JP2004094041A - Electrifying member and electrifying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrifying member capable of obtaining stable and excellent uniform electrifying property and image quality over a long term by preventing the deterioration of the performance of the electrifying member caused by the staining of the surface of the electrifying member. <P>SOLUTION: The electrifying member is constituted so that the effective line length SR1r of a surface layer provided on its outer peripheral surface is ≤107%, and the Tabar's weare thereof is ≤4.5mg or it is constituted by including crystalline resin and nucleating agent. <P>COPYRIGHT: (C)2004,JPO

Description

【００６６】
表１の結果、実施例１、２、３、４、５、６、７および８の帯電部材においては、３０万枚の画出し後も帯電ムラによる画像欠陥が発生せず、鮮明な画像が得られた。ただし、実施例４と６の帯電部材表面は画像に影響がない軽度な汚染が認められた。他の実施例の帯電部材表面は３０万枚画出しテスト後も汚れはなかった。一方、比較例１、２、３、および４の帯電部材においては、画像形成テスト時の帯電部材表面の汚れがひどく、数百枚の画像形成後に、帯電ムラによる画質欠陥が現われた。
【００６７】
【発明の効果】
以上、本発明によれば、帯電部材表面の汚れに起因する帯電部材の性能の低下を防止して、長期にわたって安定、且つ、良好な均一帯電性と、画像品質と、を得ることのできる帯電部材、及び帯電装置を提供することができる。
【図面の簡単な説明】
【図１】有効線長ＳＲｌｒを説明するための図である。
【図２】本発明の帯電部材が組み込まれた画像形成装置の一例を示す概略図である。
【図３】本発明の帯電部材を有する帯電器（帯電装置）の一例を示す概略図である。
【符号の説明】
１　　帯電部材
１ａ　導電性支持体
１ｂ　導電性弾性体層
１ｃ　抵抗層
１ｄ　表面層
１１　　感光体
１２　　レーザー書き込み装置
１３　　帯電器
１４　　現像器
１４ａ　トナーを収容する容器
１４ｂ　攪拌部材
１４ｃ　担持体
１４ｄ　供給ローラ
１５　　転写器
１６　　クリーニング装置
１６ａ　ケーシング
１６ｂ　ブレードホルダー
１６ｃ　クリーニングブレード
１７　　給紙トレイ
１８　　用紙取りだしローラ
１９　　用紙搬送ローラ
２０　　ガイド
２１　　定着装置
２１ａ　加熱ローラ
２１ｂ　加圧ローラ
２２　　搬送路
２３　　排出ローラ
２４　　搬送路
２５　　排出トレイ
３１　　支持部材
３２　　加圧スプリング
３３　　パッドホルダ
３４　　クリーニングパッド
３５　　直流電源
３６　　交流電源
Ｕ　　　画像形成装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a charging member and a charging device in an image forming apparatus such as an electrophotographic apparatus such as an electrophotographic copying machine, a printer, a facsimile, and a composite OA apparatus thereof, and an electrostatic recording apparatus. More specifically, the present invention relates to a charging member and a charging device that press against a surface of a charged body such as a photoconductor or a dielectric to uniformly charge the surface of the charged body.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, a charging process is performed on a surface of a member to be charged such as a photoconductor or a dielectric. As the charging means, a non-contact charging method of charging by corona discharge generated by applying a high voltage to a tungsten wire is widely used. However, in the non-contact charging method using the corona discharge, discharge products such as ozone and nitrogen oxides generated at the time of charging deteriorate the surface of the photoconductor, causing deterioration of the photoconductor and image blur, There has been a problem that contamination of the tungsten wire affects the image quality, causing white spots and black streaks in the image.
[0003]
In contrast to the non-contact charging method, there is a contact charging method in which a charging member is brought into contact with a member to be charged to perform a charging process. This contact charging method has the advantage that the voltage applied to the charging member is generally small and the amount of generated ozone is very small.However, toner or external additives that have passed through the cleaning blade during use adhere to the surface of the charging member. Alternatively, there is a drawback that the image sticks and sticks and an image defect occurs due to a charging failure caused by these.
[0004]
Further, in the early stage of printing, even when there is no adhesion of toner and external additives, stains are usually accelerated by continuous use. This is because the surface of the contact charging member is worn out due to friction with the photoreceptor and the toner, and is roughened.
[0005]
Several methods for improving the disadvantages of such a contact charging method have been studied so far. For example, according to the technique described in JP-A-64-66673, there is disclosed a charging member in which PTFE powder is dispersed and contained in a surface layer formed on the surface of an elastic body. Although this technology has the effect of preventing contamination of the charging member surface at the beginning of use by reducing the coefficient of kinetic friction, when it is used continuously, hard substances such as toner external additives are buried so as to pierce the charging member surface. There is a problem that this triggers to cause toner and the like to adhere to the surface of the charging member.
[0006]
Japanese Patent Application Laid-Open No. Hei 4-303861 discloses a method in which graphite as a layered solid lubricant is contained in the surface layer of a charging member to prevent contamination of the charging member and the photoreceptor. However, since graphite has a large surface energy, the effect of reducing the kinetic friction coefficient due to the delamination of graphite is offset, so that a large pollution prevention effect cannot be expected.
[0007]
In the techniques described in Japanese Patent Publication No. 50-13661, Japanese Patent No. 2649162, and Japanese Patent No. 2632899, in addition to good electrical properties, a nylon resin has both low adhesion and mechanical toughness, and other resins. It is described as being more useful as a contamination preventing material for the surface layer of the charging member. However, recently, development has been urgently required until it can be implemented in high-speed machines such as printers and copiers that do not require maintenance over a long period of time, or on-demand light printing machines that apply xerography. The fact is that it has not been reached.
[0008]
[Patent Document 1]
JP-A-64-66673
[Patent Document 2]
JP-A-4-303861
[Patent Document 3]
Japanese Patent Publication No. 50-13661
[Patent Document 4]
Patent No. 2649162
[Patent Document 5]
Patent No. 2632899
[0009]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described conventional problems and achieve the following objects. That is, an object of the present invention is to prevent deterioration in the performance of a charging member due to contamination on the surface of the charging member, and to provide a stable and good uniform charging property for a long period of time and an image quality capable of obtaining image quality. It is to provide a member and a charging device.
[0010]
[Means for Solving the Problems]
The inventors have found that contamination of the surface of the charging member, which causes deterioration of the performance of the charging member, that is, adhesion of the toner and the external additive to the surface of the charging member is partially caused by the fact that the toner and the external additive are partially removed from the surface of the charging member. Are found to be caused by embedding in minute irregularities corresponding to the particle size of the toner or external additive, and the irregularities are caused by the surface of the charging member being roughened by contact of the photoconductor, the toner or the external additive. This has led to the present invention. That is, the present invention
[0011]
<1> A charging member, wherein the effective line length SRlr of the surface layer provided on the outer peripheral surface is 107% or less, and the amount of Taber abrasion is 4.5 mg or less.
[0012]
<2> A charging member, wherein the surface layer provided on the outer peripheral surface contains a crystalline resin and a nucleating agent.
[0013]
<3> The charging agent according to <2>, wherein the nucleating agent is at least one selected from a phosphate, a metal carboxylate, and a sorbitol compound.
[0014]
<4> The charging member according to any one of <1> to <3>, wherein the surface layer is formed by performing a heat treatment.
[0015]
<5> A charging device in which a charging member is brought into contact with a member to be charged and has means for applying a voltage to the charging member, wherein the charging member is any one of <1> to <4>. A charging device, which is a charging member.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
(Charging member)
-First invention-
The charging member according to the first aspect of the present invention is characterized in that the surface layer provided on the outer peripheral surface has an effective line length SRlr of 107% or less and a Taber abrasion amount of 4.5 mg or less.
[0017]
In the charging member of the present invention, in order to avoid contamination of the surface of the charging member, which causes deterioration of the performance of the charging member, that is, fixation of the toner or the external additive to the surface of the charging member, the toner or the external additive is used. It is necessary to reduce fine irregularities corresponding to the particle diameter, and also to reduce the amount of wear on the surface of the charging member due to contact with the photoconductor, toner and external additives, and to reduce the surface roughness. Therefore, by setting the effective line length SRlr of the surface layer to 107% or less and the Taber abrasion amount to 4.5 mg or less, the fine irregularities on the surface are reduced, and the occurrence of the minute irregularities due to the roughening is suppressed. In addition, it is possible to prevent deterioration of the performance of the charging member due to contamination on the surface of the charging member, and to obtain stable and good uniform charging properties and image quality for a long period of time.
[0018]
In the charging member of the present invention, the effective line length SRlr of the surface layer needs to be 107% or less, but is preferably 100 to 105%, and more preferably 100 to 103%. If the effective line length SRlr is greater than 107%, the dirt gradually adheres to and accumulates on the surface of the charging member, for example, so that the uniform chargeability and image quality can be improved over time. descend.
[0019]
The effective line length SRlr is determined based on the type and the molecular weight of the binder resin constituting the surface layer (particularly effective when the surface layer is formed by a coating method), the particle diameter and the addition amount when the conductive fine particles are blended. It can be adjusted by appropriately selecting dispersibility, application conditions, and the like.
[0020]
Here, the effective line length SRlr is an index indicating minute irregularities on the surface of the charging member, and cuts off frequency components equal to or larger than the toner particle diameter from each frequency component of the cross-sectional shape of the surface layer surface, and obtains a roughness curve. Is divided by the measurement section length (b) and expressed as a percentage. FIG. 1 shows a roughness curve of the surface layer surface after the cutoff, in which the length in the radial direction with respect to the circumferential direction of the charging member is emphasized. Then, the effective line length SRlr is defined as in the following equation.
Formula: SRlr (%) = (a / b) × 100
In order to determine the effective line length SRlr, it is necessary to measure extremely minute irregularities on the surface of the charging member. Therefore, in the present invention, the effective line length SRlr is measured using a three-dimensional surface shape analyzer (RD500: manufactured by Electronic Engineering Laboratory) to measure the total length (a) of the roughness curve and the measurement section length (b). It is determined by the formula. This analyzer analyzes the shape of the sample surface from the reflected electron signal of a scanning electron microscope (S4200: manufactured by Hitachi, Ltd.).
[0021]
In the charging member of the present invention, the Taber abrasion amount of the surface layer is required to be 4.5 mg or less, but is preferably 0 to 4.0 mg, more preferably 0 to 3.5 mg. When the Taber abrasion amount is larger than 4.5, dirt gradually adheres and accumulates on the surface of the charging member, such as toner, so that uniform charging properties and image quality can be improved over time. descend.
[0022]
The amount of Taber abrasion can be adjusted by appropriately selecting the kind and the molecular weight of the binder resin constituting the surface layer, and when the conductive fine particles are blended, the particle diameter, the added amount, the dispersibility and the like. When a crystalline polymer is used for the binder resin, the Taber abrasion can be reduced by adding a nucleating agent or performing heat treatment after coating and drying. This is considered to be due to the fact that the degree of crystallinity of the resin is increased and the rigidity is increased due to the addition of the nucleating agent and the heat treatment after coating and drying, thereby reducing abrasion.
[0023]
Here, the Taber wear amount is an index indicating the wear amount, and can be obtained as follows. A resin layer (surface layer constituent material sample) having a thickness of about 100 μm applied on the base was applied to a Taber abrasion tester (product number 812: manufactured by Coating Tester) equipped with # 2000 wrapping tape (manufactured by Fuji Photo Film Co., Ltd.). The amount of abrasion when 1,000 rotations at a load of 1000 g and a rotation speed of 70 rpm is determined, and this is defined as the Taber abrasion amount.
[0024]
-Second invention-
A charging member according to a second aspect of the present invention is characterized in that the surface layer provided on the outer peripheral surface contains a crystalline resin and a nucleating agent. By adding a nucleating agent to the crystalline resin as the binder resin, the crystal size of the crystalline resin can be reduced and the crystallinity can be increased, and the surface layer containing these can reduce minute irregularities on the surface While suppressing the occurrence of minute irregularities due to surface roughening, preventing the deterioration of the performance of the charging member due to contamination on the surface of the charging member, stable over a long period of time, and good uniform chargeability, image quality and , You can get. Further, the conditions of the effective line length SRlr and Taber abrasion amount of the surface layer in the first aspect of the present invention can be preferably satisfied.
[0025]
As the crystalline resin, a nylon resin is preferably mentioned, while as the nucleating agent, a metal phosphate such as sodium 2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate; Metal salts of carboxylic acids such as aluminum hydroxybis (3-tert-butylbenzoate) and sodium benzoate, and sorbitol compounds such as benzylidene sorbitol and paramethylbenzylidene sorbitol can be used. Among these, metal phosphates are particularly preferred. These may be used alone or in combination of two or more.
[0026]
The compounding amount of the nucleating agent to the crystalline resin is preferably 0.01 to 5%, more preferably 0.05 to 3%, more preferably 0.1 to 2% based on the crystalline resin. .
[0027]
-Common matters of the first and second inventions (hereinafter simply referred to as the invention)-
As a preferable mode of the charging member of the present invention, for example, a conductive elastic material layer and a surface layer are sequentially provided on at least a conductive support, and if necessary, the conductive elastic material A resistance layer may be provided between the layer and the surface layer.
[0028]
For the material constituting the surface layer, in the case of the first invention, as the binder resin, a known resin material such as a polyamide resin, a polyester resin, or a polyurethane resin can be used. In the case of the second invention, A crystalline resin and a nucleating agent are used, and various additives such as a conductive agent and a crosslinking agent can be added as necessary.
[0029]
Known conductive materials such as carbon black and conductive metal oxides such as tin oxide can be used as the conductive agent. Examples of the crosslinking agent include isocyanates, melamines, methylated, ethylated, and epoxy resins. , Bisphenol-type epoxy resins, epoxy-based polymers, and the like, and blends thereof can be used. In addition, other additives other than these can be used as needed.
[0030]
The surface layer can be formed, for example, as follows. First, the above-mentioned materials are mixed, and the solid content is evenly dispersed using a sand mill or the like to prepare a coating solution. At this time, the viscosity of the coating solution and the film formation are adjusted by adjusting the mixing ratio of the diluting solvent. Next, the surface of the elastic layer or the surface of the resistive layer serving as a base is coated by a dip coating method, a dip coating method, a spray coating method (eg, a spray drying method) or the like, and the binder resin is dried and solidified at an appropriate temperature.
[0031]
When the dip coating method is employed in forming the surface layer, the effective line length SRlr tends to decrease, which is effective as a coating method. When a crystalline resin is used as the binder resin (second invention), the heat treatment increases the degree of crystallinity, resulting in high rigidity. As a result, low wear can be realized. Is a tendency to decrease. The temperature of this heat treatment is preferably from 80 to 140C, and more preferably from 100 to 120C. On the other hand, the heating time is preferably from 10 to 90 minutes, more preferably from 30 to 60 minutes.
[0032]
The thickness of the surface layer is preferably in the range of 0.5 μm to 100 μm. If the thickness of the surface layer is smaller than 0.5 μm, the effect of preventing contamination of the surface of the charging member may not be obtained. On the other hand, when the thickness is larger than 100 μm, the hardness of the charging member becomes unnecessarily large, so that sufficient adhesion to the surface of the member to be charged may not be obtained.
[0033]
The conductive support is not particularly limited as long as it is a conductive material having rigidity that supports the charging member. For example, the conductive support is plated with a metal or alloy such as aluminum, copper alloy, stainless steel, chromium, nickel, or the like. It is made of conductive material such as iron or synthetic resin. The outer diameter of the conductive support is usually in the range of 4 to 12 mm.
[0034]
The conductive elastic layer is used to press the charging member with a proper nip width or nip pressure against the surface of the member to be charged and uniformly charge the surface of the member to be charged. Is provided.
This elastic layer is formed by dispersing conductive particles in a rubber material. Examples of the rubber material include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, urethane rubber, silicone rubber, fluorine rubber, SBR, NBR, EPDM, acrylonitrile-butadiene-styrene rubber, and a blend rubber thereof. Among them, isoprene rubber, silicone rubber and EPDM are preferably used. These rubber materials may be foamed or non-foamed.
[0035]
Examples of the conductive particles include various conductive metals or alloys such as carbon black, graphite, aluminum, copper, nickel, and stainless steel, tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, and tin oxide-indium oxide solid solution. And various kinds of conductive metal oxides and fine powders obtained by subjecting the surface of an insulating material to a conductive treatment can be used.
For example, when using carbon black, it is blended in an amount of 30 to 50% by weight based on the rubber material so as to obtain a desired volume resistivity. The thickness of the conductive elastic layer may be usually in the range of 2 to 6 mm, and is preferably in the range of 3 to 5 mm. The volume resistance of the conductive elastic layer was 10 ² -10 ⁵ It is preferably in the range of Ω · cm.
[0036]
The resistance layer is provided to adjust the charging member to a predetermined resistance value, and is formed from a thin film in which the above-described conductive particles are dispersed in a resin.
The resin is not particularly limited, but is preferably a resin belonging to a somewhat soft class such as polyurethane, polyamide, and polyester. When, for example, carbon black is used as the conductive particles, it is added in an amount of 10 to 30% by weight with respect to the resin so as to obtain a desired volume resistivity. The volume resistance value of the resistance layer is 10 ⁵ -10 ⁹ It is preferably in the range of Ω · cm.
[0037]
Further, the thickness of the resistance layer is preferably in the range of 5 to 100 μm, and more preferably in the range of 10 to 80 μm. If the film thickness is less than 5 μm, not only the function of adjusting the resistance cannot be sufficiently exhibited, but also the leak is likely to occur and the surface of the member to be charged may be damaged. On the other hand, when the film thickness is larger than 100 μm, the resistance value and the hardness of the charging member increase more than necessary.
[0038]
The volume resistance value of the charging member according to the present invention having such a configuration is 1 × 10 ⁷ Ω ~ 1 × 10 ¹⁰ It is desirable to adjust so as to be within the range of Ω.
[0039]
(Charging device and image forming device)
FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus in which the charging member of the present invention is incorporated. In FIG. 2, a cylindrical photoconductor (drum) 11 that rotates in the direction of the arrow is arranged inside the main body of the image forming apparatus U, and functions as an electrostatic latent image carrier. A laser writing device 12 that writes an electrostatic latent image on the surface of the photoconductor 11 is disposed inside the main body of the image forming apparatus U. Around the cylindrical photoreceptor 11, a charger 13 for uniformly charging the surface of the photoreceptor 11 sequentially along a rotation direction thereof, a developing device 14 for visualizing the electrostatic latent image, a visualization A transfer device 15 for transferring the toner image thus formed onto a sheet (transfer material) and a cleaning device 16 for removing residual toner on the photoconductor 11 are provided.
[0040]
The developing device 14 includes a container 14a for storing toner. A stirring member 14b for stirring the toner, a rotatable developer carrier 14c, and a toner supply roller 14d for supplying the toner to the carrier 14c are provided in the container 14a. The developer carrier 14c faces the opening of the container 14a, and is supported by the container 14a with a slight gap from the surface of the photoconductor 11.
The cleaning device 16 has a casing 16a. A metal blade holder 16b is fixed to the casing 16a, and a sheet-like cleaning blade 16c is fixed to a tip of the metal blade holder 16b. The edge of the tip of the cleaning blade 16c is in contact with the surface of the photoconductor 11.
[0041]
At the lower part of the image forming apparatus U main body, a paper feed tray 17 for storing paper is arranged. A paper take-out roller 18 for taking out paper one by one from the paper feed tray 17 is arranged at an upper end portion of the paper feed tray 17. A pair of paper guides 20 that guide the paper conveyed by the pair of paper conveyance rollers 19 are disposed above the side of the paper take-out roller 18.
A fixing device 21 having a heating roller 21a and a pressure roller 21b is arranged on the upper side of the other side inside the image forming apparatus U body, and a toner image is transferred between the fixing device 21 and the transfer device 15. A conveyance path 22 that conveys the cut sheet is provided. Above the fixing device 21, a pair of discharge rollers 23 and a transport path 24 for guiding the sheet on which the toner image is fixed from the fixing device 21 to the discharge rollers 23 are provided. A discharge tray 25 on which the paper discharged from the discharge roller 23 is placed is formed on the upper surface of the main body of the image forming apparatus U.
[0042]
FIG. 3 is an enlarged view of a main part of the charger 13 shown in FIG. 1, and is a schematic view showing an example of a charger having the charging member of the present invention. In FIG. 3, the charger 13 includes the charging member 1 of the present invention in which a conductive elastic layer 1b, a resistance layer 1c, and a surface layer 1d are sequentially provided on a conductive support 1a. However, the charging member 1 may not have the resistance layer 1c.
The charging member 1 is supported at both ends of the conductive support 1 a by support members 31 fixed to the casing 16 a of the cleaning device 16. Further, the charging member 1 is pressed against the surface of the photoconductor 11 by the urging forces of two pressure springs 32, one end of which is fixed to the support member 31 and the other end of which is fixed to the end of the conductive support 1a. . A metal pad holder 33 is fixed to the support member 31, and a sheet-like cleaning pad 34 fixed to the tip of the support member 31 removes even a very small amount of toner from the surface of the charging member 1. It has become.
Further, a DC voltage is applied to the conductive support 1 a of the charging member 1 from a DC power supply 35. Further, if necessary, an AC voltage may be superimposed from the AC power supply 36 in addition to the DC voltage. Therefore, the surface of the photoconductor 11 rotating in a predetermined direction while contacting the surface layer 1d of the charging member 1 can be uniformly charged.
[0043]
The operation of the image forming apparatus U according to the present invention will be briefly described as follows. As described above, the surface of the photoconductor 11 rotating in the direction of the arrow is uniformly charged by the charging member 1 to which the voltage is applied. An electrostatic latent image is written on the uniformly charged photoconductor 11 by a laser writing device 12. The electrostatic latent image on the photoconductor 11 is developed into a toner image by the developing device 14. The toner image is transferred to a sheet conveyed from the sheet feed tray 17 by the transfer unit 15. After the transferred toner image is fixed by the fixing device 21, the sheet is discharged onto a discharge tray 25 by a discharge roller 23. After the toner image is transferred to the sheet, the toner remaining on the surface of the photoreceptor 11 is removed by the blade 16c of the cleaning device to prepare for the next electrophotographic process.
[0044]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.
[0045]
<Example 1>
(Formulation and preparation of elastic layer)
A conductive silicone rubber (X-34-2048AB, manufactured by Dow Corning Toray Co., Ltd.) is injection-molded to a SUS shaft having a diameter of 6 mm to a thickness of 3 mm, and a volume resistance of 5 × 10 ³ An elastic roller having Ωcm, ASKER-C hardness of 55 degrees and Φ12 mm was obtained.
[0046]
(Formulation and preparation of resistance layer)
The following composition was mixed in a ball mill to prepare a dispersion in which carbon black was uniformly dispersed in the resin. The obtained dispersion was spray-coated on the elastic roller, and then heated and dried to form a 20 μm-thick resistance adjusting layer made of a polyurethane film.
・ One-pack type urethane resin ・ ・ ・ ・ 100 parts by weight
(DF-407: manufactured by Dainippon Ink and Chemicals, Inc.)
・ Carbon black ・ ・ ・ ・ 5 parts by weight
(Regal 660R: manufactured by Cabot)
・ 2-butanone ・ ・ ・ ・ 100 parts by weight
[0047]
(Formulation and preparation of surface layer)
The following composition was mixed in a ball mill to prepare a dispersion in which a conductive agent and a nucleating agent were uniformly dispersed in a nylon resin.
・ Nylon quaternary copolymer resin (CM8000: manufactured by Toray) ・ ・ ・ ・ 100 parts by weight
・ Tin oxide (NS-100P: manufactured by Ishihara Sangyo) ・ ・ ・ ・ 20 parts by weight
・ Sodium 2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate (STAB NA-11: manufactured by Asahi Denka Kogyo KK) 0.5 parts by weight
・ Methanol / butanol mixture ・ ・ ・ ・ 900 parts by weight
[0048]
The resulting dispersion was applied to the roller by dip coating, and then heated and dried at 120 ° C. to form a surface layer having a thickness of 2 μm. The SRlr of this charging roll was 102%, and the Taber abrasion amount was 2.6 mg.
[0049]
<Example 2>
The same operation as in Example 1 was performed, except that the method of coating the surface layer in Example 1 was changed to the spray-dry method, to produce a charging roll. The SRlr of this charging roll was 104%, and the Taber abrasion amount was 2.6 mg.
[0050]
<Example 3>
A charging roll was prepared in the same manner as in Example 1 except that the nucleating agent for the surface layer in Example 1 was changed to paramethylbenzylidene sorbitol (Gallall MD: manufactured by Shin Nippon Rika Co., Ltd.). The SRlr of this charging roll was 104%, and the Taber abrasion was 3.5 mg.
[0051]
<Example 4>
A charging roll was prepared in the same manner as in Example 3, except that the method of coating the surface layer in Example 3 was changed to the spray-dry method. The SRlr of this charging roll was 107%, and the Taber abrasion was 3.5 mg.
[0052]
<Example 5>
The same operation as in Example 1 was performed except that the nucleating agent for the surface layer in Example 1 was changed to aluminum hydroxybis (3-tert-butylbenzoate) (Al-PTBBA: manufactured by Shell Chemical Co., Ltd.) to prepare a charging roll. did. The SRlr of this charging roll was 103%, and the Taber abrasion was 2.9 mg.
[0053]
<Example 6>
A charging roll was prepared in the same manner as in Example 5, except that the method of coating the surface layer in Example 5 was changed to the spray drying method. The SRlr of this charging roll was 105%, and the Taber abrasion was 2.9 mg.
[0054]
<Example 7>
A charging roll was prepared in the same manner as in Example 1 except that the preparation and composition of the surface layer of Example 1 were changed as described below. The SRlr of this charging roll was 104%, and the Taber abrasion amount was 4.5 mg.
[0055]
(Formulation and preparation of surface layer)
The following composition was mixed in a ball mill to prepare a dispersion in which the conductive agent was uniformly dispersed in the polyvinyl butyral resin.
・ Polyvinyl butyral resin ・ ・ ・ ・ 100 parts by weight
(Butvar B74: manufactured by Monsanto)
・ Tin oxide (NS-100P: manufactured by Ishihara Sangyo) ・ ・ ・ ・ 20 parts by weight
・ Ethanol / isopropanol mixture ・ ・ ・ ・ 900 parts by weight
[0056]
Example 8
The same surface layer as that of Example 1 was prepared, and an annealing treatment was performed at 120 ° C. for 1 hour to prepare a charging roll. The SRlr of this charging roll was 102%, and the Taber abrasion was 1.6 mg.
[0057]
<Comparative Example 1>
A charging roll was prepared in the same manner as in Example 7, except that the method of coating the surface layer in Example 7 was changed to the spray drying method. The SRlr of this charging roll was 109%, and the Taber abrasion amount was 4.5 mg.
[0058]
<Comparative Example 2>
The same operation as in Example 1 was performed except that the nucleating agent was removed from the surface layer composition of Example 1, to prepare a charging roll. The SRlr of this charging roll was 108%, and the Taber abrasion amount was 5.0 mg.
[0059]
<Comparative Example 3>
The same operation as in Comparative Example 2 was performed, except that the method of coating the surface layer in Comparative Example 2 was changed to the spray-dry method, to produce a charging roll. The SRlr of this charging roll was 110%, and the Taber abrasion amount was 5.0 mg.
[0060]
<Comparative Example 4>
The same surface layer as that of Comparative Example 2 was prepared, and an annealing treatment was performed at 120 ° C. for 1 hour to prepare a charging roll. The SRlr of this charging roll was 108%, and the Taber abrasion was 4.0 mg.
[0061]
<Comparative Example 5>
The polyvinyl butyral resin having the surface layer composition of Example 7 was prepared by adjusting the weight average molecular weight to 90 × 10 ³ The same operation as in Example 7 was carried out except that the polyvinyl butyral resin (Butvar B-90: manufactured by Sunmont Co., Ltd.) was used, to prepare a charging roll. The SRlr of this charging roll was 110%, and the Taber abrasion amount was 8.1 mg.
[0062]
<Evaluation>
(Charging potential evaluation test)
The obtained charging roll was attached to a charger in an image forming apparatus (Able3221: manufactured by Fuji Xerox Co., Ltd.), and the image forming apparatus was modified so that the potential on the surface of the photoreceptor could be measured. The surface of the photoreceptor having an outer diameter of 30 mm in contact with the charging roll was uniformly charged to -420 V, the image forming apparatus was operated, and the potential of the photoreceptor surface was continuously measured at the position of the developer carrier. . Table 1 shows the average value of the potential for one rotation of the photoconductor and the difference (potential variation) between the maximum potential and the minimum potential during one rotation. The charging potential and the variation in potential after 300,000 sheets were run were measured under an applied condition of initially applying −420 V.
[0063]
(Evaluation of image quality and evaluation of contamination on charging member surface)
The image evaluation and the contamination evaluation on the surface of the charging member were performed by mounting the charging members obtained in the respective Examples and Comparative Examples on the above-described image forming apparatus and performing an image forming test on a maximum of 300,000 sheets. Table 1 shows the results.
[0064]
The image evaluation and the contamination evaluation of the charging member surface were performed according to the following criteria.
-Image evaluation criteria-
〇: There is no deterioration in image quality after 300,000 images are output.
×: Remarkable deterioration of image quality occurs with less than 300,000 images.
−Criteria for evaluating charging member surface−
〇: No contamination on the surface of the charging member after 300,000 sheets of images were output.
Δ: Minute stains were generated on the surface of the charging member after 300,000 sheets of images were output.
×: Not more than 300,000 images were printed, and remarkable stains were generated on the surface of the charging member.
[0065]
[Table 1]

[0066]
As a result of Table 1, the charging members of Examples 1, 2, 3, 4, 5, 6, 7, and 8 did not cause image defects due to charging unevenness even after 300,000 sheets of images were output, and provided clear images. was gotten. However, the surfaces of the charging members of Examples 4 and 6 were slightly contaminated without affecting the image. The surface of the charging member of the other examples was not stained even after the image output test for 300,000 sheets. On the other hand, in the charging members of Comparative Examples 1, 2, 3, and 4, the surface of the charging member during the image forming test was significantly stained, and image defects due to charging unevenness appeared after forming hundreds of images.
[0067]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent deterioration in the performance of the charging member due to contamination on the surface of the charging member, and to obtain a stable and good uniform charging property and image quality for a long period of time. A member and a charging device can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an effective line length SRlr.
FIG. 2 is a schematic view illustrating an example of an image forming apparatus in which the charging member of the present invention is incorporated.
FIG. 3 is a schematic view showing an example of a charger (charging device) having the charging member of the present invention.
[Explanation of symbols]
1 Charging member
1a conductive support
1b Conductive elastic layer
1c Resistance layer
1d surface layer
11 Photoconductor
12 Laser writing device
13 Charger
14 Developing device
14a Container for storing toner
14b Stirring member
14c carrier
14d supply roller
15 Transfer device
16 Cleaning device
16a Casing
16b blade holder
16c cleaning blade
17 Paper tray
18 Paper take-out roller
19 Paper transport roller
20 Guide
21 Fixing device
21a heating roller
21b Pressure roller
22 Transport path
23 Discharge roller
24 transport path
25 discharge tray
31 Supporting member
32 pressure spring
33 pad holder
34 Cleaning Pad
35 DC power supply
36 AC power supply
U image forming device

Claims (5)

A charging member, wherein the effective line length SRlr of the surface layer provided on the outer peripheral surface is 107% or less, and the Taber abrasion amount is 4.5 mg or less. A charging member, wherein a surface layer provided on an outer peripheral surface includes a crystalline resin and a nucleating agent. The charging agent according to claim 2, wherein the nucleating agent is at least one selected from a phosphate, a metal carboxylate, and a sorbitol compound. The charging member according to any one of claims 1 to 3, wherein the surface layer is formed by performing a heat treatment. A charging device in which a charging member is brought into contact with a member to be charged and has a means for applying a voltage to the charging member, wherein the charging member is the charging member according to any one of claims 1 to 4. Characteristic charging device.

Images