JP4140197B2 - Toner for developing electrostatic latent image and image forming method using the same - Google Patents

Description

【０２１０】
【化２】

【０２１１】
上記化合物の添加量は、トナー全体に対し１〜３０質量％、好ましくは２〜２０質量％、さらに好ましくは３〜１５質量％である。
【０２１２】
本発明のトナーでは、ミニエマルジョン重合法により樹脂粒子中に上記離型剤を内包させ、着色粒子とともに塩析、融着させて調製することが好ましい。
【０２１３】
〈トナー粒子〉
本発明のトナーの粒径は、個数平均粒径で２〜１０μｍであることが好ましく、更に好ましくは３〜８μｍとされる。この粒径は、トナーの製造方法において、凝集剤（塩析剤）の濃度や有機溶媒の添加量、融着時間、重合体の組成によって制御することができる。
【０２１４】
個数平均粒径が３〜１０μｍであることにより、定着工程において、飛翔して加熱部材に付着しオフセットを発生させる付着力の大きいトナー微粒子が少なくなり、また、転写効率が高くなってハーフトーンの画質が向上し、細線やドット等の画質が向上する。
【０２１５】
トナーの個数平均粒径は、コールターカウンターＴＡ−II、コールターマルチサイザー、ＳＬＡＤ１１００（島津製作所社製レーザー回折式粒径測定装置）等を用いて測定することができる。
【０２１６】
本発明においては、コールターマルチサイザーを用い、粒度分布を出力するインターフェース（日科機社製）、パーソナルコンピューターを接続して使用した。前記コールターマルチサイザーにおけるアパーチャーとしては、１００μｍのものを用いて、２μｍ以上（例えば２〜４０μｍ）のトナーの体積分布を測定して粒度分布および平均粒径を算出した。
【０２１７】
トナー粒子の好ましい形状係数の範囲
本発明のトナーの形状係数は、下記式により示されるものであり、トナー粒子の丸さの度合いを示す。
【０２１８】
形状係数＝（（最大径／２）２×π）／投影面積
ここに、最大径とは、トナー粒子の平面上への投影像を２本の平行線ではさんだとき、その平行線の間隔が最大となる粒子の幅をいう。また、投影面積とは、トナー粒子の平面上への投影像の面積をいう。本発明では、この形状係数は、走査型電子顕微鏡により２０００倍にトナー粒子を拡大した写真を撮影し、ついでこの写真に基づいて「ＳＣＡＮＮＩＮＧ ＩＭＡＧＥ ＡＮＡＬＹＺＥＲ」（日本電子社製）を使用して写真画像の解析を行うことにより測定した。この際、１００個のトナー粒子を使用して本発明の形状係数を上記算出式にて測定したものである。
【０２１９】
本発明のトナーとしては、トナー粒子の粒径をＤ（μｍ）とするとき、自然対数ｌｎＤを横軸にとり、この横軸を０．２３間隔で複数の階級に分けた個数基準の粒度分布を示すヒストグラムにおいて、最頻階級に含まれるトナー粒子の相対度数（ｍ１）と、前記最頻階級の次に頻度の高い階級に含まれるトナー粒子の相対度数（ｍ２）との和（Ｍ）が７０％以上であるトナーであることが好ましい。
【０２２０】
相対度数（ｍ１）と相対度数（ｍ２）との和（Ｍ）が７０％以上であることにより、トナー粒子の粒度分布の分散が狭くなるので、当該トナーを画像形成工程に用いることにより選択現像の発生を確実に抑制することができる。
【０２２１】
本発明において、前記の個数基準の粒度分布を示すヒストグラムは、自然対数ｌｎＤ（Ｄ：個々のトナー粒子の粒径）を０．２３間隔で複数の階級（０〜０．２３：０．２３〜０．４６：０．４６〜０．６９：０．６９〜０．９２：０．９２〜１．１５：１．１５〜１．３８：１．３８〜１．６１：１．６１〜１．８４：１．８４〜２．０７：２．０７〜２．３０：２．３０〜２．５３：２．５３〜２．７６・・・）に分けた個数基準の粒度分布を示すヒストグラムであり、このヒストグラムは、下記の条件に従って、コールターマルチサイザーにより測定されたサンプルの粒径データを、Ｉ／Ｏユニットを介してコンピュータに転送し、当該コンピュータにおいて、粒度分布分析プログラムにより作成されたものである。
【０２２２】
〔測定条件〕
１：アパーチャー：１００μｍ
２：サンプル調製法：電解液〔ＩＳＯＴＯＮ Ｒ−１１（コールターサイエンティフィックジャパン社製）〕５０〜１００ｍｌに界面活性剤（中性洗剤）を適量加えて撹拌し、これに測定試料１０〜２０ｍｇを加える。この系を超音波分散機にて１分間分散処理することにより調製する。
【０２２３】
トナー粒子については、形状係数の変動係数が１６％以下であり、個数粒度分布における個数変動係数が２７％以下であるトナー粒子から構成されるトナーを使用することで、トナー表面における外添剤の存在状が均一になり、帯電量分布がシャープになるとともに高い流動性が得られる。その結果、現像性、細線再現性に優れ、安定したクリーニング性を長期にわたって形成することができる。
【０２２４】
さらに本発明者等は、個々のトナー粒子の微小な形状に着目して検討を行った結果、現像装置内部において、トナー粒子の角部分の形状が変化して丸くなり、その部分が外添剤の埋没を促進させ、帯電量の変化、流動性、クリーニング性を低下させていることが判明した。
【０２２５】
又、摩擦帯電によってトナー粒子に電荷を付与する場合には、特に角部分では外添剤が埋没しやすくなり、トナー粒子の帯電が不均一になりやすいと推定される。
【０２２６】
即ち、角がないトナー粒子の割合を５０個数％以上とし、個数粒度分布における個数変動係数を２７％以下に制御されたトナー粒子から構成されるトナーを使用することによっても、現像性、細線再現性に優れ、高画質な画像を長期にわたって形成することができることを見出した。
【０２２７】
角がないトナー粒子とは、トナー粒子の長径をＬ、Ｌ／１０を半径Ｒとする円で、トナー粒子周囲線に対し１点で内側に接しつつ内側を転がした場合に、円がトナーの外側に実質的にはみ出さないトナー粒子という。実質的にはみ出さない場合とは、円がはみ出す突起が存在する箇所が１箇所以下のことを言う。
【０２２８】
さらに、トナーを特定の形状としてその形状を揃えた場合にも、外添剤の埋没が発生せず、且つ帯電量分布がシャープとなることが判明した。
【０２２９】
すなわち、形状係数が１．２〜１．６の範囲にあるトナー粒子の割合が６５個数％以上であり、形状係数の変動係数が１６％以下であるトナーを使用することでも、現像性、細線再現性に優れ、高画質な画像を長期にわたって形成することができる。
【０２３０】
〈現像剤〉
本発明のトナーは、一成分現像剤でも二成分現像剤として用いてもよい。
【０２３１】
一成分現像剤として用いる場合は、非磁性一成分現像剤、あるいはトナー中に０．１〜０．５μｍ程度の磁性粒子を含有させ磁性一成分現像剤としたものがあげられ、いずれも使用することができる。
【０２３２】
また、キャリアと混合して二成分現像剤として用いることができる。この場合は、キャリアの磁性粒子として、鉄、フェライト、マグネタイト等の金属、それらの金属とアルミニウム、鉛等の金属との合金等の従来から公知の材料を用いることが出来る。特にフェライト粒子が好ましい。上記磁性粒子は、その体積平均粒径としては１５〜１００μｍ、より好ましくは２５〜８０μｍのものがよい。
【０２３３】
キャリアの体積平均粒径の測定は、代表的には湿式分散機を備えたレーザ回折式粒度分布測定装置「ヘロス（ＨＥＬＯＳ）」（シンパティック（ＳＹＭＰＡＴＥＣ）社製）により測定することができる。
【０２３４】
キャリアは、磁性粒子が更に樹脂により被覆されているもの、あるいは樹脂中に磁性粒子を分散させたいわゆる樹脂分散型キャリアが好ましい。コーティング用の樹脂組成としては、特に限定は無いが、例えば、オレフィン系樹脂、スチレン系樹脂、スチレン−アクリル系樹脂、シリコーン系樹脂、エステル系樹脂或いはフッ素含有重合体系樹脂等が用いられる。また、樹脂分散型キャリアを構成するための樹脂としては、特に限定されず公知のものを使用することができ、例えば、スチレン−アクリル系樹脂、ポリエステル樹脂、フッ素系樹脂、フェノール樹脂等を使用することができる。
【０２３５】
〈画像形成方法〉
次に、本発明の画像形成装置について説明する。
【０２３６】
図１は本発明の画像形成装置の一例を示す断面構成図である。４は潜像形成体である感光体ドラムであり、アルミニウム製のドラム基体の外周面に感光体層である有機光導電体（ＯＰＣ）を形成してなるもので矢印方向に所定の速度で回転する。
【０２３７】
図１において、図示しない原稿読み取り装置にて読み取った情報に基づき、半導体レーザ光源１から露光光が発せられる。これをポリゴンミラー２により、図１の紙面と垂直方向に振り分け、画像の歪みを補正するｆθレンズ３を介して、感光体面上に照射され静電潜像を作る。感光体ドラム４は、あらかじめ帯電器５により一様帯電され、像露光のタイミングにあわせて時計方向に回転を開始している。
【０２３８】
感光体ドラム面上の静電潜像は、現像器６により現像され、形成されたトナー像はタイミングを合わせて搬送されてきた転写材（転写紙）８に転写器７の作用により転写される。さらに感光体ドラム４と転写紙８は分離器（分離極）９により分離されるが、現像像は転写紙８に転写担持されて、定着器１０へと導かれ定着される。
【０２３９】
感光体面に残留した未転写のトナー等は、クリーニングブレード方式のクリーニング器１１にて清掃され、帯電前露光（ＰＣＬ）１２にて残留電荷を除き、次の画像形成のため再び帯電器５により、一様帯電される。
【０２４０】
トナーリサイクルシステム
トナーリサイクルを行うための方式としては特に限定されるものでは無いが、例えば、クリーニング部で回収されたトナーを搬送コンベアあるいは搬送スクリューによって補給用トナーホッパー、現像器あるいは補給用トナーと中間室によって混合して現像器へ供給する方法等をあげることができる。
【０２４１】
次に図２に於いて、トナーのリサイクル部材斜視構成図の一例を挙げる。この方式は現像器へリサイクルトナーを直接戻す方式である。
【０２４２】
クリーニングブレード１３で回収された未転写トナーはトナークリーニング器１１内の搬送スクリューによってトナーリサイクルパイプ１４に集められ、更にこのリサイクルパイプの受け口１５から現像器６に戻され、再び現像剤として使用される。
【０２４３】
図２は又、本発明の画像形成装置に着脱自在のプロセスカートリッジの斜視図でもある。この図２では斜視構造を判りやすくするため感光体ユニットと現像剤ユニットを分離した図面になっているが、これを全部一体化したユニットとして着脱自在に画像形成装置に搭載できる。この場合、感光体、現像器、クリーニング器及びリサイクル部材が一体となりプロセスカートリッジを構成している。
【０２４４】
又、上記画像形成装置は、感光体ドラムと、帯電器、現像器、クリーニング器あるいはリサイクル部材等の少なくとも一つを含むプロセスカートリッジを搭載する形態にすることもできる。
【０２４５】
次に、転写紙は代表的には普通紙であるが、現像後の未定着像を転写可能なものなら、特に限定されず、ＯＨＰ用のＰＥＴベース等も無論含まれる。
【０２４６】
又、クリーニングブレード１３は、厚さ１〜３０ｍｍ程度のゴム状弾性体を用い、材質としてはウレタンゴムが最も良く用いられる。これは感光体に圧接して用いられるため熱を伝え易く、本発明においては解除機構を設け、画像形成動作を行っていない時には感光体から離しておくのが望ましい。
【０２４７】
本発明は、電子写真法による画像形成装置、特にコンピュータ等からのデジタル画像データで変調した変調ビームにより感光体上に静電潜像を形成する装置に使用することもできる。
【０２４８】
この画像形成方法及び装置に採用されるコンピュータまたは複写原稿からのデジタル画像信号により光変調する走査光学系として、レーザ光学系に音響光学変調器を介在させ、当該音響光学変調器により光変調する装置、半導体レーザを用い、レーザ強度を直接変調する装置があり、これらの走査光学系から一様に帯電した感光体上にスポット露光してドット状の画像を形成する。
【０２４９】
前述の走査光学系から照射されるビームは、裾が左右に広がった正規分布状に近似した丸状や楕円状の輝度分布となり、例えばレーザビームの場合、通常、感光体上で主走査方向あるいは副走査方向の一方あるいは両者が２０〜１００μｍという極めて狭い丸状あるいは楕円状である。
【０２５０】
定着器
本発明のトナーは、上記した如くトナー像が形成された転写材（画像支持体、転写紙）を、定着器（定着装置）を構成する加熱ローラーと加圧ローラーとの間に通過させて定着する工程を含む画像形成方法に好適に使用される。
【０２５１】
図３は、本発明のトナーを用いた画像形成方法において使用する定着器の一例を示す断面図であり、図３に示す定着装置は、加熱ローラー２０と、これに当接する加圧ローラー２１とを備えている。なお、図３において、Ｔは転写紙上に形成されたトナー像である。
【０２５２】
加熱ローラー２０は、フッ素樹脂または弾性体からなる被覆層２２が芯金２３の表面に形成されてなり、線状ヒーターよりなる加熱部材２４を内包している。
【０２５３】
芯金２３は、金属から構成され、その内径は１０〜７０ｍｍとされる。芯金を構成する金属としては特に限定されるものではないが、例えば鉄、アルミニウム、銅等の金属あるいはこれらの合金を挙げることができる。
【０２５４】
芯金２３の肉厚は０．１〜１５ｍｍとされ、省エネルギーの要請（薄肉化）と、強度（構成材料に依存）とのバランスを考慮して決定される。例えば、０．５７ｍｍの鉄よりなる芯金と同等の強度を、アルミニウムよりなる芯金で保持するためには、その肉厚を０．８ｍｍとする必要がある。
【０２５５】
被覆層２２を構成するフッ素樹脂としては、ＰＴＦＥ（ポリテトラフルオロエチレン）およびＰＦＡ（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）などを例示することができる。
【０２５６】
また、被覆層２２を構成する弾性体としては、ＬＴＶ、ＲＴＶ、ＨＴＶなどの耐熱性の良好なシリコーンゴムおよびシリコーンスポンジゴムなどを用いることが好ましい。
【０２５７】
被覆層２２を構成する弾性体のアスカーＣ硬度は、８０°未満とされ、好ましくは６０°未満とされる。
【０２５８】
加圧ローラー２１は、弾性体からなる被覆層２５が芯金２６の表面に形成されてなる。被覆層２５を構成する弾性体としては特に限定されるものではなく、ウレタンゴム、シリコーンゴムなどの各種軟質ゴムおよびスポンジゴムを挙げることができ、また、被覆層を構成するものとしてシリコーンゴムおよびシリコーンスポンジゴムを用いることが好ましい。
【０２５９】
被覆層２５を構成する弾性体のアスカーＣ硬度は、８０°未満とされ、好ましくは７０°未満、更に好ましくは６０°未満とされる。
【０２６０】
また、被覆層２５の厚みは０．１〜３０ｍｍとされ、好ましくは０．１〜２０ｍｍとされる。
【０２６１】
芯金２６を構成する材料としては特に限定されるものではないが、アルミニウム、鉄、銅などの金属またはそれらの合金を挙げることができる。
【０２６２】
加熱ローラー２０と加圧ローラー２１との当接荷重（総荷重）としては、通常４０〜３５０Ｎとされ、好ましくは５０〜３００Ｎ、さらに好ましくは５０〜２５０Ｎとされる。この当接荷重は、加熱ローラー２０の強度（芯金２３の肉厚）を考慮して規定され、例えば０．３ｍｍの鉄よりなる芯金を有する加熱ローラーにあっては、２５０Ｎ以下とすることが好ましい。
【０２６３】
また、耐オフセット性および定着性の観点から、ニップ幅としては４〜１０ｍｍであることが好ましく、当該ニップの面圧は０．６×１０５〜１．５×１０５Ｐａであることが好ましい。
【０２６４】
図３に示した定着器による定着条件の一例を示せば、定着温度（加熱ローラーの表面温度）が１５０〜２１０℃とされ、定着線速が８０〜６４０ｍｍ／ｓｅｃとされる。
【０２６５】
本発明において使用する定着器には、必要に応じてクリーニング機構を付与してもよい。この場合には、シリコーンオイルを定着部の上ローラー（加熱ローラー）に供給する方式として、シリコーンオイルを含浸したパッド、ローラー、ウェッブ等で供給し、クリーニングする方法が使用できる。
【０２６６】
シリコーンオイルとしては耐熱性の高いものが使用され、ポリジメチルシリコーン、ポリフェニルメチルシリコーン、ポリジフェニルシリコーン等が使用される。粘度の低いものは使用時に流出量が大きくなることから、２０℃における粘度が１〜１００Ｐａ・ｓのものが好適に使用される。
【０２６７】
シリコーンオイルの供給量をＡ４用紙１枚当たり２ｍｇ以下とすることにより、定着後の転写紙（画像支持体）に対するシリコーンオイルの付着量が少なくなり、転写紙へ付着したシリコーンオイルによるボールペン等の油性ペンの記入しずらさがなく、加筆性が損なわれることはない。
【０２６８】
また、シリコーンオイルの変質による耐オフセット性の経時的な低下、シリコーンオイルによる光学系や帯電極の汚染などの問題を回避することができる。
【０２６９】
【実施例】
次に本発明の構成と効果を実施例として示すが、無論本発明の態様はこれに限定されるものではない。尚、文中「部」とは「質量部」を表す。
【０２７０】
〈疎水性シリカの調製例〉
疎水性シリカａ１
一次粒子径０．００７μｍのヒュームドシリカ１００質量部を高速ミキサーを有する容器に入れ、窒素雰囲気中で回転数８５００ｒｐｍで撹拌しながら、ジメチルジクロロシラン２０質量部を噴霧し、更に５分間撹拌を続けた後、得られたパウダーリキッドを窒素気流下で２００℃で３時間還流撹拌を行なった。その後常温まで冷却し、粉末の疎水性シリカａ１を得た。
【０２７１】
疎水性シリカａ２
疎水性シリカａ１の調製例において、一次粒子径０．００７μｍのヒュームドシリカの代わりに一次粒子径０．０１２μｍのヒュームドシリカを、ジメチルジクロロシランの代わりにオクチルトリメトキシシランを使用した以外は、疎水性シリカａ１と同様にして疎水性シリカａ２を得た。
【０２７２】
疎水性シリカａ３
疎水性シリカａ１の調製例において、一次粒子径０．００７μｍのヒュームドシリカの代わりに一次粒子径０．０１６μｍのヒュームドシリカを使用した以外は、疎水性シリカａ１と同様にして疎水性シリカａ３を得た。
【０２７３】
疎水性シリカｂ１
疎水性シリカａ１の調製例において、一次粒子径０．００７μｍのヒュームドシリカの代わりに一次粒子径０．０３３μｍのヒュームドシリカを、ジメチルジクロロシランの代わりにオクチルトリメトキシシランを使用した以外は、疎水性シリカａ１と同様にして疎水性シリカｂ１を得た。
【０２７４】
疎水性シリカｂ２
疎水性シリカａ１の調製例において、一次粒子径０．００７μｍのヒュームドシリカの代わりに一次粒子径０．０３０μｍのヒュームドシリカを、ジメチルジクロロシランの代わりにヘキサメチルジシラザンを使用した以外は、疎水性シリカａ１と同様にして疎水性シリカｂ２を得た。
【０２７５】
疎水性シリカｂ３
疎水性シリカａ１の調製例において一次粒子径０．００７μｍのヒュームドシリカの代わりに一次粒子径０．０７０μｍのヒュームドシリカをジメチルジクロロシランの代わりにジメチルシリコーンオイルを使用した以外は、疎水性シリカａ１と同様にして疎水性シリカｂ３を得た。
【０２７６】
〈疎水性酸化チタンの調製例〉
疎水性酸化チタンｃ１
マグネチックスターラーとトラップとを備えた丸底フラスコで１１０℃、２４時間乾燥された５部の酸化チタン（個数平均粒径０．０３０μｍのアナターゼ型酸化チタン）に、１５０部の脱水トルエンと１．５部のノルマルブチルトリメトキシシランを加え、更に緩衝剤として酢酸を０．５部を加えた。
【０２７７】
得られた懸濁液を５０〜６０℃で７時間還流させ、室温に冷却し、その後、吸引濾過した。続いて濾物をトルエンで洗浄し、１１０℃で４時間乾燥を行なった。その後、吸引濾過し、今度はエタノールで吸引濾過し、１１０℃で４時間乾燥し、メノー乳鉢で粉砕し、白色粉末状物質を得た。得られた白色粉末状物質を疎水性酸化チタンｃ１とする。
【０２７８】
疎水性酸化チタンｃ２
酸化チタンｃ１の製造において、個数平均粒径０．０３０μｍのアナターゼ型酸化チタンの代わりに個数平均粒径０．０２１μｍの酸化チタン（ルチル、アナターゼ比率１０：９０）を、ノルマルブチルトリメトキシシランの代わりにイソブチルトリメトキシシランを使用した以外は同様にして疎水性酸化チタンｃ２を得た。
【０２７９】
疎水性酸化チタンｃ３
酸化チタンｃ１の製造において、個数平均粒径０．０３０μｍのアナターゼ型酸化チタンの代わりに個数平均粒径０．０４５μｍのルチル型酸化チタンを、ノルマルブチルトリメトキシシランの代わりにデシルシランを使用した以外は同様にして疎水性酸化チタンｃ３を得た。
【０２８０】
疎水性酸化チタンｄ１
酸化チタンｃ１の製造において、個数平均粒径０．０３０μｍのアナターゼ型酸化チタンの代わりに個数平均粒径０．０９２μｍの酸化チタン（ルチル、アナターゼ比率６０：４０）を、ノルマルブチルトリメトキシシランの代わりにオクチルトリメトキシシランを使用した以外は同様にして疎水性大粒径酸化チタンｄ１を得た。
【０２８１】
疎水性酸化チタンｄ２
酸化チタンｃ１の製造において、個数平均粒径０．０３０μｍのアナターゼ型酸化チタンの代わりに個数平均粒径０．１１２μｍのルチル型酸化チタンを、ノルマルブチルトリメトキシシランの代わりにヘキシルトリメトキシシランを使用した以外は同様にして疎水性大粒径酸化チタンｄ２を得た。
【０２８２】
疎水性酸化チタンｄ３
酸化チタンｃ１の製造において、個数平均粒径０．０３０μｍのアナターゼ型酸化チタンの代わりに個数平均粒径０．４０９μｍのルチル型酸化チタンを、ノルマルブチルトリメトキシシランの代わりにデシルシランを使用した以外は同様にして疎水性大粒径酸化チタンｄ３を得た。
【０２８３】
疎水性シリカａ１〜ａ３，ｂ１〜ｂ３，疎水性チタンｃ１〜ｃ３，ｄ１〜ｄ３の物性値を下記表１に示す。
【０２８４】
【表１】

【０２８５】
〈複合樹脂粒子の調製〉
ラテックス（１ＨＭＬ）
（１）核粒子の調製（第１段重合）
撹拌装置、温度センサー、冷却管、窒素導入装置を取り付けた５０００ｍｌのセパラブルフラスコに、アニオン系界面活性剤（ドデシルスルフォン酸ナトリウム：ＳＤＳ）７．０８ｇをイオン交換水３０１０ｇに溶解させた界面活性剤溶液（水系媒体）を仕込み、窒素気流下２３０ｒｐｍの撹拌速度で撹拌しながら、内温を８０℃に昇温させた。
【０２８６】
この界面活性剤溶液に、重合開始剤（過硫酸カリウム：ＫＰＳ）９．２ｇをイオン交換水２００ｇに溶解させた開始剤溶液を添加し、温度を７５℃とした後、スチレン７０．１ｇ、ｎ−ブチルアクリレート１９．９ｇ、メタクリル酸１０．９ｇからなる単量体混合液を１時間かけて滴下し、この系を７５℃にて２時間にわたり加熱、撹拌することにより重合（第１段重合）を行い、ラテックス（高分子量樹脂からなる樹脂粒子の分散液）を調製した。これを「ラテックス（１Ｈ）」とする。
【０２８７】
（２）中間層の形成（第２段重合）
撹拌装置を取り付けたフラスコ内において、スチレン１０５．６ｇ、ｎ−ブチルアクリレート３０．０ｇ、メタクリル酸６．４ｇ、ｎ−オクチル−３−メルカプトプロピオン酸エステル５．６ｇからなる単量体混合液に、前記式１９）で表される化合物（以下、「例示化合物（１９）」という。また、他の番号の化合物も同様な表記をする）７２．０ｇを添加し、８０℃に加温し溶解させて単量体溶液を調製した。
【０２８８】
一方、アニオン系界面活性剤（ＳＤＳ）１．６ｇをイオン交換水２７００ｍｌに溶解させた界面活性剤溶液を８０℃に加熱し、この界面活性剤溶液に、核粒子の分散液である前記ラテックス（１Ｈ）を固形分換算で２８ｇ添加した後、循環経路を有する機械式分散機「クレアミックス（ＣＬＥＡＲＭＩＸ）」（エム−テクニック社製）により、前記例示化合物（１９）の単量体溶液を混合分散させ、均一な分散粒子径（２８４ｎｍ）を有する乳化粒子（油滴）を含む分散液（乳化液）を調製した。
【０２８９】
次いで、この分散液（乳化液）に、重合開始剤（ＫＰＳ）５．１ｇをイオン交換水２４０ｍｌに溶解させた開始剤溶液と、イオン交換水７５０ｍｌとを添加し、この系を８０℃にて３時間にわたり加熱撹拌することにより重合（第２段重合）を行い、ラテックス（高分子量樹脂からなる樹脂粒子の表面が中間分子量樹脂により被覆された構造の複合樹脂粒子の分散液）を得た。これを「ラテックス（１ＨＭ）」とする。
【０２９０】
（３）外層の形成（第３段重合）
上記のようにして得られたラテックス（１ＨＭ）に、重合開始剤（ＫＰＳ）７．４ｇをイオン交換水２００ｍｌに溶解させた開始剤溶液を添加し、８０℃の温度条件下に、スチレン３００ｇ、ｎ−ブチルアクリレート９５ｇ、メタクリル酸１５．３ｇ、ｎ−オクチル−３−メルカプトプロピオン酸エステル１０．４ｇからなる単量体混合液を１時間かけて滴下した。滴下終了後、２時間にわたり加熱撹拌することにより重合（第３段重合）を行った後、２８℃まで冷却しラテックス（高分子量樹脂からなる中心部と、中間分子量樹脂からなる中間層と、低分子量樹脂からなる外層とを有し、前記中間層に例示化合物（１９）が含有されている複合樹脂粒子の分散液）を得た。このラテックスを「ラテックス（１ＨＭＬ）」とする。
【０２９１】
このラテックス（１ＨＭＬ）を構成する複合樹脂粒子は、１３８，０００、８０，０００および１３，０００にピーク分子量を有するものであり、また、この複合樹脂粒子の個数平均粒径は１０２ｎｍであった。
【０２９２】
ラテックス（２ＨＬ）
（１）核粒子の調製（第１段重合）
撹拌装置を取り付けたフラスコ内において、スチレン１０５．６ｇ、ｎ−ブチルアクリレート３０．０ｇ、メタクリル酸６．４ｇからなる単量体混合液に、例示化合物（１６）７２．０ｇを添加し、８０℃に加温し溶解させて単量体溶液を調製した。
【０２９３】
一方、アニオン系界面活性剤（ＳＤＳ）１．６ｇをイオン交換水２７００ｍｌに溶解させた界面活性剤溶液を８０℃に加熱し、この界面活性剤溶液に、循環経路を有する機械式分散機「クレアミックス（ＣＬＥＡＲＭＩＸ）」（エム−テクニック社製）により、上記例示化合物（１６）の単量体溶液を混合分散させ、均一な分散粒子径（２６８ｎｍ）を有する乳化粒子（油滴）を含む分散液（乳化液）を調製した。
【０２９４】
次いで、この分散液（乳化液）に、重合開始剤（ＫＰＳ）５．１ｇをイオン交換水２４０ｍｌに溶解させた開始剤溶液と、イオン交換水７５０ｍｌとを添加し、この系を８０℃にて３時間にわたり加熱撹拌することにより重合（第１段重合）を行い、ラテックス（高分子量樹脂からなる樹脂粒子の分散液）を調製した。これを「ラテックス（２Ｈ）」とする。
【０２９５】
（２）外層の形成（第２段重合）
上記のようにして得られたラテックス（２Ｈ）に、重合開始剤（ＫＰＳ）１４．８ｇをイオン交換水４００ｍｌに溶解させた開始剤溶液を添加し、８０℃の温度条件下に、スチレン６００ｇ、ｎ−ブチルアクリレート１９０ｇ、メタクリル酸３０．０ｇ、ｎ−オクチル−３−メルカプトプロピオン酸エステル２０．８ｇからなる単量体混合液を１時間かけて滴下した。
【０２９６】
滴下終了後、２時間にわたり加熱撹拌することにより重合（第２段重合）を行った後、２８℃まで冷却しラテックス（高分子量樹脂からなる中心部と、低分子量樹脂からなる外層とを有し、前記中心部に例示化合物（１６）が含有されている複合樹脂粒子の分散液）を得た。このラテックスを「ラテックス（２ＨＬ）」とする。
【０２９７】
このラテックス（２ＨＬ）を構成する複合樹脂粒子は、１６８，０００および１１，０００にピーク分子量を有するものであり、また、この複合樹脂粒子の重量平均粒径は１２６ｎｍであった。
【０２９８】
〈着色粒子１〜４の製造〉
ｎ−ドデシル硫酸ナトリウム５９．０ｇをイオン交換水１６００ｍｌに撹拌溶解した。この溶液を撹拌しながら、カーボンブラック「リーガル３３０」（キャボット社製）４２０．０ｇを徐々に添加し、次いで、「クレアミックス」（エム−テクニック社製）を用いて分散処理することにより、着色剤粒子の分散液（以下、「着色剤分散液」という。）を調製した。この着色剤分散液における着色剤粒子の粒子径を、電気泳動光散乱光度計「ＥＬＳ−８００」（大塚電子社製）を用いて測定したところ、重量平均粒子径で９８ｎｍであった。
【０２９９】
複合樹脂粒子１の調製で得られたラテックス（１ＨＭＬ）４２０．７ｇ（固形分換算）と、イオン交換水９００ｇと、着色剤分散液１６６ｇとを、温度センサー、冷却管、窒素導入装置、撹拌装置、粒径および形状のモニタリング装置を取り付けた２段の撹拌翼を有する反応容器（翼の交差角αは２５°）に入れ撹拌した。内温を３０℃に調整した後、この溶液に５モル／リットルの水酸化ナトリウム水溶液を加えてｐＨを１１．０に調整した。
【０３００】
次いで、塩化マグネシウム６水和物１２．１ｇをイオン交換水１０００ｍｌに溶解した水溶液を、撹拌下、３０℃にて１０分間かけて添加した。３分間放置した後に昇温を開始し、この系を６〜１０分間かけて９０±３℃まで昇温した（昇温速度：１０℃／分）。その状態で、測定器（コールターカウンターＴＡ−II：コールター社製）にて会合粒子の粒径を測定し、体積平均粒径が５．５μｍになった時点で、塩化ナトリウム８０．４ｇをイオン交換水１０００ｍｌに溶解した水溶液を添加して粒子成長を停止させ、さらに、熟成処理として液温度８５±２℃にて０．５〜１５時間にわたり加熱撹拌することにより融着を継続させた。
【０３０１】
その後、８℃／分の条件で３０℃まで冷却し、塩酸を添加してｐＨを２．０に調整し撹拌を停止した。生成した会合粒子をヌッチェを用いて濾過し、イオン交換水で繰り返し洗浄し、その後、フラッシュジェットドライヤーを用いて吸気温度６０℃にて乾燥させ、ついで流動層乾燥機を用いて６０℃の温度で乾燥させ、離型剤として例示化合物（１６）を含有する着色粒子を得た。
【０３０２】
前記塩析／融着段階および形状制御工程のモニタリングにおいて、撹拌回転数、および加熱時間を制御することにより、形状および形状係数の変動係数を制御し、粒径および粒度分布の変動係数を任意に調整して、表２に示す形状特性および粒度分布特性からなる着色粒子１〜４を得た。
【０３０３】
〈着色粒子５〜８の製造〉
ラテックス（１ＨＭＬ）に代えて、複合樹脂粒子の調製で得られたラテックス（２ＨＬ）４２０．７ｇ（固形分換算）を使用し、熟成処理時間を変更したこと以外は着色粒子１〜４の製造と同様にして、表２に示す形状特性および粒度分布特性からなる着色粒子５〜８を得た。
【０３０４】
【表２】

【０３０５】
以上のようにして得られた着色粒子１〜８の各々に、疎水性シリカａ１〜ａ３、ｂ１〜ｂ３、疎水性チタンｃ１〜ｃ３、ｄ１〜ｄ３を表３に示す割合で添加し、１０リットル用ヘンシェルミキサーの回転翼の周速を２４ｍ／ｓに設定し１５分間混合した。なお、これらの着色粒子について、外部添加剤の添加によっては、その形状および粒径は変化しない。
【０３０６】
トナー表面に存在する外添剤粒子の計数結果、ＢＥＴ比表面積、表面存在量（ＥＳＣＡ測定）の結果を表３に示す。
【０３０７】
【表３】

【０３０８】
〈キャリアの製造〉
フェライト芯材の製造
ＭｎＯを２２ｍｏｌ％、Ｆｅ₂Ｏ₃を７８ｍｏｌ％を、湿式ボールミルで２時間粉砕、混合し乾燥させた後に、９００℃で２時間保持することにより仮焼成し、これをボールミルで３時間粉砕しスラリー化した。分散剤及びバインダーを添加し、スプレードライヤーにより造粒、乾燥し、その後１２００℃、３時間本焼成を行い、抵抗４．３×１０⁸Ω・ｃｍのフェライト芯材粒子を得た。
【０３０９】
被覆用樹脂の製造
界面活性剤として炭素数１２のアルキル基を有するベンゼンスルホン酸ナトリウムを用いた水溶液媒体中の濃度を０．３質量％とした乳化重合法により、シクロヘキシルメタクリレート／メチルメタクリレート（共重合比５／５）の共重合体を合成し、体積平均一次粒径０．１μｍ、重量平均分子量（Ｍｗ）２００，０００、数平均分子量（Ｍｎ）９１，０００、Ｍｗ／Ｍｎ＝２．２、軟化点温度（Ｔｓｐ）２３０℃及びガラス転移温度（Ｔｇ）１１０℃の樹脂微粒子を得た。なお、前記樹脂微粒子は、乳化状態において、水と共沸し、残存モノマー量を５１０ｐｐｍとした。
【０３１０】
次に、フェライト芯材粒子１００質量部と、前記樹脂微粒子２質量部とを、撹拌羽根付き高速撹拌混合機に投入し、１２０℃で３０分間撹拌混合して、機械的衝撃力の作用を使用して体積平均粒径６１μｍの樹脂被覆キャリアを得た。
【０３１１】
〈現像剤の製造〉
外部添加剤が添加された着色粒子の各々とキャリアとを混合し、トナー濃度が６質量％の現像剤を調製した。
【０３１２】
表３に示す様に上記手順にて作製された現像剤を実施例１〜１０、参考例１１〜１６および比較例１〜３とした。
【０３１３】
〈感光体の製造〉
感光体Ｐ１の製造
長さ３８０ｍｍ、直径６０ｍｍの円筒状導電性支持体上に下記の塗布液を塗布し感光体Ｐ１を作製した。
〈下引き層〉
チタンキレート化合物（ＴＣ−７５０ 松本製薬製） ３０ｇ
シランカップリング剤（ＫＢＭ−５０３ 信越化学社製） １７ｇ
２−プロパノール １５０ｍｌ
上記塗布液を用いて円筒状導電性支持体上に、膜厚０．５μｍとなるよう塗布した。

を混合し、サンドミルを用いて１０時間分散し、電荷発生層塗布液を調製した。この塗布液を前記下引き層の上に浸漬塗布法で塗布し、膜厚０．２μｍの電荷発生層を形成した。

を混合し、溶解して電荷輸送層塗布液を調製した。この塗布液を前記電荷発生層の上に浸漬塗布法で塗布し、乾燥膜厚２０μｍの電荷輸送層を形成した。
〈保護層〉
メチルトリメトキシシラン １５０ｇ
ジメチルジメトキシシラン ３０ｇ
反応性電荷輸送性化合物 １５ｇ
酸化防止剤 ０．７５ｇ
２−プロパノール ７５ｇ
３％酢酸 ５ｇ
を混合し、樹脂層用の塗布液を調製した。この塗布液を前記電荷輸送層の上に円形量規制型塗布装置により厚さ２μｍの樹脂層を形成し、１２０℃、１時間の加熱硬化を行い、シロキサン樹脂層を形成し、感光体Ｐ１を作製した。
【０３１４】
〈実施例１〜１０、参考例１１〜１６および比較例１〜３〉
トナーリサイクルシステムを搭載した市販のデジタル複写機（コニカ社製：Ｋｏｎｉｃａ Ｓｉｔｉｏｓ７０３０）に感光体（Ｐ１）を搭載した改造機に、高温高湿環境下（温度３３℃、相対湿度８０％）において低画素率（画素率が２％）の画像を連続して１０万枚形成する実写テストを行った後、画像濃度の環境依存性、ハーフトーンの均一性、微細ドットのチリ、スポット状トナー汚れ、かぶりについて評価した。
【０３１５】
なお、トナーリサイクルシステムにおいて高温高湿環境下、低画素率の画像を連続印字する評価法は外添剤埋没が促進されるため下記の項目に対して厳しい条件となる。
【０３１６】
画像濃度の環境依存性
マクベス反射濃度計にてソリッド画像部の最高画像濃度を測定した。高温高湿環境（３３℃、相対湿度８０％）と低温低湿環境（１０℃、相対湿度２０％）の画像濃度の差が０．０５未満を「◎」、０．０５〜０．１未満を「○」、０．１以上を「×」とした。
【０３１７】
ハーフトーンの均一性
ハーフトーンの均一性は目視にて判断し、ハーフトーン画像の均一性を評価した。
【０３１８】
ランクは下記表示として評価した。
ランクＡ：ムラの無い均一な画像
ランクＢ：スジ状の薄いムラが存在する画像
ランクＣ：スジ状の薄いムラが数本存在する画像
ランクＤ：スジ状のはっきりしたムラが数本以上存在する画像
微細ドットのチリ
画像全面に１０％網点画像を形成し、ルーペにてドット周辺のチリを観察した。チリがほとんど検知できないモノを「◎」、微かにチリがあるが、注視しなければ気づかない程度を「○」、チリが容易に検知できるものを「×」とした。
【０３１９】
かぶりの発生状況
マクベス濃度計にて比画像部の白地濃度に対する相対濃度を測定した。
【０３２０】
◎：０．００２未満
○：０．００２〜０．００５未満
×：０．００５を超えるもの
スポット状トナー汚れ
連続１０枚、画像全面に白地画像を形成し、トナー凝集体の飛散による直径０．５μｍ以上の黒点が発生するものを「×」、発生しないものを「○」とした。
【０３２１】
結果を表４に示す。
【０３２２】
【表４】

【０３２３】
表４から明かなごとく、実施例１〜１０は全ての特性に問題がないが、本発明外の比較例１〜３は、各特性に問題が出ることがわかる。
【０３２４】
【発明の効果】
本発明により、▲１▼環境依存性が少なく、▲２▼帯電分布が均一で、微細ドットのチリが少なく鮮鋭な画像が得られる、▲３▼流動性に優れ、過酷な使用条件においてもトナー顆粒、トナー凝集体飛散による画像汚れがない、▲４▼トナー外添剤埋没によるハーフトーン均質性低下が少ない、安定した画像の得られる静電潜像現像用トナーを提供することが出来る。また、トナーリサイクルシステムを組み込んだ画像形成装置に用いても、画像に黒ポチ等の故障が出ず、トナーの流動性低下や帯電性変動のない、従って画像濃度が高く、かぶりのない静電潜像現像用トナー、画像形成方法、画像形成装置及びプロセスカートリッジを提供することが出来る。
【図面の簡単な説明】
【図１】画像形成装置の一例を示す断面構成図。
【図２】画像形成装置に着脱自在のプロセスカートリッジの斜視図。
【図３】定着器の一例を示す断面図。
【符号の説明】
１ 半導体レーザ光源
２ ポリゴンミラー
３ ｆθレンズ
４ 潜像形成体である感光体ドラム
５ 帯電器
６ 現像器
７ 転写器
８ 転写材（画像支持体、転写紙等ともいう）
９ 分離器（分離極）
１０ 定着器
１１ クリーニング器
１３ クリーニングブレード
１４ トナーリサイクルパイプ
１５ リサイクルパイプの受け口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic latent image developing toner used in a copying machine, a printer, and the like, an image forming method using the toner, an image forming apparatus, and a process cartridge.
[0002]
[Prior art]
Conventionally, an image forming method using an electrostatic latent image developing method typified by electrophotography is disclosed in US Pat. Nos. 2,297,691, 2,357,809 and the like. A developing process in which an electrostatic latent image is formed on the surface of the photoreceptor, and the electrostatic latent image is converted into a toner image with a developer containing colored fine powder, and then the toner image is transferred to a recording material such as paper. An image is formed by a transfer process, and a fixing process for fixing the toner image on the recording material by heating or pressurization.
[0003]
In order for a copied image to form a good image quality over a long period of time, it is necessary for the toner to have high fluidity and to maintain stable chargeability. As a technique for improving the fluidity of a toner, it is known to add and mix a fluidizing agent such as silica fine particles to colored particles containing at least a colorant in a binder resin.
[0004]
As described above, the electrostatic latent image is developed in the development process to form a toner image. However, not all the toner that forms the toner image is transferred to the recording material. Part of the toner remains on the surface. Conventionally, this residual toner has been collected and discarded by a cleaning device. However, in recent years, toner collected from the viewpoint of economy and environmental safety is returned to the developing device again by a toner conveying screw, etc. An image forming method that employs a so-called toner recycling system that is used as toner has attracted attention.
[0005]
However, when an image is formed by an image forming method using a toner recycling system using toner containing a fluidizing agent having a small particle size, the toner is excessively compressed by a toner conveying screw or the like. As a result, the fluidizing agent that should be present on the surface of the toner particles is embedded in the toner particles, gradually decreasing the fluidity of the toner and changing the charge amount of the toner, causing toner scattering and fogging. There is also a problem that the image density is lowered.
[0006]
From the above circumstances, in order to suppress the phenomenon that the fluidizing agent of the toner is embedded in the toner particles and the fluidity is lowered, for example, Japanese Patent Laid-Open Nos. 9-211883, 10-104869, and 10- A technique as described in Japanese Patent No. 198063 has been proposed.
[0007]
Japanese Patent Laid-Open No. 2000-298372 discloses a technique in which a large particle size external additive and a small particle size external additive are used in combination and applied to a one-component developer.
[0008]
However, the present situation is that none of the techniques has yet been a sufficient solution to the problem.
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned circumstances, and the object thereof is (1) less environmental dependency, (2) a uniform charge distribution, and a sharp image with less dust of fine dots. (3) Excellent fluidity, free from image contamination due to toner granules and toner scattering even under harsh usage conditions, (4) Statically stable image with little deterioration in halftone homogeneity due to embedded toner additive An object of the present invention is to provide a toner for developing an electrostatic latent image.
[0010]
  In addition, even when used in an image forming apparatus incorporating a toner recycling system, the image does not suffer from black spots or the like, and there is no decrease in toner fluidity or chargeability variation. Therefore, the image density is high and there is no fogging. Latent image developing tonerAndImage formationThe lawIt is to provide.
[0011]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that the object of the present invention can be achieved by adopting any one of the following configurations.
[0012]
  [1] In an electrostatic latent image developing toner comprising at least a binder resin, a colorant, and an external additive,
  The toner is composed of toner particles in which the proportion of toner particles having a shape factor in the range of 1.2 to 1.6 is 65% by number or more, and the variation coefficient of the shape factor is 16% or less.
  65 to 95% by number of external additives existing on the toner surface of 0.005 μm or more and less than 0.025 μm, 4 to 35% by number of 0.025 μm or more and less than 0.080 μm, 0.080 μm or more and 0.500 μm A toner for developing an electrostatic latent image, wherein less than 0.3 to 10% by number.
  [2]  In the electrostatic latent image developing toner comprising at least a binder resin, a colorant, and an external additive,
In the toner, the proportion of toner particles without corners is 50% by number or more, and the number variation coefficient in the number particle size distribution is 27% or less,
65 to 95% by number of external additives existing on the toner surface of 0.005 μm or more and less than 0.025 μm, 4 to 35% by number of 0.025 μm or more and less than 0.080 μm, 0.080 μm or more and 0.500 μm A toner for developing an electrostatic latent image, wherein less than 0.3 to 10% by number.
[0013]
  [2The external additive is composed of silica and titanium oxide [1〕RecordToner for developing electrostatic latent image.
[0014]
  [3] Two types of silica having different number average particle diameters and two kinds of titanium oxides having different number average particle diameters are externally added [1]Or [2]The toner for developing an electrostatic latent image.
[0019]
  [4[1] to [1], wherein the toner is obtained by polymerizing at least a polymerizable monomer in an aqueous medium.3The toner for developing an electrostatic latent image according to any one of the above.
[0020]
  [5It is obtained by agglomerating and fusing at least resin particles in an aqueous medium.4The toner for developing an electrostatic latent image according to any one of the above.
  [6]In a toner for developing an electrostatic latent image comprising at least a binder resin, a colorant, and an external additive obtained by aggregating and fusing at least resin particles in an aqueous medium, the toner has a ratio of toner particles having no corners. Is 50% by number or more, and the number variation coefficient in the number particle size distribution is 27% or less,
65 to 95% by number of external additives existing on the toner surface of 0.005 μm or more and less than 0.025 μm, 4 to 35% by number of 0.025 μm or more and less than 0.080 μm, 0.080 μm or more and 0.500 μm A toner for developing an electrostatic latent image, wherein less than 0.3 to 10% by number.
[0021]
  [7] BET specific surface area of 1.3 to 1.9 m²/ G, the surface abundance of silicon atoms measured by ESCA is 6 to 12 area%, the surface abundance of titanium element is 0.5 to 4 area%, and the abundance of carbon atoms is 50 to 75 area% [1 ] ~ [6The toner for developing an electrostatic latent image according to any one of the above.
[0022]
  [8In the image forming method employing toner recycling, [1] to [7An image forming method using the toner according to any one of the above.
[0025]
The particle diameter of the external additive particles on the toner surface was photographed with a field-effect scanning electron microscope (JSM6400F, acceleration voltage 5 kV, magnification 40,000 times), and the number was counted with an image analyzer.
[0026]
100% of the total number of external additives adhering to the counted toner, those having a particle diameter of 0.005 μm or more and less than 0.025 μm, those having a particle diameter of 0.025 μm or more and less than 0.080 μm, The number% was determined by dividing into particles having a particle size of 080 μm or more and less than 0.500 μm.
[0027]
The external additive attached with a particle size of 0.005 μm or more and less than 0.025 μm is preferably 65 to 95% by number from the viewpoint of obtaining high fluidity and uniform charge amount distribution. Particularly preferred is 70 to 90% by number. If it is less than 65% by number, the fluidity is insufficient, resulting in problems such as poor cleaning and generation of toner granules. On the other hand, if it is more than 95% by number, the external additive tends to be buried during long-term stirring in the developing device or when a toner recycling system is adopted, which tends to cause fogging or poor cleaning due to a decrease in charge amount.
[0028]
The external additive adhering with a particle size of 0.025 μm or more and less than 0.080 μm is a region having both an embedding prevention function and a fluidity imparting function, and needs to be adhered at a ratio of 4 to 35% by number. It is. Particularly preferred is 5 to 20% by number. If it is less than 4% by number, the burying prevention function is insufficient, and if it is more than 35% by number, a part of the external additive is detached from the toner, causing a problem of contaminating a friction charging member such as a carrier or a member such as a photoreceptor.
[0029]
The external additive attached with a particle size of 0.080 μm or more and 0.500 μm has the effect of improving transferability in addition to the burying prevention function, and is attached at a rate of 0.3 to 10% by number. Need to be. Particularly preferred is 0.8 to 5% by number. If it is less than 0.3% by number, the above-mentioned effect does not appear, and if it exceeds 10% by number, a part of the external additive is detached, causing a problem of contaminating a friction charging member such as a carrier or a member such as a photoconductor. .
[0030]
The number% specified value for each particle size category varies, but if the above measurement and calculation are performed for each toner and the number% of each particle size category of the external additive is obtained, the value of the present invention is determined by the value. Whether it is within the regulation is determined centrally, and the total of the number% is 100%.
[0031]
Also, those having a lower value of less than 0.005 μm or more than 0.500 μm, which is the lower limit of the measured value of the entire particle size category, are preferred to have as little as possible because of problems in the properties as an external additive, 0 is desirable.
[0032]
Further, it is preferable that silica and titanium oxide are mixed in the external additive present on the toner surface. If necessary, alumina, tin oxide, iron oxide or the like may be used in combination.
[0033]
Further, it is preferable that two types of silica having different number average particle diameters and two types of titanium oxide having different number average particle diameters are externally added.
[0034]
The two types of silica having different number average particle sizes and the two types of titanium oxides having different number average particle sizes are: a) silica having a number average particle size of 0.005 to 0.015 μm (hereinafter also referred to as small diameter silica), b) Silica having a number average particle diameter of 0.020 to 0.080 μm (hereinafter also referred to as large silica), c) Titanium oxide having a number average particle diameter of 0.015 to 0.070 μm (hereinafter also referred to as small diameter titanium oxide). And d) A titanium oxide having a number average particle diameter of 0.08 to 0.2 μm (hereinafter also referred to as large-diameter titanium oxide) is preferably added externally.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
The components and embodiments of the present invention will be further described.
[0036]
<Method for producing silica core>
The silica used in the present invention is generally produced by a wet method or a dry method, and in particular, a so-called fumed silica produced by a dry method (vapor phase oxidation of a silicon halide compound) is used. It is preferable from the viewpoint of fluidity. This is manufactured by a conventionally known technique. For example, a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame is used, and the basic reaction formula is as follows.
[0037]
SiCl_Four+ 2H₂+ O₂→ SiO₂+ 4HCl
In this production process, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride or titanium chloride together with silicon halogen compounds. Of course, those using them are also included.
[0038]
<Small diameter silica to be used>
a) Silica having a number average particle diameter of 0.005 to 0.015 μm is preferably added in an amount of 0.1 to 0.8 parts by mass with respect to 100 parts by mass of the toner (no external additive added).
[0039]
Examples of commercially available silica fine powder include those marketed under the following trade names. For example, AEROSIL (made by Nippon Aerosil Co., Ltd.) 130, 200, 200V, 200CF, 200FAD, 300, 300CF, 380; Ca-O-Sil (made by CABOT) M-5, MS-7D, MS-75D, H-5 HS-5, EH-5; Wacker HDK N20 (manufactured by WACKER-CHFMIEGMMBH) S13, V15, N20, T30, T40, and the like.
[0040]
Examples of the hydrophobized silica include the following.
There are HDK H 2000, 2000/4, 3004, 2050EP, HVK21 manufactured by Clariant, and R972, R974, RX200, RY200, R202, R805, R812 manufactured by Nippon Aerosil Co., Ltd.
[0041]
<Large diameter silica to be used>
b) It is preferable to add 0.2 to 1.2 parts by mass of silica having a number average particle size of 0.020 to 0.080 μm with respect to 100 parts by mass of toner (without external additives added). More preferably, it is 0.3-0.8 mass part.
[0042]
Examples of commercially available silica fine powder include those marketed under the following trade names. AERSIL (manufactured by Nippon Aerosil Co., Ltd.) OX50, AEROSIL50, TT600, MOX80, MOX170 and the like.
[0043]
Further, examples of the hydrophobized silica include the following.
TS630 (manufactured by Cabot Corporation); NA-50H (manufactured by Kao Corporation); RY-50, NY-50, NAX-50, RX-50, RM-50 (all manufactured by Nippon Aerosil Co., Ltd.) and the like.
[0044]
<Titanium crystal system>
The titanium oxide fine particles used in the present invention include those produced by the sulfuric acid method and the chlorine method, and include a rutile type, anatase type, and amorphous type.
[0045]
Rutile, anatase, mixed crystals of rutile and anatase, amorphous, and mixed types can be used, but from the viewpoint of securing fluidity and reducing the environmental dependency of charging, rutile titanium oxide and anatase titanium oxide Is preferably used in the range of 2:98 to 45:55 by mass ratio. Moreover, it is preferable to coat | cover the particle | grain surface of the said rutile / anatase mixed titanium oxide with the layer containing an element in 1 type, or 2 or more types among aluminum, silicon, titanium, zirconium, and tin. That is, it is preferable to coat the particle surface before the treatment with the silane coupling agent with the layer containing the predetermined element.
[0046]
The reason why the layer is coated before the silane coupling agent treatment is to adjust the chargeability and resistance. The treatment amount of the element is preferably 3 to 20% by mass. If the amount is less than 3% by mass, it is difficult to obtain the effect of adjusting the charge. If the amount exceeds 20% by mass, the particles are not unified, which is not preferable.
[0047]
<Small diameter titanium oxide to be used>
c) It is preferable to add 0.1 to 1.0 part by mass of titanium oxide having a number average particle size of 0.015 to 0.070 μm with respect to 100 parts by mass of toner (without external additives added). More preferably, it is 0.2-0.8 mass part.
[0048]
Specific examples of the titanium oxide fine particles include the following. P-25 (made by Degussa); IT-S, IT-PA, IT-PB (all made by Idemitsu Kosan); R-820, R-830, R-680, CR-50, CR-60, A -100, A-220 (all manufactured by Ishihara Sangyo); MT-100SA, MT-150W, MT-500B, MT-600B (all manufactured by Teika). Examples of the titanium oxide fine particles that have been particularly hydrophobized include the following.
[0049]
STT-30A, STT-30AS, STT-30S (all manufactured by Titanium Industry Co., Ltd.); T-805 (manufactured by Nippon Aerosil Co., Ltd.); TTO-51 (manufactured by Ishihara Sangyo Co., Ltd.); TAF-1500S (manufactured by Fuji Titanium Industry Co., Ltd.) MT-100S and MT-100T (both manufactured by Teika).
[0050]
<Titanium oxide used>
d) It is preferable to add 0.2 to 1.2 parts by mass of the titanium oxide having a number average particle size of 0.08 to 0.2 μm with respect to 100 parts by mass of the toner (no external additive added). More preferably, it is 0.3-1.0 mass part.
[0051]
Examples of commercially available titanium oxide particles include those commercially available under the following trade names. TTO-51 (A) and TTO-51 (B) (both manufactured by Ishihara Sangyo Co., Ltd.); TAF-620 (manufactured by Fuji Titanium Industrial Co., Ltd.).
[0052]
Examples of the titanium oxide fine particles that have been particularly hydrophobized include the following.
[0053]
STT-60J (manufactured by Titanium Industry Co., Ltd.); JA-1, JA-3, JA-4, JA-5 (all manufactured by Teika); TAF-520, TAF-520AS, TAF-520K (all manufactured by Fuji Titanium Industry) Etc.).
[0054]
Preferably used coupling agent
It can be obtained by treating hydrophilic fine particles with a silane coupling agent such as methyltrimethoxysilane, methyltriethoxysilane, or octyltrimethoxysilane.
[0055]
Specific coupling agents are shown below.
CH_Three(CH₂)₂SiCl_Three
CH_Three(CH₂)_FiveSiCl_Three
CH_Three(CH₂)₇SiCl_Three
CH_Three(CH₂)₉SiCl_Three
CH_Three(CH₂)₉Si (OCH_Three)_Three
CH_Three(CH₂)₉Si (CH_Three) Cl₂
CH_Three(CH₂)₂Si (OCH_Three)_Three
CH_Three(CH₂)₂Si (CH_Three) (OCH_Three)₂
CH_Three(CH₂)_FiveSi (OCH_Three)_Three
CH_Three(CH₂)_FiveCONH (CH₂)₂Si (OC₂H_Five)_Three
CH_Three(CH₂)_FourCOO (CH₂)₂Si (OCH_Three)_Three
CH_Three(CH₂)₉Si (OCH_Three)_Three
CH_Three(CH₂)₉Si (CH_Three) (OCH_Three)₂
CH_Three(CH₂)₇SO₂NH (CH₂)_ThreeSi (OC₂H_Five)_Three
CH_Three(CH₂)₈(CH₂)₂Si (OCH_Three)_Three
CF_Three(CH₂)₂SiCl_Three
CF_Three(CF₂)_FiveSiCl_Three
CF_Three(CF₂)_Five(CH₂)₂SiCl_Three
CF_Three(CF₂)₇(CH₂)₂SiCl_Three
CF_Three(CF₂)₇CH₂CH₂Si (OCH_Three)_Three
CF_Three(CF₂)₇(CH₂)₂Si (CH_Three) Cl₂
CF_Three(CH₂)₂Si (OCH_Three)_Three
CF_Three(CH₂)₂Si (CH_Three) (OCH_Three)₂
CF_Three(CF₂)_Three(CH₂)₂Si (OCH_Three)_Three
CF_Three(CF₂)_FiveCONH (CH₂)₂Si (OC₂H_Five)_Three
CF_Three(CF₂)_FourCOO (CH₂)₂Si (OCH_Three)_Three
CF_Three(CF₂)₇(CH₂)₂Si (OCH_Three)_Three
CF_Three(CF₂)₇(CH₂)₂Si (CH_Three) (OCH_Three)₂
CF_Three(CF₂)₇SO₂NH (CH₂)_ThreeSi (OC₂H_Five)_Three
CF_Three(CF₂)₈(CH₂)₂Si (OCH_Three)_Three
Etc. It can also be obtained by polysiloxane treatment.
[0056]
Moreover, the said processing amount is 10-100 mass% with respect to 100 mass% of silica or titanium oxide, Preferably it is the range of 20-70 mass%. When the treatment amount is 10% by mass or less, not only low hydrophobicity can be obtained, but also solid fixation occurs during drying, resulting in poor dispersion. May be large and undesirable.
[0057]
<Lubricant used in combination with external additives>
Examples of the lubricant that can be used as an external additive include metal salts of higher fatty acids.
[0058]
Specific examples of such higher fatty acid metal salts include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, calcium stearate, and other stearic acid metal salts; zinc oleate, manganese oleate, iron oleate, olein Oleic acid metal salts such as acid copper and magnesium oleate; palmitate metal salts such as zinc palmitate, copper palmitate, magnesium palmitate and calcium palmitate; linoleic acid metal salts such as zinc linoleate and calcium linoleate; ricinol Examples include ricinoleic acid metal salts such as zinc acid and calcium ricinoleate.
[0059]
The addition amount of the external additive is preferably about 0.1 to 5% by mass with respect to the toner.
[0060]
<External additive addition process>
This step is a step of adding an external additive to the dried toner particles.
[0061]
Examples of the apparatus used for adding the external additive include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.
[0062]
In the present invention, the surface of the treatment layer treated with the silane coupling agent can be further coated with a coupling agent and / or silicone oil. That is, after the silane coupling agent is treated in an aqueous medium, an organosilicon compound such as a silane coupling agent or silicone oil can be treated in the gas phase in order to improve hydrophobicity and adjust the charge amount.
[0063]
As the silane coupling agent that can be used at this time, in addition to those described above, fluorosilane, aminosilane, polydimethylsiloxane, methylhydrogenpolysiloxane, and the like can be used.
[0064]
When the treatment is performed in the gas phase, the treatment amount is preferably 1 to 20% by mass, particularly preferably 3 to 15% by mass with respect to 100% by mass of the obtained fine powder. When the treatment amount is less than 1% by mass, the effect cannot be obtained, and when it exceeds 20% by mass, the specific surface area becomes low, which is not preferable.
[0065]
<Measuring method of each characteristic>
(1) Specific surface area
It was measured by a BET single point method using an automatic specific surface area measuring apparatus GEMINI 2375 (manufactured by Shimadzu Corporation).
[0066]
The toner of the present invention has a BET specific surface area of 1.3 to 1.9 m.²/ G is preferable. Particularly preferably, 1.4 to 1.8 m²/ G.
[0067]
(2) Degree of hydrophobicity
Add 0.1 g of hydrophobic titanium oxide fine powder to 50 ml of water, add methanol at a rate of 2 ml / min to the water with stirring at a rate of 2 ml / min, and completely wet with the methanol concentration when the fine powder starts to settle. The methanol concentration was determined.
[0068]
From the viewpoint of increasing the environmental dependency of fluidity and charging, the degree of hydrophobicity of silica particles is 30 to 100, particularly preferably 60 to 95.
[0069]
The degree of hydrophobicity of titanium oxide is 20 to 90, particularly preferably 30 to 70.
(3) Surface abundance of silicon atoms
It is preferable that the surface abundance of silicon atoms measured by ESCA is 6 to 12 area%, the surface abundance of titanium element is 0.5 to 4 area%, and the abundance of carbon atoms is 50 to 75 area%.
[0070]
For ESCA measurement, ESCA-1000 manufactured by Shimadzu Corporation was used, and the area ratio occupied by each element was determined from the relative strength ratio of carbon, oxygen, silicon, and titanium atoms.
[0071]
If the BET specific surface area is too small, the fluidity is poor, and if it is too large, the variation in charge amount due to the burying of the external additive tends to increase. In addition, if the surface abundance of silicon atoms measured by ESCA is 6 to 12 area%, the surface abundance of titanium elements is 0.5 to 4 area%, and the abundance of carbon atoms is 50 to 75 area%. It is preferable because it absorbs less moisture under high temperature and high humidity, and the charge amount does not increase at low temperature and low humidity, and a stable image can be obtained.
[0072]
<Cleaning conditions>
Cleaning blade
The cleaning blade used in the present invention is preferably an elastic rubber blade, and its physical properties can control the torque fluctuation of the present invention by controlling the rubber hardness and the rebound resilience at the same time, and the reversal of the blade can be more effectively suppressed. When the JISA hardness of the blade at 25 ± 5 ° C. is smaller than 65, the blade is easily reversed, and when it is larger than 80, the cleaning performance is deteriorated. Further, when the resilience exceeds 80, the blade is easily reversed, and when it is 20 or less, the cleaning performance is deteriorated. More preferable impact resilience is 20 or more and 80 or less. Young's modulus is 294-588 N / cm²The thing of the range of is preferable.
[0073]
Here, both JIS hardness and impact resilience are measured based on the vulcanized rubber physical test method of JIS K6301. In addition, the numerical value of impact resilience indicates%.
[0074]
As the material of the elastic rubber blade used for the cleaning blade, urethane rubber, silicone rubber, fluorine rubber, chloropyrene rubber, butadiene rubber, and the like are known. Of these, urethane rubber is in comparison with other rubbers. It is particularly preferable because of its excellent wear characteristics. For example, urethane rubber obtained by reaction-curing polycaprolactone ester and polyisocyanate described in JP-A-59-30574 is preferable.
[0075]
In the present invention, it is preferable that the elastic rubber blade is fixed to the support member substantially by the support member on the photoreceptor contact surface side. By adopting such a holding method, the torque fluctuation of the cleaning blade can be stabilized.
[0076]
Appropriate pressure contact condition of blade
The proper pressure contact condition of the elastic rubber blade to the surface of the photoreceptor is determined by a delicate balance of various characteristics and is quite narrow. The setting varies depending on characteristics such as the thickness of the elastic rubber blade, and requires precision.
[0077]
However, since elastic rubber blades can vary slightly in their thickness at the time of production, they cannot always be set under the proper conditions. May be out of the proper area. In particular, when combined with an organic photosensitive layer using a high molecular weight binder resin, image defects such as filming and black spots are likely to occur when the film deviates from an appropriate region.
[0078]
Therefore, it is necessary to take measures to cancel the variation in the characteristics of the elastic rubber blade. Even if the thickness of the elastic rubber blade is different, the pressure contact force on the surface of the photoreceptor is not affected. Would be effective.
[0079]
In the present invention, it is preferable that the free end of the elastic rubber blade is pressed in a direction opposite to the rotation direction of the photoreceptor (counter direction).
[0080]
If necessary, the cleaning blade can be sprayed with a fluorine-based lubricant on the edge of the cleaning blade, or further, the following fluorine-based polymer and fluorine-based resin powder can be applied to the tip of the cleaning blade over the entire width. It is preferable to apply a dispersion in which the body is dispersed in a fluorinated solvent.
[0081]
<Photoconductor>
Next, the photoreceptor that can be used in the present invention is not particularly limited, but an organic photoreceptor that is an electrostatic latent image forming body preferably used in the present invention will be described.
[0082]
In the present invention, an organic electrophotographic photoreceptor (organic photoreceptor) is an electrophotographic structure in which an organic compound has at least one of a charge generation function and a charge transport function that are indispensable for the construction of an electrophotographic photoreceptor. It means a photoreceptor, and all known organic electrophotographic photoreceptors such as a photoreceptor composed of a known organic charge generating material or an organic charge transport material, a photoreceptor composed of a polymer complex with a charge generating function and a charge transport function. Can be used.
[0083]
The constitution of the organic photoreceptor used in the present invention is described below.
Conductive support
The conductive support used in the photoreceptor of the present invention may be either a sheet or a cylinder, but a cylindrical conductive support is more preferable for designing an image forming apparatus in a compact manner.
[0084]
The cylindrical conductive support of the present invention means a cylindrical support necessary for forming an endless image by rotating, and the straightness is in the range of 0.1 mm or less and the deflection is 0.1 mm or less. A conductive support is preferred. Exceeding the roundness and shake range makes it difficult to form a good image.
[0085]
As the conductive material, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 103 Ω · cm or less at room temperature.
[0086]
As the conductive support used in the present invention, one having an alumite film that has been sealed on the surface thereof may be used. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing treatment in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / liter, the aluminum ion concentration is 1 to 10 g / liter, the liquid temperature is preferably around 20 ° C., and the applied voltage is preferably about 20 V. It is not limited.
[0087]
The average film thickness of the anodized film is usually 20 μm or less, particularly preferably 10 μm or less.
[0088]
Middle class
In the present invention, an intermediate layer having a barrier function may be provided between the conductive support and the photosensitive layer.
[0089]
In the present invention, in order to improve the adhesion between the conductive support and the photosensitive layer, or to prevent charge injection from the support, an intermediate layer (including an undercoat layer) is provided between the support and the photosensitive layer. Including) can also be provided. Examples of the material for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units.
[0090]
Of these subbing resins, a polyamide resin is preferable as a resin capable of reducing the increase in residual potential due to repeated use. The film thickness of the intermediate layer using these resins is preferably 0.01 to 0.5 μm.
[0091]
The intermediate layer most preferably used in the present invention includes an intermediate layer using a curable metal resin obtained by thermally curing an organic metal compound such as a silane coupling agent or a titanium coupling agent. As for the film thickness of the intermediate | middle layer using curable metal resin, 0.1-2 micrometers is preferable.
[0092]
Photosensitive layer
The photosensitive layer configuration of the photoreceptor of the present invention may be a single layer photosensitive layer configuration in which a charge generation function and a charge transport function are provided on one layer on the intermediate layer. It is preferable that the generation layer (CGL) and the charge transport layer (CTL) be separated. By adopting a configuration in which the functions are separated, an increase in the residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose. In the negatively charged photoconductor, it is preferable to adopt a structure of a charge generation layer (CGL) on the intermediate layer and a charge transport layer (CTL) thereon. In the positively charged photoconductor, the order of the layer configuration is the reverse of that in the negatively charged photoconductor. The most preferred photosensitive layer structure of the present invention is a negatively charged photoreceptor structure having the function separation structure.
[0093]
The structure of the photosensitive layer of the function-separated negatively charged photoreceptor will be described below.
Charge generation layer
The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.
[0094]
A known charge generation material (CGM) can be used as the charge generation material (CGM). For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used. Among these, the CGM that can minimize the increase in residual potential due to repeated use has a three-dimensional and potential structure that can form a stable aggregate structure among a plurality of molecules. Specifically, a phthalocyanine having a specific crystal structure. CGM of pigments and perylene pigments. For example, CGM such as titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ° with respect to Cu-Kα rays and benzimidazole perylene having a maximum peak at 2θ of 12.4 has little deterioration due to repeated use. Potential increase can be reduced.
[0095]
When a binder is used as a CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be further reduced. The thickness of the charge generation layer is preferably 0.01 μm to 2 μm.
[0096]
Charge transport layer
The charge transport layer contains a charge transport material (CTM) and a binder resin that disperses and forms a CTM. Other substances may contain additives such as antioxidants as necessary.
[0097]
A known charge transport material (CTM) can be used as the charge transport material (CTM). For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer. Among these, the CTM capable of minimizing the increase in residual potential due to repeated use has a high mobility and an ionization potential difference from the combined CGM of 0.5 (eV) or less, preferably 0 .25 (eV) or less.
[0098]
The ionization potential of CGM and CTM is measured with a surface analyzer AC-1 (manufactured by Riken Keiki Co., Ltd.).
[0099]
Examples of the resin used for the charge transport layer (CTL) include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, and polycarbonate. Resin, silicone resin, melamine resin, and copolymer resin containing two or more of repeating units of these resins. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used.
[0100]
Most preferred as a binder for these CTLs is a polycarbonate resin. The polycarbonate resin is most preferable in improving the dispersibility and electrophotographic characteristics of CTM. The ratio of the binder resin to the charge transport material is preferably 10 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge transport layer is preferably 10 to 40 μm.
[0101]
Protective layer
Various resin layers can be provided as a protective layer of the photoreceptor. In particular, by providing a cross-linked resin layer, the organic photoreceptor of the present invention having high mechanical strength can be obtained.
[0102]
Examples of the solvent or dispersion medium used for forming the intermediate layer, photosensitive layer, protective layer and the like of the present invention include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, Acetone, methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene , Tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cello Lube, and the like. Although this invention is not limited to these, Dichloromethane, 1, 2- dichloroethane, methyl ethyl ketone, etc. are used preferably. These solvents may be used alone or as a mixed solvent of two or more.
[0103]
Next, as a coating processing method for producing the organic electrophotographic photoreceptor of the present invention, a coating processing method such as dip coating, spray coating, circular amount regulation type coating or the like is used. In order to prevent the lower layer film from being dissolved as much as possible, it is preferable to use a coating method such as spray coating or circular amount regulation type (circular slide hopper type is a typical example) coating in order to achieve uniform coating processing. It is most preferable that the protective layer of the present invention uses the circular amount regulation type coating method. The circular amount regulation type coating is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.
[0104]
Next, the toner used in the present invention will be described.
<Toner production method>
The method for producing the toner of the present invention is not particularly limited. The monomer is emulsion-polymerized or mini-emulsion-polymerized in a suspension polymerization method or in a liquid (in an aqueous medium) to which an emulsion of necessary additives is added. To produce fine resin particles, add the charge controllable resin particles of the present invention, and then add an aggregating agent such as an organic solvent and salts to agglomerate and fuse the resin particles. can do.
[0105]
Suspension polymerization
An example of a method for producing the toner of the present invention is to dissolve a charge control resin in a polymerizable monomer, and add various constituent materials such as a colorant, a release agent as required, and a polymerization initiator. Then, various constituent materials are dissolved or dispersed in the polymerizable monomer using a homogenizer, a sand mill, a sand grinder, an ultrasonic disperser, or the like.
[0106]
The polymerizable monomer in which these various constituent materials are dissolved or dispersed is dispersed in oil droplets of a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer.
[0107]
Then, it transfers to the reaction apparatus (stirring apparatus) with a stirring blade, and a polymerization reaction is advanced by heating. After completion of the reaction, the dispersion stabilizer is removed, filtered, washed, and dried to prepare the toner of the present invention. In the present invention, the “aqueous medium” refers to a medium containing at least 50% by mass of water.
[0108]
Emulsion polymerization method
Examples of the method for producing the toner of the present invention include a method in which resin particles are prepared by salting out, agglomerating, and fusing in an aqueous medium. The method is not particularly limited, and examples thereof include methods disclosed in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904.
[0109]
That is, a method of salting out, agglomerating, and fusing a plurality of fine particles composed of resin particles and a coloring material, or dispersed particles of constituent materials such as resin particles and a coloring agent, particularly using an emulsifier in water After dispersion, a coagulant with a critical coagulation concentration or higher is added for salting out, and at the same time, the formed polymer is heated and fused at a temperature higher than the glass transition temperature of the polymer itself to gradually grow the particle size while forming fused particles. When the target particle size is reached, a large amount of water is added to stop the particle size growth, and the shape is controlled by smoothing the particle surface while heating and stirring, and the particles are kept in a fluid state while containing water. The toner of the present invention can be formed by heating and drying. Here, a solvent that is infinitely soluble in water, such as alcohol, may be added simultaneously with the flocculant.
[0110]
Composite resin particles obtained by multistage polymerization
A toner manufacturing process in which a release agent is contained in a region other than the outermost layer of the composite resin particles mainly includes the following processes.
[0111]
1: Multistage polymerization step (I) for obtaining composite resin particles in which a release agent is contained in a region other than the outermost layer (central portion or intermediate layer)
2: Salting out / fusion process for obtaining toner particles by salting out / fusion of composite resin particles and colorant particles (II)
3: Filtration / washing step of separating the toner particles from the toner particle dispersion and removing the surfactant from the toner particles.
4: a drying process for drying the washed toner particles;
5: Step of adding an external additive to the dried toner particles
Consists of
[0112]
Hereinafter, each step will be described in detail.
[Multistage polymerization step (I)]
The multistage polymerization step (I) is a step of producing composite resin particles by a multistage polymerization method in which a coating layer made of a monomer polymer is formed on the surface of the resin particles.
[0113]
In the present invention, it is preferable to employ a multi-stage polymerization method of three-stage polymerization or more from the viewpoint of production stability and crushing strength of the resulting toner.
[0114]
Hereinafter, the two-stage polymerization method and the three-stage polymerization method, which are representative examples of the multistage polymerization method, will be described.
[0115]
Two-stage polymerization method
The two-stage polymerization method is a method for producing composite resin particles composed of a central portion (core) formed from a high molecular weight resin containing a release agent and an outer layer (shell) formed from a low molecular weight resin. is there.
[0116]
This method will be described in detail. First, a release agent is dissolved in the monomer L to prepare a monomer solution, and this monomer solution is oiled in an aqueous medium (for example, a surfactant aqueous solution). After the dispersion, the system is polymerized (first stage polymerization) to prepare a dispersion of high molecular weight resin particles containing a release agent.
[0117]
Next, a polymerization initiator and a monomer L for obtaining a low molecular weight resin are added to the dispersion of the resin particles, and the monomer L is polymerized in the presence of the resin particles (second stage polymerization). This is a method of forming a coating layer made of a low molecular weight resin (polymer of monomer L) on the surface of the resin particles.
[0118]
Three-stage polymerization method
The three-stage polymerization method produces composite resin particles composed of a central part (core) formed from a high molecular weight resin, an intermediate layer containing a release agent, and an outer layer (shell) formed from a low molecular weight resin. Is the method.
[0119]
This method will be specifically described. First, a dispersion of resin particles obtained by a polymerization process (first-stage polymerization) according to a conventional method is added to an aqueous medium (for example, an aqueous solution of a surfactant). In the aqueous medium, a monomer solution obtained by dissolving a release agent in the monomer M is dispersed in oil droplets, and then this system is polymerized (second stage polymerization) to obtain resin particles ( Dispersion of composite resin particles (high molecular weight resin-intermediate molecular weight resin) by forming a coating layer (intermediate layer) made of a resin (monomer M polymer) containing a release agent on the surface of the core particles) Prepare the solution.
[0120]
Next, a polymerization initiator and a monomer L for obtaining a low molecular weight resin are added to the obtained dispersion of composite resin particles, and the monomer L is polymerized in the presence of the composite resin particles (third By step polymerization), a coating layer made of a low molecular weight resin (polymer of monomer L) is formed on the surface of the composite resin particles. In the above method, the incorporation of the second stage polymerization is preferable because the release agent can be finely and uniformly dispersed.
[0121]
One feature of the toner production method according to the present invention is that the polymerizable monomer is polymerized in an aqueous medium. That is, when forming resin particles (core particles) or coating layer (intermediate layer) containing a release agent, the release agent is dissolved in the monomer, and the resulting monomer solution is oiled in an aqueous medium. It is a method of obtaining latex particles by dispersing in drops and adding a polymerization initiator to this system for polymerization treatment.
[0122]
The aqueous medium as used in the field of this invention means the medium which consists of 50-100 mass% of water and 0-50 mass% of water-soluble organic solvents. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, tetrahydrofuran, and the like, and an alcohol-based organic solvent that does not dissolve the obtained resin is preferable.
[0123]
As a suitable polymerization method for forming resin particles or a coating layer containing a release agent, a release agent is used as a monomer in an aqueous medium in which a surfactant having a concentration equal to or lower than the critical micelle concentration is dissolved. The monomer solution dissolved in is dispersed in oil droplets using mechanical energy to prepare a dispersion, and a water-soluble polymerization initiator is added to the resulting dispersion to cause radical polymerization in the oil droplets. A method (hereinafter referred to as “mini-emulsion method” in the present invention), and the effects of the present invention can be exhibited more preferably. In the above method, an oil-soluble polymerization initiator may be used instead of or together with the water-soluble polymerization initiator.
[0124]
According to the mini-emulsion method that mechanically forms oil droplets, unlike the usual emulsion polymerization method, the release agent dissolved in the oil phase is not detached, and the resin particles or coating layer formed A sufficient amount of the release agent can be introduced.
[0125]
Here, the dispersing machine for dispersing oil droplets by mechanical energy is not particularly limited. For example, a stirring device “CLEARMIX” (M-Technique Co., Ltd.) equipped with a rotor that rotates at high speed. Product), ultrasonic dispersers, mechanical homogenizers, Manton gorin, pressure homogenizers, and the like. The dispersed particle diameter is 10 to 1000 nm, preferably 50 to 1000 nm, and more preferably 30 to 300 nm.
[0126]
In addition, as another polymerization method for forming the resin particles or the coating layer containing the release agent, a known method such as an emulsion polymerization method, a suspension polymerization method, or a seed polymerization method may be employed. These polymerization methods can also be employed to obtain resin particles (core particles) or coating layers constituting the composite resin particles that do not contain a release agent.
[0127]
The particle diameter of the composite resin particles obtained in this polymerization step (I) ranges from 10 to 1000 nm in terms of mass average particle diameter measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.). It is preferable that it exists in.
[0128]
Moreover, it is preferable that the glass transition temperature (Tg) of a composite resin particle exists in the range of 48-74 degreeC, More preferably, it is 52-64 degreeC.
[0129]
The softening point of the composite resin particles is preferably in the range of 95 to 140 ° C.
[Salting out / fusion process (II)]
In the salting out / fusion step (II), the composite resin particles and the colorant particles obtained in the multistage polymerization step (I) are salted out / fused (salting out and fusion occur simultaneously). This is a step of obtaining irregular (non-spherical) toner particles.
[0130]
In the present invention, salting out / fusion means that salting out (aggregation of particles) and fusion (disappearance of the interface between particles) occur simultaneously, or act of causing salting out and fusion at the same time. . In order to perform salting-out and fusion at the same time, it is necessary to agglomerate particles (composite resin particles, colorant particles) under a temperature condition higher than the glass transition temperature (Tg) of the resin constituting the composite resin particles. .
[0131]
In the salting-out / fusion step (II), internal additive particles such as charge control agents (fine particles having a number average primary particle size of about 10 to 1000 nm) are salted out / fused together with the composite resin particles and the colorant particles. You may let them. The colorant particles may be surface-modified, and conventionally known ones can be used as the surface modifier.
[0132]
The colorant particles are subjected to a salting out / fusion process in a state of being dispersed in an aqueous medium. The aqueous medium in which the colorant particles are dispersed is preferably an aqueous solution in which the surfactant is dissolved at a concentration equal to or higher than the critical micelle concentration (CMC).
[0133]
The disperser used for the dispersion treatment of the colorant particles is not particularly limited, but preferably, a stirrer “CLEARMIX” (manufactured by M-Technique) equipped with a rotor that rotates at high speed, an ultrasonic disperser, Examples thereof include a pressure disperser such as a mechanical homogenizer, a manton gourin, and a pressure homogenizer, and a medium disperser such as a Getzman mill and a diamond fine mill.
[0134]
In order to salt out / fuse the composite resin particles and the colorant particles, a salting-out agent (flocculating agent) having a critical aggregation concentration or more is added to the dispersion in which the composite resin particles and the colorant particles are dispersed. In addition, it is necessary to heat the dispersion to a temperature higher than the glass transition temperature (Tg) of the composite resin particles.
[0135]
The temperature range suitable for salting out / fusion is (Tg + 10 ° C.) to (Tg + 50 ° C.), particularly preferably (Tg + 15 ° C.) to (Tg + 40 ° C.). In addition, an organic solvent that is infinitely soluble in water may be added in order to effectively perform fusion.
[0136]
[Filtering and washing process]
In this filtration / washing step, a filtration treatment for filtering the toner particles from the toner particle dispersion obtained in the above step, and a surfactant or salt from the filtered toner particles (cake-like aggregate). A cleaning process for removing deposits such as a depositing agent is performed.
[0137]
Here, the filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.
[0138]
[Drying process]
This step is a step of drying the washed toner particles.
[0139]
Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like.
[0140]
The water content of the dried toner particles is preferably 5% by mass or less, and more preferably 2% by mass or less.
[0141]
In addition, when the toner particles that have been dried are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.
[0142]
The toner of the present invention forms composite resin particles in the absence of a colorant, adds a dispersion of the colorant particles to the dispersion of the composite resin particles, and saltes out the composite resin particles and the colorant particles. It is preferably prepared by fusing.
[0143]
Thus, the polymerization reaction for obtaining the composite resin particles is not inhibited by preparing the composite resin particles in a system in which no colorant is present. Therefore, according to the toner of the present invention, the excellent offset resistance is not impaired, and the fixing device is not contaminated or the image is not stained due to the accumulation of toner.
[0144]
Further, as a result of the polymerization reaction for obtaining the composite resin particles being reliably performed, no monomer or oligomer remains in the obtained toner particles, and the heat fixing step of the image forming method using the toner In this case, no odor is generated.
[0145]
Furthermore, since the surface characteristics of the obtained toner particles are uniform and the charge amount distribution is sharp, an image with excellent sharpness can be formed over a long period of time. According to such a toner having a uniform composition, molecular weight, and surface characteristics between toner particles, in an image forming method including a fixing step by a contact heating method, good adhesion to a transfer material (also referred to as an image support) ( While maintaining a high fixing strength, it is possible to improve the anti-offset property and the anti-rolling property, and an image having an appropriate gloss can be obtained.
[0146]
Next, each component used in the toner manufacturing process will be described in detail.
Polymerizable monomer
Regardless of the method used to prepare the toner, the polymerizable monomer for producing the resin (binder) used in the present invention has a hydrophobic monomer as an essential component, and is optionally crosslinkable. Monomers are used. Moreover, it is desirable to contain at least one monomer having an acidic polar group or a monomer having a basic polar group as described below.
[0147]
(1) Hydrophobic monomer
The hydrophobic monomer constituting the monomer component is not particularly limited, and conventionally known monomers can be used. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled.
[0148]
Specifically, monovinyl aromatic monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers , Halogenated olefin monomers and the like can be used.
[0149]
Examples of vinyl aromatic monomers include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.
[0150]
As acrylic monomers, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate , 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like.
[0151]
Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, and vinyl benzoate.
[0152]
Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.
[0153]
Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene and the like.
[0154]
Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.
[0155]
(2) Crosslinkable monomer
In order to improve the characteristics of the resin particles, a crosslinkable monomer may be added. Examples of the crosslinkable monomer include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.
[0156]
(3) Monomers having acidic polar groups
Examples of the monomer having an acidic polar group include (a) an α, β-ethylenically unsaturated compound having a carboxyl group (—COOH) and (b) a sulfone group (—SOOH)._ThreeMention may be made of α, β-ethylenically unsaturated compounds having H).
[0157]
Examples of the α, β-ethylenically unsaturated compound (a) having a —COOH group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, maleic acid. Examples thereof include acid monooctyl esters, and metal salts thereof such as Na and Zn.
[0158]
-SO of (b)_ThreeExamples of the α, β-ethylenically unsaturated compound having an H group include sulfonated styrene, its Na salt, allylsulfosuccinic acid, octyl allylsulfosuccinate, and its Na salt.
[0159]
(4) Monomers having basic polar groups
As the monomer having a basic polar group, (i) a (meth) acrylic acid ester of an aliphatic alcohol having 1 to 12, preferably 2 to 8, particularly preferably 2, an amine group or a quaternary ammonium group. , (Ii) (meth) acrylic acid amide or (meth) acrylic acid amide mono- or disubstituted optionally with an alkyl group having 1 to 18 carbon atoms on N, (iii) a heterocyclic group having N as a ring member And (iv) N, N-diallyl-alkylamine or a quaternary ammonium salt thereof. Among them, (i) aliphatic alcohol (meth) acrylic acid ester having an amine group or quaternary ammonium group is preferable as a monomer having a basic polar group.
[0160]
Examples of (meth) acrylic acid esters of aliphatic alcohols having an amine group or quaternary ammonium group (i) include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and the above four compounds. A quaternary ammonium salt, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, etc. can be mentioned.
[0161]
(Ii) (Meth) acrylic acid amide or optionally mono- or dialkyl-substituted (meth) acrylic acid amide on N includes acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N-butylmethacrylamide, N, N-dimethylacrylamide, N-octadecylacrylamide and the like can be mentioned.
[0162]
Examples of the vinyl compound substituted with a heterocyclic group having N as a ring member in (iii) include vinylpyridine, vinylpyrrolidone, vinyl-N-methylpyridinium chloride, vinyl-N-ethylpyridinium chloride and the like.
[0163]
Examples of (iv) N, N-diallyl-alkylamine include N, N-diallylmethylammonium chloride and N, N-diallylethylammonium chloride.
[0164]
(Polymerization initiator)
The radical polymerization initiator used in the present invention can be appropriately used as long as it is water-soluble. For example, persulfates (for example, potassium persulfate, ammonium persulfate, etc.), azo compounds (for example, 4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2-amidinopropane) Salt), peroxide compounds and the like. Furthermore, the radical polymerization initiator can be combined with a reducing agent as necessary to form a redox initiator. Use of a redox initiator is preferred because the polymerization activity is increased, the polymerization temperature can be lowered, and the polymerization time can be shortened.
[0165]
The polymerization temperature may be any temperature as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator, but for example, a range of 50 ° C. to 90 ° C. is used. However, it is also possible to polymerize at room temperature or higher by using a polymerization initiator that starts at room temperature, for example, a combination of hydrogen peroxide and a reducing agent (ascorbic acid or the like).
[0166]
(Chain transfer agent)
A known chain transfer agent can be used for the purpose of adjusting the molecular weight. Although it does not specifically limit as a chain transfer agent, For example, the compound which has mercapto groups, such as an octyl mercaptan, a dodecyl mercaptan, a tert- dodecyl mercaptan, is used. In particular, a compound having a mercapto group is preferably used because it suppresses odor during heat-fixing, and a toner having a sharp molecular weight distribution is obtained, and is excellent in storage stability, fixing strength, and offset resistance. For example, ethyl thioglycolate, propyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate , A compound having a mercapto group of ethylene glycol, a compound having a mercapto group of neopentyl glycol, and a compound having a mercapto group of pentaerythritol. Among these, n-octyl-3-mercaptopropionic acid ester is particularly preferable from the viewpoint of suppressing odor during toner heat fixing.
[0167]
(Surfactant)
In particular, in order to perform miniemulsion polymerization using the above-described polymerizable monomer, it is preferable to disperse oil droplets in an aqueous medium using a surfactant. The surfactant that can be used in this case is not particularly limited, and the following ionic surfactants can be given as examples of suitable compounds.
[0168]
Examples of the ionic surfactant include sulfonate (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol- 6-sulfonate sodium, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sulfonate sodium, etc.) , Sulfate salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, stearyl Potassium, calcium oleate and the like).
[0169]
Nonionic surfactants can also be used. Specifically, for example, polyethylene oxide, polypropylene oxide, a combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, Examples include sorbitan esters.
[0170]
In the present invention, these surfactants are mainly used as an emulsifier during emulsion polymerization, but may be used for other steps or for other purposes.
[0171]
(Molecular weight distribution of resin particles and toner)
The toner of the present invention preferably has a peak or shoulder at 100,000 to 1,000,000 and 1,000 to 50,000, and further has a peak or shoulder of 100,000 to 1,000,000, More preferably, it is present at 25,000 to 150,000 and 1,000 to 50,000.
[0172]
The molecular weight of the resin particles is both a high molecular weight component having a peak or shoulder in the region of 100,000 to 1,000,000 and a low molecular weight component having a peak or shoulder in the region of 1,000 to less than 50,000. A resin containing at least is preferable. More preferably, an intermediate molecular weight resin having a peak or shoulder at a peak molecular weight of 15,000 to 100,000 is preferably used.
[0173]
The molecular weight measurement method of the toner or resin is preferably measured by GPC (gel permeation chromatography) using THF (tetrahydrofuran) as a solvent. That is, 1.0 ml of THF is added to 0.5 to 5 mg of a measurement sample, more specifically 1 mg, and the mixture is sufficiently dissolved by stirring at room temperature using a magnetic stirrer or the like. Subsequently, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC. The measurement conditions of GPC are measured by stabilizing the column at 40 ° C., flowing THF at a flow rate of 1.0 ml / min, and injecting about 100 μl of a sample having a concentration of 1 mg / ml. The column is preferably used in combination with a commercially available polystyrene gel column. For example, combinations of Shodex GPC KF-801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko KK and TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, and TSKguard column manufactured by Tosoh Corporation And so on. As a detector, a refractive index detector (IR detector) or a UV detector may be used.
[0174]
In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve created using monodisperse polystyrene standard particles. About 10 points may be used as polystyrene for preparing a calibration curve.
[0175]
(Flocculant)
The flocculant used in the present invention is preferably selected from metal salts.
[0176]
Examples of the metal salt include monovalent metals such as alkali metal salts such as sodium, potassium and lithium, divalent metals such as alkaline earth metal salts such as calcium and magnesium, and divalent metals such as manganese and copper. Examples thereof include trivalent metal salts such as salts, iron and aluminum.
[0177]
Specific examples of these metal salts are shown below. Specific examples of the monovalent metal salt include sodium chloride, potassium chloride, lithium chloride, and divalent metal salts such as calcium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. Examples of the trivalent metal salt include aluminum chloride and iron chloride. These are appropriately selected according to the purpose. In general, the divalent metal salt has a smaller critical aggregation concentration (coagulation value or coagulation point) than the monovalent metal salt, and the trivalent metal salt has a smaller critical aggregation concentration.
[0178]
The critical flocculation concentration referred to in the present invention is an index related to the stability of the dispersion in the aqueous dispersion, and indicates the concentration at which flocculation occurs when a flocculant is added. This critical coagulation concentration varies greatly depending on the latex itself and the dispersant. For example, it is described in Seizo Okamura et al., Polymer Chemistry 17,601 (1960), etc., and the value can be known by following these descriptions. As another method, a desired salt is added to the target particle dispersion at a different concentration, the ζ potential of the dispersion is measured, and the salt concentration at the point where the ζ potential begins to change is defined as the critical aggregation concentration. It is also possible to do.
[0179]
In the present invention, the polymer fine particle dispersion is treated with a metal salt so as to have a concentration equal to or higher than the critical aggregation concentration. At this time, as a matter of course, whether the metal salt is added directly or as an aqueous solution is arbitrarily selected according to the purpose. When added as an aqueous solution, the added metal salt must be equal to or higher than the critical aggregation concentration of the polymer particles with respect to the volume of the polymer particle dispersion and the total volume of the metal salt aqueous solution.
[0180]
The concentration of the metal salt as a flocculant in the present invention may be not less than the critical aggregation concentration, but is preferably 1.2 times or more, more preferably 1.5 times or more the critical aggregation concentration.
[0181]
As the resin excellent in the present invention, those having a glass transition point of 20 to 90 ° C. are preferred, and those having a softening point of 80 to 220 ° C. are preferred. The glass transition point is measured by a differential calorimetric analysis method, and the softening point can be measured by a Koka flow tester.
[0182]
As a method for producing the toner of the present invention, a step of forming an oil phase component by dissolving or dispersing each material of a binder resin, a colorant, and a wax in an organic solvent, and the oil phase component in an aqueous solvent. An example of a preferable production method is a step of granulating and a step of separating and drying the particles.
[0183]
A step of preparing an oil component by dissolving or dispersing the binder resin, charge control resin, colorant, and release agent in an organic solvent that solubilizes the binder resin; and dispersing the oil component in an aqueous medium. A method for producing toner for developing an electrostatic latent image.
[0184]
The steps of preparing an oil component by dissolving and dispersing a binder resin, a colorant, and a wax in an organic solvent that solubilizes the binder resin are a binder resin, a charge control resin, a colorant, and a mold release In this step, the agent is mixed and dispersed in an organic solvent that solubilizes the binder resin.
[0185]
As the organic solvent for solubilizing the binder resin, a general organic solvent is used. For example, hydrocarbons such as toluene, xylene and hexane, halogenated hydrocarbons such as methylene chloride, chloroform and dichloroethane, alcohols such as methanol and ethanol, ethers such as tetrahydrofuran, esters such as methyl acetate, ethyl acetate and butyl acetate And ketones such as acetone, methyl ethyl ketone, and cyclohexanone. Of these, ethyl acetate, methyl ethyl ketone, and the like are preferable from the viewpoint of the solubility and solvent-removability of the resin. These may be used alone or in combination.
[0186]
The step of granulating toner from a state in which an oily component is dispersed in an aqueous medium refers to solidifying the oily component prepared in the above step from the state of being dispersed in an aqueous medium to produce particles, which are then dried. In this step, the toner is obtained.
[0187]
As the aqueous medium, water is mainly used, but a water-soluble solvent may be mixed. Furthermore, it is preferable in terms of particle size distribution to add a dispersant. Dispersants include tricalcium phosphate, hydroxyapatite, calcium carbonate, titanium oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, silica, cellulose, hydroxypropylmethylcellulose, methylcellulose, carboxymethylcellulose, starch, polyvinyl alcohol, polyacrylic An acid etc. are mentioned. The amount of the dispersant is preferably 0 to 20 parts by mass with respect to 100 parts by mass of the mother liquor.
As a stirring method for producing particles, it is desirable to apply shear, and a homogenizer, a colloid mill, a dissolver, or the like is used.
[0188]
As the drying, aeration drying apparatus, spray drying apparatus, rotary drying apparatus, air flow drying apparatus, fluidized bed drying apparatus, heat transfer heating type drying apparatus, freeze drying apparatus and the like are known, and any of them can be used.
[0189]
Colorant
Examples of the colorant (colorant particles) constituting the toner of the present invention include various inorganic pigments, organic pigments, and dyes. A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.
[0190]
Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.
[0191]
These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.
[0192]
When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.
[0193]
Conventionally known organic pigments and dyes can also be used. Specific organic pigments and dyes are exemplified below.
[0194]
Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.
[0195]
Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. And CI Pigment Yellow 156.
[0196]
Examples of green or cyan pigments include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.
[0197]
Examples of the dye include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc. can be used, and mixtures thereof can also be used.
[0198]
These organic pigments and dyes can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.
[0199]
The colorant (colorant particles) constituting the toner of the present invention may be surface-modified. A conventionally well-known thing can be used as a surface modifier, Specifically, a silane coupling agent, a titanium coupling agent, an aluminum coupling agent etc. can be used preferably.
[0200]
Examples of the silane coupling agent include alkoxysilanes such as methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane, and diphenyldimethoxysilane, siloxanes such as hexamethyldisiloxane, γ-chloropropyltrimethoxysilane, vinyltrimethyl. Chlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-ureido Examples thereof include propyltriethoxysilane.
[0201]
Examples of titanium coupling agents include TTS, 9S, 38S, 41B, 46B, 55, 138S, and 238S, which are commercially available under the trade name “Plenact” manufactured by Ajinomoto Co., Inc. -1, B-1, TOT, TST, TAA, TAT, TLA, TOG, TBSTA, A-10, TBT, B-2, B-4, B-7, B-10, TBSTA-400, TTS, TOA -30, TSDMA, TTAB, TTOP and the like. Examples of the aluminum coupling agent include “Plenact AL-M” manufactured by Ajinomoto Co., Inc.
[0202]
The addition amount of these surface modifiers is preferably 0.01 to 20% by mass, and more preferably 0.1 to 5% by mass with respect to the colorant.
[0203]
Examples of the method for modifying the surface of the colorant particles include a method in which a surface modifier is added to the dispersion of the colorant particles and this system is heated to react.
[0204]
The surface-modified colorant particles are collected by filtration, washed with the same solvent and filtered, and then dried.
[0205]
Release agent
The toner used in the present invention is preferably a toner obtained by fusing resin particles encapsulating a release agent in an aqueous medium. In this way, the resin particles in which the release agent is encapsulated in the resin particles are salted out / fused in the aqueous medium with the colorant particles, whereby a toner in which the release agent is finely dispersed can be obtained.
[0206]
In the toner of the present invention, as the release agent, low molecular weight polypropylene (number average molecular weight 1500 to 9000), low molecular weight polyethylene or the like is preferable, and an ester compound represented by the following formula is particularly preferable.
[0207]
R₁-(OCO-R₂)_n
In the formula, n is an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, particularly preferably 4. R₁, R₂Each represents a hydrocarbon group which may have a substituent. R₁Has 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 2 to 5 carbon atoms. R₂Has 1 to 40 carbon atoms, preferably 16 to 30 carbon atoms, and more preferably 18 to 26 carbon atoms.
[0208]
Next, the example of a typical compound is shown below.
[0209]
[Chemical 1]

[0210]
[Chemical 2]

[0211]
The amount of the compound added is 1 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 15% by mass with respect to the whole toner.
[0212]
The toner of the present invention is preferably prepared by encapsulating the release agent in resin particles by a mini-emulsion polymerization method, and salting out and fusing together with colored particles.
[0213]
<Toner particles>
The particle diameter of the toner of the present invention is preferably 2 to 10 [mu] m, more preferably 3 to 8 [mu] m in terms of number average particle diameter. This particle size can be controlled by the concentration of the flocculant (salting-out agent), the amount of organic solvent added, the fusing time, and the polymer composition in the toner production method.
[0214]
When the number average particle diameter is 3 to 10 μm, toner particles having high adhesion force that fly and adhere to the heating member and generate offset in the fixing process are reduced, and transfer efficiency is increased and halftone The image quality is improved, and the image quality of fine lines and dots is improved.
[0215]
The number average particle diameter of the toner can be measured using a Coulter Counter TA-II, Coulter Multisizer, SLAD 1100 (Laser Diffraction Particle Size Measuring Device manufactured by Shimadzu Corporation) or the like.
[0216]
In the present invention, a Coulter Multisizer is used, and an interface (manufactured by Nikka Machine Co., Ltd.) that outputs a particle size distribution and a personal computer are connected. The aperture in the Coulter Multisizer was 100 μm, and the volume distribution of toner of 2 μm or more (for example, 2 to 40 μm) was measured to calculate the particle size distribution and average particle size.
[0217]
Preferred shape factor range for toner particles
The shape factor of the toner of the present invention is represented by the following formula and indicates the degree of roundness of the toner particles.
[0218]
Shape factor = ((maximum diameter / 2) 2 × π) / projection area
Here, the maximum diameter refers to the width of a particle that maximizes the interval between the parallel lines when the projected image of the toner particles on the plane is sandwiched between two parallel lines. The projected area refers to the area of the projected image of the toner particles on the plane. In the present invention, this shape factor is obtained by taking a photograph in which the toner particles are magnified 2000 times with a scanning electron microscope, and then using “SCANNING IMAGE ANALYZER” (manufactured by JEOL Ltd.) based on this photograph. It was measured by performing analysis. At this time, the shape factor of the present invention was measured by the above formula using 100 toner particles.
[0219]
As the toner of the present invention, when the particle size of the toner particle is D (μm), the natural logarithm lnD is taken on the horizontal axis, and the number-based particle size distribution is divided into a plurality of classes at intervals of 0.23. In the histogram shown, the sum (M) of the relative frequency (m1) of the toner particles included in the most frequent class and the relative frequency (m2) of the toner particles included in the next most frequent class after the most frequent class is 70. % Of the toner is preferable.
[0220]
When the sum (M) of the relative frequency (m1) and the relative frequency (m2) is 70% or more, the dispersion of the particle size distribution of the toner particles becomes narrow. Therefore, selective development can be performed by using the toner in the image forming process. Can be reliably suppressed.
[0221]
In the present invention, the histogram showing the particle size distribution based on the number is a natural logarithm lnD (D: particle size of individual toner particles) having a plurality of classes (0 to 0.23: 0.23) at intervals of 0.23. 0.46: 0.46-0.69: 0.69-0.92: 0.92-1.15: 1.15-1.38: 1.38-1.61: 1.61-1. 84: 1.84 to 2.07: 2.07 to 2.30: 2.30 to 2.53: 2.53 to 2.76, and so on). This histogram was created by transferring the particle size data of the sample measured by the Coulter Multisizer to the computer via the I / O unit according to the following conditions and using the particle size distribution analysis program in the computer. is there.
[0222]
〔Measurement condition〕
1: Aperture: 100 μm
2: Sample preparation method: Electrolyte [ISOTON R-11 (manufactured by Coulter Scientific Japan)] 50-100 ml, an appropriate amount of a surfactant (neutral detergent) was added and stirred, and 10-20 mg of a measurement sample was added thereto. Add. This system is prepared by dispersing for 1 minute with an ultrasonic disperser.
[0223]
For toner particles, a toner composed of toner particles having a variation coefficient of shape factor of 16% or less and a number variation coefficient of 27% or less in the number particle size distribution is used. The presence is uniform, the charge amount distribution is sharp, and high fluidity is obtained. As a result, it is excellent in developability and fine line reproducibility, and stable cleaning properties can be formed over a long period of time.
[0224]
Furthermore, as a result of investigations by paying attention to the minute shape of each toner particle, the present inventors have changed the shape of the corner portion of the toner particle to become round inside the developing device, and this portion becomes an external additive. As a result, it was found that the change in charge amount, fluidity and cleaning properties were reduced.
[0225]
In addition, when a charge is applied to the toner particles by frictional charging, it is presumed that the external additive tends to be buried particularly at the corners, and the toner particles are likely to be non-uniformly charged.
[0226]
That is, by using toner composed of toner particles in which the number of toner particles having no corners is 50% by number or more and the number variation coefficient in the number particle size distribution is controlled to 27% or less, developability and fine line reproduction are also achieved. It has been found that a high-quality image can be formed over a long period of time.
[0227]
Toner particles having no corners are circles in which the major axis of the toner particles is L, and L / 10 is a radius R. Toner particles that do not substantially protrude outward. The case where it does not protrude substantially means that the number of protrusions protruding from the circle is one or less.
[0228]
Further, it has been found that even when toners are arranged in a specific shape, the external additive is not buried and the charge amount distribution is sharp.
[0229]
That is, even when toner having a shape factor of 1.2 to 1.6 in which the proportion of toner particles is 65% by number or more and the variation coefficient of the shape factor is 16% or less, developability, fine line An image with excellent reproducibility and high image quality can be formed over a long period of time.
[0230]
<Developer>
The toner of the present invention may be used as a one-component developer or a two-component developer.
[0231]
When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to.
[0232]
Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.
[0233]
The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.
[0234]
The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.
[0235]
<Image forming method>
Next, the image forming apparatus of the present invention will be described.
[0236]
FIG. 1 is a sectional view showing an example of an image forming apparatus according to the present invention. Reference numeral 4 denotes a photosensitive drum as a latent image forming body, which is formed by forming an organic photoconductor (OPC) as a photosensitive layer on the outer peripheral surface of an aluminum drum base, and rotates at a predetermined speed in an arrow direction. To do.
[0237]
In FIG. 1, exposure light is emitted from a semiconductor laser light source 1 based on information read by a document reading device (not shown). This is distributed in the direction perpendicular to the paper surface of FIG. 1 by the polygon mirror 2 and irradiated onto the surface of the photoreceptor through an fθ lens 3 that corrects image distortion, thereby forming an electrostatic latent image. The photosensitive drum 4 is uniformly charged in advance by the charger 5 and starts rotating clockwise in accordance with the timing of image exposure.
[0238]
The electrostatic latent image on the surface of the photosensitive drum is developed by the developing device 6, and the formed toner image is transferred to the transfer material (transfer paper) 8 that has been conveyed in time by the action of the transfer device 7. . Further, the photosensitive drum 4 and the transfer paper 8 are separated by a separator (separation pole) 9, but the developed image is transferred and supported on the transfer paper 8 and guided to the fixing device 10 to be fixed.
[0239]
Untransferred toner or the like remaining on the surface of the photoreceptor is cleaned by a cleaning device 11 of a cleaning blade type, removed residual charge by pre-charge exposure (PCL) 12, and again by the charger 5 for the next image formation. Uniformly charged.
[0240]
Toner recycling system
The method for recycling the toner is not particularly limited. For example, the toner collected by the cleaning unit is mixed with a replenishment toner hopper, a developing device or a replenishment toner by an intermediate chamber by a transport conveyor or a transport screw. And a method for supplying the developer to the developing device.
[0241]
Next, in FIG. 2, an example of a perspective configuration diagram of a toner recycling member is given. In this method, the recycled toner is directly returned to the developing unit.
[0242]
The untransferred toner collected by the cleaning blade 13 is collected on the toner recycling pipe 14 by the conveying screw in the toner cleaning device 11, returned to the developing device 6 from the receiving port 15 of the recycling pipe, and used again as a developer. .
[0243]
FIG. 2 is also a perspective view of a process cartridge detachably attached to the image forming apparatus of the present invention. In FIG. 2, the photosensitive unit and the developer unit are separated for easy understanding of the perspective structure. However, the unit can be detachably mounted on the image forming apparatus as an integrated unit. In this case, the photosensitive member, the developing device, the cleaning device, and the recycling member are integrated to form a process cartridge.
[0244]
In addition, the image forming apparatus may be configured to include a photosensitive drum and a process cartridge including at least one of a charging device, a developing device, a cleaning device, and a recycling member.
[0245]
Next, the transfer paper is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and of course includes an OHP PET base.
[0246]
The cleaning blade 13 uses a rubber-like elastic body having a thickness of about 1 to 30 mm, and urethane rubber is most often used as the material. Since this is used in pressure contact with the photoconductor, it is easy to transfer heat. In the present invention, it is desirable to provide a release mechanism and keep it away from the photoconductor when no image forming operation is performed.
[0247]
The present invention can also be used in an electrophotographic image forming apparatus, particularly an apparatus for forming an electrostatic latent image on a photosensitive member with a modulated beam modulated with digital image data from a computer or the like.
[0248]
As a scanning optical system that optically modulates with a digital image signal from a computer or a copy original employed in the image forming method and apparatus, an optical optical modulator is interposed in the laser optical system, and the optical modulation is performed by the acoustooptic modulator. There is an apparatus that directly modulates the laser intensity using a semiconductor laser, and forms a dot image by spot exposure on a uniformly charged photoconductor from these scanning optical systems.
[0249]
The beam irradiated from the scanning optical system described above has a circular or elliptical luminance distribution that approximates a normal distribution with a skirt extending from side to side. For example, in the case of a laser beam, the main scanning direction or One or both in the sub-scanning direction is an extremely narrow circle or ellipse of 20 to 100 μm.
[0250]
Fixing device
The toner of the present invention is fixed by passing a transfer material (image support, transfer paper) on which a toner image is formed as described above between a heating roller and a pressure roller constituting a fixing device (fixing device). It is suitably used for an image forming method including the step of:
[0251]
FIG. 3 is a cross-sectional view showing an example of a fixing device used in the image forming method using the toner of the present invention. The fixing device shown in FIG. 3 includes a heating roller 20 and a pressure roller 21 in contact with the heating roller 20. It has. In FIG. 3, T is a toner image formed on the transfer paper.
[0252]
The heating roller 20 has a coating layer 22 made of a fluororesin or an elastic body formed on the surface of a cored bar 23 and includes a heating member 24 made of a linear heater.
[0253]
The core metal 23 is made of metal and has an inner diameter of 10 to 70 mm. Although it does not specifically limit as a metal which comprises a metal core, For example, metals, such as iron, aluminum, copper, or these alloys can be mentioned.
[0254]
The thickness of the cored bar 23 is 0.1 to 15 mm, and is determined in consideration of the balance between the energy saving requirement (thinning) and the strength (depending on the constituent materials). For example, in order to maintain the same strength as that of a cored bar made of iron of 0.57 mm with a cored bar made of aluminum, the wall thickness needs to be 0.8 mm.
[0255]
Examples of the fluororesin constituting the coating layer 22 include PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer).
[0256]
Further, as the elastic body constituting the coating layer 22, it is preferable to use silicone rubber and silicone sponge rubber having good heat resistance such as LTV, RTV, and HTV.
[0257]
The Asker C hardness of the elastic body constituting the coating layer 22 is less than 80 °, preferably less than 60 °.
[0258]
The pressure roller 21 is formed by forming a coating layer 25 made of an elastic body on the surface of the cored bar 26. The elastic body constituting the coating layer 25 is not particularly limited, and examples thereof include various soft rubbers such as urethane rubber and silicone rubber, and sponge rubber, and those constituting the coating layer include silicone rubber and silicone. It is preferable to use sponge rubber.
[0259]
The Asker C hardness of the elastic body constituting the coating layer 25 is less than 80 °, preferably less than 70 °, and more preferably less than 60 °.
[0260]
The thickness of the coating layer 25 is 0.1 to 30 mm, preferably 0.1 to 20 mm.
[0261]
Although it does not specifically limit as a material which comprises the metal core 26, Metals, such as aluminum, iron, copper, or those alloys can be mentioned.
[0262]
The contact load (total load) between the heating roller 20 and the pressure roller 21 is usually 40 to 350 N, preferably 50 to 300 N, and more preferably 50 to 250 N. This contact load is defined in consideration of the strength of the heating roller 20 (the thickness of the core metal 23). For example, in a heating roller having a core metal made of 0.3 mm iron, the contact load should be 250 N or less. Is preferred.
[0263]
From the viewpoint of offset resistance and fixing property, the nip width is preferably 4 to 10 mm, and the surface pressure of the nip is preferably 0.6 × 10 5 to 1.5 × 10 5 Pa.
[0264]
If an example of the fixing conditions by the fixing device shown in FIG. 3 is shown, the fixing temperature (surface temperature of the heating roller) is 150 to 210 ° C., and the fixing linear velocity is 80 to 640 mm / sec.
[0265]
The fixing device used in the present invention may be provided with a cleaning mechanism as necessary. In this case, as a method of supplying silicone oil to the upper roller (heating roller) of the fixing unit, a method of supplying and cleaning with a pad, roller, web or the like impregnated with silicone oil can be used.
[0266]
As the silicone oil, one having high heat resistance is used, and polydimethyl silicone, polyphenylmethyl silicone, polydiphenyl silicone and the like are used. Since a low-viscosity thing will have a large outflow at the time of use, those having a viscosity at 20 ° C. of 1 to 100 Pa · s are preferably used.
[0267]
By setting the amount of silicone oil to be 2 mg or less per A4 sheet, the amount of silicone oil attached to the transfer paper (image support) after fixing is reduced, and the oiliness of ballpoint pens and the like by the silicone oil attached to the transfer paper is reduced. There is no difficulty in writing the pen, and the writing property is not impaired.
[0268]
Further, it is possible to avoid problems such as a decrease in offset resistance over time due to silicone oil alteration and contamination of the optical system and band electrode due to silicone oil.
[0269]
【Example】
Next, although the structure and effect of this invention are shown as an Example, of course, the aspect of this invention is not limited to this. In the text, “part” means “part by mass”.
[0270]
<Preparation example of hydrophobic silica>
Hydrophobic silica a1
Put 100 parts by mass of fumed silica with a primary particle size of 0.007 μm in a container having a high-speed mixer, spray 20 parts by mass of dimethyldichlorosilane while stirring at 8500 rpm in a nitrogen atmosphere, and continue stirring for another 5 minutes. After that, the obtained powder liquid was stirred under reflux at 200 ° C. for 3 hours under a nitrogen stream. Thereafter, the mixture was cooled to room temperature to obtain powdered hydrophobic silica a1.
[0271]
Hydrophobic silica a2
In the preparation example of the hydrophobic silica a1, except that fumed silica having a primary particle size of 0.012 μm was used instead of fumed silica having a primary particle size of 0.007 μm, and octyltrimethoxysilane was used instead of dimethyldichlorosilane, Hydrophobic silica a2 was obtained in the same manner as hydrophobic silica a1.
[0272]
Hydrophobic silica a3
In the preparation example of the hydrophobic silica a1, the hydrophobic silica a3 is the same as the hydrophobic silica a1 except that fumed silica having a primary particle diameter of 0.016 μm is used instead of fumed silica having a primary particle diameter of 0.007 μm. Got.
[0273]
Hydrophobic silica b1
In the preparation example of hydrophobic silica a1, except that fumed silica having a primary particle size of 0.033 μm was used instead of fumed silica having a primary particle size of 0.007 μm, and octyltrimethoxysilane was used instead of dimethyldichlorosilane, Hydrophobic silica b1 was obtained in the same manner as hydrophobic silica a1.
[0274]
Hydrophobic silica b2
In the preparation example of hydrophobic silica a1, except that fumed silica having a primary particle size of 0.030 μm was used instead of fumed silica having a primary particle size of 0.007 μm, and hexamethyldisilazane was used instead of dimethyldichlorosilane, Hydrophobic silica b2 was obtained in the same manner as hydrophobic silica a1.
[0275]
Hydrophobic silica b3
Hydrophobic silica except that in the preparation example of hydrophobic silica a1, fumed silica having a primary particle diameter of 0.070 μm was used instead of dimethyldichlorosilane instead of fumed silica having a primary particle diameter of 0.007 μm. Hydrophobic silica b3 was obtained in the same manner as a1.
[0276]
<Preparation example of hydrophobic titanium oxide>
Hydrophobic titanium oxide c1
In a round bottom flask equipped with a magnetic stirrer and a trap, 5 parts of titanium oxide (anatase-type titanium oxide having a number average particle size of 0.030 μm) dried at 110 ° C. for 24 hours, 150 parts of dehydrated toluene and 1. 5 parts of normal butyltrimethoxysilane was added, and 0.5 part of acetic acid was added as a buffering agent.
[0277]
The resulting suspension was refluxed at 50-60 ° C. for 7 hours, cooled to room temperature, and then filtered with suction. Subsequently, the residue was washed with toluene and dried at 110 ° C. for 4 hours. Thereafter, the mixture was filtered with suction, and then filtered with suction with ethanol, dried at 110 ° C. for 4 hours, and pulverized in a menor mortar to obtain a white powdery substance. The obtained white powdery substance is designated as hydrophobic titanium oxide c1.
[0278]
Hydrophobic titanium oxide c2
In the production of titanium oxide c1, titanium oxide having a number average particle size of 0.021 μm (rutile, anatase ratio 10:90) is used instead of normal butyltrimethoxysilane instead of anatase type titanium oxide having a number average particle size of 0.030 μm. Hydrophobic titanium oxide c2 was obtained in the same manner except that isobutyltrimethoxysilane was used.
[0279]
Hydrophobic titanium oxide c3
In the production of titanium oxide c1, rutile type titanium oxide having a number average particle size of 0.045 μm was used instead of anatase type titanium oxide having a number average particle size of 0.030 μm, and decylsilane was used instead of normal butyltrimethoxysilane. Similarly, hydrophobic titanium oxide c3 was obtained.
[0280]
Hydrophobic titanium oxide d1
In the production of titanium oxide c1, titanium oxide having a number average particle size of 0.092 μm (rutile, anatase ratio 60:40) is used instead of normal butyltrimethoxysilane instead of anatase type titanium oxide having a number average particle size of 0.030 μm. A hydrophobic large particle size titanium oxide d1 was obtained in the same manner except that octyltrimethoxysilane was used.
[0281]
Hydrophobic titanium oxide d2
In the production of titanium oxide c1, rutile titanium oxide having a number average particle size of 0.112 μm is used instead of anatase type titanium oxide having a number average particle size of 0.030 μm, and hexyltrimethoxysilane is used instead of normal butyltrimethoxysilane. A hydrophobic large particle size titanium oxide d2 was obtained in the same manner except that.
[0282]
Hydrophobic titanium oxide d3
In the production of titanium oxide c1, rutile type titanium oxide having a number average particle size of 0.409 μm was used instead of anatase type titanium oxide having a number average particle size of 0.030 μm, and decylsilane was used instead of normal butyltrimethoxysilane. Similarly, a hydrophobic large particle size titanium oxide d3 was obtained.
[0283]
Table 1 shows physical property values of the hydrophobic silicas a1 to a3, b1 to b3, and the hydrophobic titanium c1 to c3 and d1 to d3.
[0284]
[Table 1]

[0285]
<Preparation of composite resin particles>
Latex (1HML)
(1) Preparation of core particles (first stage polymerization)
Surfactant prepared by dissolving 7.08 g of an anionic surfactant (sodium dodecyl sulfonate: SDS) in 3010 g of ion-exchanged water in a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device The solution (aqueous medium) was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.
[0286]
To this surfactant solution, an initiator solution prepared by dissolving 9.2 g of a polymerization initiator (potassium persulfate: KPS) in 200 g of ion-exchanged water was added, the temperature was adjusted to 75 ° C., and then 70.1 g of styrene, n -A monomer mixture composed of 19.9 g of butyl acrylate and 10.9 g of methacrylic acid was added dropwise over 1 hour, and this system was polymerized by heating and stirring at 75 ° C for 2 hours (first stage polymerization). And a latex (a dispersion of resin particles made of a high molecular weight resin) was prepared. This is referred to as “latex (1H)”.
[0287]
(2) Formation of intermediate layer (second stage polymerization)
In a flask equipped with a stirrer, 105.6 g of styrene, 30.0 g of n-butyl acrylate, 6.4 g of methacrylic acid, 5.6 g of n-octyl-3-mercaptopropionic acid ester, Add 72.0 g of the compound represented by the formula (19) (hereinafter referred to as “Exemplary Compound (19)”, and other compounds having the same number) and warm to 80 ° C. to dissolve. A monomer solution was prepared.
[0288]
On the other hand, a surfactant solution in which 1.6 g of an anionic surfactant (SDS) was dissolved in 2700 ml of ion-exchanged water was heated to 80 ° C., and the latex (dispersed core particle) was added to the surfactant solution. 1H) was added in an amount of 28 g in terms of solid content, and then the monomer solution of the exemplified compound (19) was mixed and dispersed by a mechanical disperser “CLEARMIX” (manufactured by M-Technique) having a circulation path. Thus, a dispersion (emulsion) containing emulsion particles (oil droplets) having a uniform dispersion particle diameter (284 nm) was prepared.
[0289]
Next, an initiator solution prepared by dissolving 5.1 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water and 750 ml of ion-exchanged water were added to this dispersion (emulsion), and the system was heated at 80 ° C. Polymerization (second stage polymerization) was carried out by heating and stirring for 3 hours to obtain latex (a dispersion of composite resin particles having a structure in which the surface of resin particles made of a high molecular weight resin was coated with an intermediate molecular weight resin). This is referred to as “latex (1HM)”.
[0290]
(3) Formation of outer layer (third stage polymerization)
An initiator solution prepared by dissolving 7.4 g of a polymerization initiator (KPS) in 200 ml of ion-exchanged water is added to the latex (1HM) obtained as described above. A monomer mixed solution consisting of 95 g of n-butyl acrylate, 15.3 g of methacrylic acid, and 10.4 g of n-octyl-3-mercaptopropionic acid ester was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (third-stage polymerization) was performed by heating and stirring for 2 hours, followed by cooling to 28 ° C. and latex (a central portion made of a high molecular weight resin, an intermediate layer made of an intermediate molecular weight resin, A dispersion of composite resin particles) having an outer layer made of a molecular weight resin and containing the exemplified compound (19) in the intermediate layer was obtained. This latex is referred to as “latex (1HML)”.
[0291]
The composite resin particles constituting the latex (1HML) had peak molecular weights of 138,000, 80,000 and 13,000, and the number average particle diameter of the composite resin particles was 102 nm.
[0292]
Latex (2HL)
(1) Preparation of core particles (first stage polymerization)
In a flask equipped with a stirrer, 72.0 g of Exemplified Compound (16) was added to a monomer mixture consisting of 105.6 g of styrene, 30.0 g of n-butyl acrylate, and 6.4 g of methacrylic acid, and 80 ° C. The monomer solution was prepared by heating and dissolving.
[0293]
On the other hand, a surfactant solution in which 1.6 g of an anionic surfactant (SDS) was dissolved in 2700 ml of ion-exchanged water was heated to 80 ° C., and a mechanical disperser “Claire having a circulation path was added to the surfactant solution. Dispersion containing emulsified particles (oil droplets) having a uniform dispersed particle size (268 nm) by mixing and dispersing the monomer solution of the exemplified compound (16) by “CLEARMIX” (manufactured by M-Technique) (Emulsified liquid) was prepared.
[0294]
Next, an initiator solution prepared by dissolving 5.1 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water and 750 ml of ion-exchanged water were added to this dispersion (emulsion), and the system was heated at 80 ° C. Polymerization (first stage polymerization) was carried out by heating and stirring for 3 hours to prepare latex (a dispersion of resin particles made of a high molecular weight resin). This is referred to as “latex (2H)”.
[0295]
(2) Formation of outer layer (second stage polymerization)
An initiator solution obtained by dissolving 14.8 g of a polymerization initiator (KPS) in 400 ml of ion-exchanged water is added to the latex (2H) obtained as described above, and 600 g of styrene under a temperature condition of 80 ° C. A monomer mixed solution consisting of 190 g of n-butyl acrylate, 30.0 g of methacrylic acid, and 20.8 g of n-octyl-3-mercaptopropionic acid ester was added dropwise over 1 hour.
[0296]
After completion of the dropwise addition, polymerization (second-stage polymerization) is performed by heating and stirring for 2 hours, followed by cooling to 28 ° C. and having a latex (a central portion made of a high molecular weight resin and an outer layer made of a low molecular weight resin). A dispersion of composite resin particles containing the exemplified compound (16) in the center was obtained. This latex is referred to as “latex (2HL)”.
[0297]
The composite resin particles constituting the latex (2HL) had peak molecular weights of 168,000 and 11,000, and the weight average particle size of the composite resin particles was 126 nm.
[0298]
<Production of colored particles 1 to 4>
59.0 g of sodium n-dodecyl sulfate was dissolved in 1600 ml of ion-exchanged water with stirring. While stirring this solution, 420.0 g of carbon black “Regal 330” (Cabot Corporation) was gradually added, and then dispersed by using “Cleamix” (M-Technics Corporation) to give a coloring. A dispersion of agent particles (hereinafter referred to as “colorant dispersion”) was prepared. When the particle diameter of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the weight average particle diameter was 98 nm.
[0299]
420.7 g (in terms of solid content) of latex (1HML) obtained in the preparation of the composite resin particle 1, 900 g of ion-exchanged water, and 166 g of the colorant dispersion liquid are mixed with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device. The mixture was stirred in a reaction vessel having a two-stage stirring blade equipped with a particle size and shape monitoring device (crossing angle α of the blade was 25 °). After adjusting the internal temperature to 30 ° C., 5 mol / liter sodium hydroxide aqueous solution was added to this solution to adjust the pH to 11.0.
[0300]
Next, an aqueous solution in which 12.1 g of magnesium chloride hexahydrate was dissolved in 1000 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the temperature increase was started, and the system was heated to 90 ± 3 ° C. over 6 to 10 minutes (temperature increase rate: 10 ° C./min). In this state, the particle size of the associated particles was measured with a measuring instrument (Coulter Counter TA-II: manufactured by Coulter Co.), and when the volume average particle size became 5.5 μm, 80.4 g of sodium chloride was ion exchanged. The aqueous solution dissolved in 1000 ml of water was added to stop the particle growth, and further, the fusion was continued by heating and stirring at a liquid temperature of 85 ± 2 ° C. for 0.5 to 15 hours as an aging treatment.
[0301]
Then, it cooled to 30 degreeC on the conditions of 8 degreeC / min, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced associated particles are filtered using a Nutsche, washed repeatedly with ion-exchanged water, then dried at a suction air temperature of 60 ° C. using a flash jet dryer, and then at a temperature of 60 ° C. using a fluidized bed dryer. It dried and obtained the colored particle containing exemplary compound (16) as a mold release agent.
[0302]
In the monitoring of the salting-out / fusion stage and the shape control process, by controlling the number of revolutions of stirring and the heating time, the variation coefficient of the shape and the shape factor is controlled, and the variation coefficient of the particle size and the particle size distribution is arbitrarily set. By adjusting, colored particles 1 to 4 having shape characteristics and particle size distribution characteristics shown in Table 2 were obtained.
[0303]
<Manufacture of colored particles 5-8>
Instead of latex (1HML), 420.7 g (converted to solid content) of latex (2HL) obtained by preparing composite resin particles was used, and the production of colored particles 1 to 4 was performed except that the aging treatment time was changed. Similarly, colored particles 5 to 8 having the shape characteristics and particle size distribution characteristics shown in Table 2 were obtained.
[0304]
[Table 2]

[0305]
Hydrophobic silica a1 to a3, b1 to b3, and hydrophobic titanium c1 to c3 and d1 to d3 are added to each of the colored particles 1 to 8 obtained as described above at a ratio shown in Table 3 and 10 liters. The peripheral speed of the rotary blade of the Henschel mixer was set to 24 m / s and mixed for 15 minutes. Note that the shape and particle size of these colored particles are not changed by the addition of an external additive.
[0306]
Table 3 shows the results of counting external additive particles present on the toner surface, BET specific surface area, and surface abundance (ESCA measurement).
[0307]
[Table 3]

[0308]
<Manufacture of carriers>
Manufacture of ferrite core material
22 mol% of MnO, Fe₂O_Three78 mol% was pulverized, mixed and dried in a wet ball mill for 2 hours, and then temporarily calcined by holding at 900 ° C. for 2 hours, and this was pulverized in a ball mill for 3 hours to form a slurry. Dispersant and binder are added, granulated and dried by spray dryer, then fired at 1200 ° C. for 3 hours, resistance 4.3 × 10⁸Ω · cm ferrite core material particles were obtained.
[0309]
Manufacture of coating resin
Cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5) by an emulsion polymerization method in which the concentration in an aqueous medium using sodium benzenesulfonate having an alkyl group having 12 carbon atoms as a surfactant is 0.3% by mass. A volume average primary particle size of 0.1 μm, a weight average molecular weight (Mw) of 200,000, a number average molecular weight (Mn) of 91,000, Mw / Mn = 2.2, a softening point temperature (Tsp ) Resin fine particles having a temperature of 230 ° C. and a glass transition temperature (Tg) of 110 ° C. were obtained. The resin fine particles azeotroped with water in the emulsified state, and the residual monomer amount was 510 ppm.
[0310]
Next, 100 parts by mass of ferrite core material particles and 2 parts by mass of the resin fine particles are put into a high-speed agitator / mixer with agitating blades, and agitated and mixed at 120 ° C. for 30 minutes to use the action of mechanical impact force. Thus, a resin-coated carrier having a volume average particle size of 61 μm was obtained.
[0311]
<Manufacture of developer>
Each colored particle to which the external additive was added and the carrier were mixed to prepare a developer having a toner concentration of 6% by mass.
[0312]
  As shown in Table 3, the developers prepared by the above procedure were used in Examples 1 to10, Reference Examples 11-16 andIt was set as Comparative Examples 1-3.
[0313]
<Manufacture of photoconductor>
Manufacture of photoreceptor P1
The following coating solution was applied onto a cylindrical conductive support having a length of 380 mm and a diameter of 60 mm to prepare a photoreceptor P1.
<Underlayer>
Titanium chelate compound (TC-750, manufactured by Matsumoto Pharmaceutical) 30g
Silane coupling agent (KBM-503, Shin-Etsu Chemical Co., Ltd.) 17g
150 ml of 2-propanol
It apply | coated so that it might become a film thickness of 0.5 micrometer on a cylindrical conductive support body using the said coating liquid.

Were mixed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the undercoat layer by a dip coating method to form a charge generation layer having a thickness of 0.2 μm.

Were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 20 μm.
<Protective layer>
150g of methyltrimethoxysilane
Dimethyldimethoxysilane 30g
Reactive charge transport compound 15g
Antioxidant 0.75g
2-propanol 75g
3% acetic acid 5g
Were mixed to prepare a coating solution for the resin layer. A 2 μm-thick resin layer is formed on the charge transport layer on the charge transport layer by using a circular amount-regulating coating apparatus, and heat-cured at 120 ° C. for 1 hour to form a siloxane resin layer. Produced.
[0314]
  <Examples 1 to10, Reference Examples 11-16And Comparative Examples 1 to 3>
  A modified digital camera equipped with a photoreceptor (P1) on a commercial digital copier (Konica Sitios 7030) equipped with a toner recycling system has low pixels in a high temperature and high humidity environment (temperature 33 ° C, relative humidity 80%). After performing a live-action test that continuously forms 100,000 images with a rate of 2%, the image density depends on the environment, halftone uniformity, fine dot dust, spot-like toner stains, fogging Was evaluated.
[0315]
In the toner recycling system, an evaluation method for continuously printing an image with a low pixel ratio under a high temperature and high humidity environment is a severe condition for the following items because the external additive is buried.
[0316]
Environment dependence of image density
The maximum image density of the solid image portion was measured with a Macbeth reflection densitometer. The difference in image density between the high temperature and high humidity environment (33 ° C, relative humidity 80%) and the low temperature and low humidity environment (10 ° C, relative humidity 20%) is less than 0.05. “◯”, 0.1 or more was “x”.
[0317]
Halftone uniformity
The uniformity of the halftone was judged visually, and the uniformity of the halftone image was evaluated.
[0318]
The rank was evaluated as the following display.
Rank A: Uniform image without unevenness
Rank B: Image with thin stripe-like unevenness
Rank C: An image having several streaky thin irregularities
Rank D: An image in which several streaky irregularities are present.
Fine dots of Chile
A 10% halftone image was formed on the entire surface of the image, and dust around the dots was observed with a loupe. Items that can hardly be detected are marked with “◎”, while those that are slightly detected are marked with “◯”.
[0319]
Occurrence of fogging
The relative density with respect to the white background density of the specific image portion was measured with a Macbeth densitometer.
[0320]
A: Less than 0.002
○: 0.002 to less than 0.005
X: More than 0.005
Spot toner stains
A white background image was formed on the entire surface of 10 continuous images, and black spots having a diameter of 0.5 μm or more due to scattering of toner aggregates were indicated as “x”, and those not occurring were indicated as “◯”.
[0321]
The results are shown in Table 4.
[0322]
[Table 4]

[0323]
  As apparent from Table 4, Examples 1 to10However, Comparative Examples 1 to 3 outside the present invention have problems with each characteristic.
[0324]
【The invention's effect】
According to the present invention, (1) less dependency on the environment, (2) a uniform charge distribution, a sharp image with little dust of fine dots, and (3) excellent fluidity and toner under severe use conditions. It is possible to provide a toner for developing an electrostatic latent image which is free from image contamination due to scattering of granules and toner aggregates, and (4) is capable of producing a stable image with less deterioration in halftone homogeneity due to buried toner external additive. In addition, even when used in an image forming apparatus incorporating a toner recycling system, the image does not suffer from black spots or the like, and there is no decrease in toner fluidity or chargeability variation. Therefore, the image density is high and there is no fogging. A latent image developing toner, an image forming method, an image forming apparatus, and a process cartridge can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus.
FIG. 2 is a perspective view of a process cartridge that is detachable from an image forming apparatus.
FIG. 3 is a cross-sectional view illustrating an example of a fixing device.
[Explanation of symbols]
1 Semiconductor laser light source
2 Polygon mirror
3 fθ lens
4 Photosensitive drum as a latent image forming body
5 Charger
6 Developer
7 Transfer device
8 Transfer material (also called image support, transfer paper, etc.)
9 Separator (separator)
10 Fixing device
11 Cleaning device
13 Cleaning blade
14 Toner recycling pipe
15 Recycling pipe receptacle

Claims (8)

In the electrostatic latent image developing toner comprising at least a binder resin, a colorant, and an external additive,
The toner is composed of toner particles in which the proportion of toner particles having a shape factor in the range of 1.2 to 1.6 is 65% by number or more, and the variation coefficient of the shape factor is 16% or less.
65 to 95% by number of external additives existing on the toner surface of 0.005 μm or more and less than 0.025 μm, 4 to 35% by number of 0.025 μm or more and less than 0.080 μm, 0.080 μm or more and 0.500 μm A toner for developing an electrostatic latent image, wherein less than 0.3 to 10% by number. 2. The electrostatic latent image developing toner according to claim 1, wherein the external additive is composed of silica and titanium oxide. 3. The electrostatic latent image developing toner according to claim 1, wherein two kinds of silica having different number average particle diameters and two kinds of titanium oxides having different number average particle diameters are externally added. 4. The electrostatic latent image developing toner according to claim 1, wherein the toner is obtained by polymerizing at least a polymerizable monomer in an aqueous medium. The electrostatic latent image developing toner according to any one of claims 1 to 4, wherein the toner is obtained by aggregating and fusing at least resin particles in an aqueous medium. In a toner for developing an electrostatic latent image comprising at least a binder resin, a colorant, and an external additive obtained by aggregating and fusing at least resin particles in an aqueous medium, the toner has a ratio of toner particles having no corners. Is 50% by number or more, and the number variation coefficient in the number particle size distribution is 27% or less,
  65 to 95% by number of external additives existing on the toner surface of 0.005 μm or more and less than 0.025 μm, 4 to 35% by number of 0.025 μm or more and less than 0.080 μm, 0.080 μm or more and 0.500 μm A toner for developing an electrostatic latent image, wherein less than 0.3 to 10% by number. BET specific surface area is 1.3 to 1.9 m ² / g, silicon atom surface abundance measured by ESCA is 6 to 12 area%, titanium element surface abundance is 0.5 to 4 area%, carbon atom The toner for developing an electrostatic latent image according to claim 1, wherein the toner is present in an amount of 50 to 75 area%.   8. An image forming method employing toner recycling, wherein the toner according to claim 1 is used.

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