JP2004037786A - Electrifying member, electrophotographic device and process cartridge using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrifying member which stably holds an initial excellent electrification characteristic for a long period of time by reducing the change in a surface shape and the sticking quantity of a foreign matter due to endurance, an electrophotographic device and a process cartridge using it. <P>SOLUTION: The electrifying member possesses at least a conductive supporting body, an elastic layer provided on the conductive supporting body, and an outermost layer formed on an outermost side, and the outermost layer consists of a porous body possessing hole parts whose length (L) and diameter (D) satisfies the relation of L/D ≥ 1.1. <P>COPYRIGHT: (C)2004,JPO

Description

（ただし式中Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４は水素またはアルキル基またはヒドロキシアルキル基を示し、互いに独立でも重複しても良い。Ｘはｎ価の陰イオンであり、ｎ≧１である。）
【００４１】
中でも、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４のうち少なくとも１つがヒドロキシアルキル基（その構造中にエーテル結合を含んでいても含まなくとも良い）で他がアルキル基、かつＸは過塩素酸イオンであるものが導電性の安定性の面から特に好ましい。
【００４２】
イオン系導電性付与剤の添加量は、ゴムの種類やイオン系導電性付与剤の種類、あるいはそれらの組み合わせによって異なるが、ゴム１００質量部に対して概ね１０質量部以下、特には５質量部以下であることが好ましく、ブリード防止面から少量添加で導電性付与効果の高い組み合わせであることが望ましい。また必要に応じて、例えば、便覧ゴム・プラスチック配合薬品（１９８９年３月３０日発行、株式会社ラバーダイジェスト社）に示される材料を１種類以上添加して使用してもよい。
【００４３】
弾性層の形態としては特に制限がなくソリッドでもスポンジでも使用することができる。初期的あるいは長期的に形状の精度を強く要求される場合には安定性のあるソリッドタイプが好ましく、低コスト化の面では材料使用量の少ないスポンジタイプが適するが、いずれにしても電子写真装置との組み合わせにおいて好ましい形態を選択すればよい。
【００４４】
弾性層を製造する方法としては従来公知の方法を使用することができる。代表的な例としてはパイプ型を用いて芯金と一体に加硫成形したシームレス形状のローラを得る方法、合わせ型を用いて芯金と一体に加硫成形したのちに表面研磨してパーティングラインを除去しローラを得る方法、ゴムをチューブ状に押し出し加硫した後芯金を圧入しローラを得る方法、等がある。また加硫するエネルギー源としては、加熱が一般的であるが、電子線、紫外線、Ｘ線、マイクロウェーブ等のエネルギー線照射でも良好な結果が得られる。
【００４５】
一方、最外層に用いる導電性付与剤は電子系導電性付与剤であることが好ましく、最外層に用いる高分子化合物は水分の影響を受け難い樹脂が好ましい。つまり、最外層の高分子化合物は疎水性を有し、且つ適度な摩耗性を有する樹脂が好ましい。
【００４６】
疎水性は、ＡＳＴＭＤ５７０に準拠し２３℃／６０％ＲＨの条件で行った場合に、吸水率が１．５％以下、好ましくは１．０％以下が好ましい。
【００４７】
上記範囲に疎水性を有し、適度な摩耗性を有する樹脂としては、ウレタン結合を有する高分子化合物が望ましく、特には（メタ）アクリル酸エステルまたはスチレンを分子中に有するウレタン系高分子化合物が適する。
【００４８】
当然、高分子化合物中にイオン的な挙動を取り易い触媒残さ等の不純物の量が少ないほど好ましい。また電子系導電性付与剤としては、従来既知の電子系導電性付与剤を使用できるが、特に表面を疎水化処理した電子系導電性付与剤であれば水分や湿度の影響を受け難いので好ましく、なかでも酸化スズを用いた場合、非常に安定した耐久性を付与できるので好ましい。酸化スズとしては組成、粒径やドープの有無等で種々のものがあるが、一次粒径０．２μｍ以下のものが好ましく使用される。
【００４９】
電子系導電性付与剤の添加量は、樹脂の種類や電子系導電性付与剤の種類、あるいはそれらの組み合わせによって異なる。例えば粉体抵抗値の低い（１０^−１Ωｃｍ以下）カーボンでは、樹脂１００質量部に対して概ね２０質量部以下、望ましくは１０質量部以下が好ましく、粉体抵抗値の高い（１０^１Ωｃｍ以上）酸化スズ等の金属酸化物では、樹脂１００質量部に対して概ね２００質量部以下、望ましくは１５０質量部以下であることが好ましい。また、あまり多量に添加すると脆性が増し膜強度が低下したり、最外層形成時の成膜性が低下する、あるいは最外層形成に使用する塗料の安定性が低下するなどの問題が生じる場合があるので好ましくない。また必要に応じて、例えば、便覧ゴム・プラスチック配合薬品（１９８９年３月３０日発行、株式会社ラバーダイジェスト社）に示される材料を１種類以上添加して使用してもよい。
【００５０】
最外層が多孔質である場合、前述の通り、Ｌ／Ｄ≧１．１であれば良いが、好ましくはＬ／Ｄ≧１．２であり、一層好ましくはＬ／Ｄ≧３．０である。なお、径（Ｄ）とは、孔部の長さ方向に対して直角に切断した時の断面においてその中心を通り最も長い部分と最も短い部分の単純平均であり、孔部の径は、断面が円形を呈さない場合においても、円と同様に考えてよい。孔部の径Ｄは、最外層中の任意数の孔部における径Ｄの単純平均で表すことができる。
【００５１】
ところで、孔の形状には様々なものが有り、例えば、気泡状の形状、膜厚方向にまっすぐに形成されているものや膜内で分岐したり曲がったりしているもの等が挙げられるが、膜厚方向にまっすぐに形成されている場合、表面が摩耗しても同様の形状が次々に現れてくるので初期の形状を確保するという観点から好ましい。
【００５２】
孔部の長さは、その中心線の長さを測定して得られる。従って、分岐していたり曲まがっている場合には、膜厚よりも大きな値になることもある。特に分岐しているような場合には、複数の分岐鎖の中で最大長をもってその孔部の長さとする。また、孔部の長さは、最外層の膜厚の３０％以上、より好ましくは５０％以上であれば好ましく、１４１％以下であればなおさら好ましい。３０％より小さいと結果として球形に近くなり、また１４１％以上であるということは膜厚方向に対して孔部の傾きが４５°より大きくなるということなので、いずれの場合においても最外層が摩耗した場合初期の形状からの変化が大きくなってしまうので好ましくない。
【００５３】
さらに、孔部は最外層を貫通していてもよい。貫通している場合には一般的にはリークが発生しやすくなる可能性があるが、最外層の材質、膜厚や孔径との関係があるので必ずしも帯電特性が低下するとは限らない。しかしながら、孔径が比較的大きい場合には、保護層的な薄膜部を帯電部材に設けることが好ましい。薄膜部は最外層の下層側に最外層膜厚の３％以上の厚さであることが好ましく、より好ましくは５〜１０％程度である。
【００５４】
この薄膜部は、少なくとも帯電部材を構成する複数の層のうち最も抵抗の低い層の直上に形成すればリークに対し効果があるので好ましく、さらに最外層の直下であればより好ましい。
【００５５】
最外層に用いる多孔質体からなる多孔質膜は、種々の機能を有し、吸着材や分離膜、浸透膜、ろ過材としての機能が代表的な例として挙げられる。特に本発明のように電子写真用途に用いられる場合、揮発成分を吸着したり、下層からの染み出し物を吸着、トラップしたり、あるいは特定の気体を透過性を制御したりすることができるので、帯電部材の最外層に用いられた場合には、最外層に直接接触する部材や材料（例えば、下層に使用する材料やゴムローラ、あるいはトナー、ドラム、帯電部材クリーナ等）に使用する材料の選択肢が広がるので好ましい。
【００５６】
最外層は電子系導電性付与剤の他にも種々の目的のため様々な物質が添加されるが、添加される物質も多孔質体であれば、より一層の効果を得ることができるので好ましい。つまり、最外層表面が摩耗しても中から多孔質体が表面に現れるので、微小な表面形状や大きな表面積を一層確保しやすく、初期の形状に近い形状が連続して出現しやすくなり、その結果初期の表面特性を長期にわたって維持できることになる。
【００５７】
これら多孔質体の例としては、無機質多孔質体（例えば、活性炭、カーボンブラック、炭素や黒鉛、木炭、炭化ケイ素、シリカ、アルミナ、ゼオライト系多孔質体、粘土系多孔質体、多孔質ガラス、多孔質セラミックス、金属及び金属酸化物系多孔質体等）や有機質多孔体（例えば、木材、多孔質繊維、多孔質高分子化合物粉体や粒状物、高分子多孔質焼結体等）や複合多孔質体等を挙げることができる。
【００５８】
これらは細孔径によってサブミクロ孔マテリアル（細孔径が０．８ｎｍ以下）、ミクロ孔マテリアル（細孔径が０．８〜２ｎｍ）、メソ孔マテリアル（細孔径が２〜５０ｎｍ）、マクロ孔マテリアル（細孔径が５０ｎｍ以上）に分類される。
【００５９】
なかでも炭素は軽量、導電性、吸着力、耐熱性、耐摩耗性等種々の優れた特性を有し、細孔径が気体の分子サイズ程度のサブナノメータの超微細孔を有するものからミクロンオーダーのマクロ孔を有するものまで、種々の細孔構造が非常に発達したポーラスカーボンであることから好ましい。これらはサブミクロ孔炭素（細孔径が０．８ｎｍ以下）、ミクロ孔炭素（細孔径が０．８〜２ｎｍ）、メソ孔炭素（細孔径が２〜５０ｎｍ）、マクロ孔炭素（細孔径が５０ｎｍ以上）に分類される。代表的なものに活性炭があるが、原料や製造方法等の選択によりミクロ孔からマクロ孔まで幅広い分布を持ったものが生成し、適正な条件下では４０００ｍ^２／ｇという非常に大きな比表面積を持つものが得られ、さらには特定の条件では分子篩性を発現するものもある。
【００６０】
また、多孔質シリカ（ＳｉＯ_２）の研究も盛んであり、材料や製造条件等の検討により様々な細孔径のものが製造されており、なかでもメソ孔シリカが効果において好ましい。さらには、シリカ以外の無機材料からの合成も可能で、例えばＡｌ_２Ｏ_３、Ｎｂ_２Ｏ_５、Ｔａ_２Ｏ_５、ＴｉＯ_２、ＺｒＯ_２を始めとして種々の非シリカ系メソ孔マテリアルがある。
【００６１】
本発明の帯電部材は、上記構成による優れた表面性により、卓越した異物除去効果を有している。すなわち、一回使用したことにより表面に異物が付着している場合でも、空拭き等の簡単な手段で異物を除去できるので、初期特性をほぼ保持回復し、かつ作業性にすぐれた方法で再生することができる。さらには、異物除去のしやすさは、何回繰り返した場合でも同様の効果を得ることができるので、帯電部材の最外層がその機能を果たし得る膜厚を確保している限り何回でも繰り返し使用が可能である。
【００６２】
＜２＞本発明の電子写真装置
本発明の帯電部材は、電子写真感光体と、該電子写真感光体を所定の電位に帯電させる帯電手段と、前記電子写真感光体の帯電面に静電潜像を形成させる静電潜像形成手段と、前記電子写真感光体上に形成された静電潜像にトナーを転移させて可視化しトナー像を形成させる現像手段と、前記トナー像を転写材に転写させる転写手段とを有する画像形成装置の前記帯電手段に用いられる。
【００６３】
本発明の帯電部材は、トナーに対してストレスを与えやすい接触現像方式を採用した電子写真装置に用いることが特に好適である。
【００６４】
本発明の電子写真装置に用いる現像手段の導電性弾性部材（以下現像部材）としては、金属製の芯金とこの周面を被覆する導電性の弾性層とによって構成される公知の現像部材を用いることができる。また必要に応じて、さらに弾性層を被覆する表面層（保護層）を設けても良い。現像部材は、感光体と所定の圧力で接触し、所定の当接部を形成する。
【００６５】
本発明の帯電部材と、前記現像部材を用いる場合には、トナーの付着性と搬送性の観点から、帯電部材の十点平均粗さＲｚ（Ｒｚ１）と現像手段の導電性弾性部材の十点平均粗さＲｚ（Ｒｚ２）が、Ｒｚ１＜Ｒｚ２の関係を満たすのが好ましい。
【００６６】
具体的には、本発明の帯電部材の十点平均粗さＲｚ（Ｒｚ１）は、０．１〜７μｍが好ましい。また、本発明の電子写真装置に用いられる現像部材の十点平均粗さＲｚ（Ｒｚ２）は、１〜２０μｍが好ましい。
【００６７】
Ｒｚ１を上記範囲とするには、まず基層のＲｚを小さくすることが重要である。そのためには精密研磨やラッピング等の手法で研磨面を平滑にする方法や、無研磨で基層を形成し金型面平滑面を転写する方法、あるいは基層の上方に平滑面を有する層を形成する、等の方法がある。さらには、最外層自体の平滑性が重要である。レベリング効果を向上させる添加剤の使用、塗料に使用する溶剤の沸点や風乾時の環境制御、あるいは最外層中の添加剤（導電材やその他の添加剤）の分散性を向上する、などの方法が有効である。前記添加剤の分散性を向上するには添加剤表面の表面処理が非常に有効である。
【００６８】
また、Ｒｚ２を上記範囲とするには、適度に表面を荒らす必要がある。このような手段としては、例えば現像部材の最外層に樹脂粒子などの粗し材を添加することが有効である。
【００６９】
Ｒｚ１＜Ｒｚ２を満たすことにより、トナーへのストレスを軽減することができるので長期的な画像安定性や環境変動に対するトナーのトリボ安定性が増大するなど良好な結果を得ることができる。
【００７０】
また、帯電部材のアスカーＣ硬度（Ｈｓ１）と現像部材のアスカーＣ硬度（Ｈｓ２）が、Ｈｓ１＜Ｈｓ２の関係を満たすことが好ましい。
【００７１】
具体的には、本発明の帯電部材のアスカーＣ硬度（Ｈｓ１）は、４０〜８５°が好ましい。また、本発明の電子写真装置に用いられる導電性弾性部材のアスカーＣ硬度（Ｈｓ２）は、４５〜９０°が好ましい。
【００７２】
Ｈｓ１を上記範囲とするには、弾性層の硬度を制御することでほぼ対応できる。弾性層の硬度はゴムの種類、加硫度、補強剤や可塑剤の添加量を調整、組み合わせることにより所定の硬度に調整することができる。特に５０°以下の場合にはスポンジ化することが有効な手段である。もちろん５０°より高い場合においてもスポンジ化は可能である。さらには最外層等の被覆層の硬度を適宜制御し弾性層と適切に組み合わせることが好ましい。Ｈｓ２もＨｓ１と同様に調整することができる。
【００７３】
Ｈｓ１＜Ｈｓ２を満たすことにより、帯電部材としては安定な当接状態が確保されるだけでなく、硬度が高い現像部材と感光体との接触による振動発生を、硬度の低い帯電部材で吸収することができるため、潜像が安定し、ひいては濃度ムラ等の発生しにくい良好な画像が得られやすいという効果がある。
【００７４】
さらには、感光体の均一な帯電性と均一な現像性の観点からは、帯電部材の体積抵抗値（ρ１）と現像手段の導電性弾性部材の体積抵抗値（ρ２）が、ρ１＜ρ２の関係を満たすのが好ましい。
【００７５】
具体的には、本発明の帯電部材の体積抵抗値（ρ１）は、１×１０^３〜１×１０^１０Ωｃｍが好ましい。また、本発明の電子写真装置に用いられる導電性弾性部材の体積抵抗値（ρ２）は、１×１０^４〜１×１０^１１Ωｃｍが好ましい。
【００７６】
また、ρ１及びρ２を上記範囲とするには、目的の抵抗範囲になるように導電材の種類や添加量を調整すればよい。
【００７７】
ρ１＜ρ２を満たすことにより、現像部材から感光体表面への電荷の注入性を防止できるので、現像工程後の感光体表面電位のばらつきが少なくなり、帯電時においても感光体の均一帯電において有利ある。
【００７８】
また、帯電部材に印加する直流電圧と現像手段の導電性弾性部材に印加する直流電圧を、それぞれＶ１、Ｖ２としたときに、Ｖ１＞Ｖ２の関係を満たすことが好ましく、特には、帯電部材及び現像手段の導電性弾性部材のいずれか一方又は両方に印加する電圧が直流電圧のみである電子写真装置に用いた場合最適である。
【００７９】
Ｖ１＞Ｖ２を満たすことにより、現像部材から感光体への放電を制御又は防止でき潜像の安定性が向上するので好ましい。
【００８０】
本発明の電子写真装置に用いられる電子写真感光体、静電潜像形成手段、転写手段等は、通常の電子写真装置に用いられるものと同様のものが使用できる。
【００８１】
本発明の帯電部材を用いた電子写真装置に使用されるトナーは、特に限定はなく、さまざまな材質（例えば、バインダー、電荷制御剤、染料、顔料、助剤等）、色調（イエロー、マゼンタ、シアン、ブラック）、構造（例えば、単層あるいは複数層構成、バインダー中における種々の添加剤の存在比率や偏在の程度等）、物性（例えば、熱的、物理的、電気的、磁気的、化学的等）、表面特性（例えば、比表面積、表面硬度、極性等）、粒径（例えば、平均粒径、粒度分布等）、形状（例えば、球形、不定形等）、製法（重合による製造法、混練後粉砕する製造法、あるいはこれらを後処理した製造法等）のものを使用することができる。
【００８２】
本発明においては、本発明の帯電部材の優れた異物付着防止効果や異物脱落効果によって、従来のトナーに比して使用できる範囲が広がり、３０℃以上８０℃以下のＴｇを有するトナーを使用できる。もちろん２つ以上のＴｇを有するトナーであっても使用することができる。
【００８３】
トナーのガラス転移点温度は、高精度の内熱式入力補償型の示差走査熱量計、例えばパーキンエルマー社製のＤＳＣ−７やＴＡインスツルメンツジャパン社製のＤＳＣ２９２０を用いて、ＡＳＴＭ　Ｄ３４１８−８２に準じて測定することができる。
【００８４】
また、トナーのガラス転移点温度は、一般的には出版物ポリマーハンドブック第２版ＩＩＩ−ｐ１３９〜１９２（Ｊｏｈｎ　Ｗｉｌｅｙ＆Ｓｏｎｓ社製）に記載の理論ガラス転移温度が３０〜８０℃を示すように、トナーに用いるバインダーの構成物質（重合性単量体）を選択することにより調整することができる。
【００８５】
特に、略球状であるトナーやカラー画像用トナーを用いた場合、帯電部材表面への付着低減効果が顕著であるので好ましい。略球状のトナーの製造方法としては種々の方法があるが、例えば、粉砕後研磨により不定形のトナーを球状にする方法や重合法によって製造する方法等があり、特に重合法により製造されたトナーを用いることが最適である。
【００８６】
トナーの形態を表す指標として従来から、形状係数ＳＦ−１や形状係数ＳＦ−２が用いられいる。ＳＦ−１は粒子の丸さの度合いを示し、ＳＦ−２は粒子の凹凸の度合いを示す。本発明においては、ＳＦ−１が１００〜１５０、ＳＦ−２が１００〜１４０の範囲であることが好ましい。
【００８７】
ここで、ＳＦ−１、ＳＦ−２については、次のように計測される。すなわち、例えば日立製作所製ＦＥ−ＳＥＭ（Ｓ−８００）を用い１０００倍に拡大した２μｍ以上のトナー像を１００個無作為にサンプリングし、その画像情報はインターフェースを介してたとえばニコレ社製画像解析装置（Ｌｕｚｅｘ　　ＩＩＩ）に導入し解析を行い下式（１）、（２）より得られた値とする。
【００８８】
【数１】

【００８９】
【数２】

【００９０】
ここで、式中ＭＸＬＮＧは粒子の絶対最大長、ＰＥＲＩＭＥは粒子の周囲長、ＡＲＥＡは粒子の投影面を示す。
【００９１】
また、本発明に使用されるトナーのトリボ値としては好ましい範囲がある。すなわち、本発明の帯電部材が使用される電子写真装置において、現像手段の導電性弾性部材表面におけるトナーのトリボ値が、感光体の帯電極性と同程度の１０〜４０ｍＣ／Ｋｇの範囲であれば、安定して使用可能であることから好ましい。
【００９２】
＜３＞本発明のプロセスカートリッジ
本発明は、電子写真感光体上に形成された静電潜像をトナーを転移させて可視化してトナー像を形成し、該トナー像を転写材に転写することにより画像を形成する画像形成装置から着脱可能に構成されているプロセスカートリッジであって、電子写真感光体と、本発明の帯電部材を有する帯電手段とが一体に支持されることを特徴とするプロセスカートリッジである。
【００９３】
プロセスカートリッジに用いられる現像手段は、上述のものが使用できる。
【００９４】
本発明の帯電部材は、消耗品の補給やメンテナンス等をすることなしに、印字比率が３〜５％の画像を１００００枚以上出力するような高耐久性が要求されるプロセスカートリッジに用いることが好適である。
【００９５】
【実施例】
以下本発明を実施例を用いて説明するが、当然のことながら本発明はこれらに限定されるものではない。
【００９６】
まず本発明に使用される部材及び評価機械の構成、材質、製造方法等を説明する。なお、実施例における配合量は全て質量部を意味する。
【００９７】
＜１＞電子写真装置
（電子写真装置１）
電子写真装置１の構成は、図５に示すように電子写真プロセスを利用したカラー電子写真装置（複写機あるいはレーザビームプリンタ）であり、そこに用いられるタンデム式に配列された画像形成部の主要構成を図６に示す。
【００９８】
図６においてカラー画像形成装置は、装置本体内に例えばイエロー、シアン、マゼンタ及びブラックの可視画像を形成することができる第１〜第４の画像形成部Ｉ、ＩＩ、ＩＩＩ、ＩＶがタンデムに配列された構成を有し、各画像形成部Ｉ〜ＩＶは、図７に示されるような、それぞれ専用の光導電層を有する電子写真感光体１、帯電手段である一次帯電器２、転写手段である転写器６、現像手段である現像器４、静電潜像形成手段である露光器（不図示）等が配設されている。
【００９９】
また、各画像形成部Ｉ〜ＩＶの電子写真感光体下部には、転写ベルト駆動プーリ及び転写ベルト従動プーリに張架され駆動される転写ベルトが設けられている。さらに、図６において、第１画像形成部Ｉの右方には図に示さない給紙部が配置され、第４画像形成部ＩＶの左方には図に示さない定着器が配置される。
【０１００】
図６において、カラー画像形成を行うには、まず第１画像形成部Ｉにおいて、光導電層を有する回転する電子写真感光体に対して、一次帯電器によって均一に電荷が付与され、露光器によって露光が行われ、電子写真感光体上の光導電層上に潜像が形成される。次いで潜像が、例えばイエロートナー用現像器によって潜像が現像されて顕像が形成される。
【０１０１】
一方、給紙部から、転写ベルト駆動プーリと転写ベルト従動プーリによって駆動される転写ベルトによって、紙などの転写材（不図示）が第１画像形成部Ｉに搬送される。又、回転する電子写真感光体はその光導電層上に残存するトナーが、クリーナ（図７において８）によって除去され、新たな潜像形成に備える。
【０１０２】
第２の画像形成部ＩＩにおいても同様な工程が行われ、別色の例えばシアントナーが転写材に転写される。そしてその後もこのような工程を連続的に、第３及び第４画像形成部ＩＩＩ、ＩＶにおいても行うことにより多色のトナーの転写を転写材に対して行い、所望のカラー画像を形成することができる。このデジタル複写機を以下のようにして電子写真装置１とした。
【０１０３】
まず、解像度を１２００ｄｐｉ、プロセススピードを１２０ｍｍ／ｓ、感光体の帯電手段を接触式の導電性ローラ（帯電ローラ）とし、帯電ローラには帯電バイアスとして直流電圧−１３００Ｖを印加するようにした。なお、帯電前の前露光器は取り外してある。
【０１０４】
また、現像器は１成分ジャンピング現像から、２成分現像剤を使用可能にするために改造を行った。現像バイアスは、直流−５００Ｖとした。
【０１０５】
（電子写真装置２）
電子写真装置１の現像器を、導電性ローラ（現像ローラ）を用いた接触現像方式に変更し電子写真装置２とした。なお現像ローラの帯電バイアスは直流電圧−５００Ｖを印加するようにした。
【０１０６】
図８〜１４は、いずれも本発明の帯電部材を用いた電子写真装置の一つの実施の形態を示す概略図である。より具体的には、図８は、本発明の帯電部材を用いた中間転写方式（ベルト状）のカラー電子写真装置の一つの実施の形態を示す概略図であり、図９は、本発明の帯電部材を用いた中間転写方式（ドラム状）のカラー電子写真装置の一つの実施の形態を示す概略図であり、図１０は、本発明の帯電部材を用い、ＤＣ帯電方式／接触現像方式を採用した電子写真装置の一つの実施の形態を示す概略図であり、図１１は、本発明の帯電部材を用い、ＤＣ帯電方式／接触現像方式／クリーナレスシステムを採用した電子写真装置の一つの実施の形態を示す概略図であり、図１２は、本発明の帯電部材を用い、ＤＣ帯電方式／接触現像方式を採用した電子写真装置で帯電部材は感光体に対してカウンター方向に回転させた電子写真装置の一つの実施の形態を示す概略図であり、図１３は、本発明の帯電部材を用い、ＡＣ＋ＤＣの重畳電圧帯電方式／ジャンピング現像方式を採用した電子写真装置の一つの実施の形態を示す概略図であり、図１４は、本発明の帯電部材を用い、近接帯電方式を採用した電子写真装置の一つの実施の形態を示す概略図である。
【０１０７】
図中、１は電子写真感光体を示し、２は帯電部材を示し、３は露光光を示し、４は現像器を示し（４１はイエロー現像器、４２はマゼンタ現像器、４３はシアン現像器、４４はブラック現像器）、５は給紙ガイド（図８及び９）または転写材（図１０〜１４）を示し、Ｐは転写材（図８及び９）を示し、６は転写器を示し、７は定着器を示し、８はクリーナを示し、９はクリーニング用帯電器を示し、１１は給紙ローラを示し、２０は中間転写体を示し、２１は中間転写体用支持体を示し、２２は層を示し、６１は駆動ローラを示し、６３は２次転写器を示し、６４は従動ローラを示し、２６、２７、２８、２９は電源を示す。
【０１０８】
＜２＞電子写真感光体
（電子写真感光体製造例１）
直径３０ｍｍのアルミニウムシリンダー上に下引き層、正電荷注入防止層、電荷発生層、電荷輸送層の順に機能層を設け、電子写真感光体１を作製した。
【０１０９】
下引き層はアルミニウムドラムの欠陥等をならしたり、露光の反射によるモアレの発生を防止するために設けられている厚さ約２０μｍの導電層である。
【０１１０】
正電荷注入防止層はアルミ基体から注入された正電荷が感光体表面に帯電された負電荷を打ち消すのを防止するために設けられ、厚さ約１μｍのポリアミド樹脂によって１０^６Ωｃｍ程度に抵抗調整されている。
【０１１１】
電荷発生層はレーザ露光を受けることによって正負の電荷対を発生するために設けられた層であり、チタニルフタロシアニン系の顔料を樹脂に分散した厚さ約０．３μｍの層である。
【０１１２】
電荷輸送層はポリカーボネート樹脂にヒドラゾンを分散した厚さ２５μｍの層であり、Ｐ型半導体である。従って、感光体表面に帯電された負電荷はこの層を移動することはできず、電荷発生層で発生した正電荷のみを感光体表面に輸送することができる。
【０１１３】
電子写真感光体１の物性を測定したところ、表面の体積抵抗値（電荷輸送層単体の場合）が５×１０^１５Ωｃｍ、感光体表面のＲｚ＝２．０μｍ、静電容量Ｃ２（感光体の表面積１ｃｍ^２当たりで表す）は１００ｐＦ／ｃｍ^２であった。結果を表１に示す。
【０１１４】
なお、静電容量は以下のように測定した。
【０１１５】
アルミニウムシリンダー上にアルミシートをまきつけ、アルミシリンダー上に感光層を塗布する場合と同条件にてアルミシート上に感光層を塗布して静電容量測定用試料を作製した。静電容量の測定はインピーダンス測定器（ＹＨＰ　４１９２Ａ）で行い、感光体１ｃｍ^２当たりの静電容量を求めた。
【０１１６】
【表１】

【０１１７】
（電子写真感光体製造例２）
電荷輸送層に使用する樹脂をポリアリレート樹脂とし、厚さを１５μｍとしたこと以外は感光体製造例１と同様にして、電子写真感光体２を作製した。電子写真感光体２の特性を測定したところ、表面の体積抵抗値（電荷輸送層単体の場合）が２×１０^１５Ωｃｍ、感光体表面のＲｚ＝１．５μｍ、静電容量Ｃ２（感光体の表面積１ｃｍ^２当たりで表す）は１５０ｐＦ／ｃｍ^２であった。結果を表１に示す。
【０１１８】
＜３＞現像剤の製造
（トナー製造例１）
イオン交換水に、０．１Ｍ−Ｎａ_３ＰＯ_４水溶液と１．０Ｍ−ＣａＣｌ_２水溶液を所定量添加、攪拌し、燐酸カルシウム塩を含む水系媒体を得た。次に、下記材料を加温し、造粒機を用いて均一に溶解、分散した。
【０１１９】
・スチレン（重合性単量体）　　　　　　　　　　　　　　　　　　　　　　１００部
・ｎ−ブチルアクリレート（重合性単量体）　　　　　　　　　　　　　　　　　　　　　　　　　　　　１５部
・Ｃ．Ｉ．ピグメントブルー１５：３（シアン着色剤）　　　　　　　　　　　　　　　　　　　　　　　　　５部
・ジアルキルサリチル酸の金属化合物（荷電制御剤）　　　　　　　　　　　　　　　　　１．１部
・飽和ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　１０部
・エステル系ワックス（離型剤）　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　１５部
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）３．５部を溶解し、重合性単量体組成物を調製した。前記水系媒体中に上記重合性単量体組成物を投入し、窒素雰囲気下において、加温、攪拌し重合性単量体組成物を造粒した後、重合させた。その後残存モノマーを留去し、冷却後、塩酸を加え燐酸カルシウム塩を溶解させた後、ろ過、水洗、乾燥して得られたシアントナー粒子（Ａ−１）を風力分級して樹脂微粒子及び樹脂超微粒子の量を調製したシアントナー粒子（Ｂ）を作製した。
【０１２０】
ＳＦ−１、ＳＦ−２を測定したところ、ＳＦ−１＝１２０、ＳＦ−２＝１１０で、略球状形状であることが分かった。またコールターカウンター法によるシアントナー粒子（Ｂ）の重量平均粒径は７．１μｍであった。
【０１２１】
シアントナー粒子（Ｂ）１００部と、ＢＥＴ比表面積２２０ｍ^２／ｇの疎水性シリカ微粉体（一次平均粒径０．０１μｍ）１．１部とを混合してトナー１を調製した。
【０１２２】
トナー１のＳＦ−１＝１２０、ＳＦ−２＝１１０であり、コールターカウンター法による重量平均粒径は７．１μｍであった。さらに、トナー１のガラス転移点（Ｔｇ）を測定したところ６２℃であった。
【０１２３】
（トナー製造例２〜４）
トナー製造例１における重合性単量体組成物比や重合条件を変化させ重合度や反応度の異なるシアントナー粒子（Ａ−２）、シアントナー粒子（Ａ−３）及びシアントナー粒子（Ａ−４）を作製した。シアントナー粒子（Ａ−２）、シアントナー粒子（Ａ−３）及びシアントナー粒子（Ａ−４）をトナー製造例１と同様にしてそれぞれトナー２、トナー３、トナー４を作製した。
【０１２４】
トナー２は、ＳＦ−１＝１２０、ＳＦ−２＝１１０、重量平均粒径＝７．１μｍ、Ｔｇ＝５２℃であった。
【０１２５】
トナー３は、ＳＦ−１＝１２５、ＳＦ−２＝１１５、重量平均粒径＝７．１μｍ、Ｔｇ＝３５℃であった。
【０１２６】
トナー４は、ＳＦ−１＝１２５、ＳＦ−２＝１１０、重量平均粒径＝７．５μｍ、Ｔｇ＝７６℃であった。
【０１２７】
（トナー製造例５）
・ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　　　　　１００部
・含金属アゾ染料　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　３．０部
・低分子量ポリプロピレン　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　６．０部
・カーボンブラック　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　５．５部
上記材料を乾式混合した後に、１６２℃に設定した二軸混練押し出し機にて混練した。得られた混練物を冷却し、気流式粉砕機により微粉砕した後に風力分級して粒度分布の調整されたトナー組成物を得た。このトナー組成物を電子顕微鏡で観察したところ、粉砕トナー特有の不定形を呈していることが分かった。このトナー組成物に、疎水化処理された酸化チタン１．０質量％を外添して、重量平均粒径７．３μｍのトナー５を作製した。
【０１２８】
（現像剤製造例１〜５）
平均粒径６０μｍのニッケル亜鉛フェライトに、アクリル変性シリコーン樹脂をコートしたもの１００部に対し、トナー１〜５を８部を混合し、それぞれ現像剤１〜５とした。物性を表２に示す。
【０１２９】
【表２】

【０１３０】
＜４＞帯電部材の製造
次いで、本発明の実施例、比較例で使用する帯電部材について以下に詳述する。なお、これらの帯電部材の主要構成及び特性は表３にまとめて示す。
【０１３１】
【表３】

【０１３２】
（帯電部材製造例１）
（１−１）弾性層の作製
エピクロルヒドリンゴム（エピクロマーＣＧ、ダイソー社製）１００部、ステアリン酸１部、炭酸カルシウム５．５部、水酸化カルシウム４．４部、含水けい酸（ニプシールＶＮ３、日本シリカ社製）９部、ジエチレングリコール０．９部、ナフテン系プロセスオイル（ダイアナプロセスオイルＮＭ−２８０、出光興産社製）５部、液状ＮＢＲ（Ｎ２８０、ＪＳＲ社製）１５部、イオン系導電性付与剤としてのジメチルドデシルヒドロキシエチルアンモニウム過塩素酸塩２部を、十分冷却したニーダで混練し、ヒドリンゴムバッチを得た。
【０１３３】
これを２０℃以下に保った冷暗所で一晩熟成後、ペンタリット１部、ポリチオール系加硫剤２．３部を添加、オープンロールにて混練し、ゴムコンパウンド１を得た。
【０１３４】
次に、クロスヘッド押し出し機を用いて前記ゴムコンパウンド１をチューブ状に押し出しながら、あらかじめ導電性接着剤を塗布した、長さ４５０ｍｍ、直径８ｍｍのステンレス製芯金の周囲に導電性ゴムコンパウンド１を形成し、その後、６．０ｋｇｆ／ｃｍ^２の直接蒸気中に１時間放置することによって加硫した。
【０１３５】
加硫後、表面を精密に研磨して、平均ゴム厚さが３ｍｍ、最大外径と最小外径の差が８０μｍのクラウン形状でソリッドからなる導電性ゴムローラ１を得た。
【０１３６】
（１−２）最外層用塗料の作製
まず、表面処理酸化スズＡを次のように作製した。
【０１３７】
少量の水と加水分解用触媒を含むメタノールにγ−メタクロキシプロピルトリメトキシシラン（ＫＢＭ５０２、信越化学工業社製）を０．５質量％の濃度となるよう溶解し、表面処理液を作製する。導電性酸化スズ（表面を酸化アンチモンでドーピングした透明導電性粉末、一次粒径０．０２μｍ）をこの表面処理液に攪拌しながら３時間浸した後、ろ過して溶媒を除去した。溶媒を除去した導電性酸化スズを攪拌しながら８０℃で６時間乾燥し、さらに攪拌しながら１３５℃で６時間加熱して、表面処理導電性酸化スズＡを得た。
【０１３８】
アクリル変性ウレタン塗料（ジメチルホルムアミド（ＤＭＦ）の５質量％溶液）の樹脂分１００部に対して表面処理酸化スズＡ１０部、メソ孔活性炭（細孔径５０ｎｍ）３部をメディアを用いてペイントシェーカーで１２時間分散した。その後、メディアを分離し、硬化剤としてヘキサメチレンジイソシアネート（ＨＭＤＩ）をＯＨ／ＮＣＯ＝１／１になるように添加混合してからトルエンを用いて固形分を５質量％に調整し最外層用塗料１を作製した。
【０１３９】
（１−３）帯電部材の作製
導電性ゴムローラ１の表面を２−ブタノンにて洗浄後、γ−メルカプトプロピルトリメトキシシランの希釈溶液中で浸せき塗工にてプライマー処理した。プライマー処理の目的は、接着力向上のため及び弾性層と最外層間に極薄膜層を形成するためである。その後、最外層用塗料１を用いて浸せき塗工を行った。塗工条件は、引き上げ速度５０ｍｍ／ｓｅｃ．で上下を反転させ、繰り返し塗工を行った。最外層用塗料１を塗工後、メタノール中に浸せきし凝固させるとともに層分離を進行させ多孔質の最外層を形成し、さらに１３５℃の熱風乾燥炉で３０分加熱して、帯電部材１を作製した。
【０１４０】
（１−４）物性測定
帯電部材１について以下の項目の測定を行った。結果を表３に示す。
【０１４１】
（１）アスカーＣ硬度（Ｈｓ１）
帯電部材１あるいは導電性ローラ１のアスカーＣ硬度は、荷重１ｋｇで測定した。測定箇所は両端部及び中央部の合計３ケ所であり、これらの単純（算術）平均をもって帯電部材１のアスカーＣ硬度とした。
【０１４２】
測定の結果、左端部が６８°、中央部が６６°、右端部が６７°であり、これらの単純平均６７°を帯電部材１のアスカーＣ硬度とした。
【０１４３】
（２）体積抵抗値（ρ１）
帯電部材１の２３℃／６５％ＲＨの環境における体積抵抗値を、図４に示す装置を用い、以下のように測定、計算した。
【０１４４】
まず、帯電部材を２３℃／６５％ＲＨの環境に１２時間以上放置して十分なじませてから、その環境下で帯電部材２を金属ドラム４００に所定の荷重で押し付けた状態で、所定のスピードで回転させながら所定の電圧を印加し、流れる電流を時間の経過とともに所定時間チャートに記録する。このとき、金属ドラムの外径、荷重、印加電圧、金属ドラム及び帯電部材の回転スピード等は、帯電部材を使用する電子写真装置の条件にて行うことが望ましいが、本発明においては簡便のため、金属ドラム４００はステンレス製（表面の十点平均粗さＲｚが５μｍ以下）で、その外径が３０ｍｍ、荷重Ｗを片側５００ｇ（合計１ｋｇ）、金属ドラムの回転スピードを３０ｍｍ、帯電部材の回転は金属ドラムに従動、印加電圧を直流−５００Ｖとした。
【０１４５】
電圧印加後３０秒後の電流値を読み取り、それをＩ（Ａ）とすると、帯電部材の抵抗値Ｒ（Ω）は、Ｒ＝｜Ｖ／Ｉ｜＝｜−５００／Ｉ｜で計算される。
【０１４６】
次に、帯電部材が金属ドラムに押し付けられた時のニップ面積を適当な手段により測定し、これらの値から帯電部材の体積抵抗値を次式（３）によって計算する。
【０１４７】
【数３】
ρ１＝Ｒ×Ｓ／Ｔ　　（３）
（ρ１は帯電部材の体積抵抗値（Ωｃｍ）、Ｒは帯電部材の抵抗値（Ω）、Ｓはニップ面積（ｃｍ^２）、Ｔは帯電部材の有効厚さ（ｃｍ）を示す。）
【０１４８】
なお、帯電部材の有効厚さとは、自由状態（荷重をかけない状態）における高分子材料を主体とした層（複数の場合はそれらの合計）の肉厚あるいは繊維長のことであり、部分的に異なる場合は加重平均をもって帯電部材の有効厚さと称する。
【０１４９】
このようして帯電部材１の体積抵抗値を求めたところ、３．５×１０^５Ωｃｍであった。
【０１５０】
（３）十点平均粗さＲｚ（Ｒｚ１）
帯電部材１のＲｚの測定はＪＩＳ　Ｂ　０６０１に準拠し、（株）小坂研究所製ｓｕｒｆｃｏｒｄｅｒ　ＳＥ−３４００を用い、送り速度０．５ｍｍ／ｓ、カットオフ０．８ｍｍ、測定長２．５ｍｍの条件で測定した。測定は帯電部材の任意の３箇所について母線（長手）方向に行い、３つの値の単純平均を帯電部材１のＲｚ（Ｒｚ１）とした。なお、本実施例の帯電部材１は表面に孔が現れているので厳密な意味でＲｚではないが、本発明においては、上記方法にしたがって得られた結果をＲｚと称することとした。
【０１５１】
帯電部材１について、右端部、中央部、左端部の３箇所測定したところ、それぞれ５．２、４．７、５．１μｍであったので、これらの単純平均である５．０μｍを帯電部材１のＲｚ（Ｒｚ１）とした。
【０１５２】
（４）最外層の膜厚
帯電部材１の断面を１００倍の電子顕微鏡で観察し、任意の場所５箇所の単純平均から最外層の膜厚を求めた。その結果、それぞれ１５、１４、１５、１７、１４μｍであったので、これらの単純平均である１５μｍを膜厚とした。
【０１５３】
（５）最外層の孔径／孔部の長さ
帯電部材１の断面を１０００倍の電子顕微鏡で観察し、任意の場所５箇所の単純平均から孔径および孔部の長さを求めた。その結果、孔径は０．６０、０．５４、０．５６、０．５５、０．５０μｍであったので、これらの単純平均である０．５５μｍを孔径（Ｄ）とした。また、同様にして孔部の長さ（Ｌ）を求めたところ１８、２４、２３、１７、２０μｍであったので、これらの単純平均である２０．４μｍを孔部の長さとした。つまりＬ／Ｄ＝３７．０９である。
【０１５４】
また、断面写真をコンピュータに取り込み画像処理を行って空孔率を求めたところ１５％であった。
【０１５５】
（６）最外層の摩耗性
最外層と同一の処方にて、厚さ５００μｍ、直径１２０ｍｍのシートを作製し試料とした。このときの乾燥時間は帯電部材作製時の２倍の時間とした（温度は同じ）。この試料を用いてＪＩＳ　Ｋ　７２０４−１９９５に準じて連続５００回の試験を行った。条件は、試料を乗せる回転円盤の回転速度を６６ｍｍ、試料にかける荷重は５００ｇｆ、摩耗輪は１号平形で、ＪＩＳ　Ｒ　６２１０に準じＧＣ１５０Ｈと略称されるものを用い、試験前後の重量を１ｍｇまで正確に測定しその差を計算する。なお、測定は別個の試料を用い３回測定してそれらの差の単純平均を求め摩耗質量とした。
【０１５６】
このようにして摩耗質量を求めたところ５３ｍｇであった。
【０１５７】
（帯電部材製造例２）
（２−１）弾性層の作製
導電性ゴムローラ１を使用した。
【０１５８】
（２−２）最外層用塗料の作製
アクリル変性ウレタン塗料の濃度を１０質量％にしたこと以外は帯電部材製造例１と同様にして、最外層用塗料２を作製した。
【０１５９】
（２−３）帯電部材の作製
最外層用塗料２を用いたこと、及び塗工後メタノール中への浸せき時間を２倍にしたこと以外は、帯電部材製造例１と同様にして帯電部材２を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１６０】
（帯電部材製造例３）
（３−１）弾性層の作製
帯電部材製造例１で使用したヒドリンゴムバッチにペンタリット１部、ポリチオール系加硫剤２．５部、発泡剤としてアゾジカルボンアミド４．５部、ｐ，ｐ’−オキシビス（ベンゼンスルホニルヒドラジド）４．５部を添加、オープンロールにて混練し、ゴムコンパウンド３を得た。
【０１６１】
このゴムコンパウンド３を押し出し機を用いて、内径９ｍｍ、外径１５．３ｍｍのチューブ状に押し出し所定の長さに裁断する。次いで内径１６ｍｍの円筒状の金型に挿入（このとき、マイカ、タルク、炭酸カルシウム等の粉体を少量表面に塗ってから挿入すれば作業が容易になるので好ましい。本実施例では導電性を考慮してグラファイトを用いた）し、その中心部に長さ４５０ｍｍ、直径８ｍｍの芯金（鉄にニッケルクロムめっきを施したもの）をセットした。
【０１６２】
この状態で１７５℃の雰囲気中に６０分放置して架橋及び発泡を行ったのち金型から取り出し、表面にスキン層を有し発泡体からなる導電性ゴムローラ３を作製した。なお、断面の様子をコンピュータに取り込み画像処理をして発泡径と空孔率を調べたところ、発泡径（任意の５ヶ所の単純平均による平均孔径）は５０μｍで、空孔率は５５％であった。
【０１６３】
（３−２）最外層用塗料の作製
最外層用塗料２を使用した。
【０１６４】
（３−３）帯電部材の作製
導電性ゴムローラ２の代わりに導電性ゴムローラ３用いたこと、及び塗工後メタノール中への浸せき時間を３倍にしたこと以外は帯電部材製造例２と同様にして帯電部材３を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１６５】
（帯電部材製造例４）
（４−１）弾性層の作製
導電性ゴムローラ１を使用した。
【０１６６】
（４−２）最外層用塗料の作製
最外層用塗料１を使用した。
【０１６７】
（４−３）帯電部材の作製
塗工後メタノール中への浸せき時間を４倍にしたこと以外は帯電部材製造例１と同様にして帯電部材４を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１６８】
（帯電部材製造例５）
（５−１）弾性層の作製
導電性ゴムローラ１を使用した。
【０１６９】
（５−２）最外層用塗料の作製
ポリアミック酸溶液（混合溶媒系）の固形分１００部に対し、表面処理酸化スズＡ１０部、メソ孔シリカ（細孔径が５０ｎｍ）１．５部をメディアを用いてペイントシェーカーで１２時間分散した。その後、メディアを分離して最外層用塗料５を作製した。
【０１７０】
（５−３）帯電部材の作製
導電性ゴムローラ１を最外層用塗料５を用いてディッピングしたのち、乾燥、イミド化を行うとともに微細孔を形成して帯電部材５を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１７１】
（帯電部材製造例６）
（６−１）弾性層の作製
導電性ゴムローラ１を使用した。
【０１７２】
（６−２）最外層用塗料の作製
フェノール樹脂１００部、人工グラファイト（粒径５μｍ）１０部、表面処理酸化スズＡ１０部、導電性カーボン１部、メソ孔カーボン（細孔径が５０ｎｍ）５部、溶媒イソプロピルアルコール３００部の処方で示される原料混合物をサンドミルにて室温下で分散し、メディアを分離して最外層用塗料６を作製した。
【０１７３】
（６−３）帯電部材の作製
導電性ゴムローラ１を専用の回転装置にセットし５００ｒｐｍで回転させながら、最外層用塗料６をスプレー法によって吹き付け、導電性ゴムローラ１の表面に厚さ１５μｍに塗布し、その後塗膜を乾燥炉（温度１５０℃）にて熱硬化することにより帯電部材６を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１７４】
（帯電部材製造例７）
（７−１）弾性層の作製
導電性ゴムローラ１を使用した。
【０１７５】
（７−２）最外層用チューブの作製
スチレン−エチレンブチレン−スチレン（ＳＥＢＳ）エラストマー９０部、ポリエチレン（ＰＥ）１０部、表面処理酸化スズＡ１０部、メソ孔活性炭（細孔径が３０ｎｍ）５部、ステアリン酸亜鉛０．５部をニーダーにて溶融混練後、押し出し機にて内径１４ｍｍ、肉厚３０μｍのチューブ状に成形した。成形は公知の延伸法により、延伸速度、延伸比、温度等が適切となるよう条件を設定し、微細孔を有するチューブ７とした。
【０１７６】
（７−３）帯電部材の作製
チューブ７を、エアを適度に利用しながら導電性ローラ１に被覆した。被覆後、微細孔の大きな影響を与えない程度に７６℃で１５分間、軽く加熱し、チューブ７と導電性ローラ１の密着性を上げて、帯電部材７を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１７７】
（帯電部材製造例８）
（８−１）弾性層の作製
極高ニトリルＮＢＲ（Ｎ２１５ＳＬ、ＪＳＲ社製）４５部、高ニトリルＮＢＲ（Ｎ２２３Ｌ、ＪＳＲ社製）４５部、液状ＮＢＲ（Ｎ２８０、ＪＳＲ社製）１０部、酸化亜鉛５部、ステアリン酸１部、過塩素酸ナトリウム３部、含水シリカ（ニプシールＶＮ３、日本シリカ社製）８部、マイカ１部、ジエチレングリコール１部、２−メルカプトベンズイミダゾール０．５部、ジ（２−エチルヘキシル）フタレート（ＤＯＰ、大八化学社製）５部、ジ（２−エチルヘキシル）セバケート（サンソサイザーＤＯＳ、新日本理化社製）５部、ナフテン系オイル（ダイアナプロセスオイルＮＳ−２４、出光興産社製）５部を十分冷却したニーダーで混練し導電性ＮＢＲゴムバッチを得た。
【０１７８】
これを一晩熟成後、加硫剤として硫黄０．５部、加硫促進剤としてＮ−シクロヘキシル−２−ベンゾチアジルスルフェンアミド２．０部、ジエチルジチオカルバミン酸亜鉛１．５部、テトラブチルチウラム・ジスルフィド１．５部を添加、オープンロールにて混練し、導電性ゴムコンパウンド８を得た。
【０１７９】
次に、あらかじめ導電性接着剤を塗布した、長さ４５０ｍｍ、直径９ｍｍ（両端５０ｍｍは直径６ｍｍ）のステンレス製芯金を導電性支持体として内面が滑らかな円筒状金型の中心にセットし、その周囲に導電性ゴムコンパウンド８をインジェクションによって流し込んだ後、１７０℃の雰囲気中に６０分放置することによって加硫成形を行い、導電性支持体であるステンレス製芯金の周囲に弾性を有する層としてパーティングラインのないソリッドゴム（肉厚が３．５ｍｍ、外径１６ｍｍ、ゴム長３５０ｍｍ）が形成された導電性ゴムローラ８を作製した。
【０１８０】
（８−２）最外層用塗料の作製
最外層用塗料１を使用した。
【０１８１】
（８−３）帯電部材の作製
導電性ゴムローラ１の代わりに導電性ゴムローラ８用いたこと以外は帯電部材製造例２と同様にして帯電部材８を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１８２】
（帯電部材製造例９）
（９−１）弾性層の作製
クロロスルホン化ポリエチレンゴム（以下ＣＳＭ；ハイパロン４０、ＤｕＰｏｎｔ社製）１００部、トリフルオロメタンスルホン酸カリウム（イオン系導電性付与剤）３部、含水けい酸（ニプシールＶＮ３、日本シリカ社製）５部、ジエチレングリコール１部、ナフテン系プロセスオイル（ダイアナプロセスオイルＮＭ−２８０、出光興産社製）５部、ＤＯＰ５部、ステアリン酸１部、酸化マグネシウム６部、ペンタエリスリトール３部、ジペンタメチレンチウラムテトラスルフィド（ソクシノールＴＲＡ、住友化学社製）２部を添加、十分冷却したオープンロールで混練し、ゴムコンパウンド９を作製した。
【０１８３】
ゴムコンパウンド１の代わりにゴムコンパウンド９を使用した以外は、帯電部材製造例１と同様にして導電性ゴムローラ９を作製した。
【０１８４】
（９−２）最外層用塗料の作製
最外層用塗料１を使用した。
【０１８５】
（９−３）帯電部材の作製
導電性ゴムローラ１の代わりに導電性ゴムローラ９を用いたこと以外は、帯電部材製造例１と同様にして帯電部材９を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１８６】
（帯電部材製造例１０）
（１０−１）弾性層の作製
クロロプレンゴム（デンカクロロプレンＳ−４０、電気化学工業社製）１００部、マグネシア６部、酸化亜鉛５部、過塩素酸リチウム（イオン系導電性付与剤）５部、含水けい酸（ニプシールＶＮ３、日本シリカ社製）８部、ジエチレングリコール１部、菜種油５部、ＤＯＰ５部、ステアリン酸１部、エチレンチオウレア４部を十分冷却したオープンロールで混練し、ゴムコンパウンド１０を作製した。
【０１８７】
ゴムコンパウンド１の代わりにゴムコンパウンド１０を使用した以外は、帯電部材製造例１と同様にして導電性ゴムローラ１０を作製した。
【０１８８】
（１０−２）最外層用塗料の作製
最外層用塗料１を使用した。
【０１８９】
（１０−３）帯電部材の作製
導電性ゴムローラ１の代わりに導電性ゴムローラ１０を用いたこと以外は帯電部材製造例１と同様にして帯電部材１０を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１９０】
（帯電部材製造例１１）
（１１−１）弾性層の作製
導電性ゴムローラ１を使用した。
【０１９１】
（１１−２）最外層用塗料の作製
アクリル変性ウレタン塗料の濃度を１０質量％にし、シリコーン樹脂粒子（トレフィルＥ−５０１、東レダウコーニングシリコーン社製）を３部添加したこと以外は帯電部材製造例１と同様にして、最外層用塗料１１とした。
【０１９２】
（１１−３）帯電部材の作製
最外層用塗料１の代わりに最外層用塗料１１を用いたこと以外は帯電部材製造例１と同様にして帯電部材１を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１９３】
（帯電部材製造例１２）
（１２−１）弾性層の作製
導電性ゴムローラ１を使用した。
【０１９４】
（１２−２）最外層用塗料の作製
シリコーン樹脂粒子（トレフィルＥ−５０１、束レダウコーニングシリコーン社製）の代わりにメソカーボンマイクロビーズを５部添加したこと以外は帯電部材製造例１１と同様にして、最外層用塗料１２とした。
【０１９５】
（１２−３）帯電部材の作製
最外層用塗料１の代わりに最外層用塗料１２を用いたこと以外は帯電部材製造例１１と同様にして帯電部材１２を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１９６】
（帯電部材製造例１３）
最外層を塗工／風乾後、メタノールに浸せきすることなしに、そのままの状態で１３５℃、６０分加熱し、さらに１５０℃、３０分加熱して最外層を形成したこと以外は帯電部材製造例１と同様にして帯電部材１３を作製した。帯電部材１と同様に物性の測定を行った。結果を表３に示す。
【０１９７】
＜５＞現像部材の製造
接触現像用の現像部材として、シリコーンゴムにカーボンを加えた弾性層とナイロン樹脂にカーボンを加えた表面層とを有し、公知の方法で製造された現像ローラを準備した。現像ローラの十点平均粗さＲｚ（Ｒｚ２）は９．２μｍ、アスカーＣ硬度（Ｈｓ２）は７０°、体積抵抗値（ρ２）は１．２×１０^６Ωｃｍであった。現像部材の十点平均粗さＲｚ（Ｒｚ２）、アスカーＣ硬度（Ｈｓ２）、体積抵抗値（ρ２）は、前述した帯電部材と同様の方法で測定した。
これらを用いて行った実施例について以下に述べる。
【０１９８】
＜実施例１＞
（実施例１−１）
帯電部材１を用いて１２０００枚まで耐久を行い、初期から２０００枚毎に画像の状態をチェックした（画像はシアンの画像である）。耐久の条件は、評価モードが、５％文字原稿、Ａ４横送り、連続通紙とし、２３℃／６５％ＲＨの環境で実施した。画像評価は初期から２０００枚毎に、ハーフトーン画像（１ｄｏｔ２ｓｐａｃｅｓ）を画出しして帯電均一性を評価した。
【０１９９】
また、連続通紙１２０００枚後の帯電部材の十点平均粗さ（Ｒｚ）を測定し、初期からの変化の度合いを調査した。さらに、連続通紙１２０００枚後の帯電ローラ表面の異物付着量を測定した。異物付着量の測定は適当な手段によって帯電部材表面から異物を取り出し重量を測定し測定部の表面積で除して、単位面積当たりの付着量として求めた。
【０２００】
画像の評価のランクは、Ａ、Ｂ、Ｃ、Ｄ、Ｅで表した。Ａが最も良好な状態を示し、Ｅが最も悪い状態を意味することにした。この結果、初期、耐久を通じて良好な画像が得られた。また、耐久による帯電部材（帯電ローラ）の表面粗さ（Ｒｚ）の変化が小さいことや、帯電ローラ表面への異物付着量が小さいことが分かり、これらによってこの帯電ローラは初期の特性を耐久後もほぼ保持しているものと考えられる。
【０２０１】
すなわち、初期の良好な特性を安定的に維持することができるという、すぐれた効果が確認された。本実施例で使用した帯電部材、電子写真感光体、現像剤、電子写真装置の組み合わせと評価結果を表４に示す。
【０２０２】
（実施例１−２〜７）
帯電部材を変化させて実施例１−１と同様にして評価を行った。これらの組み合わせと評価結果を表４に示す。
【０２０３】
＜比較例１＞
帯電部材１３を用いた以外は実施例１−１と同様にして評価を行った。評価結果を表４に示す。
【０２０４】
【表４】

【０２０５】
＜実施例２＞
現像剤５の代わりに現像剤１を用い、電子写真装置１の代わりに電子写真装置２を用い、表５に示す帯電部材を用いた以外は、実施例１と同様にして評価を行った（実施例２−１〜８）。
【０２０６】
なお、画像評価に用いるハーフトーン画像を２ｄｏｔ３ｓｐａｃｅｓに変更し、それ以外は実施例１と同様とした（この場合は１ｄｏｔ２ｓｐａｃｅｓに比べ微小なムラが画像に現れやすい傾向がある）。これらの組み合わせと評価結果を表５に示す。
【０２０７】
＜比較例２＞
帯電部材１３を用いた以外は実施例２と同様にして評価を行った。評価結果を表５に示す。
【０２０８】
【表５】

【０２０９】
＜実施例３＞
現像剤５の代わりに現像剤１を用い、電子写真装置１の代わりに電子写真装置２を用い、感光体１の代わりに感光体２を用いた以外は、実施例１と同様にして評価を行った（実施例３−１〜５）。なお、画像評価に用いるハーフトーン画像を２ｄｏｔ３ｓｐａｃｅｓに変更し、それ以外は実施例１と同様とした（この場合は１ｄｏｔ２ｓｐａｃｅｓに比べ微小なムラが画像に現れやすい傾向がある）。これらの組み合わせと評価結果を表６に示す。
【０２１０】
＜比較例３＞
帯電部材１３を用いた以外は、実施例３と同様にして評価を行った。評価結果を表６に示す。
【０２１１】
【表６】

【０２１２】
＜実施例４＞
帯電部材のリサイクル性（繰り返し使用に対する安定性）について評価した（実施例４−１〜５）。なお、画像評価に用いるハーフトーン画像は実施例１と同様に１ｄｏｔ２ｓｐａｃｅｓとした。帯電部材、感光体、現像剤、電子写真装置の組み合わせとその評価結果を表７に示す。
【０２１３】
これらの結果から分かるように、本発明の帯電部材は汚れの付着量が少ないので特に清掃をせずそのままさらに使用することができる。
【０２１４】
さらに、本発明の帯電部材は付着した汚れを簡単に除去することができる。一般的に行われるような水や溶剤での洗浄や表層ごと除去して表層を再形成、といった複雑な工程を必要とせず、空拭きやエアブロー程度の簡便な手段で清掃を行うことができる。
【０２１５】
このようにして清掃した帯電部材は、当初の機能をほぼ回復しており、画像的にも良好なものが得られる。
【０２１６】
＜比較例４＞
帯電部材１３を用いた以外は、実施例４と同様にして評価を行った。評価結果を表７に示す。
【０２１７】
【表７】

【０２１８】
【発明の効果】
本発明によれば、耐久による表面形状の変化や異物の付着量が小さいので、初期の優れた帯電特性を長期にわたって安定的に保持するという、非常に優れた帯電部材及びそれを用いた装置を提供することができる。
【０２１９】
本発明の帯電部材は、特に高画質／高精細な画像を要求される電子写真装置や高速の電子写真装置、あるいは高耐久性の電子写真装置等、種々の高機能化が要求される電子写真装置においても特に好適に用いることができる。従って、６００ｄｐｉ以上（特には１２００ｄｐｉ以上）の解像度や高精細なハーフトーン画像が必要な場合、あるいは１２０ｍｍ／ｓｅｃ以上、特には１６０ｍｍ／ｓｅｃ以上のプロセススピードが必要な場合、さらには１００００枚以上、特には１２０００枚以上の画像を補給やメンテナンスを施すことなしに出力する場合等が要求される電子写真装置やそれらに用いられるプロセスカートリッジ等に適する。
【０２２０】
さらには、本発明の帯電部材は非常にリサイクル性が優れるという利点を有しており、簡便な清掃方法で、繰り返し使用可能な帯電部材を供給することができるという優れた特性を有する。
【図面の簡単な説明】
【図１】本発明の帯電部材の最外層の例を示す断面の概略図。
【図２】本発明の帯電部材の最外層の孔部の詳細図。
【図３】本発明の帯電部材の実施の形態を示す概略図。
【図４】本発明の帯電部材の体積抵抗値を測定するための機器の概略図。
【図５】本発明の帯電部材を用いたタンデム方式のカラー電子写真装置の一つの実施の形態を示す概略図。
【図６】図５のカラー電子写真装置の画像形成部の拡大図。
【図７】図６の任意の１ステーションの拡大図。
【図８】本発明の帯電部材を用いた中間転写方式（ベルト状）のカラー電子写真装置の一つの実施の形態を示す概略図。
【図９】本発明の帯電部材を用いた中間転写方式（ドラム状）のカラー電子写真装置の一つの実施の形態を示す概略図。
【図１０】本発明の帯電部材を用いた電子写真装置の一つの実施の形態を示す概略図。
【図１１】本発明の帯電部材を用いた電子写真装置の一つの実施の形態を示す概略図。
【図１２】本発明の帯電部材を用いた電子写真装置の一つの実施の形態を示す概略図。
【図１３】本発明の帯電部材を用いた電子写真装置の一つの実施の形態を示す概略図。
【図１４】本発明の帯電部材を用いた電子写真装置の一つの実施の形態を示す概略図。
【符号の説明】
１　電子写真感光体
ｔ　最外層の膜厚
２　帯電部材
２ｚ　最外層
２ｚ−１　高分子化合物部
２ｚ−２　孔部
２ｚ−３　多孔質粉体
２ａ　導電性支持体
２ｂ　弾性層
Ｌ　孔部長さ
Ｄ　孔径
３　露光
４　現像器
５　転写材
６　転写器
７　定着器
８　クリーナ
４００　金属ドラム
４０１　電源
４０２　電流計
Ｗ　荷重
Ｎ　有効長さ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a charging member used in an electrophotographic apparatus such as a copying machine, a printer, and a facsimile, an electrophotographic apparatus using the same, and a process cartridge.
[0002]
[Prior art]
Conventionally, many methods have been known as electrophotography. In general, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means (charging step). The latent image is developed with a toner to form a visible image (development step), and if necessary, a toner image is transferred to a transfer material such as paper (transfer step). The toner image is fixed (fixing step) to obtain a copy. Further, toner particles remaining on the photoreceptor without being transferred onto the transfer material are mainly removed from the photoreceptor by various means (cleaning step).
[0003]
In such an electrophotographic charging process, charging members of various shapes such as rollers, blades, brushes, belts, films, sheets, chips, etc. are used to bring the photoreceptor to a predetermined polarity and potential so that the surface of the photoreceptor has a predetermined polarity. A DC voltage or a superimposed voltage of a DC voltage and an AC voltage is applied while being opposed to (contacting or approaching) the device.
[0004]
A typical example of the charging member is a roller type charging member (charging roller). The charging roller has a configuration in which an elastic layer is provided around a support or a configuration in which a coating layer is further provided thereon. Commonly used. It is usual that rubber or an elastomer is used as a solid or sponge for the elastic layer, and a resin is used for the coating layer. The elastic layer and the coating layer are required to have conductivity. ³ ~ 1 × 10 ¹⁰ It is adjusted to the range of Ωcm.
[0005]
In order for such an electrophotographic apparatus to provide a good image over a long period from the beginning, it is important that the charging member keeps the photosensitive member uniformly charged over a long period from the beginning. In general, the surface of the charging member is worn or adhered to foreign substances during use, and various characteristics (for example, surface roughness, hardness, resistance value, etc.) that are initially set gradually change, so that the image gradually changes accordingly. In this case, an image defect occurs when a certain value is exceeded. Therefore, in order to obtain a stable image over a long period of time, it is important how to secure an initial state for a long period of time while stabilizing material properties.
[0006]
Conventionally, various approaches have been taken to solve these phenomena. For example, in order to prevent abrasion, the use of abrasion-resistant or high-toughness materials is being studied.This method can certainly prevent surface damage due to abrasion, but foreign materials adhere to the surface because it is difficult to wear. Is easily accumulated, or when a scratch is generated for some reason, the state is continued, which easily leads to an image defect.
[0007]
On the other hand, various studies have hitherto been made to prevent the adhesion of foreign matter. For example, it is common to use a low surface energy material such as the use of a fluorine material or the addition of a silicone oil.However, in the case of a fluorine material, it is soft and easily scratched, and it is hard to be cut due to its own sliding property. Not only is the above-mentioned phenomenon likely to occur, but once the particles are attached for some reason, the amount of attachment may increase at an accelerated rate. In addition, when a releasing material such as silicone oil is added, the releasing material exerts releasability by being unevenly distributed near the surface. In other words, it is considered that a bleeding motion is obtained, so that the releasability effect is secured as compared with the added amount. Therefore, there is a problem that if the surface is worn or if there is no concentration on the surface sufficient to exhibit the releasability due to the bleeding phenomenon, the adhesion of the foreign matter will proceed immediately.
[0008]
Although the conventional charging member essentially has such a problem, it may be used in an electrophotographic apparatus using a cartridge having a relatively short life, or may be affected by the accumulation of deposits. When used in an electrophotographic apparatus that applies a voltage in which an AC component is superimposed on a DC component that is difficult to output, or an electrophotographic apparatus with a small transfer residual toner amount or a toner with a small adhesion to other members (for example, a kneading type In the case of an electrophotographic apparatus or the like using a toner, a relatively high Tg toner, or a black toner), it could be used.
[0009]
With the recent spread of computers and their peripheral devices, the flow of colorization and the increase of graphic images due to diversification of values have been remarkable. As a result, electrophotographic devices such as printers, copiers, and faxes as information output means are required to have higher image quality and higher durability. Regarding high image quality, faithful reproducibility of an image is important, and there is a flow of high resolution as one of the means to cope with it. That is, how to recognize and reproduce the original image in detail, for example, a technology development from 600 dpi to 1200 dpi or more.
[0010]
On the other hand, high durability is also required. One example is that with the expansion of the global market, the number of opportunities for use in harsh environments (high-temperature, high-humidity, low-temperature, low-humidity) has increased, and the number of output sheets has also increased in terms of running cost reduction. Can be mentioned.
[0011]
When such a conventional charging member as described above is used in such an electrophotographic apparatus that requires higher image quality (or higher resolution and generally about 600 dpi or more, particularly 1200 dpi or more) and high durability, it is applied. Under certain conditions or combinations of conditions, such as the environment for outputting voltage and images, or the image pattern to be output, and the electrophotographic device to be used, the charging performance may be degraded due to the adhesion of foreign substances to the charging member surface or the portion on the charging member surface In some cases, density unevenness due to non-uniform foreign matter adhesion unevenness occurs before the originally expected number of durable sheets is reached, which causes a problem of deteriorating image quality.
[0012]
Such a phenomenon is likely to occur when using an electrophotographic apparatus that applies only a DC voltage to a charging device and outputting an image or graphic image formed in a fine black and white repetitive pattern in a low-temperature and low-humidity environment. In particular, it is likely to occur late in the life of an electrophotographic apparatus capable of outputting 10,000 sheets or more (particularly, 12,000 sheets or more) without replacing the charging member. In addition, it is particularly remarkable when the process speed is high (generally, the process speed is 100 mm / sec. Or more, particularly 120 mm / sec. Or more).
[0013]
This phenomenon is at a level that does not cause a problem in conventional electrophotographic devices. However, by improving the performance of the hardware of the electrophotographic device, it is possible to faithfully develop even the minute unevenness of the latent image, and to produce a minute image on the image. By appearing in In other words, as described above, this is a new problem that has emerged with the improvement of the hardware performance of the electrophotographic apparatus in order to cope with high image quality. It is a phenomenon.
[0014]
As described above, especially in an electrophotographic apparatus that requires high image quality and high durability, even under various conditions, minute streaks or spots of white or black or foreign matter adhered to the surface of the conductive member or a partial There is a need for a technical development of a charging member that does not cause unevenness in density due to foreign matter adhesion unevenness and has good characteristics, and an electrophotographic apparatus using the same.
[0015]
[Problems to be solved by the invention]
An object of the present invention has been made in view of the above-described problems, and is also applicable to an electrophotographic apparatus which is required to have high image quality (or high resolution and generally about 600 dpi or more, particularly 1200 dpi or more) and high durability. An object of the present invention is to provide a charging member that can be suitably used, and an electrophotographic apparatus and a process cartridge using the charging member.
[0016]
Another object of the present invention is to provide an electrophotographic apparatus in which only a DC voltage is applied to a charging member, an electrophotographic apparatus capable of outputting 10,000 sheets or more (in particular, 12,000 sheets or more) without replacing the charging member (a type using a cartridge). Or a type mounted on a main body) or a high-speed electrophotographic apparatus (process speed is generally 100 mm / sec. Or more, particularly 120 mm / sec. Or more). To provide an electrophotographic apparatus and a process cartridge.
[0017]
Still another object of the present invention is to provide a charging member capable of obtaining a good image even in a more sophisticated electrophotographic apparatus such as a cleanerless electrophotographic apparatus, an electrophotographic apparatus and a process cartridge using the same. To provide.
[0018]
In addition, another object of the present invention is to provide a charging member particularly excellent in recyclability, an electrophotographic apparatus and a process cartridge using the same.
[0019]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve these problems, and as a result, those which are easily worn have a change in surface shape (instead, the attached matter is appropriately dropped together with the wear, so that the deposited matter is hardly generated. Focusing on the fact that materials with good abrasion resistance, whose surface shape is difficult to change, have the contradictory property that deposits tend to accumulate, and it is said that a certain amount of wear is necessary to prevent deposits from accumulating. Based on the premise, the inventors found a configuration in which the surface shape is unlikely to change, and solved the problem by adopting the following configuration.
[0020]
That is, the present invention is as follows.
(1) having at least a conductive support, an elastic layer provided on the conductive support, and an outermost layer formed on the outermost side;
The charging member according to claim 1, wherein the outermost layer has a hole, and is made of a porous material having a length (L) and a diameter (D) of L / D ≧ 1.1.
(2) The charging member according to (1), wherein the porous body has an average pore diameter of 5 μm or less.
(3) The charging member according to (1) or (2), wherein the outermost layer contains at least a resin and an electronic conductivity imparting agent.
(4) The charging member according to (3), wherein the resin has a urethane bond. (5) The charging member according to any one of (1) to (4), wherein the elastic layer contains at least a rubber and an ionic conductivity imparting agent.
(6) The charging member according to (5), wherein the rubber has polarity.
(7) The charging member according to (5) or (6), wherein the rubber is epichlorohydrin rubber.
(8) an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member to a predetermined potential, electrostatic latent image forming means for forming an electrostatic latent image on a charged surface of the electrophotographic photosensitive member, An electrophotographic apparatus comprising: a developing unit that transfers a toner to an electrostatic latent image formed on an electrophotographic photosensitive member and visualizes the electrostatic latent image to form a toner image; and a transfer unit that transfers the toner image to a transfer material.
An electrophotographic apparatus, wherein the charging means has a charging member according to any one of (1) to (7).
(9) A process cartridge configured to be detachable from the image forming apparatus according to (8),
A process cartridge in which an electrophotographic photosensitive member and a charging unit having a charging member are integrally supported.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
<1> Charging member of the present invention
The charging member of the present invention has at least a conductive support, an elastic layer provided on the conductive support, and an outermost layer formed on the outermost side,
The outermost layer has a hole, and is made of a porous body having a length (L) and a diameter (D) of L / D ≧ 1.1.
[0022]
FIG. 1 is a schematic sectional view showing an example of the outermost layer of the charging member of the present invention. In FIG. 1, the outermost layer (2z) having a thickness t has a polymer compound part (2z-1) and a hole part (2z-2) in the outermost layer (2z). There is no particular limitation on the shape, size, existence state, and the like of the hole portion, and as shown in FIGS. 1A to 1F, two-dimensional or three-dimensional various modes. Can have a wide spread. In particular, in FIG. 1- (d), the outermost layer (2z) contains a porous powder (2z-3). The outermost layer is mainly composed of a polymer compound such as a resin, an elastomer, and a rubber, and is generally used by adding a material exhibiting characteristics as a charging member.
[0023]
The material exhibiting the characteristics as the charging member is not particularly limited, and an appropriate material is selected depending on the purpose. For example, a conductive agent such as carbon or a metal oxide (including a solid solution or a doped product), silica, Fillers such as mica, graphite, calcium carbonate, talc, etc., or coloring agents such as pigments and dyes, resin powders such as fluororesins, acrylic resins and polyamide resins, lubricants and leveling such as silicone oils and waxes or silicone-modified acrylic polymers And a reactive substance (for example, a coupling agent) for strengthening the interaction or bonding with the resin or these additives.
[0024]
FIG. 2 is an enlarged view showing a cross section of the charging member and a part of the outermost layer of the charging member in an enlarged manner. The outermost layer 2z has a hole having a length L and a diameter D in the layer. 2a is a conductive support and 2b is an elastic layer.
[0025]
FIG. 3 is a schematic view showing a form of the charging member of the present invention. Various shapes such as a roller shape (a, b, c, f), a drum shape (d, e), a belt shape (g), and a plate (blade) shape (h) are used. The configuration is not particularly limited as long as it has the conductive support 2a, the elastic layer 2b provided on the conductive support, and the outermost layer 2z formed on the outermost side. As the elastic layer 2b, rubber or elastomer is generally used as a sponge or solid, but may be in a brush shape as shown in FIG. Further, as shown in FIG. 3D, the outermost layer may be formed by forming an elastic layer with the porous body.
[0026]
The reason why the charging member of the present invention has an excellent foreign matter adhesion preventing effect is presumed as follows. That is, since the outermost layer is formed of a porous body and contains air in the pores, an air layer exists between the charging member and the foreign matter even if foreign matter comes into contact, preventing the close contact, or It is considered that the air layer functions as if it functions as a cushion, thereby preventing foreign matter from adhering to the surface. It is presumed that such an effect can hardly be obtained with a so-called surface roughness index as in the past.
[0027]
If the charging member of the present invention is used, even if adhesion occurs due to an electrostatic factor or other factors, the charging member easily falls off due to the influence of the air layer. Also, if a material that wears moderately is used as the polymer compound of the surface layer, foreign substances attached to the surface will fall off with wear and a new surface (that is, not stained) will appear, thus exhibiting initial characteristics. It is suitable to do. Furthermore, since the outermost layer is formed of a porous body, a new surface is preferable because it almost reproduces the initial surface shape.
[0028]
However, if the outermost layer has a low hardness such as a rubber sponge or an elastomer sponge, the abrasion becomes too large, and the durability is lowered, which is not preferable.
[0029]
The measurement of abrasion is performed in accordance with JIS K 7204-1995, "Plastic abrasion test method using abrasion wheel", and when measured under the conditions shown in Examples of the present invention, the amount of abrasion is 25 mg or more and 350 mg or less. Is preferred.
[0030]
Of course, factors that affect the abrasion include the type of the resin constituting the outermost layer, but are not determined solely. For example, the abrasion properties vary depending on the molecular weight, hardness, Tg, composition, and structure of the resin, the type and amount of the additive, the degree of crosslinking, and the type of crosslinking, and are suitable for the electrophotographic process used. It is important to appropriately set various materials and manufacturing conditions so as to obtain abrasion.
[0031]
As described above, the effect of preventing foreign matter from adhering to the charging member of the present invention depends on the air layer in the holes. Therefore, a predetermined effect can be exhibited as long as the diameter of the holes is large enough to allow gas to enter. If the pore size is too large, it is not preferable because it is embedded in the pores depending on the size of the foreign matter. It is desirable that the pore size of the porous body is smaller than the average particle size of the toner, since the toner is the most common foreign material, but the pore size is particularly preferably 5 μm or less, more preferably 1 μm or less, and particularly preferably 0.1 μm or less. 5 μm or less. Further, the smaller the pore size, the more preferable it is because the liquid and solid substances from the lower layer are less likely to penetrate due to surface tension. Naturally, the ease of penetration depends on the viscosity of the liquid and the size of the fixation. Therefore, it is more preferable to determine the pore diameter in relation to these.
[0032]
The means for making the outermost layer porous is not particularly limited, and there are various methods. For example, (1) layer conversion method (or micro-layer separation method): solution film formation method (dry film formation method, dry-wet method) (2) microporous material extraction method, (3) stretching method, (4) electron beam irradiation / etching method, (5) membrane method, wet film forming method, melt film forming method (plasticizer film forming method), etc. ) Polymer particle fusion method, (6) Cross-linking / elution method, (7) Composite film forming method (polymer coating method, monomer polymerization method, polymer surface cross-linking method, interfacial polymerization method, low-temperature plasma film forming method, filling polymerization method) And (8) a method for forming a dynamic membrane, (9) a method of arranging hollow fibers in a film thickness direction and fixing them with a binder or the like. Depending on the relation, the porous body may be formed under an optimal method and under optimal conditions.
[0033]
The conductive support used for the charging member of the present invention is not particularly limited as long as it is a good conductor of electricity, but generally includes metals such as iron, stainless steel, and aluminum, and conductive resins. From the viewpoint of versatility and cost, iron-plated products are generally used in many cases.
[0034]
The charging member of the present invention is 1 × 10 ³ ~ 1 × 10 ¹⁰ It is preferable that the layer has conductivity (volume resistance) of Ωcm, and at least the elastic layer and the outermost layer have the same volume resistance. Further, it is more preferable that the volume resistance value of the outermost layer is higher than the volume resistance value of the elastic layer by half an order or more.
[0035]
In order to obtain a charging member having the above-described volume resistance, it is preferable to adjust the resistance of both the outermost layer and the elastic layer by adding a conductivity-imparting agent to a polymer compound (resin, rubber, elastomer). The compound (resin, rubber, elastomer) and the conductivity-imparting agent are not particularly limited, and known compounds can be used. In order to maximize the effect, it is preferable that the thickness of the elastic layer is 1 to 10 mm and the thickness of the outermost layer is 1 to 500 μm.
[0036]
However, there is a preferred configuration in an electrophotographic apparatus that applies a DC voltage. In other words, from the viewpoint of uniformity of conductivity, it is preferable to use an ionic conductivity-imparting agent, but on the other hand, there is a tendency for environmental fluctuation to increase. It is a preferable configuration to use a combination used for the conductivity imparting agent.
[0037]
In such a configuration, the elastic layer preferably comprises rubber and an ionic conductivity-imparting agent, and further comprises a polymer compound having ionic behavior (that is, polar rubber) and an ionic conductivity-imparting agent. More preferred.
[0038]
The rubber used for the elastic layer is not particularly limited, and a conventionally known rubber can be used, and a polar rubber is particularly preferable. Examples of the polar rubber include nitrile rubber (NBR), chloroprene rubber (CR), chlorosulfonated polyethylene (CSM), acrylic rubber, fluorine rubber, epichlorohydrin rubber, and denatured or hydrogenated products thereof. In particular, epichlorohydrin rubber is highly preferred because it has a relatively low resistance by itself.
[0039]
As the ionic conductivity-imparting agent, conventionally known ones can be used, but a quaternary ammonium salt represented by the following structural formula is preferred from the viewpoint of versatility and easy handling.
[0040]
Embedded image

(Where R ₁ , R ₂ , R ₃ , R ₄ Represents a hydrogen, an alkyl group or a hydroxyalkyl group, and may be independent of each other or may overlap. X is an n-valent anion, where n ≧ 1. )
[0041]
Above all, R ₁ , R ₂ , R ₃ , R ₄ At least one of which is a hydroxyalkyl group (which may or may not contain an ether bond in the structure), the other is an alkyl group, and X is a perchlorate ion, from the viewpoint of conductivity stability. Particularly preferred.
[0042]
The addition amount of the ionic conductivity-imparting agent varies depending on the type of the rubber, the type of the ionic conductivity-imparting agent, or a combination thereof, but is generally about 10 parts by mass or less, particularly 5 parts by mass, per 100 parts by mass of the rubber. The combination is preferably as follows, and from the viewpoint of preventing bleeding, a combination having a high conductivity-imparting effect by adding a small amount is desirable. If necessary, for example, one or more materials shown in Handbook of Rubber / Plastic Compounding Chemicals (published March 30, 1989, Rubber Digest Co., Ltd.) may be used.
[0043]
The form of the elastic layer is not particularly limited, and a solid or sponge can be used. When high precision is required in the initial or long term, a solid type that is stable is preferable, and a sponge type that uses a small amount of material is suitable in terms of cost reduction. A preferred form may be selected in combination with the above.
[0044]
As a method for manufacturing the elastic layer, a conventionally known method can be used. A typical example is a method of obtaining a roller having a seamless shape that is vulcanized and formed integrally with a core using a pipe mold. There are a method of removing the line to obtain a roller, a method of extruding and vulcanizing rubber in a tube shape, and then press-fitting a core metal to obtain a roller. Heating is generally used as an energy source for vulcanization, but good results can be obtained by irradiation with energy rays such as electron beams, ultraviolet rays, X-rays, and microwaves.
[0045]
On the other hand, the conductivity-imparting agent used for the outermost layer is preferably an electronic conductivity-imparting agent, and the polymer compound used for the outermost layer is preferably a resin that is hardly affected by moisture. That is, the polymer compound of the outermost layer is preferably a resin having hydrophobicity and moderate abrasion.
[0046]
Hydrophobicity is preferably 1.5% or less, and more preferably 1.0% or less when subjected to 23 ° C./60% RH in accordance with ASTM D570.
[0047]
As the resin having a hydrophobic property in the above range and a suitable wear property, a polymer compound having a urethane bond is desirable, and a urethane polymer compound having a (meth) acrylate or styrene in a molecule is particularly preferable. Suitable.
[0048]
As a matter of course, it is preferable that the amount of impurities such as a catalyst residue which easily takes an ionic behavior in the polymer compound is small. In addition, as the electronic conductivity imparting agent, a conventionally known electronic conductivity imparting agent can be used, but an electron conductivity imparting agent whose surface is subjected to a hydrophobic treatment is preferably used because it is hardly affected by moisture and humidity. In particular, when tin oxide is used, very stable durability can be imparted, which is preferable. Although there are various tin oxides depending on the composition, particle diameter, presence or absence of dope, etc., those having a primary particle diameter of 0.2 μm or less are preferably used.
[0049]
The amount of the electronic conductivity imparting agent varies depending on the type of the resin, the type of the electronic conductivity imparting agent, or a combination thereof. For example, when the powder resistance value is low (10 ^-1 Ωcm or less) For carbon, the amount is preferably at most 20 parts by mass, more preferably at most 10 parts by mass with respect to 100 parts by mass of the resin. ¹ (Ωcm or more) In the case of a metal oxide such as tin oxide, the content is preferably approximately 200 parts by mass or less, more preferably 150 parts by mass or less with respect to 100 parts by mass of the resin. In addition, when added in a large amount, problems such as increased brittleness and reduced film strength, reduced film formability at the time of forming the outermost layer, or reduced stability of the paint used for forming the outermost layer may occur. Is not preferred. If necessary, for example, one or more materials shown in Handbook of Rubber / Plastic Compounding Chemicals (published March 30, 1989, Rubber Digest Co., Ltd.) may be used.
[0050]
When the outermost layer is porous, L / D ≧ 1.1 as described above, but preferably L / D ≧ 1.2, and more preferably L / D ≧ 3.0. . The diameter (D) is a simple average of the longest part and the shortest part passing through the center of the cross section when cut at a right angle to the length direction of the hole. Does not exhibit a circular shape, it may be considered in the same manner as a circle. The diameter D of the holes can be represented by a simple average of the diameters D of an arbitrary number of holes in the outermost layer.
[0051]
By the way, there are various shapes of the holes, for example, a bubble-like shape, a shape that is formed straight in the film thickness direction, a shape that is branched or bent in the film, and the like, When formed straight in the film thickness direction, similar shapes appear one after another even if the surface is worn, so that it is preferable from the viewpoint of securing the initial shape.
[0052]
The length of the hole is obtained by measuring the length of the center line. Therefore, when the light is branched or bent, the value may be larger than the film thickness. In particular, in the case of branching, the maximum length among a plurality of branched chains is defined as the length of the hole. The length of the hole is preferably at least 30%, more preferably at least 50%, even more preferably at most 141% of the thickness of the outermost layer. If it is less than 30%, it will be close to spherical as a result, and if it is more than 141%, the inclination of the hole will be greater than 45 ° with respect to the film thickness direction. In such a case, the change from the initial shape becomes large, which is not preferable.
[0053]
Further, the hole may penetrate the outermost layer. In the case where the film penetrates, there is generally a possibility that a leak is likely to occur, but the charging characteristics are not necessarily deteriorated due to the relationship with the material, thickness and hole diameter of the outermost layer. However, when the hole diameter is relatively large, it is preferable to provide a thin film portion as a protective layer on the charging member. The thin film portion preferably has a thickness of 3% or more of the outermost layer thickness below the outermost layer, more preferably about 5 to 10%.
[0054]
The thin film portion is preferably formed at least immediately above the layer having the lowest resistance among the plurality of layers constituting the charging member because it has an effect on leakage, and more preferably directly below the outermost layer.
[0055]
A porous membrane made of a porous material used for the outermost layer has various functions, and functions as an adsorbent, a separation membrane, a permeable membrane, and a filter are typical examples. Particularly when used for electrophotography as in the present invention, it is possible to adsorb volatile components, adsorb exudates from the lower layer, trap or control the permeability of specific gases, When used for the outermost layer of the charging member, the choice of materials and members to be in direct contact with the outermost layer (for example, a material used for the lower layer, a rubber roller, or a toner, a drum, a charging member cleaner, etc.) It is preferable because it spreads.
[0056]
The outermost layer is added with various substances for various purposes in addition to the electronic conductivity imparting agent. However, if the substance to be added is also a porous body, it is preferable because further effects can be obtained. . In other words, even if the outermost layer surface wears, the porous body appears on the surface from the inside, so it is easier to secure a fine surface shape and a large surface area, and a shape close to the initial shape is likely to appear continuously. As a result, the initial surface properties can be maintained for a long time.
[0057]
Examples of these porous bodies include inorganic porous bodies (for example, activated carbon, carbon black, carbon or graphite, charcoal, silicon carbide, silica, alumina, zeolite-based porous bodies, clay-based porous bodies, porous glass, Porous ceramics, metal and metal oxide-based porous materials, etc., organic porous materials (eg, wood, porous fibers, porous polymer compound powders and granules, porous polymer sintered bodies, etc.) and composites A porous body can be used.
[0058]
These are sub-micropore materials (pore diameter 0.8 nm or less), micropore materials (pore diameter 0.8 to 2 nm), mesopore materials (pore diameter 2 to 50 nm), macropore materials (pore diameter Is 50 nm or more).
[0059]
Among them, carbon has various excellent properties such as light weight, electric conductivity, adsorption power, heat resistance, abrasion resistance, etc., and the pore diameter is from sub-nanometer ultra-fine pores on the order of the molecular size of gas to micron order. It is preferable that the porous carbon has various pore structures, such as those having macropores. These include sub-microporous carbon (pore diameter 0.8 nm or less), microporous carbon (pore diameter 0.8 to 2 nm), mesoporous carbon (pore diameter 2 to 50 nm), macroporous carbon (pore diameter 50 nm or more). )are categorized. Activated carbon is a typical one, but one with a wide distribution from micropores to macropores is produced depending on the selection of raw materials and production methods, etc., and under appropriate conditions, 4000 m ² / G having a very large specific surface area, and some of them exhibit molecular sieve properties under specific conditions.
[0060]
In addition, porous silica (SiO ₂ ) Has been actively studied, and various pore diameters have been produced by examining materials, production conditions, and the like. Among them, mesoporous silica is preferable in terms of effect. Furthermore, synthesis from inorganic materials other than silica is also possible. ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , ZrO ₂ And various non-silica-based mesoporous materials.
[0061]
The charging member of the present invention has an excellent foreign matter removing effect due to the excellent surface properties of the above configuration. In other words, even if foreign matter adheres to the surface after one use, the foreign matter can be removed by simple means such as dry wiping, so that the initial characteristics can be substantially maintained and recovered, and the method can be regenerated in a manner excellent in workability. can do. Furthermore, since the same effect can be obtained even if the repetition is repeated many times, the repetition is repeated as many times as long as the outermost layer of the charging member has a film thickness capable of performing its function. Can be used.
[0062]
<2> Electrophotographic apparatus of the present invention
The charging member of the present invention includes an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member to a predetermined potential, and electrostatic latent image formation for forming an electrostatic latent image on a charged surface of the electrophotographic photosensitive member. Image forming apparatus comprising: developing means for transferring toner to an electrostatic latent image formed on the electrophotographic photosensitive member to visualize the toner image to form a toner image; and transferring means for transferring the toner image to a transfer material Used for the charging means of the device.
[0063]
The charging member of the present invention is particularly suitable for use in an electrophotographic apparatus that employs a contact development system that easily applies stress to toner.
[0064]
As the conductive elastic member (hereinafter referred to as “developing member”) of the developing means used in the electrophotographic apparatus of the present invention, a known developing member constituted by a metal core and a conductive elastic layer covering the peripheral surface thereof may be used. Can be used. If necessary, a surface layer (protective layer) covering the elastic layer may be further provided. The developing member contacts the photoconductor at a predetermined pressure to form a predetermined contact portion.
[0065]
When the charging member of the present invention and the developing member are used, the ten-point average roughness Rz (Rz1) of the charging member and the ten-point average roughness of the conductive elastic member of the developing unit are considered from the viewpoint of toner adhesion and transportability. The average roughness Rz (Rz2) preferably satisfies the relationship of Rz1 <Rz2.
[0066]
Specifically, the ten-point average roughness Rz (Rz1) of the charging member of the present invention is preferably 0.1 to 7 μm. The ten-point average roughness Rz (Rz2) of the developing member used in the electrophotographic apparatus of the present invention is preferably 1 to 20 μm.
[0067]
In order for Rz1 to fall within the above range, it is first important to reduce Rz of the base layer. For that purpose, a method of smoothing a polished surface by a method such as precision polishing or lapping, a method of forming a base layer without polishing and transferring a mold surface smooth surface, or forming a layer having a smooth surface above the base layer , Etc. Furthermore, the smoothness of the outermost layer itself is important. Methods such as the use of additives that improve the leveling effect, the control of the boiling point of the solvent used in the paint and the environment during air-drying, or the improvement of the dispersibility of additives (conductive materials and other additives) in the outermost layer Is valid. To improve the dispersibility of the additive, surface treatment of the additive surface is very effective.
[0068]
Further, in order to set Rz2 in the above range, the surface needs to be appropriately roughened. As such a means, for example, it is effective to add a roughening material such as resin particles to the outermost layer of the developing member.
[0069]
By satisfying Rz1 <Rz2, stress on the toner can be reduced, so that good results can be obtained, such as long-term image stability and increased toner tribo stability against environmental fluctuations.
[0070]
Further, it is preferable that the Asker C hardness (Hs1) of the charging member and the Asker C hardness (Hs2) of the developing member satisfy the relationship of Hs1 <Hs2.
[0071]
Specifically, the Asker C hardness (Hs1) of the charging member of the present invention is preferably 40 to 85 °. The Asker C hardness (Hs2) of the conductive elastic member used in the electrophotographic apparatus of the present invention is preferably 45 to 90 °.
[0072]
Hs1 can be almost adjusted to the above range by controlling the hardness of the elastic layer. The hardness of the elastic layer can be adjusted to a predetermined hardness by adjusting and combining the type of rubber, the degree of vulcanization, and the amount of a reinforcing agent or a plasticizer. Particularly when the angle is 50 ° or less, sponging is an effective means. Of course, sponging is possible even at a temperature higher than 50 °. Further, it is preferable to appropriately control the hardness of the coating layer such as the outermost layer, and appropriately combine the hardness with the elastic layer. Hs2 can be adjusted similarly to Hs1.
[0073]
By satisfying Hs1 <Hs2, not only a stable contact state is ensured for the charging member, but also vibration generation due to contact between the developing member having high hardness and the photoconductor is absorbed by the charging member having low hardness. Therefore, there is an effect that a latent image is stabilized and a good image in which unevenness in density or the like is hardly generated is easily obtained.
[0074]
Further, from the viewpoint of uniform charging property and uniform developing property of the photoconductor, the volume resistance value (ρ1) of the charging member and the volume resistance value (ρ2) of the conductive elastic member of the developing unit satisfy ρ1 <ρ2. Preferably, the relationship is satisfied.
[0075]
Specifically, the volume resistance value (ρ1) of the charging member of the present invention is 1 × 10 ³ ~ 1 × 10 ¹⁰ Ωcm is preferred. The volume resistivity (ρ2) of the conductive elastic member used in the electrophotographic apparatus of the present invention is 1 × 10 ⁴ ~ 1 × 10 ¹¹ Ωcm is preferred.
[0076]
Further, in order to set ρ1 and ρ2 within the above ranges, the type and amount of the conductive material may be adjusted so as to be in the target resistance range.
[0077]
By satisfying ρ1 <ρ2, it is possible to prevent charge injection from the developing member to the surface of the photoreceptor. Therefore, variation in the surface potential of the photoreceptor after the development process is reduced, and it is advantageous in uniform charging of the photoreceptor even during charging. is there.
[0078]
When the DC voltage applied to the charging member and the DC voltage applied to the conductive elastic member of the developing unit are V1 and V2, respectively, it is preferable that the relationship of V1> V2 is satisfied. It is optimal when used in an electrophotographic apparatus in which the voltage applied to one or both of the conductive elastic members of the developing means is only a DC voltage.
[0079]
By satisfying V1> V2, the discharge from the developing member to the photoconductor can be controlled or prevented, and the stability of the latent image is improved.
[0080]
As the electrophotographic photoreceptor, the electrostatic latent image forming means, the transfer means and the like used in the electrophotographic apparatus of the present invention, those similar to those used in ordinary electrophotographic apparatuses can be used.
[0081]
The toner used in the electrophotographic apparatus using the charging member of the present invention is not particularly limited, and various materials (for example, a binder, a charge control agent, a dye, a pigment, an auxiliary, and the like), and a color tone (yellow, magenta, Cyan, black), structure (for example, single-layer or multi-layer configuration, the ratio of various additives in the binder and the degree of uneven distribution), physical properties (for example, thermal, physical, electrical, magnetic, chemical) Target, surface characteristics (eg, specific surface area, surface hardness, polarity, etc.), particle size (eg, average particle size, particle size distribution, etc.), shape (eg, spherical, amorphous, etc.), production method (production method by polymerization) , Kneading and kneading, or a post-treatment of these, etc.).
[0082]
In the present invention, due to the excellent foreign matter adhesion preventing effect and foreign matter dropping effect of the charging member of the present invention, the usable range is expanded as compared with the conventional toner, and a toner having a Tg of 30 ° C. or more and 80 ° C. or less can be used. . Of course, a toner having two or more Tg can be used.
[0083]
The glass transition temperature of the toner is measured in accordance with ASTM D3418-82 using a high-precision internal heating type input compensation type differential scanning calorimeter, for example, DSC-7 manufactured by PerkinElmer or DSC2920 manufactured by TA Instruments Japan. Can be measured.
[0084]
Further, the glass transition temperature of the toner is generally set so that the theoretical glass transition temperature described in the published Polymer Handbook, 2nd edition, III-p139-192 (manufactured by John Wiley & Sons) is 30 to 80 ° C. It can be adjusted by selecting the constituent material (polymerizable monomer) of the binder used in the above.
[0085]
In particular, it is preferable to use a substantially spherical toner or a color image toner because the effect of reducing adhesion to the charging member surface is remarkable. There are various methods for producing a substantially spherical toner, for example, a method of pulverizing and shaping an amorphous toner by grinding and a method of producing the toner by a polymerization method, and in particular, a method of producing a toner by a polymerization method. It is optimal to use
[0086]
Conventionally, a shape factor SF-1 or a shape factor SF-2 has been used as an index representing the form of the toner. SF-1 indicates the degree of roundness of the particles, and SF-2 indicates the degree of irregularities of the particles. In the present invention, it is preferable that SF-1 is in the range of 100 to 150 and SF-2 is in the range of 100 to 140.
[0087]
Here, SF-1 and SF-2 are measured as follows. That is, for example, 100 toner images of 2 μm or more enlarged by 1000 times are randomly sampled by using FE-SEM (S-800) manufactured by Hitachi, Ltd. (Luzex III) and analysis is performed to obtain values obtained from the following equations (1) and (2).
[0088]
(Equation 1)

[0089]
(Equation 2)

[0090]
Here, MXLNG represents the absolute maximum length of the particle, PERIME represents the peripheral length of the particle, and AREA represents the projection surface of the particle.
[0091]
Further, there is a preferable range as the tribo value of the toner used in the present invention. That is, in the electrophotographic apparatus using the charging member of the present invention, if the tribo value of the toner on the surface of the conductive elastic member of the developing means is in the range of 10 to 40 mC / Kg, which is almost the same as the charging polarity of the photoconductor. It is preferable because it can be used stably.
[0092]
<3> Process cartridge of the present invention
The present invention relates to an image forming apparatus which forms a toner image by transferring a toner to an electrostatic latent image formed on an electrophotographic photoreceptor to form a toner image, and transfers the toner image to a transfer material to form an image. And a charging unit having the charging member of the present invention is integrally supported.
[0093]
As the developing means used in the process cartridge, those described above can be used.
[0094]
The charging member of the present invention can be used for a process cartridge requiring high durability such as outputting 10,000 or more images having a printing ratio of 3 to 5% without replenishment or maintenance of consumables. It is suitable.
[0095]
【Example】
Hereinafter, the present invention will be described with reference to examples, but it is needless to say that the present invention is not limited to these examples.
[0096]
First, the configuration, material, manufacturing method, and the like of the members and the evaluation machine used in the present invention will be described. In addition, the compounding quantity in an Example all means a mass part.
[0097]
<1> Electrophotographic device
(Electrophotographic apparatus 1)
The configuration of the electrophotographic apparatus 1 is a color electrophotographic apparatus (copying machine or laser beam printer) using an electrophotographic process as shown in FIG. 5, and the main components of an image forming unit arranged in a tandem type used therein. FIG. 6 shows the configuration.
[0098]
In FIG. 6, the color image forming apparatus includes first to fourth image forming units I, II, III, and IV capable of forming visible images of, for example, yellow, cyan, magenta, and black in a main body of the apparatus. Each of the image forming units I to IV includes an electrophotographic photosensitive member 1 having a dedicated photoconductive layer, a primary charger 2 as a charging unit, and a transfer unit as shown in FIG. A transfer unit 6, a developing unit 4 as a developing unit, an exposure unit (not shown) as an electrostatic latent image forming unit, and the like are provided.
[0099]
A transfer belt that is stretched and driven by a transfer belt driving pulley and a transfer belt driven pulley is provided below the electrophotographic photosensitive member of each of the image forming units I to IV. Further, in FIG. 6, a sheet feeding unit (not shown) is arranged on the right side of the first image forming unit I, and a fixing unit (not shown) is arranged on the left side of the fourth image forming unit IV.
[0100]
In FIG. 6, in order to form a color image, first, in the first image forming section I, an electric charge is uniformly applied to a rotating electrophotographic photosensitive member having a photoconductive layer by a primary charger, Exposure is performed to form a latent image on the photoconductive layer on the electrophotographic photoreceptor. Next, the latent image is developed by, for example, a developing device for yellow toner to form a visible image.
[0101]
On the other hand, a transfer material (not shown) such as paper is conveyed to the first image forming unit I from a paper feeding unit by a transfer belt driven by a transfer belt driving pulley and a transfer belt driven pulley. Further, the toner remaining on the photoconductive layer of the rotating electrophotographic photosensitive member is removed by a cleaner (8 in FIG. 7) to prepare for the formation of a new latent image.
[0102]
A similar process is performed in the second image forming unit II, and another color, for example, cyan toner is transferred to the transfer material. Thereafter, such a process is continuously performed in the third and fourth image forming units III and IV, so that multicolor toner is transferred to the transfer material to form a desired color image. Can be. This digital copying machine was used as an electrophotographic apparatus 1 as follows.
[0103]
First, the resolution was 1200 dpi, the process speed was 120 mm / s, the charging means of the photosensitive member was a contact-type conductive roller (charging roller), and a DC voltage of -1300 V was applied to the charging roller as a charging bias. The pre-exposure device before charging was removed.
[0104]
Further, the developing device was modified from one-component jumping development to use a two-component developer. The developing bias was DC-500V.
[0105]
(Electrophotographic equipment 2)
The developing device of the electrophotographic apparatus 1 was changed to a contact developing system using a conductive roller (developing roller) to obtain an electrophotographic apparatus 2. The charging bias of the developing roller was such that a DC voltage of -500 V was applied.
[0106]
8 to 14 are schematic diagrams each showing an embodiment of an electrophotographic apparatus using the charging member of the present invention. More specifically, FIG. 8 is a schematic diagram showing one embodiment of an intermediate transfer type (belt-shaped) color electrophotographic apparatus using the charging member of the present invention, and FIG. FIG. 10 is a schematic view showing one embodiment of an intermediate transfer type (drum-shaped) color electrophotographic apparatus using a charging member. FIG. 10 shows a DC charging type / contact development type using the charging member of the present invention. FIG. 11 is a schematic view showing one embodiment of an electrophotographic apparatus employed. FIG. 11 shows one of electrophotographic apparatuses employing a DC charging system / contact developing system / cleanerless system using a charging member of the present invention. FIG. 12 is a schematic view showing an embodiment. FIG. 12 shows an electrophotographic apparatus employing the charging member of the present invention and employing a DC charging system / contact development system, in which the charging member is rotated in the counter direction with respect to the photosensitive member. One implementation of electrophotographic equipment FIG. 13 is a schematic diagram showing one embodiment of an electrophotographic apparatus using the charging member of the present invention and employing an AC + DC superimposed voltage charging method / jumping development method. FIG. 14 is a schematic view showing one embodiment of an electrophotographic apparatus employing the charging member of the present invention and employing a proximity charging system.
[0107]
In the figure, 1 indicates an electrophotographic photosensitive member, 2 indicates a charging member, 3 indicates exposure light, and 4 indicates a developing device (41 is a yellow developing device, 42 is a magenta developing device, 43 is a cyan developing device). , 44 are black developing devices), 5 is a paper feed guide (FIGS. 8 and 9) or a transfer material (FIGS. 10 to 14), P is a transfer material (FIGS. 8 and 9), and 6 is a transfer device. , 7 indicate a fixing device, 8 indicates a cleaner, 9 indicates a cleaning charger, 11 indicates a sheet feed roller, 20 indicates an intermediate transfer member, 21 indicates an intermediate transfer member support, Reference numeral 22 indicates a layer, 61 indicates a driving roller, 63 indicates a secondary transfer unit, 64 indicates a driven roller, and 26, 27, 28, and 29 indicate power supplies.
[0108]
<2> Electrophotographic photoreceptor
(Electrophotographic photoreceptor production example 1)
A functional layer was provided on an aluminum cylinder having a diameter of 30 mm in the order of an undercoat layer, a positive charge injection preventing layer, a charge generation layer, and a charge transport layer, thereby producing an electrophotographic photoreceptor 1.
[0109]
The undercoat layer is a conductive layer having a thickness of about 20 μm, which is provided to smooth the defects of the aluminum drum and to prevent the occurrence of moire due to the reflection of exposure.
[0110]
The positive charge injection preventing layer is provided to prevent the positive charges injected from the aluminum substrate from canceling the negative charges charged on the surface of the photoreceptor, and is made of a polyamide resin having a thickness of about 1 μm. ⁶ The resistance is adjusted to about Ωcm.
[0111]
The charge generation layer is a layer provided to generate positive and negative charge pairs by receiving laser exposure, and is a layer having a thickness of about 0.3 μm in which a titanyl phthalocyanine pigment is dispersed in a resin.
[0112]
The charge transport layer is a layer having a thickness of 25 μm in which hydrazone is dispersed in a polycarbonate resin, and is a P-type semiconductor. Therefore, the negative charges charged on the photoconductor surface cannot move through this layer, and only the positive charges generated in the charge generation layer can be transported to the photoconductor surface.
[0113]
When the physical properties of the electrophotographic photoreceptor 1 were measured, the surface volume resistivity (in the case of the charge transport layer alone) was 5 × 10 ^Fifteen Ωcm, Rz of the photoconductor surface = 2.0 μm, capacitance C2 (surface area of photoconductor 1 cm ² Is 100 pF / cm ² Met. Table 1 shows the results.
[0114]
The capacitance was measured as follows.
[0115]
An aluminum sheet was spread on an aluminum cylinder, and the photosensitive layer was applied on the aluminum sheet under the same conditions as when the photosensitive layer was applied on the aluminum cylinder, to prepare a sample for capacitance measurement. The capacitance is measured with an impedance measuring device (YHP 4192A), and the photoconductor 1 cm ² Per unit capacitance was determined.
[0116]
[Table 1]

[0117]
(Electrophotographic photoreceptor production example 2)
An electrophotographic photoreceptor 2 was prepared in the same manner as in Photoreceptor Production Example 1, except that the resin used for the charge transport layer was a polyarylate resin and the thickness was 15 μm. When the characteristics of the electrophotographic photoreceptor 2 were measured, the surface volume resistivity (in the case of the charge transport layer alone) was 2 × 10 ^Fifteen Ωcm, Rz of the photoreceptor surface = 1.5 μm, capacitance C2 (photoreceptor surface area 1 cm ² Is 150 pF / cm ² Met. Table 1 shows the results.
[0118]
<3> Production of developer
(Toner Production Example 1)
0.1M-Na in ion exchange water ₃ PO ₄ Aqueous solution and 1.0 M CaCl ₂ A predetermined amount of the aqueous solution was added and stirred to obtain an aqueous medium containing calcium phosphate. Next, the following materials were heated and uniformly dissolved and dispersed using a granulator.
[0119]
・ Styrene (polymerizable monomer) 100 parts
・ 15 parts of n-butyl acrylate (polymerizable monomer)
・ C. I. Pigment Blue 15: 3 (cyan colorant) 5 parts
-Metal compound of dialkyl salicylic acid (charge control agent) 1.1 parts
・ Saturated polyester resin 10 parts
・ 15 parts of ester wax (release agent)
Into this, 3.5 parts of a polymerization initiator 2.2'-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition. The polymerizable monomer composition was charged into the aqueous medium, heated and stirred under a nitrogen atmosphere to granulate the polymerizable monomer composition, and then polymerized. Thereafter, the remaining monomer is distilled off, and after cooling, hydrochloric acid is added to dissolve the calcium phosphate salt, followed by filtration, washing with water, and drying. Cyan toner particles (B) in which the amount of ultrafine particles was adjusted were prepared.
[0120]
When SF-1 and SF-2 were measured, it was found that SF-1 = 120 and SF-2 = 110 had a substantially spherical shape. The weight average particle size of the cyan toner particles (B) determined by a Coulter counter method was 7.1 μm.
[0121]
100 parts of cyan toner particles (B) and a BET specific surface area of 220 m ² / G of hydrophobic silica fine powder (primary average particle size: 0.01 μm) was prepared.
[0122]
The toner 1 had SF-1 = 120 and SF-2 = 110, and had a weight average particle size of 7.1 μm measured by the Coulter counter method. Further, the glass transition point (Tg) of Toner 1 was measured and found to be 62 ° C.
[0123]
(Toner Production Examples 2 to 4)
Cyan toner particles (A-2), cyan toner particles (A-3), and cyan toner particles (A-) having different degrees of polymerization and reactivity by changing the polymerizable monomer composition ratio and polymerization conditions in Toner Production Example 1. 4) was produced. In the same manner as in Toner Production Example 1, toner 2, toner 3 and toner 4 were prepared for cyan toner particles (A-2), cyan toner particles (A-3) and cyan toner particles (A-4).
[0124]
Toner 2 had SF-1 = 120, SF-2 = 110, weight average particle size = 7.1 μm, and Tg = 52 ° C.
[0125]
Toner 3 had SF-1 = 125, SF-2 = 115, weight average particle size = 7.1 μm, and Tg = 35 ° C.
[0126]
Toner 4 had SF-1 = 125, SF-2 = 110, weight average particle size = 7.5 μm, and Tg = 76 ° C.
[0127]
(Toner Production Example 5)
・ 100 parts of polyester resin
・ Metallic azo dye 3.0 parts
・ Low molecular weight polypropylene 6.0 parts
・ 5.5 parts of carbon black
After the above materials were dry-mixed, they were kneaded with a twin-screw kneading extruder set at 162 ° C. The obtained kneaded material was cooled, finely pulverized by an air-flow type pulverizer, and then subjected to air classification to obtain a toner composition having an adjusted particle size distribution. When this toner composition was observed with an electron microscope, it was found that the toner composition had an irregular shape peculiar to the pulverized toner. To this toner composition, 1.0 mass% of hydrophobically treated titanium oxide was externally added to prepare a toner 5 having a weight average particle size of 7.3 μm.
[0128]
(Developer Production Examples 1 to 5)
Eight parts of toners 1 to 5 were mixed with 100 parts of nickel-zinc ferrite having an average particle size of 60 μm coated with an acrylic-modified silicone resin to prepare developers 1 to 5, respectively. Table 2 shows the physical properties.
[0129]
[Table 2]

[0130]
<4> Production of charging member
Next, the charging members used in Examples and Comparative Examples of the present invention will be described in detail below. Table 3 summarizes the main configuration and characteristics of these charging members.
[0131]
[Table 3]

[0132]
(Charging member production example 1)
(1-1) Preparation of elastic layer
100 parts of epichlorohydrin rubber (Epichromer CG, manufactured by Daiso), 1 part of stearic acid, 5.5 parts of calcium carbonate, 4.4 parts of calcium hydroxide, 9 parts of hydrous silicic acid (Nipsil VN3, manufactured by Nippon Silica Co., Ltd.), 9 parts of diethylene glycol 0 0.9 parts, 5 parts of a naphthenic process oil (Diana Process Oil NM-280, manufactured by Idemitsu Kosan Co., Ltd.), 15 parts of liquid NBR (N280, manufactured by JSR Corporation), dimethyldodecylhydroxyethylammonium peroxide as an ionic conductivity imparting agent Two parts of the chlorate were kneaded with a sufficiently cooled kneader to obtain a hydrin rubber batch.
[0133]
This was aged overnight in a cool and dark place kept at 20 ° C. or lower, and 1 part of pentalit and 2.3 parts of a polythiol-based vulcanizing agent were added and kneaded with an open roll to obtain a rubber compound 1.
[0134]
Next, while extruding the rubber compound 1 into a tube using a crosshead extruder, the conductive rubber compound 1 was coated around a stainless steel core bar having a length of 450 mm and a diameter of 8 mm to which a conductive adhesive was applied in advance. And then 6.0 kgf / cm ² Vulcanized by standing in direct steam for 1 hour.
[0135]
After vulcanization, the surface was polished precisely to obtain a crown-shaped, solid, conductive rubber roller 1 having an average rubber thickness of 3 mm and a difference between the maximum outer diameter and the minimum outer diameter of 80 μm.
[0136]
(1-2) Preparation of paint for outermost layer
First, surface-treated tin oxide A was produced as follows.
[0137]
A surface treatment liquid is prepared by dissolving γ-methacryloxypropyltrimethoxysilane (KBM502, manufactured by Shin-Etsu Chemical Co., Ltd.) to a concentration of 0.5% by mass in methanol containing a small amount of water and a hydrolysis catalyst. Conductive tin oxide (a transparent conductive powder whose surface was doped with antimony oxide, primary particle size 0.02 μm) was immersed in this surface treatment solution for 3 hours with stirring, and then filtered to remove the solvent. The conductive tin oxide from which the solvent had been removed was dried at 80 ° C. for 6 hours with stirring, and further heated at 135 ° C. for 6 hours with stirring to obtain surface-treated conductive tin oxide A.
[0138]
10 parts of surface-treated tin oxide A and 3 parts of mesoporous activated carbon (pore diameter: 50 nm) per 100 parts of a resin component of an acrylic-modified urethane paint (5% by mass solution of dimethylformamide (DMF)) were coated on a paint shaker using a medium with a medium. Time dispersed. Thereafter, the media is separated, hexamethylene diisocyanate (HMDI) as a curing agent is added and mixed so that OH / NCO = 1/1, and then the solid content is adjusted to 5% by mass with toluene, and the outermost layer paint is formed. 1 was produced.
[0139]
(1-3) Production of charging member
After the surface of the conductive rubber roller 1 was washed with 2-butanone, it was immersed in a dilute solution of γ-mercaptopropyltrimethoxysilane and subjected to primer treatment by coating. The purpose of the primer treatment is to improve the adhesive strength and to form an extremely thin layer between the elastic layer and the outermost layer. Thereafter, dip coating was performed using the coating material 1 for the outermost layer. The coating conditions were a pulling speed of 50 mm / sec. And the coating was repeated. After the outermost layer paint 1 is applied, it is immersed in methanol for coagulation and solidification, and the layers are separated to form a porous outermost layer. The porous outermost layer is further heated in a hot-air drying oven at 135 ° C. for 30 minutes to form the charging member 1. Produced.
[0140]
(1-4) Physical property measurement
The following items were measured for the charging member 1. Table 3 shows the results.
[0141]
(1) Asker C hardness (Hs1)
The Asker C hardness of the charging member 1 or the conductive roller 1 was measured under a load of 1 kg. There were a total of three locations at both ends and the center, and the simple (arithmetic) average of these was taken as the Asker C hardness of the charging member 1.
[0142]
As a result of the measurement, the left end was 68 °, the center was 66 °, and the right end was 67 °. The simple average of 67 ° was defined as Asker C hardness of the charging member 1.
[0143]
(2) Volume resistance value (ρ1)
The volume resistance of the charging member 1 in an environment of 23 ° C./65% RH was measured and calculated as follows using the apparatus shown in FIG.
[0144]
First, the charging member is left in an environment of 23 ° C./65% RH for 12 hours or more to allow sufficient adjustment, and then the charging member 2 is pressed against the metal drum 400 with a predetermined load under the environment. A predetermined voltage is applied while rotating with, and the flowing current is recorded in a predetermined time chart as time passes. At this time, the outer diameter of the metal drum, the load, the applied voltage, the rotation speed of the metal drum and the charging member, and the like are preferably performed under the conditions of the electrophotographic apparatus using the charging member. The metal drum 400 is made of stainless steel (the surface has a ten-point average roughness Rz of 5 μm or less), has an outer diameter of 30 mm, a load W of 500 g on one side (total 1 kg), a rotation speed of the metal drum of 30 mm, and a rotation of the charging member. Was driven by a metal drum, and the applied voltage was DC-500V.
[0145]
The current value 30 seconds after the application of the voltage is read, and assuming that the current value is I (A), the resistance value R (Ω) of the charging member is calculated by R = | V / I | = | −500 / I | .
[0146]
Next, the nip area when the charging member is pressed against the metal drum is measured by an appropriate means, and the volume resistance value of the charging member is calculated from these values by the following equation (3).
[0147]
[Equation 3]
ρ1 = R × S / T (3)
(Ρ1 is the volume resistance of the charging member (Ωcm), R is the resistance of the charging member (Ω), and S is the nip area (cm). ² ) And T indicate the effective thickness (cm) of the charging member. )
[0148]
The effective thickness of the charging member is a thickness or a fiber length of a layer mainly composed of a polymer material in a free state (in a state where no load is applied) (in the case of a plurality of layers, the total thereof) or a partial fiber length. , The weighted average is referred to as the effective thickness of the charging member.
[0149]
When the volume resistance value of the charging member 1 was determined in this way, it was 3.5 × 10 ⁵ Ωcm.
[0150]
(3) Ten point average roughness Rz (Rz1)
The measurement of Rz of the charging member 1 is in accordance with JIS B 0601, using a Surfcoder SE-3400 manufactured by Kosaka Laboratory Co., Ltd., under conditions of a feed rate of 0.5 mm / s, a cutoff of 0.8 mm, and a measurement length of 2.5 mm. Was measured. The measurement was performed in the generatrix (longitudinal) direction at any three points of the charging member, and a simple average of the three values was defined as Rz (Rz1) of the charging member 1. Note that the charging member 1 of this embodiment is not Rz in a strict sense because a hole appears on the surface, but in the present invention, the result obtained according to the above method is referred to as Rz.
[0151]
The charging member 1 was measured at three positions, that is, the right end, the center, and the left end, and found to be 5.2, 4.7, and 5.1 μm, respectively. Rz (Rz1).
[0152]
(4) Outermost layer thickness
The cross section of the charging member 1 was observed with an electron microscope of 100 times, and the film thickness of the outermost layer was determined from a simple average of five arbitrary locations. As a result, they were 15, 14, 15, 17, and 14 μm, respectively.
[0153]
(5) Hole diameter / hole length of outermost layer
The cross section of the charging member 1 was observed with an electron microscope at a magnification of 1000, and the pore diameter and the length of the pore were determined from a simple average of five arbitrary locations. As a result, the pore diameters were 0.60, 0.54, 0.56, 0.55, and 0.50 μm. Therefore, a simple average of 0.55 μm was determined as the pore diameter (D). When the length (L) of the hole was determined in the same manner, it was 18, 24, 23, 17, and 20 μm. Therefore, the simple average of 20.4 μm was determined as the length of the hole. That is, L / D = 37.09.
[0154]
The photograph of the cross section was taken into a computer and subjected to image processing, and the porosity was determined to be 15%.
[0155]
(6) Wearability of the outermost layer
A sheet having a thickness of 500 μm and a diameter of 120 mm was prepared using the same formulation as the outermost layer, and was used as a sample. The drying time at this time was twice as long as when the charging member was manufactured (at the same temperature). Using this sample, 500 continuous tests were performed in accordance with JIS K 7204-1995. The conditions are as follows: the rotational speed of the rotating disk on which the sample is placed is 66 mm, the load applied to the sample is 500 gf, the wear wheel is No. 1 flat type, and the abbreviation GC150H according to JIS R 6210 is used. Measure accurately and calculate the difference. In addition, the measurement was performed three times using separate samples, a simple average of the difference was obtained, and the measured value was defined as the abrasion mass.
[0156]
When the abrasion mass was determined in this way, it was 53 mg.
[0157]
(Charging member production example 2)
(2-1) Preparation of elastic layer
The conductive rubber roller 1 was used.
[0158]
(2-2) Preparation of paint for outermost layer
An outermost layer paint 2 was produced in the same manner as in the charging member production example 1 except that the concentration of the acrylic-modified urethane paint was 10% by mass.
[0159]
(2-3) Production of charging member
The charging member 2 was produced in the same manner as in the charging member production example 1, except that the outermost layer coating material 2 was used, and that the immersion time in methanol after coating was doubled. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0160]
(Charging member production example 3)
(3-1) Preparation of elastic layer
3. 1 part of pentarit, 2.5 parts of a polythiol-based vulcanizing agent, 4.5 parts of azodicarbonamide as a foaming agent, p, p'-oxybis (benzenesulfonylhydrazide) in the hydrin rubber batch used in Production Example 1 of the charging member. Five parts were added and kneaded with an open roll to obtain a rubber compound 3.
[0161]
The rubber compound 3 is extruded into a tube having an inner diameter of 9 mm and an outer diameter of 15.3 mm using an extruder, and cut into a predetermined length. Next, it is preferable to insert the material into a cylindrical mold having an inner diameter of 16 mm (at this time, it is preferable to apply a small amount of powder such as mica, talc, calcium carbonate, etc. to the surface and then insert it. In consideration of this, graphite was used), and a metal core (iron-nickel-plated iron) having a length of 450 mm and a diameter of 8 mm was set at the center.
[0162]
In this state, the substrate was left to stand in an atmosphere at 175 ° C. for 60 minutes to perform crosslinking and foaming, and then taken out of the mold to prepare a conductive rubber roller 3 having a skin layer on the surface and made of a foam. The state of the cross-section was taken into a computer and subjected to image processing to examine the foaming diameter and porosity. The foaming diameter (average pore diameter based on a simple average of five arbitrary locations) was 50 μm, and the porosity was 55%. there were.
[0163]
(3-2) Preparation of paint for outermost layer
The outermost layer paint 2 was used.
[0164]
(3-3) Production of charging member
The charging member 3 was manufactured in the same manner as in the charging member manufacturing example 2 except that the conductive rubber roller 3 was used instead of the conductive rubber roller 2 and that the immersion time in methanol after coating was tripled. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0165]
(Charging member production example 4)
(4-1) Preparation of elastic layer
The conductive rubber roller 1 was used.
[0166]
(4-2) Preparation of paint for outermost layer
The outermost layer paint 1 was used.
[0167]
(4-3) Production of charging member
The charging member 4 was produced in the same manner as in the charging member production example 1 except that the dipping time in methanol after coating was quadrupled. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0168]
(Charging member manufacturing example 5)
(5-1) Preparation of elastic layer
The conductive rubber roller 1 was used.
[0169]
(5-2) Preparation of paint for outermost layer
To 100 parts of the solid content of the polyamic acid solution (mixed solvent system), 10 parts of surface-treated tin oxide A and 1.5 parts of mesoporous silica (pore diameter: 50 nm) were dispersed for 12 hours with a paint shaker using a medium. Thereafter, the medium was separated to produce the outermost layer paint 5.
[0170]
(5-3) Production of charging member
After the conductive rubber roller 1 was dipped using the outermost layer coating material 5, drying and imidization were performed, and fine holes were formed to prepare the charging member 5. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0171]
(Charging member production example 6)
(6-1) Preparation of elastic layer
The conductive rubber roller 1 was used.
[0172]
(6-2) Preparation of paint for outermost layer
100 parts of phenolic resin, 10 parts of artificial graphite (particle size: 5 μm), 10 parts of surface-treated tin oxide, 1 part of conductive carbon, 5 parts of mesoporous carbon (pore diameter: 50 nm), and 300 parts of solvent isopropyl alcohol. The raw material mixture was dispersed at room temperature in a sand mill, and the medium was separated to prepare a paint 6 for the outermost layer.
[0173]
(6-3) Production of charging member
The outermost layer paint 6 is sprayed by a spray method while the conductive rubber roller 1 is set in a dedicated rotating device and rotated at 500 rpm, and is applied to the surface of the conductive rubber roller 1 to a thickness of 15 μm. The charging member 6 was produced by thermosetting at a temperature of 150 ° C.). Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0174]
(Charging member manufacturing example 7)
(7-1) Preparation of elastic layer
The conductive rubber roller 1 was used.
[0175]
(7-2) Preparation of tube for outermost layer
90 parts of styrene-ethylene butylene-styrene (SEBS) elastomer, 10 parts of polyethylene (PE), 10 parts of surface-treated tin oxide, 5 parts of mesoporous activated carbon (pore diameter is 30 nm), and 0.5 part of zinc stearate in a kneader. After melt-kneading, the extruder was used to form a tube having an inner diameter of 14 mm and a wall thickness of 30 μm. The molding was performed by a known stretching method by setting conditions such that the stretching speed, the stretching ratio, the temperature, and the like were appropriate, to obtain a tube 7 having micropores.
[0176]
(7-3) Production of charging member
The tube 7 was coated on the conductive roller 1 while using air appropriately. After the coating, the charging member 7 was manufactured by slightly heating at 76 ° C. for 15 minutes to such an extent that the micropores were not greatly affected, thereby increasing the adhesion between the tube 7 and the conductive roller 1. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0177]
(Charging member production example 8)
(8-1) Preparation of elastic layer
45 parts of extremely high nitrile NBR (N215SL, manufactured by JSR), 45 parts of high nitrile NBR (N223L, manufactured by JSR), 10 parts of liquid NBR (N280, manufactured by JSR), 5 parts of zinc oxide, 1 part of stearic acid, 3 parts of sodium chlorate, 8 parts of hydrous silica (Nipsil VN3, manufactured by Nippon Silica), 1 part of mica, 1 part of diethylene glycol, 0.5 part of 2-mercaptobenzimidazole, 0.5 part of di (2-ethylhexyl) phthalate (DOP, Daihachi) 5 parts of chemical (manufactured by Kagaku), 5 parts of di (2-ethylhexyl) sebacate (Sanso Sizer DOS, manufactured by Nippon Rika Co., Ltd.), and 5 parts of naphthenic oil (Diana Process Oil NS-24, manufactured by Idemitsu Kosan Co., Ltd.) were sufficiently cooled. The mixture was kneaded with a kneader to obtain a conductive NBR rubber batch.
[0178]
After aging this overnight, 0.5 part of sulfur as a vulcanizing agent, 2.0 parts of N-cyclohexyl-2-benzothiazylsulfenamide as a vulcanization accelerator, 1.5 parts of zinc diethyldithiocarbamate, tetrabutyl 1.5 parts of thiuram disulfide was added and kneaded with an open roll to obtain a conductive rubber compound 8.
[0179]
Next, a stainless steel core having a length of 450 mm and a diameter of 9 mm (both ends 50 mm and a diameter of 6 mm) coated with a conductive adhesive in advance is set at the center of a cylindrical mold having a smooth inner surface as a conductive support, After injecting the conductive rubber compound 8 around it by injection, it is vulcanized by leaving it in an atmosphere at 170 ° C. for 60 minutes to form a layer having elasticity around a stainless steel core serving as a conductive support. As a result, a conductive rubber roller 8 formed with solid rubber (part thickness: 3.5 mm, outer diameter: 16 mm, rubber length: 350 mm) without a parting line was produced.
[0180]
(8-2) Preparation of paint for outermost layer
The outermost layer paint 1 was used.
[0181]
(8-3) Production of charging member
The charging member 8 was manufactured in the same manner as in the charging member manufacturing example 2 except that the conductive rubber roller 8 was used instead of the conductive rubber roller 1. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0182]
(Example 9 of charging member production)
(9-1) Preparation of elastic layer
100 parts of chlorosulfonated polyethylene rubber (hereinafter CSM; Hypalon 40, manufactured by DuPont), 3 parts of potassium trifluoromethanesulfonate (ionic conductivity imparting agent), 5 parts of hydrous silicic acid (Nipsil VN3, manufactured by Nippon Silica), 1 part of diethylene glycol, 5 parts of naphthenic process oil (Diana process oil NM-280, manufactured by Idemitsu Kosan Co., Ltd.), 5 parts of DOP, 1 part of stearic acid, 6 parts of magnesium oxide, 3 parts of pentaerythritol, dipentamethylene thiuram tetrasulfide (succinol) TRA, manufactured by Sumitomo Chemical Co., Ltd.) and kneaded with a sufficiently cooled open roll to prepare a rubber compound 9.
[0183]
A conductive rubber roller 9 was manufactured in the same manner as in the charging member manufacturing example 1 except that the rubber compound 9 was used instead of the rubber compound 1.
[0184]
(9-2) Preparation of paint for outermost layer
The outermost layer paint 1 was used.
[0185]
(9-3) Production of charging member
The charging member 9 was manufactured in the same manner as in the charging member manufacturing example 1 except that the conductive rubber roller 9 was used instead of the conductive rubber roller 1. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0186]
(Charging member production example 10)
(10-1) Production of elastic layer
100 parts of chloroprene rubber (Denka chloroprene S-40, manufactured by Denki Kagaku Kogyo KK), 6 parts of magnesia, 5 parts of zinc oxide, 5 parts of lithium perchlorate (ionic conductivity imparting agent), hydrated silicic acid (Nipsil VN3, Japan) 8 parts of Silica Co., 1 part of diethylene glycol, 5 parts of rapeseed oil, 5 parts of DOP, 1 part of stearic acid, and 4 parts of ethylene thiourea were kneaded with a sufficiently cooled open roll to prepare a rubber compound 10.
[0187]
A conductive rubber roller 10 was produced in the same manner as in the charging member production example 1 except that the rubber compound 10 was used instead of the rubber compound 1.
[0188]
(10-2) Preparation of paint for outermost layer
The outermost layer paint 1 was used.
[0189]
(10-3) Production of charging member
The charging member 10 was manufactured in the same manner as in the charging member manufacturing example 1 except that the conductive rubber roller 10 was used instead of the conductive rubber roller 1. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0190]
(Charging member production example 11)
(11-1) Preparation of elastic layer
The conductive rubber roller 1 was used.
[0191]
(11-2) Preparation of paint for outermost layer
The outermost layer paint was prepared in the same manner as in the charging member production example 1 except that the concentration of the acrylic-modified urethane paint was 10% by mass, and 3 parts of silicone resin particles (Trefil E-501, manufactured by Toray Dow Corning Silicone Co., Ltd.) were added. 11 was set.
[0192]
(11-3) Production of charging member
The charging member 1 was manufactured in the same manner as in the charging member manufacturing example 1 except that the outermost layer coating material 11 was used instead of the outermost layer coating material 1. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0193]
(Charging member production example 12)
(12-1) Preparation of elastic layer
The conductive rubber roller 1 was used.
[0194]
(12-2) Preparation of paint for outermost layer
An outermost layer coating material 12 was obtained in the same manner as in the charging member production example 11 except that 5 parts of mesocarbon microbeads were added instead of the silicone resin particles (Trefil E-501, manufactured by Bundled Red Corning Silicone Co., Ltd.).
[0195]
(12-3) Production of charging member
The charging member 12 was produced in the same manner as in the charging member production example 11 except that the outermost layer coating material 12 was used instead of the outermost layer coating material 1. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0196]
(Charging member production example 13)
Example of manufacturing a charging member except that the outermost layer was coated / air-dried, then heated at 135 ° C. for 60 minutes without immersion in methanol, and further heated at 150 ° C. for 30 minutes to form the outermost layer. In the same manner as in Example 1, a charging member 13 was produced. Physical properties were measured in the same manner as the charging member 1. Table 3 shows the results.
[0197]
<5> Development member development
As a developing member for contact development, a developing roller having an elastic layer obtained by adding carbon to silicone rubber and a surface layer obtained by adding carbon to nylon resin and manufactured by a known method was prepared. The ten-point average roughness Rz (Rz2) of the developing roller is 9.2 μm, the Asker C hardness (Hs2) is 70 °, and the volume resistance value (ρ2) is 1.2 × 10 ⁶ Ωcm. The ten-point average roughness Rz (Rz2), Asker C hardness (Hs2), and volume resistance value (ρ2) of the developing member were measured in the same manner as the charging member described above.
Examples performed using these will be described below.
[0198]
<Example 1>
(Example 1-1)
Using the charging member 1, durability was performed up to 12,000 sheets, and the state of the image was checked every 2,000 sheets from the beginning (the image is a cyan image). The durability was evaluated in an environment of 23 ° C./65% RH in an evaluation mode of 5% character original, A4 landscape feed, continuous paper feed. In the image evaluation, a halftone image (1 dot 2 spaces) was imaged every 2000 sheets from the beginning to evaluate the charging uniformity.
[0199]
Further, the ten-point average roughness (Rz) of the charging member after 12,000 continuous paper passes was measured, and the degree of change from the initial stage was investigated. Further, the amount of foreign matter adhered to the surface of the charging roller after 12,000 continuous paper passes was measured. The amount of adhered foreign matter was measured by taking out foreign matter from the surface of the charging member by an appropriate means, measuring the weight, dividing the weight by the surface area of the measuring section, and obtaining the amount of adhered matter per unit area.
[0200]
The rank of the image evaluation was represented by A, B, C, D, and E. A means the best condition and E means the worst condition. As a result, good images were obtained at the initial stage and throughout the durability. In addition, it was found that the change in the surface roughness (Rz) of the charging member (charging roller) due to durability was small, and that the amount of foreign matter adhered to the surface of the charging roller was small. It is considered that almost all of them are retained.
[0201]
That is, it was confirmed that an excellent effect that good initial characteristics can be stably maintained. Table 4 shows combinations and evaluation results of the charging member, the electrophotographic photosensitive member, the developer, and the electrophotographic apparatus used in this example.
[0202]
(Examples 1-2 to 7)
The evaluation was performed in the same manner as in Example 1-1 except that the charging member was changed. Table 4 shows these combinations and evaluation results.
[0203]
<Comparative Example 1>
Evaluation was performed in the same manner as in Example 1-1 except that the charging member 13 was used. Table 4 shows the evaluation results.
[0204]
[Table 4]

[0205]
<Example 2>
Evaluation was performed in the same manner as in Example 1 except that the developer 1 was used instead of the developer 5, the electrophotographic apparatus 2 was used instead of the electrophotographic apparatus 1, and the charging members shown in Table 5 were used. Examples 2-1 to 8).
[0206]
The halftone image used for the image evaluation was changed to 2 dots 3 spaces, and the other conditions were the same as in Example 1 (in this case, minute unevenness tends to appear in the image more easily than 1 dot 2 spaces). Table 5 shows these combinations and evaluation results.
[0207]
<Comparative Example 2>
Evaluation was performed in the same manner as in Example 2 except that the charging member 13 was used. Table 5 shows the evaluation results.
[0208]
[Table 5]

[0209]
<Example 3>
Evaluation was performed in the same manner as in Example 1 except that developer 1 was used instead of developer 5, electrophotographic apparatus 2 was used instead of electrophotographic apparatus 1, and photoconductor 2 was used instead of photoconductor 1. (Examples 3-1 to 5). The halftone image used for the image evaluation was changed to 2 dots 3 spaces, and the other conditions were the same as in Example 1 (in this case, minute unevenness tends to appear in the image more easily than 1 dot 2 spaces). Table 6 shows the combinations and evaluation results.
[0210]
<Comparative Example 3>
Evaluation was performed in the same manner as in Example 3 except that the charging member 13 was used. Table 6 shows the evaluation results.
[0211]
[Table 6]

[0212]
<Example 4>
The recyclability (stability against repeated use) of the charging member was evaluated (Examples 4-1 to 5). The halftone image used for the image evaluation was 1 dot 2 spaces as in the first embodiment. Table 7 shows combinations of the charging member, the photoconductor, the developer, and the electrophotographic apparatus and the evaluation results.
[0213]
As can be seen from these results, the charging member of the present invention can be further used as it is without cleaning since the amount of dirt attached is small.
[0214]
Further, the charging member of the present invention can easily remove the adhered dirt. The cleaning can be performed by simple means such as dry wiping or air blowing without the need for a complicated step of generally performing washing with water or a solvent or removing the entire surface layer to re-form the surface layer.
[0215]
The charged member thus cleaned has almost recovered its original function, and a good image can be obtained.
[0216]
<Comparative Example 4>
Evaluation was performed in the same manner as in Example 4 except that the charging member 13 was used. Table 7 shows the evaluation results.
[0219]
[Table 7]

[0218]
【The invention's effect】
According to the present invention, since a change in surface shape due to durability and the amount of foreign matter attached are small, an excellent charging member and an apparatus using the same, which stably maintain excellent initial charging characteristics for a long period of time, are provided. Can be provided.
[0219]
The charging member of the present invention is an electrophotographic device that requires various advanced functions, such as an electrophotographic device that requires particularly high image quality and high definition images, a high-speed electrophotographic device, or a highly durable electrophotographic device. It can be particularly suitably used in an apparatus. Therefore, when a resolution of 600 dpi or more (especially, 1200 dpi or more) or a high-definition halftone image is required, or when a process speed of 120 mm / sec or more, particularly 160 mm / sec or more is required, 10,000 sheets or more are required. In particular, the present invention is suitable for an electrophotographic apparatus which is required to output 12,000 or more images without performing replenishment or maintenance, a process cartridge used in the electrophotographic apparatus, and the like.
[0220]
Furthermore, the charging member of the present invention has an advantage of being extremely excellent in recyclability, and has an excellent property that a charging member that can be used repeatedly can be supplied by a simple cleaning method.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view illustrating an example of an outermost layer of a charging member of the present invention.
FIG. 2 is a detailed view of a hole in an outermost layer of the charging member of the present invention.
FIG. 3 is a schematic view showing an embodiment of the charging member of the present invention.
FIG. 4 is a schematic view of an apparatus for measuring a volume resistance value of the charging member of the present invention.
FIG. 5 is a schematic view showing one embodiment of a tandem type color electrophotographic apparatus using the charging member of the present invention.
FIG. 6 is an enlarged view of an image forming unit of the color electrophotographic apparatus of FIG.
FIG. 7 is an enlarged view of an arbitrary station in FIG. 6;
FIG. 8 is a schematic view showing an embodiment of an intermediate transfer type (belt-shaped) color electrophotographic apparatus using the charging member of the present invention.
FIG. 9 is a schematic diagram showing an embodiment of an intermediate transfer type (drum-shaped) color electrophotographic apparatus using the charging member of the present invention.
FIG. 10 is a schematic view showing one embodiment of an electrophotographic apparatus using the charging member of the present invention.
FIG. 11 is a schematic view showing one embodiment of an electrophotographic apparatus using the charging member of the present invention.
FIG. 12 is a schematic view showing an embodiment of an electrophotographic apparatus using the charging member of the present invention.
FIG. 13 is a schematic view showing an embodiment of an electrophotographic apparatus using the charging member of the present invention.
FIG. 14 is a schematic view showing an embodiment of an electrophotographic apparatus using the charging member of the present invention.
[Explanation of symbols]
1. Electrophotographic photoreceptor
t Thickness of outermost layer
2 Charging member
2z outermost layer
2z-1 polymer compound
2z-2 hole
2z-3 porous powder
2a conductive support
2b elastic layer
L Hole length
D Hole diameter
3 Exposure
4 Developing device
5 Transfer material
6 Transfer device
7 Fixing device
8 Cleaner
400 metal drum
401 power supply
402 ammeter
W load
N Effective length

Claims (16)

A conductive support, an elastic layer provided on the conductive support, and at least an outermost layer formed on the outermost side,
The charging member according to claim 1, wherein the outermost layer has a hole, and is made of a porous material having a length (L) and a diameter (D) of L / D ≧ 1.1. The charging member according to claim 1, wherein the average pore diameter of the porous body is 5 µm or less. The charging member according to claim 1, wherein the outermost layer contains at least a resin and an electronic conductivity imparting agent. The charging member according to claim 3, wherein the resin has a urethane bond. The charging member according to any one of claims 1 to 4, wherein the elastic layer contains at least a rubber and an ionic conductivity imparting agent. The charging member according to claim 5, wherein the rubber has polarity. The charging member according to claim 5, wherein the rubber is epichlorohydrin rubber. An electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member to a predetermined potential, electrostatic latent image forming means for forming an electrostatic latent image on a charged surface of the electrophotographic photosensitive member, and the electrophotographic photosensitive member An electrophotographic apparatus comprising: developing means for transferring a toner to an electrostatic latent image formed on a body to visualize and form a toner image; and transfer means for transferring the toner image to a transfer material,
An electrophotographic apparatus, wherein the charging unit includes the charging member according to claim 1. 9. An electrophotographic apparatus according to claim 8, wherein said developing means has a conductive elastic member which forms a predetermined contact portion with said photosensitive member and comes into contact therewith. 10. The electronic device according to claim 9, wherein a ten-point average roughness Rz (Rz1) of the charging member and a ten-point average roughness Rz (Rz2) of the conductive elastic member of the developing unit satisfy Rz1 <Rz2. Photo equipment. 11. The electrophotographic apparatus according to claim 9, wherein the Asker C hardness (Hs1) of the charging member and the Asker C hardness (Hs2) of the conductive elastic member of the developing unit satisfy Hs1 <Hs2. The volume resistance value (ρ1) of the charging member and the volume resistance value (ρ2) of the conductive elastic member of the developing unit satisfy ρ1 <ρ2. Electrophotographic equipment. 13. The method according to claim 9, wherein V1> V2 when a DC voltage applied to the charging member and a DC voltage applied to the conductive elastic member of the developing unit are V1 and V2, respectively. The electrophotographic apparatus according to claim 1. The electrophotographic apparatus according to any one of claims 9 to 13, wherein a voltage applied to one or both of the charging member and the conductive elastic member of the developing unit is a DC voltage only. The electrophotographic apparatus according to any one of claims 8 to 14, wherein the toner has a glass transition temperature (Tg) of 30C to 80C. A process cartridge configured to be detachable from the image forming apparatus according to claim 8, wherein:
A process cartridge in which an electrophotographic photosensitive member and a charging unit having a charging member are integrally supported.

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