JP2008249985A - Developing roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller having excellent toner conveyance, suppressing toner deterioration and filming, and ensuring high-quality copy for a long term. <P>SOLUTION: The developing roller includes: a base rubber layer 2 on the peripheral face of a shaft body; an intermediate layer 3 formed on the periphery of the base rubber layer 2 directly or via other layer; and a surface layer 4 formed on the periphery of the intermediate layer 3. The intermediate layer 3 is formed from a polymer composition containing the following components (A) to (C): (A) a binder polymer; (B) particles for roughening surface (particles 1); (C) at least one surface modifying agent selected from a group consisting of a silicone surface modifying agent, fluorine surface modifying agent, acrylic fluorine surface modifying agent, acrylic silicone surface modifying agent, and acrylic fluorine silicone surface modifying agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing roll used in an electrophotographic apparatus such as an electrophotographic copying machine or a printer.

  A developing roll of an electrophotographic copying machine or the like is required to have predetermined toner chargeability and toner transportability. For this reason, it is important to uniformly roughen the roll surface. Such a developing roll is usually constituted by forming a surface resin layer directly or via an intermediate elastic layer on the surface of a base roll formed by forming a base rubber layer on the outer periphery of the core metal. In order to obtain a developing roll having a uniformly roughened roll surface, conventionally, the outer peripheral surface of the base roll formed by forming a base rubber layer on the outer periphery of the core metal is subjected to shot blasting or polishing. By roughening the outer peripheral surface, or by subjecting the inner peripheral surface of the base rubber layer molding die to rough surface processing by shot blasting in advance and transferring the roughness during base rubber layer molding, The surface resin layer is formed by coating so that the outer peripheral surface of the roll is roughened and along the rough surface.

  However, in recent years, there has been a high demand for lowering the hardness of the developing roll, and accordingly, the base rubber layer has also been reduced in hardness, so even if shot blasting or the like is performed on the outer peripheral surface of the base roll It is difficult to roughen the surface uniformly as required. On the other hand, when roughening the outer peripheral surface of the base roll by transferring the rough surface of the inner peripheral surface of the base rubber layer molding die, the surface roughness of the inner peripheral surface of the mold cannot be easily changed. In addition, it is difficult to obtain the surface roughness of the roll while finely adjusting to cope with changes in surface performance and roughness required by diversification of toner and toner.

  For this reason, in recent years, developing rolls having a surface roughness by applying a coating liquid (coating liquid) in which a filler for forming roughness is dispersed on the outer peripheral surface of the base roll are becoming mainstream. As such a roll, a developing roll in which a large number of particles are dispersed in a coating solution for forming a surface layer to give a surface roughness is common. Some of them may be partially exposed without being completely covered with the film made of the coating solution, and even if the particles are not partially exposed, Since the convex portions on the surface are formed by the particles, the film covering the particles may be scraped off by using a roll, and the particles may be exposed. When the particles are exposed in this manner, uneven charging tends to occur.

  In addition, when the roughness is formed on the surface layer as described above and the uniformity of the roughness is to be ensured, the hardness difference between the particle portion and the non-particle portion of the surface layer becomes remarkable because the particles themselves have high hardness. The toner stress locally increases. For this reason, there is a problem that toner deterioration and filming progress and toner charging performance is lowered (fogging), and image defects such as lines and ghosts are likely to be induced.

In order to solve these problems, the applicant of the present invention provides an intermediate layer between the base rubber layer and the surface layer, and does not put particles for surface roughness formation on the surface layer as described above. The roll which put the particle for surface roughness formation in the lower intermediate layer was proposed previously (refer to patent documents 1).
JP 2002-357949 A

  However, in the proposed developing roll, sometimes, as shown in FIG. 3, when the surface layer 24 is formed by coating, the uneven surface (formed by the surface roughness forming particles 21) formed on the intermediate layer 23. The coating liquid of the coating flows into the concave portion of the uneven surface (flows in the direction of the arrow in the figure), and the roughness of the surface layer 24 surface becomes smaller than the roughness of the surface of the intermediate layer 23, and the roughness Phenomenon that the variation of the becomes large occurs. In such a case, a minute recess is hidden, and only a rough surface roughness can be formed on the roll surface. In some cases, this causes unevenness in the amount of toner transported, There is a possibility that the toner transportability is lowered and the copy image quality is lowered. Therefore, it is awaited to provide a developing roll that can sufficiently meet the advanced demands such as full color and high image quality of electrophotographic copying machines.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a developing roll that is excellent in toner transportability, suppresses toner deterioration and filming, and can realize high-quality copying over a long period of time. .

In order to achieve the above object, the developing roll of the present invention comprises a shaft, a base rubber layer formed on the outer periphery thereof, and an intermediate layer formed on the outer periphery of the base rubber layer directly or via another layer. And a developing roll comprising a surface layer formed on the outer periphery of the intermediate layer, wherein the intermediate layer is formed of a polymer composition containing the following components (A) to (C): Take.
(A) Binder polymer.
(B) Particles for forming surface roughness.
(C) At least one selected from the group consisting of a silicone surface modifier, a fluorine surface modifier, an acrylic fluorine surface modifier, an acrylic silicone surface modifier, and an acrylic fluorine silicone surface modifier Surface modifiers.

  That is, the inventors of the present invention have made extensive studies in order to solve the above-described problems, and in the course of the research, the above-described proposed developing roll (particles for forming the surface roughness of the intermediate layer disclosed in JP-A-2002-357949). In the developing roll roughened by the above-mentioned method, research was repeated focusing on controlling the phenomenon shown in FIG. As a result, when the intermediate layer is formed by blending the specific surface modifier shown in the above (C) in the composition for forming an intermediate layer in advance, coating the resulting coating liquid, and drying it, The silicone component or fluorine component constituting the specific surface modifier is exposed on the surface of the intermediate layer, and the surface of the intermediate layer is modified (the surface energy is reduced). It was found that when the surface layer coating liquid was applied, the coating liquid was prevented from spreading out. This suppresses the phenomenon that the surface layer coating liquid flows into the recesses of the intermediate layer in a concentrated manner, and the surface layer coating film is formed with a uniform thickness in a shape along the uneven shape of the surface of the intermediate layer. It is possible to suppress a decrease in the surface roughness of the surface layer relative to the surface roughness.

  As described above, the developing roll of the present invention includes a base roll, an intermediate layer formed on the outer periphery thereof directly or via another layer, and a surface layer formed on the outer periphery of the intermediate layer, The layer is formed of a polymer composition containing a binder polymer, surface roughness forming particles, and a specific surface modifier as essential components. As a result, a desired uneven shape is formed on the surface of the intermediate layer, and a surface coating film is formed with a uniform thickness in a shape along the uneven shape, so that the developing roll has excellent toner transportability. The local hardness difference can be reduced, toner deterioration and filming can be suppressed, and high-quality copying can be realized over a long period of time. In addition, since the surface roughness forming particles are difficult to be exposed, there are no restrictions on chargeability and wear resistance, and the range of particle selection can be expanded. Furthermore, even if the content of the surface roughness forming particles in the intermediate layer is small, the same level of roughness as in the conventional case can be obtained, and the roll hardness can be reduced. By reducing the roll hardness in this way, there is no risk of causing toner fog on the photosensitive drum, and while maintaining the above-mentioned reduction in hardness, not only the overall toner transportability but also fineness Since the toner transportability can also be secured, it is possible to sufficiently meet the demands for full color and high image quality of electrophotographic copying machines.

  In particular, when the average particle diameter of the particles in the intermediate layer is set in a specific range, the toner transportability is further ensured, and thus a clearer printed image can be obtained.

  Further, when the ratio of the surface modifier in the intermediate layer forming composition is set within a specific range, the suppression of the phenomenon that the surface layer coating liquid flows into the recesses of the intermediate layer is more excellent. As a result, the thickness of the surface coating film is suitably adjusted.

  Further, when the ratio of the surface roughness forming particles in the intermediate layer forming composition is set within a specific range, the developing roll has an excellent balance between low hardness and toner transportability. .

  Next, embodiments of the present invention will be described in detail.

  For example, as shown in FIG. 1, the developing roll of the present invention is formed on a shaft body 5, a base rubber layer 2 formed along the outer peripheral surface of the shaft body 5, and an outer periphery of the base rubber layer 2. The intermediate layer 3 and the surface layer 4 formed on the outer periphery of the intermediate layer 3 are provided. And FIG. 2 is the figure which expanded the principal part (lamination | stacking part), and the surface roughness formation particle | grains (particle | grains 1) are disperse | distributed to the said intermediate | middle layer 3, Thereby, desired uneven | corrugated shape is formed on the roll surface. Is formed. In the present invention, the intermediate layer 3 forming composition is characterized by containing a specific surface modifier, and the intermediate layer 3 is formed by coating the composition. The phenomenon (see FIG. 3) that the coating liquid for forming the surface layer 4 concentrates and flows into the recesses is suppressed, and as shown in FIG. 2, the surface layer has a uniform thickness along the surface of the intermediate layer 3 and has a uniform thickness. 4 is formed.

  The shaft body 5 is not particularly limited. For example, a metal hollow body or solid body is used. Examples of the material include stainless steel and aluminum. In order to improve the adhesiveness of the base rubber layer, an adhesive agent, a primer, or the like may be applied to the outer peripheral surface of the shaft body 5 as necessary. The adhesive agent, the primer, etc. may be electrically conductive as necessary. May be used.

The base rubber layer 2 formed on the outer peripheral surface of the shaft body 5 is formed of, for example, ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, polyurethane elastomer, or the like. Especially, as a forming material of the said base rubber layer 2, it is preferable to use an electroconductive silicone rubber from the point that it is low hardness and there is little sag. In addition, various additives such as a conductive agent and silicone oil are appropriately blended with this material. Various conductive agents such as carbon black, graphite, potassium titanate, iron oxide, c-TiO ₂ , c-ZnO, c-SnO ₂ (where “c-” means conductivity) Can be given. Examples of the silicone oil include various types such as dimethyl silicone oil.

The intermediate layer 3 formed on the outer peripheral surface of the base rubber layer 2 is formed of a polymer composition containing the following components (A) to (C).
(A) Binder polymer.
(B) Particles for forming surface roughness.
(C) At least one selected from the group consisting of a silicone surface modifier, a fluorine surface modifier, an acrylic fluorine surface modifier, an acrylic silicone surface modifier, and an acrylic fluorine silicone surface modifier Surface modifiers.

  The binder polymer for the component (A) is not particularly limited. For example, EPDM, SBR, acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile rubber (H-NBR), polyurethane elastomer, polyester, N-methoxy Methylated nylon or the like is preferably used. In addition to the above components, a conductive agent such as carbon black, metal oxide, quaternary ammonium salt, and borate may be appropriately added as necessary.

  The material for forming the surface roughness forming particle (particle 1) of the component (B) is not particularly limited. For example, silica, urethane resin, polyamide resin, fluororesin, acrylic resin, urea resin, poly Examples thereof include methyl methacrylate (PMMA). These may be used alone or in combination of two or more. Among these, silica that can highly charge the toner is preferably used.

  Moreover, the average particle diameter of the particles 1 is not particularly limited, but is preferably set in a range of 10 to 30 μm, and more preferably in a range of 10 to 20 μm. In other words, if it is set within this range, the toner transportability is further ensured, so that a clearer printed image can be obtained. The average particle diameter of the particles 1 is a value derived using a sample arbitrarily extracted from the population. In addition, if the particle size is not uniform, as in the case of a particle shape that is not a true sphere but an elliptical sphere (a sphere with an elliptical cross section), the simple average value of the longest diameter and the shortest diameter is the particle diameter of the particle. To do.

  The ratio of the particles 1 in the composition for forming the intermediate layer 3 may be set in the range of 10 to 40 parts with respect to 100 parts by weight (hereinafter referred to as “parts”) of the binder polymer of the component (A). preferable. More preferably, it is the range of 10-25 parts. In other words, when it is set within this range, the developing roll has an excellent balance between low hardness and toner transportability.

  The surface modifier of the component (C) is a characteristic material of the present invention. As described above, the silicone-based surface modifier, the fluorine-based surface modifier, the acrylic fluorine-based surface modifier, and the acrylic silicone. A surface modifier and an acrylic fluorine silicone surface modifier are used. These may be used alone or in combination of two or more. The surface modifiers are commercially available products such as Megafac F-480SF and Megafac F-178K manufactured by Dainippon Ink & Chemicals, Inc., LSI-60 and LF-700 manufactured by Soken. It is done.

  The ratio of the surface modifier of the component (C) in the composition for forming the intermediate layer 3 should be set in the range of 0.5 to 15 parts with respect to 100 parts of the binder polymer as the component (A). Is preferred. More preferably, it is the range of 0.5-10 parts. In other words, when it is set within this range, the phenomenon that the surface coating solution flows into the recesses of the intermediate layer is more suppressed, and the thickness of the surface coating film is suitably made uniform. Because it becomes like this.

  And each material for the said intermediate | middle layer 3 formation is melt | dissolved etc. in the organic solvent (except particle | grains 1), and is used as a coating liquid. Examples of the organic solvent include methyl ethyl ketone (MEK), methanol, toluene, isopropyl alcohol, methyl cellosolve, dimethylformamide and the like. These may be used alone or in combination of two or more. In particular, it is preferable to use methyl ethyl ketone in terms of solubility in the intermediate layer 3 forming material. Such a coating liquid preferably has a viscosity of 0.02 to 0.10 Pa · s from the viewpoint of coating property and the like.

  The material for forming the surface layer 4 formed on the outer periphery of the intermediate layer 3 is not particularly limited, and examples thereof include urethane resin, polyamide resin, acrylic resin, acrylic silicone resin, butyral resin (PVB) and the like. These may be used alone or in combination of two or more. Of these, urethane resins are preferably used in terms of wear resistance. In addition to the above components, a conductive agent, a charge control agent and the like may be appropriately added as necessary.

  The material for forming the surface layer 4 is also dissolved in an organic solvent and used as a coating liquid, like the material for forming the intermediate layer 3. Conventionally known organic solvents such as MEK are used as the organic solvent. Such a coating liquid preferably has a viscosity of 0.02 to 0.10 Pa · s from the viewpoints of coating properties, the influence on the roughness variation on the roll surface, and the like.

  The developing roll of the present invention can be produced, for example, as follows.

  That is, first, the components of the base rubber layer 2 forming material are kneaded with a kneader such as a kneader to prepare a base rubber layer 2 forming composition. Next, after setting the shaft 5 made of metal in the hollow part of the cylindrical mold and casting the composition for forming the base rubber layer 2 in the gap between the cylindrical mold and the shaft 5 The mold is covered and heated to crosslink the composition for forming the base rubber layer 2. Then, the base roll formed by forming the base rubber layer 2 on the outer peripheral surface of the shaft body 5 is obtained by removing from the cylindrical mold.

  On the other hand, each material for forming the intermediate layer 3 (excluding the particles 1) is dissolved by mixing with an organic solvent to form a solution. And the composition for intermediate | middle layer 3 formation (solution for intermediate | middle layer 3 formation) is produced by adding and mixing the said particle | grains 1 to this. In this case, since the particles 1 are hard or crosslinked, they are not dissolved in the solvent and are dispersed.

  Moreover, each material for formation of the said surface layer 4 is mixed with an organic solvent, and the composition for surface layer 4 formation (solution for surface layer 4 formation) is produced.

  And the said intermediate layer 3 formation solution is applied to the outer peripheral surface of the base rubber layer 2 in the said base roll. This coating method is not particularly limited, and conventional methods such as a dipping method, a spray method, and a roll coating method can be applied. After the coating, drying and heat treatment (vulcanization treatment, conditions: 120 to 200 ° C. × 20 to 90 minutes) are performed to remove the solvent in the solution for forming the intermediate layer 3. Form. Then, the surface layer 4 forming solution is applied to the outer peripheral surface of the intermediate layer 3. As the coating method, a conventional method can be applied as in the case of the intermediate layer 3 forming solution. Then, after the coating, drying and heat treatment (vulcanization treatment, conditions: 120 to 200 ° C. × 20 to 90 minutes) are performed to remove the solvent in the solution for forming the surface layer 4 to form the surface layer 4. To do.

  In this manner, a developing roll having a three-layer structure as shown in FIG. 1 can be produced. As shown in FIG. 2, a desired uneven shape is formed on the surface of the developing roll by the particles 1 in the intermediate layer 3. And it is preferable when it forms in a fine uneven surface so that the surface roughness (Ra) may be 0.6-1.7 micrometers in the roll surface (surface of the surface layer 4). More preferably, the surface roughness (Ra) is in the range of 0.6 to 1.0 μm. That is, if the surface roughness (Ra) is less than 0.6 μm, the surface of the surface layer 4 is too smooth, so that the supply of toner is insufficient and the desired image density may not be obtained. If the thickness (Ra) exceeds 1.7 μm, the surface roughness of the surface layer 4 is so large that the uneven surface roughness of the surface layer 4 may be uneven. In addition, the said surface roughness (Ra) is a centerline average roughness (Ra) shown by the definition and display of the surface roughness of JIS B 0601-1982.

  In this developing roll, the thickness of the base rubber layer 2 is preferably set in the range of 1 to 10 mm, particularly preferably 2 to 6 mm. Moreover, the thickness of the intermediate | middle layer 3 is set to the desired thickness in the range of 3-30 micrometers from the relationship with the particle size of the particle | grains 1, Especially preferably, it is 5-20 micrometers. And it is preferable to set the thickness of the surface layer 4 in the range of 3-30 micrometers from the point of rough surface formation based on the unevenness | corrugation of the intermediate | middle layer 3, Especially preferably, it is 5-20 micrometers. The thickness of the intermediate layer 3 indicates the thickness indicated by the arrow A in FIG. 2, that is, the thickness of the concave portion in the intermediate layer 3 formed in an uneven shape by the particles 1. Similarly, the thickness of the surface layer 4 indicates the thickness indicated by the arrow B in FIG. 2, that is, the thickness of the concave portion in the surface layer 4 formed along the unevenness of the intermediate layer 3. The thickness of each layer can be obtained by taking a cross-sectional sample including the surface layer 4, the intermediate layer 3, and the base rubber layer 2 from the developing roll, and measuring it based on the micrograph.

  As an example of the developing roll of the present invention, a three-layer structure is shown in FIG. 1, but the layer formed on the outer periphery of the shaft body 5 does not necessarily have to be three layers, depending on the use of the roll. An appropriate number of layers may be formed between the base rubber layer 2 and the intermediate layer 3 to form three or more layers.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples.

[Production of base roll]
First, a metal highly conductive core metal (diameter 8 mm) was prepared as a core metal, and an adhesive was applied to the outer peripheral surface of the core metal. Next, the core metal is set in the hollow part of the cylindrical mold, and a silicone rubber compound is poured into the gap between the cylindrical mold and the core metal, and then the mold is covered and heated. (180 ° C. × 5 minutes), the silicone rubber compound was vulcanized, and then demolded to prepare a core metal (base roll) with a base rubber layer.

(Preparation of intermediate layer forming solution)
100 parts of H-NBR (ZP2020, manufactured by Zeon Corporation), 0.5 part of fluorine graft acrylic (Aron GF-300, manufactured by Toagosei Co., Ltd.), 20 parts of carbon black, 10 parts of a crosslinking agent, and 400 parts of MEK An intermediate layer forming solution was prepared by dispersing 23 parts of particles (MX1000, manufactured by Soken Co., Ltd.) made of PMMA having an average particle diameter of 10 μm in the solution obtained by mixing, and mixing and stirring.

(Preparation of surface layer forming solution)
A surface layer forming solution was prepared by mixing 100 parts of a urethane resin (Nipporan 5199, manufactured by Nippon Polyurethane Co., Ltd.), 20 parts of carbon black, and 400 parts of MEK.

[Preparation of developing roll]
The intermediate layer forming solution was applied to the outer peripheral surface of the base roll by a roll coating method, and then dried and heated to form an intermediate layer on the outer peripheral surface of the base rubber layer. Furthermore, after the surface layer forming solution was applied to the outer peripheral surface of the intermediate layer by a roll coating method, drying and heat treatment were performed to form a surface layer on the outer peripheral surface of the intermediate layer. In this way, a developing roll having a three-layer structure was produced (see FIG. 1). The thickness of the base rubber layer of this roll is 4 mm, the thickness of the intermediate layer (thickness indicated by arrow A in FIG. 2) is 10 μm, and the thickness of the surface layer (thickness indicated by arrow B in FIG. 2) is 10 μm. is there.

  The content of fluorine-grafted acrylic in the intermediate layer forming solution was 1.0 part. Otherwise, a developing roll was produced in the same manner as in Example 1.

  The content of the fluorine graft acrylic in the intermediate layer forming solution was 5 parts. Otherwise, a developing roll was produced in the same manner as in Example 1.

  The content of fluorine-grafted acrylic in the intermediate layer forming solution was 10 parts. Otherwise, a developing roll was produced in the same manner as in Example 1.

  Instead of the fluorine graft acrylic in the intermediate layer forming solution, 5 parts of silicone graft acrylic (GS30, manufactured by Toagosei Co., Ltd.) was used. Otherwise, a developing roll was produced in the same manner as in Example 1.

  Instead of the fluorine graft acrylic in the intermediate layer forming solution, 5 parts of silicone graft acrylic (manufactured by Soken Co., Ltd., LSI-60) was used. Otherwise, a developing roll was produced in the same manner as in Example 1.

  Instead of the fluorine graft acrylic in the intermediate layer forming solution, 5 parts of a perfluoroalkyl group-containing oligomer (manufactured by Dainippon Ink & Chemicals, Inc., MegaFac F-178K) was used. Otherwise, a developing roll was produced in the same manner as in Example 1.

  Instead of fluorine-grafted acrylic in the intermediate layer forming solution, 5 parts of acrylic fluorine (manufactured by Soken Co., Ltd., LF700) was used. Otherwise, a developing roll was produced in the same manner as in Example 1.

  Instead of fluorine graft acrylic in the intermediate layer forming solution, 5 parts of silicone graft acrylic (manufactured by Soken Co., Ltd., LSI-60) was used, and the content of PMMA particles in the intermediate layer forming solution was 18 parts. . Other than that was carried out similarly to Example 1, and produced the image development roll.

  The content of PMMA particles in the intermediate layer forming solution was 13 parts. The content of the fluorine graft acrylic in the intermediate layer forming solution was 5 parts. Other than that was carried out similarly to Example 1, and produced the image development roll.

  The content of PMMA particles in the intermediate layer forming solution was 17 parts. Then, 5 parts of silicone graft acrylic (manufactured by Toagosei Co., Ltd., GS30) was used in place of the fluorine graft acrylic in the intermediate layer forming solution. Other than that was carried out similarly to Example 1, and produced the image development roll.

  The content of PMMA particles in the intermediate layer forming solution was 15 parts. Then, 5 parts of acrylic fluorine (manufactured by Soken Co., Ltd., LF700) was used in place of the fluorine graft acrylic in the intermediate layer forming solution. Other than that was carried out similarly to Example 1, and produced the image development roll.

  The content of PMMA particles in the intermediate layer forming solution was 15 parts. Then, 5 parts of acrylic fluorine silicone (manufactured by Toagosei Co., Ltd., Aron GF-150) was used in place of the fluorine graft acrylic in the intermediate layer forming solution. Other than that was carried out similarly to Example 1, and produced the image development roll.

[Comparative Example 1]
Fluorine graft acrylic in the intermediate layer forming solution was not included. Other than that was carried out similarly to Example 1, and produced the image development roll.

[Comparative Example 2]
The PMMA particles and fluorine-grafted acrylic in the intermediate layer forming solution were excluded (the intermediate layer had a thickness of 10 μm and no irregularities). Then, in the surface layer forming solution, 10 parts of the PMMA particles were dispersed in the solution to form a surface layer (the surface layer had a thickness of 10 μm and had irregularities). Other than that was carried out similarly to Example 1, and produced the image development roll.

  Each developing roll thus obtained was measured and evaluated for each characteristic according to the following criteria. These results are shown together in Tables 1 and 2 below.

[Surface roughness (Ra)]
The surface roughness (μm) of the intermediate layer in the developing roll (roughness Ra of the roll surface before forming the surface layer) and the surface roughness (μm) (roughness Ra of the developing roll surface) of Surfcom (manufactured by Tokyo Seimitsu Co., Ltd.) Then, it was measured according to JIS B 0601. In addition, the said surface roughness (Ra) is a centerline average roughness (arithmetic average roughness) shown by the definition and display of the surface roughness of JIS B 0601-1982. Further, in order to see the extent to which the intermediate layer surface roughness is reflected on the surface of the surface layer, ΔRa (intermediate layer surface roughness−surface layer surface roughness), which is the difference, was calculated.

[Roll surface hardness]
The surface hardness (°) of the developing roll was measured using a micro rubber hardness meter MD-1 type (manufactured by Kobunshi Keiki Co., Ltd.).

[Image density]
The developing roll was incorporated into a laser beam printer (LBP5200 manufactured by Canon Inc.), and character printing was performed. The printed image had no problem in density, and the printed image was evaluated as “◯” until it reached the fine line.

[Roughness change]
After the developing roll was incorporated into a laser beam printer (Canon LBP5200) and 8000 images were printed (after endurance), the roughness (Ra) of the developing roll surface was measured with JIS B at Surfcom (Tokyo Seimitsu Co., Ltd.). Measured according to 0601. And the variation | change_quantity (difference) of the roughness (Ra) after the said durability with respect to initial stage roll surface roughness (Ra) was computed. The amount of change required for the present invention is 0.20 μm or less.

[Toner transport amount change]
Prepare an initial and post-endurance development roll, assemble it into a cartridge, and rotate it idle at the same speed as the actual machine to form a toner layer on the roll surface, transfer the toner on the roll surface to the tape, The toner weight (mg / cm ² ) per unit area was measured. Then, with respect to the toner weight (toner transport amount) of the initial roll, the change rate of the toner weight (toner transport amount) due to the durable roll was evaluated as ○, and the change rate of 20% or more was evaluated as ×.

[Toner Filming Resistance]
The presence or absence of occurrence of toner filming in the developing roll after the endurance was visually determined. The toner filming was such that no toner filming occurred at all, the toner filming at a slight level causing no trouble in actual use was found, and the toner filming that caused trouble in actual use occurred. Things were rated as x.

[Anti-fogging resistance]
Printing was performed again with the development roller after the endurance incorporated in a laser beam printer (LBP5200 manufactured by Canon Inc.), and the print image was not fogged (the toner was flying where there was no image). A thing was evaluated as ○, and a thing with fogging was evaluated as ×.

  From the results in the above table, it can be seen that all the products of the Examples have a smaller difference between the intermediate layer surface roughness and the surface layer surface roughness than that of Comparative Example 1. As a result, the example product (the product of the present invention) can obtain the surface roughness of the surface layer equivalent to the conventional level even if the addition amount of the roughness forming particles to be added to the intermediate layer is reduced. The surface hardness can be reduced, and the effect of suppressing toner deterioration due to durable use can be easily obtained. In Examples 9 to 13, the change in roughness (Ra) after endurance use with respect to the initial roll surface roughness (Ra) is small, and the change in toner transport amount due to endurance use is also small. It can be seen that the evaluation of fog resistance is excellent and a high-quality printed image can be obtained over a long period of time.

  On the other hand, the product of Comparative Example 1 which does not contain a specific surface modifier (fluorine graft acrylic) in the intermediate layer forming composition forms the desired surface roughness. In addition, the difference between the intermediate layer surface roughness and the surface layer surface roughness is large. And, since the desired surface roughness was formed as described above, excellent image density was obtained in the initial stage, but the change in roughness after durable use with respect to the initial roll surface roughness was large, and durability was It can be seen that the change in the toner conveyance amount due to use is large, and the evaluation of toner filming resistance and fog resistance is inferior. On the other hand, the comparative example 2 product which did not contain the surface roughness forming particles in the intermediate layer and formed the desired surface roughness by dispersing the surface roughness forming particles in the surface layer was also excellent in the initial stage. Although the image density was obtained, the change in the roughness after durable use with respect to the initial roll surface roughness was large, the change in the toner transport amount due to durable use was also large, and the evaluation of toner filming resistance and fog resistance was poor. I understand.

It is sectional drawing which shows an example of the image development roll of this invention. It is a principal part enlarged view which shows an example of the layer formation state in the image development roll of this invention. It is a principal part enlarged view which shows an example of the layer formation state in the conventional image development roll.

Explanation of symbols

1 particle 2 base rubber layer 3 intermediate layer 4 surface layer

Claims (5)

A shaft body, a base rubber layer formed on the outer periphery thereof, an intermediate layer formed on the outer periphery of the base rubber layer directly or via another layer, and a surface layer formed on the outer periphery of the intermediate layer A developing roll, wherein the intermediate layer is formed of a polymer composition containing the following components (A) to (C):
(A) Binder polymer.
(B) Particles for forming surface roughness.
(C) At least one selected from the group consisting of a silicone surface modifier, a fluorine surface modifier, an acrylic fluorine surface modifier, an acrylic silicone surface modifier, and an acrylic fluorine silicone surface modifier Surface modifiers.   The developing roll according to claim 1, wherein the average particle diameter of the particles of the component (B) is set in a range of 10 to 20 µm.   The ratio of the component (C) surface modifier in the intermediate layer forming composition is set in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder polymer (A). The developing roll according to claim 1 or 2.   The ratio of the particle | grains of (B) component in the said composition for intermediate | middle layer formation is set to the range of 10-40 weight part with respect to 100 weight part of binder polymers which are (A) component. The developing roll according to any one of the above.   The binder polymer of component (A) is ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile rubber (H-NBR), polyurethane elastomer, polyester The developing roll according to claim 1, which is at least one selected from the group consisting of N-methoxymethylated nylon and N-methoxymethylated nylon.

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