JP2012241735A - Rubber roll, die, and manufacturing method of die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber roll capable of appropriately hold powder materials on the surface and reducing stress on powder materials, a die suitable for forming a roughened surface of rubber elastic part such as a rubber roll, and a manufacturing method appropriate to manufacturing the die.SOLUTION: A rubber roll 1 contains a rubber elastic part 2 having the surface roughened by mold transferring. The rubber elastic part 2 comprises a lot of first projections 21 projecting from a surface and a lot of second projections 22 projecting from the first projections 21 and a surface therearound. A diameter of the second projection 22 is smaller than that of the first projection 21. The height of the second projection 22 is smaller than that of the first projection 21. A die 4 is laminated on a die base material 5 and formed of a first plating layer 51 containing a lot of first hole parts 511 in the surface and a second plating layer 52 laminated along the first hole parts 511 of the first plating layer 51 and a surface therearound and containing a lot of second hole parts 522 in the surface. A diameter of the second hole part 522 is smaller than that of the first hole part 511. A depth of the second hole part 522 is shallower than that of the first hole part 511.

Description

  The present invention relates to a rubber roll, a mold, and a method for manufacturing the mold.

  Conventionally, rubber rolls are used in various fields. As one of techniques using a rubber roll, a technique is known in which powder is held on a roughened rubber roll surface and the held powder is conveyed by rotation of the roll. Specifically, for example, in an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system, a rubber roll is used for development. The development is performed by holding and transporting the toner in the cartridge to the photosensitive drum by a rubber roll, and attaching the toner to the electrostatic latent image formed on the surface of the photosensitive drum to form a visible image.

  As a technique for roughening the surface of a rubber roll, as known in Patent Document 1, etc., a resin coating film in which resin particles as roughness forming particles are dispersed is formed on the surface of a rubber elastic layer of a rubber roll. There is a technique for forming surface irregularities by the convex portions by and the concave portions between the convex portions. Further, as known in Patent Document 2 and the like, there is a technique for forming surface irregularities by transferring a mold surface roughened by a plating layer or the like on which a large number of pits are formed to the surface of a rubber elastic layer.

JP 2009-75497 A JP 2006-184608 A

  However, the conventional technology has room for improvement in the following points. That is, in the rubber roll whose surface is roughened, the powder is held in the recesses on the roll surface. In addition, other members such as a blade member often come into contact with the convex portion of the roll surface.

  Here, in the rubber roll whose surface is roughened by the roughness forming particles, the resin coating film is easily scraped off by rubbing with other members at the tip of the convex portion. As a result, the use overlaps and the convex portion is lowered, the gap between the concave portions is reduced, and the holding power of the powder is lowered. In some cases, the roughness-forming particles fall off, the surface irregularities are impaired, and the powder holding power may be greatly reduced. When the holding power of the powder is reduced, the transportability of the powder due to the rotational movement of the rubber roll is reduced. The concave surface is made of a relatively hard resin. Therefore, the powder sandwiched between the surface of the recess and the other member is susceptible to stress. Furthermore, when the amount of addition of the roughness forming particles increases, the coating film hardness increases, and it becomes easy to give stress to the powder.

  On the other hand, a rubber roll whose surface has been roughened by mold transfer has a relatively large convex portion in order to ensure the holding power of the powder. For this reason, the gap between the recesses becomes large, and the powder held in the recess and the surface of the recess are easily brought into surface contact. Furthermore, since the said convex part has flexible rubber elasticity, when another member is press-contacted to a convex part, a convex part will compress-deform and the clearance gap of a recessed part will expand in a surface direction. When the gap between the recesses expands in the surface direction, the contact area between the powder held in the recess and the surface of the recess increases. Therefore, the powder sandwiched between the concave surface and the other member is easily subjected to stress. Such a problem is particularly likely to occur in the developing rubber roll that frictionally charges the toner by rubbing the convex portions on the roll surface and the blade member. When the stress on the toner increases, a problem such as a problem that the toner adheres to the blade member is induced.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a rubber roll capable of appropriately holding powder on the surface and reducing stress on the powder. Moreover, it is providing the type | mold suitable for the rough surface formation of the rubber elastic part in the said rubber roll. Moreover, it is providing the manufacturing method suitable for manufacture of the said type | mold.

  A first invention is a rubber roll having a rubber elastic portion whose surface is roughened by mold transfer, wherein the rubber elastic portion includes a plurality of first protrusions protruding outward from the surface, And a plurality of second projecting portions projecting outward from the surrounding surface, and the diameter of the second projecting portion is smaller than the diameter of the first projecting portion. The rubber roll is characterized in that the height is lower than the height of the first protrusion (claim 1).

  According to a second aspect of the present invention, there is provided a mold base part, a first plating layer laminated on the mold base part and having a number of first holes recessed inward on the surface, and the first plating layer described above. A second plated layer having a plurality of second hole portions which are laminated along the surface of the first hole portion and its surroundings and recessed inward, and the diameter of the second hole portion is the first hole portion. The mold is characterized in that it is smaller than the diameter of the hole, and the depth of the second hole is shallower than the depth of the first hole (Claim 6).

  According to a third aspect of the present invention, there is provided a first step of forming a first plating layer having a plurality of indented first holes on the surface of the mold base portion, and the first holes of the first plating layer. And a second step of forming a second plating layer having a plurality of indented second hole portions on the surface along the surface of the portion and the periphery thereof, and the diameter of the second hole portion is The mold manufacturing method is characterized in that it is smaller than the diameter of one hole and the depth of the second hole is adjusted to be shallower than the depth of the first hole (Claim 8).

  According to the rubber roll having the above configuration, the powder in contact with the surface of the rubber elastic portion is guided and held in the gap between the first protruding portion and the first protruding portion. Therefore, if the rubber roll is rotated, an appropriate amount of the powder held in the gap can be conveyed. In addition, a large number of second protrusions smaller than the first protrusions are formed on the first protrusion and the surrounding surface. Therefore, it is difficult for the powder held in the gap and the gap surface to come into surface contact, and the contact area between them can be reduced. Further, since the first protrusion has rubber elasticity, when another member such as a blade member is pressed against the first protrusion, the first protrusion is compressively deformed and the gap is expanded in the surface direction. It will be. However, even in such a case, an increase in the contact area between the powder and the surface of the gap is suppressed by the second protrusions present in the gap. Therefore, stress applied to the powder sandwiched between the gap surface and the other member can be reduced.

  According to the first aspect of the invention, it is possible to provide a rubber roll that can appropriately hold the powder on the surface and can reduce stress on the powder.

  Therefore, when the rubber roll is used as, for example, a developing rubber roll incorporated in an image forming apparatus employing an electrophotographic system, an appropriate toner conveyance amount can be provided. In addition, since the stress on the toner can be reduced, toner adhesion to the blade member in contact with the developing rubber roll can be suppressed. Therefore, it can contribute to high durability of the image forming apparatus.

  In addition, according to the mold having the above configuration, a large number of hole portions corresponding to the first hole portions of the surface of the first plating layer are formed on the surface of the second plating layer. In addition, a large number of second holes smaller than the hole corresponding to the first hole are formed on the entire surface of the second plating layer including the hole corresponding to the first hole and the surrounding surface. Yes. Therefore, by transferring the rough mold surface to the surface of the rubber elastic portion, a large number of first protrusions protruding outward from the surface, and the first protrusions and their surrounding surfaces outward. A plurality of projecting second projecting portions, the diameter of the second projecting portion is smaller than the diameter of the first projecting portion, and the height of the second projecting portion is lower than the height of the first projecting portion. The rubber elastic part which has is obtained.

  Therefore, according to the said 2nd invention, the type | mold suitable for the rough surface formation of the rubber elastic part in the said rubber roll etc. can be provided.

  Moreover, according to the manufacturing method of the type | mold which has the said structure, the type | mold which has the said structure can be manufactured through a 1st process and a 2nd process.

  Therefore, according to 3rd invention, the manufacturing method suitable for manufacture of the said type | mold can be provided.

It is explanatory drawing which shows typically the rubber roll which concerns on an Example. It is explanatory drawing which shows the AA cross section of FIG. 1 typically. It is explanatory drawing which shows typically the surface of the rubber elastic part in the B position of FIG. It is explanatory drawing which shows typically the CC cross section of the rubber elastic part of FIG. (A) is explanatory drawing which expands and shows typically the 1st protrusion part of FIG. 4, (b) is explanatory drawing which expands and schematically shows the 2nd protrusion part of FIG. It is explanatory drawing which shows typically the 1st process (1A) in the manufacturing method of the type | mold which concerns on an Example. It is explanatory drawing which shows typically the 1st process (1B) in the manufacturing method of the type | mold which concerns on an Example. It is explanatory drawing which shows typically the 2nd process (2) in the manufacturing method of the type | mold which concerns on an Example. (A) is explanatory drawing which expands and shows typically the 1st hole part of the 1st plating layer in FIG.8 (b), (b) is the 2nd hole of the 2nd plating layer in Fig.8 (a). It is explanatory drawing which expands and shows a part typically. 2 is a surface observation photograph of a first plating layer in a sample 1 mold. 4 is a surface observation photograph of a second plating layer in a sample 1 mold. 4 is a cross-sectional observation photograph of the first plating layer and the second plating layer in the sample 2 mold. 2 is a surface observation photograph of a rubber elastic part in a developing rubber roll of Sample 1. FIG. 4 is a surface observation photograph of a rubber elastic part in a developing rubber roll of Sample 12. FIG.

  The rubber roll will be described. The rubber roll has a rubber elastic portion whose surface is roughened by mold transfer. When the rubber elastic portion is molded, the surface of the rubber elastic portion may be roughened by transferring the rough state of the surface of the mold, or after forming the rubber elastic portion, The rough surface state of the mold surface which is not present may be transferred and roughened. From the viewpoint of easily roughening the surface of the rubber elastic portion, the former is preferable.

  The rubber elastic portion has a number of first protrusions protruding outward from the surface, and a number of second protrusions protruding outward from the first protrusion and its surrounding surface. , Which are integrally formed of the same rubber material. That is, a large number of first projecting portions project outward from the surface of the rubber elastic portion. And the 2nd projection part is not only the surface of the 1st projection part but the surface of the rubber elastic part between the 1st projection part and the 1st projection part, ie, the rubber in which the 1st projection part is not formed A large number of protrusions project outward from the surface of the elastic portion. Thus, the rubber elastic portion has a surface on which a large number of first protrusions protrude, and a large number of second protrusions protrude from the entire surface. In addition, the 1st protrusion part and 2nd protrusion part on the surface of a rubber elastic part do not protrude from the surface by the particle | grains for roughness formation. Moreover, the 1st protrusion part and 2nd protrusion part of a rubber elastic part surface can be confirmed from the surface observation of the rubber elastic part demonstrated below, or the cross-sectional observation of the circumferential direction cross section of a rubber elastic part.

  In the rubber elastic portion, the diameter of the second protrusion is smaller than the diameter of the first protrusion. The “diameter of the first protrusion” is the diameter or equivalent circle diameter of the first protrusion at the base end of the first protrusion. The “diameter of the second protrusion” is the diameter or equivalent circle diameter at the base end of the second protrusion. The “equivalent circle diameter” is a concept applied when the outline of the base end part of each protrusion is not substantially circular but has an irregular shape, and is inside the outline of the base end part of each protrusion. The diameter of a circle having the same area as.

  In the rubber elastic portion, it can be confirmed as follows that “diameter of the second protrusion portion <diameter of the first protrusion portion” is satisfied. First, the surface of the rubber elastic portion is observed on the central portion in the axial direction of the rubber elastic portion in the rubber roll. And it confirms that the 1st protrusion part and the 2nd protrusion part exist in the surface of a rubber elastic part. Next, the diameter of the first protrusion and the diameter of the second protrusion are compared. If it is clearly determined by the above comparative observation that “the diameter of the second protruding portion <the diameter of the first protruding portion” is satisfied, it is sufficient. When it is difficult to determine or when a specific value is obtained, the surface of the rubber elastic portion surface is observed at three locations in the circumferential direction (center angle 120 ° intervals). Then, three points at one place, that is, a total of nine points, each representative protrusion is selected, each diameter is measured, and an arithmetic average of the obtained measured values is set as the diameter of each protrusion. Thus, specific values can be compared to confirm that “diameter of second protrusion <diameter of first protrusion” is satisfied. A digital microscope (such as “MX-1200E” manufactured by Nakaden International Co., Ltd.) can be used for the observation and measurement.

  In the rubber elastic portion, the height of the second protrusion is lower than the height of the first protrusion. The “height of the first protrusion” is a distance from the base end to the tip of the first protrusion. The “height of the second protrusion” is a distance from the base end to the tip of the second protrusion.

  In the rubber elastic part, it can be confirmed as follows that “the height of the second protrusion <the height of the first protrusion” is satisfied. First, the axial center part of the rubber elastic part in the rubber roll is cut in the circumferential direction. Next, the section of the cut rubber elastic portion surface is observed. And it confirms that the 1st protrusion part and the 2nd protrusion part exist in the surface of a rubber elastic part. Next, the height of the second protrusion and the height of the first protrusion are compared. If it is clearly determined by the above comparative observation that “the height of the second protruding portion <the height of the first protruding portion” is satisfied, it is sufficient. When it is difficult to discriminate or when a specific value is obtained, a cross-sectional observation is performed on three portions (center angle 120 ° intervals) in the circumferential direction on the surface of the cut rubber elastic portion. Then, three points at one place, that is, a total of nine points, each of the representative protrusions is selected, the respective heights are measured, and the arithmetic average of the obtained measured values is set as the height of each protrusion. Thereby, specific values can be compared to confirm that “the height of the second protrusions <the height of the first protrusions” is satisfied. Note that the above-described digital microscope can be used for the observation and measurement. Moreover, it may replace with the said cross-sectional observation and the height of each protrusion part can be measured by the said surface observation.

  In the rubber roll, it is preferable that the surface of the second protrusion includes a part of a substantially spherical surface.

  The “substantially spherical surface” means not only a perfect spherical surface but also a curved surface that can be regarded as a substantially spherical surface. In addition, the above “including part” means that the surface of the second protrusion has at least a surface obtained by cutting out a substantially spherical portion. The surface shape of the second protrusion can be confirmed from the surface observation of the rubber elastic portion and the cross-sectional observation of the circumferential cross section of the rubber elastic portion. Such a second protrusion having a surface including a part of a substantially spherical surface cannot be formed by transfer of a mold surface roughened by electric discharge machining. For example, it can be suitably formed by transfer of a mold provided with a plating layer having a hole portion obtained by copying a part of the surface of the substantially spherical particle.

  When the surface of the second protrusion includes a part of a substantially spherical surface, it is easy to make point contact between the surface of the rubber elastic portion and the powder, and is held in the gap between the first protrusion and the first protrusion. The contact area between the formed powder and the surface of the gap can be further reduced. Further, even when the first protrusion is compressively deformed and the gap is expanded in the surface direction, an increase in the contact area between the powder and the gap surface is effectively suppressed. Therefore, the stress applied to the powder sandwiched between the gap surface and the other member can be further reduced.

  Therefore, this rubber roll is suitable for powder conveyance. Specifically, for example, it is suitable as a developing rubber roll that is incorporated in an image forming apparatus that employs an electrophotographic system and in which the surface of the rubber elastic portion and the blade member are rubbed over a long period of time. When applied to a developing rubber roll that uses toner as a powder, it is possible to secure an appropriate toner conveyance amount, and to easily reduce the stress applied to the toner over a long period of time, and to prevent the toner from sticking to the blade member over a long period of time. It is easy. Therefore, it is easy to contribute to high durability of the image forming apparatus.

  In the rubber roll, (1) the diameter of the first protrusion is larger than the height of the first protrusion, and / or (2) the surface of the first protrusion is a part of a substantially spherical surface. (Claim 3).

  When satisfying the above (1), as the shape of the first projecting portion, for example, the cross section when cut along the height direction of the first projecting portion is substantially trapezoidal (however, the upper base <the lower base is satisfied) And the like. The first protrusion satisfying the relationship (1) can be suitably formed by, for example, transfer of a mold provided with a plating layer having a hole portion obtained by copying a part of the surface of a bubble generated by the plating reaction. . In addition, about the case where said (2) is satisfy | filled, since it applies to the case where the surface of the 2nd protrusion part mentioned above contains a part of substantially spherical surface, description is abbreviate | omitted. Moreover, satisfying the above (1) and (2) can be confirmed from surface observation and cross-sectional observation of the rubber elastic portion described above.

  When the above (1) is satisfied, the powder holding force does not increase excessively, so that it is difficult for the powder to remain held at the bottom of the gap between the first protrusion and the first protrusion. Excellent body transportability. In particular, when the powder is toner, it is difficult for the toner to adhere to the bottom of the gap, so that it is easy to contribute to stable toner conveyance and uniform toner conveyance. Moreover, when satisfy | filling said (2), since it becomes easy to make uniform contact with other members, such as a 1st protrusion part and a blade member, it becomes easy to make the stress reduction effect with respect to a powder uniform in a roll longitudinal direction.

  The rubber roll is preferably used as a developing rubber roll, a charging rubber roll, a transfer rubber roll, a fixing rubber roll or the like incorporated in an image forming apparatus such as a copying machine, printer, facsimile, or composite machine employing an electrophotographic system. Can do. In this case, the average particle diameter of the toner particles used in the image forming apparatus is preferably 3 to 15 μm, more preferably 5 to 10 μm. The average particle size of the toner can be measured by a particle size / particle size distribution measuring device “Nanotrack UPA” manufactured by Nikkiso Co., Ltd.

Here, the diameter of the first protrusion of the rubber elastic part is φ ₁ [μm], and the diameter of the second protrusion is φ ₂ [μm]. In this case, the lower limit value of φ ₁ is preferably 30 μm, more preferably 35 μm, and even more preferably 40 μm from the viewpoint of ensuring appropriate powder holding force and powder transportability. The upper limit of φ ₁ is preferably 80 μm, more preferably 75 μm, and even more preferably 70 μm from the viewpoints of excessive powder holding force and prevention of excessive powder conveyance. Further, the lower limit value of φ ₂ is preferably 1 μm, more preferably 1.5 μm, and even more preferably 2 μm from the viewpoint of surely obtaining the effect of reducing the contact area with the powder. The upper limit value of φ ₂ is preferably 10 μm, more preferably 9.5 μm, and even more preferably 9 μm, from the viewpoint of appropriately securing a gap space and facilitating reduction of stress on the powder.

Φ ₂ / φ ₁ , which is the ratio of the diameter φ ₂ of the second protrusion to the diameter φ ₁ of the first protrusion, is a lower limit from the viewpoint of ensuring appropriate powder transportability and reducing stress on the powder. The value is preferably 0.01, more preferably 0.04, and even more preferably 0.07. On the other hand, the upper limit of φ ₂ / φ ₁ is preferably 0.3, more preferably 0.27, and even more preferably 0.24.

The height of the first protrusion of the rubber elastic part is h ₁ [μm], and the height of the second protrusion is h ₂ [μm]. In this case, the lower limit of h ₁ is preferably 5 μm, more preferably 6 μm, and even more preferably 7 μm, from the viewpoint of ensuring appropriate powder holding force and powder transportability. The upper limit value of h ₁ is preferably 25 μm, more preferably 24 μm, and even more preferably 23 μm from the viewpoints of excessive powder holding power and prevention of excessive powder conveyance. Further, the lower limit value of h ₂ is preferably 1 μm, more preferably 1.5 μm, and even more preferably 2 μm from the viewpoint of reliably obtaining the effect of reducing the contact area with the powder. The upper limit value of h ₂ is preferably 8 μm, more preferably 7 μm, and even more preferably 6 μm from the viewpoint of appropriately securing a gap space and facilitating reduction of stress on the powder.

H ₂ / h ₁ , which is the ratio of the height h ₂ of the second protrusion to the height h ₁ of the first protrusion, is from the viewpoint of ensuring appropriate powder transportability and reducing stress on the powder. The lower limit is preferably 0.04, more preferably 0.14, and even more preferably 0.24. On the other hand, the upper limit of h ₂ / h ₁ is preferably 1.6, more preferably 1.5, and even more preferably 1.4.

Further, the area ratio of the first protrusions of the rubber elastic part is Ap ₁ [%], and the area ratio of the second protrusions is Ap ₂ [%]. Specifically, Ap ₁ and Ap ₂ are the area ratio of the first protrusion and the area ratio of the second protrusion when the captured image of the surface of the rubber elastic portion is binarized using a discriminant analysis method. is there. When the value of Ap ₁ is decreased, the density of the first protrusions on the surface of the rubber elastic portion is decreased, and the gap between the first protrusion and the first protrusion is increased. On the other hand, when the value of Ap ₁ increases, the density of the first protrusions on the surface of the rubber elastic part increases, and the gap between the first protrusions and the first protrusions decreases. Therefore, the value of Ap ₁ is mainly related to the amount of powder held in the gap. The rubber roll is used by rotating the rubber elastic portion in the circumferential direction. For this reason, the value of Ap ₁ is also related to the conveyance capability of conveying the powder held in the gap by the rotation of the roll.

On the other hand, when the value of Ap ₂ is decreased, the density of the second protrusions on the surface of the rubber elastic part including the first protrusions and the periphery thereof decreases, and the gap between the second protrusions and the second protrusions. Becomes larger. On the other hand, when the value of Ap ₂ increases, the density of the second protrusions on the surface of the rubber elastic part including the first protrusions and the periphery thereof increases, and the gap between the second protrusions and the second protrusions. Becomes smaller. And a 2nd protrusion part has a diameter and height smaller than a 1st protrusion part. Therefore, the value of Ap ₂ is mainly related to the contact area between the powder held in the gap and the gap surface.

The Ap ₁ and Ap ₂ can be measured as follows. That is, an image is taken at an arbitrary position in the circumferential direction of the surface of the rubber elastic portion at the central portion in the axial direction of the rubber elastic portion in the rubber roll. Specifically, using the above-described digital microscope, an area of 0.5 mm × 0.4 mm at any one position on the surface of the rubber elastic portion is captured as an image with a resolution of 1280 × 1024 dpi. At this time, the size of one dot on the image is set to be 1/15 or less of the diameter of the target protrusion (first protrusion or second protrusion). Next, monochrome conversion is performed so that the obtained captured image can be easily binarized. Next, in order to smooth the illuminance unevenness, noise is removed from the image after monochrome conversion by a smoothing filter. Next, the image from which noise has been removed is binarized by discriminant analysis using image processing software (such as “NanoHunter NS2K-Pro / Lt” manufactured by Nanosystem Corporation). Next, the binarized image is inverted in black and white, and black noise generated inside the white portion corresponding to the target protrusion is filled with white, and then the area of the white portion is measured. As a result, the area ratio (Ap ₁ or Ap ₂ ) of the target protrusion (first protrusion or second protrusion) can be obtained.

The lower limit value of the area ratio Ap ₁ of the first protrusion is preferably 30%, more preferably 35%, and still more preferably 40% from the viewpoint of ensuring appropriate powder holding force and powder transportability. There should be. The upper limit of Ap ₁ is preferably 70%, more preferably 65%, and even more preferably 60%, from the viewpoint of preventing excessive powder holding force and excessive conveyance of the powder. The lower limit of the area ratio Ap ₂ of the second protrusion, from the viewpoint of obtaining reliably the effect of reducing the contact area with the powder, preferably 30%, more preferably 35%, more preferably 40% It is good to be. The upper limit of Ap ₂ is preferably 78.5%, more preferably 73%, and still more preferably 68%, from the viewpoint of appropriately securing a gap space and facilitating reduction of stress on the powder. Good.

In the rubber roll, the first protrusion satisfies 30 μm ≦ φ ₁ ≦ 80 μm, 5 μm ≦ h ₁ ≦ 25 μm, 30% ≦ A p ₁ ≦ 70%, and the second protrusion includes 1 μm ≦ φ ₂ ≦ 10 μm, 1 μm ≦ h ₂ , 30% ≦ Ap ₂ ≦ 78.5% is preferably satisfied (Claim 4).

  In this case, it is excellent in the balance of the holding power of powder such as toner having an average particle diameter of about 1 to 15 μm, transportability, and the effect of reducing stress on the powder. Therefore, this rubber roll is suitable, for example, as a developing rubber roll that is incorporated in an image forming apparatus that employs an electrophotographic system and in which the surface of the rubber elastic portion and the blade member are rubbed over a long period of time.

  In the rubber roll, it is preferable that the surface of the rubber elastic portion is given releasability in order to improve releasability from an object such as powder that is in contact with the surface of the rubber elastic portion. Examples of the method for imparting releasability include a method of modifying the surface of the rubber elastic portion with ultraviolet irradiation or a surface modifier. In addition, a surface layer made of a coating film containing a resin such as urethane resin or a conductive agent is laminated on the surface of the rubber elastic portion with a thickness that does not impair the unevenness caused by the first and second protrusions (coating) ) And the like. The thickness of the surface layer is preferably 10 μm or less, more preferably 5 μm or less.

  In the case of the above surface modification, it is possible to impart releasability without substantially impairing the unevenness caused by the first protrusion and the second protrusion on the surface of the rubber elastic part. Therefore, it becomes easy to suppress the density variation of the first protrusion and the second protrusion. Therefore, when this rubber roll is used as the developing rubber roll of the image forming apparatus, it is possible to secure a uniform toner conveyance amount, and to easily prevent the toner from sticking to the blade member, and to suppress density variation. . Therefore, it becomes easy to obtain a fine image. On the other hand, in the case of using the surface layer, it is possible to impart releasability to the surface of the rubber elastic layer at a relatively simple and low cost.

  In the rubber roll, the rubber elastic portion can be formed in a substantially cylindrical shape along the outer periphery of the long shaft body. Further, the rubber roll can be provided by projecting a short shaft from each end face of both end portions of a rubber elastic portion formed in a substantially cylindrical shape. The shaft body can be made of a metal (including an alloy) such as stainless steel or aluminum, a solid body of plastic, or a hollow body.

  In the rubber roll, the rubber elastic portion can be composed of one or two or more rubber elastic layers. Examples of the rubber material constituting the rubber elastic part include silicone rubber, urethane rubber, butadiene rubber, hydrin rubber, and nitrile rubber. Silicone rubber and urethane rubber can be suitably used from the viewpoint of excellent resistance to elasticity of the rubber elastic portion. Silicone rubber is particularly suitable because it is less likely to cause a volume change with respect to an environmental change such as a temperature change or a humidity change, and has an advantage that the outer diameter fluctuation of the rubber elastic portion due to the environmental change is small.

  In the rubber roll, it is preferable that the rubber elastic portion has conductivity.

  In this case, it can be suitably used as a developing rubber roll of the image forming apparatus. For imparting conductivity to the rubber elastic part, the rubber elastic part contains one or more electronic conductive agents such as carbon black, ionic conductive agents such as quaternary ammonium salts, and conductive agents such as ionic liquids. It can carry out more suitably. In addition, if necessary, a filler, an extender, a reinforcing material, a processing aid, a curing agent, a vulcanization accelerator, a crosslinking agent, a crosslinking aid, an antioxidant, a plasticizer, an ultraviolet absorber, One or two or more various additives such as pigments, silicone oils, auxiliaries, and surfactants can be appropriately added.

  In the rubber roll, the thickness of the rubber elastic part is preferably in the range of 0.1 to 10 mm. More preferably, it exists in the range of 1-5 mm.

  Next, the mold will be described. The mold is suitable for forming a rough surface on the surface of a rubber elastic part such as the rubber roll. In the above mold, the mold base portion can be made of a metal material such as a steel material such as S55C or SACM645, an aluminum material (including an alloy) such as A5056, a plastic material, or the like.

  In the mold described above, the first plating layer may be laminated on the mold base part. The mold base part and the first plating layer are not necessarily in contact with each other, and one or more plating layers such as a base plating layer are laminated between the mold base part and the first plating layer. Also good.

  In the above mold, the first plating layer laminated directly on the mold base portion or through another plating layer has a number of first hole portions recessed inward (on the mold base portion side) on the surface. doing. In addition, the second plating layer laminated along the first hole portion of the first plating layer and the surrounding surface has a number of second hole portions recessed inward (on the mold base portion side) on the surface. doing. That is, the second plating layer is laminated not only on the surface of the first plating layer where the first hole is not formed, but also on the surface in the hole of the first hole. Therefore, the second hole portion of the second plating layer exists not only on the portion where the first hole portion is not formed on the first plating layer but also on the inside of the hole of the first hole portion.

  In the above mold, the diameter of the second hole is smaller than the diameter of the first hole, and the depth of the second hole is shallower than the depth of the first hole. The “diameter of the first hole” is the diameter of the opening of the first hole or the equivalent circle diameter. The “diameter of the second hole” is the diameter or equivalent circle diameter of the opening of the second hole. "Equivalent circle diameter" is a concept applied when the contour of the opening of each hole is not substantially circular, but has an irregular shape, and is the same as the area inside the contour of the opening of each hole The diameter of a circle having an area. The “depth of the first hole” is the distance from the opening of the first hole to the bottom. The “depth of the second hole” is a distance from the opening of the second hole to the bottom. The positional relationship between the first hole portion and the second hole portion, and the relationship between the diameter and depth of each hole portion can be confirmed from surface observation and cross-sectional observation of the mold described below.

  That is, first, it is confirmed that there is a lower layer plating and an upper layer plating that are in contact with each other on the mold base part by cutting the mold. Next, by surface observation, a large number of large-diameter holes can be seen on the upper plating surface, and a large number of small-diameter holes smaller in diameter than the large-diameter holes can be seen in and around the large-diameter holes. Check. Next, through surface observation and cross-sectional observation, holes are formed on the surface of the lower layer plating corresponding to the large-diameter hole, and upper layer plating is performed along the surface in the corresponding hole and around the hole. Confirm that it is formed. Further, it is confirmed that only the small-diameter hole is directly formed on the surface of the upper plating. From these observations, it can be confirmed that the lower layer plating corresponds to the first plating layer having the first hole, and the upper layer plating corresponds to the second plating layer having the second hole. Moreover, the positional relationship between the first hole and the second hole can also be confirmed. Furthermore, the diameter and depth of the first hole and the second hole can also be compared. If it is clearly determined by the above comparative observation that “the diameter of the second hole portion <the diameter of the first hole portion” is satisfied, it is sufficient. When it is difficult to discriminate or when a specific value is obtained, the above observation is performed at any three locations on the mold surface. Then, 3 points for each place, that is, a total of 9 points, each representative hole was selected, the diameter and depth were measured, and the arithmetic mean of the measured values obtained was calculated as the diameter and depth of each hole. Say it. Thus, specific values are compared, and it is confirmed that “the diameter of the second hole <the diameter of the first hole” and “the depth of the second hole <the depth of the first hole” are satisfied. be able to. Note that the above-described digital microscope can be used for the observation and measurement. Further, as will be described later, when the mold base portion has a substantially cylindrical space, and the first plating layer and the second plating layer are formed on the inner wall of the space, the space What is necessary is just to perform the said observation and measurement about the three circumferential directions (center angle 120 degree space | interval) of the inner wall surface in the axial direction center part.

  In the above mold, the surface of the second hole part preferably includes a part of a substantially spherical surface. The “substantially spherical surface” means not only a perfect spherical surface but also a curved surface that can be regarded as a substantially spherical surface. In addition, the above “including part” means that the surface of the second hole portion has at least a surface obtained by cutting out a substantially spherical portion. The surface shape of the second hole can be confirmed from surface observation and cross-sectional observation of the mold described above. The second hole portion having a surface including a part of such a substantially spherical surface is difficult to form by electric discharge machining. For example, it can be suitably formed by copying a part of the surface of the substantially spherical particle onto the surface of the second plating layer.

  When the surface of the second hole includes a part of a substantially spherical surface, the second protrusion of the rubber elastic part obtained by the transfer is a second protrusion having a surface including a part of the substantially spherical surface. Can do.

  In the above mold, <1> the diameter of the first hole is larger than the depth of the first hole, and / or <2> the surface of the first hole is a part of a substantially spherical surface. It is preferable to contain.

  When satisfying the above <1>, as the shape of the first hole portion, for example, the cross section when cut along the depth direction of the first hole portion is substantially trapezoidal (however, the lower base <the upper base is satisfied) And the like. The first hole satisfying the relationship <1> can be preferably formed by copying a part of the surface of the bubble generated by the plating reaction on the surface of the first plating layer, for example. In addition, since the case where the above <2> is satisfied is the same as the case where the surface of the second hole portion includes a part of a substantially spherical surface, description thereof is omitted. Moreover, satisfying the above <1> and <2> can be confirmed from surface observation and cross-sectional observation of the mold described above.

  When satisfying the above <1>, the first protruding portion of the rubber elastic portion obtained by the transfer can be shaped so that the diameter of the first protruding portion is larger than the height of the first protruding portion. Moreover, when satisfy | filling said <2>, the 1st protrusion part of the rubber elastic part obtained by transcription | transfer can be made into the 1st protrusion part which has the surface containing a part of substantially spherical surface.

Here, the diameter of the first hole of the first plating layer is Φ ₁ [μm], and the diameter of the second hole of the second plating layer is Φ ₂ [μm]. In this case, the lower limit value of Φ ₁ is preferably 40 μm, more preferably 45 μm, and even more preferably 50 μm, from the viewpoint of ensuring an appropriate powder holding force and powder transportability of the rubber elastic portion obtained by transfer. It is good to be. The upper limit of Φ ₁ is preferably 90 μm, more preferably 85 μm, and even more preferably 80 μm, from the viewpoint of preventing excessive powder holding force of the rubber elastic part obtained by transfer and preventing excessive conveyance of the powder. Good. In addition, the lower limit value of Φ ₂ is preferably 1 μm, more preferably 1.5 μm, and further preferably 2 μm from the viewpoint of surely obtaining the effect of reducing the contact area with the powder of the rubber elastic part obtained by transfer. It is good to be. The upper limit value of Φ ₂ is preferably 10 μm, more preferably 9.5 μm, from the viewpoint of appropriately securing the above gap space in the rubber elastic portion obtained by transfer and facilitating reduction of stress on the powder. Preferably, it is 9 μm.

Φ ₂ / Φ ₁ , which is the ratio of the diameter Φ ₂ of the second hole to the diameter Φ ₁ of the first hole, ensures proper powder transportability and reduced stress on the powder in the rubber elastic body obtained by transfer. The lower limit is preferably 0.01, more preferably 0.04, and even more preferably 0.07 from the viewpoint of, for example. On the other hand, the upper limit of Φ ₂ / Φ ₁ is preferably 0.3, more preferably 0.27, and even more preferably 0.04.

Further, the depth of the first hole of the first plating layer is d ₁ [μm], and the depth of the second hole of the second plating layer is d ₂ [μm]. In this case, the lower limit of d ₁ is preferably 5 μm, more preferably 6 μm, and even more preferably 7 μm, from the viewpoint of ensuring an appropriate powder holding force and powder transportability of the rubber elastic part obtained by transfer. There should be. The upper limit of d ₁ is preferably 25 μm, more preferably 24 μm, and even more preferably 23 μm, from the viewpoint of preventing excessive powder holding force of the rubber elastic portion obtained by transfer and preventing excessive conveyance of powder. . Further, the lower limit of d ₂ is preferably 1 μm, more preferably 1.5 μm, and further preferably 2 μm from the viewpoint of surely obtaining an effect of reducing the contact area with the powder of the rubber elastic part obtained by transfer. There should be. The upper limit value of d ₂ is preferably 8 μm, more preferably 7 μm, and still more preferably from the viewpoint of appropriately securing the gap space in the rubber elastic portion obtained by transfer and facilitating reduction of stress on the powder. It is good that it is 6 μm.

D ₂ / d ₁ , which is a ratio of the depth d ₂ of the second hole to the depth d ₁ of the first hole, is an appropriate powder transportability and a reduction in stress on the powder in the rubber elastic body obtained by the transfer. From the standpoint of ensuring, the lower limit is preferably 0.04, more preferably 0.14, and even more preferably 0.24. On the other hand, the upper limit value of d ₂ / d ₁ is preferably 1.6, more preferably 1.5, and still more preferably 1.4.

Further, the area ratio of the first hole portion is Bp ₁ [%], and the area ratio of the second hole portion is Bp ₂ [%]. Specifically, Bp ₁ and Bp ₂ are the area ratio of the first hole and the area ratio of the second hole when the captured image of the surface of the second plating layer is binarized using a discriminant analysis method. It is. When the value of Bp ₁ is decreased, the density of the first hole portion is decreased, and the gap between the first hole portion and the first hole portion is increased. On the other hand, when the value of Bp ₁ is increased, the density of the first hole portion is increased, and the gap between the first hole portion and the first hole portion is decreased. Therefore, the value of Bp ₁ is mainly related to the amount of powder held in the gap between the first protrusion and the first protrusion on the rubber elastic portion surface obtained by transfer.

On the other hand, when the value of Bp ₂ is decreased, the density of the second hole portion is decreased, and the gap between the second hole portion and the second hole portion is increased. On the other hand, when the value of Bp ₂ is increased, the density of the second hole portion is increased and the gap between the second hole portion and the second hole portion is decreased. Therefore, the value of Bp ₂ is mainly related to the contact area between the powder held in the gap between the first protrusion and the first protrusion on the rubber elastic portion surface obtained by transfer and the surface of the gap. is there.

The Bp ₁ and Bp ₂ can be measured as follows. That is, an image is taken at an arbitrary position on the surface of the second plating layer of the above type. Specifically, using the above-described digital microscope, an area of 0.5 mm × 0.4 mm at an arbitrary position on the surface of the second plating layer is captured as an image with a resolution of 1280 × 1024 dpi. At this time, the size of one dot on the image is set to be 1/15 or less of the diameter of the target hole (first hole or second hole). Next, monochrome conversion is performed so that the obtained captured image can be easily binarized. Next, in order to smooth the illuminance unevenness, noise is removed from the image after monochrome conversion by a smoothing filter. Next, the image from which noise has been removed is binarized by discriminant analysis using image processing software (such as “NanoHunter NS2K-Pro / Lt” manufactured by Nanosystem Corporation). Next, the binarized image is inverted in black and white, and black noise generated inside the white portion corresponding to the target hole is filled with white, and then the area of the white portion is measured. Thereby, the area ratio (Bp ₁ or Bp ₂ ) of the target hole (first hole or second hole) can be obtained.

The lower limit value of the area ratio Bp ₁ of the first hole is preferably 30%, more preferably from the viewpoint of ensuring an appropriate powder holding force and powder transportability of the rubber elastic part obtained by transfer. It is good that it is 35%, more preferably 40%. The upper limit of Bp ₁ is preferably 70%, more preferably 65%, and still more preferably 60%, from the viewpoint of preventing excessive powder holding force of the rubber elastic portion obtained by transfer and preventing excessive conveyance of the powder. It is good to be. Also, the second hole portion lower limit of the area ratio Bp ₂ of, from the viewpoint of obtaining reliably the effect of reducing the contact area between the rubber elastic portion of the powder obtained by transcription, preferably 30%, more preferably Is 35%, more preferably 40%. The upper limit value of Bp ₂ is preferably 78.5%, more preferably 73%, from the viewpoint of appropriately securing the above gap space in the rubber elastic portion obtained by transfer and facilitating reduction of stress on the powder. More preferably, it is 68%.

In the above mold, the first hole satisfies 40 μm ≦ Φ ₁ ≦ 90 μm, 5 μm ≦ d ₁ ≦ 25 μm, 30% ≦ Bp ₁ ≦ 70%, and the second hole includes 1 μm ≦ Φ ₂ ≦ 10 μm, 1 μm ≦ d ₂ , 30% ≦ Bp ₂ ≦ 78.5% is preferably satisfied.

In this case, on the surface of the rubber elastic portion obtained by transfer, the first protrusion satisfies 30 μm ≦ φ ₁ ≦ 80 μm, 5 μm ≦ h ₁ ≦ 25 μm, 30% ≦ Ap ₁ ≦ 70%, and the second protrusion However, 1 μm ≦ φ ₂ ≦ 10 μm, 1 μm ≦ h ₂ , 30% ≦ Ap ₂ ≦ 78.5% are easily satisfied.

  In the above mold, the surface on the mold base portion on which the first plating layer and the second plating layer are formed may be either a flat surface or a curved surface. Preferably, in the above mold, the mold base portion has a substantially cylindrical space, and the first plating layer and the second plating layer may be formed on the inner wall of the space.

  In this case, it is suitable for molding of the rubber elastic part of the rubber roll, and the rough surface of the inner wall surface of the substantially cylindrical space is easily transferred to the surface of the rubber elastic part when the rubber elastic part is molded. be able to.

  The mold preferably has a release layer laminated along the surface of the second plating layer. Examples of the release layer include a plating layer in which fluorine resin particles such as polytetrafluoroethylene (PTFE) resin particles are dispersed. In this case, it is excellent in releasability from a rubber material or the like included in the rubber elastic portion forming material. Therefore, it becomes easy to accurately transfer the rough surface shape of the mold surface to the surface of the rubber elastic portion.

  The plating may be either electroless plating or electrolytic plating, but is preferably electroless plating with nickel, cobalt, copper, tin, palladium, alloys thereof, or the like. The plating is preferably electroless plating with nickel or a nickel alloy from the viewpoint of easy formation of each hole, corrosion resistance, cost, and the like.

  Next, a method for manufacturing the mold will be described. The method for manufacturing the mold is a method by which the mold can be preferably manufactured. In addition, since it is the same as that of description of the said mold | type about the mold base part of each process in the manufacturing method of the said mold | type, the 1st plating layer and the 2nd plating layer, description is abbreviate | omitted.

  In the mold manufacturing method, the first step includes (1A) a method of forming a first plating layer having a first hole portion by copying a part of the surface of bubbles generated by a plating reaction onto the surface of the plating layer. Or (1B) including a method of forming a first plating layer having a first hole by copying a part of the surface of the first substantially spherical particle onto the surface of the plating layer, and the second step includes ( 2) It is preferable to include a method of forming a second plating layer having a second hole by copying a part of the surface of the second substantially spherical particle onto the surface of the plating layer.

  In the case of the first step (1A), the shape of the first protruding portion of the rubber elastic portion obtained by mold transfer may be larger in the diameter of the first protruding portion than the height of the first protruding portion. Possible molds can be obtained. Moreover, in the case of the said 1st process (1B), the type | mold which can make the 1st protrusion part of the rubber elastic part obtained by transcription | transfer into the 1st protrusion part which has the surface containing a part of a substantially spherical surface. Can be obtained. In the case of the second step (2), a mold capable of making the second protruding portion of the rubber elastic portion obtained by the transfer into a second protruding portion having a surface including a part of a substantially spherical surface. Can be obtained.

  As the method of the first step (1A), specifically, the following method can be suitably exemplified.

  That is, using a plating bath containing at least metal ions to be plated metal and fine particles for adsorbing bubbles such as hydrogen gas generated by the plating reaction, electroless plating is performed on the surface of the mold base part, A plating layer having a large number of pits, which are plating defects, is formed on the surface. These pits are formed by bubbles generated during the plating reaction, such as hydrogen gas, adsorbed on the agglomerated part of the fine particles that co-deposited during plating, and further plating deposition was inhibited at the part where the bubbles were adsorbed. . According to this method, it is possible to form the first plating layer having a large number of first holes formed on the surface by copying a part of the surface of the bubble. The first hole may have a curved surface obtained by copying a part of the surface of a single bubble and / or a continuous bubble. In addition, the aggregation part of microparticles | fine-particles can be confirmed in the bottom part of the 1st hole part of the 1st plating layer formed by this method.

  Examples of the fine particles include fine particles made of silicon carbide, aluminum oxide, zirconium oxide, titanium oxide, polytetrafluoroethylene (PTFE), boron nitride and the like having an average particle diameter of about 0.5 to 5 μm. The PTFE fine particles are preferable from the viewpoint of excellent bubble adsorbability. The amount of the fine particles can be about 2 to 10 g / L. Further, in the plating bath, one or two or more cationic surfactants and / or amphoteric surfactants are used from the viewpoint of facilitating the adsorption of bubbles and forming the first hole portion more easily. It is preferable to add. Examples of the cationic surfactant include quaternary ammonium salt types such as lauryltrimethylammonium chloride and ethylene oxide addition type ammonium chloride. Examples of the amphoteric surfactant include betaine types such as lauryl betaine, amidopropyl betaine, and dimethylalkylbetaine. The amount of the cationic surfactant and / or amphoteric surfactant can be about 0.01 to 0.5 g / L. In addition, in the plating bath, there are other reducing agents (hypophosphorous acid, dimethylamine borane, hydrazine, etc., hypophosphorous acid from the viewpoint of the stability of the plating bath), complexing agents (citric acid, Malic acid, EDTA, etc.), pH buffering agents (lactic acid, acetic acid, succinic acid, etc.) and the like can be added alone or in combination.

  Further, as the method of the first step (1B), specifically, the following method can be suitably exemplified.

  That is, a plating layer containing a large number of first substantially spherical particles by performing electroless plating on the surface of the mold base portion using a plating bath containing at least metal ions to be plated metal and first substantially spherical particles. Form. Here, the formation of the plating layer is not performed such that when the plating layer is observed from the surface, the first substantially spherical particles are completely invisible due to the deposited plating. Plating until a part of the spherical particles is visible. The formation of the plating layer is in a state in which about 1/3 to 1/2 of the average particle diameter of the first substantially spherical particles is exposed from the surface of the plating layer from the viewpoint of obtaining a hole having an appropriate depth. Plating is preferably performed as described above. Then, the 1st substantially spherical particle currently hold | maintained at the plating layer is selectively removed. The removal can be performed in consideration of the material of the first substantially spherical particles. For example, if the material of the first substantially spherical particles is an organic material such as resin or rubber, the organic material may be dissolved in an appropriate solvent (acetone, MEK, toluene, NMP, etc.). It can also be burned off by heat treatment. According to the above method, it is possible to form a first plating layer having a large number of first holes formed on the surface by copying a part of the surface of the first substantially spherical particle.

  Examples of the first substantially spherical particles include organic particles such as acrylic, styrene, urethane, nylon, silicone, and cellulose having an average particle diameter of about 30 to 80 μm. Acrylic particles and styrene particles are preferable from the viewpoints of easy removal by a solvent and excellent dispersibility in a plating bath. The amount of the first substantially spherical particles can be about 1 to 100 g / L. In addition, in the said plating bath, from a viewpoint of improving the dispersibility of the 1st substantially spherical particle, the cationic surfactant and / or amphoteric surfactant mentioned above are in the range of about 0.01 to 10 g / L. It is preferable to add 1 type, or 2 or more types. In addition, one or more of the above-described reducing agents, complexing agents, pH buffering agents, and the like can be added.

  In addition, the method of the second step (2) can be specifically performed in the same manner as the method of the first step (1b) described above. However, in this case, instead of the first substantially spherical particles, second substantially spherical particles (the material is the same) having an average particle diameter of about 1 to 10 μm are used.

A rubber roll, a mold, and a method for manufacturing the mold according to an embodiment of the present invention will be specifically described with reference to the drawings.
First, a schematic configuration of the rubber roll of this example will be described with reference to FIGS. As shown in FIGS. 1 and 2, the rubber roll 1 is a developing rubber roll incorporated in an image forming apparatus employing an electrophotographic system. The rubber roll 1 has a rubber elastic portion 2 whose surface is roughened by mold transfer by a mold 4 of this example described later. The rubber elastic portion 2 is formed in layers along the outer periphery of the solid cylindrical long shaft 3. The rubber elastic portion 2 is made of conductive silicone rubber and has a thickness of 4 mm. Note that an unsaturated carbon-carbon double bond exists on the surface of the rubber elastic portion 2.

As shown in FIGS. 3 to 5, the rubber elastic portion 2 has a large number of first protruding portions 21 and second protruding portions 22. The first projecting portion 21 projects outward from the surface of the rubber elastic portion 2. The 2nd protrusion part 22 protrudes outward from the 1st protrusion part 21 and the rubber elastic part 2 surface of the circumference | surroundings. The diameter φ ₂ of the second protrusion 22 is smaller than the diameter φ ₁ of the first protrusion 21, and the height h ₂ of the second protrusion 22 is lower than the height h ₂ of the first protrusion 21. Has been. The surface of the second protrusion 22 includes a part of a substantially spherical surface. In the present example, the second projecting portion 22 is formed to project in a substantially hemispherical shape.

In the following, as will be described later, first protrusions 21 measured by the above-described method are prepared by producing molds 4 with various changes in the rough state of the mold surfaces and transferring the mold surfaces of these molds 4. Rubber roll samples were prepared in which the diameter φ ₁ , height h ₁ , area ratio Ap ₁ , and diameter φ ₂ , height h ₂ , and area ratio Ap ₂ of the second protrusion 22 were variously changed. Moreover, although FIGS. 1-5 has shown the example which does not coat | cover the surface layer on the surface of the rubber elastic part 2, the sample which formed the surface layer in order to provide mold release property was also produced. When the surface layer was not formed, the surface of the rubber elastic portion 2 was surface-modified to provide releasability.

Next, the schematic configuration of the mold of this example will be described with reference to FIGS. As shown in FIG. 8B, the mold 4 includes a mold base portion 5, a first plating layer 51, and a second plating layer 52. The 1st plating layer 51 is laminated | stacked through the base | substrate plating layer (not shown) on the type | mold base material part 5, and has the many 1st hole parts 511 dented inward on the surface. The second plating layer 52 is laminated along the first hole 511 of the first plating layer 51 and the surface around it, and has a number of second holes 522 that are recessed inward. As shown in FIG. 9, the diameter Φ ₂ of the second hole 522 is smaller than the diameter Φ _{1 of} the first hole 511, and the depth d ₂ of the second hole 522 is the depth of the first hole 511. It is shallower than d ₁ is. The surface of the second hole 522 includes a part of a substantially spherical surface. In this example, the second hole 522 is formed to be recessed in a substantially hemispherical shape.

  Here, each of the plating layers 51 and 52 is composed of an electroless nickel plating layer. Although not shown, the mold base part 5 has a substantially cylindrical hollow space in which the rubber elastic part 2 of the rubber roll 1 can be formed. And the 1st plating layer 51 and the 2nd plating layer 52 are formed on the inner wall of this space.

In addition, below, as shown in Table 1 described later, the first hole portion 511 measured by the above-described method by variously changing the plating conditions at the time of forming the first plating layer 51 and the second plating layer 52. Mold samples were prepared in which the diameter Φ ₁ , depth d ₁ , area ratio Bp ₁ , and diameter Φ ₂ , depth d ₂ , and area ratio Bp ₂ of the second hole 522 were variously changed. FIG. 8 shows an example in which no other plating layer is formed on the surface of the second plating layer 52, but in the preparation of the following samples, the releasability from the rubber elastic portion described above is improved. Therefore, an electroless nickel plating layer in which PTFE fine particles are dispersed is laminated as a release plating layer (not shown) on the surface of the second plating layer 52 so that the rough surface state of the surface of the second plating layer 52 is not impaired. did.

  Next, schematic steps of the mold manufacturing method of this example will be described with reference to FIGS. As shown in FIG. 6, first, in the first step (1A), on the inner wall of the substantially cylindrical hollow space of the mold base part 5, a large number of first holes 511 that are recessed inward are formed on the surface. The 1st plating layer 51 which has was formed. Specifically, in this example, as shown in FIG. 6 (a), hydrogen gas 513 generated by the plating reaction is adsorbed on the agglomerated portion 512 of PTFE fine particles co-deposited in the plating 51b, and thereafter, FIG. As shown in FIG. 5, a part of the surface of the hydrogen gas 513 was copied on the surface of the plating layer 51 as a trace of the separation of the hydrogen gas 513 from the aggregation portion 512. Thereby, the 1st plating layer 51 which has the 1st hole 511 was formed.

  Instead of the first step (1A), the first step (1B) as shown in FIG. 7 can be adopted. In this case, in the first step (1B), a part of the surface of the first substantially spherical particle is copied onto the surface of the plating layer, thereby forming the first plating layer having the first hole. Specifically, as shown in FIG. 7A, electroless plating is performed on the inner wall of the substantially cylindrical hollow space of the mold base portion 5 to obtain a large number of first substantially spherical particles (acrylic resin particles) 514. The plating layer 51a containing is formed. At this time, the plating conditions are adjusted so that about 1/3 to 1/2 of the average particle diameter of the first substantially spherical particles 514 is exposed from the surface of the plating layer 51a. Thereafter, as shown in FIG. 7B, the first substantially spherical particles 514 held in the plating layer 51a are dissolved in an organic solvent (acetone or the like) and selectively removed. Thus, the 1st plating layer 51 which has the 1st hole 511 can also be formed by copying a part of surface of the 1st substantially spherical particle 514 on the surface of a plating layer.

  In addition, after the first step (1A) or (1B), as shown in FIG. 8, in the second step, along the first hole 511 of the first plating layer 51 and the surrounding surface, A second plating layer 52 having a large number of second holes 522 that were recessed in the direction was formed. In this example, specifically, as shown in FIG. 8A, electroless plating is performed on the first plating layer 51, and along the first hole 511 of the first plating layer 51 and the surrounding surface. Thus, a plating layer 52a containing a large number of second substantially spherical particles (acrylic resin particles) 524 was formed. At this time, the plating conditions were adjusted so that about 1/3 to 1/2 of the average particle diameter of the second substantially spherical particles 524 was exposed from the surface of the plating layer 52a. Thereafter, as shown in FIG. 8B, the second substantially spherical particles 524 held in the plating layer 52a were dissolved in an organic solvent (acetone or the like) and selectively removed. In this way, a part of the surface of the second substantially spherical particle 524 was copied onto the surface of the plating layer, thereby forming the second plating layer 52 having the second hole portion 522.

Hereinafter, specific description will be given based on the prepared sample. By the following procedure, a sample 1 developing rubber roll having a rubber elastic portion to which the mold surface of the sample 1 and the mold surface of the sample 1 were transferred was prepared.
(Preparation of basic plating bath)
Nickel sulfate hexahydrate 20 g / L, sodium hypophosphite monohydrate (reducing agent) 25 g / L, lactic acid (complexing agent) 27 g / L, propionic acid (complexing agent) 2.5 g / L was added to prepare a basic plating bath having a pH of 4.8.

(Preparation of plating bath for the first step)
A dispersion (1) was prepared by dispersing 5 g / L of PTFE fine particles having an average particle diameter of 0.2 μm in water using 0.1 g / L of a cationic surfactant (lauryltrimethylammonium chloride). And this dispersion liquid (1) was added to the said basic plating bath, and it was set as the plating bath for 1st processes.

(Preparation of plating bath for the second step)
Disperse 12 g / L of acrylic particles (Negami Kogyo Co., Ltd., “Art Pearl GR-600”) having an average particle size of 10 μm in water using 0.1 g / L of a cationic surfactant (lauryltrimethylammonium chloride). A dispersion (2) was prepared. And this dispersion liquid (2) was added to the said basic plating bath, and it was set as the plating bath for 2nd processes.

(Preparation of plating bath for forming release plating layer)
A dispersion (3) was prepared by dispersing 10 g / L of PTFE fine particles having an average particle diameter of 0.2 μm in water using 0.2 g / L of a cationic surfactant (lauryltrimethylammonium chloride). And this dispersion liquid (3) was added to the said basic plating bath, and it was set as the plating bath for mold release plating layer formation.

(Mold making-first step)
A mold having a mold base portion made of SACM645 (aluminum chromium molybdenum steel) in which a substantially cylindrical hollow space having an inner diameter of 16 mm was formed was prepared. And the foundation | substrate electroless nickel plating layer (thickness 10 micrometers) was formed on the inner wall surface of the hollow space of the prepared type | mold. Next, electroless nickel plating is performed on the inner wall surface of the hollow space where the base electroless nickel plating layer is formed using the above-described first step plating bath under the conditions of a plating solution temperature of 90 ° C. and a plating time of 60 minutes. The first plating layer (thickness 16 μm) was formed.

  FIG. 10 is a surface observation photograph of the first plating layer. FIG. 10 is an enlarged view of the surface of the first plating layer in the axial center portion of the hollow space with the digital microscope described above, (a) is 200 times magnification and (b) is 1000 times magnification. . As can be seen from FIG. 10, the surface of the first plating layer has many holes formed by pits recessed inward. In the holes formed by the pits, hydrogen gas (bubbles) generated during the plating reaction is adsorbed to the agglomerated portion of PTFE fine particles co-deposited during the plating, and further deposition of the plating is inhibited by the adsorbed hydrogen gas (bubbles). It is formed and is a trace of the lower surface of hydrogen gas (bubbles) being copied. Further, according to FIG. 10, not only a hole portion formed by a single hydrogen gas (bubble) but also a relatively large hole portion formed by connecting a plurality of hydrogen gases (bubbles) can be confirmed. Further, according to FIG. 10, it can be seen that many of these holes have a larger diameter than the depth of the holes. Thus, the 1st plating layer which has many 1st hole parts indented inward on the inner wall surface of the hollow space of a type substrate part was formed.

(Mold making-second step)
Next, the surface of the first plating layer laminated on the inner wall surface of the hollow space is electroless nickel using the second step plating bath at a plating solution temperature of 90 ° C. and a plating time of 60 minutes. Plating was performed. Next, the acrylic particles taken into the formed plating layer were selectively dissolved and removed with acetone. Thereby, the 2nd plating layer (thickness 11 micrometers) was formed in the surface of the said 1st plating layer.

  FIG. 11 is a surface observation photograph of the second plating layer. FIG. 11 is an enlarged view of the surface of the second plating layer at the axially central portion of the hollow space with the above-mentioned digital microscope, (a) is 200 times magnification, and (b) is 1000 times magnification. . According to FIG. 11, a large number of large-diameter holes are found on the surface of the second plating layer, which is the upper layer, and a small-diameter hole having a smaller diameter than that of the large-diameter hole in and around the large-diameter hole. It can be seen that many parts are seen. FIG. 12 shows cross-sectional observation photographs of the first plating layer and the second plating layer. Note that FIG. 12 is for the type of sample 2 described later, but the type of sample 1 also had a cross section showing the same tendency as the type of sample 2. According to the cross-sectional observation result, the large-diameter hole portion visible on the surface of the second plating layer is the second plating layer following the surface in the first hole portion and the periphery of the first hole portion in the first plating layer. As a result, it was confirmed that it was present corresponding to the position of the first hole. Further, only the small-diameter hole portion was directly formed on the entire surface of the second plating layer. Further, from the observation results, it is clear that the diameter of the small-diameter hole is smaller than the diameter of the first hole, the depth of the small-diameter hole is shallower than the depth of the first hole, and the small-diameter hole is It can be said that there are two holes. Further, the second hole portion is a trace of the lower surface of the dissolved and removed acrylic particles mainly copied onto the surface of the second plating layer, and is formed from a substantially hemispherical depression. That is, the surface of the second hole portion had a part of a substantially spherical surface corresponding to the surface shape of the acrylic particles. Thus, the 2nd plating layer which has many 2nd hole parts indented inward along the surface of the 1st hole of the 1st plating layer and the circumference was formed. The mold of Sample 1 was manufactured through the above steps.

  A release plating layer (thickness 1 μm) was formed on the surface of the second plating layer in the mold of Sample 1. The release plating layer is for improving the releasability with the rubber material, and was formed so as not to impair the rough surface state of the second plating layer surface. Specifically, the release plating layer is formed by using electroless nickel on the surface of the second plating layer using a release bath for forming a release plating layer at a plating solution temperature of 90 ° C. and a plating time of 10 minutes. Plating was performed by forming a plating layer containing eutectoid PTFE fine particles.

(Production of rubber roll for development)
In the hollow space of the sample 1 type, a solid cylindrical long shaft body made of iron having a diameter of 8 mm and a length of 274 mm and having a surface plated with Ni was set coaxially. Then, after filling the space between the hollow space and the shaft body with conductive silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., “X-34-264A / B”, mixing mass ratio 30/70), By heating this mold at 190 ° C. for 30 minutes, a substantially cylindrical rubber elastic portion (length in the axial direction) made of conductive silicone rubber leaving a C═C bond on the surface along the outer periphery of the shaft body. (Roll surface length) 230 mm, thickness 4 mm).

  FIG. 13 shows a surface observation photograph of the rubber elastic part. FIG. 13 is an enlarged view of the surface of the rubber elastic portion at the central portion in the axial direction with the digital microscope described above, and the magnification is 1000 times. According to FIG. 13, it can be confirmed that the rough surface state of the mold of the sample 1 is transferred to the surface of the rubber elastic portion. That is, the rubber elastic portion protrudes outward from a large number of first protrusions (corresponding to the first hole of the first plating layer) protruding outward from the surface, and the first protrusion and its surrounding surface. A plurality of second projecting portions (corresponding to the second hole portions of the second plating layer), and the diameter of the second projecting portion is smaller than the diameter of the first projecting portion, and the height of the second projecting portion is high. It can be confirmed that the height is lower than the height of the first protrusion. Moreover, it turns out that the 2nd protrusion part is formed in the substantially hemispherical shape, and the surface contains a part of substantially spherical surface.

  Separately, 10 masses of carbon black (manufactured by Denki Kagaku Kogyo Co., Ltd., “Denka Black HS-100”) is added to 100 parts by mass of urethane resin (manufactured by Nippon Polyurethane Co., Ltd., “Nipporan 5199”) with a ball mill. After kneading, 400 parts by mass of MEK was added and mixed and stirred to prepare a surface layer forming material.

  And the said surface layer forming material was applied to the outer peripheral surface of the said rubber elastic part by the roll coat method, and the surface layer (5 micrometers in thickness) was formed by heating at 170 degreeC for 60 minute (s). This surface layer is formed to a thickness that does not impair the rough surface state of the rubber elastic portion, and is for improving the releasability from the toner. Thus, a developing rubber roll of Sample 1 having a rubber elastic portion to which the mold surface of the sample 1 was transferred was obtained.

(Types of Samples 2 to 10 and Development Rolls of Samples 2 to 10)
Sample 2 was prepared in the same manner as above except that the plating conditions for the first plating layer in the first step and the plating conditions for the second plating layer in the second step were changed as shown in Table 1 in the production of the mold of Sample 1. Ten molds were produced.

  Separately, 5 parts by mass of trichloroisocyanuric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1 part by mass of silicone oil (“X-22-174DX” manufactured by Shin-Etsu Silicone Co., Ltd.) as a component containing a C═C bond A surface modifier was prepared by mixing 80 parts by weight of tert-butyl alcohol and 20 parts by weight of ethyl acetate.

  Further, in the production of the developing rubber roll of Sample 1, the rubber elastic part was formed using the molds of Samples 2 to 10, the thickness of the surface layer was changed as shown in Table 2, and some of the other Is the same as above except that the surface of the rubber elastic part is surface-modified using the surface modifier instead of forming a surface layer, and the rubber elastic part obtained by transferring the mold surfaces of the samples 2 to 10 Development rubber rolls of Samples 2 to 10 having the above were prepared. The surface modification was performed by immersing the rubber elastic part surface in the prepared surface modifier at 25 ° C. for 30 seconds, washing the rubber elastic part surface with ethyl acetate at 25 ° C. for 30 seconds, and then adding 100 The drying was performed at 10 ° C. for 10 minutes.

(Development roll of sample 11)
In the production of the developing rubber roll of Sample 1, a rubber elastic portion was formed on the outer periphery of the shaft using a mold in which the first plating layer and the second plating layer were not formed on the inner wall surface of the hollow space. And the surface layer forming material containing the particle | grains for roughness formation was apply | coated by the roll coat method on the surface of this rubber elastic part, and the surface layer roughened by the particle | grains for roughness formation was formed. Thus, a developing rubber roll of Sample 11 in which the surface of the rubber elastic portion was roughened by the roughness forming particles was produced.

  In addition, the surface layer forming material including the particles for forming the roughness is carbon black (manufactured by Denki Kagaku Kogyo Co., Ltd., “DENKA BLACK HS” with respect to 100 parts by mass of urethane resin (manufactured by Nippon Polyurethane Co., Ltd., “Nipporan 5199”). -100 ") 10 parts by mass, 30 parts by mass of acrylic resin particles (Soken Chemical Co., Ltd.," MX-1500 ", average particle size 13 µm) as roughness forming particles were kneaded in a ball mill, and then 400 masses of MEK. Part was added and mixed and stirred.

(Sample 12 mold and sample 12 developing roll)
In the production of the mold of the sample 1, the mold in which the first plating layer is formed on the inner wall surface of the hollow space without performing the second step was used as the mold of the sample 12. Further, in the production of the developing roll of Sample 1, the rubber elastic part was formed using the mold of Sample 12, and as shown in Table 2, except that the thickness of the surface layer was changed, the same as above, A developing rubber roll for Sample 12 having a rubber elastic portion to which the mold surface of Sample 12 was transferred was prepared. In FIG. 14, the surface observation photograph of the rubber elastic part in the developing rubber roll of Sample 12 is shown. As can be seen from FIG. 14, the surface of the rubber elastic portion of the developing rubber roll of Sample 12 has only the first protrusion.

(Measurement of rough surface of rubber elastic part)
About each produced rubber roll for development, the rough surface state of each rubber elastic part was measured based on the measuring method mentioned above. Specifically, the diameter φ ₁ , height h ₁ , area ratio Ap ₁ of the first protrusion, the diameter φ ₂ , height h ₂ , and area ratio Ap ₂ of the second protrusion were measured. The results are shown in Table 2.

(Toner transport amount)
The toner transport amount was measured for each of the developed rubber rolls for development. The toner transport amount was measured by a method in which toner of a certain area on the developing rubber roll was sucked by a nozzle sucked by a hydraulic pump and the weight difference between the nozzles before and after the suction was measured. The toner used has an average particle size of 8 μm. In this example, an appropriate toner conveyance amount is set in the range of 4 to 6 mg / cm ² .

(Toner adhesion)
The toner adhesion was evaluated for each of the developed rubber rolls for development. Specifically, each developing rubber roll was incorporated into a commercially available color laser printer (“C5900” manufactured by Oki Data Corporation) and cyan (toner average particle diameter is 8 μm) in an environment of 28 ° C. × 80% RH. ), 1000 sheets, 5000 sheets, and 30000 sheets (each A4 size) of the image were printed, and the degree of adhesion of the toner to the blade member for layer formation after the durability was investigated. The case where the number of fixing points was less than one was designated as A, the case where the number of fixing points was two to four, B, the case where the number of fixing points was five to nine, and the case D where the number of fixing points was 10 or more.

  According to Tables 1 and 2, the following can be understood. That is, the developing rubber roll of Sample 11 has the surface of the rubber elastic portion roughened by the surface layer in which the roughness forming particles are dispersed. Therefore, the surface layer hardness is high, the toner is stressed, and the toner sticks easily to the blade member. Further, when used for a long time, the toner sticking tends to occur easily. Further, the toner conveyance amount also decreased. The reason why the toner conveyance amount decreases due to the long-term use is that the tip of the convex portion due to the roughness forming particles is scraped by repeated use and the toner holding power is reduced.

  In the developing rubber roll of Sample 12, the surface of the rubber elastic portion is only the first protruding portion. Therefore, there is no particular problem with the toner conveyance amount, but the contact area between the toner and the gap between the first protrusion and the first protrusion increases. For this reason, the toner is stressed, and toner sticking is likely to occur on the blade member from the initial state. Further, when used over a long period of time, there was a tendency that the toner sticking was more likely to occur.

  On the other hand, the developing rolls of Samples 1 to 7, 9, and 10 can obtain an appropriate toner conveyance amount due to the high toner holding power even though the surface is roughened by mold transfer. In addition, the toner adhesion to the blade member can be suppressed by reducing the stress on the toner. However, when the surface layer is formed on the surface of the rubber elastic portion like the developing rubber roll of Sample 8, if the surface layer is too thick, the rough surface of the rubber elastic portion is filled with the surface layer, and an appropriate toner conveyance amount is obtained. It turns out that it becomes impossible to obtain. It can also be seen that the effect of the surface layer made of resin is increased and the effect of reducing the stress on the toner is also reduced. Therefore, when forming a surface layer on the surface of a rubber elastic part, you should pay attention to these. In the case of this example, it is understood that there is no particular problem if the surface layer is 10 μm or less.

Further, in the developing rolls of Samples 1 to 6, on the rubber elastic portion surface, the first protrusion satisfies 30 μm ≦ φ ₁ ≦ 80 μm, 5 μm ≦ h ₁ ≦ 25 μm, 30% ≦ Ap ₁ ≦ 70%, 2 protrusions satisfy 1 μm ≦ φ ₂ ≦ 10 μm, 1 μm ≦ h ₂ , 30% ≦ Ap ₂ ≦ 78.5%. Therefore, it is excellent in the balance between toner transportability by an appropriate toner holding force and the effect of reducing stress on the toner. Moreover, it turns out that the said effect is acquired over a long term. Therefore, it can be said that it can contribute to the improvement of durability of various image forming apparatuses adopting the electrophotographic system in which these developing rubber rolls are incorporated.

  As mentioned above, although the Example of this invention was described in detail, this invention is not limited to the said Example, A various change is possible within the range which does not impair the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Rubber roll 2 Rubber elastic part 21 1st protrusion part 22 2nd protrusion part 3 Long axis body 4 type | mold 5 type | mold base material part 51 1st plating layer 511 1st hole part 512 Aggregation part 513 Hydrogen gas (bubble)
514 First substantially spherical particles 52 Second plating layer 522 Second hole portion 524 Second substantially spherical particles

Claims (9)

A rubber roll having a rubber elastic portion whose surface is roughened by mold transfer,
The rubber elastic portion has a number of first protrusions protruding outward from the surface thereof, and a number of second protrusions protruding outward from the first protrusion and its surrounding surface,
The diameter of the said 2nd protrusion part is smaller than the diameter of the said 1st protrusion part, and the height of the said 2nd protrusion part is lower than the height of the said 1st protrusion part, The rubber roll characterized by the above-mentioned. In the rubber roll according to claim 1,
The rubber roll characterized in that the surface of the second protrusion includes a part of a substantially spherical surface. In the rubber roll according to claim 1 or 2,
The first protrusion has a larger diameter than the first protrusion, and / or the surface of the first protrusion includes a part of a substantially spherical surface. . In the rubber roll according to any one of claims 1 to 3,
The first protrusion is 30 ≦ φ ₁ ≦ 80, 5 ≦ h ₁ ≦ 25, 30 ≦ Ap ₁ ≦ 70 (where φ ₁ is the diameter [μm] of the first protrusion, and h ₁ is the first The height [μm] of the protruding portion, Ap ₁ satisfies the area ratio [%] of the first protruding portion when the photographed image of the surface of the rubber elastic portion is binarized using a discriminant analysis method,
The second protrusion is 1 ≦ φ ₂ ≦ 10, 1 ≦ h ₂ , 30 ≦ Ap ₂ ≦ 78.5 (where φ ₂ is the diameter [μm] of the second protrusion, and h ₂ is the second The height [μm] and Ap ₂ of the protrusion satisfy the area ratio [%] of the second protrusion when the photographed image of the surface of the rubber elastic portion is binarized using a discriminant analysis method. A rubber roll characterized by In the rubber roll according to any one of claims 1 to 4,
The rubber elastic part is characterized in that the rubber elastic part has conductivity. Mold base part,
A first plating layer laminated on the mold base and having a plurality of first holes recessed inward on the surface;
A second plating layer that is laminated along the first hole portion of the first plating layer and the surface around the first hole portion and has a plurality of second hole portions that are recessed inward;
The mold characterized in that the diameter of the second hole is smaller than the diameter of the first hole, and the depth of the second hole is shallower than the depth of the first hole. The mold according to claim 6, wherein
The mold base part has a substantially cylindrical space, and the first plating layer and the second plating layer are formed on an inner wall of the space. A first step of forming a first plating layer having a large number of indented first holes on the surface of the mold base portion;
A second step of forming a second plating layer having a plurality of indented second holes on the surface along the first hole of the first plating layer and the surrounding surface thereof; and
A mold manufacturing method, characterized in that a diameter of the second hole portion is smaller than a diameter of the first hole portion, and a depth of the second hole portion is adjusted to be shallower than a depth of the first hole portion. In the manufacturing method of the type | mold of Claim 8,
In the first step, the first plating layer having the first hole is obtained by copying a part of the surface of the bubble generated by the plating reaction or the part of the surface of the first substantially spherical particle onto the surface of the plating layer. Including a method of forming
The second step includes a method of forming a second plating layer having the second hole portion by copying a part of the surface of the second substantially spherical particle onto the surface of the plating layer. Production method.