JP4148505B2 - Image forming apparatus and process cartridge - Google Patents

Description

【００２０】
ここで、「粒子投影面積」とは二値化されたトナー粒子像の面積であり、「粒子投影像の周囲長」とは該トナー粒子像のエッジ点を結んで得られる輪郭線の長さと定義する。
【００２１】
本発明における円形度は、トナー粒子の凹凸の度合いを示す指標であり、トナー粒子が完全な球形の場合に１．００を示し、表面形状が複雑になる程、円形度は小さな値となる。
【００２２】
本発明において、トナーの個数基準の粒径頻度分布の平均値を意味する円相当個数平均径ｄ₁と粒径標準偏差ＳＤｄは、粒度分布の分割点ｉでの粒径（中心値）をｄｉ、頻度をｆ_iとすると次式から算出される。
【００２３】
【数２】

【００２４】
また、円形度頻度分布の平均値を意味する平均円形度ｃと円形度標準偏差ＳＤｃは、粒度分布の分割点ｉでの円形度（中心値）をｃｉ、頻度をｆ_ciとすると、次式から算出される。
【００２５】
【数３】

【００２６】
具体的な測定方法としては、容器中に予め不純固形物等を除去したイオン交換水１０ｍｌを用意し、その中に分散剤として界面活性剤、好ましくはアルキルベンゼンスルホン酸塩を加えた後、更に測定試料を０．０２ｇを加え、均一に分散させる。分散させる手段としては、超音波分散機ＵＨ−５０型（エスエムテー社製）に振動子としてφ５ｍｍチタンの合金チップを装着したものを用い、５分間分散処理を用い、測定用の分散液とする。その際、該分散液の温度が４０℃以上とならない様に適宜冷却する。
【００２７】
トナー粒子の形状測定には、前記フロー式粒子像測定装置を用い、測定時のトナー粒子濃度が３０００〜１万個／μｌとなる様に該分散液濃度を再調整し、トナー粒子を１０００個以上計測する。計測後、このデータを用いて、トナーの円相当径や円形度頻度分布等を求める。
【００２８】
本発明に使用されるトナーに用いられるワックス成分としては、パラフィンワックス、マイクロクリスタリンワックス、ペトロラクタム等の石油系ワックス及びその誘導体、モンタンワックス及びその誘導体、フィッシャートロプシュ法による炭化水素ワックス及びその誘導体、ポリエチレンに代表されるポリオレフィンワックス及びその誘導体、カルナバワックス、キャンデリラワックス等、天然ワックス及びそれらの誘導体等で、誘導体には酸化物や、ビニルモノマーとのブロック共重合物、グラフト変性物も含み、また、高級脂肪族アルコール等のアルコール；ステアリン酸、パルミチン酸等の脂肪酸あるいはその化合物；酸アミド、エステル、ケトン、硬化ヒマシ油及びその誘導体、植物ワックス、動物ワックス等、スチレンモノマーへの溶解温度が４０〜８０℃のものであれば、どれでも用いることが可能である。
【００２９】
これらの中でもポリオレフィン、フィッシャートロプシュ法による炭化水素ワックス、石油系ワックス、高級アルコール、もしくは、高級エステルである場合、現像性や転写性の改善効果が更に高くなる。
【００３０】
上述したワックス成分は、結着樹脂１００質量部に対して１〜３０質量部使用するのが好ましい。
【００３１】
本発明のトナーに用いられる結着樹脂としては、一般的に用いられているスチレン−（メタ）アクリル共重合体、ポリエステル樹脂、エポキシ樹脂、スチレン−ブタジエン共重合体が挙げられる。重合法により直接トナー粒子を得る方法においては、それらを形成するための単量体が用いられる。
【００３２】
具体的にはスチレン；ｏ−（ｍ−、ｐ−）メチルスチレン、ｍ−（ｐ−）エチルスチレンの如きスチレン系単量体；（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、（メタ）アクリル酸ブチル、（メタ）アクリル酸オクチル、（メタ）アクリル酸ドデシル、（メタ）アクリル酸ステアリル、（メタ）アクリル酸ベヘニル、（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸ジメチルアミノエチル、（メタ）アクリル酸ジエチルアミノエチルの如き（メタ）アクリル酸エステル系単量体；ブタジエン、イソプレン、シクロヘキセン、（メタ）アクリロニトリル、アクリル酸アミドの如きエン系単量体が好ましく用いられる。これらは、単独、又は、一般的には出版物ポリマーハンドブック第２版ＩＩＩ−Ｐ１３９〜１９２（ＪｏｈｎＷｉｌｅｙ＆Ｓｏｎｓ社製）に記載の理論ガラス転移温度（Ｔｇ）が、４０〜７５℃を示すように単量体を適宜混合して用いられる。理論ガラス転移温度が４０℃未満の場合には、トナーの保存安定性や耐久安定性の面から問題が生じ易く、一方、７５℃を超える場合はトナーの定着点の上昇をもたらす。特に、フルカラー画像を形成するためのカラートナーの場合においては、各色トナーの定着時の混色性が低下し色再現性に乏しく、更にＯＨＰ画像の透明性が低下するため好ましくない。
【００３３】
結着樹脂の分子量は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により測定される。具体的なＧＰＣの測定方法としては、予めトナーをソックスレー抽出器を用いトルエン溶剤で２０時間抽出を行った後、ロータリーエバポレーターでトルエンを留去せしめて抽出物を得、更に低軟化点物質は溶解するが外殻樹脂は溶解しない有機溶剤（例えばクロロホルム等）を抽出物に加え十分洗浄を行った後、残留物をテトラヒドロフラン（ＴＨＦ）に溶解した溶液をポア径が０．３μｍの耐溶剤性メンブランフィルターでろ過したサンプル（ＴＨＦ溶液）をウォーターズ社製１５０Ｃを用いて測定する。カラム構成は、昭和電工製Ａ−８０１、８０２、８０３、８０４、８０５、８０６及び８０７を連結し、標準ポリスチレン樹脂の検量線を用い分子量分布を測定し得る。本発明に係る結着樹脂の主たるピーク分子量は５０００〜１００万、重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）との比（Ｍｗ／Ｍｎ）が、２〜１００を示すものが本発明には好ましい。
【００３４】
本発明に使用されるトナーに用いられる着色剤は、以下に示すイエロー着色剤、マゼンタ着色剤及びシアン着色剤が挙げられ、黒色着色剤としてカーボンブラック、磁性体又は以下に示すイエロー着色剤／マゼンタ着色剤／シアン着色剤を混合して黒色に調色されたものが利用される。
【００３５】
イエロー着色剤としては、縮合アゾ化合物、イソインドリノン化合物、アンスラキノン化合物、アゾ金属錯体、メチン化合物及びアリルアミド化合物等に代表される化合物が用いられる。具体的には、Ｃ．Ｉ．ピグメシトイエロー１２、１３、１４、１５、１７、６２、７４、８３、９３、９４、９５、１０９、１１０、１１１、１２８、１２９、１４７、１６８及び１８０等が好適に用いられる。
【００３６】
マゼンタ着色剤としては、縮合アゾ化合物、ジケトピロロピロール化合物、アンスラキノン、キナクリドン化合物、塩基染料レーキ化合物、ナフトール化合物、ベンズイミダゾロン化合物、チオインジゴ化合物及びペリレン化合物等が用いられる。具体的には、Ｃ．Ｉ．ピグメントレッド２、３、５、６、７、２３、４８；２、４８；３、４８；４、５７；１、８１；１、１４４、１４６、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１及び２５４等が特に好ましい。
【００３７】
シアン着色剤としては、銅フタロシアニン化合物及びその誘導体、アンスラキノン化合物及び塩基染料レーキ化合物等が利用できる。具体的には、Ｃ．Ｉ．ピグメントブルー１、７、１５、１５：１、１５：２、１５：３、１５：４、６０、６２及び６６等が特に好適に利用できる。
【００３８】
これらの着色剤は、単独又は混合し更には固溶体の状態で用いることができる。着色剤は、色相、彩度、明度、耐候性、ＯＨＰ透明性、トナー粒子中への分散性の点から選択される。該着色剤の添加量は、樹脂成分１００質量部に対し１〜２０質量部使用するのが好ましい。
【００３９】
黒色着色剤として磁性体を用いた場合には、他の着色剤と異なり、樹脂１００質量部に対し４０〜１５０質量部使用するのが好ましい。
【００４０】
本発明に使用されるトナーには、公知の荷電制御剤が使用できるが、特に帯電スピードが速くかつ一定の帯電量を安定して維持できる荷電制御剤が好ましい。更に、本発明において直接重合方法を用いる場合には、重合阻害性が無く水系への可溶化物の無い荷電制御剤が好ましい。
【００４１】
具体的な化合物としては、ネガ系としてサリチル酸、ナフトエ酸、ダイカルボン酸又はその誘導体の金属化合物、アゾ顔料又はその誘導体の金属化合物、スルホン酸、カルボン酸を側鎖に持つ高分子型化合物、ホウ素化合物、尿素化合物、ケイ素化合物及びカリークスアレーン等が利用できる。ポジ系としてニグロシン、トリフェニルメタン系化合物、四級アンモニウム塩、該四級アンモニウム塩を側鎖に有する高分子型化合物、グアニジン化合物及びイミダゾール化合物等が好ましく用いられる。しかしながら、本発明において別の荷電制御剤の添加は必須ではなく、非磁性一成分ブレードコーティング現像方法を用いた場合においてもブレード部材やスリーブ部材との摩擦帯電を積極的に利用することでトナー中に必ずしも別の荷電制御剤を含む必要はない。
【００４２】
本発明に使用されるトナーに無機微粉体を添加することは、現像性、転写性、帯電安定性、流動性及び耐久性向上のために好ましい実施形態である。該無機微粉体としては公知のものが使用可能であるが、特にシリカ、アルミナ及びチタニアあるいはその複酸化物の中から選ばれることが好ましい。更には、シリカであることがより好ましい。例えば、かかるシリカは、硅素ハロゲン化物やアルコキシドの蒸気相酸化により生成されたいわゆる乾式法又はヒュームドシリカと称される乾式シリカ及びアルコキシド、水ガラス等から製造されるいわゆる湿式シリカの両者が使用可能であるが、表面及びシリカ微粉体の内部にあるシラノール基が少なく、また、Ｎａ₂ＯやＳＯ₃ ^2-等の製造残渣の少ない乾式シリカの方が好ましい。また、乾式シリカにおいては、製造工程において例えば、塩化アルミニウムや塩化チタン等の他の金属ハロゲン化合物を硅素ハロゲン化合物と共に用いることによって、シリカと他の金属酸化物の複合微粉体を得ることも可能であり、それらも包含する。
【００４３】
本発明に使用されるトナーに用いられる無機微粉体は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ²／ｇ以上、特に５０〜４００ｍ²／ｇの範囲のものが良好な結果を与え、トナー１００質量部に対してシリカ微粉末０．１〜８質量部、好ましくは０．５〜５質量部、更に好ましくは１．０を超えて３．０質量部まで使用するのが特によい。
【００４４】
また、本発明に使用されるトナーに用いられる無機微粉体は、必要に応じ、疎水化や帯電性制御等の目的でシリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他有機硅素化合物及び有機チタン化合物等の処理剤で、あるいは、種々の処理剤で併用して処理されていることも可能であり好ましい。
【００４５】
比表面積はＢＥＴ法に従って、比表面積測定装置オートソーブ１（湯浅アイオニクス社製）を用いて試料表面に窒素ガスを吸着させ、ＢＥＴ多点法を用いて比表面積を算出した。
【００４６】
高い帯電量を維持し、低消費量及び高転写率を達成するためには、無機微粉体は少なくともシリコーンオイルで処理されることが更に好ましい。
【００４７】
本発明に使用するトナーにおいては、実質的な悪影響を与えない範囲内で更に他の添加剤、例えばポリテトラフルオロエチレン粉末、ステアリン酸亜鉛粉末、ポリフッ化ビニリデン粉末の如き滑剤粉末；酸化セリウム粉末、炭化硅素粉末、チタン酸ストロンチウム粉末等の研磨剤；例えば酸化チタン粉末、酸化アルミニウム粉末等の流動性付与剤；ケーキング防止剤、あるいは例えばカーボンブラック粉末、酸化亜鉛粉末、酸化スズ粉末等の導電性付与剤、また、逆極性の有機微粒子及び無機微粒子を現像性向上剤として少量用いることもできる。
【００４８】
本発明に使用するトナーを製造する方法としては、樹脂、低軟化点物質からなる離型剤、着色剤及び荷電制御剤等を加圧ニーダーやキクストルーダー又はメディア分散機を用い均一に分散せしめた後、機械的又はジェット気流下でターゲットに衝突させ、所望のトナー粒径に微粉砕化せしめた後、必要により、トナー粒子の平滑化及び球形化の工程を付加し、更に分級工程を経て粒度分布をシャープにせしめトナーにする粉砕方法によるトナーの製造方法の他に、特公昭５６−１３９４５号公報等に開示されているディスク又は多流体ノズルを用い溶融混合物を空気中に霧化し球状トナーを得る方法や、特公昭３６−１０２３１号公報、特開昭５９−５３８５６号公報及び特開昭５９−６１８４２号公報に述べられている懸濁重合方法を用いて直接トナーを生成する方法や、単量体には可溶で得られる重合体が不溶な水系有機溶剤を用い直接トナーを生成する分散重合方法又は水溶性極性重合開始剤存在下で直接重合しトナーを生成するソープフリー重合法に代表される乳化重合方法等を用いトナーを製造することが可能である。
【００４９】
粉砕法を用いてトナーを製造する方法においては、トナー粒子の形状を所望の円形度頻度分布の範囲に納めることが困難であり、溶融スプレー法においては、ある程度の円形度を得ることができるが、得られるトナーの粒度分布が広くなり易い傾向があると共に、トナーの表面状態をコントロールすることが困難である。他方、分散重合法においては、得られるトナーは極めてシャープな粒度分布を示すが、使用する材料の選択が狭いことや有機溶剤の利用が廃溶剤の処理や溶剤の引火性に関する観点から製造装置が複雑で煩雑化し易い。ソープフリー重合に代表される乳化重合方法は、トナーの粒度分布が比較的揃うため有効であるが、使用した乳化剤や重合開始剤末端がトナー粒子表面に存在した時に環境特性を悪化させ易い。
【００５０】
本発明においては、トナー粒子の円形度頻度分布のコントロールが重要であり、比較的容易に円相当個数平均径が２．３〜４．１μｍの微粒子トナーが得られる常圧下、又は、加圧下での乳化重合法又は懸濁重合方法を用い、予め得られた重合体にメディアを用い定形化したり、直接加圧衝突板に重合体を衝突せしめる方法や、更には得られた重合体を水系中にて凍結せしめたり、塩折や反対表面電荷を有する粒子をｐＨ等の条件を考慮することで合体し、凝集、合一せしめる凝集方法が特に好ましい。更に、一旦得られた重合粒子に更に単量体を吸着せしめた後、重合開始剤を用い重合せしめるシード重合方法も本発明に好適に利用することができる。
【００５１】
トナーの製造方法として直接重合方法を利用する場合、トナー粒子の円形度頻度分布及び粒径頻度分布の制御は、難水溶性の無機塩や保護コロイド作用をする分散剤の種類や添加量を変える方法や機械的装置条件（例えば、ローターの周速、パス回数、攪拌羽根形状等の攪拌条件や容器形状）又は、水溶液中での固形分濃度等を制御することにより所定のトナー粒子を得ることができる。
【００５２】
また、トナーを加熱乾燥する際にもトナー粒子に球形化処理を施すことが可能で、例えば流動層乾燥機を用い、回転翼の攪拌条件と処理時間を調整することによりトナー粒子形状を好ましいものとすることができる。
【００５３】
本発明のトナーは、ワックス成分の物理特性を前述の如きに特定することにより、上記の如きトナー粒子の球形化処理に対してもトナーの粗粒化やワックス成分による影響を最小限とすることができるので非常に有効なものとなる。
【００５４】
直接重合法によりトナーを製造する際、用いられる重合開始剤として例えば、２，２’−アゾビス−（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリルの如きアゾ系又はジアゾ系重合開始剤；ベンゾイルペルオキシド、メチルエチルケトンペルオキシド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキシド、２，４−ジクロロベンゾイルペルオキシド及びラウロイルペルオキシドの如き過酸化物系重合開始剤が用いられる。該重合開始剤の使用量は、目的とする重合度により変化するが一般的には重合性単量体に対し０．５〜２０質量％用いられる。重合開始剤の種類は、重合法により若干異なるが、１０時間半減期温度を参考に、単独又は混合して使用される。
【００５５】
重合度を制御するため公知の架橋剤、連鎖移動剤及び重合禁止剤等を更に添加し用いてもよい。
【００５６】
トナーの製法として分散安定剤を用いた懸濁重合法を利用する場合、用いる分散安定剤としては、無機化合物として、リン酸三カルシウム、リン酸マグネシウム、リン酸アルミニウム、リン酸亜鉛、炭酸カルシウム、炭酸マグネシウム、水酸化カルシウム、水酸化マグネシウム、水酸化アルミニウム、メタケイ酸カルシウム、硫酸カルシウム、硫酸バリウム、ベントナイト、シリカ及びアルミナ等が挙げられる。有機化合物としては、ポリビニルアルコール、ゼラチン、メチルセルロース、メチルヒドロキシプロピルセルロース、エチルセルロース、カルボキシメチルセルロースのナトリウム塩、ポリアクリル酸及びその塩、及びデンプン等が挙げられる。これらを水相に分散させて使用できる。これら分散安定剤は、重合性単量体１００質量部に対して０．２〜２０質量部を使用することが好ましい。
【００５７】
分散安定剤として、無機化合物を用いる場合、市販のものをそのまま用いてもよいが、細かい粒子を得るために、分散媒体中にて該無機化合物の微粒子を生成してもよい。例えば、リン酸三カルシウムの場合、高速攪拌下において、リン酸ナトリウム水溶液と塩化カルシウム水溶液を混合するとよい。
【００５８】
これら分散安定剤の微細な分散のために、０．００１〜０．１質量部の界面活性剤を併用してもよい。これは、上記分散安定剤の所期の作用を促進するためのものであり、例えば、ドデシルベンゼン硫酸ナトリウム、テトラデシル硫酸ナトリウム、ペンタデシル硫酸ナトリウム、オクチル硫酸ナトリウム、オレイン酸ナトリウム、ラウリル酸ナトリウム、ステアリン酸カリウム及びオレイン酸カルシウム等が挙げられる。
【００５９】
本発明で使用するトナーの製造方法として直接重合法を用いる場合においては、以下の如き製造方法が可能である。
【００６０】
重合性単量体中に、低軟化点物質からなる離型剤、着色剤、荷電制御剤及び重合開始剤その他の添加剤を加え、ホモジナイザーや超音波分散機等によって均一に溶解又は分散せしめた単量体組成物を、分散安定剤を含有する水相中に通常の攪拌機又はホモミキサーやホモジナイザー等により分散せしめる。好ましくは、単量体組成物の液滴が所望のトナー粒子のサイズを有するように攪拌速度や攪拌時間を調整し、造粒する。その後は分散安定剤の作用により、粒子状態が維持され、かつ粒子の沈降が防止される程度の攪拌を行えばよい。重合温度は４０℃以上、一般的には５０〜９０℃の温度に設定して重合を行うのが好ましい。重合反応後半に昇温してもよく、更に、本発明における画像形成方法における耐久性向上の目的で、未反応の重合性単量体や副生成物等を除去するために反応後半、又は、反応終了後に一部水系媒体を反応系から留去してもよい。反応終了後、生成したトナー粒子を洗浄・濾過により回収し、乾燥する。懸濁重合法においては、通常、単量体組成物１００質量部に対して水３００〜３０００質量部を分散媒体として使用するのが好ましい。
【００６１】
本発明の画像形成装置における現像方法は、複写機で代表される正規現像方式及びレーザープリンターに代表される反転現像方式いずれでもよく、また、現像法としては二成分磁気ブラシ現像法、磁性一成分現像法、もしくは非磁性一成分現像法いずれでもよい。
【００６２】
有機電子写真感光体は、導電性支持体上に感光層が設けられたものである。感光層は、一般に電荷発生材料、電荷輸送材料、及び結着樹脂からなり、本発明においては、電荷発生材料を含む電荷発生層と電荷輸送材料を含む電荷輸送層からなる積層型である。また、積層型の電子写真感光体の場合には、導電性支持体の上に電荷発生層、電荷輸送層の順で積層された電子写真感光体である。この電荷発生材料を含む電荷発生層と電荷輸送材料を含む電荷輸送層をこの順に積層した電子写真感光体において、より高感度、高安定性等、良好な感光体特性が得られる。また、前記感光層上に電子写真感光体の耐久性向上を目的として保護層を設けることも可能である。耐久性向上に特化した硬度の高い層を保護層として設けることにより電子写真感光体の耐久性と感度、残留電位等の電子写真感光体の電気特性との両立を計ることが可能となる。
【００６３】
本発明に用いる電子写真感光体の表面層は表面硬度が、その表面層をガラス板上に形成したときにユニバーサル硬さが２６８Ｎ／ｍｍ ² 以上４１５Ｎ／ｍｍ ² 以下である。ユニバーサル硬さが２３０Ｎ／ｍｍ²未満では、本発明の装置においてはクリーニング不良が発生し易く、特に耐久時に電子写真感光体表面に傷や不均一な摩耗が発生し、それが原因となってクリーニング不良が多発する。また、ユニバーサル硬さが５００Ｎ／ｍｍ²を超えると画像出力を連続的に多数繰り返した場合に、電子写真感光体表面とクリーニングブレードとの摩擦力が増加し、その結果ブレード先端の振動やめくれが発生することによりクリーニング不良が発生する傾向にある。これは、電子写真感光体表面の硬度が高すぎ、帯電等により劣化し滑り性の低下した最表面が除去され難くなるためと考えられる。また、ユニバーサル硬さが５００Ｎ／ｍｍ²を超えると衝撃等により表面層にひびが生じ易くなる。これは、表面層とその下の層との硬さに大きな違いがあり過ぎるためと考えられる。
【００６４】
本発明の電子写真感光体の表面層の表面硬度は、計装化圧子圧入法（ｎａｎｏｉｎｄｅｎｔａｔｉｏｎｍｅｔｈｏｄｓ）によるユニバーサル硬さ（Ｈｕ：単位Ｎ／ｍｍ²）で測定する。
【００６５】
本発明において、ユニバーサル硬さはＨｅｌｍｕｔＦｉｓｃｈｅｒＧＭＢＨ＋Ｃｏ．製のＦＩＳＣＨＥＲＳＣＯＰＥＨ１００Ｖを用いて測定した。試料は、ガラス板上に４〜５μｍの膜厚で形成した。圧子の押し込み深さは、１μｍであった。
【００６６】
本発明において表面層とは、塗膜のユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下である膜により形成される層であって、電子写真感光体の表面に設けられた層をいう。従って、導電性支持体の上に電荷発生層、電荷輸送層の順で積層された積層型の電子写真感光体の場合には電荷輸送層が表面層であり、保護層を設ける場合には保護層が表面層となる。それらは、ユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下である膜により形成される。本発明で用いられる有機電子写真感光体は、その表面層が硬化性の樹脂を含み、且つそのユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下である。
【００６７】
ユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下である表面層を持つ電子写真感光体の具体例を、電荷発生層／電荷輸送層をこの順に積層した電子写真感光体を例に説明する。この場合は、電荷輸送層のユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下である。
【００６８】
電子写真感光体の支持体としては、導電性を有するものであればよく、例えばアルミニウム、銅、クロム、ニッケル、亜鉛及びステンレス等の金属や合金をドラム又はシート状に成形したもの、アルミニウム及び銅等の金属箔をプラスチックフィルムにラミネートしたもの、アルミニウム、酸化インジウム及び酸化錫等をプラスチックフィルムに蒸着したもの、導電性物質を単独又は結着樹脂と共に塗布して導電層を設けた金属、またプラスチックフィルム及び紙等が挙げられる。
【００６９】
本発明に用いる電子写真感光体においては、導電性支持体の上にはバリアー機能と接着機能をもつ中間層を設けることができる。
【００７０】
中間層は、感光層の接着性改良、塗工性改良、支持体の保護、支持体上の欠陥の被覆、支持体からの電荷注入性改良、また感光層の電気的破壊に対する保護等のために形成される。中間層の材料としては、ポリビニルアルコール、ポリ−Ｎ−ビニルイミダゾール、ポリエチレンオキシド、エチルセルロース、エチレン−アクリル酸共重合体、カゼイン、ポリアミド、Ｎ−メトキシメチル化６ナイロン、共重合ナイロン、にかわ及びゼラチン等が挙げられる。これらは、それぞれに適した溶剤に溶解されて支持体上に塗布される。その際の膜厚としては０．１〜２μｍが好ましい。
【００７１】
本発明の電子写真感光体が積層型の電子写真感光体である場合には、電荷発生層及び電荷輸送層を積層する。電荷発生層に用いる電荷発生材料としては、セレン−テルル、ピリリウム、チアピリリウム系染料、また各種の中心金属及び結晶系、具体的には例えばα、β、γ、ε及びＸ型等の結晶型を有するフタロシアニン化合物、アントアントロン顔料、ジベンズピレンキノン顔料、ピラントロン顔料、トリスアゾ顔料、ジスアゾ顔料、モノアゾ顔料、インジゴ顔料、キナクリドン顔料、非対称キノシアニン顔料、キノシアニン及び特開昭５４−１４３６４号公報に記載のアモルファスシリコーン等が挙げられる。
【００７２】
積層型の電子写真感光体の場合、電荷発生層は前記電荷発生材料を０．３〜４倍量の結着樹脂及び溶剤と共にホモジナイザー、超音波分散、ボールミル、振動ボールミル、サンドミル、アトライター及びロールミル等の方法でよく分散し、分散液を塗布し、乾燥して形成されるか、又は前記電荷発生材料の蒸着膜等、単独組成の膜として形成される。その膜厚は５μｍ以下であることが好ましく、特には０．１〜２μｍの範囲であることが好ましい。
【００７３】
結着樹脂を用いる場合の例は、スチレン、酢酸ビニル、塩化ビニル、アクリル酸エステル、メタクリル酸エステル、フッ化ビニリデン、トリフルオロエチレン、等のビニル化合物の重合体及び共重合体、ポリビニルアルコール、ポリビニルアセタール、ポリカーボネート、ポリエステル、ポリスルホン、ポリフェニレンオキサイド、ポリウレタン、セルロース樹脂、フェノール樹脂、メラミン樹脂、ケイ素樹脂及びエポキシ樹脂等が挙げられる。
【００７４】
積層型の電子写真感光体の電荷輸送層は、一般的には結着樹脂に低分子量の電荷輸送材料を分子分散させた層が用いられており、本発明においてもユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下である膜であれば、上記結着樹脂中に低分子量の電荷輸送材料を分散した膜も使用可能である。
【００７５】
この場合の電荷輸送材料としては、特に限定されることなく、例えばヒドラゾン誘導体、ブタジエン誘導体、トリフェニルアミン誘導体、スチルベン誘導体、ピラゾリン誘導体及びオキサジアゾール誘導体等を挙げることができる。
【００７６】
結着樹脂としては、ポリメチルメタクリレート樹脂、ポリカーボネート樹脂、ポリエステル樹脂及びポリアリレート樹脂等が一般に用いられるが、以上のような低分子量の電荷輸送材料を結着樹脂中に分散した電荷輸送層では、その膜硬度は結着樹脂のユニバーサル硬度に大きく依存する。しかも低分子量の電荷輸送材料を分子分散しているため、電荷輸送層の膜硬度は結着樹脂自体のそれよりもはるかに低くなる。従って、本発明に用いるユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下である電荷輸送層を、低分子量の電荷輸送材料を結着樹脂中に分子分散した膜によって得るためには、結着樹脂としてポリカーボネート樹脂等の硬度の高い、かつ高分子量の樹脂を選択し、更に低分子量の電荷輸送材料の含有量を極力小さくする必要がある。
【００７７】
電荷輸送層の鉛筆硬度は上述のように多くの因子で決まるため、一概には決定されないが結着樹脂及び電荷輸送材料の組み合わせと、更に結着樹脂と電荷輸送材料の混合比の選択によってはユニバーサル硬さ２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下は達成される。例えば、重量平均分子量４００００以上のポリカーボネート樹脂とトリフェニルアミン誘導体又はスチルベン誘導体の電荷輸送材料を適正な比率で混合した場合には、電荷輸送層の硬度は２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下と成り得る。
【００７８】
電荷輸送層の膜硬度をユニバーサル硬さで２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下とする方法として電荷輸送材料として高分子電荷輸送材料を用いることは、非常に有効である。これは、前述のように低分子量の電荷輸送材料を結着樹脂に分散した場合には元の結着樹脂に比べて硬度が大幅に低下するのに比べて、高分子電荷輸送材料を用いた場合には高分子電荷輸送材料自体の硬度が高く、上記硬度低下がほとんど起こらないためである。
【００７９】
本発明に用いられる高分子電荷輸送材料としては、公知の高分子電荷輸送材料を用いることができる。例えば、ポリ−Ｎ−ビニルカルバゾールに代表されるような主鎖及び／又は側鎖にカルバゾール環を有する重合体、主鎖及び／又は側鎖にヒドラゾン構造を有する重合体、主鎖及び／又は側鎖に第３級アミン構造を有する重合体、ポリシラン化合物等が挙げられるがこれに限らず、公知の電荷輸送能を有する構造単位を公知の各種重合反応を用いて、共重合体や、ブロック重合体、グラフト重合体としたものも使用可能である。これら高分子電荷輸送材料は、単独で電荷輸送層を形成しても、又は低分子量電荷輸送材料の場合と同様に他の結着樹脂と混合して電荷輸送層を形成してもよい。このときに電荷輸送層のユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下であり、これを達成するために混合する樹脂の種類、混合比等を決定する必要がある。
【００８０】
以上、本発明に用いる電子写真感光体について電荷発生層／電荷輸送層をこの順に積層した積層型の電子写真感光体を例に説明したが、電子写真感光体としては前述のように、感光層上に電子写真感光体の耐久性向上を目的として保護層を設けることも、電子写真感光体の耐久性と感度や残留電位等の電子写真感光体の電気特性との両立を計る上で有効である。
【００８１】
保護層は、積層型の感光層上に形成される。本発明の電子写真感光体の保護層は、ユニバーサル硬さ２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下であることが必要である以外は特に限定されない。保護層の構成は、樹脂を主成分としてこれに膜の電気抵抗をコントロールする物質、例えば導電性粒子、イオン導電性化合物又は導電性高分子等を混合し電子写真感光体に必要な感度や残留電位を保持した上で耐久性の高い膜を形成した保護層である。この場合も、ユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下であれば本発明の電子写真感光体の保護層としては使用可能であり、公知の保護層を使用することができる。
【００８２】
前者の例としては、特開平４−２２６４６９号公報に３官能以上のアクリル（メタクリル）基を有する硬化型アクリルモノマーを重合することにより形成される保護層が開示され、他にも特開昭５７−３０８４７号公報や特開昭６０−４９４５号公報等に多数開示されているが、これらのうち膜のユニバーサル硬さが２６８Ｎ／ｍｍ²以上４１５Ｎ／ｍｍ²以下であれば本発明に用いる電子写真感光体の保護層として使用可能である。
【００８４】
本発明に使用される電子写真感光体の表面層には、各種添加剤を添加することができる。添加剤とは、酸化防止剤及び紫外線吸収剤等の劣化防止剤や、フッ素原子含有樹脂微粒子等の潤剤等である。
【００８５】
本発明において、クリーニング工程ではブレードクリーニングを用いる。電子写真感光体の小径化に伴い小スペースとなり、小型のものが望まれ、かつ高速で十分に小径で円形度の高いトナーを用いた場合の残留トナー除去をせねばならない。このためには、ゴムブレードを選択する必要がある。また、本発明で用いる小径で円形度の高いトナーは、クリーニングの難易度が高い。これをクリーニングするためには、クリーニングブレードを電子写真感光体の回転方向に対してカウンターに対向させ、更に電子写真感光体への当接圧を比較的高く設定することが好ましい。クリーニングブレードによる電子写真感光体表面への応力は、ブレードの当接方法、圧力、角度、ブレードの材質、トナーの材質及び形状等により異なり、これによって繰り返し使用時の電子写真感光体表面へのダメージも大きく影響を受ける。特に、クリーニングブレードの当接圧を高くした場合には、電子写真感光体表面の削れ・傷発生等のダメージの可能性が高くなるが、本発明のユニバーサル硬さ２３０Ｎ／ｍｍ²以上５００Ｎ／ｍｍ²以下の硬さを持つ電子写真感光体表面層を用いることにより、小径で円形度の高いトナーの安定したクリーニングと電子写真感光体の耐久性の両立が可能となるのである。
【００８６】
本発明に用いられるクリーニングブレードに使用される材料は、特に制限されるものではなく、汎用の弾性材料が多く用いられる。例えば、ポリウレタン、シリコーンゴム、フッ素ゴム、天然ゴム、ＳＢＲ、ＢＲ、ＩＲ、ＮＢＲ、ＣＲ、ＡＣＭ、ＡＮＮ及びＣＳＭ等の各種ゴム類が多く用いられ、必要に応じてブレードにポリアミド等の他の樹脂をコーティングしてもよい。
【００８７】
また、製造方法は、金型に原料を注入する方法（注型法）や円筒金型ドラムの内面に原料を注入し、ドラムを回転しながら反応させて、円筒内面に密着したシート状ゴムを形成する方法（遠心成型法）等がある。
【００８８】
図１に本発明の画像形成装置のクリーニング装置部の概略を示した。クリーニング装置は、転写工程後の電子写真感光体上に設けられ、転写されず電子写真感光体１（感光ドラム）に残留した現像剤をクリーニングブレード５−１によって除去する。除去された現像剤は、かき込み部材５−５によって容器内に回収される。カートリッジ方式では、この図に示された電子写真感光体とクリーニング装置及び廃現像剤容器が一体のユニットとなって構成され、更に現像剤容器及び現像装置等と組み合わされて使用される場合が多い。５−２は枠体、５−３は金具、５−４はスクイシート、５−６は仕切板である。
【００８９】
次に、本発明の画像形成装置について説明する。図２において、ドラム型の電子写真感光体１は、軸１ａを中心に矢印方向に所定の周速度で回転駆動する。電子写真感光体１は、その回転過程で帯電手段２によりその周面に正又は負の所定電位の均一帯電を受け、次いで露光部にて不図示の露光手段により露光光Ｌ（スリット露光あるいはレーザービーム走査露光等）を受ける。これにより、電子写真感光体周面に露光に対応した静電潜像が順次形成されていく。その静電潜像は、次いで現像手段３でトナー現像され、そのトナー現像像がコロナ転写手段４により不図示の給紙部から電子写真感光体１と転写手段４との間に、電子写真感光体１の回転と同期して取り出されて給送された転写材７の面に順次転写されていく。像転写を受けた転写材７は、電子写真感光体面から分離されて定着手段８へ導入されて像定着を受けることにより画像形成物（プリント、コピー）として機外ヘプリントアウトされる。像転写後の電子写真感光体１の表面は、クリーニング手段５にて転写残りトナーの除去を受けて清浄面化され、前露光手段６により除電処理がされて繰り返して像形成に使用される。電子写真感光体１の均一帯電手段２としては、コロナ帯電装置が一般に広く使用されている。
【００９０】
また、図３及び図４に示すように、帯電手段として接触帯電部材９を用い、電圧印加された接触帯電部材９を電子写真感光体１に接触させることにより電子写真感光体１の帯電を行ってもよい（この帯電方式を、以下接触帯電という）。図３及び図４に示す装置では、電子写真感光体１上のトナー像も接触帯電部材１０で転写材７に転写される。すなわち、電圧印加された接触帯電部材１０を転写材７に接触させることにより電子写真感光体１上のトナー像を転写材７に転写させる。
【００９１】
また、図３に示す装置では、少なくとも電子写真感光体１、接触帯電部材９及び現像手段３を容器２０に納めて一つのプロセスカートリッジとし、このプロセスカートリッジを装置本体のレール等の案内手段を用いて着脱自在に構成している。クリーニング手段５は、容器２０内に配置してもしなくてもよい。
【００９２】
更に、図４に示す装置では、少なくとも電子写真感光体１及び接触帯電部材９を第１の容器２１に納めて第１のプロセスカートリッジとし、少なくとも現像手段３を容器２２に納めて第２のプロセスカートリッジとし、これら第１のプロセスカートリッジと、第２のプロセスカートリッジとを着脱自在に構成している。クリーニング手段５は、容器２１内に配置してもしなくてもよい。
【００９３】
【実施例】
以下、実施例及び比較例により本発明を更に詳しく説明するが、本発明はこれらの実施例等によりなんら限定されるものではない。なお、実施例中の「部」は質量部を意味する。
【００９４】
＜トナーの製造例及び比較製造例＞
トナーの製造例及び比較製造例について述べる。
【００９５】
｛トナーの製造例１｝
高速攪拌装置ＴＫ式ホモミキサー（特殊機化工業社製）を備えた２リットル用４ッ口フラスコ中にイオン交換水６００ｇと０．１ｍｏｌ／リットル−Ｎａ₃ＰＯ₄水溶液５００ｇを投入し、回転数を１４０００ｒｐｍに調整し、６５℃に加温せしめた。ここに、１．０ｍｏｌ／リットル−ＣａＣｌ₂水溶液７０部を徐々に添加し、微小な難水溶性分散安定剤Ｃａ₃（ＰＯ₄）₂を含む水系分散媒体を調製した。
【００９６】
一方、分散質として、
スチレン ７８部
ｎ−ブチルアクリレート ２２部
ジビニルベンゼン ０．２部
カーボンブラック（ＢＥＴ比表面積＝５０ｍ²／ｇ） ５部
不飽和ポリエステル ４部
（エポキシ化ビスフェノールＡとフマル酸の縮合重合体、ピーク分子量＝７０００）
ジ−ｔｅｒｔ−ブチルサリチル酸のクロル化合物 ２部
エステルワックス（ｍｐ＝６２℃） １０部
【００９７】
上記混合物をアトライター（三井金属社製）を用い３時間分散させた後、２，２’−アゾビス（２，４−ジメチルバレロニトリル）５部を添加し重合性単量体組成物を調製した。
【００９８】
次に、前記水系分散媒体中に該重合性単量体組成物を投入し、内温６５℃のＮ₂雰囲気下で、高速攪拌器の回転数を１２０００ｒｐｍに維持しつつ、１５分間攪拌し、該重合性単量体組成物を造粒した。その後、攪拌器をプロペラ攪拌羽根に換え５０ｒｐｍで攪拌しながら同温度で１０時間保持して重合を完了した。
【００９９】
重合終了後、懸濁液を冷却し、次いで希塩酸を添加し分散安定剤を除去せしめた。更に、水洗浄を数回繰り返した後、流動層乾燥機（大川原製作所社製）を用い熱風中で攪拌しながら１０時間トナー粒子の球形化処理と乾燥処理を行い、重合体粒子（Ａ）を得た。該重合体粒子（Ａ）は、円相当個数平均径が４．１μｍで、円形度頻度分布における平均円形度が０．９９０で、円形度０．９５０未満のトナー粒子数が２．３個数％で、ＧＰＣによる分子量分布で、ピーク分子量が１５０００、Ｍｗ／Ｍｎが１８であった。
【０１００】
上記重合体粒子（Ａ）１００部と疎水性オイル処理シリカ微粉体（ＢＥＴ：２００ｍ²／ｇ）２部をヘンンェルミキサーで乾式混合して、トナー（Ａ）を調製した。
【０１０１】
｛トナーの製造例２〜５及び比較製造例１〜２｝
高速攪拌器の回転数及び流動層乾燥機の処理時間を表１に示す条件に変更した以外は、製造例１と同様にしてトナーを製造し、製造例２〜５のトナー（Ｂ）〜（Ｅ）及び比較製造例１〜２のトナー（ａ）、（ｂ）を得た。
【０１０２】
｛トナーの比較製造例３｝
スチレン−ｎ−ブチルアクリレート−ジビニルベンゼン樹脂 １００部
（ピーク分子量＝１５０００、Ｍｗ／Ｍｎ＝２．４、Ｔｇ＝５０℃）
トナーの製造例１で用いた不飽和ポリエステル ４部
トナーの製造例１で用いたカーボンブラック ５部
負荷電性制御剤（モノアゾ系鉄錯体） ２部
トナー製造例１で用いたエステルワックス １０部
【０１０３】
上記混合物を二軸エクストルーダーで溶融混練し、冷却した混練物をハンマーミルで粗粉砕し、粗粉砕物をジェットミルで微粉砕し、得られた微粉砕物と市販のリン酸カルシウム微粉体とをヘンシェルミキサーで混合後、得られた混合粉体を水が入っている容器へ投入し、更にホモミキサーを用い水中に分散させ、水温を徐々に昇温させ温度６０℃で２時間加熱処理せしめた。その後、希塩酸を容器に添加し、微粉砕物粒子表面のリン酸カルシウムを十分溶解した。濾別後に洗浄、乾燥せしめ、次いで４００メッシュの篩いを通して凝集物を除いた後、分級して分級粉（ｃ）とした。分級粉（ｃ）を用い、前記トナーの製造例１と同様にして比較用トナー（ｃ）を調製した。
【０１０４】
上記で得られた重合体粒子（Ａ）〜（Ｅ）、比較用重合体粒子（ａ）、（ｂ）及び分級粉（ｃ）の諸性状を表１に示す。
【０１０５】
【表１】

【０１０６】
｛トナーの製造例６〜８及び比較製造例４、５｝
分散質として、
エチレン ８０部
アクリル酸２−エチルヘキシル ２０部
ジビニルベンゼン ０．３部
カーボンブラック（ＢＥＴ比表面積＝５０ｍ²／ｇ） ７部
カーボンブラック １部
（スピロンブラックＴＲＨ、保土谷化学工業（株）製）
ポリプロピレン（ビスコール５５０Ｐ、三洋化成（株）製） １０部
２，２’−アゾビス（２，４−ジメチルバレロニトリル） ３部
上記混合物をサンドミルでよく混合し重合性組成物を得た。
【０１０７】
この重合性組成物を表２に示す濃度の燐酸三カルシウム及びドデシルベンゼンスルホン酸ナトリウムを分散安定剤として含む水中に加え、内温６５℃のＮ₂雰囲気下で、高速攪拌器にて分散させて各製造例の懸濁液を得た。その後、この懸濁液を攪拌機を備えた３ッ口フラスコに入れ、攪拌下、７０℃で１０時間加熱して重合させた後、塩酸水溶液にて燐酸三カルシウムを除去し、水洗浄の後、乾燥させてトナーを得た。この重合トナー１００部に疎水性シリカ微粉末（商品名：アエロジルＲ−９７２、アエロジル（株）製）０．３部を加えて混合し、本発明のトナー（Ｆ）〜（Ｈ）及び比較製造例４、５のトナー（ｄ）、（ｅ）を得た。上記トナーの諸性状を表２に示す。
【０１０８】
【表２】

【０１０９】
＜電子写真感光体の製造例及び比較製造例＞
｛電子写真感光体の製造例１｝
まず導電層用の塗工液を以下の手順で調製した。１０％の酸化アンチモンを含有する酸化スズで被覆した導電性酸化チタン粉体５０部、フェノール樹脂２５部、メチルセロソルブ２０部、メタノール５部及びシリコーンオイル（ポリジメチルシロキサン・ポリオキシアルキレン共重合体、平均分子量３０００）０．００２部をφ１ｍｍガラスビーズを用いたサンドミル装置で２時間分散して調製した。この塗工液をφ３０ｍｍのアルミニウムシリンダー上に浸漬塗布方法で塗布し、１４０℃で３０分間乾燥することによって、膜厚が２０μｍの導電層を形成した。
【０１１０】
次に、Ｎ−メトキシメチル化ナイロン５部をメタノール９５部中に溶解し、中間層用塗工液を調製した。この塗工液を前記の導電層上に浸漬コーティング法によって塗布し、１００℃で２０分間乾燥して、膜厚が０．６μｍの中間層を形成した。
【０１１１】
次に、下記式で示されるビスアゾ顔料５部、ポリビニルブチラール樹脂２部及びシクロヘキサノン６０部を、φ１ｍｍガラスビーズを用いたサンドミル装置で２４時間分散し、更にテトラヒドロフラン６０部を加えて電荷発生層用塗工液とした。この塗工液を前記の中間層の上に浸漬コーテイング法で塗布して、１００℃で１５分間乾燥することによって、膜厚が０．２μｍの電荷発生層を形成した。
【０１１２】
【化１】

【０１１３】
次いで、下記式で示される正孔輸送性化合物６０部をモノクロロベンゼン５０部／ジクロロメタン３０部の混合溶媒中に溶解し、電荷輸送層用塗工液を調製した。
【０１１４】
【化２】

【０１１５】
この塗工液を前記の電荷発生層上にコーティングし、加速電圧１５０ＫＶ／照射線量３０Ｍｒａｄの条件で電子線を照射し、樹脂を硬化させことにより、膜厚が１５μｍの電荷輸送層を形成し、電子写真感光体（１）を得た。このときの表面層のユニバーサル硬さは２６８Ｎ／ｍｍ²であった。
【０１１６】
｛電子写真感光体の製造例２｝
電子写真感光体製造例１と同様にして支持体、導電層及び中間層を形成した。
【０１１７】
次に、ＣｕＫα特性Ｘ線回折におけるブラッグ角２θ±０．２度の９．０度、１４．２度、２３．９度及び２７．１度に強いピークを有するオキシチタニウムフタロシアニンを３部、ポリビニルブチラール（商品名：エスレツクＢＭ２、積水化学（株）製）３部及びシクロヘキサノン３５部をφ１ｍｍガラスビーズを用いたサンドミル装置で２時間分散して、その後に酢酸エチル６０部を加えて電荷発生層用塗工液を調製した。この塗工液を前記の中間層の上に浸漬塗布方法で塗布し、５０℃で１０分間乾燥することによって、膜厚が０．２μｍの電荷発生層を形成した。
【０１１８】
次いで、下記式で示される正孔輸送性高分子化合物１５部（数平均分子量Ｍｎ＝２００００）
【０１１９】
【化３】

及び下記式で示される繰り返し単位を有し、数平均分子量Ｍｎ＝８００００のＣ型ポリカーボネート樹脂２５部
【０１２０】
【化４】

をモノクロロベンゼン１００部／ジクロロメタン５０部の混合溶媒中に溶解し調製した電荷輸送層用塗工液を用いて、前記電荷発生層上に電荷輸送層を膜厚１５μｍで形成し、電子写真感光体（２）を得た。このとき表面層のユニバーサル硬さは２５０Ｎ／ｍｍ²であった。
【０１２１】
｛電子写真感光体の製造例３｝
電子写真感光体製造例２と同様にして支持体、導電層、中間層及び電荷発生層を形成した。
【０１２２】
更に、下記式で示されるスチリル化合物２０部
【０１２３】
【化５】

及び下記式で示される繰り返し単位を有するポリカーボネート樹脂１０部
【０１２４】
【化６】

をモノクロロベンゼン５０部／ジクロロメタン２０部の混合溶媒中に溶解して調製した電荷輸送層用塗工液を用いて、前記電荷発生層上に電荷輸送層を膜厚１２μｍで形成した。
【０１２５】
次に、フラスコにコロイダルシリカ（固形分４０質量％）の水性分散液４．１部を取り、攪拌しながらコロイダルシリカ（固形分３０質量％）のイソプロピルアルコール分散液２６．５部、メチルトリエトキシシラン１．８部、γ−グリシドキシプロピルトリメトキシシラン２．４部、ｎ−パーフルオロオクチルエチルトリエトキシシラン１．１部及び酢酸３．１部を添加した。添加後、混合溶液を６５〜７０℃に加熱し、２時間反応させた。その後、イソプロピルアルコール２３．１部で希釈し、硬化触媒としてジブチル錫ジ−２−エチルヘキソエート２．８部を添加し、更にポリエーテル変成ジメチルシリコーンの１０質量％エタノール溶液０．１６部を添加し、保護層用組成物を調製し、この保護層用組成物を用いて前記電荷輸送層上に浸漬塗布後、１８０℃で１時間加熱・硬化を行い、膜厚が１．０μｍの保護層を形成し、電子写真感光体（３）を得た。
【０１２６】
この保護層用組成物による保護層のユニバーサル硬さは４１５Ｎ／ｍｍ²であった。
【０１２７】
｛電子写真感光体の製造例４｝
電子写真感光体製造例２と同様にして支持体、導電層、中間層、電荷発生層及び電荷輸送層を形成した。
【０１２８】
次いで、製造例３で使用した保護層用組成物溶液３０部に４−［Ｎ，Ｎ−ビス（３，４−ジメチルフェニル）アミノ］−［２−（トリエトキシシリル）エチル］ベンゼンを５部加え溶解し、製造例４の保護層用構成物溶液とした。この塗工液を前記電荷輸送層上に浸漬コーティングし、１８０℃で１時間加熱・硬化を行い、膜厚が１．５μｍの保護層を形成し、電子写真感光体（４）を得た。このとき保護層のユニバーサル硬さは２９０Ｎ／ｍｍ²であった。
【０１２９】
｛電子写真感光体の製造例５｝
電子写真感光体製造例３と同様にして支持体、導電層、中間層、電荷発生層及び電荷輸送層を形成した。
【０１３０】
次に、下記式で示されるアクリルモノマーを５０部、
【０１３１】
【化７】

アンチモンドープの酸化錫微粒子（商品名：Ｔ−１、三菱マテリアル製）５０部、光開始剤として２−メチルチオキサントン５部及びトルエン３００部を混合してサンドミルにて４８時間分散し、保護層用塗工液を調製した。この塗工液を用いてスプレー塗布法にて該電荷輸送層上に塗布し、乾燥した後、高圧水銀灯にて８ｍＷ／ｃｍ²の光強度にて２０秒間紫外線を照射することにより塗布膜を硬化させ、膜厚が３μｍの保護層を形成し、電子写真感光体（５）を得た。このとき保護層のユニバーサル硬さは２９０Ｎ／ｍｍ²であった。
【０１３２】
｛電子写真感光体の製造例６｝
電子写真感光体製造例３と同様にして支持体、導電層、中間層及び電荷発生層を形成した。
【０１３３】
次に、下記式に示される化合物１５部、
【０１３４】
【化８】

及び下記式で示される繰り返し単位を有し、数平均分子量Ｍｎ＝８００００のＣ型ポリカーボネート樹脂２５部
【０１３５】
【化９】

をモノクロロベンゼン８０部／ジクロロメタン５０部の混合溶媒中に溶解して調製した電荷輸送層用塗工液を用いて、前記電荷発生層上に電荷輸送層を膜厚１５μｍで形成し、電子写真感光体（６）を得た。このとき表面層のユニバーサル硬さは２３５Ｎ／ｍｍ²であった。
【０１３６】
｛電子写真感光体の比較製造例１｝
電子写真感光体製造例３と同様にして支持体、導電層、中間層及び電荷発生層を形成し、該電荷発生層上に電子写真感光体製造例３と同様な組成で膜厚を１５μｍとした電荷輸送層を形成し、比較製造例１の電子写真感光体（Ｉ）とした。このとき表面層のユニバーサル硬さは２２０Ｎ／ｍｍ²であった。
【０１３７】
｛電子写真感光体の比較製造例２｝
電子写真感光体の比較製造例１と同様にして支持体、導電層、中間層及び電荷発生層を形成し、該電荷発生層上に以下のようにして保護層を形成した。
【０１３８】
まず、フラスコにコロイダルシリカ（固形分４０質量％）の水性分散液８．７部を取り、攪拌しながらコロイダルシリカ（固形分３０質量％）のイソプロピルアルコール分散液２０．５部、メチルトリエトキシシラン２５．６部、３，３，４，４，５，５，６，６，６−ノナフルオロヘキシルトリメトキシシラン５．９部及び酢酸３．２部を添加した。添加後、混合溶液を６５〜７０℃に加熱し、２時間反応させた。その後、イソプロピルアルコール２１．７部で希釈し、硬化触媒としてベンジルトリメチルアンモニウムアセテート２．４部を添加し、更にポリエーテル変成ジメチルシリコーンの１０質量％エタノール溶液０．１６部を添加し、保護層用組成物ＩＩを作製した。この保護層用組成物ＩＩを前記電荷輸送層の上に浸漬コーティング法により塗布し、１５０℃で４時間乾燥熱処理し、膜厚が０．４μｍの保護層を形成し、比較製造例２の電子写真感光体（ＩＩ）を得た。このとき保護層のユニバーサル硬さは６８５Ｎ／ｍｍ²であった。
【０１３９】
（実施例１）
本発明の画像形成装置の実施例を説明する。実施例１の画像形成装置として市販のデジタル複写機ＧＰ−４０（キヤノン社製）を改造し、再設定した。
【０１４０】
レーザー露光装置を１２００ｄｐｉに高解像度化し、クリーニングブレードの設定圧は４０ｇ／ｃｍとし、電子写真感光体は電子写真感光体の製造例１で示したものを用いた。
【０１４１】
現像装置は、以下のように改造した。すなわち、トナー供給体であるマグネットを内包したアルミニウムスリーブの代わりにカーボンブラックを分散して抵抗を調整したシリコーンゴムからなる中抵抗ゴムローラー（直径１８ｃｍ）をトナー担持体（図２の３−１）として、電子写真感光体に当接した。トナー担持体の表面の移動方向及び回転速度は、電子写真感光体との接触部において同方向であり、電子写真感光体の回転速度に対して１５０％となるように駆動する。トナー担持体のトナーを塗布する手段としては、不図示の塗布ローラーをトナー担持体に当接させ、トナー担持体と逆方向に回転させてトナーを塗布した。トナーは、トナー製造例１で作製したトナー（Ａ）を用いた。
【０１４２】
本実施例の複写機のプロセス条件は、電子写真感光体の暗部電位、明部電位をそれぞれ−７００Ｖ、−１５０Ｖに、トナー担持体に印加する現像バイアスを−４５０Ｖ（直流成分のみ）となるように設定した。
【０１４３】
本複写機を温度湿度１５℃／１０％ＲＨの環境下に設置し、トナーを補給しつつ２０００枚の連続コピーを行い画像評価を行ったところ、１２００ｄｐｉによる画像形成においても画像濃度やドット再現性は共に非常に良好であり、クリーニング不良も発生せず、２０００枚目においても初期と同等の画像品質を得た。また、２０００枚画像出し後の電子写真感光体表面は、傷や面粗れの発生もなく、平滑な表面を保持していた。評価結果を表３に示す。
【０１４４】
（実施例２〜３）
トナーとして製造例で示したトナー（Ｂ）及び（Ｄ）を使用することを除いては、実施例１と同様に評価した。いずれの実施例においても高品質の画像が得られ、繰り返し画像出力においてもクリーニング不良は発生しなかった。結果を表３に示す。
【０１４５】
（比較例１〜５）
トナーとして比較製造例で示したトナー（ａ）〜（ｅ）を使用することを除いては、実施例１と同様に評価した。比較例１〜５においてはプリントアウト画像の評価において、特にドット再現性、飛び散り及び中抜けにおいて著しい画像不良が見られた。結果を表３に示す。
【０１４６】
【表３】

【０１４７】
（実施例４〜６）
電子写真感光体として製造例で示した電子写真感光体（３）〜（５）を使用することを除いては、実施例１と同様に評価した。
【０１４８】
いずれの実施例においても高品質の画像が得られ、繰り返し画像出力においてもクリーニング不良は発生しなかった。結果を表４に示す。
【０１４９】
（比較例６及び７）
電子写真感光体として比較製造例で示した電子写真感光体（Ｉ）及び（ＩＩ）を使用することを除いては、実施例１と同様に評価した。比較例６及び７は、共に繰り返し画像出力においてクリーニング不良が発生した。クリーニング不良は、比較例６では電子写真感光体の表面に多数発生した傷に起因し、比較例７では繰り返し画像出力中に電子写真感光体の保護層に生じた亀裂に起因して発生した。また、比較例７では繰り返し画像出力中にクリーニングブレードが反転し、継続が不可能となった。結果を表４に示す。
【０１５０】
【表４】

【０１５１】
（実施例７）
本実施例の画像形成装置について説明する。本実施例においては、市販のＬＢＰ−ＥＸ（キヤノン製）を改造し、再設定して用いた。再設定の部分は、まずレーザー露光を６００ｄｐｉから１２００ｄｐｉに改造し、クリーニングブレードの設定圧を５０ｇ／ｃｍとした。
【０１５２】
次に、現像器においてはトナー供給体であるマグネットを内包したアルミニウムスリーブの代わりにカーボンブラックを分散して抵抗を調整したシリコーンゴムからなる中抵抗ゴムローラー（直径１６ｃｍ）をトナー担持体として、電子写真感光体に当接した。トナー担持体の表面の移動方向及び回転速度は、電子写真感光体との接触部において同方向であり、電子写真感光体の回転速度に対して１４０％となるように駆動する。トナー担持体のトナーを塗布する手段としては、不図示の塗布ローラーをトナー担持体に当接させ、トナー担持体と逆方向に回転させてトナーを塗布した。更に、トナー担持体上のトナーのコート層制御のために、樹脂をコートしたステンレスブレードを取り付けた。トナーは、トナー製造例４で作製したトナー（Ｄ）を用い、電子写真感光体は製造例４で作製した電子写真感光体（４）を用いた。
【０１５３】
本実施例のＬＢＰのプロセス条件は、電子写真感光体の暗部電位、明部電位をそれぞれ−６５０Ｖ、−２００Ｖに、トナー担持体に印加する現像バイアスを−４８０Ｖ（直流成分のみ）となるように設定した。
【０１５４】
上記画像形成装置を温度湿度１０℃／８％ＲＨの環境下に設置し、トナーを補給しつつ２０００枚の連続画像出力を行い画像評価を行ったところ、１２００ｄｐｉによる画像形成においても画像は良好であり、クリーニング不良も発生せず、２０００枚目においても初期と同等の画像品質を得た。また、２０００枚画像出し後の電子写真感光体の表面は傷や面粗れの発生もなく、平滑な表面を保持していた。評価結果を表５に示す。
【０１５６】
（比較例８〜１１）
トナー及び電子写真感光体として表７に示すものを使用することを除いては、参考例３と同様に評価した。平均円形度が低いトナー（ｃ）を用いた比較例８では中抜けが特に多発し、円相当個数平均径が大きいトナー（ｄ）及び（ｅ）を用いた比較例９及び１１ではドット再現性に欠損が目立った。ユニバーサル硬度が本発明の範囲外の電子写真感光体（Ｉ）を用いた比較例８及び１０では連続画像出力において、電子写真感光体の表面に傷や表面粗れが発生し、これを起点としてクリーニング不良が発生した。また、ユニバーサル硬度が本発明の範囲外の電子写真感光体（ＩＩ）を用いた比較例９及び１１では連続画像出力において、クリーニングブレードがめくれて反転し、これによってクリーニング不良が発生した。結果を表５に示す。
【０１５７】
【表５】

【０１５８】
本発明の実施例及び比較例中に記載の評価項目の説明とその評価基準について述べる。
【０１５９】
［プリントアウト画像評価］
＜１＞画像濃度
通常の複写機用普通紙（７５ｇ／ｍ²）に所定の枚数のプリントアウトを終了した時の画像濃度により評価した。なお、画像濃度は「マクベス反射濃度計」（マクベス社製）を用いて、原稿濃度が０．００の白地部分のプリントアウト画像に対する相対濃度を測定した。
Ａ：１．４０以上
Ｂ：１．３５以上、１．４０未満
Ｃ：１．００以上、１．３５未満
Ｄ：１．００未満
【０１６０】
＜２＞ドット再現性
潜像電界によって電界が閉じ易く、再現しにくい図５に示す様な小径（５０μｍ）の孤立ドットパターンの画像をプリントアウトし、そのドット再現性を評価した。
Ａ：欠損２個以下／１００個
Ｂ：欠損３〜５個／１００個
Ｃ：欠損６〜１０個／１００個
Ｄ：欠損１１個以上／１００個
【０１６１】
＜３＞画像カブリ
「リフレクトメータ」（東京電色社製）により測定したプリントアウト画像の白地部分の白色度と転写紙の白色度の差から、カブリ濃度（％）を算出し、画像カブリを評価した。
Ａ：１．５％未満
Ｂ：１．５％以上、２．５％未満
Ｃ：２．５％以上、４．０％未満
Ｄ：４．０％以上
【０１６２】
＜４＞画像飛び散り
図６（ａ）に示した「電」文字パターンを普通紙（７５ｇ／ｍ²）と厚紙（１２８ｇ／ｍ²）にプリントした際の文字周辺部へのトナー飛び散り｛図６（ｂ）の状態｝を目視で評価した。
Ａ：ほとんど発生せず。
Ｂ：軽微な飛び散りが見られる。
Ｃ：若干の飛び散りが見られる。
Ｄ：顕著な飛び散りが見られる。
【０１６３】
＜５＞画像中抜け
図７（ａ）に示した「驚」文字パターンを厚紙（１２８ｇ／ｍ²）にプリントした際の文字の中抜け｛図７（ｂ）の状態｝を目視で評価した。
Ａ：中抜けはほとんど発生せず。
Ｂ：軽微な中抜けが見られる。
Ｃ：若干の中抜けが見られる。
Ｄ：顕著な中抜けが見られる。
【０１６４】
【発明の効果】
本発明では、径が小さく、円形度が高く、かつ円形度のそろったトナーと、表面層のユニバーサル硬さが一定範囲内の電子写真感光体とを用い、クリーニングブレードを用いるトナーのクリーニング手段を採用することによって、いかなる環境での繰り返し画像出力時においてもクリーニング不良が発生せず、安定して高い画像品質かつ高精細な画像を供給可能な画像形成装置及びプロセスカートリッジを提供することが可能となった。
【図面の簡単な説明】
【図１】本発明の画像形成装置のクリーニング装置部の概略図である。
【図２】本発明の画像写真装置の概略図である。
【図３】本発明のプロセスカートリッジを有する画像形成装置の概略図である。
【図４】本発明の別のプロセスカートリッジを有する画像形成装置の概略図である。
【図５】トナーの現像特性をチェックするための孤立ドットパターンの説明図である。
【図６】文字画像の飛び散りの状態を示す模式図である。
【図７】文字画像の中抜け状態を示す模式図である。
【符号の説明】
１ 電子写真感光体
２ 帯電手段
３ 現像手段
３−１ トナー担持体
４ 転写手段
５ クリーニング手段
５−１ クリーニングブレード
５−２ クリーニング部枠体
５−３ 金型
５−４ スクイシート
５−５ かき込み部材
５−６ 仕切り板
６ 前露光手段
７ 転写材
８ 定着手段
９ 接触帯電部材
１０ 転写用接触帯電部材
２０ 容器１
２１ 容器２
２２ 容器３[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus and a process cartridge, and more particularly, an image forming apparatus and a process cartridge having a rubber blade cleaning unit using an electrophotographic photosensitive member having a surface layer with high hardness and a toner having a high degree of circularity. About. The image forming apparatus of the present invention is applied to a copying machine, a laser printer, a plain paper facsimile, and the like.
[0002]
[Prior art]
In recent years, with rapid development of the information industry, high-quality image recording has been desired for industrial or office use. In response to these demands, various methods such as an electrophotographic method, a thermal transfer method, and an ink jet method have been proposed and put into practical use. Among them, the electrophotographic method is frequently used in offices because of its high-speed printability and merits of high image quality. Recently, there have been many cases of recording graphic images, and further higher image quality and higher definition have been achieved. It has been demanded. In response to these market demands, the resolution of laser printers has been increased from 240 dpi to 600 and 1200 dpi, and higher image quality in electrophotographic devices, such as digitalization and higher resolution in copiers, etc. And high definition.
[0003]
In response to these movements, development of precision processing technology and development and use of high-precision control technology have been proposed and studied from the device development side, but from the toner development side, the toner size is reduced. The development of high image quality due to toner and high-definition and high-definition technical development using toner with a high degree of circularity are being actively carried out. In order to improve the circularity of these toners, a conventional method of kneading, pulverizing, and classifying a colorant and a binder resin to obtain a toner is used. On the other hand, a polymerized toner obtained by polymerizing an ethylenically unsaturated monomer containing a colorant in water in the presence of a dispersant is attracting attention. Research and development has been conducted energetically, and it has been confirmed that polymerized toner is an effective means for reducing the toner diameter and improving the circularity. This small diameter and high circularity toner faithfully and accurately develops the electrostatic latent image on the electrophotographic photosensitive member, and also exhibits high transferability to improve image quality and definition. While it has a great effect, problems such as poor cleaning may occur during a printing test with a copier or printer.
[0004]
In image forming apparatuses such as copiers and printers, a toner image formed on the surface of an electrophotographic photosensitive member is conventionally transferred to a transfer material, and then untransferred toner remains on the surface of the electrophotographic photosensitive member. The toner is removed from the surface of the electrophotographic photosensitive member with a brush, a magnetic brush, a blade, or the like.
[0005]
For brush cleaning, polyester and acrylic fibers are used, and are optimized and used by changing the shape of loops and straight hairs, the hardness and thickness of the fibers, and the like. However, cleaning with only a brush cannot remove fine toner, and it is difficult to pass through the fibers and remove them sufficiently. The same applies to magnetic brushes, and attempts have been made to remove electrostatically by applying an electric field, but toner scattering occurs and is not sufficient. Therefore, at present, as a cleaning means, blade cleaning using an elastic blade is mainly used from the standpoint of removing residual toner, cost, and miniaturization.
[0006]
There are many reports on improvements in blade cleaning, which are disclosed in numerous patent publications. For example, Japanese Patent Laid-Open No. 5-35156 discloses examination results of physical property values such as hardness, elastic modulus and elongation of a urethane rubber blade and cleaning characteristics.
[0007]
In this way, blade cleaning has high cleaning performance compared to other methods, but when the above-mentioned toner with a small diameter and high circularity is cleaned, it is sufficient in all environments where copiers and printers are used. It is difficult to exhibit a good cleaning performance, and cleaning defects tend to occur particularly in an environment of high temperature and high humidity and low temperature and low humidity.
[0008]
On the other hand, as an electrophotographic photosensitive member used in an electrophotographic apparatus, an organic electrophotographic photosensitive member is often used for reasons such as production cost and chemical safety. Most organic electrophotographic photoreceptors are composed of two layers, a charge generation layer and a charge transport layer. In the cleaning described above, the charge transport layer contacts and slides against the toner and the blade. Therefore, the surface of the electrophotographic photosensitive member is damaged and worn. The scratches and uneven wear of the photosensitive layer cause uneven contact between the cleaning blade and the surface of the electrophotographic photosensitive member, which contributes to poor cleaning. Therefore, when blade cleaning is performed on a conventional organic electrophotographic photosensitive member, cleaning failure tends to occur during repeated use. Further, if the contact pressure of the cleaning blade to the surface of the electrophotographic photosensitive member is increased in order to improve the cleaning property, the initial cleaning property is improved. However, in repeated image output, the surface of the electrophotographic photosensitive member is not damaged or damaged. There was a tendency that uniform wear was further increased, and as a result, the cleaning performance was liable to deteriorate.
[0009]
To solve this problem, JP-A-63-65449 discloses that the wear amount is reduced by adding silicone resin fine particles or fluororesin fine particles to the photosensitive layer. The layer is still low in mechanical strength, and the toner additive, such as silica, alumina and titania, is an abrasive that digs deep grooves in the photosensitive layer by sliding between the electrophotographic photosensitive member and the blade. Scratches are likely to occur, such as wear, and are not sufficient for preventing poor cleaning.
[0010]
As described above, toner with a small diameter and high circularity faithfully and accurately develops an electrostatic latent image on an electrophotographic photosensitive member, and exhibits high transferability to improve image quality and definition. However, in a system using an organic electrophotographic photosensitive member and a cleaning blade, which is advantageous in terms of cost and downsizing, it is very difficult to perform stable cleaning in all usage environments. However, the current situation is that it has not been completely solved.
[0011]
[Problems to be solved by the invention]
As described above, in an image forming apparatus using a toner having a small diameter and high circularity, there is a problem in blade cleaning properties in an electrophotographic photosensitive member, particularly an organic electrophotographic photosensitive member, and improvement thereof has been demanded.
[0012]
The object of the present invention is to prevent occurrence of defective cleaning even in an electrophotographic developing method using a toner having a small diameter and high circularity as a toner, excellent in characteristics at the time of repeated image output, high image quality and high definition image. An object of the present invention is to provide an image forming apparatus and a process cartridge that can be supplied.
[0013]
[Means for Solving the Problems]
  According to the present invention, in an image forming apparatus having at least an organic electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit having toner, a transfer unit, a fixing unit, and a cleaning unit,
  In the toner-based circle equivalent diameter-circularity scattergram measured by the flow particle image measuring device, the toner equivalent circle average diameter is2.3~4.1μm and average circularity is0.979~0.994And the circularity standard deviation is0.025-0.030Dry toner(However, this excludes dry toners that contain at least a binder resin, a colorant, and a wax, and a siloxane-modified polycarbonate resin is present on the surface of the toner particles.)And
  The cleaning means is a cleaning means using at least a rubber blade;
  The organic electrophotographic photoreceptor has a support, a charge generation layer containing a charge generation material and a binder resin, and a charge transport layer containing a charge transport material and a binder resin in this order. The surface layer of the organic electrophotographic photosensitive member contains a cured resin and has a universal hardness of 268 N / mm.²415 N / mm or more²Is
An image forming apparatus is provided.
[0014]
  Further, according to the present invention, in the process cartridge in which the developing unit having toner and the cleaning unit are configured together with the organic electrophotographic photosensitive member,
  In the toner-based circle equivalent diameter-circularity scattergram measured by the flow particle image measuring device, the toner equivalent circle average diameter is2.3~4.1μm and average circularity is0.979~0.994And the circularity standard deviation is0.025-0.030Dry toner(However, this excludes dry toners that contain at least a binder resin, a colorant, and a wax, and a siloxane-modified polycarbonate resin is present on the surface of the toner particles.)And
  The cleaning means is a cleaning means using at least a rubber blade;
  The organic electrophotographic photoreceptor has a support, a charge generation layer containing a charge generation material and a binder resin, and a charge transport layer containing a charge transport material and a binder resin in this order. The surface layer of the organic electrophotographic photosensitive member contains a cured resin and has a universal hardness of 268 N / mm.²415 N / mm or more²Is
A process cartridge is provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0016]
  The toner used in the image forming apparatus of the present invention is a toner having a small particle size and high circularity. The average number of equivalent circles of toner2.3~4.1μm andBy reducing the diameter, the reproducibility in the development of the contour portion of the image, particularly the character image or the line pattern is improved. However, generally, when the toner particle size is reduced, the abundance ratio of the toner having a small particle size inevitably increases, so that the adhesion force of the toner to the surface of the electrophotographic photosensitive member and the toner carrier increases. As a result, problems such as an increase in residual toner and occurrence of image fogging have been caused.
[0017]
  Therefore, in the present invention, the circularity of the toner used is increased, and the average circularity is0.979~0.994And the circularity standard deviation is0.025 to 0.030As a result, the transferability of the toner having a small particle diameter, which has been difficult in the prior art, can be greatly improved and the developing ability for a low potential latent image can be remarkably improved.
[0018]
The equivalent circle diameter, circularity, and frequency distribution of the toner used in the present invention are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, the flow type particle image measuring apparatus is used. Measurement was performed using an FPIA-1000 type (manufactured by Toa Medical Electronics Co., Ltd.), and calculation was performed using the following formula.
[0019]
[Expression 1]

[0020]
Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define.
[0021]
The circularity in the present invention is an index indicating the degree of unevenness of the toner particles, and is 1.00 when the toner particles are perfectly spherical. The more complicated the surface shape, the smaller the circularity.
[0022]
In the present invention, a circle-equivalent number average diameter d, which means the average value of the particle size frequency distribution based on the number of toners.₁And the particle size standard deviation SDd are the particle size (center value) at the dividing point i of the particle size distribution, di, and the frequency f_iThen, it is calculated from the following formula.
[0023]
[Expression 2]

[0024]
Further, the average circularity c and the circularity standard deviation SDc, which mean the average value of the circularity frequency distribution, are ci and circularity (center value) at the division point i of the particle size distribution, and frequency is f._ciThen, it is calculated from the following equation.
[0025]
[Equation 3]

[0026]
As a specific measurement method, 10 ml of ion-exchanged water from which impure solids and the like are previously removed is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measurement is performed. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic dispersion machine UH-50 type (manufactured by SMT Co., Ltd.) equipped with a φ5 mm titanium alloy chip as a vibrator is used, and a dispersion for measurement is made using a dispersion treatment for 5 minutes. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more.
[0027]
To measure the shape of the toner particles, the flow type particle image measuring device is used, the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 / μl, and 1000 toner particles are obtained. Measure above. After the measurement, this data is used to determine the equivalent circle diameter of the toner, the circularity frequency distribution, and the like.
[0028]
As the wax component used in the toner used in the present invention, petroleum wax such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon wax and derivatives thereof by Fischer-Tropsch method, Polyolefin waxes represented by polyethylene and derivatives thereof, carnauba wax, candelilla wax, natural waxes and derivatives thereof, etc., including oxides, block copolymers with vinyl monomers, graft modified products, Further, alcohols such as higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid or compounds thereof; acid amides, esters, ketones, hydrogenated castor oil and derivatives thereof, plant waxes, animal waxes, styrene monomers As long as the melting temperature of 40 to 80 ° C. to, it is possible to use any.
[0029]
Of these, polyolefin, Fischer-Tropsch hydrocarbon wax, petroleum wax, higher alcohol, or higher ester can further improve the developability and transferability.
[0030]
The wax component described above is preferably used in an amount of 1 to 30 parts by mass with respect to 100 parts by mass of the binder resin.
[0031]
Examples of the binder resin used in the toner of the present invention include commonly used styrene- (meth) acrylic copolymers, polyester resins, epoxy resins, and styrene-butadiene copolymers. In a method for directly obtaining toner particles by a polymerization method, a monomer for forming them is used.
[0032]
Specifically, styrene; styrene monomers such as o- (m-, p-) methylstyrene, m- (p-) ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, (meth ) Propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) acrylic acid ester monomers such as dimethylaminoethyl acrylate and diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile and acrylamide Preferably used. These may be used alone or in general so that the theoretical glass transition temperature (Tg) described in the publication Polymer Handbook 2nd edition III-P139-192 (John Wiley & Sons) is 40-75 ° C. It is used by mixing the body appropriately. When the theoretical glass transition temperature is less than 40 ° C., problems are likely to occur from the viewpoint of storage stability and durability stability of the toner, while when it exceeds 75 ° C., the fixing point of the toner is increased. In particular, in the case of a color toner for forming a full-color image, the color mixing property at the time of fixing each color toner is lowered, color reproducibility is poor, and transparency of the OHP image is further lowered.
[0033]
The molecular weight of the binder resin is measured by gel permeation chromatography (GPC). As a specific GPC measurement method, toner is extracted with a toluene solvent in advance using a Soxhlet extractor for 20 hours, and then the toluene is distilled off with a rotary evaporator to obtain an extract. Further, the low softening point substance is dissolved. An organic solvent that does not dissolve the outer shell resin (such as chloroform) is added to the extract and washed thoroughly, and then a solution obtained by dissolving the residue in tetrahydrofuran (THF) is added to a solvent-resistant membrane having a pore diameter of 0.3 μm. A sample filtered with a filter (THF solution) is measured using 150C manufactured by Waters. As for the column configuration, A-801, 802, 803, 804, 805, 806 and 807 manufactured by Showa Denko can be connected, and the molecular weight distribution can be measured using a standard polystyrene resin calibration curve. The main peak molecular weight of the binder resin according to the present invention is 5,000 to 1,000,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2 to 100. Is preferred.
[0034]
Examples of the colorant used in the toner used in the present invention include the following yellow colorant, magenta colorant, and cyan colorant. As the black colorant, carbon black, a magnetic material, or the following yellow colorant / magenta A colorant / cyan colorant mixed to black is used.
[0035]
As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, allylamide compounds, and the like are used. Specifically, C.I. I. Pigmecito yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168 and 180 are preferably used.
[0036]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, and the like are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254 are particularly preferred.
[0037]
As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62 and 66 can be used particularly suitably.
[0038]
These colorants can be used alone or in combination and further in the form of a solid solution. The colorant is selected from the viewpoints of hue, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner particles. The addition amount of the colorant is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the resin component.
[0039]
When a magnetic material is used as the black colorant, it is preferable to use 40 to 150 parts by mass with respect to 100 parts by mass of the resin, unlike other colorants.
[0040]
A known charge control agent can be used for the toner used in the present invention, and a charge control agent that has a high charging speed and can stably maintain a constant charge amount is particularly preferable. Further, when the direct polymerization method is used in the present invention, a charge control agent having no polymerization inhibition and no solubilized product in an aqueous system is preferable.
[0041]
Specific examples of the negative compound include salicylic acid, naphthoic acid, dicarboxylic acid or its derivative metal compound, azo pigment or its derivative metal compound, sulfonic acid, polymer compound having carboxylic acid in the side chain, boron Compounds, urea compounds, silicon compounds, calixarenes, and the like can be used. As the positive system, nigrosine, triphenylmethane compound, quaternary ammonium salt, polymer compound having quaternary ammonium salt in the side chain, guanidine compound, imidazole compound and the like are preferably used. However, in the present invention, it is not essential to add another charge control agent, and even in the case of using a non-magnetic one-component blade coating development method, the triboelectric charge with the blade member or sleeve member is positively used in the toner. It is not always necessary to include another charge control agent.
[0042]
Addition of inorganic fine powder to the toner used in the present invention is a preferred embodiment for improving developability, transferability, charging stability, fluidity and durability. As the inorganic fine powder, known ones can be used, and it is particularly preferred to be selected from silica, alumina and titania or a double oxide thereof. Further, silica is more preferable. For example, the silica can be a so-called dry process produced by vapor phase oxidation of silicon halides or alkoxides, or dry silica called fumed silica and alkoxides, so-called wet silica produced from water glass, etc. can be used. However, there are few silanol groups on the surface and inside the silica fine powder, and Na₂O or SO_Three ^2-For example, dry silica with less production residue is preferred. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Yes, including them.
[0043]
The inorganic fine powder used in the toner used in the present invention has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.²/ G or more, especially 50-400m²/ G range gives good results, 0.1 to 8 parts by weight of fine silica powder, preferably 0.5 to 5 parts by weight, and more preferably more than 1.0 to 100 parts by weight of toner. It is particularly good to use up to 3.0 parts by weight.
[0044]
In addition, the inorganic fine powder used in the toner used in the present invention is optionally made of silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane couplings for the purpose of hydrophobicity or charge control. It is also possible to treat with an agent, a silane coupling agent having a functional group, and other treating agents such as organic silicon compounds and organotitanium compounds, or in combination with various treating agents.
[0045]
The specific surface area was calculated according to the BET method by using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics Co., Ltd.) to adsorb nitrogen gas on the sample surface and calculating the specific surface area using the BET multipoint method.
[0046]
In order to maintain a high charge amount and achieve a low consumption and a high transfer rate, the inorganic fine powder is more preferably treated with at least silicone oil.
[0047]
In the toner used in the present invention, other additives within a range that does not have a substantial adverse effect, for example, lubricant powder such as polytetrafluoroethylene powder, zinc stearate powder, polyvinylidene fluoride powder; cerium oxide powder, Polishing agents such as silicon carbide powder and strontium titanate powder; fluidity imparting agents such as titanium oxide powder and aluminum oxide powder; anti-caking agents or conductivity imparting such as carbon black powder, zinc oxide powder and tin oxide powder In addition, a small amount of a reverse polarity organic fine particle and inorganic fine particle can also be used as a developability improver.
[0048]
As a method for producing the toner used in the present invention, a resin, a release agent composed of a low softening point substance, a colorant, a charge control agent, and the like are uniformly dispersed using a pressure kneader, a kixtruder, or a media disperser. After that, it is made to collide with the target under a mechanical or jet stream and finely pulverized to a desired toner particle size, and if necessary, a step of smoothing and spheroidizing the toner particles is added, followed by a classification step. In addition to a toner production method by a pulverization method in which the particle size distribution is sharpened and the toner is made into a toner, the molten mixture is atomized in the air using a disk or a multi-fluid nozzle disclosed in Japanese Patent Publication No. 56-13945, etc. And a suspension polymerization method described in JP-B-36-10231, JP-A-59-53856, and JP-A-59-61842. Toner directly polymerized in the presence of a water-soluble polar polymerization initiator or a method for directly producing toner, a dispersion polymerization method in which an aqueous organic solvent in which the monomer is soluble and the resulting polymer is not soluble is used. The toner can be produced by using an emulsion polymerization method typified by a soap-free polymerization method for producing a toner.
[0049]
In the method of producing toner using the pulverization method, it is difficult to keep the shape of the toner particles within a desired circularity frequency distribution range. In the melt spray method, a certain degree of circularity can be obtained. In addition, the particle size distribution of the obtained toner tends to be wide, and it is difficult to control the surface state of the toner. On the other hand, in the dispersion polymerization method, the obtained toner shows a very sharp particle size distribution, but the production equipment is used from the viewpoint of the processing of the waste solvent and the flammability of the solvent due to the narrow selection of materials to be used and the use of organic solvents. Complex and easy to complicate. The emulsion polymerization method represented by soap-free polymerization is effective because the particle size distribution of the toner is relatively uniform. However, when the used emulsifier or polymerization initiator terminal is present on the toner particle surface, the environmental characteristics are easily deteriorated.
[0050]
  In the present invention, it is important to control the frequency distribution of the circularity of the toner particles.2.3~4.1Using an emulsion polymerization method or a suspension polymerization method under normal pressure or under pressure to obtain a fine particle toner of μm, the polymer obtained in advance is shaped using a medium, or the polymer is directly applied to a pressure collision plate. A method of colliding, and further a method of freezing the obtained polymer in an aqueous system or agglomerating and coalescing particles having a salt break or opposite surface charge by considering conditions such as pH. Is particularly preferred. Furthermore, a seed polymerization method in which a monomer is further adsorbed to the obtained polymer particles and then polymerized using a polymerization initiator can be suitably used in the present invention.
[0051]
When the direct polymerization method is used as a toner production method, the control of the toner particle circularity frequency distribution and particle size frequency distribution changes the kind and addition amount of a poorly water-soluble inorganic salt and a protective colloid dispersing agent. Obtain predetermined toner particles by controlling the method and mechanical device conditions (for example, the circumferential speed of the rotor, the number of passes, the stirring conditions such as the shape of the stirring blades and the shape of the container), or the solid content concentration in the aqueous solution. Can do.
[0052]
Further, when the toner is heated and dried, the toner particles can be spheroidized. For example, by using a fluidized bed dryer and adjusting the stirring conditions of the rotor blades and the processing time, the toner particle shape is preferable. It can be.
[0053]
By specifying the physical properties of the wax component as described above, the toner of the present invention minimizes the influence of toner coarsening and the wax component on the spheroidizing treatment of the toner particles as described above. Can be very effective.
[0054]
When the toner is produced by the direct polymerization method, examples of the polymerization initiator used include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1. Azo or diazo polymerization initiators such as' -azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl peroxide Peroxide-based polymerization initiators such as methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide are used. The amount of the polymerization initiator used varies depending on the desired degree of polymerization, but is generally 0.5 to 20% by mass based on the polymerizable monomer. The kind of the polymerization initiator varies slightly depending on the polymerization method, but is used alone or in combination with reference to the 10-hour half-life temperature.
[0055]
In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor and the like may be further added and used.
[0056]
When a suspension polymerization method using a dispersion stabilizer is used as a toner production method, the dispersion stabilizer used is an inorganic compound such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, Examples include magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, and alumina. Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and its salt, and starch. These can be used by dispersing in an aqueous phase. These dispersion stabilizers are preferably used in an amount of 0.2 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer.
[0057]
When an inorganic compound is used as the dispersion stabilizer, a commercially available product may be used as it is, but in order to obtain fine particles, fine particles of the inorganic compound may be generated in a dispersion medium. For example, in the case of tricalcium phosphate, a sodium phosphate aqueous solution and a calcium chloride aqueous solution may be mixed under high-speed stirring.
[0058]
For fine dispersion of these dispersion stabilizers, 0.001 to 0.1 parts by mass of a surfactant may be used in combination. This is to promote the intended action of the dispersion stabilizer, for example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, stearic acid Examples include potassium and calcium oleate.
[0059]
When the direct polymerization method is used as a method for producing the toner used in the present invention, the following production method is possible.
[0060]
A release agent consisting of a low softening point substance, a colorant, a charge control agent, a polymerization initiator and other additives were added to the polymerizable monomer, and the mixture was uniformly dissolved or dispersed by a homogenizer or an ultrasonic disperser. The monomer composition is dispersed in a water phase containing a dispersion stabilizer by a normal stirrer, a homomixer, a homogenizer, or the like. Preferably, the monomer composition is granulated by adjusting the stirring speed and stirring time so that the droplets of the monomer composition have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. The polymerization is preferably performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction, and for the purpose of improving durability in the image forming method of the present invention, in order to remove unreacted polymerizable monomers and by-products, the latter half of the reaction, or After completion of the reaction, a part of the aqueous medium may be distilled off from the reaction system. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer composition.
[0061]
The developing method in the image forming apparatus of the present invention may be either a regular developing method represented by a copying machine or a reversal developing method represented by a laser printer. The developing method is a two-component magnetic brush developing method or a magnetic one-component developing method. Either a developing method or a non-magnetic one-component developing method may be used.
[0062]
  The organic electrophotographic photosensitive member is obtained by providing a photosensitive layer on a conductive support. The photosensitive layer generally comprises a charge generation material, a charge transport material, and a binder resin.Is the electricMultilayer type consisting of a charge generation layer containing a load generating material and a charge transport layer containing a charge transport materialIs. In the case of a multilayer electrophotographic photosensitive member, the electrophotographic photosensitive member is laminated in the order of a charge generation layer and a charge transport layer on a conductive support.Is. ThisPower ofIn an electrophotographic photoreceptor in which a charge generation layer containing a load generating material and a charge transport layer containing a charge transport material are laminated in this order, good photoreceptor characteristics such as higher sensitivity and higher stability can be obtained. It is also possible to provide a protective layer on the photosensitive layer for the purpose of improving the durability of the electrophotographic photosensitive member. By providing a layer having high hardness specialized for improving durability as a protective layer, it is possible to achieve both the durability of the electrophotographic photosensitive member and the electrical characteristics of the electrophotographic photosensitive member such as sensitivity and residual potential.
[0063]
  The surface layer of the electrophotographic photosensitive member used in the present invention has a surface hardness and a universal hardness when the surface layer is formed on a glass plate.268 N / mm ² 415 N / mm or more ² It is as follows. YuNiversal hardness is 230 N / mm²If it is less than the above, in the apparatus of the present invention, cleaning defects are likely to occur, and scratches and uneven wear occur on the surface of the electrophotographic photosensitive member particularly during durability, and this causes frequent cleaning defects. Universal hardness is 500 N / mm²When the image output is repeated many times, the frictional force between the surface of the electrophotographic photosensitive member and the cleaning blade increases, and as a result, the blade tip vibrates or turns up, which tends to cause defective cleaning. It is in. This is presumably because the hardness of the surface of the electrophotographic photosensitive member is too high, and it is difficult to remove the outermost surface that has deteriorated due to charging or the like and has decreased slipperiness. Universal hardness is 500 N / mm²If it exceeds 1, the surface layer is likely to crack due to impact or the like. This is considered because there is an excessively large difference in hardness between the surface layer and the layer below it.
[0064]
The surface hardness of the surface layer of the electrophotographic photosensitive member of the present invention is determined by universal hardness (Hu: unit N / mm) according to instrumented indentation methods.²) To measure.
[0065]
In the present invention, universal hardness is HelmutFischerGMBH + Co. The measurement was carried out using a FISCHERSCOPEH 100V manufactured by the manufacturer. The sample was formed with a film thickness of 4 to 5 μm on a glass plate. The indentation depth of the indenter was 1 μm.
[0066]
  In the present invention, the surface layer means the universal hardness of the coating film.268N / mm²more than415N / mm²A layer formed by the following film, which is a layer provided on the surface of the electrophotographic photosensitive member. Therefore,Laminated in the order of a charge generation layer and a charge transport layer on a conductive supportIn the case of a multilayer electrophotographic photoreceptorIs electricCargo transportationLayerWhen a protective layer is provided, the protective layer is the surface layer. They have universal hardness268N / mm²more than415N / mm²It is formed by the following film. The organic electrophotographic photosensitive member used in the present invention has a surface layer.Contains a curable resin, andUniversal hardness268N / mm²more than415N / mm²Inis there.
[0067]
  Universal hardness268N / mm²more than415N / mm²A specific example of an electrophotographic photoreceptor having a surface layer as described below will be described by taking an electrophotographic photoreceptor in which a charge generation layer / charge transport layer are laminated in this order as an example. In this case, the universal hardness of the charge transport layer268N / mm²more than415N / mm²IsThe
[0068]
The support of the electrophotographic photosensitive member may be any material having conductivity, for example, aluminum, copper, chromium, nickel, zinc, stainless steel or other metal or alloy formed into a drum or sheet, aluminum and copper Metal foils such as those laminated on plastic films, aluminum, indium oxide and tin oxide deposited on plastic films, metals with conductive layers applied alone or with binder resin, and plastic Examples include films and paper.
[0069]
In the electrophotographic photoreceptor used in the present invention, an intermediate layer having a barrier function and an adhesive function can be provided on the conductive support.
[0070]
The intermediate layer is used for improving the adhesion of the photosensitive layer, improving the coating property, protecting the support, covering defects on the support, improving the charge injection property from the support, and protecting the photosensitive layer from electrical breakdown. Formed. Examples of the intermediate layer material include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, N-methoxymethylated 6 nylon, copolymer nylon, glue and gelatin. Is mentioned. These are dissolved in a solvent suitable for each and coated on a support. The film thickness at that time is preferably 0.1 to 2 μm.
[0071]
When the electrophotographic photosensitive member of the present invention is a laminated type electrophotographic photosensitive member, a charge generation layer and a charge transport layer are laminated. Examples of the charge generation material used for the charge generation layer include selenium-tellurium, pyrylium, thiapyrylium dyes, various central metals and crystal systems, specifically, crystal types such as α, β, γ, ε, and X types. Phthalocyanine compounds, anthanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, monoazo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine pigments, quinocyanines and amorphous materials described in JP-A No. 54-14364 Examples include silicone.
[0072]
In the case of a laminate type electrophotographic photosensitive member, the charge generation layer is composed of the charge generation material 0.3 to 4 times the amount of binder resin and solvent, homogenizer, ultrasonic dispersion, ball mill, vibration ball mill, sand mill, attritor and roll mill. The film is well dispersed by a method such as the above, and a dispersion is applied and dried, or is formed as a single composition film such as a vapor deposition film of the charge generation material. The film thickness is preferably 5 μm or less, and particularly preferably in the range of 0.1 to 2 μm.
[0073]
Examples of using binder resins are polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride, trifluoroethylene, polyvinyl alcohol, polyvinyl Examples include acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, and epoxy resin.
[0074]
  The charge transport layer of the multilayer electrophotographic photoreceptor is generally a layer in which a low molecular weight charge transport material is molecularly dispersed in a binder resin.268N / mm²more than415N / mm²As long as it is the following film, a film in which a low molecular weight charge transport material is dispersed in the binder resin can also be used.
[0075]
The charge transport material in this case is not particularly limited, and examples thereof include hydrazone derivatives, butadiene derivatives, triphenylamine derivatives, stilbene derivatives, pyrazoline derivatives, and oxadiazole derivatives.
[0076]
  As the binder resin, polymethyl methacrylate resin, polycarbonate resin, polyester resin, polyarylate resin and the like are generally used, but in the charge transport layer in which the low molecular weight charge transport material as described above is dispersed in the binder resin, The film hardness greatly depends on the universal hardness of the binder resin. In addition, since the low molecular weight charge transport material is molecularly dispersed, the film hardness of the charge transport layer is much lower than that of the binder resin itself. Therefore, the universal hardness used in the present invention is268N / mm²more than415N / mm²In order to obtain the following charge transport layer by a film in which a low molecular weight charge transport material is molecularly dispersed in a binder resin, a high-hardness and high-molecular weight resin such as polycarbonate resin is selected as the binder resin. Furthermore, it is necessary to reduce the content of the low molecular weight charge transport material as much as possible.
[0077]
  Since the pencil hardness of the charge transport layer is determined by many factors as described above, it is not generally determined, but depending on the combination of the binder resin and the charge transport material, and further the selection of the mixing ratio of the binder resin and the charge transport material. Universal hardness268N / mm²more than415N / mm²The following is achieved: For example, when a polycarbonate resin having a weight average molecular weight of 40,000 or more and a charge transport material of a triphenylamine derivative or a stilbene derivative are mixed at an appropriate ratio, the hardness of the charge transport layer is268N / mm²more than415N / mm²It can be:
[0078]
  Universal hardness for charge transport layer268N / mm²more than415N / mm²As a method described below, it is very effective to use a polymer charge transport material as the charge transport material. As described above, when the charge transport material having a low molecular weight is dispersed in the binder resin, the polymer charge transport material is used compared to the case where the hardness is significantly reduced compared to the original binder resin. In this case, the hardness of the polymer charge transporting material itself is high, and the above-described decrease in hardness hardly occurs.
[0079]
  As the polymer charge transport material used in the present invention, a known polymer charge transport material can be used. For example, a polymer having a carbazole ring in the main chain and / or side chain as represented by poly-N-vinylcarbazole, a polymer having a hydrazone structure in the main chain and / or side chain, the main chain and / or side Examples include, but are not limited to, a polymer having a tertiary amine structure in the chain, a polysilane compound, and the like. A polymer or graft polymer can also be used. These polymer charge transport materials may be used alone to form a charge transport layer, or may be mixed with other binder resins to form a charge transport layer as in the case of the low molecular weight charge transport material. At this time, the universal hardness of the charge transport layer268N / mm²more than415N / mm²In order to achieve this, it is necessary to determine the type of resin to be mixed, the mixing ratio, and the like.
[0080]
As described above, the electrophotographic photosensitive member used in the present invention has been described by way of an example of a laminated type electrophotographic photosensitive member in which a charge generation layer / a charge transport layer are laminated in this order. As described above, the electrophotographic photosensitive member is a photosensitive layer. It is also effective to provide a protective layer on the electrophotographic photosensitive member for the purpose of improving the durability of the electrophotographic photosensitive member on the balance between the durability of the electrophotographic photosensitive member and the electrical characteristics of the electrophotographic photosensitive member such as sensitivity and residual potential. is there.
[0081]
  Protective layerIs the productIt is formed on a layer type photosensitive layer. The protective layer of the electrophotographic photoreceptor of the present invention has a universal hardness.268N / mm²more than415N / mm²There is no particular limitation except that the following is necessary. Protective layer configurationThe treeSubstances that contain fat as the main component and control the electrical resistance of the film, such as conductive particles, ionic conductive compoundsOrProtection by forming a highly durable film while maintaining the sensitivity and residual potential required for electrophotographic photoreceptors by mixing conductive polymers, etc.In layersis there.ThisEven in the case of universal hardness268N / mm²more than415N / mm²If it is below, it can be used as the protective layer of the electrophotographic photosensitive member of the present invention, and a known protective layer can be used.
[0082]
  As an example of the former, JP-A-4-226469 discloses a protective layer formed by polymerizing a curable acrylic monomer having a trifunctional or higher functional acrylic (methacrylic) group. -30847 and Japanese Patent Laid-Open No. 60-4945, etc., of which the universal hardness of the film is268N / mm²more than415N / mm²The following can be used as a protective layer for the electrophotographic photoreceptor used in the present invention.
[0084]
Various additives can be added to the surface layer of the electrophotographic photosensitive member used in the present invention. Additives include deterioration inhibitors such as antioxidants and ultraviolet absorbers, and lubricants such as fluorine atom-containing resin fine particles.
[0085]
In the present invention, blade cleaning is used in the cleaning step. As the diameter of the electrophotographic photosensitive member is reduced, the space becomes smaller and a small size is desired, and the residual toner must be removed when toner having a sufficiently small diameter and high circularity is used at high speed. For this purpose, it is necessary to select a rubber blade. Further, the toner having a small diameter and high circularity used in the present invention has a high degree of cleaning difficulty. In order to clean this, it is preferable that the cleaning blade is opposed to the counter with respect to the rotation direction of the electrophotographic photosensitive member, and the contact pressure against the electrophotographic photosensitive member is set to be relatively high. The stress on the surface of the electrophotographic photosensitive member by the cleaning blade varies depending on the blade contact method, pressure, angle, blade material, toner material and shape, etc., and this causes damage to the electrophotographic photosensitive member surface during repeated use. Is also greatly affected. In particular, when the contact pressure of the cleaning blade is increased, the possibility of damage such as scraping or scratching on the surface of the electrophotographic photosensitive member increases, but the universal hardness of the present invention is 230 N / mm.²500 N / mm or more²By using an electrophotographic photosensitive member surface layer having the following hardness, it is possible to achieve both stable cleaning of toner having a small diameter and high circularity and durability of the electrophotographic photosensitive member.
[0086]
The material used for the cleaning blade used in the present invention is not particularly limited, and general-purpose elastic materials are often used. For example, various rubbers such as polyurethane, silicone rubber, fluororubber, natural rubber, SBR, BR, IR, NBR, CR, ACM, ANN, and CSM are often used. May be coated.
[0087]
In addition, the manufacturing method includes a method of injecting a raw material into a mold (casting method), a method of injecting a raw material into the inner surface of a cylindrical mold drum, reacting while rotating the drum, There is a forming method (centrifugal molding method).
[0088]
FIG. 1 shows an outline of the cleaning unit of the image forming apparatus of the present invention. The cleaning device is provided on the electrophotographic photosensitive member after the transfer process, and removes the developer remaining on the electrophotographic photosensitive member 1 (photosensitive drum) without being transferred by the cleaning blade 5-1. The removed developer is collected in the container by the scraping member 5-5. In the cartridge system, the electrophotographic photosensitive member shown in this figure, the cleaning device, and the waste developer container are configured as an integral unit, and are often used in combination with the developer container and the developing device. . 5-2 is a frame, 5-3 is a metal fitting, 5-4 is a squeeze sheet, and 5-6 is a partition plate.
[0089]
Next, the image forming apparatus of the present invention will be described. In FIG. 2, the drum-type electrophotographic photosensitive member 1 is rotationally driven at a predetermined peripheral speed in the direction of an arrow about a shaft 1a. The electrophotographic photosensitive member 1 is uniformly charged at a predetermined positive or negative potential on its peripheral surface by the charging means 2 during the rotation process, and then exposed to exposure light L (slit exposure or laser by an exposure means not shown in the exposure section. Beam scanning exposure). Thereby, electrostatic latent images corresponding to exposure are sequentially formed on the peripheral surface of the electrophotographic photosensitive member. The electrostatic latent image is then developed with toner by the developing means 3, and the toner developed image is transferred between the electrophotographic photosensitive member 1 and the transfer means 4 from a sheet feeding unit (not shown) by the corona transfer means 4. The images are sequentially transferred onto the surface of the transfer material 7 taken out and fed in synchronization with the rotation of the body 1. The transfer material 7 that has received the image transfer is separated from the surface of the electrophotographic photosensitive member, introduced into the fixing means 8, and subjected to image fixing, thereby being printed out to the outside as an image formed product (print, copy). The surface of the electrophotographic photoreceptor 1 after the image transfer is cleaned by removing the transfer residual toner by the cleaning unit 5, subjected to the charge removal process by the pre-exposure unit 6, and repeatedly used for image formation. As the uniform charging means 2 of the electrophotographic photosensitive member 1, a corona charging device is generally widely used.
[0090]
Further, as shown in FIGS. 3 and 4, the contact charging member 9 is used as a charging means, and the electrophotographic photosensitive member 1 is charged by bringing the contact charging member 9 to which voltage is applied into contact with the electrophotographic photosensitive member 1. (This charging method is hereinafter referred to as contact charging). In the apparatus shown in FIGS. 3 and 4, the toner image on the electrophotographic photosensitive member 1 is also transferred to the transfer material 7 by the contact charging member 10. That is, the toner image on the electrophotographic photosensitive member 1 is transferred to the transfer material 7 by bringing the contact charging member 10 to which voltage is applied into contact with the transfer material 7.
[0091]
In the apparatus shown in FIG. 3, at least the electrophotographic photosensitive member 1, the contact charging member 9 and the developing means 3 are stored in a container 20 to form one process cartridge, and this process cartridge is used as a guide means such as a rail of the apparatus main body. And detachable. The cleaning means 5 may or may not be disposed in the container 20.
[0092]
Further, in the apparatus shown in FIG. 4, at least the electrophotographic photosensitive member 1 and the contact charging member 9 are housed in a first container 21 to form a first process cartridge, and at least the developing means 3 is housed in a container 22 to form a second process. The first process cartridge and the second process cartridge are configured to be detachable. The cleaning means 5 may or may not be disposed in the container 21.
[0093]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these Examples. In the examples, “part” means part by mass.
[0094]
<Toner Production Examples and Comparative Production Examples>
Examples of toner production and comparative production examples will be described.
[0095]
{Toner Production Example 1}
Ion-exchanged water 600 g and 0.1 mol / liter-Na in a 2-liter 4-neck flask equipped with a high-speed stirring device TK type homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.)_ThreePO_Four500 g of an aqueous solution was added, the rotation speed was adjusted to 14000 rpm, and the mixture was heated to 65 ° C. Here, 1.0 mol / liter-CaCl₂Gradually add 70 parts of an aqueous solution to form a slightly water-insoluble dispersion stabilizer Ca_Three(PO_Four)₂An aqueous dispersion medium containing was prepared.
[0096]
On the other hand, as dispersoid,
78 parts of styrene
22 parts of n-butyl acrylate
0.2 parts of divinylbenzene
Carbon black (BET specific surface area = 50m²/ G) 5 parts
4 parts of unsaturated polyester
(Condensation polymer of epoxidized bisphenol A and fumaric acid, peak molecular weight = 7000)
Chlorine compound of di-tert-butylsalicylic acid 2 parts
Ester wax (mp = 62 ° C) 10 parts
[0097]
The above mixture was dispersed for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.), and then 5 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) was added to prepare a polymerizable monomer composition. .
[0098]
Next, the polymerizable monomer composition is put into the aqueous dispersion medium, and N.sub.₂While maintaining the rotation speed of the high-speed stirrer at 12000 rpm in an atmosphere, the mixture was stirred for 15 minutes to granulate the polymerizable monomer composition. Thereafter, the stirrer was changed to a propeller stirring blade and held at the same temperature for 10 hours while stirring at 50 rpm to complete the polymerization.
[0099]
After completion of the polymerization, the suspension was cooled, and then diluted hydrochloric acid was added to remove the dispersion stabilizer. Further, after washing with water several times, the toner particles are spheroidized and dried for 10 hours while stirring in hot air using a fluidized bed dryer (manufactured by Okawara Seisakusho) to obtain polymer particles (A). Obtained. The polymer particles (A) have a circle-equivalent number average diameter of 4.1 μm, an average circularity in a circularity frequency distribution of 0.990, and the number of toner particles having a circularity of less than 0.950 is 2.3% by number. In the molecular weight distribution by GPC, the peak molecular weight was 15000 and Mw / Mn was 18.
[0100]
100 parts of the polymer particles (A) and hydrophobic oil-treated silica fine powder (BET: 200 m²/ G) Toner (A) was prepared by dry-mixing 2 parts with a Hengel mixer.
[0101]
{Toner Production Examples 2-5 and Comparative Production Examples 1-2}
A toner was produced in the same manner as in Production Example 1 except that the rotation speed of the high-speed stirrer and the treatment time of the fluidized bed dryer were changed to the conditions shown in Table 1, and toners (B) to (B) of Production Examples 2 to 5 were prepared. E) and toners (a) and (b) of Comparative Production Examples 1 and 2 were obtained.
[0102]
{Toner Comparative Production Example 3}
100 parts of styrene-n-butyl acrylate-divinylbenzene resin
(Peak molecular weight = 15000, Mw / Mn = 2.4, Tg = 50 ° C.)
4 parts of unsaturated polyester used in Toner Production Example 1
5 parts of carbon black used in toner production example 1
Negative charge control agent (monoazo iron complex) 2 parts
10 parts of ester wax used in Toner Production Example 1
[0103]
The above mixture is melt-kneaded with a twin screw extruder, the cooled kneaded product is coarsely pulverized with a hammer mill, the coarsely pulverized product is finely pulverized with a jet mill, and the resulting finely pulverized product and commercially available calcium phosphate fine powder are mixed with Henschel. After mixing with a mixer, the obtained mixed powder was put into a container containing water, further dispersed in water using a homomixer, the water temperature was gradually raised, and heat treatment was performed at a temperature of 60 ° C. for 2 hours. Thereafter, dilute hydrochloric acid was added to the container to sufficiently dissolve the calcium phosphate on the surface of the finely pulverized particles. After separation by filtration, the product was washed and dried, then aggregated through a 400-mesh sieve, and classified to obtain a classified powder (c). Using the classified powder (c), a comparative toner (c) was prepared in the same manner as in Toner Production Example 1.
[0104]
Table 1 shows various properties of the polymer particles (A) to (E), the comparative polymer particles (a) and (b), and the classified powder (c) obtained above.
[0105]
[Table 1]

[0106]
{Toner Production Examples 6-8 and Comparative Production Examples 4, 5}
As dispersoid,
80 parts of ethylene
20 parts 2-ethylhexyl acrylate
Divinylbenzene 0.3 parts
Carbon black (BET specific surface area = 50m²/ G) 7 parts
Carbon black 1 part
(Spiron Black TRH, manufactured by Hodogaya Chemical Co., Ltd.)
10 parts of polypropylene (Biscol 550P, manufactured by Sanyo Chemical Co., Ltd.)
2,2'-azobis (2,4-dimethylvaleronitrile) 3 parts
The above mixture was thoroughly mixed with a sand mill to obtain a polymerizable composition.
[0107]
This polymerizable composition was added to water containing tricalcium phosphate and sodium dodecylbenzenesulfonate at the concentrations shown in Table 2 as a dispersion stabilizer, and the inner temperature was 65 ° C.₂In an atmosphere, the mixture was dispersed with a high-speed stirrer to obtain a suspension of each production example. Thereafter, this suspension was put into a three-necked flask equipped with a stirrer, and heated and polymerized by stirring at 70 ° C. for 10 hours. Then, tricalcium phosphate was removed with an aqueous hydrochloric acid solution, washed with water, The toner was obtained by drying. To 100 parts of this polymerized toner, 0.3 part of hydrophobic silica fine powder (trade name: Aerosil R-972, manufactured by Aerosil Co., Ltd.) is added and mixed, and the toners (F) to (H) of the present invention and comparative production are compared. Toners (d) and (e) of Examples 4 and 5 were obtained. Table 2 shows various properties of the toner.
[0108]
[Table 2]

[0109]
<Examples of production of electrophotographic photoreceptors and comparative production examples>
{Production example 1 of electrophotographic photosensitive member}
First, a coating solution for the conductive layer was prepared by the following procedure. 50 parts of conductive titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of phenol resin, 20 parts of methyl cellosolve, 5 parts of methanol and silicone oil (polydimethylsiloxane / polyoxyalkylene copolymer, An average molecular weight of 3000) 0.002 part was prepared by dispersing for 2 hours in a sand mill using φ1 mm glass beads. This coating solution was applied on an aluminum cylinder having a diameter of 30 mm by a dip coating method and dried at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 20 μm.
[0110]
Next, 5 parts of N-methoxymethylated nylon was dissolved in 95 parts of methanol to prepare an intermediate layer coating solution. This coating solution was applied onto the conductive layer by a dip coating method and dried at 100 ° C. for 20 minutes to form an intermediate layer having a thickness of 0.6 μm.
[0111]
Next, 5 parts of a bisazo pigment represented by the following formula, 2 parts of polyvinyl butyral resin, and 60 parts of cyclohexanone are dispersed for 24 hours in a sand mill using φ1 mm glass beads, and 60 parts of tetrahydrofuran is further added to coat the charge generation layer. A working liquid was used. This coating solution was applied onto the intermediate layer by a dip coating method and dried at 100 ° C. for 15 minutes to form a charge generation layer having a thickness of 0.2 μm.
[0112]
[Chemical 1]

[0113]
Next, 60 parts of a hole transporting compound represented by the following formula was dissolved in a mixed solvent of 50 parts of monochlorobenzene / 30 parts of dichloromethane to prepare a coating liquid for a charge transport layer.
[0114]
[Chemical 2]

[0115]
The coating solution is coated on the charge generation layer, irradiated with an electron beam under the conditions of an acceleration voltage of 150 KV / irradiation dose of 30 Mrad, and the resin is cured to form a charge transport layer having a thickness of 15 μm. An electrophotographic photoreceptor (1) was obtained. The universal hardness of the surface layer at this time is 268 N / mm²Met.
[0116]
{Production example 2 of electrophotographic photosensitive member}
A support, a conductive layer and an intermediate layer were formed in the same manner as in the electrophotographic photoreceptor production example 1.
[0117]
Next, 3 parts of oxytitanium phthalocyanine having strong peaks at 9.0, 14.2, 23.9, and 27.1 degrees with a Bragg angle 2θ ± 0.2 degrees in CuKα characteristic X-ray diffraction, polyvinyl Disperse 3 parts of butyral (trade name: Esletk BM2, manufactured by Sekisui Chemical Co., Ltd.) and 35 parts of cyclohexanone in a sand mill using φ1 mm glass beads for 2 hours, and then add 60 parts of ethyl acetate for the charge generation layer A coating solution was prepared. This coating solution was applied onto the intermediate layer by a dip coating method and dried at 50 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.
[0118]
Next, 15 parts of a hole transporting polymer compound represented by the following formula (number average molecular weight Mn = 20000)
[0119]
[Chemical 3]

And 25 parts of a C-type polycarbonate resin having a repeating unit represented by the following formula and having a number average molecular weight Mn = 80000
[0120]
[Formula 4]

Is formed in a mixed solvent of 100 parts of monochlorobenzene / 50 parts of dichloromethane to form a charge transport layer on the charge generation layer with a film thickness of 15 μm. (2) was obtained. At this time, the universal hardness of the surface layer is 250 N / mm²Met.
[0121]
{Production Example 3 of Electrophotographic Photoreceptor}
In the same manner as in the electrophotographic photosensitive member production example 2, a support, a conductive layer, an intermediate layer, and a charge generation layer were formed.
[0122]
Furthermore, 20 parts of a styryl compound represented by the following formula
[0123]
[Chemical formula 5]

And 10 parts of a polycarbonate resin having a repeating unit represented by the following formula
[0124]
[Chemical 6]

The charge transport layer was formed to a thickness of 12 μm on the charge generation layer using a charge transport layer coating solution prepared by dissolving in a mixed solvent of 50 parts of monochlorobenzene / 20 parts of dichloromethane.
[0125]
Next, 4.1 parts of an aqueous dispersion of colloidal silica (solid content: 40% by mass) was placed in a flask, and 26.5 parts of an isopropyl alcohol dispersion of colloidal silica (solid content: 30% by mass), methyltriethoxy, while stirring. 1.8 parts of silane, 2.4 parts of γ-glycidoxypropyltrimethoxysilane, 1.1 parts of n-perfluorooctylethyltriethoxysilane and 3.1 parts of acetic acid were added. After the addition, the mixed solution was heated to 65 to 70 ° C. and reacted for 2 hours. Thereafter, the mixture was diluted with 23.1 parts of isopropyl alcohol, 2.8 parts of dibutyltin di-2-ethylhexoate was added as a curing catalyst, and 0.16 part of a 10 mass% ethanol solution of polyether-modified dimethyl silicone was further added. And a protective layer composition is prepared. After the dip coating on the charge transport layer using the protective layer composition, the coating is heated and cured at 180 ° C. for 1 hour, and the film thickness is 1.0 μm. A layer was formed to obtain an electrophotographic photoreceptor (3).
[0126]
The universal hardness of the protective layer by this protective layer composition is 415 N / mm.²Met.
[0127]
{Production example 4 of electrophotographic photosensitive member}
A support, a conductive layer, an intermediate layer, a charge generation layer, and a charge transport layer were formed in the same manner as in Electrophotographic Photosensitive Member Production Example 2.
[0128]
Next, 5 parts of 4- [N, N-bis (3,4-dimethylphenyl) amino]-[2- (triethoxysilyl) ethyl] benzene was added to 30 parts of the protective layer composition solution used in Production Example 3. In addition, it was dissolved to obtain a protective layer composition solution of Production Example 4. This coating solution was dip coated on the charge transport layer, heated and cured at 180 ° C. for 1 hour to form a protective layer having a thickness of 1.5 μm, and an electrophotographic photoreceptor (4) was obtained. At this time, the universal hardness of the protective layer is 290 N / mm²Met.
[0129]
{Production Example 5 of Electrophotographic Photoreceptor}
A support, a conductive layer, an intermediate layer, a charge generation layer, and a charge transport layer were formed in the same manner as in Electrophotographic Photosensitive Member Production Example 3.
[0130]
Next, 50 parts of an acrylic monomer represented by the following formula,
[0131]
[Chemical 7]

50 parts of antimony-doped tin oxide fine particles (trade name: T-1, manufactured by Mitsubishi Materials), 5 parts of 2-methylthioxanthone as a photoinitiator and 300 parts of toluene are mixed and dispersed in a sand mill for 48 hours, for protective layer A coating solution was prepared. This coating solution is applied onto the charge transport layer by a spray coating method, dried, and then 8 mW / cm with a high-pressure mercury lamp.²The coating film was cured by irradiating with ultraviolet rays at a light intensity of 20 seconds to form a protective layer having a film thickness of 3 μm to obtain an electrophotographic photosensitive member (5). At this time, the universal hardness of the protective layer is 290 N / mm²Met.
[0132]
{Example 6 of production of electrophotographic photosensitive member}
A support, a conductive layer, an intermediate layer, and a charge generation layer were formed in the same manner as in Electrophotographic Photosensitive Member Production Example 3.
[0133]
Next, 15 parts of a compound represented by the following formula:
[0134]
[Chemical 8]

And 25 parts of a C-type polycarbonate resin having a repeating unit represented by the following formula and having a number average molecular weight Mn = 80000
[0135]
[Chemical 9]

A charge transport layer is formed to a thickness of 15 μm on the charge generation layer using a coating solution for charge transport layer prepared by dissolving 80 parts of monochlorobenzene in 50 parts of monochlorobenzene and electrophotographic photosensitive layer. Body (6) was obtained. At this time, the universal hardness of the surface layer is 235 N / mm²Met.
[0136]
{Comparative production example 1 of electrophotographic photosensitive member}
A support, a conductive layer, an intermediate layer, and a charge generation layer are formed in the same manner as in the electrophotographic photoreceptor production example 3, and the film thickness is 15 μm on the charge generation layer with the same composition as in the electrophotographic photoreceptor production example 3. Thus, an electrophotographic photosensitive member (I) of Comparative Production Example 1 was obtained. At this time, the universal hardness of the surface layer is 220 N / mm²Met.
[0137]
{Comparative production example 2 of electrophotographic photosensitive member}
A support, a conductive layer, an intermediate layer and a charge generation layer were formed in the same manner as in Comparative Production Example 1 of the electrophotographic photosensitive member, and a protective layer was formed on the charge generation layer as follows.
[0138]
First, 8.7 parts of an aqueous dispersion of colloidal silica (solid content: 40% by mass) was placed in a flask, and 20.5 parts of an isopropyl alcohol dispersion of colloidal silica (solid content: 30% by mass) with stirring, methyltriethoxysilane. 25.6 parts, 3,3,4,4,5,5,6,6,6-nonafluorohexyltrimethoxysilane 5.9 parts and acetic acid 3.2 parts were added. After the addition, the mixed solution was heated to 65 to 70 ° C. and reacted for 2 hours. Thereafter, it is diluted with 21.7 parts of isopropyl alcohol, 2.4 parts of benzyltrimethylammonium acetate is added as a curing catalyst, and 0.16 part of a 10% by weight ethanol solution of polyether-modified dimethyl silicone is further added. Composition II was made. This protective layer composition II was applied onto the charge transport layer by a dip coating method, dried and heat treated at 150 ° C. for 4 hours to form a protective layer having a thickness of 0.4 μm, and the electron of Comparative Production Example 2 A photographic photoreceptor (II) was obtained. At this time, the universal hardness of the protective layer is 685 N / mm.²Met.
[0139]
Example 1
An embodiment of the image forming apparatus of the present invention will be described. A commercially available digital copying machine GP-40 (manufactured by Canon Inc.) was modified and reset as the image forming apparatus of Example 1.
[0140]
The resolution of the laser exposure apparatus was increased to 1200 dpi, the setting pressure of the cleaning blade was 40 g / cm, and the electrophotographic photosensitive member shown in Production Example 1 of the electrophotographic photosensitive member was used.
[0141]
The developing device was modified as follows. That is, instead of an aluminum sleeve containing a magnet as a toner supply body, a medium resistance rubber roller (diameter 18 cm) made of silicone rubber in which carbon black is dispersed and the resistance is adjusted is used as a toner carrier (3-1 in FIG. 2). As a contact with the electrophotographic photosensitive member. The moving direction and rotational speed of the surface of the toner carrying member are the same at the contact portion with the electrophotographic photosensitive member, and are driven so as to be 150% with respect to the rotational speed of the electrophotographic photosensitive member. As a means for applying the toner on the toner carrier, an application roller (not shown) was brought into contact with the toner carrier and rotated in the opposite direction to the toner carrier to apply the toner. The toner (A) produced in Toner Production Example 1 was used as the toner.
[0142]
The process conditions of the copying machine of this embodiment are such that the dark portion potential and the bright portion potential of the electrophotographic photosensitive member are -700 V and -150 V, respectively, and the developing bias applied to the toner carrier is -450 V (only the DC component). Set to.
[0143]
When this copier was installed in an environment with a temperature and humidity of 15 ° C./10% RH, and images were evaluated by continuously copying 2000 sheets while replenishing toner, image density and dot reproducibility were also achieved in image formation at 1200 dpi. Both were very good, no cleaning failure occurred, and the image quality equivalent to the initial image was obtained even on the 2000th sheet. Further, the surface of the electrophotographic photosensitive member after 2000 images were printed had a smooth surface without any scratches or surface roughness. The evaluation results are shown in Table 3.
[0144]
    (Example 23)
  Toner (B) shown in the production example as a toneras well as(D) Was used in the same manner as in Example 1 except that In any of the examples, a high-quality image was obtained, and no defective cleaning occurred even in repeated image output. The results are shown in Table 3.
[0145]
(Comparative Examples 1-5)
Evaluation was performed in the same manner as in Example 1 except that the toners (a) to (e) shown in the comparative production examples were used as toners. In Comparative Examples 1 to 5, in the evaluation of the printout image, remarkable image defects were observed particularly in dot reproducibility, scattering, and voids. The results are shown in Table 3.
[0146]
[Table 3]

[0147]
    (Example4~6)
  The electrophotographic photosensitive member shown in the production example as an electrophotographic photosensitive member (3) ~ (5) Was used in the same manner as in Example 1 except that
[0148]
  Any implementationFor exampleIn this case, a high-quality image was obtained, and no cleaning failure occurred even in repeated image output. The results are shown in Table 4.
[0149]
(Comparative Examples 6 and 7)
Evaluation was conducted in the same manner as in Example 1 except that the electrophotographic photoreceptors (I) and (II) shown in the comparative production examples were used as the electrophotographic photoreceptor. In both Comparative Examples 6 and 7, a cleaning failure occurred in repeated image output. In Comparative Example 6, the cleaning failure was caused by many scratches on the surface of the electrophotographic photosensitive member, and in Comparative Example 7, it was caused by cracks generated in the protective layer of the electrophotographic photosensitive member during repeated image output. In Comparative Example 7, the cleaning blade was inverted during repeated image output, making it impossible to continue. The results are shown in Table 4.
[0150]
[Table 4]

[0151]
  (Example 7)
  BookImplementationAn example image forming apparatus will be described. BookImplementationIn the example, a commercially available LBP-EX (manufactured by Canon) was remodeled, re-set and used. In the resetting portion, first, the laser exposure was modified from 600 dpi to 1200 dpi, and the setting pressure of the cleaning blade was set to 50 g / cm.
[0152]
  Next, in the developing device, instead of an aluminum sleeve containing a magnet as a toner supply body, a medium resistance rubber roller (diameter 16 cm) made of silicone rubber in which resistance is adjusted by dispersing carbon black is used as a toner carrier. It contacted the photographic photoreceptor. The moving direction and the rotational speed of the surface of the toner carrier are the same at the contact portion with the electrophotographic photosensitive member, and are driven to be 140% with respect to the rotational speed of the electrophotographic photosensitive member. As a means for applying the toner on the toner carrier, an application roller (not shown) was brought into contact with the toner carrier and rotated in the opposite direction to the toner carrier to apply the toner. Further, a resin-coated stainless steel blade was attached to control the toner coat layer on the toner carrier. Toner is an example of toner production4Toner (made withD), And electrophotographic photosensitive member is a manufacturing example4Electrophotographic photosensitive member (4) Was used.
[0153]
  BookImplementationThe process conditions of the example LBP were set so that the dark part potential and the bright part potential of the electrophotographic photosensitive member were -650 V and -200 V, respectively, and the developing bias applied to the toner carrier was -480 V (only the DC component). .
[0154]
When the image forming apparatus was installed in an environment with a temperature and humidity of 10 ° C./8% RH, and 2000 images were continuously output while replenishing toner, image evaluation was performed. There was no defective cleaning, and the image quality equivalent to the initial image was obtained even on the 2000th sheet. Further, the surface of the electrophotographic photosensitive member after 2,000 images were printed had a smooth surface without any scratches or surface roughness. The evaluation results are shown in Table 5.
[0156]
  (Comparative Examples 8-11)
  Except for using toners and electrophotographic photosensitive members shown in Table 7,referenceExample3And evaluated in the same manner. In Comparative Example 8 using the toner (c) having a low average circularity, the voids are particularly frequent, and in Comparative Examples 9 and 11 using the toners (d) and (e) having a large circle equivalent number average diameter, dot reproducibility is obtained. The defect was conspicuous. Universal hardnessOutside the scope of the present inventionIn Comparative Examples 8 and 10 using the electrophotographic photosensitive member (I), in the continuous image output, the surface of the electrophotographic photosensitive member was scratched or roughened, and the defective cleaning occurred from this. Universal hardnessOutside the scope of the present inventionIn Comparative Examples 9 and 11 using the electrophotographic photosensitive member (II), the cleaning blade turned over and reversed during continuous image output, which caused a cleaning failure. The results are shown in Table 5.
[0157]
[Table 5]

[0158]
  Implementation of the present inventionExampleAnd the evaluation items described in the comparative examples and the evaluation criteria are described.
[0159]
[Printout image evaluation]
<1> Image density
Ordinary paper for ordinary copying machines (75 g / m²The image density when a predetermined number of printouts were completed was evaluated. For the image density, a “Macbeth reflection densitometer” (manufactured by Macbeth) was used to measure a relative density with respect to a printout image of a white background portion having a document density of 0.00.
A: 1.40 or more
B: 1.35 or more and less than 1.40
C: 1.00 or more and less than 1.35
D: Less than 1.00
[0160]
<2> Dot reproducibility
An image of an isolated dot pattern having a small diameter (50 μm) as shown in FIG. 5 which is easy to close due to the latent image electric field and difficult to reproduce was printed out, and the dot reproducibility was evaluated.
A: Less than 2 defects / 100
B: 3-5 defects / 100 defects
C: 6-10 defects / 100 defects
D: 11 or more defects / 100
[0161]
<3> Image fog
The fog density (%) was calculated from the difference between the whiteness of the white portion of the printout image measured by “Reflectometer” (manufactured by Tokyo Denshoku Co., Ltd.) and the whiteness of the transfer paper, and the image fogging was evaluated.
A: Less than 1.5%
B: 1.5% or more and less than 2.5%
C: 2.5% or more and less than 4.0%
D: 4.0% or more
[0162]
<4> Image scattering
The “electric” character pattern shown in FIG.²) And cardboard (128 g / m²) Was visually evaluated for the toner scattering {state in FIG. 6 (b)} to the periphery of the character when printed on.
A: Almost no occurrence.
B: Minor scattering is observed.
C: Slight scattering is observed.
D: Significant scattering is observed.
[0163]
<5> Image dropout
The “surprise” character pattern shown in FIG.²) Was visually evaluated for the hollowed out characters {state shown in FIG. 7B).
A: There is almost no void.
B: A slight void is observed.
C: Some voids are observed.
D: Significant void is seen.
[0164]
【The invention's effect】
In the present invention, toner cleaning means using a cleaning blade is used, using a toner having a small diameter, high circularity, and uniform circularity, and an electrophotographic photoreceptor having a universal hardness of the surface layer within a certain range. By adopting it, it is possible to provide an image forming apparatus and a process cartridge that can stably supply a high image quality and a high-definition image without causing defective cleaning even when repeatedly outputting images in any environment. became.
[Brief description of the drawings]
FIG. 1 is a schematic view of a cleaning device section of an image forming apparatus of the present invention.
FIG. 2 is a schematic view of an image photographic apparatus of the present invention.
FIG. 3 is a schematic view of an image forming apparatus having a process cartridge of the present invention.
FIG. 4 is a schematic view of an image forming apparatus having another process cartridge of the present invention.
FIG. 5 is an explanatory diagram of an isolated dot pattern for checking toner development characteristics.
FIG. 6 is a schematic diagram showing a state where character images are scattered.
FIG. 7 is a schematic diagram showing a hollow state in a character image.
[Explanation of symbols]
1 Electrophotographic photoreceptor
2 Charging means
3 Development means
3-1 Toner carrier
4 Transfer means
5 Cleaning means
5-1 Cleaning blade
5-2 Cleaning unit frame
5-3 Mold
5-4 Squee Sheet
5-5 Stirring member
5-6 Partition plate
6 Pre-exposure means
7 Transfer material
8 Fixing means
9 Contact charging member
10 Contact charging member for transfer
20 container 1
21 Container 2
22 Container 3

Claims (9)

In an image forming apparatus having at least an organic electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit having toner, a transfer unit, a fixing unit, and a cleaning unit,
In the toner-based circle equivalent diameter-circularity scattergram measured by the flow type particle image measuring apparatus, the toner equivalent circle average diameter is 2.3 to 4.1 μm, and the average A dry toner having a circularity of 0.979 to 0.994 and a circularity standard deviation of 0.025 to 0.030 (however, it contains at least a binder resin, a colorant and a wax, and a siloxane-modified polycarbonate resin Excluding dry toner present on the toner particle surface) ,
The cleaning means is a cleaning means using at least a rubber blade;
The organic electrophotographic photoreceptor has a support, a charge generation layer containing a charge generation material and a binder resin, and a charge transport layer containing a charge transport material and a binder resin in this order. An image forming apparatus, wherein the surface layer of the organic electrophotographic photoreceptor includes a cured resin and has a universal hardness of 268 N / mm ² or more and 415 N / mm ² or less.   The image forming apparatus according to claim 1, wherein the cleaning blade is disposed in contact with the rotation direction of the electrophotographic photosensitive member in a counter direction.   The image forming apparatus according to claim 1, wherein the surface layer of the electrophotographic photosensitive member contains a polymer charge transport material. The image forming apparatus according to any one of claims 1 to 3 , wherein the toner has 13 or less number of toner particles having a circularity of less than 0.950. The rubber blade, an image forming apparatus according to any one of claims 1 to 4 contact pressure to the surface of the electrophotographic photosensitive member is not more than 40 g / cm or more 50 g / cm.   The image forming apparatus according to claim 1, wherein the cured product of the resin is a polymer of a curable acrylic monomer. In a process cartridge in which a developing unit having toner and a cleaning unit are configured together with an organic electrophotographic photosensitive member,
In the toner-based circle equivalent diameter-circularity scattergram measured by the flow type particle image measuring apparatus, the toner equivalent circle average diameter is 2.3 to 4.1 μm, and the average A dry toner having a circularity of 0.979 to 0.994 and a circularity standard deviation of 0.025 to 0.030 (however, it contains at least a binder resin, a colorant and a wax, and a siloxane-modified polycarbonate resin Excluding dry toner present on the toner particle surface) ,
The cleaning means is a cleaning means using at least a rubber blade;
The organic electrophotographic photoreceptor has a support, a charge generation layer containing a charge generation material and a binder resin, and a charge transport layer containing a charge transport material and a binder resin in this order. A process cartridge, wherein the surface layer of the organic electrophotographic photosensitive member contains a cured product of a resin and has a universal hardness of 268 N / mm ² or more and 415 N / mm ² or less.   The process cartridge according to claim 7, wherein the cleaning blade is disposed in contact with the rotation direction of the electrophotographic photosensitive member in a counter direction.   9. The process cartridge according to claim 7, wherein the surface layer of the electrophotographic photosensitive member contains a polymer charge transport material.

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