JP5847636B2 - Image carrier cleaning roller and image forming apparatus - Google Patents

Description

  The present invention relates to an image carrier cleaning roller and an image forming apparatus, and more specifically, an image carrier cleaning roller that exhibits a high level of cleaning performance of an image carrier and an image that can form a high-quality image over a long period of time. The present invention relates to a forming apparatus.

  Various image forming apparatuses using an electrophotographic method are employed in printers such as laser printers and video printers, copiers, facsimiles, and multi-function machines thereof. In order to form a high-quality image, an image forming apparatus using an electrophotographic system is provided with a cleaning device that removes a developer that has not been transferred or conveyed as desired or an attached developer. There is.

  As such a cleaning device, for example, a cleaning device that removes foreign matters such as developer or deposits remaining on an image carrier, that is, a photoreceptor is known. The cleaning device includes a blade system having a cleaning blade that scrapes off or adheres foreign matter remaining on the surface of the image carrier with a cleaning blade or the like. There are a roller system provided with a cleaning roller that is received by pressure contact, a combined system that uses both a blade system and a roller system.

For example, Patent Document 1 discloses that “(a) an image carrier, (b) a charging unit that is disposed to face the image carrier and charges the surface of the image carrier, and (c) the image carrier”. An exposure apparatus that exposes a body to form an electrostatic latent image; (d) a developing unit that develops the electrostatic latent image into a toner image; and (e) a transfer unit that transfers the toner image to a transfer material. And (f) cleaning means for removing toner remaining on the surface of the image carrier after transfer, and (g) at least one of the charging means, developing means, transfer means, and cleaning means is foamed. (H) the silicone rubber has a cell diameter of 0.2 to 0.3 mm, and the partition wall thickness is more than half of the cell diameter. An image forming apparatus ”is defined in claim 1 and“ the cleaning apparatus ”. The means comprises a cleaning roller, which has a surface cell count of 30-50 [pieces / inch], a hardness of 35 ± 5 [°] (Asker C), a temperature of 20 [° C.] and The resistance value at a humidity of 50 [%] is approximately 10 ⁷ [Ω] ”.

Patent Document 2 states that “the roller surface comes into contact with the photosensitive drum and the residual toner remaining on the photosensitive drum is sucked by a bias voltage, and the sucked residual toner is formed on the surface of the roller. In the image forming apparatus provided with the cleaning unit held in the hole, when the particle diameter of the toner is 6 μm or more and 9 μm or less, the diameter of the hole is 50 μm or more and 150 μm or less, and the electric resistance value of the roller is 5 "Image forming apparatus characterized in that x10 ⁶ Ω or more and 5 x 10 ⁹ Ω or less" is described (claim 1 and the like).

The transfer belt cleaning roller is described in JP-A No. 2004-133218, which describes “For an endless transfer belt for transferring a toner image on one or a plurality of electrostatic latent image carriers, A transfer belt cleaning roller disposed in contact with the outer peripheral surface of the belt and removing deposits on the transfer belt, comprising a cored bar and a polyurethane foam layer covering the outer peripheral surface of the cored bar, The polyurethane foam layer has 30 or more and 60 or less cells per inch, and the opening ratio of the cell walls of the polyurethane foam layer is 3 to 50%. "Cleaning roller" is described (claim 1 etc.). Regarding this “opening ratio”, Patent Document 3 states that “a cell 80 having an opening 82 on a wall surface is connected to another cell 80 via the opening 82. The area of the opening 82 relative to the area S of the entire wall surface of the cell 80. aperture ratio the ratio of S ₁ and "Then is described (0045 column), the" aperture ratio "of the cell opening an opening ratio of the opening 82 which opens into the wall of the cell 80 on the surface of the polyurethane foam layer There is no description regarding the aperture ratio in Patent Document 3.

Japanese Patent Application Laid-Open No. 07-333996 Japanese Patent No. 3514974 JP 2009-300741 A

  By the way, when the cleaning roller of Patent Document 1 and the roller of Patent Document 2 are actually mounted on the image forming apparatus, the intended effect may not be exhibited. As a result of various studies by the inventor of the present invention, the cleaning roller of Patent Document 1 has a developer scraping performance due to “the number of cells is limited to 30 to 50 [pieces / inch]” (Claim 6). I suspect that the decline is one of the reasons. Further, the inventors of the present invention have made various studies. As a result, the roller of Patent Document 2 has a too small cell due to “the diameter of the hole being limited to 50 μm or more and 150 μm or less” (Claim 1). It is presumed that the developer is likely to adhere, and is difficult to peel once attached, and that the cleaning performance deteriorates abruptly depending on the remaining amount of the developer on the photosensitive drum.

  Even if the transfer belt cleaning roller of Patent Document 3 is mounted as an image carrier cleaning roller, the image carrier and the transfer belt have different uses and required characteristics in the first place, so that they remain or adhere to the image carrier. In some cases, the foreign matter cannot be removed, and in addition, it is easy to wear and has poor durability. Even if the transfer belt cleaning roller of Patent Document 3 is mounted as an image carrier cleaning roller, “the number of cells per inch is limited to 30 or more and 60 or less”. It is easily guessed that the effect of the period is not exhibited.

  Accordingly, it is an object of the present invention to provide an image carrier cleaning roller that exhibits a high level of image carrier cleaning performance.

  Another object of the present invention is to provide an image forming apparatus capable of forming a high-quality image over a long period of time.

  The inventor of the present invention has studied in detail the characteristics of the foamed elastic layer of the cleaning roller for the image carrier, and found that the number of cells present in the foamed elastic layer and the open area ratio of the cells opened on the outer peripheral surface of the foamed elastic layer. It has been found that excellent balance of cleaning performance can be achieved over a long period of time without greatly degrading.

Therefore, as means for solving the above problems,
Claim 1 is a cleaning roller for an image carrier having a foamed elastic layer having a plurality of cells, and a cell that opens to the outer peripheral surface of the foamed elastic layer among the cells is 1.0 mm × the outer peripheral surface. there 3-20 to 1.0mm region, and Ri total open area of 50% to 85% der which opens into the region of the surface area 1 mm ² of the region, among the cells that the foamed elastic layer has The cells that do not open to the outer peripheral surface have an average ellipticity of 0.85 or more and an opening that opens to a cross-sectional area of 1.0 mm × 1.0 mm in an arbitrary cross section of the foamed elastic layer. An image bearing member cleaning roller having an average ratio of 10 (circumferential diameter X / surface diameter Y) and having an average cell diameter of 200 to 400 μm in the foamed elastic layer . ,
Claim 2, wherein the foamed elastic layer is an image carrier cleaning roller according to claim 1, characterized in that it has a backbone JIS A hardness is formed with a rubber 25-45,
Claim 3 is the cleaning roller for an image carrier according to claim 1 or 2 , wherein the foamed elastic layer has an Asker C of 30 to 50 °.
Claim 4 is the cleaning roller for an image carrier according to any one of claims 1 to 3 , wherein the foamed elastic layer mainly has an independent cell state.
According to a fifth aspect of the present invention, the image bearing member for holding a latent image and the cleaning roller for the image bearing member according to any one of the first to fourth aspects are disposed so as to be in contact with the image bearing member. An image forming apparatus characterized by the above.

The image bearing member cleaning roller according to the present invention has 3 to 20 cleaning rollers in a 1.0 mm × 1.0 mm region on the outer peripheral surface, and a total opening area that opens to the region with respect to a surface area of 1 mm ^{2 in the} region. there have a cell opening to an outer peripheral surface of the foamed elastic layer as a 50% to 85%, also, because the average cell diameter of the cells present in the foamed elastic layer is provided with a foamed elastic layer is 200~400μm The cell walls (also referred to as partition walls) existing between the cells are inevitably thickened, and the cell walls, and thus the cells are hardly destroyed. As described above, the image carrier cleaning roller according to the present invention is highly resistant to destruction of the cell walls and the cells. Therefore, the hardness of the foamed elastic layer is reduced due to cell destruction, and the developer enters the foamed elastic layer. In addition, it is possible to effectively prevent the deterioration of the cleaning performance due to the fixing and the fluctuation of the resistance value of the foamed elastic layer.

  Therefore, according to the present invention, it is possible to provide an image carrier cleaning roller that exhibits a high level of cleaning performance of the image carrier and an image forming apparatus that can form a high-quality image over a long period of time.

  In addition, the average ratio (circumferential diameter X / surface direction) of the cell opening to an arbitrary cross-sectional area (1.0 mm × 1.0 mm) is 0.85 to 1.10. If the diameter is Y), since the cell is close to a perfect circle (true sphere), it is possible to uniformly disperse the pressing force acting on the cell. The deterioration of the cleaning performance that tends to decrease can be effectively suppressed, and the initial high cleaning performance can be maintained for a longer period of time.

  In particular, when the foamed elastic layer has a skeleton formed of rubber having a JIS A hardness of 25 to 45, even when the cell wall is thickened by reducing the number of cells and the total opening area within the above range, Since the skeleton of the surface of the cleaning roller that comes into contact with the body and foreign matter has a relatively low hardness, the foamed elastic layer exhibits flexibility and the cells are extremely difficult to be destroyed, and the durability of the foamed elastic layer is remarkably improved. In addition, when the hardness of the skeleton constituting the foamed elastic layer is relatively low, the overall hardness of the foamed elastic layer is also low, so that the image carrier remains or adheres to the image carrier. Therefore, the stress or damage given to the foreign matter, particularly the developer, is small, and the quality of the formed image is not deteriorated.

  In addition, since the image forming apparatus according to the present invention includes the image carrier cleaning roller according to the present invention, it is possible to prevent the image quality from being deteriorated due to the characteristic variation of the image carrier cleaning roller.

FIG. 1 is a perspective view showing an image carrier cleaning roller which is an example of an image carrier cleaning roller according to the present invention. FIG. 2 is a partial cross-sectional view showing a cross section of an image carrier cleaning roller as an example of an image carrier cleaning roller according to the present invention. FIG. 3 is a schematic view showing an example of an image forming apparatus according to the present invention. FIG. 4 is a schematic diagram showing a durability test apparatus that is preferably used for carrying out a durability test of the image bearing member cleaning roller in the embodiment.

  The cleaning roller for an image carrier according to the present invention only needs to have a foamed elastic layer that satisfies the characteristics described later. In addition to the foamed elastic layer, a shaft body that supports the foamed elastic layer, the shaft body, and the foamed elastic layer There may be another layer such as an elastic layer, an adhesive layer or a primer layer between them. The image bearing member cleaning roller according to the present invention will be specifically described below.

  As shown in FIGS. 1 and 2, an image carrier cleaning roller 1 as an example of an image carrier cleaning roller according to the present invention includes a shaft body 2 and a foam disposed on an outer peripheral surface of the shaft body 2. The foamed elastic layer 3 is the outermost layer and does not have a coat layer or a surface layer.

  The image bearing member cleaning roller 1 has a relatively low hardness. Specifically, the Asker C hardness is preferably 30 to 50 °, and particularly preferably 35 to 48 °. When the Asker C hardness is within the above range, the image bearing member cleaning roller 1 can ensure a sufficient nip width with the image bearing member in contact or pressure contact, and the image bearing member of course remains or adheres to the image bearing member. Since the stress or damage given to the foreign matter, particularly the developer, is small, damage to the image carrier and destruction of the developer are prevented, and sufficient cleaning performance is exhibited, the quality of the formed image is not deteriorated. Asker C hardness (1 kg load) can be measured according to JIS K6253. The Asker C hardness of the image carrier cleaning roller according to the present invention is selected, for example, from the types of silicone rubber, foaming agent and / or additive contained in the foamed silicone rubber composition forming the foamed elastic layer, and It can be adjusted by changing the blending amount or the like thereof, or by the molding conditions of the foamed elastic layer.

The image bearing member cleaning roller 1 preferably has an electrical resistance value of 10 ^5.5 to 10 ^7.5 Ω (log value ^5.5 to ^7.5 ), and 10 ⁶ to 10 ⁷ Ω. It is particularly preferable to have an electrical resistance value of The electric resistance value is an electric resistance value before using the image carrier cleaning roller 1. When the electric resistance value is within the above range, the electric removal ability to electrically remove foreign matters remaining on or attached to the image carrier, particularly the developer, from the image carrier is increased, and the cleaning performance is further improved. be able to. The electrical resistance value is obtained by, for example, using an electrical resistance meter (trade name: ULTRA HIGH RESISTANCE METER R8340A, manufactured by Advantest Co., Ltd.), placing the image carrier cleaning roller 1 horizontally, a thickness of 5 mm, a width of 30 mm, and In this state, a gold-plated plate having a length on which the entire image bearing member cleaning roller 1 can be placed is used as an electrode, and a load of 500 g is supported on both ends of the shaft member 2 of the image bearing member cleaning roller 1 (total It is possible to measure in accordance with a method in which a load of 1000 g) is applied, DC 100 V is applied between the shaft body 2 and the electrode, the value of the electric resistance meter after 1 second is read, and this value is used as the electric resistance value. it can. The electrical resistance value of the image bearing member cleaning roller 1 can be adjusted by the content of a conductivity-imparting agent (described later) contained in the foamed elastic layer 3.

  The shaft body 2 constituting the image bearing member cleaning roller 1 only needs to have good conductive characteristics, and is generally referred to as a so-called “core metal” made of iron, aluminum, stainless steel, brass, or the like. It is a shaft body. Further, the shaft body 2 may be a shaft body that is made conductive by plating an insulating core body such as a thermoplastic resin or a thermosetting resin. Furthermore, the shaft body 2 may be a thermoplastic resin or a thermosetting resin. The shaft body may be formed of a conductive resin in which carbon black or metal powder is blended as a conductivity imparting agent.

  The foamed elastic layer 3 constituting the image bearing member cleaning roller 1 is formed on the outer peripheral surface of the shaft body 2 as a foamed elastic layer having cells opened inside or on the outer peripheral surface thereof. In other words, the foamed elastic layer 3 has a structure having a skeleton formed three-dimensionally with rubber described later and a plurality of cells existing in the skeleton. When the foamed elastic layer 3 has cells, the Asker C hardness of the foamed elastic layer 3 can be lowered, and a sufficient nip width can be secured. Here, the cell included in the foamed elastic layer 3 refers to a hollow region generated by foaming or decomposition of a foaming agent contained in the foamed silicone rubber composition capable of forming the foamed elastic layer 3. Since the foamed elastic layer 3 satisfies the characteristics described later, a plurality of cells formed in the foamed elastic layer 3 are in a state in which the majority of the cells do not contact or communicate with other cells (independent cell state and The remaining cells may exist in a state of being connected to other cells (referred to as a connected cell state), and are usually an independent cell state and a connected cell state. And coexist. When a majority of the cells are in an independent cell state, the cells existing in the vicinity are not in communication with each other, so that foreign matter received from the image carrier does not enter the inside of the foamed elastic layer 3 and is developed. An increase in the hardness of the foamed elastic layer 3 due to the agent sticking in the foamed elastic layer 3 can be effectively suppressed.

  There are few cells that open to the outer peripheral surface and the end surface after forming the foamed elastic layer 3, but the outer peripheral surface is ground and polished as a finishing process of the foamed elastic layer 3 formed by foaming and curing a rubber composition to be described later. And / or a cutting process etc. will open the cell which exists in the outer peripheral surface vicinity of the foamed elastic layer 3 in the outer peripheral surface of the foamed elastic layer 3 after a process.

  The foamed elastic layer 3 has a cell (hereinafter sometimes referred to as an open cell) 3a that opens to the outer peripheral surface and a cell that exists inside the foamed elastic layer 3 and does not open to the outer peripheral surface (hereinafter referred to as an inner cell). 3b) exists.

  There are 3 to 20 open cells 3a in an area of 1.0 mm × 1.0 mm on the outer peripheral surface. If the number of open cells 3a is less than 3, there are few opportunities for the open cells 3a to come into contact with the foreign matter remaining on or attached to the image carrier, and the performance of mechanically removing the foreign matter may be inferior. When the number of open cells 3a exceeds 20, the cell walls existing between the open cells 3a become thin and the hardness of the foamed elastic layer 3 becomes lower than necessary, and the cell walls and the cells are destroyed. The cleaning performance and durability may be reduced. It is preferable that the number of open cells 3a is 6 to 12 in that the object of the present invention can be achieved well. The number of the open cells 3a is determined by observing the outer peripheral surface of the foamed elastic layer 3 with an electron microscope or the like and opening the open cells 3a arbitrarily extracted from the observation field of 1.0 mm × 1.0 mm. It can be determined by counting the number. Here, the number of open cells 3a is counted as one when the open cell 3a is an independent cell that is not connected to another adjacent cell, and the open cell 3a is connected to an adjacent cell. When the cell having the smaller opening area is joined or included in the cell having a larger opening area of 50% or more of the circumference, the cells are counted as one, and the opening cell 3a is adjacent to the cell. When the cell having the smaller opening area is joined or included in the cell having a larger opening area when the cell having the smaller opening area is joined to or included in the cell having a larger opening area, each cell is counted as one. When other cells are connected below the open cell 3a, that is, in the axial direction, the other cells are ignored and counted as one. In addition, the opening cell 3a partially opened in the extraction region is included in the opening cell 3a and counted as one, and the existence number is an arithmetic average value when a plurality of regions are extracted. In the foamed elastic layer 3, the number of open cells 3a can be adjusted by the amount of foaming agent added.

The open cells 3a are further present such that the total open area that opens to a total surface area of 1 mm ² in the region is 50 to 85% with respect to the total surface area of 1 mm ² . That is, the total opening area of the opening cell 3a is 0.5 to 0.85 mm ² . If the area ratio of the total opening area (hereinafter sometimes referred to as the total opening area ratio) is less than 50%, the number of cells for removing foreign matters remaining on or adhering to the image carrier is excessively decreased. The chance that the cell comes into contact with the foreign matter is reduced, and the cleaning characteristics may be deteriorated. On the other hand, when the total open area ratio exceeds 85%, the cell walls existing between the cells become thin and the hardness of the foamed elastic layer 3 becomes lower than necessary, and the cells existing in the vicinity of the outer peripheral surface in particular are easily destroyed. As a result, the cleaning performance and durability may be reduced. The total opening area ratio is preferably 55 to 75.5%, particularly preferably 60 to 70%, in that the object of the present invention can be satisfactorily achieved. The total opening area ratio is calculated by calculating the sum of the opening areas of the opening cells 3a existing in the extraction region extracted in the same manner as the number of existences, and the total opening area is calculated as 1 mm ² for the entire area of the observation region. It can be calculated by dividing. Here, when even a part of the opening cells 3a exist in the extraction area, the opening area in the extraction area is included in the opening area of the opening cell 3a, and the total opening area ratio is plural. It can also be an arithmetic average value when the region is extracted. In the foamed elastic layer 3, the total open area ratio of the open cells 3a can be adjusted by the amount of foaming agent added.

  The internal cell 3b existing in the foamed elastic layer 3 has an opening (hereinafter referred to as a cross-sectional opening) that opens in a cross-sectional area of 1.0 mm × 1.0 mm in a cross section when the foamed elastic layer 3 is cut along an arbitrary surface. Preferably have an average ellipticity of 0.85 or more. When the cross-sectional opening has an average ellipticity of 0.85 or more, the internal cell 3b is deformed almost uniformly, thereby dispersing the stress acting on the internal cell 3b and preventing the internal cell 3b from being broken. As a result, the foamed elastic layer 3 is prevented from being reduced in hardness due to the destruction of the internal cell 3b, and the image carrier cleaning roller 1 exhibits high cleaning performance and durability. The average ellipticity is particularly preferably 0.90 or more in terms of achieving both higher cleaning performance and higher durability. The upper limit of the average ellipticity is 1.0. Here, the average ellipticity is determined by observing a cut section obtained by cutting the foamed elastic layer 3 at an arbitrary surface with an electron microscope or the like, and arbitrarily extracting the extracted section area of 1.0 mm × 1.0 mm from the observation field. The diameter ratio (Rn / Rx) of the minimum opening diameter Rn to the maximum opening diameter Rx individually measured for all the cross-sectional openings of the internal cell 3b that is open to the inner cell 3b can be calculated, and these can be obtained by arithmetic averaging. Note that the maximum opening diameter Rx and the minimum opening diameter Rn of the cross-sectional opening may be extracted as the maximum diameter and the minimum diameter from the measurement of a large number of diameters in all circumferential directions of the cross-sectional opening. The maximum diameter and the minimum diameter may be extracted from a plurality of, for example, three kinds of diameters that can be measured as the opening diameter Rn.

  Here, each of the maximum opening diameter Rx and the minimum opening diameter Rn is measured as described above when the internal cell 3b is an independent cell not communicating with another adjacent cell, and the internal cell 3b is measured in the adjacent cell. If the cell with the smaller open area is connected or included in a cell with a larger open area when the cell having the smaller open area is joined or included, it is one cell. In the case where the internal cell 3b has a communication shape, the cell having the smaller opening area is joined or included in the cell having a larger opening area of less than 50% of the circumference. Sometimes these cells are regarded as independent cells and measured as described above. Note that the internal cell 3b partially opened in the extracted cross-sectional area is not included. In the foamed elastic layer 3, the average ellipticity of the internal cells 3b can be adjusted by the amount of foaming agent added.

  The inner cell 3b preferably has an average ratio (X / Y) of the circumferential direction diameter (X) and the surface direction diameter (Y) of the inner cell 3b of 0.85 to 1.10. If this average ratio is less than 0.85 or exceeds 1.10, the internal cell 3b is likely to be deformed and easily broken, and the hardness of the foamed elastic layer may be lowered and the cleaning performance may be lowered. The average ratio (X / Y) is particularly preferably 0.9 to 1.0 in that the cleaning performance is exhibited at a higher level. Here, the average ratio (X / Y) of the internal cells 3b is the average value of the ratio of the circumferential diameter (X) to the surface direction diameter (Y) of the internal cells 3b opening in an arbitrary cross section of the foamed elastic layer 3. 2, “surface direction diameter (Y)” is a radial direction from the center of the shaft body 2 toward the outer peripheral surface of the image bearing member cleaning roller 1, and is the center point of the cross-sectional opening of the internal cell 3 b. The opening diameter Y is on a straight line passing through C, and the “circumferential diameter (X)” is the opening diameter X on a straight line perpendicular to the “surface direction diameter (Y)”. Note that “the center point C of the opening” is the center when the opening is substantially circular, and is the intersection of the major axis and the minor axis when the opening is elliptical. For example, in the case of a communication shape described later, the maximum opening diameter Rx of a cell having a large opening area is divided into two equal parts. This average ratio (X / Y) is a 1.0 mm × 1.0 mm extracted section obtained by observing a cut section obtained by cutting the foamed elastic layer 3 at an arbitrary surface with an electron microscope or the like and arbitrarily extracting from the observation field. It can be obtained by calculating the ratio (X / Y) from the circumferential direction diameter (X) and the surface direction diameter (Y) individually measured for all the internal cells 3b opened in the region and arithmetically calculating these ratios (X / Y). .

  Here, each of the circumferential direction diameter (X) and the surface direction diameter (Y) is measured as described above when the internal cell 3b is an independent cell not communicating with another adjacent cell. In the case of a communication shape communicating with an adjacent cell, when a cell having a smaller opening area is joined or included in a cell having a larger opening area by 50% or more of its circumference, these are combined. It is assumed that one cell is measured as described above, and the inner cell 3b has a continuous shape, and a cell having a smaller opening area is bonded to a cell having a smaller opening area of less than 50% of the circumference. When it is included, these cells are regarded as independent cells and measured as described above. Note that the internal cell 3b partially opened in the extraction region is not included. In the foamed elastic layer 3, the average ratio (X / Y) of the internal cells 3b can be adjusted by the amount of foaming agent added. In the average ellipticity and the average ratio (X / Y), the cross section of the foamed elastic layer 3 is a cross section cut along a plane including the axis, but is a cross section cut along a plane perpendicular to the axis. It may be.

The average cell diameter of the cells (including the open cell 3a and the internal cell 3b) existing in the foamed elastic layer 3 is preferably 200 to 400 μm, and particularly preferably 200 to 300 μm. When the average cell diameter is within the above range, the image bearing member cleaning roller 1 is easy to mechanically remove foreign substances from the image bearing member when mounted on the cleaning device, and exhibits higher cleaning performance. The average cell diameter of the cell is determined by observing an area of about 20 mm ² with an electron microscope or the like on the cut surface or outer peripheral surface (in the case of the open cell 3a) when the foamed elastic layer 3 is cut on an arbitrary surface. The diameter of a circumscribed circle circumscribing the opening in each cell existing in the cell is measured, and the measured diameter can be obtained as an average diameter obtained by arithmetic averaging. Here, the opening of a cell is the opening of this cell when the cell is an independent cell that is not in communication with other adjacent cells, and the opening area of the cell is in the case of communication with the adjacent cell. When the cell with the smaller size is joined or included in a cell with a large opening area of 50% or more of its circumference, the openings of these cells are combined into one opening, and the cell communicates with an adjacent cell. In the case where a cell having a smaller opening area is joined or included in a cell having a larger opening area and less than 50% of its circumference, each of the openings of these cells is defined as one opening. To do. Note that an opening partly opened in the observation visual field is excluded from the measurement target. In the foamed elastic layer 3, the average cell diameter can be adjusted by the foaming agent contained in the foamed silicone rubber composition to be described later that forms the foamed elastic layer 3 or the curing conditions of the foamed silicone rubber composition.

The foamed elastic layer 3 has a relatively large specific gravity, for example, a specific gravity of 0.45 to 0.85 (g / cm ³ ), because the open cells 3a satisfy the number of existing cells and the total open area ratio. It preferably has, and particularly preferably has a specific gravity of 0.45 to 0.7 (g / cm ³ ). When the specific gravity of the foamed elastic layer 3 is within the above range, the effect of the present invention can be further enhanced. The specific gravity of the foamed elastic layer 3 can be measured by an electron density meter (in-water replacement method water temperature 23 ° C.). In the foamed elastic layer 3, the specific gravity can be adjusted by the number of cells present and the amount of raw material filler.

  Since the foamed elastic layer 3 has the open cells 3a satisfying the existence number and the total open area ratio, the foaming ratio is relatively small, for example, a foaming ratio of 105 to 150% is preferable. It is particularly preferable that the expansion ratio is%. When the expansion ratio of the foamed elastic layer 3 is within the above range, the number of existence and the total opening area ratio can be adjusted within the range, and the effects of the present invention can be further enhanced. By the way, when the expansion ratio of the foamed elastic layer 3 is small, generally the hardness of the foamed elastic layer 3 is high, but the foamed elastic layer 3 is a skeleton formed of rubber having a relatively low hardness of 25 to 45 (JIS A hardness). Therefore, an increase in the hardness of the foamed elastic layer 3 is suppressed, and an Asker C hardness of 30 to 50 ° suitable for the image bearing member cleaning roller 1 can be realized. The expansion ratio of the foamed elastic layer 3 can be calculated from the volume and mass of the foamed elastic layer 3 measured by a conventional method. The expansion ratio of the foamed elastic layer 3 can be adjusted by the foaming agent contained in the later-described foamed silicone rubber composition forming the foamed elastic layer 3 or the curing conditions of the foamed silicone rubber composition.

  Such a foamed elastic layer 3 preferably has such a hardness that the image bearing member cleaning roller 1 has an Asker C hardness within the above range. In this example, since the foamed elastic layer 3 is the outermost layer of the image bearing member cleaning roller 1, the foamed elastic layer 3 usually has the same Asker C hardness as the Asker C hardness of the image bearing member cleaning roller 1.

  The form of the foamed elastic layer 3 is not particularly limited. For example, as shown in FIG. 1, it may be a so-called straight shape adjusted to have a uniform outer diameter over the axial direction, and the outer diameter at the central portion is the outer diameter at both ends. It may be a so-called crown shape adjusted to be larger than the diameter, and may also be a so-called reverse crown shape adjusted so that the outer diameter at the center portion is smaller than the outer diameter at both ends thereof. . In this example, the foamed elastic layer 3 is formed in a straight shape.

  The thickness of the foamed elastic layer 3 is not particularly limited and can usually be adjusted to 2 to 20 mm.

  The foamed elastic layer 3 is a tubular body formed of a so-called “sponge-like” rubber having a porous structure having a large number of cells dispersed in an independent cell state on the outer peripheral surface of the shaft body 2. The rubber forming the skeleton has a JIS A hardness of preferably 25 to 50, particularly preferably 30 to 40. If the skeleton is formed of rubber having such hardness, the durability of the foamed elastic layer 3 will not be greatly reduced even if the entire foamed elastic layer 3 has a low hardness. The hardness of the rubber forming the porous structure of the foamed elastic layer 3 is a value when measured according to JIS K6253 using a test piece (size: φ29, thickness 12.5 mm) made of this rubber. .

  The rubber forming the foamed elastic layer 3 is not particularly limited, but is preferably various rubbers having the above-mentioned hardness. Specifically, silicone or silicone-modified rubber, nitrile rubber, ethylene propylene rubber (ethylene propylene diene rubber is used). And styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, fluorine rubber, and the like. Among these, silicone or silicone-modified rubber is preferable because it has low hardness and does not place an unnecessary load on the image carrier and developer. The foamed elastic layer 3 contains a conductivity-imparting agent described later in a skeleton formed of rubber.

  The foamed elastic layer 3 is formed of a foamed rubber composition, and specifically, is preferably formed by curing an addition reaction type conductive foamed silicone rubber composition.

  The addition reaction type conductive foamed silicone rubber composition includes a vinyl group-containing silicone raw rubber, a silica-based filler, a foaming agent, an addition reaction crosslinking agent, an addition reaction catalyst, a reaction control agent, and conductive carbon black. In addition, it preferably contains other conductive particles and, if desired, further contains an organic peroxide crosslinking agent, a heat resistance improver, and various additives.

  Of the addition reaction type conductive foamed silicone rubber composition, vinyl group-containing silicone raw rubber, silica-based filler, foaming agent, addition reaction crosslinking agent, addition reaction catalyst, reaction control agent, and if desired, further organic peroxide crosslinking As an addition reaction type foamed silicone rubber composition containing an agent, a heat resistance improver and various additives, for example, “addition reaction type foamed silicone rubber composition” described in JP-A-2008-076751 is used. Can be mentioned. The respective components are basically the same as the respective components in the “addition reaction type foamed silicone rubber composition” described in the publication. That is, the vinyl group-containing silicone raw rubber may be a silicone raw rubber containing a vinyl group in the molecule, and examples of the silica-based filler include fumed silica or precipitated silica, and examples of the foaming agent include an inorganic foaming agent or Examples include organic foaming agents, and addition reaction crosslinking agents include organohydrogenpolysiloxanes having two or more SiH groups (SiH bonds) in one molecule. Alternatively, a single metal belonging to Group 10 and a compound thereof can be used, and examples of the reaction control agent include methyl vinylcyclotetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, and hydroperoxide.

  The rubber contained in the foamed rubber composition is preferably a rubber having the above hardness, particularly a silicone rubber. The foamed rubber composition, particularly the addition reaction type conductive foamed silicone rubber composition, preferably has a low foaming agent content in that the foamed elastic layer 3 satisfies the existence number and the total open area ratio. Specifically, it is at most 3 parts by mass, preferably 0.8 to 2.2 parts by mass with respect to a total of 100 parts by mass of the vinyl group-containing silicone raw rubber and the silica filler.

  The foamed rubber composition, particularly the addition reaction type conductive foamed silicone rubber composition, preferably has a low silica filler content in that the entire foamed elastic layer 3 satisfies the above-mentioned hardness. The vinyl group-containing silicone raw rubber is at most 30 parts by mass, preferably 10 to 20 parts by mass, based on 100 parts by mass of the vinyl raw silicone rubber. Note that the hardness of the entire foamed elastic layer 3 can be lowered even if the amount of vinyl groups present in the vinyl group-containing silicone raw rubber is reduced.

  The image bearing member cleaning roller 1 according to the present invention can be manufactured by a manufacturing method including a step of foaming and curing a foamed rubber composition to form a foamed elastic layer. At this time, the foamed rubber composition has the number of foamed elastic layers 3 formed when foamed at a low foaming rate so as to achieve the foaming ratio in the above range, the total open area ratio, the average cell diameter, the specific gravity and the like within the above range. This is preferable because it can be adjusted.

  In order to manufacture the image bearing member cleaning roller 1, first, the shaft body 2 is prepared. The shaft body 2 is formed into a rod-like body having a uniform outer diameter along the axial direction as shown in FIG. The shaft body 2 may be plated on the outer peripheral surface thereof. For example, electroless plating, more specifically, electroless nickel plating and the like can be mentioned. These plating treatments can be performed by appropriate methods and conditions.

  Next, the prepared rubber composition, for example, the addition reaction type conductive foamed silicone rubber composition is disposed on the outer peripheral surface of the shaft body 2. The method is appropriately selected according to the foam rubber composition. For example, the shaft body 2 and the foam rubber composition are integrally extracted by an extruder or the like, and the foam rubber composition is applied to the outer peripheral surface of the shaft body 2. Examples thereof include a method of arranging, and a method of injecting a foamed rubber composition into a mold for housing the shaft body 2 and placing the foamed rubber composition on the outer peripheral surface of the shaft body 2. Among these, the method of integrally dispensing the shaft body 2 and the foamed rubber composition with an extruder or the like is preferable because the operation is easy and can be performed continuously.

  Thus, after arrange | positioning a foamed rubber composition to the outer peripheral surface of the shaft body 2, the process of foam-curing a foamed rubber composition and forming a foaming elastic layer is implemented. Specifically, the foamed rubber composition is heated together with the shaft body 2 while maintaining the state in which the foamed rubber composition is disposed on the outer peripheral surface of the shaft body 2. The foamed rubber composition is usually heated by a heating furnace such as an infrared heating furnace or a hot air furnace, a heating machine such as a dryer, etc., and rubber or resin contained in the foamed rubber composition, for example, a vinyl group-containing silicone raw rubber is crosslinked. In addition, it may be performed under conditions sufficient for the foaming agent to decompose or foam. For example, the addition reaction type conductive foamed silicone rubber composition is heated to about 170 to 500 ° C., particularly 200 to 400 ° C., and is heated for several minutes to 1 hour, particularly 5 to 30 minutes. Subsequent heating may be performed. The physical properties of the foamed elastic layer 3 are stabilized by the secondary heating. In the secondary heating, for example, the cured product of the addition reaction type conductive foamed silicone rubber composition cross-linked under the above conditions is further extruded, for example, 180 to 250 ° C., preferably 190 ° C. ˜230 ° C. for 1 to 24 hours, preferably 3 to 10 hours, or using a mold, for example, 130 to 200 ° C., preferably 150 to 180 ° C., 5 minutes to 24 hours, preferably It is performed by heating again for 10 minutes or more and 10 hours or less.

  Since the foamed elastic layer 3 formed in this way has a flat thin film formed on the outer peripheral surface thereof, a grinding process and a polishing process are performed in order to remove the thin film and form an open cell 3a that opens to the outer peripheral surface. A process and / or a cutting process is performed. In this finishing step, the size and shape of the foamed elastic layer 3 can be adjusted simultaneously in addition to the formation of the open cells 3a that open to the outer peripheral surface.

  In this manner, the image bearing member cleaning roller 1 can be manufactured.

  In the cleaning roller for an image carrier according to the present invention, since the opening cell 3a satisfies the number of existence and the total opening area ratio, the cell wall is inevitably thick and the cell wall and the cell are not easily destroyed. When mounted on the forming apparatus, the cleaning performance for the image carrier can be maintained for a long period of time. As described above, the image bearing member cleaning roller according to the present invention can greatly contribute to the image forming apparatus forming a high-quality image over a long period of time. Therefore, the image bearing member cleaning roller according to the present invention is suitable, for example, as a photosensitive drum cleaning roller of a high-speed image forming apparatus.

  The image bearing member cleaning roller according to the present invention is not limited to the above-described example, and various modifications can be made within a range in which the object of the present invention can be achieved. For example, the foamed elastic layer 3 of the image bearing member cleaning roller 1 has a single layer structure, but in the present invention, the foamed elastic layer may have a multilayer structure of two or more layers.

  Next, an image forming apparatus 30 which is an example of an image forming apparatus (hereinafter also referred to as an image forming apparatus according to the present invention) provided with the image bearing member cleaning roller according to the present invention will be described with reference to the drawings. And explain.

  As shown in FIG. 3, the image forming apparatus 30 includes a rotatable image carrier 31 on which an electrostatic latent image is formed, such as a photosensitive member, and a charging unit 32, for example, disposed around the image carrier 31. A charging roller, an exposure unit 33, a developing unit 40, a transfer unit 34 such as a transfer roller and a cleaning unit 37, and a fixing unit 35 such as a fixing device for an image forming apparatus are provided on the downstream side in the conveyance direction of the recording medium. The image forming apparatus 30 is provided with an image carrier cleaning roller 1 as a cleaning unit 37. The developing means 40 is formed basically in the same manner as the conventional developing means. Specifically, as shown in FIG. 3, the developing unit 41 and the development for supplying the developer 42 to the image carrier 31. A developer carrier 44, a developer supply unit 43 that supplies the developer 42 to the developer carrier 44, and a developer regulating member 45 that charges the developer 42 are provided. As long as the developer 42 is a one-component developer, the developer 42 may be a dry developer or a wet developer, and may be a non-magnetic developer or a magnetic developer.

  The fixing unit 35 is only required to fix the developer 42 (electrostatic latent image) transferred to the recording body 36. For example, a heat roller fixing device having a heat generating fixing roller, an oven fixing device, etc. A heat fixing device, a pressure fixing device including a fixing roller capable of pressing, and the like can be used. These fixing devices may be fixing devices having endless belts. As shown in FIG. 3, the fixing device 35 has a fixing roller 53 and an endless belt supported in the vicinity of the fixing roller 53 in a housing 50 having an opening 52 through which the recording medium 36 passes. A roller 54, an endless belt 55 wound around the fixing roller 53 and the endless belt support roller 54, and a pressure roller 56 disposed opposite to the fixing roller 53. The pressure heat fixing device is rotatably supported so that the pressure roller 56 is in contact with or in pressure contact with each other. The fixing roller 53, the endless belt support roller 54, and the pressure roller 56 each have a built-in heating body (not shown), and the pressure roller 56 is interposed via the endless belt 55 by a biasing means (not shown) such as a spring. In contact with the fixing roller 53. By passing the recording medium 36 between the endless belt 55 and the pressure roller 56, the recording medium 36 is heated simultaneously with the pressurization, and the developer 42 (electrostatic latent image) transferred to the recording medium 36 is fixed. be able to.

  The image forming apparatus 30 according to the present invention operates as follows. First, in the image forming apparatus 30, the image carrier 31 is uniformly charged by the charging unit 32, and an electrostatic latent image is formed on the surface of the image carrier 31 by the exposure unit 33. Next, the developer 42 is supplied from the developing means 40 to the image carrier 31 to develop the electrostatic latent image. Next, the developer image is transferred onto a recording body 36 conveyed between the image carrier 31 and the transfer means 34. The recording body 36 is conveyed to the fixing unit 35, and the developer image is fixed on the recording body 36 as a permanent image. In this way, an image can be formed on the recording body 36. On the other hand, the image carrier 31 after the developer image has been transferred is removed by the image carrier cleaning roller 1 disposed on the upstream side of the charging means 32 to remove the developer adhering to or remaining on the outer peripheral surface. At this time, the image carrier cleaning roller 1 as the cleaning means exhibits a high level of cleaning performance for the image carrier 31 as described above. Therefore, the developer and foreign matter are not attached to the surface of the image carrier 31 that has passed through the pressure contact portion with the image carrier cleaning roller 1, and a desired developer image is formed. A high quality image, for example, an image without an afterimage of the previous image can be formed.

  The image forming apparatus according to the present invention is not limited to the above-described example, and various modifications can be made as long as the object of the present invention can be achieved. For example, various image forming apparatuses can be used as the image forming apparatus, and an image forming apparatus that can form an image at high speed is preferable.

  The image forming apparatus 30 is an electrophotographic image forming apparatus. However, in the present invention, the image forming apparatus is not limited to the electrophotographic system, and may be, for example, an electrostatic image forming apparatus. Good. Further, the image forming apparatus 30 is a monochrome image forming apparatus in which the developing unit 40 contains only a single color developer 42. However, in this invention, the image forming apparatus is not limited to a monochrome image forming apparatus. It may be an image forming apparatus. Examples of the color image forming apparatus include a four-cycle color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier to an intermediate transfer body, and a plurality of image carriers provided with developing means for each color. Examples thereof include a tandem type color image forming apparatus in which a body is arranged in series on an intermediate transfer body or a transfer conveyance belt. The image forming apparatus 30 is an image forming apparatus such as a copying machine, a facsimile machine, or a printer.

  In the image forming apparatus 30, a one-component developer is advantageously used as the developer 42, but a two-component developer including a toner and a carrier such as iron or nickel can also be used. .

(Example 1)
A shaft body (diameter 5 mm × length 250 mm, SUM22) subjected to electroless nickel plating was washed with toluene, and a primer “No. 101A / B” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name) was applied. The primer-treated shaft body was baked at a temperature of 180 ° C. for 30 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer.

  Next, 50 parts by mass of a silicone rubber composition “KE-904FU” (manufactured by Shin-Etsu Chemical Co., Ltd.) containing a vinyl group-containing silicone raw rubber and a silica-based filler, and a vinyl group-containing silicone raw rubber “KE-77VBS” (Shin-Etsu Chemical) Industrial Co., Ltd.) 50 parts by mass, conductivity imparting material “KE-87C40PU” (Shin-Etsu Chemical Co., Ltd.) 65 parts by mass, and organic foaming agent “azobis-isobutyronitrile” (“AIBN” in Table 1) 2.0 parts by mass, addition reaction crosslinking agent “C-153A” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name), 3.5 parts by mass, an appropriate amount of platinum catalyst as an addition reaction catalyst, Reaction control agent “R-153A” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name) 1.0 part by mass and organic peroxide crosslinking agent “C-3” (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name) 5.0 mass And sufficiently kneaded by a twin roll to prepare an addition reaction-type conductive foamed silicone rubber composition. The JIS A hardness of the test piece prepared with this addition reaction type conductive foamed silicone rubber composition was 40.

  Subsequently, the shaft body 2 on which the primer layer is formed and the prepared addition reaction type conductive foamed silicone rubber composition are integrally extracted by an extrusion molding machine, and the addition reaction type conductive foaming is performed using an infrared heating furnace (IR furnace). The silicone rubber composition was heated at 250 ° C. for 10 minutes to foam-crosslink the addition reaction type conductive foamed silicone rubber composition. Thereafter, the addition reaction type conductive foamed silicone rubber composition after foaming and crosslinking is further heated at 200 ° C. for 7 hours using a gear oven, and left at room temperature for 1 hour or more. The foamed elastic layer 3 having an open cell 3a and an internal cell 3b that were ground to an outer diameter of 11 mm and opened on the outer peripheral surface was formed. The Asker C hardness of this foamed elastic layer 3 is shown in Table 1. In this way, the image bearing member cleaning roller of Example 1 was manufactured.

(Examples 2 to 5)
Silicone rubber composition “KE-904FU”, vinyl group-containing silicone raw rubber “KE-77VBS” and / or organic foaming agent “azobis-isobutyronitrile (AIBN)” in the addition reaction type conductive foamed silicone rubber composition Each image bearing member cleaning roller was manufactured basically in the same manner as in Example 1 except that the blending amount was changed to the blending amount shown in Table 1. Table 1 shows the Asker C hardness of the foamed elastic layer 3 in each of the image bearing member cleaning rollers thus manufactured. Table 1 shows the measured JIS A hardness of test pieces made of each addition reaction type conductive foamed silicone rubber composition having the same amount as in Examples 2 to 5.

(Comparative Examples 1-4)
Compounding amount of silicone rubber composition “KE-904FU”, vinyl group-containing silicone raw rubber “KE-77VBS” and / or organic foaming agent “azobis-isobutyronitrile” in the addition reaction type conductive foamed silicone rubber composition Each image bearing member cleaning roller was manufactured in the same manner as in Example 1 except that the blending amount was changed to the amount shown in Table 1. Table 1 shows the Asker C hardness of the foamed elastic layer 3 in each of the image bearing member cleaning rollers thus manufactured. Table 1 shows the measured JIS A hardness of test pieces made of each addition reaction type conductive foamed silicone rubber composition having the same blending amount as in Comparative Examples 1 to 4.

(Characteristic evaluation of foamed elastic layer)
In the foamed elastic layer of each image carrier cleaning roller manufactured as described above, the number of open cells 3a (number) (represented as “the number of cells” in Table 1) and the total of open cells 3a. Opening area ratio (%) (represented as “total opening area ratio” in Table 1), average ellipticity, average ratio (circumferential diameter X / surface direction diameter Y) (in Table 1, “average ratio (X / Y) ”), average cell diameter (μm) and specific gravity (g / cm ³ ) were measured based on the above method. The results are shown in Table 1. In addition, when the foamed elastic layer of each image carrier cleaning roller in Examples 1 to 5 and Comparative Examples 1 to 4 was observed, a majority of the cells in any of the image carrier cleaning rollers were in an independent cell state.

(Durability test)
The durability of each image carrier cleaning roller was evaluated using the cleaning roller for each image carrier manufactured in Examples and Comparative Examples and the durability test apparatus 70 described in FIG. Specifically, the durability test apparatus 70 is opposed to the metal shaft 71 and the metal shaft 71 (outer diameter 16 mm, length 300 mm, made of stainless steel (SUS304)) fixed to the lower surface inside the housing. Are provided with a test roller mounting portion 74 provided on the upper surface inside the casing so as to be movable up and down, and a pressing force adjusting means 75 capable of moving the test roller mounting portion 74 up and down, for example, a pressure adjusting micrometer.

  Each manufactured image bearing member cleaning roller is mounted on the bearing of the test roller mounting portion 74, and the test roller 76 mounted by operating the pressing force adjusting means 75 as shown in FIG. Was pressed against the metal shaft 71 so as to be 1 mm. Subsequently, it was rotationally driven for 12 hours by the drive means (not shown) with which the test roller mounting part 74 was equipped at the rotational speed of 900 rpm. The Asker C hardness of each image carrier cleaning roller before this durability test and the Asker C hardness of each image carrier cleaning roller after this durability test were measured, and the amount of decrease was calculated. The Asker C hardness is measured at three locations in the axial direction and at four locations in the circumferential direction. Specifically, the three locations in the axial direction are 30 mm from the both ends of the foamed elastic body toward the center and the axial direction. The central part of each of the four parts in the circumferential direction was four places at equal intervals in the circumferential direction where the central angle was 90 ° in each of the three parts in the axial direction. The evaluation is “「 ”when the arithmetic average decrease in the decrease in Asker C hardness at each measurement point is 0 or more and less than 1.0, and“ ◯ ”when the calculation is 1.0 or more and less than 2.5. The case of 2.5 or more was taken as “x”. The evaluation results and the arithmetic average decrease amount of Asker C hardness (indicated as “hardness decrease amount” in Table 1) are shown in Table 1.

(Cleaning performance)
Each image carrier cleaning roller after the durability test is mounted on an image forming apparatus (trade name “HL-4040CL”, manufactured by Brother Industries, Ltd.) as an image carrier cleaning roller, and each image carrier cleaning roller is mounted. The cleaning performance of was evaluated. Specifically, one black solid image is printed on the entire surface of the A4 paper (JIS), and then one white solid image is printed on the entire surface of the A4 paper (JIS), and adheres to the surface of the photoconductor as the image carrier. The remaining amount of the developing developer was visually confirmed. The evaluation was “◎” when the black developer could not be confirmed on the surface of the photoconductor, and “○” when the very small amount of black developer was partially confirmed on the surface of the photoconductor. “×” means that the black developer was clearly confirmed on the surface of the photoreceptor. The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Cleaning roller for image carriers 2 Shaft body 3 Elastic foam layer 3a Open cell 3b Internal cell 30 Image forming apparatus 31 Image carrier 32 Charging means 33 Exposure means 34 Transfer means 35 Fixing means 36 Transfer object 37 Cleaning means (image carrier) Body cleaning roller)
40 Developing means 41 Developer storing section 42 Developer 43 Developer supplying means 44 Developer carrier 45 Developer regulating member 50 Housing 52 Opening 53 Fixing roller 54 Endless belt support roller 55 Endless belt 56 Pressure roller 70 Durability test Device 71 Metal shaft 74 Test roller mounting portion 75 Pressure adjusting means 76 Test roller

Claims (5)

An image carrier cleaning roller comprising a foamed elastic layer having a plurality of cells,
Among the cells, there are 3 to 20 cells that open to the outer peripheral surface of the foamed elastic layer in a 1.0 mm × 1.0 mm region of the outer peripheral surface, and the region with respect to the surface area of 1 mm ² of the region. total opening area 50% to 85% der which opens is,
Among the cells of the foamed elastic layer, cells that do not open to the outer peripheral surface have an average opening of 1.05 × 1.0 mm in a cross-sectional area of an arbitrary cross section of the foamed elastic layer of 0.85 or more. The ellipticity has an average ratio of 0.85 to 1.10 (circumferential direction diameter X / surface direction diameter Y),
The image bearing member cleaning roller according to claim 1, wherein an average cell diameter of cells in the foamed elastic layer is 200 to 400 μm . 2. The image bearing member cleaning roller according to claim 1 , wherein the foamed elastic layer has a skeleton formed of rubber having a JIS A hardness of 25 to 45. 3. The foamed elastic layer is an image carrier cleaning roller according to claim 1 or 2 wherein the Asker C is 30 to 50 °. The foamed elastic layer is an image carrier cleaning roller according to any one of claims 1 to 3, characterized in that mainly has an independent cell state. An image carrier that holds a latent image, and an image carrier cleaning roller according to any one of claims 1 to 4 disposed so as to be in contact with the image carrier. Image forming apparatus.

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