JP2004021019A - Conductive roll, electrification roll, transfer roll, and cleaning roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roll, an electrification roll, and a transfer roll which prevent an image defect due to contamination resulting from sticking of foreign matters on a surface, minimizes an image defect when the foreign matters stick, and also prevents a photoreceptor surface from being filmed with the foreign matters. <P>SOLUTION: The conductive roll has at least two or more conductive layers including a surface layer and comes into contact with a body to be electrified in a state a voltage is applied thereto so as to electrify the body to be electrified, and is characterized in that the dynamic superfine hardness of the conductive roll is ≤0.3 and the dynamic superfine hardness of a macromolecular material forming the surface layer is ≥1.0. <P>COPYRIGHT: (C)2004,JPO

Description

【００９６】
表１の実施例に示すように、本発明の導電性ロールは、帯電ロールとして実機連続印字に用いた場合でも、印字後にロール表面にトナー等の異物付着による汚れが見られず、画質不良も発生させることがなかった。一方、比較例の帯電ロールはＲａ、表面層体積抵抗値を同等としても、異物付着、画質欠陥を防止することができないことがわかった。
【００９７】
【発明の効果】
本発明によれば、例えば異物が帯電ロールと感光体とのニップ部に進入することにより発生する帯電ロールの汚染、局所的なニップ不良、感光体のフィルミングに起因する画像欠陥を防止した帯電ロールなど、表面への異物付着を効率的に回避できる導電性ロールを提供することが可能となる。
【図面の簡単な説明】
【図１】粗大な異物が付着した帯電ロールが感光体に接触したときの模式断面図である。
【図２】粗大な異物が付着した本発明の帯電ロールが感光体に接触したときの模式断面図である。
【図３】異物と本発明の帯電ロールとの接触部分の拡大断面図である。
【図４】本発明の導電性ロールの一例を示す模式断面図である。
【図５】本発明の導電性ロールの他の一例を示す模式断面図である。
【符号の説明】
１　導電性支持体
２　発泡弾性層
３、５　無発泡弾性層
４、６　表面層
１１　帯電ロール
１２　感光体
１３　粗大な異物
１４　ニップ不良領域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a conductive roll such as a charging roll used in an electrostatic recording process in an image forming apparatus such as an electrophotographic copying machine and a printer.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in an electrophotographic image forming apparatus, a charging roll is frequently used as a member for uniformly charging the surface of a photosensitive member as a member to be charged. The charging roll contacts the photoreceptor in a state where a voltage is applied, and discharges in a minute gap between the photoreceptor and charges the photoreceptor surface. The resistance and shape of the charging roll are strictly controlled in order to uniformly charge the photoconductor.
[0003]
In an electrophotographic image forming apparatus using a charging roll, foreign matters such as transfer residual toner, carrier, and paper powder adhering to the surface of the photoreceptor enter the nip portion between the charging roll and the photoreceptor. Adhere to the surface of the charging roll and contaminate the charging roll. When foreign matter adheres to the surface of the charging roll, the foreign matter adhered portion has a high resistance, causing poor charging of the photoreceptor or causing abnormal discharge at the foreign matter adhered portion. It causes image defects such as color points.
[0004]
The charging roll in which the contamination due to the adhesion of the foreign matter has been continued for a long period of time has uneven resistance even in the entire roll, so that the charging unevenness of the photoreceptor is likely to occur. Image quality defects such as white spots and color spots.
[0005]
In particular, in recent years, in the electrophotographic image forming apparatus, higher image quality and longer life have been further required, and uneven charging, which could not be detected conventionally, causes image quality defects. In addition, in order to reduce the cost of the image forming apparatus, when a method is adopted in which charging is performed only by applying a DC voltage, an apparatus that superimposes AC on a conventional DC and applies a voltage to achieve uniform charging is used. In comparison, image defects due to adhesion of foreign matter become more remarkable.
[0006]
In order to prevent the image quality defect due to the adhesion of the foreign matter, conventionally, a method of reducing the adhesion of the foreign matter to the charging roll and a method of mounting a member for removing the adhered foreign matter have been tried.
[0007]
As a method for reducing the adhesion of foreign matter to the charging roll, for example, a surface layer is formed of a polymer material having a dense molecular structure and excellent releasability, as represented by a so-called resin, and generally has a tacky property. Attempts have been made to reduce the adhesion of foreign matter to the surface of a high elastic roll (charging roll) (Japanese Patent Laid-Open No. 1-204081).
[0008]
Further, as a method of mounting the member for removing the adhered foreign matter, a member such as a roll or a pad (Japanese Patent Application Laid-Open No. 2-301777) or a web (Japanese Patent Application Laid-Open No. 2-301779) is brought into contact with the charging roll. Attempts have been made to forcibly remove foreign matter adhering to the surface of the charging roll.
[0009]
However, in the method in which the dense polymer material is used for the surface layer, such a polymer material is generally hard, so that a small amount of foreign matter causes poor charging or accelerates the consumption of the photoconductor. Sometimes.
[0010]
Further, it has been found that even in the method of mounting the member for removing the attached foreign matter, the residual toner on the surface of the charging member cannot be sufficiently removed, and the foreign matter gradually accumulates.
[0011]
Further, the adhesion of the foreign matter is a serious problem such as reducing the durability not only for the charging roller but also for a member (transfer roll, cleaning roll, etc.) arranged around the photosensitive member and in contact with the photosensitive member. Rolls that can be fundamentally avoided or reduced, or rolls whose performance does not decrease even when foreign matter adheres, have not yet been developed.
[0012]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems of the conventional technology.
That is, the present invention prevents the occurrence of image defects due to contamination due to the attachment of foreign matter to the surface, minimizes image defects when foreign matter is attached, and further reduces filming of foreign matter on the photoreceptor surface. It is an object of the present invention to provide a conductive roll, a charging roll, a transfer roll, and a cleaning roll that can prevent the occurrence of a problem.
[0013]
[Means for Solving the Problems]
The above object is achieved by the present invention described below. That is, the present invention
<1> A conductive roll which has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged. A conductive roll having a dynamic ultra-micro hardness of 0.3 or less and a dynamic ultra-micro hardness of a polymer material constituting the surface layer is 1.0 or more.
[0014]
<2> The conductive roll according to <1>, wherein an arithmetic average roughness (Ra) of the conductive roll surface is 1.0 μm or less.
[0015]
<3> The volume resistivity of the surface layer is 1 × 10 ¹² <1> The conductive roll according to <1>, wherein the resistance is Ω · cm or less.
[0016]
<4> The volume resistivity of the surface layer is 1 × 10 ¹² <2> The conductive roll according to <2>, wherein the resistance is Ω · cm or less.
[0017]
<5> A conductive roll that has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged. A charging roll characterized by comprising a conductive roll having a dynamic ultra-micro hardness of 0.3 or less, and a dynamic ultra-micro hardness of a polymer material constituting the surface layer of 1.0 or more. is there.
[0018]
<6> The charging roll according to <5>, wherein an arithmetic average roughness (Ra) of the charging roll surface is 1.0 μm or less.
[0019]
<7> The volume resistivity of the surface layer is 1 × 10 ¹² The charging roll according to claim 5, wherein the charging roll is equal to or less than Ω · cm.
[0020]
<8> The volume resistivity of the surface layer is 1 × 10 ¹² <6> The charging roll according to <6>, wherein the charging roll has a resistivity of Ω · cm or less.
[0021]
<9> A conductive roll that has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged. A transfer roll comprising a conductive roll having a dynamic ultra-micro hardness of 0.3 or less, and a dynamic ultra-micro hardness of a polymer material constituting the surface layer of 1.0 or more. is there.
[0022]
<10> The transfer roll according to <9>, wherein an arithmetic mean roughness (Ra) of the surface of the charging roll is 1.0 μm or less.
[0023]
<11> The volume resistivity of the surface layer is 1 × 10 ¹² <9> The transfer roll according to <9>, wherein the transfer roll has a resistivity of Ω · cm or less.
[0024]
<12> The volume resistivity of the surface layer is 1 × 10 ¹² <10> The transfer roll according to <10>, wherein the transfer roll has a resistivity of Ω · cm or less.
[0025]
<13> A conductive roll that has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged. A cleaning roll comprising a conductive roll having a dynamic ultra-micro hardness of 0.3 or less and a dynamic ultra-micro hardness of a polymer material constituting the surface layer of 1.0 or more. is there.
[0026]
<14> The cleaning roll according to <13>, wherein an arithmetic average roughness (Ra) of the charging roll surface is 1.0 μm or less.
[0027]
<15> The surface layer has a volume resistivity of 1 × 10 ¹² <13> The cleaning roll according to <13>, wherein the cleaning roll has a resistivity of Ω · cm or less.
[0028]
<16> The volume resistivity of the surface layer is 1 × 10 ¹² <14> The cleaning roll according to <14>, which has a Ω · cm or less.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The conductive roll of the present invention is a conductive roll that has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged, A dynamic ultra-micro hardness of the conductive roll is 0.3 or less, and a dynamic ultra-micro hardness of a polymer material constituting the surface layer is 1.0 or more.
[0030]
The conductive roll of the present invention is not particularly limited as long as it is a roll having conductivity of the above configuration.For example, a conductive elastic layer and a surface layer are formed on a metal base material surface, Rolls, transfer rolls, cleaning rolls and the like can be mentioned.
[0031]
The object to be charged is not limited to the photoreceptor, but includes all those that are charged (including the change in polarity) by contacting the conductive roll of the present invention, such as recording paper and toner.
[0032]
First, a charging roll will be described as an example of the conductive roll of the present invention.
As described above, when the contact-type charging roll is used for a long period of time, since the charging roll is in contact with the photoreceptor, transfer residual toner on the photoreceptor surface, foreign substances such as carrier and paper powder adhere to the charging roll, Contaminates the charging roll. The contaminated charging roll causes uneven charging of the photoreceptor, and causes image quality defects such as uneven density and white spots and color spots over the entire image. Furthermore, in the nip portion between the charging roll and the photoconductor, the foreign matter that has entered the nip portion is pressed against the photoconductor by the charging roll, so that the surface of the photoconductor is scratched or the foreign material is buried in the photoconductor. This causes filming.
[0033]
In the foreign matter that enters the nip portion between the charging roll and the photoreceptor, transfer residual toner having a particle diameter of several μm, a carrier, and paper powder are gathered, and the size is in the range of tens to hundreds of μm. Some coarse foreign substances have become aggregates.
[0034]
FIG. 1 is a schematic cross-sectional view when the charging roll to which the coarse foreign matter has adhered comes into contact with the photoconductor. As shown in FIG. 1, when the coarse foreign matter 13 adheres to the surface of the charging roll 11, the poor contact of the charging roll 11 with the photoconductor 12 is caused not only by the adhering portion but also by the surrounding area. Also occurs in the portion 14 of FIG. For this reason, the poorly charged area of the photoreceptor greatly spreads around the foreign matter 13 and causes image defects such as a coarse white point and a coarse color point.
[0035]
Although the number of coarse foreign substances 13 is smaller than that of fine foreign substances, in recent years in which high image quality is required, poor charging due to poor contact between the charging roll 11 and the photoconductor 12 due to the large foreign substances 13 is large. It becomes a problem.
[0036]
The present inventors diligently studied the above problem, and found that the charging roll 11 has at least two or more conductive layers including a surface layer, and the dynamic ultra-micro hardness of the charging roll 11 is 0.3 or less. Further, by setting the dynamic ultra-micro hardness of the polymer material constituting the surface layer to 1.0 or more, it is possible to prevent image defects due to adhesion of foreign matter and filming of foreign matter on the surface of the photoconductor 12. I found it.
[0037]
The dynamic ultra-micro hardness (hereinafter sometimes simply referred to as “DH”) is determined by the test load P (mN) and the indentation depth D when the indenter enters the sample at a constant indentation speed (mN / s). (Μm) is the hardness calculated from equation (1).
DH = α × P / D ² ... (1)
In the above equation (1), α represents a constant depending on the shape of the indenter.
[0038]
The measurement of the dynamic ultra-micro hardness was performed by a dynamic ultra-micro hardness meter DUH-W201S (manufactured by Shimadzu Corporation). The dynamic ultra-micro hardness was determined by measuring a soft material by injecting a triangular pyramid indenter (vertical angle: 115 °, α: 3.8584) into a charging roll at a pushing speed of 0.14 mN / s and a test load of 0.5 mN. It was determined by measuring the indentation depth D at the time.
[0039]
The principle which can prevent the attachment of foreign matter by the charging roll of the present invention, image defects due to coarse foreign matter, and filming of foreign matter on the photoreceptor surface can be considered as follows.
FIG. 2 is a schematic cross-sectional view when the charging roll of the present invention, to which coarse foreign matter has adhered, comes into contact with the photoreceptor similarly to FIG. FIG. 3 is an enlarged cross-sectional view of the contact portion between the charging roll and the coarse foreign matter at this time.
[0040]
As shown in FIG. 2, in the nip portion between the charging roll 11 and the photoconductor 12 of the present invention, macroscopically, the charging roll 11 is in contact with the photoconductor 12 so as to enclose coarse foreign substances 13, The poor contact area 14 in FIG. 1 is considerably reduced. Further, in this case, the contact area between the charging roll 11 and the coarse foreign matter 13 is reduced microscopically as shown in FIG. For this reason, even if the coarse foreign matter 13 adheres to the surface, the defective charging area of the photoconductor 12 can be minimized, and the coarse foreign matter 13 does not adhere to the surface of the charging roll 11. In addition, the structure is such that coarse foreign substances 13 are not easily maintained on the surface of the charging roll 11 continuously.
[0041]
The provision of the charging roll 11 satisfying the above principle has been made possible by controlling the dynamic ultra-micro hardness.
The dynamic ultra-micro hardness is a hardness in a process of pushing an indenter, and includes characteristics of plastic deformation and elastic deformation of a sample. In addition, the dynamic ultra-micro hardness can measure the hardness of a micro-region in both the area and the depth, and the measured value reflects the material characteristics composed of a plurality of layers. Therefore, it has become possible to provide a charging roll capable of preventing adhesion of foreign matter, image defects due to coarse foreign matter, and filming of foreign matter on the photoreceptor surface by controlling the dynamic ultra-fine hardness.
[0042]
The dynamic ultra-micro hardness of the charging roll 11 is such that when the smaller one contacts the photoreceptor 12, the surface of the charging roll 11 flexibly follows the foreign matter as shown in FIG. It is unlikely to cause adhesion due to burial of foreign matter due to the destruction of the surface layer and local nip defects. For this reason, in the present invention, it is possible to prevent foreign matter from adhering to the charging roll 11 due to burial, and to prevent local foreign matter charging when a coarse foreign matter 13 enters the nip portion between the charging roll 11 and the photoconductor 12. In order to minimize image defects such as coarse white spots and color spots, the dynamic ultra-micro hardness of the charging roll 11 needs to be 0.3 or less.
[0043]
If the dynamic ultra-micro hardness of the charging roll 11 is larger than 0.3, the foreign matter destroys the surface layer of the charging roll, thereby increasing the adhesion of the foreign matter or causing a local nip defect due to the adhesion of the coarse foreign matter. Image defects such as coarse white spots and color spots are likely to occur, and filming of foreign substances on the surface of the photoconductor frequently occurs.
Preferably, the dynamic ultra-micro hardness of the charging roll 11 is 0.2 or less.
[0044]
On the other hand, the larger the dynamic ultra-micro hardness of the polymer material constituting the surface layer of the charging roll 11 is, the smaller the micro contact portion with the foreign matter becomes as shown in FIG. Adhesion of foreign substances to the surface can be reduced. In addition, by increasing the dynamic ultra-micro hardness of the surface layer, it is possible to quickly recover the shape of the surface of the charging roll 11 deformed with respect to the foreign matter in a minute area, and immediately discharge the foreign matter. It is possible to do.
[0045]
In the present invention, in order to prevent foreign matter from adhering to the surface of the charging roll 11, it is necessary to set the dynamic ultra-micro hardness of the polymer material constituting the surface layer to 1.0 or more. If the dynamic ultra-micro hardness is less than 1.0, the foreign matter can be efficiently released because the contact area with the foreign matter becomes microscopically large or the deformation is not sufficiently recovered by the foreign matter. Can not.
In addition, the dynamic ultra-micro hardness of the polymer material constituting the surface layer is preferably 2.0 or more.
[0046]
The dynamic ultra-micro hardness of the charging roll 11 (conductive roll) is determined as the roll itself, and the dynamic ultra-micro hardness of the polymer material forming the surface layer is determined by the thickness of the polymer material. As a sheet having a thickness of 100 μm or more, it was measured by the dynamic ultra-micro hardness tester.
[0047]
The arithmetic average roughness Ra of the surface of the charging roll 11 of the present invention is preferably 1.0 μm or less, more preferably 0.5 μm or less. If the Ra exceeds 1.0 μm, the foreign matter is likely to be buried in the concave portion of the roll surface, and it may not be possible to reduce the adhesion of the foreign matter.
[0048]
The Ra was measured using a surface roughness meter “surfcom1400A” (manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with JIS B 0601-1994 in the axial direction of the roll, measuring length 5.0 mm, cutoff value 0.8 mm, measuring speed 0.30 mm / It was measured under the condition of sec.
[0049]
Further, the volume resistivity of the surface layer is 1 × 10 ¹² Ω · cm or less, preferably 1 × 10 ¹⁰ More preferably, it is Ω · cm or less. Volume resistivity of surface layer is 1 × 10 ¹² If it exceeds Ω · cm, electrostatic adhesion between the surface of the charging roll 11 and the foreign matter becomes strong, so that it may not be possible to reduce the adhesion of the foreign matter.
[0050]
The volume resistance value is determined by measuring the surface layer composition in a sheet form, using a measuring jig (R12702A / B resitivity chamber: manufactured by Advantest) and a high resistance measuring instrument (R8340A digital high resistance / microammeter: manufactured by Advantest). The voltage adjusted so that the electric field (applied voltage / composition sheet thickness) becomes 1000 V / cm was calculated from the current value after 10 seconds of application, using the following equation (2).
Volume resistivity (Ω · cm) = (19.63 × applied voltage (V)) / (current value (A)
× composition sheet thickness (cm)) Formula (2)
The measurement of the volume resistivity was performed in a 22 ° C., 55% RH environment.
[0051]
The layer configuration of the charging roll of the present invention is not particularly limited as long as it has at least two or more conductive layers including a surface layer on the surface of the conductive support, and is composed of three or four layers. Is also good. At least one layer of the conductive layer is made of conductive elastic material so that the charging roll is pressed against the surface of the member to be charged with an appropriate pressure to form a nip with the member to be charged and uniformly charge the surface of the member to be charged. It is preferably a layer.
[0052]
The conductive support functions as an electrode and a support member of the charging roll, and is, for example, a metal or alloy such as aluminum, a copper alloy, or stainless steel; iron plated with chromium, nickel, or the like; It is made of a conductive material such as resin.
[0053]
The conductive elastic layer is formed, for example, by dispersing a conductive agent in a rubber material. Rubber materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, urethane rubber, silicone rubber, fluoro rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, ethylene-propylene -Diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber, natural rubber, and the like, and blended rubbers thereof. Among them, silicone rubber, epichlorohydrin rubber, and acrylonitrile-butadiene copolymer rubber are preferably used. These rubber materials may be foamed or non-foamed.
[0054]
As the conductive agent, an electronic conductive agent or an ionic conductive agent is used. Examples of the electronic conductive agent include carbon black such as Ketjen black and acetylene black; pyrolytic carbon and graphite; various conductive metals or alloys such as aluminum, copper, nickel and stainless steel; tin oxide, indium oxide and titanium oxide. And fine powders such as various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution; Examples of the ion conductive agent include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium, and perchlorates and chlorates of alkaline earth metals. There may be mentioned;
[0055]
These conductive agents may be used alone or in combination of two or more. The amount of addition is not particularly limited, but in the case of the above-mentioned electronic conductive agent, it is preferably in the range of 1 to 30 parts by mass, and more preferably in the range of 10 to 20 parts by mass with respect to 100 parts by mass of the rubber material. More preferably, there is. On the other hand, in the case of the ionic conductive agent, the amount is preferably 0.1 to 5.0 parts by mass, and more preferably 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the rubber material. Is more preferred.
Thereby, the volume resistance value of the conductive elastic layer is 1 × 10 ⁶ ~ 1 × 10 ¹⁰ It is preferable to adjust it to the range of Ω · cm.
Further, the hardness of the conductive elastic layer is preferably 0.1 or less in terms of the dynamic ultra-micro hardness of the sheet, and 0.05 or less in order to make the dynamic ultra-micro hardness of the charging roll an appropriate range. Is more preferable.
[0056]
As described above, the polymer material constituting the surface layer is not particularly limited as long as the dynamic ultra-fine hardness is 1.0 or more, but polyamide, polyurethane, polyvinylidene fluoride, tetrafluoroethylene copolymer , Polyester, polyimide, silicone resin, acrylic resin, polyvinyl butyral, ethylene tetrafluoroethylene copolymer, melamine resin, fluoro rubber, epoxy resin, polycarbonate, polyvinyl alcohol, cellulose, polyvinylidene chloride, polyvinyl chloride, polyethylene, ethylene acetate And vinyl copolymers.
Of these, tetrafluoroethylene copolymer, polyamide, polyvinylidene fluoride, polyimide and the like are preferably used from the viewpoint of releasability from the toner.
[0057]
The above-mentioned polymer materials may be used alone or as a mixture of two or more. Further, the number average molecular weight of the polymer material is preferably in a range of 1,000 to 100,000, and more preferably in a range of 5,000 to 20,000.
[0058]
The surface layer is formed as a composition by mixing the above-described polymer material with the conductive agent and various fine particles used for the conductive elastic layer. As the fine particles, metal oxides such as silicon oxide, aluminum oxide and barium titanate and composite metal oxides, tetrafluoroethylene, and polymer fine powders such as vinylidene fluoride may be used alone or in combination. However, the present invention is not limited to this.
[0059]
The characteristics of the surface layer also affect the dynamic ultra-micro hardness of the charging roll described above. Therefore, in order to make the dynamic hardness of the charging roll 0.3 or less, the amount of the conductive material and the fine particles to be blended as the surface layer composition is in the range of 20 to 120% by mass of the entire surface layer composition. And more preferably in the range of 40 to 100% by mass.
The thickness of the surface layer is preferably 20 μm or less, more preferably 5 μm or less.
[0060]
In addition to the conductive elastic layer and the surface layer, for example, a resistance adjusting layer can be provided between these layers. The resistance adjusting layer is made of a resin material such as urethane rubber, epichlorohydrin-ethylene oxide copolymer rubber, ethylene-propylene-diene rubber, thermoplastic elastomer, elastomer, rubber, or the like, used alone or as a mixture. It is formed by compounding the conductive agent used for the layer.
[0061]
As the surface layer, for example, the surface of the conductive elastic layer is subjected to UV irradiation treatment, heat treatment, chemical treatment such as application of a coupling agent, or the like to form a layer whose physical properties are changed from those of the inner layer to form a surface layer. You can also.
[0062]
The charging roll as the conductive roll of the present invention has been described above. However, the conductive roll of the present invention is also preferably used as a transfer roll in an electrophotographic image forming apparatus.
The transfer roll is used as a transfer member for transferring the toner image formed on the photoreceptor surface to paper or the like, but the transfer roll is also used on the photoreceptor or paper to which the residual toner adheres, similarly to the charging roll. Foreign matter easily adheres because of contact. Therefore, by using the conductive roll of the present invention as the transfer roll, it is possible to prevent transfer failure due to the adhesion of foreign matter to the surface and toner filming on the photosensitive member.
[0063]
Further, the conductive roll of the present invention is also preferably used as a cleaning roll in an electrophotographic image forming apparatus.
The cleaning roll is used as a cleaning member for cleaning residual toner adhered to the surface of the photoreceptor after transfer.If toner easily adheres to the cleaning roll, the cleaned toner continues to accumulate on the roll surface, Eventually, it causes cleaning failure and toner filming on the photosensitive member. Therefore, if the conductive roll of the present invention is used as a cleaning roll, the above problem can be solved.
[0064]
Further, the conductive roll of the present invention is not limited to the charging roll, the transfer roll, and the cleaning roll, and is used in a state where a voltage is applied, and it is necessary to avoid adhesion of foreign matter to the roll surface. It can be preferably used for various applications.
[0065]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.
<Example 1>
(Production of conductive roll)
-Molding of conductive elastic layer-
The following mixture was kneaded with an open roll, and coated on the surface of a conductive support made of SUS304 having a diameter of 8 mm so as to have a thickness of 1 mm.
[0066]
-Rubber material (EPDM): 100 parts by mass of EP65 (manufactured by JSR)
-Conductive agent (carbon black): 40 parts by mass Asahi Thermal (Asahi Carbon) and 10 parts by mass Ketjen Black EC (Lion)
・ Blowing agent: 8 parts by mass of vinyl hole AC # 3 (manufactured by Eiwa Chemical Co., Ltd.)
-Vulcanizing agent: 1 part by mass of sulfur (200 mesh manufactured by Tsurumi Chemical Industry Co., Ltd.)
Vulcanization accelerator: 2.0 parts by mass of Noxeller DM (Ouchi Shinko Chemical Co., Ltd.) and 0.5 parts by mass of Noxeller TT (Ouchi Shinko Chemical Co., Ltd.)
[0067]
Next, the following mixture kneaded with an open roll was coated on the surface thereof in a cylindrical shape so as to have a thickness of 0.5 mm, placed in a cylindrical mold having an inner diameter of 14.0 mm, and vulcanized at 170 ° C. for 30 minutes. By foaming, a cylindrical conductive elastic layer A in which a rubber non-foamed layer was formed on the surface of the elastic layer of the foam (EPDM) was obtained.
The dynamic ultra-micro hardness of the conductive elastic layer was 0.02.
[0068]
Rubber material (epichlorohydrin-ethylene oxide copolymer rubber): 100 parts by mass of Gechron 3106 (manufactured by Zeon Corporation)
-Conductive agent (carbon black): 20 parts by mass Asahi Thermal (Asahi Carbon) and 8 parts by mass Ketjen Black EC (Lion)
-Vulcanizing agent: 1 part by mass of sulfur (200 mesh manufactured by Tsurumi Chemical Industry Co., Ltd.)
Vulcanization accelerator: 2.0 parts by mass of Noxeller DM (Ouchi Shinko Chemical Co., Ltd.) and 1.0 parts by mass of Noxeller TT (Ouchi Shinko Chemical Co., Ltd.)
[0069]
-Formation of surface layer-
The following mixture was dispersed in a bead mill, and the obtained dispersion A was applied by dip coating on the surface of the conductive elastic layer A, and then dried by heating at 140 ° C. for 15 minutes to form a surface layer having a thickness of 3 μm. .
The above surface layer was separately prepared as a sheet, and its volume resistance was measured. ¹⁰ Ω · cm.
[0070]
・ Polymer material (copolymer nylon): 100 parts by mass of Alamine CM8000 (manufactured by Toray Industries, dynamic ultra-micro hardness: 1.4)
-Conductive agent (antimony-doped tin oxide): SN-100P (manufactured by Ishihara Sangyo) 40 parts by mass
-Solvent: 500 parts by mass of methanol and 240 parts by mass of butanol
[0071]
FIG. 4 is a cross-sectional view of the produced conductive roll 1. As shown in FIG. 4, the conductive roll 1 has a foamed elastic layer 2 having a thickness of about 2.5 mm around the conductive support 1 and the periphery thereof. And a non-foamed elastic layer 3 having a thickness of about 0.5 mm, and a surface layer 4 formed therearound.
[0072]
(Evaluation of conductive roll)
-Measurement of dynamic ultra-micro hardness-
The dynamic ultra-micro hardness of the conductive roll 1 was measured by the method described above.
[0073]
-Measurement of arithmetic mean roughness Ra-
The arithmetic average roughness Ra of the conductive roll 1 was measured by the method described above.
[0074]
−Evaluation of actual machine−
The conductive roll 1 was attached as a charging roll to a color copying machine DocuColor 2220 (manufactured by Fuji Xerox Co., Ltd.), and a 50,000 sheet A4 paper print test (after printing 25,000 sheets in an environment of 10 ° C. and 15% RH, printing at 28 ° C.) 25,000 sheets were printed under an 85% RH environment. If a major problem occurred on the way, printing was stopped at that point.
[0075]
The image quality was evaluated based on the following criteria based on the presence or absence of white spots, density unevenness, and the like in the halftone image for the image after running 50,000 sheets.
：: No defect such as black spot, white spot, density unevenness, etc.
Δ: Black spots and white spots of 10 or less
×: Black spots, white spots, density unevenness occurred on the entire surface
[0076]
Roll dirt evaluation was performed on the rolls after running 50,000 sheets by visual evaluation according to the following criteria.
○: Almost no foreign matter adhered or slight foreign matter adhered
Δ: Foreign matter adhered to the entire surface (thin whiteness)
×: sticking of foreign matter (whitening)
The results are summarized in Table 1.
[0077]
<Example 2>
A conductive elastic layer A was molded in the same manner as in Example 1. Next, the following mixture was dispersed in a bead mill, and the obtained dispersion B was applied by dip coating on the surface of the conductive elastic layer A, and then dried by heating at 160 ° C. for 30 minutes to form a surface layer having a thickness of 1 μm. .
The surface layer was separately prepared as a sheet, and the volume resistance was measured. ⁸ Ω · cm.
[0078]
-Polymer material (fluorine varnish): 100 parts by mass of Zeffle GK-500 (manufactured by Daikin Industries, Ltd., dynamic ultra-fine hardness: 3.6)
-Conductive agent (antimony-doped tin oxide): SN-100P (manufactured by Ishihara Sangyo) 40 parts by mass
Curing agent: Coronate 2507 (manufactured by Nippon Polyurethane Industry Co., Ltd.) 40 parts by mass
Solvent: 200 parts by mass of 2-butanone and 350 parts by mass of butyl acetate
[0079]
The produced conductive roll 2 was evaluated in the same manner as in Example 1. The results are summarized in Table 1.
[0080]
<Example 3>
The following mixture was kneaded with an open roll, coated on the surface of a conductive support made of SUS304 having a diameter of 8 mm in a cylindrical shape so as to have a thickness of 3 mm, and placed in a cylindrical mold having an inner diameter of 14.0 mm. Vulcanization was performed at 30 ° C. for 30 minutes to obtain a cylindrical conductive elastic layer B.
The dynamic ultra-micro hardness of the conductive elastic layer was 0.02.
[0081]
Rubber material (epichlorohydrin-ethylene oxyside copolymer rubber): 100 parts by mass of Gechron 3106 (manufactured by Zeon Corporation)
Conductive agent (carbon black): 25 parts by mass Asahi Thermal (Asahi Carbon) and 8 parts by mass Ketjen Black EC (Lion)
-Vulcanizing agent: 1 part by mass of sulfur (200 mesh manufactured by Tsurumi Chemical Industry Co., Ltd.)
Vulcanization accelerator: 2.0 parts by mass of Noxeller DM (manufactured by Ouchi Shinko Chemical Co., Ltd.), 0.5 parts by mass of Noxeller TT (manufactured by Ouchi Shinko Chemical Co., Ltd.)
[0082]
A dispersion A prepared in the same manner as in Example 1 was dip-coated on the surface of the conductive elastic layer B, and dried by heating at 140 ° C. for 15 minutes to form a surface layer having a thickness of 3 μm.
[0083]
FIG. 5 is a cross-sectional view of the prepared conductive roll 3. As shown in FIG. 5, the conductive roll 3 has a non-foamed elastic layer 5 having a thickness of about 3 mm It has a structure in which the surface layer 6 is formed.
The conductive roll 3 was evaluated in the same manner as in Example 1. The results are summarized in Table 1.
[0084]
<Example 4>
A conductive elastic layer B was molded in the same manner as in Example 3. The dispersion B prepared in the same manner as in Example 2 was dip-coated on the surface of the conductive elastic layer B to form a surface layer having a thickness of 1 μm.
[0085]
The produced conductive roll 4 was evaluated in the same manner as in Example 1. The results are summarized in Table 1.
[0086]
<Example 5>
A conductive elastic layer A was molded in the same manner as in Example 1. Next, the following mixture was dispersed in a bead mill, and the obtained dispersion C was applied by dip coating on the surface of the conductive elastic layer A, and then dried by heating at 150 ° C. for 30 minutes to form a surface layer having a thickness of 1 μm. .
The above surface layer was separately prepared as a sheet, and its volume resistance was measured. ¹¹ Ω · cm.
[0087]
-Polymer material (polyvinylidene fluoride): 100 parts by mass of KF polymer # 2300 (Kureha Chemical Industry Co., Ltd., dynamic ultra-fine hardness: 4.1)
-Conductive agent (antimony-doped tin oxide): SN-100P (manufactured by Ishihara Sangyo) 40 parts by mass
-Solvent: 2000 parts by mass of N'N-dimethylacetamide
[0088]
The produced conductive roll 5 was evaluated in the same manner as in Example 1. The results are summarized in Table 1.
[0089]
<Comparative Example 1>
A conductive elastic layer A was molded in the same manner as in Example 1. Next, the following mixture was dispersed in a bead mill, and the obtained dispersion D was applied by dip coating on the surface of the conductive elastic layer A, and then dried by heating at 160 ° C. for 30 minutes to form a surface layer having a thickness of 5 μm. .
The above surface layer was separately prepared as a sheet, and its volume resistance was measured. ⁸ Ω · cm.
[0090]
-Polymer material (fluorine varnish): 100 parts by mass of Zeffle GK-500 (manufactured by Daikin Industries, Ltd., dynamic ultra-fine hardness: 3.6)
-Conductive agent (antimony-doped tin oxide): SN-100P (manufactured by Ishihara Sangyo) 40 parts by mass
Curing agent: Coronate 2507 (manufactured by Nippon Polyurethane Industry Co., Ltd.) 40 parts by mass
-Solvent: 50 parts by mass of 2-butanone and 200 parts by mass of butyl acetate
[0091]
The produced conductive roll 6 was evaluated in the same manner as in Example 1. The results are summarized in Table 1.
[0092]
<Comparative Example 2>
A conductive elastic layer A was molded in the same manner as in Example 1. The following mixture was dispersed in a bead mill, and the obtained dispersion E was applied by dip coating on the surface of the conductive elastic layer A, and then dried by heating at 160 ° C. for 30 minutes to form a surface layer having a thickness of 3 μm.
The surface layer was separately prepared as a sheet, and the volume resistance was measured. ¹⁰ Ω · cm.
[0093]
・ Polymer material (soft fluorine resin): 100 parts by mass of Sefralsoft (Dynamic ultra-micro hardness: 0.6 manufactured by Central Glass Co., Ltd.)
-Conductive agent (antimony-doped tin oxide): SN-100P (manufactured by Ishihara Sangyo) 40 parts by mass
-Solvent: 900 parts by mass of N-methyl-2-pyrrolidinone
[0094]
The produced conductive roll 7 was evaluated in the same manner as in Example 1. The results are summarized in Table 1.
[0095]
[Table 1]

[0096]
As shown in the examples of Table 1, even when the conductive roll of the present invention is used as a charging roll for continuous printing on an actual machine, no stain due to foreign matters such as toner is observed on the roll surface after printing, and the image quality is poor. It did not occur. On the other hand, it was found that even if the charging roll of the comparative example had the same Ra and volume resistivity of the surface layer, it was not possible to prevent adhesion of foreign matter and image quality defects.
[0097]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the charge which prevented the contamination of the charging roll which arises by a foreign material entering into the nip part of a charging roll and a photoreceptor, a local nip defect, and the image defect resulting from the filming of a photoreceptor is prevented. It is possible to provide a conductive roll that can efficiently prevent foreign substances from adhering to the surface such as a roll.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view when a charging roll to which a coarse foreign substance has adhered contacts a photoconductor.
FIG. 2 is a schematic cross-sectional view when a charging roller of the present invention to which a coarse foreign substance has adhered contacts a photosensitive member.
FIG. 3 is an enlarged sectional view of a contact portion between a foreign matter and a charging roll of the present invention.
FIG. 4 is a schematic sectional view showing an example of the conductive roll of the present invention.
FIG. 5 is a schematic sectional view showing another example of the conductive roll of the present invention.
[Explanation of symbols]
1 conductive support
2 Foam elastic layer
3, 5 Non-foamed elastic layer
4, 6 surface layer
11 Charging roll
12 Photoconductor
13 Coarse foreign matter
14 Nip failure area

Claims (16)

A conductive roll that has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged,
A conductive ultra-fine hardness of the conductive roll is 0.3 or less, and a dynamic ultra-fine hardness of a polymer material constituting the surface layer is 1.0 or more. . The conductive roll according to claim 1, wherein an arithmetic average roughness (Ra) of the conductive roll surface is 1.0 µm or less. 2. The conductive roll according to claim 1, wherein the surface layer has a volume resistivity of 1 × 10 ¹² Ω · cm or less. 3. 3. The conductive roll according to claim 2, wherein the surface layer has a volume resistivity of 1 × 10 ¹² Ω · cm or less. 4. A conductive roll that has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged. A charging roll comprising a conductive roll having a small hardness of 0.3 or less and a dynamic ultra-micro hardness of a polymer material constituting the surface layer of 1.0 or more. The charging roll according to claim 5, wherein an arithmetic mean roughness (Ra) of the charging roll surface is 1.0 m or less. The charging roll according to claim 5, wherein the surface layer has a volume resistivity of 1 × 10 ¹² Ω · cm or less. The charging roll according to claim 6, wherein the surface layer has a volume resistivity of 1 × 10 ¹² Ω · cm or less. A conductive roll that has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged. A transfer roll comprising a conductive roll having a small hardness of 0.3 or less and a dynamic ultra-fine hardness of a polymer material constituting the surface layer of 1.0 or more. The transfer roll according to claim 9, wherein the arithmetic average roughness (Ra) of the surface of the charging roll is 1.0 m or less. The transfer roll according to claim 9, wherein the surface layer has a volume resistivity of 1 × 10 ¹² Ω · cm or less. The transfer roll according to claim 10, wherein the surface layer has a volume resistivity of 1 × 10 ¹² Ω · cm or less. A conductive roll that has at least two or more conductive layers including a surface layer, contacts a member to be charged in a state where a voltage is applied, and charges the member to be charged. A cleaning roll comprising a conductive roll having a small hardness of 0.3 or less and a dynamic ultra-fine hardness of a polymer material constituting the surface layer of 1.0 or more. The cleaning roll according to claim 13, wherein the arithmetic average roughness (Ra) of the charging roll surface is 1.0 m or less. 14. The cleaning roll according to claim 13, wherein a volume resistivity of the surface layer is 1 × 10 ¹² Ω · cm or less. The cleaning roll according to claim 14, wherein the surface layer has a volume resistivity of 1 × 10 ¹² Ω · cm or less.

Images