JP2004037667A - Developing roller, processing cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller which prevents a developer leak even in a long term use, maintains a satisfactory image, and a process cartridge using the developing roller, and an image forming apparatus. <P>SOLUTION: The developing roller of a developing device has end seal members disposed in pressure contact with developer roller ends in order to prevent a leak of developer from the ends of the developing roller. The developing roller has: a conductive shaft; a conductive elastic base layer made of a rubber which is formed on the outside of the conductive shaft; and a conductive surface layer made of a rubber or a resin which is formed on the outside of the base layer. If the ten-point average roughness of an image forming area of the developer roller surface is Rz1 and the ten-point average roughness of at least end seal contact part is Rz2, the relation between Rz1 and Rz2 is 0.25xRz1≤Rz2≤0.5xRz1. <P>COPYRIGHT: (C)2004,JPO

Description

【００４４】
上記式（ＩＩ）において、Ｌｒ_ｉは粒子ｉの投影像の面積と同一の面積を有する円の円周長を表し、Ｌｏ_ｉは、粒子ｉの投影像の周囲長を表す。
【００４５】
なお、本発明で用いるフロー式粒子像分析装置「ＦＰＩＡ−１０００」は、各粒子の円形度（Ｃ_ｉ）を算出した後、平均円形度（Ｃ）の算出に当たって、各粒子の円形度（Ｃ_ｉ）に基いて、粒子群を、円形度０．４０〜１．００を６１分割したクラスに分け、各分割点の中心値と各クラスにクラス分けされた粒子の頻度を用いて平均円形度の算出を行う算出法を用いている。この算出法で算出される平均円形度の値と、上述した各粒子の円形度（Ｃ_ｉ）を直接式（ＩＩＩ）に代入して算出される平均円形度の値との差は、非常に少なく、実質的に無視出来る程度のものであり、どちらの方法も本発明に用いることができる。本発明においては、算出時間の短絡化や算出演算式の簡略化の如きデータの取り扱い上の理由で、フロー式粒子像分析装置「ＦＰＩＡ−１０００」で測定した平均円形度を用いることとした。
【００４６】
フロー式粒子像分析装置「ＦＰＩＡ−１０００」の被検試料としては、例えば、界面活性剤を約０．１ｍｇ溶解した水１０ｍｌに現像剤約５ｍｇを加え、超音波（２０ｋＨｚ、５０Ｗ）を５分間照射し分散させ、現像剤粒子濃度を５０００〜２万個／μｌとしたものを用いることができる。
【００４７】
本発明における平均円形度は、現像剤の凹凸度合いの指標であり、現像剤が完全な球形の場合１．０００を示し、現像剤の表面形状が複雑になるほど平均円形度は小さな値となる。なお、本発明において３μｍ以上の円相当径の粒子群についてのみ円形度を測定する理由は、３μｍ未満の円相当径の粒子群には現像剤粒子とは独立して存在する外部添加剤の粒子群も多数含まれ、その影響により現像剤粒子群についての円形度を正確に見積もれないからである。
【００４８】
次に本発明のプロセスカートリッジおよび画像形成装置について説明する。
【００４９】
図２は、本発明に適用されるプロセスカートリッジおよび画像形成装置の一例を示す概念図である。図２において、現像装置２４は、一成分現像剤として非磁性トナー２８を収容した現像容器３４と、現像容器３４内の長手方向に延在する開口部に位置し感光体２１と対向設置された現像ローラ２５とを備え、感光体２１上の静電潜像を現像して可視化するようになっている。
【００５０】
現像ローラ２５は、上記開口部にて図に示す右略半周面を現像容器３４内に突入し、左略半周面を現像容器３４外に露出して横設されている。この現像容器３４外へ露出した面は、現像装置２４の図中左方に位置する潜像を担持した感光体２１に当接して対向している。
【００５１】
感光体２１の周速は５０〜１７０ｍｍ／ｓ、現像ローラ２５の周速は感光体の周速に対して１〜２倍の周速で回転させている。
【００５２】
現像ローラ２５の上方位置には、ＳＵＳ等の金属板や、ウレタン、シリコーン等のゴム材料または、バネ弾性を有するＳＵＳまたはリン青銅の金属薄板を基体とし、現像ローラ２５への当接面側にゴム材料を接着したもの等からなる現像剤規制部材２７が、自由端側の先端近傍を現像ローラ２５の外周面に面接触にて当接するように設けられており、その当接方向としては、当接部に対して先端側が現像ローラ２５の回転方向上流側に位置するいわゆるカウンター方向になっている。
【００５３】
供給ローラ２６は、現像剤規制部材２７の現像ローラ２５表面との当接部に対し現像ローラ２５の回転方向上流側に当接され、かつ回転可能に支持されている。この構造としては、発泡骨格状スポンジ構造や芯金上にレーヨン、ナイロン等の繊維を植毛したファーブラシ構造のものが、現像ローラ２５への現像剤２８の供給および未現像の現像剤の剥ぎ取りの点から好ましい。
【００５４】
なお、以上は画像形成装置本体に着脱可能な現像装置からなるプロセスカートリッジに適用した場合について説明したが、画像形成装置本体内に固定され、現像剤のみを補給するような構成の現像装置に適用してもよい。また、少なくとも上記現像装置を備え、必要に応じ感光体２１、クリーニングブレード３０、廃トナー容器３１、帯電装置２２の全てを、あるいはいくつかを一体で形成し画像形成装置本体に対し着脱可能なプロセスカートリッジに適用してもよい。
【００５５】
【実施例】
以下に実施例にてさらに詳細に説明する。なお、本実施例中の「部」および「％」は、特記されている場合を除き、それぞれ、質量部および質量％を意味する。
【００５６】
まず本実施例に使用した現像剤について説明する。
【００５７】
（現像剤製造例１）
まず、イオン交換水７０９部に０．１Ｍ−Ｎａ_３ＰＯ_４水溶液４５１部を投入し６０℃に加温した後、１．０Ｍ−ＣａＣｌ_２水溶液６７．７部を徐々に添加してＣａ_３（ＰＯ_４）_２を含む水系媒体を得た。
【００５８】
スチレン単量体　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　８０部
ｎ−ブチルアクリレート単量体　　　　　　　　　　　　　　　　　　　　２０部
不飽和ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　３部
飽和ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　４部
上記処方をアトライター（三井三池化工機（株）、商品名）を用いて均一に分散混合した。
【００５９】
この単量体組成物を６０℃に加温し、そこにベヘニン酸ベヘニルを主体とするエステルワックス６部を添加混合溶解し、これに重合開始剤２，２‘−アゾビス（２，４−ジメチルバレロニトリル）５部を溶解した。
【００６０】
前記水系媒体中に上記重合性単量体系を投入し、６０℃、Ｎ_２　雰囲気下においてＴＫ式ホモミキサー（特殊機化工業（株）、商品名）にて１０，０００ｒｐｍで１５分間撹拌し、造粒した。その後パドル撹拌翼で撹拌しつつ、６０℃で６時間反応させた。その後液温を８０℃とし更に４時間撹拌を続けた。反応終了後、８０℃で更に２時間蒸留を行い、その後、懸濁液を冷却し、塩酸を加えてＣａ_３（ＰＯ_４）_２を溶解し、濾過、水洗、乾燥して現像剤Ａを得た。該現像剤Ａの重量平均粒子径は１０．０μｍ、平均円形度は０．９４１であった。
【００６１】
（現像剤製造例２）
スチレン単量体　　　　　　　　　　　　　　　　　　　　　　　　１７５部
ｎ−ブチルアクリレート単量体　　　　　　　　　　　　　　　　　　２５部
カーボンブラック　　　　　　　　　　　　　　　　　　　　　　　　１５部
サリチル酸金属化合物　　　　　　　　　　　　　　　　　　　　　１．６部
を上記アトライターを用いて５時間分散させた後、上記混合物に下記の成分を加えて、さらに２時間分散させた。
【００６２】
飽和ホ゜リエステル（酸価９．８ｍｇＫＯＨ／ｇ、ヒ゜ーク分子量１１０００）　１６部
エステルワックス　　　　　　　　　　　　　　　　　　　　　　　　２０部
次に、上記分散質系に重合開始剤２，２’−アゾビス（２，４−ジメチルバレロニトリル）５部を添加した後、上記分散媒中に投入し、内温７０℃の窒素雰囲気下、１５０００ｒｐｍで１５分間造粒した。その後、撹拌機をプロペラ撹拌機に交換し、撹拌しながら７０℃に保ちつつ５時間重合し、さらに内温を８０℃に昇温させ５時間重合した。重合終了後、スラリーを冷却し希塩酸を添加して分散剤を除去した。さらに水洗し、乾燥、分級を行い、着色粒子を得た。
【００６３】
上記着色粒子１００部に対して、一次粒径約６ｎｍのシリカ１００部にジメチルシリコーンオイル２０部で表面処理した疎水性シリカ（ＢＥＴ＝１２５ｍ^２／ｇ）１．２部と、ハイドロタルサイト０．２部をヘンシェルミキサーＦＭ１０Ｂ（三井鉱山（株）、商品名）にて外添して現像剤Ｂを得た。
【００６４】
該現像剤Ｂの重量平均粒子径は６．８μｍ、平均円形度は０．９８０であった。
【００６５】
また、各実施例のローラは、図２の現像装置を有するプロセスカートリッジに組み込み、市販のカラーレーザープリンターＬＢＰ２１６０（キヤノン（株）、商品名）をこのプロセスカートリッジが装着できるように改造した改造機Ｂを用いて評価した。
【００６６】
（実施例１および３）
鋼材にニッケルメッキ（ＫＮメッキ）を施した長さ２５０ｍｍで径８ｍｍの導電性軸体（芯金と表すことがある）に接着剤　ＤＹ３９−１１０（東レ・ダウコーニングシリコーン（株）、商品名）を塗布し熱処理後、円筒形の金型に芯金を装着し、導電化付加型液状ジメチルシリコーン材料を注入し、１５０℃で１０分硬化し、金型より取り出し、その後２００℃で４時間二次硬化を行い、被覆長さ２４０ｍｍで径１６ｍｍ（導電性弾性体基層の厚み４ｍｍ）の導電性弾性体基層を有するローラを形成した。このローラに粗し粒子として平均粒子径１０μｍのウレタンビーズ、アートパールＣＦ−６００Ｔ（根上工業（株）、商品名）５質量部をウレタン塗料バインダー、Ｎ５０３３（日本ポリウレタン工業（株）、商品名）１００質量部に添加した導電化ウレタン塗料をディップ法にて塗布し、乾燥後１４０℃で４時間硬化し、その後室温で一日放置し、導電性表層の厚みが２０μｍで表面粗さ６μｍである現像ローラを形成した。このローラを回転させ、端部シール当接部位の十点粗さが１．５μｍとなるよう、＃２０００のサンドペーパーにて端部シール当接部位を平滑化し実施例１および３の現像ローラを形成した。
【００６７】
（実施例２および４）
端部シール当接部位の十点平均粗さが３μｍとなるよう、端部シール当接部位を平滑化した以外は実施例１と同様にして実施例２および４の現像ローラを形成した。
【００６８】
（実施例５および７）
粗し粒子として平均粒子径１５μｍのウレタンビーズ、アートパールＣ−４００（根上工業（株）、商品名）を用い、表面粗さ９．５μｍとし、端部シール当接部位の十点平均粗さが２．４μｍとなるよう、端部シール当接部位を平滑化した以外は実施例１と同様にして実施例５および７の現像ローラを形成した。
【００６９】
（実施例６および８）
端部シール当接部位の十点平均粗さが４．７μｍとなるよう、端部シール当接部位を平滑化した以外は実施例５と同様にして実施例６および８の現像ローラを形成した。
【００７０】
（比較例１）
端部シール当接部位の十点平均粗さが０．５μｍとなるよう、端部シール当接部位を平滑化した以外は実施例１と同様にして比較例１の現像ローラを形成した。
【００７１】
（比較例２）
端部シール当接部位の十点平均粗さが４μｍとなるよう、端部シール当接部位を平滑化した以外は実施例１と同様にして比較例２の現像ローラを形成した。
【００７２】
（比較例３）
粗し粒子として平均粒子径１５μｍのウレタンビーズ、アートパールＣ−４００（根上工業（株）、商品名）を１５部用い、表面粗さ９．５μｍとし、端部シール当接部位の十点平均粗さが３μｍとなるよう、端部シール当接部位を平滑化した以外は実施例１と同様にして比較例３の現像ローラを形成した。
【００７３】
これらの実施例１〜８および比較例１〜３の現像ローラについて、端部漏れを評価した結果を表１に示す。
【００７４】
【表１】

【００７５】
上記表１に示したように、本発明の現像ローラは、本発明の現像ローラを組み込んだプロセスカートリッジを用いた画像形成装置で評価した場合、現像剤端部漏れは発生せず、かつ平均円形度が０．９８０の現像剤を用いた場合は、耐久時の端部カブリも発生せず、良好な画像を長期に維持することができた。
【００７６】
また、端部シール当接部位の十点平均粗さが小さすぎる比較例１の現像ローラにおいては、現像ローラ端部の剥がれが生じ、画像不良を発生した。端部粗さが粗すぎる比較例２の現像ローラにおいては、現像剤の端部漏れが発生し、画像不良となった。なお、比較例３のＲｚ１／Ｒが大きな値となる現像ローラと現像剤種とを組み合わせた比較例３のプロセスカートリッジでは初期よりカブリがみられ初めから画像不良（ＮＧ）を発生した。
【００７７】
【発明の効果】
本発明の現像ローラ、本発明の現像ローラを使用した本発明のプロセスカートリッジおよび本発明のプロセスカートリッジを有する本発明の画像形成装置は、長期間使用した場合においても、現像剤の漏れがなく、良好な画像を維持することができ、複写機、プリンター、ファックス等に広く用いることができる。
【図面の簡単な説明】
【図１】本発明の現像ローラの一例を示す概略図である。
【図２】本発明のプロセスカートリッジおよび画像形成装置の一例を示す概念図である。
【符号の説明】
２１…感光体（感光ドラム）
２２…帯電装置
２３…レーザー光
２４…現像装置
２５…現像ローラ
２５ａ…導電性表層
２５ｂ…導電性軸体
２５ｃ…導電性弾性体基層
２５ｄ…端部シール当接部位
２６…供給ローラ
２７…現像剤規制部材
２８…非磁性トナー（現像剤）
２９…転写ローラ
３０…クリーニングブレード
３１…廃トナー容器
３２…定着装置
３３…紙
３４…現像容器[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a developing roller, a process cartridge using the developing roller, and an image forming apparatus using the process cartridge, which are used in a recording method using an electrophotographic method, an electrostatic recording method, a developer jet recording method, or the like. More specifically, the present invention relates to a developing roller, a process cartridge, and an image forming apparatus used in a copier, a printer, a facsimile, and the like, which form an image on a photoconductor in advance by using a developer and then transfer the image onto a transfer material to form an image.
[0002]
[Prior art]
For example, in an image forming apparatus using an electrophotographic method, a rotating photoconductor is uniformly charged by a charging roller and forms an electrostatic latent image by a laser or the like. Next, using the developer applied to the developing roller in a proper amount and in a uniform amount by the developer supply roller and the developer regulating member, development is performed by the developer at a contact portion between the photoconductor and the developing roller. Thereafter, the developer on the photoreceptor is transferred to recording paper by a transfer roller and fixed by heat and pressure to complete a series of processes.
[0003]
The image forming apparatus using such an electrophotographic method has been advanced in color and speed, and a developer used in such an image forming apparatus has been developed in order to cope with higher definition of an image. The particle size has been reduced. In addition, with the development of color image forming apparatuses, non-magnetic one-component developers that can take a simpler configuration are used more frequently than two-component developers using a magnetic carrier and a magnet. A non-magnetic one-component developer that does not require maintenance is applied to a color image forming apparatus of a type that is used as a single-use type.
[0004]
Furthermore, in order to further improve the color reproducibility of the developer, a device for lowering the melting point of the developer and improving color mixing has been devised. Further, from the viewpoint of energy saving of a fixing system using heat which is generally used, a device for lowering the melting point of the developer has been devised.
[0005]
As a development method used in an image forming apparatus using such a non-magnetic one-component developer, a contact development method in which development is performed by contacting a photoconductor is known. A non-magnetic one-component contact developing method using a developing roller having a conductive elastic layer is known.
[0006]
It is known that the developing roller has an uneven surface on the surface of the developing roller in order to convey an appropriate amount of the developer to the photosensitive member. The developing roller provided with a rubber base layer and a surface layer in order to contact the photoreceptor and maintain a uniform contact state is made of a relatively soft material having a JISA hardness of about 10 to 60 degrees.
[0007]
However, when the developing roller corresponding to the contact developing system of the image forming apparatus using the non-magnetic one-component developer as described above is used, there are the following problems.
[0008]
Since the developing roller has irregularities to optimize the amount of developer transported, the developer enters between the developing roller and the developer seal at the end during long-term use, and the developer leaks from the end. In addition, the inside of the image forming apparatus is contaminated, and furthermore, the leaked developer adheres to the printed image, thereby deteriorating image quality. In particular, as the particle size of the developer becomes finer, this problem becomes more remarkable, and when the melting point of the developer is low or when the printing speed is high, the developer that has leaked to the developing roller and the end seal may be removed. As a result, the gap between the developing roller and the end seal is increased, and the leakage of the developer is promoted.
[0009]
In order to solve these problems, Japanese Patent Application Laid-Open No. H03-229285 discloses that the surface roughness Rz of the portion of the powder developer conveying member in contact with the end seal member is set at 1/10 or less of the volume average particle diameter of the developer. It has been proposed that
[0010]
[Problems to be solved by the invention]
The present invention relates to a developing roller having a configuration of a conductive shaft, a conductive elastic base layer formed of a rubber material formed outside thereof, and a conductive surface layer formed of a rubber material or a resin material formed outside thereof. Another object of the present invention is to provide a developing roller capable of maintaining a good image without developing agent leaking from a roller end portion during long-term use, and further provide a process cartridge and an image forming apparatus using the developing roller. It is in.
[0011]
[Means for Solving the Problems]
The above object is achieved by the present invention described below.
[0012]
That is, the present invention relates to a developing device having at least a developer, a developing roller, and an end seal member which is disposed in pressure contact with an end of the developing roller in order to prevent leakage of the developer from the end of the developing roller. In the developing roller, the developing roller includes a conductive shaft, a conductive elastic base layer formed of a rubber material formed outside the conductive shaft, and a conductive material formed of a rubber material or a resin material formed outside the conductive shaft. When the ten-point average roughness of the image forming area on the surface of the developing roller is Rz1 and the ten-point average roughness of at least the end seal contact portion is Rz2, the relationship between Rz1 and Rz2 is as follows.
0.25 · Rz1 ≦ Rz2 ≦ 0.5 · Rz1
A developing roller.
[0013]
That is, as described above, in order to prevent the developer from leaking from the end, it is effective to set the roughness of the end of the developing roller to 0.5 or less of the image forming area. By setting the ratio to 25 or more, the friction between the end seal and the developing roller is increased, so that a developing roller that does not cause peeling of the end of the roller or breakage of the end can be obtained.
[0014]
Further, the present invention is detachably attached to the image forming apparatus main body, and is arranged at least in contact with the developer, the developing roller, and the end of the developing roller in order to prevent leakage of the developer from the end of the developing roller. In the process cartridge having the end seal member, the developing roller has a conductive shaft, a conductive elastic base layer made of a rubber material formed outside the shaft, and a rubber material formed outside the conductive shaft. When a ten-point average roughness of an image forming area on the surface of the developing roller is Rz1 and at least a ten-point average roughness of an end seal contact portion is Rz2, Rz1 The relationship with Rz2 is
0.25 · Rz1 ≦ Rz2 ≦ 0.5 · Rz1
And when the weight average particle diameter of the developer is R, the relationship between R and Rz1 is
0.6R ≦ Rz1 ≦ 1.4R
A process cartridge.
[0015]
That is, when the developing roller as described above is used in the process cartridge, the weight average particle diameter of the developer used and the surface roughness of the image forming area of the developing roller, and further, the image forming area and the end of the developing roller are used. In order to apply the non-magnetic one-component developer uniformly on the developing roller and without causing image defects such as fog, the surface roughness of the developing roller must be Is appropriate in the range of 0.6R to 1.4R with respect to the weight average particle diameter R, and the above range is appropriate as the roughness of the end portion.
[0016]
Further, the present invention is the process cartridge, wherein the developer has an average circularity of 0.950 to 0.995, and the appropriate roughness of the image forming area and the end of the developing roller is within the above range. Desirably.
[0017]
According to another aspect of the present invention, there is provided an image forming apparatus having a process cartridge, wherein the process cartridge is the above-described process cartridge.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in more detail with reference to preferred embodiments.
[0019]
As shown in FIG. 1, the developing roller of the present invention includes a conductive shaft 25b, a conductive elastic base layer 25c formed of a rubber material formed outside the shaft, and a rubber material or resin material formed outside the conductive shaft body 25b. , And has an appropriate roughness on the surface of the image forming area. An end portion (which may be referred to as an end seal contact portion) 25d that comes into contact with the end seal of the developing roller is processed to have a surface roughness of 〜 to の of the image molding area.
[0020]
Since the developing roller used in the contact developing method needs to contact the photoreceptor and have a uniform contact width, the roller hardness is about A10 to A60 degrees in terms of hardness measured by a type A durometer of JIS K 6253. In order to develop the latent image formed on the photoreceptor with a proper and charged developer, the electric resistance needs to be about 1E3 to 1E7Ω.
[0021]
As the material used for the conductive shaft, generally used metal shafts such as stainless steel having a diameter of about 4 mm to 10 mm or nickel-plated and chromated steel can be used. The contact is not particularly limited as long as no significant bending occurs due to the contact.
[0022]
Examples of the rubber material forming the conductive elastic body base layer include rubber materials such as silicone rubber, urethane rubber, NBR (nitrile butadiene rubber), EPDM (ethylene propylene diene rubber), hydrin rubber, and natural rubber, such as carbon black and metal particles. Electronic conductive agents, or those made conductive by an ionic conductive agent such as a metal salt of perchloric acid, and foams thereof, and the like, but are not particularly limited as long as appropriate softness and conductivity are achieved. Absent. What made silicone rubber and urethane rubber conductive is preferable from the point of compression set.
[0023]
In addition, various additives such as a plasticizer, an extender, a reinforcing agent, a reaction catalyst, and a reaction retarder can be used as long as the performance as a developing roller used in the contact developing system can be maintained.
[0024]
As a method for forming the conductive elastic body base layer, a rubber material is injected into a cylindrical mold and heat curing is performed, and a tube-shaped material formed in advance by extrusion or the like is heated and cured. The shaft body can be formed by press-fitting the shaft body into the conductive elastic body or the foamed conductive elastic body, followed by polishing and forming.
[0025]
Next, as a material used as the conductive surface layer, a rubber material or a resin material can be used.However, as long as it is a rubber material or a resin material having appropriate softness as a developing roller and appropriate conductivity, May be used. However, it is preferable to use a thermosetting rubber material or a resin material having a rubber elasticity that is unlikely to cause permanent deformation when the roller is pressed against the photoconductor. For example, a conductive material such as urethane resin, acrylic urethane resin, crosslinked nylon resin, and natural rubber paint is used. The compound is preferably used, but is not limited thereto. Of these, urethane resins having excellent elastic recovery are more preferable.
[0026]
The method for forming the conductive surface layer is not particularly limited. However, the resin material constituting the conductive surface layer is dissolved or dispersed in an appropriate solvent to form a coating, which is then coated with a dip, spray, etc. It is possible to use a molding method such as coating the material formed in a shape. Among these methods, the dipping method is preferable from the viewpoint that it is easy to obtain the appropriate roughness described later.
[0027]
The thickness of the conductive surface layer at this time is preferably 10 μm or more in order to prevent contamination of the photoreceptor due to seepage of a plasticizer or the like from the conductive elastic body base layer and to maintain the strength of the conductive surface layer. The thickness is preferably 50 μm or less so as not to impair the elastic recovery of the elastic elastic body base layer. If the elastic recovery property of the developing roller is impaired, the image is deformed during long-term storage, and a horizontal streak image defect of the developing roller pitch occurs in the image.
[0028]
As a method for imparting an appropriate roughness to the developing roller, a rubber, a resin, an inorganic material, or the like, which is insoluble in a solvent in a paint used for forming a conductive surface layer in advance, has an average particle diameter of about 4 to 20 μm. A method in which coarse particles are blended and applied can be mentioned.
[0029]
At this time, a desired surface roughness can be obtained by controlling the average particle diameter of the roughened particles, the amount added to the paint, the coating film thickness, and the like.
[0030]
As another method, a method may be mentioned in which the surface of the conductive elastic base layer is previously roughened by polishing or the like, and then the conductive surface layer is formed by the above-described method. From the viewpoint of easy control of the surface roughness, the former method of adding coarse particles is preferable.
[0031]
The roughness of the end portion of the developing roller (the end seal contacting portion) corresponding to the portion where the end seal is in contact is, for example, the end of the developing roller rotating around the center of the conductive shaft body is replaced with a sandpaper of about # 2000. Is fixed to a flat plate and polished for a certain period of time with a load of about 1 to 10 kg to obtain a desired surface roughness. In this case, a polishing grindstone or the like can be applied, and proper roughness can be achieved by controlling the load and time.
[0032]
As another method, the end of the roller can be pressed against a hot roll or the like to smooth the roller. Furthermore, it is possible to apply another paint that is easily deformed by heat to the end of the roller with a dip, spray, brush, dispenser, etc., dry it, and press it against a hot roll etc. to smooth it. And the roughness of the hot roll.
[0033]
However, in consideration of the step after the edge processing, a method using polishing is preferable.
[0034]
Next, the developer used in the present invention will be described.
[0035]
The developer used in the present invention is a non-magnetic one-component developer having a weight average particle diameter of 4 to 10 μm, and the developer has an average circularity of from 0.950 to 0.995 due to its high fluidity. Are preferred. When a developer having an average circularity of 0.950 or more is used, it is possible to prevent end leakage with the developing roller of the present invention, and at the same time, the end seal contact portion is wider than the end seal member. In this case, the recoverability of the developer is good, the developer does not accumulate near the end of the end seal on the image forming area side, and image defects such as end fog can be prevented. .
[0036]
Although the developer used in the present invention can be produced by a pulverization method, the particles of the developer obtained by the pulverization method are generally indefinite in shape, and are preferably used for the developer used in the present invention. In order to obtain a physical property with a certain average circularity of 0.950 or more, it is necessary to further perform a mechanical / thermal or some special treatment. Therefore, the developer used in the present invention is preferably produced by a suspension polymerization method.
[0037]
In the suspension polymerization method of the developer used in the present invention, a polymerizable monomer and a colorant (and, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives) are uniformly mixed. After dissolving or dispersing into a monomer composition, the monomer composition is suspended in a continuous layer (for example, an aqueous phase) containing a dispersion stabilizer using a suitable stirrer to cause a polymerization reaction. And a developer having a desired particle size. The developer obtained by this suspension polymerization method (sometimes referred to as a polymerized developer) is used in the present invention in which the shape of each developer particle is substantially spherical and the average circularity is 0.950 or more. It satisfies the preferable physical property requirements as a developing agent.
[0038]
The weight average particle diameter of the developer can be measured using Coulter Multisizer II (trade name, manufactured by Coulter Inc.). For example, the measurement can be performed by connecting an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution to the Coulter Multisizer II and a personal computer PC9801 (manufactured by NEC, trade name).
[0039]
As an electrolytic solution used for preparing a test sample, a 1% aqueous NaCl solution obtained by dissolving reagent primary sodium chloride in water can be used. In addition, for example, ISOTONR-II (trade name, manufactured by Coulter Scientific Japan) can be used. The test sample is prepared by adding 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, as a dispersant to 100 to 150 ml of the electrolytic solution, and further adding 2 to 20 mg of a developer sample. It can be prepared by performing a dispersion treatment for 1 to 3 minutes. In the measurement of the weight average particle size by the Coulter Multisizer, a 100 μm aperture can be used as the aperture.
[0040]
In the present invention, the weight average particle diameter of the developer particles having a particle diameter of 2 μm or more is measured by measuring the volume and number of individual particles, calculating the volume distribution and the number distribution, and calculating the weight distribution (weight basis) (The representative value of the channel is set as the representative value of each channel).
[0041]
The average circularity of the developer can be used as a simple method for quantitatively expressing the shape of the particles. In the present invention, the average circularity of the developer particles is determined by a flow type particle image analyzer “FPIA-1000”. (Trade name, manufactured by Toa Medical Electronics Co., Ltd.).
[0042]
In the present invention, the average circularity was measured for a particle group of developer particles having a circle equivalent diameter of 3 μm or more, and this was defined as the average circularity. In the present invention, the measured circularity (C _i ) Is determined by the following equation (II), and as shown by the following equation (III), the value obtained by dividing the measured total circularity of all particles by the total number of particles (m) is the average circularity (C). Is defined.
[0043]
(Equation 1)

[0044]
In the above formula (II), Lr _i Represents the circumference of a circle having the same area as the area of the projected image of the particle i, and Lo _i Represents the perimeter of the projected image of the particle i.
[0045]
The flow-type particle image analyzer “FPIA-1000” used in the present invention has a circularity (C) of each particle. _i ), The average circularity (C) is calculated, and the circularity (C) of each particle is calculated. _i ), The particle group is divided into classes obtained by dividing the circularity from 0.40 to 1.00 into 61, and the average circularity is calculated using the center value of each division point and the frequency of the particles classified into each class. A calculation method for performing the calculation is used. The value of the average circularity calculated by this calculation method and the circularity (C _i ) Is directly substituted into the formula (III), and the difference from the value of the average circularity is very small and substantially negligible. Either method can be used in the present invention. . In the present invention, the average circularity measured by the flow-type particle image analyzer "FPIA-1000" is used for data handling reasons such as shortening of calculation time and simplification of calculation formula.
[0046]
As a test sample of the flow type particle image analyzer “FPIA-1000”, for example, about 5 mg of a developer is added to 10 ml of water in which about 0.1 mg of a surfactant is dissolved, and ultrasonic waves (20 kHz, 50 W) are applied for 5 minutes. Irradiated and dispersed, and those having a developer particle concentration of 5000 to 20,000 particles / μl can be used.
[0047]
The average circularity in the present invention is an index of the degree of unevenness of the developer, and is 1.000 when the developer is perfectly spherical, and the average circularity becomes smaller as the surface shape of the developer becomes more complicated. In the present invention, the reason why the circularity is measured only for the particles having a circle equivalent diameter of 3 μm or more is that the particles of the external additive which are present independently of the developer particles are included in the particles having a circle equivalent diameter of less than 3 μm. This is because a large number of groups are included, and the circularity of the developer particle group cannot be accurately estimated due to the influence.
[0048]
Next, the process cartridge and the image forming apparatus of the present invention will be described.
[0049]
FIG. 2 is a conceptual diagram illustrating an example of a process cartridge and an image forming apparatus applied to the present invention. In FIG. 2, the developing device 24 is located at a developing container 34 containing a non-magnetic toner 28 as a one-component developer and at an opening extending in the longitudinal direction in the developing container 34 and opposed to the photoconductor 21. A developing roller 25 is provided to develop and visualize the electrostatic latent image on the photoconductor 21.
[0050]
The developing roller 25 extends laterally with the substantially right half circumferential surface shown in the drawing protruding into the developing container 34 at the opening, and the left substantially half circumferential surface exposed outside the developing container 34. The surface exposed to the outside of the developing container 34 is in contact with and faces the photosensitive member 21 carrying the latent image, which is located on the left side of the developing device 24 in the drawing.
[0051]
The peripheral speed of the photoconductor 21 is 50 to 170 mm / s, and the peripheral speed of the developing roller 25 is 1 to 2 times the peripheral speed of the photoconductor.
[0052]
A metal plate such as SUS, a rubber material such as urethane or silicone, or a metal thin plate of SUS or phosphor bronze having spring elasticity is used as a base at a position above the developing roller 25. A developer regulating member 27 made of a material such as a rubber material is provided so that the vicinity of the free end is in close contact with the outer peripheral surface of the developing roller 25 by surface contact. The leading end side with respect to the contact portion is a so-called counter direction located upstream of the developing roller 25 in the rotation direction.
[0053]
The supply roller 26 is in contact with the contact portion of the developer regulating member 27 with the surface of the developing roller 25 on the upstream side in the rotation direction of the developing roller 25, and is rotatably supported. As this structure, a foamed skeleton sponge structure or a fur brush structure in which fibers such as rayon and nylon are planted on a cored bar are used to supply the developer 28 to the developing roller 25 and to peel off the undeveloped developer. It is preferable from the point of view.
[0054]
Although the above description has been given of the case where the present invention is applied to a process cartridge including a developing device that is detachable from the image forming apparatus main body, the present invention is applied to a developing device fixed in the image forming apparatus main body and configured to supply only the developer. May be. Also, a process including at least the developing device and optionally forming all or some of the photoconductor 21, the cleaning blade 30, the waste toner container 31, and the charging device 22 integrally and detachably attached to the image forming apparatus main body. You may apply to a cartridge.
[0055]
【Example】
Hereinafter, the present invention will be described in more detail by examples. In the examples, “parts” and “%” mean parts by mass and% by mass, respectively, unless otherwise specified.
[0056]
First, the developer used in this embodiment will be described.
[0057]
(Developer Production Example 1)
First, 709 parts of ion-exchanged water was added to 0.1 M-Na ₃ PO ₄ After adding 451 parts of the aqueous solution and heating to 60 ° C., 1.0M-CaCl ₂ 67.7 parts of an aqueous solution was gradually added to add Ca ₃ (PO ₄ ) ₂ Was obtained.
[0058]
80 parts of styrene monomer
20 parts of n-butyl acrylate monomer
3 parts of unsaturated polyester resin
4 parts of saturated polyester resin
The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Kakoki Co., Ltd., trade name).
[0059]
The monomer composition was heated to 60 ° C., and 6 parts of an ester wax mainly composed of behenyl behenate was added thereto, mixed and dissolved, and the polymerization initiator 2,2′-azobis (2,4-dimethyl) was added thereto. (Valeronitrile) 5 parts were dissolved.
[0060]
The polymerizable monomer system is charged into the aqueous medium, ₂ Under an atmosphere, the mixture was stirred at 10,000 rpm for 15 minutes with a TK homomixer (trade name of Tokushu Kika Kogyo Co., Ltd.) and granulated. Thereafter, the mixture was reacted at 60 ° C. for 6 hours while stirring with a paddle stirring blade. Thereafter, the liquid temperature was set to 80 ° C., and stirring was continued for another 4 hours. After the completion of the reaction, distillation was carried out at 80 ° C. for another 2 hours. ₃ (PO ₄ ) ₂ Was dissolved, filtered, washed with water and dried to obtain a developer A. The weight average particle diameter of the developer A was 10.0 μm, and the average circularity was 0.941.
[0061]
(Developer Production Example 2)
Styrene monomer 175 parts
25 parts of n-butyl acrylate monomer
15 parts of carbon black
1.6 parts of salicylic acid metal compound
Was dispersed for 5 hours using the above-mentioned attritor, and the following components were added to the mixture, followed by further dispersing for 2 hours.
[0062]
16 parts of saturated polyester (acid value: 9.8 mgKOH / g, peak molecular weight: 11000)
Ester wax 20 parts
Next, after adding 5 parts of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) to the above-mentioned dispersoid system, the mixture is put into the above-mentioned dispersion medium, and the mixture is placed under a nitrogen atmosphere at an internal temperature of 70 ° C. Granulation was performed at 15000 rpm for 15 minutes. Thereafter, the stirrer was replaced with a propeller stirrer, polymerization was performed for 5 hours while maintaining the temperature at 70 ° C. while stirring, and the internal temperature was further raised to 80 ° C. to perform polymerization for 5 hours. After completion of the polymerization, the slurry was cooled, and dilute hydrochloric acid was added to remove the dispersant. Further, it was washed with water, dried and classified to obtain colored particles.
[0063]
Hydrophobic silica (BET = 125 m) in which 100 parts of silica having a primary particle diameter of about 6 nm was treated with 20 parts of dimethyl silicone oil with respect to 100 parts of the colored particles. ² / G) 1.2 parts and hydrotalcite 0.2 parts were externally added with a Henschel mixer FM10B (Mitsui Mining Co., Ltd., trade name) to obtain a developer B.
[0064]
The weight average particle diameter of the developer B was 6.8 μm, and the average circularity was 0.980.
[0065]
The roller of each embodiment is incorporated in a process cartridge having the developing device shown in FIG. 2, and a commercially available color laser printer LBP2160 (trade name of Canon Inc.) is modified so that the process cartridge can be mounted. Was evaluated using
[0066]
(Examples 1 and 3)
Adhesive DY39-110 (Toray Dow Corning Silicone Co., Ltd., trade name) on a 250 mm long, 8 mm diameter conductive shaft (may be referred to as a core metal) obtained by applying nickel plating (KN plating) to steel material Is applied and heat treated, a core is attached to a cylindrical mold, a conductive addition type liquid dimethyl silicone material is injected, cured at 150 ° C. for 10 minutes, removed from the mold, and then removed at 200 ° C. for 4 hours. Subsequent curing was performed to form a roller having a conductive elastic base layer having a coating length of 240 mm and a diameter of 16 mm (the thickness of the conductive elastic base layer was 4 mm). Urethane beads having an average particle diameter of 10 μm as a roughened particle on this roller, 5 parts by mass of Art Pearl CF-600T (trade name of Negami Kogyo Co., Ltd.), a urethane paint binder, N5033 (trade name of Nippon Polyurethane Industry Co., Ltd.) The conductive urethane paint added to 100 parts by mass is applied by a dipping method, dried and cured at 140 ° C. for 4 hours, and then left at room temperature for one day. The conductive surface layer has a thickness of 20 μm and a surface roughness of 6 μm. A developing roller was formed. By rotating this roller, the end seal contact portion was smoothed with # 2000 sandpaper so that the ten-point roughness of the end seal contact portion was 1.5 μm, and the developing rollers of Examples 1 and 3 were cleaned. Formed.
[0067]
(Examples 2 and 4)
The developing rollers of Examples 2 and 4 were formed in the same manner as in Example 1 except that the end seal contact portion was smoothed so that the ten-point average roughness of the end seal contact portion was 3 μm.
[0068]
(Examples 5 and 7)
Urethane beads having an average particle diameter of 15 μm, Art Pearl C-400 (Negami Kogyo Co., Ltd., trade name) were used as the coarse particles, the surface roughness was 9.5 μm, and the ten-point average roughness of the end seal contact portion The developing rollers of Examples 5 and 7 were formed in the same manner as in Example 1 except that the end seal abutting portion was smoothed so as to be 2.4 μm.
[0069]
(Examples 6 and 8)
The developing rollers of Examples 6 and 8 were formed in the same manner as in Example 5 except that the end seal contacting part was smoothed so that the ten-point average roughness of the end seal contacting part was 4.7 μm. .
[0070]
(Comparative Example 1)
A developing roller of Comparative Example 1 was formed in the same manner as in Example 1 except that the end seal contact portion was smoothed so that the ten-point average roughness of the end seal contact portion was 0.5 μm.
[0071]
(Comparative Example 2)
A developing roller of Comparative Example 2 was formed in the same manner as in Example 1 except that the end seal contact portion was smoothed so that the ten-point average roughness of the end seal contact portion was 4 μm.
[0072]
(Comparative Example 3)
Using 15 parts of urethane beads having an average particle diameter of 15 μm, Art Pearl C-400 (trade name of Negami Kogyo Co., Ltd.) as coarse particles, a surface roughness of 9.5 μm, and a ten-point average of end seal contact portions A developing roller of Comparative Example 3 was formed in the same manner as in Example 1 except that the end seal contact portion was smoothed so that the roughness became 3 μm.
[0073]
Table 1 shows the results of evaluating the end leaks of the developing rollers of Examples 1 to 8 and Comparative Examples 1 to 3.
[0074]
[Table 1]

[0075]
As shown in Table 1 above, when the developing roller of the present invention was evaluated by an image forming apparatus using a process cartridge incorporating the developing roller of the present invention, no developer edge leakage occurred and the average circular shape was obtained. When a developer having a degree of 0.980 was used, edge fogging did not occur during durability, and a good image could be maintained for a long period of time.
[0076]
Further, in the developing roller of Comparative Example 1 in which the ten-point average roughness of the end seal contact portion was too small, peeling of the end of the developing roller occurred, and an image defect occurred. In the developing roller of Comparative Example 2 in which the edge roughness was too rough, the edge of the developer leaked, resulting in an image defect. In the process cartridge of Comparative Example 3 in which the developing roller and the developer type in which Rz1 / R of Comparative Example 3 had a large value were used, fog was observed from the beginning, and an image defect (NG) occurred from the beginning.
[0077]
【The invention's effect】
The developing roller of the present invention, the process cartridge of the present invention using the developing roller of the present invention, and the image forming apparatus of the present invention having the process cartridge of the present invention, even when used for a long time, do not leak the developer, A good image can be maintained, and it can be widely used in copiers, printers, faxes, and the like.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a developing roller of the present invention.
FIG. 2 is a conceptual diagram illustrating an example of a process cartridge and an image forming apparatus of the present invention.
[Explanation of symbols]
21 ... Photoconductor (photosensitive drum)
22 ... Charging device
23 ... Laser light
24 ... Developing device
25 Developing roller
25a: conductive surface layer
25b ... conductive shaft
25c: conductive elastic base layer
25d: End seal contact area
26 ... Supply roller
27: developer regulating member
28: Non-magnetic toner (developer)
29 ... Transfer roller
30 ... Cleaning blade
31 ... waste toner container
32 ... Fixing device
33 ... paper
34 developing container

Claims (4)

At least a developing roller of a developing device having a developer, a developing roller, and an end seal member disposed in pressure contact with an end of the developing roller to prevent leakage of the developer from the end of the developing roller. The roller has a conductive shaft body, a conductive elastic base layer made of a rubber material formed outside the conductive shaft body, and a conductive surface layer made of a rubber material or a resin material formed outside the conductive shaft body, When the ten-point average roughness of the image forming area on the surface of the developing roller is Rz1, and the ten-point average roughness of at least the end seal contact portion is Rz2, the relationship between Rz1 and Rz2 is 0.25 · Rz1 ≦ Rz2 ≦ 0.5 · Rz1
A developing roller, characterized in that: At least a developer, a developing roller, and an end seal member that is disposed in pressure contact with an end of the developing roller to prevent leakage of the developer from the end of the developing roller, the end seal member being detachable from the image forming apparatus main body. In the process cartridge, the developing roller has a conductive shaft, a conductive elastic base layer formed of a rubber material formed outside the shaft, and a conductive material formed of a rubber material or a resin material formed outside the conductive shaft. When the ten-point average roughness of the image forming area on the surface of the developing roller is Rz1 and at least the ten-point average roughness of the end seal contact portion is Rz2, the relationship between Rz1 and Rz2 is 0. .25 · Rz1 ≦ Rz2 ≦ 0.5 · Rz1
And when the weight average particle diameter of the developer is R, the relationship between R and Rz1 is
0.6R ≦ Rz1 ≦ 1.4R
A process cartridge. 3. The process cartridge according to claim 2, wherein the developer has an average circularity of 0.950 to 0.995. An image forming apparatus having a process cartridge, wherein the process cartridge is the process cartridge according to claim 2 or 3.

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