or other steel materials such as sulfur free-cutting steel can be used. A metal shaft such as a zinc plated metal, a metal core made of a 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, and epichlorohydrin rubber.

  Among them, it is particularly preferable to use polyurethane, and more preferably, a polyurethane foam having an expansion ratio of 1.5 to 50 times is used. 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 and propylene oxide to be added and the microstructure, the ratio of ethylene oxide is preferably 2 to 95 mass%, more preferably 5 to 90 mass%. 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 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 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 polyisocyanate 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 isocyanate does not undergo a prepolymerization reaction with the polyol component used in the subsequent polyurethane curing reaction. Since it cures by a reaction mechanism similar to the one-shot production method, the effect of using the prepolymer method is diminished. 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.

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 mass parts with respect to 100 mass parts of polyurethane raw materials, Preferably 0.3-20 mass parts Thus, the resistance value of the elastic layer 2 can be adjusted to about 10 ⁴ to 10 ⁸ Ω, for example.

  Catalysts used for the curing reaction of polyurethane raw materials 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, dimethylpolysiloxane-polyoxyalkylene copolymer and the like are preferably 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 mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass 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 20 to 65 °, more preferably 25 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 froth method, a water foaming method, or a foaming agent froth method can be used. It is preferable to use a mechanical floss method in which foaming is performed by mechanical stirring while mixing an active gas. 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 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.

  In producing the conductive roller of the present invention, the molding conditions of the elastic layer 2 are not particularly limited, and can follow normal conditions, for example, at a temperature in the range of 15 to 80 ° C., preferably 20 to 65 ° C. The elastic layer 2 can be obtained by starting the foaming of the polyurethane raw material, performing the curing at a temperature of about 70 to 120 ° C. after completing the injection into the metal mold in which the shaft 1 is disposed, and then removing the mold. The coating layer 3 is prepared by preparing a coating solution containing the ultraviolet curable resin and silica, and using this coating solution by a known method such as dip coating, spray coating, roll coater coating, etc. It can be formed by applying to the outer peripheral surface of the substrate and drying it, followed by curing (crosslinking) by ultraviolet irradiation.

The conductive roller of the present invention is not particularly limited, and is preferably 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. The resistance value of the roller of the present invention can be set within the range of 10 ⁶ to 10 ⁹ Ω, particularly 10 ⁷ to 10 ⁸ Ω, by adjusting the resistance values of the elastic layer and the coating layer.

Hereinafter, the present invention will be described in more detail with reference to examples.
As shown in FIG. 1, a conductive roller as a developing roller comprising a shaft 1, an elastic layer 2 carried on the outer periphery thereof, and a single coating layer 3 formed on the outer peripheral surface thereof. 10 were prepared by changing only the composition of the coating layer 3 as shown in Table 1 below.

  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 mass of an isocyanate component (prepolymerized isocyanate TDI + polyether polyol), 20 parts by mass of a polyol component (polyether polyol), 2 parts by mass of carbon black (acetylene black), an ionic conductive agent (peroxide A polyurethane raw material consisting of 0.2 parts by mass 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 coating solution prepared with the formulation shown in Table 1 below was dip coated to form a coating layer 3 having a thickness of 15 μm on the outer periphery. As a result, a developing roller having a roller body of φ16 mm and a length of 240 mm was produced. The surface roughness of the obtained roller was 1.1 μm in terms of JIS arithmetic average roughness Ra.

<Surface hardness>
The surface hardness of each test roller was measured using a micro rubber hardness meter MD-1 (manufactured by Kobunshi Keiki Co., Ltd.). If the roller hardness is 40 to 65 °, it is satisfactory without any problem.

<Roller resistance>
The roller resistance was measured by applying a voltage of 300 V between the shaft and the SUS plate in a state where the load was applied to the SUS plate so that a load of 1 kg was applied to the shaft of each test roller. From the viewpoint of securing the performance as the developing roller, the roller resistance is good without any problem if it is about 10 ⁶ to 10 ⁸ Ω.

<Photoconductor contamination>
Each test roller was pressed against a photosensitive drum (OPC) with a load of 1 kg and left under high temperature and high humidity of 40 ° C. × 95% RH. The roller was taken out after a predetermined period (one week), and images were taken out by assembling each roller into an actual machine.
○: No contamination of the photosensitive drum Δ: Some contamination of the photosensitive drum was observed ×: Bleeding of the photosensitive drum was observed

  These results are also shown in Table 1 below.

＊１）ＵＶ３０００Ｂ：アクリルウレタン樹脂（日本合成化学（株）製）
＊２）ＴＭＰ−３：ＥＯ変性トリメチロールプロパントリアクリレート（日本合成科学（株）製）
＊３）ウレタン粒子：アートパールＣ８００（根上工業（株）製），平均粒径１０μｍ
＊４）光開始剤：ダロキュア−１１７３（チバスペシャリティーケミカルズ（株）製）
＊５）イオン導電剤：ＭＰ１００（四級アンモニウム塩）
＊６）カーボンブラック：アセチレンブラック

* 1) UV3000B: acrylic urethane resin (manufactured by Nippon Synthetic Chemical Co., Ltd.)
* 2) TMP-3: EO-modified trimethylolpropane triacrylate (manufactured by Nippon Synthetic Science Co., Ltd.)
* 3) Urethane particles: Art Pearl C800 (manufactured by Negami Kogyo Co., Ltd.), average particle size 10 μm
* 4) Photoinitiator: Darocur-1173 (manufactured by Ciba Specialty Chemicals)
* 5) Ionic conductive agent: MP100 (quaternary ammonium salt)
* 6) Carbon black: Acetylene black

  As shown in Table 1 above, in the roller of each example in which the coating layer is made to contain the specific silica according to the present invention as the conductive agent together with the ultraviolet curable resin, the problem of the photoreceptor contamination does not occur. It was confirmed that the desired roller resistance was obtained.

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

Explanation of symbols

1 shaft 2 elastic layer 3 coating layer 10 conductive roller

Claims (5)

In a conductive 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,
Among the coating layers, at least the outermost coating layer is an ultraviolet curable resin as a resin component, and the following (1) and (2):
(1) The content of Na ₂ O is 1% by mass or more,
(2) The content of A1 ₂ O ₃ is 1% by mass or more,
Silica satisfying any one or both of the above conditions, and the content of the silica is in the range of 20 to 100 parts by mass with respect to 100 parts by mass of the resin component. Conductive roller.   The conductive roller according to claim 1, wherein the ultraviolet curable resin is made of a urethane resin or an acrylic urethane resin having a polyester skeleton. The silica is the following (3) and (4),
(3) The content of Na ₂ O is 5 to 20% by mass,
(4) The content of A1 ₂ O ₃ is 5 to 20% by mass,
The conductive roller according to claim 1, wherein one or both of the conditions are satisfied.   The conductive roller according to claim 1, wherein the elastic layer is made of a foam.   The conductive roller according to claim 4, wherein the foam is a urethane foam obtained by foaming a urethane raw material by mechanical stirring.

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