JP4613641B2 - Charging roll manufacturing method - Google Patents

Description

The present invention relates to a copying machine, the charging roll to be used in electrophotographic apparatuses such as a printer process.

  In general, copying in an electrophotographic apparatus forms a document image as an electrostatic latent image on the surface of a photosensitive drum, forms a toner image by attaching toner to the electrostatic latent image, and transfers the toner image onto a copy sheet. This is done by fixing. In this case, in order to form an electrostatic latent image on the surface of the photosensitive drum, the surface of the photosensitive drum is charged in advance, and a document image is projected onto the charged portion via the optical system, and is exposed to light. For example, an electrostatic latent image is formed by canceling the charging of the portion. As a method for charging the surface of the photosensitive drum prior to the formation of the electrostatic latent image, a roll charging method for charging the surface of the photosensitive drum by directly contacting the charging roll with the surface of the photosensitive drum is employed.

  However, with the recent increase in speed of copying, there has been a problem that the charging roll and the photosensitive drum are vibrated, and the charging noise generated near the contact portion between the charging roll and the photosensitive drum is increased. Further, along with the improvement in durability of electrophotographic apparatuses, there is a problem that, when used for a long period of time, not only the toner adheres to the outer peripheral surface of the charging roll but also becomes uneven and adversely affects charging.

As a measure for suppressing the charging noise, a measure is taken to absorb vibration of the charging roll or the like by reducing the hardness of the conductive layer of the charging roll. In addition, as a countermeasure against the toner adhesion, a countermeasure is adopted in which the outer peripheral surface of the charging roll is roughened to make the toner adhesion uniform. There are various methods for roughening the surface of the coating layer, for example, by dispersing hard particles (sandy particles) such as urethane resin in the coating layer with respect to the developing roll instead of the charging roll. A method of roughening the surface has been proposed (see Patent Document 1).
JP-A-10-239985

  However, if the conductive layer of the charging roll is reduced in hardness to suppress charging noise, the contact portion with the photosensitive drum is greatly deformed, and this is repeated continuously, so that the life of the charging roll is shortened. is there. Moreover, when the developing roll of the above-mentioned patent document 1 is applied to a charging roll, the hard particles increase the surface hardness and increase the charging sound.

  Moreover, on the rough surface formed by dispersing hard particles, the surface roughness changes with time due to aggregation of the hard particles, making it difficult to maintain a uniform surface roughness over a long period of time. For this reason, when a charging roll whose outer peripheral surface is roughened with hard particles is used for a long period of time, the toner may become uneven and adhere to the outer peripheral surface of the charging roll despite the roughening of the outer peripheral surface. .

The present invention has been made in view of such circumstances, it is possible to suppress the size of the charging noise, toner adhesion can also be suppressed, the sole purpose of providing long life charge roll production method And

In order to achieve the above object, according to the present invention , after an elastic layer is formed on the outer peripheral surface of the shaft body, a cylindrical outermost layer is formed on the outer periphery of the elastic layer directly or via another layer. On the outer peripheral surface of the outer layer, a plurality of concave portions whose concave shape is a curved surface formed of a part of a substantially spherical surface is formed in the axial direction so that the opening edges do not overlap with each other to form a concave row. The recess rows are distributed in a plurality of rows at predetermined intervals in the circumferential direction to form a rough surface, the opening diameter of the recesses in each recess row is in the range of 50 to 150 μm, and the depth of each recess is 1. range of 5 to 20 [mu] m, a strip conductive roll production method of the opening edge distance to set the range of 0~20μm between the recess adjacent the recess, forming a recess in the outer peripheral surface of the outermost layer, The outer peripheral surface of the outermost layer is irradiated with a laser beam converged in a dot shape, and the spot irradiation portion The method of the charging roller to be formed in the concave portion as a first aspect, a method of the charging roller making, formation of recesses in the outer peripheral surface of the outermost layer, the outer peripheral surface of the elastic layer by electroforming The transfer recess is formed using the transferred transfer mold, and then the cylindrical outermost layer is formed directly or through another layer on the outer periphery of the elastic layer, and the outer surface of the elastic layer is formed on the outer surface. Due to the influence of the transfer recess, the second aspect is a method of manufacturing a charging roll that exposes the recess on the outer peripheral surface of the outermost layer, and the method of manufacturing the charging roll includes forming the recess on the outer peripheral surface of the outermost layer. While the transfer plate on which the convex portion corresponding to the concave portion is formed is heated, the outermost layer is pressed against the transfer plate and rolled, and the convex portion of the transfer plate is transferred to the outer peripheral surface of the outermost layer to form the concave portion. to a third aspect of the method of the charging roller to form a .

That is, the charging roll obtained by the manufacturing method of the charging roll according to the present invention has a plurality of recesses formed on the outer peripheral surface of the cylindrical outermost layer in the axial direction so that the opening edges do not overlap each other. There are rows, and the concave rows are distributed in a plurality of rows at predetermined intervals over the entire circumference in the circumferential direction to form a rough surface. Therefore, the pressure contact state with respect to the photosensitive drum is performed at the so-called surface of the portion between the recesses in the recess row, and does not make point contact like hard particles. Accordingly, the pressure of pressure contact is relaxed (in the case of a rough surface due to the dispersion of hard particles, the heights of the tops of the plurality of convex portions forming the rough surface vary, and the high tops make point contact with the photosensitive drum. (Partially increased), charging noise can be suppressed. In addition, the portion between the concave portion and the concave portion is deformed in the inner direction of the concave portion during the press contact with the photosensitive drum, thereby reducing the press contact pressure. As a result, the effect of suppressing charging noise is further improved. Further, the effect of suppressing charging noise can be obtained without reducing the hardness of the conductive layer as in the prior art. Furthermore, in the above charging roller, as described above, the rough surface forming the outer peripheral surface, and carried out by distributing the concave portion rows, not using hard particles. Thereby, since aggregation of hard particles does not occur, the surface roughness does not change with time, and the surface roughness can be maintained constant over a long period of time. In addition, the formation of the recess rows can relatively easily control the distance between the rows of the recess rows, the distribution density of the recesses in the recess rows, the size of the recesses, etc. It can be controlled relatively easily. In addition, during the durability test, excess toner is stored in the recesses, so that toner adhesion to the outer peripheral surface portion where no recesses are formed can be suppressed. It is proved that proper charging can be maintained over the entire range.

As described above, the charging roll obtained by the manufacturing method of the charging roll according to the present invention has a plurality of recesses formed on the outer peripheral surface of the cylindrical outermost layer in the axial direction with the opening edges not overlapping each other. Then, there are recess rows, and a plurality of the recess rows are distributed over the entire circumference in the circumferential direction at a predetermined interval to form a rough surface. Therefore, the pressure contact state with respect to the photosensitive drum is performed at the so-called surface of the portion between the recesses in the recess row, and does not make point contact like hard particles. Therefore, the pressure contact pressure is relieved and charging noise can be suppressed. In addition, the portion between the concave portion and the concave portion is deformed in the inner direction of the concave portion during the press contact with the photosensitive drum, thereby reducing the press contact pressure. As a result, the effect of suppressing charging noise is further improved. Further, the effect of suppressing charging noise can be obtained without reducing the hardness of the conductive layer as in the prior art. Further, when used for a long time, surplus toner can be stored in the recess, and toner adhesion to an outer peripheral surface portion where no recess is formed can be suppressed.

In the charging roll, the opening diameter of each recess is in the range of 50 to 150 μm, the depth of each recess is in the range of 1.5 to 20 μm, and the distance between the opening edges between adjacent recesses is 0 to 20 μm. Therefore, the surface can be formed to have a surface roughness suitable as a charging roll, and charging noise and toner adhesion can be more effectively suppressed.

In the charging roll, when the concave portions are regularly distributed in the circumferential direction and the axial direction, the surface roughness of the charging roll can be made more uniform, and charging noise can be suppressed and toner adhesion can be prevented. Suppression becomes easier to control.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1A and 1B show an embodiment of a charging roll obtained by the method for manufacturing a charging roll of the present invention. The charging roll of this embodiment has a round cross section (surface orthogonal to the axis) in a perfect circle shape, a cylindrical shaft body 1, and a cylindrical elastic body formed on the outer peripheral surface of the shaft body 1. The layer 2 is composed of a cylindrical intermediate layer 3 formed on the outer peripheral surface of the elastic layer 2 and a cylindrical outermost layer 4 formed on the outer peripheral surface of the intermediate layer 3. A plurality of recesses (dimples) A are formed in a row in the axial direction on the outer peripheral surface of the outermost layer 4 so that the opening edges do not overlap with each other. L is distributed in a plurality of rows at predetermined intervals over the entire circumference in the circumferential direction to form a rough surface.

In more detail, the shape of each recess A is, FIG Shimesuru so is an opening shaped substantially circular, curved shape concave shape becomes a part of a substantially spherical surface (e.g., hemispherical) Ru der. In addition, the size of each of the recesses A is such that the opening diameter D of each recess A is in the range of 50 to 150 μm from the viewpoint of more effectively suppressing charging noise and toner adhesion as a charging roll. depth F of 1.5~20μm range, and the distance between the opening edge of the adjacent recess a E is set to a range of 0～20Myuemu, is good preferred, 50 to the opening diameter D of each recess a The range is 120 μm, the depth F of each recess A is 3 to 10 μm, and the distance E between the opening edges of adjacent recesses A is 0 to 5 μm. Here, the “opening diameter D of each recess A” is expressed by an average value obtained by measuring the outer diameter of the charging roll with an electron microscope and measuring the opening diameter D of the recess A at any 10 locations. The “depth F of each recess A” is obtained by cutting the charging roll in the thickness direction, viewing the cross section with an electron microscope, measuring the depth F of the recess A at any 10 locations, and calculating the average value thereof. It is represented by Further, the “distance E between the opening edges of the adjacent recesses A” is expressed as an average value obtained by measuring the outer peripheral surface of the charging roll with an electron microscope and measuring between any 10 opening edges.

  In addition, from the viewpoint of making the surface roughness of the charging roll uniform over the entire outer periphery, it is preferable that the distribution of the recess rows L is regularly formed at equal intervals. Moreover, it is preferable that the distance E between the opening edges of adjacent recesses A is substantially the same. For example, the formation pitch of the recesses A is made constant in the circumferential direction or made constant in the axial direction.

  Such a charging roll is manufactured by a method in which the outer peripheral surface of the outermost layer 4 is subjected to laser etching, a method using a transfer mold prepared by electroforming, or a process in which convex portions are formed on the surface by laser processing or the like. Examples include a method of forming the recess A by pressing the plate in a heated state and a method of forming the recess A by irradiating light using a photoresist material.

  An example of the method for producing the charging roll will be described in more detail. First, a method of performing laser etching on the outer peripheral surface of the outermost layer 4 is performed as follows. That is, first, an adhesive or the like is applied to the outer peripheral surface of the shaft body 1 as necessary, and the forming material of the elastic layer 2 and the forming material of the intermediate layer 3 are applied to the outer peripheral surface using an extruder. Extrude. Then, the elastic layer 2 and the intermediate layer 3 are laminated in this order on the outer peripheral surface of the shaft body 1 by coaxially installing it in the hollow portion of the molding die, sealing it, and simultaneously crosslinking it. To do. The molding die used at this time preferably has a mirror surface (ten point average roughness (Rz) of 2 μm or less) due to polishing or the like. Thereby, the outer peripheral surface of the said intermediate | middle layer 3 is formed in a mirror surface. Then, after demolding, the outer layer 4 is coated on the outer peripheral surface of the intermediate layer 3 by a roll coating method, a spray coating method, a dipping method or the like, and then dried (cured) to form the outermost layer 4. Form. The outer peripheral surface of the outermost layer 4 is formed into a smooth surface by forming the outer peripheral surface of the intermediate layer 3 as a mirror surface. In this way, a roll body is obtained.

  And the recessed part A of the outer peripheral surface of the outermost layer 4 is formed by the said laser etching. When forming by laser etching, the laser beam is converged into minute dots by the lens system, and the minute concave portion A is formed by forming a spot portion having a high laser beam density on the outer peripheral surface of the outermost layer 4. can do. For example, a plurality of the lens systems are arranged in a straight line along the axial direction of the roll body, and a point-like portion where the laser beam converges in a dotted shape is formed on the outer peripheral surface of the outermost layer 4 along the axial direction. When a plurality of lines are scattered in a straight line from one end edge to the other end edge, the dotted portions can be formed in the recess A at a time, and one recess array L can be formed. Further, when the roll body is intermittently rotated around the axis, and laser light is intermittently irradiated in synchronization with the rotation, a plurality of recess rows L are distributed at predetermined intervals on the outer peripheral surface of the outermost layer 4. be able to. In the formation of the concave portion A, by adjusting the lens system, the point portions where the laser light is converged in a point shape are made to have a constant pitch, and further, the intermittent rotation of the roll body is made to have a constant angle. The concave portions A can be regularly distributed in the circumferential direction and the axial direction. Moreover, the size of the formed recess A can be set by adjusting the output of the laser beam, the irradiation time, and the like. After forming the recess A, the outer peripheral surface of the outermost layer 4 is polished as necessary. In this way, the charging roll can be produced. As the laser beam, an Nd-YAG laser or an excimer laser is usually used. The concave portion A may be formed by scanning one laser beam in the axial direction of the roll body and intermittently irradiating the laser beam during the scanning process. Further, in the case of laser etching, a laser reflecting layer to which white titanium particles or the like are added is disposed below the layer to be processed (outermost layer 4), and the laser is reflected so that the recess is formed only in the layer where the recess A is to be formed. A can also be provided.

  In the formation of the recesses A, the distribution density of the recesses A can be controlled relatively easily by adjusting the lens system in laser etching or adjusting the intermittent rotation of the roll body. Further, the size of the recess A can be controlled relatively easily by adjusting the output of the laser beam, the irradiation time, and the like. Thus, since the formation of the recess A can be controlled relatively easily, the surface roughness on the outer peripheral surface of the charging roll can also be controlled relatively easily. Further, the variation in the surface roughness can be made relatively simple, and charging noise and toner adhesion can be easily suppressed. In particular, it is possible to relatively easily form the concave portions A in the circumferential direction and the axial direction by adjusting the lens system and the intermittent rotation of the roll body. In this case, the surface roughness of the charging roll is relatively simple. Therefore, it becomes easier to control charging noise and toner adhesion.

Further, as another example of a method for producing a charging roll, a method using a transfer mold produced by the electroforming method is formed as, for example, a cylindrical shape as the transfer mold, and the concave portion is formed on the inner peripheral surface thereof. A plurality of convex portions having a shape corresponding to A are used. Then, by forming the elastic layer 2 using the transfer mold, the convex portions of the transfer mold are transferred to the outer peripheral surface of the elastic layer 2 to form the concave portions (transfer concave portions) in a distributed manner. And after demolding, after applying the formation material of the said intermediate | middle layer 3 and the outermost layer 4 in order to the outer peripheral surface of the elastic layer 2 by roll coating method, spray coating method, dipping method, etc., it is made to dry (harden), The intermediate layer 3 and the outermost layer 4 are formed. On the outer peripheral surface of the outermost layer 4, the concave portion A appears due to the influence of the concave portion (transfer concave portion) formed on the outer peripheral surface of the elastic layer 2. Even in this way, the above-mentioned charging roll can be produced (however, the charging roll obtained by this production method is different in the shape of the outer peripheral surface of the elastic layer 2 from the one shown in FIG. 1).

  The transfer mold can be produced by, for example, an electroforming method. That is, first, an aluminum cylinder having the same diameter as the target elastic layer 2 is prepared. Next, laser etching is performed on the outer peripheral surface of the aluminum cylinder to form a concave portion in the same manner as laser etching in which the concave portion A is formed on the outer peripheral surface of the outermost layer 4. The recess is formed in the same shape as the recess formed on the outer peripheral surface of the elastic layer 2. Next, using this as a prototype, it is immersed in a plating solution and subjected to electrolytic plating to form a plating layer (usually 2 to 7 mm) of nickel or the like on the surface of the prototype. Thereafter, it is removed from the plating solution, washed, dried, and the like. Then, using a chemical such as alkali, the above-mentioned prototype (aluminum cylinder having a recess formed on the outer peripheral surface) is dissolved. Thereby, the transfer mold comprising the plating layer can be obtained. On the inner peripheral surface of this transfer mold, the outer peripheral surface of the original mold (aluminum cylindrical body having a concave portion formed on the outer peripheral surface) is transferred, and a convex corresponding to the concave portion formed on the outer peripheral surface of the original mold. The part is formed. As described above, the outer peripheral surface of the original mold is transferred to the inner peripheral surface of the transfer mold, and the inner peripheral surface of the transfer mold is transferred to the outer peripheral surface of the elastic layer 2 of the charging roll. 2, the prepared aluminum cylinder has a mirror surface (ten-point average roughness (Rz) of 2 μm or less) by polishing or the like so that the outer peripheral surface portion where no concave portion is formed becomes smooth. It is preferable.

  Further, as still another example of the manufacturing method of the charging roll, a method of forming the concave portion A on the outer peripheral surface of the outermost layer 4 by pressing the transfer plate on which the convex portion corresponding to the concave portion A is heated is formed. The roll body is pressed against the heated transfer plate and rolled to transfer the convex portion of the transfer plate to the outer peripheral surface of the outermost layer 4. The transfer plate can be obtained by forming a uniform convex shape on a metal plate by laser processing or machining. Alternatively, a transfer plate having a uniform convex shape can be obtained by electroforming using a metal plate having a uniform concave shape formed by laser processing or machining as a prototype. In addition, after apply | coating the formation material of the outermost layer 4 to the outer peripheral surface of the intermediate | middle layer 3, the said transcription | transfer can be simultaneously performed by bridge | crosslinking and transcription | transfer by pressing against the said transfer plate heated at 200 degreeC.

In the charging roll thus obtained, a plurality of concave portions A are distributed and formed on the outer peripheral surface of the outermost layer 4 so that the opening edges do not overlap with each other. The outer peripheral surface portion B that is not formed maintains the original surface state (surface state before forming the recess A) and is not roughened. Then, the photosensitive drum is pressed against the above charging roller, is pressed against by (part between the recess A and the recess A in the concave portion rows L) B outer peripheral surface portion of the recess A is not formed. For this reason, the pressure contact comes into surface contact. In addition, the outermost layer 4 portion around the recess A (the portion between the recess A and the recess A) is deformed to the inside of the recess A by the pressure contact. From these things, a press-contact pressure is relieve | moderated and a charging sound can be suppressed.

In addition, the effect of suppressing the charging noise can be obtained without reducing the hardness of the conductive layer as in the prior art. That is, conventionally, in order to suppress charging noise, it has been necessary to set the hardness of the conductive layer to a low hardness of about 10 to 60%. However, like the above-described charging roll, a concave portion is formed on the outer peripheral surface of the outermost layer 4. When A is formed, the charging noise can be suppressed even if the hardness of the outermost layer 4 is about 30% higher than the conventional one. For this reason, the above-mentioned charging roll can have a longer life than the conventional one having a low hardness.

  Furthermore, the rough surface formation of the outer peripheral surface of the outermost layer 4 is performed by forming a plurality of recesses A in a distributed manner, and no hard particles are used. Thereby, since aggregation of hard particles does not occur, the surface roughness does not change with time, and the surface roughness can be maintained constant over a long period of time. When the charging roll is used for a long period of time, the toner can be stored in the concave portion A, and the toner adhesion to the outer peripheral surface portion (cylindrical remaining portion) B where the concave portion A is not formed is suppressed. be able to. As a result, proper charging can be maintained over a long period of time, and as a result, a high-quality copy image without image unevenness can be obtained.

FIG. 2 shows another embodiment of the charging roll obtained by the manufacturing method of the charging roll of the present invention. The charging roll according to this embodiment has a state in which a part of the concave part A of one concave part row L enters between the concave part A and the concave part A of the other concave part row L in the concave part row L adjacent in the circumferential direction. It has become. Other than that is the same as that of the said embodiment, and the same code | symbol is attached | subjected to the same part. If it does in this way, even if the recessed part A is comparatively large diameter (for example, 50-200 micrometers), the low hardness effect will come to be acquired.

Next, the shaft 1, an elastic layer 2 constituting the charging roller, the intermediate layer 3, the material for forming the outermost layer 4, and the like will be described.

  The shaft body 1 is not particularly limited, and may be solid or hollow. The material of the shaft body 1 is not particularly limited, and examples thereof include iron, iron plated, stainless steel, and aluminum. Then, an adhesive, a primer or the like is usually applied to the surface of the shaft body 1. Further, the adhesive, primer, etc. may be made conductive as necessary.

  In some cases, one of the elastic layer 2 and the intermediate layer 3 is formed as a foam layer and the other as a rubber layer, or both are formed as a foam layer or a rubber layer. The thickness of the elastic layer 2 is not particularly limited, but is usually set to about 2 to 4 mm, and the thickness of the intermediate layer 3 is usually set to about 0.1 to 0.5 mm.

  As the material for forming the foam layer, the following main material containing a foaming agent and a conductive agent is used. That is, the main material is not particularly limited. For example, polynorbornene rubber, ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (H-NBR). ), Styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), natural rubber (NR) and the like. These may be used alone or in combination of two or more. Moreover, you may add a crosslinking agent (sulfur, a peroxide, etc.), a crosslinking accelerator, oil, etc. suitably as needed.

  As the material for forming the rubber layer, the following main material containing a conductive agent is used. That is, the main material is not particularly limited. For example, acrylonitrile-butadiene rubber (NBR), epichlorohydrin homopolymer rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer Examples include rubber and acrylic rubber. These may be used alone or in combination of two or more. Moreover, you may add a vulcanizing agent, a vulcanization accelerator, an antistatic agent, an adjuvant, etc. suitably as needed.

  As the material for forming the outermost layer 4, the following main material containing a conductive agent is used. That is, the main material is not particularly limited, and examples thereof include polyamide resins, fluororesins, acrylic resins, urethane resins, and silicone resins. These may be used alone or in combination of two or more. And although the thickness of the said outermost layer 4 is not specifically limited, Usually, it is set to about 3-50 micrometers.

  In the above embodiment, the intermediate layer 3 may not be formed in some cases.

  Next, examples will be described together with comparative examples.

  As described below, using a transfer mold produced by electroforming, an elastic layer was formed on the outer peripheral surface of the shaft body to produce a roll body, and then an outermost layer was formed to produce a charging roll.

[Shaft]
An iron solid cylindrical shaft body having an outer diameter of 6 mm and a length of 230 mm was prepared.

[Material for forming elastic layer]
For 100 parts by weight of EPDM (EPT4045, Mitsui Chemicals), 6 parts by weight of zinc oxide (Mitsui Metals), 2 parts by weight of stearic acid (Lunac S30, Kao), carbon black (Denka Black HS) -100, manufactured by Denki Kagaku Kogyo Co., Ltd.) 10 parts by weight, paraffin oil (Diana Process PW380, manufactured by Idemitsu Petrochemical Co., Ltd.) 70 parts by weight, vulcanization accelerator (Noxeller BZ, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 2 parts by weight, A composition for forming an elastic layer was prepared by blending 3 parts by weight of a sulfur accelerator (Noxeller CZ, manufactured by Ouchi Shinsei Chemical Co., Ltd.) and 1 part by weight of sulfur (manufactured by Tsurumi Chemical Co., Ltd.) and kneading using a roll. .

[Material for forming outermost layer]
30 parts by weight of trimethylol melamine (Sumikaflex M3, manufactured by Sumitomo Chemical Co., Ltd.), Ketjen Black EC (manufactured by Ketjen Black International Co., Ltd.) per 100 parts by weight of N-methoxymethylated nylon (Toresin EF30T, Teikoku Chemical Co. ) Used at a ratio of 15 parts by weight, and mixed with 500 parts by weight of a methanol-toluene mixed solution (methanol: toluene = 7: 3) to prepare an outermost layer forming material.

[Production of transfer mold]
In the same manner as in the above-described embodiment, an aluminum cylinder having the same diameter as the outer diameter of the elastic layer was prepared, and laser etching was performed on the aluminum cylinder to form a large number of concave portions in a distributed manner. The laser etching conditions at this time are as follows: laser beam type: Nd-YAG laser, output: 50 W, and aluminum cylinder rotated at output: 30 A, frequency: 5 kHz, irradiation speed: 1030 mm / sec. The laser was irradiated to the outer peripheral surface of the aluminum cylinder with a width of 50 mm. In this way, an aluminum master roll was obtained, and a transfer mold was produced by electrocasting using the aluminum master roll.

[Production of roll body]
The elastic layer (thickness 3 mm) was formed on the outer peripheral surface of the shaft body by molding (170 ° C. × 30 minutes) using the transfer mold. Thereby, a large number of concave portions were distributed and formed on the outer peripheral surface of the elastic layer.

[Preparation of charging roll]
After forming the outermost layer forming material on the outer peripheral surface of the elastic layer by a roll coating method, the outermost layer was dried (cured) to form the outermost layer (thickness 5 μm). As a result, a charging roll having concave portions distributed and formed on the outer peripheral surface of the outermost layer was obtained. This recess formation is performed so that the opening edges of the recesses do not overlap each other, and a constant pitch in the circumferential direction and the axial direction (the distance between the opening edges of the recesses adjacent in the circumferential direction and the recesses adjacent in the axial direction). The distance between the opening edges of each was 5 μm). In addition, the shape of each concave portion was a substantially circular shape (opening diameter 150 μm), and the concave shape was a curved surface formed by a part of a substantially spherical surface (the depth of the concave portion was 5 μm). Further, the 10-point average roughness (Rz) of the outer peripheral surface of the outermost layer where no recess was formed was 2.5 μm. The ten-point average roughness (Rz) was measured using a surface roughness meter (Surfcom 1400D, manufactured by Tokyo Seimitsu Co., Ltd.) (the same applies to the following surface roughness measurements).

  As described below, a roll body having a two-layer structure was prepared using the shaft body, the material for forming each layer, and the like, and then the outer peripheral surface of the roll body was formed into a rough surface by laser etching to produce a charging roll.

[Production of roll body]
The elastic layer (thickness 3 mm) was formed in the outer peripheral surface of a shaft body by shape | molding (170 degreeC x 30 minutes) using a cylindrical metal mold | die. And after forming the outermost layer forming material on the outer peripheral surface of the elastic layer by the roll coating method, it was dried (cured) to form the outermost layer (thickness 10 μm). Thereby, the roll body was obtained. The ten-point average roughness (Rz) of the outermost layer of this roll was 2.5 μm.

[Preparation of charging roll]
By applying laser etching to the outer peripheral surface (outer peripheral surface of the outermost layer) of the roll body, a plurality of concave portions were formed in a distributed manner. This recess formation is performed so that the opening edges of the recesses do not overlap each other, and a constant pitch in the circumferential direction and the axial direction (the distance between the opening edges of the recesses adjacent in the circumferential direction and the recesses adjacent in the axial direction). The distance between the opening edges was 5 μm) (see FIG. 1). In addition, the shape of each concave portion was a substantially circular shape (opening diameter 150 μm), and the concave shape was a curved surface formed by a part of a substantially spherical surface (the depth of the concave portion was 5 μm). The laser etching conditions at this time are as follows: laser beam type: Nd-YAG laser, output: 27A, frequency: 30 kHz, irradiation speed: 3000 mm / sec. A laser was irradiated on the outer peripheral surface of the substrate. Further, the 10-point average roughness (Rz) of the outer peripheral surface of the outermost layer where no recess was formed was 2.5 μm.

  A roll body having a two-layer structure was produced in the same manner as in Example 2, and then the outer peripheral surface of the roll body was pressed against a heated transfer plate and rolled to produce a charging roll.

[Production of transfer plate]
An aluminum plate was prepared, and laser etching was performed on the aluminum plate (230 mm × 50 mm) to form a large number of concave portions in a distributed manner. The laser etching conditions at this time were laser beam type: Nd-YAG laser, output: 35 A, frequency: 5 kHz, irradiation speed: 1025 mm / second. Thus, an aluminum master plate was obtained, and a transfer plate was produced by electroforming using the aluminum master plate. A uniform convex shape was distributed on the surface of the transfer plate.

[Preparation of charging roll]
The transfer plate was heated to 200 ° C., and the roll body was uniformly pressed against the surface with a load of 98 N to roll, and the convex portions of the transfer plate were transferred to the outer peripheral surface of the outermost layer. This recess formation is performed so that the opening edges of the recesses do not overlap each other, and a constant pitch in the circumferential direction and the axial direction (the distance between the opening edges of the recesses adjacent in the circumferential direction and the recesses adjacent in the axial direction). The distance between the opening edges was 5 μm). In addition, the shape of each concave portion was a substantially circular shape (opening diameter 150 μm), and the concave shape was a curved surface formed by a part of a substantially spherical surface (the depth of the concave portion was 5 μm). Further, the 10-point average roughness (Rz) of the outer peripheral surface of the outermost layer where no recess was formed was 2.5 μm.

  In Example 1, the laser etching conditions were: output: 28 A, irradiation speed: 625 mm / sec, and the opening diameter of the recesses was 120 μm. Other than that, it was the same as in Example 1 above.

  In Example 2, the laser etching conditions were: output: 25 A, irradiation speed: 1800 mm / sec, and the opening diameter of the recess was 120 μm. Other than that was carried out similarly to the said Example 2.

  In Example 3 above, the laser etching conditions were output: 28 A, irradiation speed: 625 mm / second, and the opening diameter of the recesses was 120 μm. Other than that was carried out similarly to the said Example 3.

  In Example 1, the laser etching conditions were: output: 24.5 A, irradiation speed: 425 mm / sec, and the opening diameter of the recesses was 80 μm. Other than that, it was the same as in Example 1 above.

  In Example 2, the laser etching conditions were: output: 22 A, irradiation speed: 1300 mm / second, and the opening diameter of the recess was 80 μm. Other than that was carried out similarly to the said Example 2.

  In Example 3 above, the laser etching conditions were output: 24.5 A, irradiation speed: 625 mm / sec, and the opening diameter of the recesses was 80 μm. Other than that was carried out similarly to the said Example 3.

  In Example 4 described above, the laser etching conditions were a frequency of 5.9 kHz, an irradiation speed of 741 mm / second, and the depth of the recess in the outermost layer was 1.5 μm. Other than that was carried out similarly to the said Example 4.

  In Example 4 described above, the laser etching conditions were a frequency: 3.7 kHz, an irradiation speed: 460 mm / second, and the depth of the recess in the outermost layer was 10 μm. Other than that was carried out similarly to the said Example 4.

  In Example 4 described above, the laser etching conditions were a frequency of 1.0 kHz, an irradiation speed of 120 mm / second, and the depth of the recess in the outermost layer was 20 μm. Other than that was carried out similarly to the said Example 4.

  In Example 1, a # 400 stainless steel wire mesh (having a hole diameter of about 30 μm) was placed on an aluminum cylinder, and laser etching was performed thereon. Further, by setting the laser etching conditions to output: 24.5 A, frequency: 1 kHz, irradiation speed: 100 mm / second, the opening diameter of the recess formed on the outer peripheral surface of the outermost layer was set to 50 μm. Other than that, it was the same as in Example 1 above.

  In the same manner as in Example 4 above, using a transfer mold, an elastic layer was formed on the outer peripheral surface of the shaft body to produce a roll body, and then the following intermediate layer forming material was formed on the outer peripheral surface of the elastic layer. Was coated by a roll coating method and then crosslinked (170 ° C. × 30 minutes) to form an intermediate layer (thickness 0.3 mm). Then, the outermost layer was formed on the outer peripheral surface of the intermediate layer in the same manner as in Example 4 to produce a charging roll. The ten-point average roughness (Rz) of the outer peripheral surface of the outermost layer where no recess was formed was 2.5 μm.

[Formation material of intermediate layer]
For 100 parts by weight of NBR (N239SV, manufactured by JSR), 5 parts by weight of zinc oxide (made by Mitsui Kinzoku Co., Ltd.), 1 part by weight of stearic acid (Lunac S30, manufactured by Kao Corporation), carbon black (Denka Black HS- 100, manufactured by Denki Kagaku Kogyo Co., Ltd.) 40 parts by weight, silica (Nipseal ER, manufactured by Tosoh Silica Co., Ltd.) 35 parts by weight, vulcanization accelerator (Noxeller DM, manufactured by Ouchi Shinsei Chemical) 1 part by weight, vulcanization accelerator ( Noxeller TRA, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts by weight and sulfur (manufactured by Tsurumi Chemical Co., Ltd.) 1 part by weight were blended and kneaded using a kneader to prepare an intermediate layer forming material.

  As described below, a roll body having a three-layer structure is produced using the shaft body, the material for forming each layer, and the outer peripheral surface of the roll body is formed into a rough surface by laser etching in the same manner as in Example 5. Then, a charging roll was produced. The ten-point average roughness (Rz) of the outer peripheral surface of the outermost layer where no recess was formed was 2.5 μm.

[Production of roll body]
The elastic layer (thickness 3 mm) was formed in the outer peripheral surface of a shaft body by shape | molding (170 degreeC x 30 minutes) using a cylindrical metal mold | die. And after forming the formation material of an intermediate | middle layer on the outer peripheral surface of the elastic layer by the roll coating method, it was made to bridge | crosslink (170 degreeC x 30 minutes), and the intermediate | middle layer (thickness 0.3mm) was formed. And after forming the formation material of the outermost layer by the roll coating method on the outer peripheral surface of the intermediate layer, it was dried (cured) to form the outermost layer (thickness 10 μm). Thereby, the roll body was obtained. The ten-point average roughness (Rz) of the outermost layer of this roll was 2.5 μm.

  A roll body having a three-layer structure was produced in the same manner as in Example 15, and then the outer peripheral surface of the roll body was pressed against a heated transfer plate and rolled in the same manner as in Example 6 to produce a charging roll. The ten-point average roughness (Rz) of the outer peripheral surface of the outermost layer where no recess was formed was 2.5 μm.

[Comparative Example 1]
In Example 2 described above, the following (with particles) was used as the outermost layer forming material. Further, laser etching was not performed on the outermost layer. Other than that was carried out similarly to the said Example 2.

[Material for forming outermost layer]
Silica particles [Silicia 450 (average particle size 5 μm), manufactured by Fuji Silysia Co., Ltd.] were mixed with the outermost layer forming material in Example 2 above. The mixing ratio of the silica particles was 10 parts by weight with respect to 100 parts by weight of N-methoxymethylated nylon as the outermost layer forming material.

[Comparative Example 2]
In Comparative Example 1, the same material as in Example 2 was used as the outermost layer forming material. Other than that, it was the same as in Comparative Example 1 above.

[Comparative Example 3]
In Comparative Example 1, an intermediate layer was formed on the outer peripheral surface of the elastic layer in the same manner as in Example 15. Other than that, it was the same as in Comparative Example 1 above.

[Comparative Example 4]
In Comparative Example 3, the same material as in Example 2 was used as the outermost layer forming material. Other than that was carried out similarly to the said comparative example 3.

[Toner adhesion]
After 2000 images were printed using black toner, the presence or absence of toner adhesion to the outer peripheral surface of each charging roll was visually evaluated. As a result, a toner having almost no toner adhesion was evaluated as ◯, a toner having a small amount on the entire surface was evaluated as Δ, and a toner having a large amount on the entire surface was evaluated as ×.

[Charging sound]
The photosensitive drum (30 mm in diameter) and each charging roll were made parallel, and each charging roll was pressed against the outer peripheral surface of the photosensitive drum with a pressing force of 9.8 N in the axial direction of the photosensitive drum. Then, the photosensitive drum was rotated at a rotation speed of 45 rpm, and each charging roll was rotated. In this state, a voltage of AC 2 kVpp and DC 600 V was applied to the charging roll while being changed every 600 Hz within a frequency range of 600 to 3600 Hz. Then, at a point 30 cm away from the contact portion between the charging roll and the photosensitive drum, a noise meter (NL01A, manufactured by Rion Corporation) was used to measure the charging sound at each frequency. The results are also shown in Table 1 below.

  As shown in Tables 1 to 3 above, in the charging rolls of Examples 1 to 16, toner adhesion was suppressed over a long period of use, but in the charging rolls of Comparative Examples 1 to 4, there was much toner adhesion. became. As for the charging sound, the charging rolls of Examples 7 to 12 had a charging sound higher than that of the charging roll of Comparative Example 1 when the frequency was 2400 Hz, but in most other cases, Examples 1 to In comparison with the charging rolls of Comparative Examples 1 to 4, the charging roll of No. 16 has a smaller charging sound, and it can be determined that the charging roll is excellent in suppressing the charging noise.

One Embodiment of the charging roll obtained by the manufacturing method of the charging roll of this invention is shown, (a) is the explanatory view which expanded and schematically showed the front view and the surface, (b) It is XX sectional drawing of (a). It is explanatory drawing which expanded and showed the surface of the outermost layer typically in other embodiment of the charging roll obtained by the manufacturing method of the charging roll of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft body 2 Elastic layer 3 Intermediate layer 4 Outermost layer A Concave part L Concave row

Claims (3)

After forming an elastic layer on the outer peripheral surface of the shaft body, a cylindrical outermost layer is formed on the outer periphery of the elastic layer directly or via another layer , and the concave shape is substantially spherical on the outer peripheral surface of the outermost layer. A plurality of concave portions having a curved surface formed of a part of the inner surface are formed in the axial direction in a state where the opening edge portions do not overlap each other to form a concave portion row, and the concave portion row is formed over the entire circumference in the circumferential direction. A plurality of rows are distributed at predetermined intervals to form a rough surface, the opening diameter of the recesses in each recess row is in the range of 50 to 150 μm, the depth of each recess is in the range of 1.5 to 20 μm, the adjacent recesses and recesses, Is a method of manufacturing a charging roll in which the distance between the opening edges is set in a range of 0 to 20 μm, and the formation of the recesses on the outer peripheral surface of the outermost layer is performed by puncturing the laser beam on the outer peripheral surface of the outermost layer. Irradiating with convergent light, characterized in that the point-shaped irradiated portion is formed in the concave portion. Preparation of electric roll. After forming an elastic layer on the outer peripheral surface of the shaft body, a cylindrical outermost layer is formed on the outer periphery of the elastic layer directly or via another layer , and the concave shape is substantially spherical on the outer peripheral surface of the outermost layer. A plurality of concave portions having a curved surface formed of a part of the inner surface are formed in the axial direction in a state where the opening edge portions do not overlap each other to form a concave portion row, and the concave portion row is formed over the entire circumference in the circumferential direction. A plurality of rows are distributed at predetermined intervals to form a rough surface, the opening diameter of the recesses in each recess row is in the range of 50 to 150 μm, the depth of each recess is in the range of 1.5 to 20 μm, the adjacent recesses and recesses, A method of manufacturing a charging roll in which the distance between the opening edges is set in a range of 0 to 20 μm, and the formation of the recesses on the outer peripheral surface of the outermost layer is produced on the outer peripheral surface of the elastic layer by electroforming. A transfer recess is formed using the transfer mold, and then directly on the outer periphery of the elastic layer. Alternatively, a cylindrical outermost layer is formed through another layer, and the concave portion appears on the outer peripheral surface of the outermost layer due to the influence of the transfer concave portion formed on the outer peripheral surface of the elastic layer. Manufacturing method of charging roll. After forming an elastic layer on the outer peripheral surface of the shaft body, a cylindrical outermost layer is formed on the outer periphery of the elastic layer directly or via another layer , and the concave shape is substantially spherical on the outer peripheral surface of the outermost layer. A plurality of concave portions having a curved surface formed of a part of the inner surface are formed in the axial direction in a state where the opening edge portions do not overlap each other to form a concave portion row, and the concave portion row is formed over the entire circumference in the circumferential direction. A plurality of rows are distributed at predetermined intervals to form a rough surface, the opening diameter of the recesses in each recess row is in the range of 50 to 150 μm, the depth of each recess is in the range of 1.5 to 20 μm, the adjacent recesses and recesses, A method of manufacturing a charging roll in which the distance between the opening edges is set in a range of 0 to 20 μm, wherein the formation of the concave portion on the outer peripheral surface of the outermost layer is a transfer plate on which a convex portion corresponding to the concave portion is formed. In a heated state, the outermost layer is pressed against the transfer plate and rolled. Preparation of the charging roll the protrusions by transferring the outer peripheral surface of the outermost layer and forming the recess.

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