Conductive roller, method for producing conductive roller, transfer device, process cartridge, and image forming device

Abstract

The present invention provides a conductive roller, a method for manufacturing a conductive roller, a transfer device, a processing box and an image forming device. The conductive roller includes a supporting component and a conductive foamed elastic layer arranged on the above-mentioned supporting component. In a spectrum of period (μm) and amplitude (μm) obtained by fast Fourier transforming the axial concave-convex waveform of the outer peripheral surface of the above-mentioned conductive foamed elastic layer, the integral value St of the amplitude in the range of period greater than 100 μm and less than 300 μm is less than 455 μm.

Description

Technical Field

[0001] The present application relates to a conductive roller, a method for manufacturing the conductive roller, a transfer device, a process cartridge, and an image forming apparatus. Background Art

[0002] Japanese Patent Gazette No. 2959445 discloses a developing roller having small, burr-like depressions and projections that are inclined in the circumferential direction, the height of the depressions and projections being 0.1 to 30 μm, the average spacing between the projections along the circumferential direction being 1 to 200 μm, and the depressions and projections forming wavy stripes along the axial direction on the roller surface, the JIS 10-point average roughness Rz of the roller surface along the circumferential direction being 5 to 20 μm, the JIS 10-point average roughness Rz along the axial direction being 3 to 15 μm, and the average roughness Rz along the circumferential direction being greater than the average roughness Rz along the axial direction.

[0003] Japanese Patent No. 6364333 discloses a developer supply roller, the surface of which is a polymer foam material including an ether-based polyurethane foam, and the surface roughness of the surface is 40 μm or more and 140 μm or less. Here, the surface roughness is set to a measurement length of 40 mm, a measurement interval of 1 mm, and a measurement point number of 40 points, and is the standard deviation of the displacement of all the measurement points from the reference line. Summary of the invention

[0004] The present application aims to provide a conductive roller, wherein the outermost layer is a conductive foamed elastic layer, and in a spectrum of period (μm) and amplitude (μm) obtained by fast Fourier transforming the uneven waveform of the axial direction of the outer peripheral surface of the conductive foamed elastic layer, the integral value St of the amplitude in the range of period of 100 μm to 300 μm exceeds 455 μm or the amplitude A of the period of 300 μm is greater than 455 μm. 300 Compared with a conductive roller having a thickness exceeding 3.6 μm, abnormal discharge is less likely to occur between the conductive roller and the opposing member when voltage is applied.

[0005] According to the first scheme of the present application, a conductive roller is provided, which comprises a supporting component and a conductive foamed elastic layer arranged on the above-mentioned supporting component. In a spectrum of period (μm) and amplitude (μm) obtained by fast Fourier transforming the axial concave-convex waveform of the outer peripheral surface of the above-mentioned conductive foamed elastic layer, the integrated value St of the amplitude in the range of period greater than 100 μm and less than 300 μm is less than 455 μm.

[0006] According to the second aspect of the present application, the integrated value St is 410 μm or less.

[0007] According to the third embodiment of the present application, a conductive foam elastic layer is provided on the supporting member, and in a spectrum of period (μm) and amplitude (μm) obtained by fast Fourier transforming the axial concave-convex waveform of the outer peripheral surface of the conductive foam elastic layer, the amplitude A of the period 300 μm is 0.1 μm. 300 It is less than 3.6μm.

[0008] According to the fourth aspect of the present application, the amplitude A 300 It is less than 3.0μm.

[0009] According to the fifth embodiment of the present application, in the spectrum of period (μm) and amplitude (μm) obtained by fast Fourier transforming the axial concavo-convex waveform of the outer peripheral surface of the conductive foamed elastic layer, the amplitude A of the period 300 μm is 300 With period 100μm and amplitude A 100 Ratio A 300 / A 100 It is 1 to 3.

[0010] According to the sixth embodiment of the present application, the above ratio A 300 / A 100 It is above 1 and below 2.5.

[0011] According to a seventh aspect of the present application, there is provided a method for manufacturing the conductive roller, comprising: polishing the outer peripheral surface of a conductive foamed elastic layer disposed on a support member; and bringing the polished outer peripheral surface of the conductive foamed elastic layer into rotational contact with a heating roller.

[0012] According to an eighth aspect of the present application, there is provided a transfer device including the above-mentioned conductive roller.

[0013] According to a ninth aspect of the present application, there is provided a process cartridge including an image holding member and the transfer device, the process cartridge being attachable to and detachable from an image forming apparatus.

[0014] According to the tenth scheme of the present application, an image forming device is provided, which comprises: an image retaining body; a charging unit, which charges the surface of the above-mentioned image retaining body; an electrostatic image forming unit, which forms an electrostatic image on the surface of the charged above-mentioned image retaining body; a developing unit, which develops the electrostatic image formed on the surface of the above-mentioned image retaining body using a developer containing a toner to form a toner image; and a transfer unit, which comprises the above-mentioned conductive roller and transfers the above-mentioned toner image to the surface of a recording medium.

[0015] Effects of the Invention

[0016] According to the first aspect, compared with a conductive roller having a conductive foamed elastic layer as the outermost layer and an integrated value St exceeding 455 μm, a conductive roller can be provided in which abnormal discharge is less likely to occur between the conductive roller and the opposing member when voltage is applied.

[0017] According to the second aspect, compared with a conductive roller having a conductive foamed elastic layer as the outermost layer and an integrated value St exceeding 410 μm, a conductive roller can be provided in which abnormal discharge is less likely to occur between the conductive roller and the opposing member when voltage is applied.

[0018] According to the third embodiment, the outermost layer is a conductive foam elastic layer, the amplitude A 300 Compared with a conductive roller having a thickness exceeding 3.6 μm, a conductive roller in which abnormal discharge is less likely to occur between the conductive roller and the opposing member when a voltage is applied can be provided.

[0019] According to the fourth embodiment, the outermost layer is a conductive foam elastic layer, the amplitude A 300 Compared with a conductive roller having a thickness exceeding 3.0 μm, a conductive roller in which abnormal discharge is less likely to occur between the conductive roller and the opposing member when a voltage is applied can be provided.

[0020] According to the fifth embodiment, the outermost layer is a conductive foam elastic layer, the ratio A 300 / A 100 Compared with a conductive roller having a ratio greater than 3, a conductive roller in which abnormal discharge is less likely to occur between the conductive roller and the opposing member when a voltage is applied can be provided.

[0021] According to the sixth embodiment, the outermost layer is a conductive foam elastic layer, the ratio A 300 / A 100 When the ratio exceeds 2.5, it is possible to provide a conductive roller in which abnormal discharge is less likely to occur between the conductive roller and the opposing member when a voltage is applied.

[0022] According to the seventh aspect, compared with the case where the outer peripheral surface of the polished conductive foamed elastic layer is not brought into rotational contact with the heating roller, a method for manufacturing a conductive roller in which abnormal discharge is less likely to occur between the conductive roller and the opposing member when voltage is applied can be provided.

[0023] According to the eighth aspect, when the outermost layer of the conductive roller is a conductive foamed elastic layer and the integral value St exceeds 455 μm or the amplitude A 300 When the diameter exceeds 3.6 μm, a transfer device can be provided in which abnormal discharge is less likely to occur between the transfer device and the opposing member when a voltage is applied.

[0024] According to the ninth aspect, when the outermost layer of the conductive roller is a conductive foamed elastic layer and the integral value St exceeds 455 μm or the amplitude A 300When the thickness exceeds 3.6 μm, a process cartridge can be provided in which abnormal discharge is less likely to occur between the opposing member when a voltage is applied.

[0025] According to the tenth aspect, when the outermost layer of the conductive roller is a conductive foamed elastic layer and the integral value St exceeds 455 μm or the amplitude A 300 When the thickness exceeds 3.6 μm, an image forming apparatus can be provided in which abnormal discharge is less likely to occur between the opposing member when a voltage is applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic perspective view showing an example of the conductive roller according to the present embodiment.

[0027] Figure 2 is a schematic cross-sectional view showing an example of the conductive roller of this embodiment. Figure 1 AA cross-section diagram.

[0028] Figure 3 This is an example of the uneven waveform of the outer peripheral surface of the conductive foamed elastic layer included in the conductive roller of the present embodiment.

[0029] Figure 4 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0030] Figure 5 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0031] The following describes embodiments of the present application. These descriptions and examples illustrate the embodiments and do not limit the scope of the embodiments.

[0032] In the present application, a numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0033] In the present application, in the numerical range of staged recording, the upper limit or lower limit recorded in a numerical range can be replaced by the upper limit or lower limit of the numerical range of other staged recordings. In addition, in the numerical range of recording in the present application, the upper limit or lower limit of its numerical range can be replaced by the value shown in the embodiment.

[0034] In the present application, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0035] In the present application, when the embodiments are described with reference to the drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. In addition, the dimensions of the components in each figure are schematic dimensions, and the relative relationship between the dimensions of the components is not limited thereto.

[0036] In the present application, each component may include two or more corresponding substances. In the present application, when referring to the amount of each component in the composition, when there are two or more substances that meet the requirements of each component in the composition, unless otherwise stated, it refers to the total amount of the two or more substances present in the composition.

[0037] In the present application, particles that meet the requirements of each component may include two or more types. When two or more types of particles that meet the requirements of each component are present in the composition, the particle size of each component refers to the value of the mixture of the two or more types of particles present in the composition unless otherwise specified.

[0038] <Conductive Roller>

[0039] The conductive roller of this embodiment is suitably used for a transfer roller, a developing roller, a charging roller, an image holding member cleaning roller, etc. of an electrophotographic image forming apparatus. However, the use of the conductive roller of this embodiment is not limited to the above use.

[0040] The conductive roller according to the present embodiment will be described with reference to the drawings.

[0041] Figure 1 This is a schematic perspective view showing an example of the conductive roller according to the present embodiment. Figure 2 yes Figure 1 The AA cross-section diagram is Figure 1 The conductive roller shown in the figure is a cross-sectional view cut along the radial direction.

[0042] like Figure 1 and Figure 2 As shown, the conductive roller 111 is a roller member including a hollow or non-hollow cylindrical support member 112 and a conductive foamed elastic layer 113 disposed on the outer peripheral surface of the support member 112. The conductive foamed elastic layer 113 is the outermost layer of the conductive roller 111.

[0043] The conductive roller of this embodiment is not limited to Figure 1 and Figure 2 The structure shown may include an intermediate layer between the supporting member 112 and the conductive foam elastic layer 113 , for example.

[0044] Figure 3 This is an example of the uneven waveform of the outer peripheral surface of the conductive foamed elastic layer 113 .

[0045] Figure 3 (a) is a photograph of the outline of the outer peripheral surface of the conductive foamed elastic layer 113. Figure 3 The photograph (a) was taken from the side perpendicular to the axial direction of the conductive roller 111 and from the height of the outer peripheral surface contour under imaging conditions with an imaging resolution of 2 μm or less per pixel using an optical microscope (eg, KEYENCE VHX-5000).

[0046] Figure 3 (b) is based on Figure 3 (a) The photo depicts the concave and convex waveform. Figure 3 The concave-convex waveform (b) is taken in an interval of 1 mm in length along the axial direction, and a two-dimensional discrete Fourier transform (2D-DFT) is performed using fast Fourier transform (FFT) to obtain a spectrum of period (μm) and amplitude (μm).

[0047] Figure 3 (c) Yes Figure 3 (b) is the spectrum obtained by performing FFT on the concave and convex waveform. Figure 3 In the spectrum of (c), the horizontal axis is the period, the vertical axis is the amplitude, and the scale of the horizontal axis is represented by common logarithm.

[0048] From the calculation results of FFT, the integral value (μm) of the amplitude (μm) in the range of period 100 μm to 300 μm is obtained. The integral value is the sum of the amplitude (μm) of each discretized 1 μm. The integral value is obtained at least 20 locations (for example, 5 locations in the axial direction and 4 locations in the circumferential direction (every 90°)), and the average value of at least 20 locations is calculated, and the average value is used as the integral value St.

[0049] Depend on Figure 3 In the spectrum of (c), the amplitude of the period of 300 μm and the amplitude of the period of 100 μm are obtained. Similarly, the amplitude of the period of 300 μm and the amplitude of the period of 100 μm are obtained at least 20 locations, and the average value of the at least 20 locations is calculated, and the average value is taken as the amplitude A of the period of 300 μm. 300 and an amplitude A with a period of 100 μm 100 .

[0050] When a voltage is applied to the conductive roller 111 mounted on an image forming device of an electrophotographic method during image formation, abnormal discharge may sometimes occur between the conductive roller 111 and the opposing member of the roller. For example, when the conductive roller 111 is a transfer roller, the toner on the opposing member may be reversely charged due to abnormal discharge, resulting in poor transfer of the toner or scattering of the toner, and sometimes uneven density of the image. In contrast, when the integral value St of the conductive foamed elastic layer 113 of the conductive roller 111 is less than 455 μm, it is difficult to generate abnormal discharge between the conductive roller 111 and the opposing member when a voltage is applied. The mechanism is speculated as follows.

[0051] The outer peripheral surface of the conductive foamed elastic layer 113, which is the outermost layer of the conductive roller 111, is generally subjected to grinding, and the contour of the outer peripheral surface of the conductive foamed elastic layer 113 forms a complex concavoconvex waveform. It is estimated that the concavoconvex waveform is mixed with various periodic concavoconvex components such as concavoconvex components derived from grinding, concavoconvex components derived from foamed cells of the conductive foamed elastic layer 113, and concavoconvex components derived from particles dispersed in the conductive foamed elastic layer 113.

[0052] The applicant has studied the above-mentioned concavo-convex waveform by fast Fourier transform, and found that by suppressing the amplitude of the concavo-convex component in the range of 100 μm to 300 μm, the abnormal discharge between the conductive roller 111 and the opposing member of the roller can be suppressed. It is speculated that the electric field is easily concentrated on the convex part with a period of 100 μm to 300 μm, and the convex part becomes the starting point of discharge, causing abnormal discharge between the opposing member.

[0053] The present applicant has conducted further research and found that if the integral value St of the conductive foamed elastic layer 113 is 455 μm or less, abnormal discharge is less likely to occur between the conductive roller 111 and the opposing member of the roller. For example, when the conductive roller 111 is a transfer roller, if the integral value St is 455 μm or less, the occurrence of uneven image density is suppressed.

[0054] From the perspective of suppressing abnormal discharge between the conductive roller 111 and the opposing member of the roller, the smaller the integrated value St, the better, more preferably 410 μm or less, further preferably 380 μm or less, further preferably 350 μm or less, further preferably 320 μm or less.

[0055] However, it is difficult to completely eliminate the uneven components of several hundred micrometers on the outer peripheral surface of the conductive foamed elastic layer 113 where the foamed cells exist, so the lower limit of the integral value St is, for example, 100 μm or more, 150 μm or more, or 200 μm or more.

[0056] Integrated value St and amplitude A with a period of 300 μm300 The correlation is strong. With amplitude A 300 The larger the value, the larger the integral value St. The amplitude A of the period 300 μm 300 It is preferably 3.6 μm or less, more preferably 3.0 μm or less, further preferably 2.5 μm or less, and further preferably 2.0 μm or less. Amplitude A with a period of 300 μm 300 The lower limit of is not particularly limited, and is, for example, 1.5 μm or more.

[0057] In order to suppress abnormal discharge between the conductive roller 111 and the member facing the roller, the amplitude A of the period 300 μm is 300 and an amplitude A with a period of 100 μm 100 It is preferable to have the following characteristics.

[0058] Amplitude A with a period of 300 μm 300 With period 100μm and amplitude A 100 Preferably, 1≤A 300 / A 100 ≤3, preferably 1≤A 300 / A 100 ≤2.5, and preferably 1≤A 300 / A 100 The relationship is ≤2.

[0059] Amplitude A with a period of 100 μm 100 It is preferably 2 μm or less, more preferably 1.5 μm or less, and even more preferably 1.2 μm or less. The amplitude A of the period 100 μm 100 The lower limit of is not particularly limited, and is, for example, 0.8 μm or more.

[0060] Hereinafter, the materials and the like of each layer constituting the conductive roller according to the present embodiment will be described.

[0061] [Supporting parts]

[0062] The supporting member functions as a supporting member when mounted on the conductive roller image forming apparatus and functions as an electrode when performing image formation. The supporting member may be a hollow member or a solid member.

[0063] The supporting component is a conductive component, for example: metal components such as iron (free-cutting steel, etc.), copper, brass, stainless steel, aluminum, nickel, etc.; resin components or ceramic components whose outer surfaces are plated; resin components or ceramic components containing a conductive agent.

[0064] [Conductive foamed elastic layer]

[0065] The conductive foamed elastic layer is a foamed body containing a rubber material (elastic material), and may contain a conductive agent or other additives.

[0066] Examples of rubber materials (elastic materials) include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluororubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer rubber, ethylene propylene rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and the like, as well as rubbers obtained by mixing these.

[0067] Examples of the foaming agent for making the elastic layer foamable include: water; azo compounds such as azodicarbonamide, azobisisobutyronitrile, and diazoaminobenzene; benzenesulfonyl hydrazides such as benzenesulfonyl hydrazide, 4,4'-oxybisbenzenesulfonyl hydrazide, and toluenesulfonyl hydrazide; bicarbonates such as sodium bicarbonate that generate carbon dioxide by thermal decomposition; and NaNO that generates nitrogen. 2 With NH 4 Cl mixture; oxygen-generating peroxide; etc. If necessary, a foaming aid, a foaming agent, a catalyst, etc. may also be used.

[0068] When the conductivity of the rubber material is low or the rubber material has no conductivity, a conductive agent is used. Examples of the conductive agent include an electron conductive agent and an ion conductive agent.

[0069] Examples of the electronic conductive agent include carbon black such as Ketjen black and acetylene black; pyrolytic carbon and graphite; metals or alloys such as aluminum, copper, nickel, and stainless steel; conductive metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, and tin oxide-indium oxide solid solution; and powders such as those obtained by conducting the surface of insulating materials. The electronic conductive agent may be used alone or in combination of two or more.

[0070] Among them, the electronic conductive agent is preferably carbon black, and the average primary particle size of the electronic conductive agent is preferably 10 nm to 150 nm, more preferably 20 nm to 100 nm, and further preferably 30 nm to 80 nm.

[0071] The content of carbon black is preferably 1 part by mass or more and 60 parts by mass or less, and more preferably 10 parts by mass or more and 40 parts by mass or less, based on 100 parts by mass of the rubber material.

[0072] Examples of ion conductive agents include quaternary ammonium salts (e.g., perchlorates, chlorates, fluoroborates, sulfates, ethylsulfates, benzyl bromides or benzyl chlorides of lauryl trimethyl ammonium, stearyl trimethyl ammonium, octadecyl trimethyl ammonium, dodecyl trimethyl ammonium, hexadecyl trimethyl ammonium or modified fatty acid·dimethyl ethyl ammonium), aliphatic sulfonates, higher alcohol sulfates, higher alcohol ethylene oxide addition sulfates, higher alcohol phosphates, higher alcohol ethylene oxide addition phosphates, betaines, higher alcohol ethylene oxide, polyethylene glycol fatty acid esters, polyol fatty acid esters, etc. The ion conductive agents may be used alone or in combination of two or more.

[0073] The content of the ion conductive agent is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.5 parts by mass or more and 3.0 parts by mass or less, based on 100 parts by mass of the rubber material.

[0074] Examples of other additives include known materials that can be added to the elastic layer, such as foaming agents, foaming aids, softeners, plasticizers, curing agents, vulcanizers, vulcanization accelerators, antioxidants, surfactants, coupling agents, and fillers (such as silicon dioxide and calcium carbonate).

[0075] The thickness of the conductive foamed elastic layer is, for example, 1 mm to 20 mm, or preferably 2 mm to 15 mm.

[0076] The hardness of the conductive foamed elastic layer measured with an Asker-C hardness meter is preferably 20° to 70°, and more preferably 30° to 60°, under a load of 1 kgf.

[0077] <Method for producing conductive roller>

[0078] The conductive roller of the present embodiment is obtained by disposing a conductive foam elastic layer on a support member. The method of disposing the conductive foam elastic layer on the support member is not particularly limited, and examples thereof include a method of preparing a cylindrical conductive foam elastic body and inserting the support member into the cylindrical conductive foam elastic body. The outer diameter of the conductive roller is adjusted, for example, by grinding the outer peripheral surface of the conductive foam elastic layer disposed on the support member.

[0079] The method for manufacturing the conductive roller of the present embodiment preferably includes: grinding the outer peripheral surface of the conductive foamed elastic layer disposed on the support member (referred to as a "grinding step"); and bringing the outer peripheral surface of the conductive foamed elastic layer after grinding into rotational contact with a heating roller (referred to as a "surface heat treatment step"). The convex portions formed on the outer peripheral surface of the conductive foamed elastic layer during the grinding step are flattened by the surface heat treatment step, and the amplitude of the concavo-convex components in the range of a period of 100 μm or more and 300 μm or less on the outer peripheral surface of the conductive foamed elastic layer is suppressed.

[0080] The surface heat treatment step is performed, for example, by pressing a heated metal roll against the outer peripheral surface of the polished conductive foamed elastic layer and rotating the supporting member, the conductive foamed elastic layer, and the metal roll.

[0081] The amplitude and integrated value St of the concavo-convex component in the range of 100 μm to 300 μm on the outer peripheral surface of the conductive foamed elastic layer can be controlled by the size of the foamed cells of the conductive foamed elastic layer, the polishing step or the surface heat treatment step of the outer peripheral surface of the conductive foamed elastic layer.

[0082] The integral value St tends to be smaller as the foaming pore size of the conductive foamed elastic layer is smaller. When the conductive roller is applied to the transfer roller, if the foaming pore size of the outer peripheral surface of the transfer roller is small, dirt may be generated on the back side of the recording medium (the side on which the transfer roller contacts), so the foaming pore size of the outer peripheral surface of the transfer roller is preferably larger to some extent. It is speculated that this phenomenon is because the toner remaining in the image holder or the intermediate transfer body may be transferred to the transfer roller. If the foaming pore size of the outer peripheral surface of the transfer roller is larger to some extent, the toner is contained in the open foaming pores, so the toner adhesion to the back side of the recording medium where the image is subsequently formed is suppressed.

[0083] From the above viewpoints, the foamed pore diameter of the conductive foamed elastic layer is preferably 30 μm to 300 μm, more preferably 40 μm to 280 μm, and further preferably 50 μm to 250 μm.

[0084] The foamed pore size of the conductive foamed elastic layer can be controlled by the content of the foaming agent contained in the base compound of the conductive foamed elastic layer and / or the temperature and time for vulcanization molding of the conductive foamed elastic layer.

[0085] The method for measuring the foamed pore diameter of the conductive foamed elastic layer is as follows.

[0086] A cross section in the thickness direction of the conductive foamed elastic layer was made using a razor. A total of 4 cross sections were made in parallel with the axial direction and every 90° in the circumferential direction. The axial center of the cross section was photographed using a laser microscope (KEYENCE, VK-X200) to obtain an image. The image was analyzed using image analysis software (Media Cybernetics, Image-Pro Plus), and 100 foaming cells between 2000 μm and 50 μm deep were randomly selected and the major diameter was measured. The average value of the 100 cells was calculated, and then the average of the 4 cross sections was calculated, and the average value was used as the foaming pore diameter.

[0087] The integrated value St tends to be smaller as the surface roughness of the grindstone used in the grinding process is smaller, as the rotation speed of the grindstone is faster, as the rotation speed of the workpiece is faster, and as the traverse speed is slower.

[0088] Examples of the grindstone include cylindrical metal grindstones having a scepter-shaped protrusion on the surface. The protrusion is preferably in the shape of a cone or a polygonal pyramid such as a triangular pyramid or a quadrangular pyramid, and the heights of the protrusions are preferably the same.

[0089] When the above grindstone is used, the rotation speed of the grindstone is preferably 5000 rpm or more, the rotation speed of the workpiece is preferably 1000 rpm or more, and the traverse speed is preferably 500 mm / min or more and 2500 mm / min or less. rpm is the abbreviation of revolutions per minute.

[0090] The integral value St tends to decrease as the temperature of the surface heat treatment step increases. However, if the temperature of the surface heat treatment step is too high, the surface hardness increases when the outer peripheral surface of the conductive foamed elastic layer melts and solidifies, so it is preferably not too high.

[0091] From the above viewpoints, the temperature of the heating roller used in the surface heat treatment step is preferably 80°C to 180°C, more preferably 100°C to less than 180°C, and further preferably 120°C to less than 180°C.

[0092] The rotation speed of the heating roller is preferably not less than 2 rpm and not more than 60 rpm, and the rotation speed of the work is preferably not less than 2 rpm and not more than 60 rpm.

[0093] <Image Forming Device, Transfer Device, Processing Cartridge>

[0094] Figure 4 1 is a schematic structural diagram showing a direct transfer type image forming apparatus as an example of the image forming apparatus of the present embodiment.

[0095] Figure 4 The image forming apparatus 200 shown in the figure includes: a photoreceptor 207 (an example of an image holding member); a charging roller 208 for charging the surface of the photoreceptor 207 (an example of a charging unit); an exposure device 206 for forming an electrostatic image on the surface of the charged photoreceptor 207 (an example of an electrostatic image forming unit); a developing device 211 for developing the electrostatic image formed on the surface of the photoreceptor 207 into a toner image using a developer containing a toner (an example of a developing unit); and a transfer roller 212 for transferring the toner image formed on the surface of the photoreceptor 207 to the surface of a recording medium (an example of a transfer unit, an example of a transfer device of this embodiment). As the transfer roller 212, the conductive roller of this embodiment is suitable.

[0096] Figure 4 The image forming apparatus 200 shown further includes: a cleaning device 213 for removing the toner remaining on the surface of the photosensitive body 207; a static eliminating device 214 for eliminating the static electricity on the surface of the photosensitive body 207; and a fixing device 215 for fixing the toner image to the recording medium (an example of a fixing unit).

[0097] The charging roller 208 may be a contact charging type or a non-contact charging type. A voltage is applied to the charging roller 208 from a power source 209 .

[0098] Examples of the exposure device 206 include an optical device including a light source such as a semiconductor laser or an LED (light emitting diode).

[0099] The developing device 211 is a device that supplies toner to the photoconductor 207. The developing device 211 brings a rolled developer holder into contact with or close to the photoconductor 207, for example, to attach the toner to the electrostatic image on the photoconductor 207, thereby forming a toner image.

[0100] The transfer roller 212 is a transfer roller that directly contacts the surface of the recording medium, and is disposed at a position facing the photosensitive body 207. The recording paper 500 (an example of the recording medium) is fed by a feeding mechanism to the gap between the transfer roller 212 and the photosensitive body 207. When a transfer bias is applied to the transfer roller 212, an electrostatic force from the photosensitive body 207 to the recording paper 500 acts on the toner image, and the toner image on the photosensitive body 207 is transferred to the recording paper 500.

[0101] As the fixing device 215 , for example, there can be mentioned a heating fixing device including a heating roller and a pressure roller for pressing the heating roller.

[0102] The cleaning device 213 may include a device including a blade, a brush, a roller, or the like as a cleaning member.

[0103] The static eliminating device 214 is a device that irradiates the surface of the photoreceptor 207 after transfer with light to eliminate residual potential of the photoreceptor 207 , for example.

[0104] The photosensitive body 207 and the transfer roller 212 may be, for example, a cartridge structure (processing cartridge of this embodiment) that is integrated by a housing and can be attached and detached from the image forming apparatus. The cartridge structure (processing cartridge of this embodiment) may further include at least one selected from the group consisting of a charging roller 208, an exposure device 206, a developing device 211, and a cleaning device 213.

[0105] The image forming device may be a serial image forming device in which the photosensitive body 207, the charging roller 208, the exposure device 206, the developing device 211, the transfer roller 212 and the cleaning device 213 are used as one image forming unit, and two or more of the image forming units are arranged and mounted.

[0106] Figure 5 1 is a schematic structural diagram showing an image forming apparatus of an intermediate transfer system as an example of the image forming apparatus of the present embodiment. Figure 5 The image forming apparatus shown is a tandem-type image forming apparatus in which four image forming units are arranged in parallel.

[0107] Figure 5 In the image forming apparatus shown, a transfer unit for transferring a toner image formed on the surface of an image holding body to the surface of a recording medium is configured as a transfer unit (an example of a transfer device of this embodiment) having an intermediate transfer body, a primary transfer unit, and a secondary transfer unit. The transfer unit may be a cartridge structure that can be mounted and removed from the image forming apparatus.

[0108] Figure 5 The image forming apparatus shown in the figure includes: a photoreceptor 1 (an example of an image holding member); a charging roller 2 for charging the surface of the photoreceptor 1 (an example of a charging unit); an exposure device 3 for forming an electrostatic image on the surface of the charged photoreceptor 1 (an example of an electrostatic image forming unit); a developing device 4 for developing the electrostatic image formed on the surface of the photoreceptor 1 into a toner image using a developer containing a toner (an example of a developing unit); an intermediate transfer belt 20 (an example of an intermediate transfer member); a primary transfer roller 5 for transferring the toner image formed on the surface of the photoreceptor 1 to the surface of the intermediate transfer belt 20 (an example of a primary transfer unit); and a secondary transfer roller 26 for transferring the toner image transferred to the surface of the intermediate transfer belt 20 to the surface of a recording medium (an example of a secondary transfer unit). The conductive roller of the present embodiment is applied to at least one of the primary transfer roller 5 and the secondary transfer roller 26.

[0109] Figure 5 The image forming device shown further includes: a fixing device 28 for fixing the toner image to the recording medium (an example of a fixing unit); a photosensitive body cleaning device 6 for removing the toner remaining on the surface of the photosensitive body 1; and an intermediate transfer belt cleaning device 30 for removing the toner remaining on the surface of the intermediate transfer belt 20.

[0110] Figure 5The image forming apparatus shown in the figure includes first to fourth image forming units 10Y, 10M, 10C, and 10K of an electrophotographic method for outputting images of yellow (Y), magenta (M), cyan (C), and black (K) colors based on color-separated image data. These image forming units 10Y, 10M, 10C, and 10K are arranged in parallel with each other at intervals in the horizontal direction. The image forming units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the image forming apparatus.

[0111] Above each image forming unit 10Y, 10M, 10C, 10K, an intermediate transfer belt 20 is extended through each image forming unit. The intermediate transfer belt 20 is wound around a driving roller 22 and a supporting roller 24 that are in contact with the inner surface of the intermediate transfer belt 20, and runs in a direction from the first image forming unit 10Y to the fourth image forming unit 10K. The supporting roller 24 applies a force in a direction away from the driving roller 22 by a spring (not shown) or the like, and provides tension to the intermediate transfer belt 20 wound around the two. An intermediate transfer belt cleaning device 30 is provided on the image holding surface side of the intermediate transfer belt 20 so as to face the driving roller 22.

[0112] The developing devices 4Y, 4M, 4C, and 4K of the image forming units 10Y, 10M, 10C, and 10K are supplied with yellow, magenta, cyan, and black toners stored in toner cartridges 8Y, 8M, 8C, and 8K, respectively.

[0113] The first to fourth image forming units 10Y, 10M, 10C, and 10K have the same configuration and operation, and therefore, when describing the image forming units below, the first image forming unit 10Y will be described as a representative.

[0114] The first image forming unit 10Y comprises: a photoreceptor 1Y; a charging roller 2Y for charging the surface of the photoreceptor 1Y; a developing device 4Y for developing the electrostatic image formed on the surface of the photoreceptor 1Y into a toner image using a developer containing a toner; a primary transfer roller 5Y for transferring the toner image formed on the surface of the photoreceptor 1Y to the surface of the intermediate transfer belt 20; and a photoreceptor cleaning device 6Y for removing the toner remaining on the surface of the photoreceptor 1Y after the primary transfer.

[0115] The charging roller 2Y charges the surface of the photoreceptor 1Y. The charging roller 2Y may be a contact charging roller or a non-contact charging roller.

[0116] The charged surface of the photoreceptor 1Y is irradiated with the laser beam 3Y from the exposure device 3. Thus, an electrostatic image of a yellow image pattern is formed on the surface of the photoreceptor 1Y.

[0117] The developing device 4Y contains, for example, an electrostatic image developer containing at least a yellow toner and a carrier. The yellow toner is frictionally charged by being stirred inside the developing device 4Y. The electrostatic image formed on the photoreceptor 1Y is developed as a toner image by passing the surface of the photoreceptor 1Y through the developing device 4Y.

[0118] The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20 and is disposed at a position opposite to the photoreceptor 1Y. A bias power source (not shown) for applying a primary transfer bias is connected to the primary transfer roller 5Y. The primary transfer roller 5Y transfers the toner image on the photoreceptor 1Y to the intermediate transfer belt 20 by electrostatic force.

[0119] Toner images of the respective colors are sequentially transferred multiple times from the first to fourth image forming units 10Y, 10M, 10C, and 10K onto the intermediate transfer belt 20. The intermediate transfer belt 20 to which the toner images of the four colors are transferred multiple times by the first to fourth image forming units moves toward a secondary transfer unit composed of a backup roller 24 and a secondary transfer roller 26.

[0120] The secondary transfer roller 26 is a transfer roller that directly contacts the surface of the recording medium, and is arranged at a position opposite to the support roller 24 on the outer side of the intermediate transfer belt 20. The recording paper P (an example of the recording medium) is fed to the gap between the secondary transfer roller 26 and the intermediate transfer belt 20 by the feeding mechanism. When the secondary transfer bias is applied to the secondary transfer roller 26, the electrostatic force from the intermediate transfer belt 20 to the recording paper P acts on the toner image, and the toner image on the intermediate transfer belt 20 is transferred to the recording paper P.

[0121] The recording paper P to which the toner image is transferred is fed into a pressure-contact portion (nip portion) of a fixing device 28 formed of a pair of rollers, and the toner image is fixed to the recording paper P.

[0122] The toner and developer used in the image forming apparatus of the present embodiment are not particularly limited, and any known toner and developer for electrophotography can be used. The recording medium used in the image forming apparatus of the present embodiment is not particularly limited, and examples thereof include paper used in electrophotographic copiers or printers; OHP sheets; and the like.

[0123] Example

[0124] Hereinafter, the embodiments of the present application will be described in detail through examples, but the embodiments of the present application are not limited to these examples.

[0125] <Measurement method, evaluation method>

[0126] The measuring methods and evaluation methods applied to Examples and Comparative Examples are as follows.

[0127] [Calculation of integral value St]

[0128] Using an optical microscope (KEYENCE, VHX-5000), the profile was photographed from the side perpendicular to the axial direction of the conductive roller and from the height of the profile of the outer peripheral surface of the conductive foamed elastic layer under the imaging condition of a resolution of 2 μm or less per pixel. The imaging locations were 20 locations in total, including 5 locations in the axial direction (center, location 50 mm from the center, location 100 mm from the center) and 4 locations in the circumferential direction (every 90°).

[0129] The profiles were analyzed using analysis software (ImageJ) to extract the concave and convex waveforms.

[0130] For the interval of 1 mm in axial length, the concave-convex waveform was subjected to fast Fourier transform to obtain a spectrum, and the integral value (μm) of the amplitude (μm) in the range of period 100 μm to 300 μm, the amplitude (μm) of period 300 μm, and the amplitude (μm) of period 100 μm were obtained, and the average value of 20 points was calculated. Analysis software (ImageJ) was used for fast Fourier transform and spectrum analysis.

[0131] [Determination of Foaming Cell Diameter]

[0132] A cross section in the thickness direction of the conductive foamed elastic layer was made using a razor. A total of 4 cross sections were made in parallel with the axial direction and every 90° in the circumferential direction. The axial center of the cross section was photographed using a laser microscope (KEYENCE, VK-X200) to obtain an image. The image was analyzed using image analysis software (Media Cybernetics, Image-ProPlus), and 100 foaming cells between 2000 μm and 50 μm deep were randomly selected and the major diameter was measured. The average value of the 100 cells was calculated, and then the average of the 4 cross sections was calculated, and the average value was used as the foaming pore diameter.

[0133] [Evaluation of density unevenness]

[0134] The conductive roller was used as a transfer roller and mounted on DocuPrint CP400d (manufactured by Fuji Xerox Co., Ltd.), which is a direct transfer image forming apparatus. Ten solid images with an image density of 100% were output on A4-size paper in an environment of a temperature of 10°C and a relative humidity of 15%. The entire paper was observed and classified according to the following evaluation criteria.

[0135] A + (◎): High image quality with no density unevenness observed.

[0136] A (○): Good image quality with almost no density unevenness observed.

[0137] B (△): Density unevenness is observed, but the image quality is within the allowable range.

[0138] C (×): Image quality with unacceptable density unevenness was observed.

[0139] [Evaluation of the dirt on the back]

[0140] Using the above image forming apparatus, 180 halftone images with an image density of 50% were output onto A4-size paper under an environment of a temperature of 28° C. and a relative humidity of 85%, and then 20 solid images with an image density of 100% were output onto A4-size paper, and this was repeated 25 times (a total of 5,000 sheets were output). The back surfaces (surfaces without image formation) of the 4,991st to 5,000th sheets (a total of 10 sheets) were observed, and the worst dirt was classified as follows.

[0141] A (○): Dirt is slightly observed, but there is no problem in practical use.

[0142] B (△): Dirt is observed, but within the allowable range.

[0143] C (×): Unacceptable dirt was observed.

[0144] <Example 1>

[0145] [Formation of Conductive Foamed Elastic Layer]

[0146] Rubber material (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber:

[0147] CG102 manufactured by OSAKA SODA Co., Ltd.: 60%, acrylonitrile butadiene rubber: N230SV manufactured by JSR Co., Ltd.: 40%)... 100 parts by mass

[0148] Carbon black (#55, manufactured by Asahi Carbon Co., Ltd.) 15 parts by mass

[0149] ·Vulcanizing agent (sulfur) (200 mesh, manufactured by Tsurumi Chemical Industries, Ltd.)···1 part by mass

[0150] Vulcanization accelerator (Nocceler DM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) 1.5 parts by mass

[0151] ·Vulcanization accelerator (Nocceler TET, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)···1.0 part by mass

[0152] Zinc oxide (Zinc White No. 1, manufactured by Shodo Chemical Industry Co., Ltd.) 5 parts by mass

[0153] ·Calcium carbonate (WHITON SSB, manufactured by Shiraishi Calcium Co., Ltd.)···10 parts by mass

[0154] ·Stearic acid (Stearic acid S, manufactured by Kao Corporation)···1 part by mass

[0155] · Foaming agent (NEOCELLBORN N#5000, manufactured by Eiwa Chemical Industry Co., Ltd.) ··· Appropriate amount (amount to achieve the desired foaming pore diameter)

[0156] The above materials were kneaded with an open mill to obtain a rubber kneaded material A. The rubber kneaded material A was extruded and formed into a cylindrical shape with an outer diameter of 19 mm and an inner diameter of 5.6 mm, and heated at 160°C for 30 minutes to vulcanize and foam it to obtain a cylindrical conductive foamed elastic body. An axis (made of SUS, with a diameter of 6 mm) was inserted into the cylindrical conductive foamed elastic body, and a rubber grinder equipped with a cylindrical metallic grindstone (No. F60) having a socket-shaped protrusion was used to grind the outer peripheral surface of the conductive foamed elastic body at a grindstone speed of 7000 rpm, a workpiece speed of 1500 rpm, and a traverse speed of 1500 mm / min. In this way, a conductive roller 1 with a conductive foamed elastic layer having an outer diameter of 16 mm and a length of 224 mm was obtained.

[0157] <Example 2>

[0158] The conductive roller 2 was obtained in the same manner as in Example 1 except that the heating was changed to 145° C. for 40 minutes, the grinding stone rotation speed was changed to 6000 rpm, and the traverse speed was changed to 2000 mm / min.

[0159] <Example 3>

[0160] The conductive roller 3 was obtained in the same manner as in Example 1 except that the heating was changed to 135° C. for 50 minutes, the grinding stone rotation speed was changed to 5000 rpm, and the traverse speed was changed to 2500 mm / min.

[0161] <Example 4>

[0162] The conductive roller 4 was obtained in the same manner as in Example 1 except that the heating time was changed to 185° C. for 20 minutes.

[0163] <Example 5>

[0164] The conductive roller 5 was obtained in the same manner as in Example 1 except that the heating time was changed to 175° C. for 20 minutes.

[0165] <Comparative Example 1>

[0166] The conductive roller 6 was obtained in the same manner as in Example 1 except that the heating was changed to 130° C. for 60 minutes, the grindstone was changed to No. F40, the grindstone rotation speed was changed to 4000 rpm, and the traverse speed was changed to 3000 mm / min.

[0167] <Comparative Example 2>

[0168] The conductive roller 7 was obtained in the same manner as in Comparative Example 1 except that the heating time was changed to 190° C. for 15 minutes.

[0169] [Table 1]

[0170]

[0171] <Example 11>

[0172] [Formation of Conductive Foamed Elastic Layer]

[0173] Rubber material (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber: CG102 manufactured by OSAKA SODA Co., Ltd.: 60%, acrylonitrile butadiene rubber: N230SV manufactured by JSR Co., Ltd.: 40%)···100 parts by mass

[0174] Carbon black (#55, manufactured by Asahi Carbon Co., Ltd.) 15 parts by mass

[0175] ·Vulcanizing agent (sulfur) (200 mesh, manufactured by Tsurumi Chemical Industries, Ltd.)···1 part by mass

[0176] Vulcanization accelerator (Nocceler DM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) 1.5 parts by mass

[0177] ·Vulcanization accelerator (Nocceler TET, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)···1.0 part by mass

[0178] Zinc oxide (Zinc White No. 1, manufactured by Shodo Chemical Industry Co., Ltd.) 5 parts by mass

[0179] ·Calcium carbonate (WHITON SSB, manufactured by Shiraishi Calcium Co., Ltd.)···10 parts by mass

[0180] ·Stearic acid (Stearic acid S, manufactured by Kao Corporation)···1 part by mass

[0181] · Foaming agent (NEOCELLBORN N#5000, manufactured by Eiwa Chemical Industry Co., Ltd.)···5 parts by mass

[0182] The above materials were kneaded with an open mill to obtain a rubber kneaded material B. The rubber kneaded material B was extruded and molded into a cylindrical shape with an outer diameter of 19 mm and an inner diameter of 5.6 mm, and heated at 160° C. for 30 minutes to vulcanize and foam it to obtain a cylindrical conductive foamed elastic body. A shaft (made of SUS, with a diameter of 6 mm) was inserted into the cylindrical conductive foamed elastic body, and the outer peripheral surface of the conductive foamed elastic body was grinded using a rubber grinder equipped with a cylindrical metallic grindstone (No. F60) having a socket-shaped protrusion at a grindstone speed of 7000 rpm, a workpiece speed of 1500 rpm, and a traverse speed of 1500 mm / min, so that the outer diameter of the conductive foamed elastic layer was 16 mm.

[0183] Next, a metal roller (SUS, 32 mm in diameter) adjusted to 120° C. was sunk 0.8 mm into the outer peripheral surface of the polished conductive foamed elastic body and rotated in contact for 90 seconds at a metal roller rotation speed of 10 rpm and a workpiece rotation speed of 10 rpm.

[0184] In this way, a conductive roller 11 having an outer diameter of 16 mm and a length of 224 mm and provided with a conductive foamed elastic layer was obtained.

[0185] <Example 12>

[0186] The conductive roller 12 was obtained in the same manner as in Example 11 except that the grinding stone rotation speed was changed to 6000 rpm and the traverse speed was changed to 2000 mm / min.

[0187] <Example 13>

[0188] The conductive roller 13 was obtained in the same manner as in Example 11 except that the grinding stone rotation speed was changed to 5000 rpm and the traverse speed was changed to 2500 mm / min.

[0189] <Example 14>

[0190] The conductive roller 14 was obtained in the same manner as in Example 11 except that the temperature of the metal roller was changed to 80°C.

[0191] <Example 15>

[0192] The same procedure as in Example 11 was carried out except that the temperature of the metal roller was changed to 160° C., thereby obtaining a conductive roller 15 .

[0193] <Example 16>

[0194] The conductive roller 16 was obtained in the same manner as in Example 11 except that the temperature of the metal roller was changed to 180°C.

[0195] <Example 17>

[0196] The same procedure as in Example 11 was carried out except that the grindstone was changed to F40, the grindstone rotation speed was changed to 4000 rpm, the traverse speed was changed to 3000 mm / min, and the temperature of the metal roller was changed to 80° C., thereby obtaining a conductive roller 17 .

[0197] <Comparative Example 11>

[0198] The same procedure as in Example 17 was carried out except that the temperature of the metal roller was changed to 60° C., thereby obtaining a conductive roller 18 .

[0199] <Comparative Example 12>

[0200] A conductive roller 19 was obtained in the same manner as in Example 17, except that the surface heat treatment using the metal roller was not performed.

[0201] [Table 2]

[0202]

Claims

1. A conductive roller comprising: Support components; and a conductive foamed elastic layer disposed on the supporting member, In the spectrum of period and amplitude obtained by fast Fourier transforming the axial concavo-convex waveform of the outer peripheral surface of the conductive foamed elastic layer, the integral value St of the amplitude in the range of period of 100 μm to 300 μm is 100 μm to 455 μm, and the amplitude A of the period of 300 μm is 100 μm to 455 μm. 300 Amplitude A of 1.5 μm to 3.6 μm, period 300 μm 300 With period 100μm and amplitude A 100 Ratio A 300 / A 100 is 1 to 3, the foaming pore size of the conductive foamed elastic layer is 30 μm to 300 μm, and the units of the period and amplitude are μm.

2. The conductive roller according to claim 1, in, The integrated value St is 410 μm or less.

3. The conductive roller according to claim 1, in, The amplitude A 300 It is less than 3.0μm.

4. The conductive roller according to claim 1, in, The ratio A 300 / A 100 It is above 1 and below 2.

5.

5. The method for producing a conductive roller according to any one of claims 1 to 4, wherein include: grinding the outer peripheral surface of the conductive foamed elastic layer disposed on the support member; and The polished outer peripheral surface of the conductive foamed elastic layer is brought into rotational contact with a heating roller. 6 . A transfer device comprising the conductive roller according to claim 1 .

7. A process cartridge comprising: an image holding body; and The transfer device according to claim 6, The process cartridge is attachable to and detachable from the image forming apparatus.

8. An image forming apparatus comprising: Image holding body; a charging unit that charges the surface of the image holding body; an electrostatic image forming unit that forms an electrostatic image on the charged surface of the image holding member; a developing unit that develops the electrostatic image formed on the surface of the image holding member using a developer containing a toner to form a toner image; and A transfer unit comprising the conductive roller according to any one of claims 1 to 4, and transferring the toner image to a surface of a recording medium.

Images