JP2004101627A - Electrophotographic apparatus, image forming method and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic apparatus free of occurrence of image defects due to adhering and filming of a toner on a drum even after continuous printing on many sheets and improved in high durability, low temperature fixation, storage stability and cost merit not attained so far. <P>SOLUTION: In the electrophotographic apparatus, a suspension-polymerized toner as a kind of capsular toner in which the glass transition temperature (Tg) of a shell part is higher than that of a core part is combined with an acrylic OCL comprising a set polymer of a photosetting compound containing two or more acrylic functional groups and conductive particles. <P>COPYRIGHT: (C)2004,JPO

Description

【００４３】
式中、Ａは水素原子またはメチル基であり、かつ、Ａの全部における水素原子の割合は０．１〜５０％の範囲、ｎは０以上の整数である。
【００４４】
このシロキサン化合物を添加後分散した塗工液、または、これを表面処理した導電性微粒子を溶剤に溶かした結着剤樹脂中に分散することによって、分散粒子の二次粒子の形成もなく、経時的にも安定した分散性の良い塗工液が得られ、更にこの塗工液より形成した保護層は透明性が高く、耐環境性に特に優れた膜が得られた。
【００４５】
一般式（１）で示されるシロキサン化合物の分子量は特に制限されるものではないが、表面処理をする場合は、その容易さからは粘度が高すぎない方がよく、質量平均分子量で数百〜数万程度が適当である。
【００４６】
表面処理の方法としては湿式、乾式の二通りがある。湿式では導電性粒子を一般式（１）で示されるシロキサン化合物とを溶剤中で分散し、該シロキサン化合物を微粒子表面に付着させる。分散の手段としてはボールミル、サンドミル等一般の分散手段を使用することができる。次に、この分散溶液を導電性微粒子表面に固着させる。この熱処理においてはシロキサン中のＳｉ−Ｈ結合が熱処理過程において空気中の酸素によって水素原子の酸化が起こり、新たなシロキサン結合ができる。その結果、シロキサンが三次元構造にまで発達し、導電性微粒子表面がこの網状構造で包まれる。このように表面処理は、該シロキサン化合物を導電性微粒子表面に固着させることによって完了するが、必要に応じて処理後の微粒子に粉砕処理を施しても良い。乾式処理においては、溶剤を用いずに該シロキサン化合物と導電性微粒子とを混合し混練を行うことによってシロキサン化合物を微粒子表面に付着させる。その後は湿式処理と同様に熱処理、粉砕処理を施して表面処理を完了する。
【００４７】
本発明における導電性微粒子に対するシロキサン化合物の割合は、微粒子の粒径やシロキサン中のメチル基と水素原子の比率等に依存するが、１〜５０ｗｔ％、好ましくは３〜４０ｗｔ％である。
【００４８】
【表１】

【００４９】
【表２】

【００５０】
【表３】

【００５１】
また、本発明においては、オーバーコート層が滑材粒子を含有することが好ましい。その理由は，帯電時に感光体と帯電部材の摩擦が低減されるために帯電ニップが拡大し、帯電特性が向上するためである。特に滑材粒子として臨界表面張力の低いフッ素系樹脂、シリコーン系樹脂またはポリオレフィン系樹脂を用いることが好ましい。更に好ましくはフッ素系樹脂、中でもポリテトラフルオロエチレン（ＰＴＦＥ）が好ましい。この場合、滑材粒子の添加量は、結着樹脂に対して２〜５０重量％、好ましくは５〜４０重量％である。２重量％未満では、滑材粒子の量が十分ではないために、帯電特性の向上が十分ではなく、また５０重量％を超えると、画像の分解能、感光体の感度が大きく低下してしまうからである。
【００５２】
かかるフッ素系樹脂粒子はポリテトラフルオロエチレン、ポリクロロトリフルオロエチレン、ポリフッ化ビニリデン、ポリジクロロジフルオロエチレン、テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体、テトラフルオロエチレン−エチレン共重合体及びテトラフルオロエチレン−ヘキサフルオロプロピレン−パーフルオロアルキルビニルエーテル共重合体から選ばれた１種または２種以上から構成されているものである。市販のフッ素系樹脂粒子をそのまま用いることが可能である。０．３万〜５００万の数平均分子量のものが使用可能であり、０．０１〜１０μｍ、好ましくは０．０５〜２．０μｍの粒径のものが使用可能である。
【００５３】
本発明におけるオーバーコート層の膜厚は０．１〜１０μ上ｍであることが好ましく、特には１〜７μｍであることが好ましい。膜厚が０．１μｍ未満であると微小な傷に対する耐性がなくなり、結果として画像欠陥を生じ、１０μｍを超えると注入電荷の拡散により画像が乱れ易くなってしまう。
【００５４】
本発明における露光手段としては、レーザーやＬＥＤなど公知の手段を用いることができる。
【００５５】
帯電手段としては、電子写真感光体の表面層に接触し、該帯電部材に印可された電圧により感光体表面を帯電するものである。構成としては、帯電ローラー、帯電ブレード、帯電磁気ブラシ、及び帯電繊維ブラシなどがあげられる。
【００５６】
帯電ローラー及び帯電ブレードとしては、導電性を有するローラー状あるいはブレード状の弾性層上に導電性微粒子を分散したコーティング層を抵抗層として配置した構成をとってもよい。これらの帯電部材の抵抗値としては、１×１０^４Ω〜１×１０^７　Ωの範囲であることが望ましい。抵抗値が１×１０^４　Ωより低い場合にはピンホールリークを防止できないことがあり、１×１０^７　Ωより高い場合には帯電に必要な電流を流すことが出来ないことがある。
【００５７】
弾性層に用いられる樹脂材料としては、例えばＥＰＤＭ、ＥＰＴ、ＥＰＭ、ＮＢＲ、ＢＲ、及びＣＲなどの合成ゴム、天然ゴムなどの熱硬化性エラストマー、また塩化ビニル、酢酸ビニルポリエステル、ＰＶＡなどの熱可塑性エラストマーなどが用いられる。
【００５８】
また弾性層に導電性を付与するために添加される導電性微粒子としては、カーボンブラック、酸化亜鉛、酸化チタン及び金属粉などの導電性粒子が用いられる。
【００５９】
弾性層としては、ＪＩＳ　Ｋ、６３０１のＡ高度計により規定される硬度において、２０〜８０°の硬度であることが望ましい。
【００６０】
また帯電部材表面に配置される抵抗層に用いられる樹脂材料としては、ポリアミド、ポリイミド、フッ素樹脂、シリコン樹脂、ＰＶＡ及びポリエステルなどの常温において柔軟性を有する材料が用いられる。
【００６１】
さらに本発明の感光体は、接触された帯電部材から直接電荷の注入を行う帯電方式にも好適である。このような帯電方式に用いる帯電部材としては、タイデンローラー、帯電ブレード、帯電磁気ブラシ、及び帯電繊維ブラシなどがあげられる。これらの中では耐久性の点で帯電磁気ブラシ及び帯電ローラーが好ましく、さらには均一帯電性の点で帯電磁気ブラシが好ましい。
【００６２】
帯電磁気ブラシ方式は、磁気力によりフェライトなどの磁性粉体の穂を形成し、この穂だ値した磁性粉体を高密度に集めたブラシ状にし、電圧を印可することで帯電部材の役割を担わせたものである。この穂はかなり高密度化させることができ、より細密化された均一帯電を達成することが出来る。
【００６３】
構成としては非磁性の導電スリーブ、これに内包されるマグネットロール、スリーブ状の磁性導電性粒子からなり、マグネットロールは固定、スリーブ表面が感光体と周速差をもって移動するように回転される。
【００６４】
磁性導電性粒子は、
・樹脂とマグネタイトなどの磁性粉体を混練して粒子に成型したもの、もしくはこれに抵抗値調整のための導電カーボンなどを混ぜたもの
・焼結したマグネタイト、フェライト、もしくはこれらを還元処理して抵抗値を調整したもの
・またはこれらの磁性粒子をメッキ処理して抵抗値を適当な値にしたものなどが使用可能である。
【００６５】
現像手段としては、特に選ばないが、現像手段が実質的なクリーニング手段でもあるシステム、すなわち、転写位置と帯電位置の聞及び帯電位置と現像位置の間に転写後の電子写真感光体上に残留したトナーを回収し、貯蔵するクリーニング手段を有さない、所謂クリーナーレスシステムの場合、反転現像が好ましく、また、現像剤と感光体が接触するような構成が好ましい。例えば、接触二成分現像法、接触一成分法などが好適な現像方法として挙げられる。現像剤と転写残りトナーが感光体上にて接触している場合、静電気的力に、摺擦力が加わり、効果的に転写残りのトナーを現像手段にて回収できる傾向にあるからである。現像に印加されるバイアスについては、その直流成分は、黒字部（反転現像の場合、露光部分）と白地部の電位の間にすることが好ましい。
【００６６】
転写手段としては、コロナ、ローラー及びベルトなど公知の方法が用いられる。
【００６７】
本発明においては、電子写真感光体と帯電部材、必要に応じて現像手段を一体に支持しカートリッジ化し、電子写真装置本体に着脱自在のプロセスカートリッジにすることができる。
【００６８】
本発明においては、現像手段を電子写真感光体と帯電部材を有するカートリッジとは別体のカートリッジとすることができる。
【００６９】
【発明の実施の形態】
以下実施例により本発明を説明する。
【００７０】
（実施例１）
（感光体の作成方法）
アルミニウムシリンダー（Φ３０ｍｍ×３５８ｍｍ）上に、以下の材料により構成される塗料を浸せき法で塗布し、１４０℃３０分熱硬化して１５μｍの導電層を形成した。
導電性顔料：酸化スズ・酸化アンチモンコート処理酸化チタン　１０部
抵抗調整用顔料：酸化チタン　１０部
バインダー樹脂：フェノール樹脂（大日本インキ化学工業（株）製、プライオーフェンＪ３２５）　１０部
レベリング剤：シリコーンオイル（信越化学（株）製、ＳＨ２８ＰＡ）　０．００１部
溶剤：メタノール、メトキシプロパノール１／１　２０部
次にこの上に共重合ポリアミド樹脂（アミランＣＭ−８０００、東レ（株）製）１０部、メトキシメチル化６ナイロン樹脂（トレジンＥＦ−３０Ｔ、帝国化学（株）製）３０部を、メタノール４００部、ｎブタノール２００部の混合溶剤に溶解した溶液を浸せき法により塗布し、９０℃１０分熱風乾燥させ、膜厚０．７μｍの中間層を形成した。
【００７１】
次にＣｕＫαに対するＸ線回折スペクトルでのブラッグ角（２θ±０．２）が、９．０°、１４．２°、２３．９°、２７．１°に強いピークを有するチタニルオキシフタロシアニン３部とポリビニルブチラール（商品名：エスレックＢＭ２、積水化学製）２部およびシクロヘキサノン１００部をΦ１ｍｍガラスビーズを用いたサンドミル装置で４時間分散した後、酢酸エチル９０部を加えて電荷発生層用分散液を調製した。この塗料を前記中間層上に浸せき法で塗布し８０℃１５分熱風乾燥させ、０．１μｍの電荷発生層を形成した。
【００７２】
次に下記構造式のアミン化合物７部
【外２】

【００７３】
及びビスフェノールＺ型ポリカーボネート（ユーピロンＺ−４００，三菱ガス化学（株）製）１０部をジクロロメタン３０部、モノクロロベンゼン４０部の混合溶媒中に溶解し、この塗料を前記の電荷発生層上に浸せき法で塗布し１２０度１時間乾燥し１７μｍの電荷輸送層を形成した。
【００７４】
次に、オーバーコート層用の調合液を下記の手順により作成した。
【００７５】
メチルハイドロジェンシリコンオイル（商品名ＫＦ９９、信越シリコーン（株）製）表面処理した、平均粒径０．０２μｍのアンチモンドープ酸化スズ微粒子（商品名Ｔ−１，三菱マテリアル（株）製）３０部と、フッ素変性シランカップリング剤（商品名ＬＳ１０９０、信越シリコーン（株）製）で表面処理した、平均粒径０．０２μｍのアンチモンドープ酸化スズ微粒子（同上）２０部を、構造式（２）のアクリルモノマー（商品名ＴＭＰ３Ａ−３、大阪有機化学（株）製）１８部と、
【外３】

【００７６】
エタノール８０部とともにサンドミルで７２時間分散を行った。
【００７７】
なお、表面処理量を、熱重量測定装置ＴＧ／ＤＴＡ２２０８（セイコー電子工業（株）製）で窒素雰囲気下、室温から５００℃まで昇温した時の重量減少を測定することにより求めた。その結果、メチルハイドロジェンシリコンオイルは１１．２％、フッ素変性シランカップリング剤は７．１％であった。
【００７８】
この液に４ふっかエチレン樹脂粒子（商品名ルブロンＬ−２，ダイキン工業（株）製）１７部を混合して酸ふぉみる装置にてさらに２時間分散し、さらに光重合開始剤として、２，４−ジエチルチオキサントン２．７部、開始剤として４，４′−ビス（ジエチルアミノ）ベンゾフェノン０．９部を加えて溶解し、表面層様の調合液を作成した。
【００７９】
この塗料を前記電荷輸送層上に浸せき塗布し、メタルハライドランプにて２４０Ｗ／ｃｍ^２の光強度で３０秒間紫外線照射して光硬化を行い、この後１２０℃、２時間熱風乾燥して、膜厚５μｍの表面層を作成した。
【００８０】
（トナーの作成方法）
スチレン６０部、２−エチルへキシルアクリレート４０部、ジビニルベンゼン１．０部（以上３成分のＴｇの設計値：２０．９℃）、カーボンブラック〔三菱化学（株）製、＃４４〕７．５部、低分子量ポリエチレン〔三井石油化学工業（株）製、三井ハイワックス１１２０Ｈ〕２部、帯電制御剤〔保土谷化学（株）製、アイゼンスピロンブラックＴＲＨ〕１部とポリエステル樹脂〔花王（株）製、ＫＴＰ２１５０、Ｔｇ：８０℃〕１０部をアトライターで５時間分敬した後、更に２，２′−アゾビスイソブチロニトリル４部を加えたものを、スーパタイト１０〔ヒドロキシアパタイトの１０重量％水スラリー、日本化学工業（株）製〕１００部、ドデシルベンゼンスルホン酸ナトリウム〔東京化成工業（株）製〕０．１部、水４００部を混合したものに加え、混合攪拌した。次にこの混合液をキャビテーション利用の連続式分散機マイルダー〔（株）荏原製作所製〕にフィード量２５１／ｍｉｎ、回転数８０００ｒｐｍの条件で２回通過させ、懸濁・分散せしめた。この懸濁液を脱水管、コンデンサー、攪拌装置を装着したセパラブルフラスコ中にて１００ｒｐｍの攪拌速度で窒素雰囲気下、８０℃で６時間重合反応を行わせた。重合反応後、濾過、塩酸洗浄、水洗浄を行い、４０℃にて一晩、減圧乾燥させてトナーを得た。得られたトナーの粒径及び粒径分布をコールターカウンター〔日科機（株）製、ＴＡ−ＩＩ型、アパーチャー径１００μｍ〕で測定したところ、重量平均粒径が１０．５μｍ、粒径の個数分布の標準偏差は２．５μｍであった。得られたトナーを透過型電子顕微鏡にて観察したところ、樹脂様物質が重合性単量体重合物の周囲に形成された、きれいなコア・シェル構造が見られた。
【００８１】
次に評価について説明する。
【００８２】
装置はキヤノン製カラーＬＢＰ「ＬＢＰ２１６０」（プロセススピード１１７．２ｍｍ／ｓｅｃ）を用いた。感光体へ電荷を印加するため帯電ローラーに、ＤＣバイアス−５５０Ｖを印加し、さらにＶｐｐ６００Ｖ、１０００ＨｚのＡＣバイアスを重畳することにより、標準感光体サンプル表面の非照射時帯電電位Ｖｄは−５５０Ｖ、レーザー光照射時の電位Ｖ１は−１５０Ｖとなった。
【００８３】
このような電子写真装置に上記感光体とトナーを装填／充填し、常温常湿環境（２３℃、５０％ＲＨ）で通紙、印字を繰り返す１万枚の耐久テストを行った。その時の耐久前後の感光体表面電位、削れ量、画像（トナー付着、フィルミング等）を表４に示す。実施例１においてドラム上へのトナー付着、フィルミングは見られず、耐久前後において良好な画像が得られた。
【００８４】
この評価のあと、高温高湿環境（３０℃、８０％ＲＨ）、及び常温低湿環境（２３℃、５％ＲＨ）に移して画像をとった。その画像結果を同じく表４に示す。
【００８５】
（実施例２）
感光体、トナーは実施例１と同じものを用い、評価方法を以下のように変えて評価を行った。
【００８６】
装置はキヤノン製カラーＬＢＰ「ＬＢＰ２１６０」（プロセススピード１１７．２ｍｍ／ｓｅｃ）を改造して用いた。改造方法は、まず帯電器部分を前述のような磁気ブラシ注入帯電器に替えた。帯電部材の磁気粒子としては、ポリスチレン樹脂にマグネタイトを１００部入れて混練、粉砕したもので、粒子径３０μｍ、抵抗値は１×１０^６　Ωであった。磁気ブラシの抵抗値は、上記の構成の磁気ブラシに対してアルミニウムドラムを当接させ、１００ＶのＤＣ電圧を印可したときの抵抗値で定義してある。
【００８７】
このような磁気粒子をマグネットを内包したスリーブ上に厚さ１ｍｍでコートして、感光体との間に幅約２ｍｍの帯電ニップを形成する。スリーブは感光体表面の周速に対して１倍の早さで逆方向に摺接するように回転されており、感光体の磁気ブラシが均一に接触するようになっている。
【００８８】
この磁気ブラシにＤＣバイアス−５５０Ｖを印加し、さらにＶｐｐ６００Ｖ、１０００ＨｚのＡＣバイアスを重畳することにより感光体に電荷注入され、−５５０Ｖの表面電位を得る。
【００８９】
このような電子写真装置に実施例１の感光体とトナーを装填／充填し、常温常湿環境（２３℃、５０％ＲＨ）で通紙、印字を繰り返す１万枚の耐久テストを行った。その時の耐久前後の感光体表面電位、削れ量、画像を表４に示す。このときドラム上へのトナー付着、フィルミングは見られなかった。
【００９０】
この評価のあと、高温高湿環境（３０℃、８０％ＲＨ）、及び常温低湿環境（２３℃、５％ＲＨ）に移して画像をとった。その画像結果を同じく表４に示す。
【００９１】
（実施例３）
実施例１の感光体の表面層において、アクリルモノマーとして以下の構造のものをもちいた以外はすべて実施例１と同じ構成にて同じ評価を行った。
【００９２】
その結果を表４に示す。
【外４】

【００９３】
（実施例４）
感光体、トナーは実施例３と同じものを用い、評価方法を実施例２のように変えて評価を行った以外は実施例１と同じく評価を行った。
【００９４】
その結果を表４に示す。
【００９５】
（実施例５）
実施例１の感光体の表面層において、アクリルモノマーとして以下の構造式（３）と構造式（４）を１／１の比率で混合したものをもちいた以外はすべて実施例１と同じ構成にて同じ評価を行った。
【外５】

【００９６】
その結果を表４に示す。
【００９７】
（実施例６）
感光体、トナーは実施例５と同じものを用い、評価方法を実施例２のように変えて評価を行った以外は実施例１と同じく評価を行った。
【００９８】
その結果を表４に示す。
【００９９】
（比較例１）
感光体にオーバーコート層を設けず、実施例１で作成した電荷輸送層までを塗工した感光体をそのまま用い、評価方法は実施例２のように行った以外は、実施例１と同じく評価を行った。
【０１００】
その結果を表４に示す。
【０１０１】
その結果、耐久１００枚目で感光体表面へのトナー付着、耐久８００枚目でフィルミングが発生し、これ以上耐久を続けられなかった。
【０１０２】
また、高温高湿下では画像流れが発生し、常温低湿下では白抜け画像となってしまった。
【０１０３】
（比較例２）
実施例１で作成したドラムにおいて、オーバーコート層を設ける際に、メチルハイドロジェンシリコンオイル（商品名ＫＦ９９、信越シリコーン（株）製）表面処理した、平均粒径０．０２μｍのアンチモンドープ酸化スズ微粒子（商品名Ｔ−１，三菱マテリアル（株）製）３０部と、フッ素変性シランカップリング剤（商品名ＬＳ１０９０、信越シリコーン（株）製）で表面処理した、平均粒径０．０２μｍのアンチモンドープ酸化スズ微粒子（同上）２０部を添加しなかった以外は、実施例１と同様にオーバーコート層までを塗工した。評価方法は実施例２のように行った以外は、実施例１と同じく評価を行った。
【０１０４】
その結果を表４に示す。
【０１０５】
その結果、初期において帯電不良が起こり、耐久が進むにつれてさらに帯電不良は悪化した。
【０１０６】
（実施例７）
感光体は実施例１のものを用い、トナーを以下の方法で作成したものをもちいた以外はすべて実施例１と同じ構成にて同じ評価を行った。
【０１０７】
トナー製造方法実施例１において、ポリエステル樹脂〔花王（株）製、ＫＴＰ２１５０、Ｔｇ：８０℃〕１０部を、エチルセルロース（商品名　ハーキュレスＮ−４、Ｔｇ：１４０℃）に変え、カーボンブラック等をアトライターにて５時間分散したあとに溶解した以外は同様にしてトナーを得た。得られたトナーの重量平均粒径は１１．０μｍ、粒径の個数分布の標準偏差は２．６μｍであった。
【０１０８】
評価結果を表４に示す。
【０１０９】
（実施例８）
感光体、トナーは実施例７と同じものを用い、評価方法を実施例２のように変えて評価を行った以外は実施例１と同じく評価を行った。
【０１１０】
その結果を表４に示す。
【０１１１】
（実施例９）
感光体は実施例１のものを用い、トナーを以下の方法で作成したものをもちいた以外はすべて実施例１と同じ構成にて同じ評価を行った。
【０１１２】
トナー作成方法は実施例１においてアトライターで５時間分散後に、エチルセルロース（商品名ハーキュレスＮ−４）５部とイソブチルアルコール１００部を加え、その他は実施例１と同様にして重合を行った。次いで９０℃に昇温することでイソブチルアルコールを留出させ、エチルセルロースの表面偏在化を促進させた。更に、減圧することでイソブチルアルコールを完全に除去した後、濾過、塩酸洗浄、水洗浄を行い、４０℃で一晩、減圧乾燥してトナーを得た。得られたトナーの重量平均粒径は１１．５μｍ、粒径の個数分布の標準偏差は２．８μｍであった。このトナーを透過型電子顕微鏡にて観察したところ、きれいなコア・シェル構造が見られた。
【０１１３】
評価結果を表４に示す。
【０１１４】
（実施例１０）
感光体、トナーは実施例９と同じものを用い、評価方法を実施例２のように変えて評価を行った以外は実施例１と同じく評価を行った。
【０１１５】
その結果を表４に示す。
【０１１６】
（比較例３）
感光体は実施例１のものを用い、トナーを以下の方法で作成した粉砕トナーをもちいた以外はすべて実施例１と同じ構成にて同じ評価を行った。
【０１１７】
その結果を表４に示す。
【０１１８】
（比較例４）
感光体、トナーは比較例３と同じものを用い、評価方法を実施例２のように変えて評価を行った以外は実施例１と同じく評価を行った。
【０１１９】
その結果を表４に示す。
【０１２０】
表４を見て明らかなように、特定のオーバーコート層を有する感光体と重合トナーの組み合わせのときには初期の表面電位特性／画像は良好であり、１万枚の耐久を行っても、ドラム上へのトナー付着、フィルミングなどといった欠陥が起こらず、ドラム表面削れも良好であった。これは帯電方式がローラーでの直接帯電によるもの／導電微粒子を用いた注入帯電によるものどちらでも有効であった。
【０１２１】
それに対して、オーバーコート層を有さないドラムと重合トナーの組み合わせでは、耐久初期段階でドラム上へのトナー付着、フィルミングなどといった欠陥が起こり、ドラム表面削れ／傷はＮＧとなった。さらに高温高湿下においては画像流れが発生し、常温低湿では画像の白抜けが発生した。又、オーバーコート層中に導電性微粒子を添加しない系では、帯電不良となり、印字がきちんと行われなかった。
【０１２２】
さらにオーバーコート層を有するドラムと、重合ではなく粉砕法によって得られた粉砕トナーの組み合わせでは定着不良となり、印字がきちんと行われなかった。
【０１２３】
つまり、特定のオーバーコート層と重合トナーの組み合わせた時のみ、良好な耐久特性が得られ、本発明の有効性を証明した。
【０１２４】
【表４】

【０１２５】
【発明の効果】
本発明は、多数枚の連続プリントを行ってもドラム上へのトナー付着やフィルミング等による画像欠陥が生じず、従来実現されていなかった高耐久性／低温定着／保存安定性／コストメリットの改善された電子写真装置を提供する。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic apparatus for developing, transferring, and fixing an electric latent image, an image forming method, and a process cartridge.
[0002]
[Prior art]
In the electrophotographic process, usually, the photosensitive member surface is uniformly charged, a latent image is formed by exposure, a developed image is formed with toner, the image is transferred to a transfer material mainly including paper, and the remaining toner, paper powder, etc. It consists of removal (cleaning) from the surface.
[0003]
Conventionally, in order to obtain a toner, a thermoplastic resin is melted, and a dye, a coloring agent such as a pigment, a charge controlling agent, an anti-offset agent, a fixing accelerator, a magnetic material, and the like are added and kneaded sufficiently, if necessary. After being cooled and solidified, a method of performing coarse pulverization, fine pulverization, and classification to obtain a desired particle size has been carried out. However, this method has disadvantages such as cost / decrease in yield due to reduction of toner particle size / deterioration of image quality due to poor fluidity / fog. As a method for solving these problems at once, a number of methods for producing a toner having excellent low-temperature fixability by a suspension polymerization method and a method for producing a microencapsulated toner have been recently proposed. For example, Japanese Patent Application Laid-Open No. 61-118758 discloses a method in which a suspension polymerization method is applied, and a toner obtained by suspension polymerization is used as a seed, and Tg (glass transition temperature) is higher than that of the seed. A method for achieving both storage stability and low-temperature fixability by absorbing the above monomer, and JP-A-62-75543 proposes a microencapsulated toner. However, in such a method, a problem occurs in terms of satisfactory characteristics / cost, and at present, a practical method has not yet been developed. Furthermore, various methods have recently been proposed for obtaining capsule toner by a dry method using a mechanochemical method. As an example, JP-A-3-77960 can be cited, but it is extremely difficult to uniformly encapsulate all the toners by such a method, the yield is poor, and the cost is low, including a classification step. But it is not realistic.
[0004]
Therefore, a toner to which the suspension polymerization method is applied is disclosed in JP-A-05-150549. This suspension polymerization toner is a kind of capsule toner, characterized by having a higher glass transition temperature (Tg) of a shell portion than a core portion, and has excellent low-temperature fixability and good storage stability. Realized toner.
[0005]
However, most of the constituent materials of generally used toner are binder resins, and materials that are advantageous for electrophotographic processes other than development are not always used. Even with this toner, problems such as adhesion of the toner to the photoreceptor and generation of untransferred toner due to the low Tg of the core portion occur.
[0006]
On the other hand, electrophotographic photoreceptors have traditionally used inorganic conductive materials such as selenium, zinc oxide, and cadmium sulfide, but recently used organic conductive materials that have advantages such as freedom of design and safety. Photoconductors are being actively developed. Electrophotographic photoreceptors using these organic photoconductive compounds are used as function-separated type photoreceptors in which a charge transport layer and a charge generation layer are laminated in order to satisfy both electrical and mechanical properties. Often. On the other hand, it is needless to say that the electrophotographic photoreceptor is required to have sensitivity, electrical characteristics, and optical characteristics according to the applied electrophotographic process.
[0007]
In particular, in the case of an electrophotographic photoreceptor that is used repeatedly, the surface of the electrophotographic photoreceptor is directly subjected to electrical or mechanical external force such as corona or direct charging, image exposure, toner development, transfer process, surface cleaning, etc. Also, durability for them is required.
[0008]
Specifically, the surface is worn or scratched due to electrical deterioration due to ozone and nitrogen oxide during charging, electrical deterioration due to discharging during charging, and rubbing of paper powder, toner, and cleaning member. There is a demand for durability against mechanical deterioration.
[0009]
Regarding mechanical deterioration, many organic photoconductors are particularly inferior in hardness to inorganic photoconductors, and improvement in durability against mechanical deterioration is particularly desired.
[0010]
Various attempts have been made to satisfy the durability characteristics required for the photoreceptor as described above.
[0011]
For example, attempts have been made to provide a protective layer mainly composed of a resin on a photosensitive layer. For example, JP-A-56-42863 and JP-A-53-10374 disclose that a protective layer containing a curable resin as a main component is used to improve hardness and wear resistance. I have.
[0012]
To obtain a better image, the protective layer of the photoreceptor is required to have not only properties such as high hardness and excellent abrasion resistance, but also an appropriate resistance of the protective layer itself. If the resistance of the protective layer is too high, by repeating the electrophotographic process such as charging / exposure, charges are accumulated in the protective layer, that is, the so-called residual potential increases, and the potential becomes unstable when the photoconductor is repeatedly used. Therefore, the image quality becomes unstable. On the other hand, if the resistance is too low, the electrostatic latent image will flow in the plane direction in the protective layer, causing problems such as blurring and blurring of the image. In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 57-30843 discloses that the resistance of a protective layer is controlled by adding a metal oxide as conductive fine particles. However, a protective layer having sufficient durability and surface properties while maintaining the above-mentioned appropriate resistance has not yet been obtained.
[0013]
On the other hand, as a charging process in an electrophotographic apparatus, corona charging, which is generated by applying a high voltage (5 to 8 KV DC) to a metal wire, has been used, but in recent years, Japanese Patent Application Laid-Open Nos. As proposed in JP-A-104351, JP-A-58-40566, JP-A-58-139156, JP-A-58-150975, etc., a charging member arranged in contact with the surface of a photoreceptor is used. A method of charging the surface of a photoreceptor by applying a voltage has been studied and has come into practical use.
[0014]
Specifically, the surface of the photoconductor is charged to a predetermined potential by contacting the surface of the photoconductor with a charging member such as a conductive elastic roller to which a DC voltage of about 1 to 2 KV is externally applied. Further, there has been proposed a method of superimposing an AC voltage on a DC voltage in order to improve charging uniformity.
[0015]
These charging methods have advantages such as simplification of a charging device and downsizing of a high-voltage power supply.On the other hand, deterioration of the photoreceptor surface and associated abrasion, scratches, toner adhesion and filming due to toner and its constituent components, and the like are provided. And it is more likely to occur.
[0016]
On the other hand, Japanese Patent Application Laid-Open No. 61-57958 discloses a photosensitive member having a surface layer in which conductive particles are dispersed in a resin and having a controlled resistance value, and conductive fine particles are brought into contact with the photosensitive member. A method has been proposed in which a voltage is applied directly to the conductive fine particles to directly inject electric charges into the surface layer to thereby perform uniform charging. However, when the conductive fine particles used for charging come into contact with the photoconductor and the conductive fine particles released from the restraint of the charging member and pressed against the other photoconductor contact member, the photoconductor is easily damaged. In such a process, toner adhesion and filming due to the toner and its components are particularly likely to occur, and the releasability and strength of the photoreceptor surface are further required.
[0017]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present invention by a combination of a specific photosensitive drum and a specific suspension polymerization toner. In other words, no matter what kind of charging means or process is used, a photosensitive drum containing conductive particles and a cured polymer of a photocurable compound containing two or more acrylic functional groups in the surface layer, and a kind of capsule toner. It can be seen that, in combination with a suspension polymerization toner characterized in that the shell portion has a higher glass transition temperature (Tg) than the core portion, image defects such as toner adhesion on the drum and filming do not occur, This combination was found to be good.
[0018]
As described above, according to the present invention, by combining a toner excellent in low-temperature fixability / storage stability / cost merit and a photosensitive drum excellent in release property / strength, the toner on the drum can be used in any charging means and process. An electrophotographic apparatus having excellent image characteristics free from adhesion can be obtained.
[0019]
Hereinafter, the specific method will be described in detail.
[0020]
Preferred examples of the developing toner used in the present invention will be described below.
[0021]
The developing toner of the present invention can be widely used not only for electrophotographic copying machines but also for electrophotographic applications such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making. First, a colorant such as carbon black, a charge control agent, a wax, and other toner property improvers are added to the polymerizable monomer, and a glass transition temperature (Tg) is obtained by polymerizing the polymerizable monomer. A resin-like substance higher than the Tg of the obtained resin is added, and these are mixed and dispersed. At this time, it is preferable to add a polymerization-inactive solvent in order to more efficiently localize the resinous substance to the surface. The toner composition thus obtained is used as an oil phase, a polymerization initiator is added, and suspension polymerization is performed in the presence of a dispersion stabilizer.
[0022]
As an example of the suspension polymerization method, a water-soluble polymer compound, a water phase in which a dispersion stabilizer such as a poorly water-soluble inorganic compound or the like is uniformly dissolved or dispersed, a dispersion of the oil phase is added, and a homomixer is added. The oil droplets are dispersed into oil droplets of 5 to 30 μm by a homogenizer or a dispersing means such as a continuous disperser utilizing vortex flow or cavitation. The weight ratio between the oil phase and the aqueous phase is set in the range of 1: 1 to 1:10, and is set within a range in which coalescence of particles does not occur during polymerization. The dispersion liquid in which the oil phase is uniformly dispersed in the aqueous phase is transferred to a polymerization reactor equipped with a stirrer, a condenser, a thermometer, a nitrogen inlet tube, a dehydration tube, and the temperature is raised to a temperature at which the polymerization initiator is decomposed. The polymerization is performed under an atmosphere. Next, if necessary, treatment with water or a dilute acid is performed, followed by filtration and drying to obtain a toner. When a polymerization-inert solvent is added, the temperature is raised to the boiling point of the polymerization-inert solvent or the azeotropic point with water, and the pressure is reduced under normal pressure or reduced pressure as needed. By distilling off the polymerization-inactive solvent and removing the solvent from the toner particles, the resinous substance can be more efficiently localized on the surface. After the removal of the solvent, the aqueous phase is removed by filtration, and treatment with water or a dilute acid is performed as necessary.
[0023]
Next, examples of preferred embodiments of the electrophotographic photosensitive member used in the present invention will be described below.
[0024]
The electrophotographic photoreceptor of the present invention can be widely used not only for electrophotographic copying machines but also for electrophotographic applications such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.
[0025]
Examples of the conductive substrate include metals such as aluminum and stainless steel, alloys such as aluminum alloys and indium oxide-tin oxide, plastics having a coating layer of these metals and alloys, paper and plastic impregnated with conductive particles, and conductive materials. Cylindrical cylinders and films such as plastics with polymers are used.
[0026]
On these conductive substrates, improvement of the adhesiveness of the photosensitive layer, improvement of coating properties, protection of the substrate, covering of defects on the substrate, improvement of charge injection from the substrate, protection of the photosensitive layer against electrical breakdown, etc. An undercoat layer may be provided for the purpose. The undercoat layer is polyvinyl alcohol, poly-N-vinyl imidazole, polyethylene-oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymerized nylon, glue, gelatin, It is formed by materials such as polyurethane and aluminum oxide. The film thickness is usually about 0.1 to 10 μm, preferably about 0.1 to 3 μm.
[0027]
The photosensitive layer is roughly classified into a single layer type containing a charge generating substance and a charge transporting substance in the same layer, and a laminated type having a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. From the viewpoint of characteristics, it is preferable to use a laminated type.
[0028]
The charge generation layer is composed of an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone face, a squarylium dye, a pyrylium salt, a thiopyrium salt, a triphenylmethane dye, and an inorganic material such as selenium or amorphous silicon. A charge generating substance such as a substance is dispersed in an appropriate binder resin and coated. Alternatively, it is formed by vapor deposition. The binder resin can be selected from a wide range of binder resins, for example, polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacryl resin, phenol resin, silicone resin, epoxy resin, and vinyl acetate resin. Is mentioned. The amount of the binder resin contained in the charge generation layer is selected to be 80% by weight or less, preferably 0 to 40% by weight. Further, the thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.05 to 2 μm.
[0029]
The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them.
[0030]
The charge transport layer is formed by dissolving a charge transport material in a solvent together with a binder resin as required, and applying the solution. The film thickness is generally 5 to 40 μm. As the charge transporting substance, a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene and phenanthrene in a main chain or a side chain; a nitrogen-containing cyclic compound such as indole, carbazole, oxadiazole and pyrazoline; a hydrazone compound; Styryl compounds; and inorganic compounds such as selenium, selenium-tellurium, amorphous silicon and cadmium sulfide.
[0031]
Examples of the binder resin for dispersing these charge transporting substances include resins such as polycarbonate resin, polyester resin, polymethacrylate, polystyrene resin, acrylic resin, and polyamide resin; and organic resins such as poly-N-vinylcarbazole and polyvinylanthracene. Photoconductive polymers and the like can be mentioned.
[0032]
The single-layer type photosensitive layer is formed by applying a solution containing the above-mentioned charge generating substance, charge transporting substance and binder resin.
[0033]
The photoreceptor used in the invention has a layer farthest from the support, that is, an overcoat layer (or a charge injection layer) as a surface layer.
[0034]
This overcoat layer is composed of a conductive fine particle resin dispersion layer in which conductive fine particles are dispersed in a binder resin, the deposited film is deposited, the conductive fine particle resin dispersed film is dipped coating method, spray coating method, roll coating. It is formed by applying by an appropriate coating method such as a method and a beam coating method. Further, a resin formed by mixing or copolymerizing an insulating binder resin with a resin having high light transmittance and ionic conductivity, or a resin formed of a single resin having a medium resistance and photoconductive properties may be used. In the case of the conductive fine particle dispersed film, the amount of the conductive fine particles is preferably 2 to 190% by weight based on the binder resin. If the amount is less than 2% by weight, it is difficult to obtain a desired volume resistance value. If the amount is more than 190% by weight, the film strength is reduced, the charge injection layer is easily scraped off, and the life of the photoconductor is shortened. This is because it becomes a tendency.
[0035]
Examples of the conductive fine particles dispersed in the binder resin of the overcoat layer include metals, metal oxides, conductive polymers, and carbon black. Examples of the metal include aluminum, zinc, chromium, nickel, stainless steel, silver, and the like, and those obtained by vapor-depositing these metals on the surfaces of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide-coated titanium oxide, tin-doped indium oxide, antimony-doped tin oxide, and zirconium oxide. Examples of the conductive polymer include polyacetylene, polythiophene, and polypyrrole. These may be used alone or as a mixture of two or more. Generally, when dispersing particles in the overcoat layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles. The dispersed conductive and insulating particles preferably have a particle size of 0.5 μm or less, particularly preferably 0.1 μm or less. Further, a metal oxide is more desirable in terms of transparency.
[0036]
The resin fine particles are added together with the conductive particles together with the conductive particles in the resin solution so that the particles are not aggregated, or the fluorine atom-containing compound is added during the dispersion of the conductive particles, or the surface of the conductive particles is coated with the fluorine atom-containing compound. It is good to process.
[0037]
By adding a fluorine atom-containing compound or performing a surface treatment on the conductive particles, the dispersibility and dispersion stability of the conductive particles and the fluorine atom-containing resin particles in the resin solution are lower than in the case where the fluorine atom-containing compound is not present. Can be significantly improved. In addition, secondary particles of dispersed particles are formed by dispersing fluorine atom-containing resin particles in a liquid in which conductive particles are dispersed by adding a fluorine atom-containing compound or in a liquid in which conductive particles subjected to surface treatment are dispersed. No coating liquid is obtained which is very stable and has good dispersibility over time.
[0038]
Examples of the fluorine atom-containing compound in the present invention include a fluorinated silane coupling agent, a fluorine-modified silicone oil, and a fluorine-based surfactant. Preferred examples of the compounds are shown in Tables 1 to 3, but the present invention is not limited to these compounds.
[0039]
As a surface treatment method for the conductive particles, the conductive particles and the surface treatment agent are mixed and dispersed in an appropriate solvent, and the surface treatment agent is attached to the surface of the conductive particles. As a dispersion method, a usual dispersion means such as a ball mill and a sand mill can be used. Next, the solvent may be removed from the dispersion solution and fixed to the surface of the conductive particles. If necessary, a heat treatment may be further performed thereafter. Further, a catalyst for promoting the reaction can be added to the treatment liquid. Further, if necessary, the conductive particles after the surface treatment can be further subjected to a pulverizing treatment.
[0040]
The ratio of the fluorine atom-containing compound to the conductive particles is affected by the particle size of the particles, but is 1 to 65 wt%, preferably 1 to 50 wt%, based on the total weight of the surface-treated conductive particles.
[0041]
As described above, by dispersing the conductive particles after adding the fluorine atom-containing compound, or by using the conductive particles surface-treated with the fluorine atom-containing compound, the dispersion of the fluorine atom-containing resin particles is stable, It is possible to form a protective layer having excellent slipperiness and releasability. However, with recent advances in colorization, high image quality, and high stability, there has been a demand for more environmental stability, and a protective layer has come to require even more environmental stability.
[0042]
In the present invention, in order to form an environmentally stable protective layer, a siloxane compound represented by the following general formula (1) may be added at the time of dispersion of conductive particles, or a conductive surface treated in advance. By mixing the particles, a protective layer having better environmental stability can be obtained.
[Outside 1]

[0043]
In the formula, A is a hydrogen atom or a methyl group, and the proportion of hydrogen atoms in all A is in the range of 0.1 to 50%, and n is an integer of 0 or more.
[0044]
By dispersing the coating liquid in which the siloxane compound is added and then dispersed, or the surface-treated conductive fine particles in a binder resin dissolved in a solvent, the secondary particles of the dispersed particles are not formed and the aging is performed. A coating liquid which was stable and excellent in dispersibility was obtained, and a protective layer formed from this coating liquid had high transparency and a film which was particularly excellent in environmental resistance.
[0045]
The molecular weight of the siloxane compound represented by the general formula (1) is not particularly limited, but when the surface treatment is performed, it is better not to have a too high viscosity because of its easiness, and it is preferable that the viscosity is several hundred to About tens of thousands are appropriate.
[0046]
There are two types of surface treatment, wet and dry. In the wet method, conductive particles are dispersed in a solvent with a siloxane compound represented by the general formula (1), and the siloxane compound is attached to the surface of the fine particles. As a dispersing means, general dispersing means such as a ball mill and a sand mill can be used. Next, this dispersion solution is fixed to the surface of the conductive fine particles. In this heat treatment, the Si—H bonds in the siloxane undergo oxidation of hydrogen atoms by oxygen in the air during the heat treatment process, so that a new siloxane bond is formed. As a result, the siloxane develops to a three-dimensional structure, and the surface of the conductive fine particles is enveloped by this network structure. Thus, the surface treatment is completed by fixing the siloxane compound to the surface of the conductive fine particles. However, if necessary, the fine particles after the treatment may be subjected to a pulverizing treatment. In the dry treatment, the siloxane compound and the conductive fine particles are mixed and kneaded without using a solvent, whereby the siloxane compound is attached to the surface of the fine particles. After that, heat treatment and pulverization are performed in the same manner as in the wet treatment to complete the surface treatment.
[0047]
The ratio of the siloxane compound to the conductive fine particles in the present invention depends on the particle size of the fine particles, the ratio of the methyl group to the hydrogen atom in the siloxane, and the like, but is 1 to 50% by weight, preferably 3 to 40% by weight.
[0048]
[Table 1]

[0049]
[Table 2]

[0050]
[Table 3]

[0051]
In the present invention, it is preferable that the overcoat layer contains lubricant particles. The reason is that the friction between the photosensitive member and the charging member during charging is reduced, so that the charging nip is enlarged and the charging characteristics are improved. In particular, it is preferable to use a fluorine resin, a silicone resin or a polyolefin resin having a low critical surface tension as the lubricant particles. More preferably, a fluorine-based resin, in particular, polytetrafluoroethylene (PTFE) is preferred. In this case, the amount of the lubricant particles is 2 to 50% by weight, preferably 5 to 40% by weight, based on the binder resin. If the amount is less than 2% by weight, the amount of the lubricant particles is not sufficient, so that the charging characteristics are not sufficiently improved. If the amount exceeds 50% by weight, the resolution of the image and the sensitivity of the photoreceptor are greatly reduced. It is.
[0052]
Such fluororesin particles include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, It is composed of one or more selected from a fluoroethylene-ethylene copolymer and a tetrafluoroethylene-hexafluoropropylene-perfluoroalkylvinyl ether copolymer. Commercially available fluorine resin particles can be used as they are. Those having a number average molecular weight of from 30,000 to 5,000,000 can be used, and those having a particle size of from 0.01 to 10 µm, preferably from 0.05 to 2.0 µm can be used.
[0053]
The thickness of the overcoat layer in the present invention is preferably from 0.1 to 10 μm, particularly preferably from 1 to 7 μm. When the film thickness is less than 0.1 μm, resistance to minute scratches is lost, and as a result, an image defect occurs. When the film thickness exceeds 10 μm, an image is easily disturbed due to diffusion of injected charges.
[0054]
As the exposure unit in the present invention, a known unit such as a laser or an LED can be used.
[0055]
The charging means is a means for contacting the surface layer of the electrophotographic photoreceptor and charging the surface of the photoreceptor by a voltage applied to the charging member. Examples of the configuration include a charging roller, a charging blade, a charging magnetic brush, and a charging fiber brush.
[0056]
The charging roller and the charging blade may have a configuration in which a coating layer in which conductive fine particles are dispersed is disposed as a resistance layer on a conductive roller-like or blade-like elastic layer. The resistance value of these charging members is 1 × 10 ⁴ Ω ~ 1 × 10 ⁷ It is desirable to be in the range of Ω. Resistance value is 1 × 10 ⁴ If it is lower than Ω, pinhole leak may not be prevented, and 1 × 10 ⁷ If it is higher than Ω, a current necessary for charging may not be able to flow.
[0057]
Examples of the resin material used for the elastic layer include synthetic rubbers such as EPDM, EPT, EPM, NBR, BR, and CR, thermosetting elastomers such as natural rubber, and thermoplastic materials such as vinyl chloride, vinyl acetate polyester, and PVA. An elastomer or the like is used.
[0058]
As the conductive fine particles added to impart conductivity to the elastic layer, conductive particles such as carbon black, zinc oxide, titanium oxide, and metal powder are used.
[0059]
The elastic layer desirably has a hardness of 20 to 80 [deg.] In the hardness specified by the altimeter A of JIS K, 6301.
[0060]
As the resin material used for the resistance layer disposed on the surface of the charging member, a material having flexibility at normal temperature, such as polyamide, polyimide, fluororesin, silicon resin, PVA, and polyester is used.
[0061]
Furthermore, the photoreceptor of the present invention is also suitable for a charging system in which charges are directly injected from a charging member in contact. Examples of the charging member used in such a charging method include a Tiden roller, a charging blade, a charging magnetic brush, and a charging fiber brush. Of these, a charged magnetic brush and a charged roller are preferable in terms of durability, and a charged magnetic brush is more preferable in terms of uniform charging.
[0062]
The charged magnetic brush method forms spikes of magnetic powder such as ferrite by a magnetic force, and forms the brush shape of the sprinkled magnetic powder at a high density, and applies a voltage to play the role of a charging member. It was carried. The spikes can be considerably densified, and a finer uniform charging can be achieved.
[0063]
It is composed of a non-magnetic conductive sleeve, a magnet roll contained therein, and a sleeve-shaped magnetic conductive particle. The magnet roll is fixed and rotated so that the sleeve surface moves at a peripheral speed difference from the photosensitive member.
[0064]
The magnetic conductive particles are
・ Mixed resin and magnetic powder such as magnetite to form particles, or mixed with conductive carbon for resistance adjustment
・ Sintered magnetite, ferrite, or those whose resistance has been adjusted by reducing them
-Alternatively, those obtained by plating these magnetic particles to have an appropriate resistance value can be used.
[0065]
Although there is no particular limitation on the developing means, a system in which the developing means is also a substantial cleaning means, that is, the transfer position and the charging position, and the residual on the electrophotographic photosensitive member after transfer between the charging position and the developing position In the case of a so-called cleaner-less system having no cleaning means for collecting and storing the collected toner, reversal development is preferable, and a configuration in which the developer and the photoconductor are in contact is preferable. For example, a contact two-component developing method, a contact one-component method and the like are mentioned as suitable developing methods. This is because, when the developer and the transfer residual toner are in contact with each other on the photosensitive member, a rubbing force is applied to the electrostatic force, and there is a tendency that the transfer residual toner can be effectively collected by the developing unit. It is preferable that the DC component of the bias applied to the development be between the black portion (the exposed portion in the case of the reversal development) and the potential of the white background portion.
[0066]
As a transfer unit, a known method such as a corona, a roller, and a belt is used.
[0067]
In the present invention, the electrophotographic photosensitive member, the charging member, and, if necessary, the developing means are integrally supported to form a cartridge, and the process cartridge can be detachably attached to the main body of the electrophotographic apparatus.
[0068]
In the present invention, the developing means may be a separate cartridge from the cartridge having the electrophotographic photosensitive member and the charging member.
[0069]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to examples.
[0070]
(Example 1)
(Method of making photoconductor)
A coating composed of the following materials was applied on an aluminum cylinder (Φ30 mm × 358 mm) by a dipping method, and thermally cured at 140 ° C. for 30 minutes to form a 15 μm conductive layer.
Conductive pigment: 10 parts of titanium oxide treated with tin oxide and antimony oxide
Pigment for resistance adjustment: 10 parts of titanium oxide
Binder resin: 10 parts of phenolic resin (Plyofen J325, manufactured by Dainippon Ink and Chemicals, Inc.)
Leveling agent: silicone oil (SH28PA, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.001 part
Solvent: methanol, methoxypropanol 1/1 20 parts
Next, 10 parts of a copolymerized polyamide resin (Amilan CM-8000, manufactured by Toray Industries, Inc.), 30 parts of a methoxymethylated 6 nylon resin (Toresin EF-30T, manufactured by Teikoku Chemical Co., Ltd.), and 400 parts of methanol Then, a solution dissolved in a mixed solvent of 200 parts of n-butanol was applied by a dipping method, and dried with hot air at 90 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.7 μm.
[0071]
Next, 3 parts of titanyloxyphthalocyanine having strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° in the Bragg angle (2θ ± 0.2) in the X-ray diffraction spectrum with respect to CuKα. And 2 parts of polyvinyl butyral (trade name: Esrec BM2, manufactured by Sekisui Chemical) and 100 parts of cyclohexanone were dispersed in a sand mill using Φ1 mm glass beads for 4 hours, and then 90 parts of ethyl acetate was added to prepare a dispersion for charge generation layer. Prepared. This paint was applied on the intermediate layer by a dipping method and dried with hot air at 80 ° C. for 15 minutes to form a 0.1 μm charge generation layer.
[0072]
Next, 7 parts of an amine compound having the following structural formula
[Outside 2]

[0073]
And 10 parts of bisphenol Z-type polycarbonate (Iupilon Z-400, manufactured by Mitsubishi Gas Chemical Co., Ltd.) are dissolved in a mixed solvent of 30 parts of dichloromethane and 40 parts of monochlorobenzene, and the paint is immersed on the charge generation layer. And dried at 120 ° C. for 1 hour to form a 17 μm charge transport layer.
[0074]
Next, a preparation liquid for the overcoat layer was prepared by the following procedure.
[0075]
30 parts of antimony-doped tin oxide fine particles (trade name: T-1, manufactured by Mitsubishi Materials Corporation) having an average particle size of 0.02 μm and treated with methyl hydrogen silicone oil (trade name: KF99, manufactured by Shin-Etsu Silicone Co., Ltd.) 20 parts of antimony-doped tin oxide fine particles (same as above) having an average particle size of 0.02 μm, surface-treated with a fluorine-modified silane coupling agent (trade name: LS1090, manufactured by Shin-Etsu Silicone Co., Ltd.) were treated with an acrylic resin having the structural formula (2) 18 parts of a monomer (trade name: TMP3A-3, manufactured by Osaka Organic Chemical Co., Ltd.)
[Outside 3]

[0076]
Dispersion was carried out for 72 hours with a sand mill together with 80 parts of ethanol.
[0077]
The surface treatment amount was determined by measuring the weight loss when the temperature was raised from room temperature to 500 ° C. in a nitrogen atmosphere using a thermogravimeter TG / DTA2208 (manufactured by Seiko Instruments Inc.). As a result, methyl hydrogen silicone oil was 11.2%, and fluorine-modified silane coupling agent was 7.1%.
[0078]
To this solution, 17 parts of 4-fluoroethylene resin particles (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) were mixed, and the mixture was further dispersed for 2 hours with an acid-filtration apparatus. 2.7 parts of 2,4-diethylthioxanthone and 0.9 parts of 4,4'-bis (diethylamino) benzophenone as an initiator were added and dissolved to prepare a surface layer-like preparation.
[0079]
This paint was dipped and applied on the charge transport layer, and was applied with a metal halide lamp at 240 W / cm. ² UV light was applied for 30 seconds to perform photocuring, followed by drying with hot air at 120 ° C. for 2 hours to form a surface layer having a thickness of 5 μm.
[0080]
(How to make toner)
6. Styrene 60 parts, 2-ethylhexyl acrylate 40 parts, divinylbenzene 1.0 part (design value of Tg of the above three components: 20.9 ° C.), carbon black [manufactured by Mitsubishi Chemical Corporation, # 44] 5 parts, 2 parts of low molecular weight polyethylene [Mitsui Petrochemical Industry Co., Ltd., Mitsui High Wax 1120H], 1 part of charge control agent [Hodogaya Chemical Co., Ltd., Aizen Spiron Black TRH] and polyester resin [Kao ( Co., Ltd., KTP2150, Tg: 80 ° C.] 10 parts was separated by an attritor for 5 hours, and then 4 parts of 2,2′-azobisisobutyronitrile was added thereto. 100 parts by weight of a 10% by weight water slurry, manufactured by Nippon Chemical Industry Co., Ltd .; 0.1 part of sodium dodecylbenzenesulfonate [manufactured by Tokyo Chemical Industry Co., Ltd.]; and 400 parts of water. Addition to those the, stirred and mixed. Next, the mixed solution was passed twice through a cavitation continuous dispersing machine Milder (manufactured by Ebara Corporation) under the conditions of a feed rate of 251 / min and a rotation speed of 8000 rpm to suspend and disperse the mixture. This suspension was subjected to a polymerization reaction at 80 ° C. for 6 hours in a separable flask equipped with a dehydrating tube, a condenser and a stirrer at a stirring speed of 100 rpm under a nitrogen atmosphere. After the polymerization reaction, the resultant was filtered, washed with hydrochloric acid, and washed with water, and dried under reduced pressure at 40 ° C. overnight to obtain a toner. The particle size and the particle size distribution of the obtained toner were measured using a Coulter counter (TA-II, manufactured by Nikkaki Co., Ltd., aperture diameter: 100 μm). The standard deviation of the distribution was 2.5 μm. Observation of the obtained toner with a transmission electron microscope showed a clear core-shell structure in which a resin-like substance was formed around the polymerizable monomer polymer.
[0081]
Next, evaluation will be described.
[0082]
The apparatus used was a Canon color LBP "LBP2160" (process speed 117.2 mm / sec). By applying a DC bias of -550 V to the charging roller to apply a charge to the photoreceptor and superimposing an AC bias of Vpp 600 V and 1000 Hz, the non-irradiation charging potential Vd of the standard photoreceptor sample surface is -550 V, and the laser The potential V1 at the time of light irradiation was -150V.
[0083]
Such an electrophotographic apparatus was loaded / filled with the above-mentioned photoreceptor and toner, and subjected to a durability test of 10,000 sheets in which paper passing and printing were repeated in a normal temperature and normal humidity environment (23 ° C., 50% RH). Table 4 shows the photoreceptor surface potential, the amount of scraping, and the image (toner adhesion, filming, etc.) before and after the endurance. In Example 1, neither toner adhesion nor filming on the drum was observed, and good images were obtained before and after the endurance.
[0084]
After this evaluation, the images were transferred to a high-temperature and high-humidity environment (30 ° C., 80% RH) and a normal-temperature, low-humidity environment (23 ° C., 5% RH) to take images. The image results are also shown in Table 4.
[0085]
(Example 2)
The same photoreceptor and toner were used as in Example 1, and the evaluation was performed by changing the evaluation method as follows.
[0086]
The apparatus was modified from a Canon color LBP "LBP2160" (process speed: 117.2 mm / sec). In the remodeling method, the charger was first replaced with a magnetic brush injection charger as described above. As the magnetic particles of the charging member, 100 parts of magnetite was put into a polystyrene resin, kneaded and pulverized, and the particle diameter was 30 μm and the resistance value was 1 × 10 ⁶ Ω. The resistance value of the magnetic brush is defined as a resistance value when an aluminum drum is brought into contact with the magnetic brush having the above configuration and a DC voltage of 100 V is applied.
[0087]
Such a magnetic particle is coated on a sleeve containing a magnet with a thickness of 1 mm to form a charging nip having a width of about 2 mm between the sleeve and the photosensitive member. The sleeve is rotated so as to slide in the opposite direction at a speed one time faster than the peripheral speed of the photoreceptor surface, so that the magnetic brush of the photoreceptor comes into uniform contact.
[0088]
A DC bias of -550 V is applied to the magnetic brush, and further, an AC bias of Vpp of 600 V and 1000 Hz is superimposed on the magnetic brush, whereby charges are injected into the photoconductor, and a surface potential of -550 V is obtained.
[0089]
The photosensitive member and the toner of Example 1 were loaded / filled in such an electrophotographic apparatus, and a durability test was performed on 10,000 sheets in which paper passing and printing were repeated in a normal temperature and normal humidity environment (23 ° C., 50% RH). Table 4 shows the photoreceptor surface potential, the amount of shaving, and the image before and after the endurance. At this time, neither toner adhesion nor filming on the drum was observed.
[0090]
After this evaluation, the images were transferred to a high-temperature and high-humidity environment (30 ° C., 80% RH) and a normal-temperature, low-humidity environment (23 ° C., 5% RH) to take images. The image results are also shown in Table 4.
[0091]
(Example 3)
In the surface layer of the photoreceptor of Example 1, the same evaluation was performed with the same configuration as in Example 1 except that the acrylic monomer having the following structure was used.
[0092]
Table 4 shows the results.
[Outside 4]

[0093]
(Example 4)
The same evaluation was performed as in Example 1 except that the same photoconductor and toner were used as in Example 3, and the evaluation method was changed as in Example 2.
[0094]
Table 4 shows the results.
[0095]
(Example 5)
In the surface layer of the photoreceptor of Example 1, the same structure as in Example 1 was used except that a mixture of the following structural formulas (3) and (4) at a ratio of 1/1 was used as an acrylic monomer. The same evaluation was performed.
[Outside 5]

[0096]
Table 4 shows the results.
[0097]
(Example 6)
The same photoreceptor and toner as in Example 5 were used, and the evaluation was performed in the same manner as in Example 1 except that the evaluation method was changed as in Example 2.
[0098]
Table 4 shows the results.
[0099]
(Comparative Example 1)
The evaluation was performed in the same manner as in Example 1 except that an overcoat layer was not provided on the photoreceptor, and the photoreceptor coated up to the charge transport layer prepared in Example 1 was used as it was, and the evaluation method was performed as in Example 2. Was done.
[0100]
Table 4 shows the results.
[0101]
As a result, toner adhesion to the photosensitive member surface occurred on the 100th durable sheet, and filming occurred on the 800th durable sheet, and the durability could not be maintained further.
[0102]
In addition, under high temperature and high humidity, image deletion occurred, and under normal temperature and low humidity, a blank image was formed.
[0103]
(Comparative Example 2)
In the drum prepared in Example 1, antimony-doped tin oxide fine particles having an average particle size of 0.02 μm and surface-treated with methyl hydrogen silicone oil (trade name: KF99, manufactured by Shin-Etsu Silicone Co., Ltd.) when the overcoat layer was provided. (Trade name: T-1, manufactured by Mitsubishi Materials Corporation) 30 parts and antimony-doped with an average particle size of 0.02 μm, surface-treated with a fluorine-modified silane coupling agent (trade name: LS1090, manufactured by Shin-Etsu Silicone Co., Ltd.) Coating up to the overcoat layer was carried out in the same manner as in Example 1, except that 20 parts of tin oxide fine particles (same as above) were not added. The evaluation was performed in the same manner as in Example 1 except that the evaluation method was as in Example 2.
[0104]
Table 4 shows the results.
[0105]
As a result, poor charging occurred at an early stage, and the poor charging worsened as durability advanced.
[0106]
(Example 7)
The same evaluation was performed with the same configuration as in Example 1 except that the photoreceptor used was that of Example 1 and that the toner prepared by the following method was used.
[0107]
Toner Production Method In Example 1, 10 parts of a polyester resin (KTP Co., Ltd., KTP2150, Tg: 80 ° C.) was changed to 10 parts by ethyl cellulose (trade name: Hercules N-4, Tg: 140 ° C.), and carbon black and the like were used. A toner was obtained in the same manner except that the toner was dissolved after dispersing with a lighter for 5 hours. The weight average particle diameter of the obtained toner was 11.0 μm, and the standard deviation of the number distribution of the particle diameter was 2.6 μm.
[0108]
Table 4 shows the evaluation results.
[0109]
(Example 8)
The same photoconductor and toner were used as in Example 7, and the evaluation was performed in the same manner as in Example 1 except that the evaluation method was changed as in Example 2.
[0110]
Table 4 shows the results.
[0111]
(Example 9)
The same evaluation was performed with the same configuration as in Example 1 except that the photoreceptor used was that of Example 1 and that the toner prepared by the following method was used.
[0112]
The toner was prepared in the same manner as in Example 1 except that 5 parts of ethyl cellulose (trade name: Hercules N-4) and 100 parts of isobutyl alcohol were added after dispersing for 5 hours using an attritor in Example 1. Then, the temperature was raised to 90 ° C. to distill off isobutyl alcohol and promote uneven distribution of the surface of ethyl cellulose. Further, after isobutyl alcohol was completely removed by reducing the pressure, filtration, washing with hydrochloric acid, and washing with water were performed, and the resultant was dried under reduced pressure at 40 ° C. overnight to obtain a toner. The weight average particle diameter of the obtained toner was 11.5 μm, and the standard deviation of the number distribution of the particle diameter was 2.8 μm. Observation of this toner with a transmission electron microscope revealed a beautiful core-shell structure.
[0113]
Table 4 shows the evaluation results.
[0114]
(Example 10)
The same photosensitive member and toner as in Example 9 were used, and the evaluation was performed in the same manner as in Example 1 except that the evaluation method was changed as in Example 2.
[0115]
Table 4 shows the results.
[0116]
(Comparative Example 3)
The same evaluation was performed with the same configuration as in Example 1 except that the photoreceptor used in Example 1 was used and the toner used was a pulverized toner prepared by the following method.
[0117]
Table 4 shows the results.
[0118]
(Comparative Example 4)
The same photosensitive member and toner as in Comparative Example 3 were used, and the evaluation was performed in the same manner as in Example 1 except that the evaluation method was changed as in Example 2.
[0119]
Table 4 shows the results.
[0120]
As is apparent from Table 4, when the photoreceptor having a specific overcoat layer and the polymerized toner are combined, the initial surface potential characteristics / images are good, and even when the durability of 10,000 sheets is performed, the drum is still on the drum. Defects such as toner adhesion to the film and filming did not occur, and the drum surface was well scraped. This was effective whether the charging method was direct charging using a roller or injection charging using conductive fine particles.
[0121]
On the other hand, in the case of the combination of the drum having no overcoat layer and the polymerization toner, defects such as toner adhesion on the drum and filming occurred in the early stage of the durability, and the drum surface abrasion / scratch was NG. Further, under high temperature and high humidity, image deletion occurred, and under low temperature and normal temperature, white spots of the image occurred. Further, in a system in which the conductive fine particles were not added to the overcoat layer, charging was poor, and printing was not properly performed.
[0122]
Furthermore, the combination of the drum having the overcoat layer and the pulverized toner obtained by a pulverization method instead of polymerization resulted in poor fixing, and printing was not properly performed.
[0123]
That is, only when a specific overcoat layer and a polymerized toner were combined, good durability was obtained, and the effectiveness of the present invention was proved.
[0124]
[Table 4]

[0125]
【The invention's effect】
According to the present invention, even if a large number of continuous prints are performed, image defects such as toner adhesion on the drum and filming do not occur, and high durability / low-temperature fixing / storage stability / cost merit which have not been realized conventionally. Provide an improved electrophotographic apparatus.

Claims (4)

In an electrophotographic apparatus having a charging unit, an exposure unit, a developing unit, and a transfer unit around an electrophotographic photosensitive member,
The surface layer of the electrophotographic photoreceptor contains a cured polymer of a photocurable compound containing two or more acrylic functional groups in one molecule, and conductive particles,
The developing means has a toner having an external additive, and the toner is obtained by polymerization by a suspension polymerization method. In the polymerization, the glass transition of a polymerizable monomer mixture containing a colorant and a charge control agent is performed. An electrophotographic apparatus characterized in that a suspension polymerization is carried out by adding and containing a resin-like substance having a Tg higher than the temperature (Tg). 2. The electrophotographic apparatus according to claim 1, wherein the charging means has a charging member made of magnetic particles placed in contact with the electrophotographic photosensitive member. A charging step of charging the electrophotographic photosensitive member by applying a voltage to a charging member made of magnetic particles in contact with the electrophotographic photosensitive member, and an electrostatic latent by irradiating the charged electrophotographic photosensitive member with light. Image forming method including an exposing step of forming an image, a developing step of forming a toner image by developing the formed electrostatic latent image using toner, and a transfer step of transferring the developed toner image to a transfer material At
The surface layer of the electrophotographic photoreceptor contains a cured polymer of a photocurable compound containing two or more acrylic functional groups in one molecule, and conductive particles,
The developing means has a toner having an external additive, and the toner is obtained by polymerization by a suspension polymerization method. In the polymerization, the glass transition of a polymerizable monomer mixture containing a colorant and a charge control agent is performed. An electrophotographic apparatus characterized in that a suspension polymerization is carried out by adding and containing a resin-like substance having a Tg higher than the temperature (Tg). An electrophotographic photosensitive member, and a charging unit having a charging member made of magnetic particles arranged in contact with the electrophotographic photosensitive member are integrally supported, and in a process cartridge detachably attachable to an electrophotographic apparatus,
The electrophotographic apparatus has the charging unit, the exposing unit, the developing unit, and the transferring unit around the electrophotographic photosensitive member in this order, and the surface layer of the electrophotographic photosensitive member has two acrylic functional groups in one molecule. The cured polymer of the photocurable compound containing the above, including conductive particles,
The developing means has a toner having an external additive, and the toner is obtained by polymerization by a suspension polymerization method. In the polymerization, the glass transition of a polymerizable monomer mixture containing a colorant and a charge control agent is performed. An electrophotographic apparatus characterized in that a suspension polymerization is carried out by adding and containing a resin-like substance having a Tg higher than the temperature (Tg).