阅读说明：本技术 导电性辊、导电性辊的制造方法、转印装置、处理盒和图像形成装置 (Conductive roller, method for manufacturing conductive roller, transfer device, process cartridge, and image forming apparatus ) 是由 六反实 新宫剑太 于 2020-02-17 设计创作，主要内容包括：本发明提供导电性辊、导电性辊的制造方法、转印装置、处理盒和图像形成装置,所述导电性辊具备支撑部件和配置于上述支撑部件上的导电性发泡弹性层,将上述导电性发泡弹性层的外周面的轴向的凹凸波形进行快速傅利叶变换而得到的周期(μm)和振幅(μm)的谱图中,周期100μm以上300μm以下的范围的振幅的积分值St为455μm以下。(The invention provides a conductive roller, a method for manufacturing the conductive roller, a transfer device, a process cartridge and an image forming apparatus, wherein the conductive roller comprises a support member and a conductive foamed elastic layer arranged on the support member, and in a spectrum of a period (mum) and an amplitude (mum) obtained by performing fast Fourier transform on a concave-convex waveform in an axial direction of an outer peripheral surface of the conductive foamed elastic layer, an integral value St of the amplitude in a range of 100 to 300 μm of the period is 455 μm.)

1. A conductive roller is provided with:

a support member; and

a conductive foamed elastic layer disposed on the support member,

in a spectrum of a period and an amplitude obtained by subjecting a waveform of irregularities in an axial direction of an outer peripheral surface of the conductive foamed elastic layer to a fast Fourier transform, an integral St of the amplitude in a range of a period of 100 to 300 μm is 455 μm or less, and a unit of the period and the amplitude is μm.

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

3. A conductive roller is provided with:

a support member; and

a conductive foamed elastic layer disposed on the support member,

an amplitude A with a cycle of 300 μm in a period and amplitude spectrum obtained by subjecting the axially concave-convex waveform of the outer peripheral surface of the conductive foamed elastic layer to a fast Fourier transform₃₀₀Is 3.6 μm or less, and the unit of the period and the amplitude is μm.

4. The conductive roller according to claim 3, wherein the amplitude A is₃₀₀Is 3.0 μm or less.

5. The conductive roller according to any one of claims 1 to 4, wherein the axially concave-convex waveform of the outer peripheral surface of the conductive foamed elastic layer has a period obtained by fast Fourier transformAmplitude A of 300 μm period in the spectrum of sum amplitude₃₀₀Amplitude A with period of 100 μm₁₀₀Ratio of A₃₀₀/A₁₀₀Is1 to 3 inclusive, and the unit of the period and the amplitude is μm.

6. The conductive roller according to claim 5, wherein the ratio A₃₀₀/A₁₀₀Is1 to 2.5 inclusive.

7. The method for manufacturing the conductive roller according to any one of claims 1 to 6, comprising:

polishing an outer peripheral surface of the conductive foamed elastic layer disposed on the support member; and

the outer peripheral surface of the conductive foamed elastic layer after polishing is brought into rotational contact with a heating roller.

8. A transfer device comprising the conductive roller according to any one of claims 1 to 6.

9. A process cartridge includes:

an image holding body; and

a transfer device according to claim 8, wherein the transfer device is provided with a transfer roller,

the process cartridge is attached to and detached from the image forming apparatus.

10. An image forming apparatus includes:

an image holding body;

a charging unit that charges a surface of the image holding body;

an electrostatic image forming unit that forms an electrostatic image on a surface of the charged image holding body;

a developing unit that develops the electrostatic image formed on the surface of the image holding body with 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 6, for transferring the toner image onto a surface of a recording medium.

Technical Field

The present application relates to a conductive roller, a method of manufacturing the conductive roller, a transfer device, a process cartridge, and an image forming apparatus.

Background

Japanese patent No. 2959445 discloses a developing roller having fine bristle-like irregularities inclined in the circumferential direction, the irregularities having a height of 0.1 to 30 μm and an average interval between protrusions in the circumferential direction of 1 to 200 μm, the irregularities forming wavy stripes in the axial direction on the roller surface, the roller surface having an average roughness Rz at JIS10 points in the circumferential direction of 5 to 20 μm, an average roughness Rz at JIS10 points in the axial direction of 3 to 15 μm, and the average roughness Rz in the circumferential direction being larger than the average roughness Rz in the axial direction.

Japanese patent No. 6364333 discloses a developer supply roller whose surface is a polymer foam material containing an ether polyurethane foam and whose surface roughness is 40 μm or more and 140 μm or less. Here, the surface roughness is set such that the measurement length is 40mm, the measurement interval is 1mm, and the number of measurement points is 40 points, and is a standard deviation of displacement from a reference line of all measurement points.

Disclosure of Invention

The subject of the application is to provide a conductive roller, the outermost layer of which is a conductive foamed elastic layer, in a period (mum) and amplitude (mum) spectrogram obtained by fast Fourier transform of an axial concave-convex waveform of the outer peripheral surface of the conductive foamed elastic layer, the integral value St of the amplitude in a range of 100-300μm of the period exceeds 455μm or the amplitude A of 300μm of the period₃₀₀The conductive roller having a thickness exceeding 3.6 μm is less likely to cause abnormal discharge between the roller and the opposing member when a voltage is applied.

According to the 1 St aspect of the present application, there is provided a conductive roller comprising a support member and a conductive foamed elastic layer disposed on the support member, wherein in a spectrum of a period (μm) and an amplitude (μm) obtained by subjecting a waveform of irregularities in an outer peripheral surface of the conductive foamed elastic layer in an axial direction to a fast fourier transform, an integrated value St of the amplitude in a range of the period from 100 μm to 300 μm is 455 μm or less.

According to claim 2 of the present application, the integrated value St is 410 μm or less.

According to claim 3 of the present application, the foam structure comprises a support member and a conductive foamed elastic layer disposed on the support member, and has a period (μm) and an amplitude (μm) obtained by subjecting a concave-convex waveform in an axial direction of an outer peripheral surface of the conductive foamed elastic layer to a fast fourier transformμ m) of the spectrum, amplitude A of a period of 300 μm₃₀₀Is 3.6 μm or less.

According to claim 4 of the present application, the amplitude A is₃₀₀Is 3.0 μm or less.

According to claim 5 of the present application, in a spectrum of a period (μm) and an amplitude (μm) obtained by subjecting the axially concave-convex waveform of the outer peripheral surface of the conductive foamed elastic layer to a fast fourier transform, the amplitude a of the period 300 μm₃₀₀Amplitude A with period of 100 μm₁₀₀Ratio of A₃₀₀/A₁₀₀1 to 3.

According to claim 6 of the present application, the above ratio A₃₀₀/A₁₀₀Is1 to 2.5 inclusive.

According to the 7 th aspect of the present application, there is provided the method for manufacturing the conductive roller, comprising: polishing an outer peripheral surface of the conductive foamed elastic layer disposed on the support member; and bringing the outer peripheral surface of the polished conductive foamed elastic layer into rotational contact with a heating roller.

According to the 8 th aspect of the present application, there is provided a transfer device including the conductive roller.

According to the 9 th aspect of the present application, there is provided a process cartridge which is attached to and detached from an image forming apparatus, the process cartridge including the image holder and the transfer device.

According to a 10 th aspect of the present application, there is provided an image forming apparatus including: an image holding body; a charging unit that charges a surface of the image holding body; an electrostatic image forming unit that forms an electrostatic image on a surface of the charged image holding body; a developing unit that develops the electrostatic image formed on the surface of the image holding body with a developer containing a toner to form a toner image; and a transfer unit including the conductive roller, for transferring the toner image onto a surface of a recording medium.

Effects of the invention

According to the above aspect 1, it is possible to provide a conductive roller in which abnormal discharge is less likely to occur between the roller and a counter member when a voltage is applied, as compared with a conductive roller in which the outermost layer is a conductive foamed elastic layer and the integrated value St exceeds 455 μm.

According to the above aspect 2, it is possible to provide a conductive roller in which abnormal discharge is less likely to occur between the roller and the opposing member when a voltage is applied, as compared with a conductive roller in which the outermost layer is a conductive foamed elastic layer and the integrated value St exceeds 410 μm.

According to the above aspect 3, the outermost layer is a conductive foamed elastic layer and has an amplitude A₃₀₀A conductive roller which is less likely to cause abnormal discharge between the roller and a counter member when a voltage is applied, as compared with a conductive roller having a thickness of more than 3.6 μm, can be provided.

According to the above-mentioned aspect 4, the outermost layer is a conductive foamed elastic layer and has an amplitude A₃₀₀A conductive roller which is less likely to cause abnormal discharge between the roller and a counter member when a voltage is applied, as compared with a conductive roller having a thickness of more than 3.0 [ mu ] m, can be provided.

According to the above aspect 5, the outermost layer is a conductive foamed elastic layer, and the above ratio A₃₀₀/A₁₀₀The conductive roller having a conductivity exceeding 3 can provide a conductive roller which is less likely to cause abnormal discharge between the opposite member and the conductive roller when a voltage is applied.

According to the above-mentioned aspect 6, the outermost layer is a conductive foamed elastic layer, and the above-mentioned ratio A₃₀₀/A₁₀₀The conductive roller having a conductivity exceeding 2.5 can provide a conductive roller which is less likely to cause abnormal discharge between the roller and a counter member when a voltage is applied.

According to the above 7, as compared with the case where the outer peripheral surface of the conductive foamed elastic layer after polishing is not brought into rotational contact with the heating roller, it is possible to provide a method for manufacturing a conductive roller in which abnormal discharge is less likely to occur between the roller and the opposing member when a voltage is applied.

According to the above-mentioned aspect 8, the outermost layer of the conductive roller is a conductive foamed elastic layer, and the integral value St exceeds 455 μm or the amplitude A₃₀₀Compared with the case of exceeding 3.6 μm, a transfer device in which abnormal discharge is less likely to occur between the transfer device and the opposing member when a voltage is applied can be provided.

According to the above-mentioned aspect 9, the outermost layer of the conductive roller is a conductive foamed elastic layer, and the integral value St exceeds 455 μm or the amplitude A₃₀₀Over 3.6 μmIn contrast, a process cartridge in which abnormal discharge is less likely to occur between the process cartridge and the opposing member when a voltage is applied can be provided.

According to the above 10 th aspect, the outermost layer of the conductive roller is a conductive foamed elastic layer, and the integral value St exceeds 455 μm or the amplitude A₃₀₀An image forming apparatus in which abnormal discharge is less likely to occur between the image forming apparatus and the opposing member when a voltage is applied, as compared with the case where the voltage exceeds 3.6 μm, can be provided.

Drawings

Fig. 1 is a schematic perspective view showing an example of the conductive roller according to the present embodiment.

Fig. 2 is a schematic cross-sectional view showing an example of the conductive roller of the present embodiment, and is a cross-sectional view a-a of fig. 1.

Fig. 3 shows an example of the waveform of the unevenness of the outer peripheral surface of the conductive foamed elastic layer included in the conductive roller according to the present embodiment.

Fig. 4 is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

Fig. 5 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

Detailed Description

Hereinafter, embodiments of the present application will be described. The description and examples illustrate embodiments and do not limit the scope of the embodiments.

The numerical range expressed by "to" in the present application means a range including numerical values described before and after "to" as a minimum value and a maximum value, respectively.

In the present application, in the numerical ranges recited in the stepwise manner, the upper limit value or the lower limit value recited in one numerical range may be replaced with the upper limit value or the lower limit value recited in another stepwise manner. In the numerical ranges described in the present application, the upper limit or the lower limit of the numerical range may be replaced with the values shown in the examples.

In the present application, the term "step" includes not only an independent step but also a step that is not clearly distinguished from other steps, and is included in the term as long as the intended purpose of the step is achieved.

In the present application, when the embodiment is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. The dimensions of the components in the drawings are schematic dimensions, and the relative relationship between the dimensions of the components is not limited to this.

In the present application, each component may contain two or more corresponding substances. In referring to the amount of each ingredient in the composition herein, when two or more substances corresponding to each ingredient are present in the composition, the total amount of the two or more substances present in the composition is meant unless otherwise specified.

In the present application, the particles corresponding to each component may contain two or more kinds. When two or more kinds of particles corresponding to each component are present in the composition, the particle diameter of each component refers to a value of a mixture of the two or more kinds of particles present in the composition, unless otherwise specified.

< conductive roller >

The conductive roller of the present embodiment is suitably used for a transfer roller, a developing roller, a charging roller, an image holder cleaning roller, and the like of an electrophotographic image forming apparatus. However, the use of the conductive roller of the present embodiment is not limited to the above-described use.

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

Fig. 1 is a schematic perspective view showing an example of the conductive roller according to the present embodiment. Fig. 2 is a sectional view taken along line a-a of fig. 1, and is a sectional view of the conductive roller illustrated in fig. 1 taken along the radial direction.

As shown in fig. 1 and 2, the conductive roller 111 is a roller member having a hollow or non-hollow columnar 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.

The conductive roller of the present embodiment is not limited to the configuration shown in fig. 1 and 2, and may have an intermediate layer between the support member 112 and the conductive foamed elastic layer 113, for example.

Fig. 3 shows an example of the uneven waveform on the outer peripheral surface of the conductive foamed elastic layer 113.

Fig. 3(a) is a photograph of the outline of the outer peripheral surface of the conductive foamed elastic layer 113. The photograph of fig. 3(a) is taken using an optical microscope (for example, VHX-5000, KEYENCE corporation) under an imaging condition in which the resolution per 1 pixel is 2 μm or less, from the side perpendicular to the axial direction of the conductive roller 111 and from the height of the contour of the outer peripheral surface.

Fig. 3(b) is a concave-convex waveform drawn based on the photograph of fig. 3 (a). A section having a length of 1mm in the axial direction is taken from the concave-convex waveform of fig. 3(b), and a spectrum of a period (μm) and an amplitude (μm) is obtained by performing two-dimensional discrete Fourier transform (2D-DFT) using Fast Fourier Transform (FFT).

Fig. 3(c) is a spectrum obtained by performing FFT on the concave-convex waveform of fig. 3 (b). In the spectrum of fig. 3(c), the horizontal axis represents the period, the vertical axis represents the amplitude, and the scale of the horizontal axis is represented by a common logarithm.

An integral value (μm) of the amplitude (μm) in a range of a cycle of 100 μm to 300 μm is obtained from the calculation result of the FFT. The integrated value is the sum of the discretized amplitudes (μm) per 1 μm. The integrated value is found at least 20 places (for example, at 5 places in the axial direction and at 4 places in the circumferential direction (every 90 °)), and the average value at least 20 places is calculated as the integrated value St.

From the spectrum of FIG. 3(c), the amplitude of 300 μm in cycle and the amplitude of 100 μm in cycle were obtained. Similarly to the above, the amplitude of 300 μm in period and the amplitude of 100 μm in period were obtained for at least 20 positions, the average value of at least 20 positions was calculated, and the average value was defined as the amplitude A of 300 μm in period₃₀₀And an amplitude A of period 100 μm₁₀₀。

When a voltage is applied to the conductive roller 111 mounted in an electrophotographic image forming apparatus during image formation and the voltage is applied to the conductive roller 111, abnormal discharge may occur between the conductive roller 111 and a member facing the roller. For example, when the conductive roller 111 is a transfer roller, the toner on the opposite member is reversely charged due to abnormal discharge, and as a result, transfer failure of the toner or scattering of the toner occurs, and the image may have uneven density. On the other hand, when the integrated value St of the conductive foamed elastic layer 113 of the conductive roller 111 is 455 μm or less, abnormal discharge is less likely to occur between the opposite member and the applied voltage. The mechanism is presumed as follows.

The outer peripheral surface of the conductive foamed elastic layer 113, which is the outermost layer of the conductive roller 111, is usually subjected to polishing, and the outer peripheral surface of the conductive foamed elastic layer 113 has a complex uneven waveform in its contour. It is estimated that the uneven waveform contains uneven components having various periods, such as uneven components resulting from polishing, uneven components resulting from foam cells of the conductive foamed elastic layer 113, and uneven components resulting from particles dispersed and contained in the conductive foamed elastic layer 113.

The applicant of the present invention has studied the above-described waveform of the irregularities by performing a fast fourier transform, and as a result, has found that the occurrence of abnormal discharge between the conductive roller 111 and the member opposed to the roller can be suppressed by suppressing the amplitude of the irregularity component having a period in a range of 100 μm to 300 μm relatively low. It is estimated that the electric field is likely to concentrate on the convex portions having a period of 100 μm to 300 μm, and the convex portions serve as the starting points of the discharge and cause abnormal discharge between the opposing member and the electric field.

As a result of further investigation, the present applicant found that if the integrated 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 member facing the roller. For example, when the conductive roller 111 is a transfer roller, if the integrated value St is 455 μm or less, the occurrence of image density unevenness is suppressed.

From the viewpoint of suppressing abnormal discharge between the conductive roller 111 and the member facing the roller, the smaller the integral value St is, the more preferable is 410 μm or less, the more preferable is 380 μm or less, the more preferable is 350 μm or less, and the more preferable is 320 μm or less.

However, since it is difficult to completely eliminate the uneven component of several hundred micrometers on the outer peripheral surface of the conductive foamed elastic layer 113 having foamed cells, the lower limit of the integral value St is, for example, 100 μm or more, 150 μm or more, or 200 μm or more.

Integral value St and weekAmplitude A of period 300 μm₃₀₀The correlation of (A) is strong. Having an amplitude A₃₀₀The larger the integral value St becomes, the larger the tendency becomes. Amplitude A of period 300 μm₃₀₀Preferably 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 of period 300 μm₃₀₀The lower limit of (B) is not particularly limited, but is, for example, 1.5 μm or more.

The amplitude A of the period 300 μm is considered to suppress abnormal discharge between the conductive roller 111 and the opposed member of the roller₃₀₀And an amplitude A of period 100 μm₁₀₀Preferably, the following characteristics are provided.

Amplitude A of period 300 μm₃₀₀Amplitude A with period of 100 μm₁₀₀Preferably satisfies 1. ltoreq. A₃₀₀/A₁₀₀A relation of ≦ 3, more preferably 1 ≦ A₃₀₀/A₁₀₀A relation of not more than 2.5, more preferably 1. ltoreq. A₃₀₀/A₁₀₀The relationship of less than or equal to 2.

Amplitude A of period 100 μm₁₀₀Preferably 2 μm or less, more preferably 1.5 μm or less, and further preferably 1.2 μm or less. Amplitude A of period 100 μm₁₀₀The lower limit of (B) is not particularly limited, but is, for example, 0.8 μm or more.

Hereinafter, materials and the like of each layer constituting the conductive roller of the present embodiment will be described.

[ supporting Member ]

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

The support member is a conductive member, and examples thereof include: metal parts such as iron (free cutting steel, etc.), copper, brass, stainless steel, aluminum, nickel, etc.; a resin member or ceramic member having an outer surface subjected to plating treatment; a resin member or a ceramic member containing a conductive agent.

[ conductive foamed elastic layer ]

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

Examples of the rubber material (elastic material) include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluororubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer rubber, ethylene propylene diene monomer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and a rubber obtained by mixing these rubbers.

Examples of the foaming agent for making the elastic layer foamable include: water; azo compounds such as azodicarbonamide, azobisisobutyronitrile, diazoaminobenzene, and the like; benzenesulfonyl hydrazines such as benzenesulfonyl hydrazide, 4' -oxybis-benzenesulfonyl hydrazide and toluenesulfonyl hydrazide; bicarbonates such as sodium bicarbonate which generate carbon dioxide by thermal decomposition; NaNO for generating nitrogen gas₂And NH₄A mixture of Cl; an oxygen-generating peroxide; and the like. If necessary, a foaming aid, a foam stabilizer, a catalyst, and the like may be used.

The conductive agent is used when the conductivity of the rubber material is low or when the rubber material does not have conductivity. Examples of the conductive agent include an electron conductive agent and an ion conductive agent.

Examples of the electron conductive agent include: carbon black such as ketjen black and acetylene black; pyrolytic carbon, 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 solutions, and tin oxide-indium oxide solid solutions; a substance obtained by conducting a conductive treatment on the surface of an insulating substance; and the like. The electron conductive agent may be used alone or in combination of two or more.

Among them, the electron conductive agent is preferably carbon black, and the average primary particle diameter of the electron conductive agent is preferably 10nm to 150nm, more preferably 20nm to 100nm, and further preferably 30nm to 80 nm.

The content of carbon black is preferably 1 to 60 parts by mass, more preferably 10 to 40 parts by mass, per 100 parts by mass of the rubber material.

Examples of the ion conductive agent include quaternary ammonium salts (for example, perchlorates of lauryl trimethyl ammonium, stearyl trimethyl ammonium, lauryl trimethyl ammonium, cetyl trimethyl ammonium, or modified fatty acid dimethylethyl ammonium, chlorates, fluoroborates, sulfates, ethyl sulfates, benzyl bromides, or benzyl chlorides), aliphatic sulfonates, higher alcohol sulfate salts, higher alcohol ethylene oxide addition sulfate salts, higher alcohol phosphate salts, higher alcohol ethylene oxide addition phosphate salts, betaines, higher alcohol ethylene oxide, polyethylene glycol fatty acid esters, and polyol fatty acid esters. The ion conductive agent may be used alone or in combination of two or more.

The content of the ionic conductive agent is preferably 0.1 part by mass or more and 5.0 parts by mass or less, and more preferably 0.5 part by mass or more and 3.0 parts by mass or less, per 100 parts by mass of the rubber material.

Examples of the other additives include known materials that can be added to the elastic layer, such as a foaming agent, a foaming aid, a softener, a plasticizer, a curing agent, a vulcanizing agent, a vulcanization accelerator, an antioxidant, a surfactant, a coupling agent, and a filler (silica, calcium carbonate, and the like).

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

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

< method for producing conductive roller >

The conductive roller of the present embodiment is obtained by disposing a conductive foamed elastic layer on a support member. The method of disposing the conductive foamed elastic layer on the support member is not particularly limited, and examples thereof include: a method of preparing a cylindrical conductive foamed elastomer and inserting a support member into the cylindrical conductive foamed elastomer. The outer diameter of the conductive roller is adjusted by, for example, polishing the outer peripheral surface of the conductive foamed elastic layer disposed on the support member.

The method for manufacturing a conductive roller according to the present embodiment preferably includes: polishing the outer peripheral surface of the conductive foamed elastic layer disposed on the support member (referred to as a "polishing step"); and bringing the outer peripheral surface of the polished conductive foamed elastic layer into rotational contact with a heating roller (referred to as a "surface heat treatment step"). The convex portion formed on the outer peripheral surface of the conductive foamed elastic layer in the polishing step is flattened by the surface heat treatment step, and the amplitude of the convex-concave component in the range of the cycle of the outer peripheral surface of the conductive foamed elastic layer of 100 μm to 300 μm is suppressed.

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

The amplitude and the integral value St of the uneven component having a period 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.

The integral value St tends to decrease as the cell diameter of the conductive foamed elastic layer decreases. When the conductive roller is applied to a transfer roller, the foamed pores on the outer peripheral surface of the transfer roller are preferably somewhat large because the back surface of the recording medium (the surface on the side in contact with the transfer roller) may be contaminated if the foamed pores on the outer peripheral surface of the transfer roller are small. This phenomenon is presumed to be because toner remaining on the image holding body or the intermediate transfer body sometimes transfers to the transfer roller, and if the foaming pore diameter of the outer peripheral surface of the transfer roller is large to some extent, toner is contained in the open foaming pore, and therefore toner adhesion on the back surface of the recording medium on which the image is subsequently formed is suppressed.

From the above aspect, 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.

The cell diameter 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 the conductive foamed elastic layer.

The method of measuring the cell diameter of the conductive foamed elastic layer is as follows.

A cross section in the thickness direction of the conductive foamed elastic layer was produced using a razor. In the cross section, a total of 4 pieces were produced in parallel with the axial direction and at 90 ° intervals in the circumferential direction. An image was taken of the axial center of the cross section with a laser microscope (KEYENCE, VK-X200). The images were analyzed by Image analysis software (Media Cybernetics, Image-Pro Plus), 100 cells having a depth of 50 to 2050 μm and a length of 2000 μm were randomly selected, the average of 100 cells was measured, the average of 4 cells was calculated, and the average was defined as the cell diameter.

The integrated value St has the following tendency: the smaller the surface roughness of the grinding stone used in the grinding step, the smaller the rotation speed of the grinding stone, the smaller the rotation speed of the workpiece, and the smaller the traverse speed.

The grindstone may be, for example, a cylindrical metal grindstone having flower-socket ( mountain) -shaped protrusions on the surface thereof, and the protrusions are preferably in the shape of a pyramid such as a cone, a triangular pyramid, or a rectangular pyramid, and preferably have the same height.

When the above-mentioned grindstone is used, the rotation speed of the grindstone is preferably 5000rpm or more, the rotation speed of the workpiece is preferably 1000rpm or more, and the traverse speed is preferably 500mm/min to 2500 mm/min. rpm is an abbreviation for resolution per minute.

The integrated value St tends to decrease as the temperature in the surface heat treatment step increases. However, if the temperature in the surface heat treatment step is too high, the surface hardness is preferably not too high because the surface hardness increases when the outer peripheral surface of the conductive foamed elastic layer is melted and solidified.

From the above-described aspect, the temperature of the heating roller used in the surface heat treatment step is preferably 80 ℃ to 180 ℃, more preferably 100 ℃ to less than 180 ℃, and further preferably 120 ℃ to less than 180 ℃.

The rotation speed of the heating roller is preferably 2rpm to 60rpm, and the rotation speed of the workpiece is preferably 2rpm to 60 rpm.

< image Forming apparatus, transfer apparatus, Process Cartridge >

Fig. 4 is a schematic configuration diagram illustrating an image forming apparatus of a direct transfer system as an example of the image forming apparatus of the present embodiment.

The image forming apparatus 200 shown in fig. 4 includes: a photoreceptor 207 (an example of an image holder); 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 (an example of an electrostatic image forming unit) on the surface of the charged photoreceptor 207; a developing device 211 that develops the electrostatic image formed on the surface of the photoconductor 207 into a toner image with 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 photoconductor 207 to the surface of the recording medium (an example of a transfer unit, an example of a transfer device according to the present embodiment). The conductive roller of the present embodiment is applied as the transfer roller 212.

The image forming apparatus 200 shown in fig. 4 further includes: a cleaning device 213 for removing the toner remaining on the surface of the photoconductor 207; a charge removing device 214 for removing charge from the surface of the photoreceptor 207; the fixing device 215 fixes the toner image to a recording medium (an example of a fixing unit).

The charging roller 208 may be a contact charging method or a non-contact charging method. A voltage is applied from a power supply 209 to the charging roller 208.

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

The developing device 211 supplies toner to the photoreceptor 207. The developing device 211 causes a developer holder in a roll shape to come into contact with or close to the photoconductor 207, for example, and causes toner to adhere to the electrostatic image on the photoconductor 207, thereby forming a toner image.

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

As the fixing device 215, for example, a heating fixing device including a heating roller and a pressure roller that presses the heating roller is exemplified.

Examples of the cleaning device 213 include a device provided with a blade, a brush, a roller, and the like as a cleaning member.

The static elimination device 214 is a device that, for example, irradiates the surface of the photoreceptor 207 after transfer with light to remove the residual potential of the photoreceptor 207.

The photoreceptor 207 and the transfer roller 212 may be integrated into a single casing, for example, and may be a cartridge structure (process cartridge according to the present embodiment) that is detachably mounted to the image forming apparatus. The cartridge structure (the process cartridge of the present embodiment) may further include at least 1 selected from the group consisting of the charging roller 208, the exposure device 206, the developing device 211, and the cleaning device 213.

The image forming apparatus may be a tandem type image forming apparatus in which 1 image forming unit includes the photosensitive member 207, the charging roller 208, the exposure device 206, the developing device 211, the transfer roller 212, and the cleaning device 213, and 2 or more image forming units are mounted in a row.

Fig. 5 is a schematic configuration diagram illustrating an image forming apparatus of an intermediate transfer system as an example of the image forming apparatus of the present embodiment. The image forming apparatus shown in fig. 5 is a tandem image forming apparatus in which 4 image forming units are arranged in parallel.

In the image forming apparatus shown in fig. 5, a transfer unit that transfers 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 apparatus of the present embodiment) including an intermediate transfer body, a primary transfer unit, and a secondary transfer unit. The transfer unit may be a cartridge structure that is attached to and detached from the image forming apparatus.

The image forming apparatus shown in fig. 5 includes: a photoreceptor 1 (an example of an image holder); a charging roller 2 for charging the surface of the photoreceptor 1 (an example of a charging means); an exposure device 3 that forms an electrostatic image (an example of an electrostatic image forming unit) on the surface of the charged photoreceptor 1; a developing device 4 for developing an electrostatic image formed on the surface of the photoreceptor 1 into a toner image with 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 that transfers 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.

The image forming apparatus shown in fig. 5 further includes: a fixing device 28 for fixing the toner image to a recording medium (an example of a fixing unit); a photoreceptor cleaning device 6 for removing the toner remaining on the surface of the photoreceptor 1; and an intermediate transfer belt cleaning device 30 for removing the toner remaining on the surface of the intermediate transfer belt 20.

The image forming apparatus shown in fig. 5 includes 1 st to 4 th image forming units 10Y, 10M, 10C, and 10K of an electrophotographic system that output images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units 10Y, 10M, 10C, and 10K are arranged in parallel at intervals in the horizontal direction. The image forming units 10Y, 10M, 10C, and 10K may be process cartridges that are detachably mounted to the image forming apparatus, respectively.

Above the image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 extends through the image forming units. The intermediate transfer belt 20 is wound around a driving roller 22 and a supporting roller 24 which are in contact with the inner surface of the intermediate transfer belt 20, and runs in a direction from the 1 st image forming unit 10Y to the 4 th image forming unit 10K. The support roller 24 is biased in a direction away from the drive roller 22 by a spring or the like, not shown, and applies tension to the intermediate transfer belt 20 wound around the roller. 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 drive roller 22.

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

Since the 1 st to 4 th image forming units 10Y, 10M, 10C, and 10K have the same configuration and operation, the 1 st image forming unit 10Y will be described below as a representative example in the case of describing image forming units.

The 1 st image forming unit 10Y includes: 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 by a developer containing a toner; a primary transfer roller 5Y that transfers 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.

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

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

The developing device 4Y contains therein, 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. By passing the surface of the photoconductor 1Y through the developing device 4Y, the electrostatic image formed on the photoconductor 1Y is developed as a toner image.

The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20 and at a position facing the photoreceptor 1Y. A bias power supply (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 photoconductor 1Y to the intermediate transfer belt 20 by electrostatic force.

Toner images of the respective colors are sequentially transferred from the 1 st to 4 th image forming units 10Y, 10M, 10C, and 10K on the intermediate transfer belt 20 a plurality of times. The intermediate transfer belt 20 on which the toner images of 4 colors are transferred a plurality of times by the 1 st to 4 th image forming units moves to a secondary transfer unit constituted by a support roller 24 and a secondary transfer roller 26.

The secondary transfer roller 26 is a transfer roller that is in direct contact with the surface of the recording medium, and is disposed outside the intermediate transfer belt 20 at a position facing the support roller 24. A recording sheet P (an example of a recording medium) is fed by a feeding mechanism to a gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are in contact. 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.

The recording paper P to which the toner image is transferred is fed to a pressure contact portion (nip portion) of a fixing device 28 constituted by a pair of rollers, and the toner image is fixed to the recording paper P.

The toner and the 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 a copying machine or a printer of an electrophotographic system; an OHP sheet; and the like.

Examples

Hereinafter, embodiments of the present application will be described in detail by way of examples, but the embodiments of the present application are not limited to these examples at all.

< measuring method, evaluation method >

The measurement method and evaluation method applied to examples and comparative examples are as follows.

[ calculation of integral value St ]

The profile was imaged 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 imaging conditions in which the resolution per 1 pixel was 2 μm or less using an optical microscope (VHX-5000, KEYENCE corporation). The positions to be imaged are 20 points in total of 5 points in the axial direction (center, position 50mm from the center, position 100mm from the center) and 4 points in the circumferential direction (every 90 °).

The profile was subjected to image analysis using analysis software (ImageJ), and the concave-convex waveform was extracted.

In the interval of 1mm in the 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 the period of 100 μm to 300 μm, the amplitude (μm) of the period of 300 μm, and the amplitude (μm) of the period of 100 μm were obtained, and the average value at 20 points was calculated. Fast fourier transform and spectral analysis used analysis software (ImageJ).

[ measurement of cell diameter of foam ]

A cross section in the thickness direction of the conductive foamed elastic layer was produced using a razor. In the cross section, a total of 4 pieces were produced in parallel with the axial direction and at 90 ° intervals in the circumferential direction. An image was taken of the axial center of the cross section with a laser microscope (KEYENCE, VK-X200). The images were analyzed by Image analysis software (Media Cybernetics, Image-ProPlus), 100 cells having a depth of 50 to 2050 μm and a length of 2000 μm were randomly selected, the average of 100 cells was measured, the average of 4 cells was calculated, and the average was defined as the cell diameter.

[ evaluation of unevenness in concentration ]

The conductive roller was attached to a docupint CP400d (manufactured by fuji xerox corporation) as an image forming apparatus of a direct transfer method as a transfer roller, and 10 solid images with an image density of 100% were output onto a paper of a4 size under an environment of 10 ℃ temperature and 15% relative humidity. The entire sheet was observed and classified according to the following evaluation criteria.

A⁺(excellent): high image quality with no unevenness in density was observed.

A (∘): good image quality with uneven density is hardly observed.

B (Δ): the image quality was observed to be uneven in density but within the allowable range.

C (x): the image quality was observed to have an unacceptable density unevenness.

[ evaluation of dirt on the backside ]

Using the image forming apparatus, 180 halftone images with an image density of 50% were output onto a paper of a4 size in an environment with a temperature of 28 ℃ and a relative humidity of 85%, and then 20 solid images with an image density of 100% were output onto a paper of a4 size, and the process was repeated 25 times (total output of 5000 sheets). The worst dirt was classified as follows by observing the rear surfaces (surfaces on which no image was formed) of 4991 th to 5000 th (10 sheets in total).

A (∘): fouling was slightly observed but there was no practical problem.

B (Δ): fouling was observed, but within the allowed range.

C (x): unacceptable fouling was observed.

< example 1>

[ formation of conductive foamed elastic layer ]

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

CG102 manufactured by OSAKA SODA corporation: 60%, acrylonitrile butadiene rubber: JSR corporation manufactures N230 SV: 40 percent of 100 parts by mass

Carbon Black (55, manufactured by Asahi Carbon Co., Ltd.). 15 parts by mass

Vulcanizing agent (sulfur) (200 mesh, He, manufactured by chemical industries Co., Ltd.). 1 part by mass

Vulcanization accelerator (NOCCELER DM, available from Dai-Nei chemical industries Co., Ltd.). 1.5 parts by mass

Vulcanization accelerator (NOCCELER TET, available from Dai-Nei chemical industries Co., Ltd.). 1.0 part by mass

5 parts by mass of zinc oxide (Zinc white No. 1, manufactured by Zhengsui chemical industries Co., Ltd.)

10 parts by mass of calcium carbonate (WHITON SSB, manufactured by Baishi calcium Co., Ltd.)

Stearic acid (stearic acid S, manufactured by Kao corporation) ·.1 parts by mass

Foaming agent (NEOCELLBORN #5000, manufactured by Yonghe chemical industries Ltd.). The appropriate amount (amount of foamed cell diameter to a desired value)

The above materials were kneaded by an open mill to obtain a rubber kneaded material a. The rubber kneaded material A was extruded and molded into a cylindrical shape having an outer diameter of 19mm and an inner diameter of 5.6mm, and then heated at 160 ℃ for 30 minutes to be vulcanized and foamed, thereby obtaining a cylindrical conductive foamed elastomer. A shaft (made of SUS and having a diameter of 6mm) was inserted into a cylindrical conductive foamed elastomer, and the outer peripheral surface of the conductive foamed elastomer was polished by a rubber grinder equipped with a cylindrical metallic grindstone (No. F60) having a flower-socket-shaped protrusion under conditions of a grindstone rotation speed of 7000rpm, a workpiece rotation speed of 1500rpm, and a traverse speed of 1500 mm/min. Thus, a conductive roller 1 having an outer diameter of 16mm and a length of 224mm and provided with a conductive foamed elastic layer was obtained.

< example 2>

In the same manner as in example 1, the temperature was changed to 145 ℃ for 40 minutes, the rotational speed of the grindstone was changed to 6000rpm, and the traverse speed was changed to 2000mm/min, to obtain a conductive roller 2.

< example 3>

In the same manner as in example 1, the heating was changed to 135 ℃ for 50 minutes, the rotational speed of the grindstone was changed to 5000rpm, and the traversing speed was changed to 2500mm/min, to obtain a conductive roller 3.

< example 4>

Similarly to example 1, the temperature was changed to 185 ℃ for 20 minutes to obtain a conductive roller 4.

< example 5>

In the same manner as in example 1, except that the heating was changed to 175 ℃ for 20 minutes, the conductive roller 5 was obtained.

< comparative example 1>

In the same manner as in example 1, the temperature was changed to 130 ℃ for 60 minutes, the number of the grindstone was changed to F40, the rotational speed of the grindstone was changed to 4000rpm, and the traversing speed was changed to 3000mm/min, thereby obtaining a conductive roller 6.

< comparative example 2>

In the same manner as in comparative example 1, but the heating was changed to 190 ℃ for 15 minutes, to obtain a conductive roller 7.

[ Table 1]

< example 11>

[ formation of conductive foamed elastic layer ]

Rubber materials (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber: CG 102: 60, manufactured by OSAKA SODA Co., Ltd., acrylonitrile butadiene rubber: N230 SV: 40, manufactured by JSR Co., Ltd.). 100 parts by mass · · · · · · · · · · · · · · · · · · · · · · ·

Carbon Black (55, manufactured by Asahi Carbon Co., Ltd.). 15 parts by mass

Vulcanizing agent (sulfur) (200 mesh, He, manufactured by chemical industries Co., Ltd.). 1 part by mass

Vulcanization accelerator (NOCCELER DM, available from Dai-Nei chemical industries Co., Ltd.). 1.5 parts by mass

Vulcanization accelerator (NOCCELER TET, available from Dai-Nei chemical industries Co., Ltd.). 1.0 part by mass

5 parts by mass of zinc oxide (Zinc white No. 1, manufactured by Zhengsui chemical industries Co., Ltd.)

10 parts by mass of calcium carbonate (WHITON SSB, manufactured by Baishi calcium Co., Ltd.)

Stearic acid (stearic acid S, manufactured by Kao corporation) ·.1 parts by mass

Foaming agent (NEOCELLBORN #5000, manufactured by Yonghe chemical industry Co.). 5 parts by mass

The above materials were kneaded by an open mill to obtain a rubber kneaded material B. The rubber kneaded material B was extruded and molded into a cylindrical shape having an outer diameter of 19mm and an inner diameter of 5.6mm, and then heated at 160 ℃ for 30 minutes to be vulcanized and foamed, thereby obtaining a cylindrical conductive foamed elastomer. A shaft (made of SUS and having a diameter of 6mm) was inserted into a cylindrical conductive foamed elastic body, and the outer peripheral surface of the conductive foamed elastic body was polished with a rubber grinder equipped with a cylindrical metallic grindstone (No. F60) having a flower-socket-shaped protrusion under conditions of a grindstone rotation speed of 7000rpm, a workpiece rotation speed of 1500rpm, and a traverse speed of 1500mm/min, so that the outer diameter of the conductive foamed elastic layer was 16 mm.

Then, a metal roll (made of SUS, diameter 32mm) adjusted to 120 ℃ was allowed to be immersed in 0.8mm on the outer peripheral surface of the conductive foamed elastomer after polishing, and was rotated in contact for 90 seconds under conditions of a metal roll rotation speed of 10rpm and a workpiece rotation speed of 10 rpm.

Thus, a conductive roller 11 having an outer diameter of 16mm and a length of 224mm and provided with a conductive foamed elastic layer was obtained.

< example 12>

Similarly to example 11, the conductive roller 12 was obtained by changing the rotational speed of the grindstone to 6000rpm and the traverse speed to 2000 mm/min.

< example 13>

Similarly to example 11, the conductive roller 13 was obtained by changing the grindstone rotation speed to 5000rpm and the traverse speed to 2500 mm/min.

< example 14>

Similarly to example 11, the temperature of the metal roller was changed to 80 ℃.

< example 15>

Similarly to example 11, the temperature of the metal roller was changed to 160 ℃.

< example 16>

Similarly to example 11, the temperature of the metal roller was changed to 180 ℃.

< example 17>

Similarly to example 11, the conductive roller 17 was obtained by changing the grindstone to number F40, changing the grindstone rotation speed to 4000rpm, changing the traverse speed to 3000mm/min, and changing the metal roller temperature to 80 ℃.

< comparative example 11>

A conductive roller 18 was obtained in the same manner as in example 17 except that the temperature of the metal roller was changed to 60 ℃.

< comparative example 12>

Similarly to example 17, but without performing surface heat treatment using a metal roller, a conductive roller 19 was obtained.

[ Table 2]