JP2005300752A - Developing roller, electrophotographic process cartridge and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller capable of forming a high-quality image without generating image stripes and banding even in a high-speed and high-definition electrophotographic process. <P>SOLUTION: The developing roller is a roller having a conductive shaft center body and an elastic layer and/or a resin layer provided on the outer periphery of the shaft center body, and forms a visible image on the surface of a photoreceptor drum by forming a developer thin layer on the surface of the roller, bringing the roller into contact with the photoreceptor drum and supplying developer to the surface of the photoreceptor drum. In the developing roller, rubber material constituting the elastic layer is set so that its repulsive elastic modulus is 50 to 75% and its specific gravity is 1.02 to 1.10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus such as an electrophotographic copying apparatus, a printer, and an electrostatic recording apparatus, and the developer is supplied to the surface of the image forming body by contacting the image forming body. The present invention relates to a developing roller capable of obtaining a high-definition image in an electrophotographic process cartridge for forming a visible image, an electrophotographic process cartridge including the developing roller, and an electrophotographic image forming apparatus.

  Conventionally, a contact developing method is known as a developing method for forming a visible image on the surface of a photosensitive drum by supplying a developer to the photosensitive drum by a developing roller arranged in contact with the image forming body (photosensitive drum). It has been. In this contact development method, the developer is attached to the surface of the developing roller, the layer thickness of the developer is made uniform by a layer thickness regulating member, and the developer is attached to the surface of the photosensitive drum by bringing the developing roller into contact with the photosensitive drum. I am letting. For this reason, the developing roller used in the developing system needs to have elasticity and hardness for forming an appropriate nip when in contact with the photosensitive drum, and further have an appropriate electrical conductivity.

  The development roller structure required for this purpose has conventionally been to impart conductivity to elastic rubber such as EPDM, silicone rubber, polyurethane rubber and its foam on the outer periphery of a shaft core made of a good conductor such as metal. In order to achieve this, a material coated with a conductive agent such as carbon black is used. Furthermore, there has also been proposed a coating in which a coating film containing a conductive agent and resin particles is coated on the outer periphery of the elastic layer for the purpose of controlling the amount of developer attached to the surface of the developing roller.

  For example, Patent Document 1 proposes a developing roller whose elastic layer has a hardness of 20 ° to 40 ° (Asker C). As the developing roller proposed in this proposal, the elastic layer hardness as described above has been proposed from the viewpoint of preventing image density unevenness and developer deterioration.

  The developing roller thus reduced in hardness has a large amount of deformation of the contact portion with the layer thickness regulating member that is in contact with a constant load. It becomes difficult to recover, and streaks may occur in the image when printing next time, which may be a problem.

  In addition, it is known that by making the elastic layer of the developing roller highly repulsive, the deformation amount of the contact portion due to long-term contact with the layer thickness regulating member can be reduced to suppress the occurrence of image streaks. . In Patent Document 2, the hardness of the elastic layer constituting the developing roller is reduced to some extent to reduce the stress on the developer to obtain an appropriate nip, and the rebound elastic modulus of the elastic layer is By making it larger than a certain level, even if an elastic material in a low hardness region is used, it becomes possible to reduce the deformation remaining at the contact portion with the layer thickness regulating member to some extent, and there is a technique for suppressing the occurrence of image streaks. Proposed.

JP 2000-112225 A Japanese Patent Laid-Open No. 10-268631

  However, with the recent increase in printing speed, higher image definition, and further colorization, even a slight change in the shape of the developing roller has been confirmed as a streak in the image. Even in a developing roller having an elastic layer whose hardness and rebound elastic modulus are appropriately adjusted as in the prior art, streaks on the image due to deformation at the contact portion with the layer thickness regulating member become a problem, and further improvement is desired. It has come to be. Further, since the material of the elastic layer is made highly repellent, problems such as banding due to an increase in torque in the developing roller driving mechanism also occur.

  Therefore, in the present invention, in order to eliminate the banding due to the rotation unevenness of the developing roller driving mechanism, the conventional technology cannot be adopted from the viewpoint of image streaks accompanying the deformation of the contact portion due to the contact with the layer thickness regulating member. Even when a material having a rebound resilience in a region is used for the elastic layer, it is possible to obtain a developing roller having high ability for image streaking and banding by optimizing the specific gravity.

  An object of the present invention is to provide a developing roller that can form a high-quality image free from image streaking or banding even in a high-speed, high-definition electrophotographic process.

  According to the present invention, there is provided a roller having a conductive shaft core and an elastic layer and / or a resin layer provided on the outer periphery of the shaft core, wherein a thin layer of developer is formed on the roller surface, In the developing roller for forming a visible image on the surface of the photosensitive drum by bringing the roller into contact with the photosensitive drum and supplying the developer to the surface of the photosensitive drum, the rubber material constituting the elastic layer has a rebound elastic modulus of 50. There is provided a developing roller having a specific gravity of 1.02 to 1.10.

  According to the present invention, the photosensitive roller is provided with a developing roller, a thin layer of developer is formed on the surface of the developing roller, the developer roller is brought into contact with the photosensitive drum, and the developer is supplied to the surface of the photosensitive drum. An electrophotographic process cartridge for forming a visible image on a drum surface is provided, wherein the developing roller is the developing roller described above.

  According to the present invention, a developing roller is provided, a thin layer of developer is formed on the surface of the developing roller, the developer roller is brought into contact with the photosensitive drum, and the developer is supplied to the surface of the photosensitive drum. In the electrophotographic image forming apparatus for forming a visible image on the surface of the photosensitive drum, the electrophotographic image forming apparatus is characterized in that the developing roller is the above developing roller.

  The developing roller according to the present invention is a high-speed, high-definition electrophotographic process cartridge and an electrophotographic image apparatus in which the electrophotographic process cartridge is incorporated, and a contact portion that occurs due to long-term contact with the developer layer thickness regulating member of the developing roller. It is possible to supply a high-definition image without image streaking due to deformation or banding due to uneven rotation of the developing roller. In addition, an electrophotographic process cartridge and an electrophotographic image forming apparatus capable of obtaining a high-definition image free from image stripes and banding are provided.

  As a result of intensive studies to solve the above problems, the present inventors have found that the rebound resilience is 50 to 75% and the specific gravity is 1.02 to 1.10. It was discovered that a high-definition image free from image streaks and banding can be obtained by using the filling material as the elastic layer of the developing roller, and the present invention has been achieved.

  The hardness of the elastic body used for forming the elastic layer is preferably 27 to 55 ° (Asker C), and the material is preferably silicone rubber.

  As the silicone rubber, an organohydrogensiloxane having a hydrogen atom directly bonded to at least two silicon atoms in one molecule per 100 parts by weight of an organopolysiloxane having at least two alkenyl groups in one molecule (silicon The total number of hydrogen atoms directly bonded to the atoms / (total number of alkenyl groups of component (A)) is 0.8 to 1.5 parts by weight, and the conductivity-imparting agent and / or reinforcing emphasis material and It is preferable that the total amount of the extender is 5 to 50 parts by weight, and that the catalyst is a curable composition in an amount sufficient to cure the composition.

  Next, the present invention will be described in more detail with reference to preferred embodiments. These examples are examples of the best mode of the present invention, but the present invention is not limited to the examples.

[Development roller]
Next, the configuration of the developing roller of the present invention will be described. The developing roller of the present invention has, for example, a cross-sectional structure as shown in FIG. 1 and has a conductive shaft core 1 and a concentric circular shape on the outer periphery of the shaft core 1 as shown in FIG. And a surface layer 3 that is a resin layer formed on the outer periphery of the elastic layer 2.

[Shaft core]
The conductive shaft core 1 used in the present invention is, for example, a cylinder having a carbon steel alloy surface with industrial nickel plating having a thickness of 5 μm. In addition to the materials constituting the conductive shaft core 1, for example, alloys such as iron, aluminum, titanium, copper and nickel, alloys such as stainless steel, duralumin, brass and bronze containing these metals, carbon black, A known material exhibiting rigidity and conductivity, such as a composite material in which carbon fibers are hardened with plastic, can also be used. Moreover, as a shape, it can also be set as the cylindrical shape which made the center part the cavity other than column shape.

[Elastic layer]
As the raw material rubber forming the elastic layer, ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR) ), Styrene-butadiene rubber (SBR), fluorine rubber, silicone rubber, epichlorohydrin rubber, hydride of NBR, polysulfide rubber, urethane rubber and the like can be used.

  Furthermore, in the developing roller of the present invention, when forming a rubber molded body for forming the elastic layer, components necessary for the function required for the elastic layer itself, such as a conductive agent, a non-conductive material, are used in accordance with individual applications. Various additive components used when forming a rubber molded body, for example, various additives such as a crosslinking agent, a catalyst, a dispersion accelerator, etc., may be appropriately blended in the main rubber material. it can.

  Conductive agents added for the purpose of imparting conductivity to the elastic layer include various conductive metals or alloys such as carbon black, graphite, aluminum, copper, tin, and stainless steel, tin oxide, zinc oxide, indium oxide, and titanium oxide. Further, various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution, and fine powders such as insulating materials 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.

  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. The silica used in this case is not particularly limited, and conventionally known ones can be widely used. Examples thereof include anhydrous silicic acid by the dry method described above, hydrous silicic acid by the wet method, and synthetic silicate. .

  In the developing roller of the present invention, the rebound resilience of the rubber molded body forming the elastic layer is selected in the range of 50 to 75%. If the rebound resilience of the molded rubber forming the elastic layer is less than 50%, it is difficult to obtain rubber elasticity that contributes to set performance. On the other hand, when it exceeds 75%, banding occurs with an increase in the driving torque of the developing roller.

  At the same time, the specific gravity of the rubber molded body forming the elastic layer is selected to be in the range of 1.02 to 1.10. In the range where the specific gravity of the rubber molded body is less than 1.02, since the reinforcing property of the rubber molded body is insufficient, durability as an elastic layer necessary for the product is impaired, and the elastic layer is scraped during continuous durability. There will be problems that cause burrs.

  On the other hand, when the specific gravity of the rubber molded body exceeds 1.10, the behavior of the polymer component for expressing rubber elasticity that contributes to the set performance in the rubber molded body even in the range of the rebound elastic modulus. Is not preferable because it is inhibited.

  The hardness of the rubber molded body forming the elastic layer is preferably in the range of 27 ° to 55 ° (Asker C). If the hardness (Asker C) of the rubber molding forming the elastic layer is less than 27 °, the end portion of the conductive resin layer due to durability is peeled off, which is not preferable. On the other hand, if the angle exceeds 55 °, the stress on the developer increases and development streaks occur.

  In particular, when silicone rubber is used as the raw material rubber for forming the elastic layer, it is easy to obtain a rubber having a rebound resilience and specific gravity within the above ranges. Silicone rubber is excellent in processability, has no dimensional stability due to the generation of by-products associated with the curing reaction, and has an addition reaction cross-linking type for reasons such as stable physical properties after curing. Silicone rubber polymers are preferred.

  This silicone rubber contains, for example, an organopolysiloxane represented by Chemical Formula 1 and an organohydrogenpolysiloxane represented by Chemical Formula 2, and can be used by appropriately mixing with a catalyst or other additives.

  Organopolysiloxane is a base polymer of silicone rubber, and its molecular weight is not particularly limited, but is preferably from 100,000 to 1,000,000, and the average molecular weight is preferably from 400,000 to 700,000.

  The organopolysiloxane preferably has at least two alkenyl groups in one molecule, and the type thereof is not particularly limited. However, at least one of vinyl group and allyl group is preferable because of its high reactivity with active hydrogen. One is preferable, and a vinyl group is particularly preferable.

  Organohydrogenpolysiloxane serves as a crosslinking agent for addition reaction in the curing process, and the number of silicon-bonded hydrogen atoms in one molecule is 2 or more, and in order to perform the curing reaction optimally, Three or more polymers are preferred. The molecular weight of the polyorganohydrogenpolysiloxane is not particularly limited and may be from 1,000 to 10,000, but a relatively low molecular weight of 1,000 or more and 5,000 or less is preferable in order to appropriately perform the curing reaction.

  The amount of the organohydrogenpolysiloxane blended with respect to the number of alkenyl groups in the organopolysiloxane is the number of Si—H groups in the organohydrogenpolysiloxane, ie, (total number of hydrogen atoms directly bonded to silicon atoms) / ( If the total number of alkenyl groups of the organopolysiloxane is less than 0.5, a sufficient network structure cannot be obtained and the necessary rebound resilience and hardness after curing cannot be obtained. A range of 0.5 to 1.5 is preferable because the H group is hardened by an excessive crosslinking reaction caused by moisture or the like.

  When the blending amount of the conductive agent and the non-conductive filler is less than 5 parts with respect to 100 parts of the organopolysiloxane, the resulting silicone rubber has poor reinforcement, and when it exceeds 50 parts, the rubber elasticity contributing to the set performance is reduced. Since the behavior of the polymer component for expression is inhibited, 5 to 50 parts is preferable.

As the catalyst for the silicone rubber, a transition metal compound that exhibits a catalytic action in the hydrosilylation reaction can be used. Specific examples thereof include Fe (CO) ₅ Co (CO) ₈ , RuCl ₃ , IrCl ₃ , [(olefin) PtCl ₂ ] ₂ , vinyl group-containing polysiloxane-Pt complex, H ₂ PtCl ₆ .6H ₂ O, L ₂ Ni (olefin), L ₄ Pd, L ₄ Pt, L ₂ NiCl ₂ (where L = PPh ₃ or PR ′ ₃ , where P is phosphorus, Ph is a phenyl group, and R ′ is an alkyl group) Can be mentioned. Of these, platinum, palladium, and rhodium-based transition metal compounds are preferable.

  In the case of a platinum-based metal compound catalyst, the compounding amount of the catalyst is preferably 1 to 100 ppm by mass as platinum in silicone rubber (including various compounds), but is not limited to this range. It is appropriately selected depending on the target pot life, curing time, product shape and the like.

  As a method for arranging the elastic layer around the shaft core body 1, several methods such as extrusion molding and injection molding may be mentioned. Among these, the elastic body processed by extrusion molding has the advantage that it is not necessary to prepare a mold for molding, but it does not have shape accuracy for use as a developing roller as it is. It is necessary to finish the surface into a desired shape by polishing the surface with a grinding machine or the like.

  On the other hand, in forming the developing roller elastic layer by injecting an uncured material into a cylindrical mold and then vulcanizing by heating, the elastic layer is arranged around the shaft body. Since the shape is reproduced on the basis of a certain amount of shrinkage, it is possible to obtain a shape having a sufficiently satisfactory shape accuracy without polishing.

［表層］
本発明では以上のようにして形成された導電性弾性層の表面に更に表層として樹脂層を形成することもできる。表層を形成する材料としては、各種のポリアミド、フッ素樹脂、水素添加スチレン−ブチレン樹脂、ウレタン樹脂、シリコーン樹脂、ポリエステル樹脂、フェノール樹脂、イミド樹脂、オレフィン樹脂等が挙げられる。

[Surface]
In the present invention, a resin layer can also be formed as a surface layer on the surface of the conductive elastic layer formed as described above. Examples of the material for forming the surface layer include various polyamides, fluororesins, hydrogenated styrene-butylene resins, urethane resins, silicone resins, polyester resins, phenol resins, imide resins, olefin resins, and the like.

  These materials constituting the surface layer are dispersed using a conventionally known dispersion apparatus using beads such as a sand mill, a paint shaker, a dyno mill, a pearl mill or the like. The obtained dispersion for forming the surface layer is applied to the surface of the conductive substrate by a spray coating method, a dipping method or the like. In the present invention, since it is preferable that the surface of the developing roller is uniformly rough, spray coating is particularly preferably used.

  The thickness of the surface layer is preferably 5 μm or more from the viewpoint of preventing the low molecular weight component from seeping out and contaminating the photoreceptor, and from the viewpoint of preventing the developing roller from becoming hard and causing fusing. preferable. More preferably, it is 10-30 micrometers.

  By dispersing fine particles having a mass average particle diameter of 1 to 20 μm in the surface layer formed as described above, the developer on the surface of the developing roller can be easily conveyed, and a sufficient amount of developer can be developed. It can be conveyed to an area, which is preferable. Examples of the fine particles used for such purpose include plastic pigments such as polymethyl methyl methacrylate fine particles, silicone rubber fine particles, polyurethane fine particles, polystyrene fine particles, amino resin fine particles, and phenol resin fine particles. Methyl acid fine particles and silicone rubber fine particles are preferable. These fine particles are preferably added in a range of about 20 to 200% by mass (based on the total mass of the surface layer constituting components excluding the fine particles) of the surface layer.

[Electrophotographic process cartridge]
Next, FIG. 3 shows an example of a schematic diagram of a contact developing type electrophotographic image forming apparatus having a developing roller of the present invention.

  First, an electrophotographic process cartridge having the developing roller of the present invention will be described. The electrophotographic process cartridge includes a primary charging roller 4, a photosensitive drum 5, a developing roller 11, a developer supply roller 12, a developer layer thickness regulating member 15 that is a developer layer thickness regulating member, a stirring blade 17 and the developer 14 are combined into one cartridge, and can be integrally replaced in the electrophotographic image apparatus. The developer sent to the developer supply roller by the stirring blade is uniformly coated on the surface of the developing roller 11 by the developer layer thickness regulating member, and is conveyed to the surface of the photosensitive drum 5 and developed. After the developer is transferred to the recording medium 10 such as paper, the surface of the photosensitive drum 5 is uniformly charged again by the primary charging roller.

  Looking at the electrophotographic image forming apparatus of the contact development type according to FIG. 3, the developing roller 11 of the present invention holds the developer 14 on its surface and rotates the laser on the photosensitive drum 5 while rotating in the direction of the arrow. The latent image formed by the light 16 is developed, and the developer remaining on the surface of the developing roller 11 without being used for development is returned to the developing container 13 while being carried on the surface.

  Inside the developing container, the developer supply roller 12 removes the developer remaining on the surface of the developing roller 11 from the surface of the developing roller 11 and supplies new developer to the surface of the developing roller 11. The new developer supplied to the surface of the developing roller 11 has its coat thickness uniformly adjusted by the developer layer thickness regulating member 15 and is conveyed to the developing area. By repeating this, the developing roller 11 always coats a new developer uniformly to develop the electrostatic latent image.

  The developed developer image is conveyed to the transfer area by the rotation of the photosensitive drum 5 and transferred to the recording medium 10 by the transfer roller 9. Thereafter, the unfixed developer image passes between the fixing roller 7 and the pressure roller 8 and is fixed to the recording medium by pressure and heat. The developer remaining on the photosensitive drum 5 without being transferred in the transfer step is removed from the photosensitive drum by the cleaning elastic blade 6 as the photosensitive drum 5 rotates. The surface of the photosensitive drum 5 whose surface has been cleaned is charged by the primary charging roller 4 and is subjected to exposure and development again.

  Hereinafter, the present invention will be described in more detail by way of examples.

  First, a method for measuring each physical property of the elastic layer material used in Examples and Comparative Examples will be described.

[Asker C hardness]
The Asker C hardness was measured using an Asker C type hardness tester (manufactured by Kobunshi Keiki Co., Ltd.) on a test piece having a thickness of 6 mm. The details of the measuring method other than the measuring device were performed according to JIS-K6253 5 (durometer hardness test).

[Rebound resilience]
The rebound resilience was measured according to JISK6255.

[specific gravity]
The specific gravity was measured according to JIS K6268 5.1 (Method A). However, the temperature of water was 23 ± 2 ° C.

  next. The developing roller evaluation method performed in the examples and comparative examples will be described.

[Banding image evaluation method]
The electrophotographic laser beam printer used in this evaluation is a machine for A4 size output, the output speed of the recording medium is A4 vertical 16 sheets / minute, and the image resolution is 600 dpi. The photosensitive drum is a reversal developing type photosensitive drum in which an OPC (organic photoconductor) layer is coated on an aluminum cylinder, and the outermost layer is a charge transport layer using a modified polycarbonate as a binder resin.

  Banding image evaluation was performed from solid images and halftone images. In other words, the level where the image density is sufficiently high and streaks occur in the driving gear cycle of the developing roller in the direction perpendicular to the image printing direction and is a practical problem, and the level where the streak occurs thinly but has no practical problem. Δ and no streak were marked as ○.

[Image evaluation method for set performance]
The developing roller is mounted on the electrophotographic process cartridge, and the developing roller is 40 ° C., 95% R.D. After being left for 1 month in an environment of H, the developing roller was remounted on a newly prepared electrophotographic process cartridge, and image evaluation was performed with an electrophotographic laser beam printer.

  Regarding image evaluation, the image density is sufficiently dark and the level that is a practical problem because streaks occur in the direction of the developing roller in the direction perpendicular to the image printing direction, and the level that causes a practical problem is thin, but the level is low. Δ and no streak were marked as ○.

[Image evaluation method for development streaks]
The developing roller is attached to an electrophotographic laser beam printer, and after 10000 continuous images of a horizontal line having a width of 2 dots and an interval of 50 dots in the direction perpendicular to the rotation direction of the photosensitive drum, the rotation direction of the photosensitive drum is changed. The evaluation was performed using an image in which a horizontal line having a width of 1 dot and an interval of 2 dots was drawn in the vertical direction. That is, x indicates a level at which an image defect of the developing roller pitch due to the fusion of the developer to the surface of the developing roller or blade is observed, and Δ indicates a level at which an image defect of the developing roller pitch is observed but has no practical problem. A level at which no defective image of the pitch was observed was marked with a circle.

[Surface adhesion]
The surface of the developing roller was visually observed after 10,000 sheets of continuous durability, and the surface layer was observed to float from the edge to the image area, or the level that had been peeled off was x, and the surface layer was floating at the edge. Is observed or peeled off, but a level that does not cause a practical problem due to the non-image area is indicated by Δ, and a level at which no peeling occurs is indicated by ○.

  Next, the developing roller manufacturing method actually evaluated in the present invention will be described in detail.

  First, the shaft core is made of iron with chemical nickel plating. The shaft core is placed in the center of the cylindrical mold, and silicone rubber is injected into the cylindrical mold from the inlet. And cured by heating at 110 ° C. for 5 minutes to form a silicone rubber elastic layer. The silicone rubber contains silica powder and carbon black as a filler in organopolysiloxane and a small amount of platinum compound as a curing catalyst, and silica powder and carbon black as a filler in organohydrogenpolysiloxane. In addition, a mixture of a mixture of a trace amount of curing retardant and a weight ratio of 1: 1 was used. Prior to the formation of the silicone rubber elastic layer, the surface of the core metal was subjected to primer treatment for the purpose of improving the adhesion between the silicone rubber and the shaft core body.

  Next, heat treatment was performed at 200 ° C. for 4 hours for the purpose of stabilizing the physical properties after curing of the silicone rubber elastic layer, removing reaction residues and unreacted low molecular components in the silicone rubber elastic layer, and the like.

  Thereafter, a dipping solution containing 10 to 20% of polymethyl methyl methacrylate fine particles having an average particle diameter of 10 to 20 μm is dispersed on the surface of the obtained silicone rubber elastic layer for the purpose of improving urethane resin and developer transportability. Was laminated.

  Then, the roller after coating and air drying was subjected to a heat treatment at 140 ° C. for 4 hours to form a polyurethane resin layer having a thickness of about 20 μm as a surface layer.

  In the above methods and materials, Examples 1 to 7 and Comparative Examples 1 to 8 described below are specific gravity, hardness and repulsion of the silicone rubber elastic layer by changing the ratio of the filler contained in the silicone rubber and the polymer crosslinking density. The results of evaluating the characteristics with various changes in the elastic modulus are shown below.

  Using a silicone rubber having a specific gravity of 1.06, a material hardness of 46 ° (Asker C) and a rebound resilience of 72% when cured, according to the above method, an iron of 8 mm in diameter is used. A silicone rubber elastic layer was formed on the shaft to obtain a conductive roller elastic layer having a rubber part diameter of 16 mm and a rubber part length of 240 mm.

  Next, the obtained silicone rubber elastic layer was dipped with the above-mentioned surface coating material and dried at 140 ° C. for 4 hours to provide a surface layer having a thickness of about 20 μm. When the obtained developing roller was incorporated into an electrophotographic image apparatus and an image was output, an image having a uniform density without streaks was obtained. The results are summarized in Table 1.

  Developing roller in the same manner as in Example 1 except that the specific gravity of the silicone rubber material used is 1.02, the material hardness when cured is 33 ° (Asuka C), and the rebound resilience is 60%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 1.

  The developing roller was the same as in Example 1 except that the specific gravity of the silicone rubber material used was 1.07, the material hardness when cured was 41 ° (Asuka C), and the rebound resilience was 63%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 1.

  The developing roller was the same as in Example 1 except that the specific gravity of the silicone rubber material used was 1.10, the material hardness when cured was 43 ° (Asuka C), and the rebound resilience was 61%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 1.

  Developing roller in the same manner as in Example 1 except that the specific gravity of the silicone rubber material used is 1.06, the material hardness when cured is 33 ° (Asker C), and the rebound resilience is 53%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 1.

  The developing roller is the same as in Example 1 except that the specific gravity of the silicone rubber material used is 1.03, the material hardness when cured is 26 ° (Asker C), and the rebound resilience is 50%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 1.

The developing roller is the same as in Example 1 except that the specific gravity of the silicone rubber material used is 1.08, the material hardness when cured is 56 ° (Asker C), and the rebound resilience is 75%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 1.
(Comparative Example 1)
Developing roller in the same manner as in Example 1 except that the specific gravity of the silicone rubber material used is 1.01, the material hardness when cured is 47 ° (Asker C), and the rebound resilience is 78%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 2. However, with this roller, “debris” was generated during continuous durability of 10,000 sheets, and it was impossible to evaluate the adhesion between the image of the development stripe and the surface layer.
(Comparative Example 2)
The developing roller was the same as in Example 1 except that the specific gravity of the silicone rubber material used was 1.03, the material hardness when cured was 46 ° (Asker C), and the rebound resilience was 78%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 2.
(Comparative Example 3)
The developing roller is the same as in Example 1 except that the specific gravity of the silicone rubber material used is 1.27, the material hardness when cured is 70 ° (Asker C), and the rebound resilience is 82%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 2.
(Comparative Example 4)
Developing roller in the same manner as in Example 1 except that the specific gravity of the silicone rubber material used is 1.01, the material hardness when cured is 31 ° (Asker C), and the rebound resilience is 52%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 2. However, with this roller, “debris” was generated during continuous durability of 10,000 sheets, and it was impossible to evaluate the adhesion between the image of the development stripe and the surface layer.
(Comparative Example 5)
Developing roller in the same manner as in Example 1 except that the specific gravity of the silicone rubber material used is 1.16, the material hardness when cured is 48 ° (Asker C), and the rebound resilience is 76%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 2.
(Comparative Example 6)
Developing roller in the same manner as in Example 1 except that the specific gravity of the silicone rubber material used is 1.01, the material hardness when cured is 12 ° (Asker C), and the rebound resilience is 26%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 2. However, this roller generated “scratch” during continuous durability of 10,000 sheets, and the adhesion between the image of the development streak and the surface layer could not be evaluated.
(Comparative Example 7)
The developing roller is the same as in Example 1 except that the specific gravity of the silicone rubber material used is 1.04, the material hardness when cured is 16 ° (Asker C), and the rebound resilience is 30%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 2.
(Comparative Example 8)
The developing roller is the same as in Example 1 except that the specific gravity of the silicone rubber material used is 1.27, the material hardness when cured is 37 ° (Asker C), and the rebound resilience is 42%. Was made. Measurement and evaluation were performed in the same manner as in Example 1, and the results are summarized in Table 2.

  The developing roller of the present invention can provide a developing roller having high ability for banding and image streaking by defining the rebound resilience and specific gravity used for the elastic layer.

  That is, the present invention uses a material having a low rebound elastic modulus in an electrophotographic image forming apparatus such as an electrophotographic copying apparatus, a printer, and an electrostatic recording apparatus in order to eliminate banding due to rotation unevenness of a developing roller driving mechanism. In addition, an electrophotographic process cartridge and an electrophotographic image having a developing roller capable of obtaining a high-definition image without an image streak caused by deformation of a contact portion caused by long-term contact with the layer thickness regulating member by optimizing specific gravity A forming apparatus can be provided.

It is a conceptual sectional view of a developing roller showing an embodiment of the present invention. It is a conceptual perspective view of the developing roller showing an embodiment of the present invention. 1 is a schematic diagram illustrating an example of an electrophotographic image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft core body 2 Elastic layer 3 Surface layer 4 Primary charging roller 5 Photosensitive drum 6 Elastic blade 7 Fixing roller 8 Pressure roller 9 Transfer roller 10 Recording medium 11 Developing roller 12 Developer supply roller 13 Developer container 14 Developer 15 Developer Layer thickness regulating member 16 Laser light 17 Stirring blade

Claims (6)

In a developing roller comprising: forming at least one elastic layer on the outer periphery of a metal shaft core, and further providing a resin layer on the outer periphery of the elastic layer;
A developing roller characterized in that the rubber material constituting the elastic layer has a rebound resilience of 50 to 75% and a specific gravity of 1.02 to 1.10.   The developing roller according to claim 1, wherein the rubber material has a hardness (Asker C) of 27 ° to 55 °.   The developing roller according to claim 1, wherein the rubber material is silicone rubber. The silicone rubber is
(A) 100 parts by weight of an organopolysiloxane having at least two alkenyl groups in one molecule;
(B) An organohydrogensiloxane having hydrogen atoms directly bonded to at least two silicon atoms in one molecule (total number of hydrogen atoms directly bonded to silicon atoms) / (total number of alkenyl groups in component (A)) is 0. Parts by weight of 5 to 1.5,
(C) 5-50 parts by weight of the total amount of conductive agent and non-conductive filler,
(D) an amount sufficient to cure the catalyst composition;
The developing roller according to claim 3, wherein the developing roller is a curable composition containing an essential component. A developing roller is mounted, a thin layer of developer is formed on the surface of the developing roller, the developer is supplied to the surface of the image forming body by bringing the developing roller into contact with the image forming body, and the image forming body In an electrophotographic process cartridge that forms a visible image on the surface,
An electrophotographic process cartridge, wherein the developing roller is the developing roller according to claim 1. A developing roller is mounted, a thin layer of developer is formed on the surface of the developing roller, the developer is supplied to the surface of the image forming body by bringing the developing roller into contact with the image forming body, and the image forming body In the electrophotographic image forming apparatus for forming a visible image on the surface,
An electrophotographic image forming apparatus, wherein the developing roller is the developing roller according to claim 1.

Images