JP2004212520A - Toner and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner which prevents occurrence of a streaky image (development streaks) by suppressing the fusion and sticking of the toner on a regulating member in a toner regulation part in a developing vessel. <P>SOLUTION: The toner comprises toner particles consisting essentially of binder resin, colorant, and an external additive on the surfaces of the toner particles, wherein the external additive is fine silica particles (a) having peaks in at least (1) a range of 0.04 to 1.0 μm, (2) a range of 1.0 to 50 μm and (3) a range of 50 to 2,000 μm in a volume particle size distribution measured with a laser diffraction type particle size distribution analyzer. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００７８】
かかる表面処理用の微粉体をトナー母体表面に処理する具体的な方法としては、着色性樹脂粒子と、上記の如き疎水化シリカ微粉末等、および必要に応じてその他の無機粉体や滑剤粉末を加え、上記の混合装置で充分に混合することによって行う。
【００７９】
次に、本発明に使用可能なトナー粒子の製造方法について述べる。
【００８０】
本発明に係るトナー粒子を製造するには、溶融粉砕法、重合法等の公知の方法が用いられる。
【００８１】
溶融粉砕法の例としては、結着樹脂、ワックス、着色剤としての顔料、染料、荷電制御材、必要に応じその他の添加剤等をヘンシェルミキサー、ボールミル等の混合器により十分混合した後、加熱ロール、ニーダー、エクストルーダーの如き熱混練機を用いて溶融混練して樹脂類を溶解した中に金属化合物、顔料、染料を分散又は溶解し、冷却固化し、次いで、粉砕、球形化処理、分級を行なって本発明に係るトナーを得ることが出来る。
【００８２】
分級工程においては生産効率上、多分割分級機を用いることが好ましい。
【００８３】
また、重合法の例としては、重合性単量体、架橋剤、重合開始剤、ワックス、着色剤としての顔料、染料、又は磁性体、その他の添加剤等を混合分散し、懸濁分散安定剤の存在下、水系中で懸濁重合することにより重合性着色樹脂粒子を合成し、固液分離、乾燥の後分級を行なって本発明に係るトナーを得ることが出来る。
【００８４】
該懸濁分散安定剤は、公知のものが使用でき、具体的にはリン酸三カルシウム，リン酸マグネシウム，リン酸アルミニウム，炭酸カルシウム，炭酸マグネシウム，水酸化カルシウム，硫酸カルシウム，シリカ，アルミナ等の無機化合物や、ポリビニルアルコール，ゼラチン，セルロース類の金属塩，デンプン等の有機系化合物があげられる。これら分散剤は、重合性単量体１００質量部に対して０．２〜１０質量部を使用することが好ましい。
【００８５】
本発明のトナー粒子の原材料は特に限定するものではなく、電子写真用のトナーとして公知の材料が使用できる。
【００８６】
本発明のトナー粒子に使用可能な着色剤としては、任意の適当な顔料又は染料が挙げられる。トナー着色剤は周知であって、例えば黒色顔料としてカーボンブラック、磁性体、アニリンブラック、アセチレンブラック、ランプブラック、グラファイトあるいはこれらの混合物、または以下に示すイエロー着色剤／マゼンタ着色剤／シアン着色剤を混合して黒色に調色されたものが利用される。
【００８７】
イエロー着色剤としては、縮合アゾ化合物、イソインドリノン化合物、アンスラキノン化合物、アゾ金属錯体、メチン化合物、アリルアミド化合物に代表される化合物等が用いられる。具体的には、Ｃ．Ｉ．ピグメントイエロー１２、１３、１４、１５、１７、６２、７４、８３、９３、９４、９５、１０９、１１０、１１１、１２８、１２９、１４７、１６８、１８０等が好適に用いられる。
【００８８】
マゼンタ着色剤としては、縮合アゾ化合物、ジケトピロロピロール化合物、アンスラキノン、キナクリドン化合物、塩基染料レーキ化合物、ナフトール化合物、ベンズイミダゾロン化合物、チオインジゴ化合物、ペリレン化合物等が用いられる。具体的には、Ｃ．Ｉ．ピグメントレッド２、３、５、６、７、２３、４８；２、４８；３、４８；４、５７；１、８１；１、１４４、１４６、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１、２５４が特に好ましい。
【００８９】
かかる顔料を単独で使用しても構わないが、染料と顔料と併用してその鮮明度を向上させた方がフルカラー画像の画質の点からより好ましい。
【００９０】
染料の具体例として例えばＣ．Ｉ．ダイレクトレッド１、Ｃ．Ｉ．ダイレクトブルー１、Ｃ．Ｉ．ダイレクトグリーン６等がある。
【００９１】
これらは定着画像の光学濃度を維持するために必要な量が使用され、通常、結着樹脂１００質量部に対して、０．１〜６０質量部、好ましくは０．５〜２０質量部使用される。
【００９２】
本発明のトナー粒子に用いられる結着樹脂は、トナーを製造する際に用いられるものであれば特に限定されるものでははい。本発明のトナー用樹脂に用いられる結着樹脂の具体例としては、以下の重合性単量体の重合体、又は、重合性単量体単独の重合体の混合物、あるいは、２種類以上の重合性単量体の共重合生成物が挙げられる。更に具体的には、スチレン−アクリル酸共重合体あるいはスチレン−メタクリル酸系共重合体が好ましい。
【００９３】
また、定着性を改善する目的で公知の架橋性重合性単量体や連鎖移動剤を使用することも良い。
【００９４】
さらに、本発明のトナーには、定着時の離型性向上のために公知のワックス成分を含有することが好ましい。ワックス成分としては、定着時の離型性及び現像性として十分な性能を維持するものであれば特に限定されるものではない。
【００９５】
ワックス成分の具体的な例としては以下の化合物が挙げられる。
【００９６】
例えばシリコーン樹脂、ポリエステル、ポリウレタン、ポリアミド、エポキシ樹脂、ポリビニルブチラール、ロジン、変性ロジン、テルペン樹脂、フェノール樹脂、低分子量ポリエチレン又は低分子量ポリプロピレンの如き脂肪族又は脂環族炭化水素樹脂、芳香族系石油樹脂、塩素化パラフィン、パラフィンワックスなどである。
【００９７】
中でも好ましく用いられるワックスは、低分子量ポリプロピレン及び子の副生成物、低分子量ポリエステルおよびエステル系ワックス、脂肪族の誘導体である。
【００９８】
これらのワックスから、種々の方法によりワックスを分子量により分別したワックスも本発明に好ましく用いられる。また、分別後に酸価やブロック共重合、グラフト変性を行っても良い。
【００９９】
本発明に好適なトナーの粒度としては、従来、電子写真に使用されている一般的なトナー粒子径が使用可能である。トナーの粒度としては例えばコールターマルチサイザー（コールター社製）で測定される体積平均粒子径で２μｍ以上１５μｍ以下が好ましく、５μｍ以上１０μｍ以下がより好ましい。
【０１００】
トナーの体積平均粒子径が２μｍ未満の場合は、本発明の外添剤を使用しても本発明の効果が得られ難くなり好ましくない。特に、連続耐久での粒度変化が抑制できにくくなり、耐久での転写性悪化による画質劣化を招くため好ましくない。さらに、このような粒度のトナーは、画像カブリが悪化する傾向があり、本発明の外添剤を使用してもその傾向は良化しにくいものである。
【０１０１】
また、トナーの体積平均粒子径が１５μｍ超の場合は、トナーへの帯電付与性が低下し、トナーの機内への飛散やトナーのボタもれによる画像汚染を生じやすくなるため好ましくない。特にこのような傾向は高湿度環境での使用初期などで顕著である。
【０１０２】
本発明に好適なトナー形状としては、トナーの個数基準の粒径頻度分布における円相当個数平均径が２〜１０μｍであり、円形度頻度分布における平均円形度が０．９２０〜０．９９５、より好ましくは０．９８０〜０．９９５とすることがよい。また、円形度の分布状態を表す円形度標準偏差は０．０４０未満であることが好ましい。
【０１０３】
これらの形状にトナーの粒子形状を精密に制御することでトナーの転写性や耐久安定性が向上し、本願の効果がさらに効果的に現れるものである。
【０１０４】
特に、電子写真での微小スポット潜像を現像する場合において平均円形度が０．９２０以上であることが有効である。また、平均円形度が０．９９５を超えるとトナー表面の劣化が著しいものとなり耐久性等に問題を生じる様になる。
【０１０５】
従って本発明に好適なトナーの形状は適度な円形度及び適度な円形度の分布状態を維持することが重要である。
【０１０６】
特に上のごとき傾向は、複数のトナー像を現像／転写せしめるフルカラー複写機を用いた場合に顕在化する。すなわち、フルカラー画像の生成においては、４色のトナー像が均一に転写されにくく、さらに、中間転写体を用いる場合には色ムラやカラーバランスの面で問題が生じ易く、高画質のフルカラー画像を安定して出力することが困難となる。
【０１０７】
本発明におけるトナーの円形度及び円形度の分布状態は、トナー粒子の形状を定量的に表現する簡便な方法として用いたものであり、本発明ではその測定方法の一例としてフロー式粒子像測定装置ＦＰＩＡ−１０００型（東亜医用電子社製）を用いて測定した。
【０１０８】
次に、本発明に好適な画像形成方法について述べる。
【０１０９】
本願で好適な画像形成方法は、少なくともトナー規制部材、トナー供給部材、静電潜像担持体、転写部材かななる一成分接触現像方法である。
【０１１０】
静電潜像担持体としては、Ａ−Ｓｅ、Ｃｄｓ、ＺｎＯ_２、ＯＰＣ、Ａ−Ｓｉの様な光導電絶縁物質層を持つ公知の感光ドラムもしくは感光ベルトが好適に使用される。
【０１１１】
これらの中で、ＯＰＣが特に好ましく使用される。ＯＰＣ静電潜像担持体における有機系感光層の結着樹脂は特に限定するものではなく、公知の結着樹脂が使用できるが、トナーの帯電性や転写性、フィルミングの観点から、ポリカーボネート樹脂、ポリアリレート樹脂が好ましい。
【０１１２】
本発明の画像形成方法における潜像担持体の帯電工程は、特に限定するものではなく、種々の帯電方法を使用することができる。具体的には、帯電手段が静電潜像担持体に非接触なコロナ放電や帯電部材を静電潜像担持体に当接させる直接帯電法が好適に使用できる。また、帯電ブレードを用いる帯電方法や、導電性ブラシを用いる方法も可能である。
【０１１３】
本発明の画像形成方法におけるトナー供給部材は、トナー供給部材として剛体ローラを用い、静電潜像担持体をベルトのごときフレキシブルなものとした構成や、静電潜像担持体として剛体を、トナー供給部材として弾性体のごときフレキシブルなものを使用する構成をとることが可能である。
【０１１４】
剛体の静電潜像担持体に対して圧接して配置する場合は弾性ローラが好ましく用いられる。以下、弾性ローラと剛体の静電潜像担持体を組合せて使用する系について述べる。
【０１１５】
本発明に好適な現像工程は、トナーを担持するトナー供給部材を静電潜像担持体に直接接触させ現像を行なうものである。トナー供給部材と静電潜像担持体の回転方向は順方向に設定されている。
【０１１６】
弾性ローラの硬度としては、現像性と耐久性の両立の観点から２０〜６５度（ＡＳＫＥＲ Ｃ）程度が好ましく、３０〜６０度が更に好ましい。弾性ローラの材質としては公知の材質、構造のものが使用可能である。特にシリコーンゴム、ウレタンゴム、ＮＢＲの如きソリッドのゴム弾性体、あるいはこれらの発泡弾性体が好ましく使用される。また、表面に中心部と異なるコート層を有する公知の多層構造ローラも使用できる。また、帯電性付与や搬送性付与の目的で公知の表面処理を施しても良い。
【０１１７】
トナー供給部材の表面形状としては、その表面粗度を制御することが高画質及び高耐久性を両立するために好ましい。トナー供給部材の表面粗度として、たとえばＲａ（μｍ）「ＪＩＳ Ｂ ０６０１」を０．２〜３．０となるように設定すると、高画質及び高耐久性を両立できる。該トナー供給部材の表面粗度Ｒａが３．０を超えると、該トナー供給部材上のトナー層の薄層化が困難となるばかりか、トナーの帯電性が改善されないので画質の向上は望めない。３．０以下にすることでトナー供給部材表面のトナーの搬送能力を抑制し、該トナー供給部材上のトナー層を薄層化すると共に、該トナー供給部材とトナーの接触回数が多くなるため、該トナーの帯電性も改善されるので相乗的に画質が向上する。一方、表面粗度Ｒａが０．２よりも小さくなると、トナーコート量の制御が難しくなる。
【０１１８】
トナー供給部材上のトナーは、トナー供給部材表面に圧接するよう配置されているトナー規制部材により規制され、トナー供給部材上のトナー層を形成する。
【０１１９】
トナー規制部材をトナー供給部材表面へ圧接しトナー供給部材上の層厚を規制する圧力は、トナーのトナー量を一定にし、且つ、トナーに程良い帯電性を付与するように適宜調節することが好ましい。
【０１２０】
トナーコート量の規制部材の材質としては、所望の極性にトナーを帯電させるのに適した摩擦帯電系列の材質を選択することが好ましく、シリコーンゴム、ウレタンゴム、ＮＢＲの如きゴム弾性体、ポリエチレンテレフタレートの如き合成樹脂弾性体、ステンレス、鋼、リン青銅の如き金属弾性体が使用でき、また、それらの複合体、たとえば、金属弾性体に樹脂やゴムをスリーブ当接部に当たるように貼り合わせるものや、コーティング塗布したものであっても良い。
【０１２１】
更に、弾性の規制部材中に有機物や無機物を添加してもよく、溶融混合させても良いし、分散させても良い。例えば、金属酸化物、金属粉、セラミックス、炭素同素体、ウィスカー、無機繊維、染料、顔料、界面活性剤などを添加することにより、トナーの帯電性をコントロールできる。特に、弾性体がゴムや樹脂等の成型体の場合には、シリカ、アルミナ、チタニア、酸化錫、酸化ジルコニア、酸化亜鉛等の金属酸化物微粉末、カーボンブラック、一般にトナーに用いられる荷電制御剤等を含有させることも好ましい。
【０１２２】
また、導電性の規制部材とトナー供給部材の組み合わせで使用する場合は、規制部材とトナー供給部材の間に直流電場及び／または交流電場を印加することも好ましい。このような電場を印加することによって、均一薄層塗布や、均一帯電性が向上し、充分な画像濃度の達成及び良質の画像を得ることができる。
【０１２３】
また、弾性の規制部材とトナー供給部材に耐久性が要求される場合には、金属弾性体に樹脂やゴムをスリーブ当接部に当たるように貼り合わせるものや、コーティング塗布したものが好ましい。
【０１２４】
さらに転写方法は特に限定するものではなく、接触または非接触方式の公知の転写方式が使用可能である。
【０１２５】
【実施例】
以下、本発明を製造例及び実施例により具体的に説明するが、これは本発明をなんら限定するものではない。
【０１２６】
シリカ微紛体の製造例
公知の乾式法によりシリカ微粒子を合成した。さらにこの製造方法の工程をコントロールすることでシリカ微粒子の粒径をコントロールし、任意の粒子径を有するシリカ微粒子を合成した。さらにこれらシリカ微粒子を複数種組合せ、且つ、表２に示す表面処理剤を１０乃至３０重量％使用して表面処理した後、適宜解砕処理、及び粗大粒子の除去処理を行うことで粒径頻度のピークをコントロールしたシリカ微粒子を合成した。
【０１２７】
粒径頻度のピークコントロール方法としては種々の手段が存在するが、本例では下記の方法により行った。
【０１２８】
▲１▼０．０４〜１．０μｍ ： 乾式法によりシリカ微粒子を合成するときの温度、圧、撹拌の製造条件でコントロールにより調整した。具体的には、おもに乾式での気層成長時の時間、圧力及び温度を適宜制御することで０．０４〜１．０μｍの範囲にピークを有するシリカ微粉体の合成を行った。
【０１２９】
▲２▼１．０〜５０μｍ ： 表面処理品の解砕処理条件でのコントロールにより調整した。具体的には、▲３▼５０〜２０００μｍの範囲にピークを有するシリカ微粉体に対して解砕装置（機械式ミル粉砕装置、例えばボールミルやミクロンミルなど）を使用して解砕処理することで、１．０〜５０μｍの範囲にピークを有するシリカ微粉体の合成を行った。なお、解砕処理は、その機械的強度の強弱からにより、解砕程度の異なるサンプルを用意した。
【０１３０】
▲３▼５０〜２０００μｍ ： 表面処理時の表面処理剤の特性と量、及び処理方法（溶剤希釈してスプレードライする）の処理条件でコントロールにより調整した。具体的には、▲２▼１．０〜５０μｍの範囲にピークを有するシリカ微粉体に対して、表面処理剤の粘度、及び表面処理剤を噴霧するときの溶剤希釈濃度、吐出量を適宜制御することで５０〜２０００μｍの範囲にピークを有するシリカ微粉体の合成を行った。
【０１３１】
得られた外添剤の粒度分布のピーク位置と使用した表面処理剤及び解砕処理の強度について表２にまとめた。
【０１３２】
【表２】

【０１３３】
トナーの製造例
トナー製造例（１）
高速撹拌装置ＴＫ−ホモミキサーを具備した２リットル用四つ口フラスコ中に、Ｎａ_３ＰＯ_４水溶液を添加し回転数を９０００ｒｐｍに調整し、６３℃に加温せしめた。ここにＣａＣｌ_２水溶液を徐々に添加し、微小な難水溶性分散剤Ｃａ_３（ＰＯ_４）_２を含む水系分散媒体を調製した。
【０１３４】
一方、

上記材料をボールミルで十分に分散させた後、ボールミルより内容物を単離した。この内容物に重合開始剤を添加したものを、前記水系分散媒体中に投入し回転数９０００ｒｐｍを維持しつつ造粒した。その後、パドル撹拌翼で撹拌しつつ６５℃で４時間反応させた後、８０℃で５時間重合させた。５時間後に減圧蒸留することにより残留する低分子量分を除去した。
【０１３５】
反応終了後、懸濁液を冷却し、塩酸を加えて難水溶性分散剤Ｃａ_３（ＰＯ_４）_２を溶解し、濾過、水洗、乾燥した後に風力分級によって所望の粒度に分級し、トナー粒子（１）を得た。
【０１３６】
このようにして得られたトナー粒子（１）１００質量部対して、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つシリカ微粒子（１） １．５質量部を混合して、ヘンシェルミキサー（三井鉱山社製）に仕込んだ。
【０１３７】
ヘンシェルミキサーは撹拌翼の周方向に対してバッフル板が９０度、回転数は１８００回転になるよう設定したものを使用した。この装置を用い２０分間混合することによって、本発明のトナー（１）を合成した。
【０１３８】
得られたトナーの重量平均粒子径は６．５５μｍ、平均円形度は０．９８０、円形度標準偏差は０．０３９であった。
【０１３９】
また、得られたトナーの表面を走査型電子顕微鏡（ＦＥ ＳＥＭ 日立製Ｓ−４７００など）によって観察したところ、トナー粒子表面にシリカ微粒子が付着しているのが確認できた。さらに、１μｍ以上のシリカ微粒子は存在していないことがわかった。
【０１４０】
これは、トナー粒子表面に外添剤を付着させる外添処理工程で１μｍ以上のシリカ微粒子がほぐれ、着色剤表面に付着したものと考えられる。また、このような結果から、１μｍ以上のシリカ微粒子は、その凝集力は低く、容易に解砕されうることがわかる。従って、この１μｍ以上のシリカ微粒子は表面処理工程での表面処理剤の液滴を中心として一次粒子径に近い粒度のシリカ微粒子が付着して塊状になったものであると考えられる。
【０１４１】
また、このとき使用した微粒子（１）についてレーザー回折型粒度分布を測定したところ、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つものであった。さらにこの分布の▲１▼０．０４〜１．０μｍの粒子径に属する粒度頻度（Ｒ２）と、▲３▼５０〜２０００μｍの粒子径に属する粒度頻度（Ｒ２）との関係（Ｒ２／Ｒ１）を調べたところ０．４であった。
【０１４２】
トナー製造例（２）、（３）
外添剤を微粒子（１）に替えて▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つ微粒子（２）及び（３）を使用する他はトナー製造例（１）と同様にして本発明のトナー（２）及び（３）を合成した。
【０１４３】
また、このとき使用した微粒子についてレーザー回折型粒度分布を測定したところ、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つものであった。さらにこの分布の▲１▼０．０４〜１．０μｍの粒子径に属する粒度頻度（Ｒ２）と、▲３▼５０〜２０００μｍの粒子径に属する粒度頻度（Ｒ２）との関係（Ｒ２／Ｒ１）を調べたところ、シリカ微粒子（２）は０．５、シリカ微粒子（３）は１．０であった。
【０１４４】
トナー製造例（４）
外添剤を微粒子（１）に替えて▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍの範囲にそれぞれピークを持つ微粒子（４）を０．５質量部と、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つ微粒子（７）を１．２質量部とを用い、さらに、ハイドロタルサイト化合物０．２質量部を混合する他はトナー製造例（１）と同様にして本発明のトナー（４）を合成した。また、このとき使用した微粒子（４）と（７）を別途混合してレーザー回折型粒度分布を測定したところ、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つものであった。さらにこの分布の▲１▼０．０４〜１．０μｍの粒子径に属する粒度頻度（Ｒ２）と、▲３▼５０〜２０００μｍの粒子径に属する粒度頻度（Ｒ２）との関係（Ｒ２／Ｒ１）を調べたところ１．５であった。
【０１４５】
トナー製造例（５）
トナー製造例（１）で使用した着色剤をカーボンブラックからピグメントイエロー１８０に替え、且つ、ハイドロタルサイトをチタン酸ストロンチウム０．１質量部に替えた他はトナー製造例（１）と同様にして本発明のトナー（５）を合成した。
【０１４６】
トナー製造例（６）
トナー製造例（１）で使用した着色剤をカーボンブラックからピグメントレッド１６６に替えた他はトナー製造例（１）と同様にして本発明のトナー（６）を合成した。
【０１４７】
トナー製造例（７）
トナー製造例（１）で使用した着色剤をカーボンブラックからピグメントブルー１５：３に替え、且つ、ハイドロタルサイトをルチル型の酸化チタンに替えた他はトナー製造例（１）と同様にして本発明のトナー（７）を合成した。
【０１４８】
トナー製造例（８）
トナー製造例（１）で使用した微粒子（１）に替えて、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍの範囲にそれぞれピークを持つ微粒子（４）を０．６質量部と、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つ微粒子（７）を０．５質量部とを用いる他はトナー製造例（１）と同様にして本発明のトナー（８）を合成した。
【０１４９】
また、このとき使用した微粒子（４）と（７）を別途混合してレーザー回折型粒度分布を測定したところ、（Ｒ２／Ｒ１）は０．６であった。
【０１５０】
トナー製造例（９）
トナー製造例（１）で使用した微粒子（１）の量を０．８質量部とし、且つ、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つ微粒子（２）を０．８質量部とを用いる他はトナー製造例（１）と同様にして本発明のトナー（９）を合成した。
【０１５１】
また、このとき使用した微粒子（１）と（２）を別途混合してレーザー回折型粒度分布を測定したところ、（Ｒ２／Ｒ１）は０．５であった。
【０１５２】
トナー製造例（１０）
トナー製造例（１）で使用した微粒子（１）の量を０．４質量部とし、且つ、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つ微粒子（２）を０．４質量部と、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つ微粒子（３）を０．４質量部とを用い、且つ、酸化チタン０．１質量部とを用いる他はトナー製造例（１）と同様にして本発明のトナー（１０）を合成した。
【０１５３】
また、このとき使用した微粒子（１）、（２）と（３）を別途混合してレーザー回折型粒度分布を測定したところ、（Ｒ２／Ｒ１）は０．６であった。
【０１５４】
トナー製造例（１１）

上記材料をニーダー型ミキサーに仕込み、混合しながら非加圧下で１２０℃に昇温させ、充分に前混合する。その後３本ロールで２回混練し、第一の混練物を得た。
【０１５５】

上記材料をヘンシェルミキサーにより十分予備混合を行い、二軸式押出し機で溶融混練し、冷却後ハンマーミルを用いて約１〜２ｍｍ程度粗粉砕し、次いでエアージェット方式による微粉砕機で微粉砕した。更に得られた微粉砕物を多分割分級装置で微粉及び粗粉を同時に厳密に除去した後、ローターを回転して機械的衝撃力を与える方式の表面改質装置を用い、１６００ｒｐｍ（周速８０ｍ／ｓｅｃ）で３分間バッチ式により該トナー粒子を表面処理し、次いで多分割分級装置によって分級し、トナー粒子（２）を得た。
【０１５６】
このようにして得られたトナー粒子（２）１００質量部対して、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つシリカ微粒子（１）１．８質量部を混合して、ヘンシェルミキサーに仕込み、トナー製造例（１）と同様の条件で混合することによって、本発明のトナー（１）を合成した。
【０１５７】
得られたトナーの円相当平均粒子径Ｄ１は７．２μｍ、平均円形度は０．９６８、円形度標準偏差は０．０３４であった。
【０１５８】
比較トナー製造例（１）
トナー製造例（１）で使用した微粒子（１）に替えて、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍの範囲にそれぞれピークを持つ微粒子（４）２．０質量部と、酸化チタン０．１質量部とを用いる他はトナー製造例（１）と同様にして比較用トナー（１）を合成した。
【０１５９】
比較トナー製造例（２）
トナー製造例（１）で使用した微粒子（１）に替えて、▲２▼１．０〜５０μｍと、▲３▼５０〜２０００μｍの範囲にそれぞれピークを持つ微粒子（７）１．８質量部を用いる他はトナー製造例（１）と同様にして比較用トナー（２）を合成した。
【０１６０】
比較トナー製造例（３）
トナー製造例（１）で使用した微粒子（１）に替えて、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍの範囲にそれぞれピークを持つ微粒子（４）１．０質量部と、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍの範囲にそれぞれピークを持つ微粒子（５）１．０質量部と、酸化チタン０．１質量部とを用いる他はトナー製造例（１）と同様にして比較用トナー（３）を合成した。
【０１６１】
また、このとき使用した微粒子（４）と（５）を別途混合してレーザー回折型粒度分布を測定したところ、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍの範囲にそれぞれピークを持つものであった。
【０１６２】
得られたトナー製造例、及び比較製造例について表３にまとめた。
【０１６３】
【表３】

【０１６４】
実施例で使用する画像形成装置について、以下にその概略を説明する。
【０１６５】
図１において、１は潜像担持体としての感光ドラムであって、該感光ドラム１は図示矢印Ａ方向に回転し、帯電装置２によって一様に帯電され、露光手段であるレーザー光３によってその表面に静電潜像が形成される。
【０１６６】
上記静電潜像は、現像装置４によって現像されてトナー像として可視化されるが、現像装置４は感光ドラムｌに対して近接配置され、プロセスカートリッジとして画像形成装置本体に対し着脱可能に構成されている。尚、本実施の形態では、露光部にトナー像を形成する所謂反転現像を行っている。
【０１６７】
可視化された感光ドラム１上のトナー像は、転写ローラ９によって記録媒体である紙１３に転写され、転写されないで感光ドラム１上に残留する転写残トナーは、クリーニングブレード１０により掻き取られて廃トナー容器１１に収納され、クリーニングされた感光ドラム１は前記作用を繰り返して画像形成を行う。
【０１６８】
一方、トナー像を転写された紙１３は定着装置１２によって定着処理され、装置外に排出されてプリント動作が終了する。
【０１６９】
次いで、本発明に係る前記現像装置４を図２に基づいて説明する。
【０１７０】
図３において、１４は一成分トナーとしての非磁性トナー８を収容する現像容器であり、該現像容器１４内の長手方向に延在する開口部には、感光ドラム１と、対向配置されたトナー供給部材としてのトナー供給部材５が回転可能に配置されており、このトナー供給部材５に担持された非磁性トナー８によって感光体１上の静電潜像が現像されて可視化される。
【０１７１】
上記トナー供給部材５は、アスカーＣ硬度が４０度のソリッドゴムに対してウレタン成分を含むコート層を有するローラである。
【０１７２】
このトナー供給部材５は、現像容器１４の前記開口部にて図に示す右半周面を現像容器１４内に突入し、左半周面を現像容器１４外に露出して横設されている。このトナー供給部材５の現像容器１４外へ露出した面は、現像装置４の左方に位置する感光ドラム１に対して微小間隙をもって対向している。そして、このトナー供給部材５は図１の矢印Ｂ方向に回転駆動され、その表面は適度な凹凸を有しており、この凹凸によって該トナー供給部材５の非磁性トナー８との摺擦確率が高められるとともに、非磁性トナー８の搬送が良好に行われる。
【０１７３】
また、トナー供給部材５の上方位置には、トナー規制部材７が押え板金１５に支持されて設けられており、該トナー規制部材７の自由端側の先端近傍はトナー供給部材５の外周面に面接触状態で当接されている。尚、トナー規制部材７は、バネ弾性を有するリン青銅の金属薄板を用いている。
【０１７４】
このトナー供給部材５に対するトナー規制部材７の当接圧を適宜調整することによって、トナー供給部材５上のトナー乗り量が０．５ｇ／ｍ^２になるよう調整した。
【０１７５】
更に、図２において、６はトナー補給部材としてのローラであり、該ローラ６は前記トナー規制部材７のトナー供給部材５表面との当接部に対してトナー供給部材回転方向上流側に当接され、且つ、回転可能に支持されている。
【０１７６】
以上の構成を有する現像装置４において、現像動作時に現像容器１４内の非磁性トナー８は、撹拌部材１９の矢印Ｃ方向の回転に伴ってローラ６方向に送られる。
【０１７７】
そして、非磁性トナー８は、ローラ６が図示矢印Ｄ方向に回転することによってトナー供給部材５の近傍に搬送され、トナー供給部材５とローラ６との当接部においてローラ６上に担持されている非磁性トナー８はトナー供給部材５と摺擦されることによって摩擦帯電を受け、トナー供給部材５上に付着する。
【０１７８】
その後、非磁性トナー８はトナー供給部材５の矢印Ｂ方向の回転に伴ってトナー規制部材７の圧接下に送られ、ここで適正な摩擦帯電を受けてトナー供給部材５上に薄層形成された後、感光ドラム１との対向部である現像部へ搬送されて現像に供される。
【０１７９】
実施例１から２０、及び、比較例１から３
以上、図１及び図２の現像器を用いて、トナー製造例（１）から（２０）、及び、比較製造例（１）から（３）のトナーをトナー容器にそれぞれ充填し、画像印字率が５％になるよう調整した評価用画像を用い、モノカラーで連続６０００枚の耐久を行い、トナーの画質及び耐久性について評価を行った。
【０１８０】
なお、画像出力環境としては温度１５℃，湿度５％ＲＨ環境、及び、温度３２℃，湿度７０％ＲＨの２環境において行った。
【０１８１】
以上の評価結果を表４及び５にまとめる（評価基準は後述）。
【０１８２】
【表４】

【０１８３】
【表５】

【０１８４】
このような低温低湿及び高温高湿環境での耐久において、実施例１〜１８ではスジ状画像（現像スジ）の発生が軽減されている理由としては、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと▲３▼５０〜２０００μｍの範囲に少なくともそれぞれピークを持つシリカ微粒子を使用することによって、現像容器内でのトナー規制部分において、規制部材へのトナーの融着、固着を抑えることが可能となったためであると考えられる。
【０１８５】
また、トナー飛散、トナーボタもれ、画像カブリの発生を抑制できた理由としては、トナーの耐久劣化を抑制し、耐久劣化による特性変動を少なくすることが可能となったためであると考えられる。
【０１８６】
また、耐久後の現像器内のトナー成分を分析したところ、実施例１乃至１８においてはトナー粒度は初期の粒度とほとんど変化しておらず、さらに外添剤の定量を行ったところ、外添剤由来の元素存在比率も初期とほとんど変化していないことがわかった。一方、比較例１乃至３においては粒度、及び外添剤量は耐久によって変化していた。
【０１８７】
このようなことから、耐久での転写抜け、ライン太さが安定した劣化の少ない画像が得られた理由としては、耐久中のトナー、及び外添剤の選択消費が少なくなったことが効果的に作用したためであると考えられる。
【０１８８】
実施例１９
本実施例で使用したフルカラーの画像形成実施例について説明する。
一例として、各色のトナー画像を静電潜像担持体に現像し、逐次転写する画像形成方法について、図３をもとに説明する。
【０１８９】
ここでは、第１，第２，第３および第４の画像形成部２９ａ，２９ｂ，２９ｃ，２９ｄが並設されており、各画像形成部はそれぞれ専用の静電潜像保持体、いわゆる感光ドラム１９ａ，１９ｂ，１９ｃおよび１９ｄを具備している。
【０１９０】
感光ドラム１９ａ，１９ｂ，１９ｃおよび１９ｄはその外周側に潜像形成手段２３ａ，２３ｂ，２３ｃおよび２３ｄ、現像部１７ａ，１７ｂ，１７ｃおよび１７ｄ、転写用放電部２４ａ，２４ｂ，２４ｃおよび２４ｄ、ならびにクリーニング部１８ａ，１８ｂ，１８ｃおよび１８ｄが配置されている。
【０１９１】
このような構成にて、先ず、第１画像形成部２９ａの感光ドラム１９ａ上に潜像形成手段２３ａによって原稿画像における、例えばイエロー成分色の潜像が形成される。該潜像は現像手段１７ａのイエロートナーを有するトナーで可視画像とされ、転写部２４ａにて、転写材としての記録材Ｓに転写される。
【０１９２】
上記のようにイエロー画像が転写材２５に転写されている間に、第２画像形成部２９ｂではマゼンタ成分色の潜像が感光ドラム１９ｂ上に形成され、続いて現像手段１７ｂのマゼンタトナーを有するトナーで可視画像とされる。この可視画像（マゼンタトナー像）は、上記の第１画像形成部２９ａでの転写が終了した転写材Ｓが転写部２４ｂに搬入されたときに、該転写材Ｓの所定位置に重ねて転写される。
【０１９３】
以下、上記と同様な方法により第３，第４の画像形成部２９ｃ，２９ｄによってシアン色，ブラック色の画像形成が行なわれ、上記同一の転写材Ｓに、シアン色，ブラック色を重ねて転写するのである。このような画像形成プロセスが終了したならば、転写材Ｓは定着部２２に搬送され、転写材Ｓ上の画像を定着する。これによって転写材Ｓ上には多色画像が得られるのである。転写が終了した各感光ドラム１９ａ，１９ｂ，１９ｃおよび１９ｄはクリーニング部１８ａ，１８ｂ，１８ｃおよび１８ｄにより残留トナーを除去され、引き続き行なわれる次の潜像形成のために供せられる。
【０１９４】
なお、上記画像形成装置では、転写材としての記録材Ｓの搬送のために、搬送ベルト２５が用いられており、図３において、転写材Ｓは右側から左側へ搬送され、その搬送過程で、各画像形成部２９ａ，２９ｂ，２９ｃおよび２９ｄにおける各転写部２４ａ，２４ｂ，２４ｃおよび２４ｄを通過し、転写をうける。
【０１９５】
この画像形成方法において、転写材Ｓを搬送する搬送手段として加工の容易性及び耐久性の観点からテトロン（登録商標）繊維のメッシュを用いた搬送ベルトおよびポリエチレンテレフタレート系樹脂、ポリイミド系樹脂、ウレタン系樹脂の如き薄い誘電体シートを用いた搬送ベルトが利用される。
【０１９６】
転写材Ｓが第４画像形成部２９ｄを通過すると、ＡＣ電圧が除電器２０に加えられ、転写材Ｓは除電され、ベルト２５から分離され、その後、定着器２２に入り、画像定着され、排出口２６から排出される。
【０１９７】
本発明トナーは転写性が優れているので、転写を繰返す毎に搬送手段の帯電が増しても、同じ転写電流で各転写におけるトナーの転写性を均一化でき、良質な高品位画像が得られることになる。
【０１９８】
このフルカラー画像形成装置を用い、現像部１７−ａ、１７−ｂ、１７−ｃ、１７−ｄに、トナー（４）、トナー（５）、トナー（６）、トナー（７）を用い、フルカラーモードで温度２３℃／湿度５０％の条件下でＡ４サイズの用紙に横線パターン画像を連続５０００枚の耐久試験を行った。
【０１９９】
画像評価：
初期及び耐久画像について現像品質、転写性、現像スジ、カブリについて評価したところ、いずれに於いても遜色のない画像が得られた。さらに、耐久終了時の現像器付近のトナー飛散を観察したところほとんど問題のないレベルであった。
【０２００】
以上から、本外添剤を使用して実用的なフルカラー画像形成が可能であることが明らかになった。
【０２０１】
このような耐久でのスジ状画像（現像スジ）の発生が起こらない理由としては、▲１▼０．０４〜１．０μｍと、▲２▼１．０〜５０μｍと▲３▼５０〜２０００μｍの範囲に少なくともそれぞれピークを持つシリカ微粒子を使用することによって、現像容器内でのトナー規制部分において、規制部材へのトナーの融着、固着を抑えることが可能となったためであると考えられる。
【０２０２】
また、トナー飛散、トナーボタもれ、画像カブリの発生を抑制できた理由としては、トナーの耐久劣化を抑制し、耐久劣化による特性変動を少なくすることが可能となったためであると考えられる。
【０２０３】
また、耐久後の現像器内のトナー成分を分析したところ、トナー粒度は初期の粒度とほとんど変化しておらず、さらに外添剤の定量を行ったところ、外添剤由来の元素存在比率も初期とほとんど変化していないことがわかった。
【０２０４】
このようなことから、耐久での転写抜け、ライン太さが安定した劣化の少ない画像が得られた理由としては、耐久中のトナー、及び外添剤の選択消費が少なくなったことが効果的に作用したためであると考えられる。
【０２０５】
従って、本発明で好適な粒度分布を有するシリカ粒子を使用したトナーは、本実施例の如き現像方法とのマッチングに優れたものであることがわかった。
【０２０６】
更にこのような効果は、現像装置の規制部分の帯電付与挙動から考えると、本願実施例の非磁性一成分接触現像系でより顕著に現れるものであると考えられる。
【０２０７】
本実施例に示した評価基準を以下に示す。
【０２０８】
プリントアウト画像評価
（１）画像品質
１０枚目のべた黒パターンのサンプル内の、４０点の濃度を測定する。高濃度５点と低濃度５点のそれぞれの平均値を求め、その差に応じてランク分けした。濃度測定は、反射濃度計ＲＤ９１８（マクベス社製）でおこなった。 尚、画像濃度は「マクベス反射濃度計」（マクベス社製）を用いて、原稿濃度が０．００の白地部分のプリントアウト画像に対する相対濃度を測定した。
Ａ：非常に良好 濃度差が０．１未満
Ｂ：良好 濃度差が０．１以上０．２未満
Ｃ：可 濃度差が０．２以上０．３未満
Ｄ：実用上問題なし 濃度差が０．３以上０．５未満
Ｅ：実用不可 濃度差が０．５以上
【０２０９】
（２）転写性
全白画像を出力し、「リフレクトメータ」（東京電色社製）により測定したプリントアウト画像の白地部分の白色度と転写紙の白色度の差から、カブリ濃度（％）を算出し、画像カブリを評価し、帯電安定性の指標とした。
Ａ：非常に良好 転写抜けが認められない
Ｂ：良好 転写抜けが認められるがほとんど気にならないレベル
Ｃ：可 転写抜けがあるが問題にないレベル
Ｄ：実用上問題なし 転写抜けが著しいが問題にならないレベル
Ｅ：実用不可 転写抜けが著しく問題となるレベル
【０２１０】
（３）文字太り
耐久中に図４に示す画像を出力し、出力画像から｛幅ａ｝と｛幅ｂ｝を１０点測定したものの平均を、図４に示す測定式に当てはめて文字太り率（％）を算出し文字太りを評価した。
Ａ：１１０％未満
Ｂ：１１０％以上、１３０％未満
Ｃ：１３０％以上、１５０未満
Ｄ：１５０％以上、１７０未満
Ｅ：１９０％以上
【０２１１】
（４）現像スジ
２５％ハーフトーン画像を出力し、画像上の現像スジの発生の程度を目視で評価した。
Ａ：非常に良好 （未発生）
Ｂ：良好 （ほとんど発生せず）
Ｃ：実用可 （弱いスジが数本発生するが、実用上問題にならないレベル）
Ｄ：実用難あり （弱いスジが多数発生し、実用上問題となるレベル）
Ｅ：実用不可 （著しいスジが発生し、実用外のレベル）
【０２１２】
（５）カブリ
「リフレクトメータ」（東京電色社製）により測定したプリントアウト画像の白地部分の白色度と転写紙の白色度の差から、カブリ濃度（％）を算出し、画像カブリを評価した
Ａ：非常に良好（１．０％未満）
Ｂ：良好 （１．０％以上、２．０％未満）
Ｃ：実用可 （２．０％以上、３．０％未満）
Ｄ：実用難あり（３．０％以上、４．０％未満）
Ｅ：実用不可 （４％以上）
【０２１３】
（６）トナー飛散
耐久後のプロセスカートリッジを観察し、トナーの飛び散りや、もれに由来する機内汚染の発生レベルを目視評価した。
Ａ：非常に良好 （汚染が全くない）
Ｂ：良好 （汚染が僅かにあるが実用上問題ないレベル）
Ｃ：許容内 （汚染があるが、実用可能なレベル）
Ｄ：若干問題あり（汚染が認められ、連続使用に於いて若干問題あるレベル）
Ｅ：実用不可 （汚染が著しく、実用不可なレベル）
【０２１４】
【発明の効果】
以上説明したように、本発明のトナー及び画像形成方法によれば、耐久での画質劣化を抑制し、転写性が良好なトナー、及び画像形成方法が得られる。また、規制部材への融着を極力抑えることで現像スジの発生しにくいトナー、及び画像形成方法が得られる。さらに、トナーの帯電性が安定することで、初期及び耐久中の画像カブリがほとんどなく、トナー飛散による機内汚染を防止する効果が得られる。
【図面の簡単な説明】
【図１】本発明に好適な非磁性一成分画像形成装置の概略図である。
【図２】本発明に好適な非磁性一成分画像形成装置の現像部分の概略図である。
【図３】本発明に好適な一例であるフルカラーの画像形成装置の概略図である。
【図４】文字太りを測定するための画像の概略図である。
【符号の説明】
１ 感光体ドラム（潜像担持体）
２ 帯電ローラ
３ レーザー光
４ 現像容器
５ トナー供給部材
７ トナー規制部材
９ 転写ローラ
１０ クリーニング機構
１３ 転写材
１２ 定着器
１７ａ カラー現像容器１
１７ｂ カラー現像容器２
１７ｃ カラー現像容器３
１７ｄ カラー現像容器４[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a toner used in a recording method using an electrophotographic method, an electrostatic recording method, a magnetic recording method, a toner jet method, or the like, or a toner used in a full-color image forming method, and an image forming method. More specifically, the present invention relates to electrophotography such as a copying machine, a printer, and a facsimile, which forms a toner image on an electrostatic latent image carrier in advance, and then transfers the image onto a transfer material to form an image. The present invention relates to a toner used in a one-component contact developing method used for electroprinting and an image forming method.
[0002]
More specifically, the present invention relates to a full-color electrophotographic toner developed using a non-magnetic one-component toner including yellow, magenta, cyan, and black, and an image forming method.
[0003]
[Prior art]
2. Description of the Related Art Conventionally, toners used in electrophotography have various fine particles (external additives) mechanically attached to the surface of toner particles for the purpose of imparting appropriate powder characteristics. As a kind of the external additive, many methods have been proposed in which inorganic fine powders such as various metal oxides are mixed and used.
[0004]
Among these, a toner using a plurality of silicas in combination has been proposed, and a toner free from a decrease in powder fluidity of the toner itself, a decrease in print density, and no fog even when continuous printing is repeated can be obtained.
[0005]
A toner in which two or more kinds of silica particles and a conductive metal oxide are externally added to toner particles has been proposed. According to the invention, even if continuous printing is repeated, the toner can be obtained without lowering of powder fluidity of the toner itself, lowering of print density, and generation of fog (for example, see Patent Document 1).
[0006]
Further, there has been proposed a toner in which the distribution of the particle diameter existence ratio of the external additive present on the toner surface is specified (for example, see Patent Document 2).
[0007]
In Patent Document 2, 65 to 95% by number of external additives present on the toner surface is 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, and 0. Disclosed is a toner for developing an electrostatic latent image, wherein 0.3 to 10% by number of 080 μm or more and less than 0.500 μm is used. Such a toner has low environmental dependency, uniform charge distribution, a sharp image with less fine dot dust, excellent fluidity, and toner stains even under severe use conditions due to scattering of toner granules and toner aggregates. No stable deterioration of halftone uniformity due to burying of toner external additive is obtained.
[0008]
However, the proposal of Patent Document 2 describes the primary particle size distribution of the external additive attached to the toner particle surface when the external additive is observed by SEM. On the other hand, the present application has a completely different scale because it is a rule for the particle size distribution in the form of secondary aggregates, which is one of the properties of the original external additive. In addition, although such a proposal has the described effects, there is no clear description on image deterioration and transfer failure in durability, development streaks and image fogging due to fusion of toner to a regulating member, and the effects are unknown. In particular, there is no description of long-term use in a non-magnetic one-component contact developing system, and the effect of the non-magnetic one-component contact developing system is unknown.
[0009]
[Patent Document 1]
JP-A-2000-89507
[Patent Document 2]
JP-A-2002-196526
[0010]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner and an image forming method which solve the above-mentioned problems of the related art.
[0011]
That is, a first object of the present invention is to provide a toner and an image forming method in which streak-like images (development streaks) are not generated by suppressing fusion and fixation of toner to a regulating member in a toner regulating portion in a developing container. Is to provide.
[0012]
Further, a second object of the present invention is to provide a toner and an image forming method which do not cause toner scattering, toner leakage, and image fogging throughout durability by suppressing deterioration due to durability of toner and reducing characteristic fluctuation due to durability deterioration. To provide.
[0013]
Further, a third object of the present invention is to provide a toner capable of obtaining a stable image with less transfer loss and a stable line thickness by reducing the selective consumption of the toner and the external additive during the durability. An object of the present invention is to provide an image forming method.
[0014]
[Means to solve the problem]
The present inventors have conducted intensive studies and as a result, have found that, in a toner composed of toner particles and an external additive, the use of an external additive having a characteristic volume particle size distribution of the external additive exhibits a desired effect. I found it.
[0015]
That is, toner particles comprising at least a binder resin and a colorant, and a toner having an external additive on the surface of the toner particles,
The external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) 1.0 to 50 μm,
(3) It has been found that the above-mentioned problems can be solved by a non-magnetic one-component toner characterized by externally adding silica fine particles (a) each having at least a peak in the range of 50 to 2000 μm, and an image forming method. Was.
[0016]
Further, toner particles, a toner having an external additive on the surface of the toner particles,
The external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) silica fine particles (b) each having at least a peak in the range of 1.0 to 50 μm;
(2) 1.0 to 50 μm,
{Circle around (3)} A non-magnetic one-component toner characterized by externally adding two types of silica fine particles having different particle size distributions of silica fine particles (c) having at least a peak in the range of 50 to 2000 μm, and an image forming method. Also found that the same effect was exhibited.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The feature of the present invention lies in the particle size distribution of the external additive of the toner.
[0018]
The first feature of the present invention will be described.
[0019]
The toner of the present invention is a toner having at least a binder resin and a colorant, and a toner having an external additive on the surface of the toner particles,
The external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) 1.0 to 50 μm,
{Circle around (3)} A non-magnetic one-component toner characterized by externally adding silica fine particles (a) each having at least a peak in the range of 50 to 2000 μm, and an image forming method using the toner.
[0020]
The second feature of the present invention will be described.
[0021]
The toner of the present invention is a toner having at least a binder resin and a colorant, and a toner having an external additive on the surface of the toner particles,
The external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) silica fine particles (b) each having at least a peak in the range of 1.0 to 50 μm;
(2) 1.0 to 50 μm,
{Circle around (3)} Non-magnetic one-component toner characterized by externally adding two types of silica fine particles (c) having at least respective peaks in the range of 50 to 2000 μm and having different particle size distributions, and using the toner Image forming method.
[0022]
The external additive of the present invention has a characteristic distribution in a volume particle size distribution measured by a laser diffraction type particle size distribution meter.
[0023]
First, in the present invention, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) 1.0 to 50 μm
(3) silica fine particles (a) having at least respective peaks in the range of 50 to 2000 μm;
Or, the external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) silica fine particles (b) each having at least a peak in the range of 1.0 to 50 μm;
(2) 1.0 to 50 μm,
{Circle around (3)} Externally adding two types of silica fine particles having different particle size distributions of silica fine particles (c) having at least peaks in the range of 50 to 2000 μm.
Being
Is required.
[0024]
The silica fine particles having a peak in the particle size distribution of 0.04 μm or more and less than 1.0 μm have a smaller particle size than the toner particles. These silica fine particles having a peak in the particle size distribution are present in the primary particle diameter of the original silica or in a lightly secondary aggregated state.
[0025]
When the external additives having these particle diameters are externally added to the surface of the colorant particles, the external additives maintain the primary particle diameter or the lightly secondary aggregation state even when they are attached to the toner particle surfaces.
[0026]
Although it is not clear whether the particle size characteristics of such silica fine particles are directly related to the effect, for example, when used in a non-magnetic one-component developing method, silica fine particles having such particle size characteristics are used as colorant particles. By being present on the surface, it is possible to prevent the toner from being fused and fixed to the toner regulating member, and it is possible to prevent the occurrence of streak-like images (developing stripes) caused by the fusion and fixation of the regulating member. It became clear.
[0027]
Further, it was revealed that the presence of the external additive having the particle diameter of such silica fine particles on the toner surface suppressed the deterioration of other external additives and reduced the durability change of the transfer efficiency. .
[0028]
This is because such silica fine particles having a peak in the particle size distribution of not less than 0.04 μm and less than 1.0 μm have a relatively large particle size when compared to silica fine particles belonging to other distributions when attached to the toner surface. For this reason, it is considered that embedding of the external additive on the toner surface due to mechanical stress during durability was suppressed. It is thought that by suppressing such external additive deterioration, the state close to the initial characteristics was maintained even in the latter half of the durability, and the transferability equivalent to the initial state could be maintained even with the toner subjected to the durability. Can be
[0029]
Next, the silica fine particles having a peak in the particle size distribution in the range of 1.0 to 50 μm have a particle size equal to or larger than that of the toner particles. These silicas are secondary aggregates obtained by secondary aggregation of fine silica particles. It is presumed that such secondary aggregation occurs due to electrostatic attraction between the primary particles of the silica fine particles and interparticle force.
[0030]
The presence of such silica aggregates in the external additive of the toner assists the chargeability of the toner and stabilizes the charge characteristics of the toner. Further, the silica fine particles having such a particle size have a great effect of improving the fluidity of the toner, and exhibit the inherent fluidity of the toner.
[0031]
Accordingly, such silica fine particles having a peak in the particle size distribution have an effect of suppressing white background contamination (image fog) during development.
[0032]
Further, by adding such silica fine particles having a peak in the particle size distribution in the range of 1.0 to 50 μm, the effect of suppressing the particle size selectivity of the toner particles in durability and averaging the toner consumption particle size can be obtained. Express. As a result, even in the latter half of the durability, it is possible to maintain the fine line reproducibility equivalent to the initial stage.
[0033]
Next, the silica fine particles having a peak in the particle size distribution in the range of 50 to 2000 μm are mainly aggregates in which the silica fine particles form a huge secondary aggregate by a surface treatment agent or the like.
[0034]
Such agglomerates of silica fine particles are not present in the silica fine particles before the treatment, but appear after the surface treatment, and thus are considered to have been generated by this surface treatment.
[0035]
These silica fine particles having a peak in the particle size distribution are remarkably generated by the treatment with a low-viscosity liquid, such as oil, among the hydrophobic treatments. Also, as the amount of processing increases, the peak in the range of 50 to 2000 μm increases. This is a process in which the silica fine particles are stirred appropriately while a low-viscosity liquid hydrophobizing agent such as oil is directly sprayed or sprayed with a solvent-diluted mist. It is considered that this is because the method of attaching to the surface is adopted.
[0036]
Accordingly, the silica fine particles having such a peak in the particle size distribution are silica particles having a feature that they contain a large amount of a low-viscosity liquid hydrophobizing agent such as oil as compared with silica fine particles having other particle size distributions.
[0037]
When silica fine particles containing a large amount of a low-viscosity liquid hydrophobizing agent such as oil are used and adhered to the surface of toner particles by a mechanical method, a peak appears in such a particle size distribution due to the mechanical treatment. The silica fine particles having the same change their structure and are themselves crushed to a particle size close to the secondary aggregate of the silica fine particles before the treatment. At the same time, a part of the low-viscosity liquid hydrophobizing agent held in the aggregate is released into the system. It is considered that most of the released low-viscosity liquid hydrophobizing agent adheres to the surface of the toner particles.
[0038]
Therefore, by using silica fine particles having a peak in a particle size distribution in the range of 50 to 2000 μm, a low-viscosity liquid hydrophobizing agent such as oil can be contained in the toner in a minute distribution.
[0039]
When a toner containing a low-viscosity liquid hydrophobizing agent such as oil in a minute distribution is used in a one-component contact developing system, it is possible to supply oil to a toner regulating unit in a developing device. Will be possible.
[0040]
By supplying the oil from the toner to the members in the developing device in this manner, it becomes possible to make it difficult to cause the fusion of the toner to the toner regulating member by, for example, the releasing action of the oil. Further, since this oil is generally a hydrophobizing agent, the frictionally charged portion of the developing device is hardly affected by humidity, so that the effect of stabilizing the operation in the environment of the developing device can be obtained. .
[0041]
Particle size measurement method
The measuring method of the volume particle size distribution by the laser diffraction type particle size distribution meter in the present invention was performed by the method described later.
[0042]
measuring device
・ Coulter LS-230 type particle size distribution meter (manufactured by Coulter)
Particle size measurement range
・ 0.04 μm to 2000 μm
Measurement solvent
·ethanol
Equipment factor
-Refractive index of ethanol: 1.36
-Optical model: 1.08 (real part)-0.00i (imaginary part)
Measurement temperature
・ 20 ℃ ～ 25 ℃
Measuring method  (Parts not described conform to the handling method of the device.)
• Execute the background function with the measurement solvent.
-Prepare a separately prepared measurement sample solution in the measurement device so that the PIDS is 45 to 55%.
[0043]
As a method for preparing the sample liquid for measurement of the external additive, 0.4 g of the fine powder to be measured is placed in a beaker containing 100 ml of ethanol, and the mixture is stirred for 1 minute, so that the sample liquid is mixed with the measuring solvent. After that, ultrasonic dispersion treatment is performed for 3 minutes. Immediately after the processing is completed, a measurement sample solution is added to the measurement section of the measurement device so as to have the above-mentioned PIDS concentration. The measurement sample liquid prepared in this manner was measured within one minute.
[0044]
On the other hand, as a method of preparing a measurement sample liquid when measuring a fine powder from a toner externally added, 4 g of the sample toner to be measured is placed in a beaker containing 100 ml of ethanol, and stirred for 1 minute. After the measurement sample is mixed in, the ultrasonic dispersion treatment is performed for 1 minute.
[0045]
Next, toner particles are isolated from the dispersion by centrifugation or static decantation to obtain a dispersion of the external additive.
[0046]
The resulting dispersion is sonicated for 1 minute. Immediately after the processing is completed, a measurement sample solution is added to the measurement section of the measurement device so as to have the above-mentioned PIDS concentration. The measurement sample liquid prepared in this manner was measured within one minute.
[0047]
Method for producing silica fine particles
The silica fine particles used in the present invention generally include those produced by a wet method or a dry method, and in particular, those called so-called fumed silica produced by a dry method (vapor phase oxidation of a silicon halide compound). Is preferred from the viewpoint of fluidity. This is manufactured by a conventionally known technique.
[0048]
For example, it utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.
SiCl₄+ 2H₂+ O₂→ SiO₂+4 HCl
[0049]
In this production step, it is also possible to obtain a composite fine powder of silica and another metal oxide by using another metal halide compound such as aluminum chloride or titanium chloride together with a silicon halide compound. Of course, those using them are also included.
[0050]
By controlling the steps of this production method, it is possible to control the primary particle diameter of the silica fine particles.
[0051]
After the production, a desired external additive particle size distribution can be obtained by a post-treatment step such as a mechanical crushing treatment or a treatment for removing coarse particles.
[0052]
Further, the surface of the silica fine particles is hydrophilic derived from silanol groups present on the conventional silica surface, and the silica fine particles usable in the present invention are preferably those which have been made hydrophobic by a surface treatment described later.
[0053]
The particle size distribution of the silica fine particles is also greatly affected by this hydrophobic treatment. Therefore, the particle size distribution of the silica fine particles of the present invention is measured and evaluated in a state where the particle size distribution is adjusted by performing a post-process after the hydrophobic treatment.
[0054]
The surface treatment of silica fine particles that can be suitably used in the present invention will be described. The surface treatment is not particularly limited as long as the powder can be generally subjected to a hydrophobic treatment, but preferably a silane coupling agent or an oil shown below is used. It is possible.
[0055]
First, the hydrophobic treatment with a silane coupling agent will be described.
[0056]
The silane coupling agent that can be used is not particularly limited as long as it can react with the residual groups on the inorganic oxide fine particles or the adsorbed water to achieve uniform treatment, and can also stabilize the charge of the toner and impart fluidity. It does not do.
[0057]
As an example of a silane coupling agent, the following general formula
Rm SiYn
(R: alkoxy group
m: an integer of 1 to 3 Y: an alkyl group, a hydrocarbon group containing a vinyl group, a glycidoxy group, and a methacryl group, n: an integer of 1 to 3)
Are represented.
[0058]
Representative compounds of the silane coupling agent usable in the present invention include vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane. Silane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, etc. it can.
[0059]
More preferably, C_a  H_{2a + 1}-Si (OC_b  H_{2b + 1})₃
(A = 4-12, b = 1-3)
It is.
[0060]
Here, when a in the general formula is smaller than 4, the treatment is facilitated, but sufficient hydrophobicity cannot be achieved. If a is larger than 12, the hydrophobicity becomes sufficient, but the coalescence of the particles increases, and the fluidity-imparting ability decreases. If b is greater than 3, the reactivity will decrease and the hydrophobicity will not be sufficiently achieved. Therefore, a in the above general formula is 4 to 12, preferably 4 to 8, and b is 1 to 3, preferably 1 to 2.
[0061]
The treatment amount is preferably 1 to 50 parts by mass with respect to 100 parts by mass, and 3 to 40 parts by mass to uniformly treat the particles without coalescing.
[0062]
Next, oils used in the hydrophobizing treatment will be described.
[0063]
The oils that can be used for the hydrophobizing treatment of the silica fine particles of the present invention are not particularly limited as long as they can stabilize the charge of the toner and impart fluidity.
[0064]
Examples of usable oils include silicone oil such as dimethylpolysiloxane and methylhydrogenpolysiloxane, paraffin, and mineral oil. Among these, dimethylpolysiloxane is particularly preferred because of its excellent environmental stability, uniform treatment, high release property and high versatility.
[0065]
Among dimethylpolysiloxanes, from the viewpoint of ease of processing and uniformity, a grade having a particularly low viscosity characteristic is more preferable.
[0066]
The treatment amount is preferably 1 to 50 parts by mass with respect to 100 parts by mass, and 3 to 40 parts by mass to uniformly treat the particles without coalescing.
[0067]
The surface treatment method of the silica fine particles with these hydrophobizing agents includes, for example, a method of spraying the treating agent with the silica particles in a fluidized state, and a method of dropping droplets onto the silica particles that are mechanically stirred. A known method such as a method for performing the method can be used. Further, after performing the surface treatment, overheating may be performed for the purpose of accelerating the reaction or removing the solvent.
[0068]
The amount of the silica fine particles that can be used in the present invention is preferably 0.05 to 3.0 parts by mass based on 100 parts by mass of the toner particles.
[0069]
If the total amount of the silica fine particles is less than 0.05 parts by mass, fluidity cannot be imparted, and the phenomenon of density thinning and line stability due to insufficient supply of toner cannot be achieved. If the amount is more than 3.0 parts by mass, a large amount of released external additive is generated, and the released external additive causes a contamination of the developing portion, which causes problems such as contamination of the charging member and adhesion to the member.
[0070]
In the toner of the present invention, a known external additive can be used in addition to the above silica fine particles.
[0071]
Examples of external additives that can be used in combination are oxides of metals such as magnesium, zinc, aluminum, cerium, cobalt, iron, zirconium, chromium, manganese, strontium, tin and antimony; calcium titanate, magnesium titanate, titanic acid Composite metal oxides such as strontium; metal salts such as calcium carbonate, magnesium carbonate and aluminum carbonate; clay minerals such as kaolin; phosphoric acid compounds such as apatite; silicon compounds such as silicon carbide and silicon nitride; Examples include carbon powder and hydrotalcite compounds.
[0072]
Among these, fine powders such as zinc oxide, aluminum oxide, cobalt oxide, manganese dioxide, strontium titanate, magnesium titanate, and hydrotalcite compounds are preferred.
[0073]
Further, a known lubricant powder may be added to the toner. Examples of the lubricant powder include fluororesins such as polyethylene fluoride and polyvinylidene fluoride; fluorine compounds such as carbon fluoride; fatty acid metal salts such as zinc stearate; fatty acid derivatives such as fatty acids and fatty acid esters; and molybdenum sulfide.
[0074]
These fine particle powders can be used for controlling chargeability and toner characteristics. The method of use is not particularly limited.
[0075]
At this time, the amount of the fine particle powder used is preferably 0.005 to 2.0 parts by mass, more preferably 0.02 to 0.7 parts by mass, based on 100 parts by mass of the toner particles. Is preferred.
[0076]
The specific device for treating the surface of the toner particles with the silica fine particles and other external additives of the present invention is not particularly limited as long as sufficient characteristics can be obtained. Can be used. Examples of preferred mixing devices among these include a Henschel mixer, a super mixer, a ribocorn, a Nauta mixer, a spiral mixer, a Lodige mixer, a turbulizer, a cyclomix, a V-type blender, etc., among these. Henschel mixers, supermixers, and ribocorns are particularly preferred to achieve the proper fluidity and jetness indices of the present application.
[0077]
[Table 1]

[0078]
Specific methods for treating the surface of the toner base with the fine powder for surface treatment include coloring resin particles, the above-mentioned hydrophobized silica fine powder and the like, and other inorganic powder and lubricant powder as necessary. And thoroughly mixing with the mixing device described above.
[0079]
Next, a method for producing toner particles usable in the present invention will be described.
[0080]
In order to produce the toner particles according to the present invention, known methods such as a melt pulverization method and a polymerization method are used.
[0081]
As an example of the melt-pulverization method, a binder resin, wax, a pigment as a colorant, a dye, a charge control material, and if necessary, other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill, and then heated. Using a hot kneader such as a roll, kneader, or extruder, melt or knead the resin, disperse or dissolve the metal compound, pigment, or dye in the resin, cool and solidify, then pulverize, spheroidize, and classify To obtain the toner according to the present invention.
[0082]
In the classifying step, it is preferable to use a multi-segment classifier in terms of production efficiency.
[0083]
Examples of the polymerization method include mixing and dispersing a polymerizable monomer, a cross-linking agent, a polymerization initiator, a wax, a pigment as a colorant, a dye, or a magnetic substance, and other additives. The toner according to the present invention can be obtained by synthesizing polymerizable colored resin particles by suspension polymerization in an aqueous system in the presence of an agent, solid-liquid separation, drying and classification.
[0084]
As the suspension dispersion stabilizer, known ones can be used, and specific examples thereof include tricalcium phosphate, magnesium phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, calcium sulfate, silica, and alumina. Examples include inorganic compounds, and organic compounds such as polyvinyl alcohol, gelatin, metal salts of celluloses, and starch. It is preferable to use 0.2 to 10 parts by mass of these dispersants based on 100 parts by mass of the polymerizable monomer.
[0085]
The raw material of the toner particles of the present invention is not particularly limited, and a material known as a toner for electrophotography can be used.
[0086]
Colorants that can be used in the toner particles of the present invention include any suitable pigments or dyes. Toner colorants are well known and include, for example, black pigments such as carbon black, magnetic material, aniline black, acetylene black, lamp black, graphite or mixtures thereof, or the following yellow colorants / magenta colorants / cyan colorants. What is mixed and toned to black is used.
[0087]
As the yellow colorant, a compound represented by a condensed azo compound, an isoindolinone compound, an anthraquinone compound, an azo metal complex, a methine compound, an allylamide compound, or the like is used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180 and the like are preferably used.
[0088]
Examples of the magenta colorant include a condensed azo compound, a diketopyrrolopyrrole compound, an anthraquinone, a quinacridone compound, a basic dye lake compound, a naphthol compound, a benzimidazolone compound, a thioindigo compound, and a perylene compound. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 are particularly preferred.
[0089]
Such a pigment may be used alone, but it is more preferable to improve the sharpness of the pigment in combination with the dye and the pigment from the viewpoint of the image quality of a full-color image.
[0090]
Specific examples of the dye include, for example, C.I. I. Direct Red 1, C.I. I. Direct Blue 1, C.I. I. Direct Green 6 and the like.
[0091]
These are used in an amount necessary to maintain the optical density of the fixed image, and are usually used in an amount of 0.1 to 60 parts by mass, preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the binder resin. You.
[0092]
The binder resin used for the toner particles of the present invention is not particularly limited as long as it is used for producing a toner. Specific examples of the binder resin used in the resin for toner of the present invention include polymers of the following polymerizable monomers, or a mixture of polymers of the polymerizable monomers alone, or two or more kinds of polymers. And a copolymerization product of a hydrophilic monomer. More specifically, a styrene-acrylic acid copolymer or a styrene-methacrylic acid copolymer is preferred.
[0093]
It is also possible to use a known crosslinkable polymerizable monomer or chain transfer agent for the purpose of improving fixability.
[0094]
Further, the toner of the present invention preferably contains a known wax component for improving the releasability at the time of fixing. The wax component is not particularly limited as long as it maintains sufficient performance as a releasing property and a developing property at the time of fixing.
[0095]
Specific examples of the wax component include the following compounds.
[0096]
For example, silicone resin, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin such as low molecular weight polyethylene or low molecular weight polypropylene, aromatic petroleum Resin, chlorinated paraffin, paraffin wax and the like.
[0097]
Of these, waxes preferably used are low-molecular-weight polypropylene, by-products of low-molecular-weight polypropylene, low-molecular-weight polyester and ester-based waxes, and aliphatic derivatives.
[0098]
From these waxes, waxes obtained by fractionating waxes by molecular weight by various methods are also preferably used in the present invention. Further, after the fractionation, acid value, block copolymerization, and graft modification may be performed.
[0099]
As the particle size of the toner suitable for the present invention, a general toner particle size conventionally used in electrophotography can be used. The particle size of the toner is preferably 2 μm or more and 15 μm or less, more preferably 5 μm or more and 10 μm or less as measured by a Coulter Multisizer (manufactured by Coulter Inc.).
[0100]
When the volume average particle diameter of the toner is less than 2 μm, the effect of the present invention is hardly obtained even when the external additive of the present invention is used, which is not preferable. In particular, it is difficult to suppress a change in particle size during continuous durability, and this leads to deterioration of image quality due to deterioration of transferability in durability. Further, the toner having such a particle size tends to deteriorate image fog, and the tendency is not easily improved even when the external additive of the present invention is used.
[0101]
Further, when the volume average particle diameter of the toner is more than 15 μm, the charge-imparting property to the toner is reduced, and the toner is liable to be scattered in the apparatus and the image to be easily contaminated by toner leakage. In particular, such a tendency is remarkable in an early stage of use in a high humidity environment.
[0102]
As the toner shape suitable for the present invention, the number average diameter of circles in the particle number frequency distribution based on the number of toner is 2 to 10 μm, and the average circularity in the circularity frequency distribution is 0.920 to 0.995. Preferably, it is set to 0.980 to 0.995. Further, it is preferable that the circularity standard deviation indicating the distribution state of the circularity is less than 0.040.
[0103]
By precisely controlling the particle shape of the toner to these shapes, the transferability and durability stability of the toner are improved, and the effect of the present invention appears more effectively.
[0104]
In particular, when developing a minute spot latent image in electrophotography, it is effective that the average circularity is 0.920 or more. On the other hand, when the average circularity exceeds 0.995, the surface of the toner deteriorates remarkably, causing problems in durability and the like.
[0105]
Therefore, it is important that the shape of the toner suitable for the present invention maintain an appropriate circularity and a distribution state of an appropriate circularity.
[0106]
In particular, the above tendency becomes apparent when a full-color copying machine that develops / transfers a plurality of toner images is used. That is, in the generation of a full-color image, it is difficult to uniformly transfer the four-color toner images. Further, when an intermediate transfer member is used, problems are likely to occur in terms of color unevenness and color balance. It is difficult to output stably.
[0107]
The circularity of the toner and the distribution state of the circularity in the present invention are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, a flow type particle image measuring apparatus is used as an example of the measuring method. It measured using FPIA-1000 type (made by Toa Medical Electronics Co., Ltd.).
[0108]
Next, an image forming method suitable for the present invention will be described.
[0109]
The image forming method suitable in the present application is a one-component contact developing method that is at least a toner regulating member, a toner supply member, an electrostatic latent image carrier, and a transfer member.
[0110]
As the electrostatic latent image carrier, A-Se, Cds, ZnO₂A known photosensitive drum or photosensitive belt having a photoconductive insulating material layer such as OPC, OPC and A-Si is preferably used.
[0111]
Of these, OPC is particularly preferably used. The binder resin of the organic photosensitive layer in the OPC electrostatic latent image carrier is not particularly limited, and a known binder resin can be used. However, from the viewpoints of toner chargeability, transferability and filming, polycarbonate resin is used. And polyarylate resin.
[0112]
The charging step of the latent image carrier in the image forming method of the present invention is not particularly limited, and various charging methods can be used. Specifically, a corona discharge in which the charging means is not in contact with the electrostatic latent image carrier or a direct charging method in which a charging member is brought into contact with the electrostatic latent image carrier can be suitably used. Further, a charging method using a charging blade or a method using a conductive brush is also possible.
[0113]
The toner supply member in the image forming method of the present invention uses a rigid roller as the toner supply member, and a configuration in which the electrostatic latent image carrier is made flexible such as a belt, or a rigid body as the electrostatic latent image carrier is formed by toner. It is possible to adopt a configuration in which a flexible member such as an elastic body is used as the supply member.
[0114]
An elastic roller is preferably used when it is arranged to be pressed against a rigid electrostatic latent image carrier. Hereinafter, a system using a combination of an elastic roller and a rigid electrostatic latent image carrier will be described.
[0115]
In the development step suitable for the present invention, development is performed by bringing a toner supply member carrying toner into direct contact with the electrostatic latent image carrier. The rotation directions of the toner supply member and the electrostatic latent image carrier are set in the forward direction.
[0116]
The hardness of the elastic roller is preferably about 20 to 65 degrees (ASKER C), and more preferably 30 to 60 degrees, from the viewpoint of achieving both developability and durability. Known materials and structures can be used as the material of the elastic roller. In particular, solid rubber elastic bodies such as silicone rubber, urethane rubber and NBR, or foamed elastic bodies thereof are preferably used. Further, a known multi-layer structure roller having a coat layer different from the central portion on the surface can also be used. In addition, a known surface treatment may be performed for the purpose of imparting chargeability and transportability.
[0117]
As the surface shape of the toner supply member, it is preferable to control the surface roughness in order to achieve both high image quality and high durability. When the surface roughness of the toner supply member is set, for example, to Ra (μm) “JIS B 0601” of 0.2 to 3.0, both high image quality and high durability can be achieved. If the surface roughness Ra of the toner supply member exceeds 3.0, it becomes difficult not only to reduce the thickness of the toner layer on the toner supply member but also to improve the image quality because the chargeability of the toner is not improved. . By setting the ratio to 3.0 or less, the toner conveyance ability on the surface of the toner supply member is suppressed, the toner layer on the toner supply member is made thinner, and the number of times of contact between the toner supply member and the toner increases. Since the chargeability of the toner is also improved, the image quality is synergistically improved. On the other hand, when the surface roughness Ra is smaller than 0.2, it becomes difficult to control the toner coat amount.
[0118]
The toner on the toner supply member is regulated by a toner regulation member arranged to be in pressure contact with the surface of the toner supply member, and forms a toner layer on the toner supply member.
[0119]
The pressure that presses the toner regulating member against the surface of the toner supply member and regulates the layer thickness on the toner supply member can be appropriately adjusted so that the toner amount of the toner is constant and that the toner has an appropriate chargeability. preferable.
[0120]
As the material of the toner coating amount regulating member, it is preferable to select a material of a triboelectric series suitable for charging the toner to a desired polarity, and a rubber elastic material such as silicone rubber, urethane rubber, NBR, polyethylene terephthalate A synthetic resin elastic body such as, stainless steel, steel, metal elastic body such as phosphor bronze can be used, and a composite thereof, for example, a resin or rubber bonded to the metal elastic body so as to hit the sleeve contact portion, , May be coated.
[0121]
Further, an organic substance or an inorganic substance may be added to the elastic regulating member, may be melt-mixed, or may be dispersed. For example, the chargeability of the toner can be controlled by adding metal oxides, metal powders, ceramics, carbon allotropes, whiskers, inorganic fibers, dyes, pigments, surfactants, and the like. In particular, when the elastic body is a molded body such as rubber or resin, fine particles of metal oxide such as silica, alumina, titania, tin oxide, zirconia, and zinc oxide, carbon black, a charge control agent generally used for toner And the like.
[0122]
When a combination of a conductive regulating member and a toner supplying member is used, it is also preferable to apply a DC electric field and / or an AC electric field between the regulating member and the toner supplying member. By applying such an electric field, uniform thin layer coating and uniform chargeability are improved, and a sufficient image density can be achieved and a high quality image can be obtained.
[0123]
When durability is required for the elastic regulating member and the toner supply member, it is preferable that a resin or rubber is bonded to the metal elastic body so as to contact the sleeve contact portion, or a metal is applied.
[0124]
Further, the transfer method is not particularly limited, and a known transfer method of a contact or non-contact method can be used.
[0125]
【Example】
Hereinafter, the present invention will be described specifically with reference to Production Examples and Examples, but this does not limit the present invention in any way.
[0126]
Production example of fine silica powder
Silica fine particles were synthesized by a known dry method. Furthermore, the particle size of the silica fine particles was controlled by controlling the steps of this production method, and silica fine particles having an arbitrary particle size were synthesized. Further, after a surface treatment is carried out using a combination of a plurality of these silica fine particles and a surface treatment agent shown in Table 2 in an amount of 10 to 30% by weight, an appropriate crushing treatment and a treatment for removing coarse particles are performed. Silica fine particles with controlled peaks were synthesized.
[0127]
There are various methods for controlling the peak of the particle size frequency. In this example, the following method was used.
[0128]
{Circle around (1)} 0.04 to 1.0 μm: The temperature, pressure and stirring conditions for synthesizing silica fine particles by a dry method were adjusted by control. Specifically, a silica fine powder having a peak in the range of 0.04 to 1.0 μm was synthesized by appropriately controlling the time, pressure and temperature during the gas phase growth in the dry method.
[0129]
{Circle around (2)} 1.0 to 50 μm: Adjusted by controlling the conditions for crushing the surface-treated product. Specifically, (3) a silica fine powder having a peak in the range of 50 to 2000 μm is subjected to a crushing treatment using a crushing device (a mechanical mill crushing device, such as a ball mill or a micron mill). And silica fine powder having a peak in the range of 1.0 to 50 μm was synthesized. In the crushing process, samples having different crushing degrees were prepared depending on the mechanical strength.
[0130]
{Circle around (3)} 50-2000 μm: The characteristics and amount of the surface treatment agent at the time of the surface treatment and the treatment conditions (diluted with a solvent and spray-dried) were adjusted by control. Specifically, (2) the viscosity of the surface treatment agent, the solvent dilution concentration when spraying the surface treatment agent, and the discharge amount are appropriately controlled with respect to the silica fine powder having a peak in the range of 1.0 to 50 μm. Thus, a silica fine powder having a peak in the range of 50 to 2000 μm was synthesized.
[0131]
Table 2 shows the peak position of the particle size distribution of the obtained external additive, the surface treatment agent used, and the strength of the crushing treatment.
[0132]
[Table 2]

[0133]
Example of toner production
Example of toner production (1)
In a two-liter four-necked flask equipped with a high-speed stirrer TK-Homomixer,₃PO₄An aqueous solution was added, the rotation speed was adjusted to 9000 rpm, and the mixture was heated to 63 ° C. Here CaCl₂The aqueous solution is gradually added, and a fine hardly water-soluble dispersant Ca is added.₃(PO₄)₂The aqueous dispersion medium containing was prepared.
[0134]
on the other hand,

After sufficiently dispersing the above materials in a ball mill, the contents were isolated from the ball mill. The content obtained by adding a polymerization initiator to the content was charged into the aqueous dispersion medium and granulated while maintaining a rotation speed of 9000 rpm. Thereafter, the mixture was reacted at 65 ° C. for 4 hours while stirring with a paddle stirring blade, and then polymerized at 80 ° C. for 5 hours. After 5 hours, the remaining low molecular weight components were removed by vacuum distillation.
[0135]
After completion of the reaction, the suspension was cooled, and hydrochloric acid was added to the suspension to prepare a poorly water-soluble dispersant Ca.₃(PO₄)₂Was dissolved, filtered, washed with water and dried, and then classified to a desired particle size by air classification to obtain toner particles (1).
[0136]
With respect to 100 parts by mass of the toner particles (1) thus obtained, (1) 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3) 50 to 2000 μm, respectively. 1.5 parts by mass of silica fine particles (1) having a peak were mixed and charged into a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.).
[0137]
The Henschel mixer used was such that the baffle plate was set at 90 degrees with respect to the circumferential direction of the stirring blade, and the number of revolutions was set at 1800 revolutions. The toner (1) of the present invention was synthesized by mixing using this apparatus for 20 minutes.
[0138]
The weight average particle diameter of the obtained toner was 6.55 μm, the average circularity was 0.980, and the circularity standard deviation was 0.039.
[0139]
In addition, when the surface of the obtained toner was observed with a scanning electron microscope (such as S-4700 manufactured by FE SEM Hitachi), it was confirmed that silica fine particles had adhered to the surface of the toner particles. Furthermore, it was found that silica fine particles of 1 μm or more did not exist.
[0140]
This is presumably because silica fine particles of 1 μm or more were loosened and adhered to the surface of the colorant in the external addition treatment step of adhering the external additive to the surface of the toner particles. In addition, it can be seen from these results that silica fine particles having a size of 1 μm or more have a low cohesive force and can be easily crushed. Therefore, it is considered that the silica fine particles having a size of 1 μm or more are formed by agglomeration of silica fine particles having a particle size close to the primary particle diameter around the droplets of the surface treatment agent in the surface treatment step.
[0141]
Further, when the laser diffraction particle size distribution of the fine particles (1) used at this time was measured, it was found that (1) 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3) 50 to 2000 μm. Each had a peak in the range. Further, (1) the relationship between the particle size frequency (R2) belonging to the particle size of 0.04 to 1.0 μm and (3) the particle size frequency (R2) belonging to the particle size of 50 to 2000 μm (R2 / R1) Was 0.4.
[0142]
Toner production examples (2), (3)
Fine particles (2) having peaks in the ranges of (1) 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3) 50 to 2000 μm by replacing the external additive with the fine particles (1). The toners (2) and (3) of the invention were synthesized in the same manner as in the toner production example (1) except that the toners (3) and (3) were used.
[0143]
Further, when the laser diffraction particle size distribution of the fine particles used at this time was measured, it was found that (1) ranges from 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3) 50 to 2000 μm. It had a peak. Further, (1) the relationship between the particle size frequency (R2) belonging to the particle size of 0.04 to 1.0 μm and (3) the particle size frequency (R2) belonging to the particle size of 50 to 2000 μm (R2 / R1) As a result, the silica fine particle (2) was 0.5 and the silica fine particle (3) was 1.0.
[0144]
Example of toner production (4)
Replacing the external additive with the fine particles (1), (1) 0.04 to 1.0 μm, and (2) 0.5 parts by mass of the fine particles (4) each having a peak in the range of 1.0 to 50 μm. (2) Using 1.2 parts by mass of fine particles (7) each having a peak in the range of 1.0 to 50 μm and (3) 50 to 2000 μm, and further mixing 0.2 parts by mass of a hydrotalcite compound. Other than that, the toner (4) of the present invention was synthesized in the same manner as in the toner production example (1). Further, when the fine particles (4) and (7) used at this time were separately mixed and the laser diffraction particle size distribution was measured, (1) 0.04 to 1.0 μm, and (2) 1.0 to 50 μm. And (3) peaks in the range of 50 to 2000 μm. Furthermore, (1) the relationship between the particle size frequency (R2) belonging to the particle size of 0.04 to 1.0 μm and (3) the particle size frequency (R2) belonging to the particle size of 50 to 2000 μm (R2 / R1) Was 1.5.
[0145]
Example of toner production (5)
Pigment Yellow 180 was used instead of carbon black as the colorant used in toner production example (1), and 0.1 part by mass of strontium titanate was used instead of hydrotalcite, in the same manner as in toner production example (1). The toner (5) of the present invention was synthesized.
[0146]
Example of toner production (6)
The toner (6) of the present invention was synthesized in the same manner as in the toner production example (1) except that the colorant used in the toner production example (1) was changed from carbon black to Pigment Red 166.
[0147]
Example of toner production (7)
Pigment blue 15: 3 was used instead of carbon black for the colorant used in toner production example (1), and rutile-type titanium oxide was used for hydrotalcite. Inventive toner (7) was synthesized.
[0148]
Example of toner production (8)
In place of the fine particles (1) used in the toner production example (1), (1) 0.04 to 1.0 μm and (2) fine particles (4) each having a peak in the range of 1.0 to 50 μm are defined as 0. Toner production example (1) except that 0.6 parts by mass, (2) 1.0 to 50 μm, and (3) 0.5 parts by mass of fine particles (7) each having a peak in the range of 50 to 2000 μm are used. In the same manner as in the above, the toner (8) of the present invention was synthesized.
[0149]
In addition, when the fine particles (4) and (7) used at this time were separately mixed and the laser diffraction particle size distribution was measured, (R2 / R1) was 0.6.
[0150]
Example of toner production (9)
The amount of the fine particles (1) used in the toner production example (1) was 0.8 parts by mass, and (1) 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3). The toner (9) of the present invention was synthesized in the same manner as in the toner production example (1) except that 0.8 parts by mass of the fine particles (2) each having a peak in the range of 50 to 2000 μm was used.
[0151]
In addition, when the fine particles (1) and (2) used at this time were separately mixed and a laser diffraction particle size distribution was measured, (R2 / R1) was 0.5.
[0152]
Example of toner production (10)
The amount of the fine particles (1) used in the toner production example (1) was 0.4 parts by mass, and (1) 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3). 0.4 parts by mass of the fine particles (2) each having a peak in the range of 50 to 2000 μm, (1) 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3) 50 to 2000 μm. In the same manner as in the toner production example (1) except that 0.4 parts by mass of the fine particles (3) each having a peak in the range described above and 0.1 part by mass of titanium oxide are used. 10) was synthesized.
[0153]
Further, when the fine particles (1), (2) and (3) used at this time were separately mixed and the laser diffraction particle size distribution was measured, (R2 / R1) was 0.6.
[0154]
Example of toner production (11)

The above-mentioned materials are charged into a kneader-type mixer, and while mixing, the temperature is raised to 120 ° C. under no pressure, and the mixture is sufficiently premixed. Thereafter, the mixture was kneaded twice with three rolls to obtain a first kneaded material.
[0155]

The above materials were sufficiently premixed by a Henschel mixer, melt-kneaded by a twin-screw extruder, cooled, roughly crushed by a hammer mill to about 1 to 2 mm, and then finely crushed by an air jet fine crusher. . Further, after fine and coarse powders of the obtained finely pulverized material are strictly removed at the same time by a multi-segmentation classifier, a rotor is rotated to apply a mechanical impact force to a surface reforming apparatus of 1600 rpm (peripheral speed 80 m). / Sec) for 3 minutes by a batch process for surface treatment of the toner particles, and then classification by a multi-division classifier to obtain toner particles (2).
[0156]
With respect to 100 parts by mass of the toner particles (2) thus obtained, (1) 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3) 50 to 2000 μm, respectively. 1.8 parts by mass of the silica fine particles (1) having a peak were mixed, charged into a Henschel mixer, and mixed under the same conditions as in the toner production example (1) to synthesize the toner (1) of the present invention.
[0157]
The obtained toner had a circle-equivalent average particle diameter D1 of 7.2 μm, an average circularity of 0.968, and a circularity standard deviation of 0.034.
[0158]
Comparative toner production example (1)
1. Fine particles (4) having peaks in the range of (1) 0.04 to 1.0 μm and (2) 1.0 to 50 μm instead of the fine particles (1) used in the toner production example (1). Comparative toner (1) was synthesized in the same manner as in toner production example (1) except that 0 parts by mass and 0.1 part by mass of titanium oxide were used.
[0159]
Comparative toner production example (2)
Instead of the fine particles (1) used in the toner production example (1), 1.8 parts by mass of the fine particles (7) having peaks in the range of (2) 1.0 to 50 μm and (3) 50 to 2000 μm, respectively. A comparative toner (2) was synthesized in the same manner as in the toner production example (1) except for using the same.
[0160]
Comparative toner production example (3)
In place of the fine particles (1) used in the toner production example (1), (1) fine particles (4) having peaks in the range of 0.04 to 1.0 μm and (2) 1.0 to 50 μm, respectively. 0 parts by mass, (1) 0.04 to 1.0 μm, and (2) 1.0 parts by mass of fine particles (5) each having a peak in the range of 1.0 to 50 μm, and 0.1 parts by mass of titanium oxide. A comparative toner (3) was synthesized in the same manner as in the toner production example (1) except that the above was used.
[0161]
Further, when the fine particles (4) and (5) used at this time were separately mixed and the laser diffraction particle size distribution was measured, (1) 0.04 to 1.0 μm and (2) 1.0 to 50 μm Each had a peak in the range.
[0162]
Table 3 shows the obtained toner production examples and comparative production examples.
[0163]
[Table 3]

[0164]
An outline of an image forming apparatus used in the embodiment will be described below.
[0165]
In FIG. 1, reference numeral 1 denotes a photosensitive drum as a latent image carrier. The photosensitive drum 1 rotates in a direction indicated by an arrow A in FIG. An electrostatic latent image is formed on the surface.
[0166]
The electrostatic latent image is developed by the developing device 4 and is visualized as a toner image. The developing device 4 is disposed close to the photosensitive drum 1 and is configured to be detachable from the image forming apparatus main body as a process cartridge. ing. In this embodiment, so-called reversal development for forming a toner image on an exposed portion is performed.
[0167]
The visualized toner image on the photosensitive drum 1 is transferred by a transfer roller 9 to a paper 13 as a recording medium, and untransferred toner remaining on the photosensitive drum 1 without being transferred is scraped off by a cleaning blade 10 and discarded. The photosensitive drum 1 housed and cleaned in the toner container 11 repeats the above operation to form an image.
[0168]
On the other hand, the paper 13 to which the toner image has been transferred is subjected to a fixing process by the fixing device 12, and is discharged out of the device, thereby completing the printing operation.
[0169]
Next, the developing device 4 according to the present invention will be described with reference to FIG.
[0170]
In FIG. 3, reference numeral 14 denotes a developing container for storing the non-magnetic toner 8 as a one-component toner. An opening extending in the longitudinal direction in the developing container 14 has a toner disposed opposite to the photosensitive drum 1. A toner supply member 5 as a supply member is rotatably arranged, and the electrostatic latent image on the photoconductor 1 is developed and visualized by the non-magnetic toner 8 carried on the toner supply member 5.
[0171]
The toner supply member 5 is a roller having a coat layer containing a urethane component with respect to solid rubber having an Asker C hardness of 40 degrees.
[0172]
The toner supply member 5 is provided laterally with the right half peripheral surface shown in the drawing protruding into the developing container 14 at the opening of the developing container 14 and the left half peripheral surface being exposed outside the developing container 14. The surface of the toner supply member 5 exposed to the outside of the developing container 14 faces the photosensitive drum 1 located on the left side of the developing device 4 with a small gap. The toner supply member 5 is driven to rotate in the direction of arrow B in FIG. 1, and the surface thereof has appropriate unevenness. The unevenness reduces the probability of the toner supply member 5 rubbing against the non-magnetic toner 8. As a result, the conveyance of the non-magnetic toner 8 is favorably performed.
[0173]
A toner regulating member 7 is provided above the toner supply member 5 so as to be supported by a holding plate 15. The vicinity of the free end of the toner regulation member 7 is near the outer peripheral surface of the toner supply member 5. It is in contact with the surface. The toner regulating member 7 is made of a phosphor bronze thin metal plate having spring elasticity.
[0174]
By appropriately adjusting the contact pressure of the toner regulating member 7 with respect to the toner supply member 5, the amount of the toner riding on the toner supply member 5 is 0.5 g / m.²It was adjusted to become.
[0175]
Further, in FIG. 2, reference numeral 6 denotes a roller serving as a toner replenishing member. The roller 6 abuts on the upstream side in the rotation direction of the toner supply member with respect to the contact portion of the toner regulating member 7 with the surface of the toner supply member 5. And is rotatably supported.
[0176]
In the developing device 4 having the above configuration, the non-magnetic toner 8 in the developing container 14 is sent in the direction of the roller 6 with the rotation of the stirring member 19 in the direction of the arrow C during the developing operation.
[0177]
The non-magnetic toner 8 is conveyed to the vicinity of the toner supply member 5 by the rotation of the roller 6 in the direction of arrow D in the drawing, and is carried on the roller 6 at the contact portion between the toner supply member 5 and the roller 6. The non-magnetic toner 8 is frictionally charged by being rubbed with the toner supply member 5 and adheres to the toner supply member 5.
[0178]
Thereafter, the non-magnetic toner 8 is sent under pressure of the toner regulating member 7 with the rotation of the toner supply member 5 in the direction of arrow B, where it is subjected to appropriate triboelectric charging to form a thin layer on the toner supply member 5. After that, it is conveyed to a developing unit which is a part facing the photosensitive drum 1 and is subjected to development.
[0179]
Examples 1 to 20 and Comparative Examples 1 to 3
As described above, the toners of the toner production examples (1) to (20) and the comparative production examples (1) to (3) are filled in the toner containers by using the developing devices of FIGS. Using the image for evaluation adjusted so as to be 5%, the continuous durability of 6000 sheets of monocolor was performed, and the image quality and durability of the toner were evaluated.
[0180]
The image output was performed in two environments: a temperature of 15 ° C. and a humidity of 5% RH, and a temperature of 32 ° C. and a humidity of 70% RH.
[0181]
The above evaluation results are summarized in Tables 4 and 5 (evaluation criteria will be described later).
[0182]
[Table 4]

[0183]
[Table 5]

[0184]
In Examples 1 to 18, in the durability in such a low-temperature, low-humidity and high-temperature, high-humidity environment, the occurrence of streak-like images (developed streaks) is reduced as follows: (1) 0.04 to 1.0 μm (2) By using silica fine particles having at least peaks in the range of 1.0 to 50 μm and (3) of 50 to 2000 μm, toner is fused to the regulating member in the toner regulating portion in the developing container. It is considered that this is because sticking can be suppressed.
[0185]
Further, it is considered that the reason why toner scattering, toner leakage, and image fogging can be suppressed is that it is possible to suppress the deterioration of the durability of the toner and reduce the characteristic fluctuation due to the deterioration of the durability.
[0186]
Further, when the toner component in the developing device after the endurance was analyzed, in Examples 1 to 18, the toner particle size hardly changed from the initial particle size. Further, when the external additive was quantified, It was found that the element abundance derived from the agent also hardly changed from the initial stage. On the other hand, in Comparative Examples 1 to 3, the particle size and the amount of the external additive changed depending on the durability.
[0187]
For this reason, the reason why an image with stable transfer omission and line thickness with little deterioration was obtained in durability was that the selective consumption of toner and external additives during durability was reduced. It is considered that this is because
[0188]
Example 19
A full-color image forming embodiment used in this embodiment will be described.
As an example, an image forming method in which toner images of each color are developed on an electrostatic latent image carrier and sequentially transferred will be described with reference to FIG.
[0189]
Here, first, second, third, and fourth image forming units 29a, 29b, 29c, and 29d are arranged side by side, and each image forming unit is a dedicated electrostatic latent image holder, a so-called photosensitive drum. 19a, 19b, 19c and 19d.
[0190]
The photosensitive drums 19a, 19b, 19c and 19d have latent image forming means 23a, 23b, 23c and 23d, developing sections 17a, 17b, 17c and 17d, transfer discharge sections 24a, 24b, 24c and 24d, and cleaning on the outer peripheral side. Parts 18a, 18b, 18c and 18d are arranged.
[0191]
With such a configuration, first, for example, a latent image of a yellow component color in a document image is formed on the photosensitive drum 19a of the first image forming unit 29a by the latent image forming unit 23a. The latent image is converted into a visible image by a toner having a yellow toner of the developing unit 17a, and is transferred to a recording material S as a transfer material at a transfer unit 24a.
[0192]
While the yellow image is being transferred to the transfer material 25 as described above, the latent image of the magenta component color is formed on the photosensitive drum 19b in the second image forming section 29b, and subsequently the developing unit 17b has the magenta toner. A visible image is formed by the toner. This visible image (magenta toner image) is transferred onto the transfer material S at a predetermined position when the transfer material S, which has been transferred by the first image forming unit 29a, is carried into the transfer unit 24b. You.
[0193]
Thereafter, cyan and black images are formed by the third and fourth image forming units 29c and 29d in the same manner as described above, and the cyan and black colors are transferred onto the same transfer material S in a superimposed manner. You do it. When such an image forming process is completed, the transfer material S is conveyed to the fixing unit 22, where the image on the transfer material S is fixed. Thus, a multicolor image is obtained on the transfer material S. After the transfer, the photosensitive drums 19a, 19b, 19c, and 19d are cleaned of residual toner by the cleaning units 18a, 18b, 18c, and 18d, and are provided for a subsequent latent image formation.
[0194]
In the image forming apparatus, the transport belt 25 is used for transporting the recording material S as a transfer material. In FIG. 3, the transfer material S is transported from right to left. The sheet passes through the transfer sections 24a, 24b, 24c and 24d in the image forming sections 29a, 29b, 29c and 29d and undergoes transfer.
[0195]
In this image forming method, a transport belt using a mesh of Tetron (registered trademark) fiber, a polyethylene terephthalate-based resin, a polyimide-based resin, and a urethane-based as a transport means for transporting the transfer material S from the viewpoint of ease of processing and durability. A conveyor belt using a thin dielectric sheet such as a resin is used.
[0196]
When the transfer material S passes through the fourth image forming unit 29d, an AC voltage is applied to the charge eliminator 20, the transfer material S is discharged, separated from the belt 25, and then enters the fixing device 22, where the image is fixed and discharged. It is discharged from the outlet 26.
[0197]
Since the toner of the present invention has excellent transferability, the transferability of the toner in each transfer can be made uniform with the same transfer current even if the charging of the conveying means increases each time the transfer is repeated, and a high-quality high-quality image can be obtained. Will be.
[0198]
Using this full-color image forming apparatus, toner (4), toner (5), toner (6), and toner (7) are used for developing units 17-a, 17-b, 17-c, and 17-d to form a full-color image. An endurance test was performed on A4 size paper under the conditions of a temperature of 23 ° C. and a humidity of 50% in a mode of 5000 continuous horizontal line pattern images.
[0199]
Image rating:
When the development quality, transferability, development streak, and fog were evaluated for the initial and durable images, images comparable to any of them were obtained. Further, when toner scattering near the developing device at the end of the endurance was observed, the level was almost no problem.
[0200]
From the above, it has been clarified that a practical full-color image can be formed using the external additive.
[0201]
The reason why streak-like images (development streaks) do not occur during such durability is as follows: (1) 0.04 to 1.0 μm, (2) 1.0 to 50 μm, and (3) 50 to 2000 μm. It is considered that the use of the silica fine particles having at least a peak in each of the ranges makes it possible to suppress the fusion and fixation of the toner to the regulating member in the toner regulating portion in the developing container.
[0202]
Further, it is considered that the reason why the toner scattering, the toner leakage, and the generation of the image fogging can be suppressed is that the deterioration in the durability of the toner can be suppressed, and the characteristic fluctuation due to the deterioration in the durability can be reduced.
[0203]
In addition, when the toner components in the developing device after the durability were analyzed, the toner particle size hardly changed from the initial particle size, and the external additive was quantified. It turns out that it has hardly changed from the beginning.
[0204]
For this reason, the reason why an image with stable transfer omission and line thickness with little deterioration was obtained in durability was that the selective consumption of toner and external additives during durability was reduced. It is considered that this is because
[0205]
Therefore, it was found that the toner using the silica particles having a preferable particle size distribution in the present invention was excellent in matching with the developing method as in the present embodiment.
[0206]
Further, such an effect is considered to be more conspicuous in the non-magnetic one-component contact developing system of the embodiment of the present invention, considering the charging behavior of the regulated portion of the developing device.
[0207]
The evaluation criteria shown in this example are shown below.
[0208]
Printout image evaluation
(1) Image quality
The density of 40 points in the sample of the tenth solid black pattern is measured. The average value of each of 5 points of high density and 5 points of low density was determined, and the results were ranked according to the difference. The density was measured with a reflection densitometer RD918 (manufactured by Macbeth). The image density was measured by using a "Macbeth reflection densitometer" (manufactured by Macbeth) with respect to the printout image of a white background portion having a document density of 0.00.
A: Very good, density difference is less than 0.1
B: Good Density difference is 0.1 or more and less than 0.2
C: Possible Density difference is 0.2 or more and less than 0.3
D: No problem in practical use The density difference is 0.3 or more and less than 0.5
E: impractical Density difference is 0.5 or more
[0209]
(2) Transferability
An all-white image is output, and the fog density (%) is calculated from the difference between the whiteness of the white background portion of the printout image and the whiteness of the transfer paper measured by a "Reflectometer" (manufactured by Tokyo Denshoku Co., Ltd.). Fog was evaluated and used as an index of charging stability.
A: Very good No transfer omission observed
B: Good Transfer omission is observed but hardly noticeable
C: Possible Transfer missing but no problem
D: No problem in practical use.
E: Unusable level at which transfer omission is a serious problem
[0210]
(3) fat
The image shown in FIG. 4 is output during endurance, and the average of 10 measurements of {width a} and {width b} from the output image is applied to the measurement formula shown in FIG. 4 to calculate the character fattening rate (%). We evaluated character fattening.
A: Less than 110%
B: 110% or more and less than 130%
C: 130% or more and less than 150
D: 150% or more and less than 170
E: 190% or more
[0211]
(4) Development line
A 25% halftone image was output, and the degree of development streaks on the image was visually evaluated.
A: Very good (not generated)
B: good (almost no occurrence)
C: Practical possible (several weak stripes are generated, but this is not a problem in practical use)
D: Difficult for practical use (Many weak streaks occur, which is a practically problematic level)
E: Impossible (significant streaks are generated and are not practical)
[0212]
(5) Fog
The fog density (%) was calculated from the difference between the whiteness of the white background portion of the printout image and the whiteness of the transfer paper measured by a "Reflectometer" (manufactured by Tokyo Denshoku Co., Ltd.), and the image fog was evaluated.
A: Very good (less than 1.0%)
B: Good (1.0% or more, less than 2.0%)
C: Practical (2.0% or more and less than 3.0%)
D: Practical difficulty (3.0% or more and less than 4.0%)
E: Not practical (more than 4%)
[0213]
(6) toner scattering
The process cartridge after the endurance was observed, and the occurrence level of in-machine contamination caused by toner scattering and leakage was visually evaluated.
A: Very good (no contamination at all)
B: Good (slight contamination but no practical problem)
C: acceptable (contaminated, but practical)
D: Somewhat problematic (contamination was recognized and there was some problem in continuous use)
E: impractical (contamination is remarkable and impractical)
[0214]
【The invention's effect】
As described above, according to the toner and the image forming method of the present invention, it is possible to obtain a toner and an image forming method which suppress deterioration of image quality in durability and have good transferability. Further, by suppressing fusion to the regulating member as much as possible, it is possible to obtain a toner in which development streaks hardly occur and an image forming method. Further, since the chargeability of the toner is stabilized, there is almost no image fogging at the initial stage and during the durability, and an effect of preventing contamination inside the apparatus due to toner scattering can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a non-magnetic one-component image forming apparatus suitable for the present invention.
FIG. 2 is a schematic view of a developing portion of a non-magnetic one-component image forming apparatus suitable for the present invention.
FIG. 3 is a schematic view of a full-color image forming apparatus as an example suitable for the present invention.
FIG. 4 is a schematic diagram of an image for measuring character fatness.
[Explanation of symbols]
1 Photoconductor drum (latent image carrier)
2 Charging roller
3 Laser light
4 Developing container
5 Toner supply member
7 Toner regulating member
9 Transfer roller
10 Cleaning mechanism
13 Transfer material
12 Fixing device
17a color developing container 1
17b color developing container 2
17c color developing container 3
17d color developing container 4

Claims (40)

A toner having at least a binder resin and a colorant, and a toner having an external additive on the surface of the toner particles,
The external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) 1.0 to 50 μm,
{Circle around (3)} Non-magnetic one-component toner characterized by externally adding silica fine particles (a) having at least a peak in the range of 50 to 2000 μm. 2. The toner according to claim 1, wherein the silica fine particles (a) are used in an amount of 0.05 to 3.0 parts by mass based on 100 parts by mass of the toner particles. The toner according to claim 1, wherein the silica fine particles (a) of the external additive are particles that have been subjected to a silane coupling agent treatment or a silicone oil treatment. 4. The external additive silica fine particle (a) as a silane coupling agent treating agent selected from hexamethylenedisilane, methyltrimethoxysilane and hydroxypropyltrimethoxysilane. Toner. In the volume particle size distribution measured by a laser diffraction type particle size distribution analyzer, the external additive has (1) a particle size frequency (R2) belonging to a particle size of 0.04 to 1.0 μm, and (3) a particle size of 50 to 2000 μm. The relationship with the granularity frequency (R2) to which it belongs is 0.1> R2 / R1> 5.0.
The toner according to any one of claims 1 to 4, wherein the following relationship is satisfied. The toner according to any one of claims 1 to 5, further comprising a hydrotalcite compound in addition to the silica fine particles (a). In the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the average circularity of the toner is 0.920 to 0.995, and the circularity standard deviation is 0.040 or less. The toner according to any one of claims 1 to 6, wherein In the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the average circularity of the toner is 0.950 to 0.990, and the circularity standard deviation is 0.040 or less. The toner according to any one of claims 1 to 6, wherein The toner according to any one of claims 1 to 8, wherein the toner particles contain a release agent component. A toner having at least a binder resin and a colorant, and a toner having an external additive on the surface of the toner particles,
The external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) silica fine particles (b) each having at least a peak in the range of 1.0 to 50 μm;
(2) 1.0 to 50 μm,
{Circle around (3)} A non-magnetic one-component toner, characterized by externally adding two types of silica fine particles having different particle size distributions of silica fine particles (c) each having at least a peak in the range of 50 to 2000 μm. The silica fine particles (b) are used in an amount of 0.05 to 2.0 parts by mass and the silica fine particles (c) are used in an amount of 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the toner particles. The toner according to claim 10, wherein The silica fine particles (b) of the external additive are particles subjected to a silane coupling agent treatment and a silicone oil treatment, and the silica fine particles (c) are particles subjected to a silicone oil treatment. The toner according to claim 10, wherein: The silane coupling agent treating agent of the silica fine particles (b) of the external additive is selected from hexamethylenedisilane, methyltrimethoxysilane, and hydroxypropyltrimethoxysilane. Toner. In the volume particle size distribution measured by a laser diffraction type particle size distribution analyzer, the external additive has (1) a particle size frequency (R2) belonging to a particle size of 0.04 to 1.0 μm, and (3) a particle size of 50 to 2000 μm. The relationship with the granularity frequency (R2) to which it belongs is 0.1> R2 / R1> 5.0.
14. The toner according to claim 10, wherein the following relationship is satisfied. 15. The toner according to claim 10, further comprising a hydrotalcite compound in addition to the silica fine particles (b) and the silica fine particles (c). In the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the average circularity of the toner is 0.920 to 0.995, and the circularity standard deviation is 0.040 or less. The toner according to any one of claims 10 to 15, wherein In the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the average circularity of the toner is 0.950 to 0.990, and the circularity standard deviation is 0.040 or less. The toner according to any one of claims 10 to 15, wherein 18. The toner according to claim 10, wherein the toner particles contain a release agent component. In a contact developing type image forming method including at least a toner regulating member, a toner supply member, an electrostatic latent image carrier, and a transfer member,
The toner used is a toner particle comprising at least a binder resin and a colorant, and a toner having an external additive on the surface of the toner particle,
The external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) 1.0 to 50 μm,
{Circle around (3)} A non-magnetic one-component toner characterized by externally adding silica fine particles (a) having at least a peak in the range of 50 to 2000 μm. 20. The image forming method according to claim 19, wherein the toner supply member is an elastic roller, and the elastic roller has a hardness of 20 to 65 degrees. 21. The image forming method according to claim 19, wherein a coating amount of the toner layer on the toner supply member is 0.2 mg / cm ² or more and 1.0 mg / cm ² or less. The image forming method according to any one of claims 19 to 21, wherein the silica fine particles (a) are used in an amount of 0.05 to 3.0 parts by mass based on 100 parts by mass of the toner particles. 23. The image forming method according to claim 19, wherein the silica fine particles (a) of the external additive are particles that have been subjected to a silane coupling agent treatment or a silicone oil treatment. The silane coupling agent treating agent for the silica fine particles (a) as the external additive is selected from hexamethylenedisilane, methyltrimethoxysilane, and hydroxypropyltrimethoxysilane. The image forming method according to any one of the above. In the volume particle size distribution measured by a laser diffraction type particle size distribution analyzer, the external additive has (1) a particle size frequency (R2) belonging to a particle size of 0.04 to 1.0 μm, and (3) a particle size of 50 to 2000 μm. The relationship with the granularity frequency (R2) to which it belongs is 0.1> R2 / R1> 5.0.
The image forming method according to any one of claims 19 to 24, wherein the following relationship is satisfied. The image forming method according to any one of claims 19 to 25, further comprising a hydrotalcite compound in addition to the silica fine particles (a). In the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the average circularity of the toner is 0.920 to 0.995, and the circularity standard deviation is 0.040 or less. The image forming method according to any one of claims 19 to 26, wherein: In the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the average circularity of the toner is 0.950 to 0.990, and the circularity standard deviation is 0.040 or less. The image forming method according to any one of claims 19 to 26, wherein: 29. The image forming method according to claim 19, wherein the toner particles contain a release agent component. In a contact developing type image forming method including at least a toner regulating member, a toner supply member, an electrostatic latent image carrier, and a transfer member,
The toner used is a toner particle comprising at least a binder resin and a colorant, and a toner having an external additive on the surface of the toner particle,
The external additive, in the volume particle size distribution by a laser diffraction type particle size distribution meter,
(1) 0.04 to 1.0 μm,
(2) silica fine particles (b) each having at least a peak in the range of 1.0 to 50 μm;
(2) 1.0 to 50 μm,
{Circle around (3)} A non-magnetic one-component toner characterized by externally adding two types of silica fine particles having different particle size distributions of silica fine particles (c) each having at least a peak in the range of 50 to 2000 μm. Image forming method. 31. The image forming method according to claim 30, wherein the toner supply member is an elastic roller, and the elastic roller has a hardness of 20 to 65 degrees. 32. The image forming method according to claim 30, wherein a coating amount of the toner layer on the toner supply member is 0.2 mg / cm ² or more and 1.0 mg / cm ² or less. The silica fine particles (b) are used in an amount of 0.05 to 2.0 parts by mass and the silica fine particles (c) are used in an amount of 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the toner particles. The image forming method according to any one of claims 30 to 32. The silica fine particles (b) of the external additive are particles subjected to a silane coupling agent treatment and a silicone oil treatment, and the silica fine particles (c) are particles subjected to a silicone oil treatment. The image forming method according to any one of claims 30 to 33, wherein: 35. The external additive according to claim 34, wherein the silane coupling agent treating agent of the silica fine particles (b) is selected from hexamethylenedisilane, methyltrimethoxysilane, and hydroxypropyltrimethoxysilane. Image forming method. In the volume particle size distribution measured by a laser diffraction type particle size distribution analyzer, the external additive has (1) a particle size frequency (R2) belonging to a particle size of 0.04 to 1.0 μm, and (3) a particle size of 50 to 2000 μm. The relationship with the granularity frequency (R2) to which it belongs is 0.1> R2 / R1> 5.0.
The image forming method according to any one of claims 30 to 35, wherein the following relationship is satisfied. The image forming method according to any one of claims 30 to 36, further comprising a hydrotalcite compound in addition to the silica fine particles (b) and the silica fine particles (c). In the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the average circularity of the toner is 0.920 to 0.995, and the circularity standard deviation is 0.040 or less. The image forming method according to any one of claims 30 to 37, wherein: In the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device, the average circularity of the toner is 0.950 to 0.990, and the circularity standard deviation is 0.040 or less. The image forming method according to any one of claims 30 to 37, wherein: The image forming method according to any one of claims 30 to 39, wherein the toner particles contain a release agent component.

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