JP3953121B2 - Toner for developing electrostatic image and image forming method - Google Patents

Description

【００２８】
上式中、Ｌは粒子の周囲長（μｍ）、Ａは粒子の投影面積（μｍ²）を表す。
【００２９】
上式中のＬ及びＡは、粒子を投影し、その投影したときのＬ及びＡを測定するが、具体的には投影し、それのＬ及びＡを個々をｎ＝１００〜１０００の平均値を画像解析装置で測定する。
【００３０】
本発明の目的をより良く達成するトナーは、上記特徴を有する着色粒子より作られたトナーであり、比較的球形に近い形状を有すると共に、大きな表面積を有するトナーであり、特定の形状、大きな表面積を有するため、上記した本発明の諸目的を達成し得るものと推察される。
【００３１】
本発明の実施に当たって用いられる素材及び態様につきさらに説明する。
【００３２】
トナー樹脂を構成するモノマー（単量体）としては、具体的には、スチレン、ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、α−メチルスチレン、ｐ−クロロスチレン、３，４−ジクロロスチレン、ｐ−フェニルスチレン、ｐ−エチルスチレン、２，４−ジメチルスチレン、ｐ−ｔ−ブチルスチレン、ｐ−ｎ−ヘキシルスチレン、ｐ−ｎ−オクチルスチレン、ｐ−ｎ−ノニルスチレン、ｐ−ｎ−デシルスチレン、ｐ−ｎ−ドデシルスチレンの様なスチレンあるいはスチレン誘導体、ビニルナフタレンの如き芳香族ビニル化合物；メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ−ブチル、メタクリル酸イソプロピル、メタクリル酸イソブチル、メタクリル酸ｔ−ブチル、メタクリル酸ｎ−オクチル、メタクリル酸２−エチルヘキシル、メタクリル酸ステアリル、メタクリル酸ラウリル、メタクリル酸フェニル、メタクリル酸ジエチルアミノエチル、メタクリル酸ジメチルアミノエチル等のメタクリル酸エステル誘導体、アクリル酸メチル、アクリル酸エチル、アクリル酸イソプロピル、アクリル酸ｎ−ブチル、アクリル酸ｔ−ブチル、アクリル酸イソブチル、アクリル酸ｎ−オクチル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸ラウリル、アクリル酸フェニル等のアクリル酸エステル誘導体の如きα−メチレン脂肪族モノカルボン酸エステル類；エチレン、プロピレン、イソブチレン等のオレフィン類；塩化ビニル、塩化ビニリデン、臭化ビニル、フッ化ビニル、フッ化ビニリデン等のハロゲン系ビニル類；プロピオン酸ビニル、酢酸ビニル、ベンゾエ酸ビニル等のビニルエステル類；ビニルメチルエーテル、ビニルエチルエーテル等のビニルエーテル類；ビニルメチルケトン、ビニルエチルケトン、ビニルヘキシルケトン等のビニルケトン類；Ｎ−ビニルカルバゾール、Ｎ−ビニルインドール、Ｎ−ビニルピロリドン等のＮ−ビニル化合物、アクリロニトリル、メタクリロニトリル、アクリルアミド等のアクリル酸あるいはメタクリル酸誘導体がある。これらの単量体の中でも、芳香族ビニル化合物及びα−メチレン脂肪族モノカルボン酸エステルが好ましい。
【００３３】
これらビニル系単量体は単独あるいは組み合わせて使用し、共重合体を得てトナーに使用することができる。また、樹脂を構成する単量体としてイオン性解離基を有するものを組み合わせて用いることが出来る。例えば、カルボキシ基、スルホ基、ホスホ基等の置換基を単量体の構成基として有するもので、具体的には、アクリル酸、メタクリル酸、マレイン酸、イタコン酸、ケイ皮酸、フマール酸、マレイン酸モノアルキルエステル、イタコン酸モノアルキルエステル、スチレンスルフォン酸、アリルスルフォコハク酸、２−アクリルアミド−２−メチルプロパンスルフォン酸、アシッドホスホオキシエチルメタクリレート、３−クロロ−２−アシッドホスホオキシプロピルメタクリレート等があげられる。
【００３４】
本発明において、上述して得られた樹脂は、特に乳化重合法によって得られた場合は、微粒子状態で得られるので、凝集剤を使用して、更に水に無限溶解する溶媒を添加し、得られた樹脂のガラス転移点以上に加熱処理することにより、所望の粒径の粒子（トナー）とすることが出来る。
【００３５】
本発明のトナーを製造するに際して、使用される凝集剤としては特に限定されるものでは無いが、金属塩から選択されるものが好適に使用される。具体的には、一価の金属として例えばナトリウム、カリウム、リチウム等のアルカリ金属の塩、二価の金属として例えばカルシウム、マグネシウム等のアルカリ土類の金属塩、マンガン、銅等の二価の金属の塩、鉄、アルミニウム等の三価の金属の塩等があげられ、具体的な塩としては、塩化ナトリウム、塩化カリウム、塩化リチウム、塩化カルシウム、安価亜鉛、硫酸銅、硫酸マグネシウム、硫酸マンガン等を挙げることができる。これらは組み合わせて使用してもよい。
【００３６】
これらの凝集剤は臨界凝集濃度以上添加して使用される。この臨界凝集濃度とは、水性分散物の安定性に関する指標であり、凝集剤を添加して凝集が発生する濃度を示すものである。この臨界凝集濃度は、乳化された成分及び分散剤自体によって大きく変化するものである。例えば、岡村誠三他著「高分子化学 Ｖｏｌ．１７、ｐ６０１（１９６０）日本高分子学会編」等に記述されており、詳細な臨界凝集濃度を求めることができる。また、別な手法として、目的とする粒子分散液に所望の塩を濃度変えて添加し、その分散液のζ（ゼータ）電位を測定し、この値が変化する塩濃度を臨界凝集濃度として求めることもできる。
【００３７】
本発明に用いられる凝集剤の添加量は、臨界凝集濃度以上であればよいが、好ましくは臨界凝集濃度の１．２倍以上、さらに好ましくは１．５倍以上添加することがよい。
【００３８】
使用する水に無限溶解する溶媒とは、着色された重合体分散液、すなわち水性分散液に対して無限溶解する溶媒を示し、この溶媒は、本発明に於いては形成された樹脂を溶解させないものが選択される。具体的には、メタノール、エタノール、プロパノール、イソプロパノール、ｔ−ブタノール、メトキシエタノール、ブトキシエタノール等のアルコール類、アセトニトリル等のニトリル類、ジオキサン等のエーテル類をあげることができる。特に、エタノール、プロパノール、イソプロパノールが好ましい。
【００３９】
この無限溶解する溶媒の添加量は、凝集剤を添加した重合体含有分散液に対して１〜３００体積％が好ましい。
【００４０】
本発明のトナーに用いる樹脂を形成する重合方法としては種々の方法を使用することができるが、特に好適な方法としては上述した乳化重合法である。
【００４１】
本発明のトナーには各種の着色剤、定着性改良剤の如き特性改良剤を使用出来る。使用できる着色剤としてはカーボンブラック、磁性体、染料、顔料等を任意に使用することができ、カーボンブラックとしてはチャネルブラック、ファーネスブラック、アセチレンブラック、サーマルブラック・ランプブラック等が使用される。磁性体としては鉄、ニッケル、コバルト等の強磁性金属、これらの金属を含む合金、フェライト、マグネタイト等の強磁性金属の化合物、強磁性金属を含まないが熱処理する事により強磁性を示す合金、例えばマンガン−銅−アルミニウム、マンガン−銅−錫等のホイスラー合金と呼ばれる種類の合金、二酸化クロム等を用いる事ができる。染料としてはＣ．Ｉ．ソルベントレッド１、同４９、同５２、同５８、同６３、同１１１、同１２２、Ｃ．Ｉ．ソルベントイエロー１９、同４４、同７７、同７９、同８１、同８２、同９３、同９８、同１０３、同１０４、同１１２、同１６２、Ｃ．Ｉ．ソルベントブルー２５、同３６、同６０、同７０、同９３、同９５等を用いる事ができ、またこれらの混合物も用いる事ができる。顔料としてはＣ．Ｉ．ピグメントレッド５、同４８：１、同５３：１、同５７：１、同１２２、同１３９、同１４４、同１４９、同１６６、同１７７、同１７８、同２２２、Ｃ．Ｉ．ピグメントオレンジ３１、同４３、Ｃ．Ｉ．ピグメントイエロー１４、同１７、同９３、同９４、同１３８、Ｃ．Ｉ．ピグメントグリーン７、Ｃ．Ｉ．ピグメントブルー１５：３、同６０等を用いる事ができ、これらの混合物も用いる事ができる。これらの着色剤は数平均一次粒子径は、概ね１０〜２００ｎｍ程度のものをトナーに分散して用いるのが好ましい。
【００４２】
着色剤の添加方法としては、本発明のトナーを乳化重合法で調製する場合、重合体自体を乳化重合法で調製し、ついで、凝集剤を添加することで凝集させる段階で添加する方法や、単量体を重合させる段階で着色剤を添加する方法等を使用することができる。なお、着色剤は重合体を調整する段階で添加する場合はラジカル重合性を阻害しない様に表面をカップリング剤等で処理して使用することが好ましい。
【００４３】
さらに、定着性改良剤としての低分子量ポリプロピレン（数平均分子量＝１，５００〜９，０００）や低分子量ポリエチレン等を添加してもよい。また、荷電制御剤としてアゾ系金属錯体、４級アンモニウム塩等を用いてもよい。これらの特性改良剤は、着色剤と同じ方法でトナーに添加されるのが通常である。
【００４４】
また、流動性付与の観点から、無機微粒子、有機微粒子を重合して得られた着色粒子に添加してもよい。この場合、無機微粒子の使用が好ましく、シリカ、チタニア、アルミナ等の無機酸化物粒子の使用が好ましく、さらに、これら無機微粒子はシランカップリング剤やチタンカップリング剤等によって疎水化処理されていることが好ましい。
【００４５】
本発明のトナーは前述の重合体自体を複数個会合させることで製造することができるものであるが、この場合、重合体粒子の分散液に対して撹拌下、凝集剤である金属塩を臨界凝集濃度以上の量を添加し、更に、前述した水に無限溶解する溶媒を添加、さらに重合体のガラス転移点温度以上に加熱処理することで得ることができる。
【００４６】
本発明のトナーはＢＥＴ値比表面積が５ｍ²／ｇ以上であることが望ましく、技術的な観点からは１５０ｍ²／ｇ以下であるが、好ましくは１００ｍ²／ｇ以下であり、特に好ましくは５〜５０ｍ²／ｇである。
【００４７】
又、本発明の着色粒子はトナーは形状係数が１．０１〜１．５であることが望ましいが、形状係数は１．０５〜１．３であることがさらに好ましい。
【００４８】
本発明のトナーを製造する方法は、上述の様に、特に限定されるものでは無いが、好ましくは特開平５−２６５２５２号、同６−３２９９４７号公報、特願平６−２２３９５３号出願に記載の方法が使用される。すなわち、樹脂及び着色剤等より構成される微粒子を複数会合させる方法、特に水中にてこれらを臨界凝集濃度以上の濃度以上の凝集剤及び水に対して無限溶解する有機溶媒で処理する方法が好ましく使用されている。さらに、形成された重合体自体のガラス転移点温度以上で加熱融着することによって本発明のＢＥＴ値比表面積及び形状係数を有するトナーを形成することができる。
【００４９】
本発明のトナー自体の粒径は、任意であるが、小粒径のものが本発明の効果を奏しやすく、かつ改良効果の発揮度も大きく、体積平均粒径で２〜１０μｍのものが好ましく、特に３〜９μｍのものが好ましい。この粒径は、凝集剤の濃度や有機溶媒の添加量、さらには重合体自体の組成によって制御することができる。
【００５０】
本発明のトナーは、例えば磁性体を含有させて一成分磁性トナーとして使用する場合、いわゆるキャリアと混合して二成分現像剤として使用する場合、非磁性トナーを単独で使用する場合等が考えられいずれも好適に使用することができるが、特に本発明ではキャリアと混合して使用する二成分現像剤として使用するのが好ましい。
【００５１】
二成分現像剤を構成するキャリアとしては鉄、フェライト等の磁性材料粒子のみで構成される非被覆キャリア、あるいは磁性材料粒子表面を樹脂等によって被覆した樹脂被覆キャリアのいずれを使用してもよい。このキャリアの平均粒径は体積平均粒径で３０〜１５０μｍが好ましい。また、被覆するための樹脂としては特に限定されるものでは無いが、例えばスチレン−アクリル酸エステル樹脂、シリコーン樹脂をあげることができる。
【００５２】
本発明のトナーが使用できる現像方式としては特に限定されず、接触現像方式あるいは非接触現像方式等に好適に使用することができる。接触方式の現像としては、本発明のトナーを有する現像剤の層厚は現像領域に於いて０．１〜８ｍｍ、好ましくは０．４〜５ｍｍとし、現像領域において現像剤を穂立たせる、所謂磁気ブラシ現像方式で現像される。また、この場合、感光体と現像剤担持体との間隙は、０．１５〜７ｍｍ、特に、０．２〜４ｍｍであることが好ましい。
【００５３】
また、非接触系現像方式としては、現像剤担持体上に形成された現像剤層と感光体とが接触しないものであり、この現像方式を構成するために現像剤層は薄層で形成されることが好ましい。この方法は現像剤担持体表面の現像領域で２０〜５００μｍの現像剤層を形成させ、感光体と現像剤担持体との間隙が該現像剤層よりも大きい間隙を有するものである。
【００５４】
非接触現像方式において、薄層形成は磁気の力を使用する磁性ブレードや現像剤担持体表面に現像剤層規制棒を押圧する方式等で形成される。さらに、ウレタンブレードや燐青銅板等を現像剤担持体表面に接触させ現像剤層を規制する方法もある。押圧規制部材の押圧力としては１〜１５ｇｆ／ｍｍが好適である。押圧力が小さい場合には規制力が不足するために搬送が不安定になりやすく、一方、押圧力が大きい場合には現像剤に対するストレスが大きくなるため、現像剤の耐久性が低下しやすい。好ましい範囲は３〜１０ｇｆ／ｍｍである。さらに、非接触現像方式においては、現像に際して現像バイアス電圧を付加するのが好ましいが、この場合、直流成分のみ付与する方式でも良いし、交流バイアスを重畳印加する方式のいずれでも良い。
【００５５】
現像剤担持体の大きさとしては直径が１０〜４０ｍｍの内部に磁石を保持したものが好適である。直径が小さすぎる場合には現像剤の混合が不足し、トナーに対して充分な帯電付与を行うに充分な混合を確保することが困難となり、直径が大きすぎる場合には現像剤に対する遠心力が大きくなり、トナーの飛散の問題を発生しやすい。
【００５６】
以下、非接触現像方式の一例を図１を用いて説明する。
【００５７】
図１は、本発明の画像形成方法に好適に使用できる非接触現像方式の現像部の概略図であり、１は感光体、２は現像剤担持体、３は本発明のトナーを含有する二成分現像剤、４は現像剤層規制部材、５は現像領域、６は現像剤層、７は交番電界を形成するための電源である。
【００５８】
本発明のトナーを含有する二成分現像剤はその内部に磁石２Ｂを有する現像剤担持体２上に磁気力により担持され、現像スリーブ２Ａの移動により現像領域５に搬送される。この搬送に際して、現像剤層６は現像剤層規制部材４により、現像領域５に於いて、感光体１と接触することがないようにその厚さの層に規制される。
【００５９】
現像領域５の最小間隙（Ｄｓｄ）はその領域に搬送される現像剤層６の厚さ（好ましくは２０〜５００μｍ）より大きく、例えば１００〜１０００μｍ程度である。交番電界を形成するための電源７は、周波数１〜１０ｋＨｚ、電圧１〜３ｋＶｐ−ｐの交流が好ましい。電源７には直流を交流に直列に加えた構成であってもよい。直流電圧を付加する場合は３００〜８００Ｖが好ましい。
【００６０】
本発明のトナーをカラー画像形成方式へ適用する場合、感光体上へ単色の画像を形成しつつ逐次画像支持体へ転写する方式（これを逐次転写方式とし、図２に示す。）、あるいは感光体上に複数回単色画像を現像しカラー画像を形成した後に一括して画像支持体へ転写する方式（これを一括転写方式とし、図３に示す。）等の方式があげられる。
【００６１】
尚、本発明の明細書中においては、潜像が形成されトナー現像されるのは、感光体上として説明しているが、特に感光体に限定されることなく、上記機能を持つ静電荷潜像支持体上であればよい。
【００６２】
図２、３における画像形成方式について以下に詳述する。
【００６３】
本発明に於いて使用される現像剤担持体としては、図１、２、３に示すごとく、担持体内部に磁石２Ｂを内蔵した現像器が用いられ、現像剤担持体表面を構成するスリーブ２Ａとしてはアルミニウムや表面を酸化処理したアルミニウムあるいはステンレス製のものが用いられる。
【００６４】
以下、図２に示した逐次転写方式の一例について説明する。
【００６５】
１１は帯電電極である帯電器、１２はイエロー、マゼンタ、シアン、黒のトナーを各々に装填する現像器からなる現像ユニットで、４色のトナーに対応する４つの器に分かれている。これら現像器の基本構成は、図１に示した現像部の概略図と同じである。１４は感光体ドラム、１３はクリーニングユニット、１５は感光体ドラム上に形成された単色カラートナー像を一時的に保持し、さらにその上に次の単色トナー像を保持し、最終的に所望の多色カラー画像を形成する転写ドラム、１６は転写ドラム上のトナー画像が転写される転写材を搬送する搬送ユニット、１７は転写ドラム１５の内部に設けられ、内部からコロナ放電し、転写材を該ドラムに静電吸着する吸着電極、１８は感光体ドラム１４上に形成されたトナー像を逐次転写ドラムに転写させる転写電極、１９は転写ドラム１５上に静電吸着した転写材を剥離するための剥離電極、２０は転写材剥離後、転写ドラムに残留する電荷を除去する除去電極である。
【００６６】
感光体ドラム１４上に帯電器１１により、一様に電荷を形成し、その後、像様露光（手段図示せず）し、静電潜像を形成する。この静電潜像は、現像ユニット１２の一色のトナー（例えば黒トナー）を保有する現像器により現像され、一色のトナー画像が感光体ドラム１４上に形成される。一方搬送ユニット１６により転写ドラム１５上に搬送された転写材料は吸着電極１７により転写ドラム上に静電吸着され、転写部に搬送される。
【００６７】
この搬送された転写材へは、転写部において、感光体ドラム１４上に形成されている上記トナー像を転写する。この転写像を転写後の感光体ドラム１４上には、トナーが残留しており、この残留トナーはクリーニングユニット１３によりクリーニングされ、次のプロセスに使用される。多色画像を形成する場合、同様なプロセスに従い他の色のトナー画像が現像により形成され、逐一転写ドラム１５に転写される。最終的には、所望のトナー画像が転写ドラム１５上に吸着されている転写材上に形成される。所望のトナー画像がを形成した転写材は、剥離電極１９により剥離され、定着部へ搬送され、最終の固定された多色トナー画像が得られる。一方、転写ドラム１５は残留している電荷を除電極２０により除去され、次のプロセスに使用される。
【００６８】
次に図３を使用し、一括転写方式について説明する。
【００６９】
装置の各部は図２の例と同じであるので省略する。但し、２１は搬送された転写材を搬送しながら、トナー像を転写する搬送部である。感光体ドラム１４上に帯電電極により一様に電荷を形成し、その後潜像形成手段（手段図示せず）により静電潜像を形成する。この静電潜像は、現像ユニット１２の一色のトナー（例えば黒トナー）を保有する現像器により現像され、一色のトナー画像が感光体ドラム上に形成される。本図示例においては、このトナー像は転写されることなく、そのままトナー画像を有している感光体ドラム上に再度、帯電電極１１により一様に電荷を形成し、さらに静電潜像を形成し、上記とは異なる色のトナーを有する現像器により現像され、他の色のトナー像が先のトナー像上に重ね合わせて形成される。この間クリーニングユニット１３、転写電極１８、搬送部２１は作動せず、かつ感光体ドラム１４上のトナー像を乱すことがない様に感光体ドラム１４から退避させられている。
【００７０】
所望の画像形成が終了し、多色トナー画像が形成された後、感光体ドラム上のトナー画像は、搬送ユニット１６により搬送された転写材に、搬送部２１により搬送されながら、転写電極１８によりトナー画像は転写される。転写されたトナー画像を担持して転写材は定着部へ搬送され、固定化され、転写材上に最終多色トナー画像が形成される。トナー像を転写した後の感光体ドラム１４にはトナーが残留するのでクリーニングユニット１３によりクリーニングされ、次のプロセスに使用される。
【００７１】
上述した各種方式で感光体上に形成されたトナー像は、転写工程により紙等の転写材に転写される。転写方式としては特に限定されず、いわゆるコロナ転写方式やローラー転写方式等種々の方式を採用することができる。
【００７２】
本発明のトナーは転写効率が高く、かつ感光体上に残留するトナーが少ないので例えばブレードクリーニング方式に用いた場合ブレードの感光体への押接力を軽減する等ができ、感光体の長寿命化にも寄与することができる等の効果も有する。
【００７３】
トナー像を転写材に転写した後、感光体上に残留したトナーはクリーニングにより除去され、感光体は次のプロセスに繰り返し使用される。
【００７４】
本発明に於いてクリーニングする機構に関しては特に限定されず、ブレードクリーニング方式、磁気ブラシクリーニング方式、ファーブラシクリーニング方式などの公知のクリーニング機構を任意に使用することができる。これらクリーニング機構として、好適なものは上述した理由から、いわゆるクリーニングブレードを用いたブレードクリーニング方式である。
【００７５】
【実施例】
以下、実施例を挙げて本発明を詳細に説明するが、本発明の態様はこれに限定されない。
【００７６】
（着色粒子）
着色粒子製造例１
カーボンブラック（リーガル３３０Ｒ：キャボット社製）をアルミニウムカップリング剤（プレンアクトＡＬ−Ｍ：味の素社製）で処理したものを１０．６７ｇをドデシル硫酸ナトリウム４．９２ｇを１２０ｍｌの純水に溶解した水溶液に添加し、各判しつつ超音波を照射しカーボンブラックの水分散液を調整した。又低分子量ポリプロピレン（数平均分子量＝３２００）を熱を加えながら水中に界面活性剤を用い乳化させた固形分濃度＝２０重量％の乳化分散液を調製した。上記カーボンブラックの分散液に低分子量ポリプロピレン乳化分散液４３ｇを混合し、スチレンモノマー９０．０ｇ、ジビニルベンゼン（有効成分＝５５％）１０．９ｇ、ｎ−ブチルアクリレート１８．０ｇ、メタクリル酸モノマー６．０ｇ、tert-ドデシルメルカプタン３．３ｇ、脱気済み純水８５０ｍｌを添加した後、窒素気流下撹拌を行いつつ、７０℃まで昇温した。次いで、過硫酸カリウム６．１ｇを溶解した純水２００ｍｌを加え７０℃、６時間重合を行った後、室温まで冷却した。得られたカーボンブラック含有着色粒子分散液を『分散液１』とした。尚、この分散液の粒子径は、光散乱電気泳動粒径測定装置ＥＬＳ−８００（大塚電子工業（株））を用い測定し、テトラヒドロフラン不溶分は上記の重合から着色剤及び低分子量ポリプロピレンを除き重合したものを用い測定した。
【００７７】
加圧反応器にこの『分散液１』６００ｍｌに対し２．７ｍｏｌ／ｌの塩化カリウム水溶液を１６０ｍｌ，更にイソプロピルアルコール９４ｍｌ，ポリオキシエチレンオクチルフェニルエーテル（エチレンオキサイド平均重合度は１０である）５．４ｇを純水４０ｍｌに溶解した水溶液を添加した。
【００７８】
更に５ｋｇ／ｃｍ²の圧力をかけた後、内温を１３０℃まで昇温し６時間反応を行った後、室温まで冷却し、圧力を解除し反応液を濾過、水洗を行い乾燥し本発明の着色粒子を得た。このものを『着色粒子１』とした。
【００７９】
着色粒子製造例２
上記着色粒子製造例１において添加するモノマーの量をスチレンモノマー９３．０ｇ、ジビニルベンゼン（有効成分＝５５％）５．４５ｇ、ｎ−ブチルアクリレート１８．０ｇ、メタクリル酸モノマー６．０ｇに代えた他は同ようにして本発明の着色粒子を得た。ここで得られた分散液を『分散液２』とし、着色粒子を『着色粒子２』とした。
【００８０】
着色粒子製造例３
上記着色粒子製造例１において添加するモノマーの量をスチレンモノマー９４．８ｇ、ジビニルベンゼン（有効成分＝５５％）２．１８ｇ、ｎ−ブチルアクリレート１８．０ｇ、メタクリル酸モノマー６．０ｇに代えた他は同ようにして本発明の着色粒子を得た。ここで得られた分散液を『分散液３』とし、着色粒子を『着色粒子３』とした。
【００８１】
着色粒子製造例４
上記着色粒子製造例１において添加するモノマーの量をスチレンモノマー９１．０８ｇ、ジビニルベンゼン（有効成分＝５５％）０．２２ｇ、ｎ−ブチルアクリレート１８．０ｇ、メタクリル酸モノマー６．０ｇに代えた他は同ようにして本発明の着色粒子を得た。ここで得られた分散液を『分散液４』とし、着色粒子を『着色粒子４』とした。
【００８２】
着色粒子製造例５
上記着色粒子製造例１において添加するモノマーの量をスチレンモノマー９５．９８ｇ、ジビニルベンゼン（有効成分＝５５％）０．０２ｇ、ｎ−ブチルアクリレート１８．０ｇ、メタクリル酸モノマー６．０ｇに代えた他は同ようにして本発明の着色粒子を得た。ここで得られた分散液を『分散液５』とし、着色粒子を『着色粒子５』とした。
【００８３】
着色粒子製造例６
上記着色粒子製造例３において表面処理されたカーボンブラックの代わりにＣ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １７を用いた他は同様にして本発明の着色粒子を得た。ここで得られた分散液を『分散液６』とし、着色粒子を『着色粒子６』とした。
【００８４】
着色粒子製造例７
上記着色粒子製造例３において表面処理されたカーボンブラックの代わりにＣ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ １２２を用いた他は同様にして本発明の着色粒子を得た。ここで得られた分散液を『分散液７』とし、着色粒子を『着色粒子７』とした。
【００８５】
着色粒子製造例８
上記着色粒子製造例３において表面処理されたカーボンブラックの代わりにＣ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５：３を用いた他は同様にして本発明の着色粒子を得た。ここで得られた分散液を『分散液８』とし、着色粒子を『着色粒子８』とした。
【００８６】
比較用着色粒子製造例１
上記着色粒子製造例１において添加するモノマーの量をスチレンモノマー８９．７８ｇ、ジビニルベンゼン（有効成分＝５５％）１３．３２ｇ、ｎ−ブチルアクリレート１８．４ｇ、メタクリル酸モノマー６．１ｇに代えた他は同ようにして本発明の着色粒子を得た。ここで得られた着色粒子を『比較用着色粒子１』とした。
【００８７】
比較用着色粒子製造例２
上記着色粒子製造例１において添加するモノマーの量をスチレンモノマー９８．１ｇ、ｎ−ブチルアクリレート１８．４ｇ、メタクリル酸モノマー６．１ｇに代えた他は同ようにして本発明の着色粒子を得た。ここで得られた着色粒子を『比較用着色粒子２』とした。
【００８８】
得られた着色粒子、比較用着色粒子の分散液１〜８、比較用分散液１〜２の平均粒径とＴＨＦ不溶分を下記表１に示した。
【００８９】
【表１】

【００９０】
着色粒子１〜８及び比較用着色粒子１〜２については、体積平均粒径及び粒度分布をレーザー回折粒度測定装置ＳＡＬＤ−１１００：島津製作所製を用い測定し、ＢＥＴ比表面積はフローソーブ２３００：島津製作所製を用い窒素吸着法の１点法を用い測定した。更に粒子形状は高速画像解析装置ＳＰＩＣＣＡ：日本アビオニクス社製を用い、トナー粒子の周囲長／粒子の円相当周で定義される形状係数を用いて表２に表した。
【００９１】
【表２】

【００９２】
（トナーの作製）
着色粒子１〜着色粒子８及び比較用着色粒子１〜比較用着色粒子２に対し疎水性シリカ（一時粒子径＝１２ｎｍ）を１重量％添加しトナーを得た。これらを『トナー１』〜『トナー８』及び『比較用トナー１』〜『比較用トナー２』とした。
【００９３】
（現像剤の作製）
更に上記トナーをスチレン−アクリル酸エステル樹脂で被覆した体積平均粒径が５０μｍのフェライトキャリアと混合し、上記『トナー１』〜『トナー８』及び『比較用トナー１』〜『比較用トナー２』に対応する『現像剤１』〜『現像剤８』及び『比較用現像剤１』〜『比較用現像剤２』とした。
【００９４】
（評価方法）
現像剤の評価は複写機Ｋｏｎｉｃａ Ｕ−ＢＩＸ３１３５（コニカ（株）製）を使用し行った。
【００９５】
定着性試験
上記現像剤及び比較用現像剤を用い、絶対反射濃度１．０になるよう現像を行い、定着後定着性試験として擦り試験を行い反射濃度の差から定着率を算出した。
【００９６】
画像評価
テストチャートを各現像剤を用い複写し、その画像の官能評価を行った。
【００９７】
評価は、画像の質感、重厚さに対し、
◎；非常に良好、
○；良好、
△；劣悪、
×；非常に劣悪、
の４段階で評価した。
【００９８】
結果を以下に示す。
【００９９】
【表３】

【０１００】
本発明内の現像剤１〜８は、定着性試験、画像評価の性能共、十分実用上問題ない水準なのに対し、本発明外の比較用現像剤１〜２は両特性とも十分な特性が得られないことがわかる。
【０１０１】
尚、比較用現像剤２では、オフセットが発生していた。
【０１０２】
【発明の効果】
本発明により、改良された定着性及び画像の光沢を抑えた重厚な画像を形成する方法を提供することが出来る。
【図面の簡単な説明】
【図１】非接触現像方式の一例を示す概略図。
【図２】逐次転写方式の一例を示す概略図。
【図３】一括転写方式の一例を示す概略図。
【符号の説明】
１ 感光体
２ 現像剤担持体
２Ａ 現像スリーブ
２Ｂ 磁石
３ 二成分現像剤（本発明のトナー含有）
４ 現像剤層規制部材
５ 現像領域
６ 現像剤層
７ 交番電界を形成するための電源
１１ 帯電器
１２ 現像ユニット
１３ クリーニングユニット
１４ 感光体ドラム
１５ 転写ドラム
１６ 搬送ユニット
１７ 吸着電極
１８ 転写電極
１９ 剥離電極
２０ 除電電極
２１ 搬送部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic charge image developing toner used in an image forming apparatus used for a copying machine, a printer, and the like, and an image forming method using the toner.
[0002]
[Prior art]
In recent years, electrostatic image development represented by an electrophotographic development system has been used in various fields. For example, it is used not only in copying machines but also in the fields of printers, which are output terminals of computers, color copying machines, color printers, and the like, and the demand for image quality is increasing as usage in these fields progresses.
[0003]
For this reason, the degree of demand for the toner itself has increased, and in addition to the image quality performance that has been regarded as a problem, such as resolving power, various demands have been made, such as fixing fastness and improved texture of the finished image.
[0004]
However, in these respects, there are still many unexamined parts, and the superiority or inferiority may vary depending on the preference and application of each individual, and the present situation is not established technically.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for forming a thick image with improved fixability and reduced gloss of the image.
[0006]
[Means for Solving the Problems]
The object of the present invention is achieved by adopting one of the following configurations.
[0007]
(1)After polymerization reactionAggregate and fuse polymer primary particlesObtainedIn the electrostatic image developing toner comprising colored particles, the degree of crosslinking of the primary particles is 0.01% to 50% by weight in terms of tetrahydrofuran insolubles.The shape factor of the colored particles is 1.01 to 1.5An electrostatic charge image developing toner characterized by
[0008]
(2)SaidThe BET specific surface area of the colored particles is 5m²The toner for developing an electrostatic charge image according to (1), wherein the toner is / g or more.
[0009]
(3)From the colored particles obtained by agglomerating and fusing the polymer primary particles after the polymerization reaction at 90 ° C. to 180 ° C.The toner for developing an electrostatic charge image according to (1) or (2).
[0010]
(4)The electrostatic latent image on the photosensitive member is developed using the electrostatic image developing toner according to any one of (1) to (3).An image forming method characterized by that.
[0011]
(5)The toner image formed on the electrostatic latent image support is transferred onto a transfer material using the electrostatic image developing toner according to any one of (1) to (3).It is characterized byPaintingImage forming method.
[0012]
(6)(5) characterized in that after the toner image is transferred onto a transfer material, toner remaining on the electrostatic latent image support is cleaned.The image forming method described.
[0013]
(7) In an image forming method for transferring a toner image formed on an image support onto a transfer material, electrostatic image development comprising colored particles formed by agglomerating and fusing polymer primary particles with the toner. An image forming method comprising: a toner for developing an electrostatic image, wherein the primary particles have a crosslinking degree of 0.01% by weight to 50% by weight in terms of tetrahydrofuran insolubles.
[0014]
(8) In an image forming method for transferring a toner image formed on an image support onto a transfer material, electrostatic image development comprising colored particles formed by agglomerating and fusing polymer primary particles with the toner. Toner, wherein the colored particles have a BET specific surface area of 5 m.²(6) The image forming method as described in (7) above, wherein the toner is an electrostatic charge image developing toner of at least / g.
[0015]
(9) In an image forming method for transferring a toner image formed on an image support onto a transfer material, electrostatic image development comprising colored particles formed by agglomerating and fusing polymer primary particles with the toner. (7) or (8), wherein the colored particles have a shape factor of 1.01 to 1.5.
[0016]
(10) In an image forming method in which a toner image formed on an image support is transferred onto a transfer material and then the toner remaining on the support is cleaned, the toner aggregates polymer primary particles, An electrostatic charge image developing toner comprising fused colored particles, wherein the colored particles have a crosslinking degree of 0.01% to 50% by weight in terms of tetrahydrofuran insolubles. An image forming method characterized by the above.
[0017]
(11) In an image forming method in which a toner image formed on an image support is transferred onto a transfer material and then the toner remaining on the support is cleaned, the toner aggregates polymer primary particles, A toner for developing an electrostatic image comprising colored particles formed by fusing, wherein the colored particles have a BET specific surface area of 5 m.²(10) The image forming method as described in (10) above, wherein the toner is an electrostatic charge image developing toner of at least / g.
[0018]
(12) In an image forming method in which a toner image formed on an image support is transferred onto a transfer material and then the toner remaining on the support is cleaned, the toner aggregates polymer primary particles, An electrostatic charge image developing toner comprising fused colored particles, wherein the colored particle has a shape factor of 1.01 to 1.5 (10). ) Or (11).
[0019]
Toner production method
The toner of the present invention is produced by associating and fusing a plurality of polymer primary particles having a particle size equal to or smaller than a desired toner particle size. The polymer particles are produced using a known polymerization method. For example, an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a soap-free polymerization method, a seed polymerization method, a molecular diffusion method, a two-stage swelling method, and the like are used. Preferably, a submicron polymer particle dispersion is obtained using an emulsion polymerization method, and a plurality of the dispersed particles are associated and fused.
[0020]
In order to make toner further, an aggregating agent is added to the polymer primary particle dispersion, an organic solvent that is infinitely soluble in water is added, and the mixture is heated at a temperature equal to or higher than the glass transition temperature of the polymer primary particles. It can be manufactured by fusing. The internal additive essential as a toner and the internal additive that is added as desired include a colorant, a fixability improving agent, a charge control agent, and the like. These may be used at the time of polymerization or association of the polymer primary particle dispersion. Sometimes added in the form of an aqueous dispersion. In this case, it is particularly preferably added during the polymerization. As a result, the internal additive is uniformly combined with the polymer particles, and the internal additive in the toner is also uniformly present in the toner particles, so that stable toner characteristics can be obtained.
[0021]
Since the primary particles used in the present invention are crosslinked, it is generally difficult to show a glass transition temperature. For this reason, heat fusion is difficult to proceed. For this reason, it is necessary to raise the reaction temperature in order to sufficiently adjust the toner particle shape. Generally, it is performed in the range of 90 ° C to 180 ° C. Since the boiling point of the reaction solution is exceeded at this temperature, it is preferable to use a pressurized reactor.
[0022]
Copolymerization ratio of crosslinking monomer
The crosslinking monomer varies in degree of crosslinking depending on the reactivity of the monomer itself, polymerization conditions, etc., but in order to make the insoluble content of tetrahydrofuran (THF) 0.01 wt% to 50 wt%, the copolymerization ratio is 0.01 The range of wt% to 5 wt% is preferred. When the THF-insoluble content is less than this range, neither the fixability nor the non-glossiness of the image is significantly affected. On the other hand, if this range is exceeded, the fixability becomes extremely poor.
[0023]
Here, insoluble content of tetrahydrofuran (THF) was measured by adding the polymer to a concentration of 1% by weight with respect to THF at 25 ° C., and stirring for 24 hours, followed by filtration and residual solid content. Calculated from weight.
[0024]
Cross-linking monomer
As the crosslinking monomer, an ethylenic polyfunctional monomer having radical polymerizability is used. Examples include divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, and the like. Monomers having a reactive group in the pendant group, such as glycidyl methacrylate, methylol acrylamide, acrolein, etc. can also be used. A radical polymerizable ethylenically unsaturated polyfunctional monomer is preferable, and divinylbenzene is more preferable.
[0025]
One desirable aspect of the toner of the present invention is that the colored particles have a BET specific surface area of 5 m.²The specific surface area of the BET value is measured by a one-point method of nitrogen adsorption method, specifically, a flowsorb 2300 measuring device manufactured by Shimadzu Corporation.
[0026]
  The toner of the present inventionThe mode ofThe colored particles have a shape factor of 1.01 to 1.5. This shape factor is defined as the perimeter of the particle / equivalent circle circumference of the particle, and specifically is defined by the following equation.
[0027]
[Expression 1]

[0028]
In the above formula, L is the perimeter of the particle (μm), A is the projected area of the particle (μm)²).
[0029]
L and A in the above formula project a particle and measure L and A when the particle is projected. Specifically, L and A are projected, and each of L and A is an average value of n = 100 to 1000. Is measured with an image analyzer.
[0030]
A toner that better achieves the object of the present invention is a toner made of colored particles having the above-mentioned characteristics, and has a relatively spherical shape and a large surface area, and has a specific shape and a large surface area. Therefore, it is presumed that the above-described objects of the present invention can be achieved.
[0031]
The materials and modes used in carrying out the present invention will be further described.
[0032]
Specific examples of the monomer (monomer) constituting the toner resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4- Dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pt-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, p- styrene or styrene derivatives such as n-decylstyrene, pn-dodecylstyrene, aromatic vinyl compounds such as vinylnaphthalene; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, T-butyl methacrylate, n-octyl methacrylate, methacryl Methacrylate derivatives such as 2-ethylhexyl, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate Α-methylene aliphatic monocarboxylic acids such as t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, etc. Esters; Olefins such as ethylene, propylene and isobutylene; Halogen-based vinyls such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride and vinylidene fluoride; Vinyl propionate Vinyl esters such as vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone; N-vinyl carbazole and N-vinyl indole N-vinyl compounds such as N-vinylpyrrolidone, and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. Among these monomers, aromatic vinyl compounds and α-methylene aliphatic monocarboxylic acid esters are preferred.
[0033]
These vinyl monomers can be used alone or in combination to obtain a copolymer for use in the toner. Moreover, what has an ionic dissociation group as a monomer which comprises resin can be used in combination. For example, having a substituent such as a carboxy group, a sulfo group, a phospho group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, Maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate Etc.
[0034]
In the present invention, the resin obtained as described above is obtained in a fine particle state, particularly when obtained by an emulsion polymerization method. Therefore, a flocculant is used and a solvent that is infinitely soluble in water is added to obtain the resin. Heat treatment above the glass transition point of the obtained resin makes it possible to obtain particles (toner) having a desired particle diameter.
[0035]
In the production of the toner of the present invention, the flocculant used is not particularly limited, but those selected from metal salts are preferably used. Specifically, as a monovalent metal, for example, an alkali metal salt such as sodium, potassium or lithium, as a divalent metal, for example, an alkaline earth metal salt such as calcium or magnesium, or a divalent metal such as manganese or copper. Salts, trivalent metal salts such as iron and aluminum, etc., and specific salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, inexpensive zinc, copper sulfate, magnesium sulfate, manganese sulfate, etc. Can be mentioned. These may be used in combination.
[0036]
These flocculants are used by adding more than the critical flocculent concentration. The critical flocculation concentration is an index relating to the stability of the aqueous dispersion, and indicates a concentration at which flocculation occurs when a flocculant is added. This critical aggregation concentration varies greatly depending on the emulsified components and the dispersant itself. For example, it is described in Seizo Okamura et al., “Polymer Chemistry Vol. 17, p601 (1960) edited by Japan Society of Polymer Science”, and the like, and a detailed critical aggregation concentration can be obtained. As another method, a desired salt is added to the target particle dispersion at different concentrations, the ζ (zeta) potential of the dispersion is measured, and the salt concentration at which this value changes is obtained as the critical aggregation concentration. You can also.
[0037]
The addition amount of the flocculant used in the present invention may be not less than the critical aggregation concentration, but is preferably 1.2 times or more, more preferably 1.5 times or more the critical aggregation concentration.
[0038]
The solvent that is infinitely soluble in the water used is a colored polymer dispersion, that is, a solvent that is infinitely soluble in an aqueous dispersion, and this solvent does not dissolve the resin formed in the present invention. The one is selected. Specific examples include alcohols such as methanol, ethanol, propanol, isopropanol, t-butanol, methoxyethanol, and butoxyethanol, nitriles such as acetonitrile, and ethers such as dioxane. In particular, ethanol, propanol, and isopropanol are preferable.
[0039]
The addition amount of the infinitely soluble solvent is preferably 1 to 300% by volume with respect to the polymer-containing dispersion added with the flocculant.
[0040]
Various methods can be used as the polymerization method for forming the resin used in the toner of the present invention. The particularly preferable method is the emulsion polymerization method described above.
[0041]
In the toner of the present invention, various colorants and property improvers such as fixability improvers can be used. As the colorant that can be used, carbon black, a magnetic substance, a dye, a pigment, and the like can be arbitrarily used. As the carbon black, channel black, furnace black, acetylene black, thermal black / lamp black, and the like are used. Magnetic materials include ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but exhibit ferromagnetism by heat treatment, For example, a kind of alloy called Heusler alloy such as manganese-copper-aluminum, manganese-copper-tin, chromium dioxide, or the like can be used. As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 etc. can be used, and a mixture thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment yellow 14, 17, 93, 94, 138, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 60, etc. can be used, and a mixture thereof can also be used. These colorants preferably have a number average primary particle size of about 10 to 200 nm dispersed in the toner.
[0042]
As a method for adding the colorant, when the toner of the present invention is prepared by an emulsion polymerization method, the polymer itself is prepared by an emulsion polymerization method, and then added at the stage of aggregation by adding an aggregating agent, For example, a method of adding a colorant at the stage of polymerizing the monomer can be used. In addition, when adding a coloring agent in the stage which adjusts a polymer, it is preferable to use it, treating the surface with a coupling agent etc. so that radical polymerization property may not be inhibited.
[0043]
Furthermore, low molecular weight polypropylene (number average molecular weight = 1,500 to 9,000), low molecular weight polyethylene or the like as a fixing property improving agent may be added. An azo metal complex, a quaternary ammonium salt, or the like may be used as a charge control agent. These property improvers are usually added to the toner in the same manner as the colorants.
[0044]
Further, from the viewpoint of imparting fluidity, it may be added to colored particles obtained by polymerizing inorganic fine particles and organic fine particles. In this case, the use of inorganic fine particles is preferable, the use of inorganic oxide particles such as silica, titania, and alumina is preferable, and these inorganic fine particles are hydrophobized with a silane coupling agent, a titanium coupling agent, or the like. Is preferred.
[0045]
The toner of the present invention can be produced by associating a plurality of the aforementioned polymers themselves. In this case, the metal salt as a flocculant is critically stirred with stirring the polymer particle dispersion. It can be obtained by adding an amount equal to or higher than the agglomeration concentration, adding the above-mentioned solvent that is infinitely soluble in water, and further heat-treating the glass transition temperature or higher.
[0046]
The toner of the present invention has a BET specific surface area of 5 m.²/ G or more, 150 m from a technical point of view²/ G or less, preferably 100 m²/ G or less, particularly preferably 5 to 50 m²/ G.
[0047]
The colored particles of the present invention preferably have a toner having a shape factor of 1.01 to 1.5, but more preferably 1.05 to 1.3.
[0048]
The method for producing the toner of the present invention is not particularly limited as described above, but is preferably described in Japanese Patent Application Laid-Open Nos. 5-265252, 6-329947, and Japanese Patent Application No. 6-223953. The method is used. That is, a method of associating a plurality of fine particles composed of a resin, a colorant and the like, particularly a method of treating these in water with an aggregating agent having a concentration equal to or higher than the critical aggregating concentration and an organic solvent infinitely soluble in water in use. Furthermore, the toner having the BET specific surface area and the shape factor of the present invention can be formed by heat-sealing at or above the glass transition temperature of the formed polymer itself.
[0049]
The particle size of the toner itself of the present invention is arbitrary, but those having a small particle size are likely to exhibit the effects of the present invention and exhibit a large improvement effect, and those having a volume average particle size of 2 to 10 μm are preferable. In particular, those having 3 to 9 μm are preferable. This particle size can be controlled by the concentration of the flocculant, the amount of organic solvent added, and the composition of the polymer itself.
[0050]
The toner of the present invention may be used, for example, as a one-component magnetic toner containing a magnetic material, used as a two-component developer mixed with a so-called carrier, or a non-magnetic toner alone. Any of them can be suitably used, but in the present invention, it is particularly preferred to use as a two-component developer used by mixing with a carrier.
[0051]
As the carrier constituting the two-component developer, either an uncoated carrier composed only of magnetic material particles such as iron or ferrite, or a resin-coated carrier whose magnetic material particle surface is coated with a resin or the like may be used. The average particle size of the carrier is preferably 30 to 150 μm in terms of volume average particle size. The resin for coating is not particularly limited, and examples thereof include styrene-acrylic acid ester resins and silicone resins.
[0052]
The developing method in which the toner of the present invention can be used is not particularly limited, and can be suitably used for a contact developing method or a non-contact developing method. In the contact type development, the layer thickness of the developer having the toner of the present invention is 0.1 to 8 mm, preferably 0.4 to 5 mm in the development region, and the developer is sprinkled in the development region. It is developed with a magnetic brush development system. In this case, the gap between the photosensitive member and the developer carrying member is preferably 0.15 to 7 mm, particularly preferably 0.2 to 4 mm.
[0053]
Further, as a non-contact type development method, the developer layer formed on the developer carrying member and the photoreceptor are not in contact with each other, and the developer layer is formed as a thin layer in order to constitute this development method. It is preferable. In this method, a developer layer having a thickness of 20 to 500 μm is formed in the developing region on the surface of the developer carrying member, and the gap between the photosensitive member and the developer carrying member is larger than the developer layer.
[0054]
In the non-contact development method, the thin layer is formed by a magnetic blade using magnetic force, a method of pressing a developer layer regulating rod on the surface of the developer carrying member, or the like. Further, there is a method of regulating the developer layer by bringing a urethane blade, a phosphor bronze plate or the like into contact with the surface of the developer carrying member. The pressing force of the pressing restricting member is preferably 1 to 15 gf / mm. When the pressing force is small, the regulation force is insufficient, and thus the conveyance is likely to be unstable. On the other hand, when the pressing force is large, the stress on the developer is increased, and the durability of the developer is likely to be lowered. A preferred range is 3 to 10 gf / mm. Further, in the non-contact development method, it is preferable to apply a development bias voltage at the time of development, but in this case, either a method of applying only a DC component or a method of applying an AC bias superimposed may be used.
[0055]
The developer carrying member preferably has a magnet with a diameter of 10 to 40 mm. When the diameter is too small, mixing of the developer is insufficient, and it becomes difficult to ensure sufficient mixing for imparting sufficient charge to the toner. When the diameter is too large, centrifugal force on the developer is insufficient. It becomes large and is likely to cause a problem of toner scattering.
[0056]
Hereinafter, an example of the non-contact development method will be described with reference to FIG.
[0057]
FIG. 1 is a schematic view of a developing portion of a non-contact developing system that can be suitably used in the image forming method of the present invention, wherein 1 is a photoreceptor, 2 is a developer carrier, and 3 is a toner containing the toner of the present invention. Component developer, 4 is a developer layer regulating member, 5 is a development region, 6 is a developer layer, and 7 is a power source for forming an alternating electric field.
[0058]
The two-component developer containing the toner of the present invention is carried by a magnetic force on the developer carrying member 2 having a magnet 2B therein, and is conveyed to the developing region 5 by the movement of the developing sleeve 2A. During this transport, the developer layer 6 is regulated by the developer layer regulating member 4 to a layer having a thickness so as not to come into contact with the photoreceptor 1 in the development region 5.
[0059]
The minimum gap (Dsd) of the development region 5 is larger than the thickness (preferably 20 to 500 μm) of the developer layer 6 conveyed to that region, for example, about 100 to 1000 μm. The power source 7 for forming the alternating electric field is preferably an alternating current having a frequency of 1 to 10 kHz and a voltage of 1 to 3 kVp-p. The power source 7 may have a configuration in which direct current is added in series with alternating current. In the case of applying a DC voltage, 300 to 800 V is preferable.
[0060]
When the toner of the present invention is applied to a color image forming method, a method of transferring a single color image onto a photoconductor while sequentially transferring it to an image support (this is a sequential transfer method, as shown in FIG. 2), or photosensitive. Examples thereof include a system in which a single color image is developed a plurality of times on a body to form a color image and then transferred to an image support in a lump (this is referred to as a batch transfer system and shown in FIG. 3).
[0061]
In the specification of the present invention, the latent image is formed and the toner is developed on the photosensitive member. However, the latent electrostatic latent image having the above function is not limited to the photosensitive member. It may be on the image support.
[0062]
The image forming method in FIGS. 2 and 3 will be described in detail below.
[0063]
As the developer carrier used in the present invention, as shown in FIGS. 1, 2, and 3, a developing device having a magnet 2B built in the carrier is used, and a sleeve 2A constituting the surface of the developer carrier. For example, aluminum, aluminum whose surface is oxidized, or stainless steel is used.
[0064]
Hereinafter, an example of the sequential transfer method shown in FIG. 2 will be described.
[0065]
A charging unit 11 is a charging electrode, and a developing unit 12 is composed of a developing unit loaded with yellow, magenta, cyan, and black toners, and is divided into four units corresponding to four color toners. The basic configuration of these developing units is the same as the schematic diagram of the developing unit shown in FIG. 14 is a photosensitive drum, 13 is a cleaning unit, 15 is temporarily holding a single color toner image formed on the photosensitive drum, and further holding the next single color toner image thereon, and finally a desired color toner image. A transfer drum that forms a multi-color image, 16 is a transport unit that transports a transfer material onto which a toner image on the transfer drum is transferred, and 17 is provided inside the transfer drum 15 and corona discharges from the inside to transfer the transfer material. An attracting electrode that electrostatically attracts to the drum, 18 is a transfer electrode that sequentially transfers the toner image formed on the photosensitive drum 14 to the transfer drum, and 19 is for peeling off the electrostatically attracted transfer material on the transfer drum 15. The peeling electrode 20 is a removal electrode for removing the charge remaining on the transfer drum after the transfer material is peeled off.
[0066]
Charge is uniformly formed on the photosensitive drum 14 by the charger 11, and then imagewise exposure (means not shown) is performed to form an electrostatic latent image. The electrostatic latent image is developed by a developing unit that holds one color toner (for example, black toner) of the developing unit 12, and a one color toner image is formed on the photosensitive drum 14. On the other hand, the transfer material transported onto the transfer drum 15 by the transport unit 16 is electrostatically attracted onto the transfer drum by the suction electrode 17 and transported to the transfer unit.
[0067]
The toner image formed on the photosensitive drum 14 is transferred to the transferred transfer material at the transfer portion. The toner remains on the photosensitive drum 14 after the transfer image is transferred. The residual toner is cleaned by the cleaning unit 13 and used in the next process. When a multicolor image is formed, toner images of other colors are formed by development according to a similar process, and transferred to the transfer drum 15 one by one. Finally, a desired toner image is formed on the transfer material adsorbed on the transfer drum 15. The transfer material on which the desired toner image is formed is peeled off by the peeling electrode 19 and conveyed to the fixing unit, and a final fixed multicolor toner image is obtained. On the other hand, the transfer drum 15 is used for the next process after the remaining charges are removed by the electrode removal electrode 20.
[0068]
Next, the batch transfer method will be described with reference to FIG.
[0069]
Since each part of the apparatus is the same as the example of FIG. Reference numeral 21 denotes a transport unit that transfers the toner image while transporting the transported transfer material. Electric charges are uniformly formed on the photosensitive drum 14 by charging electrodes, and then an electrostatic latent image is formed by latent image forming means (means not shown). This electrostatic latent image is developed by a developing device that holds one color toner (for example, black toner) of the developing unit 12, and a one color toner image is formed on the photosensitive drum. In the illustrated example, the toner image is not transferred, and a charge is uniformly formed on the photosensitive drum having the toner image as it is by the charging electrode 11 to form an electrostatic latent image. Then, it is developed by a developing device having toner of a color different from the above, and a toner image of another color is formed on top of the previous toner image. During this time, the cleaning unit 13, the transfer electrode 18, and the transport unit 21 do not operate and are retracted from the photosensitive drum 14 so as not to disturb the toner image on the photosensitive drum 14.
[0070]
After the desired image formation is completed and a multicolor toner image is formed, the toner image on the photosensitive drum is transferred to the transfer material transferred by the transfer unit 16 by the transfer unit 21 while being transferred by the transfer unit 21. The toner image is transferred. The transferred toner image is carried and the transfer material is conveyed to the fixing unit and fixed, and a final multicolor toner image is formed on the transfer material. Since the toner remains on the photosensitive drum 14 after the toner image is transferred, it is cleaned by the cleaning unit 13 and used in the next process.
[0071]
The toner image formed on the photoreceptor by the various methods described above is transferred to a transfer material such as paper by a transfer process. The transfer method is not particularly limited, and various methods such as a so-called corona transfer method and a roller transfer method can be employed.
[0072]
The toner of the present invention has a high transfer efficiency and a small amount of toner remaining on the photosensitive member. For example, when used in a blade cleaning method, the pressing force of the blade against the photosensitive member can be reduced, and the life of the photosensitive member can be extended. It is also possible to contribute to the above.
[0073]
After the toner image is transferred to the transfer material, the toner remaining on the photoconductor is removed by cleaning, and the photoconductor is repeatedly used in the next process.
[0074]
In the present invention, the cleaning mechanism is not particularly limited, and a known cleaning mechanism such as a blade cleaning system, a magnetic brush cleaning system, and a fur brush cleaning system can be arbitrarily used. A preferable cleaning mechanism is a blade cleaning system using a so-called cleaning blade for the above-described reason.
[0075]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this.
[0076]
(Colored particles)
Colored particle production example 1
Carbon black (Regal 330R: manufactured by Cabot Corporation) treated with an aluminum coupling agent (Plenact AL-M: manufactured by Ajinomoto Co., Inc.) in an aqueous solution obtained by dissolving 10.67 g of sodium dodecyl sulfate 4.92 g in 120 ml of pure water. The mixture was added and irradiated with ultrasonic waves to make a water dispersion of carbon black. Further, an emulsion dispersion having a solid content concentration of 20% by weight was prepared by emulsifying low molecular weight polypropylene (number average molecular weight = 3200) in water using a surfactant. The carbon black dispersion is mixed with 43 g of a low molecular weight polypropylene emulsified dispersion, 90.0 g of styrene monomer, 10.9 g of divinylbenzene (active ingredient = 55%), 18.0 g of n-butyl acrylate, 6. After adding 0 g, 3.3 g of tert-dodecyl mercaptan, and 850 ml of degassed pure water, the temperature was raised to 70 ° C. while stirring under a nitrogen stream. Next, 200 ml of pure water in which 6.1 g of potassium persulfate was dissolved was added, polymerization was performed at 70 ° C. for 6 hours, and then cooled to room temperature. The resulting carbon black-containing colored particle dispersion was designated as “Dispersion 1”. The particle size of this dispersion was measured using a light scattering electrophoretic particle size measuring device ELS-800 (Otsuka Electronics Co., Ltd.). Tetrahydrofuran insolubles were excluded from the above polymerization except for the colorant and low molecular weight polypropylene. It measured using what superposed | polymerized.
[0077]
4. In a pressure reactor, 160 ml of a 2.7 mol / l potassium chloride aqueous solution per 600 ml of the “dispersion 1”, 94 ml of isopropyl alcohol, and polyoxyethylene octyl phenyl ether (the average degree of polymerization of ethylene oxide is 10) An aqueous solution in which 4 g was dissolved in 40 ml of pure water was added.
[0078]
5kg / cm²Then, the internal temperature was raised to 130 ° C. and the reaction was performed for 6 hours, and then cooled to room temperature, the pressure was released, the reaction solution was filtered, washed with water and dried to obtain the colored particles of the present invention. It was. This was designated as “Colored Particle 1”.
[0079]
Colored particle production example 2
The amount of the monomer added in the colored particle production example 1 was changed to 93.0 g of styrene monomer, 5.45 g of divinylbenzene (active ingredient = 55%), 18.0 g of n-butyl acrylate, and 6.0 g of methacrylic acid monomer. In the same manner, colored particles of the present invention were obtained. The dispersion obtained here was designated as “dispersion 2”, and the colored particles were designated as “colored particles 2”.
[0080]
Colored particle production example 3
The amount of the monomer added in the colored particle production example 1 was changed to 94.8 g of styrene monomer, 2.18 g of divinylbenzene (active ingredient = 55%), 18.0 g of n-butyl acrylate, and 6.0 g of methacrylic acid monomer. In the same manner, colored particles of the present invention were obtained. The dispersion thus obtained was designated as “Dispersion 3”, and the colored particles were designated as “Colored particles 3”.
[0081]
Colored particle production example 4
The amount of the monomer added in the colored particle production example 1 was changed to 91.08 g of styrene monomer, 0.22 g of divinylbenzene (active ingredient = 55%), 18.0 g of n-butyl acrylate, and 6.0 g of methacrylic acid monomer. In the same manner, colored particles of the present invention were obtained. The dispersion thus obtained was designated as “Dispersion 4”, and the colored particles were designated as “Colored particles 4”.
[0082]
Colored particle production example 5
The amount of the monomer added in the colored particle production example 1 was changed to 95.98 g of styrene monomer, 0.02 g of divinylbenzene (active ingredient = 55%), 18.0 g of n-butyl acrylate, and 6.0 g of methacrylic acid monomer. In the same manner, colored particles of the present invention were obtained. The obtained dispersion was designated as “Dispersion 5”, and the colored particles were designated as “Colored particles 5”.
[0083]
Colored particle production example 6
In place of the carbon black surface-treated in the above colored particle production example 3, C.I. I. The colored particles of the present invention were obtained in the same manner except that Pigment Yellow 17 was used. The obtained dispersion was designated as “Dispersion 6”, and the colored particles were designated as “Colored particles 6”.
[0084]
Colored particle production example 7
In place of the carbon black surface-treated in the above colored particle production example 3, C.I. I. The colored particles of the present invention were obtained in the same manner except that Pigment Red 122 was used. The resulting dispersion was designated as “Dispersion 7”, and the colored particles were designated “Colored Particles 7”.
[0085]
Colored particle production example 8
In place of the carbon black surface-treated in the above colored particle production example 3, C.I. I. The colored particles of the present invention were obtained in the same manner except that Pigment Blue 15: 3 was used. The obtained dispersion was designated as “dispersion 8”, and the colored particles were designated as “colored particles 8”.
[0086]
Comparative colored particle production example 1
The amount of monomer added in the colored particle production example 1 was changed to 89.78 g of styrene monomer, 13.32 g of divinylbenzene (active ingredient = 55%), 18.4 g of n-butyl acrylate, and 6.1 g of methacrylic acid monomer. In the same manner, colored particles of the present invention were obtained. The colored particles obtained here were designated as “comparative colored particles 1”.
[0087]
Colored particle production example 2 for comparison
The colored particles of the present invention were obtained in the same manner except that the amount of the monomer added in the colored particle production example 1 was changed to 98.1 g of styrene monomer, 18.4 g of n-butyl acrylate, and 6.1 g of methacrylic acid monomer. . The colored particles obtained here were designated as “comparative colored particles 2”.
[0088]
Table 1 below shows the average particle size and THF-insoluble content of the obtained colored particles, comparative colored particle dispersions 1 to 8, and comparative dispersions 1 and 2.
[0089]
[Table 1]

[0090]
For the colored particles 1 to 8 and the comparative colored particles 1 and 2, the volume average particle size and particle size distribution are measured using a laser diffraction particle size analyzer SALD-1100: manufactured by Shimadzu Corporation, and the BET specific surface area is Flowsorb 2300: Shimadzu Corporation. The product was measured using a one-point method of nitrogen adsorption method. Further, the particle shape is shown in Table 2 using a high-speed image analysis apparatus SPICCA: manufactured by Nippon Avionics Co., Ltd., and using a shape factor defined by the perimeter of toner particles / equivalent circle of particles.
[0091]
[Table 2]

[0092]
(Production of toner)
1% by weight of hydrophobic silica (temporary particle size = 12 nm) was added to the colored particles 1 to 8 and the comparative colored particles 1 to 2 for comparison to obtain a toner. These were designated as “toner 1” to “toner 8” and “comparative toner 1” to “comparative toner 2”.
[0093]
(Development of developer)
Further, the above toner is mixed with a ferrite carrier having a volume average particle diameter of 50 μm coated with styrene-acrylic ester resin, and the above “Toner 1” to “Toner 8” and “Comparative toner 1” to “Comparative toner 2” are mixed. "Developer 1" to "Developer 8" and "Comparative developer 1" to "Comparative developer 2" corresponding to the above.
[0094]
(Evaluation methods)
The developer was evaluated using a copying machine Konica U-BIX3135 (manufactured by Konica Corporation).
[0095]
Fixability test
Using the developer and the comparative developer, development was performed so that the absolute reflection density was 1.0, a rubbing test was performed as a fixing property test after fixing, and the fixing rate was calculated from the difference in reflection density.
[0096]
Image evaluation
The test chart was copied using each developer, and the sensory evaluation of the image was performed.
[0097]
Evaluation is based on the texture and heavyness of the image.
◎; very good,
○: Good,
△: Poor,
×: Very bad,
The four grades were evaluated.
[0098]
The results are shown below.
[0099]
[Table 3]

[0100]
Developers 1 to 8 in the present invention are at a level where there are no problems in practical use in terms of both the fixability test and the image evaluation performance, whereas comparative developers 1 and 2 outside the present invention have sufficient characteristics for both. I can't understand.
[0101]
In the comparative developer 2, an offset occurred.
[0102]
【The invention's effect】
According to the present invention, it is possible to provide a method for forming a thick image with improved fixability and reduced gloss of the image.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of a non-contact development method.
FIG. 2 is a schematic diagram illustrating an example of a sequential transfer method.
FIG. 3 is a schematic diagram illustrating an example of a batch transfer method.
[Explanation of symbols]
1 Photoconductor
2 Developer carrier
2A Development sleeve
2B magnet
3 Two-component developer (containing toner of the present invention)
4 Developer layer regulating member
5 Development area
6 Developer layer
7 Power supply for generating an alternating electric field
11 Charger
12 Development unit
13 Cleaning unit
14 Photosensitive drum
15 Transfer drum
16 Transport unit
17 Adsorption electrode
18 Transfer electrode
19 Peeling electrode
20 Static elimination electrode
21 Transport section

Claims (6)

In a toner for developing an electrostatic image comprising colored particles obtained by agglomerating and fusing polymer primary particles after the polymerization reaction, the degree of cross-linking of the primary particles is 0.01% to 50% by weight in terms of tetrahydrofuran insolubles. An electrostatic charge image developing toner , wherein the colored particles have a shape factor of 1.01 to 1.5 . ^2. The electrostatic image developing toner according to claim 1, wherein the colored particles have a BET specific surface area of 5 m ² / g or more. The electrostatic image developing toner according to claim 1, wherein the toner is composed of colored particles obtained by agglomerating and fusing the polymer primary particles after the polymerization reaction at 90 ° C. to 180 ° C. 3. An image forming method comprising developing an electrostatic latent image on a photoreceptor using the electrostatic image developing toner according to claim 1 . Picture according using the toner for electrostatic image development according to any one of claim 1 to 3, you said the toner image formed on the electrostatic latent image bearing member on that you transferred onto the transfer material Image forming method. 6. The image forming method according to claim 5, wherein after the toner image is transferred onto a transfer material, the toner remaining on the electrostatic charge latent image support is cleaned .

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