JP3862412B2 - toner - Google Patents

Description

（式中、ＭＸＬＮＧは粒子の絶対最大長、ＰＥＲＩＭＥは粒子の周囲長、ＡＲＥＡは粒子の投影面積を示す。）
【００４６】
形状係数ＳＦ−１はトナー粒子の丸さの度合を示し、形状係数ＳＦ−２はトナー粒子の凹凸の度合を示している。
【００４７】
トナーの形状係数ＳＦ−１，ＳＦ−２は、それぞれ１００に近い方が転写性に優れるが、トナーの形状係数ＳＦ−１が１１０以下の時あるいはトナーの球状係数ＳＦ−２が１１０以下の時、及びＳＦ−２の値から１００を引いた値ＢとＳＦ−１の値から１００を引いた値Ａとの比Ｂ／Ａの値が１．０を超えるときは、一般にクリーニング不良が発生しやすく、トナーの形状係数ＳＦ−１が１６０を超えると、球形から離れて不定形に近づき、現像器内でトナーが破砕され易く、粒度分布が変動したり、帯電量分布がブロードになりやすく地カブリや反転カブリが生じやすい。また、ＳＦ−２が１４０を超えると、静電潜像担持体（感光体）から転写材への転写時におけるトナー像の転写効率の低下、および文字やライン画像の転写中抜けを招き好ましくない。この際、粉砕法で製造したトナーが好ましく用いられる。
【００４８】
また、Ｂ／Ａは図４において、原点を通る直線の傾きを示し、好ましくはこの値が０．２〜０．９（さらには０．３５〜０．８５）であることが、現像性を維持しながら転写性を向上させるために好ましい。また、さらにトナー粒子表面に無機微粉体及びハイドロタルサイト類化合物を有することで、転写効率の向上及び文字やライン画像の転写中抜けの改善が高度に達成される。
【００４９】
本発明では、上記効果以外にトナー形状を上記の如く規定することにより、トナー像の密な充填が可能となり、得られる画像に平滑性が増し、品位ある画像となる。
【００５０】
本発明において更に高画質化のためより微小な潜像ドットを忠実に現像するために、トナー粒子は重量平均径が４μｍ〜８μｍであることが好ましい。重量平均径が４μｍ未満のトナー粒子においては、転写効率の低下から感光体上に転写残のトナーが多く、さらに、カブリ・転写不良に基づく画像の不均一ムラの原因となりやすく、本発明で使用するトナーには好ましくない。また、トナー粒子の重量平均径が８μｍを超える場合には、文字やライン画像の飛び散りが生じやすい。
【００５１】
トナーの平均粒径及び粒度分布はコールターカウンターＴＡ−ＩＩ型あるいはコールターマルチサイザー（コールター社製）等を用い、個数分布，体積分布を出力するインターフェイス（日科機製）及びＰＣ９８０１パーソナルコンピューター（ＮＥＣ製）を接続し、電解液は１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製する。たとえば、ＩＳＯＴＯＮ Ｒ−ＩＩ（コールターサイエンティフィックジャパン社製）が使用できる。測定法としては、前記電解水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤（好ましくはアルキルベンゼンスルフォン酸塩）を０．１〜５ｍｌ加え、更に測定試料を２〜２０ｍｇ加える。試料を懸濁した電解液は超音波分散器で約１〜３分間分散処理を行ない前記コールターカウンターＴＡ−ＩＩ型によりアパーチャーとして１００μｍアパーチャーを用いて、２μｍ以上のトナーの体積，個数を測定して体積分布と個数分布とを算出した。それから、本発明に係わる体積分布から求めた体積基準の重量平均粒径（Ｄ₄）、個数分布から求めた個数基準の長さ平均粒径（Ｄ₁）を求めた。
【００５２】
本発明に使用される結着樹脂の種類としては、例えば、ポリスチレン、ポリ−ｐ−クロルスチレン、ポリビニルトルエン等のスチレン及びその置換体の単重合体；スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体等のスチレン系共重合体；ポリ塩化ビニル、フェノール樹脂、天然変性フェノール樹脂、天然樹脂変性マレイン酸樹脂、アクリル樹脂、メタクリル樹脂、ポリ酢酸ビニール、シリコーン樹脂、ポリエステル樹脂、ポリウレタン、ポリアミド樹脂、フラン樹脂、エポキシ樹脂、キシレン樹脂、ポリビニルブチラール、テルペン樹脂、クマロンインデン樹脂、石油系樹脂等が使用できる。また、架橋されたスチレン系樹脂も好ましい結着樹脂である。
【００５３】
スチレン系共重合体のスチレンモノマーに対するコモノマーとしては、例えば、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸ドデシル、アクリル酸オクチル、アクリル酸−２−エチルヘキシル、アクリル酸フェニル、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸オクチル、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ような二重結合を有するモノカルボン酸もしくはその置換体；例えば、マレイン酸、マレイン酸ブチル、マレイン酸メチル、マレイン酸ジメチル、等のような二重結合を有するジカルボン酸及びその置換体；例えば、塩化ビニル、酢酸ビニル、安息香酸ビニル等のようなビニルエステル類、例えば、エチレン、プロピレン、ブチレン等のようなエチレン系オレフィン類；例えば、ビニルメチルケトン、ビニルヘキシルケトン等のようなビニルケトン類；例えば、ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテル等のようなビニルエーテル類；等のビニル単量体が単独もしくは組み合わせて用いられる。ここで架橋剤としては、主として２個以上の重合可能な二重結合を有する化合物が用いられ、例えば、ジビニルベンゼン、ジビニルナフタレン等のような芳香族ジビニル化合物；例えば、エチレングリコールジアクリレート、エチレングリコールジメタクリレート、１，３−ブタンジオールジメタクリレート等のような二重結合を２個有するカルボン酸エステル；ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド、ジビニルスルホン等のジビニル化合物；及び３個以上のビニル基を有する化合物；が単独もしくは混合物として使用できる。
【００５４】
本発明のトナーに用いる結着樹脂が酸価を有することが好ましい。樹脂が酸価を有することで、本発明のハイドロタルサイト類化合物との組み合わせにおいて、帯電の立ち上がりがより速く、帯電安定性がより高度に達成できる。結着樹脂の酸価としては、１〜３５ｍｇＫＯＨ／ｇ（より好ましくは５〜２５ｍｇＫＯＨ／ｇ）が良い。１ｍｇＫＯＨ／ｇ未満だと帯電の立ち上がりが悪く、３５ｍｇＫＯＨ／ｇを超えると環境安定性が劣る。
【００５５】
本発明に使用可能な離型剤としては、パラフィンワックス、マイクロクリスタリンワックス、ペトロラクタム等の石油系ワックス及びその誘導体、モンタンワックス及びその誘導体、フィッシャートロプシュ法による炭化水素ワックス及びその誘導体、ポリエチレンに代表されるポリオレフィンワックス及びその誘導体、カルナバワックス、キャンデリラワックス等天然ワックス及びその誘導体などで、誘導体には酸化物や、ビニル系モノマーとのブロック共重合物、グラフト変性物を含む。高級脂肪族アルコール；ステアリン酸、パルミチン酸等の脂肪酸、あるいはその化合物、酸アミド、エステル、ケトン、硬化ヒマシ油及びその誘導体、植物系ワックス、動物性ワックス等示差熱分析における吸熱ピークを６０℃以上１２０℃以下に有するものが好ましい。
【００５６】
これらの中でも、示差熱分析における吸熱ピークを６０℃以上１２０℃以下に有する化合物が、ポリオレフィンもしくはフィッシャートロプシュ法による炭化水素ワックスもしくは石油系ワックスもしくは高級アルコールである場合が本発明においては特に好ましい。
【００５７】
上記のある化合物を用いた場合、「再転写」防止効果がさらに高くなる。
【００５８】
これらの化合物は、比較的それ自身の極性が低くトナー母体の帯電を安定させるものと考えられる。
【００５９】
本発明のトナーには荷電制御剤をトナー粒子に配合（内添）、又はトナー粒子と混合（外添）して用いることが好ましい。荷電制御剤によって、現像システムに応じた最適の荷電量コントロールが可能となり、特に本発明では粒度分布と荷電量とのバランスを更に安定したものとすることが可能である。トナーを負荷電性に制御するものとして下記物質がある。
【００６０】
例えば有機金属錯体、キレート化合物が有効であり、モノアゾ金属錯体、アセチルアセトン金属錯体、芳香族ハイドロキシカルボン酸、芳香族ダイカルボン酸系の金属錯体がある。他には、芳香族ハイドロキシカルボン酸、芳香族モノ及びポリカルボン酸及びその金属塩、無水物、エステル類、ビスフェノール等のフェノール誘導体類等がある。
【００６１】
また正荷電性に制御するものとして下記物質がある。
【００６２】
ニグロシン及び脂肪酸金属塩等による変性物；トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルフォン酸塩、テトラブチルアンモニウムテトラフルオロボレート等の四級アンモニウム塩、及びこれらの類似体であるホスホニウム塩等のオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、燐タングステン酸、燐モリブデン酸、燐タングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物等）、高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイド等のジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレート等のジオルガノスズボレート類；これらを単独あるいは２種類以上組み合わせて用いることができる。
【００６３】
本発明による効果が効果的に発揮できるすなわち、帯電安定性・転写性向上が効率よく図れるのは、負帯電トナーの場合である。
【００６４】
負帯電性トナーの場合、本発明のハイドロタルサイト類はトナーに対して逆極性であり、これがトナー表面に存在することにより、帯電が減衰した場合マイクロキャリア的に帯電を上昇させ、逆にトナーがチャージアップした場合中和し、トナー帯電を均一化する。
【００６５】
正帯電性トナーに対してもチャージを補う効果があるものの安定性に関しては、負帯電性トナーとの組み合わせに劣る。
【００６６】
上述した荷電制御剤は微粒子状として用いることが好ましく、この場合これらの荷電制御剤の個数平均粒径は４μｍ以下さらには３μｍ以下が特に好ましい。これらの荷電制御剤をトナーに内添する場合は結着樹脂１００質量部に対して０．１〜２０質量部、特に０．２〜１０質量部使用することが好ましい。
【００６７】
本発明のトナーに用いられる着色剤は、黒色着色剤としてカーボンブラック，磁性体，以下に示すイエロー／マゼンタ／シアン着色剤を用い黒色に調色されたものが利用される。
【００６８】
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、９７、１０９、１１０、１１１、１２０、１２７、１２８、１２９、１４７、１６８、１７４、１７６、１８０、１８１、１９１等が好適に用いられる。
【００６９】
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。
【００７０】
シアン着色剤としては、銅フタロシアニン化合物及びその誘導体，アンスラキノン化合物，塩基染料レーキ化合物等が利用できる。具体的には、Ｃ．Ｉ．ピグメントブルー１、７、１５、１５：１、１５：２、１５：３、１５：４、６０、６２、６６等が特に好適に利用できる。
【００７１】
これらの着色剤は、単独又は混合し更には固溶体の状態で用いることができる。本発明の着色剤は、色相角，彩度，明度，耐候性，ＯＨＰ透明性，トナー中への分散性の点から選択される。該着色剤の添加量は、樹脂１００質量部に対し１〜２０質量部添加して用いられる。
【００７２】
黒色着色剤として磁性体を用いた場合には、他の着色剤と異なり、樹脂１００質量部に対し３０〜２００質量部添加して用いられる。
【００７３】
磁性体としては、鉄，コバルト，ニッケル，銅，マグネシウム，マンガン，アルミニウム，珪素などの元素を含む金属酸化物などがある。中でも四三酸化鉄，γ−酸化鉄等，酸化鉄を主成分とするものが好ましい。また、トナー帯電性コントロールの観点から硅素元素またはアルミニウム元素等、他の金属元素を含有していてもよい。これら磁性粒子は、窒素吸着法によるＢＥＴ比表面積が好ましく２〜３ｍ²／ｇ、特に３〜２８ｍ²／ｇ、更にモース硬度が５〜７の磁性粉が好ましい。
【００７４】
磁性体の形状としては、８面体，６面体，球体，針状，鱗片状などがあるが、８面体，６面体，球体，不定型等の異方性の少ないものが画像濃度を高める上で好ましい。磁性体の平均粒径としては０．０５〜１．０μｍが好ましく、さらに好ましくは０．１〜０．６μｍ、さらには、０．１〜０．４μｍが好ましい。
【００７５】
磁性体量は結着樹脂１００質量部に対し３０〜２００質量部、好ましくは４０〜２００質量部、さらには５０〜１５０質量部が好ましい。３０質量部未満ではトナー搬送に磁気力を用いる現像器においては、搬送性が不十分で現像剤担持体上の現像剤層にムラが生じ画像ムラとなる傾向であり、さらに現像剤トリボの上昇に起因する画像濃度の低下が生じ易い傾向であった。一方、２００質量部を超えると定着性に問題が生ずる傾向であった。
【００７６】
また本発明のトナーに含有される無機微粉体としては公知のものが用いられるが、帯電安定性，現像性，流動性，保存性向上のため、シリカ，アルミナ，チタニアあるいはその複酸化物の中から選ばれることが好ましい。さらには、シリカであることがより好ましい。例えば、かかるシリカは硅素ハロゲン化物やアルコキシドの蒸気相酸化により生成されたいわゆる乾式法又はヒュームドシリカと称される乾式シリカ及びアルコキシド，水ガラス等から製造されるいわゆる湿式シリカの両者が使用可能であるが、表面及びシリカ微粉体の内部にあるシラノール基が少なく、またＮａ₂Ｏ，ＳＯ_３ ^２−等の製造残滓の少ない乾式シリカの方が好ましい。また乾式シリカにおいては、製造工程において例えば、塩化アルミニウム，塩化チタン等他の金属ハロゲン化合物を硅素ハロゲン化合物と共に用いることによって、シリカと他の金属酸化物の複合微粉体を得ることも可能でありそれらも包含する。
【００７７】
本発明に用いられる無機微粉体は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ²／ｇ以上、特に５０〜４００ｍ²／ｇの範囲のものが良好な結果を与え、トナー１００質量部に対してシリカ微粉末０．１〜８質量部、好ましくは０．５〜５質量部、さらに好ましくは１．０を超えて３．０質量部まで使用するのが特に良い。
い。
【００７８】
また、本発明に用いられる無機微粉体は、必要に応じ、疎水化，帯電性制御等の目的でシリコーンワニス，各種変性シリコーンワニス，シリコーンオイル，各種変性シリコーンオイル，シランカップリング剤，官能基を有するシランカップリング剤，その他有機硅素化合物，有機チタン化合物等の処理剤で、あるいは、種々の処理剤で併用して処理されていることも可能であり好ましい。
【００７９】
また、本発明においては、クリーニング性向上等のために、前記無機微粉体及びハイドロタルサイト類化合物に加えて、さらに一次粒径が３０ｎｍを超える（好ましくは比表面積が５０ｍ²／ｇ未満）、より好ましくは５０ｎｍ以上（好ましくは比表面積が３０ｍ²／ｇ未満）の無機又は有機の球状に近い微粒子をさらに添加することも好ましい形態の一つである。例えば球状シリカ粒子，球状ポリメチルシルセスキオキサン粒子，球状樹脂粒子等が好ましく用いられる。
【００８０】
本発明のトナーにおいては、実質的な悪影響を与えない範囲内で更に他の添加剤、例えばテフロン粉末、ステアリン酸亜鉛粉末、ポリフッ化ビニリデン粉末の如き滑剤粉末；酸化セリウム粉末、炭化硅素粉末、チタン酸ストロンチウム粉末などの研磨剤；例えば酸化チタン粉末、酸化アルミニウム粉末などの流動性付与剤；ケーキング防止剤、あるいは例えばカーボンブラック粉末、酸化亜鉛粉末、酸化スズ粉末等の導電性付与剤、また、逆極性の有機微粒子及び無機微粒子を現像性向上剤として少量用いることもできる。
【００８１】
本発明に係わるトナーを作製するには、公知の方法が用いられるが、例えば、結着樹脂、ワックス、金属塩ないしは金属錯体、着色剤としての顔料、染料、又は磁性体、必要に応じて荷電制御剤、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てから加熱ロール、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お互いに相溶せしめた中に金属化合物、顔料、染料、磁性体を分散又は溶解せしめ、冷却固化、粉砕後、分級及び表面処理を行なってトナー粒子を得、無機微粉体及びハイドロタルサイト類化合物を添加混合することによって、本発明に係るトナーを得ることが出来る。分級及び表面処理の順序は、どちらが先でも良い。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。
【００８２】
本発明のトナーの特定の円形度分布及び粒度分布を達成するためには、機械衝撃式、ジェット式等の公知の粉砕装置を用いた方法により粉砕（必要に応じて分級）するだけでも良い。よりシャープな円形度分布を得る場合には、熱をかけて粉砕したり、さらに補助的に機械的衝撃を加える処理をすることが好ましい。
【００８３】
また、微粉砕（必要に応じて分級）されたトナー粒子を熱水中に分散させる湯浴法、熱気流中を通過させる方法などを用いても良いが、トナーの帯電量が低くなり転写特性及びその他画像特性、更に生産性の面でも機械的衝撃力による処理を加える方法が最も好ましい。
【００８４】
機械的衝撃力を加える手段としては、例えば川崎重工社製のクリプトロンシステムやターボ工業社製のターボミル等の機械衝撃式粉砕機を用いる方法、また、ホソカワミクロン社製のメカノフージョンシステムや奈良機械製作所製のハイブリダイゼーションシステム等の装置のように、高速回転する羽根によりトナーをケーシングの内側に遠心力により押しつけ、圧縮力、摩擦力等の力によりトナーに機械的衝撃力を加える方法が挙げられる。
【００８５】
また、本発明のトナーの特定の円形度分布及び粒度分布を達成するためには、特公昭５６−１３９４５号公報等に記載のディスク又は多流体ノズルを用い溶融混合物を空気中に霧化し球状トナーを得る方法や、特公昭３６−１０２３１号公報，特開昭５９−５３８５６号公報，特開昭５９−６１８４２号公報に述べられている懸濁重合方法を用いて直接トナーを生成する方法や、単量体には可溶で得られる重合体が不溶な水系有機溶剤を用い直接トナーを生成する方法や、単量体には可溶で得られる重合体が不溶な水系有機溶剤を用い直接トナーを生成する分散重合方法又は水溶性極性重合開始剤存在下で直接重合しトナーを生成するソープフリー重合方法に代表される乳化重合方法等を用いトナーを製造することが可能である。
【００８６】
本発明は、像担持体の表面が高分子結着剤を主体として構成される場合に有効である。例えば、セレン，アモルファスシリコンなどの無機像担持体の上に樹脂を主体とした、保護膜を設ける場合、又は機能分離型有機像担持体の電荷輸送層として、電荷輸送材と樹脂からなる表面層をもつ場合、さらにその上に上記のような保護層を設ける場合等がある。このような表面層に離型性を付与する手段としては、▲１▼膜を構成する樹脂自体に表面エネルギーの低いものを用いる、▲２▼撥水，親油性を付与するような添加剤を加える、▲３▼高い離型性を有する材料を粉体状にして分散する、などが挙げられる。▲１▼の例としては、樹脂の構造中にフッ素含有基、シリコン含有基等を導入することにより達成する。▲２▼としては、界面活性剤等を添加剤とすればよい。▲３▼としては、フッ素原子を含む化合物、すなわちポリ４フッ化エチレン、ポリフッ化ビニリデン、フッ化カーボン等の粉体が挙げられる。この中でも特にポリ４フッ化エチレンが好適である。本発明においては、▲３▼の含フッ素樹脂などの離型性粉体の最表面層への分散が特に好適である。
【００８７】
これらの手段によって像担持体表面の水に対する接触角を８５度以上（好ましくは９０度以上）とすることができる。８５度未満では耐久によるトナーおよびトナー担持体の劣化が生じやすい。
【００８８】
これらの粉体を表面に含有させるためには、バインダー樹脂中に該粉体を分散させた層を像担持体最表面に設けるか、あるいは、元々樹脂を主体として構成されている有機像担持体であれば、新たに表面層を設けなくても、最上層に該粉体を分散させれば良い。
【００８９】
該粉体の表面層への添加量は、表面層総質量に対して、１〜６０質量％、さらには、２〜５０質量％が好ましい。１質量％より少ないとトナー及びトナー担持体の耐久性改善の効果が不十分であり、６０質量％を超えると膜の強度が低下したり、像担持体への入射光量が著しく低下したりするため、好ましくない。
【００９０】
本発明は、帯電手段が帯電部材を像担持体に当接させる直接帯電法の場合に特に効果的である。帯電手段が像担持体に接することのないコロナ放電等に比べて、像担持体表面に対する負荷が大きいので像担持体寿命という点で改善効果が顕著であり、好ましい適用形態の一つである。
【００９１】
本発明に用いられる像担持体の好ましい態様の一つを以下に説明する。
【００９２】
導電性基体としては、アルミニウム，ステンレス等の金属、アルミニウム合金，酸化インジウム−酸化錫合金等による被膜層を有するプラスチック、導電性粒子を含浸させた紙，プラスチック，導電性ポリマーを有するプラスチック等の円筒状シリンダー及びフィルムが用いられる。
【００９３】
これら導電性基体上には、感光層の接着性向上，塗工性改良，基体の保護，基体上の欠陥の被覆，基体からの電荷注入性改良，感光層の電気的破壊に対する保護等を目的として下引き層を設けても良い。下引き層は、ポリビニルアルコール，ポリ−Ｎ−ビニルイミダゾール，ポリエチレンオキシド，エチルセルロース，メチルセルロース，ニトロセルロース，エチレン−アクリル酸コポリマー，ポリビニルブチラール，フェノール樹脂，カゼイン，ポリアミド，共重合ナイロン，ニカワ，ゼラチン，ポリウレタン，酸化アルミニウム等の材料によって形成される。その膜厚は通常０．１〜１０μｍ、好ましくは０．１〜３μｍ程度である。
【００９４】
電荷発生層は、アゾ系顔料，フタロシアニン系顔料，インジゴ系顔料，ペリレン系顔料，多環キノン系顔料，スクワリリウム色素，ピリリウム塩類，チオピリリウム塩類，トリフェニルメタン系色素、セレン，非晶質シリコン等の無機物質などの電荷発生物質を適当な結着剤に分散し塗工あるいは蒸着等により形成される。結着剤としては、広範囲な結着性樹脂から選択でき、例えば、ポリカーボネート樹脂，ポリエステル樹脂，ポリビニルブチラール樹脂，ポリスチレン樹脂，アクリル樹脂，メタクリル樹脂，フェノール樹脂，シリコーン樹脂，エポキシ樹脂，酢酸ビニル樹脂等が挙げられる。電荷発生層中に含有される結着剤の量は８０質量％以下、好ましくは０〜４０質量％に選ぶ。また、電荷発生層の膜厚は５μｍ以下、特には０．０５〜２μｍが好ましい。
【００９５】
電荷輸送層は、電界の存在下で電荷発生層から電荷キャリアを受け取り、これを輸送する機能を有している。電荷輸送層は電荷輸送物質を必要に応じて結着樹脂と共に溶剤中に溶解し、塗工することによって形成され、その膜厚は一般的には５〜４０μｍである。電荷輸送物質としては、主鎖または側鎖にビフェニレン，アントラセン，ピレン，フェナントレンなどの構造を有する多環芳香族化合物、インドール，カルバゾール，オキサジアゾール，ピラゾリンなどの含窒素環式化合物、ヒドラゾン化合物、スチリル化合物、セレン，セレン−テルル，非晶質シリコン，硫化カドニウム等が挙げられる。
【００９６】
また、これら電荷輸送物質を分散させる結着樹脂としては、ポリカーボネート樹脂，ポリエステル樹脂，ポリメタクリル酸エステル，ポリスチレン樹脂，アクリル樹脂，ポリアミド樹脂等の樹脂、ポリ−Ｎ−ビニルカルバゾール，ポリビニルアントラセン等の有機光導電性ポリマー等が挙げられる。
【００９７】
また、表面層として、保護層を設けてもよい。保護層の樹脂としては、ポリエステル，ポリカーボネート，アクリル樹脂，エポキシ樹脂，フェノール樹脂、あるいはこれらの樹脂の硬化剤等が単独あるいは２種以上組み合わされて用いられる。
【００９８】
また、保護層の樹脂中に導電性微粒子を分散してもよい。導電性微粒子の例としては、金属，金属酸化物等が挙げられ、好ましくは、酸化亜鉛，酸化チタン，酸化スズ，酸化アンチモン，酸化インジウム，酸化ビスマス，酸化スズ被膜酸化チタン，スズ被膜酸化インジウム，アンチモン被膜酸化スズ，酸化ジルコニウム等の超微粒子がある。これらは単独で用いても２種以上を混合して用いても良い。一般的に保護層に粒子を分散させる場合、分散粒子による入射光の散乱を防ぐために入射光の波長よりも粒子の粒径の方が小さいことが必要であり、本発明における保護層に分散される導電性，絶縁性粒子の粒径としては０．５μｍ以下であることが好ましい。また、保護層中での含有量は、保護層総質量に対して２〜９０質量％が好ましく、５〜８０質量％がより好ましい。保護層の膜厚は、０．１〜１０μｍが好ましく、１〜７μｍがより好ましい。
【００９９】
表面層の塗工は、樹脂分散液をスプレーコーティング，ビームコーティングあるいは浸透（ディッピング）コーティングすることによって行うことができる。
【０１００】
次に、本発明のトナーを用いる画像形成方法に適用可能な接触転写工程について具体的に説明する。
【０１０１】
接触転写工程とは、静電荷像担持体又は中間転写体と転写材を介して転写手段を当接しながら現像画像を転写材に静電転写するのであるが、転写手段の当接圧力としては線圧２．９Ｎ／ｍ（３ｇ／ｃｍ）以上であることが好ましく、より好ましくは１９．６Ｎ／ｍ（２０ｇ／ｃｍ）以上である。当接圧力としての線圧が２．９Ｎ／ｍ（３ｇ／ｃｍ）未満であると、転写材の搬送ずれや転写不良の発生が起こりやすくなるため好ましくない。
【０１０２】
接触転写工程における転写手段としては、転写ローラーあるいは転写ベルトを有する装置が使用される。図５に示した転写ローラー１１４は少なくとも芯金１１４ａと導電性弾性層１１４ｂから構成され、導電性弾性層はカーボンの如き導電材を分散させたウレタンやＥＰＤＭの如き、体積抵抗１０⁶〜１０¹⁰Ωｃｍ程度の弾性体で作られている。
【０１０３】
本発明は、静電潜像担持体（感光体）の表面が有機化合物である様な画像形成装置において特に有効に用いられる。即ち、有機化合物が感光体の表面層を形成している場合には、無機材料を用いた他の感光体よりもトナー粒子に含まれる結着樹脂との接着性に優れ、転写性がより低下する傾向にあるためである。
【０１０４】
本発明に係る感光体の表面物質としては、たとえばシリコーン樹脂、塩化ビニリデン、エチレン−塩化ビニル、スチレン−アクリロニトリル、スチレン−メチルメタクリレート、スチレン、ポリエチレンテレフタレートおよびポリカーボネートが挙げられるが、これらに限定されることなく他のモノマーあるいは前述の結着樹脂間での共重合体およびブレンド体も使用することができる。
【０１０５】
本発明は、直径が５０ｍｍ以下の小径の感光体を有する画像形成装置に対し特に有効に用いられる。即ち、小径感光体の場合には、同一の線圧に対する曲率が大きく、当接部における圧力の集中が起こりやすいためである。ベルト感光体でも同一の現象があると考えられるが、本発明は、転写部での曲率半径が２５ｍｍ以下の画像形成装置に対しても有効である。
【０１０６】
また本発明のトナーは、トナー担持体上のトナーを規制する部材によってトナー担持体上のトナー層厚よりも像担持体とトナー担持体の最近接間隙が広くなるように設定して用いるが、トナー担持体上の磁性トナーを規制する部材がトナーを介してトナー担持体に当接されている弾性部材によって規制されることが、トナーを均一帯電させる観点から特に好ましい。
【０１０７】
また、本発明に使用されるトナー担持体の表面粗さはＪＩＳ中心線平均粗さ（Ｒａ）で０．２〜３．５μｍの範囲にあることが好ましい。
【０１０８】
Ｒａが０．２μｍ未満ではトナー担持体上の帯電量が高くなり、現像性が不充分となる。Ｒａが３．５μｍを超えると、トナー担持体上のトナーコート層にムラが生じ、画像上で濃度ムラとなる。さらに好ましくは、０．５〜３．０μｍの範囲にあることが好ましい。
【０１０９】
さらに本発明の磁性トナーは高い帯電能力を有するために現像に際しては、トナーの総帯電量をコントロールすることが望ましく、本発明に係わるトナー担持体の表面は導電性微粒子及び／又は滑剤を分散した樹脂層で被覆されていることが好ましい。
【０１１０】
トナー担持体表面を被覆する樹脂層に含有される導電性微粒子としては、カーボンブラック、グラファイト、導電性酸化亜鉛等の導電性金属酸化物及び金属複酸化物、などが単独もしくは２つ以上好ましく用いられる。また、該導電性微粒子が分散される樹脂としては、フェノール系樹脂、エポキシ系樹脂、ポリアミド系樹脂、ポリエステル系樹脂、ポリカーボネート系樹脂、ポリオレフィン系樹脂、シリコーン系樹脂、フッ素系樹脂、スチレン系樹脂、アクリル系樹脂など公知の樹脂が用いられる。
【０１１１】
特に熱硬化性もしくは、光硬化性の樹脂が好ましい。
【０１１２】
本発明において一成分現像方法を用いる場合には、高画質を得るためにトナー担持体上に、トナー担持体−潜像担持体の最近接距離（Ｓ−Ｄ間）よりも小さい層厚で、磁性トナーを塗布し、交番電界を印加して現像を行う現像工程で現像されることが好ましい。
【０１１３】
本発明においてはオゾンが発生しないように帯電部材が感光体に当接されていることが環境保全上好ましい。
【０１１４】
帯電ローラーを用いたときの好ましいプロセス条件としては、ローラーの当接圧が５〜５００ｇ／ｃｍで、直流電圧に交流電圧を重畳したものを用いたときには、交流電圧＝０．５〜５ｋＶｐｐ，交流周波数＝５０〜５ｋＨｚ，直流電圧＝±０．２〜±５ｋＶである。
【０１１５】
この他の帯電手段としては、帯電ブレードを用いる方法や、導電性ブラシを用いる方法がある。これらの接触帯電手段は、高電圧が不要になったり、オゾンの発生が低減するといった効果がある。
【０１１６】
接触帯電手段としての帯電ローラー及び帯電ブレードの材質としては、導電性ゴムが好ましく、その表面に離型性被膜を設けてもよい。離型性被膜としては、ナイロン系樹脂，ＰＶＤＦ（ポリフッ化ビニリデン），ＰＶＤＣ（ポリ塩化ビニリデン）及びフッ素アクリル樹脂が適用可能である。
【０１１７】
次に本発明の画像形成方法の好ましい形態を図に沿って具体的に説明する。
【０１１８】
図１において、１００は静電潜像担持体（感光体）で、その周囲に一次帯電部材１１７、現像器１４０、転写手段１１４、クリーナ１１６、レジストローラー１２４等が設けられている。静電潜像担持体１００に当接する一次帯電部材１１７にバイアスを印加して、静電潜像担持体１００は一様に一次帯電される。そして、レーザー発生装置１２１によりレーザー光１２３を潜像担持体１００に照射、露光することによって静電潜像が形成される。現像器１４０は図２に示すように潜像担持体１００に近接して、アルミニウム，ステンレス等非磁性金属で作られた円筒状の基体上に被覆層を設けたトナー担持体（現像スリーブ）１０２が配設され、潜像担持体１００とトナー担持体１０２との間隙は、図示されないトナー担持体／潜像担持体間隙保持部材等により一定に維持されている。また現像器内には撹拌棒１４１が配設され、現像スリーブ内には複数の磁極を有するマグネットローラー１０４がトナー担持体１０２と同心的に固定、配設されており、トナー担持体１０２は回転可能である。マグネットローラー１０４には図示の如く複数の磁極が具備されており、Ｓ₁は現像、Ｎ₁はトナー量規制、Ｓ₂はトナーの取り込み／搬送、Ｎ₂はトナーの吹き出し防止に影響している。トナー担持体１０２に付着して搬送される磁性トナー量を規制する部材として当接ブレード１０３が配設され、トナー担持体１０２に搬送されるトナー量を制御する。現像領域では、潜像担持体１００とトナー担持体１０２との間に現像バイアスが印加され、トナー担持体上トナーは静電潜像に応じて潜像担持体１００上に飛翔し可視像となる。
【０１１９】
【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。尚、以下の配合における部数は全て質量部である。
【０１２０】

【０１２１】
上記材料をブレンダーにて混合し、１１０℃に加熱した二軸エクストルーダーで溶融混練し、冷却した混練物をハンマーミルで粗粉砕し、粗粉砕物を機械式粉砕器で微粉砕し、得られた微粉砕物をコアンダ効果を用いた多分割分級機にて厳密に分級し、その後衝撃式表面処理装置（処理温度６０℃、回転式処理ブレード周速１００ｍ／ｓｅｃ．）て磁性トナー粒子（１）を得た。
【０１２２】
ついで、得られた磁性トナー粒子（１）１００部に対し、ヘキサメチルジシラザンとシリコーンオイルで疎水化処理された一次粒径１２ｎｍの乾式シリカ１．２部とハイドロタルサイト〔Ｍｇ_0.72Ａｌ_0.28（ＯＨ）₂（ＣＯ₃）_0.14・０．５４Ｈ₂Ｏ；ＢＥＴ比表面積１０ｍ²／ｇ〕０．３部を添加し、混合機にて混合し磁性トナー１を得た。得られた磁性トナー１は重量平均粒径６．９μｍ、ＳＦ−１が１２０、ＳＦ−２が１１５であった。得られた磁性トナー１のその他の物性を表１に示す。
【０１２３】
＜評価方法＞
（感光体製造例１）
感光体としては直径３０ｍｍのＡｌシリンダーを基体とした。これに、図３に示すような構成の層を順次浸漬塗布により積層して、感光体を作製した。
【０１２４】
（１）導電性被覆層：酸化錫及び酸化チタンの粉末をフェノール樹脂に分散したものを主体とする。膜厚１５μｍ。
【０１２５】
（２）下引き層：変性ナイロン及び共重合ナイロンを主体とする。膜厚０．６μｍ。
【０１２６】
（３）電荷発生層：長波長域に吸収を持つアゾ顔料をブチラール樹脂に分散したものを主体とする。膜厚０．６μｍ。
【０１２７】
（４）電荷輸送層：ホール搬送性トリフェニルアミン化合物をポリカーボネート樹脂（オスワルド粘度法による分子量２万）に８：１０の質量比で溶解したものを主体とし、さらにポリ４フッ化エチレン粉体（粒径０．２μｍ）を総固形分に対して３質量％添加し、均一に分散した。膜厚１５μｍ。水に対する接触角は８７度であった。
【０１２８】
なお、接触角の測定は純水を用い、装置は協和界面科学（株）、接触角計ＣＡ−Ｘ型を用いた。
【０１２９】
画像形成装置として、概ね図１に示されるものを用いた。
【０１３０】
静電潜像担持体として（感光体製造例１）の有機感光体（ＯＰＣ）ドラムを用い暗部電位Ｖｄ＝−６００Ｖ，明部電位ＶＬ＝−２００Ｖとした。感光ドラムと現像スリーブとの間隙を３００μｍとし、トナー担持体として下記の構成の層厚約７μｍ，ＪＩＳ中心線平均粗さ（Ｒａ）１．３μｍの樹脂層を、表面が鏡面である直径２０φのアルミニウム円筒上に形成した現像スリーブを使用し、現像磁極が９５ｍＴ（９５０ガウス）で、トナー規制部材として厚み１．０ｍｍ，自由長１０ｍｍのウレタンゴム製ブレードを１４．７Ｎ／ｍ（１５ｇ／ｃｍ）の線圧で当接させた。
フェノール樹脂 １００部
グラファイト（粒径約７μｍ） ９０部
カーボンブラック １０部
【０１３１】
次いで、現像バイアスとして直流バイアス成分Ｖｄｃ＝−４００Ｖ，重畳する交流バイアス成分Ｖ_P-P＝１６００Ｖ，ｆ＝２０００Ｈｚを用いた。また、現像スリーブの周速は感光体周速（１００ｍｍ／ｓｅｃ）に対して順方向に１００％のスピード（１００ｍｍ／ｓｅｃ）とした。
【０１３２】
また、図５のような転写ローラー（導電性カーボンを分散したエチレン−プロピレンゴム製、導電性弾性層の体積抵抗値１０⁶Ωｃｍ、表面ゴム硬度２２°、直径２０ｍｍ、当接圧４９Ｎ／ｍ（５０ｇ／ｃｍ））を、感光体周速（１００ｍｍ／ｓｅｃ）に対して等速とし、転写バイアスを２〜２０μＡの間で振って転写性のラチチュードを評価した。トナーとして磁性トナー１を使用し、２８．５℃，８５％ＲＨ環境下で転写バイアスを２〜２０μＡの間で振って転写性のラチチュードを評価した。転写紙としては９０ｇ／ｍ²の紙を使用した。
【０１３３】
この時の感光体から転写材への転写効率９０％以上が得られる範囲は、４〜１８μＡと広い条件において高い転写効率を示し、文字やラインの転写中抜けもなく、画像上に飛び散りのない良好な画像が得られた。転写性はベタ黒の感光体上の転写残トナーをマイラーテープにより、テーピングしてはぎ取り、紙上に貼ったもののマクベス濃度から、テープのみを貼ったもののマクベス濃度を差し引いた数値で評価した。
【０１３４】
また、中央から左半分にベタ白画像、右半分にベタ黒画像を配置した画像で３０．０℃，８０％ＲＨ環境下で耐久をし、現像スリーブ上のトナーの帯電量を測定した。
【０１３５】
評価結果を表２に示す。耐久初期・後期双方ともベタ白部とベタ黒部のトナー帯電量差が少なく、また耐久前期・後期でのベタ白部の帯電量差が少なく、濃度変動、カブリ、画像飛び散りのないドット再現性に優れた画像が得られた。
【０１３６】
（実施例２）
実施例１における衝撃式表面処理装置の条件を変更して、磁性トナー粒子（２）を得た。
【０１３７】
得られた磁性トナー粒子（２）１００部に対し、ヘキサメチルジシラザンとシリコーンオイルで疎水化処理された一次粒径１１ｎｍの乾式シリカ１．４部とハイドロタルサイト０．０８部を添加し、混合機にて混合し磁性トナー２を得た。得られた磁性トナー２のその他物性を表１に示す。
【０１３８】
トナーとして上記のトナー２を使用した以外は実施例１と同様の装置・条件で画出しを行ったところ、表２に示した様に良好な結果が得られた。
【０１３９】
（実施例３）
実施例１における衝撃式表面処理装置の条件を変更して、磁性トナー粒子（３）を得た。
【０１４０】
得られた磁性トナー粒子（３）１００部に対し、ヘキサメチルジシラザンとシリコーンオイルで疎水化処理された一次粒径１１ｎｍの乾式シリカ１．４部とハイドロタルサイト０．７部を添加し、混合機にて混合し磁性トナー３を得た。得られた磁性トナー３のその他物性を表１に示す。
【０１４１】
トナーとして上記のトナー３を使用した以外は実施例１と同様の装置・条件で画出しを行った。その結果、表２に示した様に良好な結果が得られた。
【０１４２】
（実施例４）
実施例１における衝撃式表面処理装置の条件を変更して、磁性トナー粒子（４）を得た。
【０１４３】
得られた磁性トナー粒子（４）１００部に対し、ヘキサメチルジシラザンとシリコーンオイルで疎水化処理された一次粒径１１ｎｍの乾式シリカ１．４部とハイドロタルサイト１．２部を添加し、混合機にて混合し磁性トナー４を得た。得られた磁性トナー４のその他物性を表１に示す。
【０１４４】
トナーとして上記の磁性トナー４を使用した以外は実施例１と同様の装置・条件で画出しを行った。その結果、表２に示した様に良好な結果が得られた。
【０１４５】

【０１４６】
上記材料をブレンダーにて混合し、１３０℃に加熱した二軸エクストルーダーで溶融混練し、冷却した混練物をハンマーミルで粗粉砕し、粗粉砕物をジェットミルで微粉砕し、得られた微粉砕物をコアンダ効果を用いた多分割分級機にて厳密に分級して磁性トナー粒子（５）を得た。
【０１４７】
得られた磁性トナー粒子（５）１００部に対し、１．０部のヘキサメチルジシラザンで疎水化処理した一次粒径約１６ｎｍの乾式シリカ（ＢＥＴ比表面積１００ｍ²／ｇ）を１．２部添加し、混合機にて混合し磁性トナー５を得た。得られた磁性トナー５の物性を表１に示す。
【０１４８】
トナーとして上記のトナー５を使用する以外は、実施例１と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率９０％以上が得られる範囲は８μＡのみであり、十分な転写ラチチュードは得られなかった。また、やや文字やラインの転写中抜けが多く、飛び散りが非常に多い画像であった。
【０１４９】
（比較例２）
比較例１と同様にして、磁性トナー粒子（６）を得た。
【０１５０】
得られた磁性トナー粒子（６）１００部に対し、ヘキサメチルジシラザンとシリコーンオイルで疎水化処理された一次粒径１１ｎｍの乾式シリカ１．４部とハイドロタルサイト０．７部を添加し、混合機にて混合し磁性トナー６を得た。得られた磁性トナー６のその他物性を表１に示す。
【０１５１】
トナーとして上記のトナー６を使用した以外は実施例１と同様の装置・条件で画出しを行った。その結果、感光体から転写材への転写効率９０％以上が得られる範囲は６〜８μＡのみであり、十分な転写ラチチュードは得られず、しかも画像濃度が薄く貧弱な、飛び散りが非常に多い画像であった。
【０１５２】
【表１】

【０１５３】
【表２】

【０１５４】
【発明の効果】
帯電安定性に優れ、高画像濃度・潜像再現性を保持しつつ、高品位で鮮鋭な画像が得られる。特に従来のトナーと比較して幅広い転写ラチチュードが得られ、特に非磁性のフルカラートナーと同時一括転写するプロセスにおいて非常に有効である。
【図面の簡単な説明】
【図１】本発明の実施例に用いた画像形成装置の一例の説明図である。
【図２】図１の要部拡大図である。
【図３】感光体の構成の一例を示す説明図である。
【図４】形状係数ＳＦ−１，ＳＦ−２における、本発明の範囲を示す図である。
【図５】当接転写部材の一例を示す図である。
【符号の説明】
１００ 感光ドラム
１０２ 現像スリーブ（トナー担持体）
１０３ 当接ブレード
１０４ マグネットローラー
１１４ 転写帯電ローラー
１１６ クリーナ
１１７ 一次帯電ローラー
１４０ 現像器
１４１ 攪拌棒[0001]
BACKGROUND 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 recording method, or the like. More specifically, the present invention relates to a toner used in a copying machine, a printer, and a fax machine that 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.
[0002]
[Prior art]
Conventionally, many methods are known as electrophotographic methods. Generally, a photoconductive substance is used to form an electric latent image on an image carrier (photosensitive member) by various means, and then the electrophotographic method is used. The latent image is developed with toner to form a visible image. If necessary, the toner image is transferred onto a transfer material such as paper, and then the toner image is fixed on the transfer material by heat and pressure to obtain a copy. Is.
[0003]
As a method for visualizing an electric latent image, a cascade development method, a magnetic brush development method, a pressure development method, and the like are known. Further, there is also used a method in which a magnetic toner is used and a rotating sleeve having a magnetic pole at the center is used to fly between the photosensitive member and the sleeve by an electric field.
[0004]
Since the one-component development method does not require carrier particles such as glass beads or iron powder as in the two-component method, the development device itself can be reduced in size and weight. Furthermore, since the two-component development method needs to keep the toner concentration in the carrier constant, a device for detecting the toner concentration and supplying a necessary amount of toner is required. Therefore, the developing device is also large and heavy here. Since such a device is not necessary in the one-component development method, it is preferable because it can be made small and light.
[0005]
In addition, LED and LBP printers are the mainstream in the recent market as printer devices, and the direction of technology is higher resolution, that is, what was conventionally 240, 300 dpi has become 400, 600, 800 dpi. Accordingly, the development method is also required to have higher definition. In addition, copiers are also becoming more sophisticated, and therefore are moving toward digitalization. Since this method is mainly a method of forming an electrostatic charge image with a laser, it is also proceeding in the direction of high resolution, and here again, a high-resolution and high-definition developing method is required as in the case of a printer. . For this reason, the toner particle size has been reduced. No. 4, JP-A-4-162048, etc. propose a toner having a specific particle size distribution and a small particle size.
[0006]
The toner image formed on the photoconductor in the development process is transferred to the transfer material in the transfer process, but the transfer residual toner remaining on the photoconductor is cleaned in the cleaning process, and the toner is stored in the waste toner container. For this cleaning process, conventional blade cleaning, fur brush cleaning, roller cleaning, and the like have been used. From the standpoint of the apparatus, since the apparatus is inevitably enlarged in order to have such a cleaning apparatus, it has become a bottleneck when aiming to make the apparatus compact. Furthermore, from the viewpoint of ecology, a system with little waste toner is desired in the sense of effective use of toner, and a toner with high transfer efficiency has been demanded.
[0007]
Japanese Patent Application Laid-Open No. 61-279864 proposes a toner that defines shape factors SF-1 and SF-2. However, this publication has no description regarding transfer, and as a result of carrying out the examples, the transfer efficiency is low and further improvement is required.
[0008]
Further, Japanese Patent Laid-Open No. 63-235953 proposes a magnetic toner that has been spheroidized by a mechanical impact force. However, the transfer efficiency is still insufficient and further improvement is necessary.
[0009]
In recent years, from the viewpoint of environmental protection, primary charging and transfer processes using a photoreceptor contact member are becoming mainstream from the conventional primary charging and transfer processes using corona discharge.
[0010]
For example, Japanese Patent Laid-Open Nos. 63-149669 and 2-123385 have been proposed. These relate to a contact charging method and a contact transfer method, and a conductive elastic roller is brought into contact with the electrostatic latent image carrier and a voltage is applied to the conductive roller while the electrostatic latent image carrier is integrated. Then, after a toner image is obtained by exposure and development processes, a transfer material is passed through the electrostatic latent image carrier while pressing another conductive roller to which a voltage is applied. After the toner image on the image carrier is transferred to a transfer material, a transfer image is obtained through a fixing process.
[0011]
However, in such a roller transfer method that does not use corona discharge, the transfer member is brought into contact with the photoconductor through the transfer member during transfer, so that the toner image formed on the photoconductor is transferred to the transfer material. At this time, the toner image is brought into pressure contact, which causes a problem of partial transfer failure called so-called transfer omission.
[0012]
In addition, as the diameter of the toner decreases, the adhesion force (mirror image force, van der Waals force, etc.) of the toner particles to the photosensitive member becomes larger than the Coulomb force applied to the toner particles during transfer, resulting in a residual transfer. There was a tendency for toner to increase.
[0013]
Furthermore, in recent years, there has been an increasing demand for colorization in copying machines, printers, fax machines, and the like using electrophotography.
[0014]
In general, a color toner is a non-magnetic toner because it is difficult to use a magnetic toner containing a magnetic substance because of its color. In a color electrophotographic apparatus using a magnetic toner as a black toner and a non-magnetic toner as a color toner, the optimum transfer current value of the non-magnetic toner is higher than the optimum transfer current value of the magnetic toner. For this reason, when the transfer condition of the apparatus main body is set to the non-magnetic toner, the magnetic toner causes a so-called retransfer problem that the toner transferred to the transfer material returns to the latent image carrier. Conversely, when the optimum transfer condition is matched with the black toner, transfer failure of the non-magnetic toner occurs.
[0015]
Transfer when using such magnetic toner and non-magnetic toner at the same time is a problem that must be improved in order to obtain a color electrophotographic apparatus capable of obtaining high resolution and high definition images at a small size, light weight and low cost. there were.
[0016]
On the other hand, as a toner containing hydrotalcites, an Mg-Al system has been proposed in Japanese Patent No. 2854306, but NO from the surface of the photoconductor._XThe purpose of this is to remove the charging stability and the like. Further, for the purpose of charging stability in Japanese Patent No. 2683331, Japanese Patent Laid-Open No. 6-138597, etc., for example, a ternary system in which one or two divalent metals (Zn or the like) are added to an Mg—Al system, for example. Toners containing hydrotalcites have been proposed. However, charging stability and transferability in a harsher environment are still insufficient.
[0017]
[Problems to be solved by the invention]
An object of the present invention is to provide a toner that solves the above-mentioned problems of the prior art.
[0018]
That is, an object of the present invention is to provide a toner that is excellent in transferability, has a small amount of residual toner, and does not cause transfer loss even in a roller transfer system, or in which development thereof is suppressed.
[0019]
It is a further object of the present invention to provide a toner that has excellent charging stability even under harsh environments, and has low image density due to charge-up during endurance and charge-down during standing, and image defects such as fogging.
[0020]
A further object of the present invention is to provide a toner that can prevent retransfer under a wide range of transfer current conditions and obtain high transfer efficiency.
[0021]
It is a further object of the present invention to provide a toner in which no charging abnormality or image defect occurs due to contamination of a member pressed against the electrostatic latent image carrier, or these phenomena are suppressed.
[0022]
[Means for Solving the Problems]
  The present invention is a toner having toner particles containing at least a binder resin and a colorant, an inorganic fine powder, and a hydrotalcite compound, and the value of the shape factor SF-1 measured by an image analyzer of the toner is 100. ~ 160 and the value of SF-2 is 100 ~ 140,
  The acid value of the binder resin is 1.5 to 17 mg KOH / g.The
  The toner exhibits negative chargeabilityThis invention relates to a toner.
[0023]
Furthermore, the present invention relates to a toner characterized in that the value of the shape factor SF-1 measured by the toner image analyzer is 100 to 150 and the value of SF-2 is 100 to 140.
[0024]
Further, according to the present invention, the value of the shape factor SF-1 measured by the toner image analyzer is 110 to 160, the value of SF-2 is 115 to 140, and 100 from the value of the shape factor SF-2. The present invention relates to a toner characterized in that a ratio B / A between a value B obtained by subtracting 1 and a value A obtained by subtracting 100 from the value of SF-1 is 1.0 or less.
[0025]
Furthermore, the present invention relates to a toner characterized in that the inorganic fine powder contained in the toner is one or more inorganic fine powders selected from titania, alumina, silica, or double oxides thereof.
[0026]
Furthermore, the present invention relates to a toner characterized in that the inorganic fine powder contained in the toner is hydrophobized.
[0027]
Furthermore, the present invention relates to a toner characterized in that the hydrophobic inorganic fine powder contained in the toner is treated with at least silicone oil.
[0028]
Furthermore, the present invention relates to a toner characterized in that the toner exhibits negative chargeability.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors are a toner having toner particles containing at least a binder resin and a colorant, an inorganic fine powder, and a hydrotalcite compound, and a value of the shape factor SF-1 measured by an image analysis apparatus of the toner. It was found that the object of the present invention can be achieved to a high degree by using a toner having a value of 100 to 160 and an SF-2 value of 100 to 140.
[0031]
Although details are unknown, it has been clarified that by adding a hydrotalcite compound externally to a toner having a defined shape, it is excellent in charging stability and transferability.
[0032]
The hydrotalcite compound of the present invention is a non-stoichiometric compound represented by the following general formula (1).
[0033]
[Expression 1]
M²⁺ _y  M³⁺ _x(OH)₂A^n- _{(x / n)}・ MH₂O (1)
(However, 0 <x ≦ 0.5, y = 1−x, m ≧ 0, M²⁺: Divalent metal ion selected from at least Mg, Zn, Ca, Ba, Ni, Sr, Cu, Fe, M³⁺: Trivalent metal ion selected from at least Al, B, Ga, Fe, Co, and In, A^n-: N-valent anion. )
[0034]
The divalent or trivalent metal may be a solid solution containing at least one kind and containing a plurality of different elements. Moreover, you may contain a trace amount of monovalent metals.
[0035]
Hydrotalcite A used in the present invention^n-As (n-valent anion), CO_Three ^2-, OH^-, Cl^-, I^-, F^-, Br^-, SO_Four ^2-, HCO_Three ^-, CH_ThreeCOO^-, NO_Three ^-And may be single or plural.
[0036]
The specific surface area of the hydrotalcites used in the present invention is 1.0 m.²/ G or more, more preferably 5.0 m²/ G or more is preferable.
[0037]
The specific surface area was calculated according to the BET method by using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics Co., Ltd.) to adsorb nitrogen gas on the sample surface and calculating the specific surface area using the BET multipoint method.
[0038]
The hydrotalcite used in the present invention is preferably hydrophobized with a surface treatment agent in order to stabilize the environment. As the surface treatment agent, higher fatty acids, coupling agents, esters, oils such as silicone oil, and the like can be used.
[0039]
The amount of the hydrotalcite compound added to the toner is 0.03 to 3 parts by weight (more preferably 0.1 to 1.0 part by weight) with respect to 100 parts by weight of the toner. When the addition amount is less than 0.03 parts by weight, the effect of the present invention is insufficient, and when it exceeds 3 parts by weight, the environmental stability becomes insufficient.
[0040]
In addition, the hydrotalcite compound of the present invention is preferably one represented by the general formula (2) in which the divalent metal ion is Mg and the trivalent metal ion is Al.
[0041]
[Expression 2]
Mg_yAl_x(OH)₂A^n- _{(x / n)}・ MH₂O (2)
(However, 0 <x ≦ 0.5, y = 1−x, m ≧ 0, A^n-: N-valent anion. )
[0042]
Furthermore, in the present invention, the value of the shape factor SF-1 measured by the toner image analyzer is 100 to 160, more preferably 110 to 150, and the value of SF-2 is 100 to 140, more preferably 115. Furthermore, the ratio B / A of the value B obtained by subtracting 100 from the value of the shape factor SF-2 of the toner and the value A obtained by subtracting 100 from the value of SF-1 is 1.0 or less. It is characterized by that.
[0043]
By specifying the shape factor of the toner as described above and containing the hydrotalcite compound of the present invention, the present inventors can achieve further improvement in charging stability and transferability, and dot reproducibility. I found it to be excellent.
[0044]
In the present invention, SF-1 and SF-2 indicating shape factors are, for example, randomly sampled 100 toner images of 2 μm or more magnified 1000 times using FE-SEM (S-800) manufactured by Hitachi, Ltd. Then, the image information is introduced into, for example, an image analysis apparatus (Luzex III) manufactured by Nicole via an interface, and the values obtained by calculation are defined as shape factors SF-1 and SF-2. .
[0045]
[Equation 3]

(In the formula, MXLNG represents the absolute maximum length of the particle, PERIME represents the perimeter of the particle, and AREA represents the projected area of the particle.)
[0046]
The shape factor SF-1 indicates the degree of roundness of the toner particles, and the shape factor SF-2 indicates the degree of unevenness of the toner particles.
[0047]
When the toner shape factors SF-1 and SF-2 are close to 100, the transfer property is excellent. However, when the toner shape factor SF-1 is 110 or less or when the toner spherical coefficient SF-2 is 110 or less. When the ratio B / A between the value B obtained by subtracting 100 from the value of SF-2 and the value A obtained by subtracting 100 from the value of SF-1 exceeds 1.0, generally a cleaning failure occurs. When the toner shape factor SF-1 exceeds 160, the toner moves away from the spherical shape and approaches an indeterminate shape. The toner is easily crushed in the developing device, the particle size distribution is changed, and the charge amount distribution is likely to be broad. Fog and reversal fog are likely to occur. In addition, if SF-2 exceeds 140, the transfer efficiency of the toner image at the time of transfer from the electrostatic latent image carrier (photoreceptor) to the transfer material will be reduced, and the transfer of characters and line images may be lost. . At this time, a toner produced by a pulverization method is preferably used.
[0048]
Further, B / A represents the slope of a straight line passing through the origin in FIG. 4, and preferably this value is 0.2 to 0.9 (more preferably 0.35 to 0.85). It is preferable in order to improve transferability while maintaining. Further, by having the inorganic fine powder and the hydrotalcite compound on the toner particle surface, the transfer efficiency can be improved and the text and line images can be easily transferred and skipped.
[0049]
In the present invention, in addition to the above effects, by defining the toner shape as described above, it is possible to densely fill the toner image, and the resulting image has improved smoothness and a quality image.
[0050]
In the present invention, the toner particles preferably have a weight average diameter of 4 μm to 8 μm in order to faithfully develop finer latent image dots for higher image quality. For toner particles having a weight average diameter of less than 4 μm, a large amount of toner remains on the photosensitive member due to a decrease in transfer efficiency, and moreover, it tends to cause uneven image unevenness due to fog and transfer failure. It is not preferable for the toner to be used. Further, when the weight average diameter of the toner particles exceeds 8 μm, characters and line images are likely to be scattered.
[0051]
For the average particle size and particle size distribution of the toner, a Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Inc.) is used. And 1% NaCl aqueous solution is prepared using 1st grade sodium chloride as the electrolyte. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample is suspended is subjected to a dispersion process for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of toners of 2 μm or more are measured using the Coulter counter TA-II with a 100 μm aperture as an aperture. Volume distribution and number distribution were calculated. Then, the volume-based weight average particle diameter (D_Four), The number average length average particle diameter (D₁)
[0052]
Examples of the binder resin used in the present invention include styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and a homopolymer of a substituted product thereof; styrene-p-chlorostyrene copolymer, styrene. -Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Styrene copolymers such as coalesced; poly Vinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral Terpene resin, coumarone indene resin, petroleum resin and the like can be used. A cross-linked styrene resin is also a preferable binder resin.
[0053]
Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid. Monocarboxylic acid having a double bond such as acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide and the like; for example, maleic acid, butyl maleate , Dicarboxylic acids having a double bond such as methyl maleate, dimethyl maleate, and the like; and substituted products thereof; for example, vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate, and the like, such as ethylene, propylene Ethylene-based olefins such as vinyl and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; and vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl monomers are used alone or in combination. Here, as the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate, ethylene glycol A carboxylic acid ester having two double bonds, such as dimethacrylate, 1,3-butanediol dimethacrylate; a divinyl compound such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and three or more vinyl groups. Can be used alone or as a mixture.
[0054]
The binder resin used in the toner of the present invention preferably has an acid value. Since the resin has an acid value, in the combination with the hydrotalcite compound of the present invention, the rise of charge is faster and charge stability can be achieved to a higher degree. The acid value of the binder resin is preferably 1 to 35 mgKOH / g (more preferably 5 to 25 mgKOH / g). If it is less than 1 mg KOH / g, the rise of charge is poor, and if it exceeds 35 mg KOH / g, the environmental stability is poor.
[0055]
Examples of the release agent usable in the present invention include petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon waxes and derivatives thereof by Fischer-Tropsch method, and polyethylene. Polyolefin waxes and derivatives thereof, natural waxes such as carnauba wax and candelilla wax and derivatives thereof, and the derivatives include oxides, block copolymers with vinyl monomers, and graft modified products. Higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid, or compounds thereof, acid amides, esters, ketones, hydrogenated castor oil and derivatives thereof, plant waxes, animal waxes, etc. endothermic peaks in differential thermal analysis of 60 ° C. or higher What has 120 degrees C or less is preferable.
[0056]
Among these, it is particularly preferable in the present invention that the compound having an endothermic peak in a differential thermal analysis at 60 ° C. or more and 120 ° C. or less is a polyolefin, a hydrocarbon wax by petroleum Fischer-Tropsch method, a petroleum wax, or a higher alcohol.
[0057]
When a certain compound described above is used, the “retransfer” prevention effect is further enhanced.
[0058]
These compounds are considered to have a relatively low polarity and stabilize the charging of the toner base.
[0059]
In the toner of the present invention, it is preferable to use a charge control agent blended with toner particles (internal addition) or mixed with toner particles (external addition). The charge control agent makes it possible to control the optimum charge amount according to the development system. In particular, in the present invention, the balance between the particle size distribution and the charge amount can be further stabilized. The following substances are used for controlling the toner to be negatively charged.
[0060]
For example, organometallic complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.
[0061]
In addition, the following substances can be controlled to be positively charged.
[0062]
Modified products by nigrosine and fatty acid metal salts; oniums such as quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and phosphonium salts which are analogs thereof Salts and their lake pigments, triphenylmethane dyes and their lake pigments (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, Russian compounds, metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexyltin volley Diorgano tin borate such like; can be used in combination singly or two or more kinds.
[0063]
It is in the case of negatively charged toner that the effects of the present invention can be effectively exhibited, that is, charging stability and transferability can be improved efficiently.
[0064]
In the case of a negatively chargeable toner, the hydrotalcites of the present invention have a polarity opposite to that of the toner, and the presence of the hydrotalcite on the toner surface increases the charge like a microcarrier when the charge is attenuated. When the toner is charged up, the toner is neutralized to make the toner charge uniform.
[0065]
Although the positively chargeable toner has an effect of supplementing the charge, the stability is inferior to the combination with the negatively chargeable toner.
[0066]
The charge control agent described above is preferably used in the form of fine particles. In this case, the number average particle diameter of these charge control agents is particularly preferably 4 μm or less, and more preferably 3 μm or less. When these charge control agents are internally added to the toner, it is preferable to use 0.1 to 20 parts by mass, particularly 0.2 to 10 parts by mass with respect to 100 parts by mass of the binder resin.
[0067]
As the colorant used in the toner of the present invention, a black colorant that is toned in black using carbon black, a magnetic material, and the following yellow / magenta / cyan colorant is used.
[0068]
As the yellow colorant, compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 168, 174, 176, 180, 181 and 191 are preferably used.
[0069]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. 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.
[0070]
As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably.
[0071]
These colorants can be used alone or in combination and further in the form of a solid solution. The colorant of the present invention is selected from the viewpoints of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner. The colorant is added in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the resin.
[0072]
When a magnetic material is used as the black colorant, it is used by adding 30 to 200 parts by mass with respect to 100 parts by mass of the resin, unlike other colorants.
[0073]
Examples of the magnetic material include metal oxides containing elements such as iron, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. Of these, those containing iron oxide as a main component, such as triiron tetroxide and γ-iron oxide, are preferable. Further, from the viewpoint of toner chargeability control, other metal elements such as silicon element or aluminum element may be contained. These magnetic particles preferably have a BET specific surface area of 2 to 3 m by a nitrogen adsorption method.²/ G, especially 3 to 28m²/ G, and magnetic powder having a Mohs hardness of 5 to 7 is preferred.
[0074]
The shape of the magnetic body includes octahedrons, hexahedrons, spheres, needles, scales, and the like, but those with less anisotropy such as octahedrons, hexahedrons, spheres, and irregular shapes increase the image density. preferable. The average particle size of the magnetic material is preferably 0.05 to 1.0 μm, more preferably 0.1 to 0.6 μm, and further preferably 0.1 to 0.4 μm.
[0075]
The amount of magnetic material is 30 to 200 parts by mass, preferably 40 to 200 parts by mass, and more preferably 50 to 150 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 30 parts by mass, the developer using magnetic force for toner conveyance tends to have insufficient conveyance and unevenness in the developer layer on the developer carrier, resulting in image unevenness, and further increase in developer tribo. The image density tends to decrease due to the above. On the other hand, when the amount exceeds 200 parts by mass, there is a tendency that a problem occurs in the fixing property.
[0076]
Further, known inorganic fine powders contained in the toner of the present invention are used. Among the inorganic fine powders, among silica, alumina, titania or a double oxide thereof for improving charging stability, developability, fluidity and storage stability. Is preferably selected from. Further, silica is more preferable. For example, the silica can be either a so-called dry method produced by vapor phase oxidation of silicon halide or alkoxide, or dry silica called fumed silica and so-called wet silica produced from alkoxide, water glass, etc. There are few silanol groups on the surface and in the silica fine powder, and Na₂O, SO₃ ^2-For example, dry silica with less production residue is preferred. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.
[0077]
The inorganic fine powder used in the present invention has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.²/ G or more, especially 50-400m²/ G range gives good results, 0.1 to 8 parts by weight of silica fine powder, preferably 0.5 to 5 parts by weight, more preferably more than 1.0 to 100 parts by weight of toner. It is particularly good to use up to 3.0 parts by weight.
Yes.
[0078]
In addition, the inorganic fine powder used in the present invention has a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, and a functional group as necessary for the purpose of hydrophobization and chargeability control. It is possible and preferable to treat with a treating agent such as a silane coupling agent, an organic silicon compound, an organic titanium compound, etc. or in combination with various treating agents.
[0079]
In the present invention, in addition to the inorganic fine powder and the hydrotalcite compound, the primary particle size is more than 30 nm (preferably the specific surface area is 50 m in order to improve the cleaning property.²/ G), more preferably 50 nm or more (preferably a specific surface area of 30 m)²It is also one of preferred modes to add inorganic or organic fine particles close to spherical shape (less than / g). For example, spherical silica particles, spherical polymethylsilsesquioxane particles, spherical resin particles and the like are preferably used.
[0080]
In the toner of the present invention, other additives, such as a lubricant powder such as Teflon powder, zinc stearate powder, polyvinylidene fluoride powder, cerium oxide powder, silicon carbide powder, titanium, within a range that does not have a substantial adverse effect. Abrasives such as strontium acid powder; fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder; anti-caking agents or conductivity-imparting agents such as carbon black powder, zinc oxide powder and tin oxide powder; A small amount of polar organic fine particles and inorganic fine particles can be used as a developability improver.
[0081]
For producing the toner according to the present invention, a known method is used. For example, a binder resin, a wax, a metal salt or a metal complex, a pigment as a colorant, a dye, or a magnetic material, and if necessary charged. Control agents, other additives, etc. are thoroughly mixed with a mixer such as a Henschel mixer or ball mill, and then melt-kneaded using a heat kneader such as a heating roll, kneader or extruder to make the resins compatible with each other. Disperse or dissolve the metal compound, pigment, dye, and magnetic substance in the container, cool and solidify, grind, classify and surface-treat to obtain toner particles, and add and mix the inorganic fine powder and hydrotalcite compound. Thus, the toner according to the present invention can be obtained. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.
[0082]
In order to achieve the specific circularity distribution and particle size distribution of the toner of the present invention, the toner may be pulverized (classified as necessary) by a method using a known pulverizer such as a mechanical impact type or a jet type. In order to obtain a sharper circularity distribution, it is preferable to pulverize with heat or to add a mechanical impact in an auxiliary manner.
[0083]
In addition, a hot water bath method in which finely pulverized (classified as necessary) toner particles are dispersed in hot water or a method in which the toner particles pass through a hot air stream may be used. In addition, the method of applying treatment by mechanical impact force is most preferable in terms of image characteristics and productivity.
[0084]
As a means for applying mechanical impact force, for example, a method using a mechanical impact type pulverizer such as a kryptron system manufactured by Kawasaki Heavy Industries, Ltd. or a turbo mill manufactured by Turbo Industry Co., a mechano-fusion system manufactured by Hosokawa Micron Co., Ltd. or Nara Machinery Co., Ltd. There is a method of applying a mechanical impact force to the toner by a force such as a compressive force or a frictional force by pressing the toner against the inside of the casing by a centrifugal force with a blade rotating at high speed, as in a device such as a hybridization system manufactured by the manufacturer.
[0085]
Further, in order to achieve the specific circularity distribution and particle size distribution of the toner of the present invention, the molten mixture is atomized into the air using a disk or a multi-fluid nozzle described in JP-B-56-13945, etc. A method of directly producing toner using a suspension polymerization method described in JP-B-36-10231, JP-A-59-53856, and JP-A-59-61842, A method of directly producing a toner using an aqueous organic solvent that is soluble in the monomer and insoluble in the polymer, or a direct toner using an aqueous organic solvent that is soluble in the monomer and insoluble in the polymer It is possible to produce a toner using a dispersion polymerization method for producing a toner or an emulsion polymerization method represented by a soap-free polymerization method for producing a toner by direct polymerization in the presence of a water-soluble polar polymerization initiator.
[0086]
The present invention is effective when the surface of the image carrier is mainly composed of a polymer binder. For example, when a protective film mainly comprising a resin is provided on an inorganic image carrier such as selenium or amorphous silicon, or as a charge transport layer of a function-separated organic image carrier, a surface layer made of a charge transport material and a resin In some cases, the protective layer as described above may be further provided thereon. As a means for imparting releasability to such a surface layer, (1) a resin having a low surface energy is used for the resin constituting the film, and (2) an additive that imparts water repellency and lipophilicity. And (3) a material having high releasability is dispersed in powder form. The example of (1) is achieved by introducing a fluorine-containing group, a silicon-containing group or the like into the resin structure. As (2), a surfactant or the like may be used as an additive. Examples of (3) include compounds containing fluorine atoms, that is, powders such as polytetrafluoroethylene, polyvinylidene fluoride, and carbon fluoride. Of these, polytetrafluoroethylene is particularly preferred. In the present invention, it is particularly preferable to disperse the releasable powder such as the fluorine-containing resin (3) in the outermost surface layer.
[0087]
By these means, the contact angle of water on the surface of the image carrier can be 85 degrees or more (preferably 90 degrees or more). If it is less than 85 degrees, the toner and the toner carrier are likely to deteriorate due to durability.
[0088]
In order to contain these powders on the surface, a layer in which the powder is dispersed in a binder resin is provided on the outermost surface of the image carrier, or an organic image carrier originally composed mainly of a resin In this case, the powder may be dispersed in the uppermost layer without newly providing a surface layer.
[0089]
The amount of the powder added to the surface layer is preferably 1 to 60% by mass, and more preferably 2 to 50% by mass with respect to the total mass of the surface layer. If the amount is less than 1% by mass, the effect of improving the durability of the toner and the toner carrier is insufficient. If the amount exceeds 60% by mass, the strength of the film is reduced and the amount of incident light on the image carrier is significantly reduced. Therefore, it is not preferable.
[0090]
The present invention is particularly effective in the case of the direct charging method in which the charging means makes the charging member contact the image carrier. Compared with corona discharge or the like in which the charging means does not come into contact with the image carrier, the load on the surface of the image carrier is large, so that the improvement effect is remarkable in terms of the life of the image carrier, which is one of the preferred applications.
[0091]
One preferred embodiment of the image carrier used in the present invention will be described below.
[0092]
As the conductive substrate, cylinders such as metals such as aluminum and stainless steel, plastics having a coating layer of aluminum alloy, indium oxide-tin oxide alloy, paper impregnated with conductive particles, plastics, plastics having a conductive polymer, etc. Cylinder and film are used.
[0093]
On these conductive substrates, the purpose is to improve the adhesion of the photosensitive layer, improve the coatability, protect the substrate, cover defects on the substrate, improve the charge injection from the substrate, and protect the photosensitive layer from electrical breakdown. An undercoat layer may be provided. Undercoat layer is polyvinyl alcohol, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymer nylon, glue, gelatin, polyurethane , Formed of a material such as aluminum oxide. The film thickness is usually about 0.1 to 10 μm, preferably about 0.1 to 3 μm.
[0094]
The charge generation layer is composed of azo pigments, phthalocyanine pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, squarylium dyes, pyrylium salts, thiopyrylium salts, triphenylmethane dyes, selenium, amorphous silicon, etc. A charge generating substance such as an inorganic substance is dispersed in a suitable binder and formed by coating or vapor deposition. The binder can be selected from a wide range of binder resins, such as polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacrylic resin, phenol resin, silicone resin, epoxy resin, vinyl acetate resin, etc. Is mentioned. The amount of the binder contained in the charge generation layer is selected to be 80% by mass or less, preferably 0 to 40% by mass. The thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably 0.05 to 2 μm.
[0095]
The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transport layer is formed by dissolving a charge transport material in a solvent together with a binder resin as required, and coating, and the film thickness is generally 5 to 40 μm. Examples of charge transport materials include polycyclic aromatic compounds having a structure such as biphenylene, anthracene, pyrene, and phenanthrene in the main chain or side chain, nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole, and pyrazoline, hydrazone compounds, Examples include styryl compounds, selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide.
[0096]
In addition, binder resins for dispersing these charge transport materials include polycarbonate resins, polyester resins, polymethacrylic acid esters, polystyrene resins, acrylic resins, polyamide resins and other organic materials such as poly-N-vinylcarbazole and polyvinylanthracene. A photoconductive polymer etc. are mentioned.
[0097]
Moreover, you may provide a protective layer as a surface layer. As the resin for the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent for these resins may be used alone or in combination of two or more.
[0098]
Moreover, you may disperse | distribute electroconductive fine particles in resin of a protective layer. Examples of the conductive fine particles include metals, metal oxides, and the like, and preferably zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide-coated titanium oxide, tin-coated indium oxide, There are ultrafine particles such as antimony-coated tin oxide and zirconium oxide. These may be used alone or in combination of two or more. In general, when particles are dispersed in a protective layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of incident light in order to prevent scattering of incident light by the dispersed particles, and the particles are dispersed in the protective layer in the present invention. The particle size of the conductive and insulating particles is preferably 0.5 μm or less. Moreover, 2-90 mass% is preferable with respect to the protective layer total mass, and, as for content in a protective layer, 5-80 mass% is more preferable. The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 7 μm.
[0099]
The surface layer can be applied by spray coating, beam coating or penetration (dipping) coating of the resin dispersion.
[0100]
Next, the contact transfer process applicable to the image forming method using the toner of the present invention will be specifically described.
[0101]
The contact transfer process is to electrostatically transfer the developed image to the transfer material while contacting the transfer means via the transfer material with the electrostatic charge image carrier or intermediate transfer body. The pressure is preferably 2.9 N / m (3 g / cm) or more, more preferably 19.6 N / m (20 g / cm) or more. If the linear pressure as the contact pressure is less than 2.9 N / m (3 g / cm), it is not preferable because transfer of the transfer material and transfer failure are likely to occur.
[0102]
As the transfer means in the contact transfer process, an apparatus having a transfer roller or a transfer belt is used. The transfer roller 114 shown in FIG. 5 includes at least a cored bar 114a and a conductive elastic layer 114b. The conductive elastic layer has a volume resistance of 10 such as urethane or EPDM in which a conductive material such as carbon is dispersed.⁶-10^TenIt is made of an elastic body of about Ωcm.
[0103]
The present invention is particularly effectively used in an image forming apparatus in which the surface of an electrostatic latent image carrier (photoconductor) is an organic compound. That is, when the organic compound forms the surface layer of the photoconductor, it has better adhesion to the binder resin contained in the toner particles than other photoconductors using inorganic materials, and transferability is further reduced. This is because they tend to.
[0104]
Examples of the surface material of the photoreceptor according to the present invention include, but are not limited to, silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene, polyethylene terephthalate, and polycarbonate. Alternatively, other monomers or copolymers and blends between the aforementioned binder resins can also be used.
[0105]
The present invention is particularly effectively used for an image forming apparatus having a small diameter photoconductor having a diameter of 50 mm or less. That is, in the case of a small-diameter photoconductor, the curvature with respect to the same linear pressure is large, and pressure concentration tends to occur at the contact portion. Although the belt photoreceptor is considered to have the same phenomenon, the present invention is also effective for an image forming apparatus having a radius of curvature of 25 mm or less at the transfer portion.
[0106]
In addition, the toner of the present invention is used by setting a member that regulates the toner on the toner carrier so that the closest gap between the image carrier and the toner carrier is wider than the toner layer thickness on the toner carrier. It is particularly preferable from the viewpoint of uniform charging of the toner that the member for regulating the magnetic toner on the toner carrier is regulated by an elastic member that is in contact with the toner carrier via the toner.
[0107]
The surface roughness of the toner carrier used in the present invention is preferably in the range of 0.2 to 3.5 μm in terms of JIS centerline average roughness (Ra).
[0108]
If Ra is less than 0.2 μm, the charge amount on the toner carrying member becomes high, and the developability becomes insufficient. When Ra exceeds 3.5 μm, unevenness occurs in the toner coat layer on the toner carrier, resulting in uneven density on the image. More preferably, it is in the range of 0.5 to 3.0 μm.
[0109]
Further, since the magnetic toner of the present invention has a high charging capability, it is desirable to control the total charge amount of the toner during development. Conductive fine particles and / or a lubricant are dispersed on the surface of the toner carrier according to the present invention. It is preferable that it is covered with a resin layer.
[0110]
As the conductive fine particles contained in the resin layer covering the surface of the toner carrier, conductive metal oxides and metal double oxides such as carbon black, graphite, and conductive zinc oxide are used alone or in combination of two or more. It is done. Examples of the resin in which the conductive fine particles are dispersed include phenolic resins, epoxy resins, polyamide resins, polyester resins, polycarbonate resins, polyolefin resins, silicone resins, fluorine resins, styrene resins, Known resins such as acrylic resins are used.
[0111]
In particular, a thermosetting or photocurable resin is preferable.
[0112]
In the case of using the one-component development method in the present invention, in order to obtain high image quality, the layer thickness is smaller than the closest distance (between S and D) of the toner carrier-latent image carrier on the toner carrier, It is preferable to develop in a development process in which magnetic toner is applied and development is performed by applying an alternating electric field.
[0113]
In the present invention, it is preferable from the viewpoint of environmental conservation that the charging member is in contact with the photoreceptor so that ozone is not generated.
[0114]
As a preferable process condition when using a charging roller, when a contact pressure of the roller is 5 to 500 g / cm and an AC voltage is superimposed on a DC voltage, AC voltage = 0.5 to 5 kVpp, AC Frequency = 50 to 5 kHz, DC voltage = ± 0.2 to ± 5 kV.
[0115]
Other charging means include a method using a charging blade and a method using a conductive brush. These contact charging means are effective in that a high voltage is not required and generation of ozone is reduced.
[0116]
The material of the charging roller and charging blade as the contact charging means is preferably conductive rubber, and a release coating may be provided on the surface thereof. As the releasable coating, nylon resin, PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride), and fluorine acrylic resin are applicable.
[0117]
Next, a preferred embodiment of the image forming method of the present invention will be specifically described with reference to the drawings.
[0118]
In FIG. 1, reference numeral 100 denotes an electrostatic latent image carrier (photoconductor), which is provided with a primary charging member 117, a developing device 140, a transfer unit 114, a cleaner 116, a registration roller 124, and the like. By applying a bias to the primary charging member 117 that is in contact with the electrostatic latent image carrier 100, the electrostatic latent image carrier 100 is uniformly primary charged. Then, an electrostatic latent image is formed by irradiating and exposing the latent image carrier 100 with the laser beam 123 by the laser generator 121. As shown in FIG. 2, the developing device 140 is adjacent to the latent image carrier 100 and is a toner carrier (developing sleeve) 102 in which a coating layer is provided on a cylindrical base made of a nonmagnetic metal such as aluminum or stainless steel. The gap between the latent image carrier 100 and the toner carrier 102 is maintained constant by a toner carrier / latent image carrier gap holding member (not shown). Further, a stirring bar 141 is disposed in the developing device, and a magnet roller 104 having a plurality of magnetic poles is fixed and disposed concentrically with the toner carrier 102 in the developing sleeve, and the toner carrier 102 rotates. Is possible. The magnet roller 104 is provided with a plurality of magnetic poles as shown in FIG.₁Is development, N₁Is the toner amount regulation, S₂Is the toner uptake / conveyance, N₂Affects the prevention of toner blowout. A contact blade 103 is provided as a member for regulating the amount of magnetic toner that adheres to the toner carrier 102 and is conveyed, and controls the amount of toner conveyed to the toner carrier 102. In the development region, a development bias is applied between the latent image carrier 100 and the toner carrier 102, and the toner on the toner carrier flies over the latent image carrier 100 in accordance with the electrostatic latent image and becomes a visible image. Become.
[0119]
【Example】
Hereinafter, the present invention will be specifically described with reference to production examples and examples, but this does not limit the present invention in any way. In addition, all the parts in the following mixing | blending are a mass part.
[0120]

[0121]
The above materials are mixed in a blender, melt kneaded with a biaxial extruder heated to 110 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, and the coarsely pulverized product is finely pulverized with a mechanical pulverizer. The finely pulverized product is strictly classified by a multi-division classifier using the Coanda effect, and then an impact surface treatment device (treatment temperature 60 ° C., rotary treatment blade peripheral speed 100 m / sec.) Is used to produce magnetic toner particles (1 )
[0122]
Next, 1.2 parts of dry silica having a primary particle size of 12 nm hydrophobized with hexamethyldisilazane and silicone oil and hydrotalcite [Mg] to 100 parts of the obtained magnetic toner particles (1)._0.72Al_0.28(OH)₂(CO_Three)_0.14・ 0.54H₂O: BET specific surface area 10 m²/ G] 0.3 parts was added and mixed with a mixer to obtain magnetic toner 1. The obtained magnetic toner 1 had a weight average particle diameter of 6.9 μm, SF-1 of 120, and SF-2 of 115. Table 1 shows other physical properties of the magnetic toner 1 obtained.
[0123]
<Evaluation method>
(Photoreceptor Production Example 1)
As the photoreceptor, an Al cylinder having a diameter of 30 mm was used as a base. To this, layers having a structure as shown in FIG. 3 were sequentially laminated by dip coating to produce a photoreceptor.
[0124]
(1) Conductive coating layer: mainly composed of a powder of tin oxide and titanium oxide dispersed in a phenol resin. Film thickness 15 μm.
[0125]
(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. Film thickness 0.6 μm.
[0126]
(3) Charge generation layer: Mainly composed of an azo pigment having absorption in a long wavelength region dispersed in a butyral resin. Film thickness 0.6 μm.
[0127]
(4) Charge transport layer: Mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 by the Oswald viscosity method) at a mass ratio of 8:10, and polytetrafluoroethylene powder ( 3% by mass with respect to the total solid content was added and dispersed uniformly. Film thickness 15 μm. The contact angle with water was 87 degrees.
[0128]
Note that pure water was used for measurement of the contact angle, and Kyowa Interface Science Co., Ltd., contact angle meter CA-X type was used as the apparatus.
[0129]
As the image forming apparatus, an apparatus generally shown in FIG. 1 was used.
[0130]
An organic photoreceptor (OPC) drum (Photoconductor Production Example 1) was used as the electrostatic latent image carrier, and the dark part potential Vd = −600V and the bright part potential VL = −200V. The gap between the photosensitive drum and the developing sleeve is set to 300 μm, and a resin layer having a layer thickness of about 7 μm and a JIS centerline average roughness (Ra) of 1.3 μm is used as a toner carrier, and the surface is a mirror surface with a diameter of 20φ. A developing sleeve formed on an aluminum cylinder is used, a developing magnetic pole is 95 mT (950 gauss), and a urethane rubber blade with a thickness of 1.0 mm and a free length of 10 mm as a toner regulating member is 14.7 N / m (15 g / cm). It was made to contact by the linear pressure of.
100 parts of phenolic resin
90 parts of graphite (particle size approx. 7μm)
10 parts of carbon black
[0131]
Next, a DC bias component Vdc = −400V as a developing bias, and an overlapping AC bias component V_PP= 1600 V, f = 2000 Hz was used. The peripheral speed of the developing sleeve was 100% (100 mm / sec) in the forward direction with respect to the peripheral speed of the photosensitive member (100 mm / sec).
[0132]
Further, a transfer roller as shown in FIG. 5 (made of ethylene-propylene rubber in which conductive carbon is dispersed, the volume resistance value of the conductive elastic layer is 10).⁶Ωcm, surface rubber hardness of 22 °, diameter of 20 mm, contact pressure of 49 N / m (50 g / cm)) is constant with respect to the peripheral speed of the photoreceptor (100 mm / sec), and the transfer bias is between 2 and 20 μA. Shaking was used to evaluate the transfer latitude. Magnetic toner 1 was used as the toner, and the transfer bias was evaluated by shaking the transfer bias between 2 and 20 μA in an environment of 28.5 ° C. and 85% RH. 90g / m for transfer paper²Paper was used.
[0133]
At this time, the range in which the transfer efficiency from the photoconductor to the transfer material is 90% or more shows a high transfer efficiency in a wide range of 4 to 18 μA, and there is no skipping of characters and lines, and no scattering on the image. A good image was obtained. The transfer property was evaluated by a numerical value obtained by subtracting the Macbeth density of the tape with only the tape from the Macbeth density of what was stuck on the paper after taping off the transfer residual toner on the solid black photoconductor with a Mylar tape.
[0134]
Further, a solid white image on the left half from the center and a solid black image on the right half were endured in an environment of 30.0 ° C. and 80% RH, and the charge amount of the toner on the developing sleeve was measured.
[0135]
The evaluation results are shown in Table 2. The difference in toner charge between the solid white part and the solid black part is small in both the early and late endurance, and the difference in the charge amount of the solid white part in the early and late endurance is small, resulting in dot reproducibility without density fluctuations, fogging, and image scattering. An excellent image was obtained.
[0136]
(Example 2)
Magnetic toner particles (2) were obtained by changing the conditions of the impact surface treatment apparatus in Example 1.
[0137]
To 100 parts of the obtained magnetic toner particles (2), 1.4 parts of dry silica having a primary particle size of 11 nm hydrophobized with hexamethyldisilazane and silicone oil and 0.08 part of hydrotalcite are added, The magnetic toner 2 was obtained by mixing with a mixer. Table 1 shows other physical properties of the magnetic toner 2 obtained.
[0138]
Except that the above toner 2 was used as the toner, the image was printed using the same apparatus and conditions as in Example 1. As shown in Table 2, good results were obtained.
[0139]
(Example 3)
Magnetic toner particles (3) were obtained by changing the conditions of the impact surface treatment apparatus in Example 1.
[0140]
To 100 parts of the obtained magnetic toner particles (3), 1.4 parts of dry silica having a primary particle diameter of 11 nm hydrophobized with hexamethyldisilazane and silicone oil and 0.7 parts of hydrotalcite are added, The magnetic toner 3 was obtained by mixing with a mixer. Table 1 shows other physical properties of the magnetic toner 3 obtained.
[0141]
An image was printed using the same apparatus and conditions as in Example 1 except that the above toner 3 was used as the toner. As a result, good results were obtained as shown in Table 2.
[0142]
(Example 4)
Magnetic toner particles (4) were obtained by changing the conditions of the impact surface treatment apparatus in Example 1.
[0143]
To 100 parts of the obtained magnetic toner particles (4), 1.4 parts of dry silica having a primary particle size of 11 nm hydrophobized with hexamethyldisilazane and silicone oil and 1.2 parts of hydrotalcite are added, The magnetic toner 4 was obtained by mixing with a mixer. Table 1 shows other physical properties of the magnetic toner 4 thus obtained.
[0144]
Images were printed using the same apparatus and conditions as in Example 1 except that the above magnetic toner 4 was used as the toner. As a result, good results were obtained as shown in Table 2.
[0145]

[0146]
The above materials are mixed in a blender, melt kneaded with a biaxial extruder heated to 130 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, and the coarsely pulverized product is finely pulverized with a jet mill. The pulverized product was strictly classified by a multi-division classifier using the Coanda effect to obtain magnetic toner particles (5).
[0147]
100 parts of the obtained magnetic toner particles (5) were subjected to a hydrophobic treatment with 1.0 part of hexamethyldisilazane and dry silica having a primary particle diameter of about 16 nm (BET specific surface area of 100 m).²/ G) was added and mixed with a mixer to obtain magnetic toner 5. Table 1 shows the physical properties of the magnetic toner 5 obtained.
[0148]
An image was printed using the same apparatus and conditions as in Example 1 except that the above toner 5 was used as the toner. As a result, the transfer efficiency of 90% or more from the photoconductor to the transfer material was only 8 μA, and sufficient transfer latitude was not obtained. In addition, the image was a lot of characters and lines, and the image was very scattered.
[0149]
(Comparative Example 2)
In the same manner as in Comparative Example 1, magnetic toner particles (6) were obtained.
[0150]
To 100 parts of the obtained magnetic toner particles (6), 1.4 parts of dry silica having a primary particle diameter of 11 nm hydrophobized with hexamethyldisilazane and silicone oil and 0.7 parts of hydrotalcite are added, The magnetic toner 6 was obtained by mixing with a mixer. Table 1 shows other physical properties of the magnetic toner 6 obtained.
[0151]
An image was printed under the same apparatus and conditions as in Example 1 except that the above toner 6 was used as the toner. As a result, the transfer efficiency from the photoconductor to the transfer material of 90% or more is only 6 to 8 μA, sufficient transfer latitude cannot be obtained, and the image density is thin and poor, and the image is very scattered. Met.
[0152]
[Table 1]

[0153]
[Table 2]

[0154]
【The invention's effect】
It is excellent in charging stability, and a high-quality and sharp image can be obtained while maintaining high image density and latent image reproducibility. In particular, a wide transfer latitude can be obtained as compared with the conventional toner, and it is very effective particularly in the process of simultaneous batch transfer with a non-magnetic full-color toner.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an example of an image forming apparatus used in an embodiment of the present invention.
FIG. 2 is an enlarged view of a main part of FIG.
FIG. 3 is an explanatory diagram illustrating an example of a configuration of a photoconductor.
FIG. 4 is a diagram showing the scope of the present invention in the shape factors SF-1 and SF-2.
FIG. 5 is a diagram illustrating an example of a contact transfer member.
[Explanation of symbols]
100 Photosensitive drum
102 Developing sleeve (toner carrier)
103 Contact blade
104 Magnet roller
114 Transfer charging roller
116 Cleaner
117 Primary charging roller
140 Developer
141 Stir bar

Claims (5)

A toner having toner particles containing at least a binder resin and a colorant, an inorganic fine powder, and a hydrotalcite compound, and a shape factor SF-1 measured by an image analyzer of the toner is 100 to 160. And the value of SF-2 is 100 to 140,
The acid value of the binder resin is Ri 1.5~17mgKOH / g Der,
A toner characterized in that the toner exhibits negative chargeability .   The value B of the shape factor SF-1 measured by the toner image analyzer is 110 to 160, the value of SF-2 is 115 to 140, and the value B obtained by subtracting 100 from the value of the shape factor SF-2. 2. The toner according to claim 1, wherein a ratio B / A of the value A obtained by subtracting 100 from the value of SF-1 is 1.0 or less.   The toner according to claim 1 or 2, wherein the inorganic fine powder contained in the toner is at least one inorganic fine powder selected from titania, alumina, silica or a double oxide thereof.   The developing toner according to claim 1, wherein the inorganic fine powder contained in the toner has been subjected to a hydrophobic treatment.   The toner according to claim 4, wherein the hydrophobic inorganic fine powder contained in the toner is at least treated with silicone oil.

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