JP4194533B2 - Developing roller and image forming apparatus using the same - Google Patents

Description

The present invention relates to a developing roller, and more specifically, mainly in an apparatus (hereinafter, collectively referred to as an electrophotographic apparatus) that employs an electrophotographic system for image formation, such as a receiving apparatus such as a copying machine, a printer, or a facsimile. developing roller for use in, and to a developing device and an image forming apparatus using the developing roller.

  In an electrophotographic apparatus using an electrophotographic system for image formation, such as a copying machine, a facsimile machine, and a printer, an elastic roller suitable for various purposes is used in the image forming process. For example, in a one-component development type electrophotographic apparatus, a process in which an electrostatic latent image formed on a surface of a photoreceptor is visualized with a developer, that is, in a development process, a developer carrying a developer on the surface is developed. A method is used in which a developer is moved by bringing a roller into pressure contact with a surface of a photoreceptor as a latent image carrier. The elastic layer of the developing roller used in this step needs to press the elastic member with a predetermined contact width against the photosensitive member, is easily deformed, and at the same time has excellent deformation recovery (set recovery), and What has low surface characteristics (hereinafter referred to as adhesion) required for the developer to adhere to the roller surface is desired. In addition, the elastic layer on the surface of the developing roller is easily deformed even when the developer supplied in the developing unit is thinly carried on the elastic layer using a blade that contacts the surface layer of the developing roller. In addition, it is necessary to have excellent deformation recovery properties, and it is difficult for the developer to adhere to the surface of the developing roller.

  In addition, in the image forming process, as an elastic roller that is used in a form that directly or indirectly contacts or presses the surface of the photoreceptor, there is a charging roller used in a contact charging type charger. Also in the process of transferring an image (toner image) made of the developer on the surface of the developed photoreceptor onto a transfer sheet such as a copy sheet, a transfer roller that is charged with a polarity different from the charge on the surface of the photoreceptor is used. These charging roller and transfer roller also require that the elastic member be pressed against the photosensitive member with a predetermined contact width, are easily deformed, have excellent deformation recovery properties, and adherence of the developer to the surface. A low one is desired.

  As described above, the elastic roller used in the electrophotographic apparatus has a function corresponding to each application, for example, a developer carrying characteristic in the developing roller, and a conductive characteristic related to charging property in the charging roller or the transfer roller. In addition to the different performance depending on each application, the required performance common as an elastic roller also varies.

  Among the required performance common to the elastic roller, various proposals have conventionally been made for deformation recovery (that is, setability), which is important in maintaining an appropriate contact state. For example, it is known that relatively preferable performance can be obtained by using a urethane resin in a resin layer coated as a surface layer located on the outermost side of the elastic roller.

  In the Japanese Patent Application Laid-Open No. 2002-257130, the inventors combined deformation hardness (compression set) and compression set and permanent elongation of a resin layer on the outer periphery thereof within preferable ranges, respectively. It discloses that the elastic roller has an excellent two-layer structure.

  On the other hand, when a flexible material that easily obtains deformation recovery is used for the surface layer, the adhesion of the developer or the like to the surface of the surface layer tends to increase, and the strength tends to decrease. When an elastic roller having such a surface layer is used as a developing roller, the developer adheres to the surface, which may hinder the operation of supplying a good developer to the photosensitive member, or the resin layer surface may be cracked, cracked or scraped. May occur, making it difficult to obtain good quality images.

  Japanese Patent Laid-Open No. 2000-330370 discloses a toner carrier (developing roller) having a coating layer made of a material containing a resin obtained by curing a mixture of an alkyd-modified silicone compound and a melamine resin on the surface of a conductive elastic layer. It is disclosed that, when used, the coating layer is not cracked or scraped, and various image defects are prevented from occurring.

Japanese Patent No. 3143545 can be cited as an electrophotographic roller using sugar alcohol, which is different from the present invention. In the charging member disclosed in this specification, a polyisocyanate is reacted with a polymer mixture obtained by polymerizing a monomer having an ethylenically unsaturated group in the presence of carbon and polyol on the resin layer. It is characterized by containing the conductive polyurethane resin obtained by this. And with this configuration, it has a stable conductivity in an environment from high temperature and high humidity to low temperature and low humidity, and without causing discharge dielectric breakdown of the photoconductor, the surface of the photoconductor can be charged very uniformly, As a result, it is disclosed that an extremely excellent image can be supplied. Among them, polyhydric alcohols are listed as materials used for polyols, and sugar alcohols are listed in the list of polyhydric alcohols. Absent.
JP 2002-257130 A JP 2000-330370 A Japanese Patent No. 3143545

  In recent years, the required performance of an elastic roller used in an electrophotographic apparatus has become more advanced as the electrophotographic apparatus is speeded up and the image quality is improved, and further improvement is required. . In particular, in surface layer materials, there is still a need to maintain the properties of both low adhesion and film strength with respect to the developer, as well as flexibility and set recoverability, or to further improve these properties.

The object of the present invention is to solve the problems of the elastic roller used in such an electrophotographic apparatus. In particular, an object of the present invention is to adopt a resin surface layer having excellent durability and reducing adhesion, improving the strength of a film, and an elastic roller suitable as a developing roller having a resin layer containing a urethane resin as a surface layer. It is to provide an elastic roller. Another object of the present invention is to provide a developing device and an image forming apparatus using the elastic roller as a developing roller .

  In order to solve the above-mentioned problems, the present inventors have intensively studied and studied. Among urethane resins, it has been confirmed that generally those having flexibility have high adhesion, and conversely, those having low adhesion and good tend to be inferior in flexibility. If carbon black or other fillers are added to highly flexible urethane resin, the surface properties of the developer and external additives contained in the developer, such as adhesion, will be reduced, but the flexibility and set recovery will be reduced. Sex will not be obtained.

  Based on the above findings, the present inventors have advanced further research, and in an elastic roller having a laminated structure in which a surface layer is provided on a roller layer provided on a shaft body, the outer layer (surface layer) By using a urethane resin material containing an appropriate amount of sugar alcohol as the material, it is possible to make an elastic roller that is highly flexible, has low adhesion, and does not crack or crack, and has excellent durability. As a result, the present invention has been completed.

That is, the developing roller of the present invention is a developing roller having a mandrel, and two or more layers including an elastic layer provided on the outer peripheral surface of the mandrel, the surface layer of the outermost layer Consists of a resin layer containing a urethane resin as a main component, and contains 0.050 to 5.0% by mass of a sugar alcohol or a component derived from the sugar alcohol in the resin component of the resin layer. A developing roller.

The developing device according to the present invention includes a latent image carrier for forming an electrostatic latent image by an electrophotographic method, and a state in which the surface of the latent image carrier is abutted or pressed while supporting the developer. A developing roller for supplying the developer to the electrostatic latent image formed on the latent image carrier to develop the electrostatic latent image, wherein the developing roller comprises: A developing device comprising the developing roller having the above-described configuration .

The image forming apparatus of the present invention further includes a latent image carrier capable of forming an electrostatic latent image by an electrophotographic method, a charging device for charging the latent image carrier for forming an electrostatic latent image, and An electrostatic latent image forming apparatus for forming an electrostatic latent image on a charged area of the latent image carrier, and a developer attached to the area of the latent image carrier on which the electrostatic latent image is formed a developing device for obtaining an image by visualizing an electrostatic latent image, in an image forming apparatus having a transfer device for transferring the transfer paper an image composed of developer, the developing device, the An image forming apparatus comprising a developing device having a configuration.

In the elastic roller used as the developing roller according to the present invention , urethane resin is used as a main component for the surface layer constituting the roller surface, and sugar alcohol or a sugar alcohol-derived configuration in the resin component is 0.050 to 5.0. By containing the resin in an amount of mass%, the adhesiveness on the roller surface is reduced and the strength of the coating is improved, and the elastic roller has excellent durability. The elastic roller of the present invention is not only a developing roller but also a charging roller, a transfer roller, and a pressure roller that are used in an electrophotographic apparatus in contact with a photosensitive member as a latent image carrier. Even when applied to the above, an appropriate nip width and durability of the surface state can be stably obtained, and an elastic roller excellent in maintaining the initial good quality for a long time can be easily obtained.

  The elastic roller according to the present invention has a shaft core that is a shaft core of the roller, and two or more layers provided on the outer peripheral surface of the shaft core, and a surface layer as an outermost layer is a main component. It consists of a resin layer containing a urethane resin, and the resin component of the resin layer contains a sugar alcohol or a component derived from the sugar alcohol.

  For example, when an elastic roller having this structural feature is applied to a developing roller, an appropriate nip width can be easily obtained by using a flexible urethane resin layer as the outermost layer, and at the same time, the surface of the roller can be obtained by adding a sugar alcohol component. Since the adhesion of the toner is reduced and the coating strength is improved, the developer component is not fixed to the roller surface, and a latent image is carried in a state where an appropriate amount of developer is carried on the surface in a thin film. It is possible to tightly contact the photosensitive member as a body. As a result, an appropriate amount of developer can be uniformly applied to the surface of the photoreceptor, and better image formation can be performed, and the coating strength is high, the set recoverability is good, and the excellent durability The good image quality can be maintained for a long time.

  In addition, even when the elastic roller having the above structural features is applied to the charging roller, the initial dense state in contact with the surface of the photoreceptor due to the flexibility obtained from the urethane resin and its low surface adhesion. Can be maintained for a long time. In other words, the appropriate nip width and surface state sustainability required to increase the charging efficiency can be stably obtained. As a result, the reduction in charging efficiency can be suppressed, and the original good image quality can be maintained over a long period of time. Make a big contribution. Also, when applied to the transfer roller, the effect similar to that of the charging roller makes a great contribution to maintaining the initial good image quality over a long period of time.

  Hereinafter, the present invention will be described in more detail.

FIG. 1 and FIG. 2 schematically show an example of a structure relating to an elastic roller as a developing roller of the present invention. The elastic roller 1 illustrated in FIGS. 1 and 2 has a shaft core 11 that is usually formed of a conductive material such as metal as a shaft core at the center, and an outer peripheral surface of the shaft core 11 as a roller layer. An elastic body layer (base layer) 12 is fixed thereon, and a resin layer (surface layer) 13 is laminated on the outer peripheral surface of the elastic body layer 12. Here, a description will be given of an elastic roller having two layers on the outer peripheral surface of the shaft core as described above.

  As the shaft core body 11, a shaft core body having a columnar shape or a hollow cylindrical shape and formed of a conductive material such as metal can be used. When the elastic roller is used in an electrically insulated state (for example, a pressure roller or a conveyance roller), the shape of the shaft core body is set against the external force applied to the elastic roller during use. As long as it can be held firmly, the shaft core may be formed of a non-conductive material. Even when such an elastic roller is used with an electrical bias applied or grounded, the main body is made of a non-conductive material instead of being composed of a conductive material. It is also possible to use a material which is formed of a material and has a structure in which the surface is subjected to a conductive treatment satisfying desired conductivity, for example, a coating with a highly conductive coating layer.

  Since a developing roller, a charging roller, and a transfer roller used in an electrophotographic apparatus are generally used with an electrical bias applied or grounded, the shaft core body is electrically conductive. The substrate is a so-called shaft core 11. For example, in an elastic roller for a charging roller, the shaft core 11 is not only a support member, but also functions as an electrode of the charging member. For example, a metal such as aluminum, copper alloy, or stainless steel Or at least the outer peripheral surface of an alloy, iron plated with chromium, nickel or the like, synthetic resin, etc. is made of a conductive material sufficient to apply a predetermined voltage to the roller layer formed thereon. Constitute. In a developing roller, a charging roller, and a transfer roller used in an electrophotographic apparatus, the outer diameter of a conductive substrate that is a shaft core is usually in a range of 4 to 10 mm.

  The elastic body layer 12 serving as a base layer has flexibility, and can be formed as a molded body using rubber as a raw material main component. As the rubber as the main ingredient of the elastic layer 12, various rubbers conventionally used for elastic rollers can be used. Specifically, ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR). ), Fluororubber, silicone rubber, epichlorohydrin rubber, NBR hydride, polysulfide rubber, urethane rubber and the like. These materials may be used in combination of two or more as necessary, as long as desired elastic body hardness and desired characteristics of the roller are given. These rubber materials can be blended with various additives as necessary to form an elastic layer. Additives include components necessary for the functions required for the elastic layer itself, for example, conductive agents, non-conductive fillers, and rubber moldings, depending on the specific application of the elastic roller. Various additives such as a crosslinking agent, a catalyst, and a dispersion accelerator can be appropriately blended with the main rubber material. These addition amounts can also be selected according to the characteristics required for the intended application.

  The conductive agent added for the purpose of imparting conductivity to the elastic layer includes various conductive metals such as carbon black, graphite, aluminum, copper, tin, and stainless steel, or alloys, tin oxide, zinc oxide, and indium oxide. Further, various conductive metal oxides such as titanium oxide, tin oxide-antimony oxide solid solution, tin oxide-indium oxide solid solution, and fine powders such as insulating substances coated with these conductive materials can be used. Among these, carbon black can be suitably used because it can be obtained relatively easily and good chargeability can be obtained regardless of the type of the main rubber material. As a means for dispersing the finely powdered conductive agent in the main rubber material, conventionally used means such as a roll kneader, a Banbury mixer, a ball mill, a sand grinder, a paint shaker, etc. may be used. What is necessary is just to use suitably according to material.

In addition, as a means for imparting conductivity to the elastic layer, a method of adding a conductive polymer compound instead of the conductive agent or together with the conductive agent can be used. For example, as a conductive polymer compound, as a host polymer, polyacetylene, poly (p-phenylene), polypyrrole, polythiophenine, poly (p-phenylene oxide), poly (p-phenylene sulfide), poly (p-ferene vinylene) ), Poly (2,6-dimethylphenylene oxide), poly (bisphenol A carbonate), polyvinylcarbazole, polydiacetylene, poly (N-methyl-4-vinylpyridine), polyaniline, polyquinoline, poly (phenylene ether sulfone), etc. These are used as dopants, such as AsF ₅ , I ₂ , Br ₂ , SO ₃ , Na, K, ClO ₄ , FeCl ₃ , F, Cl, Br, I, Kr, and other ions, Li, TCNQ (7 , 7,8,8-tetracyanoquinodimethane) What is available.

  Examples of the non-conductive filler that can be added to the rubber molded body include diatomaceous earth, quartz powder, dry silica, wet silica, titanium oxide, zinc oxide, aluminosilicate, calcium carbonate, and the like.

  As a crosslinking agent used when producing a rubber molded body, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, Examples thereof include t-butyl peroxybenzoate and p-chlorobenzoyl peroxide. For example, when liquid silicone rubber is used, the rubber components can be cross-linked using a platinum catalyst with polyorganohydrogensiloxane as a cross-linking component.

  In the case where an elastic roller is used as the developing roller, the thickness of the elastic layer is preferably 0. In order to ensure a uniform nip width when abutting and to satisfy a suitable set recoverability. It is desirable that the thickness is 5 mm or more, more preferably 1.0 mm or more. The thickness of the elastic body layer is not particularly limited as long as the outer diameter accuracy of the produced elastic roller is not impaired, but generally, if the thickness of the elastic body layer is excessively increased, the production cost of the rubber molded body is reduced. In view of these practical restrictions, the thickness of the elastic body layer is preferably 6.0 mm or less, more preferably 5.0 mm or less. Therefore, the thickness of the elastic layer is desirably selected in the range of 0.5 to 6.0 mm, and more desirably selected in the range of 1.0 to 5.0 mm. The thickness of the elastic body layer is appropriately selected according to the hardness.

  The hardness (Asker-C) of the elastic body layer 12 is selected in the range of 10 to 70 °. If the hardness (Asker-C) is less than 10 °, rubber elasticity is difficult to obtain, whereas if it exceeds 70 °, it tends to be difficult to obtain an appropriate nip width. More preferably, the hardness (Asker-C) of the rubber molded body forming the elastic body layer is preferably selected in the range of 15 to 55 °.

  The resin layer 11 which becomes a surface layer is a resin layer containing a urethane resin, and includes at least one of sugar alcohol and a component derived from sugar alcohol in the resin component. The sugar alcohol and the components derived from the sugar alcohol (the total amount thereof when multiple types are used) contained in the resin component are suitably in the range of 0.050 to 5.0% by mass. If the content is less than 0.050% by mass, it is not sufficient to obtain the effect of addition, and the surface layer surface adhesion reduction and the surface layer coating strength improvement cannot be obtained. On the other hand, if the content exceeds 5.0% by mass, the flexibility of the urethane resin serving as a base is impaired and hardened, so that cracks and the like are generated, causing problems. Moreover, when adding xylitol, the range of 0.40-4.0 mass% is more preferable. Here, when determining the mass percentage of sugar alcohol, the “resin component” refers to the resin, its monomer component, curing agent component, crosslinker component, etc. in the case of a blend of urethane resin polyol, diisocyanate, and other resins. Based on the resin itself and its constituent components (including sugar alcohols) that are the main component of the resin layer film forming component, additives such as conductive agents and non-conductive fillers are not included. .

  Moreover, the component derived from sugar alcohol shall mean the state by which the structure of the carbon atom and oxygen atom of sugar alcohol was maintained. For example, the structure which the carbon which the hydroxyl group (-OH) of sugar alcohol has formed the urethane bond between the isocyanate compound used as a crosslinking material points out. Specifically, the xylitol-derived structure (component) with respect to xylitol, which is a sugar alcohol (see the following formula (1)), includes those shown in the following formula (2).

樹脂層中に含有される糖アルコールまたは糖アルコール由来の構成の質量％は、実際にローラを作成する際の配合比から計算により求めればよい。また、既に被膜された表層における質量％の求め方としては、その場合に応じ、一般的に知られる方法より適した方法を選択し分析すればよいが、熱可塑ポリウレタン（非架橋ウレタン）の場合は単に溶解させて分析する方法、ウレタン硬化物（架橋ウレタン）の場合には化学分解によりウレタン結合を分解し分析する方法を用いることが出来る。熱可塑ポリウレタンの場合、重ＤＭＳＯ、重ＤＭＦに溶解もしくは膨潤させ、¹³Ｃ ＮＭＲ，¹Ｈ ＮＭＲにて分析するのが適している。ウレタン硬化物の場合、すなわち、化学分解によりウレタン結合を分解し分析する方法としては、例えば、水酸化ナトリウムによる分解、ピリジンを用いた分解等があげられれる。

What is necessary is just to obtain | require the mass% of the structure derived from the sugar alcohol or sugar alcohol contained in a resin layer from the compounding ratio at the time of actually producing a roller. In addition, as a method for obtaining the mass% in the already coated surface layer, a method more suitable than a generally known method may be selected and analyzed depending on the case, but in the case of thermoplastic polyurethane (non-crosslinked urethane) Can be simply dissolved and analyzed, and in the case of a urethane cured product (crosslinked urethane), a method of decomposing and analyzing urethane bonds by chemical decomposition can be used. In the case of thermoplastic polyurethane, it is suitable to dissolve or swell in heavy DMSO or heavy DMF and analyze by ¹³ C NMR and ¹ H NMR. In the case of a urethane cured product, that is, examples of a method for decomposing and analyzing a urethane bond by chemical decomposition include, for example, decomposition with sodium hydroxide, decomposition with pyridine, and the like.

The procedure of the decomposition method using sodium hydroxide is shown below. About 1 g of a sample is cut finely, put into a pressure decomposition vessel together with 20 ml of 20% by mass sodium hydroxide, and decomposed at 180 ° C. for 12 hours. After cooling, the mixture is extracted with diethyl ether, and the ether layer is further washed with 2N hydrochloric acid. The ether layer contains polyether polyol, sugar alcohol, diamine derived from isocyanate in aqueous hydrochloric acid, and chain extender (diisocyanate, etc.) in the alkaline decomposition solution. ¹³ C NMR, ¹ H NMR, IR, etc. The component is identified by In the case of polyester polyol, it is decomposed into a diol compound and a dicarboxylic acid, and this is analyzed in the same manner to identify components.

  As for the decomposition method using pyridine, the method described in Shigeaki Yonemori et al. (Analytical Chemistry, 41, 655, 1992) can be used, and the molecular weight measurement of the polyester polyol and the chain extender can be distinguished. . By using the above method or the like, the sugar mass or the mass% of the sugar alcohol-derived constitution can be determined.

  As the sugar alcohol, those having 4 or more hydroxyl groups in one molecule are preferable, such as adonitol, arabitol, xylitol, D-mannitol, iditol, thalitol, dulcitol, maltitol, lactitol, pentaerythritol, methyl glucoside, etc. May be used alone or in combination. Among these, monosaccharide sugar alcohols are easy to use, and the effects are remarkable and stable. In particular, xylitol and D-mannitol are more preferable. When a monosaccharide is used, it is considered that it is easy to efficiently obtain a high-order crosslinked structure for reasons such as low molecular weight, high mobility in a resin solution, and low steric hindrance. Further, D-sorbitol, which is the same monosaccharide, has a property excellent in moisture retention, is difficult to handle in the present invention, has insufficient effects, and is not preferably used. The reaction of urethane resin curing is easily affected by moisture, and it is considered that the moisture content of D-sorbitol (or variation in the moisture content) is affected.

  A urethane resin is used as a main component of the film forming the resin layer (surface layer) 13. For example, in the use of a developing roller, when urethane resin is used, it is easy to obtain a film having both toner chargeability, self-film reinforcement, and flexibility.

  As a resin film body of a urethane resin that can be used, for example, one prepared by a method of cross-linking a polyurethane prepolymer, or a conductive material of an additive is previously blended with a polyol, and the polyol in this blend is Examples include those prepared by reacting with polyisocyanate by a one-shot method to obtain a polyurethane resin.

  When a polyurethane resin is produced by this one-shot method, the polyol used is a polyol used for producing a general flexible polyurethane foam or urethane elastomer, for example, a polyether polyol having a polyhydroxyl group at the terminal, a polyester polyol. And polyether polyester polyol which is a copolymer of both. In addition, general polyols such as polyolefin polyols such as polybutadiene polyol and polyisoprene polyol, and so-called polymer polyols obtained by polymerizing ethylenically unsaturated monomers in polyols can also be used.

  On the other hand, as the isocyanate compound to be reacted with the above-mentioned polyol compound, polyisocyanate used for production of general flexible polyurethane foam and urethane elastomer, that is, tolylene diisocyanate (TDI), crude TDI, 4,4'-diphenylmethane diisocyanate. (MDI), crude MDI, aliphatic polyisocyanates having 2 to 18 carbon atoms, alicyclic polyisocyanates having 4 to 15 carbon atoms, mixtures of these polyisocyanates and modified products thereof, for example, partially reacted with polyols The prepolymer obtained by the above is used.

  The other components, for example, the components to be blended are not particularly limited. For example, when used as a developing roller, considering the function of supporting toner particles as a developer, self-film reinforcing property, toner From the viewpoint of chargeability and the like, in addition to the urethane resin, a polyamide resin and a urea resin are also preferably used. In addition, it is preferable to use the compounding ratio of resin other than a urethane resin in the range of 2-20 mass% in a resin component in the range which does not impair the property of a urethane resin.

  Furthermore, in order to form the resin layer 13 as the surface layer with good film formability, components necessary for the functions required for the resin layer itself, such as a conductive agent, non-conductive, are used in accordance with the individual use of the elastic roller. Various additives such as fillers and other additives used when forming and laminating on the outer periphery of the elastic layer 12, for example, various additives such as a crosslinking agent, a catalyst, and a dispersion accelerator are appropriately added to the main resin material. Can be blended. Note that additives such as a conductive agent and a non-conductive filler can be appropriately selected from those exemplified above as additives that can be contained in the elastic layer according to the main resin material. Moreover, the addition amount can be suitably selected according to the addition purpose, as long as the characteristics of the resin layer to be formed are maintained within the range in which the effects of the present invention are exhibited.

  The elastic modulus of the resin layer 13 is not particularly limited as long as film properties and durability can be obtained practically. The resin layer 13 is desired to exhibit a high followability to deformation of the elastic body layer 12, and therefore, the resin film body forming the resin layer preferably has a low hardness and elastic modulus.

  The thickness of the resin layer 13 is preferably selected to be 3 μm or more in order to ensure sufficient wear resistance. On the other hand, the developing roller, the charging roller, the transfer roller, and the like are made of an elastic roller having conductivity. In this case, in order to achieve uniform conductivity, the thickness of the resin layer is preferably limited to 100 μm or less. Further, when the thickness of the resin layer is less than 3 μm, it is difficult to uniformly apply and form the elastic layer surface with a desired thin film thickness, while the hardness of the resin layer is that of the elastic layer. Since it is higher than the hardness, if the film thickness exceeds 100 μm, the influence on the deformability of the entire elastic roller becomes large, which is not preferable. Further, the thickness of the resin layer may be appropriately selected according to the hardness and the like in the above range. The thickness of the resin layer of the present invention is measured and determined by observing the cross section with an optical microscope or the like using a sample cut out from a roller.

  For forming the resin layer 13, a method can be used in which the resin raw material used as a raw material for the resin film body is applied in a liquid state to the surface of the elastic body layer, and then the resin film body is formed. The method for applying the resin material is not particularly limited, but the resin material is uniformly applied to the surface of the elastic layer with a desired thickness by a method such as air spray, roll coating, curtain coating, dipping or the like. Thereafter, in order to obtain a resin film body, heat treatment may be performed as necessary.

  The two-layered elastic roller in which the elastic body layer 12 and the resin layer 13 are laminated in this order on the shaft core body 11 has been described above, but the layer structure on the outer periphery of the shaft core body in the elastic roller according to the present invention is three layers. You may have the above multilayered structure. For example, an elastic roller in which another resin layer is further provided between the elastic body layer 12 and the resin layer 13 in the configuration shown in FIG. 2, or the elastic body layer 12 itself includes a plurality of layers (for example, three elastic layers are sequentially formed). An elastic roller composed of a laminated structure). In any configuration, there is no problem as long as the function of the surface layer (resin layer 13) as the outermost layer can be sufficiently obtained, that is, the effect of the present invention can be obtained.

  As described above, the elastic roller according to the present invention is obtained by adding sugar alcohol while maintaining the flexibility, deformation followability, and setability of the urethane resin in the resin layer coated as the outermost surface layer. The adhesion of the coating layer is reduced, the strength of the coating is improved, and the durability is excellent. From this advantage, the elastic roller of the present invention can be suitably used as an elastic roller such as a developing roller, a charging roller, and a transfer roller in an electrophotographic apparatus or the like. In particular, when used for a developing roller, it is easy to obtain an appropriate nip width by using a flexible urethane resin layer, and at the same time, the developer component does not stick to the surface, and an appropriate amount of developer. Can be in close contact with the photoconductor in a state where it is carried as a thin film on its surface, uniformly applying an appropriate amount of developer to the surface of the photoconductor, and performing better image formation, and Due to its high coating strength and excellent durability, its good image quality can be maintained after long-term use. Further, the above-described advantages become more remarkable under the condition that the electrophotographic apparatus to be used is speeded up and the process speed, that is, the speed of the surface of the photoreceptor is increased.

  FIG. 3 is a cross-sectional view showing a schematic configuration of a developing device using the elastic roller of the present invention as a developing roller, and an image forming apparatus using the elastic roller as at least one of a developing roller, a charging roller, or a transfer roller. is there.

  In this image forming apparatus, the photosensitive drum 21 as a latent image carrier rotates in the direction of arrow A, and the region of the photosensitive drum 21 that has passed therethrough is uniformly charged by the charging device 22 for charging the photosensitive drum 21. Further, in this charged region, an electrostatic latent image is formed on the surface by laser light 23 which is an exposure means for writing the electrostatic latent image. The electrostatic latent image is provided with toner as a developer by the developing device 2 that is disposed in the vicinity of the photosensitive drum 21 and is held by a process cartridge 24 (not shown) that is detachable from the image forming apparatus main body. The toner image is developed and visualized as a toner image.

  For development, a method such as so-called reversal development in which a toner image is formed on the exposed portion can be used. The visualized toner image (image) on the photosensitive drum 21 is transferred onto a transfer paper 33 such as paper by a transfer roller 29. The paper 33 to which the toner image has been transferred is subjected to fixing processing by the fixing device 32, discharged outside the device, and the printing operation is completed. The transfer roller 33 is a region that holds the toner image on the photosensitive drum 21 by pressing the transfer paper 33 from the back surface to the region holding the toner image on the photosensitive drum 21 to transfer the toner image onto the surface of the transfer paper. On the contrary, the toner image transfer is promoted by being charged. The transfer paper 33 is pressed against the surface of the photosensitive drum 21 by automatically inserting the transfer paper 33 into the portion where the photosensitive drum 21 and the transfer roller 29 are in contact with each other. Achieved.

  On the other hand, the transfer residual toner remaining on the photosensitive drum 21 without being transferred is scraped off by the cleaning blade 30 and stored in the waste toner container 31, and the above process is repeated on the cleaned photosensitive drum 21. The same image can be copied or a new image can be transferred.

  In the illustrated example, the developing device 2 is positioned opposite to the developing device 34 containing a non-magnetic toner 28 as a one-component developer and the photosensitive drum 21 located in an opening extending in the longitudinal direction in the developing container 34. And a developing roller 25 as a developer carrying member, and the electrostatic latent image on the photosensitive drum 21 is developed and visualized.

  The developing roller 25 is in contact with the photosensitive drum 21 with a contact width. In the developing device 2, the auxiliary roller 26 having elasticity is abutted on the upstream side in the rotation direction of the developing roller 25 with respect to the abutting portion of the elastic blade 27 with the surface of the developing roller 25 and rotates in the developing container 34. Supported as possible. As the structure of the auxiliary roller 26, a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon or nylon are planted on the core metal, the toner 28 is supplied to the developing roller 25 and the undeveloped toner is stripped off. It is preferable from the point. In this embodiment, an auxiliary roller 26 having a diameter of 16 mm and having a polyurethane foam on a core metal is used.

  As the contact width of the auxiliary roller 26 with respect to the developing roller 25, 1 to 8 mm is effective, and it is preferable to have a relative speed at the contact portion with respect to the developing roller 25. In this embodiment, The contact width is set to 3 mm, and the driving means (not shown) at a predetermined timing is set so that the peripheral speed of the elastic roller 26 is 50 mm / s during development operation (the relative speed with respect to the developing roller 25 is 130 mm / s). It is driven to rotate.

  The elastic roller according to the present invention is applied to a charging roller 22 for charging the region by contact or pressure contact with the cleaned region of the surface of the photosensitive drum 21 and a region for holding the toner image on the photosensitive drum 21. It can also be suitably used as the transfer roller 29 arranged in contact or pressure contact.

Hereinafter, the present invention will be described more specifically with reference to examples. These examples are examples of the best mode of the present invention, but the present invention is not limited to the examples. The elastic roller manufactured by the method shown in the embodiment is, for example, a developing member such as a developing roller, a charging member such as a charging roller or a transfer roller, and an elastic used in an electrophotographic apparatus or the like in various individual applications. It can be suitably used as a roller.
[Example 1] Elastic roller 1
An SUS metal core (φ6 mm) with nickel plating applied as a shaft core was further applied and baked with an adhesive. This shaft core is placed in a mold, and as a raw rubber, a liquid silicone rubber (a linear polydimethylsiloxane blocked with a terminal vinyl group, a branched polysiloxane segment having one vinyl group, and a bifunctional dimethyl group). Addition of a polysiloxane mixture consisting of a block polymer consisting of a linear oil segment containing siloxane and an organosiloxane having two or more silicon-bonded hydrogen atoms in one molecule as a cross-linking agent and a platinum-based catalyst Type silicone rubber composition) 100 parts by mass, 4 parts by mass of silica powder as a heat resistance imparting agent that is an inorganic fine powder, 60 parts by mass of quartz powder, and 10 parts by mass of carbon black as a conductivity imparting agent are mixed to form a liquid rubber compound. Was prepared and injected into a cavity formed in the mold. Subsequently, the mold was heated at 150 ° C. for 20 minutes to cure and cure the silicone rubber, and after cooling, the mold was removed to produce a roller having an elastic body layer having a thickness of 4 mm on the outer periphery of the shaft core body. .

  Next, solid content 15 mass of isocyanate (Coronate L; trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.) as a curing agent with respect to 100 mass parts of solid content of polyol (Nipporan 5025; trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.). Parts, xylitol as sugar alcohol (xylit; trade name, manufactured by Towa Kasei Kogyo Co., Ltd.) 0.10 parts by mass, carbon black as a conductive agent is added in an appropriate amount, methyl ethyl ketone is used as a main solvent, and the mixture is stirred thoroughly It adjusted so that it might become an organic solvent mixed solution of 11% of solid content. The roller is immersed in this coating solution, coated, pulled up, dried, and heat-treated at 142 ° C. for 30 minutes to provide an elastic roller 1 having a surface layer of about 20 μm provided on the outer periphery of the elastic layer. Was made. The sugar alcohol component in the resin component of the surface layer of the elastic roller 1 thus produced was 0.087% by mass.

[Example 2] Elastic roller 2
The elastic roller 2 was produced in the same manner as in Example 1 except that the addition amount of xylitol (Xylit, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name), which is a sugar alcohol component, was changed to 0.50 parts by mass. The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 2 was 0.43% by mass.

[Example 3] Elastic roller 3
The elastic roller 3 was produced in the same manner as in Example 1 except that the addition amount of xylitol (Xylit, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name), which is a sugar alcohol component, was changed to 3.0 parts by mass. The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 3 was 2.5% by mass.

[Embodiment 4] Elastic roller 4
The elastic roller 4 was produced in the same manner as in Example 1 except that the addition amount of xylitol (Xylit, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name), which is a sugar alcohol component, was changed to 4.7 parts by mass. The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 4 was 3.9% by mass.
[Embodiment 5] Elastic roller 5
The elastic roller 5 was produced in the same manner as in Example 1 except that the amount of xylitol (Xylit, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name), which is a sugar alcohol component, was changed to 5.8 parts by mass. The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 5 was 4.8% by mass.

[Embodiment 6] Elastic roller 6
An elastic roller 6 was produced in the same manner as in Example 1 except that 1.2 parts by mass of D-mannitol (Marine Crystal, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name) was added as a sugar alcohol component instead of xylitol. . The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 6 was 1.0% by mass.

[Embodiment 7] Elastic roller 7
An elastic roller 7 was produced in the same manner as in Example 1 except that 3.0 parts by mass of D-mannitol (Marine Crystal, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name) was added as a sugar alcohol component instead of xylitol. . The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 7 was 2.5% by mass.

[Embodiment 8] Elastic roller 8
An elastic roller 8 was produced in the same manner as in Example 1 except that 3.0 parts by mass of maltitol (Resis, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name) was added as a sugar alcohol component instead of xylitol. The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 8 was 2.5% by mass.

[Comparative Example 1] Elastic roller 9
An elastic roller 9 was produced in the same manner as in Example 1 except that the sugar alcohol component was not added. The sugar alcohol component is not contained in the resin component of the surface layer of the produced elastic roller 9.

[Comparative Example 2] Elastic roller 10
The elastic roller 10 was produced in the same manner as in Example 1 except that the addition amount of xylitol (Xylit, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name), which is a sugar alcohol component, was changed to 0.04 parts by mass. The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 10 was 0.035% by mass.

[Comparative Example 3] Elastic roller 11
The elastic roller 11 was produced in the same manner as in Example 1 except that the addition amount of xylitol (Xylit, manufactured by Towa Kasei Kogyo Co., Ltd .; trade name), which is a sugar alcohol component, was changed to 10 parts by mass. The sugar alcohol component in the resin component of the surface layer of the produced elastic roller 11 was 8.0% by mass.

[Characteristic evaluation]
The elastic roller obtained as described above was incorporated into an actual machine as a developing roller, and various evaluations were performed. In addition, carbon black was appropriately added to the elastic body layer and the resin layer of all the developing rollers, and the electric resistance of the rollers was adjusted to 10 ⁶ or less.
・ Evaluation of adhesion The evaluation of adhesion was made by taking out the developing roller after printing 100 sheets, blowing the air on the roller surface with air spray, scattering the developer adhering to the surface, and further methylating the surface. Wipe with a cloth containing alcohol and evaluate. If the roller surface is clearly exposed by spraying with air spray and there is no deposit ◎, if there is a little adhesion of external additives contained in the developer ○, spraying by air spray can not remove the deposit, When the cloth containing methyl alcohol was wiped, the surface where the roller surface was clearly exposed was indicated by Δ, and when spraying with air spray and wiping with the cloth containing methyl alcohol were left as adhered, x was assigned.
Image Level Evaluation Image level and durability were evaluated by observing the presence and change of image problems at the initial stage and before and after printing 6000 sheets, and the state of the roller surface after printing 6000 sheets. Initially, the evaluation of the images before and after printing 6000 sheets was: ◎ for good, ◯ for no problem, △ for slightly shaded, and for those with noticeable image defects such as dropout × It was. The durability was evaluated by comparing the images at the initial stage and before and after printing of 6000 sheets. No change over time, ◎ for those that are good or no problem, ◯ for those that are slightly degraded but no problem, Although there was no change, the case where there was a problem in the image itself was indicated by Δ, and the case where the problem occurred in the image over time was indicated by ×.
・ Comprehensive evaluation As described above, the comprehensive evaluation is ◎ if there is no problem in adhesion and durability and the image level is good, ○ if there is no problem in any of the adhesion, durability, and image level. The case where a problem occurred in any of the durability was evaluated as x.

  The results of evaluation based on the above criteria are shown in Table 1.

表１に示すとおり、実施例１〜８では、付着性、耐久性いずれの性能にも問題はなかった。その中でも実施例２、３、４、６、７は、特に良好な結果が得られた。

As shown in Table 1, in Examples 1 to 8, there was no problem in the performance of both adhesion and durability. Among them, Examples 2, 3, 4, 6, and 7 gave particularly good results.

It is a figure which shows typically an example of the whole structure of the elastic roller as a developing roller of this invention. FIG. 3 is a cross-sectional view schematically showing a two-layer structure of a roller layer in an elastic roller as a developing roller of the present invention.

It is sectional drawing of FIG.
It is explanatory drawing of the image forming apparatus using the developing device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Elastic roller 2 ... Developing apparatus 3 ... Image forming apparatus 11 ... Shaft core body 12 ... Elastic body layer (base layer)
13 ... Resin layer (surface layer)
21 ... photosensitive drum 22 ... charging device 23 ... laser beam 25 ... developing roller 26 ... auxiliary roller 27 ... elastic blade 28 ... toner 29 ... transfer roller 30 ... cleaning blade 31 ... waste toner container 32 ... fixing device 33 ... paper 34 ... development container

Claims (6)

A developing roller having a shaft core and two or more layers including an elastic layer provided on an outer peripheral surface of the shaft core,
The outermost surface layer is composed of a resin layer containing a urethane resin as a main component, and 0.05 to 5.0% by mass of sugar alcohol or a component derived from the sugar alcohol in the resin component of the resin layer A developing roller. The developing roller according to claim 1, wherein the resin layer is obtained by curing a coating film of a paint containing a polyol compound, an isocyanate compound, and the sugar alcohol. The sugar alcohol includes a developing roller according to claim 1 or 2 is at least one of xylitol and D- mannitol. The developing roller according to claim 1, wherein a thickness of the resin layer is selected in a range of 3 to 100 μm. A latent image carrier for forming an electrostatic latent image by an electrophotographic method, and a developer in a state where the developer is carried in contact with or pressed against the surface of the latent image carrier. A developing roller for supplying the electrostatic latent image formed on the image carrier and developing the electrostatic latent image,
A developing device wherein the developing roller is characterized <br/> it is a developing roller according to any one of claims 1 to 4. A latent image carrier capable of forming an electrostatic latent image by an electrophotographic method, a charging device for charging the latent image carrier for forming an electrostatic latent image, and a static region in a charged region of the latent image carrier. An electrostatic latent image forming apparatus for forming an electrostatic latent image; and a developer is attached to a region of the latent image carrier on which the electrostatic latent image is formed to visualize the electrostatic latent image. In an image forming apparatus having a developing device for obtaining an image and a transfer device for transferring an image made of the developer onto transfer paper,
An image forming apparatus according to claim 5 , wherein the developing device is the developing device according to claim 5.

Images