JP3598570B2 - Electrostatic image developer - Google Patents
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Description
【０００１】
【産業上の利用分野】
本発明は電子写真法、静電記録法等において形成される静電潜像を現像するために使用される静電荷像現像剤に関するものである。
【０００２】
【従来の技術】
電子複写機等で使用される現像剤は、その現像工程において、例えば静電荷像が形成されている感光体等の像担持体に一旦付着され、次に転写工程において感光体から転写紙に転写された後、定着工程においてコピー紙面に定着される。その際、潜像保持面上に形成される静電荷像を現像するための現像剤として、キャリアとトナーから成る二成分系現像剤及びキャリアを必要としない一成分系現像剤（磁性トナー、非磁性トナー）が知られている。
【０００３】
該現像剤に含有されるトナーとしては、正荷電性トナー、負荷電性トナーがあり、従来より正荷電性トナーへ帯電性を付与するものとしては、ニグロシン系染料、４級アンモニウム塩等のトナーへの添加剤としての帯電制御剤や、キャリアに所定の帯電性を付与するコーティング剤等が知られており、一方、負帯電性を付与するものとしては、含金アゾ染料等の帯電制御剤や無機微粉末、有機微粉、及びキャリアのコーティング剤等が知られている。
【０００４】
そして、トナーの流動性、帯電性等を改善する目的で、更には、トナー粒子に導電性を付与し現像性の向上や安定した画像濃度及び画質を付与する目的で各種金属酸化物等の微粉末を添加して使用する方法や、また感光体に付着する紙粉やコロナチャージャーで発生する含窒素化合物を感光体から除去する目的で各種磁性粉末等を添加して使用する方法が提案されている。トナー粒子と磁性粉末を含有したトナーまたは現像剤の具体的な例としては、特開昭５８−１０５２３６号公報、特開昭５８−１１８６５２号公報、特開昭６２−２５８４７２号公報、特開平１−２２９２６６号公報、特開平５−１４６３５５号公報などに記載されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、従来のトナーまたは現像剤を用いて複写機などで繰り返しコピーした場合、画像濃度が安定しなかったり、コピーを重ねていく内にカブリが悪化したり、階調性が悪化したり、トナー消費量が途中から多くなったり、複写機内部を汚染するトナー飛散が多く発生するなどの問題があった。更に、十分な現像性を得るために、磁性粉末をトナー粒子に十分な量を添加すると磁性粉末が有機光半導体などの感光体に損傷を与え、感光体の傷ついた部分にトナーまたは遊離した外添剤が埋まり込むことでコメット状のトナーまたは外添剤付着による画像欠陥を発生させたり、また感光体の表面を磁性粉末などの外添剤が研磨することで感光体の帯電性能を劣化させたり、感光体表面が溝状に摩耗されることでコピー黒ベタ部にスジ状欠陥を発生するなどの問題が生じていた。
【０００６】
従って、本発明の第１の目的は、画像濃度、カブリが良好で、階調性に優れ、ハケ筋、欠け、コメット等の画像欠陥が無い高画像・高画質の複写物が得られる現像剤を提供することにある。第２の目的は繰り返し連続的にコピー、印刷した場合にも画像・画質が安定し、機内汚染が少なく、トナー消費量が安定するなど耐久性能に優れた現像剤を提供することにある。第３の目的は温度、湿度などが変化した場合でも画像濃度、カブリなどの画像・画質変化の小さい環境依存性の良い現像剤を提供することにある。第４の目的は高温度で長時間貯蔵保存した場合でもトナーが固まることなく画像・画質の変化が小さいなどの貯蔵安定性に優れた現像剤を提供することにある。
【０００７】
【課題を解決するための手段】
本発明者らは、かかる問題を鋭意検討した結果、トナー粒子に添加する無機微粉末の表面の面数を１０面以上にすることによって、上記の問題点が解決できることを見出して、本発明に到達した。すなわち、本発明の要旨は、樹脂および着色剤を含有する非磁性トナー粒子の表面に１０面体以上の多面体無機微粉末が外添されていることを特徴とする静電荷像現像剤に存する。
【０００８】
【作用】
以下、本発明を詳細に説明する。
本発明に使用し得る樹脂としては、静電荷像現像用トナーに適した公知の種々のものが使用できる。
スチレン系樹脂（スチレンまたはスチレン置換体を含む単重合体または共重合体）としては、例えば、ポリスチレン、クロロポリスチレン、ポリ−α−メチルスチレン、スチレン−クロロスチレン共重合体、スチレン−プロピレン共重合体、スチレン−ブタジエン共重合体、スチレン−塩化ビニル共重合体、スチレン−酢酸ビニル共重合体、スチレン−アクリル酸エステル共重合体（スチレン−アクリル酸メチル共重合体、スチレン−アクリル酸エチル共重合体、スチレン−アクリル酸ブチル共重合体、スチレン−アクリル酸オクチル共重合体及びスチレン−アクリル酸フェニル共重合体等）、スチレン−メタクリル酸エステル共重合体（スチレン−メタクリル酸メチル共重合体、スチレン−メタクリル酸エチル共重合体、スチレン−メタクリル酸ブチル共重合体及びスチレン−メタクリル酸フェニル共重合体等）、スチレン−α−クロルアクリル酸メチル共重合体及びスチレン−アクリロニトリル−アクリル酸エステル共重合体などがある。さらにまた、特公昭５１−２３３５４号公報、特開昭５０−４４８３６号公報に記載されている架橋系バインダー樹脂、あるいは特公昭５５−６８９５号公報、特公昭６３−３２１８０号公報に記載されている非架橋系バインダー樹脂も使用できる。
【０００９】
ポリエステル樹脂としては、公知の飽和、不飽和のものから任意に使用でき、組成としては多価アルコールと多塩基酸よりなり、必要に応じてこれら多価アルコール及び多塩基酸の少なくとも一方が３価以上の多官能性成分を含有する単量体組成物を重合することにより得られる。
エポキシ系樹脂としては、例えばビスフェノールＡとエピクロルヒドリンとの重縮合物の汎用エポキシ樹脂、カルボン酸、フェノール、ジアリールスルホンアミド等で変性された変性エポキシ樹脂、フェノール樹脂とエポキシ樹脂をブレンドしたエポキシ樹脂などがある。
【００１０】
その他の樹脂として、塩化ビニル樹脂、ロジン変性マレイン酸樹脂、フェノール樹脂、ポリエチレン樹脂、ポリプロピレン樹脂、アイオノマー樹脂、ポリウレタン樹脂、シリコーン樹脂、ケトン樹脂、エチレン−エチルアクリレート共重合体、キシレン樹脂、ポリビニルブチラール樹脂、並びにポリカーボネート樹脂等がある。
本発明に用いるのに好ましい樹脂としてはスチレン系樹脂、ポリエステル樹脂及びエポキシ樹脂等を挙げることができる。また、樹脂は単独に使用するに限らず、２種以上併用することができ、本発明に用いる樹脂としてはスチレン系樹脂を主成分（好ましくは５０％以上）とするものが特に好ましい。
【００１１】
樹脂のフロー軟化温度（Ｔｍ）としては８０〜１５０℃程度がよく、更には９０〜１４０℃程度が好ましい。８０℃未満では紙への定着温度は低くて良好であるが、ホットオフセットが発生しやすく、またトナーが現像槽内部で破砕されやすくなりキャリア表面、ドクターブレードにトナーが固着するスペント現象が発生し、帯電特性の悪化を引き起こし、ひいては現像剤の耐久性能の悪化を招き問題がある。また、１５０℃より高いと定着温度紙への定着温度が高く、またトナー粉砕性が悪い等の問題がある。
【００１２】
樹脂のガラス転移温度は４５℃程度以上が好ましく、４５℃未満では４０℃の高温で長時間トナーを放置した場合にトナーの固い凝集或いは固着を招くなど保存安定性が悪く、また、外添工程でトナー凝集物を生成し易く、更に篩別装置のスクリーン、側壁等に付着し凝集物を生成しやすく、更にまたトナーを現像器内で長時間使用した場合現像器内の軸受、穂立ち規制板等の部位に固着したりするなどの使用上の問題がある。
樹脂の製造は公知の製造方法で行えばよく、例えばスチレン系樹脂の場合には溶液重合、懸濁重合、塊状重合、乳化重合等により行えばよく、必要に応じて低分子量体と高分子量体の重合方法を違えてもよい。
本発明で使用する樹脂の各試験方法を以下に説明する。
【００１３】
〔フロー軟化温度（Ｔｍ）〕
フローテスター（（株）島津製作所社製ＣＦＴ−５００）において、試料１ｇをノズル１ｍｍ×１０ｍｍのダイ、荷重３０ｋｇ、予熱時間５０℃で５分、昇温速度３℃／分の条件下で測定を行い、フロー開始から終了までの距離の中間点の温度をフロー軟化温度（Ｔｍ）とする。
【００１４】
〔ガラス転移温度（Ｔｇ）〕
示差熱分析計（（株）島津製作所社製ＤＴＡ−４０）において、昇温速度１０℃／分の条件で測定した曲線の転移（変曲）開始部に接線を引き、その交点温度をガラス転移温度（Ｔｇ）とする。
本発明で用いる着色剤としては、従来から用いられているものであれば特に制限されるものではなく、任意の適当な顔料又は染料が使用できる。例えば、酸化チタン、亜鉛華、アルミナホワイト、炭酸カルシウム、紺青、マグネタイト、カーボンブラック、フタロシアニンブルー、フタロシアニングリーン、ハンザイエローＧ、ローダミン系顔料、クロムイエロー、キナクリドン、ベンジジンイエロー、ローズベンガル、トリアリルメタン系染料、アントラキノン染料、モノアゾ及びジスアゾ系顔料などを所望するトナーの色に着色剤を単独または混合して用いる。着色剤の含有量は、現像により可視像を形成することができるようトナーを着色するのに十分な量あればよく、例えば樹脂１００重量部に対して１〜２０重量部とするのが好ましい。
【００１５】
この他、必要に応じてトナーの熱特性、物理特性、離型特性等を改善する目的で助剤を少量添加してもよく、例えば、ポリアルキレンワックス、パラフィンワックス、高級脂肪酸、脂肪酸アミド、金属石鹸等が使用できる。その添加量は、トナー粒子１００重量部に対して０．１〜１０重量部が好ましい。
更にこの他、トナーの帯電性を調整する目的で公知の正荷電性または負荷電性の帯電制御剤を単独または併用して使用することができる。正荷電性トナーの場合にはニグロシン系染料、４級アンモニウム塩、トリアミノトリフェニルメタン系化合物、イミダゾール化合物等の公知の帯電制御剤、負荷電性トナーの場合には含金アゾ系染料、サルチル酸金属錯体、アルキルサルチル酸金属錯体、カーリックスアレーン化合物等の公知の帯電制御剤を適量添加しても良い。その添加量は樹脂１００重量部に対して０．０５〜１０重量部程度が好ましい。
【００１６】
本発明でトナー粒子と混合する外添剤としては、少なくとも表面の面数が１０面以上、好ましくは１２面以上、更に好ましくは１４〜３０面の多面体無機微粉末が使用される。１０面未満の無機微粉末、例えば針状や、６面体、８面体等の磁性粉末を使用すると、感光体表面の損傷が大きくなりスジ状の凹凸欠陥や凹部にトナーまたは外添剤の埋まり込むコメット状の欠陥が発生し易くなり、ひいてはコピー、印刷等の画像欠陥を発生し易くなり好ましくない。一方、角がなく、丸みを帯びたような形状では、フィルミング（ワックス等のトナー成分または外添剤等の微粉末が感光体へ付着する現象）防止効果が発揮されない。
【００１７】
更に、多面体無機微粉末の粒径は２μｍ以下が好ましく、更には１μｍ以下が好適である。２μｍより大きいと感光体への研磨性が強く、損傷を与えてしまい、安定した画像・画質の複写物が得られにくい。
更にまた、多面体無機微粉末のＢＥＴ法比表面積は２ｍ２ ／ｇ以上、好ましくは３ｍ２ ／ｇ以上が好適である。比表面積が２ｍ２ ／ｇ未満だと粒径が２μｍより大きい場合と同じ問題があり好ましくない。
【００１８】
本発明に用いる多面体無機微粉末としては、例えば酸化鉄、酸化クロム、チタン酸カルシウム、チタン酸ストロンチウム、チタン酸バリウム、チタン酸マグネシウム、酸化セリウム、酸化ジルコニウム、酸化アルミニウム、酸化チタン、酸化亜鉛などがあり、これらを単独もしくは混合して用いる。本発明の多面体無機微粉末としては多面体磁性粉末を好適に用いることができる。
【００１９】
磁性粉末の構造は、一般式（ＭＯ）（Ｆｅ２ Ｏ３ ）で表わされるフェライト、マグネタイトがよく、ここでＭはＣｕ、Ｚｎ、Ｆｅ、Ｍｇ、Ｍｎ、Ｎｉなどの２価の金属を表し、１種または２種以上使用してもよい。トナーの抵抗調整付与機能などの面から、Ｍは少なくともＦｅを含有することが好ましい。
多面体無機微粉末の混合量は、トナー粒子１００重量部に対して０．０５〜１０重量部が好ましく、更に０．１〜１重量部が好適である。少なすぎると感光体に付着したトナーの研磨効果はなく、また多すぎると感光体に損傷を与える。更にまた多面体磁性粉末を用いる場合には、該粉末の抵抗が小さいので、正荷電性トナーの場合にはトナー粒子の抵抗が下がって階調性が低下し、トナー消費量の増大を引き起こす問題があり、負荷電性トナーの場合には帯電性の上昇を招き、画像濃度の低下を引き起こす問題がある。
【００２０】
本発明で使用する１０面体以上の多面体無機微粉末の製造方法の例としては、例えば特開平５−４３２５３号公報に多面体マグネタイト粒子の製造方法について記載がある。また、多面体無機微粉末は抵抗調整、疎水性、帯電性等を改質する目的でシランカップリング剤、チタネートカップリング剤、シリコンオイル、アミノ基を含有したスチレン系樹脂などで表面処理してもよい。
更に、本発明の外添剤として、多面体無機微粉末と一緒に流動性改善などの目的で、あるいはフィルミング防止効果を充分に発揮させる目的で、多面体無機微粉末以外の非磁性粉末を用いることが好ましく、特に酸化珪素、酸化チタン、酸化アルミニウム、酸化亜鉛、酸化マグネシウムの群より１種類以上選択された非磁性粉末を併用するのが好ましい。特に、最近の高画質化に伴いトナー粒子径が小さくなる傾向にあり、多面体無機微粉末と非磁性粉末の併用はトナー粒子径が３〜１２μｍの範囲で有効に作用し、更に好ましくは３〜１０μｍの範囲が好適である。
【００２１】
非磁性粉末のＢＥＴ法比表面積は１０〜５００ｍ２ ／ｇが好ましく、この範囲内だとトナー貯蔵安定性、トナー供給部からのトナー補給性、現像部でのトナー搬送性等に優れている。非表面積が１０ｍ２ ／ｇ未満では十分な流動性改善機能、搬送機能が付与できず、また、５００ｍ２ ／ｇより大きいとトナー粒子同士の隔壁効果が減じるため高温保管時でのトナー凝集、固着を招きやすく、更に有機光導電体等の感光体へのフィルミングを発生しやすいなどの問題がある。
【００２２】
非磁性粉末は表面を公知の処理剤及び処理方法で疎水化処理されていることが好ましく、これにより疎水性機能が付与され環境依存性が改善されるとともに、非磁性粉末同士の凝集が少なくなり、トナーの流動性改善機能が優れたものとなる。表面処理としては少なくともシランカップリング剤がよく、これ以外の処理剤ではトナーの流動性改善機能が劣り好ましくないが、シランカップリング剤と他の処理剤を併用したり、多層に表面処理してもよい。シランカップリング剤としては、例えば、オルガノアルコキシシラン（メトキシトリメチルシラン、ジメトキシジメチルシラン、トリメトキシメチルシラン、エトキシトリメチルシラン等）、オルガノクロルシラン（トリクロルメチルシラン、ジクロルジメチルシラン、クロルトリメチルシラン、トリクロルエチルシラン、ジクロルジエチルシラン、クロルトリエチルシラン、クロルトリフェニルシラン等）、オルガノシラザン（トリエチルシラザン、トリプロピルシラザン、トリフェニルシラザン、ヘキサメチルジシラザン、ヘキサエチルジシラザン、ヘキサフェニルジシラザン等）、オルガノジシラン、オルガノシラン等があり、これらは１種あるいは２種以上の混合物で用いられ、好ましくは、オルガノクロルシラン、オルガノシラザンがよい。
【００２３】
非磁性粉末の添加量は、トナー粒子１００重量部に対して０．０１〜１０重量部が好ましく、更には０．０５〜８重量部が好適である。非磁性粉末が０．０１重量部未満だと流動性改善効果がなく、また１０重量部より多いと遊離した非磁性粉末により感光体にフィルミングが発生したり、二成分系現像剤のキャリアや一成分系現像器内の帯電付与部材に付着したりして帯電機能劣化等の障害を引き起こし好ましくなく、更にまた正荷電性トナーの場合には帯電性の著しい低下を招き、カブリの悪化、トナー飛散量の増大を引き起こす問題があり、負荷電性トナーの場合には帯電性に著しい上昇を招き、画像濃度の低下を引き起こす問題がある。
【００２４】
この他、トナーの外添剤としては多面体無機微粉末以外の導電性チタン、酸化アンチモン、酸化錫、酸化セリウム、硫酸バリウム、チタン酸ストロンチウム、ハイドロタルサイト類化合物、アクリルビーズ、シリコンビーズ、ポリエチレンビーズなどの公知の無機、有機微粉末を適量添加してもよく、好ましくはトナー粒子１００重量部に対して０．００５〜８重量部である。
本発明で使用する外添剤の各試験方法を以下に説明する。
【００２５】
〔多面体無機微粉末表面の面数〕
多面体無機微粉末の表面面数は走査型電子顕微鏡で粒子を拡大して面数を実測すればよい。
〔多面体無機微粉末の粒径〕
多面体無機微粉末の粒径は、例えば走査型電子顕微鏡で１０個以上の粉末の長手方向と短手方向の長さを計り、それぞれを平均して求めればよい。
【００２６】
〔多面体無機微粉末及び非磁性粉末のＢＥＴ法比表面積〕
多面体無機微粉末及び非磁性粉末の非表面積は市販されている窒素吸着ＢＥＴ法比表面積装置を用いて測定することができ、例えば（株）島津製作所製流動式比表面積自動測定装置（フローソープ２３００型）などがある。
また、本発明のトナーはキャリアを使用しない一成分系現像剤（磁性粉を２０％以上含有した磁性トナー、或いは実質的に磁性粉を含有しない非磁性トナー）または二成分系現像剤（スリーブにトナー粒子とキャリア粒子の磁気ブラシを形成する通常の二成分系現像剤、或いはスリーブにトナー粒子のみの穂を形成する新二成分系現像剤）として使用することができるが、二成分系現像剤に用いる場合には、磁性キャリアと混合して用いればよく、現像剤中のキャリアとトナーの含有比は１００：１〜１０重量部が好ましい磁性キャリアとしては、粒子径２０〜２００μｍ程度の鉄粉、フェライト粉、マグネタイト粉、磁性樹脂キャリアなど従来から公知のものが使用できる。またこれら表面に公知のシリコーン系樹脂、アクリル系樹脂、フッ素系樹脂、スチレン系樹脂など、或いはこれらの樹脂の混合物を単層、または多層にコーティングしたものも好適に使用できる。
【００２７】
まず、本発明のトナー製造方法について一例を説明するが、その要旨を越えない限り以下の説明に何等制限されるものではない。
トナー内添剤としては少なくとも樹脂、着色剤を所定量秤量して配合し、混合する。混合装置の一例としては、ダブルコン・ミキサー、Ｖ型ミキサー、ドラム型ミキサー、スーパーミキサー、ヘンシェルミキサー、ナウターミキサー等がある。
【００２８】
次に、混練工程では、バッチ式（例えば加圧ニーダー、バンバリーミキサー等）または連続式の練り機を用いるが、連続生産できる等の優位性から、近年は１軸または２軸押出機が主流であり、例えば神戸製鋼所社製ＫＴＫ型２軸押出機、東芝機械社製ＴＥＭ型２軸押出機、ケイ・シー・ケイ社製２軸押出機、池貝鉄工社製ＰＣＭ型２軸押出機、ブス社製コ・ニーダー等が良い。
混練後、トナーは２本ロール等で圧延され、水冷等で冷却・固化する冷却工程を経る。
【００２９】
次いで、粉砕工程では、クラッシャー、ハンマーミル、フェザーミル等で粗粉砕し、ジェットミル、高速ローター回転式ミル等で細粉砕し、段階的に所定トナー粒度まで粉砕する。
粉砕後、慣性分級方式のエルボジェット、遠心力分級方式のミクロプレックス、ＤＳセパレーター等でトナーを分級し、平均粒子径３〜１２μｍのトナーを得る。分級工程で発生したトナー粗粉は粉砕工程に戻し、また発生した微粉はトナー原料の配合工程に戻して再利用しても良い。
【００３０】
平均粒径が１２μｍより大きいとコピー画質の解像度が劣化し、３μｍ未満だとトナー搬送時トナーが飛散し環境上支障がある。尚、トナー粒子の平均粒径は公知の粒度分布測定装置で測定すればよく、例えばコールター社製コールターカウンター（型式ＴＡ−ＩＩ）などがある。
更に、トナーに外添処理する場合には、分級後のトナーと各種外添剤を所定量配合して、ヘンシェルミキサー、スーパーミキサー等の粉体にせん断力を与える高速攪拌機などで、撹拌・混合するのがよい。この際、外添機内部で発熱があり、凝集物を生成し易くなるので外添機の容器部周囲を水で冷却するなどの手段で温度調整をする方が好ましい。
更に外添トナーは必要に応じて公知の篩別装置、例えば佐藤式振動篩、ジャイロシフター、遠心式スクリーン分級機などで、トナー凝集物、遊離した外添剤等を除去すればよい。
【００３１】
【発明の効果】
本発明の静電荷像現像剤を用いることにより、コピー画質上にコメット、フィルミング等による画像欠陥の発生が少なく、連続使用時でも画像濃度、カブリ、階調性等の画像・画質特性、トナー消費量などが安定して良好であり、耐久性、トナーの貯蔵安定性、トナー補給性・搬送性などのトナー性能に優れ、多大な工業的利益を提供するものである。
【００３２】
【実施例】
以下、実施例により本発明を更に説明するが、本発明はその要旨を超えない限り以下の実施例により何等制限されるものではない。なお、下記実施例中、単に「部」とあるものはいずれも「重量部」を意味するものとする。
【００３３】
【表１】
・スチレン／ｎ−ブチルアクリレート １００部
＝モノマー重量比＝８５／１５の共重合樹脂
（フロー軟化温度１３０℃，ガラス転移温度６０℃）
・着色剤 カーボンブラック ＭＡ１００Ｓ ６部
（三菱化学社製）
・低分子量ポリプロピレン ２．５部
（蒸気圧浸透圧法による数平均分子量＝７０００）
・帯電制御剤 ボントロンＰ５１ ２部
（オリエント化学社製４級アンモニウム塩化合物）
【００３４】
を配合し、連続２軸押出機を用いて混練、粉砕し、分級して平均粒径９μｍ（コールターカウンターＴＡ−ＩＩで測定した体積換算の平均値）の黒色トナーを得た。
また、磁性粉末として下記のものを使用した。
【００３５】
【表２】
ここで、保持力と飽和磁化は市販の直流磁気特性測定装置を用いて５ｋエルステッドの磁場をかけて測定し、電気抵抗は平行電極面積３．１４ｃｍ２ の測定セル内に磁性粉末を入れて上部電極と下部電極にはさみ、上部電極に荷重１ｋｇの錘を乗せ、直流電圧１００Ｖを印加して市販の絶縁抵抗計で抵抗値を測定した。
【００３７】
＜実施例１＞
黒色トナー１００部に対して疎水性シリカＡ（日本アエロジル社製Ｒ−９７２、比表面積＝１１０ｍ２ ／ｇ）０．３５部、マグネタイトＡ ０．２部をスーパーミキサーで外添処理して、外添トナーＡを得た。ついで、外添トナーＡ ４．２部と平均粒径１００μｍのシリコン樹脂でコートしたフェライト粉キャリア１００部とをＶ型混合機で混合、撹拌し、スタート用現像剤Ａを作製した。
次に、この現像剤Ａをスタート用現像剤とし、外添トナーＡを補給用トナーとして有機光導電体を感光体とし、ブレードクリーニング方式で、二成分磁気ブラシの正規現像方式（感光体表面電位；通常モード（Ｎモード）ＤＣ−７００Ｖ、写真モード（Ｐモード）ＤＣ−５００、バイアス電圧；ＤＣ−２００Ｖ）のコピー速度５０枚／分の複写機（シャープ製ＳＦ−９４００の改造機）を用いて、次の耐久性試験、環境性試験、高温貯蔵性試験を行った。
【００３８】
耐久性試験
温度２３〜２５℃、湿度５０〜６０ＲＨ％の通常環境下で３００，０００枚の実写試験を実施した。この試験の結果、３００，０００枚実写中で画像濃度及びカブリが安定して良好であり、中間調再現性に優れ、トナー飛散による機内の汚染もなく良好であった（図１）。
【００３９】
環境性試験
温度３５〜３７℃、湿度８３〜８７ＲＨ％の高温高湿環境下で１００，０００枚の実写試験を実施した。この試験の結果、１００，０００枚実写中でも通常環境下に比較して顕著な差もなく、コピー耐久性、画質安定性に優れ、感光体へのフィルミング、コメットの発生もなかった（図２）。
【００４０】
高温貯蔵性試験
スタート用現像剤と補充用トナーをそれぞれボトルに入れ密閉状態にして、温度４５℃、湿度５０ＲＨ％の環境下で１０日間保管し、冷却した後、これらの現像剤を用いて温度２３〜２５℃、湿度５０〜６０ＲＨ％の通常環境下で５０，０００枚の実写試験を実施した。この試験の結果、５０，０００枚実写中でもコピー白地部汚れであるカブリの増加がなく、画像濃度も安定して高く、トナー飛散による機内汚染もないなど良好であり、高温で長時間さらされた後に使用しても耐久性能、コピー画質安定性に優れた現像剤であった。
【００４１】
＜比較例１＞
実施例１のマグネタイトＡをマグネタイトＢに変更した以外は実施例１と同様に外添トナーＢとスタート現像剤Ｂを作製し、実施例１と同様に耐久性試験、環境性試験、高温貯蔵性試験を行った。
耐久性試験
１００，０００枚過ぎより写真モードの画像濃度が上昇傾向にあり、中間調の再現性が悪化すると共に、トナー消費量が増大する傾向にあった。また、２００，０００枚過ぎからカブリがやや高くなり好ましくなく、３００，０００枚後に複写機内部の現像器底部及び現像器下に位置するコピー紙搬送部の両端にトナー飛散による汚れがあった。更にまた、２００，０００枚過ぎの途中から感光体上にコメット（外添剤の付着と推測される）が発生し、コピー白部に黒い斑点状の画像欠陥が発生した（図３）。
【００４２】
環境性試験
５０，０００枚過ぎより写真モードの画像濃度が上昇傾向にあり、中間調の再現性（階調性）も悪くなり好ましくなかった。また、１００，０００枚後の複写機内部のトナー飛散による汚れも目立った（図４）。
高温貯蔵性試験
実施例１に比しカブリが高めであり、５０，０００枚後の複写機内部のトナー飛散による汚れも多く目立った。
【００４３】
＜比較例２＞
実施例１のマグネタイトＡをマグネタイトＣに変更した以外は実施例１と同様に外添トナーＣとスタート現像剤Ｃを作製し、実施例１と同様に耐久性試験、環境性試験、高温貯蔵性試験を行った。
耐久性試験
実施例１とほぼ同様であった。
【００４４】
環境性試験
５０，０００枚過ぎの途中から感光体上にフィルミングが発生し、コピー画像の文字、細線等のキレが悪化したり、写真などの絵原稿をコピーした画像がややボケるなどの画像欠陥が発生し、問題があった。
高温貯蔵性試験
実施例１とほぼ同様であった。
【００４５】
＜実施例２＞
実施例１のマグネタイトＡの添加量を０．５部に変更した以外は実施例１と同様に外添トナーＤとスタート現像剤Ｄを作製し、実施例１と同様に耐久性試験、環境性試験、高温貯蔵性試験を行った。
耐久性試験
実施例１と同様に良好であった。
【００４６】
環境性試験
実施例１と同様に良好であった。
高温貯蔵性試験
実施例１と同様に良好であった。
実施例１〜２と比較例１〜２の耐久性試験の評価結果を表１に、環境性試験の評価結果を表２に、高温貯蔵性試験の評価結果を表３にそれぞれ示す。
【００４７】
【表３】
【表４】
【表５】
ここで、使用されている語句を以下に簡単に説明する。
画像濃度
コピー黒部をマクベス反射濃度計（サカタインク社製ＲＤ−９１４型）で反射濃度を測定し、画像濃度とした。
カブリ
コピー前とコピー後の通紙のハンター白度を色差計（日本電色工業社製ＺＩＩ−Σ８０型）で測定し、コピー前後のハンター白度差を求めカブリ値とした。
【００５１】
トナー濃度
コピーチェック後に現像器より現像剤をサンプリングし、トナーを除去して重量分析し、現像剤中のトナー濃度を求めた。
トナー帯電量（帯電量と略す）
上記でサンプリングした現像剤を東芝ケミカル社製ブローオフ帯電量測定装置で測定し、トナー濃度で補正して、トナー単位重量当たりの帯電量を求めた。
【図面の簡単な説明】
【図１】実施例１の耐久性試験実写データー
【図２】実施例１の環境性試験実写データー
【図３】比較例１の耐久性試験実写データー
【図４】比較例１の環境性試験実写データー[0001]
[Industrial applications]
The present invention relates to an electrostatic image developer used for developing an electrostatic latent image formed in an electrophotographic method, an electrostatic recording method, or the like.
[0002]
[Prior art]
In a developing process, a developer used in an electronic copying machine or the like is once attached to an image carrier such as a photoconductor on which an electrostatic image is formed, and then transferred from the photoconductor to transfer paper in a transfer process. Then, in a fixing step, the sheet is fixed on the copy paper surface. At this time, as a developer for developing an electrostatic charge image formed on the latent image holding surface, a two-component developer composed of a carrier and a toner and a one-component developer (a magnetic toner, a non- Magnetic toners) are known.
[0003]
As the toner contained in the developer, there are a positively charged toner and a negatively charged toner. Conventionally, a toner such as a nigrosine dye, a quaternary ammonium salt, etc. There are known charge control agents as additives to coatings, coating agents for imparting predetermined chargeability to carriers, and the like, while those providing negative chargeability include charge control agents such as gold-containing azo dyes. And inorganic fine powder, organic fine powder, and a coating agent for a carrier are known.
[0004]
Fine particles of various metal oxides or the like are used for the purpose of improving the fluidity and chargeability of the toner, and for the purpose of imparting conductivity to the toner particles to improve the developability and to provide stable image density and image quality. There has been proposed a method of adding and using powders, and a method of adding and using various magnetic powders for the purpose of removing paper containing powder attached to the photoreceptor and nitrogen-containing compounds generated in the corona charger from the photoreceptor. I have. Specific examples of toner or developer containing toner particles and magnetic powder include JP-A-58-105236, JP-A-58-118652, JP-A-62-258472, and JP-A-Hei. -229266, JP-A-5-146355 and the like.
[0005]
[Problems to be solved by the invention]
However, when copying is repeatedly performed using a conventional toner or developer with a copying machine or the like, the image density is not stable, fog is deteriorated while the copies are superimposed, the gradation is deteriorated, and the toner is deteriorated. There have been problems such as that the consumption amount increases in the middle and that toner scattering which contaminates the inside of the copying machine occurs frequently. Further, when a sufficient amount of magnetic powder is added to toner particles to obtain sufficient developability, the magnetic powder damages a photoreceptor such as an organic photo-semiconductor, and a toner or a separated external part is damaged on a damaged part of the photoreceptor. Embedding of additives causes image defects due to comet-like toner or external additives attached, and also deteriorates the charging performance of the photoconductor by polishing the surface of the photoconductor with an external additive such as magnetic powder. In addition, there have been problems such as the fact that the surface of the photoreceptor is worn in a groove shape, thereby causing streak-like defects in the solid black portion of the copy.
[0006]
Therefore, a first object of the present invention is to provide a developer capable of obtaining a high-image / high-quality copy having excellent image density and fog, excellent gradation, and free from image defects such as stripes, chipping, and comets. Is to provide. A second object of the present invention is to provide a developer having excellent durability performance such as stable image and image quality even when repeatedly copied and printed, less contamination in the apparatus, and stable toner consumption. A third object of the present invention is to provide a developer which is small in changes in image and image quality such as image density and fog even when temperature, humidity and the like change, and has good environment dependency. A fourth object is to provide a developer excellent in storage stability such that the toner does not solidify and the change in image and image quality is small even when stored and stored at a high temperature for a long time.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on such problems, and as a result, have found that the above problems can be solved by setting the number of surfaces of the inorganic fine powder to be added to the toner particles to 10 or more. Reached. That is, the gist of the present invention contains a resin and a colorant. Non-magnetic Toner particles On the
[0008]
[Action]
Hereinafter, the present invention will be described in detail.
As the resin that can be used in the present invention, various known resins suitable for the toner for developing electrostatic images can be used.
Examples of the styrene-based resin (a homopolymer or a copolymer containing styrene or a styrene-substituted product) include, for example, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer Styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer) Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene- Ethyl methacrylate copolymer, styrene-methac Le butyl acrylate copolymer and styrene - phenyl methacrylate copolymer), styrene -α- chloromethyl acrylate copolymers, and styrene - acrylonitrile - there are acrylic acid ester copolymer. Furthermore, a crosslinked binder resin described in JP-B-51-23354 and JP-A-50-44836, or described in JP-B-55-6895 and JP-B-63-32180. Non-crosslinked binder resins can also be used.
[0009]
Any known saturated or unsaturated polyester resin can be used as the polyester resin. The composition is composed of a polyhydric alcohol and a polybasic acid, and if necessary, at least one of the polyhydric alcohol and the polybasic acid is trivalent. It is obtained by polymerizing a monomer composition containing the above-mentioned multifunctional component.
Examples of the epoxy resin include a general-purpose epoxy resin of a polycondensate of bisphenol A and epichlorohydrin, a modified epoxy resin modified with carboxylic acid, phenol, diarylsulfonamide, and the like, and an epoxy resin blended with a phenol resin and an epoxy resin. is there.
[0010]
Other resins include vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin And polycarbonate resin.
Preferred resins for use in the present invention include styrene resins, polyester resins and epoxy resins. The resin is not limited to being used alone, and two or more resins can be used in combination. As the resin used in the present invention, a resin containing a styrene-based resin as a main component (preferably 50% or more) is particularly preferable.
[0011]
The flow softening temperature (Tm) of the resin is preferably about 80 to 150 ° C, more preferably about 90 to 140 ° C. If the temperature is lower than 80 ° C., the fixing temperature to the paper is low and good, but hot offset is apt to occur, and the toner is easily crushed in the developing tank, causing a spent phenomenon in which the toner adheres to the carrier surface and the doctor blade. In addition, there is a problem that the charging characteristics are deteriorated and the durability of the developer is deteriorated. On the other hand, if the temperature is higher than 150 ° C., there are problems that the fixing temperature to the paper is high and the toner pulverizability is poor.
[0012]
The glass transition temperature of the resin is preferably about 45 ° C. or higher. If the temperature is lower than 45 ° C., if the toner is left at a high temperature of 40 ° C. for a long period of time, the storage stability is poor such that the toner is hardly aggregated or fixed. Easily forms toner agglomerates, adheres to the screen and side walls of the sieving apparatus, and easily forms agglomerates. Furthermore, when the toner is used for a long time in the developing device, the bearings and spikes in the developing device are regulated. There is a problem in use such as sticking to a part such as a plate.
The resin may be produced by a known production method.For example, in the case of a styrene-based resin, it may be carried out by solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, or the like. The polymerization method may be different.
Each test method of the resin used in the present invention will be described below.
[0013]
[Flow softening temperature (Tm)]
In a flow tester (CFT-500 manufactured by Shimadzu Corporation), 1 g of a sample was measured under the conditions of a nozzle of 1 mm × 10 mm, a load of 30 kg, a preheating time of 50 ° C. for 5 minutes, and a heating rate of 3 ° C./min. Then, the temperature at the midpoint of the distance from the start to the end of the flow is defined as the flow softening temperature (Tm).
[0014]
[Glass transition temperature (Tg)]
In a differential thermal analyzer (DTA-40, manufactured by Shimadzu Corporation), a tangent line was drawn at the transition (inflection) start point of the curve measured at a heating rate of 10 ° C./min, and the temperature at the intersection was determined by the glass transition. Temperature (Tg).
The colorant used in the present invention is not particularly limited as long as it is conventionally used, and any suitable pigment or dye can be used. For example, titanium oxide, zinc white, alumina white, calcium carbonate, navy blue, magnetite, carbon black, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine-based pigment, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane-based Dyes, anthraquinone dyes, monoazo and disazo pigments and the like are used alone or in combination with a colorant for a desired toner color. The content of the colorant may be an amount sufficient to color the toner so that a visible image can be formed by development, and is preferably, for example, 1 to 20 parts by weight based on 100 parts by weight of the resin. .
[0015]
In addition, if necessary, a small amount of an auxiliary agent may be added for the purpose of improving the thermal characteristics, physical characteristics, release characteristics, etc. of the toner. For example, polyalkylene wax, paraffin wax, higher fatty acid, fatty acid amide, metal Soap and the like can be used. The addition amount is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the toner particles.
In addition, known positively or negatively chargeable charge control agents can be used alone or in combination for the purpose of adjusting the chargeability of the toner. In the case of a positively chargeable toner, a known charge control agent such as a nigrosine dye, a quaternary ammonium salt, a triaminotriphenylmethane compound or an imidazole compound, and in the case of a negatively chargeable toner, a gold-containing azo dye or saltyl An appropriate amount of a known charge control agent such as an acid metal complex, an alkylsalicylic acid metal complex, and a curlics arene compound may be added. The addition amount is preferably about 0.05 to 10 parts by weight based on 100 parts by weight of the resin.
[0016]
As the external additive to be mixed with the toner particles in the present invention, a polyhedral inorganic fine powder having at least 10 or more, preferably 12 or more, more preferably 14 to 30 surfaces is used. When an inorganic fine powder having less than 10 surfaces, for example, a magnetic powder such as a needle-like, hexahedral, or octahedral, is used, the surface of the photoreceptor is greatly damaged, and the toner or the external additive is buried in the streak-like uneven defects or recesses. Comet-like defects are likely to occur, and image defects such as copying and printing are likely to occur, which is not preferable. On the other hand, a rounded shape having no corners does not exhibit an effect of preventing filming (a phenomenon in which a fine powder such as a toner component such as wax or an external additive adheres to a photoreceptor).
[0017]
Further, the particle diameter of the polyhedral inorganic fine powder is preferably 2 μm or less, and more preferably 1 μm or less. If it is larger than 2 μm, the photoreceptor has a high polishing property and is damaged, so that it is difficult to obtain a copy having a stable image and image quality.
Furthermore, the BET specific surface area of the polyhedral inorganic fine powder is 2 m 2 / G or more, preferably 3 m 2 / G or more is preferred. Specific surface area is 2m 2 / G is not preferable because it has the same problem as when the particle size is larger than 2 μm.
[0018]
Examples of the polyhedral inorganic fine powder used in the present invention include iron oxide, chromium oxide, calcium titanate, strontium titanate, barium titanate, magnesium titanate, cerium oxide, zirconium oxide, aluminum oxide, titanium oxide, zinc oxide, and the like. Yes, these may be used alone or as a mixture. As the polyhedral inorganic fine powder of the present invention, a polyhedral magnetic powder can be suitably used.
[0019]
The structure of the magnetic powder is represented by the general formula (MO) (Fe 2 O 3 )), Wherein M represents a divalent metal such as Cu, Zn, Fe, Mg, Mn, and Ni, and may be used alone or in combination of two or more. It is preferable that M contains at least Fe from the viewpoint of the toner resistance adjustment providing function and the like.
The mixing amount of the polyhedral inorganic fine powder is preferably from 0.05 to 10 parts by weight, more preferably from 0.1 to 1 part by weight, per 100 parts by weight of the toner particles. If the amount is too small, there is no polishing effect of the toner attached to the photoconductor, and if the amount is too large, the photoconductor is damaged. Furthermore, when the polyhedral magnetic powder is used, since the resistance of the powder is small, in the case of a positively charged toner, the resistance of the toner particles is reduced, the gradation is reduced, and the toner consumption is increased. In the case of a negatively chargeable toner, there is a problem that the chargeability is increased and the image density is reduced.
[0020]
As an example of a method for producing a polyhedral inorganic fine powder having 10 or more polyhedrons used in the present invention, a method for producing polyhedral magnetite particles is described in, for example, JP-A-5-43253. In addition, the polyhedral inorganic fine powder may be surface-treated with a silane coupling agent, a titanate coupling agent, a silicone oil, a styrene-based resin containing an amino group, etc. for the purpose of adjusting resistance, modifying hydrophobicity, charging property, etc. Good.
Further, as an external additive of the present invention, a non-magnetic powder other than the polyhedral inorganic fine powder is used for the purpose of improving fluidity together with the polyhedral inorganic fine powder, or for the purpose of sufficiently exhibiting a filming preventing effect. It is particularly preferable to use a non-magnetic powder selected from the group consisting of silicon oxide, titanium oxide, aluminum oxide, zinc oxide and magnesium oxide in combination. In particular, the toner particle size tends to be reduced with the recent improvement in image quality, and the combined use of the polyhedral inorganic fine powder and the non-magnetic powder effectively works when the toner particle size is in the range of 3 to 12 μm, and more preferably 3 to 12 μm. A range of 10 μm is preferred.
[0021]
BET specific surface area of nonmagnetic powder is 10 to 500 m 2 / G is preferable, and within this range, the toner storage stability, the toner replenishment from the toner supply unit, the toner transportability in the development unit, and the like are excellent. Non-surface area is 10m 2 / G cannot provide a sufficient fluidity improving function and a conveying function. 2 If the ratio is larger than / g, the partition wall effect between toner particles is reduced, so that toner aggregation and fixation during high-temperature storage are liable to occur, and further, filming to a photoconductor such as an organic photoconductor tends to occur.
[0022]
The surface of the non-magnetic powder is preferably subjected to a hydrophobic treatment using a known treatment agent and a known treatment method, whereby the hydrophobic function is imparted to improve the environment dependency, and the aggregation of the non-magnetic powder is reduced. Thus, the toner fluidity improving function is excellent. As a surface treatment, at least a silane coupling agent is preferable, and other treatment agents are not preferable because the fluidity improving function of the toner is inferior. However, a silane coupling agent and another treatment agent are used in combination, or a multi-layer surface treatment is performed. Is also good. Examples of the silane coupling agent include organoalkoxysilanes (methoxytrimethylsilane, dimethoxydimethylsilane, trimethoxymethylsilane, ethoxytrimethylsilane, etc.), and organochlorosilanes (trichloromethylsilane, dichlorodimethylsilane, chlorotrimethylsilane, trichloro) Ethylsilane, dichlorodiethylsilane, chlorotriethylsilane, chlorotriphenylsilane, etc.), organosilazane (triethylsilazane, tripropylsilazane, triphenylsilazane, hexamethyldisilazane, hexaethyldisilazane, hexaphenyldisilazane, etc.), There are organodisilane, organosilane, and the like, and these are used alone or in a mixture of two or more. Preferably, organochlorosilane, organosilaza Good.
[0023]
The addition amount of the nonmagnetic powder is preferably 0.01 to 10 parts by weight, and more preferably 0.05 to 8 parts by weight, based on 100 parts by weight of the toner particles. When the amount of the non-magnetic powder is less than 0.01 part by weight, there is no fluidity improving effect. When the amount is more than 10 parts by weight, filming occurs on the photoreceptor due to the released non-magnetic powder, or the carrier of the two-component developer or It is not preferable because it adheres to a charging member in a one-component developing device and causes obstacles such as deterioration of a charging function. In addition, in the case of a positively chargeable toner, a remarkable decrease in chargeability is caused. There is a problem that the scattering amount is increased, and in the case of the negatively charged toner, there is a problem that the chargeability is significantly increased and the image density is reduced.
[0024]
In addition, as an external additive of the toner, conductive titanium, antimony oxide, tin oxide, cerium oxide, barium sulfate, strontium titanate, hydrotalcite compounds, acrylic beads, silicon beads, polyethylene beads other than the polyhedral inorganic fine powder are used. An appropriate amount of a known inorganic or organic fine powder such as an inorganic fine powder may be added, and preferably 0.005 to 8 parts by weight based on 100 parts by weight of the toner particles.
Each test method of the external additive used in the present invention will be described below.
[0025]
(Number of polyhedral inorganic fine powder surfaces)
The number of surfaces of the polyhedral inorganic fine powder may be measured by enlarging the particles with a scanning electron microscope.
(Particle size of polyhedral inorganic fine powder)
The particle size of the polyhedral inorganic fine powder may be determined, for example, by measuring the lengths of 10 or more powders in the longitudinal direction and the transverse direction with a scanning electron microscope, and averaging the respective lengths.
[0026]
[BET specific surface area of polyhedral inorganic fine powder and nonmagnetic powder]
The non-surface area of the polyhedral inorganic fine powder and the non-magnetic powder can be measured using a commercially available nitrogen adsorption BET method specific surface area apparatus. For example, a flow-type specific surface area automatic measuring apparatus (Flow Soap 2300, manufactured by Shimadzu Corporation) Type).
Further, the toner of the present invention is a one-component developer (magnetic toner containing 20% or more of magnetic powder, or a non-magnetic toner substantially containing no magnetic powder) without using a carrier, or a two-component developer (for a sleeve). Can be used as a normal two-component developer that forms a magnetic brush of toner particles and carrier particles, or a new two-component developer that forms ears of only toner particles on a sleeve). In the case where the magnetic carrier is used, the carrier may be mixed with a magnetic carrier, and the content ratio of the carrier and the toner in the developer is preferably 100: 1 to 10 parts by weight. Conventionally known materials such as ferrite powder, magnetite powder and magnetic resin carrier can be used. In addition, a known silicone resin, acrylic resin, fluorine resin, styrene resin, or the like, or a mixture of these resins coated in a single layer or a multi-layer can be suitably used.
[0027]
First, an example of the toner manufacturing method of the present invention will be described. However, the present invention is not limited to the following description without departing from the gist thereof.
As the toner internal additive, at least a predetermined amount of a resin and a colorant are weighed, blended, and mixed. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauta mixer and the like.
[0028]
Next, in the kneading process, a batch-type (for example, a pressure kneader, a Banbury mixer, etc.) or a continuous-type kneader is used. However, in recent years, a single-screw or twin-screw extruder is mainly used due to its superiority such as continuous production. Yes, for example, KTK type twin screw extruder manufactured by Kobe Steel, TEM twin screw extruder manufactured by Toshiba Machine Co., Ltd., twin screw extruder manufactured by KCK Co., Ltd., PCM type twin screw extruder manufactured by Ikegai Iron Works, Bus Co-kneader manufactured by Sharp is good.
After kneading, the toner is rolled by two rolls or the like, and undergoes a cooling step of cooling and solidifying by water cooling or the like.
[0029]
Next, in the pulverizing step, coarse pulverization is performed by a crusher, a hammer mill, a feather mill, or the like, finely pulverized by a jet mill, a high-speed rotor rotary mill, or the like, and pulverized to a predetermined toner particle size in a stepwise manner.
After the pulverization, the toner is classified using an inertial classification type elbow jet, a centrifugal force classification type microplex, a DS separator, or the like to obtain a toner having an average particle diameter of 3 to 12 μm. The coarse toner powder generated in the classification step may be returned to the pulverization step, and the generated fine powder may be returned to the toner raw material mixing step for reuse.
[0030]
If the average particle size is larger than 12 μm, the resolution of the copy image quality is degraded. Incidentally, the average particle size of the toner particles may be measured by a known particle size distribution analyzer, for example, a Coulter counter (model TA-II) manufactured by Coulter Corporation.
Further, when externally adding to the toner, a predetermined amount of the classified toner and various external additives are blended, and the mixture is stirred and mixed by a high-speed stirrer that applies a shear force to the powder such as a Henschel mixer or a super mixer. Good to do. At this time, since heat is generated inside the external additive device and aggregates are easily generated, it is preferable to adjust the temperature by means such as cooling the periphery of the container portion of the external additive device with water.
Further, the externally added toner may be removed by a known sieving apparatus such as a Sato type vibrating sieve, a gyro shifter, a centrifugal screen classifier or the like, if necessary, to remove toner aggregates, liberated external additives, and the like.
[0031]
【The invention's effect】
By using the electrostatic image developer of the present invention, the occurrence of image defects due to comet, filming, etc. on the copy image quality is small, and the image / image quality characteristics such as image density, fog, gradation, etc. The toner consumption is stable and good, and the toner performance such as durability, toner storage stability, toner replenishment and transportability is excellent, and a great industrial benefit is provided.
[0032]
【Example】
Hereinafter, the present invention will be further described with reference to examples. However, the present invention is not limited by the following examples unless it exceeds the gist thereof. In addition, in the following examples, all simply referred to as "parts" mean "parts by weight".
[0033]
[Table 1]
・ Styrene / n-
= Copolymer resin with monomer weight ratio = 85/15
(Flow softening temperature 130 ° C,
・ Colorant carbon black MA100S 6 parts
(Mitsubishi Chemical Corporation)
・ 2.5 parts of low molecular weight polypropylene
(Number average molecular weight by vapor pressure osmometry = 7000)
・ Charge control agent Bontron P51 2 parts
(Quaternary ammonium salt compound manufactured by Orient Chemical Co., Ltd.)
[0034]
Was kneaded, pulverized and classified using a continuous twin-screw extruder to obtain a black toner having an average particle size of 9 μm (average value in terms of volume measured by a Coulter Counter TA-II).
The following were used as the magnetic powder.
[0035]
[Table 2]
Here, the coercive force and the saturation magnetization were measured by applying a magnetic field of 5 kOersted using a commercially available DC magnetic property measuring apparatus, and the electric resistance was 3.14 cm in the parallel electrode area. 2 Was placed between the upper and lower electrodes, a weight having a load of 1 kg was placed on the upper electrode, a DC voltage of 100 V was applied, and the resistance was measured with a commercially available insulation resistance meter.
[0037]
<Example 1>
Hydrophobic silica A (R-972 manufactured by Nippon Aerosil Co., Ltd., specific surface area = 110 m) is applied to 100 parts of black toner. 2 / G) 0.35 parts of magnetite A and 0.2 parts of magnetite A were externally added using a supermixer to obtain externally added toner A. Next, 4.2 parts of the externally added toner A and 100 parts of a ferrite powder carrier coated with a silicon resin having an average particle diameter of 100 μm were mixed and stirred by a V-type mixer to prepare a developer A for start.
Next, the developer A is used as a starting developer, the externally added toner A is used as a replenishing toner, the organic photoconductor is used as a photoconductor, and a blade cleaning system is used for a regular development system using a two-component magnetic brush (photoconductor surface potential). Using a copying machine (modification of SF-9400 manufactured by Sharp) with a copy speed of 50 sheets / min in normal mode (N mode) DC-700V, photo mode (P mode) DC-500, bias voltage: DC-200V). The following durability test, environmental test, and high-temperature storage test were performed.
[0038]
Durability test
Under a normal environment of a temperature of 23 to 25 ° C. and a humidity of 50 to 60 RH%, 300,000 actual photographing tests were performed. As a result of this test, the image density and fog were stable and good in actual copying of 300,000 sheets, the halftone reproducibility was excellent, and the inside of the apparatus due to toner scattering was good (FIG. 1).
[0039]
Environmental testing
A real-photo test of 100,000 sheets was conducted in a high-temperature, high-humidity environment with a temperature of 35 to 37 ° C and a humidity of 83 to 87 RH%. As a result of this test, there was no remarkable difference even in actual copying of 100,000 sheets as compared with the normal environment, excellent copy durability and image quality stability, and no occurrence of filming or comet on the photoreceptor (FIG. 2). ).
[0040]
High temperature storage test
The starting developer and the replenishing toner are put into bottles, respectively, and are sealed, stored for 10 days in an environment of a temperature of 45 ° C. and a humidity of 50 RH%, cooled, and then cooled to a temperature of 23 to 25 ° C. using these developers. The actual photographing test of 50,000 sheets was carried out under a normal environment with a humidity of 50 to 60% RH. As a result of this test, even if the 50,000 sheets were actually photographed, there was no increase in fog, which is a stain on the copy white background, the image density was stable and high, and there was no contamination inside the apparatus due to toner scattering. The developer was excellent in durability performance and copy image stability even when used later.
[0041]
<Comparative Example 1>
An external toner B and a start developer B were prepared in the same manner as in Example 1 except that magnetite A in Example 1 was changed to magnetite B, and a durability test, an environmental test, and a high-temperature storage property were performed in the same manner as in Example 1. The test was performed.
Durability test
After 100,000 sheets, the image density in the photographic mode tends to increase, the reproducibility of halftones deteriorates, and the toner consumption tends to increase. Further, fogging became slightly high after 200,000 sheets, which was not preferable. After 300,000 sheets, dirt due to toner scattering was found on the bottom of the developing device inside the copying machine and at both ends of the copy paper transporting portion located below the developing device. Furthermore, a comet (presumed to be an external additive attached) occurred on the photoreceptor in the middle of 200,000 sheets, and a black spot-like image defect occurred on the white portion of the copy (FIG. 3).
[0042]
Environmental testing
After 50,000 sheets, the image density in the photographic mode tends to increase, and the halftone reproducibility (gradation) deteriorates, which is not preferable. In addition, dirt due to toner scattering inside the copying machine after 100,000 copies was also noticeable (FIG. 4).
High temperature storage test
The fogging was higher than that of Example 1, and many stains due to scattering of toner inside the copying machine after 50,000 sheets were noticeable.
[0043]
<Comparative Example 2>
An external toner C and a start developer C were prepared in the same manner as in Example 1 except that magnetite A in Example 1 was changed to magnetite C, and a durability test, an environmental test, and a high-temperature storage property were performed in the same manner as in Example 1. The test was performed.
Durability test
It was almost the same as Example 1.
[0044]
Environmental testing
Filming occurs on the photoreceptor in the middle of 50,000 sheets, and image defects such as deterioration of characters such as characters and thin lines of a copied image and blurring of an image obtained by copying a picture manuscript such as a photograph may occur. Occurred and had a problem.
High temperature storage test
It was almost the same as Example 1.
[0045]
<Example 2>
An external toner D and a start developer D were prepared in the same manner as in Example 1 except that the addition amount of magnetite A in Example 1 was changed to 0.5 part, and a durability test and environmental properties were performed in the same manner as in Example 1. A test and a high-temperature storage test were performed.
Durability test
It was good as in Example 1.
[0046]
Environmental testing
It was good as in Example 1.
High temperature storage test
It was good as in Example 1.
Table 1 shows the evaluation results of the durability tests of Examples 1 and 2 and Comparative Examples 1 and 2, Table 2 shows the evaluation results of the environmental test, and Table 3 shows the evaluation results of the high-temperature storage test.
[0047]
[Table 3]
[Table 4]
[Table 5]
Here, the terms used are briefly described below.
Image density
The reflection density of the copy black portion was measured with a Macbeth reflection densitometer (RD-914, manufactured by Sakata Ink Co., Ltd.) to obtain the image density.
Fog
The hunter whiteness of the paper passing before and after copying was measured with a color difference meter (ZII- # 80, manufactured by Nippon Denshoku Industries Co., Ltd.), and the difference in hunter whiteness before and after copying was determined as a fog value.
[0051]
Toner density
After the copy check, the developer was sampled from the developing device, the toner was removed, and weight analysis was performed to determine the toner concentration in the developer.
Toner charge amount (abbreviated as charge amount)
The developer sampled as described above was measured with a blow-off charge amount measuring device manufactured by Toshiba Chemical Company, and corrected with the toner concentration to determine the charge amount per unit weight of the toner.
[Brief description of the drawings]
FIG. 1 is a photograph of actual durability test data of Example 1.
FIG. 2 shows actual test data of an environmental test in Example 1.
FIG. 3 is a photograph of actual durability test data of Comparative Example 1.
FIG. 4 is an actual environmental test data of Comparative Example 1.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8418795A JP3598570B2 (en) | 1995-04-10 | 1995-04-10 | Electrostatic image developer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8418795A JP3598570B2 (en) | 1995-04-10 | 1995-04-10 | Electrostatic image developer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08278655A JPH08278655A (en) | 1996-10-22 |
| JP3598570B2 true JP3598570B2 (en) | 2004-12-08 |
Family
ID=13823479
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8418795A Expired - Fee Related JP3598570B2 (en) | 1995-04-10 | 1995-04-10 | Electrostatic image developer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3598570B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006301305A (en) * | 2005-04-20 | 2006-11-02 | Kyocera Mita Corp | Toner for developing electrostatic image and image forming method for same |
| JP5180455B2 (en) * | 2006-10-02 | 2013-04-10 | 三井金属鉱業株式会社 | Magnetite particle powder |
-
1995
- 1995-04-10 JP JP8418795A patent/JP3598570B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08278655A (en) | 1996-10-22 |
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